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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (C) 2007 Oracle.  All rights reserved.
  */
 
 #include <crypto/hash.h>
 #include <linux/kernel.h>
 #include <linux/bio.h>
 #include <linux/blk-cgroup.h>
 #include <linux/file.h>
 #include <linux/fs.h>
 #include <linux/pagemap.h>
 #include <linux/highmem.h>
 #include <linux/time.h>
 #include <linux/init.h>
 #include <linux/string.h>
 #include <linux/backing-dev.h>
 #include <linux/writeback.h>
 #include <linux/compat.h>
 #include <linux/xattr.h>
 #include <linux/posix_acl.h>
 #include <linux/falloc.h>
 #include <linux/slab.h>
 #include <linux/ratelimit.h>
 #include <linux/btrfs.h>
 #include <linux/blkdev.h>
 #include <linux/posix_acl_xattr.h>
 #include <linux/uio.h>
 #include <linux/magic.h>
 #include <linux/iversion.h>
 #include <linux/swap.h>
 #include <linux/migrate.h>
 #include <linux/sched/mm.h>
 #include <linux/iomap.h>
 #include <asm/unaligned.h>
 #include <linux/fsverity.h>
 #include "misc.h"
 #include "ctree.h"
 #include "disk-io.h"
 #include "transaction.h"
 #include "btrfs_inode.h"
 #include "print-tree.h"
 #include "ordered-data.h"
 #include "xattr.h"
 #include "tree-log.h"
 #include "volumes.h"
 #include "compression.h"
 #include "locking.h"
 #include "free-space-cache.h"
 #include "props.h"
 #include "qgroup.h"
 #include "delalloc-space.h"
 #include "block-group.h"
 #include "space-info.h"
 #include "zoned.h"
 #include "subpage.h"
 #include "inode-item.h"
 
 struct btrfs_iget_args {
     u64 ino;
     struct btrfs_root *root;
 };
 
 struct btrfs_dio_data {
     ssize_t submitted;
     struct extent_changeset *data_reserved;
     bool data_space_reserved;
     bool nocow_done;
 };
 
 struct btrfs_dio_private {
     struct inode *inode;
 
     /*
      * Since DIO can use anonymous page, we cannot use page_offset() to
      * grab the file offset, thus need a dedicated member for file offset.
      */
     u64 file_offset;
     /* Used for bio::bi_size */
     u32 bytes;
 
     /*
      * References to this structure. There is one reference per in-flight
      * bio plus one while we're still setting up.
      */
     refcount_t refs;
 
     /* Array of checksums */
     u8 *csums;
 
     /* This must be last */
     struct bio bio;
 };
 
 static struct bio_set btrfs_dio_bioset;
 
 struct btrfs_rename_ctx {
     /* Output field. Stores the index number of the old directory entry. */
     u64 index;
 };
 
 static const struct inode_operations btrfs_dir_inode_operations;
 static const struct inode_operations btrfs_symlink_inode_operations;
 static const struct inode_operations btrfs_special_inode_operations;
 static const struct inode_operations btrfs_file_inode_operations;
 static const struct address_space_operations btrfs_aops;
 static const struct file_operations btrfs_dir_file_operations;
 
 static struct kmem_cache *btrfs_inode_cachep;
 struct kmem_cache *btrfs_trans_handle_cachep;
 struct kmem_cache *btrfs_path_cachep;
 struct kmem_cache *btrfs_free_space_cachep;
 struct kmem_cache *btrfs_free_space_bitmap_cachep;
 
 static int btrfs_setsize(struct inode *inode, struct iattr *attr);
 static int btrfs_truncate(struct inode *inode, bool skip_writeback);
 static noinline int cow_file_range(struct btrfs_inode *inode,
                    struct page *locked_page,
                    u64 start, u64 end, int *page_started,
                    unsigned long *nr_written, int unlock,
                    u64 *done_offset);
 static struct extent_map *create_io_em(struct btrfs_inode *inode, u64 start,
                        u64 len, u64 orig_start, u64 block_start,
                        u64 block_len, u64 orig_block_len,
                        u64 ram_bytes, int compress_type,
                        int type);
 
 /*
  * btrfs_inode_lock - lock inode i_rwsem based on arguments passed
  *
  * ilock_flags can have the following bit set:
  *
  * BTRFS_ILOCK_SHARED - acquire a shared lock on the inode
  * BTRFS_ILOCK_TRY - try to acquire the lock, if fails on first attempt
  *           return -EAGAIN
  * BTRFS_ILOCK_MMAP - acquire a write lock on the i_mmap_lock
  */
 int btrfs_inode_lock(struct inode *inode, unsigned int ilock_flags)
 {
     if (ilock_flags & BTRFS_ILOCK_SHARED) {
         if (ilock_flags & BTRFS_ILOCK_TRY) {
             if (!inode_trylock_shared(inode))
                 return -EAGAIN;
             else
                 return 0;
         }
         inode_lock_shared(inode);
     } else {
         if (ilock_flags & BTRFS_ILOCK_TRY) {
             if (!inode_trylock(inode))
                 return -EAGAIN;
             else
                 return 0;
         }
         inode_lock(inode);
     }
     if (ilock_flags & BTRFS_ILOCK_MMAP)
         down_write(&BTRFS_I(inode)->i_mmap_lock);
     return 0;
 }
 
 /*
  * btrfs_inode_unlock - unock inode i_rwsem
  *
  * ilock_flags should contain the same bits set as passed to btrfs_inode_lock()
  * to decide whether the lock acquired is shared or exclusive.
  */
 void btrfs_inode_unlock(struct inode *inode, unsigned int ilock_flags)
 {
     if (ilock_flags & BTRFS_ILOCK_MMAP)
         up_write(&BTRFS_I(inode)->i_mmap_lock);
     if (ilock_flags & BTRFS_ILOCK_SHARED)
         inode_unlock_shared(inode);
     else
         inode_unlock(inode);
 }
 
 /*
  * Cleanup all submitted ordered extents in specified range to handle errors
  * from the btrfs_run_delalloc_range() callback.
  *
  * NOTE: caller must ensure that when an error happens, it can not call
  * extent_clear_unlock_delalloc() to clear both the bits EXTENT_DO_ACCOUNTING
  * and EXTENT_DELALLOC simultaneously, because that causes the reserved metadata
  * to be released, which we want to happen only when finishing the ordered
  * extent (btrfs_finish_ordered_io()).
  */
 static inline void btrfs_cleanup_ordered_extents(struct btrfs_inode *inode,
                          struct page *locked_page,
                          u64 offset, u64 bytes)
 {
     unsigned long index = offset >> PAGE_SHIFT;
     unsigned long end_index = (offset + bytes - 1) >> PAGE_SHIFT;
     u64 page_start, page_end;
     struct page *page;
 
     if (locked_page) {
         page_start = page_offset(locked_page);
         page_end = page_start + PAGE_SIZE - 1;
     }
 
     while (index <= end_index) {
         /*
          * For locked page, we will call end_extent_writepage() on it
          * in run_delalloc_range() for the error handling.  That
          * end_extent_writepage() function will call
          * btrfs_mark_ordered_io_finished() to clear page Ordered and
          * run the ordered extent accounting.
          *
          * Here we can't just clear the Ordered bit, or
          * btrfs_mark_ordered_io_finished() would skip the accounting
          * for the page range, and the ordered extent will never finish.
          */
         if (locked_page && index == (page_start >> PAGE_SHIFT)) {
             index++;
             continue;
         }
         page = find_get_page(inode->vfs_inode.i_mapping, index);
         index++;
         if (!page)
             continue;
 
         /*
          * Here we just clear all Ordered bits for every page in the
          * range, then btrfs_mark_ordered_io_finished() will handle
          * the ordered extent accounting for the range.
          */
         btrfs_page_clamp_clear_ordered(inode->root->fs_info, page,
                            offset, bytes);
         put_page(page);
     }
 
     if (locked_page) {
         /* The locked page covers the full range, nothing needs to be done */
         if (bytes + offset <= page_start + PAGE_SIZE)
             return;
         /*
          * In case this page belongs to the delalloc range being
          * instantiated then skip it, since the first page of a range is
          * going to be properly cleaned up by the caller of
          * run_delalloc_range
          */
         if (page_start >= offset && page_end <= (offset + bytes - 1)) {
             bytes = offset + bytes - page_offset(locked_page) - PAGE_SIZE;
             offset = page_offset(locked_page) + PAGE_SIZE;
         }
     }
 
     return btrfs_mark_ordered_io_finished(inode, NULL, offset, bytes, false);
 }
 
 static int btrfs_dirty_inode(struct inode *inode);
 
 static int btrfs_init_inode_security(struct btrfs_trans_handle *trans,
                      struct btrfs_new_inode_args *args)
 {
     int err;
 
     if (args->default_acl) {
         err = __btrfs_set_acl(trans, args->inode, args->default_acl,
                       ACL_TYPE_DEFAULT);
         if (err)
             return err;
     }
     if (args->acl) {
         err = __btrfs_set_acl(trans, args->inode, args->acl, ACL_TYPE_ACCESS);
         if (err)
             return err;
     }
     if (!args->default_acl && !args->acl)
         cache_no_acl(args->inode);
     return btrfs_xattr_security_init(trans, args->inode, args->dir,
                      &args->dentry->d_name);
 }
 
 /*
  * this does all the hard work for inserting an inline extent into
  * the btree.  The caller should have done a btrfs_drop_extents so that
  * no overlapping inline items exist in the btree
  */
 static int insert_inline_extent(struct btrfs_trans_handle *trans,
                 struct btrfs_path *path,
                 struct btrfs_inode *inode, bool extent_inserted,
                 size_t size, size_t compressed_size,
                 int compress_type,
                 struct page **compressed_pages,
                 bool update_i_size)
 {
     struct btrfs_root *root = inode->root;
     struct extent_buffer *leaf;
     struct page *page = NULL;
     char *kaddr;
     unsigned long ptr;
     struct btrfs_file_extent_item *ei;
     int ret;
     size_t cur_size = size;
     u64 i_size;
 
     ASSERT((compressed_size > 0 && compressed_pages) ||
            (compressed_size == 0 && !compressed_pages));
 
     if (compressed_size && compressed_pages)
         cur_size = compressed_size;
 
     if (!extent_inserted) {
         struct btrfs_key key;
         size_t datasize;
 
         key.objectid = btrfs_ino(inode);
         key.offset = 0;
         key.type = BTRFS_EXTENT_DATA_KEY;
 
         datasize = btrfs_file_extent_calc_inline_size(cur_size);
         ret = btrfs_insert_empty_item(trans, root, path, &key,
                           datasize);
         if (ret)
             goto fail;
     }
     leaf = path->nodes[0];
     ei = btrfs_item_ptr(leaf, path->slots[0],
                 struct btrfs_file_extent_item);
     btrfs_set_file_extent_generation(leaf, ei, trans->transid);
     btrfs_set_file_extent_type(leaf, ei, BTRFS_FILE_EXTENT_INLINE);
     btrfs_set_file_extent_encryption(leaf, ei, 0);
     btrfs_set_file_extent_other_encoding(leaf, ei, 0);
     btrfs_set_file_extent_ram_bytes(leaf, ei, size);
     ptr = btrfs_file_extent_inline_start(ei);
 
     if (compress_type != BTRFS_COMPRESS_NONE) {
         struct page *cpage;
         int i = 0;
         while (compressed_size > 0) {
             cpage = compressed_pages[i];
             cur_size = min_t(unsigned long, compressed_size,
                        PAGE_SIZE);
 
             kaddr = kmap_local_page(cpage);
             write_extent_buffer(leaf, kaddr, ptr, cur_size);
             kunmap_local(kaddr);
 
             i++;
             ptr += cur_size;
             compressed_size -= cur_size;
         }
         btrfs_set_file_extent_compression(leaf, ei,
                           compress_type);
     } else {
         page = find_get_page(inode->vfs_inode.i_mapping, 0);
         btrfs_set_file_extent_compression(leaf, ei, 0);
         kaddr = kmap_local_page(page);
         write_extent_buffer(leaf, kaddr, ptr, size);
         kunmap_local(kaddr);
         put_page(page);
     }
     btrfs_mark_buffer_dirty(leaf);
     btrfs_release_path(path);
 
     /*
      * We align size to sectorsize for inline extents just for simplicity
      * sake.
      */
     ret = btrfs_inode_set_file_extent_range(inode, 0,
                     ALIGN(size, root->fs_info->sectorsize));
     if (ret)
         goto fail;
 
     /*
      * We're an inline extent, so nobody can extend the file past i_size
      * without locking a page we already have locked.
      *
      * We must do any i_size and inode updates before we unlock the pages.
      * Otherwise we could end up racing with unlink.
      */
     i_size = i_size_read(&inode->vfs_inode);
     if (update_i_size && size > i_size) {
         i_size_write(&inode->vfs_inode, size);
         i_size = size;
     }
     inode->disk_i_size = i_size;
 
 fail:
     return ret;
 }
 
 
 /*
  * conditionally insert an inline extent into the file.  This
  * does the checks required to make sure the data is small enough
  * to fit as an inline extent.
  */
 static noinline int cow_file_range_inline(struct btrfs_inode *inode, u64 size,
                       size_t compressed_size,
                       int compress_type,
                       struct page **compressed_pages,
                       bool update_i_size)
 {
     struct btrfs_drop_extents_args drop_args = { 0 };
     struct btrfs_root *root = inode->root;
     struct btrfs_fs_info *fs_info = root->fs_info;
     struct btrfs_trans_handle *trans;
     u64 data_len = (compressed_size ?: size);
     int ret;
     struct btrfs_path *path;
 
     /*
      * We can create an inline extent if it ends at or beyond the current
      * i_size, is no larger than a sector (decompressed), and the (possibly
      * compressed) data fits in a leaf and the configured maximum inline
      * size.
      */
     if (size < i_size_read(&inode->vfs_inode) ||
         size > fs_info->sectorsize ||
         data_len > BTRFS_MAX_INLINE_DATA_SIZE(fs_info) ||
         data_len > fs_info->max_inline)
         return 1;
 
     path = btrfs_alloc_path();
     if (!path)
         return -ENOMEM;
 
     trans = btrfs_join_transaction(root);
     if (IS_ERR(trans)) {
         btrfs_free_path(path);
         return PTR_ERR(trans);
     }
     trans->block_rsv = &inode->block_rsv;
 
     drop_args.path = path;
     drop_args.start = 0;
     drop_args.end = fs_info->sectorsize;
     drop_args.drop_cache = true;
     drop_args.replace_extent = true;
     drop_args.extent_item_size = btrfs_file_extent_calc_inline_size(data_len);
     ret = btrfs_drop_extents(trans, root, inode, &drop_args);
     if (ret) {
         btrfs_abort_transaction(trans, ret);
         goto out;
     }
 
     ret = insert_inline_extent(trans, path, inode, drop_args.extent_inserted,
                    size, compressed_size, compress_type,
                    compressed_pages, update_i_size);
     if (ret && ret != -ENOSPC) {
         btrfs_abort_transaction(trans, ret);
         goto out;
     } else if (ret == -ENOSPC) {
         ret = 1;
         goto out;
     }
 
     btrfs_update_inode_bytes(inode, size, drop_args.bytes_found);
     ret = btrfs_update_inode(trans, root, inode);
     if (ret && ret != -ENOSPC) {
         btrfs_abort_transaction(trans, ret);
         goto out;
     } else if (ret == -ENOSPC) {
         ret = 1;
         goto out;
     }
 
     btrfs_set_inode_full_sync(inode);
 out:
     /*
      * Don't forget to free the reserved space, as for inlined extent
      * it won't count as data extent, free them directly here.
      * And at reserve time, it's always aligned to page size, so
      * just free one page here.
      */
     btrfs_qgroup_free_data(inode, NULL, 0, PAGE_SIZE);
     btrfs_free_path(path);
     btrfs_end_transaction(trans);
     return ret;
 }
 
 struct async_extent {
     u64 start;
     u64 ram_size;
     u64 compressed_size;
     struct page **pages;
     unsigned long nr_pages;
     int compress_type;
     struct list_head list;
 };
 
 struct async_chunk {
     struct inode *inode;
     struct page *locked_page;
     u64 start;
     u64 end;
     blk_opf_t write_flags;
     struct list_head extents;
     struct cgroup_subsys_state *blkcg_css;
     struct btrfs_work work;
     struct async_cow *async_cow;
 };
 
 struct async_cow {
     atomic_t num_chunks;
     struct async_chunk chunks[];
 };
 
 static noinline int add_async_extent(struct async_chunk *cow,
                      u64 start, u64 ram_size,
                      u64 compressed_size,
                      struct page **pages,
                      unsigned long nr_pages,
                      int compress_type)
 {
     struct async_extent *async_extent;
 
     async_extent = kmalloc(sizeof(*async_extent), GFP_NOFS);
     BUG_ON(!async_extent); /* -ENOMEM */
     async_extent->start = start;
     async_extent->ram_size = ram_size;
     async_extent->compressed_size = compressed_size;
     async_extent->pages = pages;
     async_extent->nr_pages = nr_pages;
     async_extent->compress_type = compress_type;
     list_add_tail(&async_extent->list, &cow->extents);
     return 0;
 }
 
 /*
  * Check if the inode needs to be submitted to compression, based on mount
  * options, defragmentation, properties or heuristics.
  */
 static inline int inode_need_compress(struct btrfs_inode *inode, u64 start,
                       u64 end)
 {
     struct btrfs_fs_info *fs_info = inode->root->fs_info;
 
     if (!btrfs_inode_can_compress(inode)) {
         WARN(IS_ENABLED(CONFIG_BTRFS_DEBUG),
             KERN_ERR "BTRFS: unexpected compression for ino %llu\n",
             btrfs_ino(inode));
         return 0;
     }
     /*
      * Special check for subpage.
      *
      * We lock the full page then run each delalloc range in the page, thus
      * for the following case, we will hit some subpage specific corner case:
      *
      * 0        32K     64K
      * |    |///////|   |///////|
      *      \- A        \- B
      *
      * In above case, both range A and range B will try to unlock the full
      * page [0, 64K), causing the one finished later will have page
      * unlocked already, triggering various page lock requirement BUG_ON()s.
      *
      * So here we add an artificial limit that subpage compression can only
      * if the range is fully page aligned.
      *
      * In theory we only need to ensure the first page is fully covered, but
      * the tailing partial page will be locked until the full compression
      * finishes, delaying the write of other range.
      *
      * TODO: Make btrfs_run_delalloc_range() to lock all delalloc range
      * first to prevent any submitted async extent to unlock the full page.
      * By this, we can ensure for subpage case that only the last async_cow
      * will unlock the full page.
      */
     if (fs_info->sectorsize < PAGE_SIZE) {
         if (!PAGE_ALIGNED(start) ||
             !PAGE_ALIGNED(end + 1))
             return 0;
     }
 
     /* force compress */
     if (btrfs_test_opt(fs_info, FORCE_COMPRESS))
         return 1;
     /* defrag ioctl */
     if (inode->defrag_compress)
         return 1;
     /* bad compression ratios */
     if (inode->flags & BTRFS_INODE_NOCOMPRESS)
         return 0;
     if (btrfs_test_opt(fs_info, COMPRESS) ||
         inode->flags & BTRFS_INODE_COMPRESS ||
         inode->prop_compress)
         return btrfs_compress_heuristic(&inode->vfs_inode, start, end);
     return 0;
 }
 
 static inline void inode_should_defrag(struct btrfs_inode *inode,
         u64 start, u64 end, u64 num_bytes, u32 small_write)
 {
     /* If this is a small write inside eof, kick off a defrag */
     if (num_bytes < small_write &&
         (start > 0 || end + 1 < inode->disk_i_size))
         btrfs_add_inode_defrag(NULL, inode, small_write);
 }
 
 /*
  * we create compressed extents in two phases.  The first
  * phase compresses a range of pages that have already been
  * locked (both pages and state bits are locked).
  *
  * This is done inside an ordered work queue, and the compression
  * is spread across many cpus.  The actual IO submission is step
  * two, and the ordered work queue takes care of making sure that
  * happens in the same order things were put onto the queue by
  * writepages and friends.
  *
  * If this code finds it can't get good compression, it puts an
  * entry onto the work queue to write the uncompressed bytes.  This
  * makes sure that both compressed inodes and uncompressed inodes
  * are written in the same order that the flusher thread sent them
  * down.
  */
 static noinline int compress_file_range(struct async_chunk *async_chunk)
 {
     struct inode *inode = async_chunk->inode;
     struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
     u64 blocksize = fs_info->sectorsize;
     u64 start = async_chunk->start;
     u64 end = async_chunk->end;
     u64 actual_end;
     u64 i_size;
     int ret = 0;
     struct page **pages = NULL;
     unsigned long nr_pages;
     unsigned long total_compressed = 0;
     unsigned long total_in = 0;
     int i;
     int will_compress;
     int compress_type = fs_info->compress_type;
     int compressed_extents = 0;
     int redirty = 0;
 
     inode_should_defrag(BTRFS_I(inode), start, end, end - start + 1,
             SZ_16K);
 
     /*
      * We need to save i_size before now because it could change in between
      * us evaluating the size and assigning it.  This is because we lock and
      * unlock the page in truncate and fallocate, and then modify the i_size
      * later on.
      *
      * The barriers are to emulate READ_ONCE, remove that once i_size_read
      * does that for us.
      */
     barrier();
     i_size = i_size_read(inode);
     barrier();
     actual_end = min_t(u64, i_size, end + 1);
 again:
     will_compress = 0;
     nr_pages = (end >> PAGE_SHIFT) - (start >> PAGE_SHIFT) + 1;
     nr_pages = min_t(unsigned long, nr_pages,
             BTRFS_MAX_COMPRESSED / PAGE_SIZE);
 
     /*
      * we don't want to send crud past the end of i_size through
      * compression, that's just a waste of CPU time.  So, if the
      * end of the file is before the start of our current
      * requested range of bytes, we bail out to the uncompressed
      * cleanup code that can deal with all of this.
      *
      * It isn't really the fastest way to fix things, but this is a
      * very uncommon corner.
      */
     if (actual_end <= start)
         goto cleanup_and_bail_uncompressed;
 
     total_compressed = actual_end - start;
 
     /*
      * Skip compression for a small file range(<=blocksize) that
      * isn't an inline extent, since it doesn't save disk space at all.
      */
     if (total_compressed <= blocksize &&
        (start > 0 || end + 1 < BTRFS_I(inode)->disk_i_size))
         goto cleanup_and_bail_uncompressed;
 
     /*
      * For subpage case, we require full page alignment for the sector
      * aligned range.
      * Thus we must also check against @actual_end, not just @end.
      */
     if (blocksize < PAGE_SIZE) {
         if (!PAGE_ALIGNED(start) ||
             !PAGE_ALIGNED(round_up(actual_end, blocksize)))
             goto cleanup_and_bail_uncompressed;
     }
 
     total_compressed = min_t(unsigned long, total_compressed,
             BTRFS_MAX_UNCOMPRESSED);
     total_in = 0;
     ret = 0;
 
     /*
      * we do compression for mount -o compress and when the
      * inode has not been flagged as nocompress.  This flag can
      * change at any time if we discover bad compression ratios.
      */
     if (inode_need_compress(BTRFS_I(inode), start, end)) {
         WARN_ON(pages);
         pages = kcalloc(nr_pages, sizeof(struct page *), GFP_NOFS);
         if (!pages) {
             /* just bail out to the uncompressed code */
             nr_pages = 0;
             goto cont;
         }
 
         if (BTRFS_I(inode)->defrag_compress)
             compress_type = BTRFS_I(inode)->defrag_compress;
         else if (BTRFS_I(inode)->prop_compress)
             compress_type = BTRFS_I(inode)->prop_compress;
 
         /*
          * we need to call clear_page_dirty_for_io on each
          * page in the range.  Otherwise applications with the file
          * mmap'd can wander in and change the page contents while
          * we are compressing them.
          *
          * If the compression fails for any reason, we set the pages
          * dirty again later on.
          *
          * Note that the remaining part is redirtied, the start pointer
          * has moved, the end is the original one.
          */
         if (!redirty) {
             extent_range_clear_dirty_for_io(inode, start, end);
             redirty = 1;
         }
 
         /* Compression level is applied here and only here */
         ret = btrfs_compress_pages(
             compress_type | (fs_info->compress_level << 4),
                        inode->i_mapping, start,
                        pages,
                        &nr_pages,
                        &total_in,
                        &total_compressed);
 
         if (!ret) {
             unsigned long offset = offset_in_page(total_compressed);
             struct page *page = pages[nr_pages - 1];
 
             /* zero the tail end of the last page, we might be
              * sending it down to disk
              */
             if (offset)
                 memzero_page(page, offset, PAGE_SIZE - offset);
             will_compress = 1;
         }
     }
 cont:
     /*
      * Check cow_file_range() for why we don't even try to create inline
      * extent for subpage case.
      */
     if (start == 0 && fs_info->sectorsize == PAGE_SIZE) {
         /* lets try to make an inline extent */
         if (ret || total_in < actual_end) {
             /* we didn't compress the entire range, try
              * to make an uncompressed inline extent.
              */
             ret = cow_file_range_inline(BTRFS_I(inode), actual_end,
                             0, BTRFS_COMPRESS_NONE,
                             NULL, false);
         } else {
             /* try making a compressed inline extent */
             ret = cow_file_range_inline(BTRFS_I(inode), actual_end,
                             total_compressed,
                             compress_type, pages,
                             false);
         }
         if (ret <= 0) {
             unsigned long clear_flags = EXTENT_DELALLOC |
                 EXTENT_DELALLOC_NEW | EXTENT_DEFRAG |
                 EXTENT_DO_ACCOUNTING;
             unsigned long page_error_op;
 
             page_error_op = ret < 0 ? PAGE_SET_ERROR : 0;
 
             /*
              * inline extent creation worked or returned error,
              * we don't need to create any more async work items.
              * Unlock and free up our temp pages.
              *
              * We use DO_ACCOUNTING here because we need the
              * delalloc_release_metadata to be done _after_ we drop
              * our outstanding extent for clearing delalloc for this
              * range.
              */
             extent_clear_unlock_delalloc(BTRFS_I(inode), start, end,
                              NULL,
                              clear_flags,
                              PAGE_UNLOCK |
                              PAGE_START_WRITEBACK |
                              page_error_op |
                              PAGE_END_WRITEBACK);
 
             /*
              * Ensure we only free the compressed pages if we have
              * them allocated, as we can still reach here with
              * inode_need_compress() == false.
              */
             if (pages) {
                 for (i = 0; i < nr_pages; i++) {
                     WARN_ON(pages[i]->mapping);
                     put_page(pages[i]);
                 }
                 kfree(pages);
             }
             return 0;
         }
     }
 
     if (will_compress) {
         /*
          * we aren't doing an inline extent round the compressed size
          * up to a block size boundary so the allocator does sane
          * things
          */
         total_compressed = ALIGN(total_compressed, blocksize);
 
         /*
          * one last check to make sure the compression is really a
          * win, compare the page count read with the blocks on disk,
          * compression must free at least one sector size
          */
         total_in = round_up(total_in, fs_info->sectorsize);
         if (total_compressed + blocksize <= total_in) {
             compressed_extents++;
 
             /*
              * The async work queues will take care of doing actual
              * allocation on disk for these compressed pages, and
              * will submit them to the elevator.
              */
             add_async_extent(async_chunk, start, total_in,
                     total_compressed, pages, nr_pages,
                     compress_type);
 
             if (start + total_in < end) {
                 start += total_in;
                 pages = NULL;
                 cond_resched();
                 goto again;
             }
             return compressed_extents;
         }
     }
     if (pages) {
         /*
          * the compression code ran but failed to make things smaller,
          * free any pages it allocated and our page pointer array
          */
         for (i = 0; i < nr_pages; i++) {
             WARN_ON(pages[i]->mapping);
             put_page(pages[i]);
         }
         kfree(pages);
         pages = NULL;
         total_compressed = 0;
         nr_pages = 0;
 
         /* flag the file so we don't compress in the future */
         if (!btrfs_test_opt(fs_info, FORCE_COMPRESS) &&
             !(BTRFS_I(inode)->prop_compress)) {
             BTRFS_I(inode)->flags |= BTRFS_INODE_NOCOMPRESS;
         }
     }
 cleanup_and_bail_uncompressed:
     /*
      * No compression, but we still need to write the pages in the file
      * we've been given so far.  redirty the locked page if it corresponds
      * to our extent and set things up for the async work queue to run
      * cow_file_range to do the normal delalloc dance.
      */
     if (async_chunk->locked_page &&
         (page_offset(async_chunk->locked_page) >= start &&
          page_offset(async_chunk->locked_page)) <= end) {
         __set_page_dirty_nobuffers(async_chunk->locked_page);
         /* unlocked later on in the async handlers */
     }
 
     if (redirty)
         extent_range_redirty_for_io(inode, start, end);
     add_async_extent(async_chunk, start, end - start + 1, 0, NULL, 0,
              BTRFS_COMPRESS_NONE);
     compressed_extents++;
 
     return compressed_extents;
 }
 
 static void free_async_extent_pages(struct async_extent *async_extent)
 {
     int i;
 
     if (!async_extent->pages)
         return;
 
     for (i = 0; i < async_extent->nr_pages; i++) {
         WARN_ON(async_extent->pages[i]->mapping);
         put_page(async_extent->pages[i]);
     }
     kfree(async_extent->pages);
     async_extent->nr_pages = 0;
     async_extent->pages = NULL;
 }
 
 static int submit_uncompressed_range(struct btrfs_inode *inode,
                      struct async_extent *async_extent,
                      struct page *locked_page)
 {
     u64 start = async_extent->start;
     u64 end = async_extent->start + async_extent->ram_size - 1;
     unsigned long nr_written = 0;
     int page_started = 0;
     int ret;
 
     /*
      * Call cow_file_range() to run the delalloc range directly, since we
      * won't go to NOCOW or async path again.
      *
      * Also we call cow_file_range() with @unlock_page == 0, so that we
      * can directly submit them without interruption.
      */
     ret = cow_file_range(inode, locked_page, start, end, &page_started,
                  &nr_written, 0, NULL);
     /* Inline extent inserted, page gets unlocked and everything is done */
     if (page_started) {
         ret = 0;
         goto out;
     }
     if (ret < 0) {
         btrfs_cleanup_ordered_extents(inode, locked_page, start, end - start + 1);
         if (locked_page) {
             const u64 page_start = page_offset(locked_page);
             const u64 page_end = page_start + PAGE_SIZE - 1;
 
             btrfs_page_set_error(inode->root->fs_info, locked_page,
                          page_start, PAGE_SIZE);
             set_page_writeback(locked_page);
             end_page_writeback(locked_page);
             end_extent_writepage(locked_page, ret, page_start, page_end);
             unlock_page(locked_page);
         }
         goto out;
     }
 
     ret = extent_write_locked_range(&inode->vfs_inode, start, end);
     /* All pages will be unlocked, including @locked_page */
 out:
     kfree(async_extent);
     return ret;
 }
 
 static int submit_one_async_extent(struct btrfs_inode *inode,
                    struct async_chunk *async_chunk,
                    struct async_extent *async_extent,
                    u64 *alloc_hint)
 {
     struct extent_io_tree *io_tree = &inode->io_tree;
     struct btrfs_root *root = inode->root;
     struct btrfs_fs_info *fs_info = root->fs_info;
     struct btrfs_key ins;
     struct page *locked_page = NULL;
     struct extent_map *em;
     int ret = 0;
     u64 start = async_extent->start;
     u64 end = async_extent->start + async_extent->ram_size - 1;
 
     /*
      * If async_chunk->locked_page is in the async_extent range, we need to
      * handle it.
      */
     if (async_chunk->locked_page) {
         u64 locked_page_start = page_offset(async_chunk->locked_page);
         u64 locked_page_end = locked_page_start + PAGE_SIZE - 1;
 
         if (!(start >= locked_page_end || end <= locked_page_start))
             locked_page = async_chunk->locked_page;
     }
     lock_extent(io_tree, start, end);
 
     /* We have fall back to uncompressed write */
     if (!async_extent->pages)
         return submit_uncompressed_range(inode, async_extent, locked_page);
 
     ret = btrfs_reserve_extent(root, async_extent->ram_size,
                    async_extent->compressed_size,
                    async_extent->compressed_size,
                    0, *alloc_hint, &ins, 1, 1);
     if (ret) {
         free_async_extent_pages(async_extent);
         /*
          * Here we used to try again by going back to non-compressed
          * path for ENOSPC.  But we can't reserve space even for
          * compressed size, how could it work for uncompressed size
          * which requires larger size?  So here we directly go error
          * path.
          */
         goto out_free;
     }
 
     /* Here we're doing allocation and writeback of the compressed pages */
     em = create_io_em(inode, start,
               async_extent->ram_size,   /* len */
               start,            /* orig_start */
               ins.objectid,         /* block_start */
               ins.offset,           /* block_len */
               ins.offset,           /* orig_block_len */
               async_extent->ram_size,   /* ram_bytes */
               async_extent->compress_type,
               BTRFS_ORDERED_COMPRESSED);
     if (IS_ERR(em)) {
         ret = PTR_ERR(em);
         goto out_free_reserve;
     }
     free_extent_map(em);
 
     ret = btrfs_add_ordered_extent(inode, start,        /* file_offset */
                        async_extent->ram_size,  /* num_bytes */
                        async_extent->ram_size,  /* ram_bytes */
                        ins.objectid,        /* disk_bytenr */
                        ins.offset,      /* disk_num_bytes */
                        0,           /* offset */
                        1 << BTRFS_ORDERED_COMPRESSED,
                        async_extent->compress_type);
     if (ret) {
         btrfs_drop_extent_cache(inode, start, end, 0);
         goto out_free_reserve;
     }
     btrfs_dec_block_group_reservations(fs_info, ins.objectid);
 
     /* Clear dirty, set writeback and unlock the pages. */
     extent_clear_unlock_delalloc(inode, start, end,
             NULL, EXTENT_LOCKED | EXTENT_DELALLOC,
             PAGE_UNLOCK | PAGE_START_WRITEBACK);
     if (btrfs_submit_compressed_write(inode, start, /* file_offset */
                 async_extent->ram_size, /* num_bytes */
                 ins.objectid,       /* disk_bytenr */
                 ins.offset,         /* compressed_len */
                 async_extent->pages,    /* compressed_pages */
                 async_extent->nr_pages,
                 async_chunk->write_flags,
                 async_chunk->blkcg_css, true)) {
         const u64 start = async_extent->start;
         const u64 end = start + async_extent->ram_size - 1;
 
         btrfs_writepage_endio_finish_ordered(inode, NULL, start, end, 0);
 
         extent_clear_unlock_delalloc(inode, start, end, NULL, 0,
                          PAGE_END_WRITEBACK | PAGE_SET_ERROR);
         free_async_extent_pages(async_extent);
     }
     *alloc_hint = ins.objectid + ins.offset;
     kfree(async_extent);
     return ret;
 
 out_free_reserve:
     btrfs_dec_block_group_reservations(fs_info, ins.objectid);
     btrfs_free_reserved_extent(fs_info, ins.objectid, ins.offset, 1);
 out_free:
     extent_clear_unlock_delalloc(inode, start, end,
                      NULL, EXTENT_LOCKED | EXTENT_DELALLOC |
                      EXTENT_DELALLOC_NEW |
                      EXTENT_DEFRAG | EXTENT_DO_ACCOUNTING,
                      PAGE_UNLOCK | PAGE_START_WRITEBACK |
                      PAGE_END_WRITEBACK | PAGE_SET_ERROR);
     free_async_extent_pages(async_extent);
     kfree(async_extent);
     return ret;
 }
 
 /*
  * Phase two of compressed writeback.  This is the ordered portion of the code,
  * which only gets called in the order the work was queued.  We walk all the
  * async extents created by compress_file_range and send them down to the disk.
  */
 static noinline void submit_compressed_extents(struct async_chunk *async_chunk)
 {
     struct btrfs_inode *inode = BTRFS_I(async_chunk->inode);
     struct btrfs_fs_info *fs_info = inode->root->fs_info;
     struct async_extent *async_extent;
     u64 alloc_hint = 0;
     int ret = 0;
 
     while (!list_empty(&async_chunk->extents)) {
         u64 extent_start;
         u64 ram_size;
 
         async_extent = list_entry(async_chunk->extents.next,
                       struct async_extent, list);
         list_del(&async_extent->list);
         extent_start = async_extent->start;
         ram_size = async_extent->ram_size;
 
         ret = submit_one_async_extent(inode, async_chunk, async_extent,
                           &alloc_hint);
         btrfs_debug(fs_info,
 "async extent submission failed root=%lld inode=%llu start=%llu len=%llu ret=%d",
                 inode->root->root_key.objectid,
                 btrfs_ino(inode), extent_start, ram_size, ret);
     }
 }
 
 static u64 get_extent_allocation_hint(struct btrfs_inode *inode, u64 start,
                       u64 num_bytes)
 {
     struct extent_map_tree *em_tree = &inode->extent_tree;
     struct extent_map *em;
     u64 alloc_hint = 0;
 
     read_lock(&em_tree->lock);
     em = search_extent_mapping(em_tree, start, num_bytes);
     if (em) {
         /*
          * if block start isn't an actual block number then find the
          * first block in this inode and use that as a hint.  If that
          * block is also bogus then just don't worry about it.
          */
         if (em->block_start >= EXTENT_MAP_LAST_BYTE) {
             free_extent_map(em);
             em = search_extent_mapping(em_tree, 0, 0);
             if (em && em->block_start < EXTENT_MAP_LAST_BYTE)
                 alloc_hint = em->block_start;
             if (em)
                 free_extent_map(em);
         } else {
             alloc_hint = em->block_start;
             free_extent_map(em);
         }
     }
     read_unlock(&em_tree->lock);
 
     return alloc_hint;
 }
 
 /*
  * when extent_io.c finds a delayed allocation range in the file,
  * the call backs end up in this code.  The basic idea is to
  * allocate extents on disk for the range, and create ordered data structs
  * in ram to track those extents.
  *
  * locked_page is the page that writepage had locked already.  We use
  * it to make sure we don't do extra locks or unlocks.
  *
  * *page_started is set to one if we unlock locked_page and do everything
  * required to start IO on it.  It may be clean and already done with
  * IO when we return.
  *
  * When unlock == 1, we unlock the pages in successfully allocated regions.
  * When unlock == 0, we leave them locked for writing them out.
  *
  * However, we unlock all the pages except @locked_page in case of failure.
  *
  * In summary, page locking state will be as follow:
  *
  * - page_started == 1 (return value)
  *     - All the pages are unlocked. IO is started.
  *     - Note that this can happen only on success
  * - unlock == 1
  *     - All the pages except @locked_page are unlocked in any case
  * - unlock == 0
  *     - On success, all the pages are locked for writing out them
  *     - On failure, all the pages except @locked_page are unlocked
  *
  * When a failure happens in the second or later iteration of the
  * while-loop, the ordered extents created in previous iterations are kept
  * intact. So, the caller must clean them up by calling
  * btrfs_cleanup_ordered_extents(). See btrfs_run_delalloc_range() for
  * example.
  */
 static noinline int cow_file_range(struct btrfs_inode *inode,
                    struct page *locked_page,
                    u64 start, u64 end, int *page_started,
                    unsigned long *nr_written, int unlock,
                    u64 *done_offset)
 {
     struct btrfs_root *root = inode->root;
     struct btrfs_fs_info *fs_info = root->fs_info;
     u64 alloc_hint = 0;
     u64 orig_start = start;
     u64 num_bytes;
     unsigned long ram_size;
     u64 cur_alloc_size = 0;
     u64 min_alloc_size;
     u64 blocksize = fs_info->sectorsize;
     struct btrfs_key ins;
     struct extent_map *em;
     unsigned clear_bits;
     unsigned long page_ops;
     bool extent_reserved = false;
     int ret = 0;
 
     if (btrfs_is_free_space_inode(inode)) {
         ret = -EINVAL;
         goto out_unlock;
     }
 
     num_bytes = ALIGN(end - start + 1, blocksize);
     num_bytes = max(blocksize,  num_bytes);
     ASSERT(num_bytes <= btrfs_super_total_bytes(fs_info->super_copy));
 
     inode_should_defrag(inode, start, end, num_bytes, SZ_64K);
 
     /*
      * Due to the page size limit, for subpage we can only trigger the
      * writeback for the dirty sectors of page, that means data writeback
      * is doing more writeback than what we want.
      *
      * This is especially unexpected for some call sites like fallocate,
      * where we only increase i_size after everything is done.
      * This means we can trigger inline extent even if we didn't want to.
      * So here we skip inline extent creation completely.
      */
     if (start == 0 && fs_info->sectorsize == PAGE_SIZE) {
         u64 actual_end = min_t(u64, i_size_read(&inode->vfs_inode),
                        end + 1);
 
         /* lets try to make an inline extent */
         ret = cow_file_range_inline(inode, actual_end, 0,
                         BTRFS_COMPRESS_NONE, NULL, false);
         if (ret == 0) {
             /*
              * We use DO_ACCOUNTING here because we need the
              * delalloc_release_metadata to be run _after_ we drop
              * our outstanding extent for clearing delalloc for this
              * range.
              */
             extent_clear_unlock_delalloc(inode, start, end,
                      locked_page,
                      EXTENT_LOCKED | EXTENT_DELALLOC |
                      EXTENT_DELALLOC_NEW | EXTENT_DEFRAG |
                      EXTENT_DO_ACCOUNTING, PAGE_UNLOCK |
                      PAGE_START_WRITEBACK | PAGE_END_WRITEBACK);
             *nr_written = *nr_written +
                  (end - start + PAGE_SIZE) / PAGE_SIZE;
             *page_started = 1;
             /*
              * locked_page is locked by the caller of
              * writepage_delalloc(), not locked by
              * __process_pages_contig().
              *
              * We can't let __process_pages_contig() to unlock it,
              * as it doesn't have any subpage::writers recorded.
              *
              * Here we manually unlock the page, since the caller
              * can't use page_started to determine if it's an
              * inline extent or a compressed extent.
              */
             unlock_page(locked_page);
             goto out;
         } else if (ret < 0) {
             goto out_unlock;
         }
     }
 
     alloc_hint = get_extent_allocation_hint(inode, start, num_bytes);
     btrfs_drop_extent_cache(inode, start, start + num_bytes - 1, 0);
 
     /*
      * Relocation relies on the relocated extents to have exactly the same
      * size as the original extents. Normally writeback for relocation data
      * extents follows a NOCOW path because relocation preallocates the
      * extents. However, due to an operation such as scrub turning a block
      * group to RO mode, it may fallback to COW mode, so we must make sure
      * an extent allocated during COW has exactly the requested size and can
      * not be split into smaller extents, otherwise relocation breaks and
      * fails during the stage where it updates the bytenr of file extent
      * items.
      */
     if (btrfs_is_data_reloc_root(root))
         min_alloc_size = num_bytes;
     else
         min_alloc_size = fs_info->sectorsize;
 
     while (num_bytes > 0) {
         cur_alloc_size = num_bytes;
         ret = btrfs_reserve_extent(root, cur_alloc_size, cur_alloc_size,
                        min_alloc_size, 0, alloc_hint,
                        &ins, 1, 1);
         if (ret < 0)
             goto out_unlock;
         cur_alloc_size = ins.offset;
         extent_reserved = true;
 
         ram_size = ins.offset;
         em = create_io_em(inode, start, ins.offset, /* len */
                   start, /* orig_start */
                   ins.objectid, /* block_start */
                   ins.offset, /* block_len */
                   ins.offset, /* orig_block_len */
                   ram_size, /* ram_bytes */
                   BTRFS_COMPRESS_NONE, /* compress_type */
                   BTRFS_ORDERED_REGULAR /* type */);
         if (IS_ERR(em)) {
             ret = PTR_ERR(em);
             goto out_reserve;
         }
         free_extent_map(em);
 
         ret = btrfs_add_ordered_extent(inode, start, ram_size, ram_size,
                            ins.objectid, cur_alloc_size, 0,
                            1 << BTRFS_ORDERED_REGULAR,
                            BTRFS_COMPRESS_NONE);
         if (ret)
             goto out_drop_extent_cache;
 
         if (btrfs_is_data_reloc_root(root)) {
             ret = btrfs_reloc_clone_csums(inode, start,
                               cur_alloc_size);
             /*
              * Only drop cache here, and process as normal.
              *
              * We must not allow extent_clear_unlock_delalloc()
              * at out_unlock label to free meta of this ordered
              * extent, as its meta should be freed by
              * btrfs_finish_ordered_io().
              *
              * So we must continue until @start is increased to
              * skip current ordered extent.
              */
             if (ret)
                 btrfs_drop_extent_cache(inode, start,
                         start + ram_size - 1, 0);
         }
 
         btrfs_dec_block_group_reservations(fs_info, ins.objectid);
 
         /*
          * We're not doing compressed IO, don't unlock the first page
          * (which the caller expects to stay locked), don't clear any
          * dirty bits and don't set any writeback bits
          *
          * Do set the Ordered (Private2) bit so we know this page was
          * properly setup for writepage.
          */
         page_ops = unlock ? PAGE_UNLOCK : 0;
         page_ops |= PAGE_SET_ORDERED;
 
         extent_clear_unlock_delalloc(inode, start, start + ram_size - 1,
                          locked_page,
                          EXTENT_LOCKED | EXTENT_DELALLOC,
                          page_ops);
         if (num_bytes < cur_alloc_size)
             num_bytes = 0;
         else
             num_bytes -= cur_alloc_size;
         alloc_hint = ins.objectid + ins.offset;
         start += cur_alloc_size;
         extent_reserved = false;
 
         /*
          * btrfs_reloc_clone_csums() error, since start is increased
          * extent_clear_unlock_delalloc() at out_unlock label won't
          * free metadata of current ordered extent, we're OK to exit.
          */
         if (ret)
             goto out_unlock;
     }
 out:
     return ret;
 
 out_drop_extent_cache:
     btrfs_drop_extent_cache(inode, start, start + ram_size - 1, 0);
 out_reserve:
     btrfs_dec_block_group_reservations(fs_info, ins.objectid);
     btrfs_free_reserved_extent(fs_info, ins.objectid, ins.offset, 1);
 out_unlock:
     /*
      * If done_offset is non-NULL and ret == -EAGAIN, we expect the
      * caller to write out the successfully allocated region and retry.
      */
     if (done_offset && ret == -EAGAIN) {
         if (orig_start < start)
             *done_offset = start - 1;
         else
             *done_offset = start;
         return ret;
     } else if (ret == -EAGAIN) {
         /* Convert to -ENOSPC since the caller cannot retry. */
         ret = -ENOSPC;
     }
 
     /*
      * Now, we have three regions to clean up:
      *
      * |-------(1)----|---(2)---|-------------(3)----------|
      * `- orig_start  `- start  `- start + cur_alloc_size  `- end
      *
      * We process each region below.
      */
 
     clear_bits = EXTENT_LOCKED | EXTENT_DELALLOC | EXTENT_DELALLOC_NEW |
         EXTENT_DEFRAG | EXTENT_CLEAR_META_RESV;
     page_ops = PAGE_UNLOCK | PAGE_START_WRITEBACK | PAGE_END_WRITEBACK;
 
     /*
      * For the range (1). We have already instantiated the ordered extents
      * for this region. They are cleaned up by
      * btrfs_cleanup_ordered_extents() in e.g,
      * btrfs_run_delalloc_range(). EXTENT_LOCKED | EXTENT_DELALLOC are
      * already cleared in the above loop. And, EXTENT_DELALLOC_NEW |
      * EXTENT_DEFRAG | EXTENT_CLEAR_META_RESV are handled by the cleanup
      * function.
      *
      * However, in case of unlock == 0, we still need to unlock the pages
      * (except @locked_page) to ensure all the pages are unlocked.
      */
     if (!unlock && orig_start < start) {
         if (!locked_page)
             mapping_set_error(inode->vfs_inode.i_mapping, ret);
         extent_clear_unlock_delalloc(inode, orig_start, start - 1,
                          locked_page, 0, page_ops);
     }
 
     /*
      * For the range (2). If we reserved an extent for our delalloc range
      * (or a subrange) and failed to create the respective ordered extent,
      * then it means that when we reserved the extent we decremented the
      * extent's size from the data space_info's bytes_may_use counter and
      * incremented the space_info's bytes_reserved counter by the same
      * amount. We must make sure extent_clear_unlock_delalloc() does not try
      * to decrement again the data space_info's bytes_may_use counter,
      * therefore we do not pass it the flag EXTENT_CLEAR_DATA_RESV.
      */
     if (extent_reserved) {
         extent_clear_unlock_delalloc(inode, start,
                          start + cur_alloc_size - 1,
                          locked_page,
                          clear_bits,
                          page_ops);
         start += cur_alloc_size;
         if (start >= end)
             return ret;
     }
 
     /*
      * For the range (3). We never touched the region. In addition to the
      * clear_bits above, we add EXTENT_CLEAR_DATA_RESV to release the data
      * space_info's bytes_may_use counter, reserved in
      * btrfs_check_data_free_space().
      */
     extent_clear_unlock_delalloc(inode, start, end, locked_page,
                      clear_bits | EXTENT_CLEAR_DATA_RESV,
                      page_ops);
     return ret;
 }
 
 /*
  * work queue call back to started compression on a file and pages
  */
 static noinline void async_cow_start(struct btrfs_work *work)
 {
     struct async_chunk *async_chunk;
     int compressed_extents;
 
     async_chunk = container_of(work, struct async_chunk, work);
 
     compressed_extents = compress_file_range(async_chunk);
     if (compressed_extents == 0) {
         btrfs_add_delayed_iput(async_chunk->inode);
         async_chunk->inode = NULL;
     }
 }
 
 /*
  * work queue call back to submit previously compressed pages
  */
 static noinline void async_cow_submit(struct btrfs_work *work)
 {
     struct async_chunk *async_chunk = container_of(work, struct async_chunk,
                              work);
     struct btrfs_fs_info *fs_info = btrfs_work_owner(work);
     unsigned long nr_pages;
 
     nr_pages = (async_chunk->end - async_chunk->start + PAGE_SIZE) >>
         PAGE_SHIFT;
 
     /*
      * ->inode could be NULL if async_chunk_start has failed to compress,
      * in which case we don't have anything to submit, yet we need to
      * always adjust ->async_delalloc_pages as its paired with the init
      * happening in cow_file_range_async
      */
     if (async_chunk->inode)
         submit_compressed_extents(async_chunk);
 
     /* atomic_sub_return implies a barrier */
     if (atomic_sub_return(nr_pages, &fs_info->async_delalloc_pages) <
         5 * SZ_1M)
         cond_wake_up_nomb(&fs_info->async_submit_wait);
 }
 
 static noinline void async_cow_free(struct btrfs_work *work)
 {
     struct async_chunk *async_chunk;
     struct async_cow *async_cow;
 
     async_chunk = container_of(work, struct async_chunk, work);
     if (async_chunk->inode)
         btrfs_add_delayed_iput(async_chunk->inode);
     if (async_chunk->blkcg_css)
         css_put(async_chunk->blkcg_css);
 
     async_cow = async_chunk->async_cow;
     if (atomic_dec_and_test(&async_cow->num_chunks))
         kvfree(async_cow);
 }
 
 static int cow_file_range_async(struct btrfs_inode *inode,
                 struct writeback_control *wbc,
                 struct page *locked_page,
                 u64 start, u64 end, int *page_started,
                 unsigned long *nr_written)
 {
     struct btrfs_fs_info *fs_info = inode->root->fs_info;
     struct cgroup_subsys_state *blkcg_css = wbc_blkcg_css(wbc);
     struct async_cow *ctx;
     struct async_chunk *async_chunk;
     unsigned long nr_pages;
     u64 cur_end;
     u64 num_chunks = DIV_ROUND_UP(end - start, SZ_512K);
     int i;
     bool should_compress;
     unsigned nofs_flag;
     const blk_opf_t write_flags = wbc_to_write_flags(wbc);
 
     unlock_extent(&inode->io_tree, start, end);
 
     if (inode->flags & BTRFS_INODE_NOCOMPRESS &&
         !btrfs_test_opt(fs_info, FORCE_COMPRESS)) {
         num_chunks = 1;
         should_compress = false;
     } else {
         should_compress = true;
     }
 
     nofs_flag = memalloc_nofs_save();
     ctx = kvmalloc(struct_size(ctx, chunks, num_chunks), GFP_KERNEL);
     memalloc_nofs_restore(nofs_flag);
 
     if (!ctx) {
         unsigned clear_bits = EXTENT_LOCKED | EXTENT_DELALLOC |
             EXTENT_DELALLOC_NEW | EXTENT_DEFRAG |
             EXTENT_DO_ACCOUNTING;
         unsigned long page_ops = PAGE_UNLOCK | PAGE_START_WRITEBACK |
                      PAGE_END_WRITEBACK | PAGE_SET_ERROR;
 
         extent_clear_unlock_delalloc(inode, start, end, locked_page,
                          clear_bits, page_ops);
         return -ENOMEM;
     }
 
     async_chunk = ctx->chunks;
     atomic_set(&ctx->num_chunks, num_chunks);
 
     for (i = 0; i < num_chunks; i++) {
         if (should_compress)
             cur_end = min(end, start + SZ_512K - 1);
         else
             cur_end = end;
 
         /*
          * igrab is called higher up in the call chain, take only the
          * lightweight reference for the callback lifetime
          */
         ihold(&inode->vfs_inode);
         async_chunk[i].async_cow = ctx;
         async_chunk[i].inode = &inode->vfs_inode;
         async_chunk[i].start = start;
         async_chunk[i].end = cur_end;
         async_chunk[i].write_flags = write_flags;
         INIT_LIST_HEAD(&async_chunk[i].extents);
 
         /*
          * The locked_page comes all the way from writepage and its
          * the original page we were actually given.  As we spread
          * this large delalloc region across multiple async_chunk
          * structs, only the first struct needs a pointer to locked_page
          *
          * This way we don't need racey decisions about who is supposed
          * to unlock it.
          */
         if (locked_page) {
             /*
              * Depending on the compressibility, the pages might or
              * might not go through async.  We want all of them to
              * be accounted against wbc once.  Let's do it here
              * before the paths diverge.  wbc accounting is used
              * only for foreign writeback detection and doesn't
              * need full accuracy.  Just account the whole thing
              * against the first page.
              */
             wbc_account_cgroup_owner(wbc, locked_page,
                          cur_end - start);
             async_chunk[i].locked_page = locked_page;
             locked_page = NULL;
         } else {
             async_chunk[i].locked_page = NULL;
         }
 
         if (blkcg_css != blkcg_root_css) {
             css_get(blkcg_css);
             async_chunk[i].blkcg_css = blkcg_css;
         } else {
             async_chunk[i].blkcg_css = NULL;
         }
 
         btrfs_init_work(&async_chunk[i].work, async_cow_start,
                 async_cow_submit, async_cow_free);
 
         nr_pages = DIV_ROUND_UP(cur_end - start, PAGE_SIZE);
         atomic_add(nr_pages, &fs_info->async_delalloc_pages);
 
         btrfs_queue_work(fs_info->delalloc_workers, &async_chunk[i].work);
 
         *nr_written += nr_pages;
         start = cur_end + 1;
     }
     *page_started = 1;
     return 0;
 }
 
 static noinline int run_delalloc_zoned(struct btrfs_inode *inode,
                        struct page *locked_page, u64 start,
                        u64 end, int *page_started,
                        unsigned long *nr_written)
 {
     u64 done_offset = end;
     int ret;
     bool locked_page_done = false;
 
     while (start <= end) {
         ret = cow_file_range(inode, locked_page, start, end, page_started,
                      nr_written, 0, &done_offset);
         if (ret && ret != -EAGAIN)
             return ret;
 
         if (*page_started) {
             ASSERT(ret == 0);
             return 0;
         }
 
         if (ret == 0)
             done_offset = end;
 
         if (done_offset == start) {
             wait_on_bit_io(&inode->root->fs_info->flags,
                        BTRFS_FS_NEED_ZONE_FINISH,
                        TASK_UNINTERRUPTIBLE);
             continue;
         }
 
         if (!locked_page_done) {
             __set_page_dirty_nobuffers(locked_page);
             account_page_redirty(locked_page);
         }
         locked_page_done = true;
         extent_write_locked_range(&inode->vfs_inode, start, done_offset);
 
         start = done_offset + 1;
     }
 
     *page_started = 1;
 
     return 0;
 }
 
 static noinline int csum_exist_in_range(struct btrfs_fs_info *fs_info,
                     u64 bytenr, u64 num_bytes)
 {
     struct btrfs_root *csum_root = btrfs_csum_root(fs_info, bytenr);
     struct btrfs_ordered_sum *sums;
     int ret;
     LIST_HEAD(list);
 
     ret = btrfs_lookup_csums_range(csum_root, bytenr,
                        bytenr + num_bytes - 1, &list, 0);
     if (ret == 0 && list_empty(&list))
         return 0;
 
     while (!list_empty(&list)) {
         sums = list_entry(list.next, struct btrfs_ordered_sum, list);
         list_del(&sums->list);
         kfree(sums);
     }
     if (ret < 0)
         return ret;
     return 1;
 }
 
 static int fallback_to_cow(struct btrfs_inode *inode, struct page *locked_page,
                const u64 start, const u64 end,
                int *page_started, unsigned long *nr_written)
 {
     const bool is_space_ino = btrfs_is_free_space_inode(inode);
     const bool is_reloc_ino = btrfs_is_data_reloc_root(inode->root);
     const u64 range_bytes = end + 1 - start;
     struct extent_io_tree *io_tree = &inode->io_tree;
     u64 range_start = start;
     u64 count;
 
     /*
      * If EXTENT_NORESERVE is set it means that when the buffered write was
      * made we had not enough available data space and therefore we did not
      * reserve data space for it, since we though we could do NOCOW for the
      * respective file range (either there is prealloc extent or the inode
      * has the NOCOW bit set).
      *
      * However when we need to fallback to COW mode (because for example the
      * block group for the corresponding extent was turned to RO mode by a
      * scrub or relocation) we need to do the following:
      *
      * 1) We increment the bytes_may_use counter of the data space info.
      *    If COW succeeds, it allocates a new data extent and after doing
      *    that it decrements the space info's bytes_may_use counter and
      *    increments its bytes_reserved counter by the same amount (we do
      *    this at btrfs_add_reserved_bytes()). So we need to increment the
      *    bytes_may_use counter to compensate (when space is reserved at
      *    buffered write time, the bytes_may_use counter is incremented);
      *
      * 2) We clear the EXTENT_NORESERVE bit from the range. We do this so
      *    that if the COW path fails for any reason, it decrements (through
      *    extent_clear_unlock_delalloc()) the bytes_may_use counter of the
      *    data space info, which we incremented in the step above.
      *
      * If we need to fallback to cow and the inode corresponds to a free
      * space cache inode or an inode of the data relocation tree, we must
      * also increment bytes_may_use of the data space_info for the same
      * reason. Space caches and relocated data extents always get a prealloc
      * extent for them, however scrub or balance may have set the block
      * group that contains that extent to RO mode and therefore force COW
      * when starting writeback.
      */
     count = count_range_bits(io_tree, &range_start, end, range_bytes,
                  EXTENT_NORESERVE, 0);
     if (count > 0 || is_space_ino || is_reloc_ino) {
         u64 bytes = count;
         struct btrfs_fs_info *fs_info = inode->root->fs_info;
         struct btrfs_space_info *sinfo = fs_info->data_sinfo;
 
         if (is_space_ino || is_reloc_ino)
             bytes = range_bytes;
 
         spin_lock(&sinfo->lock);
         btrfs_space_info_update_bytes_may_use(fs_info, sinfo, bytes);
         spin_unlock(&sinfo->lock);
 
         if (count > 0)
             clear_extent_bit(io_tree, start, end, EXTENT_NORESERVE,
                      0, 0, NULL);
     }
 
     return cow_file_range(inode, locked_page, start, end, page_started,
                   nr_written, 1, NULL);
 }
 
 struct can_nocow_file_extent_args {
     /* Input fields. */
 
     /* Start file offset of the range we want to NOCOW. */
     u64 start;
     /* End file offset (inclusive) of the range we want to NOCOW. */
     u64 end;
     bool writeback_path;
     bool strict;
     /*
      * Free the path passed to can_nocow_file_extent() once it's not needed
      * anymore.
      */
     bool free_path;
 
     /* Output fields. Only set when can_nocow_file_extent() returns 1. */
 
     u64 disk_bytenr;
     u64 disk_num_bytes;
     u64 extent_offset;
     /* Number of bytes that can be written to in NOCOW mode. */
     u64 num_bytes;
 };
 
 /*
  * Check if we can NOCOW the file extent that the path points to.
  * This function may return with the path released, so the caller should check
  * if path->nodes[0] is NULL or not if it needs to use the path afterwards.
  *
  * Returns: < 0 on error
  *            0 if we can not NOCOW
  *            1 if we can NOCOW
  */
 static int can_nocow_file_extent(struct btrfs_path *path,
                  struct btrfs_key *key,
                  struct btrfs_inode *inode,
                  struct can_nocow_file_extent_args *args)
 {
     const bool is_freespace_inode = btrfs_is_free_space_inode(inode);
     struct extent_buffer *leaf = path->nodes[0];
     struct btrfs_root *root = inode->root;
     struct btrfs_file_extent_item *fi;
     u64 extent_end;
     u8 extent_type;
     int can_nocow = 0;
     int ret = 0;
 
     fi = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_file_extent_item);
     extent_type = btrfs_file_extent_type(leaf, fi);
 
     if (extent_type == BTRFS_FILE_EXTENT_INLINE)
         goto out;
 
     /* Can't access these fields unless we know it's not an inline extent. */
     args->disk_bytenr = btrfs_file_extent_disk_bytenr(leaf, fi);
     args->disk_num_bytes = btrfs_file_extent_disk_num_bytes(leaf, fi);
     args->extent_offset = btrfs_file_extent_offset(leaf, fi);
 
     if (!(inode->flags & BTRFS_INODE_NODATACOW) &&
         extent_type == BTRFS_FILE_EXTENT_REG)
         goto out;
 
     /*
      * If the extent was created before the generation where the last snapshot
      * for its subvolume was created, then this implies the extent is shared,
      * hence we must COW.
      */
     if (!args->strict &&
         btrfs_file_extent_generation(leaf, fi) <=
         btrfs_root_last_snapshot(&root->root_item))
         goto out;
 
     /* An explicit hole, must COW. */
     if (args->disk_bytenr == 0)
         goto out;
 
     /* Compressed/encrypted/encoded extents must be COWed. */
     if (btrfs_file_extent_compression(leaf, fi) ||
         btrfs_file_extent_encryption(leaf, fi) ||
         btrfs_file_extent_other_encoding(leaf, fi))
         goto out;
 
     extent_end = btrfs_file_extent_end(path);
 
     /*
      * The following checks can be expensive, as they need to take other
      * locks and do btree or rbtree searches, so release the path to avoid
      * blocking other tasks for too long.
      */
     btrfs_release_path(path);
 
     ret = btrfs_cross_ref_exist(root, btrfs_ino(inode),
                     key->offset - args->extent_offset,
                     args->disk_bytenr, false, path);
     WARN_ON_ONCE(ret > 0 && is_freespace_inode);
     if (ret != 0)
         goto out;
 
     if (args->free_path) {
         /*
          * We don't need the path anymore, plus through the
          * csum_exist_in_range() call below we will end up allocating
          * another path. So free the path to avoid unnecessary extra
          * memory usage.
          */
         btrfs_free_path(path);
         path = NULL;
     }
 
     /* If there are pending snapshots for this root, we must COW. */
     if (args->writeback_path && !is_freespace_inode &&
         atomic_read(&root->snapshot_force_cow))
         goto out;
 
     args->disk_bytenr += args->extent_offset;
     args->disk_bytenr += args->start - key->offset;
     args->num_bytes = min(args->end + 1, extent_end) - args->start;
 
     /*
      * Force COW if csums exist in the range. This ensures that csums for a
      * given extent are either valid or do not exist.
      */
     ret = csum_exist_in_range(root->fs_info, args->disk_bytenr, args->num_bytes);
     WARN_ON_ONCE(ret > 0 && is_freespace_inode);
     if (ret != 0)
         goto out;
 
     can_nocow = 1;
  out:
     if (args->free_path && path)
         btrfs_free_path(path);
 
     return ret < 0 ? ret : can_nocow;
 }
 
 /*
  * when nowcow writeback call back.  This checks for snapshots or COW copies
  * of the extents that exist in the file, and COWs the file as required.
  *
  * If no cow copies or snapshots exist, we write directly to the existing
  * blocks on disk
  */
 static noinline int run_delalloc_nocow(struct btrfs_inode *inode,
                        struct page *locked_page,
                        const u64 start, const u64 end,
                        int *page_started,
                        unsigned long *nr_written)
 {
     struct btrfs_fs_info *fs_info = inode->root->fs_info;
     struct btrfs_root *root = inode->root;
     struct btrfs_path *path;
     u64 cow_start = (u64)-1;
     u64 cur_offset = start;
     int ret;
     bool check_prev = true;
     u64 ino = btrfs_ino(inode);
     struct btrfs_block_group *bg;
     bool nocow = false;
     struct can_nocow_file_extent_args nocow_args = { 0 };
 
     path = btrfs_alloc_path();
     if (!path) {
         extent_clear_unlock_delalloc(inode, start, end, locked_page,
                          EXTENT_LOCKED | EXTENT_DELALLOC |
                          EXTENT_DO_ACCOUNTING |
                          EXTENT_DEFRAG, PAGE_UNLOCK |
                          PAGE_START_WRITEBACK |
                          PAGE_END_WRITEBACK);
         return -ENOMEM;
     }
 
     nocow_args.end = end;
     nocow_args.writeback_path = true;
 
     while (1) {
         struct btrfs_key found_key;
         struct btrfs_file_extent_item *fi;
         struct extent_buffer *leaf;
         u64 extent_end;
         u64 ram_bytes;
         u64 nocow_end;
         int extent_type;
 
         nocow = false;
 
         ret = btrfs_lookup_file_extent(NULL, root, path, ino,
                            cur_offset, 0);
         if (ret < 0)
             goto error;
 
         /*
          * If there is no extent for our range when doing the initial
          * search, then go back to the previous slot as it will be the
          * one containing the search offset
          */
         if (ret > 0 && path->slots[0] > 0 && check_prev) {
             leaf = path->nodes[0];
             btrfs_item_key_to_cpu(leaf, &found_key,
                           path->slots[0] - 1);
             if (found_key.objectid == ino &&
                 found_key.type == BTRFS_EXTENT_DATA_KEY)
                 path->slots[0]--;
         }
         check_prev = false;
 next_slot:
         /* Go to next leaf if we have exhausted the current one */
         leaf = path->nodes[0];
         if (path->slots[0] >= btrfs_header_nritems(leaf)) {
             ret = btrfs_next_leaf(root, path);
             if (ret < 0) {
                 if (cow_start != (u64)-1)
                     cur_offset = cow_start;
                 goto error;
             }
             if (ret > 0)
                 break;
             leaf = path->nodes[0];
         }
 
         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 
         /* Didn't find anything for our INO */
         if (found_key.objectid > ino)
             break;
         /*
          * Keep searching until we find an EXTENT_ITEM or there are no
          * more extents for this inode
          */
         if (WARN_ON_ONCE(found_key.objectid < ino) ||
             found_key.type < BTRFS_EXTENT_DATA_KEY) {
             path->slots[0]++;
             goto next_slot;
         }
 
         /* Found key is not EXTENT_DATA_KEY or starts after req range */
         if (found_key.type > BTRFS_EXTENT_DATA_KEY ||
             found_key.offset > end)
             break;
 
         /*
          * If the found extent starts after requested offset, then
          * adjust extent_end to be right before this extent begins
          */
         if (found_key.offset > cur_offset) {
             extent_end = found_key.offset;
             extent_type = 0;
             goto out_check;
         }
 
         /*
          * Found extent which begins before our range and potentially
          * intersect it
          */
         fi = btrfs_item_ptr(leaf, path->slots[0],
                     struct btrfs_file_extent_item);
         extent_type = btrfs_file_extent_type(leaf, fi);
         /* If this is triggered then we have a memory corruption. */
         ASSERT(extent_type < BTRFS_NR_FILE_EXTENT_TYPES);
         if (WARN_ON(extent_type >= BTRFS_NR_FILE_EXTENT_TYPES)) {
             ret = -EUCLEAN;
             goto error;
         }
         ram_bytes = btrfs_file_extent_ram_bytes(leaf, fi);
         extent_end = btrfs_file_extent_end(path);
 
         /*
          * If the extent we got ends before our current offset, skip to
          * the next extent.
          */
         if (extent_end <= cur_offset) {
             path->slots[0]++;
             goto next_slot;
         }
 
         nocow_args.start = cur_offset;
         ret = can_nocow_file_extent(path, &found_key, inode, &nocow_args);
         if (ret < 0) {
             if (cow_start != (u64)-1)
                 cur_offset = cow_start;
             goto error;
         } else if (ret == 0) {
             goto out_check;
         }
 
         ret = 0;
         bg = btrfs_inc_nocow_writers(fs_info, nocow_args.disk_bytenr);
         if (bg)
             nocow = true;
 out_check:
         /*
          * If nocow is false then record the beginning of the range
          * that needs to be COWed
          */
         if (!nocow) {
             if (cow_start == (u64)-1)
                 cow_start = cur_offset;
             cur_offset = extent_end;
             if (cur_offset > end)
                 break;
             if (!path->nodes[0])
                 continue;
             path->slots[0]++;
             goto next_slot;
         }
 
         /*
          * COW range from cow_start to found_key.offset - 1. As the key
          * will contain the beginning of the first extent that can be
          * NOCOW, following one which needs to be COW'ed
          */
         if (cow_start != (u64)-1) {
             ret = fallback_to_cow(inode, locked_page,
                           cow_start, found_key.offset - 1,
                           page_started, nr_written);
             if (ret)
                 goto error;
             cow_start = (u64)-1;
         }
 
         nocow_end = cur_offset + nocow_args.num_bytes - 1;
 
         if (extent_type == BTRFS_FILE_EXTENT_PREALLOC) {
             u64 orig_start = found_key.offset - nocow_args.extent_offset;
             struct extent_map *em;
 
             em = create_io_em(inode, cur_offset, nocow_args.num_bytes,
                       orig_start,
                       nocow_args.disk_bytenr, /* block_start */
                       nocow_args.num_bytes, /* block_len */
                       nocow_args.disk_num_bytes, /* orig_block_len */
                       ram_bytes, BTRFS_COMPRESS_NONE,
                       BTRFS_ORDERED_PREALLOC);
             if (IS_ERR(em)) {
                 ret = PTR_ERR(em);
                 goto error;
             }
             free_extent_map(em);
             ret = btrfs_add_ordered_extent(inode,
                     cur_offset, nocow_args.num_bytes,
                     nocow_args.num_bytes,
                     nocow_args.disk_bytenr,
                     nocow_args.num_bytes, 0,
                     1 << BTRFS_ORDERED_PREALLOC,
                     BTRFS_COMPRESS_NONE);
             if (ret) {
                 btrfs_drop_extent_cache(inode, cur_offset,
                             nocow_end, 0);
                 goto error;
             }
         } else {
             ret = btrfs_add_ordered_extent(inode, cur_offset,
                                nocow_args.num_bytes,
                                nocow_args.num_bytes,
                                nocow_args.disk_bytenr,
                                nocow_args.num_bytes,
                                0,
                                1 << BTRFS_ORDERED_NOCOW,
                                BTRFS_COMPRESS_NONE);
             if (ret)
                 goto error;
         }
 
         if (nocow) {
             btrfs_dec_nocow_writers(bg);
             nocow = false;
         }
 
         if (btrfs_is_data_reloc_root(root))
             /*
              * Error handled later, as we must prevent
              * extent_clear_unlock_delalloc() in error handler
              * from freeing metadata of created ordered extent.
              */
             ret = btrfs_reloc_clone_csums(inode, cur_offset,
                               nocow_args.num_bytes);
 
         extent_clear_unlock_delalloc(inode, cur_offset, nocow_end,
                          locked_page, EXTENT_LOCKED |
                          EXTENT_DELALLOC |
                          EXTENT_CLEAR_DATA_RESV,
                          PAGE_UNLOCK | PAGE_SET_ORDERED);
 
         cur_offset = extent_end;
 
         /*
          * btrfs_reloc_clone_csums() error, now we're OK to call error
          * handler, as metadata for created ordered extent will only
          * be freed by btrfs_finish_ordered_io().
          */
         if (ret)
             goto error;
         if (cur_offset > end)
             break;
     }
     btrfs_release_path(path);
 
     if (cur_offset <= end && cow_start == (u64)-1)
         cow_start = cur_offset;
 
     if (cow_start != (u64)-1) {
         cur_offset = end;
         ret = fallback_to_cow(inode, locked_page, cow_start, end,
                       page_started, nr_written);
         if (ret)
             goto error;
     }
 
 error:
     if (nocow)
         btrfs_dec_nocow_writers(bg);
 
     if (ret && cur_offset < end)
         extent_clear_unlock_delalloc(inode, cur_offset, end,
                          locked_page, EXTENT_LOCKED |
                          EXTENT_DELALLOC | EXTENT_DEFRAG |
                          EXTENT_DO_ACCOUNTING, PAGE_UNLOCK |
                          PAGE_START_WRITEBACK |
                          PAGE_END_WRITEBACK);
     btrfs_free_path(path);
     return ret;
 }
 
 static bool should_nocow(struct btrfs_inode *inode, u64 start, u64 end)
 {
     if (inode->flags & (BTRFS_INODE_NODATACOW | BTRFS_INODE_PREALLOC)) {
         if (inode->defrag_bytes &&
             test_range_bit(&inode->io_tree, start, end, EXTENT_DEFRAG,
                    0, NULL))
             return false;
         return true;
     }
     return false;
 }
 
 /*
  * Function to process delayed allocation (create CoW) for ranges which are
  * being touched for the first time.
  */
 int btrfs_run_delalloc_range(struct btrfs_inode *inode, struct page *locked_page,
         u64 start, u64 end, int *page_started, unsigned long *nr_written,
         struct writeback_control *wbc)
 {
     int ret;
     const bool zoned = btrfs_is_zoned(inode->root->fs_info);
 
     /*
      * The range must cover part of the @locked_page, or the returned
      * @page_started can confuse the caller.
      */
     ASSERT(!(end <= page_offset(locked_page) ||
          start >= page_offset(locked_page) + PAGE_SIZE));
 
     if (should_nocow(inode, start, end)) {
         /*
          * Normally on a zoned device we're only doing COW writes, but
          * in case of relocation on a zoned filesystem we have taken
          * precaution, that we're only writing sequentially. It's safe
          * to use run_delalloc_nocow() here, like for  regular
          * preallocated inodes.
          */
         ASSERT(!zoned || btrfs_is_data_reloc_root(inode->root));
         ret = run_delalloc_nocow(inode, locked_page, start, end,
                      page_started, nr_written);
     } else if (!btrfs_inode_can_compress(inode) ||
            !inode_need_compress(inode, start, end)) {
         if (zoned)
             ret = run_delalloc_zoned(inode, locked_page, start, end,
                          page_started, nr_written);
         else
             ret = cow_file_range(inode, locked_page, start, end,
                          page_started, nr_written, 1, NULL);
     } else {
         set_bit(BTRFS_INODE_HAS_ASYNC_EXTENT, &inode->runtime_flags);
         ret = cow_file_range_async(inode, wbc, locked_page, start, end,
                        page_started, nr_written);
     }
     ASSERT(ret <= 0);
     if (ret)
         btrfs_cleanup_ordered_extents(inode, locked_page, start,
                           end - start + 1);
     return ret;
 }
 
 void btrfs_split_delalloc_extent(struct inode *inode,
                  struct extent_state *orig, u64 split)
 {
     struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
     u64 size;
 
     /* not delalloc, ignore it */
     if (!(orig->state & EXTENT_DELALLOC))
         return;
 
     size = orig->end - orig->start + 1;
     if (size > fs_info->max_extent_size) {
         u32 num_extents;
         u64 new_size;
 
         /*
          * See the explanation in btrfs_merge_delalloc_extent, the same
          * applies here, just in reverse.
          */
         new_size = orig->end - split + 1;
         num_extents = count_max_extents(fs_info, new_size);
         new_size = split - orig->start;
         num_extents += count_max_extents(fs_info, new_size);
         if (count_max_extents(fs_info, size) >= num_extents)
             return;
     }
 
     spin_lock(&BTRFS_I(inode)->lock);
     btrfs_mod_outstanding_extents(BTRFS_I(inode), 1);
     spin_unlock(&BTRFS_I(inode)->lock);
 }
 
 /*
  * Handle merged delayed allocation extents so we can keep track of new extents
  * that are just merged onto old extents, such as when we are doing sequential
  * writes, so we can properly account for the metadata space we'll need.
  */
 void btrfs_merge_delalloc_extent(struct inode *inode, struct extent_state *new,
                  struct extent_state *other)
 {
     struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
     u64 new_size, old_size;
     u32 num_extents;
 
     /* not delalloc, ignore it */
     if (!(other->state & EXTENT_DELALLOC))
         return;
 
     if (new->start > other->start)
         new_size = new->end - other->start + 1;
     else
         new_size = other->end - new->start + 1;
 
     /* we're not bigger than the max, unreserve the space and go */
     if (new_size <= fs_info->max_extent_size) {
         spin_lock(&BTRFS_I(inode)->lock);
         btrfs_mod_outstanding_extents(BTRFS_I(inode), -1);
         spin_unlock(&BTRFS_I(inode)->lock);
         return;
     }
 
     /*
      * We have to add up either side to figure out how many extents were
      * accounted for before we merged into one big extent.  If the number of
      * extents we accounted for is <= the amount we need for the new range
      * then we can return, otherwise drop.  Think of it like this
      *
      * [ 4k][MAX_SIZE]
      *
      * So we've grown the extent by a MAX_SIZE extent, this would mean we
      * need 2 outstanding extents, on one side we have 1 and the other side
      * we have 1 so they are == and we can return.  But in this case
      *
      * [MAX_SIZE+4k][MAX_SIZE+4k]
      *
      * Each range on their own accounts for 2 extents, but merged together
      * they are only 3 extents worth of accounting, so we need to drop in
      * this case.
      */
     old_size = other->end - other->start + 1;
     num_extents = count_max_extents(fs_info, old_size);
     old_size = new->end - new->start + 1;
     num_extents += count_max_extents(fs_info, old_size);
     if (count_max_extents(fs_info, new_size) >= num_extents)
         return;
 
     spin_lock(&BTRFS_I(inode)->lock);
     btrfs_mod_outstanding_extents(BTRFS_I(inode), -1);
     spin_unlock(&BTRFS_I(inode)->lock);
 }
 
 static void btrfs_add_delalloc_inodes(struct btrfs_root *root,
                       struct inode *inode)
 {
     struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
 
     spin_lock(&root->delalloc_lock);
     if (list_empty(&BTRFS_I(inode)->delalloc_inodes)) {
         list_add_tail(&BTRFS_I(inode)->delalloc_inodes,
                   &root->delalloc_inodes);
         set_bit(BTRFS_INODE_IN_DELALLOC_LIST,
             &BTRFS_I(inode)->runtime_flags);
         root->nr_delalloc_inodes++;
         if (root->nr_delalloc_inodes == 1) {
             spin_lock(&fs_info->delalloc_root_lock);
             BUG_ON(!list_empty(&root->delalloc_root));
             list_add_tail(&root->delalloc_root,
                       &fs_info->delalloc_roots);
             spin_unlock(&fs_info->delalloc_root_lock);
         }
     }
     spin_unlock(&root->delalloc_lock);
 }
 
 
 void __btrfs_del_delalloc_inode(struct btrfs_root *root,
                 struct btrfs_inode *inode)
 {
     struct btrfs_fs_info *fs_info = root->fs_info;
 
     if (!list_empty(&inode->delalloc_inodes)) {
         list_del_init(&inode->delalloc_inodes);
         clear_bit(BTRFS_INODE_IN_DELALLOC_LIST,
               &inode->runtime_flags);
         root->nr_delalloc_inodes--;
         if (!root->nr_delalloc_inodes) {
             ASSERT(list_empty(&root->delalloc_inodes));
             spin_lock(&fs_info->delalloc_root_lock);
             BUG_ON(list_empty(&root->delalloc_root));
             list_del_init(&root->delalloc_root);
             spin_unlock(&fs_info->delalloc_root_lock);
         }
     }
 }
 
 static void btrfs_del_delalloc_inode(struct btrfs_root *root,
                      struct btrfs_inode *inode)
 {
     spin_lock(&root->delalloc_lock);
     __btrfs_del_delalloc_inode(root, inode);
     spin_unlock(&root->delalloc_lock);
 }
 
 /*
  * Properly track delayed allocation bytes in the inode and to maintain the
  * list of inodes that have pending delalloc work to be done.
  */
 void btrfs_set_delalloc_extent(struct inode *inode, struct extent_state *state,
                    u32 bits)
 {
     struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
 
     if ((bits & EXTENT_DEFRAG) && !(bits & EXTENT_DELALLOC))
         WARN_ON(1);
     /*
      * set_bit and clear bit hooks normally require _irqsave/restore
      * but in this case, we are only testing for the DELALLOC
      * bit, which is only set or cleared with irqs on
      */
     if (!(state->state & EXTENT_DELALLOC) && (bits & EXTENT_DELALLOC)) {
         struct btrfs_root *root = BTRFS_I(inode)->root;
         u64 len = state->end + 1 - state->start;
         u32 num_extents = count_max_extents(fs_info, len);
         bool do_list = !btrfs_is_free_space_inode(BTRFS_I(inode));
 
         spin_lock(&BTRFS_I(inode)->lock);
         btrfs_mod_outstanding_extents(BTRFS_I(inode), num_extents);
         spin_unlock(&BTRFS_I(inode)->lock);
 
         /* For sanity tests */
         if (btrfs_is_testing(fs_info))
             return;
 
         percpu_counter_add_batch(&fs_info->delalloc_bytes, len,
                      fs_info->delalloc_batch);
         spin_lock(&BTRFS_I(inode)->lock);
         BTRFS_I(inode)->delalloc_bytes += len;
         if (bits & EXTENT_DEFRAG)
             BTRFS_I(inode)->defrag_bytes += len;
         if (do_list && !test_bit(BTRFS_INODE_IN_DELALLOC_LIST,
                      &BTRFS_I(inode)->runtime_flags))
             btrfs_add_delalloc_inodes(root, inode);
         spin_unlock(&BTRFS_I(inode)->lock);
     }
 
     if (!(state->state & EXTENT_DELALLOC_NEW) &&
         (bits & EXTENT_DELALLOC_NEW)) {
         spin_lock(&BTRFS_I(inode)->lock);
         BTRFS_I(inode)->new_delalloc_bytes += state->end + 1 -
             state->start;
         spin_unlock(&BTRFS_I(inode)->lock);
     }
 }
 
 /*
  * Once a range is no longer delalloc this function ensures that proper
  * accounting happens.
  */
 void btrfs_clear_delalloc_extent(struct inode *vfs_inode,
                  struct extent_state *state, u32 bits)
 {
     struct btrfs_inode *inode = BTRFS_I(vfs_inode);
     struct btrfs_fs_info *fs_info = btrfs_sb(vfs_inode->i_sb);
     u64 len = state->end + 1 - state->start;
     u32 num_extents = count_max_extents(fs_info, len);
 
     if ((state->state & EXTENT_DEFRAG) && (bits & EXTENT_DEFRAG)) {
         spin_lock(&inode->lock);
         inode->defrag_bytes -= len;
         spin_unlock(&inode->lock);
     }
 
     /*
      * set_bit and clear bit hooks normally require _irqsave/restore
      * but in this case, we are only testing for the DELALLOC
      * bit, which is only set or cleared with irqs on
      */
     if ((state->state & EXTENT_DELALLOC) && (bits & EXTENT_DELALLOC)) {
         struct btrfs_root *root = inode->root;
         bool do_list = !btrfs_is_free_space_inode(inode);
 
         spin_lock(&inode->lock);
         btrfs_mod_outstanding_extents(inode, -num_extents);
         spin_unlock(&inode->lock);
 
         /*
          * We don't reserve metadata space for space cache inodes so we
          * don't need to call delalloc_release_metadata if there is an
          * error.
          */
         if (bits & EXTENT_CLEAR_META_RESV &&
             root != fs_info->tree_root)
             btrfs_delalloc_release_metadata(inode, len, false);
 
         /* For sanity tests. */
         if (btrfs_is_testing(fs_info))
             return;
 
         if (!btrfs_is_data_reloc_root(root) &&
             do_list && !(state->state & EXTENT_NORESERVE) &&
             (bits & EXTENT_CLEAR_DATA_RESV))
             btrfs_free_reserved_data_space_noquota(fs_info, len);
 
         percpu_counter_add_batch(&fs_info->delalloc_bytes, -len,
                      fs_info->delalloc_batch);
         spin_lock(&inode->lock);
         inode->delalloc_bytes -= len;
         if (do_list && inode->delalloc_bytes == 0 &&
             test_bit(BTRFS_INODE_IN_DELALLOC_LIST,
                     &inode->runtime_flags))
             btrfs_del_delalloc_inode(root, inode);
         spin_unlock(&inode->lock);
     }
 
     if ((state->state & EXTENT_DELALLOC_NEW) &&
         (bits & EXTENT_DELALLOC_NEW)) {
         spin_lock(&inode->lock);
         ASSERT(inode->new_delalloc_bytes >= len);
         inode->new_delalloc_bytes -= len;
         if (bits & EXTENT_ADD_INODE_BYTES)
             inode_add_bytes(&inode->vfs_inode, len);
         spin_unlock(&inode->lock);
     }
 }
 
 /*
  * in order to insert checksums into the metadata in large chunks,
  * we wait until bio submission time.   All the pages in the bio are
  * checksummed and sums are attached onto the ordered extent record.
  *
  * At IO completion time the cums attached on the ordered extent record
  * are inserted into the btree
  */
 static blk_status_t btrfs_submit_bio_start(struct inode *inode, struct bio *bio,
                        u64 dio_file_offset)
 {
     return btrfs_csum_one_bio(BTRFS_I(inode), bio, (u64)-1, false);
 }
 
 /*
  * Split an extent_map at [start, start + len]
  *
  * This function is intended to be used only for extract_ordered_extent().
  */
 static int split_zoned_em(struct btrfs_inode *inode, u64 start, u64 len,
               u64 pre, u64 post)
 {
     struct extent_map_tree *em_tree = &inode->extent_tree;
     struct extent_map *em;
     struct extent_map *split_pre = NULL;
     struct extent_map *split_mid = NULL;
     struct extent_map *split_post = NULL;
     int ret = 0;
     unsigned long flags;
 
     /* Sanity check */
     if (pre == 0 && post == 0)
         return 0;
 
     split_pre = alloc_extent_map();
     if (pre)
         split_mid = alloc_extent_map();
     if (post)
         split_post = alloc_extent_map();
     if (!split_pre || (pre && !split_mid) || (post && !split_post)) {
         ret = -ENOMEM;
         goto out;
     }
 
     ASSERT(pre + post < len);
 
     lock_extent(&inode->io_tree, start, start + len - 1);
     write_lock(&em_tree->lock);
     em = lookup_extent_mapping(em_tree, start, len);
     if (!em) {
         ret = -EIO;
         goto out_unlock;
     }
 
     ASSERT(em->len == len);
     ASSERT(!test_bit(EXTENT_FLAG_COMPRESSED, &em->flags));
     ASSERT(em->block_start < EXTENT_MAP_LAST_BYTE);
     ASSERT(test_bit(EXTENT_FLAG_PINNED, &em->flags));
     ASSERT(!test_bit(EXTENT_FLAG_LOGGING, &em->flags));
     ASSERT(!list_empty(&em->list));
 
     flags = em->flags;
     clear_bit(EXTENT_FLAG_PINNED, &em->flags);
 
     /* First, replace the em with a new extent_map starting from * em->start */
     split_pre->start = em->start;
     split_pre->len = (pre ? pre : em->len - post);
     split_pre->orig_start = split_pre->start;
     split_pre->block_start = em->block_start;
     split_pre->block_len = split_pre->len;
     split_pre->orig_block_len = split_pre->block_len;
     split_pre->ram_bytes = split_pre->len;
     split_pre->flags = flags;
     split_pre->compress_type = em->compress_type;
     split_pre->generation = em->generation;
 
     replace_extent_mapping(em_tree, em, split_pre, 1);
 
     /*
      * Now we only have an extent_map at:
      *     [em->start, em->start + pre] if pre != 0
      *     [em->start, em->start + em->len - post] if pre == 0
      */
 
     if (pre) {
         /* Insert the middle extent_map */
         split_mid->start = em->start + pre;
         split_mid->len = em->len - pre - post;
         split_mid->orig_start = split_mid->start;
         split_mid->block_start = em->block_start + pre;
         split_mid->block_len = split_mid->len;
         split_mid->orig_block_len = split_mid->block_len;
         split_mid->ram_bytes = split_mid->len;
         split_mid->flags = flags;
         split_mid->compress_type = em->compress_type;
         split_mid->generation = em->generation;
         add_extent_mapping(em_tree, split_mid, 1);
     }
 
     if (post) {
         split_post->start = em->start + em->len - post;
         split_post->len = post;
         split_post->orig_start = split_post->start;
         split_post->block_start = em->block_start + em->len - post;
         split_post->block_len = split_post->len;
         split_post->orig_block_len = split_post->block_len;
         split_post->ram_bytes = split_post->len;
         split_post->flags = flags;
         split_post->compress_type = em->compress_type;
         split_post->generation = em->generation;
         add_extent_mapping(em_tree, split_post, 1);
     }
 
     /* Once for us */
     free_extent_map(em);
     /* Once for the tree */
     free_extent_map(em);
 
 out_unlock:
     write_unlock(&em_tree->lock);
     unlock_extent(&inode->io_tree, start, start + len - 1);
 out:
     free_extent_map(split_pre);
     free_extent_map(split_mid);
     free_extent_map(split_post);
 
     return ret;
 }
 
 static blk_status_t extract_ordered_extent(struct btrfs_inode *inode,
                        struct bio *bio, loff_t file_offset)
 {
     struct btrfs_ordered_extent *ordered;
     u64 start = (u64)bio->bi_iter.bi_sector << SECTOR_SHIFT;
     u64 file_len;
     u64 len = bio->bi_iter.bi_size;
     u64 end = start + len;
     u64 ordered_end;
     u64 pre, post;
     int ret = 0;
 
     ordered = btrfs_lookup_ordered_extent(inode, file_offset);
     if (WARN_ON_ONCE(!ordered))
         return BLK_STS_IOERR;
 
     /* No need to split */
     if (ordered->disk_num_bytes == len)
         goto out;
 
     /* We cannot split once end_bio'd ordered extent */
     if (WARN_ON_ONCE(ordered->bytes_left != ordered->disk_num_bytes)) {
         ret = -EINVAL;
         goto out;
     }
 
     /* We cannot split a compressed ordered extent */
     if (WARN_ON_ONCE(ordered->disk_num_bytes != ordered->num_bytes)) {
         ret = -EINVAL;
         goto out;
     }
 
     ordered_end = ordered->disk_bytenr + ordered->disk_num_bytes;
     /* bio must be in one ordered extent */
     if (WARN_ON_ONCE(start < ordered->disk_bytenr || end > ordered_end)) {
         ret = -EINVAL;
         goto out;
     }
 
     /* Checksum list should be empty */
     if (WARN_ON_ONCE(!list_empty(&ordered->list))) {
         ret = -EINVAL;
         goto out;
     }
 
     file_len = ordered->num_bytes;
     pre = start - ordered->disk_bytenr;
     post = ordered_end - end;
 
     ret = btrfs_split_ordered_extent(ordered, pre, post);
     if (ret)
         goto out;
     ret = split_zoned_em(inode, file_offset, file_len, pre, post);
 
 out:
     btrfs_put_ordered_extent(ordered);
 
     return errno_to_blk_status(ret);
 }
 
 void btrfs_submit_data_write_bio(struct inode *inode, struct bio *bio, int mirror_num)
 {
     struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
     struct btrfs_inode *bi = BTRFS_I(inode);
     blk_status_t ret;
 
     if (bio_op(bio) == REQ_OP_ZONE_APPEND) {
         ret = extract_ordered_extent(bi, bio,
                 page_offset(bio_first_bvec_all(bio)->bv_page));
         if (ret)
             goto out;
     }
 
     /*
      * If we need to checksum, and the I/O is not issued by fsync and
      * friends, that is ->sync_writers != 0, defer the submission to a
      * workqueue to parallelize it.
      *
      * Csum items for reloc roots have already been cloned at this point,
      * so they are handled as part of the no-checksum case.
      */
     if (!(bi->flags & BTRFS_INODE_NODATASUM) &&
         !test_bit(BTRFS_FS_STATE_NO_CSUMS, &fs_info->fs_state) &&
         !btrfs_is_data_reloc_root(bi->root)) {
         if (!atomic_read(&bi->sync_writers) &&
             btrfs_wq_submit_bio(inode, bio, mirror_num, 0,
                     btrfs_submit_bio_start))
             return;
 
         ret = btrfs_csum_one_bio(bi, bio, (u64)-1, false);
         if (ret)
             goto out;
     }
     btrfs_submit_bio(fs_info, bio, mirror_num);
     return;
 out:
     if (ret) {
         bio->bi_status = ret;
         bio_endio(bio);
     }
 }
 
 void btrfs_submit_data_read_bio(struct inode *inode, struct bio *bio,
             int mirror_num, enum btrfs_compression_type compress_type)
 {
     struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
     blk_status_t ret;
 
     if (compress_type != BTRFS_COMPRESS_NONE) {
         /*
          * btrfs_submit_compressed_read will handle completing the bio
          * if there were any errors, so just return here.
          */
         btrfs_submit_compressed_read(inode, bio, mirror_num);
         return;
     }
 
     /* Save the original iter for read repair */
     btrfs_bio(bio)->iter = bio->bi_iter;
 
     /*
      * Lookup bio sums does extra checks around whether we need to csum or
      * not, which is why we ignore skip_sum here.
      */
     ret = btrfs_lookup_bio_sums(inode, bio, NULL);
     if (ret) {
         bio->bi_status = ret;
         bio_endio(bio);
         return;
     }
 
     btrfs_submit_bio(fs_info, bio, mirror_num);
 }
 
 /*
  * given a list of ordered sums record them in the inode.  This happens
  * at IO completion time based on sums calculated at bio submission time.
  */
 static int add_pending_csums(struct btrfs_trans_handle *trans,
                  struct list_head *list)
 {
     struct btrfs_ordered_sum *sum;
     struct btrfs_root *csum_root = NULL;
     int ret;
 
     list_for_each_entry(sum, list, list) {
         trans->adding_csums = true;
         if (!csum_root)
             csum_root = btrfs_csum_root(trans->fs_info,
                             sum->bytenr);
         ret = btrfs_csum_file_blocks(trans, csum_root, sum);
         trans->adding_csums = false;
         if (ret)
             return ret;
     }
     return 0;
 }
 
 static int btrfs_find_new_delalloc_bytes(struct btrfs_inode *inode,
                      const u64 start,
                      const u64 len,
                      struct extent_state **cached_state)
 {
     u64 search_start = start;
     const u64 end = start + len - 1;
 
     while (search_start < end) {
         const u64 search_len = end - search_start + 1;
         struct extent_map *em;
         u64 em_len;
         int ret = 0;
 
         em = btrfs_get_extent(inode, NULL, 0, search_start, search_len);
         if (IS_ERR(em))
             return PTR_ERR(em);
 
         if (em->block_start != EXTENT_MAP_HOLE)
             goto next;
 
         em_len = em->len;
         if (em->start < search_start)
             em_len -= search_start - em->start;
         if (em_len > search_len)
             em_len = search_len;
 
         ret = set_extent_bit(&inode->io_tree, search_start,
                      search_start + em_len - 1,
                      EXTENT_DELALLOC_NEW, 0, NULL, cached_state,
                      GFP_NOFS, NULL);
 next:
         search_start = extent_map_end(em);
         free_extent_map(em);
         if (ret)
             return ret;
     }
     return 0;
 }
 
 int btrfs_set_extent_delalloc(struct btrfs_inode *inode, u64 start, u64 end,
                   unsigned int extra_bits,
                   struct extent_state **cached_state)
 {
     WARN_ON(PAGE_ALIGNED(end));
 
     if (start >= i_size_read(&inode->vfs_inode) &&
         !(inode->flags & BTRFS_INODE_PREALLOC)) {
         /*
          * There can't be any extents following eof in this case so just
          * set the delalloc new bit for the range directly.
          */
         extra_bits |= EXTENT_DELALLOC_NEW;
     } else {
         int ret;
 
         ret = btrfs_find_new_delalloc_bytes(inode, start,
                             end + 1 - start,
                             cached_state);
         if (ret)
             return ret;
     }
 
     return set_extent_delalloc(&inode->io_tree, start, end, extra_bits,
                    cached_state);
 }
 
 /* see btrfs_writepage_start_hook for details on why this is required */
 struct btrfs_writepage_fixup {
     struct page *page;
     struct inode *inode;
     struct btrfs_work work;
 };
 
 static void btrfs_writepage_fixup_worker(struct btrfs_work *work)
 {
     struct btrfs_writepage_fixup *fixup;
     struct btrfs_ordered_extent *ordered;
     struct extent_state *cached_state = NULL;
     struct extent_changeset *data_reserved = NULL;
     struct page *page;
     struct btrfs_inode *inode;
     u64 page_start;
     u64 page_end;
     int ret = 0;
     bool free_delalloc_space = true;
 
     fixup = container_of(work, struct btrfs_writepage_fixup, work);
     page = fixup->page;
     inode = BTRFS_I(fixup->inode);
     page_start = page_offset(page);
     page_end = page_offset(page) + PAGE_SIZE - 1;
 
     /*
      * This is similar to page_mkwrite, we need to reserve the space before
      * we take the page lock.
      */
     ret = btrfs_delalloc_reserve_space(inode, &data_reserved, page_start,
                        PAGE_SIZE);
 again:
     lock_page(page);
 
     /*
      * Before we queued this fixup, we took a reference on the page.
      * page->mapping may go NULL, but it shouldn't be moved to a different
      * address space.
      */
     if (!page->mapping || !PageDirty(page) || !PageChecked(page)) {
         /*
          * Unfortunately this is a little tricky, either
          *
          * 1) We got here and our page had already been dealt with and
          *    we reserved our space, thus ret == 0, so we need to just
          *    drop our space reservation and bail.  This can happen the
          *    first time we come into the fixup worker, or could happen
          *    while waiting for the ordered extent.
          * 2) Our page was already dealt with, but we happened to get an
          *    ENOSPC above from the btrfs_delalloc_reserve_space.  In
          *    this case we obviously don't have anything to release, but
          *    because the page was already dealt with we don't want to
          *    mark the page with an error, so make sure we're resetting
          *    ret to 0.  This is why we have this check _before_ the ret
          *    check, because we do not want to have a surprise ENOSPC
          *    when the page was already properly dealt with.
          */
         if (!ret) {
             btrfs_delalloc_release_extents(inode, PAGE_SIZE);
             btrfs_delalloc_release_space(inode, data_reserved,
                              page_start, PAGE_SIZE,
                              true);
         }
         ret = 0;
         goto out_page;
     }
 
     /*
      * We can't mess with the page state unless it is locked, so now that
      * it is locked bail if we failed to make our space reservation.
      */
     if (ret)
         goto out_page;
 
     lock_extent_bits(&inode->io_tree, page_start, page_end, &cached_state);
 
     /* already ordered? We're done */
     if (PageOrdered(page))
         goto out_reserved;
 
     ordered = btrfs_lookup_ordered_range(inode, page_start, PAGE_SIZE);
     if (ordered) {
         unlock_extent_cached(&inode->io_tree, page_start, page_end,
                      &cached_state);
         unlock_page(page);
         btrfs_start_ordered_extent(ordered, 1);
         btrfs_put_ordered_extent(ordered);
         goto again;
     }
 
     ret = btrfs_set_extent_delalloc(inode, page_start, page_end, 0,
                     &cached_state);
     if (ret)
         goto out_reserved;
 
     /*
      * Everything went as planned, we're now the owner of a dirty page with
      * delayed allocation bits set and space reserved for our COW
      * destination.
      *
      * The page was dirty when we started, nothing should have cleaned it.
      */
     BUG_ON(!PageDirty(page));
     free_delalloc_space = false;
 out_reserved:
     btrfs_delalloc_release_extents(inode, PAGE_SIZE);
     if (free_delalloc_space)
         btrfs_delalloc_release_space(inode, data_reserved, page_start,
                          PAGE_SIZE, true);
     unlock_extent_cached(&inode->io_tree, page_start, page_end,
                  &cached_state);
 out_page:
     if (ret) {
         /*
          * We hit ENOSPC or other errors.  Update the mapping and page
          * to reflect the errors and clean the page.
          */
         mapping_set_error(page->mapping, ret);
         end_extent_writepage(page, ret, page_start, page_end);
         clear_page_dirty_for_io(page);
         SetPageError(page);
     }
     btrfs_page_clear_checked(inode->root->fs_info, page, page_start, PAGE_SIZE);
     unlock_page(page);
     put_page(page);
     kfree(fixup);
     extent_changeset_free(data_reserved);
     /*
      * As a precaution, do a delayed iput in case it would be the last iput
      * that could need flushing space. Recursing back to fixup worker would
      * deadlock.
      */
     btrfs_add_delayed_iput(&inode->vfs_inode);
 }
 
 /*
  * There are a few paths in the higher layers of the kernel that directly
  * set the page dirty bit without asking the filesystem if it is a
  * good idea.  This causes problems because we want to make sure COW
  * properly happens and the data=ordered rules are followed.
  *
  * In our case any range that doesn't have the ORDERED bit set
  * hasn't been properly setup for IO.  We kick off an async process
  * to fix it up.  The async helper will wait for ordered extents, set
  * the delalloc bit and make it safe to write the page.
  */
 int btrfs_writepage_cow_fixup(struct page *page)
 {
     struct inode *inode = page->mapping->host;
     struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
     struct btrfs_writepage_fixup *fixup;
 
     /* This page has ordered extent covering it already */
     if (PageOrdered(page))
         return 0;
 
     /*
      * PageChecked is set below when we create a fixup worker for this page,
      * don't try to create another one if we're already PageChecked()
      *
      * The extent_io writepage code will redirty the page if we send back
      * EAGAIN.
      */
     if (PageChecked(page))
         return -EAGAIN;
 
     fixup = kzalloc(sizeof(*fixup), GFP_NOFS);
     if (!fixup)
         return -EAGAIN;
 
     /*
      * We are already holding a reference to this inode from
      * write_cache_pages.  We need to hold it because the space reservation
      * takes place outside of the page lock, and we can't trust
      * page->mapping outside of the page lock.
      */
     ihold(inode);
     btrfs_page_set_checked(fs_info, page, page_offset(page), PAGE_SIZE);
     get_page(page);
     btrfs_init_work(&fixup->work, btrfs_writepage_fixup_worker, NULL, NULL);
     fixup->page = page;
     fixup->inode = inode;
     btrfs_queue_work(fs_info->fixup_workers, &fixup->work);
 
     return -EAGAIN;
 }
 
 static int insert_reserved_file_extent(struct btrfs_trans_handle *trans,
                        struct btrfs_inode *inode, u64 file_pos,
                        struct btrfs_file_extent_item *stack_fi,
                        const bool update_inode_bytes,
                        u64 qgroup_reserved)
 {
     struct btrfs_root *root = inode->root;
     const u64 sectorsize = root->fs_info->sectorsize;
     struct btrfs_path *path;
     struct extent_buffer *leaf;
     struct btrfs_key ins;
     u64 disk_num_bytes = btrfs_stack_file_extent_disk_num_bytes(stack_fi);
     u64 disk_bytenr = btrfs_stack_file_extent_disk_bytenr(stack_fi);
     u64 offset = btrfs_stack_file_extent_offset(stack_fi);
     u64 num_bytes = btrfs_stack_file_extent_num_bytes(stack_fi);
     u64 ram_bytes = btrfs_stack_file_extent_ram_bytes(stack_fi);
     struct btrfs_drop_extents_args drop_args = { 0 };
     int ret;
 
     path = btrfs_alloc_path();
     if (!path)
         return -ENOMEM;
 
     /*
      * we may be replacing one extent in the tree with another.
      * The new extent is pinned in the extent map, and we don't want
      * to drop it from the cache until it is completely in the btree.
      *
      * So, tell btrfs_drop_extents to leave this extent in the cache.
      * the caller is expected to unpin it and allow it to be merged
      * with the others.
      */
     drop_args.path = path;
     drop_args.start = file_pos;
     drop_args.end = file_pos + num_bytes;
     drop_args.replace_extent = true;
     drop_args.extent_item_size = sizeof(*stack_fi);
     ret = btrfs_drop_extents(trans, root, inode, &drop_args);
     if (ret)
         goto out;
 
     if (!drop_args.extent_inserted) {
         ins.objectid = btrfs_ino(inode);
         ins.offset = file_pos;
         ins.type = BTRFS_EXTENT_DATA_KEY;
 
         ret = btrfs_insert_empty_item(trans, root, path, &ins,
                           sizeof(*stack_fi));
         if (ret)
             goto out;
     }
     leaf = path->nodes[0];
     btrfs_set_stack_file_extent_generation(stack_fi, trans->transid);
     write_extent_buffer(leaf, stack_fi,
             btrfs_item_ptr_offset(leaf, path->slots[0]),
             sizeof(struct btrfs_file_extent_item));
 
     btrfs_mark_buffer_dirty(leaf);
     btrfs_release_path(path);
 
     /*
      * If we dropped an inline extent here, we know the range where it is
      * was not marked with the EXTENT_DELALLOC_NEW bit, so we update the
      * number of bytes only for that range containing the inline extent.
      * The remaining of the range will be processed when clearning the
      * EXTENT_DELALLOC_BIT bit through the ordered extent completion.
      */
     if (file_pos == 0 && !IS_ALIGNED(drop_args.bytes_found, sectorsize)) {
         u64 inline_size = round_down(drop_args.bytes_found, sectorsize);
 
         inline_size = drop_args.bytes_found - inline_size;
         btrfs_update_inode_bytes(inode, sectorsize, inline_size);
         drop_args.bytes_found -= inline_size;
         num_bytes -= sectorsize;
     }
 
     if (update_inode_bytes)
         btrfs_update_inode_bytes(inode, num_bytes, drop_args.bytes_found);
 
     ins.objectid = disk_bytenr;
     ins.offset = disk_num_bytes;
     ins.type = BTRFS_EXTENT_ITEM_KEY;
 
     ret = btrfs_inode_set_file_extent_range(inode, file_pos, ram_bytes);
     if (ret)
         goto out;
 
     ret = btrfs_alloc_reserved_file_extent(trans, root, btrfs_ino(inode),
                            file_pos - offset,
                            qgroup_reserved, &ins);
 out:
     btrfs_free_path(path);
 
     return ret;
 }
 
 static void btrfs_release_delalloc_bytes(struct btrfs_fs_info *fs_info,
                      u64 start, u64 len)
 {
     struct btrfs_block_group *cache;
 
     cache = btrfs_lookup_block_group(fs_info, start);
     ASSERT(cache);
 
     spin_lock(&cache->lock);
     cache->delalloc_bytes -= len;
     spin_unlock(&cache->lock);
 
     btrfs_put_block_group(cache);
 }
 
 static int insert_ordered_extent_file_extent(struct btrfs_trans_handle *trans,
                          struct btrfs_ordered_extent *oe)
 {
     struct btrfs_file_extent_item stack_fi;
     bool update_inode_bytes;
     u64 num_bytes = oe->num_bytes;
     u64 ram_bytes = oe->ram_bytes;
 
     memset(&stack_fi, 0, sizeof(stack_fi));
     btrfs_set_stack_file_extent_type(&stack_fi, BTRFS_FILE_EXTENT_REG);
     btrfs_set_stack_file_extent_disk_bytenr(&stack_fi, oe->disk_bytenr);
     btrfs_set_stack_file_extent_disk_num_bytes(&stack_fi,
                            oe->disk_num_bytes);
     btrfs_set_stack_file_extent_offset(&stack_fi, oe->offset);
     if (test_bit(BTRFS_ORDERED_TRUNCATED, &oe->flags)) {
         num_bytes = oe->truncated_len;
         ram_bytes = num_bytes;
     }
     btrfs_set_stack_file_extent_num_bytes(&stack_fi, num_bytes);
     btrfs_set_stack_file_extent_ram_bytes(&stack_fi, ram_bytes);
     btrfs_set_stack_file_extent_compression(&stack_fi, oe->compress_type);
     /* Encryption and other encoding is reserved and all 0 */
 
     /*
      * For delalloc, when completing an ordered extent we update the inode's
      * bytes when clearing the range in the inode's io tree, so pass false
      * as the argument 'update_inode_bytes' to insert_reserved_file_extent(),
      * except if the ordered extent was truncated.
      */
     update_inode_bytes = test_bit(BTRFS_ORDERED_DIRECT, &oe->flags) ||
                  test_bit(BTRFS_ORDERED_ENCODED, &oe->flags) ||
                  test_bit(BTRFS_ORDERED_TRUNCATED, &oe->flags);
 
     return insert_reserved_file_extent(trans, BTRFS_I(oe->inode),
                        oe->file_offset, &stack_fi,
                        update_inode_bytes, oe->qgroup_rsv);
 }
 
 /*
  * As ordered data IO finishes, this gets called so we can finish
  * an ordered extent if the range of bytes in the file it covers are
  * fully written.
  */
 int btrfs_finish_ordered_io(struct btrfs_ordered_extent *ordered_extent)
 {
     struct btrfs_inode *inode = BTRFS_I(ordered_extent->inode);
     struct btrfs_root *root = inode->root;
     struct btrfs_fs_info *fs_info = root->fs_info;
     struct btrfs_trans_handle *trans = NULL;
     struct extent_io_tree *io_tree = &inode->io_tree;
     struct extent_state *cached_state = NULL;
     u64 start, end;
     int compress_type = 0;
     int ret = 0;
     u64 logical_len = ordered_extent->num_bytes;
     bool freespace_inode;
     bool truncated = false;
     bool clear_reserved_extent = true;
     unsigned int clear_bits = EXTENT_DEFRAG;
 
     start = ordered_extent->file_offset;
     end = start + ordered_extent->num_bytes - 1;
 
     if (!test_bit(BTRFS_ORDERED_NOCOW, &ordered_extent->flags) &&
         !test_bit(BTRFS_ORDERED_PREALLOC, &ordered_extent->flags) &&
         !test_bit(BTRFS_ORDERED_DIRECT, &ordered_extent->flags) &&
         !test_bit(BTRFS_ORDERED_ENCODED, &ordered_extent->flags))
         clear_bits |= EXTENT_DELALLOC_NEW;
 
     freespace_inode = btrfs_is_free_space_inode(inode);
 
     if (test_bit(BTRFS_ORDERED_IOERR, &ordered_extent->flags)) {
         ret = -EIO;
         goto out;
     }
 
     /* A valid bdev implies a write on a sequential zone */
     if (ordered_extent->bdev) {
         btrfs_rewrite_logical_zoned(ordered_extent);
         btrfs_zone_finish_endio(fs_info, ordered_extent->disk_bytenr,
                     ordered_extent->disk_num_bytes);
     }
 
     btrfs_free_io_failure_record(inode, start, end);
 
     if (test_bit(BTRFS_ORDERED_TRUNCATED, &ordered_extent->flags)) {
         truncated = true;
         logical_len = ordered_extent->truncated_len;
         /* Truncated the entire extent, don't bother adding */
         if (!logical_len)
             goto out;
     }
 
     if (test_bit(BTRFS_ORDERED_NOCOW, &ordered_extent->flags)) {
         BUG_ON(!list_empty(&ordered_extent->list)); /* Logic error */
 
         btrfs_inode_safe_disk_i_size_write(inode, 0);
         if (freespace_inode)
             trans = btrfs_join_transaction_spacecache(root);
         else
             trans = btrfs_join_transaction(root);
         if (IS_ERR(trans)) {
             ret = PTR_ERR(trans);
             trans = NULL;
             goto out;
         }
         trans->block_rsv = &inode->block_rsv;
         ret = btrfs_update_inode_fallback(trans, root, inode);
         if (ret) /* -ENOMEM or corruption */
             btrfs_abort_transaction(trans, ret);
         goto out;
     }
 
     clear_bits |= EXTENT_LOCKED;
     lock_extent_bits(io_tree, start, end, &cached_state);
 
     if (freespace_inode)
         trans = btrfs_join_transaction_spacecache(root);
     else
         trans = btrfs_join_transaction(root);
     if (IS_ERR(trans)) {
         ret = PTR_ERR(trans);
         trans = NULL;
         goto out;
     }
 
     trans->block_rsv = &inode->block_rsv;
 
     if (test_bit(BTRFS_ORDERED_COMPRESSED, &ordered_extent->flags))
         compress_type = ordered_extent->compress_type;
     if (test_bit(BTRFS_ORDERED_PREALLOC, &ordered_extent->flags)) {
         BUG_ON(compress_type);
         ret = btrfs_mark_extent_written(trans, inode,
                         ordered_extent->file_offset,
                         ordered_extent->file_offset +
                         logical_len);
         btrfs_zoned_release_data_reloc_bg(fs_info, ordered_extent->disk_bytenr,
                           ordered_extent->disk_num_bytes);
     } else {
         BUG_ON(root == fs_info->tree_root);
         ret = insert_ordered_extent_file_extent(trans, ordered_extent);
         if (!ret) {
             clear_reserved_extent = false;
             btrfs_release_delalloc_bytes(fs_info,
                         ordered_extent->disk_bytenr,
                         ordered_extent->disk_num_bytes);
         }
     }
     unpin_extent_cache(&inode->extent_tree, ordered_extent->file_offset,
                ordered_extent->num_bytes, trans->transid);
     if (ret < 0) {
         btrfs_abort_transaction(trans, ret);
         goto out;
     }
 
     ret = add_pending_csums(trans, &ordered_extent->list);
     if (ret) {
         btrfs_abort_transaction(trans, ret);
         goto out;
     }
 
     /*
      * If this is a new delalloc range, clear its new delalloc flag to
      * update the inode's number of bytes. This needs to be done first
      * before updating the inode item.
      */
     if ((clear_bits & EXTENT_DELALLOC_NEW) &&
         !test_bit(BTRFS_ORDERED_TRUNCATED, &ordered_extent->flags))
         clear_extent_bit(&inode->io_tree, start, end,
                  EXTENT_DELALLOC_NEW | EXTENT_ADD_INODE_BYTES,
                  0, 0, &cached_state);
 
     btrfs_inode_safe_disk_i_size_write(inode, 0);
     ret = btrfs_update_inode_fallback(trans, root, inode);
     if (ret) { /* -ENOMEM or corruption */
         btrfs_abort_transaction(trans, ret);
         goto out;
     }
     ret = 0;
 out:
     clear_extent_bit(&inode->io_tree, start, end, clear_bits,
              (clear_bits & EXTENT_LOCKED) ? 1 : 0, 0,
              &cached_state);
 
     if (trans)
         btrfs_end_transaction(trans);
 
     if (ret || truncated) {
         u64 unwritten_start = start;
 
         /*
          * If we failed to finish this ordered extent for any reason we
          * need to make sure BTRFS_ORDERED_IOERR is set on the ordered
          * extent, and mark the inode with the error if it wasn't
          * already set.  Any error during writeback would have already
          * set the mapping error, so we need to set it if we're the ones
          * marking this ordered extent as failed.
          */
         if (ret && !test_and_set_bit(BTRFS_ORDERED_IOERR,
                          &ordered_extent->flags))
             mapping_set_error(ordered_extent->inode->i_mapping, -EIO);
 
         if (truncated)
             unwritten_start += logical_len;
         clear_extent_uptodate(io_tree, unwritten_start, end, NULL);
 
         /* Drop the cache for the part of the extent we didn't write. */
         btrfs_drop_extent_cache(inode, unwritten_start, end, 0);
 
         /*
          * If the ordered extent had an IOERR or something else went
          * wrong we need to return the space for this ordered extent
          * back to the allocator.  We only free the extent in the
          * truncated case if we didn't write out the extent at all.
          *
          * If we made it past insert_reserved_file_extent before we
          * errored out then we don't need to do this as the accounting
          * has already been done.
          */
         if ((ret || !logical_len) &&
             clear_reserved_extent &&
             !test_bit(BTRFS_ORDERED_NOCOW, &ordered_extent->flags) &&
             !test_bit(BTRFS_ORDERED_PREALLOC, &ordered_extent->flags)) {
             /*
              * Discard the range before returning it back to the
              * free space pool
              */
             if (ret && btrfs_test_opt(fs_info, DISCARD_SYNC))
                 btrfs_discard_extent(fs_info,
                         ordered_extent->disk_bytenr,
                         ordered_extent->disk_num_bytes,
                         NULL);
             btrfs_free_reserved_extent(fs_info,
                     ordered_extent->disk_bytenr,
                     ordered_extent->disk_num_bytes, 1);
         }
     }
 
     /*
      * This needs to be done to make sure anybody waiting knows we are done
      * updating everything for this ordered extent.
      */
     btrfs_remove_ordered_extent(inode, ordered_extent);
 
     /* once for us */
     btrfs_put_ordered_extent(ordered_extent);
     /* once for the tree */
     btrfs_put_ordered_extent(ordered_extent);
 
     return ret;
 }
 
 void btrfs_writepage_endio_finish_ordered(struct btrfs_inode *inode,
                       struct page *page, u64 start,
                       u64 end, bool uptodate)
 {
     trace_btrfs_writepage_end_io_hook(inode, start, end, uptodate);
 
     btrfs_mark_ordered_io_finished(inode, page, start, end + 1 - start, uptodate);
 }
 
 /*
  * Verify the checksum for a single sector without any extra action that depend
  * on the type of I/O.
  */
 int btrfs_check_sector_csum(struct btrfs_fs_info *fs_info, struct page *page,
                 u32 pgoff, u8 *csum, const u8 * const csum_expected)
 {
     SHASH_DESC_ON_STACK(shash, fs_info->csum_shash);
     char *kaddr;
 
     ASSERT(pgoff + fs_info->sectorsize <= PAGE_SIZE);
 
     shash->tfm = fs_info->csum_shash;
 
     kaddr = kmap_local_page(page) + pgoff;
     crypto_shash_digest(shash, kaddr, fs_info->sectorsize, csum);
     kunmap_local(kaddr);
 
     if (memcmp(csum, csum_expected, fs_info->csum_size))
         return -EIO;
     return 0;
 }
 
 /*
  * check_data_csum - verify checksum of one sector of uncompressed data
  * @inode:  inode
  * @bbio:   btrfs_bio which contains the csum
  * @bio_offset: offset to the beginning of the bio (in bytes)
  * @page:   page where is the data to be verified
  * @pgoff:  offset inside the page
  *
  * The length of such check is always one sector size.
  *
  * When csum mismatch is detected, we will also report the error and fill the
  * corrupted range with zero. (Thus it needs the extra parameters)
  */
 int btrfs_check_data_csum(struct inode *inode, struct btrfs_bio *bbio,
               u32 bio_offset, struct page *page, u32 pgoff)
 {
     struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
     u32 len = fs_info->sectorsize;
     u8 *csum_expected;
     u8 csum[BTRFS_CSUM_SIZE];
 
     ASSERT(pgoff + len <= PAGE_SIZE);
 
     csum_expected = btrfs_csum_ptr(fs_info, bbio->csum, bio_offset);
 
     if (btrfs_check_sector_csum(fs_info, page, pgoff, csum, csum_expected))
         goto zeroit;
     return 0;
 
 zeroit:
     btrfs_print_data_csum_error(BTRFS_I(inode),
                     bbio->file_offset + bio_offset,
                     csum, csum_expected, bbio->mirror_num);
     if (bbio->device)
         btrfs_dev_stat_inc_and_print(bbio->device,
                          BTRFS_DEV_STAT_CORRUPTION_ERRS);
     memzero_page(page, pgoff, len);
     return -EIO;
 }
 
 /*
  * When reads are done, we need to check csums to verify the data is correct.
  * if there's a match, we allow the bio to finish.  If not, the code in
  * extent_io.c will try to find good copies for us.
  *
  * @bio_offset: offset to the beginning of the bio (in bytes)
  * @start:  file offset of the range start
  * @end:    file offset of the range end (inclusive)
  *
  * Return a bitmap where bit set means a csum mismatch, and bit not set means
  * csum match.
  */
 unsigned int btrfs_verify_data_csum(struct btrfs_bio *bbio,
                     u32 bio_offset, struct page *page,
                     u64 start, u64 end)
 {
     struct inode *inode = page->mapping->host;
     struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
     struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
     struct btrfs_root *root = BTRFS_I(inode)->root;
     const u32 sectorsize = root->fs_info->sectorsize;
     u32 pg_off;
     unsigned int result = 0;
 
     /*
      * This only happens for NODATASUM or compressed read.
      * Normally this should be covered by above check for compressed read
      * or the next check for NODATASUM.  Just do a quicker exit here.
      */
     if (bbio->csum == NULL)
         return 0;
 
     if (BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)
         return 0;
 
     if (unlikely(test_bit(BTRFS_FS_STATE_NO_CSUMS, &fs_info->fs_state)))
         return 0;
 
     ASSERT(page_offset(page) <= start &&
            end <= page_offset(page) + PAGE_SIZE - 1);
     for (pg_off = offset_in_page(start);
          pg_off < offset_in_page(end);
          pg_off += sectorsize, bio_offset += sectorsize) {
         u64 file_offset = pg_off + page_offset(page);
         int ret;
 
         if (btrfs_is_data_reloc_root(root) &&
             test_range_bit(io_tree, file_offset,
                    file_offset + sectorsize - 1,
                    EXTENT_NODATASUM, 1, NULL)) {
             /* Skip the range without csum for data reloc inode */
             clear_extent_bits(io_tree, file_offset,
                       file_offset + sectorsize - 1,
                       EXTENT_NODATASUM);
             continue;
         }
         ret = btrfs_check_data_csum(inode, bbio, bio_offset, page, pg_off);
         if (ret < 0) {
             const int nr_bit = (pg_off - offset_in_page(start)) >>
                      root->fs_info->sectorsize_bits;
 
             result |= (1U << nr_bit);
         }
     }
     return result;
 }
 
 /*
  * btrfs_add_delayed_iput - perform a delayed iput on @inode
  *
  * @inode: The inode we want to perform iput on
  *
  * This function uses the generic vfs_inode::i_count to track whether we should
  * just decrement it (in case it's > 1) or if this is the last iput then link
  * the inode to the delayed iput machinery. Delayed iputs are processed at
  * transaction commit time/superblock commit/cleaner kthread.
  */
 void btrfs_add_delayed_iput(struct inode *inode)
 {
     struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
     struct btrfs_inode *binode = BTRFS_I(inode);
 
     if (atomic_add_unless(&inode->i_count, -1, 1))
         return;
 
     atomic_inc(&fs_info->nr_delayed_iputs);
     spin_lock(&fs_info->delayed_iput_lock);
     ASSERT(list_empty(&binode->delayed_iput));
     list_add_tail(&binode->delayed_iput, &fs_info->delayed_iputs);
     spin_unlock(&fs_info->delayed_iput_lock);
     if (!test_bit(BTRFS_FS_CLEANER_RUNNING, &fs_info->flags))
         wake_up_process(fs_info->cleaner_kthread);
 }
 
 static void run_delayed_iput_locked(struct btrfs_fs_info *fs_info,
                     struct btrfs_inode *inode)
 {
     list_del_init(&inode->delayed_iput);
     spin_unlock(&fs_info->delayed_iput_lock);
     iput(&inode->vfs_inode);
     if (atomic_dec_and_test(&fs_info->nr_delayed_iputs))
         wake_up(&fs_info->delayed_iputs_wait);
     spin_lock(&fs_info->delayed_iput_lock);
 }
 
 static void btrfs_run_delayed_iput(struct btrfs_fs_info *fs_info,
                    struct btrfs_inode *inode)
 {
     if (!list_empty(&inode->delayed_iput)) {
         spin_lock(&fs_info->delayed_iput_lock);
         if (!list_empty(&inode->delayed_iput))
             run_delayed_iput_locked(fs_info, inode);
         spin_unlock(&fs_info->delayed_iput_lock);
     }
 }
 
 void btrfs_run_delayed_iputs(struct btrfs_fs_info *fs_info)
 {
 
     spin_lock(&fs_info->delayed_iput_lock);
     while (!list_empty(&fs_info->delayed_iputs)) {
         struct btrfs_inode *inode;
 
         inode = list_first_entry(&fs_info->delayed_iputs,
                 struct btrfs_inode, delayed_iput);
         run_delayed_iput_locked(fs_info, inode);
         cond_resched_lock(&fs_info->delayed_iput_lock);
     }
     spin_unlock(&fs_info->delayed_iput_lock);
 }
 
 /**
  * Wait for flushing all delayed iputs
  *
  * @fs_info:  the filesystem
  *
  * This will wait on any delayed iputs that are currently running with KILLABLE
  * set.  Once they are all done running we will return, unless we are killed in
  * which case we return EINTR. This helps in user operations like fallocate etc
  * that might get blocked on the iputs.
  *
  * Return EINTR if we were killed, 0 if nothing's pending
  */
 int btrfs_wait_on_delayed_iputs(struct btrfs_fs_info *fs_info)
 {
     int ret = wait_event_killable(fs_info->delayed_iputs_wait,
             atomic_read(&fs_info->nr_delayed_iputs) == 0);
     if (ret)
         return -EINTR;
     return 0;
 }
 
 /*
  * This creates an orphan entry for the given inode in case something goes wrong
  * in the middle of an unlink.
  */
 int btrfs_orphan_add(struct btrfs_trans_handle *trans,
              struct btrfs_inode *inode)
 {
     int ret;
 
     ret = btrfs_insert_orphan_item(trans, inode->root, btrfs_ino(inode));
     if (ret && ret != -EEXIST) {
         btrfs_abort_transaction(trans, ret);
         return ret;
     }
 
     return 0;
 }
 
 /*
  * We have done the delete so we can go ahead and remove the orphan item for
  * this particular inode.
  */
 static int btrfs_orphan_del(struct btrfs_trans_handle *trans,
                 struct btrfs_inode *inode)
 {
     return btrfs_del_orphan_item(trans, inode->root, btrfs_ino(inode));
 }
 
 /*
  * this cleans up any orphans that may be left on the list from the last use
  * of this root.
  */
 int btrfs_orphan_cleanup(struct btrfs_root *root)
 {
     struct btrfs_fs_info *fs_info = root->fs_info;
     struct btrfs_path *path;
     struct extent_buffer *leaf;
     struct btrfs_key key, found_key;
     struct btrfs_trans_handle *trans;
     struct inode *inode;
     u64 last_objectid = 0;
     int ret = 0, nr_unlink = 0;
 
     if (test_and_set_bit(BTRFS_ROOT_ORPHAN_CLEANUP, &root->state))
         return 0;
 
     path = btrfs_alloc_path();
     if (!path) {
         ret = -ENOMEM;
         goto out;
     }
     path->reada = READA_BACK;
 
     key.objectid = BTRFS_ORPHAN_OBJECTID;
     key.type = BTRFS_ORPHAN_ITEM_KEY;
     key.offset = (u64)-1;
 
     while (1) {
         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
         if (ret < 0)
             goto out;
 
         /*
          * if ret == 0 means we found what we were searching for, which
          * is weird, but possible, so only screw with path if we didn't
          * find the key and see if we have stuff that matches
          */
         if (ret > 0) {
             ret = 0;
             if (path->slots[0] == 0)
                 break;
             path->slots[0]--;
         }
 
         /* pull out the item */
         leaf = path->nodes[0];
         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 
         /* make sure the item matches what we want */
         if (found_key.objectid != BTRFS_ORPHAN_OBJECTID)
             break;
         if (found_key.type != BTRFS_ORPHAN_ITEM_KEY)
             break;
 
         /* release the path since we're done with it */
         btrfs_release_path(path);
 
         /*
          * this is where we are basically btrfs_lookup, without the
          * crossing root thing.  we store the inode number in the
          * offset of the orphan item.
          */
 
         if (found_key.offset == last_objectid) {
             btrfs_err(fs_info,
                   "Error removing orphan entry, stopping orphan cleanup");
             ret = -EINVAL;
             goto out;
         }
 
         last_objectid = found_key.offset;
 
         found_key.objectid = found_key.offset;
         found_key.type = BTRFS_INODE_ITEM_KEY;
         found_key.offset = 0;
         inode = btrfs_iget(fs_info->sb, last_objectid, root);
         ret = PTR_ERR_OR_ZERO(inode);
         if (ret && ret != -ENOENT)
             goto out;
 
         if (ret == -ENOENT && root == fs_info->tree_root) {
             struct btrfs_root *dead_root;
             int is_dead_root = 0;
 
             /*
              * This is an orphan in the tree root. Currently these
              * could come from 2 sources:
              *  a) a root (snapshot/subvolume) deletion in progress
              *  b) a free space cache inode
              * We need to distinguish those two, as the orphan item
              * for a root must not get deleted before the deletion
              * of the snapshot/subvolume's tree completes.
              *
              * btrfs_find_orphan_roots() ran before us, which has
              * found all deleted roots and loaded them into
              * fs_info->fs_roots_radix. So here we can find if an
              * orphan item corresponds to a deleted root by looking
              * up the root from that radix tree.
              */
 
             spin_lock(&fs_info->fs_roots_radix_lock);
             dead_root = radix_tree_lookup(&fs_info->fs_roots_radix,
                              (unsigned long)found_key.objectid);
             if (dead_root && btrfs_root_refs(&dead_root->root_item) == 0)
                 is_dead_root = 1;
             spin_unlock(&fs_info->fs_roots_radix_lock);
 
             if (is_dead_root) {
                 /* prevent this orphan from being found again */
                 key.offset = found_key.objectid - 1;
                 continue;
             }
 
         }
 
         /*
          * If we have an inode with links, there are a couple of
          * possibilities:
          *
          * 1. We were halfway through creating fsverity metadata for the
          * file. In that case, the orphan item represents incomplete
          * fsverity metadata which must be cleaned up with
          * btrfs_drop_verity_items and deleting the orphan item.
 
          * 2. Old kernels (before v3.12) used to create an
          * orphan item for truncate indicating that there were possibly
          * extent items past i_size that needed to be deleted. In v3.12,
          * truncate was changed to update i_size in sync with the extent
          * items, but the (useless) orphan item was still created. Since
          * v4.18, we don't create the orphan item for truncate at all.
          *
          * So, this item could mean that we need to do a truncate, but
          * only if this filesystem was last used on a pre-v3.12 kernel
          * and was not cleanly unmounted. The odds of that are quite
          * slim, and it's a pain to do the truncate now, so just delete
          * the orphan item.
          *
          * It's also possible that this orphan item was supposed to be
          * deleted but wasn't. The inode number may have been reused,
          * but either way, we can delete the orphan item.
          */
         if (ret == -ENOENT || inode->i_nlink) {
             if (!ret) {
                 ret = btrfs_drop_verity_items(BTRFS_I(inode));
                 iput(inode);
                 if (ret)
                     goto out;
             }
             trans = btrfs_start_transaction(root, 1);
             if (IS_ERR(trans)) {
                 ret = PTR_ERR(trans);
                 goto out;
             }
             btrfs_debug(fs_info, "auto deleting %Lu",
                     found_key.objectid);
             ret = btrfs_del_orphan_item(trans, root,
                             found_key.objectid);
             btrfs_end_transaction(trans);
             if (ret)
                 goto out;
             continue;
         }
 
         nr_unlink++;
 
         /* this will do delete_inode and everything for us */
         iput(inode);
     }
     /* release the path since we're done with it */
     btrfs_release_path(path);
 
     if (test_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED, &root->state)) {
         trans = btrfs_join_transaction(root);
         if (!IS_ERR(trans))
             btrfs_end_transaction(trans);
     }
 
     if (nr_unlink)
         btrfs_debug(fs_info, "unlinked %d orphans", nr_unlink);
 
 out:
     if (ret)
         btrfs_err(fs_info, "could not do orphan cleanup %d", ret);
     btrfs_free_path(path);
     return ret;
 }
 
 /*
  * very simple check to peek ahead in the leaf looking for xattrs.  If we
  * don't find any xattrs, we know there can't be any acls.
  *
  * slot is the slot the inode is in, objectid is the objectid of the inode
  */
 static noinline int acls_after_inode_item(struct extent_buffer *leaf,
                       int slot, u64 objectid,
                       int *first_xattr_slot)
 {
     u32 nritems = btrfs_header_nritems(leaf);
     struct btrfs_key found_key;
     static u64 xattr_access = 0;
     static u64 xattr_default = 0;
     int scanned = 0;
 
     if (!xattr_access) {
         xattr_access = btrfs_name_hash(XATTR_NAME_POSIX_ACL_ACCESS,
                     strlen(XATTR_NAME_POSIX_ACL_ACCESS));
         xattr_default = btrfs_name_hash(XATTR_NAME_POSIX_ACL_DEFAULT,
                     strlen(XATTR_NAME_POSIX_ACL_DEFAULT));
     }
 
     slot++;
     *first_xattr_slot = -1;
     while (slot < nritems) {
         btrfs_item_key_to_cpu(leaf, &found_key, slot);
 
         /* we found a different objectid, there must not be acls */
         if (found_key.objectid != objectid)
             return 0;
 
         /* we found an xattr, assume we've got an acl */
         if (found_key.type == BTRFS_XATTR_ITEM_KEY) {
             if (*first_xattr_slot == -1)
                 *first_xattr_slot = slot;
             if (found_key.offset == xattr_access ||
                 found_key.offset == xattr_default)
                 return 1;
         }
 
         /*
          * we found a key greater than an xattr key, there can't
          * be any acls later on
          */
         if (found_key.type > BTRFS_XATTR_ITEM_KEY)
             return 0;
 
         slot++;
         scanned++;
 
         /*
          * it goes inode, inode backrefs, xattrs, extents,
          * so if there are a ton of hard links to an inode there can
          * be a lot of backrefs.  Don't waste time searching too hard,
          * this is just an optimization
          */
         if (scanned >= 8)
             break;
     }
     /* we hit the end of the leaf before we found an xattr or
      * something larger than an xattr.  We have to assume the inode
      * has acls
      */
     if (*first_xattr_slot == -1)
         *first_xattr_slot = slot;
     return 1;
 }
 
 /*
  * read an inode from the btree into the in-memory inode
  */
 static int btrfs_read_locked_inode(struct inode *inode,
                    struct btrfs_path *in_path)
 {
     struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
     struct btrfs_path *path = in_path;
     struct extent_buffer *leaf;
     struct btrfs_inode_item *inode_item;
     struct btrfs_root *root = BTRFS_I(inode)->root;
     struct btrfs_key location;
     unsigned long ptr;
     int maybe_acls;
     u32 rdev;
     int ret;
     bool filled = false;
     int first_xattr_slot;
 
     ret = btrfs_fill_inode(inode, &rdev);
     if (!ret)
         filled = true;
 
     if (!path) {
         path = btrfs_alloc_path();
         if (!path)
             return -ENOMEM;
     }
 
     memcpy(&location, &BTRFS_I(inode)->location, sizeof(location));
 
     ret = btrfs_lookup_inode(NULL, root, path, &location, 0);
     if (ret) {
         if (path != in_path)
             btrfs_free_path(path);
         return ret;
     }
 
     leaf = path->nodes[0];
 
     if (filled)
         goto cache_index;
 
     inode_item = btrfs_item_ptr(leaf, path->slots[0],
                     struct btrfs_inode_item);
     inode->i_mode = btrfs_inode_mode(leaf, inode_item);
     set_nlink(inode, btrfs_inode_nlink(leaf, inode_item));
     i_uid_write(inode, btrfs_inode_uid(leaf, inode_item));
     i_gid_write(inode, btrfs_inode_gid(leaf, inode_item));
     btrfs_i_size_write(BTRFS_I(inode), btrfs_inode_size(leaf, inode_item));
     btrfs_inode_set_file_extent_range(BTRFS_I(inode), 0,
             round_up(i_size_read(inode), fs_info->sectorsize));
 
     inode->i_atime.tv_sec = btrfs_timespec_sec(leaf, &inode_item->atime);
     inode->i_atime.tv_nsec = btrfs_timespec_nsec(leaf, &inode_item->atime);
 
     inode->i_mtime.tv_sec = btrfs_timespec_sec(leaf, &inode_item->mtime);
     inode->i_mtime.tv_nsec = btrfs_timespec_nsec(leaf, &inode_item->mtime);
 
     inode->i_ctime.tv_sec = btrfs_timespec_sec(leaf, &inode_item->ctime);
     inode->i_ctime.tv_nsec = btrfs_timespec_nsec(leaf, &inode_item->ctime);
 
     BTRFS_I(inode)->i_otime.tv_sec =
         btrfs_timespec_sec(leaf, &inode_item->otime);
     BTRFS_I(inode)->i_otime.tv_nsec =
         btrfs_timespec_nsec(leaf, &inode_item->otime);
 
     inode_set_bytes(inode, btrfs_inode_nbytes(leaf, inode_item));
     BTRFS_I(inode)->generation = btrfs_inode_generation(leaf, inode_item);
     BTRFS_I(inode)->last_trans = btrfs_inode_transid(leaf, inode_item);
 
     inode_set_iversion_queried(inode,
                    btrfs_inode_sequence(leaf, inode_item));
     inode->i_generation = BTRFS_I(inode)->generation;
     inode->i_rdev = 0;
     rdev = btrfs_inode_rdev(leaf, inode_item);
 
     BTRFS_I(inode)->index_cnt = (u64)-1;
     btrfs_inode_split_flags(btrfs_inode_flags(leaf, inode_item),
                 &BTRFS_I(inode)->flags, &BTRFS_I(inode)->ro_flags);
 
 cache_index:
     /*
      * If we were modified in the current generation and evicted from memory
      * and then re-read we need to do a full sync since we don't have any
      * idea about which extents were modified before we were evicted from
      * cache.
      *
      * This is required for both inode re-read from disk and delayed inode
      * in delayed_nodes_tree.
      */
     if (BTRFS_I(inode)->last_trans == fs_info->generation)
         set_bit(BTRFS_INODE_NEEDS_FULL_SYNC,
             &BTRFS_I(inode)->runtime_flags);
 
     /*
      * We don't persist the id of the transaction where an unlink operation
      * against the inode was last made. So here we assume the inode might
      * have been evicted, and therefore the exact value of last_unlink_trans
      * lost, and set it to last_trans to avoid metadata inconsistencies
      * between the inode and its parent if the inode is fsync'ed and the log
      * replayed. For example, in the scenario:
      *
      * touch mydir/foo
      * ln mydir/foo mydir/bar
      * sync
      * unlink mydir/bar
      * echo 2 > /proc/sys/vm/drop_caches   # evicts inode
      * xfs_io -c fsync mydir/foo
      * <power failure>
      * mount fs, triggers fsync log replay
      *
      * We must make sure that when we fsync our inode foo we also log its
      * parent inode, otherwise after log replay the parent still has the
      * dentry with the "bar" name but our inode foo has a link count of 1
      * and doesn't have an inode ref with the name "bar" anymore.
      *
      * Setting last_unlink_trans to last_trans is a pessimistic approach,
      * but it guarantees correctness at the expense of occasional full
      * transaction commits on fsync if our inode is a directory, or if our
      * inode is not a directory, logging its parent unnecessarily.
      */
     BTRFS_I(inode)->last_unlink_trans = BTRFS_I(inode)->last_trans;
 
     /*
      * Same logic as for last_unlink_trans. We don't persist the generation
      * of the last transaction where this inode was used for a reflink
      * operation, so after eviction and reloading the inode we must be
      * pessimistic and assume the last transaction that modified the inode.
      */
     BTRFS_I(inode)->last_reflink_trans = BTRFS_I(inode)->last_trans;
 
     path->slots[0]++;
     if (inode->i_nlink != 1 ||
         path->slots[0] >= btrfs_header_nritems(leaf))
         goto cache_acl;
 
     btrfs_item_key_to_cpu(leaf, &location, path->slots[0]);
     if (location.objectid != btrfs_ino(BTRFS_I(inode)))
         goto cache_acl;
 
     ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
     if (location.type == BTRFS_INODE_REF_KEY) {
         struct btrfs_inode_ref *ref;
 
         ref = (struct btrfs_inode_ref *)ptr;
         BTRFS_I(inode)->dir_index = btrfs_inode_ref_index(leaf, ref);
     } else if (location.type == BTRFS_INODE_EXTREF_KEY) {
         struct btrfs_inode_extref *extref;
 
         extref = (struct btrfs_inode_extref *)ptr;
         BTRFS_I(inode)->dir_index = btrfs_inode_extref_index(leaf,
                                      extref);
     }
 cache_acl:
     /*
      * try to precache a NULL acl entry for files that don't have
      * any xattrs or acls
      */
     maybe_acls = acls_after_inode_item(leaf, path->slots[0],
             btrfs_ino(BTRFS_I(inode)), &first_xattr_slot);
     if (first_xattr_slot != -1) {
         path->slots[0] = first_xattr_slot;
         ret = btrfs_load_inode_props(inode, path);
         if (ret)
             btrfs_err(fs_info,
                   "error loading props for ino %llu (root %llu): %d",
                   btrfs_ino(BTRFS_I(inode)),
                   root->root_key.objectid, ret);
     }
     if (path != in_path)
         btrfs_free_path(path);
 
     if (!maybe_acls)
         cache_no_acl(inode);
 
     switch (inode->i_mode & S_IFMT) {
     case S_IFREG:
         inode->i_mapping->a_ops = &btrfs_aops;
         inode->i_fop = &btrfs_file_operations;
         inode->i_op = &btrfs_file_inode_operations;
         break;
     case S_IFDIR:
         inode->i_fop = &btrfs_dir_file_operations;
         inode->i_op = &btrfs_dir_inode_operations;
         break;
     case S_IFLNK:
         inode->i_op = &btrfs_symlink_inode_operations;
         inode_nohighmem(inode);
         inode->i_mapping->a_ops = &btrfs_aops;
         break;
     default:
         inode->i_op = &btrfs_special_inode_operations;
         init_special_inode(inode, inode->i_mode, rdev);
         break;
     }
 
     btrfs_sync_inode_flags_to_i_flags(inode);
     return 0;
 }
 
 /*
  * given a leaf and an inode, copy the inode fields into the leaf
  */
 static void fill_inode_item(struct btrfs_trans_handle *trans,
                 struct extent_buffer *leaf,
                 struct btrfs_inode_item *item,
                 struct inode *inode)
 {
     struct btrfs_map_token token;
     u64 flags;
 
     btrfs_init_map_token(&token, leaf);
 
     btrfs_set_token_inode_uid(&token, item, i_uid_read(inode));
     btrfs_set_token_inode_gid(&token, item, i_gid_read(inode));
     btrfs_set_token_inode_size(&token, item, BTRFS_I(inode)->disk_i_size);
     btrfs_set_token_inode_mode(&token, item, inode->i_mode);
     btrfs_set_token_inode_nlink(&token, item, inode->i_nlink);
 
     btrfs_set_token_timespec_sec(&token, &item->atime,
                      inode->i_atime.tv_sec);
     btrfs_set_token_timespec_nsec(&token, &item->atime,
                       inode->i_atime.tv_nsec);
 
     btrfs_set_token_timespec_sec(&token, &item->mtime,
                      inode->i_mtime.tv_sec);
     btrfs_set_token_timespec_nsec(&token, &item->mtime,
                       inode->i_mtime.tv_nsec);
 
     btrfs_set_token_timespec_sec(&token, &item->ctime,
                      inode->i_ctime.tv_sec);
     btrfs_set_token_timespec_nsec(&token, &item->ctime,
                       inode->i_ctime.tv_nsec);
 
     btrfs_set_token_timespec_sec(&token, &item->otime,
                      BTRFS_I(inode)->i_otime.tv_sec);
     btrfs_set_token_timespec_nsec(&token, &item->otime,
                       BTRFS_I(inode)->i_otime.tv_nsec);
 
     btrfs_set_token_inode_nbytes(&token, item, inode_get_bytes(inode));
     btrfs_set_token_inode_generation(&token, item,
                      BTRFS_I(inode)->generation);
     btrfs_set_token_inode_sequence(&token, item, inode_peek_iversion(inode));
     btrfs_set_token_inode_transid(&token, item, trans->transid);
     btrfs_set_token_inode_rdev(&token, item, inode->i_rdev);
     flags = btrfs_inode_combine_flags(BTRFS_I(inode)->flags,
                       BTRFS_I(inode)->ro_flags);
     btrfs_set_token_inode_flags(&token, item, flags);
     btrfs_set_token_inode_block_group(&token, item, 0);
 }
 
 /*
  * copy everything in the in-memory inode into the btree.
  */
 static noinline int btrfs_update_inode_item(struct btrfs_trans_handle *trans,
                 struct btrfs_root *root,
                 struct btrfs_inode *inode)
 {
     struct btrfs_inode_item *inode_item;
     struct btrfs_path *path;
     struct extent_buffer *leaf;
     int ret;
 
     path = btrfs_alloc_path();
     if (!path)
         return -ENOMEM;
 
     ret = btrfs_lookup_inode(trans, root, path, &inode->location, 1);
     if (ret) {
         if (ret > 0)
             ret = -ENOENT;
         goto failed;
     }
 
     leaf = path->nodes[0];
     inode_item = btrfs_item_ptr(leaf, path->slots[0],
                     struct btrfs_inode_item);
 
     fill_inode_item(trans, leaf, inode_item, &inode->vfs_inode);
     btrfs_mark_buffer_dirty(leaf);
     btrfs_set_inode_last_trans(trans, inode);
     ret = 0;
 failed:
     btrfs_free_path(path);
     return ret;
 }
 
 /*
  * copy everything in the in-memory inode into the btree.
  */
 noinline int btrfs_update_inode(struct btrfs_trans_handle *trans,
                 struct btrfs_root *root,
                 struct btrfs_inode *inode)
 {
     struct btrfs_fs_info *fs_info = root->fs_info;
     int ret;
 
     /*
      * If the inode is a free space inode, we can deadlock during commit
      * if we put it into the delayed code.
      *
      * The data relocation inode should also be directly updated
      * without delay
      */
     if (!btrfs_is_free_space_inode(inode)
         && !btrfs_is_data_reloc_root(root)
         && !test_bit(BTRFS_FS_LOG_RECOVERING, &fs_info->flags)) {
         btrfs_update_root_times(trans, root);
 
         ret = btrfs_delayed_update_inode(trans, root, inode);
         if (!ret)
             btrfs_set_inode_last_trans(trans, inode);
         return ret;
     }
 
     return btrfs_update_inode_item(trans, root, inode);
 }
 
 int btrfs_update_inode_fallback(struct btrfs_trans_handle *trans,
                 struct btrfs_root *root, struct btrfs_inode *inode)
 {
     int ret;
 
     ret = btrfs_update_inode(trans, root, inode);
     if (ret == -ENOSPC)
         return btrfs_update_inode_item(trans, root, inode);
     return ret;
 }
 
 /*
  * unlink helper that gets used here in inode.c and in the tree logging
  * recovery code.  It remove a link in a directory with a given name, and
  * also drops the back refs in the inode to the directory
  */
 static int __btrfs_unlink_inode(struct btrfs_trans_handle *trans,
                 struct btrfs_inode *dir,
                 struct btrfs_inode *inode,
                 const char *name, int name_len,
                 struct btrfs_rename_ctx *rename_ctx)
 {
     struct btrfs_root *root = dir->root;
     struct btrfs_fs_info *fs_info = root->fs_info;
     struct btrfs_path *path;
     int ret = 0;
     struct btrfs_dir_item *di;
     u64 index;
     u64 ino = btrfs_ino(inode);
     u64 dir_ino = btrfs_ino(dir);
 
     path = btrfs_alloc_path();
     if (!path) {
         ret = -ENOMEM;
         goto out;
     }
 
     di = btrfs_lookup_dir_item(trans, root, path, dir_ino,
                     name, name_len, -1);
     if (IS_ERR_OR_NULL(di)) {
         ret = di ? PTR_ERR(di) : -ENOENT;
         goto err;
     }
     ret = btrfs_delete_one_dir_name(trans, root, path, di);
     if (ret)
         goto err;
     btrfs_release_path(path);
 
     /*
      * If we don't have dir index, we have to get it by looking up
      * the inode ref, since we get the inode ref, remove it directly,
      * it is unnecessary to do delayed deletion.
      *
      * But if we have dir index, needn't search inode ref to get it.
      * Since the inode ref is close to the inode item, it is better
      * that we delay to delete it, and just do this deletion when
      * we update the inode item.
      */
     if (inode->dir_index) {
         ret = btrfs_delayed_delete_inode_ref(inode);
         if (!ret) {
             index = inode->dir_index;
             goto skip_backref;
         }
     }
 
     ret = btrfs_del_inode_ref(trans, root, name, name_len, ino,
                   dir_ino, &index);
     if (ret) {
         btrfs_info(fs_info,
             "failed to delete reference to %.*s, inode %llu parent %llu",
             name_len, name, ino, dir_ino);
         btrfs_abort_transaction(trans, ret);
         goto err;
     }
 skip_backref:
     if (rename_ctx)
         rename_ctx->index = index;
 
     ret = btrfs_delete_delayed_dir_index(trans, dir, index);
     if (ret) {
         btrfs_abort_transaction(trans, ret);
         goto err;
     }
 
     /*
      * If we are in a rename context, we don't need to update anything in the
      * log. That will be done later during the rename by btrfs_log_new_name().
      * Besides that, doing it here would only cause extra unnecessary btree
      * operations on the log tree, increasing latency for applications.
      */
     if (!rename_ctx) {
         btrfs_del_inode_ref_in_log(trans, root, name, name_len, inode,
                        dir_ino);
         btrfs_del_dir_entries_in_log(trans, root, name, name_len, dir,
                          index);
     }
 
     /*
      * If we have a pending delayed iput we could end up with the final iput
      * being run in btrfs-cleaner context.  If we have enough of these built
      * up we can end up burning a lot of time in btrfs-cleaner without any
      * way to throttle the unlinks.  Since we're currently holding a ref on
      * the inode we can run the delayed iput here without any issues as the
      * final iput won't be done until after we drop the ref we're currently
      * holding.
      */
     btrfs_run_delayed_iput(fs_info, inode);
 err:
     btrfs_free_path(path);
     if (ret)
         goto out;
 
     btrfs_i_size_write(dir, dir->vfs_inode.i_size - name_len * 2);
     inode_inc_iversion(&inode->vfs_inode);
     inode_inc_iversion(&dir->vfs_inode);
     inode->vfs_inode.i_ctime = current_time(&inode->vfs_inode);
     dir->vfs_inode.i_mtime = inode->vfs_inode.i_ctime;
     dir->vfs_inode.i_ctime = inode->vfs_inode.i_ctime;
     ret = btrfs_update_inode(trans, root, dir);
 out:
     return ret;
 }
 
 int btrfs_unlink_inode(struct btrfs_trans_handle *trans,
                struct btrfs_inode *dir, struct btrfs_inode *inode,
                const char *name, int name_len)
 {
     int ret;
     ret = __btrfs_unlink_inode(trans, dir, inode, name, name_len, NULL);
     if (!ret) {
         drop_nlink(&inode->vfs_inode);
         ret = btrfs_update_inode(trans, inode->root, inode);
     }
     return ret;
 }
 
 /*
  * helper to start transaction for unlink and rmdir.
  *
  * unlink and rmdir are special in btrfs, they do not always free space, so
  * if we cannot make our reservations the normal way try and see if there is
  * plenty of slack room in the global reserve to migrate, otherwise we cannot
  * allow the unlink to occur.
  */
 static struct btrfs_trans_handle *__unlink_start_trans(struct inode *dir)
 {
     struct btrfs_root *root = BTRFS_I(dir)->root;
 
     /*
      * 1 for the possible orphan item
      * 1 for the dir item
      * 1 for the dir index
      * 1 for the inode ref
      * 1 for the inode
      * 1 for the parent inode
      */
     return btrfs_start_transaction_fallback_global_rsv(root, 6);
 }
 
 static int btrfs_unlink(struct inode *dir, struct dentry *dentry)
 {
     struct btrfs_trans_handle *trans;
     struct inode *inode = d_inode(dentry);
     int ret;
 
     trans = __unlink_start_trans(dir);
     if (IS_ERR(trans))
         return PTR_ERR(trans);
 
     btrfs_record_unlink_dir(trans, BTRFS_I(dir), BTRFS_I(d_inode(dentry)),
             0);
 
     ret = btrfs_unlink_inode(trans, BTRFS_I(dir),
             BTRFS_I(d_inode(dentry)), dentry->d_name.name,
             dentry->d_name.len);
     if (ret)
         goto out;
 
     if (inode->i_nlink == 0) {
         ret = btrfs_orphan_add(trans, BTRFS_I(inode));
         if (ret)
             goto out;
     }
 
 out:
     btrfs_end_transaction(trans);
     btrfs_btree_balance_dirty(BTRFS_I(dir)->root->fs_info);
     return ret;
 }
 
 static int btrfs_unlink_subvol(struct btrfs_trans_handle *trans,
                    struct inode *dir, struct dentry *dentry)
 {
     struct btrfs_root *root = BTRFS_I(dir)->root;
     struct btrfs_inode *inode = BTRFS_I(d_inode(dentry));
     struct btrfs_path *path;
     struct extent_buffer *leaf;
     struct btrfs_dir_item *di;
     struct btrfs_key key;
     const char *name = dentry->d_name.name;
     int name_len = dentry->d_name.len;
     u64 index;
     int ret;
     u64 objectid;
     u64 dir_ino = btrfs_ino(BTRFS_I(dir));
 
     if (btrfs_ino(inode) == BTRFS_FIRST_FREE_OBJECTID) {
         objectid = inode->root->root_key.objectid;
     } else if (btrfs_ino(inode) == BTRFS_EMPTY_SUBVOL_DIR_OBJECTID) {
         objectid = inode->location.objectid;
     } else {
         WARN_ON(1);
         return -EINVAL;
     }
 
     path = btrfs_alloc_path();
     if (!path)
         return -ENOMEM;
 
     di = btrfs_lookup_dir_item(trans, root, path, dir_ino,
                    name, name_len, -1);
     if (IS_ERR_OR_NULL(di)) {
         ret = di ? PTR_ERR(di) : -ENOENT;
         goto out;
     }
 
     leaf = path->nodes[0];
     btrfs_dir_item_key_to_cpu(leaf, di, &key);
     WARN_ON(key.type != BTRFS_ROOT_ITEM_KEY || key.objectid != objectid);
     ret = btrfs_delete_one_dir_name(trans, root, path, di);
     if (ret) {
         btrfs_abort_transaction(trans, ret);
         goto out;
     }
     btrfs_release_path(path);
 
     /*
      * This is a placeholder inode for a subvolume we didn't have a
      * reference to at the time of the snapshot creation.  In the meantime
      * we could have renamed the real subvol link into our snapshot, so
      * depending on btrfs_del_root_ref to return -ENOENT here is incorrect.
      * Instead simply lookup the dir_index_item for this entry so we can
      * remove it.  Otherwise we know we have a ref to the root and we can
      * call btrfs_del_root_ref, and it _shouldn't_ fail.
      */
     if (btrfs_ino(inode) == BTRFS_EMPTY_SUBVOL_DIR_OBJECTID) {
         di = btrfs_search_dir_index_item(root, path, dir_ino,
                          name, name_len);
         if (IS_ERR_OR_NULL(di)) {
             if (!di)
                 ret = -ENOENT;
             else
                 ret = PTR_ERR(di);
             btrfs_abort_transaction(trans, ret);
             goto out;
         }
 
         leaf = path->nodes[0];
         btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
         index = key.offset;
         btrfs_release_path(path);
     } else {
         ret = btrfs_del_root_ref(trans, objectid,
                      root->root_key.objectid, dir_ino,
                      &index, name, name_len);
         if (ret) {
             btrfs_abort_transaction(trans, ret);
             goto out;
         }
     }
 
     ret = btrfs_delete_delayed_dir_index(trans, BTRFS_I(dir), index);
     if (ret) {
         btrfs_abort_transaction(trans, ret);
         goto out;
     }
 
     btrfs_i_size_write(BTRFS_I(dir), dir->i_size - name_len * 2);
     inode_inc_iversion(dir);
     dir->i_mtime = current_time(dir);
     dir->i_ctime = dir->i_mtime;
     ret = btrfs_update_inode_fallback(trans, root, BTRFS_I(dir));
     if (ret)
         btrfs_abort_transaction(trans, ret);
 out:
     btrfs_free_path(path);
     return ret;
 }
 
 /*
  * Helper to check if the subvolume references other subvolumes or if it's
  * default.
  */
 static noinline int may_destroy_subvol(struct btrfs_root *root)
 {
     struct btrfs_fs_info *fs_info = root->fs_info;
     struct btrfs_path *path;
     struct btrfs_dir_item *di;
     struct btrfs_key key;
     u64 dir_id;
     int ret;
 
     path = btrfs_alloc_path();
     if (!path)
         return -ENOMEM;
 
     /* Make sure this root isn't set as the default subvol */
     dir_id = btrfs_super_root_dir(fs_info->super_copy);
     di = btrfs_lookup_dir_item(NULL, fs_info->tree_root, path,
                    dir_id, "default", 7, 0);
     if (di && !IS_ERR(di)) {
         btrfs_dir_item_key_to_cpu(path->nodes[0], di, &key);
         if (key.objectid == root->root_key.objectid) {
             ret = -EPERM;
             btrfs_err(fs_info,
                   "deleting default subvolume %llu is not allowed",
                   key.objectid);
             goto out;
         }
         btrfs_release_path(path);
     }
 
     key.objectid = root->root_key.objectid;
     key.type = BTRFS_ROOT_REF_KEY;
     key.offset = (u64)-1;
 
     ret = btrfs_search_slot(NULL, fs_info->tree_root, &key, path, 0, 0);
     if (ret < 0)
         goto out;
     BUG_ON(ret == 0);
 
     ret = 0;
     if (path->slots[0] > 0) {
         path->slots[0]--;
         btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
         if (key.objectid == root->root_key.objectid &&
             key.type == BTRFS_ROOT_REF_KEY)
             ret = -ENOTEMPTY;
     }
 out:
     btrfs_free_path(path);
     return ret;
 }
 
 /* Delete all dentries for inodes belonging to the root */
 static void btrfs_prune_dentries(struct btrfs_root *root)
 {
     struct btrfs_fs_info *fs_info = root->fs_info;
     struct rb_node *node;
     struct rb_node *prev;
     struct btrfs_inode *entry;
     struct inode *inode;
     u64 objectid = 0;
 
     if (!BTRFS_FS_ERROR(fs_info))
         WARN_ON(btrfs_root_refs(&root->root_item) != 0);
 
     spin_lock(&root->inode_lock);
 again:
     node = root->inode_tree.rb_node;
     prev = NULL;
     while (node) {
         prev = node;
         entry = rb_entry(node, struct btrfs_inode, rb_node);
 
         if (objectid < btrfs_ino(entry))
             node = node->rb_left;
         else if (objectid > btrfs_ino(entry))
             node = node->rb_right;
         else
             break;
     }
     if (!node) {
         while (prev) {
             entry = rb_entry(prev, struct btrfs_inode, rb_node);
             if (objectid <= btrfs_ino(entry)) {
                 node = prev;
                 break;
             }
             prev = rb_next(prev);
         }
     }
     while (node) {
         entry = rb_entry(node, struct btrfs_inode, rb_node);
         objectid = btrfs_ino(entry) + 1;
         inode = igrab(&entry->vfs_inode);
         if (inode) {
             spin_unlock(&root->inode_lock);
             if (atomic_read(&inode->i_count) > 1)
                 d_prune_aliases(inode);
             /*
              * btrfs_drop_inode will have it removed from the inode
              * cache when its usage count hits zero.
              */
             iput(inode);
             cond_resched();
             spin_lock(&root->inode_lock);
             goto again;
         }
 
         if (cond_resched_lock(&root->inode_lock))
             goto again;
 
         node = rb_next(node);
     }
     spin_unlock(&root->inode_lock);
 }
 
 int btrfs_delete_subvolume(struct inode *dir, struct dentry *dentry)
 {
     struct btrfs_fs_info *fs_info = btrfs_sb(dentry->d_sb);
     struct btrfs_root *root = BTRFS_I(dir)->root;
     struct inode *inode = d_inode(dentry);
     struct btrfs_root *dest = BTRFS_I(inode)->root;
     struct btrfs_trans_handle *trans;
     struct btrfs_block_rsv block_rsv;
     u64 root_flags;
     int ret;
 
     /*
      * Don't allow to delete a subvolume with send in progress. This is
      * inside the inode lock so the error handling that has to drop the bit
      * again is not run concurrently.
      */
     spin_lock(&dest->root_item_lock);
     if (dest->send_in_progress) {
         spin_unlock(&dest->root_item_lock);
         btrfs_warn(fs_info,
                "attempt to delete subvolume %llu during send",
                dest->root_key.objectid);
         return -EPERM;
     }
     if (atomic_read(&dest->nr_swapfiles)) {
         spin_unlock(&dest->root_item_lock);
         btrfs_warn(fs_info,
                "attempt to delete subvolume %llu with active swapfile",
                root->root_key.objectid);
         return -EPERM;
     }
     root_flags = btrfs_root_flags(&dest->root_item);
     btrfs_set_root_flags(&dest->root_item,
                  root_flags | BTRFS_ROOT_SUBVOL_DEAD);
     spin_unlock(&dest->root_item_lock);
 
     down_write(&fs_info->subvol_sem);
 
     ret = may_destroy_subvol(dest);
     if (ret)
         goto out_up_write;
 
     btrfs_init_block_rsv(&block_rsv, BTRFS_BLOCK_RSV_TEMP);
     /*
      * One for dir inode,
      * two for dir entries,
      * two for root ref/backref.
      */
     ret = btrfs_subvolume_reserve_metadata(root, &block_rsv, 5, true);
     if (ret)
         goto out_up_write;
 
     trans = btrfs_start_transaction(root, 0);
     if (IS_ERR(trans)) {
         ret = PTR_ERR(trans);
         goto out_release;
     }
     trans->block_rsv = &block_rsv;
     trans->bytes_reserved = block_rsv.size;
 
     btrfs_record_snapshot_destroy(trans, BTRFS_I(dir));
 
     ret = btrfs_unlink_subvol(trans, dir, dentry);
     if (ret) {
         btrfs_abort_transaction(trans, ret);
         goto out_end_trans;
     }
 
     ret = btrfs_record_root_in_trans(trans, dest);
     if (ret) {
         btrfs_abort_transaction(trans, ret);
         goto out_end_trans;
     }
 
     memset(&dest->root_item.drop_progress, 0,
         sizeof(dest->root_item.drop_progress));
     btrfs_set_root_drop_level(&dest->root_item, 0);
     btrfs_set_root_refs(&dest->root_item, 0);
 
     if (!test_and_set_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED, &dest->state)) {
         ret = btrfs_insert_orphan_item(trans,
                     fs_info->tree_root,
                     dest->root_key.objectid);
         if (ret) {
             btrfs_abort_transaction(trans, ret);
             goto out_end_trans;
         }
     }
 
     ret = btrfs_uuid_tree_remove(trans, dest->root_item.uuid,
                   BTRFS_UUID_KEY_SUBVOL,
                   dest->root_key.objectid);
     if (ret && ret != -ENOENT) {
         btrfs_abort_transaction(trans, ret);
         goto out_end_trans;
     }
     if (!btrfs_is_empty_uuid(dest->root_item.received_uuid)) {
         ret = btrfs_uuid_tree_remove(trans,
                       dest->root_item.received_uuid,
                       BTRFS_UUID_KEY_RECEIVED_SUBVOL,
                       dest->root_key.objectid);
         if (ret && ret != -ENOENT) {
             btrfs_abort_transaction(trans, ret);
             goto out_end_trans;
         }
     }
 
     free_anon_bdev(dest->anon_dev);
     dest->anon_dev = 0;
 out_end_trans:
     trans->block_rsv = NULL;
     trans->bytes_reserved = 0;
     ret = btrfs_end_transaction(trans);
     inode->i_flags |= S_DEAD;
 out_release:
     btrfs_subvolume_release_metadata(root, &block_rsv);
 out_up_write:
     up_write(&fs_info->subvol_sem);
     if (ret) {
         spin_lock(&dest->root_item_lock);
         root_flags = btrfs_root_flags(&dest->root_item);
         btrfs_set_root_flags(&dest->root_item,
                 root_flags & ~BTRFS_ROOT_SUBVOL_DEAD);
         spin_unlock(&dest->root_item_lock);
     } else {
         d_invalidate(dentry);
         btrfs_prune_dentries(dest);
         ASSERT(dest->send_in_progress == 0);
     }
 
     return ret;
 }
 
 static int btrfs_rmdir(struct inode *dir, struct dentry *dentry)
 {
     struct inode *inode = d_inode(dentry);
     struct btrfs_fs_info *fs_info = BTRFS_I(inode)->root->fs_info;
     int err = 0;
     struct btrfs_trans_handle *trans;
     u64 last_unlink_trans;
 
     if (inode->i_size > BTRFS_EMPTY_DIR_SIZE)
         return -ENOTEMPTY;
     if (btrfs_ino(BTRFS_I(inode)) == BTRFS_FIRST_FREE_OBJECTID) {
         if (unlikely(btrfs_fs_incompat(fs_info, EXTENT_TREE_V2))) {
             btrfs_err(fs_info,
             "extent tree v2 doesn't support snapshot deletion yet");
             return -EOPNOTSUPP;
         }
         return btrfs_delete_subvolume(dir, dentry);
     }
 
     trans = __unlink_start_trans(dir);
     if (IS_ERR(trans))
         return PTR_ERR(trans);
 
     if (unlikely(btrfs_ino(BTRFS_I(inode)) == BTRFS_EMPTY_SUBVOL_DIR_OBJECTID)) {
         err = btrfs_unlink_subvol(trans, dir, dentry);
         goto out;
     }
 
     err = btrfs_orphan_add(trans, BTRFS_I(inode));
     if (err)
         goto out;
 
     last_unlink_trans = BTRFS_I(inode)->last_unlink_trans;
 
     /* now the directory is empty */
     err = btrfs_unlink_inode(trans, BTRFS_I(dir),
             BTRFS_I(d_inode(dentry)), dentry->d_name.name,
             dentry->d_name.len);
     if (!err) {
         btrfs_i_size_write(BTRFS_I(inode), 0);
         /*
          * Propagate the last_unlink_trans value of the deleted dir to
          * its parent directory. This is to prevent an unrecoverable
          * log tree in the case we do something like this:
          * 1) create dir foo
          * 2) create snapshot under dir foo
          * 3) delete the snapshot
          * 4) rmdir foo
          * 5) mkdir foo
          * 6) fsync foo or some file inside foo
          */
         if (last_unlink_trans >= trans->transid)
             BTRFS_I(dir)->last_unlink_trans = last_unlink_trans;
     }
 out:
     btrfs_end_transaction(trans);
     btrfs_btree_balance_dirty(fs_info);
 
     return err;
 }
 
 /*
  * btrfs_truncate_block - read, zero a chunk and write a block
  * @inode - inode that we're zeroing
  * @from - the offset to start zeroing
  * @len - the length to zero, 0 to zero the entire range respective to the
  *  offset
  * @front - zero up to the offset instead of from the offset on
  *
  * This will find the block for the "from" offset and cow the block and zero the
  * part we want to zero.  This is used with truncate and hole punching.
  */
 int btrfs_truncate_block(struct btrfs_inode *inode, loff_t from, loff_t len,
              int front)
 {
     struct btrfs_fs_info *fs_info = inode->root->fs_info;
     struct address_space *mapping = inode->vfs_inode.i_mapping;
     struct extent_io_tree *io_tree = &inode->io_tree;
     struct btrfs_ordered_extent *ordered;
     struct extent_state *cached_state = NULL;
     struct extent_changeset *data_reserved = NULL;
     bool only_release_metadata = false;
     u32 blocksize = fs_info->sectorsize;
     pgoff_t index = from >> PAGE_SHIFT;
     unsigned offset = from & (blocksize - 1);
     struct page *page;
     gfp_t mask = btrfs_alloc_write_mask(mapping);
     size_t write_bytes = blocksize;
     int ret = 0;
     u64 block_start;
     u64 block_end;
 
     if (IS_ALIGNED(offset, blocksize) &&
         (!len || IS_ALIGNED(len, blocksize)))
         goto out;
 
     block_start = round_down(from, blocksize);
     block_end = block_start + blocksize - 1;
 
     ret = btrfs_check_data_free_space(inode, &data_reserved, block_start,
                       blocksize);
     if (ret < 0) {
         if (btrfs_check_nocow_lock(inode, block_start, &write_bytes) > 0) {
             /* For nocow case, no need to reserve data space */
             only_release_metadata = true;
         } else {
             goto out;
         }
     }
     ret = btrfs_delalloc_reserve_metadata(inode, blocksize, blocksize, false);
     if (ret < 0) {
         if (!only_release_metadata)
             btrfs_free_reserved_data_space(inode, data_reserved,
                                block_start, blocksize);
         goto out;
     }
 again:
     page = find_or_create_page(mapping, index, mask);
     if (!page) {
         btrfs_delalloc_release_space(inode, data_reserved, block_start,
                          blocksize, true);
         btrfs_delalloc_release_extents(inode, blocksize);
         ret = -ENOMEM;
         goto out;
     }
     ret = set_page_extent_mapped(page);
     if (ret < 0)
         goto out_unlock;
 
     if (!PageUptodate(page)) {
         ret = btrfs_read_folio(NULL, page_folio(page));
         lock_page(page);
         if (page->mapping != mapping) {
             unlock_page(page);
             put_page(page);
             goto again;
         }
         if (!PageUptodate(page)) {
             ret = -EIO;
             goto out_unlock;
         }
     }
     wait_on_page_writeback(page);
 
     lock_extent_bits(io_tree, block_start, block_end, &cached_state);
 
     ordered = btrfs_lookup_ordered_extent(inode, block_start);
     if (ordered) {
         unlock_extent_cached(io_tree, block_start, block_end,
                      &cached_state);
         unlock_page(page);
         put_page(page);
         btrfs_start_ordered_extent(ordered, 1);
         btrfs_put_ordered_extent(ordered);
         goto again;
     }
 
     clear_extent_bit(&inode->io_tree, block_start, block_end,
              EXTENT_DELALLOC | EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG,
              0, 0, &cached_state);
 
     ret = btrfs_set_extent_delalloc(inode, block_start, block_end, 0,
                     &cached_state);
     if (ret) {
         unlock_extent_cached(io_tree, block_start, block_end,
                      &cached_state);
         goto out_unlock;
     }
 
     if (offset != blocksize) {
         if (!len)
             len = blocksize - offset;
         if (front)
             memzero_page(page, (block_start - page_offset(page)),
                      offset);
         else
             memzero_page(page, (block_start - page_offset(page)) + offset,
                      len);
     }
     btrfs_page_clear_checked(fs_info, page, block_start,
                  block_end + 1 - block_start);
     btrfs_page_set_dirty(fs_info, page, block_start, block_end + 1 - block_start);
     unlock_extent_cached(io_tree, block_start, block_end, &cached_state);
 
     if (only_release_metadata)
         set_extent_bit(&inode->io_tree, block_start, block_end,
                    EXTENT_NORESERVE, 0, NULL, NULL, GFP_NOFS, NULL);
 
 out_unlock:
     if (ret) {
         if (only_release_metadata)
             btrfs_delalloc_release_metadata(inode, blocksize, true);
         else
             btrfs_delalloc_release_space(inode, data_reserved,
                     block_start, blocksize, true);
     }
     btrfs_delalloc_release_extents(inode, blocksize);
     unlock_page(page);
     put_page(page);
 out:
     if (only_release_metadata)
         btrfs_check_nocow_unlock(inode);
     extent_changeset_free(data_reserved);
     return ret;
 }
 
 static int maybe_insert_hole(struct btrfs_root *root, struct btrfs_inode *inode,
                  u64 offset, u64 len)
 {
     struct btrfs_fs_info *fs_info = root->fs_info;
     struct btrfs_trans_handle *trans;
     struct btrfs_drop_extents_args drop_args = { 0 };
     int ret;
 
     /*
      * If NO_HOLES is enabled, we don't need to do anything.
      * Later, up in the call chain, either btrfs_set_inode_last_sub_trans()
      * or btrfs_update_inode() will be called, which guarantee that the next
      * fsync will know this inode was changed and needs to be logged.
      */
     if (btrfs_fs_incompat(fs_info, NO_HOLES))
         return 0;
 
     /*
      * 1 - for the one we're dropping
      * 1 - for the one we're adding
      * 1 - for updating the inode.
      */
     trans = btrfs_start_transaction(root, 3);
     if (IS_ERR(trans))
         return PTR_ERR(trans);
 
     drop_args.start = offset;
     drop_args.end = offset + len;
     drop_args.drop_cache = true;
 
     ret = btrfs_drop_extents(trans, root, inode, &drop_args);
     if (ret) {
         btrfs_abort_transaction(trans, ret);
         btrfs_end_transaction(trans);
         return ret;
     }
 
     ret = btrfs_insert_file_extent(trans, root, btrfs_ino(inode),
             offset, 0, 0, len, 0, len, 0, 0, 0);
     if (ret) {
         btrfs_abort_transaction(trans, ret);
     } else {
         btrfs_update_inode_bytes(inode, 0, drop_args.bytes_found);
         btrfs_update_inode(trans, root, inode);
     }
     btrfs_end_transaction(trans);
     return ret;
 }
 
 /*
  * This function puts in dummy file extents for the area we're creating a hole
  * for.  So if we are truncating this file to a larger size we need to insert
  * these file extents so that btrfs_get_extent will return a EXTENT_MAP_HOLE for
  * the range between oldsize and size
  */
 int btrfs_cont_expand(struct btrfs_inode *inode, loff_t oldsize, loff_t size)
 {
     struct btrfs_root *root = inode->root;
     struct btrfs_fs_info *fs_info = root->fs_info;
     struct extent_io_tree *io_tree = &inode->io_tree;
     struct extent_map *em = NULL;
     struct extent_state *cached_state = NULL;
     struct extent_map_tree *em_tree = &inode->extent_tree;
     u64 hole_start = ALIGN(oldsize, fs_info->sectorsize);
     u64 block_end = ALIGN(size, fs_info->sectorsize);
     u64 last_byte;
     u64 cur_offset;
     u64 hole_size;
     int err = 0;
 
     /*
      * If our size started in the middle of a block we need to zero out the
      * rest of the block before we expand the i_size, otherwise we could
      * expose stale data.
      */
     err = btrfs_truncate_block(inode, oldsize, 0, 0);
     if (err)
         return err;
 
     if (size <= hole_start)
         return 0;
 
     btrfs_lock_and_flush_ordered_range(inode, hole_start, block_end - 1,
                        &cached_state);
     cur_offset = hole_start;
     while (1) {
         em = btrfs_get_extent(inode, NULL, 0, cur_offset,
                       block_end - cur_offset);
         if (IS_ERR(em)) {
             err = PTR_ERR(em);
             em = NULL;
             break;
         }
         last_byte = min(extent_map_end(em), block_end);
         last_byte = ALIGN(last_byte, fs_info->sectorsize);
         hole_size = last_byte - cur_offset;
 
         if (!test_bit(EXTENT_FLAG_PREALLOC, &em->flags)) {
             struct extent_map *hole_em;
 
             err = maybe_insert_hole(root, inode, cur_offset,
                         hole_size);
             if (err)
                 break;
 
             err = btrfs_inode_set_file_extent_range(inode,
                             cur_offset, hole_size);
             if (err)
                 break;
 
             btrfs_drop_extent_cache(inode, cur_offset,
                         cur_offset + hole_size - 1, 0);
             hole_em = alloc_extent_map();
             if (!hole_em) {
                 btrfs_set_inode_full_sync(inode);
                 goto next;
             }
             hole_em->start = cur_offset;
             hole_em->len = hole_size;
             hole_em->orig_start = cur_offset;
 
             hole_em->block_start = EXTENT_MAP_HOLE;
             hole_em->block_len = 0;
             hole_em->orig_block_len = 0;
             hole_em->ram_bytes = hole_size;
             hole_em->compress_type = BTRFS_COMPRESS_NONE;
             hole_em->generation = fs_info->generation;
 
             while (1) {
                 write_lock(&em_tree->lock);
                 err = add_extent_mapping(em_tree, hole_em, 1);
                 write_unlock(&em_tree->lock);
                 if (err != -EEXIST)
                     break;
                 btrfs_drop_extent_cache(inode, cur_offset,
                             cur_offset +
                             hole_size - 1, 0);
             }
             free_extent_map(hole_em);
         } else {
             err = btrfs_inode_set_file_extent_range(inode,
                             cur_offset, hole_size);
             if (err)
                 break;
         }
 next:
         free_extent_map(em);
         em = NULL;
         cur_offset = last_byte;
         if (cur_offset >= block_end)
             break;
     }
     free_extent_map(em);
     unlock_extent_cached(io_tree, hole_start, block_end - 1, &cached_state);
     return err;
 }
 
 static int btrfs_setsize(struct inode *inode, struct iattr *attr)
 {
     struct btrfs_root *root = BTRFS_I(inode)->root;
     struct btrfs_trans_handle *trans;
     loff_t oldsize = i_size_read(inode);
     loff_t newsize = attr->ia_size;
     int mask = attr->ia_valid;
     int ret;
 
     /*
      * The regular truncate() case without ATTR_CTIME and ATTR_MTIME is a
      * special case where we need to update the times despite not having
      * these flags set.  For all other operations the VFS set these flags
      * explicitly if it wants a timestamp update.
      */
     if (newsize != oldsize) {
         inode_inc_iversion(inode);
         if (!(mask & (ATTR_CTIME | ATTR_MTIME))) {
             inode->i_mtime = current_time(inode);
             inode->i_ctime = inode->i_mtime;
         }
     }
 
     if (newsize > oldsize) {
         /*
          * Don't do an expanding truncate while snapshotting is ongoing.
          * This is to ensure the snapshot captures a fully consistent
          * state of this file - if the snapshot captures this expanding
          * truncation, it must capture all writes that happened before
          * this truncation.
          */
         btrfs_drew_write_lock(&root->snapshot_lock);
         ret = btrfs_cont_expand(BTRFS_I(inode), oldsize, newsize);
         if (ret) {
             btrfs_drew_write_unlock(&root->snapshot_lock);
             return ret;
         }
 
         trans = btrfs_start_transaction(root, 1);
         if (IS_ERR(trans)) {
             btrfs_drew_write_unlock(&root->snapshot_lock);
             return PTR_ERR(trans);
         }
 
         i_size_write(inode, newsize);
         btrfs_inode_safe_disk_i_size_write(BTRFS_I(inode), 0);
         pagecache_isize_extended(inode, oldsize, newsize);
         ret = btrfs_update_inode(trans, root, BTRFS_I(inode));
         btrfs_drew_write_unlock(&root->snapshot_lock);
         btrfs_end_transaction(trans);
     } else {
         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
 
         if (btrfs_is_zoned(fs_info)) {
             ret = btrfs_wait_ordered_range(inode,
                     ALIGN(newsize, fs_info->sectorsize),
                     (u64)-1);
             if (ret)
                 return ret;
         }
 
         /*
          * We're truncating a file that used to have good data down to
          * zero. Make sure any new writes to the file get on disk
          * on close.
          */
         if (newsize == 0)
             set_bit(BTRFS_INODE_FLUSH_ON_CLOSE,
                 &BTRFS_I(inode)->runtime_flags);
 
         truncate_setsize(inode, newsize);
 
         inode_dio_wait(inode);
 
         ret = btrfs_truncate(inode, newsize == oldsize);
         if (ret && inode->i_nlink) {
             int err;
 
             /*
              * Truncate failed, so fix up the in-memory size. We
              * adjusted disk_i_size down as we removed extents, so
              * wait for disk_i_size to be stable and then update the
              * in-memory size to match.
              */
             err = btrfs_wait_ordered_range(inode, 0, (u64)-1);
             if (err)
                 return err;
             i_size_write(inode, BTRFS_I(inode)->disk_i_size);
         }
     }
 
     return ret;
 }
 
 static int btrfs_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
              struct iattr *attr)
 {
     struct inode *inode = d_inode(dentry);
     struct btrfs_root *root = BTRFS_I(inode)->root;
     int err;
 
     if (btrfs_root_readonly(root))
         return -EROFS;
 
     err = setattr_prepare(mnt_userns, dentry, attr);
     if (err)
         return err;
 
     if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) {
         err = btrfs_setsize(inode, attr);
         if (err)
             return err;
     }
 
     if (attr->ia_valid) {
         setattr_copy(mnt_userns, inode, attr);
         inode_inc_iversion(inode);
         err = btrfs_dirty_inode(inode);
 
         if (!err && attr->ia_valid & ATTR_MODE)
             err = posix_acl_chmod(mnt_userns, inode, inode->i_mode);
     }
 
     return err;
 }
 
 /*
  * While truncating the inode pages during eviction, we get the VFS
  * calling btrfs_invalidate_folio() against each folio of the inode. This
  * is slow because the calls to btrfs_invalidate_folio() result in a
  * huge amount of calls to lock_extent_bits() and clear_extent_bit(),
  * which keep merging and splitting extent_state structures over and over,
  * wasting lots of time.
  *
  * Therefore if the inode is being evicted, let btrfs_invalidate_folio()
  * skip all those expensive operations on a per folio basis and do only
  * the ordered io finishing, while we release here the extent_map and
  * extent_state structures, without the excessive merging and splitting.
  */
 static void evict_inode_truncate_pages(struct inode *inode)
 {
     struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
     struct extent_map_tree *map_tree = &BTRFS_I(inode)->extent_tree;
     struct rb_node *node;
 
     ASSERT(inode->i_state & I_FREEING);
     truncate_inode_pages_final(&inode->i_data);
 
     write_lock(&map_tree->lock);
     while (!RB_EMPTY_ROOT(&map_tree->map.rb_root)) {
         struct extent_map *em;
 
         node = rb_first_cached(&map_tree->map);
         em = rb_entry(node, struct extent_map, rb_node);
         clear_bit(EXTENT_FLAG_PINNED, &em->flags);
         clear_bit(EXTENT_FLAG_LOGGING, &em->flags);
         remove_extent_mapping(map_tree, em);
         free_extent_map(em);
         if (need_resched()) {
             write_unlock(&map_tree->lock);
             cond_resched();
             write_lock(&map_tree->lock);
         }
     }
     write_unlock(&map_tree->lock);
 
     /*
      * Keep looping until we have no more ranges in the io tree.
      * We can have ongoing bios started by readahead that have
      * their endio callback (extent_io.c:end_bio_extent_readpage)
      * still in progress (unlocked the pages in the bio but did not yet
      * unlocked the ranges in the io tree). Therefore this means some
      * ranges can still be locked and eviction started because before
      * submitting those bios, which are executed by a separate task (work
      * queue kthread), inode references (inode->i_count) were not taken
      * (which would be dropped in the end io callback of each bio).
      * Therefore here we effectively end up waiting for those bios and
      * anyone else holding locked ranges without having bumped the inode's
      * reference count - if we don't do it, when they access the inode's
      * io_tree to unlock a range it may be too late, leading to an
      * use-after-free issue.
      */
     spin_lock(&io_tree->lock);
     while (!RB_EMPTY_ROOT(&io_tree->state)) {
         struct extent_state *state;
         struct extent_state *cached_state = NULL;
         u64 start;
         u64 end;
         unsigned state_flags;
 
         node = rb_first(&io_tree->state);
         state = rb_entry(node, struct extent_state, rb_node);
         start = state->start;
         end = state->end;
         state_flags = state->state;
         spin_unlock(&io_tree->lock);
 
         lock_extent_bits(io_tree, start, end, &cached_state);
 
         /*
          * If still has DELALLOC flag, the extent didn't reach disk,
          * and its reserved space won't be freed by delayed_ref.
          * So we need to free its reserved space here.
          * (Refer to comment in btrfs_invalidate_folio, case 2)
          *
          * Note, end is the bytenr of last byte, so we need + 1 here.
          */
         if (state_flags & EXTENT_DELALLOC)
             btrfs_qgroup_free_data(BTRFS_I(inode), NULL, start,
                            end - start + 1);
 
         clear_extent_bit(io_tree, start, end,
                  EXTENT_LOCKED | EXTENT_DELALLOC |
                  EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG, 1, 1,
                  &cached_state);
 
         cond_resched();
         spin_lock(&io_tree->lock);
     }
     spin_unlock(&io_tree->lock);
 }
 
 static struct btrfs_trans_handle *evict_refill_and_join(struct btrfs_root *root,
                             struct btrfs_block_rsv *rsv)
 {
     struct btrfs_fs_info *fs_info = root->fs_info;
     struct btrfs_trans_handle *trans;
     u64 delayed_refs_extra = btrfs_calc_insert_metadata_size(fs_info, 1);
     int ret;
 
     /*
      * Eviction should be taking place at some place safe because of our
      * delayed iputs.  However the normal flushing code will run delayed
      * iputs, so we cannot use FLUSH_ALL otherwise we'll deadlock.
      *
      * We reserve the delayed_refs_extra here again because we can't use
      * btrfs_start_transaction(root, 0) for the same deadlocky reason as
      * above.  We reserve our extra bit here because we generate a ton of
      * delayed refs activity by truncating.
      *
      * BTRFS_RESERVE_FLUSH_EVICT will steal from the global_rsv if it can,
      * if we fail to make this reservation we can re-try without the
      * delayed_refs_extra so we can make some forward progress.
      */
     ret = btrfs_block_rsv_refill(fs_info, rsv, rsv->size + delayed_refs_extra,
                      BTRFS_RESERVE_FLUSH_EVICT);
     if (ret) {
         ret = btrfs_block_rsv_refill(fs_info, rsv, rsv->size,
                          BTRFS_RESERVE_FLUSH_EVICT);
         if (ret) {
             btrfs_warn(fs_info,
                    "could not allocate space for delete; will truncate on mount");
             return ERR_PTR(-ENOSPC);
         }
         delayed_refs_extra = 0;
     }
 
     trans = btrfs_join_transaction(root);
     if (IS_ERR(trans))
         return trans;
 
     if (delayed_refs_extra) {
         trans->block_rsv = &fs_info->trans_block_rsv;
         trans->bytes_reserved = delayed_refs_extra;
         btrfs_block_rsv_migrate(rsv, trans->block_rsv,
                     delayed_refs_extra, 1);
     }
     return trans;
 }
 
 void btrfs_evict_inode(struct inode *inode)
 {
     struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
     struct btrfs_trans_handle *trans;
     struct btrfs_root *root = BTRFS_I(inode)->root;
     struct btrfs_block_rsv *rsv;
     int ret;
 
     trace_btrfs_inode_evict(inode);
 
     if (!root) {
         fsverity_cleanup_inode(inode);
         clear_inode(inode);
         return;
     }
 
     evict_inode_truncate_pages(inode);
 
     if (inode->i_nlink &&
         ((btrfs_root_refs(&root->root_item) != 0 &&
           root->root_key.objectid != BTRFS_ROOT_TREE_OBJECTID) ||
          btrfs_is_free_space_inode(BTRFS_I(inode))))
         goto no_delete;
 
     if (is_bad_inode(inode))
         goto no_delete;
 
     btrfs_free_io_failure_record(BTRFS_I(inode), 0, (u64)-1);
 
     if (test_bit(BTRFS_FS_LOG_RECOVERING, &fs_info->flags))
         goto no_delete;
 
     if (inode->i_nlink > 0) {
         BUG_ON(btrfs_root_refs(&root->root_item) != 0 &&
                root->root_key.objectid != BTRFS_ROOT_TREE_OBJECTID);
         goto no_delete;
     }
 
     /*
      * This makes sure the inode item in tree is uptodate and the space for
      * the inode update is released.
      */
     ret = btrfs_commit_inode_delayed_inode(BTRFS_I(inode));
     if (ret)
         goto no_delete;
 
     /*
      * This drops any pending insert or delete operations we have for this
      * inode.  We could have a delayed dir index deletion queued up, but
      * we're removing the inode completely so that'll be taken care of in
      * the truncate.
      */
     btrfs_kill_delayed_inode_items(BTRFS_I(inode));
 
     rsv = btrfs_alloc_block_rsv(fs_info, BTRFS_BLOCK_RSV_TEMP);
     if (!rsv)
         goto no_delete;
     rsv->size = btrfs_calc_metadata_size(fs_info, 1);
     rsv->failfast = true;
 
     btrfs_i_size_write(BTRFS_I(inode), 0);
 
     while (1) {
         struct btrfs_truncate_control control = {
             .inode = BTRFS_I(inode),
             .ino = btrfs_ino(BTRFS_I(inode)),
             .new_size = 0,
             .min_type = 0,
         };
 
         trans = evict_refill_and_join(root, rsv);
         if (IS_ERR(trans))
             goto free_rsv;
 
         trans->block_rsv = rsv;
 
         ret = btrfs_truncate_inode_items(trans, root, &control);
         trans->block_rsv = &fs_info->trans_block_rsv;
         btrfs_end_transaction(trans);
         btrfs_btree_balance_dirty(fs_info);
         if (ret && ret != -ENOSPC && ret != -EAGAIN)
             goto free_rsv;
         else if (!ret)
             break;
     }
 
     /*
      * Errors here aren't a big deal, it just means we leave orphan items in
      * the tree. They will be cleaned up on the next mount. If the inode
      * number gets reused, cleanup deletes the orphan item without doing
      * anything, and unlink reuses the existing orphan item.
      *
      * If it turns out that we are dropping too many of these, we might want
      * to add a mechanism for retrying these after a commit.
      */
     trans = evict_refill_and_join(root, rsv);
     if (!IS_ERR(trans)) {
         trans->block_rsv = rsv;
         btrfs_orphan_del(trans, BTRFS_I(inode));
         trans->block_rsv = &fs_info->trans_block_rsv;
         btrfs_end_transaction(trans);
     }
 
 free_rsv:
     btrfs_free_block_rsv(fs_info, rsv);
 no_delete:
     /*
      * If we didn't successfully delete, the orphan item will still be in
      * the tree and we'll retry on the next mount. Again, we might also want
      * to retry these periodically in the future.
      */
     btrfs_remove_delayed_node(BTRFS_I(inode));
     fsverity_cleanup_inode(inode);
     clear_inode(inode);
 }
 
 /*
  * Return the key found in the dir entry in the location pointer, fill @type
  * with BTRFS_FT_*, and return 0.
  *
  * If no dir entries were found, returns -ENOENT.
  * If found a corrupted location in dir entry, returns -EUCLEAN.
  */
 static int btrfs_inode_by_name(struct inode *dir, struct dentry *dentry,
                    struct btrfs_key *location, u8 *type)
 {
     const char *name = dentry->d_name.name;
     int namelen = dentry->d_name.len;
     struct btrfs_dir_item *di;
     struct btrfs_path *path;
     struct btrfs_root *root = BTRFS_I(dir)->root;
     int ret = 0;
 
     path = btrfs_alloc_path();
     if (!path)
         return -ENOMEM;
 
     di = btrfs_lookup_dir_item(NULL, root, path, btrfs_ino(BTRFS_I(dir)),
             name, namelen, 0);
     if (IS_ERR_OR_NULL(di)) {
         ret = di ? PTR_ERR(di) : -ENOENT;
         goto out;
     }
 
     btrfs_dir_item_key_to_cpu(path->nodes[0], di, location);
     if (location->type != BTRFS_INODE_ITEM_KEY &&
         location->type != BTRFS_ROOT_ITEM_KEY) {
         ret = -EUCLEAN;
         btrfs_warn(root->fs_info,
 "%s gets something invalid in DIR_ITEM (name %s, directory ino %llu, location(%llu %u %llu))",
                __func__, name, btrfs_ino(BTRFS_I(dir)),
                location->objectid, location->type, location->offset);
     }
     if (!ret)
         *type = btrfs_dir_type(path->nodes[0], di);
 out:
     btrfs_free_path(path);
     return ret;
 }
 
 /*
  * when we hit a tree root in a directory, the btrfs part of the inode
  * needs to be changed to reflect the root directory of the tree root.  This
  * is kind of like crossing a mount point.
  */
 static int fixup_tree_root_location(struct btrfs_fs_info *fs_info,
                     struct inode *dir,
                     struct dentry *dentry,
                     struct btrfs_key *location,
                     struct btrfs_root **sub_root)
 {
     struct btrfs_path *path;
     struct btrfs_root *new_root;
     struct btrfs_root_ref *ref;
     struct extent_buffer *leaf;
     struct btrfs_key key;
     int ret;
     int err = 0;
 
     path = btrfs_alloc_path();
     if (!path) {
         err = -ENOMEM;
         goto out;
     }
 
     err = -ENOENT;
     key.objectid = BTRFS_I(dir)->root->root_key.objectid;
     key.type = BTRFS_ROOT_REF_KEY;
     key.offset = location->objectid;
 
     ret = btrfs_search_slot(NULL, fs_info->tree_root, &key, path, 0, 0);
     if (ret) {
         if (ret < 0)
             err = ret;
         goto out;
     }
 
     leaf = path->nodes[0];
     ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref);
     if (btrfs_root_ref_dirid(leaf, ref) != btrfs_ino(BTRFS_I(dir)) ||
         btrfs_root_ref_name_len(leaf, ref) != dentry->d_name.len)
         goto out;
 
     ret = memcmp_extent_buffer(leaf, dentry->d_name.name,
                    (unsigned long)(ref + 1),
                    dentry->d_name.len);
     if (ret)
         goto out;
 
     btrfs_release_path(path);
 
     new_root = btrfs_get_fs_root(fs_info, location->objectid, true);
     if (IS_ERR(new_root)) {
         err = PTR_ERR(new_root);
         goto out;
     }
 
     *sub_root = new_root;
     location->objectid = btrfs_root_dirid(&new_root->root_item);
     location->type = BTRFS_INODE_ITEM_KEY;
     location->offset = 0;
     err = 0;
 out:
     btrfs_free_path(path);
     return err;
 }
 
 static void inode_tree_add(struct inode *inode)
 {
     struct btrfs_root *root = BTRFS_I(inode)->root;
     struct btrfs_inode *entry;
     struct rb_node **p;
     struct rb_node *parent;
     struct rb_node *new = &BTRFS_I(inode)->rb_node;
     u64 ino = btrfs_ino(BTRFS_I(inode));
 
     if (inode_unhashed(inode))
         return;
     parent = NULL;
     spin_lock(&root->inode_lock);
     p = &root->inode_tree.rb_node;
     while (*p) {
         parent = *p;
         entry = rb_entry(parent, struct btrfs_inode, rb_node);
 
         if (ino < btrfs_ino(entry))
             p = &parent->rb_left;
         else if (ino > btrfs_ino(entry))
             p = &parent->rb_right;
         else {
             WARN_ON(!(entry->vfs_inode.i_state &
                   (I_WILL_FREE | I_FREEING)));
             rb_replace_node(parent, new, &root->inode_tree);
             RB_CLEAR_NODE(parent);
             spin_unlock(&root->inode_lock);
             return;
         }
     }
     rb_link_node(new, parent, p);
     rb_insert_color(new, &root->inode_tree);
     spin_unlock(&root->inode_lock);
 }
 
 static void inode_tree_del(struct btrfs_inode *inode)
 {
     struct btrfs_root *root = inode->root;
     int empty = 0;
 
     spin_lock(&root->inode_lock);
     if (!RB_EMPTY_NODE(&inode->rb_node)) {
         rb_erase(&inode->rb_node, &root->inode_tree);
         RB_CLEAR_NODE(&inode->rb_node);
         empty = RB_EMPTY_ROOT(&root->inode_tree);
     }
     spin_unlock(&root->inode_lock);
 
     if (empty && btrfs_root_refs(&root->root_item) == 0) {
         spin_lock(&root->inode_lock);
         empty = RB_EMPTY_ROOT(&root->inode_tree);
         spin_unlock(&root->inode_lock);
         if (empty)
             btrfs_add_dead_root(root);
     }
 }
 
 
 static int btrfs_init_locked_inode(struct inode *inode, void *p)
 {
     struct btrfs_iget_args *args = p;
 
     inode->i_ino = args->ino;
     BTRFS_I(inode)->location.objectid = args->ino;
     BTRFS_I(inode)->location.type = BTRFS_INODE_ITEM_KEY;
     BTRFS_I(inode)->location.offset = 0;
     BTRFS_I(inode)->root = btrfs_grab_root(args->root);
     BUG_ON(args->root && !BTRFS_I(inode)->root);
     return 0;
 }
 
 static int btrfs_find_actor(struct inode *inode, void *opaque)
 {
     struct btrfs_iget_args *args = opaque;
 
     return args->ino == BTRFS_I(inode)->location.objectid &&
         args->root == BTRFS_I(inode)->root;
 }
 
 static struct inode *btrfs_iget_locked(struct super_block *s, u64 ino,
                        struct btrfs_root *root)
 {
     struct inode *inode;
     struct btrfs_iget_args args;
     unsigned long hashval = btrfs_inode_hash(ino, root);
 
     args.ino = ino;
     args.root = root;
 
     inode = iget5_locked(s, hashval, btrfs_find_actor,
                  btrfs_init_locked_inode,
                  (void *)&args);
     return inode;
 }
 
 /*
  * Get an inode object given its inode number and corresponding root.
  * Path can be preallocated to prevent recursing back to iget through
  * allocator. NULL is also valid but may require an additional allocation
  * later.
  */
 struct inode *btrfs_iget_path(struct super_block *s, u64 ino,
                   struct btrfs_root *root, struct btrfs_path *path)
 {
     struct inode *inode;
 
     inode = btrfs_iget_locked(s, ino, root);
     if (!inode)
         return ERR_PTR(-ENOMEM);
 
     if (inode->i_state & I_NEW) {
         int ret;
 
         ret = btrfs_read_locked_inode(inode, path);
         if (!ret) {
             inode_tree_add(inode);
             unlock_new_inode(inode);
         } else {
             iget_failed(inode);
             /*
              * ret > 0 can come from btrfs_search_slot called by
              * btrfs_read_locked_inode, this means the inode item
              * was not found.
              */
             if (ret > 0)
                 ret = -ENOENT;
             inode = ERR_PTR(ret);
         }
     }
 
     return inode;
 }
 
 struct inode *btrfs_iget(struct super_block *s, u64 ino, struct btrfs_root *root)
 {
     return btrfs_iget_path(s, ino, root, NULL);
 }
 
 static struct inode *new_simple_dir(struct super_block *s,
                     struct btrfs_key *key,
                     struct btrfs_root *root)
 {
     struct inode *inode = new_inode(s);
 
     if (!inode)
         return ERR_PTR(-ENOMEM);
 
     BTRFS_I(inode)->root = btrfs_grab_root(root);
     memcpy(&BTRFS_I(inode)->location, key, sizeof(*key));
     set_bit(BTRFS_INODE_DUMMY, &BTRFS_I(inode)->runtime_flags);
 
     inode->i_ino = BTRFS_EMPTY_SUBVOL_DIR_OBJECTID;
     /*
      * We only need lookup, the rest is read-only and there's no inode
      * associated with the dentry
      */
     inode->i_op = &simple_dir_inode_operations;
     inode->i_opflags &= ~IOP_XATTR;
     inode->i_fop = &simple_dir_operations;
     inode->i_mode = S_IFDIR | S_IRUGO | S_IWUSR | S_IXUGO;
     inode->i_mtime = current_time(inode);
     inode->i_atime = inode->i_mtime;
     inode->i_ctime = inode->i_mtime;
     BTRFS_I(inode)->i_otime = inode->i_mtime;
 
     return inode;
 }
 
 static_assert(BTRFS_FT_UNKNOWN == FT_UNKNOWN);
 static_assert(BTRFS_FT_REG_FILE == FT_REG_FILE);
 static_assert(BTRFS_FT_DIR == FT_DIR);
 static_assert(BTRFS_FT_CHRDEV == FT_CHRDEV);
 static_assert(BTRFS_FT_BLKDEV == FT_BLKDEV);
 static_assert(BTRFS_FT_FIFO == FT_FIFO);
 static_assert(BTRFS_FT_SOCK == FT_SOCK);
 static_assert(BTRFS_FT_SYMLINK == FT_SYMLINK);
 
 static inline u8 btrfs_inode_type(struct inode *inode)
 {
     return fs_umode_to_ftype(inode->i_mode);
 }
 
 struct inode *btrfs_lookup_dentry(struct inode *dir, struct dentry *dentry)
 {
     struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb);
     struct inode *inode;
     struct btrfs_root *root = BTRFS_I(dir)->root;
     struct btrfs_root *sub_root = root;
     struct btrfs_key location;
     u8 di_type = 0;
     int ret = 0;
 
     if (dentry->d_name.len > BTRFS_NAME_LEN)
         return ERR_PTR(-ENAMETOOLONG);
 
     ret = btrfs_inode_by_name(dir, dentry, &location, &di_type);
     if (ret < 0)
         return ERR_PTR(ret);
 
     if (location.type == BTRFS_INODE_ITEM_KEY) {
         inode = btrfs_iget(dir->i_sb, location.objectid, root);
         if (IS_ERR(inode))
             return inode;
 
         /* Do extra check against inode mode with di_type */
         if (btrfs_inode_type(inode) != di_type) {
             btrfs_crit(fs_info,
 "inode mode mismatch with dir: inode mode=0%o btrfs type=%u dir type=%u",
                   inode->i_mode, btrfs_inode_type(inode),
                   di_type);
             iput(inode);
             return ERR_PTR(-EUCLEAN);
         }
         return inode;
     }
 
     ret = fixup_tree_root_location(fs_info, dir, dentry,
                        &location, &sub_root);
     if (ret < 0) {
         if (ret != -ENOENT)
             inode = ERR_PTR(ret);
         else
             inode = new_simple_dir(dir->i_sb, &location, root);
     } else {
         inode = btrfs_iget(dir->i_sb, location.objectid, sub_root);
         btrfs_put_root(sub_root);
 
         if (IS_ERR(inode))
             return inode;
 
         down_read(&fs_info->cleanup_work_sem);
         if (!sb_rdonly(inode->i_sb))
             ret = btrfs_orphan_cleanup(sub_root);
         up_read(&fs_info->cleanup_work_sem);
         if (ret) {
             iput(inode);
             inode = ERR_PTR(ret);
         }
     }
 
     return inode;
 }
 
 static int btrfs_dentry_delete(const struct dentry *dentry)
 {
     struct btrfs_root *root;
     struct inode *inode = d_inode(dentry);
 
     if (!inode && !IS_ROOT(dentry))
         inode = d_inode(dentry->d_parent);
 
     if (inode) {
         root = BTRFS_I(inode)->root;
         if (btrfs_root_refs(&root->root_item) == 0)
             return 1;
 
         if (btrfs_ino(BTRFS_I(inode)) == BTRFS_EMPTY_SUBVOL_DIR_OBJECTID)
             return 1;
     }
     return 0;
 }
 
 static struct dentry *btrfs_lookup(struct inode *dir, struct dentry *dentry,
                    unsigned int flags)
 {
     struct inode *inode = btrfs_lookup_dentry(dir, dentry);
 
     if (inode == ERR_PTR(-ENOENT))
         inode = NULL;
     return d_splice_alias(inode, dentry);
 }
 
 /*
  * All this infrastructure exists because dir_emit can fault, and we are holding
  * the tree lock when doing readdir.  For now just allocate a buffer and copy
  * our information into that, and then dir_emit from the buffer.  This is
  * similar to what NFS does, only we don't keep the buffer around in pagecache
  * because I'm afraid I'll mess that up.  Long term we need to make filldir do
  * copy_to_user_inatomic so we don't have to worry about page faulting under the
  * tree lock.
  */
 static int btrfs_opendir(struct inode *inode, struct file *file)
 {
     struct btrfs_file_private *private;
 
     private = kzalloc(sizeof(struct btrfs_file_private), GFP_KERNEL);
     if (!private)
         return -ENOMEM;
     private->filldir_buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
     if (!private->filldir_buf) {
         kfree(private);
         return -ENOMEM;
     }
     file->private_data = private;
     return 0;
 }
 
 struct dir_entry {
     u64 ino;
     u64 offset;
     unsigned type;
     int name_len;
 };
 
 static int btrfs_filldir(void *addr, int entries, struct dir_context *ctx)
 {
     while (entries--) {
         struct dir_entry *entry = addr;
         char *name = (char *)(entry + 1);
 
         ctx->pos = get_unaligned(&entry->offset);
         if (!dir_emit(ctx, name, get_unaligned(&entry->name_len),
                      get_unaligned(&entry->ino),
                      get_unaligned(&entry->type)))
             return 1;
         addr += sizeof(struct dir_entry) +
             get_unaligned(&entry->name_len);
         ctx->pos++;
     }
     return 0;
 }
 
 static int btrfs_real_readdir(struct file *file, struct dir_context *ctx)
 {
     struct inode *inode = file_inode(file);
     struct btrfs_root *root = BTRFS_I(inode)->root;
     struct btrfs_file_private *private = file->private_data;
     struct btrfs_dir_item *di;
     struct btrfs_key key;
     struct btrfs_key found_key;
     struct btrfs_path *path;
     void *addr;
     struct list_head ins_list;
     struct list_head del_list;
     int ret;
     char *name_ptr;
     int name_len;
     int entries = 0;
     int total_len = 0;
     bool put = false;
     struct btrfs_key location;
 
     if (!dir_emit_dots(file, ctx))
         return 0;
 
     path = btrfs_alloc_path();
     if (!path)
         return -ENOMEM;
 
     addr = private->filldir_buf;
     path->reada = READA_FORWARD;
 
     INIT_LIST_HEAD(&ins_list);
     INIT_LIST_HEAD(&del_list);
     put = btrfs_readdir_get_delayed_items(inode, &ins_list, &del_list);
 
 again:
     key.type = BTRFS_DIR_INDEX_KEY;
     key.offset = ctx->pos;
     key.objectid = btrfs_ino(BTRFS_I(inode));
 
     btrfs_for_each_slot(root, &key, &found_key, path, ret) {
         struct dir_entry *entry;
         struct extent_buffer *leaf = path->nodes[0];
 
         if (found_key.objectid != key.objectid)
             break;
         if (found_key.type != BTRFS_DIR_INDEX_KEY)
             break;
         if (found_key.offset < ctx->pos)
             continue;
         if (btrfs_should_delete_dir_index(&del_list, found_key.offset))
             continue;
         di = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_dir_item);
         name_len = btrfs_dir_name_len(leaf, di);
         if ((total_len + sizeof(struct dir_entry) + name_len) >=
             PAGE_SIZE) {
             btrfs_release_path(path);
             ret = btrfs_filldir(private->filldir_buf, entries, ctx);
             if (ret)
                 goto nopos;
             addr = private->filldir_buf;
             entries = 0;
             total_len = 0;
             goto again;
         }
 
         entry = addr;
         put_unaligned(name_len, &entry->name_len);
         name_ptr = (char *)(entry + 1);
         read_extent_buffer(leaf, name_ptr, (unsigned long)(di + 1),
                    name_len);
         put_unaligned(fs_ftype_to_dtype(btrfs_dir_type(leaf, di)),
                 &entry->type);
         btrfs_dir_item_key_to_cpu(leaf, di, &location);
         put_unaligned(location.objectid, &entry->ino);
         put_unaligned(found_key.offset, &entry->offset);
         entries++;
         addr += sizeof(struct dir_entry) + name_len;
         total_len += sizeof(struct dir_entry) + name_len;
     }
     /* Catch error encountered during iteration */
     if (ret < 0)
         goto err;
 
     btrfs_release_path(path);
 
     ret = btrfs_filldir(private->filldir_buf, entries, ctx);
     if (ret)
         goto nopos;
 
     ret = btrfs_readdir_delayed_dir_index(ctx, &ins_list);
     if (ret)
         goto nopos;
 
     /*
      * Stop new entries from being returned after we return the last
      * entry.
      *
      * New directory entries are assigned a strictly increasing
      * offset.  This means that new entries created during readdir
      * are *guaranteed* to be seen in the future by that readdir.
      * This has broken buggy programs which operate on names as
      * they're returned by readdir.  Until we re-use freed offsets
      * we have this hack to stop new entries from being returned
      * under the assumption that they'll never reach this huge
      * offset.
      *
      * This is being careful not to overflow 32bit loff_t unless the
      * last entry requires it because doing so has broken 32bit apps
      * in the past.
      */
     if (ctx->pos >= INT_MAX)
         ctx->pos = LLONG_MAX;
     else
         ctx->pos = INT_MAX;
 nopos:
     ret = 0;
 err:
     if (put)
         btrfs_readdir_put_delayed_items(inode, &ins_list, &del_list);
     btrfs_free_path(path);
     return ret;
 }
 
 /*
  * This is somewhat expensive, updating the tree every time the
  * inode changes.  But, it is most likely to find the inode in cache.
  * FIXME, needs more benchmarking...there are no reasons other than performance
  * to keep or drop this code.
  */
 static int btrfs_dirty_inode(struct inode *inode)
 {
     struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
     struct btrfs_root *root = BTRFS_I(inode)->root;
     struct btrfs_trans_handle *trans;
     int ret;
 
     if (test_bit(BTRFS_INODE_DUMMY, &BTRFS_I(inode)->runtime_flags))
         return 0;
 
     trans = btrfs_join_transaction(root);
     if (IS_ERR(trans))
         return PTR_ERR(trans);
 
     ret = btrfs_update_inode(trans, root, BTRFS_I(inode));
     if (ret && (ret == -ENOSPC || ret == -EDQUOT)) {
         /* whoops, lets try again with the full transaction */
         btrfs_end_transaction(trans);
         trans = btrfs_start_transaction(root, 1);
         if (IS_ERR(trans))
             return PTR_ERR(trans);
 
         ret = btrfs_update_inode(trans, root, BTRFS_I(inode));
     }
     btrfs_end_transaction(trans);
     if (BTRFS_I(inode)->delayed_node)
         btrfs_balance_delayed_items(fs_info);
 
     return ret;
 }
 
 /*
  * This is a copy of file_update_time.  We need this so we can return error on
  * ENOSPC for updating the inode in the case of file write and mmap writes.
  */
 static int btrfs_update_time(struct inode *inode, struct timespec64 *now,
                  int flags)
 {
     struct btrfs_root *root = BTRFS_I(inode)->root;
     bool dirty = flags & ~S_VERSION;
 
     if (btrfs_root_readonly(root))
         return -EROFS;
 
     if (flags & S_VERSION)
         dirty |= inode_maybe_inc_iversion(inode, dirty);
     if (flags & S_CTIME)
         inode->i_ctime = *now;
     if (flags & S_MTIME)
         inode->i_mtime = *now;
     if (flags & S_ATIME)
         inode->i_atime = *now;
     return dirty ? btrfs_dirty_inode(inode) : 0;
 }
 
 /*
  * find the highest existing sequence number in a directory
  * and then set the in-memory index_cnt variable to reflect
  * free sequence numbers
  */
 static int btrfs_set_inode_index_count(struct btrfs_inode *inode)
 {
     struct btrfs_root *root = inode->root;
     struct btrfs_key key, found_key;
     struct btrfs_path *path;
     struct extent_buffer *leaf;
     int ret;
 
     key.objectid = btrfs_ino(inode);
     key.type = BTRFS_DIR_INDEX_KEY;
     key.offset = (u64)-1;
 
     path = btrfs_alloc_path();
     if (!path)
         return -ENOMEM;
 
     ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
     if (ret < 0)
         goto out;
     /* FIXME: we should be able to handle this */
     if (ret == 0)
         goto out;
     ret = 0;
 
     if (path->slots[0] == 0) {
         inode->index_cnt = BTRFS_DIR_START_INDEX;
         goto out;
     }
 
     path->slots[0]--;
 
     leaf = path->nodes[0];
     btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
 
     if (found_key.objectid != btrfs_ino(inode) ||
         found_key.type != BTRFS_DIR_INDEX_KEY) {
         inode->index_cnt = BTRFS_DIR_START_INDEX;
         goto out;
     }
 
     inode->index_cnt = found_key.offset + 1;
 out:
     btrfs_free_path(path);
     return ret;
 }
 
 /*
  * helper to find a free sequence number in a given directory.  This current
  * code is very simple, later versions will do smarter things in the btree
  */
 int btrfs_set_inode_index(struct btrfs_inode *dir, u64 *index)
 {
     int ret = 0;
 
     if (dir->index_cnt == (u64)-1) {
         ret = btrfs_inode_delayed_dir_index_count(dir);
         if (ret) {
             ret = btrfs_set_inode_index_count(dir);
             if (ret)
                 return ret;
         }
     }
 
     *index = dir->index_cnt;
     dir->index_cnt++;
 
     return ret;
 }
 
 static int btrfs_insert_inode_locked(struct inode *inode)
 {
     struct btrfs_iget_args args;
 
     args.ino = BTRFS_I(inode)->location.objectid;
     args.root = BTRFS_I(inode)->root;
 
     return insert_inode_locked4(inode,
            btrfs_inode_hash(inode->i_ino, BTRFS_I(inode)->root),
            btrfs_find_actor, &args);
 }
 
 int btrfs_new_inode_prepare(struct btrfs_new_inode_args *args,
                 unsigned int *trans_num_items)
 {
     struct inode *dir = args->dir;
     struct inode *inode = args->inode;
     int ret;
 
     ret = posix_acl_create(dir, &inode->i_mode, &args->default_acl, &args->acl);
     if (ret)
         return ret;
 
     /* 1 to add inode item */
     *trans_num_items = 1;
     /* 1 to add compression property */
     if (BTRFS_I(dir)->prop_compress)
         (*trans_num_items)++;
     /* 1 to add default ACL xattr */
     if (args->default_acl)
         (*trans_num_items)++;
     /* 1 to add access ACL xattr */
     if (args->acl)
         (*trans_num_items)++;
 #ifdef CONFIG_SECURITY
     /* 1 to add LSM xattr */
     if (dir->i_security)
         (*trans_num_items)++;
 #endif
     if (args->orphan) {
         /* 1 to add orphan item */
         (*trans_num_items)++;
     } else {
         /*
          * 1 to add dir item
          * 1 to add dir index
          * 1 to update parent inode item
          *
          * No need for 1 unit for the inode ref item because it is
          * inserted in a batch together with the inode item at
          * btrfs_create_new_inode().
          */
         *trans_num_items += 3;
     }
     return 0;
 }
 
 void btrfs_new_inode_args_destroy(struct btrfs_new_inode_args *args)
 {
     posix_acl_release(args->acl);
     posix_acl_release(args->default_acl);
 }
 
 /*
  * Inherit flags from the parent inode.
  *
  * Currently only the compression flags and the cow flags are inherited.
  */
 static void btrfs_inherit_iflags(struct inode *inode, struct inode *dir)
 {
     unsigned int flags;
 
     flags = BTRFS_I(dir)->flags;
 
     if (flags & BTRFS_INODE_NOCOMPRESS) {
         BTRFS_I(inode)->flags &= ~BTRFS_INODE_COMPRESS;
         BTRFS_I(inode)->flags |= BTRFS_INODE_NOCOMPRESS;
     } else if (flags & BTRFS_INODE_COMPRESS) {
         BTRFS_I(inode)->flags &= ~BTRFS_INODE_NOCOMPRESS;
         BTRFS_I(inode)->flags |= BTRFS_INODE_COMPRESS;
     }
 
     if (flags & BTRFS_INODE_NODATACOW) {
         BTRFS_I(inode)->flags |= BTRFS_INODE_NODATACOW;
         if (S_ISREG(inode->i_mode))
             BTRFS_I(inode)->flags |= BTRFS_INODE_NODATASUM;
     }
 
     btrfs_sync_inode_flags_to_i_flags(inode);
 }
 
 int btrfs_create_new_inode(struct btrfs_trans_handle *trans,
                struct btrfs_new_inode_args *args)
 {
     struct inode *dir = args->dir;
     struct inode *inode = args->inode;
     const char *name = args->orphan ? NULL : args->dentry->d_name.name;
     int name_len = args->orphan ? 0 : args->dentry->d_name.len;
     struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb);
     struct btrfs_root *root;
     struct btrfs_inode_item *inode_item;
     struct btrfs_key *location;
     struct btrfs_path *path;
     u64 objectid;
     struct btrfs_inode_ref *ref;
     struct btrfs_key key[2];
     u32 sizes[2];
     struct btrfs_item_batch batch;
     unsigned long ptr;
     int ret;
 
     path = btrfs_alloc_path();
     if (!path)
         return -ENOMEM;
 
     if (!args->subvol)
         BTRFS_I(inode)->root = btrfs_grab_root(BTRFS_I(dir)->root);
     root = BTRFS_I(inode)->root;
 
     ret = btrfs_get_free_objectid(root, &objectid);
     if (ret)
         goto out;
     inode->i_ino = objectid;
 
     if (args->orphan) {
         /*
          * O_TMPFILE, set link count to 0, so that after this point, we
          * fill in an inode item with the correct link count.
          */
         set_nlink(inode, 0);
     } else {
         trace_btrfs_inode_request(dir);
 
         ret = btrfs_set_inode_index(BTRFS_I(dir), &BTRFS_I(inode)->dir_index);
         if (ret)
             goto out;
     }
     /* index_cnt is ignored for everything but a dir. */
     BTRFS_I(inode)->index_cnt = BTRFS_DIR_START_INDEX;
     BTRFS_I(inode)->generation = trans->transid;
     inode->i_generation = BTRFS_I(inode)->generation;
 
     /*
      * Subvolumes don't inherit flags from their parent directory.
      * Originally this was probably by accident, but we probably can't
      * change it now without compatibility issues.
      */
     if (!args->subvol)
         btrfs_inherit_iflags(inode, dir);
 
     if (S_ISREG(inode->i_mode)) {
         if (btrfs_test_opt(fs_info, NODATASUM))
             BTRFS_I(inode)->flags |= BTRFS_INODE_NODATASUM;
         if (btrfs_test_opt(fs_info, NODATACOW))
             BTRFS_I(inode)->flags |= BTRFS_INODE_NODATACOW |
                 BTRFS_INODE_NODATASUM;
     }
 
     location = &BTRFS_I(inode)->location;
     location->objectid = objectid;
     location->offset = 0;
     location->type = BTRFS_INODE_ITEM_KEY;
 
     ret = btrfs_insert_inode_locked(inode);
     if (ret < 0) {
         if (!args->orphan)
             BTRFS_I(dir)->index_cnt--;
         goto out;
     }
 
     /*
      * We could have gotten an inode number from somebody who was fsynced
      * and then removed in this same transaction, so let's just set full
      * sync since it will be a full sync anyway and this will blow away the
      * old info in the log.
      */
     btrfs_set_inode_full_sync(BTRFS_I(inode));
 
     key[0].objectid = objectid;
     key[0].type = BTRFS_INODE_ITEM_KEY;
     key[0].offset = 0;
 
     sizes[0] = sizeof(struct btrfs_inode_item);
 
     if (!args->orphan) {
         /*
          * Start new inodes with an inode_ref. This is slightly more
          * efficient for small numbers of hard links since they will
          * be packed into one item. Extended refs will kick in if we
          * add more hard links than can fit in the ref item.
          */
         key[1].objectid = objectid;
         key[1].type = BTRFS_INODE_REF_KEY;
         if (args->subvol) {
             key[1].offset = objectid;
             sizes[1] = 2 + sizeof(*ref);
         } else {
             key[1].offset = btrfs_ino(BTRFS_I(dir));
             sizes[1] = name_len + sizeof(*ref);
         }
     }
 
     batch.keys = &key[0];
     batch.data_sizes = &sizes[0];
     batch.total_data_size = sizes[0] + (args->orphan ? 0 : sizes[1]);
     batch.nr = args->orphan ? 1 : 2;
     ret = btrfs_insert_empty_items(trans, root, path, &batch);
     if (ret != 0) {
         btrfs_abort_transaction(trans, ret);
         goto discard;
     }
 
     inode->i_mtime = current_time(inode);
     inode->i_atime = inode->i_mtime;
     inode->i_ctime = inode->i_mtime;
     BTRFS_I(inode)->i_otime = inode->i_mtime;
 
     /*
      * We're going to fill the inode item now, so at this point the inode
      * must be fully initialized.
      */
 
     inode_item = btrfs_item_ptr(path->nodes[0], path->slots[0],
                   struct btrfs_inode_item);
     memzero_extent_buffer(path->nodes[0], (unsigned long)inode_item,
                  sizeof(*inode_item));
     fill_inode_item(trans, path->nodes[0], inode_item, inode);
 
     if (!args->orphan) {
         ref = btrfs_item_ptr(path->nodes[0], path->slots[0] + 1,
                      struct btrfs_inode_ref);
         ptr = (unsigned long)(ref + 1);
         if (args->subvol) {
             btrfs_set_inode_ref_name_len(path->nodes[0], ref, 2);
             btrfs_set_inode_ref_index(path->nodes[0], ref, 0);
             write_extent_buffer(path->nodes[0], "..", ptr, 2);
         } else {
             btrfs_set_inode_ref_name_len(path->nodes[0], ref, name_len);
             btrfs_set_inode_ref_index(path->nodes[0], ref,
                           BTRFS_I(inode)->dir_index);
             write_extent_buffer(path->nodes[0], name, ptr, name_len);
         }
     }
 
     btrfs_mark_buffer_dirty(path->nodes[0]);
     /*
      * We don't need the path anymore, plus inheriting properties, adding
      * ACLs, security xattrs, orphan item or adding the link, will result in
      * allocating yet another path. So just free our path.
      */
     btrfs_free_path(path);
     path = NULL;
 
     if (args->subvol) {
         struct inode *parent;
 
         /*
          * Subvolumes inherit properties from their parent subvolume,
          * not the directory they were created in.
          */
         parent = btrfs_iget(fs_info->sb, BTRFS_FIRST_FREE_OBJECTID,
                     BTRFS_I(dir)->root);
         if (IS_ERR(parent)) {
             ret = PTR_ERR(parent);
         } else {
             ret = btrfs_inode_inherit_props(trans, inode, parent);
             iput(parent);
         }
     } else {
         ret = btrfs_inode_inherit_props(trans, inode, dir);
     }
     if (ret) {
         btrfs_err(fs_info,
               "error inheriting props for ino %llu (root %llu): %d",
               btrfs_ino(BTRFS_I(inode)), root->root_key.objectid,
               ret);
     }
 
     /*
      * Subvolumes don't inherit ACLs or get passed to the LSM. This is
      * probably a bug.
      */
     if (!args->subvol) {
         ret = btrfs_init_inode_security(trans, args);
         if (ret) {
             btrfs_abort_transaction(trans, ret);
             goto discard;
         }
     }
 
     inode_tree_add(inode);
 
     trace_btrfs_inode_new(inode);
     btrfs_set_inode_last_trans(trans, BTRFS_I(inode));
 
     btrfs_update_root_times(trans, root);
 
     if (args->orphan) {
         ret = btrfs_orphan_add(trans, BTRFS_I(inode));
     } else {
         ret = btrfs_add_link(trans, BTRFS_I(dir), BTRFS_I(inode), name,
                      name_len, 0, BTRFS_I(inode)->dir_index);
     }
     if (ret) {
         btrfs_abort_transaction(trans, ret);
         goto discard;
     }
 
     return 0;
 
 discard:
     /*
      * discard_new_inode() calls iput(), but the caller owns the reference
      * to the inode.
      */
     ihold(inode);
     discard_new_inode(inode);
 out:
     btrfs_free_path(path);
     return ret;
 }
 
 /*
  * utility function to add 'inode' into 'parent_inode' with
  * a give name and a given sequence number.
  * if 'add_backref' is true, also insert a backref from the
  * inode to the parent directory.
  */
 int btrfs_add_link(struct btrfs_trans_handle *trans,
            struct btrfs_inode *parent_inode, struct btrfs_inode *inode,
            const char *name, int name_len, int add_backref, u64 index)
 {
     int ret = 0;
     struct btrfs_key key;
     struct btrfs_root *root = parent_inode->root;
     u64 ino = btrfs_ino(inode);
     u64 parent_ino = btrfs_ino(parent_inode);
 
     if (unlikely(ino == BTRFS_FIRST_FREE_OBJECTID)) {
         memcpy(&key, &inode->root->root_key, sizeof(key));
     } else {
         key.objectid = ino;
         key.type = BTRFS_INODE_ITEM_KEY;
         key.offset = 0;
     }
 
     if (unlikely(ino == BTRFS_FIRST_FREE_OBJECTID)) {
         ret = btrfs_add_root_ref(trans, key.objectid,
                      root->root_key.objectid, parent_ino,
                      index, name, name_len);
     } else if (add_backref) {
         ret = btrfs_insert_inode_ref(trans, root, name, name_len, ino,
                          parent_ino, index);
     }
 
     /* Nothing to clean up yet */
     if (ret)
         return ret;
 
     ret = btrfs_insert_dir_item(trans, name, name_len, parent_inode, &key,
                     btrfs_inode_type(&inode->vfs_inode), index);
     if (ret == -EEXIST || ret == -EOVERFLOW)
         goto fail_dir_item;
     else if (ret) {
         btrfs_abort_transaction(trans, ret);
         return ret;
     }
 
     btrfs_i_size_write(parent_inode, parent_inode->vfs_inode.i_size +
                name_len * 2);
     inode_inc_iversion(&parent_inode->vfs_inode);
     /*
      * If we are replaying a log tree, we do not want to update the mtime
      * and ctime of the parent directory with the current time, since the
      * log replay procedure is responsible for setting them to their correct
      * values (the ones it had when the fsync was done).
      */
     if (!test_bit(BTRFS_FS_LOG_RECOVERING, &root->fs_info->flags)) {
         struct timespec64 now = current_time(&parent_inode->vfs_inode);
 
         parent_inode->vfs_inode.i_mtime = now;
         parent_inode->vfs_inode.i_ctime = now;
     }
     ret = btrfs_update_inode(trans, root, parent_inode);
     if (ret)
         btrfs_abort_transaction(trans, ret);
     return ret;
 
 fail_dir_item:
     if (unlikely(ino == BTRFS_FIRST_FREE_OBJECTID)) {
         u64 local_index;
         int err;
         err = btrfs_del_root_ref(trans, key.objectid,
                      root->root_key.objectid, parent_ino,
                      &local_index, name, name_len);
         if (err)
             btrfs_abort_transaction(trans, err);
     } else if (add_backref) {
         u64 local_index;
         int err;
 
         err = btrfs_del_inode_ref(trans, root, name, name_len,
                       ino, parent_ino, &local_index);
         if (err)
             btrfs_abort_transaction(trans, err);
     }
 
     /* Return the original error code */
     return ret;
 }
 
 static int btrfs_create_common(struct inode *dir, struct dentry *dentry,
                    struct inode *inode)
 {
     struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb);
     struct btrfs_root *root = BTRFS_I(dir)->root;
     struct btrfs_new_inode_args new_inode_args = {
         .dir = dir,
         .dentry = dentry,
         .inode = inode,
     };
     unsigned int trans_num_items;
     struct btrfs_trans_handle *trans;
     int err;
 
     err = btrfs_new_inode_prepare(&new_inode_args, &trans_num_items);
     if (err)
         goto out_inode;
 
     trans = btrfs_start_transaction(root, trans_num_items);
     if (IS_ERR(trans)) {
         err = PTR_ERR(trans);
         goto out_new_inode_args;
     }
 
     err = btrfs_create_new_inode(trans, &new_inode_args);
     if (!err)
         d_instantiate_new(dentry, inode);
 
     btrfs_end_transaction(trans);
     btrfs_btree_balance_dirty(fs_info);
 out_new_inode_args:
     btrfs_new_inode_args_destroy(&new_inode_args);
 out_inode:
     if (err)
         iput(inode);
     return err;
 }
 
 static int btrfs_mknod(struct user_namespace *mnt_userns, struct inode *dir,
                struct dentry *dentry, umode_t mode, dev_t rdev)
 {
     struct inode *inode;
 
     inode = new_inode(dir->i_sb);
     if (!inode)
         return -ENOMEM;
     inode_init_owner(mnt_userns, inode, dir, mode);
     inode->i_op = &btrfs_special_inode_operations;
     init_special_inode(inode, inode->i_mode, rdev);
     return btrfs_create_common(dir, dentry, inode);
 }
 
 static int btrfs_create(struct user_namespace *mnt_userns, struct inode *dir,
             struct dentry *dentry, umode_t mode, bool excl)
 {
     struct inode *inode;
 
     inode = new_inode(dir->i_sb);
     if (!inode)
         return -ENOMEM;
     inode_init_owner(mnt_userns, inode, dir, mode);
     inode->i_fop = &btrfs_file_operations;
     inode->i_op = &btrfs_file_inode_operations;
     inode->i_mapping->a_ops = &btrfs_aops;
     return btrfs_create_common(dir, dentry, inode);
 }
 
 static int btrfs_link(struct dentry *old_dentry, struct inode *dir,
               struct dentry *dentry)
 {
     struct btrfs_trans_handle *trans = NULL;
     struct btrfs_root *root = BTRFS_I(dir)->root;
     struct inode *inode = d_inode(old_dentry);
     struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
     u64 index;
     int err;
     int drop_inode = 0;
 
     /* do not allow sys_link's with other subvols of the same device */
     if (root->root_key.objectid != BTRFS_I(inode)->root->root_key.objectid)
         return -EXDEV;
 
     if (inode->i_nlink >= BTRFS_LINK_MAX)
         return -EMLINK;
 
     err = btrfs_set_inode_index(BTRFS_I(dir), &index);
     if (err)
         goto fail;
 
     /*
      * 2 items for inode and inode ref
      * 2 items for dir items
      * 1 item for parent inode
      * 1 item for orphan item deletion if O_TMPFILE
      */
     trans = btrfs_start_transaction(root, inode->i_nlink ? 5 : 6);
     if (IS_ERR(trans)) {
         err = PTR_ERR(trans);
         trans = NULL;
         goto fail;
     }
 
     /* There are several dir indexes for this inode, clear the cache. */
     BTRFS_I(inode)->dir_index = 0ULL;
     inc_nlink(inode);
     inode_inc_iversion(inode);
     inode->i_ctime = current_time(inode);
     ihold(inode);
     set_bit(BTRFS_INODE_COPY_EVERYTHING, &BTRFS_I(inode)->runtime_flags);
 
     err = btrfs_add_link(trans, BTRFS_I(dir), BTRFS_I(inode),
                  dentry->d_name.name, dentry->d_name.len, 1, index);
 
     if (err) {
         drop_inode = 1;
     } else {
         struct dentry *parent = dentry->d_parent;
 
         err = btrfs_update_inode(trans, root, BTRFS_I(inode));
         if (err)
             goto fail;
         if (inode->i_nlink == 1) {
             /*
              * If new hard link count is 1, it's a file created
              * with open(2) O_TMPFILE flag.
              */
             err = btrfs_orphan_del(trans, BTRFS_I(inode));
             if (err)
                 goto fail;
         }
         d_instantiate(dentry, inode);
         btrfs_log_new_name(trans, old_dentry, NULL, 0, parent);
     }
 
 fail:
     if (trans)
         btrfs_end_transaction(trans);
     if (drop_inode) {
         inode_dec_link_count(inode);
         iput(inode);
     }
     btrfs_btree_balance_dirty(fs_info);
     return err;
 }
 
 static int btrfs_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
                struct dentry *dentry, umode_t mode)
 {
     struct inode *inode;
 
     inode = new_inode(dir->i_sb);
     if (!inode)
         return -ENOMEM;
     inode_init_owner(mnt_userns, inode, dir, S_IFDIR | mode);
     inode->i_op = &btrfs_dir_inode_operations;
     inode->i_fop = &btrfs_dir_file_operations;
     return btrfs_create_common(dir, dentry, inode);
 }
 
 static noinline int uncompress_inline(struct btrfs_path *path,
                       struct page *page,
                       size_t pg_offset, u64 extent_offset,
                       struct btrfs_file_extent_item *item)
 {
     int ret;
     struct extent_buffer *leaf = path->nodes[0];
     char *tmp;
     size_t max_size;
     unsigned long inline_size;
     unsigned long ptr;
     int compress_type;
 
     WARN_ON(pg_offset != 0);
     compress_type = btrfs_file_extent_compression(leaf, item);
     max_size = btrfs_file_extent_ram_bytes(leaf, item);
     inline_size = btrfs_file_extent_inline_item_len(leaf, path->slots[0]);
     tmp = kmalloc(inline_size, GFP_NOFS);
     if (!tmp)
         return -ENOMEM;
     ptr = btrfs_file_extent_inline_start(item);
 
     read_extent_buffer(leaf, tmp, ptr, inline_size);
 
     max_size = min_t(unsigned long, PAGE_SIZE, max_size);
     ret = btrfs_decompress(compress_type, tmp, page,
                    extent_offset, inline_size, max_size);
 
     /*
      * decompression code contains a memset to fill in any space between the end
      * of the uncompressed data and the end of max_size in case the decompressed
      * data ends up shorter than ram_bytes.  That doesn't cover the hole between
      * the end of an inline extent and the beginning of the next block, so we
      * cover that region here.
      */
 
     if (max_size + pg_offset < PAGE_SIZE)
         memzero_page(page,  pg_offset + max_size,
                  PAGE_SIZE - max_size - pg_offset);
     kfree(tmp);
     return ret;
 }
 
 /**
  * btrfs_get_extent - Lookup the first extent overlapping a range in a file.
  * @inode:  file to search in
  * @page:   page to read extent data into if the extent is inline
  * @pg_offset:  offset into @page to copy to
  * @start:  file offset
  * @len:    length of range starting at @start
  *
  * This returns the first &struct extent_map which overlaps with the given
  * range, reading it from the B-tree and caching it if necessary. Note that
  * there may be more extents which overlap the given range after the returned
  * extent_map.
  *
  * If @page is not NULL and the extent is inline, this also reads the extent
  * data directly into the page and marks the extent up to date in the io_tree.
  *
  * Return: ERR_PTR on error, non-NULL extent_map on success.
  */
 struct extent_map *btrfs_get_extent(struct btrfs_inode *inode,
                     struct page *page, size_t pg_offset,
                     u64 start, u64 len)
 {
     struct btrfs_fs_info *fs_info = inode->root->fs_info;
     int ret = 0;
     u64 extent_start = 0;
     u64 extent_end = 0;
     u64 objectid = btrfs_ino(inode);
     int extent_type = -1;
     struct btrfs_path *path = NULL;
     struct btrfs_root *root = inode->root;
     struct btrfs_file_extent_item *item;
     struct extent_buffer *leaf;
     struct btrfs_key found_key;
     struct extent_map *em = NULL;
     struct extent_map_tree *em_tree = &inode->extent_tree;
     struct extent_io_tree *io_tree = &inode->io_tree;
 
     read_lock(&em_tree->lock);
     em = lookup_extent_mapping(em_tree, start, len);
     read_unlock(&em_tree->lock);
 
     if (em) {
         if (em->start > start || em->start + em->len <= start)
             free_extent_map(em);
         else if (em->block_start == EXTENT_MAP_INLINE && page)
             free_extent_map(em);
         else
             goto out;
     }
     em = alloc_extent_map();
     if (!em) {
         ret = -ENOMEM;
         goto out;
     }
     em->start = EXTENT_MAP_HOLE;
     em->orig_start = EXTENT_MAP_HOLE;
     em->len = (u64)-1;
     em->block_len = (u64)-1;
 
     path = btrfs_alloc_path();
     if (!path) {
         ret = -ENOMEM;
         goto out;
     }
 
     /* Chances are we'll be called again, so go ahead and do readahead */
     path->reada = READA_FORWARD;
 
     /*
      * The same explanation in load_free_space_cache applies here as well,
      * we only read when we're loading the free space cache, and at that
      * point the commit_root has everything we need.
      */
     if (btrfs_is_free_space_inode(inode)) {
         path->search_commit_root = 1;
         path->skip_locking = 1;
     }
 
     ret = btrfs_lookup_file_extent(NULL, root, path, objectid, start, 0);
     if (ret < 0) {
         goto out;
     } else if (ret > 0) {
         if (path->slots[0] == 0)
             goto not_found;
         path->slots[0]--;
         ret = 0;
     }
 
     leaf = path->nodes[0];
     item = btrfs_item_ptr(leaf, path->slots[0],
                   struct btrfs_file_extent_item);
     btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
     if (found_key.objectid != objectid ||
         found_key.type != BTRFS_EXTENT_DATA_KEY) {
         /*
          * If we backup past the first extent we want to move forward
          * and see if there is an extent in front of us, otherwise we'll
          * say there is a hole for our whole search range which can
          * cause problems.
          */
         extent_end = start;
         goto next;
     }
 
     extent_type = btrfs_file_extent_type(leaf, item);
     extent_start = found_key.offset;
     extent_end = btrfs_file_extent_end(path);
     if (extent_type == BTRFS_FILE_EXTENT_REG ||
         extent_type == BTRFS_FILE_EXTENT_PREALLOC) {
         /* Only regular file could have regular/prealloc extent */
         if (!S_ISREG(inode->vfs_inode.i_mode)) {
             ret = -EUCLEAN;
             btrfs_crit(fs_info,
         "regular/prealloc extent found for non-regular inode %llu",
                    btrfs_ino(inode));
             goto out;
         }
         trace_btrfs_get_extent_show_fi_regular(inode, leaf, item,
                                extent_start);
     } else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
         trace_btrfs_get_extent_show_fi_inline(inode, leaf, item,
                               path->slots[0],
                               extent_start);
     }
 next:
     if (start >= extent_end) {
         path->slots[0]++;
         if (path->slots[0] >= btrfs_header_nritems(leaf)) {
             ret = btrfs_next_leaf(root, path);
             if (ret < 0)
                 goto out;
             else if (ret > 0)
                 goto not_found;
 
             leaf = path->nodes[0];
         }
         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
         if (found_key.objectid != objectid ||
             found_key.type != BTRFS_EXTENT_DATA_KEY)
             goto not_found;
         if (start + len <= found_key.offset)
             goto not_found;
         if (start > found_key.offset)
             goto next;
 
         /* New extent overlaps with existing one */
         em->start = start;
         em->orig_start = start;
         em->len = found_key.offset - start;
         em->block_start = EXTENT_MAP_HOLE;
         goto insert;
     }
 
     btrfs_extent_item_to_extent_map(inode, path, item, !page, em);
 
     if (extent_type == BTRFS_FILE_EXTENT_REG ||
         extent_type == BTRFS_FILE_EXTENT_PREALLOC) {
         goto insert;
     } else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
         unsigned long ptr;
         char *map;
         size_t size;
         size_t extent_offset;
         size_t copy_size;
 
         if (!page)
             goto out;
 
         size = btrfs_file_extent_ram_bytes(leaf, item);
         extent_offset = page_offset(page) + pg_offset - extent_start;
         copy_size = min_t(u64, PAGE_SIZE - pg_offset,
                   size - extent_offset);
         em->start = extent_start + extent_offset;
         em->len = ALIGN(copy_size, fs_info->sectorsize);
         em->orig_block_len = em->len;
         em->orig_start = em->start;
         ptr = btrfs_file_extent_inline_start(item) + extent_offset;
 
         if (!PageUptodate(page)) {
             if (btrfs_file_extent_compression(leaf, item) !=
                 BTRFS_COMPRESS_NONE) {
                 ret = uncompress_inline(path, page, pg_offset,
                             extent_offset, item);
                 if (ret)
                     goto out;
             } else {
                 map = kmap_local_page(page);
                 read_extent_buffer(leaf, map + pg_offset, ptr,
                            copy_size);
                 if (pg_offset + copy_size < PAGE_SIZE) {
                     memset(map + pg_offset + copy_size, 0,
                            PAGE_SIZE - pg_offset -
                            copy_size);
                 }
                 kunmap_local(map);
             }
             flush_dcache_page(page);
         }
         set_extent_uptodate(io_tree, em->start,
                     extent_map_end(em) - 1, NULL, GFP_NOFS);
         goto insert;
     }
 not_found:
     em->start = start;
     em->orig_start = start;
     em->len = len;
     em->block_start = EXTENT_MAP_HOLE;
 insert:
     ret = 0;
     btrfs_release_path(path);
     if (em->start > start || extent_map_end(em) <= start) {
         btrfs_err(fs_info,
               "bad extent! em: [%llu %llu] passed [%llu %llu]",
               em->start, em->len, start, len);
         ret = -EIO;
         goto out;
     }
 
     write_lock(&em_tree->lock);
     ret = btrfs_add_extent_mapping(fs_info, em_tree, &em, start, len);
     write_unlock(&em_tree->lock);
 out:
     btrfs_free_path(path);
 
     trace_btrfs_get_extent(root, inode, em);
 
     if (ret) {
         free_extent_map(em);
         return ERR_PTR(ret);
     }
     return em;
 }
 
 struct extent_map *btrfs_get_extent_fiemap(struct btrfs_inode *inode,
                        u64 start, u64 len)
 {
     struct extent_map *em;
     struct extent_map *hole_em = NULL;
     u64 delalloc_start = start;
     u64 end;
     u64 delalloc_len;
     u64 delalloc_end;
     int err = 0;
 
     em = btrfs_get_extent(inode, NULL, 0, start, len);
     if (IS_ERR(em))
         return em;
     /*
      * If our em maps to:
      * - a hole or
      * - a pre-alloc extent,
      * there might actually be delalloc bytes behind it.
      */
     if (em->block_start != EXTENT_MAP_HOLE &&
         !test_bit(EXTENT_FLAG_PREALLOC, &em->flags))
         return em;
     else
         hole_em = em;
 
     /* check to see if we've wrapped (len == -1 or similar) */
     end = start + len;
     if (end < start)
         end = (u64)-1;
     else
         end -= 1;
 
     em = NULL;
 
     /* ok, we didn't find anything, lets look for delalloc */
     delalloc_len = count_range_bits(&inode->io_tree, &delalloc_start,
                  end, len, EXTENT_DELALLOC, 1);
     delalloc_end = delalloc_start + delalloc_len;
     if (delalloc_end < delalloc_start)
         delalloc_end = (u64)-1;
 
     /*
      * We didn't find anything useful, return the original results from
      * get_extent()
      */
     if (delalloc_start > end || delalloc_end <= start) {
         em = hole_em;
         hole_em = NULL;
         goto out;
     }
 
     /*
      * Adjust the delalloc_start to make sure it doesn't go backwards from
      * the start they passed in
      */
     delalloc_start = max(start, delalloc_start);
     delalloc_len = delalloc_end - delalloc_start;
 
     if (delalloc_len > 0) {
         u64 hole_start;
         u64 hole_len;
         const u64 hole_end = extent_map_end(hole_em);
 
         em = alloc_extent_map();
         if (!em) {
             err = -ENOMEM;
             goto out;
         }
 
         ASSERT(hole_em);
         /*
          * When btrfs_get_extent can't find anything it returns one
          * huge hole
          *
          * Make sure what it found really fits our range, and adjust to
          * make sure it is based on the start from the caller
          */
         if (hole_end <= start || hole_em->start > end) {
                free_extent_map(hole_em);
                hole_em = NULL;
         } else {
                hole_start = max(hole_em->start, start);
                hole_len = hole_end - hole_start;
         }
 
         if (hole_em && delalloc_start > hole_start) {
             /*
              * Our hole starts before our delalloc, so we have to
              * return just the parts of the hole that go until the
              * delalloc starts
              */
             em->len = min(hole_len, delalloc_start - hole_start);
             em->start = hole_start;
             em->orig_start = hole_start;
             /*
              * Don't adjust block start at all, it is fixed at
              * EXTENT_MAP_HOLE
              */
             em->block_start = hole_em->block_start;
             em->block_len = hole_len;
             if (test_bit(EXTENT_FLAG_PREALLOC, &hole_em->flags))
                 set_bit(EXTENT_FLAG_PREALLOC, &em->flags);
         } else {
             /*
              * Hole is out of passed range or it starts after
              * delalloc range
              */
             em->start = delalloc_start;
             em->len = delalloc_len;
             em->orig_start = delalloc_start;
             em->block_start = EXTENT_MAP_DELALLOC;
             em->block_len = delalloc_len;
         }
     } else {
         return hole_em;
     }
 out:
 
     free_extent_map(hole_em);
     if (err) {
         free_extent_map(em);
         return ERR_PTR(err);
     }
     return em;
 }
 
 static struct extent_map *btrfs_create_dio_extent(struct btrfs_inode *inode,
                           const u64 start,
                           const u64 len,
                           const u64 orig_start,
                           const u64 block_start,
                           const u64 block_len,
                           const u64 orig_block_len,
                           const u64 ram_bytes,
                           const int type)
 {
     struct extent_map *em = NULL;
     int ret;
 
     if (type != BTRFS_ORDERED_NOCOW) {
         em = create_io_em(inode, start, len, orig_start, block_start,
                   block_len, orig_block_len, ram_bytes,
                   BTRFS_COMPRESS_NONE, /* compress_type */
                   type);
         if (IS_ERR(em))
             goto out;
     }
     ret = btrfs_add_ordered_extent(inode, start, len, len, block_start,
                        block_len, 0,
                        (1 << type) |
                        (1 << BTRFS_ORDERED_DIRECT),
                        BTRFS_COMPRESS_NONE);
     if (ret) {
         if (em) {
             free_extent_map(em);
             btrfs_drop_extent_cache(inode, start, start + len - 1, 0);
         }
         em = ERR_PTR(ret);
     }
  out:
 
     return em;
 }
 
 static struct extent_map *btrfs_new_extent_direct(struct btrfs_inode *inode,
                           u64 start, u64 len)
 {
     struct btrfs_root *root = inode->root;
     struct btrfs_fs_info *fs_info = root->fs_info;
     struct extent_map *em;
     struct btrfs_key ins;
     u64 alloc_hint;
     int ret;
 
     alloc_hint = get_extent_allocation_hint(inode, start, len);
     ret = btrfs_reserve_extent(root, len, len, fs_info->sectorsize,
                    0, alloc_hint, &ins, 1, 1);
     if (ret)
         return ERR_PTR(ret);
 
     em = btrfs_create_dio_extent(inode, start, ins.offset, start,
                      ins.objectid, ins.offset, ins.offset,
                      ins.offset, BTRFS_ORDERED_REGULAR);
     btrfs_dec_block_group_reservations(fs_info, ins.objectid);
     if (IS_ERR(em))
         btrfs_free_reserved_extent(fs_info, ins.objectid, ins.offset,
                        1);
 
     return em;
 }
 
 static bool btrfs_extent_readonly(struct btrfs_fs_info *fs_info, u64 bytenr)
 {
     struct btrfs_block_group *block_group;
     bool readonly = false;
 
     block_group = btrfs_lookup_block_group(fs_info, bytenr);
     if (!block_group || block_group->ro)
         readonly = true;
     if (block_group)
         btrfs_put_block_group(block_group);
     return readonly;
 }
 
 /*
  * Check if we can do nocow write into the range [@offset, @offset + @len)
  *
  * @offset: File offset
  * @len:    The length to write, will be updated to the nocow writeable
  *      range
  * @orig_start: (optional) Return the original file offset of the file extent
  * @orig_len:   (optional) Return the original on-disk length of the file extent
  * @ram_bytes:  (optional) Return the ram_bytes of the file extent
  * @strict: if true, omit optimizations that might force us into unnecessary
  *      cow. e.g., don't trust generation number.
  *
  * Return:
  * >0   and update @len if we can do nocow write
  *  0   if we can't do nocow write
  * <0   if error happened
  *
  * NOTE: This only checks the file extents, caller is responsible to wait for
  *   any ordered extents.
  */
 noinline int can_nocow_extent(struct inode *inode, u64 offset, u64 *len,
                   u64 *orig_start, u64 *orig_block_len,
                   u64 *ram_bytes, bool strict)
 {
     struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
     struct can_nocow_file_extent_args nocow_args = { 0 };
     struct btrfs_path *path;
     int ret;
     struct extent_buffer *leaf;
     struct btrfs_root *root = BTRFS_I(inode)->root;
     struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
     struct btrfs_file_extent_item *fi;
     struct btrfs_key key;
     int found_type;
 
     path = btrfs_alloc_path();
     if (!path)
         return -ENOMEM;
 
     ret = btrfs_lookup_file_extent(NULL, root, path,
             btrfs_ino(BTRFS_I(inode)), offset, 0);
     if (ret < 0)
         goto out;
 
     if (ret == 1) {
         if (path->slots[0] == 0) {
             /* can't find the item, must cow */
             ret = 0;
             goto out;
         }
         path->slots[0]--;
     }
     ret = 0;
     leaf = path->nodes[0];
     btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
     if (key.objectid != btrfs_ino(BTRFS_I(inode)) ||
         key.type != BTRFS_EXTENT_DATA_KEY) {
         /* not our file or wrong item type, must cow */
         goto out;
     }
 
     if (key.offset > offset) {
         /* Wrong offset, must cow */
         goto out;
     }
 
     if (btrfs_file_extent_end(path) <= offset)
         goto out;
 
     fi = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_file_extent_item);
     found_type = btrfs_file_extent_type(leaf, fi);
     if (ram_bytes)
         *ram_bytes = btrfs_file_extent_ram_bytes(leaf, fi);
 
     nocow_args.start = offset;
     nocow_args.end = offset + *len - 1;
     nocow_args.strict = strict;
     nocow_args.free_path = true;
 
     ret = can_nocow_file_extent(path, &key, BTRFS_I(inode), &nocow_args);
     /* can_nocow_file_extent() has freed the path. */
     path = NULL;
 
     if (ret != 1) {
         /* Treat errors as not being able to NOCOW. */
         ret = 0;
         goto out;
     }
 
     ret = 0;
     if (btrfs_extent_readonly(fs_info, nocow_args.disk_bytenr))
         goto out;
 
     if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATACOW) &&
         found_type == BTRFS_FILE_EXTENT_PREALLOC) {
         u64 range_end;
 
         range_end = round_up(offset + nocow_args.num_bytes,
                      root->fs_info->sectorsize) - 1;
         ret = test_range_bit(io_tree, offset, range_end,
                      EXTENT_DELALLOC, 0, NULL);
         if (ret) {
             ret = -EAGAIN;
             goto out;
         }
     }
 
     if (orig_start)
         *orig_start = key.offset - nocow_args.extent_offset;
     if (orig_block_len)
         *orig_block_len = nocow_args.disk_num_bytes;
 
     *len = nocow_args.num_bytes;
     ret = 1;
 out:
     btrfs_free_path(path);
     return ret;
 }
 
 static int lock_extent_direct(struct inode *inode, u64 lockstart, u64 lockend,
                   struct extent_state **cached_state,
                   unsigned int iomap_flags)
 {
     const bool writing = (iomap_flags & IOMAP_WRITE);
     const bool nowait = (iomap_flags & IOMAP_NOWAIT);
     struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
     struct btrfs_ordered_extent *ordered;
     int ret = 0;
 
     while (1) {
         if (nowait) {
             if (!try_lock_extent(io_tree, lockstart, lockend))
                 return -EAGAIN;
         } else {
             lock_extent_bits(io_tree, lockstart, lockend, cached_state);
         }
         /*
          * We're concerned with the entire range that we're going to be
          * doing DIO to, so we need to make sure there's no ordered
          * extents in this range.
          */
         ordered = btrfs_lookup_ordered_range(BTRFS_I(inode), lockstart,
                              lockend - lockstart + 1);
 
         /*
          * We need to make sure there are no buffered pages in this
          * range either, we could have raced between the invalidate in
          * generic_file_direct_write and locking the extent.  The
          * invalidate needs to happen so that reads after a write do not
          * get stale data.
          */
         if (!ordered &&
             (!writing || !filemap_range_has_page(inode->i_mapping,
                              lockstart, lockend)))
             break;
 
         unlock_extent_cached(io_tree, lockstart, lockend, cached_state);
 
         if (ordered) {
             if (nowait) {
                 btrfs_put_ordered_extent(ordered);
                 ret = -EAGAIN;
                 break;
             }
             /*
              * If we are doing a DIO read and the ordered extent we
              * found is for a buffered write, we can not wait for it
              * to complete and retry, because if we do so we can
              * deadlock with concurrent buffered writes on page
              * locks. This happens only if our DIO read covers more
              * than one extent map, if at this point has already
              * created an ordered extent for a previous extent map
              * and locked its range in the inode's io tree, and a
              * concurrent write against that previous extent map's
              * range and this range started (we unlock the ranges
              * in the io tree only when the bios complete and
              * buffered writes always lock pages before attempting
              * to lock range in the io tree).
              */
             if (writing ||
                 test_bit(BTRFS_ORDERED_DIRECT, &ordered->flags))
                 btrfs_start_ordered_extent(ordered, 1);
             else
                 ret = nowait ? -EAGAIN : -ENOTBLK;
             btrfs_put_ordered_extent(ordered);
         } else {
             /*
              * We could trigger writeback for this range (and wait
              * for it to complete) and then invalidate the pages for
              * this range (through invalidate_inode_pages2_range()),
              * but that can lead us to a deadlock with a concurrent
              * call to readahead (a buffered read or a defrag call
              * triggered a readahead) on a page lock due to an
              * ordered dio extent we created before but did not have
              * yet a corresponding bio submitted (whence it can not
              * complete), which makes readahead wait for that
              * ordered extent to complete while holding a lock on
              * that page.
              */
             ret = nowait ? -EAGAIN : -ENOTBLK;
         }
 
         if (ret)
             break;
 
         cond_resched();
     }
 
     return ret;
 }
 
 /* The callers of this must take lock_extent() */
 static struct extent_map *create_io_em(struct btrfs_inode *inode, u64 start,
                        u64 len, u64 orig_start, u64 block_start,
                        u64 block_len, u64 orig_block_len,
                        u64 ram_bytes, int compress_type,
                        int type)
 {
     struct extent_map_tree *em_tree;
     struct extent_map *em;
     int ret;
 
     ASSERT(type == BTRFS_ORDERED_PREALLOC ||
            type == BTRFS_ORDERED_COMPRESSED ||
            type == BTRFS_ORDERED_NOCOW ||
            type == BTRFS_ORDERED_REGULAR);
 
     em_tree = &inode->extent_tree;
     em = alloc_extent_map();
     if (!em)
         return ERR_PTR(-ENOMEM);
 
     em->start = start;
     em->orig_start = orig_start;
     em->len = len;
     em->block_len = block_len;
     em->block_start = block_start;
     em->orig_block_len = orig_block_len;
     em->ram_bytes = ram_bytes;
     em->generation = -1;
     set_bit(EXTENT_FLAG_PINNED, &em->flags);
     if (type == BTRFS_ORDERED_PREALLOC) {
         set_bit(EXTENT_FLAG_FILLING, &em->flags);
     } else if (type == BTRFS_ORDERED_COMPRESSED) {
         set_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
         em->compress_type = compress_type;
     }
 
     do {
         btrfs_drop_extent_cache(inode, em->start,
                     em->start + em->len - 1, 0);
         write_lock(&em_tree->lock);
         ret = add_extent_mapping(em_tree, em, 1);
         write_unlock(&em_tree->lock);
         /*
          * The caller has taken lock_extent(), who could race with us
          * to add em?
          */
     } while (ret == -EEXIST);
 
     if (ret) {
         free_extent_map(em);
         return ERR_PTR(ret);
     }
 
     /* em got 2 refs now, callers needs to do free_extent_map once. */
     return em;
 }
 
 
 static int btrfs_get_blocks_direct_write(struct extent_map **map,
                      struct inode *inode,
                      struct btrfs_dio_data *dio_data,
                      u64 start, u64 len,
                      unsigned int iomap_flags)
 {
     const bool nowait = (iomap_flags & IOMAP_NOWAIT);
     struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
     struct extent_map *em = *map;
     int type;
     u64 block_start, orig_start, orig_block_len, ram_bytes;
     struct btrfs_block_group *bg;
     bool can_nocow = false;
     bool space_reserved = false;
     u64 prev_len;
     int ret = 0;
 
     /*
      * We don't allocate a new extent in the following cases
      *
      * 1) The inode is marked as NODATACOW. In this case we'll just use the
      * existing extent.
      * 2) The extent is marked as PREALLOC. We're good to go here and can
      * just use the extent.
      *
      */
     if (test_bit(EXTENT_FLAG_PREALLOC, &em->flags) ||
         ((BTRFS_I(inode)->flags & BTRFS_INODE_NODATACOW) &&
          em->block_start != EXTENT_MAP_HOLE)) {
         if (test_bit(EXTENT_FLAG_PREALLOC, &em->flags))
             type = BTRFS_ORDERED_PREALLOC;
         else
             type = BTRFS_ORDERED_NOCOW;
         len = min(len, em->len - (start - em->start));
         block_start = em->block_start + (start - em->start);
 
         if (can_nocow_extent(inode, start, &len, &orig_start,
                      &orig_block_len, &ram_bytes, false) == 1) {
             bg = btrfs_inc_nocow_writers(fs_info, block_start);
             if (bg)
                 can_nocow = true;
         }
     }
 
     prev_len = len;
     if (can_nocow) {
         struct extent_map *em2;
 
         /* We can NOCOW, so only need to reserve metadata space. */
         ret = btrfs_delalloc_reserve_metadata(BTRFS_I(inode), len, len,
                               nowait);
         if (ret < 0) {
             /* Our caller expects us to free the input extent map. */
             free_extent_map(em);
             *map = NULL;
             btrfs_dec_nocow_writers(bg);
             if (nowait && (ret == -ENOSPC || ret == -EDQUOT))
                 ret = -EAGAIN;
             goto out;
         }
         space_reserved = true;
 
         em2 = btrfs_create_dio_extent(BTRFS_I(inode), start, len,
                           orig_start, block_start,
                           len, orig_block_len,
                           ram_bytes, type);
         btrfs_dec_nocow_writers(bg);
         if (type == BTRFS_ORDERED_PREALLOC) {
             free_extent_map(em);
             *map = em2;
             em = em2;
         }
 
         if (IS_ERR(em2)) {
             ret = PTR_ERR(em2);
             goto out;
         }
 
         dio_data->nocow_done = true;
     } else {
         /* Our caller expects us to free the input extent map. */
         free_extent_map(em);
         *map = NULL;
 
         if (nowait)
             return -EAGAIN;
 
         /*
          * If we could not allocate data space before locking the file
          * range and we can't do a NOCOW write, then we have to fail.
          */
         if (!dio_data->data_space_reserved)
             return -ENOSPC;
 
         /*
          * We have to COW and we have already reserved data space before,
          * so now we reserve only metadata.
          */
         ret = btrfs_delalloc_reserve_metadata(BTRFS_I(inode), len, len,
                               false);
         if (ret < 0)
             goto out;
         space_reserved = true;
 
         em = btrfs_new_extent_direct(BTRFS_I(inode), start, len);
         if (IS_ERR(em)) {
             ret = PTR_ERR(em);
             goto out;
         }
         *map = em;
         len = min(len, em->len - (start - em->start));
         if (len < prev_len)
             btrfs_delalloc_release_metadata(BTRFS_I(inode),
                             prev_len - len, true);
     }
 
     /*
      * We have created our ordered extent, so we can now release our reservation
      * for an outstanding extent.
      */
     btrfs_delalloc_release_extents(BTRFS_I(inode), prev_len);
 
     /*
      * Need to update the i_size under the extent lock so buffered
      * readers will get the updated i_size when we unlock.
      */
     if (start + len > i_size_read(inode))
         i_size_write(inode, start + len);
 out:
     if (ret && space_reserved) {
         btrfs_delalloc_release_extents(BTRFS_I(inode), len);
         btrfs_delalloc_release_metadata(BTRFS_I(inode), len, true);
     }
     return ret;
 }
 
 static int btrfs_dio_iomap_begin(struct inode *inode, loff_t start,
         loff_t length, unsigned int flags, struct iomap *iomap,
         struct iomap *srcmap)
 {
     struct iomap_iter *iter = container_of(iomap, struct iomap_iter, iomap);
     struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
     struct extent_map *em;
     struct extent_state *cached_state = NULL;
     struct btrfs_dio_data *dio_data = iter->private;
     u64 lockstart, lockend;
     const bool write = !!(flags & IOMAP_WRITE);
     int ret = 0;
     u64 len = length;
     const u64 data_alloc_len = length;
     bool unlock_extents = false;
 
     /*
      * We could potentially fault if we have a buffer > PAGE_SIZE, and if
      * we're NOWAIT we may submit a bio for a partial range and return
      * EIOCBQUEUED, which would result in an errant short read.
      *
      * The best way to handle this would be to allow for partial completions
      * of iocb's, so we could submit the partial bio, return and fault in
      * the rest of the pages, and then submit the io for the rest of the
      * range.  However we don't have that currently, so simply return
      * -EAGAIN at this point so that the normal path is used.
      */
     if (!write && (flags & IOMAP_NOWAIT) && length > PAGE_SIZE)
         return -EAGAIN;
 
     /*
      * Cap the size of reads to that usually seen in buffered I/O as we need
      * to allocate a contiguous array for the checksums.
      */
     if (!write)
         len = min_t(u64, len, fs_info->sectorsize * BTRFS_MAX_BIO_SECTORS);
 
     lockstart = start;
     lockend = start + len - 1;
 
     /*
      * iomap_dio_rw() only does filemap_write_and_wait_range(), which isn't
      * enough if we've written compressed pages to this area, so we need to
      * flush the dirty pages again to make absolutely sure that any
      * outstanding dirty pages are on disk - the first flush only starts
      * compression on the data, while keeping the pages locked, so by the
      * time the second flush returns we know bios for the compressed pages
      * were submitted and finished, and the pages no longer under writeback.
      *
      * If we have a NOWAIT request and we have any pages in the range that
      * are locked, likely due to compression still in progress, we don't want
      * to block on page locks. We also don't want to block on pages marked as
      * dirty or under writeback (same as for the non-compression case).
      * iomap_dio_rw() did the same check, but after that and before we got
      * here, mmap'ed writes may have happened or buffered reads started
      * (readpage() and readahead(), which lock pages), as we haven't locked
      * the file range yet.
      */
     if (test_bit(BTRFS_INODE_HAS_ASYNC_EXTENT,
              &BTRFS_I(inode)->runtime_flags)) {
         if (flags & IOMAP_NOWAIT) {
             if (filemap_range_needs_writeback(inode->i_mapping,
                               lockstart, lockend))
                 return -EAGAIN;
         } else {
             ret = filemap_fdatawrite_range(inode->i_mapping, start,
                                start + length - 1);
             if (ret)
                 return ret;
         }
     }
 
     memset(dio_data, 0, sizeof(*dio_data));
 
     /*
      * We always try to allocate data space and must do it before locking
      * the file range, to avoid deadlocks with concurrent writes to the same
      * range if the range has several extents and the writes don't expand the
      * current i_size (the inode lock is taken in shared mode). If we fail to
      * allocate data space here we continue and later, after locking the
      * file range, we fail with ENOSPC only if we figure out we can not do a
      * NOCOW write.
      */
     if (write && !(flags & IOMAP_NOWAIT)) {
         ret = btrfs_check_data_free_space(BTRFS_I(inode),
                           &dio_data->data_reserved,
                           start, data_alloc_len);
         if (!ret)
             dio_data->data_space_reserved = true;
         else if (ret && !(BTRFS_I(inode)->flags &
                   (BTRFS_INODE_NODATACOW | BTRFS_INODE_PREALLOC)))
             goto err;
     }
 
     /*
      * If this errors out it's because we couldn't invalidate pagecache for
      * this range and we need to fallback to buffered IO, or we are doing a
      * NOWAIT read/write and we need to block.
      */
     ret = lock_extent_direct(inode, lockstart, lockend, &cached_state, flags);
     if (ret < 0)
         goto err;
 
     em = btrfs_get_extent(BTRFS_I(inode), NULL, 0, start, len);
     if (IS_ERR(em)) {
         ret = PTR_ERR(em);
         goto unlock_err;
     }
 
     /*
      * Ok for INLINE and COMPRESSED extents we need to fallback on buffered
      * io.  INLINE is special, and we could probably kludge it in here, but
      * it's still buffered so for safety lets just fall back to the generic
      * buffered path.
      *
      * For COMPRESSED we _have_ to read the entire extent in so we can
      * decompress it, so there will be buffering required no matter what we
      * do, so go ahead and fallback to buffered.
      *
      * We return -ENOTBLK because that's what makes DIO go ahead and go back
      * to buffered IO.  Don't blame me, this is the price we pay for using
      * the generic code.
      */
     if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags) ||
         em->block_start == EXTENT_MAP_INLINE) {
         free_extent_map(em);
         /*
          * If we are in a NOWAIT context, return -EAGAIN in order to
          * fallback to buffered IO. This is not only because we can
          * block with buffered IO (no support for NOWAIT semantics at
          * the moment) but also to avoid returning short reads to user
          * space - this happens if we were able to read some data from
          * previous non-compressed extents and then when we fallback to
          * buffered IO, at btrfs_file_read_iter() by calling
          * filemap_read(), we fail to fault in pages for the read buffer,
          * in which case filemap_read() returns a short read (the number
          * of bytes previously read is > 0, so it does not return -EFAULT).
          */
         ret = (flags & IOMAP_NOWAIT) ? -EAGAIN : -ENOTBLK;
         goto unlock_err;
     }
 
     len = min(len, em->len - (start - em->start));
 
     /*
      * If we have a NOWAIT request and the range contains multiple extents
      * (or a mix of extents and holes), then we return -EAGAIN to make the
      * caller fallback to a context where it can do a blocking (without
      * NOWAIT) request. This way we avoid doing partial IO and returning
      * success to the caller, which is not optimal for writes and for reads
      * it can result in unexpected behaviour for an application.
      *
      * When doing a read, because we use IOMAP_DIO_PARTIAL when calling
      * iomap_dio_rw(), we can end up returning less data then what the caller
      * asked for, resulting in an unexpected, and incorrect, short read.
      * That is, the caller asked to read N bytes and we return less than that,
      * which is wrong unless we are crossing EOF. This happens if we get a
      * page fault error when trying to fault in pages for the buffer that is
      * associated to the struct iov_iter passed to iomap_dio_rw(), and we
      * have previously submitted bios for other extents in the range, in
      * which case iomap_dio_rw() may return us EIOCBQUEUED if not all of
      * those bios have completed by the time we get the page fault error,
      * which we return back to our caller - we should only return EIOCBQUEUED
      * after we have submitted bios for all the extents in the range.
      */
     if ((flags & IOMAP_NOWAIT) && len < length) {
         free_extent_map(em);
         ret = -EAGAIN;
         goto unlock_err;
     }
 
     if (write) {
         ret = btrfs_get_blocks_direct_write(&em, inode, dio_data,
                             start, len, flags);
         if (ret < 0)
             goto unlock_err;
         unlock_extents = true;
         /* Recalc len in case the new em is smaller than requested */
         len = min(len, em->len - (start - em->start));
         if (dio_data->data_space_reserved) {
             u64 release_offset;
             u64 release_len = 0;
 
             if (dio_data->nocow_done) {
                 release_offset = start;
                 release_len = data_alloc_len;
             } else if (len < data_alloc_len) {
                 release_offset = start + len;
                 release_len = data_alloc_len - len;
             }
 
             if (release_len > 0)
                 btrfs_free_reserved_data_space(BTRFS_I(inode),
                                    dio_data->data_reserved,
                                    release_offset,
                                    release_len);
         }
     } else {
         /*
          * We need to unlock only the end area that we aren't using.
          * The rest is going to be unlocked by the endio routine.
          */
         lockstart = start + len;
         if (lockstart < lockend)
             unlock_extents = true;
     }
 
     if (unlock_extents)
         unlock_extent_cached(&BTRFS_I(inode)->io_tree,
                      lockstart, lockend, &cached_state);
     else
         free_extent_state(cached_state);
 
     /*
      * Translate extent map information to iomap.
      * We trim the extents (and move the addr) even though iomap code does
      * that, since we have locked only the parts we are performing I/O in.
      */
     if ((em->block_start == EXTENT_MAP_HOLE) ||
         (test_bit(EXTENT_FLAG_PREALLOC, &em->flags) && !write)) {
         iomap->addr = IOMAP_NULL_ADDR;
         iomap->type = IOMAP_HOLE;
     } else {
         iomap->addr = em->block_start + (start - em->start);
         iomap->type = IOMAP_MAPPED;
     }
     iomap->offset = start;
     iomap->bdev = fs_info->fs_devices->latest_dev->bdev;
     iomap->length = len;
 
     if (write && btrfs_use_zone_append(BTRFS_I(inode), em->block_start))
         iomap->flags |= IOMAP_F_ZONE_APPEND;
 
     free_extent_map(em);
 
     return 0;
 
 unlock_err:
     unlock_extent_cached(&BTRFS_I(inode)->io_tree, lockstart, lockend,
                  &cached_state);
 err:
     if (dio_data->data_space_reserved) {
         btrfs_free_reserved_data_space(BTRFS_I(inode),
                            dio_data->data_reserved,
                            start, data_alloc_len);
         extent_changeset_free(dio_data->data_reserved);
     }
 
     return ret;
 }
 
 static int btrfs_dio_iomap_end(struct inode *inode, loff_t pos, loff_t length,
         ssize_t written, unsigned int flags, struct iomap *iomap)
 {
     struct iomap_iter *iter = container_of(iomap, struct iomap_iter, iomap);
     struct btrfs_dio_data *dio_data = iter->private;
     size_t submitted = dio_data->submitted;
     const bool write = !!(flags & IOMAP_WRITE);
     int ret = 0;
 
     if (!write && (iomap->type == IOMAP_HOLE)) {
         /* If reading from a hole, unlock and return */
         unlock_extent(&BTRFS_I(inode)->io_tree, pos, pos + length - 1);
         return 0;
     }
 
     if (submitted < length) {
         pos += submitted;
         length -= submitted;
         if (write)
             btrfs_mark_ordered_io_finished(BTRFS_I(inode), NULL,
                                pos, length, false);
         else
             unlock_extent(&BTRFS_I(inode)->io_tree, pos,
                       pos + length - 1);
         ret = -ENOTBLK;
     }
 
     if (write)
         extent_changeset_free(dio_data->data_reserved);
     return ret;
 }
 
 static void btrfs_dio_private_put(struct btrfs_dio_private *dip)
 {
     /*
      * This implies a barrier so that stores to dio_bio->bi_status before
      * this and loads of dio_bio->bi_status after this are fully ordered.
      */
     if (!refcount_dec_and_test(&dip->refs))
         return;
 
     if (btrfs_op(&dip->bio) == BTRFS_MAP_WRITE) {
         btrfs_mark_ordered_io_finished(BTRFS_I(dip->inode), NULL,
                            dip->file_offset, dip->bytes,
                            !dip->bio.bi_status);
     } else {
         unlock_extent(&BTRFS_I(dip->inode)->io_tree,
                   dip->file_offset,
                   dip->file_offset + dip->bytes - 1);
     }
 
     kfree(dip->csums);
     bio_endio(&dip->bio);
 }
 
 static void submit_dio_repair_bio(struct inode *inode, struct bio *bio,
                   int mirror_num,
                   enum btrfs_compression_type compress_type)
 {
     struct btrfs_dio_private *dip = bio->bi_private;
     struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
 
     BUG_ON(bio_op(bio) == REQ_OP_WRITE);
 
     refcount_inc(&dip->refs);
     btrfs_submit_bio(fs_info, bio, mirror_num);
 }
 
 static blk_status_t btrfs_check_read_dio_bio(struct btrfs_dio_private *dip,
                          struct btrfs_bio *bbio,
                          const bool uptodate)
 {
     struct inode *inode = dip->inode;
     struct btrfs_fs_info *fs_info = BTRFS_I(inode)->root->fs_info;
     struct extent_io_tree *failure_tree = &BTRFS_I(inode)->io_failure_tree;
     struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
     const bool csum = !(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM);
     blk_status_t err = BLK_STS_OK;
     struct bvec_iter iter;
     struct bio_vec bv;
     u32 offset;
 
     btrfs_bio_for_each_sector(fs_info, bv, bbio, iter, offset) {
         u64 start = bbio->file_offset + offset;
 
         if (uptodate &&
             (!csum || !btrfs_check_data_csum(inode, bbio, offset, bv.bv_page,
                            bv.bv_offset))) {
             clean_io_failure(fs_info, failure_tree, io_tree, start,
                      bv.bv_page, btrfs_ino(BTRFS_I(inode)),
                      bv.bv_offset);
         } else {
             int ret;
 
             ret = btrfs_repair_one_sector(inode, bbio, offset,
                     bv.bv_page, bv.bv_offset,
                     submit_dio_repair_bio);
             if (ret)
                 err = errno_to_blk_status(ret);
         }
     }
 
     return err;
 }
 
 static blk_status_t btrfs_submit_bio_start_direct_io(struct inode *inode,
                              struct bio *bio,
                              u64 dio_file_offset)
 {
     return btrfs_csum_one_bio(BTRFS_I(inode), bio, dio_file_offset, false);
 }
 
 static void btrfs_end_dio_bio(struct bio *bio)
 {
     struct btrfs_dio_private *dip = bio->bi_private;
     struct btrfs_bio *bbio = btrfs_bio(bio);
     blk_status_t err = bio->bi_status;
 
     if (err)
         btrfs_warn(BTRFS_I(dip->inode)->root->fs_info,
                "direct IO failed ino %llu rw %d,%u sector %#Lx len %u err no %d",
                btrfs_ino(BTRFS_I(dip->inode)), bio_op(bio),
                bio->bi_opf, bio->bi_iter.bi_sector,
                bio->bi_iter.bi_size, err);
 
     if (bio_op(bio) == REQ_OP_READ)
         err = btrfs_check_read_dio_bio(dip, bbio, !err);
 
     if (err)
         dip->bio.bi_status = err;
 
     btrfs_record_physical_zoned(dip->inode, bbio->file_offset, bio);
 
     bio_put(bio);
     btrfs_dio_private_put(dip);
 }
 
 static void btrfs_submit_dio_bio(struct bio *bio, struct inode *inode,
                  u64 file_offset, int async_submit)
 {
     struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
     struct btrfs_dio_private *dip = bio->bi_private;
     blk_status_t ret;
 
     /* Save the original iter for read repair */
     if (btrfs_op(bio) == BTRFS_MAP_READ)
         btrfs_bio(bio)->iter = bio->bi_iter;
 
     if (BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)
         goto map;
 
     if (btrfs_op(bio) == BTRFS_MAP_WRITE) {
         /* Check btrfs_submit_data_write_bio() for async submit rules */
         if (async_submit && !atomic_read(&BTRFS_I(inode)->sync_writers) &&
             btrfs_wq_submit_bio(inode, bio, 0, file_offset,
                     btrfs_submit_bio_start_direct_io))
             return;
 
         /*
          * If we aren't doing async submit, calculate the csum of the
          * bio now.
          */
         ret = btrfs_csum_one_bio(BTRFS_I(inode), bio, file_offset, false);
         if (ret) {
             bio->bi_status = ret;
             bio_endio(bio);
             return;
         }
     } else {
         btrfs_bio(bio)->csum = btrfs_csum_ptr(fs_info, dip->csums,
                               file_offset - dip->file_offset);
     }
 map:
     btrfs_submit_bio(fs_info, bio, 0);
 }
 
 static void btrfs_submit_direct(const struct iomap_iter *iter,
         struct bio *dio_bio, loff_t file_offset)
 {
     struct btrfs_dio_private *dip =
         container_of(dio_bio, struct btrfs_dio_private, bio);
     struct inode *inode = iter->inode;
     const bool write = (btrfs_op(dio_bio) == BTRFS_MAP_WRITE);
     struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
     const bool raid56 = (btrfs_data_alloc_profile(fs_info) &
                  BTRFS_BLOCK_GROUP_RAID56_MASK);
     struct bio *bio;
     u64 start_sector;
     int async_submit = 0;
     u64 submit_len;
     u64 clone_offset = 0;
     u64 clone_len;
     u64 logical;
     int ret;
     blk_status_t status;
     struct btrfs_io_geometry geom;
     struct btrfs_dio_data *dio_data = iter->private;
     struct extent_map *em = NULL;
 
     dip->inode = inode;
     dip->file_offset = file_offset;
     dip->bytes = dio_bio->bi_iter.bi_size;
     refcount_set(&dip->refs, 1);
     dip->csums = NULL;
 
     if (!write && !(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) {
         unsigned int nr_sectors =
             (dio_bio->bi_iter.bi_size >> fs_info->sectorsize_bits);
 
         /*
          * Load the csums up front to reduce csum tree searches and
          * contention when submitting bios.
          */
         status = BLK_STS_RESOURCE;
         dip->csums = kcalloc(nr_sectors, fs_info->csum_size, GFP_NOFS);
         if (!dip)
             goto out_err;
 
         status = btrfs_lookup_bio_sums(inode, dio_bio, dip->csums);
         if (status != BLK_STS_OK)
             goto out_err;
     }
 
     start_sector = dio_bio->bi_iter.bi_sector;
     submit_len = dio_bio->bi_iter.bi_size;
 
     do {
         logical = start_sector << 9;
         em = btrfs_get_chunk_map(fs_info, logical, submit_len);
         if (IS_ERR(em)) {
             status = errno_to_blk_status(PTR_ERR(em));
             em = NULL;
             goto out_err_em;
         }
         ret = btrfs_get_io_geometry(fs_info, em, btrfs_op(dio_bio),
                         logical, &geom);
         if (ret) {
             status = errno_to_blk_status(ret);
             goto out_err_em;
         }
 
         clone_len = min(submit_len, geom.len);
         ASSERT(clone_len <= UINT_MAX);
 
         /*
          * This will never fail as it's passing GPF_NOFS and
          * the allocation is backed by btrfs_bioset.
          */
         bio = btrfs_bio_clone_partial(dio_bio, clone_offset, clone_len);
         bio->bi_private = dip;
         bio->bi_end_io = btrfs_end_dio_bio;
         btrfs_bio(bio)->file_offset = file_offset;
 
         if (bio_op(bio) == REQ_OP_ZONE_APPEND) {
             status = extract_ordered_extent(BTRFS_I(inode), bio,
                             file_offset);
             if (status) {
                 bio_put(bio);
                 goto out_err;
             }
         }
 
         ASSERT(submit_len >= clone_len);
         submit_len -= clone_len;
 
         /*
          * Increase the count before we submit the bio so we know
          * the end IO handler won't happen before we increase the
          * count. Otherwise, the dip might get freed before we're
          * done setting it up.
          *
          * We transfer the initial reference to the last bio, so we
          * don't need to increment the reference count for the last one.
          */
         if (submit_len > 0) {
             refcount_inc(&dip->refs);
             /*
              * If we are submitting more than one bio, submit them
              * all asynchronously. The exception is RAID 5 or 6, as
              * asynchronous checksums make it difficult to collect
              * full stripe writes.
              */
             if (!raid56)
                 async_submit = 1;
         }
 
         btrfs_submit_dio_bio(bio, inode, file_offset, async_submit);
 
         dio_data->submitted += clone_len;
         clone_offset += clone_len;
         start_sector += clone_len >> 9;
         file_offset += clone_len;
 
         free_extent_map(em);
     } while (submit_len > 0);
     return;
 
 out_err_em:
     free_extent_map(em);
 out_err:
     dio_bio->bi_status = status;
     btrfs_dio_private_put(dip);
 }
 
 static const struct iomap_ops btrfs_dio_iomap_ops = {
     .iomap_begin            = btrfs_dio_iomap_begin,
     .iomap_end              = btrfs_dio_iomap_end,
 };
 
 static const struct iomap_dio_ops btrfs_dio_ops = {
     .submit_io      = btrfs_submit_direct,
     .bio_set        = &btrfs_dio_bioset,
 };
 
 ssize_t btrfs_dio_rw(struct kiocb *iocb, struct iov_iter *iter, size_t done_before)
 {
     struct btrfs_dio_data data;
 
     return iomap_dio_rw(iocb, iter, &btrfs_dio_iomap_ops, &btrfs_dio_ops,
                 IOMAP_DIO_PARTIAL | IOMAP_DIO_NOSYNC,
                 &data, done_before);
 }
 
 static int btrfs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
             u64 start, u64 len)
 {
     int ret;
 
     ret = fiemap_prep(inode, fieinfo, start, &len, 0);
     if (ret)
         return ret;
 
     return extent_fiemap(BTRFS_I(inode), fieinfo, start, len);
 }
 
 static int btrfs_writepages(struct address_space *mapping,
                 struct writeback_control *wbc)
 {
     return extent_writepages(mapping, wbc);
 }
 
 static void btrfs_readahead(struct readahead_control *rac)
 {
     extent_readahead(rac);
 }
 
 /*
  * For release_folio() and invalidate_folio() we have a race window where
  * folio_end_writeback() is called but the subpage spinlock is not yet released.
  * If we continue to release/invalidate the page, we could cause use-after-free
  * for subpage spinlock.  So this function is to spin and wait for subpage
  * spinlock.
  */
 static void wait_subpage_spinlock(struct page *page)
 {
     struct btrfs_fs_info *fs_info = btrfs_sb(page->mapping->host->i_sb);
     struct btrfs_subpage *subpage;
 
     if (!btrfs_is_subpage(fs_info, page))
         return;
 
     ASSERT(PagePrivate(page) && page->private);
     subpage = (struct btrfs_subpage *)page->private;
 
     /*
      * This may look insane as we just acquire the spinlock and release it,
      * without doing anything.  But we just want to make sure no one is
      * still holding the subpage spinlock.
      * And since the page is not dirty nor writeback, and we have page
      * locked, the only possible way to hold a spinlock is from the endio
      * function to clear page writeback.
      *
      * Here we just acquire the spinlock so that all existing callers
      * should exit and we're safe to release/invalidate the page.
      */
     spin_lock_irq(&subpage->lock);
     spin_unlock_irq(&subpage->lock);
 }
 
 static bool __btrfs_release_folio(struct folio *folio, gfp_t gfp_flags)
 {
     int ret = try_release_extent_mapping(&folio->page, gfp_flags);
 
     if (ret == 1) {
         wait_subpage_spinlock(&folio->page);
         clear_page_extent_mapped(&folio->page);
     }
     return ret;
 }
 
 static bool btrfs_release_folio(struct folio *folio, gfp_t gfp_flags)
 {
     if (folio_test_writeback(folio) || folio_test_dirty(folio))
         return false;
     return __btrfs_release_folio(folio, gfp_flags);
 }
 
 #ifdef CONFIG_MIGRATION
 static int btrfs_migrate_folio(struct address_space *mapping,
                  struct folio *dst, struct folio *src,
                  enum migrate_mode mode)
 {
     int ret = filemap_migrate_folio(mapping, dst, src, mode);
 
     if (ret != MIGRATEPAGE_SUCCESS)
         return ret;
 
     if (folio_test_ordered(src)) {
         folio_clear_ordered(src);
         folio_set_ordered(dst);
     }
 
     return MIGRATEPAGE_SUCCESS;
 }
 #else
 #define btrfs_migrate_folio NULL
 #endif
 
 static void btrfs_invalidate_folio(struct folio *folio, size_t offset,
                  size_t length)
 {
     struct btrfs_inode *inode = BTRFS_I(folio->mapping->host);
     struct btrfs_fs_info *fs_info = inode->root->fs_info;
     struct extent_io_tree *tree = &inode->io_tree;
     struct extent_state *cached_state = NULL;
     u64 page_start = folio_pos(folio);
     u64 page_end = page_start + folio_size(folio) - 1;
     u64 cur;
     int inode_evicting = inode->vfs_inode.i_state & I_FREEING;
 
     /*
      * We have folio locked so no new ordered extent can be created on this
      * page, nor bio can be submitted for this folio.
      *
      * But already submitted bio can still be finished on this folio.
      * Furthermore, endio function won't skip folio which has Ordered
      * (Private2) already cleared, so it's possible for endio and
      * invalidate_folio to do the same ordered extent accounting twice
      * on one folio.
      *
      * So here we wait for any submitted bios to finish, so that we won't
      * do double ordered extent accounting on the same folio.
      */
     folio_wait_writeback(folio);
     wait_subpage_spinlock(&folio->page);
 
     /*
      * For subpage case, we have call sites like
      * btrfs_punch_hole_lock_range() which passes range not aligned to
      * sectorsize.
      * If the range doesn't cover the full folio, we don't need to and
      * shouldn't clear page extent mapped, as folio->private can still
      * record subpage dirty bits for other part of the range.
      *
      * For cases that invalidate the full folio even the range doesn't
      * cover the full folio, like invalidating the last folio, we're
      * still safe to wait for ordered extent to finish.
      */
     if (!(offset == 0 && length == folio_size(folio))) {
         btrfs_release_folio(folio, GFP_NOFS);
         return;
     }
 
     if (!inode_evicting)
         lock_extent_bits(tree, page_start, page_end, &cached_state);
 
     cur = page_start;
     while (cur < page_end) {
         struct btrfs_ordered_extent *ordered;
         bool delete_states;
         u64 range_end;
         u32 range_len;
 
         ordered = btrfs_lookup_first_ordered_range(inode, cur,
                                page_end + 1 - cur);
         if (!ordered) {
             range_end = page_end;
             /*
              * No ordered extent covering this range, we are safe
              * to delete all extent states in the range.
              */
             delete_states = true;
             goto next;
         }
         if (ordered->file_offset > cur) {
             /*
              * There is a range between [cur, oe->file_offset) not
              * covered by any ordered extent.
              * We are safe to delete all extent states, and handle
              * the ordered extent in the next iteration.
              */
             range_end = ordered->file_offset - 1;
             delete_states = true;
             goto next;
         }
 
         range_end = min(ordered->file_offset + ordered->num_bytes - 1,
                 page_end);
         ASSERT(range_end + 1 - cur < U32_MAX);
         range_len = range_end + 1 - cur;
         if (!btrfs_page_test_ordered(fs_info, &folio->page, cur, range_len)) {
             /*
              * If Ordered (Private2) is cleared, it means endio has
              * already been executed for the range.
              * We can't delete the extent states as
              * btrfs_finish_ordered_io() may still use some of them.
              */
             delete_states = false;
             goto next;
         }
         btrfs_page_clear_ordered(fs_info, &folio->page, cur, range_len);
 
         /*
          * IO on this page will never be started, so we need to account
          * for any ordered extents now. Don't clear EXTENT_DELALLOC_NEW
          * here, must leave that up for the ordered extent completion.
          *
          * This will also unlock the range for incoming
          * btrfs_finish_ordered_io().
          */
         if (!inode_evicting)
             clear_extent_bit(tree, cur, range_end,
                      EXTENT_DELALLOC |
                      EXTENT_LOCKED | EXTENT_DO_ACCOUNTING |
                      EXTENT_DEFRAG, 1, 0, &cached_state);
 
         spin_lock_irq(&inode->ordered_tree.lock);
         set_bit(BTRFS_ORDERED_TRUNCATED, &ordered->flags);
         ordered->truncated_len = min(ordered->truncated_len,
                          cur - ordered->file_offset);
         spin_unlock_irq(&inode->ordered_tree.lock);
 
         if (btrfs_dec_test_ordered_pending(inode, &ordered,
                            cur, range_end + 1 - cur)) {
             btrfs_finish_ordered_io(ordered);
             /*
              * The ordered extent has finished, now we're again
              * safe to delete all extent states of the range.
              */
             delete_states = true;
         } else {
             /*
              * btrfs_finish_ordered_io() will get executed by endio
              * of other pages, thus we can't delete extent states
              * anymore
              */
             delete_states = false;
         }
 next:
         if (ordered)
             btrfs_put_ordered_extent(ordered);
         /*
          * Qgroup reserved space handler
          * Sector(s) here will be either:
          *
          * 1) Already written to disk or bio already finished
          *    Then its QGROUP_RESERVED bit in io_tree is already cleared.
          *    Qgroup will be handled by its qgroup_record then.
          *    btrfs_qgroup_free_data() call will do nothing here.
          *
          * 2) Not written to disk yet
          *    Then btrfs_qgroup_free_data() call will clear the
          *    QGROUP_RESERVED bit of its io_tree, and free the qgroup
          *    reserved data space.
          *    Since the IO will never happen for this page.
          */
         btrfs_qgroup_free_data(inode, NULL, cur, range_end + 1 - cur);
         if (!inode_evicting) {
             clear_extent_bit(tree, cur, range_end, EXTENT_LOCKED |
                  EXTENT_DELALLOC | EXTENT_UPTODATE |
                  EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG, 1,
                  delete_states, &cached_state);
         }
         cur = range_end + 1;
     }
     /*
      * We have iterated through all ordered extents of the page, the page
      * should not have Ordered (Private2) anymore, or the above iteration
      * did something wrong.
      */
     ASSERT(!folio_test_ordered(folio));
     btrfs_page_clear_checked(fs_info, &folio->page, folio_pos(folio), folio_size(folio));
     if (!inode_evicting)
         __btrfs_release_folio(folio, GFP_NOFS);
     clear_page_extent_mapped(&folio->page);
 }
 
 /*
  * btrfs_page_mkwrite() is not allowed to change the file size as it gets
  * called from a page fault handler when a page is first dirtied. Hence we must
  * be careful to check for EOF conditions here. We set the page up correctly
  * for a written page which means we get ENOSPC checking when writing into
  * holes and correct delalloc and unwritten extent mapping on filesystems that
  * support these features.
  *
  * We are not allowed to take the i_mutex here so we have to play games to
  * protect against truncate races as the page could now be beyond EOF.  Because
  * truncate_setsize() writes the inode size before removing pages, once we have
  * the page lock we can determine safely if the page is beyond EOF. If it is not
  * beyond EOF, then the page is guaranteed safe against truncation until we
  * unlock the page.
  */
 vm_fault_t btrfs_page_mkwrite(struct vm_fault *vmf)
 {
     struct page *page = vmf->page;
     struct inode *inode = file_inode(vmf->vma->vm_file);
     struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
     struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
     struct btrfs_ordered_extent *ordered;
     struct extent_state *cached_state = NULL;
     struct extent_changeset *data_reserved = NULL;
     unsigned long zero_start;
     loff_t size;
     vm_fault_t ret;
     int ret2;
     int reserved = 0;
     u64 reserved_space;
     u64 page_start;
     u64 page_end;
     u64 end;
 
     reserved_space = PAGE_SIZE;
 
     sb_start_pagefault(inode->i_sb);
     page_start = page_offset(page);
     page_end = page_start + PAGE_SIZE - 1;
     end = page_end;
 
     /*
      * Reserving delalloc space after obtaining the page lock can lead to
      * deadlock. For example, if a dirty page is locked by this function
      * and the call to btrfs_delalloc_reserve_space() ends up triggering
      * dirty page write out, then the btrfs_writepages() function could
      * end up waiting indefinitely to get a lock on the page currently
      * being processed by btrfs_page_mkwrite() function.
      */
     ret2 = btrfs_delalloc_reserve_space(BTRFS_I(inode), &data_reserved,
                         page_start, reserved_space);
     if (!ret2) {
         ret2 = file_update_time(vmf->vma->vm_file);
         reserved = 1;
     }
     if (ret2) {
         ret = vmf_error(ret2);
         if (reserved)
             goto out;
         goto out_noreserve;
     }
 
     ret = VM_FAULT_NOPAGE; /* make the VM retry the fault */
 again:
     down_read(&BTRFS_I(inode)->i_mmap_lock);
     lock_page(page);
     size = i_size_read(inode);
 
     if ((page->mapping != inode->i_mapping) ||
         (page_start >= size)) {
         /* page got truncated out from underneath us */
         goto out_unlock;
     }
     wait_on_page_writeback(page);
 
     lock_extent_bits(io_tree, page_start, page_end, &cached_state);
     ret2 = set_page_extent_mapped(page);
     if (ret2 < 0) {
         ret = vmf_error(ret2);
         unlock_extent_cached(io_tree, page_start, page_end, &cached_state);
         goto out_unlock;
     }
 
     /*
      * we can't set the delalloc bits if there are pending ordered
      * extents.  Drop our locks and wait for them to finish
      */
     ordered = btrfs_lookup_ordered_range(BTRFS_I(inode), page_start,
             PAGE_SIZE);
     if (ordered) {
         unlock_extent_cached(io_tree, page_start, page_end,
                      &cached_state);
         unlock_page(page);
         up_read(&BTRFS_I(inode)->i_mmap_lock);
         btrfs_start_ordered_extent(ordered, 1);
         btrfs_put_ordered_extent(ordered);
         goto again;
     }
 
     if (page->index == ((size - 1) >> PAGE_SHIFT)) {
         reserved_space = round_up(size - page_start,
                       fs_info->sectorsize);
         if (reserved_space < PAGE_SIZE) {
             end = page_start + reserved_space - 1;
             btrfs_delalloc_release_space(BTRFS_I(inode),
                     data_reserved, page_start,
                     PAGE_SIZE - reserved_space, true);
         }
     }
 
     /*
      * page_mkwrite gets called when the page is firstly dirtied after it's
      * faulted in, but write(2) could also dirty a page and set delalloc
      * bits, thus in this case for space account reason, we still need to
      * clear any delalloc bits within this page range since we have to
      * reserve data&meta space before lock_page() (see above comments).
      */
     clear_extent_bit(&BTRFS_I(inode)->io_tree, page_start, end,
               EXTENT_DELALLOC | EXTENT_DO_ACCOUNTING |
               EXTENT_DEFRAG, 0, 0, &cached_state);
 
     ret2 = btrfs_set_extent_delalloc(BTRFS_I(inode), page_start, end, 0,
                     &cached_state);
     if (ret2) {
         unlock_extent_cached(io_tree, page_start, page_end,
                      &cached_state);
         ret = VM_FAULT_SIGBUS;
         goto out_unlock;
     }
 
     /* page is wholly or partially inside EOF */
     if (page_start + PAGE_SIZE > size)
         zero_start = offset_in_page(size);
     else
         zero_start = PAGE_SIZE;
 
     if (zero_start != PAGE_SIZE)
         memzero_page(page, zero_start, PAGE_SIZE - zero_start);
 
     btrfs_page_clear_checked(fs_info, page, page_start, PAGE_SIZE);
     btrfs_page_set_dirty(fs_info, page, page_start, end + 1 - page_start);
     btrfs_page_set_uptodate(fs_info, page, page_start, end + 1 - page_start);
 
     btrfs_set_inode_last_sub_trans(BTRFS_I(inode));
 
     unlock_extent_cached(io_tree, page_start, page_end, &cached_state);
     up_read(&BTRFS_I(inode)->i_mmap_lock);
 
     btrfs_delalloc_release_extents(BTRFS_I(inode), PAGE_SIZE);
     sb_end_pagefault(inode->i_sb);
     extent_changeset_free(data_reserved);
     return VM_FAULT_LOCKED;
 
 out_unlock:
     unlock_page(page);
     up_read(&BTRFS_I(inode)->i_mmap_lock);
 out:
     btrfs_delalloc_release_extents(BTRFS_I(inode), PAGE_SIZE);
     btrfs_delalloc_release_space(BTRFS_I(inode), data_reserved, page_start,
                      reserved_space, (ret != 0));
 out_noreserve:
     sb_end_pagefault(inode->i_sb);
     extent_changeset_free(data_reserved);
     return ret;
 }
 
 static int btrfs_truncate(struct inode *inode, bool skip_writeback)
 {
     struct btrfs_truncate_control control = {
         .inode = BTRFS_I(inode),
         .ino = btrfs_ino(BTRFS_I(inode)),
         .min_type = BTRFS_EXTENT_DATA_KEY,
         .clear_extent_range = true,
     };
     struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
     struct btrfs_root *root = BTRFS_I(inode)->root;
     struct btrfs_block_rsv *rsv;
     int ret;
     struct btrfs_trans_handle *trans;
     u64 mask = fs_info->sectorsize - 1;
     u64 min_size = btrfs_calc_metadata_size(fs_info, 1);
 
     if (!skip_writeback) {
         ret = btrfs_wait_ordered_range(inode, inode->i_size & (~mask),
                            (u64)-1);
         if (ret)
             return ret;
     }
 
     /*
      * Yes ladies and gentlemen, this is indeed ugly.  We have a couple of
      * things going on here:
      *
      * 1) We need to reserve space to update our inode.
      *
      * 2) We need to have something to cache all the space that is going to
      * be free'd up by the truncate operation, but also have some slack
      * space reserved in case it uses space during the truncate (thank you
      * very much snapshotting).
      *
      * And we need these to be separate.  The fact is we can use a lot of
      * space doing the truncate, and we have no earthly idea how much space
      * we will use, so we need the truncate reservation to be separate so it
      * doesn't end up using space reserved for updating the inode.  We also
      * need to be able to stop the transaction and start a new one, which
      * means we need to be able to update the inode several times, and we
      * have no idea of knowing how many times that will be, so we can't just
      * reserve 1 item for the entirety of the operation, so that has to be
      * done separately as well.
      *
      * So that leaves us with
      *
      * 1) rsv - for the truncate reservation, which we will steal from the
      * transaction reservation.
      * 2) fs_info->trans_block_rsv - this will have 1 items worth left for
      * updating the inode.
      */
     rsv = btrfs_alloc_block_rsv(fs_info, BTRFS_BLOCK_RSV_TEMP);
     if (!rsv)
         return -ENOMEM;
     rsv->size = min_size;
     rsv->failfast = true;
 
     /*
      * 1 for the truncate slack space
      * 1 for updating the inode.
      */
     trans = btrfs_start_transaction(root, 2);
     if (IS_ERR(trans)) {
         ret = PTR_ERR(trans);
         goto out;
     }
 
     /* Migrate the slack space for the truncate to our reserve */
     ret = btrfs_block_rsv_migrate(&fs_info->trans_block_rsv, rsv,
                       min_size, false);
     BUG_ON(ret);
 
     trans->block_rsv = rsv;
 
     while (1) {
         struct extent_state *cached_state = NULL;
         const u64 new_size = inode->i_size;
         const u64 lock_start = ALIGN_DOWN(new_size, fs_info->sectorsize);
 
         control.new_size = new_size;
         lock_extent_bits(&BTRFS_I(inode)->io_tree, lock_start, (u64)-1,
                  &cached_state);
         /*
          * We want to drop from the next block forward in case this new
          * size is not block aligned since we will be keeping the last
          * block of the extent just the way it is.
          */
         btrfs_drop_extent_cache(BTRFS_I(inode),
                     ALIGN(new_size, fs_info->sectorsize),
                     (u64)-1, 0);
 
         ret = btrfs_truncate_inode_items(trans, root, &control);
 
         inode_sub_bytes(inode, control.sub_bytes);
         btrfs_inode_safe_disk_i_size_write(BTRFS_I(inode), control.last_size);
 
         unlock_extent_cached(&BTRFS_I(inode)->io_tree, lock_start,
                      (u64)-1, &cached_state);
 
         trans->block_rsv = &fs_info->trans_block_rsv;
         if (ret != -ENOSPC && ret != -EAGAIN)
             break;
 
         ret = btrfs_update_inode(trans, root, BTRFS_I(inode));
         if (ret)
             break;
 
         btrfs_end_transaction(trans);
         btrfs_btree_balance_dirty(fs_info);
 
         trans = btrfs_start_transaction(root, 2);
         if (IS_ERR(trans)) {
             ret = PTR_ERR(trans);
             trans = NULL;
             break;
         }
 
         btrfs_block_rsv_release(fs_info, rsv, -1, NULL);
         ret = btrfs_block_rsv_migrate(&fs_info->trans_block_rsv,
                           rsv, min_size, false);
         BUG_ON(ret);    /* shouldn't happen */
         trans->block_rsv = rsv;
     }
 
     /*
      * We can't call btrfs_truncate_block inside a trans handle as we could
      * deadlock with freeze, if we got BTRFS_NEED_TRUNCATE_BLOCK then we
      * know we've truncated everything except the last little bit, and can
      * do btrfs_truncate_block and then update the disk_i_size.
      */
     if (ret == BTRFS_NEED_TRUNCATE_BLOCK) {
         btrfs_end_transaction(trans);
         btrfs_btree_balance_dirty(fs_info);
 
         ret = btrfs_truncate_block(BTRFS_I(inode), inode->i_size, 0, 0);
         if (ret)
             goto out;
         trans = btrfs_start_transaction(root, 1);
         if (IS_ERR(trans)) {
             ret = PTR_ERR(trans);
             goto out;
         }
         btrfs_inode_safe_disk_i_size_write(BTRFS_I(inode), 0);
     }
 
     if (trans) {
         int ret2;
 
         trans->block_rsv = &fs_info->trans_block_rsv;
         ret2 = btrfs_update_inode(trans, root, BTRFS_I(inode));
         if (ret2 && !ret)
             ret = ret2;
 
         ret2 = btrfs_end_transaction(trans);
         if (ret2 && !ret)
             ret = ret2;
         btrfs_btree_balance_dirty(fs_info);
     }
 out:
     btrfs_free_block_rsv(fs_info, rsv);
     /*
      * So if we truncate and then write and fsync we normally would just
      * write the extents that changed, which is a problem if we need to
      * first truncate that entire inode.  So set this flag so we write out
      * all of the extents in the inode to the sync log so we're completely
      * safe.
      *
      * If no extents were dropped or trimmed we don't need to force the next
      * fsync to truncate all the inode's items from the log and re-log them
      * all. This means the truncate operation did not change the file size,
      * or changed it to a smaller size but there was only an implicit hole
      * between the old i_size and the new i_size, and there were no prealloc
      * extents beyond i_size to drop.
      */
     if (control.extents_found > 0)
         btrfs_set_inode_full_sync(BTRFS_I(inode));
 
     return ret;
 }
 
 struct inode *btrfs_new_subvol_inode(struct user_namespace *mnt_userns,
                      struct inode *dir)
 {
     struct inode *inode;
 
     inode = new_inode(dir->i_sb);
     if (inode) {
         /*
          * Subvolumes don't inherit the sgid bit or the parent's gid if
          * the parent's sgid bit is set. This is probably a bug.
          */
         inode_init_owner(mnt_userns, inode, NULL,
                  S_IFDIR | (~current_umask() & S_IRWXUGO));
         inode->i_op = &btrfs_dir_inode_operations;
         inode->i_fop = &btrfs_dir_file_operations;
     }
     return inode;
 }
 
 struct inode *btrfs_alloc_inode(struct super_block *sb)
 {
     struct btrfs_fs_info *fs_info = btrfs_sb(sb);
     struct btrfs_inode *ei;
     struct inode *inode;
 
     ei = alloc_inode_sb(sb, btrfs_inode_cachep, GFP_KERNEL);
     if (!ei)
         return NULL;
 
     ei->root = NULL;
     ei->generation = 0;
     ei->last_trans = 0;
     ei->last_sub_trans = 0;
     ei->logged_trans = 0;
     ei->delalloc_bytes = 0;
     ei->new_delalloc_bytes = 0;
     ei->defrag_bytes = 0;
     ei->disk_i_size = 0;
     ei->flags = 0;
     ei->ro_flags = 0;
     ei->csum_bytes = 0;
     ei->index_cnt = (u64)-1;
     ei->dir_index = 0;
     ei->last_unlink_trans = 0;
     ei->last_reflink_trans = 0;
     ei->last_log_commit = 0;
 
     spin_lock_init(&ei->lock);
     ei->outstanding_extents = 0;
     if (sb->s_magic != BTRFS_TEST_MAGIC)
         btrfs_init_metadata_block_rsv(fs_info, &ei->block_rsv,
                           BTRFS_BLOCK_RSV_DELALLOC);
     ei->runtime_flags = 0;
     ei->prop_compress = BTRFS_COMPRESS_NONE;
     ei->defrag_compress = BTRFS_COMPRESS_NONE;
 
     ei->delayed_node = NULL;
 
     ei->i_otime.tv_sec = 0;
     ei->i_otime.tv_nsec = 0;
 
     inode = &ei->vfs_inode;
     extent_map_tree_init(&ei->extent_tree);
     extent_io_tree_init(fs_info, &ei->io_tree, IO_TREE_INODE_IO, inode);
     extent_io_tree_init(fs_info, &ei->io_failure_tree,
                 IO_TREE_INODE_IO_FAILURE, inode);
     extent_io_tree_init(fs_info, &ei->file_extent_tree,
                 IO_TREE_INODE_FILE_EXTENT, inode);
     ei->io_tree.track_uptodate = true;
     ei->io_failure_tree.track_uptodate = true;
     atomic_set(&ei->sync_writers, 0);
     mutex_init(&ei->log_mutex);
     btrfs_ordered_inode_tree_init(&ei->ordered_tree);
     INIT_LIST_HEAD(&ei->delalloc_inodes);
     INIT_LIST_HEAD(&ei->delayed_iput);
     RB_CLEAR_NODE(&ei->rb_node);
     init_rwsem(&ei->i_mmap_lock);
 
     return inode;
 }
 
 #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
 void btrfs_test_destroy_inode(struct inode *inode)
 {
     btrfs_drop_extent_cache(BTRFS_I(inode), 0, (u64)-1, 0);
     kmem_cache_free(btrfs_inode_cachep, BTRFS_I(inode));
 }
 #endif
 
 void btrfs_free_inode(struct inode *inode)
 {
     kmem_cache_free(btrfs_inode_cachep, BTRFS_I(inode));
 }
 
 void btrfs_destroy_inode(struct inode *vfs_inode)
 {
     struct btrfs_ordered_extent *ordered;
     struct btrfs_inode *inode = BTRFS_I(vfs_inode);
     struct btrfs_root *root = inode->root;
 
     WARN_ON(!hlist_empty(&vfs_inode->i_dentry));
     WARN_ON(vfs_inode->i_data.nrpages);
     WARN_ON(inode->block_rsv.reserved);
     WARN_ON(inode->block_rsv.size);
     WARN_ON(inode->outstanding_extents);
     if (!S_ISDIR(vfs_inode->i_mode)) {
         WARN_ON(inode->delalloc_bytes);
         WARN_ON(inode->new_delalloc_bytes);
     }
     WARN_ON(inode->csum_bytes);
     WARN_ON(inode->defrag_bytes);
 
     /*
      * This can happen where we create an inode, but somebody else also
      * created the same inode and we need to destroy the one we already
      * created.
      */
     if (!root)
         return;
 
     while (1) {
         ordered = btrfs_lookup_first_ordered_extent(inode, (u64)-1);
         if (!ordered)
             break;
         else {
             btrfs_err(root->fs_info,
                   "found ordered extent %llu %llu on inode cleanup",
                   ordered->file_offset, ordered->num_bytes);
             btrfs_remove_ordered_extent(inode, ordered);
             btrfs_put_ordered_extent(ordered);
             btrfs_put_ordered_extent(ordered);
         }
     }
     btrfs_qgroup_check_reserved_leak(inode);
     inode_tree_del(inode);
     btrfs_drop_extent_cache(inode, 0, (u64)-1, 0);
     btrfs_inode_clear_file_extent_range(inode, 0, (u64)-1);
     btrfs_put_root(inode->root);
 }
 
 int btrfs_drop_inode(struct inode *inode)
 {
     struct btrfs_root *root = BTRFS_I(inode)->root;
 
     if (root == NULL)
         return 1;
 
     /* the snap/subvol tree is on deleting */
     if (btrfs_root_refs(&root->root_item) == 0)
         return 1;
     else
         return generic_drop_inode(inode);
 }
 
 static void init_once(void *foo)
 {
     struct btrfs_inode *ei = foo;
 
     inode_init_once(&ei->vfs_inode);
 }
 
 void __cold btrfs_destroy_cachep(void)
 {
     /*
      * Make sure all delayed rcu free inodes are flushed before we
      * destroy cache.
      */
     rcu_barrier();
     bioset_exit(&btrfs_dio_bioset);
     kmem_cache_destroy(btrfs_inode_cachep);
     kmem_cache_destroy(btrfs_trans_handle_cachep);
     kmem_cache_destroy(btrfs_path_cachep);
     kmem_cache_destroy(btrfs_free_space_cachep);
     kmem_cache_destroy(btrfs_free_space_bitmap_cachep);
 }
 
 int __init btrfs_init_cachep(void)
 {
     btrfs_inode_cachep = kmem_cache_create("btrfs_inode",
             sizeof(struct btrfs_inode), 0,
             SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD | SLAB_ACCOUNT,
             init_once);
     if (!btrfs_inode_cachep)
         goto fail;
 
     btrfs_trans_handle_cachep = kmem_cache_create("btrfs_trans_handle",
             sizeof(struct btrfs_trans_handle), 0,
             SLAB_TEMPORARY | SLAB_MEM_SPREAD, NULL);
     if (!btrfs_trans_handle_cachep)
         goto fail;
 
     btrfs_path_cachep = kmem_cache_create("btrfs_path",
             sizeof(struct btrfs_path), 0,
             SLAB_MEM_SPREAD, NULL);
     if (!btrfs_path_cachep)
         goto fail;
 
     btrfs_free_space_cachep = kmem_cache_create("btrfs_free_space",
             sizeof(struct btrfs_free_space), 0,
             SLAB_MEM_SPREAD, NULL);
     if (!btrfs_free_space_cachep)
         goto fail;
 
     btrfs_free_space_bitmap_cachep = kmem_cache_create("btrfs_free_space_bitmap",
                             PAGE_SIZE, PAGE_SIZE,
                             SLAB_MEM_SPREAD, NULL);
     if (!btrfs_free_space_bitmap_cachep)
         goto fail;
 
     if (bioset_init(&btrfs_dio_bioset, BIO_POOL_SIZE,
             offsetof(struct btrfs_dio_private, bio),
             BIOSET_NEED_BVECS))
         goto fail;
 
     return 0;
 fail:
     btrfs_destroy_cachep();
     return -ENOMEM;
 }
 
 static int btrfs_getattr(struct user_namespace *mnt_userns,
              const struct path *path, struct kstat *stat,
              u32 request_mask, unsigned int flags)
 {
     u64 delalloc_bytes;
     u64 inode_bytes;
     struct inode *inode = d_inode(path->dentry);
     u32 blocksize = inode->i_sb->s_blocksize;
     u32 bi_flags = BTRFS_I(inode)->flags;
     u32 bi_ro_flags = BTRFS_I(inode)->ro_flags;
 
     stat->result_mask |= STATX_BTIME;
     stat->btime.tv_sec = BTRFS_I(inode)->i_otime.tv_sec;
     stat->btime.tv_nsec = BTRFS_I(inode)->i_otime.tv_nsec;
     if (bi_flags & BTRFS_INODE_APPEND)
         stat->attributes |= STATX_ATTR_APPEND;
     if (bi_flags & BTRFS_INODE_COMPRESS)
         stat->attributes |= STATX_ATTR_COMPRESSED;
     if (bi_flags & BTRFS_INODE_IMMUTABLE)
         stat->attributes |= STATX_ATTR_IMMUTABLE;
     if (bi_flags & BTRFS_INODE_NODUMP)
         stat->attributes |= STATX_ATTR_NODUMP;
     if (bi_ro_flags & BTRFS_INODE_RO_VERITY)
         stat->attributes |= STATX_ATTR_VERITY;
 
     stat->attributes_mask |= (STATX_ATTR_APPEND |
                   STATX_ATTR_COMPRESSED |
                   STATX_ATTR_IMMUTABLE |
                   STATX_ATTR_NODUMP);
 
     generic_fillattr(mnt_userns, inode, stat);
     stat->dev = BTRFS_I(inode)->root->anon_dev;
 
     spin_lock(&BTRFS_I(inode)->lock);
     delalloc_bytes = BTRFS_I(inode)->new_delalloc_bytes;
     inode_bytes = inode_get_bytes(inode);
     spin_unlock(&BTRFS_I(inode)->lock);
     stat->blocks = (ALIGN(inode_bytes, blocksize) +
             ALIGN(delalloc_bytes, blocksize)) >> 9;
     return 0;
 }
 
 static int btrfs_rename_exchange(struct inode *old_dir,
                   struct dentry *old_dentry,
                   struct inode *new_dir,
                   struct dentry *new_dentry)
 {
     struct btrfs_fs_info *fs_info = btrfs_sb(old_dir->i_sb);
     struct btrfs_trans_handle *trans;
     unsigned int trans_num_items;
     struct btrfs_root *root = BTRFS_I(old_dir)->root;
     struct btrfs_root *dest = BTRFS_I(new_dir)->root;
     struct inode *new_inode = new_dentry->d_inode;
     struct inode *old_inode = old_dentry->d_inode;
     struct timespec64 ctime = current_time(old_inode);
     struct btrfs_rename_ctx old_rename_ctx;
     struct btrfs_rename_ctx new_rename_ctx;
     u64 old_ino = btrfs_ino(BTRFS_I(old_inode));
     u64 new_ino = btrfs_ino(BTRFS_I(new_inode));
     u64 old_idx = 0;
     u64 new_idx = 0;
     int ret;
     int ret2;
     bool need_abort = false;
 
     /*
      * For non-subvolumes allow exchange only within one subvolume, in the
      * same inode namespace. Two subvolumes (represented as directory) can
      * be exchanged as they're a logical link and have a fixed inode number.
      */
     if (root != dest &&
         (old_ino != BTRFS_FIRST_FREE_OBJECTID ||
          new_ino != BTRFS_FIRST_FREE_OBJECTID))
         return -EXDEV;
 
     /* close the race window with snapshot create/destroy ioctl */
     if (old_ino == BTRFS_FIRST_FREE_OBJECTID ||
         new_ino == BTRFS_FIRST_FREE_OBJECTID)
         down_read(&fs_info->subvol_sem);
 
     /*
      * For each inode:
      * 1 to remove old dir item
      * 1 to remove old dir index
      * 1 to add new dir item
      * 1 to add new dir index
      * 1 to update parent inode
      *
      * If the parents are the same, we only need to account for one
      */
     trans_num_items = (old_dir == new_dir ? 9 : 10);
     if (old_ino == BTRFS_FIRST_FREE_OBJECTID) {
         /*
          * 1 to remove old root ref
          * 1 to remove old root backref
          * 1 to add new root ref
          * 1 to add new root backref
          */
         trans_num_items += 4;
     } else {
         /*
          * 1 to update inode item
          * 1 to remove old inode ref
          * 1 to add new inode ref
          */
         trans_num_items += 3;
     }
     if (new_ino == BTRFS_FIRST_FREE_OBJECTID)
         trans_num_items += 4;
     else
         trans_num_items += 3;
     trans = btrfs_start_transaction(root, trans_num_items);
     if (IS_ERR(trans)) {
         ret = PTR_ERR(trans);
         goto out_notrans;
     }
 
     if (dest != root) {
         ret = btrfs_record_root_in_trans(trans, dest);
         if (ret)
             goto out_fail;
     }
 
     /*
      * We need to find a free sequence number both in the source and
      * in the destination directory for the exchange.
      */
     ret = btrfs_set_inode_index(BTRFS_I(new_dir), &old_idx);
     if (ret)
         goto out_fail;
     ret = btrfs_set_inode_index(BTRFS_I(old_dir), &new_idx);
     if (ret)
         goto out_fail;
 
     BTRFS_I(old_inode)->dir_index = 0ULL;
     BTRFS_I(new_inode)->dir_index = 0ULL;
 
     /* Reference for the source. */
     if (old_ino == BTRFS_FIRST_FREE_OBJECTID) {
         /* force full log commit if subvolume involved. */
         btrfs_set_log_full_commit(trans);
     } else {
         ret = btrfs_insert_inode_ref(trans, dest,
                          new_dentry->d_name.name,
                          new_dentry->d_name.len,
                          old_ino,
                          btrfs_ino(BTRFS_I(new_dir)),
                          old_idx);
         if (ret)
             goto out_fail;
         need_abort = true;
     }
 
     /* And now for the dest. */
     if (new_ino == BTRFS_FIRST_FREE_OBJECTID) {
         /* force full log commit if subvolume involved. */
         btrfs_set_log_full_commit(trans);
     } else {
         ret = btrfs_insert_inode_ref(trans, root,
                          old_dentry->d_name.name,
                          old_dentry->d_name.len,
                          new_ino,
                          btrfs_ino(BTRFS_I(old_dir)),
                          new_idx);
         if (ret) {
             if (need_abort)
                 btrfs_abort_transaction(trans, ret);
             goto out_fail;
         }
     }
 
     /* Update inode version and ctime/mtime. */
     inode_inc_iversion(old_dir);
     inode_inc_iversion(new_dir);
     inode_inc_iversion(old_inode);
     inode_inc_iversion(new_inode);
     old_dir->i_mtime = ctime;
     old_dir->i_ctime = ctime;
     new_dir->i_mtime = ctime;
     new_dir->i_ctime = ctime;
     old_inode->i_ctime = ctime;
     new_inode->i_ctime = ctime;
 
     if (old_dentry->d_parent != new_dentry->d_parent) {
         btrfs_record_unlink_dir(trans, BTRFS_I(old_dir),
                 BTRFS_I(old_inode), 1);
         btrfs_record_unlink_dir(trans, BTRFS_I(new_dir),
                 BTRFS_I(new_inode), 1);
     }
 
     /* src is a subvolume */
     if (old_ino == BTRFS_FIRST_FREE_OBJECTID) {
         ret = btrfs_unlink_subvol(trans, old_dir, old_dentry);
     } else { /* src is an inode */
         ret = __btrfs_unlink_inode(trans, BTRFS_I(old_dir),
                        BTRFS_I(old_dentry->d_inode),
                        old_dentry->d_name.name,
                        old_dentry->d_name.len,
                        &old_rename_ctx);
         if (!ret)
             ret = btrfs_update_inode(trans, root, BTRFS_I(old_inode));
     }
     if (ret) {
         btrfs_abort_transaction(trans, ret);
         goto out_fail;
     }
 
     /* dest is a subvolume */
     if (new_ino == BTRFS_FIRST_FREE_OBJECTID) {
         ret = btrfs_unlink_subvol(trans, new_dir, new_dentry);
     } else { /* dest is an inode */
         ret = __btrfs_unlink_inode(trans, BTRFS_I(new_dir),
                        BTRFS_I(new_dentry->d_inode),
                        new_dentry->d_name.name,
                        new_dentry->d_name.len,
                        &new_rename_ctx);
         if (!ret)
             ret = btrfs_update_inode(trans, dest, BTRFS_I(new_inode));
     }
     if (ret) {
         btrfs_abort_transaction(trans, ret);
         goto out_fail;
     }
 
     ret = btrfs_add_link(trans, BTRFS_I(new_dir), BTRFS_I(old_inode),
                  new_dentry->d_name.name,
                  new_dentry->d_name.len, 0, old_idx);
     if (ret) {
         btrfs_abort_transaction(trans, ret);
         goto out_fail;
     }
 
     ret = btrfs_add_link(trans, BTRFS_I(old_dir), BTRFS_I(new_inode),
                  old_dentry->d_name.name,
                  old_dentry->d_name.len, 0, new_idx);
     if (ret) {
         btrfs_abort_transaction(trans, ret);
         goto out_fail;
     }
 
     if (old_inode->i_nlink == 1)
         BTRFS_I(old_inode)->dir_index = old_idx;
     if (new_inode->i_nlink == 1)
         BTRFS_I(new_inode)->dir_index = new_idx;
 
     /*
      * Now pin the logs of the roots. We do it to ensure that no other task
      * can sync the logs while we are in progress with the rename, because
      * that could result in an inconsistency in case any of the inodes that
      * are part of this rename operation were logged before.
      */
     if (old_ino != BTRFS_FIRST_FREE_OBJECTID)
         btrfs_pin_log_trans(root);
     if (new_ino != BTRFS_FIRST_FREE_OBJECTID)
         btrfs_pin_log_trans(dest);
 
     /* Do the log updates for all inodes. */
     if (old_ino != BTRFS_FIRST_FREE_OBJECTID)
         btrfs_log_new_name(trans, old_dentry, BTRFS_I(old_dir),
                    old_rename_ctx.index, new_dentry->d_parent);
     if (new_ino != BTRFS_FIRST_FREE_OBJECTID)
         btrfs_log_new_name(trans, new_dentry, BTRFS_I(new_dir),
                    new_rename_ctx.index, old_dentry->d_parent);
 
     /* Now unpin the logs. */
     if (old_ino != BTRFS_FIRST_FREE_OBJECTID)
         btrfs_end_log_trans(root);
     if (new_ino != BTRFS_FIRST_FREE_OBJECTID)
         btrfs_end_log_trans(dest);
 out_fail:
     ret2 = btrfs_end_transaction(trans);
     ret = ret ? ret : ret2;
 out_notrans:
     if (new_ino == BTRFS_FIRST_FREE_OBJECTID ||
         old_ino == BTRFS_FIRST_FREE_OBJECTID)
         up_read(&fs_info->subvol_sem);
 
     return ret;
 }
 
 static struct inode *new_whiteout_inode(struct user_namespace *mnt_userns,
                     struct inode *dir)
 {
     struct inode *inode;
 
     inode = new_inode(dir->i_sb);
     if (inode) {
         inode_init_owner(mnt_userns, inode, dir,
                  S_IFCHR | WHITEOUT_MODE);
         inode->i_op = &btrfs_special_inode_operations;
         init_special_inode(inode, inode->i_mode, WHITEOUT_DEV);
     }
     return inode;
 }
 
 static int btrfs_rename(struct user_namespace *mnt_userns,
             struct inode *old_dir, struct dentry *old_dentry,
             struct inode *new_dir, struct dentry *new_dentry,
             unsigned int flags)
 {
     struct btrfs_fs_info *fs_info = btrfs_sb(old_dir->i_sb);
     struct btrfs_new_inode_args whiteout_args = {
         .dir = old_dir,
         .dentry = old_dentry,
     };
     struct btrfs_trans_handle *trans;
     unsigned int trans_num_items;
     struct btrfs_root *root = BTRFS_I(old_dir)->root;
     struct btrfs_root *dest = BTRFS_I(new_dir)->root;
     struct inode *new_inode = d_inode(new_dentry);
     struct inode *old_inode = d_inode(old_dentry);
     struct btrfs_rename_ctx rename_ctx;
     u64 index = 0;
     int ret;
     int ret2;
     u64 old_ino = btrfs_ino(BTRFS_I(old_inode));
 
     if (btrfs_ino(BTRFS_I(new_dir)) == BTRFS_EMPTY_SUBVOL_DIR_OBJECTID)
         return -EPERM;
 
     /* we only allow rename subvolume link between subvolumes */
     if (old_ino != BTRFS_FIRST_FREE_OBJECTID && root != dest)
         return -EXDEV;
 
     if (old_ino == BTRFS_EMPTY_SUBVOL_DIR_OBJECTID ||
         (new_inode && btrfs_ino(BTRFS_I(new_inode)) == BTRFS_FIRST_FREE_OBJECTID))
         return -ENOTEMPTY;
 
     if (S_ISDIR(old_inode->i_mode) && new_inode &&
         new_inode->i_size > BTRFS_EMPTY_DIR_SIZE)
         return -ENOTEMPTY;
 
 
     /* check for collisions, even if the  name isn't there */
     ret = btrfs_check_dir_item_collision(dest, new_dir->i_ino,
                  new_dentry->d_name.name,
                  new_dentry->d_name.len);
 
     if (ret) {
         if (ret == -EEXIST) {
             /* we shouldn't get
              * eexist without a new_inode */
             if (WARN_ON(!new_inode)) {
                 return ret;
             }
         } else {
             /* maybe -EOVERFLOW */
             return ret;
         }
     }
     ret = 0;
 
     /*
      * we're using rename to replace one file with another.  Start IO on it
      * now so  we don't add too much work to the end of the transaction
      */
     if (new_inode && S_ISREG(old_inode->i_mode) && new_inode->i_size)
         filemap_flush(old_inode->i_mapping);
 
     if (flags & RENAME_WHITEOUT) {
         whiteout_args.inode = new_whiteout_inode(mnt_userns, old_dir);
         if (!whiteout_args.inode)
             return -ENOMEM;
         ret = btrfs_new_inode_prepare(&whiteout_args, &trans_num_items);
         if (ret)
             goto out_whiteout_inode;
     } else {
         /* 1 to update the old parent inode. */
         trans_num_items = 1;
     }
 
     if (old_ino == BTRFS_FIRST_FREE_OBJECTID) {
         /* Close the race window with snapshot create/destroy ioctl */
         down_read(&fs_info->subvol_sem);
         /*
          * 1 to remove old root ref
          * 1 to remove old root backref
          * 1 to add new root ref
          * 1 to add new root backref
          */
         trans_num_items += 4;
     } else {
         /*
          * 1 to update inode
          * 1 to remove old inode ref
          * 1 to add new inode ref
          */
         trans_num_items += 3;
     }
     /*
      * 1 to remove old dir item
      * 1 to remove old dir index
      * 1 to add new dir item
      * 1 to add new dir index
      */
     trans_num_items += 4;
     /* 1 to update new parent inode if it's not the same as the old parent */
     if (new_dir != old_dir)
         trans_num_items++;
     if (new_inode) {
         /*
          * 1 to update inode
          * 1 to remove inode ref
          * 1 to remove dir item
          * 1 to remove dir index
          * 1 to possibly add orphan item
          */
         trans_num_items += 5;
     }
     trans = btrfs_start_transaction(root, trans_num_items);
     if (IS_ERR(trans)) {
         ret = PTR_ERR(trans);
         goto out_notrans;
     }
 
     if (dest != root) {
         ret = btrfs_record_root_in_trans(trans, dest);
         if (ret)
             goto out_fail;
     }
 
     ret = btrfs_set_inode_index(BTRFS_I(new_dir), &index);
     if (ret)
         goto out_fail;
 
     BTRFS_I(old_inode)->dir_index = 0ULL;
     if (unlikely(old_ino == BTRFS_FIRST_FREE_OBJECTID)) {
         /* force full log commit if subvolume involved. */
         btrfs_set_log_full_commit(trans);
     } else {
         ret = btrfs_insert_inode_ref(trans, dest,
                          new_dentry->d_name.name,
                          new_dentry->d_name.len,
                          old_ino,
                          btrfs_ino(BTRFS_I(new_dir)), index);
         if (ret)
             goto out_fail;
     }
 
     inode_inc_iversion(old_dir);
     inode_inc_iversion(new_dir);
     inode_inc_iversion(old_inode);
     old_dir->i_mtime = current_time(old_dir);
     old_dir->i_ctime = old_dir->i_mtime;
     new_dir->i_mtime = old_dir->i_mtime;
     new_dir->i_ctime = old_dir->i_mtime;
     old_inode->i_ctime = old_dir->i_mtime;
 
     if (old_dentry->d_parent != new_dentry->d_parent)
         btrfs_record_unlink_dir(trans, BTRFS_I(old_dir),
                 BTRFS_I(old_inode), 1);
 
     if (unlikely(old_ino == BTRFS_FIRST_FREE_OBJECTID)) {
         ret = btrfs_unlink_subvol(trans, old_dir, old_dentry);
     } else {
         ret = __btrfs_unlink_inode(trans, BTRFS_I(old_dir),
                     BTRFS_I(d_inode(old_dentry)),
                     old_dentry->d_name.name,
                     old_dentry->d_name.len,
                     &rename_ctx);
         if (!ret)
             ret = btrfs_update_inode(trans, root, BTRFS_I(old_inode));
     }
     if (ret) {
         btrfs_abort_transaction(trans, ret);
         goto out_fail;
     }
 
     if (new_inode) {
         inode_inc_iversion(new_inode);
         new_inode->i_ctime = current_time(new_inode);
         if (unlikely(btrfs_ino(BTRFS_I(new_inode)) ==
                  BTRFS_EMPTY_SUBVOL_DIR_OBJECTID)) {
             ret = btrfs_unlink_subvol(trans, new_dir, new_dentry);
             BUG_ON(new_inode->i_nlink == 0);
         } else {
             ret = btrfs_unlink_inode(trans, BTRFS_I(new_dir),
                          BTRFS_I(d_inode(new_dentry)),
                          new_dentry->d_name.name,
                          new_dentry->d_name.len);
         }
         if (!ret && new_inode->i_nlink == 0)
             ret = btrfs_orphan_add(trans,
                     BTRFS_I(d_inode(new_dentry)));
         if (ret) {
             btrfs_abort_transaction(trans, ret);
             goto out_fail;
         }
     }
 
     ret = btrfs_add_link(trans, BTRFS_I(new_dir), BTRFS_I(old_inode),
                  new_dentry->d_name.name,
                  new_dentry->d_name.len, 0, index);
     if (ret) {
         btrfs_abort_transaction(trans, ret);
         goto out_fail;
     }
 
     if (old_inode->i_nlink == 1)
         BTRFS_I(old_inode)->dir_index = index;
 
     if (old_ino != BTRFS_FIRST_FREE_OBJECTID)
         btrfs_log_new_name(trans, old_dentry, BTRFS_I(old_dir),
                    rename_ctx.index, new_dentry->d_parent);
 
     if (flags & RENAME_WHITEOUT) {
         ret = btrfs_create_new_inode(trans, &whiteout_args);
         if (ret) {
             btrfs_abort_transaction(trans, ret);
             goto out_fail;
         } else {
             unlock_new_inode(whiteout_args.inode);
             iput(whiteout_args.inode);
             whiteout_args.inode = NULL;
         }
     }
 out_fail:
     ret2 = btrfs_end_transaction(trans);
     ret = ret ? ret : ret2;
 out_notrans:
     if (old_ino == BTRFS_FIRST_FREE_OBJECTID)
         up_read(&fs_info->subvol_sem);
     if (flags & RENAME_WHITEOUT)
         btrfs_new_inode_args_destroy(&whiteout_args);
 out_whiteout_inode:
     if (flags & RENAME_WHITEOUT)
         iput(whiteout_args.inode);
     return ret;
 }
 
 static int btrfs_rename2(struct user_namespace *mnt_userns, struct inode *old_dir,
              struct dentry *old_dentry, struct inode *new_dir,
              struct dentry *new_dentry, unsigned int flags)
 {
     int ret;
 
     if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT))
         return -EINVAL;
 
     if (flags & RENAME_EXCHANGE)
         ret = btrfs_rename_exchange(old_dir, old_dentry, new_dir,
                         new_dentry);
     else
         ret = btrfs_rename(mnt_userns, old_dir, old_dentry, new_dir,
                    new_dentry, flags);
 
     btrfs_btree_balance_dirty(BTRFS_I(new_dir)->root->fs_info);
 
     return ret;
 }
 
 struct btrfs_delalloc_work {
     struct inode *inode;
     struct completion completion;
     struct list_head list;
     struct btrfs_work work;
 };
 
 static void btrfs_run_delalloc_work(struct btrfs_work *work)
 {
     struct btrfs_delalloc_work *delalloc_work;
     struct inode *inode;
 
     delalloc_work = container_of(work, struct btrfs_delalloc_work,
                      work);
     inode = delalloc_work->inode;
     filemap_flush(inode->i_mapping);
     if (test_bit(BTRFS_INODE_HAS_ASYNC_EXTENT,
                 &BTRFS_I(inode)->runtime_flags))
         filemap_flush(inode->i_mapping);
 
     iput(inode);
     complete(&delalloc_work->completion);
 }
 
 static struct btrfs_delalloc_work *btrfs_alloc_delalloc_work(struct inode *inode)
 {
     struct btrfs_delalloc_work *work;
 
     work = kmalloc(sizeof(*work), GFP_NOFS);
     if (!work)
         return NULL;
 
     init_completion(&work->completion);
     INIT_LIST_HEAD(&work->list);
     work->inode = inode;
     btrfs_init_work(&work->work, btrfs_run_delalloc_work, NULL, NULL);
 
     return work;
 }
 
 /*
  * some fairly slow code that needs optimization. This walks the list
  * of all the inodes with pending delalloc and forces them to disk.
  */
 static int start_delalloc_inodes(struct btrfs_root *root,
                  struct writeback_control *wbc, bool snapshot,
                  bool in_reclaim_context)
 {
     struct btrfs_inode *binode;
     struct inode *inode;
     struct btrfs_delalloc_work *work, *next;
     struct list_head works;
     struct list_head splice;
     int ret = 0;
     bool full_flush = wbc->nr_to_write == LONG_MAX;
 
     INIT_LIST_HEAD(&works);
     INIT_LIST_HEAD(&splice);
 
     mutex_lock(&root->delalloc_mutex);
     spin_lock(&root->delalloc_lock);
     list_splice_init(&root->delalloc_inodes, &splice);
     while (!list_empty(&splice)) {
         binode = list_entry(splice.next, struct btrfs_inode,
                     delalloc_inodes);
 
         list_move_tail(&binode->delalloc_inodes,
                    &root->delalloc_inodes);
 
         if (in_reclaim_context &&
             test_bit(BTRFS_INODE_NO_DELALLOC_FLUSH, &binode->runtime_flags))
             continue;
 
         inode = igrab(&binode->vfs_inode);
         if (!inode) {
             cond_resched_lock(&root->delalloc_lock);
             continue;
         }
         spin_unlock(&root->delalloc_lock);
 
         if (snapshot)
             set_bit(BTRFS_INODE_SNAPSHOT_FLUSH,
                 &binode->runtime_flags);
         if (full_flush) {
             work = btrfs_alloc_delalloc_work(inode);
             if (!work) {
                 iput(inode);
                 ret = -ENOMEM;
                 goto out;
             }
             list_add_tail(&work->list, &works);
             btrfs_queue_work(root->fs_info->flush_workers,
                      &work->work);
         } else {
             ret = filemap_fdatawrite_wbc(inode->i_mapping, wbc);
             btrfs_add_delayed_iput(inode);
             if (ret || wbc->nr_to_write <= 0)
                 goto out;
         }
         cond_resched();
         spin_lock(&root->delalloc_lock);
     }
     spin_unlock(&root->delalloc_lock);
 
 out:
     list_for_each_entry_safe(work, next, &works, list) {
         list_del_init(&work->list);
         wait_for_completion(&work->completion);
         kfree(work);
     }
 
     if (!list_empty(&splice)) {
         spin_lock(&root->delalloc_lock);
         list_splice_tail(&splice, &root->delalloc_inodes);
         spin_unlock(&root->delalloc_lock);
     }
     mutex_unlock(&root->delalloc_mutex);
     return ret;
 }
 
 int btrfs_start_delalloc_snapshot(struct btrfs_root *root, bool in_reclaim_context)
 {
     struct writeback_control wbc = {
         .nr_to_write = LONG_MAX,
         .sync_mode = WB_SYNC_NONE,
         .range_start = 0,
         .range_end = LLONG_MAX,
     };
     struct btrfs_fs_info *fs_info = root->fs_info;
 
     if (BTRFS_FS_ERROR(fs_info))
         return -EROFS;
 
     return start_delalloc_inodes(root, &wbc, true, in_reclaim_context);
 }
 
 int btrfs_start_delalloc_roots(struct btrfs_fs_info *fs_info, long nr,
                    bool in_reclaim_context)
 {
     struct writeback_control wbc = {
         .nr_to_write = nr,
         .sync_mode = WB_SYNC_NONE,
         .range_start = 0,
         .range_end = LLONG_MAX,
     };
     struct btrfs_root *root;
     struct list_head splice;
     int ret;
 
     if (BTRFS_FS_ERROR(fs_info))
         return -EROFS;
 
     INIT_LIST_HEAD(&splice);
 
     mutex_lock(&fs_info->delalloc_root_mutex);
     spin_lock(&fs_info->delalloc_root_lock);
     list_splice_init(&fs_info->delalloc_roots, &splice);
     while (!list_empty(&splice)) {
         /*
          * Reset nr_to_write here so we know that we're doing a full
          * flush.
          */
         if (nr == LONG_MAX)
             wbc.nr_to_write = LONG_MAX;
 
         root = list_first_entry(&splice, struct btrfs_root,
                     delalloc_root);
         root = btrfs_grab_root(root);
         BUG_ON(!root);
         list_move_tail(&root->delalloc_root,
                    &fs_info->delalloc_roots);
         spin_unlock(&fs_info->delalloc_root_lock);
 
         ret = start_delalloc_inodes(root, &wbc, false, in_reclaim_context);
         btrfs_put_root(root);
         if (ret < 0 || wbc.nr_to_write <= 0)
             goto out;
         spin_lock(&fs_info->delalloc_root_lock);
     }
     spin_unlock(&fs_info->delalloc_root_lock);
 
     ret = 0;
 out:
     if (!list_empty(&splice)) {
         spin_lock(&fs_info->delalloc_root_lock);
         list_splice_tail(&splice, &fs_info->delalloc_roots);
         spin_unlock(&fs_info->delalloc_root_lock);
     }
     mutex_unlock(&fs_info->delalloc_root_mutex);
     return ret;
 }
 
 static int btrfs_symlink(struct user_namespace *mnt_userns, struct inode *dir,
              struct dentry *dentry, const char *symname)
 {
     struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb);
     struct btrfs_trans_handle *trans;
     struct btrfs_root *root = BTRFS_I(dir)->root;
     struct btrfs_path *path;
     struct btrfs_key key;
     struct inode *inode;
     struct btrfs_new_inode_args new_inode_args = {
         .dir = dir,
         .dentry = dentry,
     };
     unsigned int trans_num_items;
     int err;
     int name_len;
     int datasize;
     unsigned long ptr;
     struct btrfs_file_extent_item *ei;
     struct extent_buffer *leaf;
 
     name_len = strlen(symname);
     if (name_len > BTRFS_MAX_INLINE_DATA_SIZE(fs_info))
         return -ENAMETOOLONG;
 
     inode = new_inode(dir->i_sb);
     if (!inode)
         return -ENOMEM;
     inode_init_owner(mnt_userns, inode, dir, S_IFLNK | S_IRWXUGO);
     inode->i_op = &btrfs_symlink_inode_operations;
     inode_nohighmem(inode);
     inode->i_mapping->a_ops = &btrfs_aops;
     btrfs_i_size_write(BTRFS_I(inode), name_len);
     inode_set_bytes(inode, name_len);
 
     new_inode_args.inode = inode;
     err = btrfs_new_inode_prepare(&new_inode_args, &trans_num_items);
     if (err)
         goto out_inode;
     /* 1 additional item for the inline extent */
     trans_num_items++;
 
     trans = btrfs_start_transaction(root, trans_num_items);
     if (IS_ERR(trans)) {
         err = PTR_ERR(trans);
         goto out_new_inode_args;
     }
 
     err = btrfs_create_new_inode(trans, &new_inode_args);
     if (err)
         goto out;
 
     path = btrfs_alloc_path();
     if (!path) {
         err = -ENOMEM;
         btrfs_abort_transaction(trans, err);
         discard_new_inode(inode);
         inode = NULL;
         goto out;
     }
     key.objectid = btrfs_ino(BTRFS_I(inode));
     key.offset = 0;
     key.type = BTRFS_EXTENT_DATA_KEY;
     datasize = btrfs_file_extent_calc_inline_size(name_len);
     err = btrfs_insert_empty_item(trans, root, path, &key,
                       datasize);
     if (err) {
         btrfs_abort_transaction(trans, err);
         btrfs_free_path(path);
         discard_new_inode(inode);
         inode = NULL;
         goto out;
     }
     leaf = path->nodes[0];
     ei = btrfs_item_ptr(leaf, path->slots[0],
                 struct btrfs_file_extent_item);
     btrfs_set_file_extent_generation(leaf, ei, trans->transid);
     btrfs_set_file_extent_type(leaf, ei,
                    BTRFS_FILE_EXTENT_INLINE);
     btrfs_set_file_extent_encryption(leaf, ei, 0);
     btrfs_set_file_extent_compression(leaf, ei, 0);
     btrfs_set_file_extent_other_encoding(leaf, ei, 0);
     btrfs_set_file_extent_ram_bytes(leaf, ei, name_len);
 
     ptr = btrfs_file_extent_inline_start(ei);
     write_extent_buffer(leaf, symname, ptr, name_len);
     btrfs_mark_buffer_dirty(leaf);
     btrfs_free_path(path);
 
     d_instantiate_new(dentry, inode);
     err = 0;
 out:
     btrfs_end_transaction(trans);
     btrfs_btree_balance_dirty(fs_info);
 out_new_inode_args:
     btrfs_new_inode_args_destroy(&new_inode_args);
 out_inode:
     if (err)
         iput(inode);
     return err;
 }
 
 static struct btrfs_trans_handle *insert_prealloc_file_extent(
                        struct btrfs_trans_handle *trans_in,
                        struct btrfs_inode *inode,
                        struct btrfs_key *ins,
                        u64 file_offset)
 {
     struct btrfs_file_extent_item stack_fi;
     struct btrfs_replace_extent_info extent_info;
     struct btrfs_trans_handle *trans = trans_in;
     struct btrfs_path *path;
     u64 start = ins->objectid;
     u64 len = ins->offset;
     int qgroup_released;
     int ret;
 
     memset(&stack_fi, 0, sizeof(stack_fi));
 
     btrfs_set_stack_file_extent_type(&stack_fi, BTRFS_FILE_EXTENT_PREALLOC);
     btrfs_set_stack_file_extent_disk_bytenr(&stack_fi, start);
     btrfs_set_stack_file_extent_disk_num_bytes(&stack_fi, len);
     btrfs_set_stack_file_extent_num_bytes(&stack_fi, len);
     btrfs_set_stack_file_extent_ram_bytes(&stack_fi, len);
     btrfs_set_stack_file_extent_compression(&stack_fi, BTRFS_COMPRESS_NONE);
     /* Encryption and other encoding is reserved and all 0 */
 
     qgroup_released = btrfs_qgroup_release_data(inode, file_offset, len);
     if (qgroup_released < 0)
         return ERR_PTR(qgroup_released);
 
     if (trans) {
         ret = insert_reserved_file_extent(trans, inode,
                           file_offset, &stack_fi,
                           true, qgroup_released);
         if (ret)
             goto free_qgroup;
         return trans;
     }
 
     extent_info.disk_offset = start;
     extent_info.disk_len = len;
     extent_info.data_offset = 0;
     extent_info.data_len = len;
     extent_info.file_offset = file_offset;
     extent_info.extent_buf = (char *)&stack_fi;
     extent_info.is_new_extent = true;
     extent_info.update_times = true;
     extent_info.qgroup_reserved = qgroup_released;
     extent_info.insertions = 0;
 
     path = btrfs_alloc_path();
     if (!path) {
         ret = -ENOMEM;
         goto free_qgroup;
     }
 
     ret = btrfs_replace_file_extents(inode, path, file_offset,
                      file_offset + len - 1, &extent_info,
                      &trans);
     btrfs_free_path(path);
     if (ret)
         goto free_qgroup;
     return trans;
 
 free_qgroup:
     /*
      * We have released qgroup data range at the beginning of the function,
      * and normally qgroup_released bytes will be freed when committing
      * transaction.
      * But if we error out early, we have to free what we have released
      * or we leak qgroup data reservation.
      */
     btrfs_qgroup_free_refroot(inode->root->fs_info,
             inode->root->root_key.objectid, qgroup_released,
             BTRFS_QGROUP_RSV_DATA);
     return ERR_PTR(ret);
 }
 
 static int __btrfs_prealloc_file_range(struct inode *inode, int mode,
                        u64 start, u64 num_bytes, u64 min_size,
                        loff_t actual_len, u64 *alloc_hint,
                        struct btrfs_trans_handle *trans)
 {
     struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
     struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
     struct extent_map *em;
     struct btrfs_root *root = BTRFS_I(inode)->root;
     struct btrfs_key ins;
     u64 cur_offset = start;
     u64 clear_offset = start;
     u64 i_size;
     u64 cur_bytes;
     u64 last_alloc = (u64)-1;
     int ret = 0;
     bool own_trans = true;
     u64 end = start + num_bytes - 1;
 
     if (trans)
         own_trans = false;
     while (num_bytes > 0) {
         cur_bytes = min_t(u64, num_bytes, SZ_256M);
         cur_bytes = max(cur_bytes, min_size);
         /*
          * If we are severely fragmented we could end up with really
          * small allocations, so if the allocator is returning small
          * chunks lets make its job easier by only searching for those
          * sized chunks.
          */
         cur_bytes = min(cur_bytes, last_alloc);
         ret = btrfs_reserve_extent(root, cur_bytes, cur_bytes,
                 min_size, 0, *alloc_hint, &ins, 1, 0);
         if (ret)
             break;
 
         /*
          * We've reserved this space, and thus converted it from
          * ->bytes_may_use to ->bytes_reserved.  Any error that happens
          * from here on out we will only need to clear our reservation
          * for the remaining unreserved area, so advance our
          * clear_offset by our extent size.
          */
         clear_offset += ins.offset;
 
         last_alloc = ins.offset;
         trans = insert_prealloc_file_extent(trans, BTRFS_I(inode),
                             &ins, cur_offset);
         /*
          * Now that we inserted the prealloc extent we can finally
          * decrement the number of reservations in the block group.
          * If we did it before, we could race with relocation and have
          * relocation miss the reserved extent, making it fail later.
          */
         btrfs_dec_block_group_reservations(fs_info, ins.objectid);
         if (IS_ERR(trans)) {
             ret = PTR_ERR(trans);
             btrfs_free_reserved_extent(fs_info, ins.objectid,
                            ins.offset, 0);
             break;
         }
 
         btrfs_drop_extent_cache(BTRFS_I(inode), cur_offset,
                     cur_offset + ins.offset -1, 0);
 
         em = alloc_extent_map();
         if (!em) {
             btrfs_set_inode_full_sync(BTRFS_I(inode));
             goto next;
         }
 
         em->start = cur_offset;
         em->orig_start = cur_offset;
         em->len = ins.offset;
         em->block_start = ins.objectid;
         em->block_len = ins.offset;
         em->orig_block_len = ins.offset;
         em->ram_bytes = ins.offset;
         set_bit(EXTENT_FLAG_PREALLOC, &em->flags);
         em->generation = trans->transid;
 
         while (1) {
             write_lock(&em_tree->lock);
             ret = add_extent_mapping(em_tree, em, 1);
             write_unlock(&em_tree->lock);
             if (ret != -EEXIST)
                 break;
             btrfs_drop_extent_cache(BTRFS_I(inode), cur_offset,
                         cur_offset + ins.offset - 1,
                         0);
         }
         free_extent_map(em);
 next:
         num_bytes -= ins.offset;
         cur_offset += ins.offset;
         *alloc_hint = ins.objectid + ins.offset;
 
         inode_inc_iversion(inode);
         inode->i_ctime = current_time(inode);
         BTRFS_I(inode)->flags |= BTRFS_INODE_PREALLOC;
         if (!(mode & FALLOC_FL_KEEP_SIZE) &&
             (actual_len > inode->i_size) &&
             (cur_offset > inode->i_size)) {
             if (cur_offset > actual_len)
                 i_size = actual_len;
             else
                 i_size = cur_offset;
             i_size_write(inode, i_size);
             btrfs_inode_safe_disk_i_size_write(BTRFS_I(inode), 0);
         }
 
         ret = btrfs_update_inode(trans, root, BTRFS_I(inode));
 
         if (ret) {
             btrfs_abort_transaction(trans, ret);
             if (own_trans)
                 btrfs_end_transaction(trans);
             break;
         }
 
         if (own_trans) {
             btrfs_end_transaction(trans);
             trans = NULL;
         }
     }
     if (clear_offset < end)
         btrfs_free_reserved_data_space(BTRFS_I(inode), NULL, clear_offset,
             end - clear_offset + 1);
     return ret;
 }
 
 int btrfs_prealloc_file_range(struct inode *inode, int mode,
                   u64 start, u64 num_bytes, u64 min_size,
                   loff_t actual_len, u64 *alloc_hint)
 {
     return __btrfs_prealloc_file_range(inode, mode, start, num_bytes,
                        min_size, actual_len, alloc_hint,
                        NULL);
 }
 
 int btrfs_prealloc_file_range_trans(struct inode *inode,
                     struct btrfs_trans_handle *trans, int mode,
                     u64 start, u64 num_bytes, u64 min_size,
                     loff_t actual_len, u64 *alloc_hint)
 {
     return __btrfs_prealloc_file_range(inode, mode, start, num_bytes,
                        min_size, actual_len, alloc_hint, trans);
 }
 
 static int btrfs_permission(struct user_namespace *mnt_userns,
                 struct inode *inode, int mask)
 {
     struct btrfs_root *root = BTRFS_I(inode)->root;
     umode_t mode = inode->i_mode;
 
     if (mask & MAY_WRITE &&
         (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) {
         if (btrfs_root_readonly(root))
             return -EROFS;
         if (BTRFS_I(inode)->flags & BTRFS_INODE_READONLY)
             return -EACCES;
     }
     return generic_permission(mnt_userns, inode, mask);
 }
 
 static int btrfs_tmpfile(struct user_namespace *mnt_userns, struct inode *dir,
              struct dentry *dentry, umode_t mode)
 {
     struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb);
     struct btrfs_trans_handle *trans;
     struct btrfs_root *root = BTRFS_I(dir)->root;
     struct inode *inode;
     struct btrfs_new_inode_args new_inode_args = {
         .dir = dir,
         .dentry = dentry,
         .orphan = true,
     };
     unsigned int trans_num_items;
     int ret;
 
     inode = new_inode(dir->i_sb);
     if (!inode)
         return -ENOMEM;
     inode_init_owner(mnt_userns, inode, dir, mode);
     inode->i_fop = &btrfs_file_operations;
     inode->i_op = &btrfs_file_inode_operations;
     inode->i_mapping->a_ops = &btrfs_aops;
 
     new_inode_args.inode = inode;
     ret = btrfs_new_inode_prepare(&new_inode_args, &trans_num_items);
     if (ret)
         goto out_inode;
 
     trans = btrfs_start_transaction(root, trans_num_items);
     if (IS_ERR(trans)) {
         ret = PTR_ERR(trans);
         goto out_new_inode_args;
     }
 
     ret = btrfs_create_new_inode(trans, &new_inode_args);
 
     /*
      * We set number of links to 0 in btrfs_create_new_inode(), and here we
      * set it to 1 because d_tmpfile() will issue a warning if the count is
      * 0, through:
      *
      *    d_tmpfile() -> inode_dec_link_count() -> drop_nlink()
      */
     set_nlink(inode, 1);
 
     if (!ret) {
         d_tmpfile(dentry, inode);
         unlock_new_inode(inode);
         mark_inode_dirty(inode);
     }
 
     btrfs_end_transaction(trans);
     btrfs_btree_balance_dirty(fs_info);
 out_new_inode_args:
     btrfs_new_inode_args_destroy(&new_inode_args);
 out_inode:
     if (ret)
         iput(inode);
     return ret;
 }
 
 void btrfs_set_range_writeback(struct btrfs_inode *inode, u64 start, u64 end)
 {
     struct btrfs_fs_info *fs_info = inode->root->fs_info;
     unsigned long index = start >> PAGE_SHIFT;
     unsigned long end_index = end >> PAGE_SHIFT;
     struct page *page;
     u32 len;
 
     ASSERT(end + 1 - start <= U32_MAX);
     len = end + 1 - start;
     while (index <= end_index) {
         page = find_get_page(inode->vfs_inode.i_mapping, index);
         ASSERT(page); /* Pages should be in the extent_io_tree */
 
         btrfs_page_set_writeback(fs_info, page, start, len);
         put_page(page);
         index++;
     }
 }
 
 int btrfs_encoded_io_compression_from_extent(struct btrfs_fs_info *fs_info,
                          int compress_type)
 {
     switch (compress_type) {
     case BTRFS_COMPRESS_NONE:
         return BTRFS_ENCODED_IO_COMPRESSION_NONE;
     case BTRFS_COMPRESS_ZLIB:
         return BTRFS_ENCODED_IO_COMPRESSION_ZLIB;
     case BTRFS_COMPRESS_LZO:
         /*
          * The LZO format depends on the sector size. 64K is the maximum
          * sector size that we support.
          */
         if (fs_info->sectorsize < SZ_4K || fs_info->sectorsize > SZ_64K)
             return -EINVAL;
         return BTRFS_ENCODED_IO_COMPRESSION_LZO_4K +
                (fs_info->sectorsize_bits - 12);
     case BTRFS_COMPRESS_ZSTD:
         return BTRFS_ENCODED_IO_COMPRESSION_ZSTD;
     default:
         return -EUCLEAN;
     }
 }
 
 static ssize_t btrfs_encoded_read_inline(
                 struct kiocb *iocb,
                 struct iov_iter *iter, u64 start,
                 u64 lockend,
                 struct extent_state **cached_state,
                 u64 extent_start, size_t count,
                 struct btrfs_ioctl_encoded_io_args *encoded,
                 bool *unlocked)
 {
     struct btrfs_inode *inode = BTRFS_I(file_inode(iocb->ki_filp));
     struct btrfs_root *root = inode->root;
     struct btrfs_fs_info *fs_info = root->fs_info;
     struct extent_io_tree *io_tree = &inode->io_tree;
     struct btrfs_path *path;
     struct extent_buffer *leaf;
     struct btrfs_file_extent_item *item;
     u64 ram_bytes;
     unsigned long ptr;
     void *tmp;
     ssize_t ret;
 
     path = btrfs_alloc_path();
     if (!path) {
         ret = -ENOMEM;
         goto out;
     }
     ret = btrfs_lookup_file_extent(NULL, root, path, btrfs_ino(inode),
                        extent_start, 0);
     if (ret) {
         if (ret > 0) {
             /* The extent item disappeared? */
             ret = -EIO;
         }
         goto out;
     }
     leaf = path->nodes[0];
     item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_file_extent_item);
 
     ram_bytes = btrfs_file_extent_ram_bytes(leaf, item);
     ptr = btrfs_file_extent_inline_start(item);
 
     encoded->len = min_t(u64, extent_start + ram_bytes,
                  inode->vfs_inode.i_size) - iocb->ki_pos;
     ret = btrfs_encoded_io_compression_from_extent(fs_info,
                  btrfs_file_extent_compression(leaf, item));
     if (ret < 0)
         goto out;
     encoded->compression = ret;
     if (encoded->compression) {
         size_t inline_size;
 
         inline_size = btrfs_file_extent_inline_item_len(leaf,
                                 path->slots[0]);
         if (inline_size > count) {
             ret = -ENOBUFS;
             goto out;
         }
         count = inline_size;
         encoded->unencoded_len = ram_bytes;
         encoded->unencoded_offset = iocb->ki_pos - extent_start;
     } else {
         count = min_t(u64, count, encoded->len);
         encoded->len = count;
         encoded->unencoded_len = count;
         ptr += iocb->ki_pos - extent_start;
     }
 
     tmp = kmalloc(count, GFP_NOFS);
     if (!tmp) {
         ret = -ENOMEM;
         goto out;
     }
     read_extent_buffer(leaf, tmp, ptr, count);
     btrfs_release_path(path);
     unlock_extent_cached(io_tree, start, lockend, cached_state);
     btrfs_inode_unlock(&inode->vfs_inode, BTRFS_ILOCK_SHARED);
     *unlocked = true;
 
     ret = copy_to_iter(tmp, count, iter);
     if (ret != count)
         ret = -EFAULT;
     kfree(tmp);
 out:
     btrfs_free_path(path);
     return ret;
 }
 
 struct btrfs_encoded_read_private {
     struct btrfs_inode *inode;
     u64 file_offset;
     wait_queue_head_t wait;
     atomic_t pending;
     blk_status_t status;
     bool skip_csum;
 };
 
 static blk_status_t submit_encoded_read_bio(struct btrfs_inode *inode,
                         struct bio *bio, int mirror_num)
 {
     struct btrfs_encoded_read_private *priv = bio->bi_private;
     struct btrfs_fs_info *fs_info = inode->root->fs_info;
     blk_status_t ret;
 
     if (!priv->skip_csum) {
         ret = btrfs_lookup_bio_sums(&inode->vfs_inode, bio, NULL);
         if (ret)
             return ret;
     }
 
     atomic_inc(&priv->pending);
     btrfs_submit_bio(fs_info, bio, mirror_num);
     return BLK_STS_OK;
 }
 
 static blk_status_t btrfs_encoded_read_verify_csum(struct btrfs_bio *bbio)
 {
     const bool uptodate = (bbio->bio.bi_status == BLK_STS_OK);
     struct btrfs_encoded_read_private *priv = bbio->bio.bi_private;
     struct btrfs_inode *inode = priv->inode;
     struct btrfs_fs_info *fs_info = inode->root->fs_info;
     u32 sectorsize = fs_info->sectorsize;
     struct bio_vec *bvec;
     struct bvec_iter_all iter_all;
     u32 bio_offset = 0;
 
     if (priv->skip_csum || !uptodate)
         return bbio->bio.bi_status;
 
     bio_for_each_segment_all(bvec, &bbio->bio, iter_all) {
         unsigned int i, nr_sectors, pgoff;
 
         nr_sectors = BTRFS_BYTES_TO_BLKS(fs_info, bvec->bv_len);
         pgoff = bvec->bv_offset;
         for (i = 0; i < nr_sectors; i++) {
             ASSERT(pgoff < PAGE_SIZE);
             if (btrfs_check_data_csum(&inode->vfs_inode, bbio, bio_offset,
                         bvec->bv_page, pgoff))
                 return BLK_STS_IOERR;
             bio_offset += sectorsize;
             pgoff += sectorsize;
         }
     }
     return BLK_STS_OK;
 }
 
 static void btrfs_encoded_read_endio(struct bio *bio)
 {
     struct btrfs_encoded_read_private *priv = bio->bi_private;
     struct btrfs_bio *bbio = btrfs_bio(bio);
     blk_status_t status;
 
     status = btrfs_encoded_read_verify_csum(bbio);
     if (status) {
         /*
          * The memory barrier implied by the atomic_dec_return() here
          * pairs with the memory barrier implied by the
          * atomic_dec_return() or io_wait_event() in
          * btrfs_encoded_read_regular_fill_pages() to ensure that this
          * write is observed before the load of status in
          * btrfs_encoded_read_regular_fill_pages().
          */
         WRITE_ONCE(priv->status, status);
     }
     if (!atomic_dec_return(&priv->pending))
         wake_up(&priv->wait);
     btrfs_bio_free_csum(bbio);
     bio_put(bio);
 }
 
 int btrfs_encoded_read_regular_fill_pages(struct btrfs_inode *inode,
                       u64 file_offset, u64 disk_bytenr,
                       u64 disk_io_size, struct page **pages)
 {
     struct btrfs_fs_info *fs_info = inode->root->fs_info;
     struct btrfs_encoded_read_private priv = {
         .inode = inode,
         .file_offset = file_offset,
         .pending = ATOMIC_INIT(1),
         .skip_csum = (inode->flags & BTRFS_INODE_NODATASUM),
     };
     unsigned long i = 0;
     u64 cur = 0;
     int ret;
 
     init_waitqueue_head(&priv.wait);
     /*
      * Submit bios for the extent, splitting due to bio or stripe limits as
      * necessary.
      */
     while (cur < disk_io_size) {
         struct extent_map *em;
         struct btrfs_io_geometry geom;
         struct bio *bio = NULL;
         u64 remaining;
 
         em = btrfs_get_chunk_map(fs_info, disk_bytenr + cur,
                      disk_io_size - cur);
         if (IS_ERR(em)) {
             ret = PTR_ERR(em);
         } else {
             ret = btrfs_get_io_geometry(fs_info, em, BTRFS_MAP_READ,
                             disk_bytenr + cur, &geom);
             free_extent_map(em);
         }
         if (ret) {
             WRITE_ONCE(priv.status, errno_to_blk_status(ret));
             break;
         }
         remaining = min(geom.len, disk_io_size - cur);
         while (bio || remaining) {
             size_t bytes = min_t(u64, remaining, PAGE_SIZE);
 
             if (!bio) {
                 bio = btrfs_bio_alloc(BIO_MAX_VECS);
                 bio->bi_iter.bi_sector =
                     (disk_bytenr + cur) >> SECTOR_SHIFT;
                 bio->bi_end_io = btrfs_encoded_read_endio;
                 bio->bi_private = &priv;
                 bio->bi_opf = REQ_OP_READ;
             }
 
             if (!bytes ||
                 bio_add_page(bio, pages[i], bytes, 0) < bytes) {
                 blk_status_t status;
 
                 status = submit_encoded_read_bio(inode, bio, 0);
                 if (status) {
                     WRITE_ONCE(priv.status, status);
                     bio_put(bio);
                     goto out;
                 }
                 bio = NULL;
                 continue;
             }
 
             i++;
             cur += bytes;
             remaining -= bytes;
         }
     }
 
 out:
     if (atomic_dec_return(&priv.pending))
         io_wait_event(priv.wait, !atomic_read(&priv.pending));
     /* See btrfs_encoded_read_endio() for ordering. */
     return blk_status_to_errno(READ_ONCE(priv.status));
 }
 
 static ssize_t btrfs_encoded_read_regular(struct kiocb *iocb,
                       struct iov_iter *iter,
                       u64 start, u64 lockend,
                       struct extent_state **cached_state,
                       u64 disk_bytenr, u64 disk_io_size,
                       size_t count, bool compressed,
                       bool *unlocked)
 {
     struct btrfs_inode *inode = BTRFS_I(file_inode(iocb->ki_filp));
     struct extent_io_tree *io_tree = &inode->io_tree;
     struct page **pages;
     unsigned long nr_pages, i;
     u64 cur;
     size_t page_offset;
     ssize_t ret;
 
     nr_pages = DIV_ROUND_UP(disk_io_size, PAGE_SIZE);
     pages = kcalloc(nr_pages, sizeof(struct page *), GFP_NOFS);
     if (!pages)
         return -ENOMEM;
     ret = btrfs_alloc_page_array(nr_pages, pages);
     if (ret) {
         ret = -ENOMEM;
         goto out;
         }
 
     ret = btrfs_encoded_read_regular_fill_pages(inode, start, disk_bytenr,
                             disk_io_size, pages);
     if (ret)
         goto out;
 
     unlock_extent_cached(io_tree, start, lockend, cached_state);
     btrfs_inode_unlock(&inode->vfs_inode, BTRFS_ILOCK_SHARED);
     *unlocked = true;
 
     if (compressed) {
         i = 0;
         page_offset = 0;
     } else {
         i = (iocb->ki_pos - start) >> PAGE_SHIFT;
         page_offset = (iocb->ki_pos - start) & (PAGE_SIZE - 1);
     }
     cur = 0;
     while (cur < count) {
         size_t bytes = min_t(size_t, count - cur,
                      PAGE_SIZE - page_offset);
 
         if (copy_page_to_iter(pages[i], page_offset, bytes,
                       iter) != bytes) {
             ret = -EFAULT;
             goto out;
         }
         i++;
         cur += bytes;
         page_offset = 0;
     }
     ret = count;
 out:
     for (i = 0; i < nr_pages; i++) {
         if (pages[i])
             __free_page(pages[i]);
     }
     kfree(pages);
     return ret;
 }
 
 ssize_t btrfs_encoded_read(struct kiocb *iocb, struct iov_iter *iter,
                struct btrfs_ioctl_encoded_io_args *encoded)
 {
     struct btrfs_inode *inode = BTRFS_I(file_inode(iocb->ki_filp));
     struct btrfs_fs_info *fs_info = inode->root->fs_info;
     struct extent_io_tree *io_tree = &inode->io_tree;
     ssize_t ret;
     size_t count = iov_iter_count(iter);
     u64 start, lockend, disk_bytenr, disk_io_size;
     struct extent_state *cached_state = NULL;
     struct extent_map *em;
     bool unlocked = false;
 
     file_accessed(iocb->ki_filp);
 
     btrfs_inode_lock(&inode->vfs_inode, BTRFS_ILOCK_SHARED);
 
     if (iocb->ki_pos >= inode->vfs_inode.i_size) {
         btrfs_inode_unlock(&inode->vfs_inode, BTRFS_ILOCK_SHARED);
         return 0;
     }
     start = ALIGN_DOWN(iocb->ki_pos, fs_info->sectorsize);
     /*
      * We don't know how long the extent containing iocb->ki_pos is, but if
      * it's compressed we know that it won't be longer than this.
      */
     lockend = start + BTRFS_MAX_UNCOMPRESSED - 1;
 
     for (;;) {
         struct btrfs_ordered_extent *ordered;
 
         ret = btrfs_wait_ordered_range(&inode->vfs_inode, start,
                            lockend - start + 1);
         if (ret)
             goto out_unlock_inode;
         lock_extent_bits(io_tree, start, lockend, &cached_state);
         ordered = btrfs_lookup_ordered_range(inode, start,
                              lockend - start + 1);
         if (!ordered)
             break;
         btrfs_put_ordered_extent(ordered);
         unlock_extent_cached(io_tree, start, lockend, &cached_state);
         cond_resched();
     }
 
     em = btrfs_get_extent(inode, NULL, 0, start, lockend - start + 1);
     if (IS_ERR(em)) {
         ret = PTR_ERR(em);
         goto out_unlock_extent;
     }
 
     if (em->block_start == EXTENT_MAP_INLINE) {
         u64 extent_start = em->start;
 
         /*
          * For inline extents we get everything we need out of the
          * extent item.
          */
         free_extent_map(em);
         em = NULL;
         ret = btrfs_encoded_read_inline(iocb, iter, start, lockend,
                         &cached_state, extent_start,
                         count, encoded, &unlocked);
         goto out;
     }
 
     /*
      * We only want to return up to EOF even if the extent extends beyond
      * that.
      */
     encoded->len = min_t(u64, extent_map_end(em),
                  inode->vfs_inode.i_size) - iocb->ki_pos;
     if (em->block_start == EXTENT_MAP_HOLE ||
         test_bit(EXTENT_FLAG_PREALLOC, &em->flags)) {
         disk_bytenr = EXTENT_MAP_HOLE;
         count = min_t(u64, count, encoded->len);
         encoded->len = count;
         encoded->unencoded_len = count;
     } else if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) {
         disk_bytenr = em->block_start;
         /*
          * Bail if the buffer isn't large enough to return the whole
          * compressed extent.
          */
         if (em->block_len > count) {
             ret = -ENOBUFS;
             goto out_em;
         }
         disk_io_size = em->block_len;
         count = em->block_len;
         encoded->unencoded_len = em->ram_bytes;
         encoded->unencoded_offset = iocb->ki_pos - em->orig_start;
         ret = btrfs_encoded_io_compression_from_extent(fs_info,
                                  em->compress_type);
         if (ret < 0)
             goto out_em;
         encoded->compression = ret;
     } else {
         disk_bytenr = em->block_start + (start - em->start);
         if (encoded->len > count)
             encoded->len = count;
         /*
          * Don't read beyond what we locked. This also limits the page
          * allocations that we'll do.
          */
         disk_io_size = min(lockend + 1, iocb->ki_pos + encoded->len) - start;
         count = start + disk_io_size - iocb->ki_pos;
         encoded->len = count;
         encoded->unencoded_len = count;
         disk_io_size = ALIGN(disk_io_size, fs_info->sectorsize);
     }
     free_extent_map(em);
     em = NULL;
 
     if (disk_bytenr == EXTENT_MAP_HOLE) {
         unlock_extent_cached(io_tree, start, lockend, &cached_state);
         btrfs_inode_unlock(&inode->vfs_inode, BTRFS_ILOCK_SHARED);
         unlocked = true;
         ret = iov_iter_zero(count, iter);
         if (ret != count)
             ret = -EFAULT;
     } else {
         ret = btrfs_encoded_read_regular(iocb, iter, start, lockend,
                          &cached_state, disk_bytenr,
                          disk_io_size, count,
                          encoded->compression,
                          &unlocked);
     }
 
 out:
     if (ret >= 0)
         iocb->ki_pos += encoded->len;
 out_em:
     free_extent_map(em);
 out_unlock_extent:
     if (!unlocked)
         unlock_extent_cached(io_tree, start, lockend, &cached_state);
 out_unlock_inode:
     if (!unlocked)
         btrfs_inode_unlock(&inode->vfs_inode, BTRFS_ILOCK_SHARED);
     return ret;
 }
 
 ssize_t btrfs_do_encoded_write(struct kiocb *iocb, struct iov_iter *from,
                    const struct btrfs_ioctl_encoded_io_args *encoded)
 {
     struct btrfs_inode *inode = BTRFS_I(file_inode(iocb->ki_filp));
     struct btrfs_root *root = inode->root;
     struct btrfs_fs_info *fs_info = root->fs_info;
     struct extent_io_tree *io_tree = &inode->io_tree;
     struct extent_changeset *data_reserved = NULL;
     struct extent_state *cached_state = NULL;
     int compression;
     size_t orig_count;
     u64 start, end;
     u64 num_bytes, ram_bytes, disk_num_bytes;
     unsigned long nr_pages, i;
     struct page **pages;
     struct btrfs_key ins;
     bool extent_reserved = false;
     struct extent_map *em;
     ssize_t ret;
 
     switch (encoded->compression) {
     case BTRFS_ENCODED_IO_COMPRESSION_ZLIB:
         compression = BTRFS_COMPRESS_ZLIB;
         break;
     case BTRFS_ENCODED_IO_COMPRESSION_ZSTD:
         compression = BTRFS_COMPRESS_ZSTD;
         break;
     case BTRFS_ENCODED_IO_COMPRESSION_LZO_4K:
     case BTRFS_ENCODED_IO_COMPRESSION_LZO_8K:
     case BTRFS_ENCODED_IO_COMPRESSION_LZO_16K:
     case BTRFS_ENCODED_IO_COMPRESSION_LZO_32K:
     case BTRFS_ENCODED_IO_COMPRESSION_LZO_64K:
         /* The sector size must match for LZO. */
         if (encoded->compression -
             BTRFS_ENCODED_IO_COMPRESSION_LZO_4K + 12 !=
             fs_info->sectorsize_bits)
             return -EINVAL;
         compression = BTRFS_COMPRESS_LZO;
         break;
     default:
         return -EINVAL;
     }
     if (encoded->encryption != BTRFS_ENCODED_IO_ENCRYPTION_NONE)
         return -EINVAL;
 
     orig_count = iov_iter_count(from);
 
     /* The extent size must be sane. */
     if (encoded->unencoded_len > BTRFS_MAX_UNCOMPRESSED ||
         orig_count > BTRFS_MAX_COMPRESSED || orig_count == 0)
         return -EINVAL;
 
     /*
      * The compressed data must be smaller than the decompressed data.
      *
      * It's of course possible for data to compress to larger or the same
      * size, but the buffered I/O path falls back to no compression for such
      * data, and we don't want to break any assumptions by creating these
      * extents.
      *
      * Note that this is less strict than the current check we have that the
      * compressed data must be at least one sector smaller than the
      * decompressed data. We only want to enforce the weaker requirement
      * from old kernels that it is at least one byte smaller.
      */
     if (orig_count >= encoded->unencoded_len)
         return -EINVAL;
 
     /* The extent must start on a sector boundary. */
     start = iocb->ki_pos;
     if (!IS_ALIGNED(start, fs_info->sectorsize))
         return -EINVAL;
 
     /*
      * The extent must end on a sector boundary. However, we allow a write
      * which ends at or extends i_size to have an unaligned length; we round
      * up the extent size and set i_size to the unaligned end.
      */
     if (start + encoded->len < inode->vfs_inode.i_size &&
         !IS_ALIGNED(start + encoded->len, fs_info->sectorsize))
         return -EINVAL;
 
     /* Finally, the offset in the unencoded data must be sector-aligned. */
     if (!IS_ALIGNED(encoded->unencoded_offset, fs_info->sectorsize))
         return -EINVAL;
 
     num_bytes = ALIGN(encoded->len, fs_info->sectorsize);
     ram_bytes = ALIGN(encoded->unencoded_len, fs_info->sectorsize);
     end = start + num_bytes - 1;
 
     /*
      * If the extent cannot be inline, the compressed data on disk must be
      * sector-aligned. For convenience, we extend it with zeroes if it
      * isn't.
      */
     disk_num_bytes = ALIGN(orig_count, fs_info->sectorsize);
     nr_pages = DIV_ROUND_UP(disk_num_bytes, PAGE_SIZE);
     pages = kvcalloc(nr_pages, sizeof(struct page *), GFP_KERNEL_ACCOUNT);
     if (!pages)
         return -ENOMEM;
     for (i = 0; i < nr_pages; i++) {
         size_t bytes = min_t(size_t, PAGE_SIZE, iov_iter_count(from));
         char *kaddr;
 
         pages[i] = alloc_page(GFP_KERNEL_ACCOUNT);
         if (!pages[i]) {
             ret = -ENOMEM;
             goto out_pages;
         }
         kaddr = kmap_local_page(pages[i]);
         if (copy_from_iter(kaddr, bytes, from) != bytes) {
             kunmap_local(kaddr);
             ret = -EFAULT;
             goto out_pages;
         }
         if (bytes < PAGE_SIZE)
             memset(kaddr + bytes, 0, PAGE_SIZE - bytes);
         kunmap_local(kaddr);
     }
 
     for (;;) {
         struct btrfs_ordered_extent *ordered;
 
         ret = btrfs_wait_ordered_range(&inode->vfs_inode, start, num_bytes);
         if (ret)
             goto out_pages;
         ret = invalidate_inode_pages2_range(inode->vfs_inode.i_mapping,
                             start >> PAGE_SHIFT,
                             end >> PAGE_SHIFT);
         if (ret)
             goto out_pages;
         lock_extent_bits(io_tree, start, end, &cached_state);
         ordered = btrfs_lookup_ordered_range(inode, start, num_bytes);
         if (!ordered &&
             !filemap_range_has_page(inode->vfs_inode.i_mapping, start, end))
             break;
         if (ordered)
             btrfs_put_ordered_extent(ordered);
         unlock_extent_cached(io_tree, start, end, &cached_state);
         cond_resched();
     }
 
     /*
      * We don't use the higher-level delalloc space functions because our
      * num_bytes and disk_num_bytes are different.
      */
     ret = btrfs_alloc_data_chunk_ondemand(inode, disk_num_bytes);
     if (ret)
         goto out_unlock;
     ret = btrfs_qgroup_reserve_data(inode, &data_reserved, start, num_bytes);
     if (ret)
         goto out_free_data_space;
     ret = btrfs_delalloc_reserve_metadata(inode, num_bytes, disk_num_bytes,
                           false);
     if (ret)
         goto out_qgroup_free_data;
 
     /* Try an inline extent first. */
     if (start == 0 && encoded->unencoded_len == encoded->len &&
         encoded->unencoded_offset == 0) {
         ret = cow_file_range_inline(inode, encoded->len, orig_count,
                         compression, pages, true);
         if (ret <= 0) {
             if (ret == 0)
                 ret = orig_count;
             goto out_delalloc_release;
         }
     }
 
     ret = btrfs_reserve_extent(root, disk_num_bytes, disk_num_bytes,
                    disk_num_bytes, 0, 0, &ins, 1, 1);
     if (ret)
         goto out_delalloc_release;
     extent_reserved = true;
 
     em = create_io_em(inode, start, num_bytes,
               start - encoded->unencoded_offset, ins.objectid,
               ins.offset, ins.offset, ram_bytes, compression,
               BTRFS_ORDERED_COMPRESSED);
     if (IS_ERR(em)) {
         ret = PTR_ERR(em);
         goto out_free_reserved;
     }
     free_extent_map(em);
 
     ret = btrfs_add_ordered_extent(inode, start, num_bytes, ram_bytes,
                        ins.objectid, ins.offset,
                        encoded->unencoded_offset,
                        (1 << BTRFS_ORDERED_ENCODED) |
                        (1 << BTRFS_ORDERED_COMPRESSED),
                        compression);
     if (ret) {
         btrfs_drop_extent_cache(inode, start, end, 0);
         goto out_free_reserved;
     }
     btrfs_dec_block_group_reservations(fs_info, ins.objectid);
 
     if (start + encoded->len > inode->vfs_inode.i_size)
         i_size_write(&inode->vfs_inode, start + encoded->len);
 
     unlock_extent_cached(io_tree, start, end, &cached_state);
 
     btrfs_delalloc_release_extents(inode, num_bytes);
 
     if (btrfs_submit_compressed_write(inode, start, num_bytes, ins.objectid,
                       ins.offset, pages, nr_pages, 0, NULL,
                       false)) {
         btrfs_writepage_endio_finish_ordered(inode, pages[0], start, end, 0);
         ret = -EIO;
         goto out_pages;
     }
     ret = orig_count;
     goto out;
 
 out_free_reserved:
     btrfs_dec_block_group_reservations(fs_info, ins.objectid);
     btrfs_free_reserved_extent(fs_info, ins.objectid, ins.offset, 1);
 out_delalloc_release:
     btrfs_delalloc_release_extents(inode, num_bytes);
     btrfs_delalloc_release_metadata(inode, disk_num_bytes, ret < 0);
 out_qgroup_free_data:
     if (ret < 0)
         btrfs_qgroup_free_data(inode, data_reserved, start, num_bytes);
 out_free_data_space:
     /*
      * If btrfs_reserve_extent() succeeded, then we already decremented
      * bytes_may_use.
      */
     if (!extent_reserved)
         btrfs_free_reserved_data_space_noquota(fs_info, disk_num_bytes);
 out_unlock:
     unlock_extent_cached(io_tree, start, end, &cached_state);
 out_pages:
     for (i = 0; i < nr_pages; i++) {
         if (pages[i])
             __free_page(pages[i]);
     }
     kvfree(pages);
 out:
     if (ret >= 0)
         iocb->ki_pos += encoded->len;
     return ret;
 }
 
 #ifdef CONFIG_SWAP
 /*
  * Add an entry indicating a block group or device which is pinned by a
  * swapfile. Returns 0 on success, 1 if there is already an entry for it, or a
  * negative errno on failure.
  */
 static int btrfs_add_swapfile_pin(struct inode *inode, void *ptr,
                   bool is_block_group)
 {
     struct btrfs_fs_info *fs_info = BTRFS_I(inode)->root->fs_info;
     struct btrfs_swapfile_pin *sp, *entry;
     struct rb_node **p;
     struct rb_node *parent = NULL;
 
     sp = kmalloc(sizeof(*sp), GFP_NOFS);
     if (!sp)
         return -ENOMEM;
     sp->ptr = ptr;
     sp->inode = inode;
     sp->is_block_group = is_block_group;
     sp->bg_extent_count = 1;
 
     spin_lock(&fs_info->swapfile_pins_lock);
     p = &fs_info->swapfile_pins.rb_node;
     while (*p) {
         parent = *p;
         entry = rb_entry(parent, struct btrfs_swapfile_pin, node);
         if (sp->ptr < entry->ptr ||
             (sp->ptr == entry->ptr && sp->inode < entry->inode)) {
             p = &(*p)->rb_left;
         } else if (sp->ptr > entry->ptr ||
                (sp->ptr == entry->ptr && sp->inode > entry->inode)) {
             p = &(*p)->rb_right;
         } else {
             if (is_block_group)
                 entry->bg_extent_count++;
             spin_unlock(&fs_info->swapfile_pins_lock);
             kfree(sp);
             return 1;
         }
     }
     rb_link_node(&sp->node, parent, p);
     rb_insert_color(&sp->node, &fs_info->swapfile_pins);
     spin_unlock(&fs_info->swapfile_pins_lock);
     return 0;
 }
 
 /* Free all of the entries pinned by this swapfile. */
 static void btrfs_free_swapfile_pins(struct inode *inode)
 {
     struct btrfs_fs_info *fs_info = BTRFS_I(inode)->root->fs_info;
     struct btrfs_swapfile_pin *sp;
     struct rb_node *node, *next;
 
     spin_lock(&fs_info->swapfile_pins_lock);
     node = rb_first(&fs_info->swapfile_pins);
     while (node) {
         next = rb_next(node);
         sp = rb_entry(node, struct btrfs_swapfile_pin, node);
         if (sp->inode == inode) {
             rb_erase(&sp->node, &fs_info->swapfile_pins);
             if (sp->is_block_group) {
                 btrfs_dec_block_group_swap_extents(sp->ptr,
                                sp->bg_extent_count);
                 btrfs_put_block_group(sp->ptr);
             }
             kfree(sp);
         }
         node = next;
     }
     spin_unlock(&fs_info->swapfile_pins_lock);
 }
 
 struct btrfs_swap_info {
     u64 start;
     u64 block_start;
     u64 block_len;
     u64 lowest_ppage;
     u64 highest_ppage;
     unsigned long nr_pages;
     int nr_extents;
 };
 
 static int btrfs_add_swap_extent(struct swap_info_struct *sis,
                  struct btrfs_swap_info *bsi)
 {
     unsigned long nr_pages;
     unsigned long max_pages;
     u64 first_ppage, first_ppage_reported, next_ppage;
     int ret;
 
     /*
      * Our swapfile may have had its size extended after the swap header was
      * written. In that case activating the swapfile should not go beyond
      * the max size set in the swap header.
      */
     if (bsi->nr_pages >= sis->max)
         return 0;
 
     max_pages = sis->max - bsi->nr_pages;
     first_ppage = ALIGN(bsi->block_start, PAGE_SIZE) >> PAGE_SHIFT;
     next_ppage = ALIGN_DOWN(bsi->block_start + bsi->block_len,
                 PAGE_SIZE) >> PAGE_SHIFT;
 
     if (first_ppage >= next_ppage)
         return 0;
     nr_pages = next_ppage - first_ppage;
     nr_pages = min(nr_pages, max_pages);
 
     first_ppage_reported = first_ppage;
     if (bsi->start == 0)
         first_ppage_reported++;
     if (bsi->lowest_ppage > first_ppage_reported)
         bsi->lowest_ppage = first_ppage_reported;
     if (bsi->highest_ppage < (next_ppage - 1))
         bsi->highest_ppage = next_ppage - 1;
 
     ret = add_swap_extent(sis, bsi->nr_pages, nr_pages, first_ppage);
     if (ret < 0)
         return ret;
     bsi->nr_extents += ret;
     bsi->nr_pages += nr_pages;
     return 0;
 }
 
 static void btrfs_swap_deactivate(struct file *file)
 {
     struct inode *inode = file_inode(file);
 
     btrfs_free_swapfile_pins(inode);
     atomic_dec(&BTRFS_I(inode)->root->nr_swapfiles);
 }
 
 static int btrfs_swap_activate(struct swap_info_struct *sis, struct file *file,
                    sector_t *span)
 {
     struct inode *inode = file_inode(file);
     struct btrfs_root *root = BTRFS_I(inode)->root;
     struct btrfs_fs_info *fs_info = root->fs_info;
     struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
     struct extent_state *cached_state = NULL;
     struct extent_map *em = NULL;
     struct btrfs_device *device = NULL;
     struct btrfs_swap_info bsi = {
         .lowest_ppage = (sector_t)-1ULL,
     };
     int ret = 0;
     u64 isize;
     u64 start;
 
     /*
      * If the swap file was just created, make sure delalloc is done. If the
      * file changes again after this, the user is doing something stupid and
      * we don't really care.
      */
     ret = btrfs_wait_ordered_range(inode, 0, (u64)-1);
     if (ret)
         return ret;
 
     /*
      * The inode is locked, so these flags won't change after we check them.
      */
     if (BTRFS_I(inode)->flags & BTRFS_INODE_COMPRESS) {
         btrfs_warn(fs_info, "swapfile must not be compressed");
         return -EINVAL;
     }
     if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATACOW)) {
         btrfs_warn(fs_info, "swapfile must not be copy-on-write");
         return -EINVAL;
     }
     if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) {
         btrfs_warn(fs_info, "swapfile must not be checksummed");
         return -EINVAL;
     }
 
     /*
      * Balance or device remove/replace/resize can move stuff around from
      * under us. The exclop protection makes sure they aren't running/won't
      * run concurrently while we are mapping the swap extents, and
      * fs_info->swapfile_pins prevents them from running while the swap
      * file is active and moving the extents. Note that this also prevents
      * a concurrent device add which isn't actually necessary, but it's not
      * really worth the trouble to allow it.
      */
     if (!btrfs_exclop_start(fs_info, BTRFS_EXCLOP_SWAP_ACTIVATE)) {
         btrfs_warn(fs_info,
        "cannot activate swapfile while exclusive operation is running");
         return -EBUSY;
     }
 
     /*
      * Prevent snapshot creation while we are activating the swap file.
      * We do not want to race with snapshot creation. If snapshot creation
      * already started before we bumped nr_swapfiles from 0 to 1 and
      * completes before the first write into the swap file after it is
      * activated, than that write would fallback to COW.
      */
     if (!btrfs_drew_try_write_lock(&root->snapshot_lock)) {
         btrfs_exclop_finish(fs_info);
         btrfs_warn(fs_info,
        "cannot activate swapfile because snapshot creation is in progress");
         return -EINVAL;
     }
     /*
      * Snapshots can create extents which require COW even if NODATACOW is
      * set. We use this counter to prevent snapshots. We must increment it
      * before walking the extents because we don't want a concurrent
      * snapshot to run after we've already checked the extents.
      *
      * It is possible that subvolume is marked for deletion but still not
      * removed yet. To prevent this race, we check the root status before
      * activating the swapfile.
      */
     spin_lock(&root->root_item_lock);
     if (btrfs_root_dead(root)) {
         spin_unlock(&root->root_item_lock);
 
         btrfs_exclop_finish(fs_info);
         btrfs_warn(fs_info,
         "cannot activate swapfile because subvolume %llu is being deleted",
             root->root_key.objectid);
         return -EPERM;
     }
     atomic_inc(&root->nr_swapfiles);
     spin_unlock(&root->root_item_lock);
 
     isize = ALIGN_DOWN(inode->i_size, fs_info->sectorsize);
 
     lock_extent_bits(io_tree, 0, isize - 1, &cached_state);
     start = 0;
     while (start < isize) {
         u64 logical_block_start, physical_block_start;
         struct btrfs_block_group *bg;
         u64 len = isize - start;
 
         em = btrfs_get_extent(BTRFS_I(inode), NULL, 0, start, len);
         if (IS_ERR(em)) {
             ret = PTR_ERR(em);
             goto out;
         }
 
         if (em->block_start == EXTENT_MAP_HOLE) {
             btrfs_warn(fs_info, "swapfile must not have holes");
             ret = -EINVAL;
             goto out;
         }
         if (em->block_start == EXTENT_MAP_INLINE) {
             /*
              * It's unlikely we'll ever actually find ourselves
              * here, as a file small enough to fit inline won't be
              * big enough to store more than the swap header, but in
              * case something changes in the future, let's catch it
              * here rather than later.
              */
             btrfs_warn(fs_info, "swapfile must not be inline");
             ret = -EINVAL;
             goto out;
         }
         if (test_bit(EXTENT_FLAG_COMPRESSED, &em->flags)) {
             btrfs_warn(fs_info, "swapfile must not be compressed");
             ret = -EINVAL;
             goto out;
         }
 
         logical_block_start = em->block_start + (start - em->start);
         len = min(len, em->len - (start - em->start));
         free_extent_map(em);
         em = NULL;
 
         ret = can_nocow_extent(inode, start, &len, NULL, NULL, NULL, true);
         if (ret < 0) {
             goto out;
         } else if (ret) {
             ret = 0;
         } else {
             btrfs_warn(fs_info,
                    "swapfile must not be copy-on-write");
             ret = -EINVAL;
             goto out;
         }
 
         em = btrfs_get_chunk_map(fs_info, logical_block_start, len);
         if (IS_ERR(em)) {
             ret = PTR_ERR(em);
             goto out;
         }
 
         if (em->map_lookup->type & BTRFS_BLOCK_GROUP_PROFILE_MASK) {
             btrfs_warn(fs_info,
                    "swapfile must have single data profile");
             ret = -EINVAL;
             goto out;
         }
 
         if (device == NULL) {
             device = em->map_lookup->stripes[0].dev;
             ret = btrfs_add_swapfile_pin(inode, device, false);
             if (ret == 1)
                 ret = 0;
             else if (ret)
                 goto out;
         } else if (device != em->map_lookup->stripes[0].dev) {
             btrfs_warn(fs_info, "swapfile must be on one device");
             ret = -EINVAL;
             goto out;
         }
 
         physical_block_start = (em->map_lookup->stripes[0].physical +
                     (logical_block_start - em->start));
         len = min(len, em->len - (logical_block_start - em->start));
         free_extent_map(em);
         em = NULL;
 
         bg = btrfs_lookup_block_group(fs_info, logical_block_start);
         if (!bg) {
             btrfs_warn(fs_info,
                "could not find block group containing swapfile");
             ret = -EINVAL;
             goto out;
         }
 
         if (!btrfs_inc_block_group_swap_extents(bg)) {
             btrfs_warn(fs_info,
                "block group for swapfile at %llu is read-only%s",
                bg->start,
                atomic_read(&fs_info->scrubs_running) ?
                        " (scrub running)" : "");
             btrfs_put_block_group(bg);
             ret = -EINVAL;
             goto out;
         }
 
         ret = btrfs_add_swapfile_pin(inode, bg, true);
         if (ret) {
             btrfs_put_block_group(bg);
             if (ret == 1)
                 ret = 0;
             else
                 goto out;
         }
 
         if (bsi.block_len &&
             bsi.block_start + bsi.block_len == physical_block_start) {
             bsi.block_len += len;
         } else {
             if (bsi.block_len) {
                 ret = btrfs_add_swap_extent(sis, &bsi);
                 if (ret)
                     goto out;
             }
             bsi.start = start;
             bsi.block_start = physical_block_start;
             bsi.block_len = len;
         }
 
         start += len;
     }
 
     if (bsi.block_len)
         ret = btrfs_add_swap_extent(sis, &bsi);
 
 out:
     if (!IS_ERR_OR_NULL(em))
         free_extent_map(em);
 
     unlock_extent_cached(io_tree, 0, isize - 1, &cached_state);
 
     if (ret)
         btrfs_swap_deactivate(file);
 
     btrfs_drew_write_unlock(&root->snapshot_lock);
 
     btrfs_exclop_finish(fs_info);
 
     if (ret)
         return ret;
 
     if (device)
         sis->bdev = device->bdev;
     *span = bsi.highest_ppage - bsi.lowest_ppage + 1;
     sis->max = bsi.nr_pages;
     sis->pages = bsi.nr_pages - 1;
     sis->highest_bit = bsi.nr_pages - 1;
     return bsi.nr_extents;
 }
 #else
 static void btrfs_swap_deactivate(struct file *file)
 {
 }
 
 static int btrfs_swap_activate(struct swap_info_struct *sis, struct file *file,
                    sector_t *span)
 {
     return -EOPNOTSUPP;
 }
 #endif
 
 /*
  * Update the number of bytes used in the VFS' inode. When we replace extents in
  * a range (clone, dedupe, fallocate's zero range), we must update the number of
  * bytes used by the inode in an atomic manner, so that concurrent stat(2) calls
  * always get a correct value.
  */
 void btrfs_update_inode_bytes(struct btrfs_inode *inode,
                   const u64 add_bytes,
                   const u64 del_bytes)
 {
     if (add_bytes == del_bytes)
         return;
 
     spin_lock(&inode->lock);
     if (del_bytes > 0)
         inode_sub_bytes(&inode->vfs_inode, del_bytes);
     if (add_bytes > 0)
         inode_add_bytes(&inode->vfs_inode, add_bytes);
     spin_unlock(&inode->lock);
 }
 
 /**
  * Verify that there are no ordered extents for a given file range.
  *
  * @inode:   The target inode.
  * @start:   Start offset of the file range, should be sector size aligned.
  * @end:     End offset (inclusive) of the file range, its value +1 should be
  *           sector size aligned.
  *
  * This should typically be used for cases where we locked an inode's VFS lock in
  * exclusive mode, we have also locked the inode's i_mmap_lock in exclusive mode,
  * we have flushed all delalloc in the range, we have waited for all ordered
  * extents in the range to complete and finally we have locked the file range in
  * the inode's io_tree.
  */
 void btrfs_assert_inode_range_clean(struct btrfs_inode *inode, u64 start, u64 end)
 {
     struct btrfs_root *root = inode->root;
     struct btrfs_ordered_extent *ordered;
 
     if (!IS_ENABLED(CONFIG_BTRFS_ASSERT))
         return;
 
     ordered = btrfs_lookup_first_ordered_range(inode, start, end + 1 - start);
     if (ordered) {
         btrfs_err(root->fs_info,
 "found unexpected ordered extent in file range [%llu, %llu] for inode %llu root %llu (ordered range [%llu, %llu])",
               start, end, btrfs_ino(inode), root->root_key.objectid,
               ordered->file_offset,
               ordered->file_offset + ordered->num_bytes - 1);
         btrfs_put_ordered_extent(ordered);
     }
 
     ASSERT(ordered == NULL);
 }
 
 static const struct inode_operations btrfs_dir_inode_operations = {
     .getattr    = btrfs_getattr,
     .lookup     = btrfs_lookup,
     .create     = btrfs_create,
     .unlink     = btrfs_unlink,
     .link       = btrfs_link,
     .mkdir      = btrfs_mkdir,
     .rmdir      = btrfs_rmdir,
     .rename     = btrfs_rename2,
     .symlink    = btrfs_symlink,
     .setattr    = btrfs_setattr,
     .mknod      = btrfs_mknod,
     .listxattr  = btrfs_listxattr,
     .permission = btrfs_permission,
     .get_acl    = btrfs_get_acl,
     .set_acl    = btrfs_set_acl,
     .update_time    = btrfs_update_time,
     .tmpfile        = btrfs_tmpfile,
     .fileattr_get   = btrfs_fileattr_get,
     .fileattr_set   = btrfs_fileattr_set,
 };
 
 static const struct file_operations btrfs_dir_file_operations = {
     .llseek     = generic_file_llseek,
     .read       = generic_read_dir,
     .iterate_shared = btrfs_real_readdir,
     .open       = btrfs_opendir,
     .unlocked_ioctl = btrfs_ioctl,
 #ifdef CONFIG_COMPAT
     .compat_ioctl   = btrfs_compat_ioctl,
 #endif
     .release        = btrfs_release_file,
     .fsync      = btrfs_sync_file,
 };
 
 /*
  * btrfs doesn't support the bmap operation because swapfiles
  * use bmap to make a mapping of extents in the file.  They assume
  * these extents won't change over the life of the file and they
  * use the bmap result to do IO directly to the drive.
  *
  * the btrfs bmap call would return logical addresses that aren't
  * suitable for IO and they also will change frequently as COW
  * operations happen.  So, swapfile + btrfs == corruption.
  *
  * For now we're avoiding this by dropping bmap.
  */
 static const struct address_space_operations btrfs_aops = {
     .read_folio = btrfs_read_folio,
     .writepages = btrfs_writepages,
     .readahead  = btrfs_readahead,
     .direct_IO  = noop_direct_IO,
     .invalidate_folio = btrfs_invalidate_folio,
     .release_folio  = btrfs_release_folio,
     .migrate_folio  = btrfs_migrate_folio,
     .dirty_folio    = filemap_dirty_folio,
     .error_remove_page = generic_error_remove_page,
     .swap_activate  = btrfs_swap_activate,
     .swap_deactivate = btrfs_swap_deactivate,
 };
 
 static const struct inode_operations btrfs_file_inode_operations = {
     .getattr    = btrfs_getattr,
     .setattr    = btrfs_setattr,
     .listxattr      = btrfs_listxattr,
     .permission = btrfs_permission,
     .fiemap     = btrfs_fiemap,
     .get_acl    = btrfs_get_acl,
     .set_acl    = btrfs_set_acl,
     .update_time    = btrfs_update_time,
     .fileattr_get   = btrfs_fileattr_get,
     .fileattr_set   = btrfs_fileattr_set,
 };
 static const struct inode_operations btrfs_special_inode_operations = {
     .getattr    = btrfs_getattr,
     .setattr    = btrfs_setattr,
     .permission = btrfs_permission,
     .listxattr  = btrfs_listxattr,
     .get_acl    = btrfs_get_acl,
     .set_acl    = btrfs_set_acl,
     .update_time    = btrfs_update_time,
 };
 static const struct inode_operations btrfs_symlink_inode_operations = {
     .get_link   = page_get_link,
     .getattr    = btrfs_getattr,
     .setattr    = btrfs_setattr,
     .permission = btrfs_permission,
     .listxattr  = btrfs_listxattr,
     .update_time    = btrfs_update_time,
 };
 
 const struct dentry_operations btrfs_dentry_operations = {
     .d_delete   = btrfs_dentry_delete,
 };