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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
 /*
  *  linux/fs/ext4/inode.c
  *
  * Copyright (C) 1992, 1993, 1994, 1995
  * Remy Card (card@masi.ibp.fr)
  * Laboratoire MASI - Institut Blaise Pascal
  * Universite Pierre et Marie Curie (Paris VI)
  *
  *  from
  *
  *  linux/fs/minix/inode.c
  *
  *  Copyright (C) 1991, 1992  Linus Torvalds
  *
  *  64-bit file support on 64-bit platforms by Jakub Jelinek
  *  (jj@sunsite.ms.mff.cuni.cz)
  *
  *  Assorted race fixes, rewrite of ext4_get_block() by Al Viro, 2000
  */
 
 #include <linux/fs.h>
 #include <linux/mount.h>
 #include <linux/time.h>
 #include <linux/highuid.h>
 #include <linux/pagemap.h>
 #include <linux/dax.h>
 #include <linux/quotaops.h>
 #include <linux/string.h>
 #include <linux/buffer_head.h>
 #include <linux/writeback.h>
 #include <linux/pagevec.h>
 #include <linux/mpage.h>
 #include <linux/namei.h>
 #include <linux/uio.h>
 #include <linux/bio.h>
 #include <linux/workqueue.h>
 #include <linux/kernel.h>
 #include <linux/printk.h>
 #include <linux/slab.h>
 #include <linux/bitops.h>
 #include <linux/iomap.h>
 #include <linux/iversion.h>
 
 #include "ext4_jbd2.h"
 #include "xattr.h"
 #include "acl.h"
 #include "truncate.h"
 
 #include <trace/events/ext4.h>
 
 static __u32 ext4_inode_csum(struct inode *inode, struct ext4_inode *raw,
                   struct ext4_inode_info *ei)
 {
     struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
     __u32 csum;
     __u16 dummy_csum = 0;
     int offset = offsetof(struct ext4_inode, i_checksum_lo);
     unsigned int csum_size = sizeof(dummy_csum);
 
     csum = ext4_chksum(sbi, ei->i_csum_seed, (__u8 *)raw, offset);
     csum = ext4_chksum(sbi, csum, (__u8 *)&dummy_csum, csum_size);
     offset += csum_size;
     csum = ext4_chksum(sbi, csum, (__u8 *)raw + offset,
                EXT4_GOOD_OLD_INODE_SIZE - offset);
 
     if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
         offset = offsetof(struct ext4_inode, i_checksum_hi);
         csum = ext4_chksum(sbi, csum, (__u8 *)raw +
                    EXT4_GOOD_OLD_INODE_SIZE,
                    offset - EXT4_GOOD_OLD_INODE_SIZE);
         if (EXT4_FITS_IN_INODE(raw, ei, i_checksum_hi)) {
             csum = ext4_chksum(sbi, csum, (__u8 *)&dummy_csum,
                        csum_size);
             offset += csum_size;
         }
         csum = ext4_chksum(sbi, csum, (__u8 *)raw + offset,
                    EXT4_INODE_SIZE(inode->i_sb) - offset);
     }
 
     return csum;
 }
 
 static int ext4_inode_csum_verify(struct inode *inode, struct ext4_inode *raw,
                   struct ext4_inode_info *ei)
 {
     __u32 provided, calculated;
 
     if (EXT4_SB(inode->i_sb)->s_es->s_creator_os !=
         cpu_to_le32(EXT4_OS_LINUX) ||
         !ext4_has_metadata_csum(inode->i_sb))
         return 1;
 
     provided = le16_to_cpu(raw->i_checksum_lo);
     calculated = ext4_inode_csum(inode, raw, ei);
     if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE &&
         EXT4_FITS_IN_INODE(raw, ei, i_checksum_hi))
         provided |= ((__u32)le16_to_cpu(raw->i_checksum_hi)) << 16;
     else
         calculated &= 0xFFFF;
 
     return provided == calculated;
 }
 
 void ext4_inode_csum_set(struct inode *inode, struct ext4_inode *raw,
              struct ext4_inode_info *ei)
 {
     __u32 csum;
 
     if (EXT4_SB(inode->i_sb)->s_es->s_creator_os !=
         cpu_to_le32(EXT4_OS_LINUX) ||
         !ext4_has_metadata_csum(inode->i_sb))
         return;
 
     csum = ext4_inode_csum(inode, raw, ei);
     raw->i_checksum_lo = cpu_to_le16(csum & 0xFFFF);
     if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE &&
         EXT4_FITS_IN_INODE(raw, ei, i_checksum_hi))
         raw->i_checksum_hi = cpu_to_le16(csum >> 16);
 }
 
 static inline int ext4_begin_ordered_truncate(struct inode *inode,
                           loff_t new_size)
 {
     trace_ext4_begin_ordered_truncate(inode, new_size);
     /*
      * If jinode is zero, then we never opened the file for
      * writing, so there's no need to call
      * jbd2_journal_begin_ordered_truncate() since there's no
      * outstanding writes we need to flush.
      */
     if (!EXT4_I(inode)->jinode)
         return 0;
     return jbd2_journal_begin_ordered_truncate(EXT4_JOURNAL(inode),
                            EXT4_I(inode)->jinode,
                            new_size);
 }
 
 static int __ext4_journalled_writepage(struct page *page, unsigned int len);
 static int ext4_meta_trans_blocks(struct inode *inode, int lblocks,
                   int pextents);
 
 /*
  * Test whether an inode is a fast symlink.
  * A fast symlink has its symlink data stored in ext4_inode_info->i_data.
  */
 int ext4_inode_is_fast_symlink(struct inode *inode)
 {
     if (!(EXT4_I(inode)->i_flags & EXT4_EA_INODE_FL)) {
         int ea_blocks = EXT4_I(inode)->i_file_acl ?
                 EXT4_CLUSTER_SIZE(inode->i_sb) >> 9 : 0;
 
         if (ext4_has_inline_data(inode))
             return 0;
 
         return (S_ISLNK(inode->i_mode) && inode->i_blocks - ea_blocks == 0);
     }
     return S_ISLNK(inode->i_mode) && inode->i_size &&
            (inode->i_size < EXT4_N_BLOCKS * 4);
 }
 
 /*
  * Called at the last iput() if i_nlink is zero.
  */
 void ext4_evict_inode(struct inode *inode)
 {
     handle_t *handle;
     int err;
     /*
      * Credits for final inode cleanup and freeing:
      * sb + inode (ext4_orphan_del()), block bitmap, group descriptor
      * (xattr block freeing), bitmap, group descriptor (inode freeing)
      */
     int extra_credits = 6;
     struct ext4_xattr_inode_array *ea_inode_array = NULL;
     bool freeze_protected = false;
 
     trace_ext4_evict_inode(inode);
 
     if (EXT4_I(inode)->i_flags & EXT4_EA_INODE_FL)
         ext4_evict_ea_inode(inode);
     if (inode->i_nlink) {
         /*
          * When journalling data dirty buffers are tracked only in the
          * journal. So although mm thinks everything is clean and
          * ready for reaping the inode might still have some pages to
          * write in the running transaction or waiting to be
          * checkpointed. Thus calling jbd2_journal_invalidate_folio()
          * (via truncate_inode_pages()) to discard these buffers can
          * cause data loss. Also even if we did not discard these
          * buffers, we would have no way to find them after the inode
          * is reaped and thus user could see stale data if he tries to
          * read them before the transaction is checkpointed. So be
          * careful and force everything to disk here... We use
          * ei->i_datasync_tid to store the newest transaction
          * containing inode's data.
          *
          * Note that directories do not have this problem because they
          * don't use page cache.
          */
         if (inode->i_ino != EXT4_JOURNAL_INO &&
             ext4_should_journal_data(inode) &&
             S_ISREG(inode->i_mode) && inode->i_data.nrpages) {
             journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;
             tid_t commit_tid = EXT4_I(inode)->i_datasync_tid;
 
             jbd2_complete_transaction(journal, commit_tid);
             filemap_write_and_wait(&inode->i_data);
         }
         truncate_inode_pages_final(&inode->i_data);
 
         goto no_delete;
     }
 
     if (is_bad_inode(inode))
         goto no_delete;
     dquot_initialize(inode);
 
     if (ext4_should_order_data(inode))
         ext4_begin_ordered_truncate(inode, 0);
     truncate_inode_pages_final(&inode->i_data);
 
     /*
      * For inodes with journalled data, transaction commit could have
      * dirtied the inode. Flush worker is ignoring it because of I_FREEING
      * flag but we still need to remove the inode from the writeback lists.
      */
     if (!list_empty_careful(&inode->i_io_list)) {
         WARN_ON_ONCE(!ext4_should_journal_data(inode));
         inode_io_list_del(inode);
     }
 
     /*
      * Protect us against freezing - iput() caller didn't have to have any
      * protection against it. When we are in a running transaction though,
      * we are already protected against freezing and we cannot grab further
      * protection due to lock ordering constraints.
      */
     if (!ext4_journal_current_handle()) {
         sb_start_intwrite(inode->i_sb);
         freeze_protected = true;
     }
 
     if (!IS_NOQUOTA(inode))
         extra_credits += EXT4_MAXQUOTAS_DEL_BLOCKS(inode->i_sb);
 
     /*
      * Block bitmap, group descriptor, and inode are accounted in both
      * ext4_blocks_for_truncate() and extra_credits. So subtract 3.
      */
     handle = ext4_journal_start(inode, EXT4_HT_TRUNCATE,
              ext4_blocks_for_truncate(inode) + extra_credits - 3);
     if (IS_ERR(handle)) {
         ext4_std_error(inode->i_sb, PTR_ERR(handle));
         /*
          * If we're going to skip the normal cleanup, we still need to
          * make sure that the in-core orphan linked list is properly
          * cleaned up.
          */
         ext4_orphan_del(NULL, inode);
         if (freeze_protected)
             sb_end_intwrite(inode->i_sb);
         goto no_delete;
     }
 
     if (IS_SYNC(inode))
         ext4_handle_sync(handle);
 
     /*
      * Set inode->i_size to 0 before calling ext4_truncate(). We need
      * special handling of symlinks here because i_size is used to
      * determine whether ext4_inode_info->i_data contains symlink data or
      * block mappings. Setting i_size to 0 will remove its fast symlink
      * status. Erase i_data so that it becomes a valid empty block map.
      */
     if (ext4_inode_is_fast_symlink(inode))
         memset(EXT4_I(inode)->i_data, 0, sizeof(EXT4_I(inode)->i_data));
     inode->i_size = 0;
     err = ext4_mark_inode_dirty(handle, inode);
     if (err) {
         ext4_warning(inode->i_sb,
                  "couldn't mark inode dirty (err %d)", err);
         goto stop_handle;
     }
     if (inode->i_blocks) {
         err = ext4_truncate(inode);
         if (err) {
             ext4_error_err(inode->i_sb, -err,
                        "couldn't truncate inode %lu (err %d)",
                        inode->i_ino, err);
             goto stop_handle;
         }
     }
 
     /* Remove xattr references. */
     err = ext4_xattr_delete_inode(handle, inode, &ea_inode_array,
                       extra_credits);
     if (err) {
         ext4_warning(inode->i_sb, "xattr delete (err %d)", err);
 stop_handle:
         ext4_journal_stop(handle);
         ext4_orphan_del(NULL, inode);
         if (freeze_protected)
             sb_end_intwrite(inode->i_sb);
         ext4_xattr_inode_array_free(ea_inode_array);
         goto no_delete;
     }
 
     /*
      * Kill off the orphan record which ext4_truncate created.
      * AKPM: I think this can be inside the above `if'.
      * Note that ext4_orphan_del() has to be able to cope with the
      * deletion of a non-existent orphan - this is because we don't
      * know if ext4_truncate() actually created an orphan record.
      * (Well, we could do this if we need to, but heck - it works)
      */
     ext4_orphan_del(handle, inode);
     EXT4_I(inode)->i_dtime  = (__u32)ktime_get_real_seconds();
 
     /*
      * One subtle ordering requirement: if anything has gone wrong
      * (transaction abort, IO errors, whatever), then we can still
      * do these next steps (the fs will already have been marked as
      * having errors), but we can't free the inode if the mark_dirty
      * fails.
      */
     if (ext4_mark_inode_dirty(handle, inode))
         /* If that failed, just do the required in-core inode clear. */
         ext4_clear_inode(inode);
     else
         ext4_free_inode(handle, inode);
     ext4_journal_stop(handle);
     if (freeze_protected)
         sb_end_intwrite(inode->i_sb);
     ext4_xattr_inode_array_free(ea_inode_array);
     return;
 no_delete:
     if (!list_empty(&EXT4_I(inode)->i_fc_list))
         ext4_fc_mark_ineligible(inode->i_sb, EXT4_FC_REASON_NOMEM, NULL);
     ext4_clear_inode(inode);    /* We must guarantee clearing of inode... */
 }
 
 #ifdef CONFIG_QUOTA
 qsize_t *ext4_get_reserved_space(struct inode *inode)
 {
     return &EXT4_I(inode)->i_reserved_quota;
 }
 #endif
 
 /*
  * Called with i_data_sem down, which is important since we can call
  * ext4_discard_preallocations() from here.
  */
 void ext4_da_update_reserve_space(struct inode *inode,
                     int used, int quota_claim)
 {
     struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
     struct ext4_inode_info *ei = EXT4_I(inode);
 
     spin_lock(&ei->i_block_reservation_lock);
     trace_ext4_da_update_reserve_space(inode, used, quota_claim);
     if (unlikely(used > ei->i_reserved_data_blocks)) {
         ext4_warning(inode->i_sb, "%s: ino %lu, used %d "
              "with only %d reserved data blocks",
              __func__, inode->i_ino, used,
              ei->i_reserved_data_blocks);
         WARN_ON(1);
         used = ei->i_reserved_data_blocks;
     }
 
     /* Update per-inode reservations */
     ei->i_reserved_data_blocks -= used;
     percpu_counter_sub(&sbi->s_dirtyclusters_counter, used);
 
     spin_unlock(&ei->i_block_reservation_lock);
 
     /* Update quota subsystem for data blocks */
     if (quota_claim)
         dquot_claim_block(inode, EXT4_C2B(sbi, used));
     else {
         /*
          * We did fallocate with an offset that is already delayed
          * allocated. So on delayed allocated writeback we should
          * not re-claim the quota for fallocated blocks.
          */
         dquot_release_reservation_block(inode, EXT4_C2B(sbi, used));
     }
 
     /*
      * If we have done all the pending block allocations and if
      * there aren't any writers on the inode, we can discard the
      * inode's preallocations.
      */
     if ((ei->i_reserved_data_blocks == 0) &&
         !inode_is_open_for_write(inode))
         ext4_discard_preallocations(inode, 0);
 }
 
 static int __check_block_validity(struct inode *inode, const char *func,
                 unsigned int line,
                 struct ext4_map_blocks *map)
 {
     if (ext4_has_feature_journal(inode->i_sb) &&
         (inode->i_ino ==
          le32_to_cpu(EXT4_SB(inode->i_sb)->s_es->s_journal_inum)))
         return 0;
     if (!ext4_inode_block_valid(inode, map->m_pblk, map->m_len)) {
         ext4_error_inode(inode, func, line, map->m_pblk,
                  "lblock %lu mapped to illegal pblock %llu "
                  "(length %d)", (unsigned long) map->m_lblk,
                  map->m_pblk, map->m_len);
         return -EFSCORRUPTED;
     }
     return 0;
 }
 
 int ext4_issue_zeroout(struct inode *inode, ext4_lblk_t lblk, ext4_fsblk_t pblk,
                ext4_lblk_t len)
 {
     int ret;
 
     if (IS_ENCRYPTED(inode) && S_ISREG(inode->i_mode))
         return fscrypt_zeroout_range(inode, lblk, pblk, len);
 
     ret = sb_issue_zeroout(inode->i_sb, pblk, len, GFP_NOFS);
     if (ret > 0)
         ret = 0;
 
     return ret;
 }
 
 #define check_block_validity(inode, map)    \
     __check_block_validity((inode), __func__, __LINE__, (map))
 
 #ifdef ES_AGGRESSIVE_TEST
 static void ext4_map_blocks_es_recheck(handle_t *handle,
                        struct inode *inode,
                        struct ext4_map_blocks *es_map,
                        struct ext4_map_blocks *map,
                        int flags)
 {
     int retval;
 
     map->m_flags = 0;
     /*
      * There is a race window that the result is not the same.
      * e.g. xfstests #223 when dioread_nolock enables.  The reason
      * is that we lookup a block mapping in extent status tree with
      * out taking i_data_sem.  So at the time the unwritten extent
      * could be converted.
      */
     down_read(&EXT4_I(inode)->i_data_sem);
     if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
         retval = ext4_ext_map_blocks(handle, inode, map, 0);
     } else {
         retval = ext4_ind_map_blocks(handle, inode, map, 0);
     }
     up_read((&EXT4_I(inode)->i_data_sem));
 
     /*
      * We don't check m_len because extent will be collpased in status
      * tree.  So the m_len might not equal.
      */
     if (es_map->m_lblk != map->m_lblk ||
         es_map->m_flags != map->m_flags ||
         es_map->m_pblk != map->m_pblk) {
         printk("ES cache assertion failed for inode: %lu "
                "es_cached ex [%d/%d/%llu/%x] != "
                "found ex [%d/%d/%llu/%x] retval %d flags %x\n",
                inode->i_ino, es_map->m_lblk, es_map->m_len,
                es_map->m_pblk, es_map->m_flags, map->m_lblk,
                map->m_len, map->m_pblk, map->m_flags,
                retval, flags);
     }
 }
 #endif /* ES_AGGRESSIVE_TEST */
 
 /*
  * The ext4_map_blocks() function tries to look up the requested blocks,
  * and returns if the blocks are already mapped.
  *
  * Otherwise it takes the write lock of the i_data_sem and allocate blocks
  * and store the allocated blocks in the result buffer head and mark it
  * mapped.
  *
  * If file type is extents based, it will call ext4_ext_map_blocks(),
  * Otherwise, call with ext4_ind_map_blocks() to handle indirect mapping
  * based files
  *
  * On success, it returns the number of blocks being mapped or allocated.  if
  * create==0 and the blocks are pre-allocated and unwritten, the resulting @map
  * is marked as unwritten. If the create == 1, it will mark @map as mapped.
  *
  * It returns 0 if plain look up failed (blocks have not been allocated), in
  * that case, @map is returned as unmapped but we still do fill map->m_len to
  * indicate the length of a hole starting at map->m_lblk.
  *
  * It returns the error in case of allocation failure.
  */
 int ext4_map_blocks(handle_t *handle, struct inode *inode,
             struct ext4_map_blocks *map, int flags)
 {
     struct extent_status es;
     int retval;
     int ret = 0;
 #ifdef ES_AGGRESSIVE_TEST
     struct ext4_map_blocks orig_map;
 
     memcpy(&orig_map, map, sizeof(*map));
 #endif
 
     map->m_flags = 0;
     ext_debug(inode, "flag 0x%x, max_blocks %u, logical block %lu\n",
           flags, map->m_len, (unsigned long) map->m_lblk);
 
     /*
      * ext4_map_blocks returns an int, and m_len is an unsigned int
      */
     if (unlikely(map->m_len > INT_MAX))
         map->m_len = INT_MAX;
 
     /* We can handle the block number less than EXT_MAX_BLOCKS */
     if (unlikely(map->m_lblk >= EXT_MAX_BLOCKS))
         return -EFSCORRUPTED;
 
     /* Lookup extent status tree firstly */
     if (!(EXT4_SB(inode->i_sb)->s_mount_state & EXT4_FC_REPLAY) &&
         ext4_es_lookup_extent(inode, map->m_lblk, NULL, &es)) {
         if (ext4_es_is_written(&es) || ext4_es_is_unwritten(&es)) {
             map->m_pblk = ext4_es_pblock(&es) +
                     map->m_lblk - es.es_lblk;
             map->m_flags |= ext4_es_is_written(&es) ?
                     EXT4_MAP_MAPPED : EXT4_MAP_UNWRITTEN;
             retval = es.es_len - (map->m_lblk - es.es_lblk);
             if (retval > map->m_len)
                 retval = map->m_len;
             map->m_len = retval;
         } else if (ext4_es_is_delayed(&es) || ext4_es_is_hole(&es)) {
             map->m_pblk = 0;
             retval = es.es_len - (map->m_lblk - es.es_lblk);
             if (retval > map->m_len)
                 retval = map->m_len;
             map->m_len = retval;
             retval = 0;
         } else {
             BUG();
         }
 
         if (flags & EXT4_GET_BLOCKS_CACHED_NOWAIT)
             return retval;
 #ifdef ES_AGGRESSIVE_TEST
         ext4_map_blocks_es_recheck(handle, inode, map,
                        &orig_map, flags);
 #endif
         goto found;
     }
     /*
      * In the query cache no-wait mode, nothing we can do more if we
      * cannot find extent in the cache.
      */
     if (flags & EXT4_GET_BLOCKS_CACHED_NOWAIT)
         return 0;
 
     /*
      * Try to see if we can get the block without requesting a new
      * file system block.
      */
     down_read(&EXT4_I(inode)->i_data_sem);
     if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
         retval = ext4_ext_map_blocks(handle, inode, map, 0);
     } else {
         retval = ext4_ind_map_blocks(handle, inode, map, 0);
     }
     if (retval > 0) {
         unsigned int status;
 
         if (unlikely(retval != map->m_len)) {
             ext4_warning(inode->i_sb,
                      "ES len assertion failed for inode "
                      "%lu: retval %d != map->m_len %d",
                      inode->i_ino, retval, map->m_len);
             WARN_ON(1);
         }
 
         status = map->m_flags & EXT4_MAP_UNWRITTEN ?
                 EXTENT_STATUS_UNWRITTEN : EXTENT_STATUS_WRITTEN;
         if (!(flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE) &&
             !(status & EXTENT_STATUS_WRITTEN) &&
             ext4_es_scan_range(inode, &ext4_es_is_delayed, map->m_lblk,
                        map->m_lblk + map->m_len - 1))
             status |= EXTENT_STATUS_DELAYED;
         ret = ext4_es_insert_extent(inode, map->m_lblk,
                         map->m_len, map->m_pblk, status);
         if (ret < 0)
             retval = ret;
     }
     up_read((&EXT4_I(inode)->i_data_sem));
 
 found:
     if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED) {
         ret = check_block_validity(inode, map);
         if (ret != 0)
             return ret;
     }
 
     /* If it is only a block(s) look up */
     if ((flags & EXT4_GET_BLOCKS_CREATE) == 0)
         return retval;
 
     /*
      * Returns if the blocks have already allocated
      *
      * Note that if blocks have been preallocated
      * ext4_ext_get_block() returns the create = 0
      * with buffer head unmapped.
      */
     if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED)
         /*
          * If we need to convert extent to unwritten
          * we continue and do the actual work in
          * ext4_ext_map_blocks()
          */
         if (!(flags & EXT4_GET_BLOCKS_CONVERT_UNWRITTEN))
             return retval;
 
     /*
      * Here we clear m_flags because after allocating an new extent,
      * it will be set again.
      */
     map->m_flags &= ~EXT4_MAP_FLAGS;
 
     /*
      * New blocks allocate and/or writing to unwritten extent
      * will possibly result in updating i_data, so we take
      * the write lock of i_data_sem, and call get_block()
      * with create == 1 flag.
      */
     down_write(&EXT4_I(inode)->i_data_sem);
 
     /*
      * We need to check for EXT4 here because migrate
      * could have changed the inode type in between
      */
     if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
         retval = ext4_ext_map_blocks(handle, inode, map, flags);
     } else {
         retval = ext4_ind_map_blocks(handle, inode, map, flags);
 
         if (retval > 0 && map->m_flags & EXT4_MAP_NEW) {
             /*
              * We allocated new blocks which will result in
              * i_data's format changing.  Force the migrate
              * to fail by clearing migrate flags
              */
             ext4_clear_inode_state(inode, EXT4_STATE_EXT_MIGRATE);
         }
 
         /*
          * Update reserved blocks/metadata blocks after successful
          * block allocation which had been deferred till now. We don't
          * support fallocate for non extent files. So we can update
          * reserve space here.
          */
         if ((retval > 0) &&
             (flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE))
             ext4_da_update_reserve_space(inode, retval, 1);
     }
 
     if (retval > 0) {
         unsigned int status;
 
         if (unlikely(retval != map->m_len)) {
             ext4_warning(inode->i_sb,
                      "ES len assertion failed for inode "
                      "%lu: retval %d != map->m_len %d",
                      inode->i_ino, retval, map->m_len);
             WARN_ON(1);
         }
 
         /*
          * We have to zeroout blocks before inserting them into extent
          * status tree. Otherwise someone could look them up there and
          * use them before they are really zeroed. We also have to
          * unmap metadata before zeroing as otherwise writeback can
          * overwrite zeros with stale data from block device.
          */
         if (flags & EXT4_GET_BLOCKS_ZERO &&
             map->m_flags & EXT4_MAP_MAPPED &&
             map->m_flags & EXT4_MAP_NEW) {
             ret = ext4_issue_zeroout(inode, map->m_lblk,
                          map->m_pblk, map->m_len);
             if (ret) {
                 retval = ret;
                 goto out_sem;
             }
         }
 
         /*
          * If the extent has been zeroed out, we don't need to update
          * extent status tree.
          */
         if ((flags & EXT4_GET_BLOCKS_PRE_IO) &&
             ext4_es_lookup_extent(inode, map->m_lblk, NULL, &es)) {
             if (ext4_es_is_written(&es))
                 goto out_sem;
         }
         status = map->m_flags & EXT4_MAP_UNWRITTEN ?
                 EXTENT_STATUS_UNWRITTEN : EXTENT_STATUS_WRITTEN;
         if (!(flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE) &&
             !(status & EXTENT_STATUS_WRITTEN) &&
             ext4_es_scan_range(inode, &ext4_es_is_delayed, map->m_lblk,
                        map->m_lblk + map->m_len - 1))
             status |= EXTENT_STATUS_DELAYED;
         ret = ext4_es_insert_extent(inode, map->m_lblk, map->m_len,
                         map->m_pblk, status);
         if (ret < 0) {
             retval = ret;
             goto out_sem;
         }
     }
 
 out_sem:
     up_write((&EXT4_I(inode)->i_data_sem));
     if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED) {
         ret = check_block_validity(inode, map);
         if (ret != 0)
             return ret;
 
         /*
          * Inodes with freshly allocated blocks where contents will be
          * visible after transaction commit must be on transaction's
          * ordered data list.
          */
         if (map->m_flags & EXT4_MAP_NEW &&
             !(map->m_flags & EXT4_MAP_UNWRITTEN) &&
             !(flags & EXT4_GET_BLOCKS_ZERO) &&
             !ext4_is_quota_file(inode) &&
             ext4_should_order_data(inode)) {
             loff_t start_byte =
                 (loff_t)map->m_lblk << inode->i_blkbits;
             loff_t length = (loff_t)map->m_len << inode->i_blkbits;
 
             if (flags & EXT4_GET_BLOCKS_IO_SUBMIT)
                 ret = ext4_jbd2_inode_add_wait(handle, inode,
                         start_byte, length);
             else
                 ret = ext4_jbd2_inode_add_write(handle, inode,
                         start_byte, length);
             if (ret)
                 return ret;
         }
     }
     if (retval > 0 && (map->m_flags & EXT4_MAP_UNWRITTEN ||
                 map->m_flags & EXT4_MAP_MAPPED))
         ext4_fc_track_range(handle, inode, map->m_lblk,
                     map->m_lblk + map->m_len - 1);
     if (retval < 0)
         ext_debug(inode, "failed with err %d\n", retval);
     return retval;
 }
 
 /*
  * Update EXT4_MAP_FLAGS in bh->b_state. For buffer heads attached to pages
  * we have to be careful as someone else may be manipulating b_state as well.
  */
 static void ext4_update_bh_state(struct buffer_head *bh, unsigned long flags)
 {
     unsigned long old_state;
     unsigned long new_state;
 
     flags &= EXT4_MAP_FLAGS;
 
     /* Dummy buffer_head? Set non-atomically. */
     if (!bh->b_page) {
         bh->b_state = (bh->b_state & ~EXT4_MAP_FLAGS) | flags;
         return;
     }
     /*
      * Someone else may be modifying b_state. Be careful! This is ugly but
      * once we get rid of using bh as a container for mapping information
      * to pass to / from get_block functions, this can go away.
      */
     do {
         old_state = READ_ONCE(bh->b_state);
         new_state = (old_state & ~EXT4_MAP_FLAGS) | flags;
     } while (unlikely(
          cmpxchg(&bh->b_state, old_state, new_state) != old_state));
 }
 
 static int _ext4_get_block(struct inode *inode, sector_t iblock,
                struct buffer_head *bh, int flags)
 {
     struct ext4_map_blocks map;
     int ret = 0;
 
     if (ext4_has_inline_data(inode))
         return -ERANGE;
 
     map.m_lblk = iblock;
     map.m_len = bh->b_size >> inode->i_blkbits;
 
     ret = ext4_map_blocks(ext4_journal_current_handle(), inode, &map,
                   flags);
     if (ret > 0) {
         map_bh(bh, inode->i_sb, map.m_pblk);
         ext4_update_bh_state(bh, map.m_flags);
         bh->b_size = inode->i_sb->s_blocksize * map.m_len;
         ret = 0;
     } else if (ret == 0) {
         /* hole case, need to fill in bh->b_size */
         bh->b_size = inode->i_sb->s_blocksize * map.m_len;
     }
     return ret;
 }
 
 int ext4_get_block(struct inode *inode, sector_t iblock,
            struct buffer_head *bh, int create)
 {
     return _ext4_get_block(inode, iblock, bh,
                    create ? EXT4_GET_BLOCKS_CREATE : 0);
 }
 
 /*
  * Get block function used when preparing for buffered write if we require
  * creating an unwritten extent if blocks haven't been allocated.  The extent
  * will be converted to written after the IO is complete.
  */
 int ext4_get_block_unwritten(struct inode *inode, sector_t iblock,
                  struct buffer_head *bh_result, int create)
 {
     ext4_debug("ext4_get_block_unwritten: inode %lu, create flag %d\n",
            inode->i_ino, create);
     return _ext4_get_block(inode, iblock, bh_result,
                    EXT4_GET_BLOCKS_CREATE_UNWRIT_EXT);
 }
 
 /* Maximum number of blocks we map for direct IO at once. */
 #define DIO_MAX_BLOCKS 4096
 
 /*
  * `handle' can be NULL if create is zero
  */
 struct buffer_head *ext4_getblk(handle_t *handle, struct inode *inode,
                 ext4_lblk_t block, int map_flags)
 {
     struct ext4_map_blocks map;
     struct buffer_head *bh;
     int create = map_flags & EXT4_GET_BLOCKS_CREATE;
     bool nowait = map_flags & EXT4_GET_BLOCKS_CACHED_NOWAIT;
     int err;
 
     ASSERT((EXT4_SB(inode->i_sb)->s_mount_state & EXT4_FC_REPLAY)
             || handle != NULL || create == 0);
     ASSERT(create == 0 || !nowait);
 
     map.m_lblk = block;
     map.m_len = 1;
     err = ext4_map_blocks(handle, inode, &map, map_flags);
 
     if (err == 0)
         return create ? ERR_PTR(-ENOSPC) : NULL;
     if (err < 0)
         return ERR_PTR(err);
 
     if (nowait)
         return sb_find_get_block(inode->i_sb, map.m_pblk);
 
     bh = sb_getblk(inode->i_sb, map.m_pblk);
     if (unlikely(!bh))
         return ERR_PTR(-ENOMEM);
     if (map.m_flags & EXT4_MAP_NEW) {
         ASSERT(create != 0);
         ASSERT((EXT4_SB(inode->i_sb)->s_mount_state & EXT4_FC_REPLAY)
                 || (handle != NULL));
 
         /*
          * Now that we do not always journal data, we should
          * keep in mind whether this should always journal the
          * new buffer as metadata.  For now, regular file
          * writes use ext4_get_block instead, so it's not a
          * problem.
          */
         lock_buffer(bh);
         BUFFER_TRACE(bh, "call get_create_access");
         err = ext4_journal_get_create_access(handle, inode->i_sb, bh,
                              EXT4_JTR_NONE);
         if (unlikely(err)) {
             unlock_buffer(bh);
             goto errout;
         }
         if (!buffer_uptodate(bh)) {
             memset(bh->b_data, 0, inode->i_sb->s_blocksize);
             set_buffer_uptodate(bh);
         }
         unlock_buffer(bh);
         BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
         err = ext4_handle_dirty_metadata(handle, inode, bh);
         if (unlikely(err))
             goto errout;
     } else
         BUFFER_TRACE(bh, "not a new buffer");
     return bh;
 errout:
     brelse(bh);
     return ERR_PTR(err);
 }
 
 struct buffer_head *ext4_bread(handle_t *handle, struct inode *inode,
                    ext4_lblk_t block, int map_flags)
 {
     struct buffer_head *bh;
     int ret;
 
     bh = ext4_getblk(handle, inode, block, map_flags);
     if (IS_ERR(bh))
         return bh;
     if (!bh || ext4_buffer_uptodate(bh))
         return bh;
 
     ret = ext4_read_bh_lock(bh, REQ_META | REQ_PRIO, true);
     if (ret) {
         put_bh(bh);
         return ERR_PTR(ret);
     }
     return bh;
 }
 
 /* Read a contiguous batch of blocks. */
 int ext4_bread_batch(struct inode *inode, ext4_lblk_t block, int bh_count,
              bool wait, struct buffer_head **bhs)
 {
     int i, err;
 
     for (i = 0; i < bh_count; i++) {
         bhs[i] = ext4_getblk(NULL, inode, block + i, 0 /* map_flags */);
         if (IS_ERR(bhs[i])) {
             err = PTR_ERR(bhs[i]);
             bh_count = i;
             goto out_brelse;
         }
     }
 
     for (i = 0; i < bh_count; i++)
         /* Note that NULL bhs[i] is valid because of holes. */
         if (bhs[i] && !ext4_buffer_uptodate(bhs[i]))
             ext4_read_bh_lock(bhs[i], REQ_META | REQ_PRIO, false);
 
     if (!wait)
         return 0;
 
     for (i = 0; i < bh_count; i++)
         if (bhs[i])
             wait_on_buffer(bhs[i]);
 
     for (i = 0; i < bh_count; i++) {
         if (bhs[i] && !buffer_uptodate(bhs[i])) {
             err = -EIO;
             goto out_brelse;
         }
     }
     return 0;
 
 out_brelse:
     for (i = 0; i < bh_count; i++) {
         brelse(bhs[i]);
         bhs[i] = NULL;
     }
     return err;
 }
 
 int ext4_walk_page_buffers(handle_t *handle, struct inode *inode,
                struct buffer_head *head,
                unsigned from,
                unsigned to,
                int *partial,
                int (*fn)(handle_t *handle, struct inode *inode,
                      struct buffer_head *bh))
 {
     struct buffer_head *bh;
     unsigned block_start, block_end;
     unsigned blocksize = head->b_size;
     int err, ret = 0;
     struct buffer_head *next;
 
     for (bh = head, block_start = 0;
          ret == 0 && (bh != head || !block_start);
          block_start = block_end, bh = next) {
         next = bh->b_this_page;
         block_end = block_start + blocksize;
         if (block_end <= from || block_start >= to) {
             if (partial && !buffer_uptodate(bh))
                 *partial = 1;
             continue;
         }
         err = (*fn)(handle, inode, bh);
         if (!ret)
             ret = err;
     }
     return ret;
 }
 
 /*
  * To preserve ordering, it is essential that the hole instantiation and
  * the data write be encapsulated in a single transaction.  We cannot
  * close off a transaction and start a new one between the ext4_get_block()
  * and the commit_write().  So doing the jbd2_journal_start at the start of
  * prepare_write() is the right place.
  *
  * Also, this function can nest inside ext4_writepage().  In that case, we
  * *know* that ext4_writepage() has generated enough buffer credits to do the
  * whole page.  So we won't block on the journal in that case, which is good,
  * because the caller may be PF_MEMALLOC.
  *
  * By accident, ext4 can be reentered when a transaction is open via
  * quota file writes.  If we were to commit the transaction while thus
  * reentered, there can be a deadlock - we would be holding a quota
  * lock, and the commit would never complete if another thread had a
  * transaction open and was blocking on the quota lock - a ranking
  * violation.
  *
  * So what we do is to rely on the fact that jbd2_journal_stop/journal_start
  * will _not_ run commit under these circumstances because handle->h_ref
  * is elevated.  We'll still have enough credits for the tiny quotafile
  * write.
  */
 int do_journal_get_write_access(handle_t *handle, struct inode *inode,
                 struct buffer_head *bh)
 {
     int dirty = buffer_dirty(bh);
     int ret;
 
     if (!buffer_mapped(bh) || buffer_freed(bh))
         return 0;
     /*
      * __block_write_begin() could have dirtied some buffers. Clean
      * the dirty bit as jbd2_journal_get_write_access() could complain
      * otherwise about fs integrity issues. Setting of the dirty bit
      * by __block_write_begin() isn't a real problem here as we clear
      * the bit before releasing a page lock and thus writeback cannot
      * ever write the buffer.
      */
     if (dirty)
         clear_buffer_dirty(bh);
     BUFFER_TRACE(bh, "get write access");
     ret = ext4_journal_get_write_access(handle, inode->i_sb, bh,
                         EXT4_JTR_NONE);
     if (!ret && dirty)
         ret = ext4_handle_dirty_metadata(handle, NULL, bh);
     return ret;
 }
 
 #ifdef CONFIG_FS_ENCRYPTION
 static int ext4_block_write_begin(struct page *page, loff_t pos, unsigned len,
                   get_block_t *get_block)
 {
     unsigned from = pos & (PAGE_SIZE - 1);
     unsigned to = from + len;
     struct inode *inode = page->mapping->host;
     unsigned block_start, block_end;
     sector_t block;
     int err = 0;
     unsigned blocksize = inode->i_sb->s_blocksize;
     unsigned bbits;
     struct buffer_head *bh, *head, *wait[2];
     int nr_wait = 0;
     int i;
 
     BUG_ON(!PageLocked(page));
     BUG_ON(from > PAGE_SIZE);
     BUG_ON(to > PAGE_SIZE);
     BUG_ON(from > to);
 
     if (!page_has_buffers(page))
         create_empty_buffers(page, blocksize, 0);
     head = page_buffers(page);
     bbits = ilog2(blocksize);
     block = (sector_t)page->index << (PAGE_SHIFT - bbits);
 
     for (bh = head, block_start = 0; bh != head || !block_start;
         block++, block_start = block_end, bh = bh->b_this_page) {
         block_end = block_start + blocksize;
         if (block_end <= from || block_start >= to) {
             if (PageUptodate(page)) {
                 set_buffer_uptodate(bh);
             }
             continue;
         }
         if (buffer_new(bh))
             clear_buffer_new(bh);
         if (!buffer_mapped(bh)) {
             WARN_ON(bh->b_size != blocksize);
             err = get_block(inode, block, bh, 1);
             if (err)
                 break;
             if (buffer_new(bh)) {
                 if (PageUptodate(page)) {
                     clear_buffer_new(bh);
                     set_buffer_uptodate(bh);
                     mark_buffer_dirty(bh);
                     continue;
                 }
                 if (block_end > to || block_start < from)
                     zero_user_segments(page, to, block_end,
                                block_start, from);
                 continue;
             }
         }
         if (PageUptodate(page)) {
             set_buffer_uptodate(bh);
             continue;
         }
         if (!buffer_uptodate(bh) && !buffer_delay(bh) &&
             !buffer_unwritten(bh) &&
             (block_start < from || block_end > to)) {
             ext4_read_bh_lock(bh, 0, false);
             wait[nr_wait++] = bh;
         }
     }
     /*
      * If we issued read requests, let them complete.
      */
     for (i = 0; i < nr_wait; i++) {
         wait_on_buffer(wait[i]);
         if (!buffer_uptodate(wait[i]))
             err = -EIO;
     }
     if (unlikely(err)) {
         page_zero_new_buffers(page, from, to);
     } else if (fscrypt_inode_uses_fs_layer_crypto(inode)) {
         for (i = 0; i < nr_wait; i++) {
             int err2;
 
             err2 = fscrypt_decrypt_pagecache_blocks(page, blocksize,
                                 bh_offset(wait[i]));
             if (err2) {
                 clear_buffer_uptodate(wait[i]);
                 err = err2;
             }
         }
     }
 
     return err;
 }
 #endif
 
 static int ext4_write_begin(struct file *file, struct address_space *mapping,
                 loff_t pos, unsigned len,
                 struct page **pagep, void **fsdata)
 {
     struct inode *inode = mapping->host;
     int ret, needed_blocks;
     handle_t *handle;
     int retries = 0;
     struct page *page;
     pgoff_t index;
     unsigned from, to;
 
     if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
         return -EIO;
 
     trace_ext4_write_begin(inode, pos, len);
     /*
      * Reserve one block more for addition to orphan list in case
      * we allocate blocks but write fails for some reason
      */
     needed_blocks = ext4_writepage_trans_blocks(inode) + 1;
     index = pos >> PAGE_SHIFT;
     from = pos & (PAGE_SIZE - 1);
     to = from + len;
 
     if (ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA)) {
         ret = ext4_try_to_write_inline_data(mapping, inode, pos, len,
                             pagep);
         if (ret < 0)
             return ret;
         if (ret == 1)
             return 0;
     }
 
     /*
      * grab_cache_page_write_begin() can take a long time if the
      * system is thrashing due to memory pressure, or if the page
      * is being written back.  So grab it first before we start
      * the transaction handle.  This also allows us to allocate
      * the page (if needed) without using GFP_NOFS.
      */
 retry_grab:
     page = grab_cache_page_write_begin(mapping, index);
     if (!page)
         return -ENOMEM;
     unlock_page(page);
 
 retry_journal:
     handle = ext4_journal_start(inode, EXT4_HT_WRITE_PAGE, needed_blocks);
     if (IS_ERR(handle)) {
         put_page(page);
         return PTR_ERR(handle);
     }
 
     lock_page(page);
     if (page->mapping != mapping) {
         /* The page got truncated from under us */
         unlock_page(page);
         put_page(page);
         ext4_journal_stop(handle);
         goto retry_grab;
     }
     /* In case writeback began while the page was unlocked */
     wait_for_stable_page(page);
 
 #ifdef CONFIG_FS_ENCRYPTION
     if (ext4_should_dioread_nolock(inode))
         ret = ext4_block_write_begin(page, pos, len,
                          ext4_get_block_unwritten);
     else
         ret = ext4_block_write_begin(page, pos, len,
                          ext4_get_block);
 #else
     if (ext4_should_dioread_nolock(inode))
         ret = __block_write_begin(page, pos, len,
                       ext4_get_block_unwritten);
     else
         ret = __block_write_begin(page, pos, len, ext4_get_block);
 #endif
     if (!ret && ext4_should_journal_data(inode)) {
         ret = ext4_walk_page_buffers(handle, inode,
                          page_buffers(page), from, to, NULL,
                          do_journal_get_write_access);
     }
 
     if (ret) {
         bool extended = (pos + len > inode->i_size) &&
                 !ext4_verity_in_progress(inode);
 
         unlock_page(page);
         /*
          * __block_write_begin may have instantiated a few blocks
          * outside i_size.  Trim these off again. Don't need
          * i_size_read because we hold i_rwsem.
          *
          * Add inode to orphan list in case we crash before
          * truncate finishes
          */
         if (extended && ext4_can_truncate(inode))
             ext4_orphan_add(handle, inode);
 
         ext4_journal_stop(handle);
         if (extended) {
             ext4_truncate_failed_write(inode);
             /*
              * If truncate failed early the inode might
              * still be on the orphan list; we need to
              * make sure the inode is removed from the
              * orphan list in that case.
              */
             if (inode->i_nlink)
                 ext4_orphan_del(NULL, inode);
         }
 
         if (ret == -ENOSPC &&
             ext4_should_retry_alloc(inode->i_sb, &retries))
             goto retry_journal;
         put_page(page);
         return ret;
     }
     *pagep = page;
     return ret;
 }
 
 /* For write_end() in data=journal mode */
 static int write_end_fn(handle_t *handle, struct inode *inode,
             struct buffer_head *bh)
 {
     int ret;
     if (!buffer_mapped(bh) || buffer_freed(bh))
         return 0;
     set_buffer_uptodate(bh);
     ret = ext4_handle_dirty_metadata(handle, NULL, bh);
     clear_buffer_meta(bh);
     clear_buffer_prio(bh);
     return ret;
 }
 
 /*
  * We need to pick up the new inode size which generic_commit_write gave us
  * `file' can be NULL - eg, when called from page_symlink().
  *
  * ext4 never places buffers on inode->i_mapping->private_list.  metadata
  * buffers are managed internally.
  */
 static int ext4_write_end(struct file *file,
               struct address_space *mapping,
               loff_t pos, unsigned len, unsigned copied,
               struct page *page, void *fsdata)
 {
     handle_t *handle = ext4_journal_current_handle();
     struct inode *inode = mapping->host;
     loff_t old_size = inode->i_size;
     int ret = 0, ret2;
     int i_size_changed = 0;
     bool verity = ext4_verity_in_progress(inode);
 
     trace_ext4_write_end(inode, pos, len, copied);
 
     if (ext4_has_inline_data(inode))
         return ext4_write_inline_data_end(inode, pos, len, copied, page);
 
     copied = block_write_end(file, mapping, pos, len, copied, page, fsdata);
     /*
      * it's important to update i_size while still holding page lock:
      * page writeout could otherwise come in and zero beyond i_size.
      *
      * If FS_IOC_ENABLE_VERITY is running on this inode, then Merkle tree
      * blocks are being written past EOF, so skip the i_size update.
      */
     if (!verity)
         i_size_changed = ext4_update_inode_size(inode, pos + copied);
     unlock_page(page);
     put_page(page);
 
     if (old_size < pos && !verity)
         pagecache_isize_extended(inode, old_size, pos);
     /*
      * Don't mark the inode dirty under page lock. First, it unnecessarily
      * makes the holding time of page lock longer. Second, it forces lock
      * ordering of page lock and transaction start for journaling
      * filesystems.
      */
     if (i_size_changed)
         ret = ext4_mark_inode_dirty(handle, inode);
 
     if (pos + len > inode->i_size && !verity && ext4_can_truncate(inode))
         /* if we have allocated more blocks and copied
          * less. We will have blocks allocated outside
          * inode->i_size. So truncate them
          */
         ext4_orphan_add(handle, inode);
 
     ret2 = ext4_journal_stop(handle);
     if (!ret)
         ret = ret2;
 
     if (pos + len > inode->i_size && !verity) {
         ext4_truncate_failed_write(inode);
         /*
          * If truncate failed early the inode might still be
          * on the orphan list; we need to make sure the inode
          * is removed from the orphan list in that case.
          */
         if (inode->i_nlink)
             ext4_orphan_del(NULL, inode);
     }
 
     return ret ? ret : copied;
 }
 
 /*
  * This is a private version of page_zero_new_buffers() which doesn't
  * set the buffer to be dirty, since in data=journalled mode we need
  * to call ext4_handle_dirty_metadata() instead.
  */
 static void ext4_journalled_zero_new_buffers(handle_t *handle,
                         struct inode *inode,
                         struct page *page,
                         unsigned from, unsigned to)
 {
     unsigned int block_start = 0, block_end;
     struct buffer_head *head, *bh;
 
     bh = head = page_buffers(page);
     do {
         block_end = block_start + bh->b_size;
         if (buffer_new(bh)) {
             if (block_end > from && block_start < to) {
                 if (!PageUptodate(page)) {
                     unsigned start, size;
 
                     start = max(from, block_start);
                     size = min(to, block_end) - start;
 
                     zero_user(page, start, size);
                     write_end_fn(handle, inode, bh);
                 }
                 clear_buffer_new(bh);
             }
         }
         block_start = block_end;
         bh = bh->b_this_page;
     } while (bh != head);
 }
 
 static int ext4_journalled_write_end(struct file *file,
                      struct address_space *mapping,
                      loff_t pos, unsigned len, unsigned copied,
                      struct page *page, void *fsdata)
 {
     handle_t *handle = ext4_journal_current_handle();
     struct inode *inode = mapping->host;
     loff_t old_size = inode->i_size;
     int ret = 0, ret2;
     int partial = 0;
     unsigned from, to;
     int size_changed = 0;
     bool verity = ext4_verity_in_progress(inode);
 
     trace_ext4_journalled_write_end(inode, pos, len, copied);
     from = pos & (PAGE_SIZE - 1);
     to = from + len;
 
     BUG_ON(!ext4_handle_valid(handle));
 
     if (ext4_has_inline_data(inode))
         return ext4_write_inline_data_end(inode, pos, len, copied, page);
 
     if (unlikely(copied < len) && !PageUptodate(page)) {
         copied = 0;
         ext4_journalled_zero_new_buffers(handle, inode, page, from, to);
     } else {
         if (unlikely(copied < len))
             ext4_journalled_zero_new_buffers(handle, inode, page,
                              from + copied, to);
         ret = ext4_walk_page_buffers(handle, inode, page_buffers(page),
                          from, from + copied, &partial,
                          write_end_fn);
         if (!partial)
             SetPageUptodate(page);
     }
     if (!verity)
         size_changed = ext4_update_inode_size(inode, pos + copied);
     ext4_set_inode_state(inode, EXT4_STATE_JDATA);
     EXT4_I(inode)->i_datasync_tid = handle->h_transaction->t_tid;
     unlock_page(page);
     put_page(page);
 
     if (old_size < pos && !verity)
         pagecache_isize_extended(inode, old_size, pos);
 
     if (size_changed) {
         ret2 = ext4_mark_inode_dirty(handle, inode);
         if (!ret)
             ret = ret2;
     }
 
     if (pos + len > inode->i_size && !verity && ext4_can_truncate(inode))
         /* if we have allocated more blocks and copied
          * less. We will have blocks allocated outside
          * inode->i_size. So truncate them
          */
         ext4_orphan_add(handle, inode);
 
     ret2 = ext4_journal_stop(handle);
     if (!ret)
         ret = ret2;
     if (pos + len > inode->i_size && !verity) {
         ext4_truncate_failed_write(inode);
         /*
          * If truncate failed early the inode might still be
          * on the orphan list; we need to make sure the inode
          * is removed from the orphan list in that case.
          */
         if (inode->i_nlink)
             ext4_orphan_del(NULL, inode);
     }
 
     return ret ? ret : copied;
 }
 
 /*
  * Reserve space for a single cluster
  */
 static int ext4_da_reserve_space(struct inode *inode)
 {
     struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
     struct ext4_inode_info *ei = EXT4_I(inode);
     int ret;
 
     /*
      * We will charge metadata quota at writeout time; this saves
      * us from metadata over-estimation, though we may go over by
      * a small amount in the end.  Here we just reserve for data.
      */
     ret = dquot_reserve_block(inode, EXT4_C2B(sbi, 1));
     if (ret)
         return ret;
 
     spin_lock(&ei->i_block_reservation_lock);
     if (ext4_claim_free_clusters(sbi, 1, 0)) {
         spin_unlock(&ei->i_block_reservation_lock);
         dquot_release_reservation_block(inode, EXT4_C2B(sbi, 1));
         return -ENOSPC;
     }
     ei->i_reserved_data_blocks++;
     trace_ext4_da_reserve_space(inode);
     spin_unlock(&ei->i_block_reservation_lock);
 
     return 0;       /* success */
 }
 
 void ext4_da_release_space(struct inode *inode, int to_free)
 {
     struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
     struct ext4_inode_info *ei = EXT4_I(inode);
 
     if (!to_free)
         return;     /* Nothing to release, exit */
 
     spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
 
     trace_ext4_da_release_space(inode, to_free);
     if (unlikely(to_free > ei->i_reserved_data_blocks)) {
         /*
          * if there aren't enough reserved blocks, then the
          * counter is messed up somewhere.  Since this
          * function is called from invalidate page, it's
          * harmless to return without any action.
          */
         ext4_warning(inode->i_sb, "ext4_da_release_space: "
              "ino %lu, to_free %d with only %d reserved "
              "data blocks", inode->i_ino, to_free,
              ei->i_reserved_data_blocks);
         WARN_ON(1);
         to_free = ei->i_reserved_data_blocks;
     }
     ei->i_reserved_data_blocks -= to_free;
 
     /* update fs dirty data blocks counter */
     percpu_counter_sub(&sbi->s_dirtyclusters_counter, to_free);
 
     spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
 
     dquot_release_reservation_block(inode, EXT4_C2B(sbi, to_free));
 }
 
 /*
  * Delayed allocation stuff
  */
 
 struct mpage_da_data {
     struct inode *inode;
     struct writeback_control *wbc;
 
     pgoff_t first_page; /* The first page to write */
     pgoff_t next_page;  /* Current page to examine */
     pgoff_t last_page;  /* Last page to examine */
     /*
      * Extent to map - this can be after first_page because that can be
      * fully mapped. We somewhat abuse m_flags to store whether the extent
      * is delalloc or unwritten.
      */
     struct ext4_map_blocks map;
     struct ext4_io_submit io_submit;    /* IO submission data */
     unsigned int do_map:1;
     unsigned int scanned_until_end:1;
 };
 
 static void mpage_release_unused_pages(struct mpage_da_data *mpd,
                        bool invalidate)
 {
     unsigned nr, i;
     pgoff_t index, end;
     struct folio_batch fbatch;
     struct inode *inode = mpd->inode;
     struct address_space *mapping = inode->i_mapping;
 
     /* This is necessary when next_page == 0. */
     if (mpd->first_page >= mpd->next_page)
         return;
 
     mpd->scanned_until_end = 0;
     index = mpd->first_page;
     end   = mpd->next_page - 1;
     if (invalidate) {
         ext4_lblk_t start, last;
         start = index << (PAGE_SHIFT - inode->i_blkbits);
         last = end << (PAGE_SHIFT - inode->i_blkbits);
 
         /*
          * avoid racing with extent status tree scans made by
          * ext4_insert_delayed_block()
          */
         down_write(&EXT4_I(inode)->i_data_sem);
         ext4_es_remove_extent(inode, start, last - start + 1);
         up_write(&EXT4_I(inode)->i_data_sem);
     }
 
     folio_batch_init(&fbatch);
     while (index <= end) {
         nr = filemap_get_folios(mapping, &index, end, &fbatch);
         if (nr == 0)
             break;
         for (i = 0; i < nr; i++) {
             struct folio *folio = fbatch.folios[i];
 
             if (folio->index < mpd->first_page)
                 continue;
             if (folio->index + folio_nr_pages(folio) - 1 > end)
                 continue;
             BUG_ON(!folio_test_locked(folio));
             BUG_ON(folio_test_writeback(folio));
             if (invalidate) {
                 if (folio_mapped(folio))
                     folio_clear_dirty_for_io(folio);
                 block_invalidate_folio(folio, 0,
                         folio_size(folio));
                 folio_clear_uptodate(folio);
             }
             folio_unlock(folio);
         }
         folio_batch_release(&fbatch);
     }
 }
 
 static void ext4_print_free_blocks(struct inode *inode)
 {
     struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
     struct super_block *sb = inode->i_sb;
     struct ext4_inode_info *ei = EXT4_I(inode);
 
     ext4_msg(sb, KERN_CRIT, "Total free blocks count %lld",
            EXT4_C2B(EXT4_SB(inode->i_sb),
             ext4_count_free_clusters(sb)));
     ext4_msg(sb, KERN_CRIT, "Free/Dirty block details");
     ext4_msg(sb, KERN_CRIT, "free_blocks=%lld",
            (long long) EXT4_C2B(EXT4_SB(sb),
         percpu_counter_sum(&sbi->s_freeclusters_counter)));
     ext4_msg(sb, KERN_CRIT, "dirty_blocks=%lld",
            (long long) EXT4_C2B(EXT4_SB(sb),
         percpu_counter_sum(&sbi->s_dirtyclusters_counter)));
     ext4_msg(sb, KERN_CRIT, "Block reservation details");
     ext4_msg(sb, KERN_CRIT, "i_reserved_data_blocks=%u",
          ei->i_reserved_data_blocks);
     return;
 }
 
 static int ext4_bh_delay_or_unwritten(handle_t *handle, struct inode *inode,
                       struct buffer_head *bh)
 {
     return (buffer_delay(bh) || buffer_unwritten(bh)) && buffer_dirty(bh);
 }
 
 /*
  * ext4_insert_delayed_block - adds a delayed block to the extents status
  *                             tree, incrementing the reserved cluster/block
  *                             count or making a pending reservation
  *                             where needed
  *
  * @inode - file containing the newly added block
  * @lblk - logical block to be added
  *
  * Returns 0 on success, negative error code on failure.
  */
 static int ext4_insert_delayed_block(struct inode *inode, ext4_lblk_t lblk)
 {
     struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
     int ret;
     bool allocated = false;
     bool reserved = false;
 
     /*
      * If the cluster containing lblk is shared with a delayed,
      * written, or unwritten extent in a bigalloc file system, it's
      * already been accounted for and does not need to be reserved.
      * A pending reservation must be made for the cluster if it's
      * shared with a written or unwritten extent and doesn't already
      * have one.  Written and unwritten extents can be purged from the
      * extents status tree if the system is under memory pressure, so
      * it's necessary to examine the extent tree if a search of the
      * extents status tree doesn't get a match.
      */
     if (sbi->s_cluster_ratio == 1) {
         ret = ext4_da_reserve_space(inode);
         if (ret != 0)   /* ENOSPC */
             goto errout;
         reserved = true;
     } else {   /* bigalloc */
         if (!ext4_es_scan_clu(inode, &ext4_es_is_delonly, lblk)) {
             if (!ext4_es_scan_clu(inode,
                           &ext4_es_is_mapped, lblk)) {
                 ret = ext4_clu_mapped(inode,
                               EXT4_B2C(sbi, lblk));
                 if (ret < 0)
                     goto errout;
                 if (ret == 0) {
                     ret = ext4_da_reserve_space(inode);
                     if (ret != 0)   /* ENOSPC */
                         goto errout;
                     reserved = true;
                 } else {
                     allocated = true;
                 }
             } else {
                 allocated = true;
             }
         }
     }
 
     ret = ext4_es_insert_delayed_block(inode, lblk, allocated);
     if (ret && reserved)
         ext4_da_release_space(inode, 1);
 
 errout:
     return ret;
 }
 
 /*
  * This function is grabs code from the very beginning of
  * ext4_map_blocks, but assumes that the caller is from delayed write
  * time. This function looks up the requested blocks and sets the
  * buffer delay bit under the protection of i_data_sem.
  */
 static int ext4_da_map_blocks(struct inode *inode, sector_t iblock,
                   struct ext4_map_blocks *map,
                   struct buffer_head *bh)
 {
     struct extent_status es;
     int retval;
     sector_t invalid_block = ~((sector_t) 0xffff);
 #ifdef ES_AGGRESSIVE_TEST
     struct ext4_map_blocks orig_map;
 
     memcpy(&orig_map, map, sizeof(*map));
 #endif
 
     if (invalid_block < ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es))
         invalid_block = ~0;
 
     map->m_flags = 0;
     ext_debug(inode, "max_blocks %u, logical block %lu\n", map->m_len,
           (unsigned long) map->m_lblk);
 
     /* Lookup extent status tree firstly */
     if (ext4_es_lookup_extent(inode, iblock, NULL, &es)) {
         if (ext4_es_is_hole(&es)) {
             retval = 0;
             down_read(&EXT4_I(inode)->i_data_sem);
             goto add_delayed;
         }
 
         /*
          * Delayed extent could be allocated by fallocate.
          * So we need to check it.
          */
         if (ext4_es_is_delayed(&es) && !ext4_es_is_unwritten(&es)) {
             map_bh(bh, inode->i_sb, invalid_block);
             set_buffer_new(bh);
             set_buffer_delay(bh);
             return 0;
         }
 
         map->m_pblk = ext4_es_pblock(&es) + iblock - es.es_lblk;
         retval = es.es_len - (iblock - es.es_lblk);
         if (retval > map->m_len)
             retval = map->m_len;
         map->m_len = retval;
         if (ext4_es_is_written(&es))
             map->m_flags |= EXT4_MAP_MAPPED;
         else if (ext4_es_is_unwritten(&es))
             map->m_flags |= EXT4_MAP_UNWRITTEN;
         else
             BUG();
 
 #ifdef ES_AGGRESSIVE_TEST
         ext4_map_blocks_es_recheck(NULL, inode, map, &orig_map, 0);
 #endif
         return retval;
     }
 
     /*
      * Try to see if we can get the block without requesting a new
      * file system block.
      */
     down_read(&EXT4_I(inode)->i_data_sem);
     if (ext4_has_inline_data(inode))
         retval = 0;
     else if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
         retval = ext4_ext_map_blocks(NULL, inode, map, 0);
     else
         retval = ext4_ind_map_blocks(NULL, inode, map, 0);
 
 add_delayed:
     if (retval == 0) {
         int ret;
 
         /*
          * XXX: __block_prepare_write() unmaps passed block,
          * is it OK?
          */
 
         ret = ext4_insert_delayed_block(inode, map->m_lblk);
         if (ret != 0) {
             retval = ret;
             goto out_unlock;
         }
 
         map_bh(bh, inode->i_sb, invalid_block);
         set_buffer_new(bh);
         set_buffer_delay(bh);
     } else if (retval > 0) {
         int ret;
         unsigned int status;
 
         if (unlikely(retval != map->m_len)) {
             ext4_warning(inode->i_sb,
                      "ES len assertion failed for inode "
                      "%lu: retval %d != map->m_len %d",
                      inode->i_ino, retval, map->m_len);
             WARN_ON(1);
         }
 
         status = map->m_flags & EXT4_MAP_UNWRITTEN ?
                 EXTENT_STATUS_UNWRITTEN : EXTENT_STATUS_WRITTEN;
         ret = ext4_es_insert_extent(inode, map->m_lblk, map->m_len,
                         map->m_pblk, status);
         if (ret != 0)
             retval = ret;
     }
 
 out_unlock:
     up_read((&EXT4_I(inode)->i_data_sem));
 
     return retval;
 }
 
 /*
  * This is a special get_block_t callback which is used by
  * ext4_da_write_begin().  It will either return mapped block or
  * reserve space for a single block.
  *
  * For delayed buffer_head we have BH_Mapped, BH_New, BH_Delay set.
  * We also have b_blocknr = -1 and b_bdev initialized properly
  *
  * For unwritten buffer_head we have BH_Mapped, BH_New, BH_Unwritten set.
  * We also have b_blocknr = physicalblock mapping unwritten extent and b_bdev
  * initialized properly.
  */
 int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,
                struct buffer_head *bh, int create)
 {
     struct ext4_map_blocks map;
     int ret = 0;
 
     BUG_ON(create == 0);
     BUG_ON(bh->b_size != inode->i_sb->s_blocksize);
 
     map.m_lblk = iblock;
     map.m_len = 1;
 
     /*
      * first, we need to know whether the block is allocated already
      * preallocated blocks are unmapped but should treated
      * the same as allocated blocks.
      */
     ret = ext4_da_map_blocks(inode, iblock, &map, bh);
     if (ret <= 0)
         return ret;
 
     map_bh(bh, inode->i_sb, map.m_pblk);
     ext4_update_bh_state(bh, map.m_flags);
 
     if (buffer_unwritten(bh)) {
         /* A delayed write to unwritten bh should be marked
          * new and mapped.  Mapped ensures that we don't do
          * get_block multiple times when we write to the same
          * offset and new ensures that we do proper zero out
          * for partial write.
          */
         set_buffer_new(bh);
         set_buffer_mapped(bh);
     }
     return 0;
 }
 
 static int __ext4_journalled_writepage(struct page *page,
                        unsigned int len)
 {
     struct address_space *mapping = page->mapping;
     struct inode *inode = mapping->host;
     handle_t *handle = NULL;
     int ret = 0, err = 0;
     int inline_data = ext4_has_inline_data(inode);
     struct buffer_head *inode_bh = NULL;
     loff_t size;
 
     ClearPageChecked(page);
 
     if (inline_data) {
         BUG_ON(page->index != 0);
         BUG_ON(len > ext4_get_max_inline_size(inode));
         inode_bh = ext4_journalled_write_inline_data(inode, len, page);
         if (inode_bh == NULL)
             goto out;
     }
     /*
      * We need to release the page lock before we start the
      * journal, so grab a reference so the page won't disappear
      * out from under us.
      */
     get_page(page);
     unlock_page(page);
 
     handle = ext4_journal_start(inode, EXT4_HT_WRITE_PAGE,
                     ext4_writepage_trans_blocks(inode));
     if (IS_ERR(handle)) {
         ret = PTR_ERR(handle);
         put_page(page);
         goto out_no_pagelock;
     }
     BUG_ON(!ext4_handle_valid(handle));
 
     lock_page(page);
     put_page(page);
     size = i_size_read(inode);
     if (page->mapping != mapping || page_offset(page) > size) {
         /* The page got truncated from under us */
         ext4_journal_stop(handle);
         ret = 0;
         goto out;
     }
 
     if (inline_data) {
         ret = ext4_mark_inode_dirty(handle, inode);
     } else {
         struct buffer_head *page_bufs = page_buffers(page);
 
         if (page->index == size >> PAGE_SHIFT)
             len = size & ~PAGE_MASK;
         else
             len = PAGE_SIZE;
 
         ret = ext4_walk_page_buffers(handle, inode, page_bufs, 0, len,
                          NULL, do_journal_get_write_access);
 
         err = ext4_walk_page_buffers(handle, inode, page_bufs, 0, len,
                          NULL, write_end_fn);
     }
     if (ret == 0)
         ret = err;
     err = ext4_jbd2_inode_add_write(handle, inode, page_offset(page), len);
     if (ret == 0)
         ret = err;
     EXT4_I(inode)->i_datasync_tid = handle->h_transaction->t_tid;
     err = ext4_journal_stop(handle);
     if (!ret)
         ret = err;
 
     ext4_set_inode_state(inode, EXT4_STATE_JDATA);
 out:
     unlock_page(page);
 out_no_pagelock:
     brelse(inode_bh);
     return ret;
 }
 
 /*
  * Note that we don't need to start a transaction unless we're journaling data
  * because we should have holes filled from ext4_page_mkwrite(). We even don't
  * need to file the inode to the transaction's list in ordered mode because if
  * we are writing back data added by write(), the inode is already there and if
  * we are writing back data modified via mmap(), no one guarantees in which
  * transaction the data will hit the disk. In case we are journaling data, we
  * cannot start transaction directly because transaction start ranks above page
  * lock so we have to do some magic.
  *
  * This function can get called via...
  *   - ext4_writepages after taking page lock (have journal handle)
  *   - journal_submit_inode_data_buffers (no journal handle)
  *   - shrink_page_list via the kswapd/direct reclaim (no journal handle)
  *   - grab_page_cache when doing write_begin (have journal handle)
  *
  * We don't do any block allocation in this function. If we have page with
  * multiple blocks we need to write those buffer_heads that are mapped. This
  * is important for mmaped based write. So if we do with blocksize 1K
  * truncate(f, 1024);
  * a = mmap(f, 0, 4096);
  * a[0] = 'a';
  * truncate(f, 4096);
  * we have in the page first buffer_head mapped via page_mkwrite call back
  * but other buffer_heads would be unmapped but dirty (dirty done via the
  * do_wp_page). So writepage should write the first block. If we modify
  * the mmap area beyond 1024 we will again get a page_fault and the
  * page_mkwrite callback will do the block allocation and mark the
  * buffer_heads mapped.
  *
  * We redirty the page if we have any buffer_heads that is either delay or
  * unwritten in the page.
  *
  * We can get recursively called as show below.
  *
  *  ext4_writepage() -> kmalloc() -> __alloc_pages() -> page_launder() ->
  *      ext4_writepage()
  *
  * But since we don't do any block allocation we should not deadlock.
  * Page also have the dirty flag cleared so we don't get recurive page_lock.
  */
 static int ext4_writepage(struct page *page,
               struct writeback_control *wbc)
 {
     struct folio *folio = page_folio(page);
     int ret = 0;
     loff_t size;
     unsigned int len;
     struct buffer_head *page_bufs = NULL;
     struct inode *inode = page->mapping->host;
     struct ext4_io_submit io_submit;
     bool keep_towrite = false;
 
     if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb)))) {
         folio_invalidate(folio, 0, folio_size(folio));
         folio_unlock(folio);
         return -EIO;
     }
 
     trace_ext4_writepage(page);
     size = i_size_read(inode);
     if (page->index == size >> PAGE_SHIFT &&
         !ext4_verity_in_progress(inode))
         len = size & ~PAGE_MASK;
     else
         len = PAGE_SIZE;
 
     /* Should never happen but for bugs in other kernel subsystems */
     if (!page_has_buffers(page)) {
         ext4_warning_inode(inode,
            "page %lu does not have buffers attached", page->index);
         ClearPageDirty(page);
         unlock_page(page);
         return 0;
     }
 
     page_bufs = page_buffers(page);
     /*
      * We cannot do block allocation or other extent handling in this
      * function. If there are buffers needing that, we have to redirty
      * the page. But we may reach here when we do a journal commit via
      * journal_submit_inode_data_buffers() and in that case we must write
      * allocated buffers to achieve data=ordered mode guarantees.
      *
      * Also, if there is only one buffer per page (the fs block
      * size == the page size), if one buffer needs block
      * allocation or needs to modify the extent tree to clear the
      * unwritten flag, we know that the page can't be written at
      * all, so we might as well refuse the write immediately.
      * Unfortunately if the block size != page size, we can't as
      * easily detect this case using ext4_walk_page_buffers(), but
      * for the extremely common case, this is an optimization that
      * skips a useless round trip through ext4_bio_write_page().
      */
     if (ext4_walk_page_buffers(NULL, inode, page_bufs, 0, len, NULL,
                    ext4_bh_delay_or_unwritten)) {
         redirty_page_for_writepage(wbc, page);
         if ((current->flags & PF_MEMALLOC) ||
             (inode->i_sb->s_blocksize == PAGE_SIZE)) {
             /*
              * For memory cleaning there's no point in writing only
              * some buffers. So just bail out. Warn if we came here
              * from direct reclaim.
              */
             WARN_ON_ONCE((current->flags & (PF_MEMALLOC|PF_KSWAPD))
                             == PF_MEMALLOC);
             unlock_page(page);
             return 0;
         }
         keep_towrite = true;
     }
 
     if (PageChecked(page) && ext4_should_journal_data(inode))
         /*
          * It's mmapped pagecache.  Add buffers and journal it.  There
          * doesn't seem much point in redirtying the page here.
          */
         return __ext4_journalled_writepage(page, len);
 
     ext4_io_submit_init(&io_submit, wbc);
     io_submit.io_end = ext4_init_io_end(inode, GFP_NOFS);
     if (!io_submit.io_end) {
         redirty_page_for_writepage(wbc, page);
         unlock_page(page);
         return -ENOMEM;
     }
     ret = ext4_bio_write_page(&io_submit, page, len, keep_towrite);
     ext4_io_submit(&io_submit);
     /* Drop io_end reference we got from init */
     ext4_put_io_end_defer(io_submit.io_end);
     return ret;
 }
 
 static int mpage_submit_page(struct mpage_da_data *mpd, struct page *page)
 {
     int len;
     loff_t size;
     int err;
 
     BUG_ON(page->index != mpd->first_page);
     clear_page_dirty_for_io(page);
     /*
      * We have to be very careful here!  Nothing protects writeback path
      * against i_size changes and the page can be writeably mapped into
      * page tables. So an application can be growing i_size and writing
      * data through mmap while writeback runs. clear_page_dirty_for_io()
      * write-protects our page in page tables and the page cannot get
      * written to again until we release page lock. So only after
      * clear_page_dirty_for_io() we are safe to sample i_size for
      * ext4_bio_write_page() to zero-out tail of the written page. We rely
      * on the barrier provided by TestClearPageDirty in
      * clear_page_dirty_for_io() to make sure i_size is really sampled only
      * after page tables are updated.
      */
     size = i_size_read(mpd->inode);
     if (page->index == size >> PAGE_SHIFT &&
         !ext4_verity_in_progress(mpd->inode))
         len = size & ~PAGE_MASK;
     else
         len = PAGE_SIZE;
     err = ext4_bio_write_page(&mpd->io_submit, page, len, false);
     if (!err)
         mpd->wbc->nr_to_write--;
     mpd->first_page++;
 
     return err;
 }
 
 #define BH_FLAGS (BIT(BH_Unwritten) | BIT(BH_Delay))
 
 /*
  * mballoc gives us at most this number of blocks...
  * XXX: That seems to be only a limitation of ext4_mb_normalize_request().
  * The rest of mballoc seems to handle chunks up to full group size.
  */
 #define MAX_WRITEPAGES_EXTENT_LEN 2048
 
 /*
  * mpage_add_bh_to_extent - try to add bh to extent of blocks to map
  *
  * @mpd - extent of blocks
  * @lblk - logical number of the block in the file
  * @bh - buffer head we want to add to the extent
  *
  * The function is used to collect contig. blocks in the same state. If the
  * buffer doesn't require mapping for writeback and we haven't started the
  * extent of buffers to map yet, the function returns 'true' immediately - the
  * caller can write the buffer right away. Otherwise the function returns true
  * if the block has been added to the extent, false if the block couldn't be
  * added.
  */
 static bool mpage_add_bh_to_extent(struct mpage_da_data *mpd, ext4_lblk_t lblk,
                    struct buffer_head *bh)
 {
     struct ext4_map_blocks *map = &mpd->map;
 
     /* Buffer that doesn't need mapping for writeback? */
     if (!buffer_dirty(bh) || !buffer_mapped(bh) ||
         (!buffer_delay(bh) && !buffer_unwritten(bh))) {
         /* So far no extent to map => we write the buffer right away */
         if (map->m_len == 0)
             return true;
         return false;
     }
 
     /* First block in the extent? */
     if (map->m_len == 0) {
         /* We cannot map unless handle is started... */
         if (!mpd->do_map)
             return false;
         map->m_lblk = lblk;
         map->m_len = 1;
         map->m_flags = bh->b_state & BH_FLAGS;
         return true;
     }
 
     /* Don't go larger than mballoc is willing to allocate */
     if (map->m_len >= MAX_WRITEPAGES_EXTENT_LEN)
         return false;
 
     /* Can we merge the block to our big extent? */
     if (lblk == map->m_lblk + map->m_len &&
         (bh->b_state & BH_FLAGS) == map->m_flags) {
         map->m_len++;
         return true;
     }
     return false;
 }
 
 /*
  * mpage_process_page_bufs - submit page buffers for IO or add them to extent
  *
  * @mpd - extent of blocks for mapping
  * @head - the first buffer in the page
  * @bh - buffer we should start processing from
  * @lblk - logical number of the block in the file corresponding to @bh
  *
  * Walk through page buffers from @bh upto @head (exclusive) and either submit
  * the page for IO if all buffers in this page were mapped and there's no
  * accumulated extent of buffers to map or add buffers in the page to the
  * extent of buffers to map. The function returns 1 if the caller can continue
  * by processing the next page, 0 if it should stop adding buffers to the
  * extent to map because we cannot extend it anymore. It can also return value
  * < 0 in case of error during IO submission.
  */
 static int mpage_process_page_bufs(struct mpage_da_data *mpd,
                    struct buffer_head *head,
                    struct buffer_head *bh,
                    ext4_lblk_t lblk)
 {
     struct inode *inode = mpd->inode;
     int err;
     ext4_lblk_t blocks = (i_size_read(inode) + i_blocksize(inode) - 1)
                             >> inode->i_blkbits;
 
     if (ext4_verity_in_progress(inode))
         blocks = EXT_MAX_BLOCKS;
 
     do {
         BUG_ON(buffer_locked(bh));
 
         if (lblk >= blocks || !mpage_add_bh_to_extent(mpd, lblk, bh)) {
             /* Found extent to map? */
             if (mpd->map.m_len)
                 return 0;
             /* Buffer needs mapping and handle is not started? */
             if (!mpd->do_map)
                 return 0;
             /* Everything mapped so far and we hit EOF */
             break;
         }
     } while (lblk++, (bh = bh->b_this_page) != head);
     /* So far everything mapped? Submit the page for IO. */
     if (mpd->map.m_len == 0) {
         err = mpage_submit_page(mpd, head->b_page);
         if (err < 0)
             return err;
     }
     if (lblk >= blocks) {
         mpd->scanned_until_end = 1;
         return 0;
     }
     return 1;
 }
 
 /*
  * mpage_process_page - update page buffers corresponding to changed extent and
  *             may submit fully mapped page for IO
  *
  * @mpd     - description of extent to map, on return next extent to map
  * @m_lblk  - logical block mapping.
  * @m_pblk  - corresponding physical mapping.
  * @map_bh  - determines on return whether this page requires any further
  *        mapping or not.
  * Scan given page buffers corresponding to changed extent and update buffer
  * state according to new extent state.
  * We map delalloc buffers to their physical location, clear unwritten bits.
  * If the given page is not fully mapped, we update @map to the next extent in
  * the given page that needs mapping & return @map_bh as true.
  */
 static int mpage_process_page(struct mpage_da_data *mpd, struct page *page,
                   ext4_lblk_t *m_lblk, ext4_fsblk_t *m_pblk,
                   bool *map_bh)
 {
     struct buffer_head *head, *bh;
     ext4_io_end_t *io_end = mpd->io_submit.io_end;
     ext4_lblk_t lblk = *m_lblk;
     ext4_fsblk_t pblock = *m_pblk;
     int err = 0;
     int blkbits = mpd->inode->i_blkbits;
     ssize_t io_end_size = 0;
     struct ext4_io_end_vec *io_end_vec = ext4_last_io_end_vec(io_end);
 
     bh = head = page_buffers(page);
     do {
         if (lblk < mpd->map.m_lblk)
             continue;
         if (lblk >= mpd->map.m_lblk + mpd->map.m_len) {
             /*
              * Buffer after end of mapped extent.
              * Find next buffer in the page to map.
              */
             mpd->map.m_len = 0;
             mpd->map.m_flags = 0;
             io_end_vec->size += io_end_size;
 
             err = mpage_process_page_bufs(mpd, head, bh, lblk);
             if (err > 0)
                 err = 0;
             if (!err && mpd->map.m_len && mpd->map.m_lblk > lblk) {
                 io_end_vec = ext4_alloc_io_end_vec(io_end);
                 if (IS_ERR(io_end_vec)) {
                     err = PTR_ERR(io_end_vec);
                     goto out;
                 }
                 io_end_vec->offset = (loff_t)mpd->map.m_lblk << blkbits;
             }
             *map_bh = true;
             goto out;
         }
         if (buffer_delay(bh)) {
             clear_buffer_delay(bh);
             bh->b_blocknr = pblock++;
         }
         clear_buffer_unwritten(bh);
         io_end_size += (1 << blkbits);
     } while (lblk++, (bh = bh->b_this_page) != head);
 
     io_end_vec->size += io_end_size;
     *map_bh = false;
 out:
     *m_lblk = lblk;
     *m_pblk = pblock;
     return err;
 }
 
 /*
  * mpage_map_buffers - update buffers corresponding to changed extent and
  *             submit fully mapped pages for IO
  *
  * @mpd - description of extent to map, on return next extent to map
  *
  * Scan buffers corresponding to changed extent (we expect corresponding pages
  * to be already locked) and update buffer state according to new extent state.
  * We map delalloc buffers to their physical location, clear unwritten bits,
  * and mark buffers as uninit when we perform writes to unwritten extents
  * and do extent conversion after IO is finished. If the last page is not fully
  * mapped, we update @map to the next extent in the last page that needs
  * mapping. Otherwise we submit the page for IO.
  */
 static int mpage_map_and_submit_buffers(struct mpage_da_data *mpd)
 {
     struct folio_batch fbatch;
     unsigned nr, i;
     struct inode *inode = mpd->inode;
     int bpp_bits = PAGE_SHIFT - inode->i_blkbits;
     pgoff_t start, end;
     ext4_lblk_t lblk;
     ext4_fsblk_t pblock;
     int err;
     bool map_bh = false;
 
     start = mpd->map.m_lblk >> bpp_bits;
     end = (mpd->map.m_lblk + mpd->map.m_len - 1) >> bpp_bits;
     lblk = start << bpp_bits;
     pblock = mpd->map.m_pblk;
 
     folio_batch_init(&fbatch);
     while (start <= end) {
         nr = filemap_get_folios(inode->i_mapping, &start, end, &fbatch);
         if (nr == 0)
             break;
         for (i = 0; i < nr; i++) {
             struct page *page = &fbatch.folios[i]->page;
 
             err = mpage_process_page(mpd, page, &lblk, &pblock,
                          &map_bh);
             /*
              * If map_bh is true, means page may require further bh
              * mapping, or maybe the page was submitted for IO.
              * So we return to call further extent mapping.
              */
             if (err < 0 || map_bh)
                 goto out;
             /* Page fully mapped - let IO run! */
             err = mpage_submit_page(mpd, page);
             if (err < 0)
                 goto out;
         }
         folio_batch_release(&fbatch);
     }
     /* Extent fully mapped and matches with page boundary. We are done. */
     mpd->map.m_len = 0;
     mpd->map.m_flags = 0;
     return 0;
 out:
     folio_batch_release(&fbatch);
     return err;
 }
 
 static int mpage_map_one_extent(handle_t *handle, struct mpage_da_data *mpd)
 {
     struct inode *inode = mpd->inode;
     struct ext4_map_blocks *map = &mpd->map;
     int get_blocks_flags;
     int err, dioread_nolock;
 
     trace_ext4_da_write_pages_extent(inode, map);
     /*
      * Call ext4_map_blocks() to allocate any delayed allocation blocks, or
      * to convert an unwritten extent to be initialized (in the case
      * where we have written into one or more preallocated blocks).  It is
      * possible that we're going to need more metadata blocks than
      * previously reserved. However we must not fail because we're in
      * writeback and there is nothing we can do about it so it might result
      * in data loss.  So use reserved blocks to allocate metadata if
      * possible.
      *
      * We pass in the magic EXT4_GET_BLOCKS_DELALLOC_RESERVE if
      * the blocks in question are delalloc blocks.  This indicates
      * that the blocks and quotas has already been checked when
      * the data was copied into the page cache.
      */
     get_blocks_flags = EXT4_GET_BLOCKS_CREATE |
                EXT4_GET_BLOCKS_METADATA_NOFAIL |
                EXT4_GET_BLOCKS_IO_SUBMIT;
     dioread_nolock = ext4_should_dioread_nolock(inode);
     if (dioread_nolock)
         get_blocks_flags |= EXT4_GET_BLOCKS_IO_CREATE_EXT;
     if (map->m_flags & BIT(BH_Delay))
         get_blocks_flags |= EXT4_GET_BLOCKS_DELALLOC_RESERVE;
 
     err = ext4_map_blocks(handle, inode, map, get_blocks_flags);
     if (err < 0)
         return err;
     if (dioread_nolock && (map->m_flags & EXT4_MAP_UNWRITTEN)) {
         if (!mpd->io_submit.io_end->handle &&
             ext4_handle_valid(handle)) {
             mpd->io_submit.io_end->handle = handle->h_rsv_handle;
             handle->h_rsv_handle = NULL;
         }
         ext4_set_io_unwritten_flag(inode, mpd->io_submit.io_end);
     }
 
     BUG_ON(map->m_len == 0);
     return 0;
 }
 
 /*
  * mpage_map_and_submit_extent - map extent starting at mpd->lblk of length
  *               mpd->len and submit pages underlying it for IO
  *
  * @handle - handle for journal operations
  * @mpd - extent to map
  * @give_up_on_write - we set this to true iff there is a fatal error and there
  *                     is no hope of writing the data. The caller should discard
  *                     dirty pages to avoid infinite loops.
  *
  * The function maps extent starting at mpd->lblk of length mpd->len. If it is
  * delayed, blocks are allocated, if it is unwritten, we may need to convert
  * them to initialized or split the described range from larger unwritten
  * extent. Note that we need not map all the described range since allocation
  * can return less blocks or the range is covered by more unwritten extents. We
  * cannot map more because we are limited by reserved transaction credits. On
  * the other hand we always make sure that the last touched page is fully
  * mapped so that it can be written out (and thus forward progress is
  * guaranteed). After mapping we submit all mapped pages for IO.
  */
 static int mpage_map_and_submit_extent(handle_t *handle,
                        struct mpage_da_data *mpd,
                        bool *give_up_on_write)
 {
     struct inode *inode = mpd->inode;
     struct ext4_map_blocks *map = &mpd->map;
     int err;
     loff_t disksize;
     int progress = 0;
     ext4_io_end_t *io_end = mpd->io_submit.io_end;
     struct ext4_io_end_vec *io_end_vec;
 
     io_end_vec = ext4_alloc_io_end_vec(io_end);
     if (IS_ERR(io_end_vec))
         return PTR_ERR(io_end_vec);
     io_end_vec->offset = ((loff_t)map->m_lblk) << inode->i_blkbits;
     do {
         err = mpage_map_one_extent(handle, mpd);
         if (err < 0) {
             struct super_block *sb = inode->i_sb;
 
             if (ext4_forced_shutdown(EXT4_SB(sb)) ||
                 ext4_test_mount_flag(sb, EXT4_MF_FS_ABORTED))
                 goto invalidate_dirty_pages;
             /*
              * Let the uper layers retry transient errors.
              * In the case of ENOSPC, if ext4_count_free_blocks()
              * is non-zero, a commit should free up blocks.
              */
             if ((err == -ENOMEM) ||
                 (err == -ENOSPC && ext4_count_free_clusters(sb))) {
                 if (progress)
                     goto update_disksize;
                 return err;
             }
             ext4_msg(sb, KERN_CRIT,
                  "Delayed block allocation failed for "
                  "inode %lu at logical offset %llu with"
                  " max blocks %u with error %d",
                  inode->i_ino,
                  (unsigned long long)map->m_lblk,
                  (unsigned)map->m_len, -err);
             ext4_msg(sb, KERN_CRIT,
                  "This should not happen!! Data will "
                  "be lost\n");
             if (err == -ENOSPC)
                 ext4_print_free_blocks(inode);
         invalidate_dirty_pages:
             *give_up_on_write = true;
             return err;
         }
         progress = 1;
         /*
          * Update buffer state, submit mapped pages, and get us new
          * extent to map
          */
         err = mpage_map_and_submit_buffers(mpd);
         if (err < 0)
             goto update_disksize;
     } while (map->m_len);
 
 update_disksize:
     /*
      * Update on-disk size after IO is submitted.  Races with
      * truncate are avoided by checking i_size under i_data_sem.
      */
     disksize = ((loff_t)mpd->first_page) << PAGE_SHIFT;
     if (disksize > READ_ONCE(EXT4_I(inode)->i_disksize)) {
         int err2;
         loff_t i_size;
 
         down_write(&EXT4_I(inode)->i_data_sem);
         i_size = i_size_read(inode);
         if (disksize > i_size)
             disksize = i_size;
         if (disksize > EXT4_I(inode)->i_disksize)
             EXT4_I(inode)->i_disksize = disksize;
         up_write(&EXT4_I(inode)->i_data_sem);
         err2 = ext4_mark_inode_dirty(handle, inode);
         if (err2) {
             ext4_error_err(inode->i_sb, -err2,
                        "Failed to mark inode %lu dirty",
                        inode->i_ino);
         }
         if (!err)
             err = err2;
     }
     return err;
 }
 
 /*
  * Calculate the total number of credits to reserve for one writepages
  * iteration. This is called from ext4_writepages(). We map an extent of
  * up to MAX_WRITEPAGES_EXTENT_LEN blocks and then we go on and finish mapping
  * the last partial page. So in total we can map MAX_WRITEPAGES_EXTENT_LEN +
  * bpp - 1 blocks in bpp different extents.
  */
 static int ext4_da_writepages_trans_blocks(struct inode *inode)
 {
     int bpp = ext4_journal_blocks_per_page(inode);
 
     return ext4_meta_trans_blocks(inode,
                 MAX_WRITEPAGES_EXTENT_LEN + bpp - 1, bpp);
 }
 
 /*
  * mpage_prepare_extent_to_map - find & lock contiguous range of dirty pages
  *               and underlying extent to map
  *
  * @mpd - where to look for pages
  *
  * Walk dirty pages in the mapping. If they are fully mapped, submit them for
  * IO immediately. When we find a page which isn't mapped we start accumulating
  * extent of buffers underlying these pages that needs mapping (formed by
  * either delayed or unwritten buffers). We also lock the pages containing
  * these buffers. The extent found is returned in @mpd structure (starting at
  * mpd->lblk with length mpd->len blocks).
  *
  * Note that this function can attach bios to one io_end structure which are
  * neither logically nor physically contiguous. Although it may seem as an
  * unnecessary complication, it is actually inevitable in blocksize < pagesize
  * case as we need to track IO to all buffers underlying a page in one io_end.
  */
 static int mpage_prepare_extent_to_map(struct mpage_da_data *mpd)
 {
     struct address_space *mapping = mpd->inode->i_mapping;
     struct pagevec pvec;
     unsigned int nr_pages;
     long left = mpd->wbc->nr_to_write;
     pgoff_t index = mpd->first_page;
     pgoff_t end = mpd->last_page;
     xa_mark_t tag;
     int i, err = 0;
     int blkbits = mpd->inode->i_blkbits;
     ext4_lblk_t lblk;
     struct buffer_head *head;
 
     if (mpd->wbc->sync_mode == WB_SYNC_ALL || mpd->wbc->tagged_writepages)
         tag = PAGECACHE_TAG_TOWRITE;
     else
         tag = PAGECACHE_TAG_DIRTY;
 
     pagevec_init(&pvec);
     mpd->map.m_len = 0;
     mpd->next_page = index;
     while (index <= end) {
         nr_pages = pagevec_lookup_range_tag(&pvec, mapping, &index, end,
                 tag);
         if (nr_pages == 0)
             break;
 
         for (i = 0; i < nr_pages; i++) {
             struct page *page = pvec.pages[i];
 
             /*
              * Accumulated enough dirty pages? This doesn't apply
              * to WB_SYNC_ALL mode. For integrity sync we have to
              * keep going because someone may be concurrently
              * dirtying pages, and we might have synced a lot of
              * newly appeared dirty pages, but have not synced all
              * of the old dirty pages.
              */
             if (mpd->wbc->sync_mode == WB_SYNC_NONE && left <= 0)
                 goto out;
 
             /* If we can't merge this page, we are done. */
             if (mpd->map.m_len > 0 && mpd->next_page != page->index)
                 goto out;
 
             lock_page(page);
             /*
              * If the page is no longer dirty, or its mapping no
              * longer corresponds to inode we are writing (which
              * means it has been truncated or invalidated), or the
              * page is already under writeback and we are not doing
              * a data integrity writeback, skip the page
              */
             if (!PageDirty(page) ||
                 (PageWriteback(page) &&
                  (mpd->wbc->sync_mode == WB_SYNC_NONE)) ||
                 unlikely(page->mapping != mapping)) {
                 unlock_page(page);
                 continue;
             }
 
             wait_on_page_writeback(page);
             BUG_ON(PageWriteback(page));
 
             /*
              * Should never happen but for buggy code in
              * other subsystems that call
              * set_page_dirty() without properly warning
              * the file system first.  See [1] for more
              * information.
              *
              * [1] https://lore.kernel.org/linux-mm/20180103100430.GE4911@quack2.suse.cz
              */
             if (!page_has_buffers(page)) {
                 ext4_warning_inode(mpd->inode, "page %lu does not have buffers attached", page->index);
                 ClearPageDirty(page);
                 unlock_page(page);
                 continue;
             }
 
             if (mpd->map.m_len == 0)
                 mpd->first_page = page->index;
             mpd->next_page = page->index + 1;
             /* Add all dirty buffers to mpd */
             lblk = ((ext4_lblk_t)page->index) <<
                 (PAGE_SHIFT - blkbits);
             head = page_buffers(page);
             err = mpage_process_page_bufs(mpd, head, head, lblk);
             if (err <= 0)
                 goto out;
             err = 0;
             left--;
         }
         pagevec_release(&pvec);
         cond_resched();
     }
     mpd->scanned_until_end = 1;
     return 0;
 out:
     pagevec_release(&pvec);
     return err;
 }
 
 static int ext4_writepages(struct address_space *mapping,
                struct writeback_control *wbc)
 {
     pgoff_t writeback_index = 0;
     long nr_to_write = wbc->nr_to_write;
     int range_whole = 0;
     int cycled = 1;
     handle_t *handle = NULL;
     struct mpage_da_data mpd;
     struct inode *inode = mapping->host;
     int needed_blocks, rsv_blocks = 0, ret = 0;
     struct ext4_sb_info *sbi = EXT4_SB(mapping->host->i_sb);
     struct blk_plug plug;
     bool give_up_on_write = false;
 
     if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
         return -EIO;
 
     percpu_down_read(&sbi->s_writepages_rwsem);
     trace_ext4_writepages(inode, wbc);
 
     /*
      * No pages to write? This is mainly a kludge to avoid starting
      * a transaction for special inodes like journal inode on last iput()
      * because that could violate lock ordering on umount
      */
     if (!mapping->nrpages || !mapping_tagged(mapping, PAGECACHE_TAG_DIRTY))
         goto out_writepages;
 
     if (ext4_should_journal_data(inode)) {
         ret = generic_writepages(mapping, wbc);
         goto out_writepages;
     }
 
     /*
      * If the filesystem has aborted, it is read-only, so return
      * right away instead of dumping stack traces later on that
      * will obscure the real source of the problem.  We test
      * EXT4_MF_FS_ABORTED instead of sb->s_flag's SB_RDONLY because
      * the latter could be true if the filesystem is mounted
      * read-only, and in that case, ext4_writepages should
      * *never* be called, so if that ever happens, we would want
      * the stack trace.
      */
     if (unlikely(ext4_forced_shutdown(EXT4_SB(mapping->host->i_sb)) ||
              ext4_test_mount_flag(inode->i_sb, EXT4_MF_FS_ABORTED))) {
         ret = -EROFS;
         goto out_writepages;
     }
 
     /*
      * If we have inline data and arrive here, it means that
      * we will soon create the block for the 1st page, so
      * we'd better clear the inline data here.
      */
     if (ext4_has_inline_data(inode)) {
         /* Just inode will be modified... */
         handle = ext4_journal_start(inode, EXT4_HT_INODE, 1);
         if (IS_ERR(handle)) {
             ret = PTR_ERR(handle);
             goto out_writepages;
         }
         BUG_ON(ext4_test_inode_state(inode,
                 EXT4_STATE_MAY_INLINE_DATA));
         ext4_destroy_inline_data(handle, inode);
         ext4_journal_stop(handle);
     }
 
     if (ext4_should_dioread_nolock(inode)) {
         /*
          * We may need to convert up to one extent per block in
          * the page and we may dirty the inode.
          */
         rsv_blocks = 1 + ext4_chunk_trans_blocks(inode,
                         PAGE_SIZE >> inode->i_blkbits);
     }
 
     if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
         range_whole = 1;
 
     if (wbc->range_cyclic) {
         writeback_index = mapping->writeback_index;
         if (writeback_index)
             cycled = 0;
         mpd.first_page = writeback_index;
         mpd.last_page = -1;
     } else {
         mpd.first_page = wbc->range_start >> PAGE_SHIFT;
         mpd.last_page = wbc->range_end >> PAGE_SHIFT;
     }
 
     mpd.inode = inode;
     mpd.wbc = wbc;
     ext4_io_submit_init(&mpd.io_submit, wbc);
 retry:
     if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
         tag_pages_for_writeback(mapping, mpd.first_page, mpd.last_page);
     blk_start_plug(&plug);
 
     /*
      * First writeback pages that don't need mapping - we can avoid
      * starting a transaction unnecessarily and also avoid being blocked
      * in the block layer on device congestion while having transaction
      * started.
      */
     mpd.do_map = 0;
     mpd.scanned_until_end = 0;
     mpd.io_submit.io_end = ext4_init_io_end(inode, GFP_KERNEL);
     if (!mpd.io_submit.io_end) {
         ret = -ENOMEM;
         goto unplug;
     }
     ret = mpage_prepare_extent_to_map(&mpd);
     /* Unlock pages we didn't use */
     mpage_release_unused_pages(&mpd, false);
     /* Submit prepared bio */
     ext4_io_submit(&mpd.io_submit);
     ext4_put_io_end_defer(mpd.io_submit.io_end);
     mpd.io_submit.io_end = NULL;
     if (ret < 0)
         goto unplug;
 
     while (!mpd.scanned_until_end && wbc->nr_to_write > 0) {
         /* For each extent of pages we use new io_end */
         mpd.io_submit.io_end = ext4_init_io_end(inode, GFP_KERNEL);
         if (!mpd.io_submit.io_end) {
             ret = -ENOMEM;
             break;
         }
 
         /*
          * We have two constraints: We find one extent to map and we
          * must always write out whole page (makes a difference when
          * blocksize < pagesize) so that we don't block on IO when we
          * try to write out the rest of the page. Journalled mode is
          * not supported by delalloc.
          */
         BUG_ON(ext4_should_journal_data(inode));
         needed_blocks = ext4_da_writepages_trans_blocks(inode);
 
         /* start a new transaction */
         handle = ext4_journal_start_with_reserve(inode,
                 EXT4_HT_WRITE_PAGE, needed_blocks, rsv_blocks);
         if (IS_ERR(handle)) {
             ret = PTR_ERR(handle);
             ext4_msg(inode->i_sb, KERN_CRIT, "%s: jbd2_start: "
                    "%ld pages, ino %lu; err %d", __func__,
                 wbc->nr_to_write, inode->i_ino, ret);
             /* Release allocated io_end */
             ext4_put_io_end(mpd.io_submit.io_end);
             mpd.io_submit.io_end = NULL;
             break;
         }
         mpd.do_map = 1;
 
         trace_ext4_da_write_pages(inode, mpd.first_page, mpd.wbc);
         ret = mpage_prepare_extent_to_map(&mpd);
         if (!ret && mpd.map.m_len)
             ret = mpage_map_and_submit_extent(handle, &mpd,
                     &give_up_on_write);
         /*
          * Caution: If the handle is synchronous,
          * ext4_journal_stop() can wait for transaction commit
          * to finish which may depend on writeback of pages to
          * complete or on page lock to be released.  In that
          * case, we have to wait until after we have
          * submitted all the IO, released page locks we hold,
          * and dropped io_end reference (for extent conversion
          * to be able to complete) before stopping the handle.
          */
         if (!ext4_handle_valid(handle) || handle->h_sync == 0) {
             ext4_journal_stop(handle);
             handle = NULL;
             mpd.do_map = 0;
         }
         /* Unlock pages we didn't use */
         mpage_release_unused_pages(&mpd, give_up_on_write);
         /* Submit prepared bio */
         ext4_io_submit(&mpd.io_submit);
 
         /*
          * Drop our io_end reference we got from init. We have
          * to be careful and use deferred io_end finishing if
          * we are still holding the transaction as we can
          * release the last reference to io_end which may end
          * up doing unwritten extent conversion.
          */
         if (handle) {
             ext4_put_io_end_defer(mpd.io_submit.io_end);
             ext4_journal_stop(handle);
         } else
             ext4_put_io_end(mpd.io_submit.io_end);
         mpd.io_submit.io_end = NULL;
 
         if (ret == -ENOSPC && sbi->s_journal) {
             /*
              * Commit the transaction which would
              * free blocks released in the transaction
              * and try again
              */
             jbd2_journal_force_commit_nested(sbi->s_journal);
             ret = 0;
             continue;
         }
         /* Fatal error - ENOMEM, EIO... */
         if (ret)
             break;
     }
 unplug:
     blk_finish_plug(&plug);
     if (!ret && !cycled && wbc->nr_to_write > 0) {
         cycled = 1;
         mpd.last_page = writeback_index - 1;
         mpd.first_page = 0;
         goto retry;
     }
 
     /* Update index */
     if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
         /*
          * Set the writeback_index so that range_cyclic
          * mode will write it back later
          */
         mapping->writeback_index = mpd.first_page;
 
 out_writepages:
     trace_ext4_writepages_result(inode, wbc, ret,
                      nr_to_write - wbc->nr_to_write);
     percpu_up_read(&sbi->s_writepages_rwsem);
     return ret;
 }
 
 static int ext4_dax_writepages(struct address_space *mapping,
                    struct writeback_control *wbc)
 {
     int ret;
     long nr_to_write = wbc->nr_to_write;
     struct inode *inode = mapping->host;
     struct ext4_sb_info *sbi = EXT4_SB(mapping->host->i_sb);
 
     if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
         return -EIO;
 
     percpu_down_read(&sbi->s_writepages_rwsem);
     trace_ext4_writepages(inode, wbc);
 
     ret = dax_writeback_mapping_range(mapping, sbi->s_daxdev, wbc);
     trace_ext4_writepages_result(inode, wbc, ret,
                      nr_to_write - wbc->nr_to_write);
     percpu_up_read(&sbi->s_writepages_rwsem);
     return ret;
 }
 
 static int ext4_nonda_switch(struct super_block *sb)
 {
     s64 free_clusters, dirty_clusters;
     struct ext4_sb_info *sbi = EXT4_SB(sb);
 
     /*
      * switch to non delalloc mode if we are running low
      * on free block. The free block accounting via percpu
      * counters can get slightly wrong with percpu_counter_batch getting
      * accumulated on each CPU without updating global counters
      * Delalloc need an accurate free block accounting. So switch
      * to non delalloc when we are near to error range.
      */
     free_clusters =
         percpu_counter_read_positive(&sbi->s_freeclusters_counter);
     dirty_clusters =
         percpu_counter_read_positive(&sbi->s_dirtyclusters_counter);
     /*
      * Start pushing delalloc when 1/2 of free blocks are dirty.
      */
     if (dirty_clusters && (free_clusters < 2 * dirty_clusters))
         try_to_writeback_inodes_sb(sb, WB_REASON_FS_FREE_SPACE);
 
     if (2 * free_clusters < 3 * dirty_clusters ||
         free_clusters < (dirty_clusters + EXT4_FREECLUSTERS_WATERMARK)) {
         /*
          * free block count is less than 150% of dirty blocks
          * or free blocks is less than watermark
          */
         return 1;
     }
     return 0;
 }
 
 static int ext4_da_write_begin(struct file *file, struct address_space *mapping,
                    loff_t pos, unsigned len,
                    struct page **pagep, void **fsdata)
 {
     int ret, retries = 0;
     struct page *page;
     pgoff_t index;
     struct inode *inode = mapping->host;
 
     if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
         return -EIO;
 
     index = pos >> PAGE_SHIFT;
 
     if (ext4_nonda_switch(inode->i_sb) || ext4_verity_in_progress(inode)) {
         *fsdata = (void *)FALL_BACK_TO_NONDELALLOC;
         return ext4_write_begin(file, mapping, pos,
                     len, pagep, fsdata);
     }
     *fsdata = (void *)0;
     trace_ext4_da_write_begin(inode, pos, len);
 
     if (ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA)) {
         ret = ext4_da_write_inline_data_begin(mapping, inode, pos, len,
                               pagep, fsdata);
         if (ret < 0)
             return ret;
         if (ret == 1)
             return 0;
     }
 
 retry:
     page = grab_cache_page_write_begin(mapping, index);
     if (!page)
         return -ENOMEM;
 
     /* In case writeback began while the page was unlocked */
     wait_for_stable_page(page);
 
 #ifdef CONFIG_FS_ENCRYPTION
     ret = ext4_block_write_begin(page, pos, len,
                      ext4_da_get_block_prep);
 #else
     ret = __block_write_begin(page, pos, len, ext4_da_get_block_prep);
 #endif
     if (ret < 0) {
         unlock_page(page);
         put_page(page);
         /*
          * block_write_begin may have instantiated a few blocks
          * outside i_size.  Trim these off again. Don't need
          * i_size_read because we hold inode lock.
          */
         if (pos + len > inode->i_size)
             ext4_truncate_failed_write(inode);
 
         if (ret == -ENOSPC &&
             ext4_should_retry_alloc(inode->i_sb, &retries))
             goto retry;
         return ret;
     }
 
     *pagep = page;
     return ret;
 }
 
 /*
  * Check if we should update i_disksize
  * when write to the end of file but not require block allocation
  */
 static int ext4_da_should_update_i_disksize(struct page *page,
                         unsigned long offset)
 {
     struct buffer_head *bh;
     struct inode *inode = page->mapping->host;
     unsigned int idx;
     int i;
 
     bh = page_buffers(page);
     idx = offset >> inode->i_blkbits;
 
     for (i = 0; i < idx; i++)
         bh = bh->b_this_page;
 
     if (!buffer_mapped(bh) || (buffer_delay(bh)) || buffer_unwritten(bh))
         return 0;
     return 1;
 }
 
 static int ext4_da_write_end(struct file *file,
                  struct address_space *mapping,
                  loff_t pos, unsigned len, unsigned copied,
                  struct page *page, void *fsdata)
 {
     struct inode *inode = mapping->host;
     loff_t new_i_size;
     unsigned long start, end;
     int write_mode = (int)(unsigned long)fsdata;
 
     if (write_mode == FALL_BACK_TO_NONDELALLOC)
         return ext4_write_end(file, mapping, pos,
                       len, copied, page, fsdata);
 
     trace_ext4_da_write_end(inode, pos, len, copied);
 
     if (write_mode != CONVERT_INLINE_DATA &&
         ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA) &&
         ext4_has_inline_data(inode))
         return ext4_write_inline_data_end(inode, pos, len, copied, page);
 
     start = pos & (PAGE_SIZE - 1);
     end = start + copied - 1;
 
     /*
      * Since we are holding inode lock, we are sure i_disksize <=
      * i_size. We also know that if i_disksize < i_size, there are
      * delalloc writes pending in the range upto i_size. If the end of
      * the current write is <= i_size, there's no need to touch
      * i_disksize since writeback will push i_disksize upto i_size
      * eventually. If the end of the current write is > i_size and
      * inside an allocated block (ext4_da_should_update_i_disksize()
      * check), we need to update i_disksize here as neither
      * ext4_writepage() nor certain ext4_writepages() paths not
      * allocating blocks update i_disksize.
      *
      * Note that we defer inode dirtying to generic_write_end() /
      * ext4_da_write_inline_data_end().
      */
     new_i_size = pos + copied;
     if (copied && new_i_size > inode->i_size &&
         ext4_da_should_update_i_disksize(page, end))
         ext4_update_i_disksize(inode, new_i_size);
 
     return generic_write_end(file, mapping, pos, len, copied, page, fsdata);
 }
 
 /*
  * Force all delayed allocation blocks to be allocated for a given inode.
  */
 int ext4_alloc_da_blocks(struct inode *inode)
 {
     trace_ext4_alloc_da_blocks(inode);
 
     if (!EXT4_I(inode)->i_reserved_data_blocks)
         return 0;
 
     /*
      * We do something simple for now.  The filemap_flush() will
      * also start triggering a write of the data blocks, which is
      * not strictly speaking necessary (and for users of
      * laptop_mode, not even desirable).  However, to do otherwise
      * would require replicating code paths in:
      *
      * ext4_writepages() ->
      *    write_cache_pages() ---> (via passed in callback function)
      *        __mpage_da_writepage() -->
      *           mpage_add_bh_to_extent()
      *           mpage_da_map_blocks()
      *
      * The problem is that write_cache_pages(), located in
      * mm/page-writeback.c, marks pages clean in preparation for
      * doing I/O, which is not desirable if we're not planning on
      * doing I/O at all.
      *
      * We could call write_cache_pages(), and then redirty all of
      * the pages by calling redirty_page_for_writepage() but that
      * would be ugly in the extreme.  So instead we would need to
      * replicate parts of the code in the above functions,
      * simplifying them because we wouldn't actually intend to
      * write out the pages, but rather only collect contiguous
      * logical block extents, call the multi-block allocator, and
      * then update the buffer heads with the block allocations.
      *
      * For now, though, we'll cheat by calling filemap_flush(),
      * which will map the blocks, and start the I/O, but not
      * actually wait for the I/O to complete.
      */
     return filemap_flush(inode->i_mapping);
 }
 
 /*
  * bmap() is special.  It gets used by applications such as lilo and by
  * the swapper to find the on-disk block of a specific piece of data.
  *
  * Naturally, this is dangerous if the block concerned is still in the
  * journal.  If somebody makes a swapfile on an ext4 data-journaling
  * filesystem and enables swap, then they may get a nasty shock when the
  * data getting swapped to that swapfile suddenly gets overwritten by
  * the original zero's written out previously to the journal and
  * awaiting writeback in the kernel's buffer cache.
  *
  * So, if we see any bmap calls here on a modified, data-journaled file,
  * take extra steps to flush any blocks which might be in the cache.
  */
 static sector_t ext4_bmap(struct address_space *mapping, sector_t block)
 {
     struct inode *inode = mapping->host;
     journal_t *journal;
     sector_t ret = 0;
     int err;
 
     inode_lock_shared(inode);
     /*
      * We can get here for an inline file via the FIBMAP ioctl
      */
     if (ext4_has_inline_data(inode))
         goto out;
 
     if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY) &&
             test_opt(inode->i_sb, DELALLOC)) {
         /*
          * With delalloc we want to sync the file
          * so that we can make sure we allocate
          * blocks for file
          */
         filemap_write_and_wait(mapping);
     }
 
     if (EXT4_JOURNAL(inode) &&
         ext4_test_inode_state(inode, EXT4_STATE_JDATA)) {
         /*
          * This is a REALLY heavyweight approach, but the use of
          * bmap on dirty files is expected to be extremely rare:
          * only if we run lilo or swapon on a freshly made file
          * do we expect this to happen.
          *
          * (bmap requires CAP_SYS_RAWIO so this does not
          * represent an unprivileged user DOS attack --- we'd be
          * in trouble if mortal users could trigger this path at
          * will.)
          *
          * NB. EXT4_STATE_JDATA is not set on files other than
          * regular files.  If somebody wants to bmap a directory
          * or symlink and gets confused because the buffer
          * hasn't yet been flushed to disk, they deserve
          * everything they get.
          */
 
         ext4_clear_inode_state(inode, EXT4_STATE_JDATA);
         journal = EXT4_JOURNAL(inode);
         jbd2_journal_lock_updates(journal);
         err = jbd2_journal_flush(journal, 0);
         jbd2_journal_unlock_updates(journal);
 
         if (err)
             goto out;
     }
 
     ret = iomap_bmap(mapping, block, &ext4_iomap_ops);
 
 out:
     inode_unlock_shared(inode);
     return ret;
 }
 
 static int ext4_read_folio(struct file *file, struct folio *folio)
 {
     struct page *page = &folio->page;
     int ret = -EAGAIN;
     struct inode *inode = page->mapping->host;
 
     trace_ext4_readpage(page);
 
     if (ext4_has_inline_data(inode))
         ret = ext4_readpage_inline(inode, page);
 
     if (ret == -EAGAIN)
         return ext4_mpage_readpages(inode, NULL, page);
 
     return ret;
 }
 
 static void ext4_readahead(struct readahead_control *rac)
 {
     struct inode *inode = rac->mapping->host;
 
     /* If the file has inline data, no need to do readahead. */
     if (ext4_has_inline_data(inode))
         return;
 
     ext4_mpage_readpages(inode, rac, NULL);
 }
 
 static void ext4_invalidate_folio(struct folio *folio, size_t offset,
                 size_t length)
 {
     trace_ext4_invalidate_folio(folio, offset, length);
 
     /* No journalling happens on data buffers when this function is used */
     WARN_ON(folio_buffers(folio) && buffer_jbd(folio_buffers(folio)));
 
     block_invalidate_folio(folio, offset, length);
 }
 
 static int __ext4_journalled_invalidate_folio(struct folio *folio,
                         size_t offset, size_t length)
 {
     journal_t *journal = EXT4_JOURNAL(folio->mapping->host);
 
     trace_ext4_journalled_invalidate_folio(folio, offset, length);
 
     /*
      * If it's a full truncate we just forget about the pending dirtying
      */
     if (offset == 0 && length == folio_size(folio))
         folio_clear_checked(folio);
 
     return jbd2_journal_invalidate_folio(journal, folio, offset, length);
 }
 
 /* Wrapper for aops... */
 static void ext4_journalled_invalidate_folio(struct folio *folio,
                        size_t offset,
                        size_t length)
 {
     WARN_ON(__ext4_journalled_invalidate_folio(folio, offset, length) < 0);
 }
 
 static bool ext4_release_folio(struct folio *folio, gfp_t wait)
 {
     journal_t *journal = EXT4_JOURNAL(folio->mapping->host);
 
     trace_ext4_releasepage(&folio->page);
 
     /* Page has dirty journalled data -> cannot release */
     if (folio_test_checked(folio))
         return false;
     if (journal)
         return jbd2_journal_try_to_free_buffers(journal, folio);
     else
         return try_to_free_buffers(folio);
 }
 
 static bool ext4_inode_datasync_dirty(struct inode *inode)
 {
     journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;
 
     if (journal) {
         if (jbd2_transaction_committed(journal,
             EXT4_I(inode)->i_datasync_tid))
             return false;
         if (test_opt2(inode->i_sb, JOURNAL_FAST_COMMIT))
             return !list_empty(&EXT4_I(inode)->i_fc_list);
         return true;
     }
 
     /* Any metadata buffers to write? */
     if (!list_empty(&inode->i_mapping->private_list))
         return true;
     return inode->i_state & I_DIRTY_DATASYNC;
 }
 
 static void ext4_set_iomap(struct inode *inode, struct iomap *iomap,
                struct ext4_map_blocks *map, loff_t offset,
                loff_t length, unsigned int flags)
 {
     u8 blkbits = inode->i_blkbits;
 
     /*
      * Writes that span EOF might trigger an I/O size update on completion,
      * so consider them to be dirty for the purpose of O_DSYNC, even if
      * there is no other metadata changes being made or are pending.
      */
     iomap->flags = 0;
     if (ext4_inode_datasync_dirty(inode) ||
         offset + length > i_size_read(inode))
         iomap->flags |= IOMAP_F_DIRTY;
 
     if (map->m_flags & EXT4_MAP_NEW)
         iomap->flags |= IOMAP_F_NEW;
 
     if (flags & IOMAP_DAX)
         iomap->dax_dev = EXT4_SB(inode->i_sb)->s_daxdev;
     else
         iomap->bdev = inode->i_sb->s_bdev;
     iomap->offset = (u64) map->m_lblk << blkbits;
     iomap->length = (u64) map->m_len << blkbits;
 
     if ((map->m_flags & EXT4_MAP_MAPPED) &&
         !ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
         iomap->flags |= IOMAP_F_MERGED;
 
     /*
      * Flags passed to ext4_map_blocks() for direct I/O writes can result
      * in m_flags having both EXT4_MAP_MAPPED and EXT4_MAP_UNWRITTEN bits
      * set. In order for any allocated unwritten extents to be converted
      * into written extents correctly within the ->end_io() handler, we
      * need to ensure that the iomap->type is set appropriately. Hence, the
      * reason why we need to check whether the EXT4_MAP_UNWRITTEN bit has
      * been set first.
      */
     if (map->m_flags & EXT4_MAP_UNWRITTEN) {
         iomap->type = IOMAP_UNWRITTEN;
         iomap->addr = (u64) map->m_pblk << blkbits;
         if (flags & IOMAP_DAX)
             iomap->addr += EXT4_SB(inode->i_sb)->s_dax_part_off;
     } else if (map->m_flags & EXT4_MAP_MAPPED) {
         iomap->type = IOMAP_MAPPED;
         iomap->addr = (u64) map->m_pblk << blkbits;
         if (flags & IOMAP_DAX)
             iomap->addr += EXT4_SB(inode->i_sb)->s_dax_part_off;
     } else {
         iomap->type = IOMAP_HOLE;
         iomap->addr = IOMAP_NULL_ADDR;
     }
 }
 
 static int ext4_iomap_alloc(struct inode *inode, struct ext4_map_blocks *map,
                 unsigned int flags)
 {
     handle_t *handle;
     u8 blkbits = inode->i_blkbits;
     int ret, dio_credits, m_flags = 0, retries = 0;
 
     /*
      * Trim the mapping request to the maximum value that we can map at
      * once for direct I/O.
      */
     if (map->m_len > DIO_MAX_BLOCKS)
         map->m_len = DIO_MAX_BLOCKS;
     dio_credits = ext4_chunk_trans_blocks(inode, map->m_len);
 
 retry:
     /*
      * Either we allocate blocks and then don't get an unwritten extent, so
      * in that case we have reserved enough credits. Or, the blocks are
      * already allocated and unwritten. In that case, the extent conversion
      * fits into the credits as well.
      */
     handle = ext4_journal_start(inode, EXT4_HT_MAP_BLOCKS, dio_credits);
     if (IS_ERR(handle))
         return PTR_ERR(handle);
 
     /*
      * DAX and direct I/O are the only two operations that are currently
      * supported with IOMAP_WRITE.
      */
     WARN_ON(!(flags & (IOMAP_DAX | IOMAP_DIRECT)));
     if (flags & IOMAP_DAX)
         m_flags = EXT4_GET_BLOCKS_CREATE_ZERO;
     /*
      * We use i_size instead of i_disksize here because delalloc writeback
      * can complete at any point during the I/O and subsequently push the
      * i_disksize out to i_size. This could be beyond where direct I/O is
      * happening and thus expose allocated blocks to direct I/O reads.
      */
     else if (((loff_t)map->m_lblk << blkbits) >= i_size_read(inode))
         m_flags = EXT4_GET_BLOCKS_CREATE;
     else if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
         m_flags = EXT4_GET_BLOCKS_IO_CREATE_EXT;
 
     ret = ext4_map_blocks(handle, inode, map, m_flags);
 
     /*
      * We cannot fill holes in indirect tree based inodes as that could
      * expose stale data in the case of a crash. Use the magic error code
      * to fallback to buffered I/O.
      */
     if (!m_flags && !ret)
         ret = -ENOTBLK;
 
     ext4_journal_stop(handle);
     if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
         goto retry;
 
     return ret;
 }
 
 
 static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
         unsigned flags, struct iomap *iomap, struct iomap *srcmap)
 {
     int ret;
     struct ext4_map_blocks map;
     u8 blkbits = inode->i_blkbits;
 
     if ((offset >> blkbits) > EXT4_MAX_LOGICAL_BLOCK)
         return -EINVAL;
 
     if (WARN_ON_ONCE(ext4_has_inline_data(inode)))
         return -ERANGE;
 
     /*
      * Calculate the first and last logical blocks respectively.
      */
     map.m_lblk = offset >> blkbits;
     map.m_len = min_t(loff_t, (offset + length - 1) >> blkbits,
               EXT4_MAX_LOGICAL_BLOCK) - map.m_lblk + 1;
 
     if (flags & IOMAP_WRITE) {
         /*
          * We check here if the blocks are already allocated, then we
          * don't need to start a journal txn and we can directly return
          * the mapping information. This could boost performance
          * especially in multi-threaded overwrite requests.
          */
         if (offset + length <= i_size_read(inode)) {
             ret = ext4_map_blocks(NULL, inode, &map, 0);
             if (ret > 0 && (map.m_flags & EXT4_MAP_MAPPED))
                 goto out;
         }
         ret = ext4_iomap_alloc(inode, &map, flags);
     } else {
         ret = ext4_map_blocks(NULL, inode, &map, 0);
     }
 
     if (ret < 0)
         return ret;
 out:
     /*
      * When inline encryption is enabled, sometimes I/O to an encrypted file
      * has to be broken up to guarantee DUN contiguity.  Handle this by
      * limiting the length of the mapping returned.
      */
     map.m_len = fscrypt_limit_io_blocks(inode, map.m_lblk, map.m_len);
 
     ext4_set_iomap(inode, iomap, &map, offset, length, flags);
 
     return 0;
 }
 
 static int ext4_iomap_overwrite_begin(struct inode *inode, loff_t offset,
         loff_t length, unsigned flags, struct iomap *iomap,
         struct iomap *srcmap)
 {
     int ret;
 
     /*
      * Even for writes we don't need to allocate blocks, so just pretend
      * we are reading to save overhead of starting a transaction.
      */
     flags &= ~IOMAP_WRITE;
     ret = ext4_iomap_begin(inode, offset, length, flags, iomap, srcmap);
     WARN_ON_ONCE(iomap->type != IOMAP_MAPPED);
     return ret;
 }
 
 static int ext4_iomap_end(struct inode *inode, loff_t offset, loff_t length,
               ssize_t written, unsigned flags, struct iomap *iomap)
 {
     /*
      * Check to see whether an error occurred while writing out the data to
      * the allocated blocks. If so, return the magic error code so that we
      * fallback to buffered I/O and attempt to complete the remainder of
      * the I/O. Any blocks that may have been allocated in preparation for
      * the direct I/O will be reused during buffered I/O.
      */
     if (flags & (IOMAP_WRITE | IOMAP_DIRECT) && written == 0)
         return -ENOTBLK;
 
     return 0;
 }
 
 const struct iomap_ops ext4_iomap_ops = {
     .iomap_begin        = ext4_iomap_begin,
     .iomap_end      = ext4_iomap_end,
 };
 
 const struct iomap_ops ext4_iomap_overwrite_ops = {
     .iomap_begin        = ext4_iomap_overwrite_begin,
     .iomap_end      = ext4_iomap_end,
 };
 
 static bool ext4_iomap_is_delalloc(struct inode *inode,
                    struct ext4_map_blocks *map)
 {
     struct extent_status es;
     ext4_lblk_t offset = 0, end = map->m_lblk + map->m_len - 1;
 
     ext4_es_find_extent_range(inode, &ext4_es_is_delayed,
                   map->m_lblk, end, &es);
 
     if (!es.es_len || es.es_lblk > end)
         return false;
 
     if (es.es_lblk > map->m_lblk) {
         map->m_len = es.es_lblk - map->m_lblk;
         return false;
     }
 
     offset = map->m_lblk - es.es_lblk;
     map->m_len = es.es_len - offset;
 
     return true;
 }
 
 static int ext4_iomap_begin_report(struct inode *inode, loff_t offset,
                    loff_t length, unsigned int flags,
                    struct iomap *iomap, struct iomap *srcmap)
 {
     int ret;
     bool delalloc = false;
     struct ext4_map_blocks map;
     u8 blkbits = inode->i_blkbits;
 
     if ((offset >> blkbits) > EXT4_MAX_LOGICAL_BLOCK)
         return -EINVAL;
 
     if (ext4_has_inline_data(inode)) {
         ret = ext4_inline_data_iomap(inode, iomap);
         if (ret != -EAGAIN) {
             if (ret == 0 && offset >= iomap->length)
                 ret = -ENOENT;
             return ret;
         }
     }
 
     /*
      * Calculate the first and last logical block respectively.
      */
     map.m_lblk = offset >> blkbits;
     map.m_len = min_t(loff_t, (offset + length - 1) >> blkbits,
               EXT4_MAX_LOGICAL_BLOCK) - map.m_lblk + 1;
 
     /*
      * Fiemap callers may call for offset beyond s_bitmap_maxbytes.
      * So handle it here itself instead of querying ext4_map_blocks().
      * Since ext4_map_blocks() will warn about it and will return
      * -EIO error.
      */
     if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 
         if (offset >= sbi->s_bitmap_maxbytes) {
             map.m_flags = 0;
             goto set_iomap;
         }
     }
 
     ret = ext4_map_blocks(NULL, inode, &map, 0);
     if (ret < 0)
         return ret;
     if (ret == 0)
         delalloc = ext4_iomap_is_delalloc(inode, &map);
 
 set_iomap:
     ext4_set_iomap(inode, iomap, &map, offset, length, flags);
     if (delalloc && iomap->type == IOMAP_HOLE)
         iomap->type = IOMAP_DELALLOC;
 
     return 0;
 }
 
 const struct iomap_ops ext4_iomap_report_ops = {
     .iomap_begin = ext4_iomap_begin_report,
 };
 
 /*
  * Whenever the folio is being dirtied, corresponding buffers should already
  * be attached to the transaction (we take care of this in ext4_page_mkwrite()
  * and ext4_write_begin()). However we cannot move buffers to dirty transaction
  * lists here because ->dirty_folio is called under VFS locks and the folio
  * is not necessarily locked.
  *
  * We cannot just dirty the folio and leave attached buffers clean, because the
  * buffers' dirty state is "definitive".  We cannot just set the buffers dirty
  * or jbddirty because all the journalling code will explode.
  *
  * So what we do is to mark the folio "pending dirty" and next time writepage
  * is called, propagate that into the buffers appropriately.
  */
 static bool ext4_journalled_dirty_folio(struct address_space *mapping,
         struct folio *folio)
 {
     WARN_ON_ONCE(!folio_buffers(folio));
     folio_set_checked(folio);
     return filemap_dirty_folio(mapping, folio);
 }
 
 static bool ext4_dirty_folio(struct address_space *mapping, struct folio *folio)
 {
     WARN_ON_ONCE(!folio_test_locked(folio) && !folio_test_dirty(folio));
     WARN_ON_ONCE(!folio_buffers(folio));
     return block_dirty_folio(mapping, folio);
 }
 
 static int ext4_iomap_swap_activate(struct swap_info_struct *sis,
                     struct file *file, sector_t *span)
 {
     return iomap_swapfile_activate(sis, file, span,
                        &ext4_iomap_report_ops);
 }
 
 static const struct address_space_operations ext4_aops = {
     .read_folio     = ext4_read_folio,
     .readahead      = ext4_readahead,
     .writepage      = ext4_writepage,
     .writepages     = ext4_writepages,
     .write_begin        = ext4_write_begin,
     .write_end      = ext4_write_end,
     .dirty_folio        = ext4_dirty_folio,
     .bmap           = ext4_bmap,
     .invalidate_folio   = ext4_invalidate_folio,
     .release_folio      = ext4_release_folio,
     .direct_IO      = noop_direct_IO,
     .migrate_folio      = buffer_migrate_folio,
     .is_partially_uptodate  = block_is_partially_uptodate,
     .error_remove_page  = generic_error_remove_page,
     .swap_activate      = ext4_iomap_swap_activate,
 };
 
 static const struct address_space_operations ext4_journalled_aops = {
     .read_folio     = ext4_read_folio,
     .readahead      = ext4_readahead,
     .writepage      = ext4_writepage,
     .writepages     = ext4_writepages,
     .write_begin        = ext4_write_begin,
     .write_end      = ext4_journalled_write_end,
     .dirty_folio        = ext4_journalled_dirty_folio,
     .bmap           = ext4_bmap,
     .invalidate_folio   = ext4_journalled_invalidate_folio,
     .release_folio      = ext4_release_folio,
     .direct_IO      = noop_direct_IO,
     .is_partially_uptodate  = block_is_partially_uptodate,
     .error_remove_page  = generic_error_remove_page,
     .swap_activate      = ext4_iomap_swap_activate,
 };
 
 static const struct address_space_operations ext4_da_aops = {
     .read_folio     = ext4_read_folio,
     .readahead      = ext4_readahead,
     .writepage      = ext4_writepage,
     .writepages     = ext4_writepages,
     .write_begin        = ext4_da_write_begin,
     .write_end      = ext4_da_write_end,
     .dirty_folio        = ext4_dirty_folio,
     .bmap           = ext4_bmap,
     .invalidate_folio   = ext4_invalidate_folio,
     .release_folio      = ext4_release_folio,
     .direct_IO      = noop_direct_IO,
     .migrate_folio      = buffer_migrate_folio,
     .is_partially_uptodate  = block_is_partially_uptodate,
     .error_remove_page  = generic_error_remove_page,
     .swap_activate      = ext4_iomap_swap_activate,
 };
 
 static const struct address_space_operations ext4_dax_aops = {
     .writepages     = ext4_dax_writepages,
     .direct_IO      = noop_direct_IO,
     .dirty_folio        = noop_dirty_folio,
     .bmap           = ext4_bmap,
     .swap_activate      = ext4_iomap_swap_activate,
 };
 
 void ext4_set_aops(struct inode *inode)
 {
     switch (ext4_inode_journal_mode(inode)) {
     case EXT4_INODE_ORDERED_DATA_MODE:
     case EXT4_INODE_WRITEBACK_DATA_MODE:
         break;
     case EXT4_INODE_JOURNAL_DATA_MODE:
         inode->i_mapping->a_ops = &ext4_journalled_aops;
         return;
     default:
         BUG();
     }
     if (IS_DAX(inode))
         inode->i_mapping->a_ops = &ext4_dax_aops;
     else if (test_opt(inode->i_sb, DELALLOC))
         inode->i_mapping->a_ops = &ext4_da_aops;
     else
         inode->i_mapping->a_ops = &ext4_aops;
 }
 
 static int __ext4_block_zero_page_range(handle_t *handle,
         struct address_space *mapping, loff_t from, loff_t length)
 {
     ext4_fsblk_t index = from >> PAGE_SHIFT;
     unsigned offset = from & (PAGE_SIZE-1);
     unsigned blocksize, pos;
     ext4_lblk_t iblock;
     struct inode *inode = mapping->host;
     struct buffer_head *bh;
     struct page *page;
     int err = 0;
 
     page = find_or_create_page(mapping, from >> PAGE_SHIFT,
                    mapping_gfp_constraint(mapping, ~__GFP_FS));
     if (!page)
         return -ENOMEM;
 
     blocksize = inode->i_sb->s_blocksize;
 
     iblock = index << (PAGE_SHIFT - inode->i_sb->s_blocksize_bits);
 
     if (!page_has_buffers(page))
         create_empty_buffers(page, blocksize, 0);
 
     /* Find the buffer that contains "offset" */
     bh = page_buffers(page);
     pos = blocksize;
     while (offset >= pos) {
         bh = bh->b_this_page;
         iblock++;
         pos += blocksize;
     }
     if (buffer_freed(bh)) {
         BUFFER_TRACE(bh, "freed: skip");
         goto unlock;
     }
     if (!buffer_mapped(bh)) {
         BUFFER_TRACE(bh, "unmapped");
         ext4_get_block(inode, iblock, bh, 0);
         /* unmapped? It's a hole - nothing to do */
         if (!buffer_mapped(bh)) {
             BUFFER_TRACE(bh, "still unmapped");
             goto unlock;
         }
     }
 
     /* Ok, it's mapped. Make sure it's up-to-date */
     if (PageUptodate(page))
         set_buffer_uptodate(bh);
 
     if (!buffer_uptodate(bh)) {
         err = ext4_read_bh_lock(bh, 0, true);
         if (err)
             goto unlock;
         if (fscrypt_inode_uses_fs_layer_crypto(inode)) {
             /* We expect the key to be set. */
             BUG_ON(!fscrypt_has_encryption_key(inode));
             err = fscrypt_decrypt_pagecache_blocks(page, blocksize,
                                    bh_offset(bh));
             if (err) {
                 clear_buffer_uptodate(bh);
                 goto unlock;
             }
         }
     }
     if (ext4_should_journal_data(inode)) {
         BUFFER_TRACE(bh, "get write access");
         err = ext4_journal_get_write_access(handle, inode->i_sb, bh,
                             EXT4_JTR_NONE);
         if (err)
             goto unlock;
     }
     zero_user(page, offset, length);
     BUFFER_TRACE(bh, "zeroed end of block");
 
     if (ext4_should_journal_data(inode)) {
         err = ext4_handle_dirty_metadata(handle, inode, bh);
     } else {
         err = 0;
         mark_buffer_dirty(bh);
         if (ext4_should_order_data(inode))
             err = ext4_jbd2_inode_add_write(handle, inode, from,
                     length);
     }
 
 unlock:
     unlock_page(page);
     put_page(page);
     return err;
 }
 
 /*
  * ext4_block_zero_page_range() zeros out a mapping of length 'length'
  * starting from file offset 'from'.  The range to be zero'd must
  * be contained with in one block.  If the specified range exceeds
  * the end of the block it will be shortened to end of the block
  * that corresponds to 'from'
  */
 static int ext4_block_zero_page_range(handle_t *handle,
         struct address_space *mapping, loff_t from, loff_t length)
 {
     struct inode *inode = mapping->host;
     unsigned offset = from & (PAGE_SIZE-1);
     unsigned blocksize = inode->i_sb->s_blocksize;
     unsigned max = blocksize - (offset & (blocksize - 1));
 
     /*
      * correct length if it does not fall between
      * 'from' and the end of the block
      */
     if (length > max || length < 0)
         length = max;
 
     if (IS_DAX(inode)) {
         return dax_zero_range(inode, from, length, NULL,
                       &ext4_iomap_ops);
     }
     return __ext4_block_zero_page_range(handle, mapping, from, length);
 }
 
 /*
  * ext4_block_truncate_page() zeroes out a mapping from file offset `from'
  * up to the end of the block which corresponds to `from'.
  * This required during truncate. We need to physically zero the tail end
  * of that block so it doesn't yield old data if the file is later grown.
  */
 static int ext4_block_truncate_page(handle_t *handle,
         struct address_space *mapping, loff_t from)
 {
     unsigned offset = from & (PAGE_SIZE-1);
     unsigned length;
     unsigned blocksize;
     struct inode *inode = mapping->host;
 
     /* If we are processing an encrypted inode during orphan list handling */
     if (IS_ENCRYPTED(inode) && !fscrypt_has_encryption_key(inode))
         return 0;
 
     blocksize = inode->i_sb->s_blocksize;
     length = blocksize - (offset & (blocksize - 1));
 
     return ext4_block_zero_page_range(handle, mapping, from, length);
 }
 
 int ext4_zero_partial_blocks(handle_t *handle, struct inode *inode,
                  loff_t lstart, loff_t length)
 {
     struct super_block *sb = inode->i_sb;
     struct address_space *mapping = inode->i_mapping;
     unsigned partial_start, partial_end;
     ext4_fsblk_t start, end;
     loff_t byte_end = (lstart + length - 1);
     int err = 0;
 
     partial_start = lstart & (sb->s_blocksize - 1);
     partial_end = byte_end & (sb->s_blocksize - 1);
 
     start = lstart >> sb->s_blocksize_bits;
     end = byte_end >> sb->s_blocksize_bits;
 
     /* Handle partial zero within the single block */
     if (start == end &&
         (partial_start || (partial_end != sb->s_blocksize - 1))) {
         err = ext4_block_zero_page_range(handle, mapping,
                          lstart, length);
         return err;
     }
     /* Handle partial zero out on the start of the range */
     if (partial_start) {
         err = ext4_block_zero_page_range(handle, mapping,
                          lstart, sb->s_blocksize);
         if (err)
             return err;
     }
     /* Handle partial zero out on the end of the range */
     if (partial_end != sb->s_blocksize - 1)
         err = ext4_block_zero_page_range(handle, mapping,
                          byte_end - partial_end,
                          partial_end + 1);
     return err;
 }
 
 int ext4_can_truncate(struct inode *inode)
 {
     if (S_ISREG(inode->i_mode))
         return 1;
     if (S_ISDIR(inode->i_mode))
         return 1;
     if (S_ISLNK(inode->i_mode))
         return !ext4_inode_is_fast_symlink(inode);
     return 0;
 }
 
 /*
  * We have to make sure i_disksize gets properly updated before we truncate
  * page cache due to hole punching or zero range. Otherwise i_disksize update
  * can get lost as it may have been postponed to submission of writeback but
  * that will never happen after we truncate page cache.
  */
 int ext4_update_disksize_before_punch(struct inode *inode, loff_t offset,
                       loff_t len)
 {
     handle_t *handle;
     int ret;
 
     loff_t size = i_size_read(inode);
 
     WARN_ON(!inode_is_locked(inode));
     if (offset > size || offset + len < size)
         return 0;
 
     if (EXT4_I(inode)->i_disksize >= size)
         return 0;
 
     handle = ext4_journal_start(inode, EXT4_HT_MISC, 1);
     if (IS_ERR(handle))
         return PTR_ERR(handle);
     ext4_update_i_disksize(inode, size);
     ret = ext4_mark_inode_dirty(handle, inode);
     ext4_journal_stop(handle);
 
     return ret;
 }
 
 static void ext4_wait_dax_page(struct inode *inode)
 {
     filemap_invalidate_unlock(inode->i_mapping);
     schedule();
     filemap_invalidate_lock(inode->i_mapping);
 }
 
 int ext4_break_layouts(struct inode *inode)
 {
     struct page *page;
     int error;
 
     if (WARN_ON_ONCE(!rwsem_is_locked(&inode->i_mapping->invalidate_lock)))
         return -EINVAL;
 
     do {
         page = dax_layout_busy_page(inode->i_mapping);
         if (!page)
             return 0;
 
         error = ___wait_var_event(&page->_refcount,
                 atomic_read(&page->_refcount) == 1,
                 TASK_INTERRUPTIBLE, 0, 0,
                 ext4_wait_dax_page(inode));
     } while (error == 0);
 
     return error;
 }
 
 /*
  * ext4_punch_hole: punches a hole in a file by releasing the blocks
  * associated with the given offset and length
  *
  * @inode:  File inode
  * @offset: The offset where the hole will begin
  * @len:    The length of the hole
  *
  * Returns: 0 on success or negative on failure
  */
 
 int ext4_punch_hole(struct file *file, loff_t offset, loff_t length)
 {
     struct inode *inode = file_inode(file);
     struct super_block *sb = inode->i_sb;
     ext4_lblk_t first_block, stop_block;
     struct address_space *mapping = inode->i_mapping;
     loff_t first_block_offset, last_block_offset, max_length;
     struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
     handle_t *handle;
     unsigned int credits;
     int ret = 0, ret2 = 0;
 
     trace_ext4_punch_hole(inode, offset, length, 0);
 
     /*
      * Write out all dirty pages to avoid race conditions
      * Then release them.
      */
     if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) {
         ret = filemap_write_and_wait_range(mapping, offset,
                            offset + length - 1);
         if (ret)
             return ret;
     }
 
     inode_lock(inode);
 
     /* No need to punch hole beyond i_size */
     if (offset >= inode->i_size)
         goto out_mutex;
 
     /*
      * If the hole extends beyond i_size, set the hole
      * to end after the page that contains i_size
      */
     if (offset + length > inode->i_size) {
         length = inode->i_size +
            PAGE_SIZE - (inode->i_size & (PAGE_SIZE - 1)) -
            offset;
     }
 
     /*
      * For punch hole the length + offset needs to be within one block
      * before last range. Adjust the length if it goes beyond that limit.
      */
     max_length = sbi->s_bitmap_maxbytes - inode->i_sb->s_blocksize;
     if (offset + length > max_length)
         length = max_length - offset;
 
     if (offset & (sb->s_blocksize - 1) ||
         (offset + length) & (sb->s_blocksize - 1)) {
         /*
          * Attach jinode to inode for jbd2 if we do any zeroing of
          * partial block
          */
         ret = ext4_inode_attach_jinode(inode);
         if (ret < 0)
             goto out_mutex;
 
     }
 
     /* Wait all existing dio workers, newcomers will block on i_rwsem */
     inode_dio_wait(inode);
 
     ret = file_modified(file);
     if (ret)
         goto out_mutex;
 
     /*
      * Prevent page faults from reinstantiating pages we have released from
      * page cache.
      */
     filemap_invalidate_lock(mapping);
 
     ret = ext4_break_layouts(inode);
     if (ret)
         goto out_dio;
 
     first_block_offset = round_up(offset, sb->s_blocksize);
     last_block_offset = round_down((offset + length), sb->s_blocksize) - 1;
 
     /* Now release the pages and zero block aligned part of pages*/
     if (last_block_offset > first_block_offset) {
         ret = ext4_update_disksize_before_punch(inode, offset, length);
         if (ret)
             goto out_dio;
         truncate_pagecache_range(inode, first_block_offset,
                      last_block_offset);
     }
 
     if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
         credits = ext4_writepage_trans_blocks(inode);
     else
         credits = ext4_blocks_for_truncate(inode);
     handle = ext4_journal_start(inode, EXT4_HT_TRUNCATE, credits);
     if (IS_ERR(handle)) {
         ret = PTR_ERR(handle);
         ext4_std_error(sb, ret);
         goto out_dio;
     }
 
     ret = ext4_zero_partial_blocks(handle, inode, offset,
                        length);
     if (ret)
         goto out_stop;
 
     first_block = (offset + sb->s_blocksize - 1) >>
         EXT4_BLOCK_SIZE_BITS(sb);
     stop_block = (offset + length) >> EXT4_BLOCK_SIZE_BITS(sb);
 
     /* If there are blocks to remove, do it */
     if (stop_block > first_block) {
 
         down_write(&EXT4_I(inode)->i_data_sem);
         ext4_discard_preallocations(inode, 0);
 
         ret = ext4_es_remove_extent(inode, first_block,
                         stop_block - first_block);
         if (ret) {
             up_write(&EXT4_I(inode)->i_data_sem);
             goto out_stop;
         }
 
         if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
             ret = ext4_ext_remove_space(inode, first_block,
                             stop_block - 1);
         else
             ret = ext4_ind_remove_space(handle, inode, first_block,
                             stop_block);
 
         up_write(&EXT4_I(inode)->i_data_sem);
     }
     ext4_fc_track_range(handle, inode, first_block, stop_block);
     if (IS_SYNC(inode))
         ext4_handle_sync(handle);
 
     inode->i_mtime = inode->i_ctime = current_time(inode);
     ret2 = ext4_mark_inode_dirty(handle, inode);
     if (unlikely(ret2))
         ret = ret2;
     if (ret >= 0)
         ext4_update_inode_fsync_trans(handle, inode, 1);
 out_stop:
     ext4_journal_stop(handle);
 out_dio:
     filemap_invalidate_unlock(mapping);
 out_mutex:
     inode_unlock(inode);
     return ret;
 }
 
 int ext4_inode_attach_jinode(struct inode *inode)
 {
     struct ext4_inode_info *ei = EXT4_I(inode);
     struct jbd2_inode *jinode;
 
     if (ei->jinode || !EXT4_SB(inode->i_sb)->s_journal)
         return 0;
 
     jinode = jbd2_alloc_inode(GFP_KERNEL);
     spin_lock(&inode->i_lock);
     if (!ei->jinode) {
         if (!jinode) {
             spin_unlock(&inode->i_lock);
             return -ENOMEM;
         }
         ei->jinode = jinode;
         jbd2_journal_init_jbd_inode(ei->jinode, inode);
         jinode = NULL;
     }
     spin_unlock(&inode->i_lock);
     if (unlikely(jinode != NULL))
         jbd2_free_inode(jinode);
     return 0;
 }
 
 /*
  * ext4_truncate()
  *
  * We block out ext4_get_block() block instantiations across the entire
  * transaction, and VFS/VM ensures that ext4_truncate() cannot run
  * simultaneously on behalf of the same inode.
  *
  * As we work through the truncate and commit bits of it to the journal there
  * is one core, guiding principle: the file's tree must always be consistent on
  * disk.  We must be able to restart the truncate after a crash.
  *
  * The file's tree may be transiently inconsistent in memory (although it
  * probably isn't), but whenever we close off and commit a journal transaction,
  * the contents of (the filesystem + the journal) must be consistent and
  * restartable.  It's pretty simple, really: bottom up, right to left (although
  * left-to-right works OK too).
  *
  * Note that at recovery time, journal replay occurs *before* the restart of
  * truncate against the orphan inode list.
  *
  * The committed inode has the new, desired i_size (which is the same as
  * i_disksize in this case).  After a crash, ext4_orphan_cleanup() will see
  * that this inode's truncate did not complete and it will again call
  * ext4_truncate() to have another go.  So there will be instantiated blocks
  * to the right of the truncation point in a crashed ext4 filesystem.  But
  * that's fine - as long as they are linked from the inode, the post-crash
  * ext4_truncate() run will find them and release them.
  */
 int ext4_truncate(struct inode *inode)
 {
     struct ext4_inode_info *ei = EXT4_I(inode);
     unsigned int credits;
     int err = 0, err2;
     handle_t *handle;
     struct address_space *mapping = inode->i_mapping;
 
     /*
      * There is a possibility that we're either freeing the inode
      * or it's a completely new inode. In those cases we might not
      * have i_rwsem locked because it's not necessary.
      */
     if (!(inode->i_state & (I_NEW|I_FREEING)))
         WARN_ON(!inode_is_locked(inode));
     trace_ext4_truncate_enter(inode);
 
     if (!ext4_can_truncate(inode))
         goto out_trace;
 
     if (inode->i_size == 0 && !test_opt(inode->i_sb, NO_AUTO_DA_ALLOC))
         ext4_set_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE);
 
     if (ext4_has_inline_data(inode)) {
         int has_inline = 1;
 
         err = ext4_inline_data_truncate(inode, &has_inline);
         if (err || has_inline)
             goto out_trace;
     }
 
     /* If we zero-out tail of the page, we have to create jinode for jbd2 */
     if (inode->i_size & (inode->i_sb->s_blocksize - 1)) {
         if (ext4_inode_attach_jinode(inode) < 0)
             goto out_trace;
     }
 
     if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
         credits = ext4_writepage_trans_blocks(inode);
     else
         credits = ext4_blocks_for_truncate(inode);
 
     handle = ext4_journal_start(inode, EXT4_HT_TRUNCATE, credits);
     if (IS_ERR(handle)) {
         err = PTR_ERR(handle);
         goto out_trace;
     }
 
     if (inode->i_size & (inode->i_sb->s_blocksize - 1))
         ext4_block_truncate_page(handle, mapping, inode->i_size);
 
     /*
      * We add the inode to the orphan list, so that if this
      * truncate spans multiple transactions, and we crash, we will
      * resume the truncate when the filesystem recovers.  It also
      * marks the inode dirty, to catch the new size.
      *
      * Implication: the file must always be in a sane, consistent
      * truncatable state while each transaction commits.
      */
     err = ext4_orphan_add(handle, inode);
     if (err)
         goto out_stop;
 
     down_write(&EXT4_I(inode)->i_data_sem);
 
     ext4_discard_preallocations(inode, 0);
 
     if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
         err = ext4_ext_truncate(handle, inode);
     else
         ext4_ind_truncate(handle, inode);
 
     up_write(&ei->i_data_sem);
     if (err)
         goto out_stop;
 
     if (IS_SYNC(inode))
         ext4_handle_sync(handle);
 
 out_stop:
     /*
      * If this was a simple ftruncate() and the file will remain alive,
      * then we need to clear up the orphan record which we created above.
      * However, if this was a real unlink then we were called by
      * ext4_evict_inode(), and we allow that function to clean up the
      * orphan info for us.
      */
     if (inode->i_nlink)
         ext4_orphan_del(handle, inode);
 
     inode->i_mtime = inode->i_ctime = current_time(inode);
     err2 = ext4_mark_inode_dirty(handle, inode);
     if (unlikely(err2 && !err))
         err = err2;
     ext4_journal_stop(handle);
 
 out_trace:
     trace_ext4_truncate_exit(inode);
     return err;
 }
 
 static inline u64 ext4_inode_peek_iversion(const struct inode *inode)
 {
     if (unlikely(EXT4_I(inode)->i_flags & EXT4_EA_INODE_FL))
         return inode_peek_iversion_raw(inode);
     else
         return inode_peek_iversion(inode);
 }
 
 static int ext4_inode_blocks_set(struct ext4_inode *raw_inode,
                  struct ext4_inode_info *ei)
 {
     struct inode *inode = &(ei->vfs_inode);
     u64 i_blocks = READ_ONCE(inode->i_blocks);
     struct super_block *sb = inode->i_sb;
 
     if (i_blocks <= ~0U) {
         /*
          * i_blocks can be represented in a 32 bit variable
          * as multiple of 512 bytes
          */
         raw_inode->i_blocks_lo   = cpu_to_le32(i_blocks);
         raw_inode->i_blocks_high = 0;
         ext4_clear_inode_flag(inode, EXT4_INODE_HUGE_FILE);
         return 0;
     }
 
     /*
      * This should never happen since sb->s_maxbytes should not have
      * allowed this, sb->s_maxbytes was set according to the huge_file
      * feature in ext4_fill_super().
      */
     if (!ext4_has_feature_huge_file(sb))
         return -EFSCORRUPTED;
 
     if (i_blocks <= 0xffffffffffffULL) {
         /*
          * i_blocks can be represented in a 48 bit variable
          * as multiple of 512 bytes
          */
         raw_inode->i_blocks_lo   = cpu_to_le32(i_blocks);
         raw_inode->i_blocks_high = cpu_to_le16(i_blocks >> 32);
         ext4_clear_inode_flag(inode, EXT4_INODE_HUGE_FILE);
     } else {
         ext4_set_inode_flag(inode, EXT4_INODE_HUGE_FILE);
         /* i_block is stored in file system block size */
         i_blocks = i_blocks >> (inode->i_blkbits - 9);
         raw_inode->i_blocks_lo   = cpu_to_le32(i_blocks);
         raw_inode->i_blocks_high = cpu_to_le16(i_blocks >> 32);
     }
     return 0;
 }
 
 static int ext4_fill_raw_inode(struct inode *inode, struct ext4_inode *raw_inode)
 {
     struct ext4_inode_info *ei = EXT4_I(inode);
     uid_t i_uid;
     gid_t i_gid;
     projid_t i_projid;
     int block;
     int err;
 
     err = ext4_inode_blocks_set(raw_inode, ei);
 
     raw_inode->i_mode = cpu_to_le16(inode->i_mode);
     i_uid = i_uid_read(inode);
     i_gid = i_gid_read(inode);
     i_projid = from_kprojid(&init_user_ns, ei->i_projid);
     if (!(test_opt(inode->i_sb, NO_UID32))) {
         raw_inode->i_uid_low = cpu_to_le16(low_16_bits(i_uid));
         raw_inode->i_gid_low = cpu_to_le16(low_16_bits(i_gid));
         /*
          * Fix up interoperability with old kernels. Otherwise,
          * old inodes get re-used with the upper 16 bits of the
          * uid/gid intact.
          */
         if (ei->i_dtime && list_empty(&ei->i_orphan)) {
             raw_inode->i_uid_high = 0;
             raw_inode->i_gid_high = 0;
         } else {
             raw_inode->i_uid_high =
                 cpu_to_le16(high_16_bits(i_uid));
             raw_inode->i_gid_high =
                 cpu_to_le16(high_16_bits(i_gid));
         }
     } else {
         raw_inode->i_uid_low = cpu_to_le16(fs_high2lowuid(i_uid));
         raw_inode->i_gid_low = cpu_to_le16(fs_high2lowgid(i_gid));
         raw_inode->i_uid_high = 0;
         raw_inode->i_gid_high = 0;
     }
     raw_inode->i_links_count = cpu_to_le16(inode->i_nlink);
 
     EXT4_INODE_SET_XTIME(i_ctime, inode, raw_inode);
     EXT4_INODE_SET_XTIME(i_mtime, inode, raw_inode);
     EXT4_INODE_SET_XTIME(i_atime, inode, raw_inode);
     EXT4_EINODE_SET_XTIME(i_crtime, ei, raw_inode);
 
     raw_inode->i_dtime = cpu_to_le32(ei->i_dtime);
     raw_inode->i_flags = cpu_to_le32(ei->i_flags & 0xFFFFFFFF);
     if (likely(!test_opt2(inode->i_sb, HURD_COMPAT)))
         raw_inode->i_file_acl_high =
             cpu_to_le16(ei->i_file_acl >> 32);
     raw_inode->i_file_acl_lo = cpu_to_le32(ei->i_file_acl);
     ext4_isize_set(raw_inode, ei->i_disksize);
 
     raw_inode->i_generation = cpu_to_le32(inode->i_generation);
     if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode)) {
         if (old_valid_dev(inode->i_rdev)) {
             raw_inode->i_block[0] =
                 cpu_to_le32(old_encode_dev(inode->i_rdev));
             raw_inode->i_block[1] = 0;
         } else {
             raw_inode->i_block[0] = 0;
             raw_inode->i_block[1] =
                 cpu_to_le32(new_encode_dev(inode->i_rdev));
             raw_inode->i_block[2] = 0;
         }
     } else if (!ext4_has_inline_data(inode)) {
         for (block = 0; block < EXT4_N_BLOCKS; block++)
             raw_inode->i_block[block] = ei->i_data[block];
     }
 
     if (likely(!test_opt2(inode->i_sb, HURD_COMPAT))) {
         u64 ivers = ext4_inode_peek_iversion(inode);
 
         raw_inode->i_disk_version = cpu_to_le32(ivers);
         if (ei->i_extra_isize) {
             if (EXT4_FITS_IN_INODE(raw_inode, ei, i_version_hi))
                 raw_inode->i_version_hi =
                     cpu_to_le32(ivers >> 32);
             raw_inode->i_extra_isize =
                 cpu_to_le16(ei->i_extra_isize);
         }
     }
 
     if (i_projid != EXT4_DEF_PROJID &&
         !ext4_has_feature_project(inode->i_sb))
         err = err ?: -EFSCORRUPTED;
 
     if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE &&
         EXT4_FITS_IN_INODE(raw_inode, ei, i_projid))
         raw_inode->i_projid = cpu_to_le32(i_projid);
 
     ext4_inode_csum_set(inode, raw_inode, ei);
     return err;
 }
 
 /*
  * ext4_get_inode_loc returns with an extra refcount against the inode's
  * underlying buffer_head on success. If we pass 'inode' and it does not
  * have in-inode xattr, we have all inode data in memory that is needed
  * to recreate the on-disk version of this inode.
  */
 static int __ext4_get_inode_loc(struct super_block *sb, unsigned long ino,
                 struct inode *inode, struct ext4_iloc *iloc,
                 ext4_fsblk_t *ret_block)
 {
     struct ext4_group_desc  *gdp;
     struct buffer_head  *bh;
     ext4_fsblk_t        block;
     struct blk_plug     plug;
     int         inodes_per_block, inode_offset;
 
     iloc->bh = NULL;
     if (ino < EXT4_ROOT_INO ||
         ino > le32_to_cpu(EXT4_SB(sb)->s_es->s_inodes_count))
         return -EFSCORRUPTED;
 
     iloc->block_group = (ino - 1) / EXT4_INODES_PER_GROUP(sb);
     gdp = ext4_get_group_desc(sb, iloc->block_group, NULL);
     if (!gdp)
         return -EIO;
 
     /*
      * Figure out the offset within the block group inode table
      */
     inodes_per_block = EXT4_SB(sb)->s_inodes_per_block;
     inode_offset = ((ino - 1) %
             EXT4_INODES_PER_GROUP(sb));
     block = ext4_inode_table(sb, gdp) + (inode_offset / inodes_per_block);
     iloc->offset = (inode_offset % inodes_per_block) * EXT4_INODE_SIZE(sb);
 
     bh = sb_getblk(sb, block);
     if (unlikely(!bh))
         return -ENOMEM;
     if (ext4_buffer_uptodate(bh))
         goto has_buffer;
 
     lock_buffer(bh);
     if (ext4_buffer_uptodate(bh)) {
         /* Someone brought it uptodate while we waited */
         unlock_buffer(bh);
         goto has_buffer;
     }
 
     /*
      * If we have all information of the inode in memory and this
      * is the only valid inode in the block, we need not read the
      * block.
      */
     if (inode && !ext4_test_inode_state(inode, EXT4_STATE_XATTR)) {
         struct buffer_head *bitmap_bh;
         int i, start;
 
         start = inode_offset & ~(inodes_per_block - 1);
 
         /* Is the inode bitmap in cache? */
         bitmap_bh = sb_getblk(sb, ext4_inode_bitmap(sb, gdp));
         if (unlikely(!bitmap_bh))
             goto make_io;
 
         /*
          * If the inode bitmap isn't in cache then the
          * optimisation may end up performing two reads instead
          * of one, so skip it.
          */
         if (!buffer_uptodate(bitmap_bh)) {
             brelse(bitmap_bh);
             goto make_io;
         }
         for (i = start; i < start + inodes_per_block; i++) {
             if (i == inode_offset)
                 continue;
             if (ext4_test_bit(i, bitmap_bh->b_data))
                 break;
         }
         brelse(bitmap_bh);
         if (i == start + inodes_per_block) {
             struct ext4_inode *raw_inode =
                 (struct ext4_inode *) (bh->b_data + iloc->offset);
 
             /* all other inodes are free, so skip I/O */
             memset(bh->b_data, 0, bh->b_size);
             if (!ext4_test_inode_state(inode, EXT4_STATE_NEW))
                 ext4_fill_raw_inode(inode, raw_inode);
             set_buffer_uptodate(bh);
             unlock_buffer(bh);
             goto has_buffer;
         }
     }
 
 make_io:
     /*
      * If we need to do any I/O, try to pre-readahead extra
      * blocks from the inode table.
      */
     blk_start_plug(&plug);
     if (EXT4_SB(sb)->s_inode_readahead_blks) {
         ext4_fsblk_t b, end, table;
         unsigned num;
         __u32 ra_blks = EXT4_SB(sb)->s_inode_readahead_blks;
 
         table = ext4_inode_table(sb, gdp);
         /* s_inode_readahead_blks is always a power of 2 */
         b = block & ~((ext4_fsblk_t) ra_blks - 1);
         if (table > b)
             b = table;
         end = b + ra_blks;
         num = EXT4_INODES_PER_GROUP(sb);
         if (ext4_has_group_desc_csum(sb))
             num -= ext4_itable_unused_count(sb, gdp);
         table += num / inodes_per_block;
         if (end > table)
             end = table;
         while (b <= end)
             ext4_sb_breadahead_unmovable(sb, b++);
     }
 
     /*
      * There are other valid inodes in the buffer, this inode
      * has in-inode xattrs, or we don't have this inode in memory.
      * Read the block from disk.
      */
     trace_ext4_load_inode(sb, ino);
     ext4_read_bh_nowait(bh, REQ_META | REQ_PRIO, NULL);
     blk_finish_plug(&plug);
     wait_on_buffer(bh);
     ext4_simulate_fail_bh(sb, bh, EXT4_SIM_INODE_EIO);
     if (!buffer_uptodate(bh)) {
         if (ret_block)
             *ret_block = block;
         brelse(bh);
         return -EIO;
     }
 has_buffer:
     iloc->bh = bh;
     return 0;
 }
 
 static int __ext4_get_inode_loc_noinmem(struct inode *inode,
                     struct ext4_iloc *iloc)
 {
     ext4_fsblk_t err_blk = 0;
     int ret;
 
     ret = __ext4_get_inode_loc(inode->i_sb, inode->i_ino, NULL, iloc,
                     &err_blk);
 
     if (ret == -EIO)
         ext4_error_inode_block(inode, err_blk, EIO,
                     "unable to read itable block");
 
     return ret;
 }
 
 int ext4_get_inode_loc(struct inode *inode, struct ext4_iloc *iloc)
 {
     ext4_fsblk_t err_blk = 0;
     int ret;
 
     ret = __ext4_get_inode_loc(inode->i_sb, inode->i_ino, inode, iloc,
                     &err_blk);
 
     if (ret == -EIO)
         ext4_error_inode_block(inode, err_blk, EIO,
                     "unable to read itable block");
 
     return ret;
 }
 
 
 int ext4_get_fc_inode_loc(struct super_block *sb, unsigned long ino,
               struct ext4_iloc *iloc)
 {
     return __ext4_get_inode_loc(sb, ino, NULL, iloc, NULL);
 }
 
 static bool ext4_should_enable_dax(struct inode *inode)
 {
     struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 
     if (test_opt2(inode->i_sb, DAX_NEVER))
         return false;
     if (!S_ISREG(inode->i_mode))
         return false;
     if (ext4_should_journal_data(inode))
         return false;
     if (ext4_has_inline_data(inode))
         return false;
     if (ext4_test_inode_flag(inode, EXT4_INODE_ENCRYPT))
         return false;
     if (ext4_test_inode_flag(inode, EXT4_INODE_VERITY))
         return false;
     if (!test_bit(EXT4_FLAGS_BDEV_IS_DAX, &sbi->s_ext4_flags))
         return false;
     if (test_opt(inode->i_sb, DAX_ALWAYS))
         return true;
 
     return ext4_test_inode_flag(inode, EXT4_INODE_DAX);
 }
 
 void ext4_set_inode_flags(struct inode *inode, bool init)
 {
     unsigned int flags = EXT4_I(inode)->i_flags;
     unsigned int new_fl = 0;
 
     WARN_ON_ONCE(IS_DAX(inode) && init);
 
     if (flags & EXT4_SYNC_FL)
         new_fl |= S_SYNC;
     if (flags & EXT4_APPEND_FL)
         new_fl |= S_APPEND;
     if (flags & EXT4_IMMUTABLE_FL)
         new_fl |= S_IMMUTABLE;
     if (flags & EXT4_NOATIME_FL)
         new_fl |= S_NOATIME;
     if (flags & EXT4_DIRSYNC_FL)
         new_fl |= S_DIRSYNC;
 
     /* Because of the way inode_set_flags() works we must preserve S_DAX
      * here if already set. */
     new_fl |= (inode->i_flags & S_DAX);
     if (init && ext4_should_enable_dax(inode))
         new_fl |= S_DAX;
 
     if (flags & EXT4_ENCRYPT_FL)
         new_fl |= S_ENCRYPTED;
     if (flags & EXT4_CASEFOLD_FL)
         new_fl |= S_CASEFOLD;
     if (flags & EXT4_VERITY_FL)
         new_fl |= S_VERITY;
     inode_set_flags(inode, new_fl,
             S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC|S_DAX|
             S_ENCRYPTED|S_CASEFOLD|S_VERITY);
 }
 
 static blkcnt_t ext4_inode_blocks(struct ext4_inode *raw_inode,
                   struct ext4_inode_info *ei)
 {
     blkcnt_t i_blocks ;
     struct inode *inode = &(ei->vfs_inode);
     struct super_block *sb = inode->i_sb;
 
     if (ext4_has_feature_huge_file(sb)) {
         /* we are using combined 48 bit field */
         i_blocks = ((u64)le16_to_cpu(raw_inode->i_blocks_high)) << 32 |
                     le32_to_cpu(raw_inode->i_blocks_lo);
         if (ext4_test_inode_flag(inode, EXT4_INODE_HUGE_FILE)) {
             /* i_blocks represent file system block size */
             return i_blocks  << (inode->i_blkbits - 9);
         } else {
             return i_blocks;
         }
     } else {
         return le32_to_cpu(raw_inode->i_blocks_lo);
     }
 }
 
 static inline int ext4_iget_extra_inode(struct inode *inode,
                      struct ext4_inode *raw_inode,
                      struct ext4_inode_info *ei)
 {
     __le32 *magic = (void *)raw_inode +
             EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize;
 
     if (EXT4_INODE_HAS_XATTR_SPACE(inode)  &&
         *magic == cpu_to_le32(EXT4_XATTR_MAGIC)) {
         ext4_set_inode_state(inode, EXT4_STATE_XATTR);
         return ext4_find_inline_data_nolock(inode);
     } else
         EXT4_I(inode)->i_inline_off = 0;
     return 0;
 }
 
 int ext4_get_projid(struct inode *inode, kprojid_t *projid)
 {
     if (!ext4_has_feature_project(inode->i_sb))
         return -EOPNOTSUPP;
     *projid = EXT4_I(inode)->i_projid;
     return 0;
 }
 
 /*
  * ext4 has self-managed i_version for ea inodes, it stores the lower 32bit of
  * refcount in i_version, so use raw values if inode has EXT4_EA_INODE_FL flag
  * set.
  */
 static inline void ext4_inode_set_iversion_queried(struct inode *inode, u64 val)
 {
     if (unlikely(EXT4_I(inode)->i_flags & EXT4_EA_INODE_FL))
         inode_set_iversion_raw(inode, val);
     else
         inode_set_iversion_queried(inode, val);
 }
 
 struct inode *__ext4_iget(struct super_block *sb, unsigned long ino,
               ext4_iget_flags flags, const char *function,
               unsigned int line)
 {
     struct ext4_iloc iloc;
     struct ext4_inode *raw_inode;
     struct ext4_inode_info *ei;
     struct ext4_super_block *es = EXT4_SB(sb)->s_es;
     struct inode *inode;
     journal_t *journal = EXT4_SB(sb)->s_journal;
     long ret;
     loff_t size;
     int block;
     uid_t i_uid;
     gid_t i_gid;
     projid_t i_projid;
 
     if ((!(flags & EXT4_IGET_SPECIAL) &&
          ((ino < EXT4_FIRST_INO(sb) && ino != EXT4_ROOT_INO) ||
           ino == le32_to_cpu(es->s_usr_quota_inum) ||
           ino == le32_to_cpu(es->s_grp_quota_inum) ||
           ino == le32_to_cpu(es->s_prj_quota_inum) ||
           ino == le32_to_cpu(es->s_orphan_file_inum))) ||
         (ino < EXT4_ROOT_INO) ||
         (ino > le32_to_cpu(es->s_inodes_count))) {
         if (flags & EXT4_IGET_HANDLE)
             return ERR_PTR(-ESTALE);
         __ext4_error(sb, function, line, false, EFSCORRUPTED, 0,
                  "inode #%lu: comm %s: iget: illegal inode #",
                  ino, current->comm);
         return ERR_PTR(-EFSCORRUPTED);
     }
 
     inode = iget_locked(sb, ino);
     if (!inode)
         return ERR_PTR(-ENOMEM);
     if (!(inode->i_state & I_NEW))
         return inode;
 
     ei = EXT4_I(inode);
     iloc.bh = NULL;
 
     ret = __ext4_get_inode_loc_noinmem(inode, &iloc);
     if (ret < 0)
         goto bad_inode;
     raw_inode = ext4_raw_inode(&iloc);
 
     if ((ino == EXT4_ROOT_INO) && (raw_inode->i_links_count == 0)) {
         ext4_error_inode(inode, function, line, 0,
                  "iget: root inode unallocated");
         ret = -EFSCORRUPTED;
         goto bad_inode;
     }
 
     if ((flags & EXT4_IGET_HANDLE) &&
         (raw_inode->i_links_count == 0) && (raw_inode->i_mode == 0)) {
         ret = -ESTALE;
         goto bad_inode;
     }
 
     if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
         ei->i_extra_isize = le16_to_cpu(raw_inode->i_extra_isize);
         if (EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize >
             EXT4_INODE_SIZE(inode->i_sb) ||
             (ei->i_extra_isize & 3)) {
             ext4_error_inode(inode, function, line, 0,
                      "iget: bad extra_isize %u "
                      "(inode size %u)",
                      ei->i_extra_isize,
                      EXT4_INODE_SIZE(inode->i_sb));
             ret = -EFSCORRUPTED;
             goto bad_inode;
         }
     } else
         ei->i_extra_isize = 0;
 
     /* Precompute checksum seed for inode metadata */
     if (ext4_has_metadata_csum(sb)) {
         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
         __u32 csum;
         __le32 inum = cpu_to_le32(inode->i_ino);
         __le32 gen = raw_inode->i_generation;
         csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)&inum,
                    sizeof(inum));
         ei->i_csum_seed = ext4_chksum(sbi, csum, (__u8 *)&gen,
                           sizeof(gen));
     }
 
     if ((!ext4_inode_csum_verify(inode, raw_inode, ei) ||
         ext4_simulate_fail(sb, EXT4_SIM_INODE_CRC)) &&
          (!(EXT4_SB(sb)->s_mount_state & EXT4_FC_REPLAY))) {
         ext4_error_inode_err(inode, function, line, 0,
                 EFSBADCRC, "iget: checksum invalid");
         ret = -EFSBADCRC;
         goto bad_inode;
     }
 
     inode->i_mode = le16_to_cpu(raw_inode->i_mode);
     i_uid = (uid_t)le16_to_cpu(raw_inode->i_uid_low);
     i_gid = (gid_t)le16_to_cpu(raw_inode->i_gid_low);
     if (ext4_has_feature_project(sb) &&
         EXT4_INODE_SIZE(sb) > EXT4_GOOD_OLD_INODE_SIZE &&
         EXT4_FITS_IN_INODE(raw_inode, ei, i_projid))
         i_projid = (projid_t)le32_to_cpu(raw_inode->i_projid);
     else
         i_projid = EXT4_DEF_PROJID;
 
     if (!(test_opt(inode->i_sb, NO_UID32))) {
         i_uid |= le16_to_cpu(raw_inode->i_uid_high) << 16;
         i_gid |= le16_to_cpu(raw_inode->i_gid_high) << 16;
     }
     i_uid_write(inode, i_uid);
     i_gid_write(inode, i_gid);
     ei->i_projid = make_kprojid(&init_user_ns, i_projid);
     set_nlink(inode, le16_to_cpu(raw_inode->i_links_count));
 
     ext4_clear_state_flags(ei); /* Only relevant on 32-bit archs */
     ei->i_inline_off = 0;
     ei->i_dir_start_lookup = 0;
     ei->i_dtime = le32_to_cpu(raw_inode->i_dtime);
     /* We now have enough fields to check if the inode was active or not.
      * This is needed because nfsd might try to access dead inodes
      * the test is that same one that e2fsck uses
      * NeilBrown 1999oct15
      */
     if (inode->i_nlink == 0) {
         if ((inode->i_mode == 0 ||
              !(EXT4_SB(inode->i_sb)->s_mount_state & EXT4_ORPHAN_FS)) &&
             ino != EXT4_BOOT_LOADER_INO) {
             /* this inode is deleted */
             ret = -ESTALE;
             goto bad_inode;
         }
         /* The only unlinked inodes we let through here have
          * valid i_mode and are being read by the orphan
          * recovery code: that's fine, we're about to complete
          * the process of deleting those.
          * OR it is the EXT4_BOOT_LOADER_INO which is
          * not initialized on a new filesystem. */
     }
     ei->i_flags = le32_to_cpu(raw_inode->i_flags);
     ext4_set_inode_flags(inode, true);
     inode->i_blocks = ext4_inode_blocks(raw_inode, ei);
     ei->i_file_acl = le32_to_cpu(raw_inode->i_file_acl_lo);
     if (ext4_has_feature_64bit(sb))
         ei->i_file_acl |=
             ((__u64)le16_to_cpu(raw_inode->i_file_acl_high)) << 32;
     inode->i_size = ext4_isize(sb, raw_inode);
     if ((size = i_size_read(inode)) < 0) {
         ext4_error_inode(inode, function, line, 0,
                  "iget: bad i_size value: %lld", size);
         ret = -EFSCORRUPTED;
         goto bad_inode;
     }
     /*
      * If dir_index is not enabled but there's dir with INDEX flag set,
      * we'd normally treat htree data as empty space. But with metadata
      * checksumming that corrupts checksums so forbid that.
      */
     if (!ext4_has_feature_dir_index(sb) && ext4_has_metadata_csum(sb) &&
         ext4_test_inode_flag(inode, EXT4_INODE_INDEX)) {
         ext4_error_inode(inode, function, line, 0,
              "iget: Dir with htree data on filesystem without dir_index feature.");
         ret = -EFSCORRUPTED;
         goto bad_inode;
     }
     ei->i_disksize = inode->i_size;
 #ifdef CONFIG_QUOTA
     ei->i_reserved_quota = 0;
 #endif
     inode->i_generation = le32_to_cpu(raw_inode->i_generation);
     ei->i_block_group = iloc.block_group;
     ei->i_last_alloc_group = ~0;
     /*
      * NOTE! The in-memory inode i_data array is in little-endian order
      * even on big-endian machines: we do NOT byteswap the block numbers!
      */
     for (block = 0; block < EXT4_N_BLOCKS; block++)
         ei->i_data[block] = raw_inode->i_block[block];
     INIT_LIST_HEAD(&ei->i_orphan);
     ext4_fc_init_inode(&ei->vfs_inode);
 
     /*
      * Set transaction id's of transactions that have to be committed
      * to finish f[data]sync. We set them to currently running transaction
      * as we cannot be sure that the inode or some of its metadata isn't
      * part of the transaction - the inode could have been reclaimed and
      * now it is reread from disk.
      */
     if (journal) {
         transaction_t *transaction;
         tid_t tid;
 
         read_lock(&journal->j_state_lock);
         if (journal->j_running_transaction)
             transaction = journal->j_running_transaction;
         else
             transaction = journal->j_committing_transaction;
         if (transaction)
             tid = transaction->t_tid;
         else
             tid = journal->j_commit_sequence;
         read_unlock(&journal->j_state_lock);
         ei->i_sync_tid = tid;
         ei->i_datasync_tid = tid;
     }
 
     if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
         if (ei->i_extra_isize == 0) {
             /* The extra space is currently unused. Use it. */
             BUILD_BUG_ON(sizeof(struct ext4_inode) & 3);
             ei->i_extra_isize = sizeof(struct ext4_inode) -
                         EXT4_GOOD_OLD_INODE_SIZE;
         } else {
             ret = ext4_iget_extra_inode(inode, raw_inode, ei);
             if (ret)
                 goto bad_inode;
         }
     }
 
     EXT4_INODE_GET_XTIME(i_ctime, inode, raw_inode);
     EXT4_INODE_GET_XTIME(i_mtime, inode, raw_inode);
     EXT4_INODE_GET_XTIME(i_atime, inode, raw_inode);
     EXT4_EINODE_GET_XTIME(i_crtime, ei, raw_inode);
 
     if (likely(!test_opt2(inode->i_sb, HURD_COMPAT))) {
         u64 ivers = le32_to_cpu(raw_inode->i_disk_version);
 
         if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
             if (EXT4_FITS_IN_INODE(raw_inode, ei, i_version_hi))
                 ivers |=
             (__u64)(le32_to_cpu(raw_inode->i_version_hi)) << 32;
         }
         ext4_inode_set_iversion_queried(inode, ivers);
     }
 
     ret = 0;
     if (ei->i_file_acl &&
         !ext4_inode_block_valid(inode, ei->i_file_acl, 1)) {
         ext4_error_inode(inode, function, line, 0,
                  "iget: bad extended attribute block %llu",
                  ei->i_file_acl);
         ret = -EFSCORRUPTED;
         goto bad_inode;
     } else if (!ext4_has_inline_data(inode)) {
         /* validate the block references in the inode */
         if (!(EXT4_SB(sb)->s_mount_state & EXT4_FC_REPLAY) &&
             (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
             (S_ISLNK(inode->i_mode) &&
             !ext4_inode_is_fast_symlink(inode)))) {
             if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
                 ret = ext4_ext_check_inode(inode);
             else
                 ret = ext4_ind_check_inode(inode);
         }
     }
     if (ret)
         goto bad_inode;
 
     if (S_ISREG(inode->i_mode)) {
         inode->i_op = &ext4_file_inode_operations;
         inode->i_fop = &ext4_file_operations;
         ext4_set_aops(inode);
     } else if (S_ISDIR(inode->i_mode)) {
         inode->i_op = &ext4_dir_inode_operations;
         inode->i_fop = &ext4_dir_operations;
     } else if (S_ISLNK(inode->i_mode)) {
         /* VFS does not allow setting these so must be corruption */
         if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) {
             ext4_error_inode(inode, function, line, 0,
                      "iget: immutable or append flags "
                      "not allowed on symlinks");
             ret = -EFSCORRUPTED;
             goto bad_inode;
         }
         if (IS_ENCRYPTED(inode)) {
             inode->i_op = &ext4_encrypted_symlink_inode_operations;
         } else if (ext4_inode_is_fast_symlink(inode)) {
             inode->i_link = (char *)ei->i_data;
             inode->i_op = &ext4_fast_symlink_inode_operations;
             nd_terminate_link(ei->i_data, inode->i_size,
                 sizeof(ei->i_data) - 1);
         } else {
             inode->i_op = &ext4_symlink_inode_operations;
         }
     } else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode) ||
           S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
         inode->i_op = &ext4_special_inode_operations;
         if (raw_inode->i_block[0])
             init_special_inode(inode, inode->i_mode,
                old_decode_dev(le32_to_cpu(raw_inode->i_block[0])));
         else
             init_special_inode(inode, inode->i_mode,
                new_decode_dev(le32_to_cpu(raw_inode->i_block[1])));
     } else if (ino == EXT4_BOOT_LOADER_INO) {
         make_bad_inode(inode);
     } else {
         ret = -EFSCORRUPTED;
         ext4_error_inode(inode, function, line, 0,
                  "iget: bogus i_mode (%o)", inode->i_mode);
         goto bad_inode;
     }
     if (IS_CASEFOLDED(inode) && !ext4_has_feature_casefold(inode->i_sb))
         ext4_error_inode(inode, function, line, 0,
                  "casefold flag without casefold feature");
     brelse(iloc.bh);
 
     unlock_new_inode(inode);
     return inode;
 
 bad_inode:
     brelse(iloc.bh);
     iget_failed(inode);
     return ERR_PTR(ret);
 }
 
 static void __ext4_update_other_inode_time(struct super_block *sb,
                        unsigned long orig_ino,
                        unsigned long ino,
                        struct ext4_inode *raw_inode)
 {
     struct inode *inode;
 
     inode = find_inode_by_ino_rcu(sb, ino);
     if (!inode)
         return;
 
     if (!inode_is_dirtytime_only(inode))
         return;
 
     spin_lock(&inode->i_lock);
     if (inode_is_dirtytime_only(inode)) {
         struct ext4_inode_info  *ei = EXT4_I(inode);
 
         inode->i_state &= ~I_DIRTY_TIME;
         spin_unlock(&inode->i_lock);
 
         spin_lock(&ei->i_raw_lock);
         EXT4_INODE_SET_XTIME(i_ctime, inode, raw_inode);
         EXT4_INODE_SET_XTIME(i_mtime, inode, raw_inode);
         EXT4_INODE_SET_XTIME(i_atime, inode, raw_inode);
         ext4_inode_csum_set(inode, raw_inode, ei);
         spin_unlock(&ei->i_raw_lock);
         trace_ext4_other_inode_update_time(inode, orig_ino);
         return;
     }
     spin_unlock(&inode->i_lock);
 }
 
 /*
  * Opportunistically update the other time fields for other inodes in
  * the same inode table block.
  */
 static void ext4_update_other_inodes_time(struct super_block *sb,
                       unsigned long orig_ino, char *buf)
 {
     unsigned long ino;
     int i, inodes_per_block = EXT4_SB(sb)->s_inodes_per_block;
     int inode_size = EXT4_INODE_SIZE(sb);
 
     /*
      * Calculate the first inode in the inode table block.  Inode
      * numbers are one-based.  That is, the first inode in a block
      * (assuming 4k blocks and 256 byte inodes) is (n*16 + 1).
      */
     ino = ((orig_ino - 1) & ~(inodes_per_block - 1)) + 1;
     rcu_read_lock();
     for (i = 0; i < inodes_per_block; i++, ino++, buf += inode_size) {
         if (ino == orig_ino)
             continue;
         __ext4_update_other_inode_time(sb, orig_ino, ino,
                            (struct ext4_inode *)buf);
     }
     rcu_read_unlock();
 }
 
 /*
  * Post the struct inode info into an on-disk inode location in the
  * buffer-cache.  This gobbles the caller's reference to the
  * buffer_head in the inode location struct.
  *
  * The caller must have write access to iloc->bh.
  */
 static int ext4_do_update_inode(handle_t *handle,
                 struct inode *inode,
                 struct ext4_iloc *iloc)
 {
     struct ext4_inode *raw_inode = ext4_raw_inode(iloc);
     struct ext4_inode_info *ei = EXT4_I(inode);
     struct buffer_head *bh = iloc->bh;
     struct super_block *sb = inode->i_sb;
     int err;
     int need_datasync = 0, set_large_file = 0;
 
     spin_lock(&ei->i_raw_lock);
 
     /*
      * For fields not tracked in the in-memory inode, initialise them
      * to zero for new inodes.
      */
     if (ext4_test_inode_state(inode, EXT4_STATE_NEW))
         memset(raw_inode, 0, EXT4_SB(inode->i_sb)->s_inode_size);
 
     if (READ_ONCE(ei->i_disksize) != ext4_isize(inode->i_sb, raw_inode))
         need_datasync = 1;
     if (ei->i_disksize > 0x7fffffffULL) {
         if (!ext4_has_feature_large_file(sb) ||
             EXT4_SB(sb)->s_es->s_rev_level == cpu_to_le32(EXT4_GOOD_OLD_REV))
             set_large_file = 1;
     }
 
     err = ext4_fill_raw_inode(inode, raw_inode);
     spin_unlock(&ei->i_raw_lock);
     if (err) {
         EXT4_ERROR_INODE(inode, "corrupted inode contents");
         goto out_brelse;
     }
 
     if (inode->i_sb->s_flags & SB_LAZYTIME)
         ext4_update_other_inodes_time(inode->i_sb, inode->i_ino,
                           bh->b_data);
 
     BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
     err = ext4_handle_dirty_metadata(handle, NULL, bh);
     if (err)
         goto out_error;
     ext4_clear_inode_state(inode, EXT4_STATE_NEW);
     if (set_large_file) {
         BUFFER_TRACE(EXT4_SB(sb)->s_sbh, "get write access");
         err = ext4_journal_get_write_access(handle, sb,
                             EXT4_SB(sb)->s_sbh,
                             EXT4_JTR_NONE);
         if (err)
             goto out_error;
         lock_buffer(EXT4_SB(sb)->s_sbh);
         ext4_set_feature_large_file(sb);
         ext4_superblock_csum_set(sb);
         unlock_buffer(EXT4_SB(sb)->s_sbh);
         ext4_handle_sync(handle);
         err = ext4_handle_dirty_metadata(handle, NULL,
                          EXT4_SB(sb)->s_sbh);
     }
     ext4_update_inode_fsync_trans(handle, inode, need_datasync);
 out_error:
     ext4_std_error(inode->i_sb, err);
 out_brelse:
     brelse(bh);
     return err;
 }
 
 /*
  * ext4_write_inode()
  *
  * We are called from a few places:
  *
  * - Within generic_file_aio_write() -> generic_write_sync() for O_SYNC files.
  *   Here, there will be no transaction running. We wait for any running
  *   transaction to commit.
  *
  * - Within flush work (sys_sync(), kupdate and such).
  *   We wait on commit, if told to.
  *
  * - Within iput_final() -> write_inode_now()
  *   We wait on commit, if told to.
  *
  * In all cases it is actually safe for us to return without doing anything,
  * because the inode has been copied into a raw inode buffer in
  * ext4_mark_inode_dirty().  This is a correctness thing for WB_SYNC_ALL
  * writeback.
  *
  * Note that we are absolutely dependent upon all inode dirtiers doing the
  * right thing: they *must* call mark_inode_dirty() after dirtying info in
  * which we are interested.
  *
  * It would be a bug for them to not do this.  The code:
  *
  *  mark_inode_dirty(inode)
  *  stuff();
  *  inode->i_size = expr;
  *
  * is in error because write_inode() could occur while `stuff()' is running,
  * and the new i_size will be lost.  Plus the inode will no longer be on the
  * superblock's dirty inode list.
  */
 int ext4_write_inode(struct inode *inode, struct writeback_control *wbc)
 {
     int err;
 
     if (WARN_ON_ONCE(current->flags & PF_MEMALLOC) ||
         sb_rdonly(inode->i_sb))
         return 0;
 
     if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
         return -EIO;
 
     if (EXT4_SB(inode->i_sb)->s_journal) {
         if (ext4_journal_current_handle()) {
             ext4_debug("called recursively, non-PF_MEMALLOC!\n");
             dump_stack();
             return -EIO;
         }
 
         /*
          * No need to force transaction in WB_SYNC_NONE mode. Also
          * ext4_sync_fs() will force the commit after everything is
          * written.
          */
         if (wbc->sync_mode != WB_SYNC_ALL || wbc->for_sync)
             return 0;
 
         err = ext4_fc_commit(EXT4_SB(inode->i_sb)->s_journal,
                         EXT4_I(inode)->i_sync_tid);
     } else {
         struct ext4_iloc iloc;
 
         err = __ext4_get_inode_loc_noinmem(inode, &iloc);
         if (err)
             return err;
         /*
          * sync(2) will flush the whole buffer cache. No need to do
          * it here separately for each inode.
          */
         if (wbc->sync_mode == WB_SYNC_ALL && !wbc->for_sync)
             sync_dirty_buffer(iloc.bh);
         if (buffer_req(iloc.bh) && !buffer_uptodate(iloc.bh)) {
             ext4_error_inode_block(inode, iloc.bh->b_blocknr, EIO,
                            "IO error syncing inode");
             err = -EIO;
         }
         brelse(iloc.bh);
     }
     return err;
 }
 
 /*
  * In data=journal mode ext4_journalled_invalidate_folio() may fail to invalidate
  * buffers that are attached to a folio straddling i_size and are undergoing
  * commit. In that case we have to wait for commit to finish and try again.
  */
 static void ext4_wait_for_tail_page_commit(struct inode *inode)
 {
     unsigned offset;
     journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;
     tid_t commit_tid = 0;
     int ret;
 
     offset = inode->i_size & (PAGE_SIZE - 1);
     /*
      * If the folio is fully truncated, we don't need to wait for any commit
      * (and we even should not as __ext4_journalled_invalidate_folio() may
      * strip all buffers from the folio but keep the folio dirty which can then
      * confuse e.g. concurrent ext4_writepage() seeing dirty folio without
      * buffers). Also we don't need to wait for any commit if all buffers in
      * the folio remain valid. This is most beneficial for the common case of
      * blocksize == PAGESIZE.
      */
     if (!offset || offset > (PAGE_SIZE - i_blocksize(inode)))
         return;
     while (1) {
         struct folio *folio = filemap_lock_folio(inode->i_mapping,
                       inode->i_size >> PAGE_SHIFT);
         if (!folio)
             return;
         ret = __ext4_journalled_invalidate_folio(folio, offset,
                         folio_size(folio) - offset);
         folio_unlock(folio);
         folio_put(folio);
         if (ret != -EBUSY)
             return;
         commit_tid = 0;
         read_lock(&journal->j_state_lock);
         if (journal->j_committing_transaction)
             commit_tid = journal->j_committing_transaction->t_tid;
         read_unlock(&journal->j_state_lock);
         if (commit_tid)
             jbd2_log_wait_commit(journal, commit_tid);
     }
 }
 
 /*
  * ext4_setattr()
  *
  * Called from notify_change.
  *
  * We want to trap VFS attempts to truncate the file as soon as
  * possible.  In particular, we want to make sure that when the VFS
  * shrinks i_size, we put the inode on the orphan list and modify
  * i_disksize immediately, so that during the subsequent flushing of
  * dirty pages and freeing of disk blocks, we can guarantee that any
  * commit will leave the blocks being flushed in an unused state on
  * disk.  (On recovery, the inode will get truncated and the blocks will
  * be freed, so we have a strong guarantee that no future commit will
  * leave these blocks visible to the user.)
  *
  * Another thing we have to assure is that if we are in ordered mode
  * and inode is still attached to the committing transaction, we must
  * we start writeout of all the dirty pages which are being truncated.
  * This way we are sure that all the data written in the previous
  * transaction are already on disk (truncate waits for pages under
  * writeback).
  *
  * Called with inode->i_rwsem down.
  */
 int ext4_setattr(struct user_namespace *mnt_userns, struct dentry *dentry,
          struct iattr *attr)
 {
     struct inode *inode = d_inode(dentry);
     int error, rc = 0;
     int orphan = 0;
     const unsigned int ia_valid = attr->ia_valid;
 
     if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
         return -EIO;
 
     if (unlikely(IS_IMMUTABLE(inode)))
         return -EPERM;
 
     if (unlikely(IS_APPEND(inode) &&
              (ia_valid & (ATTR_MODE | ATTR_UID |
                   ATTR_GID | ATTR_TIMES_SET))))
         return -EPERM;
 
     error = setattr_prepare(mnt_userns, dentry, attr);
     if (error)
         return error;
 
     error = fscrypt_prepare_setattr(dentry, attr);
     if (error)
         return error;
 
     error = fsverity_prepare_setattr(dentry, attr);
     if (error)
         return error;
 
     if (is_quota_modification(mnt_userns, inode, attr)) {
         error = dquot_initialize(inode);
         if (error)
             return error;
     }
 
     if (i_uid_needs_update(mnt_userns, attr, inode) ||
         i_gid_needs_update(mnt_userns, attr, inode)) {
         handle_t *handle;
 
         /* (user+group)*(old+new) structure, inode write (sb,
          * inode block, ? - but truncate inode update has it) */
         handle = ext4_journal_start(inode, EXT4_HT_QUOTA,
             (EXT4_MAXQUOTAS_INIT_BLOCKS(inode->i_sb) +
              EXT4_MAXQUOTAS_DEL_BLOCKS(inode->i_sb)) + 3);
         if (IS_ERR(handle)) {
             error = PTR_ERR(handle);
             goto err_out;
         }
 
         /* dquot_transfer() calls back ext4_get_inode_usage() which
          * counts xattr inode references.
          */
         down_read(&EXT4_I(inode)->xattr_sem);
         error = dquot_transfer(mnt_userns, inode, attr);
         up_read(&EXT4_I(inode)->xattr_sem);
 
         if (error) {
             ext4_journal_stop(handle);
             return error;
         }
         /* Update corresponding info in inode so that everything is in
          * one transaction */
         i_uid_update(mnt_userns, attr, inode);
         i_gid_update(mnt_userns, attr, inode);
         error = ext4_mark_inode_dirty(handle, inode);
         ext4_journal_stop(handle);
         if (unlikely(error)) {
             return error;
         }
     }
 
     if (attr->ia_valid & ATTR_SIZE) {
         handle_t *handle;
         loff_t oldsize = inode->i_size;
         loff_t old_disksize;
         int shrink = (attr->ia_size < inode->i_size);
 
         if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
             struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 
             if (attr->ia_size > sbi->s_bitmap_maxbytes) {
                 return -EFBIG;
             }
         }
         if (!S_ISREG(inode->i_mode)) {
             return -EINVAL;
         }
 
         if (IS_I_VERSION(inode) && attr->ia_size != inode->i_size)
             inode_inc_iversion(inode);
 
         if (shrink) {
             if (ext4_should_order_data(inode)) {
                 error = ext4_begin_ordered_truncate(inode,
                                 attr->ia_size);
                 if (error)
                     goto err_out;
             }
             /*
              * Blocks are going to be removed from the inode. Wait
              * for dio in flight.
              */
             inode_dio_wait(inode);
         }
 
         filemap_invalidate_lock(inode->i_mapping);
 
         rc = ext4_break_layouts(inode);
         if (rc) {
             filemap_invalidate_unlock(inode->i_mapping);
             goto err_out;
         }
 
         if (attr->ia_size != inode->i_size) {
             handle = ext4_journal_start(inode, EXT4_HT_INODE, 3);
             if (IS_ERR(handle)) {
                 error = PTR_ERR(handle);
                 goto out_mmap_sem;
             }
             if (ext4_handle_valid(handle) && shrink) {
                 error = ext4_orphan_add(handle, inode);
                 orphan = 1;
             }
             /*
              * Update c/mtime on truncate up, ext4_truncate() will
              * update c/mtime in shrink case below
              */
             if (!shrink) {
                 inode->i_mtime = current_time(inode);
                 inode->i_ctime = inode->i_mtime;
             }
 
             if (shrink)
                 ext4_fc_track_range(handle, inode,
                     (attr->ia_size > 0 ? attr->ia_size - 1 : 0) >>
                     inode->i_sb->s_blocksize_bits,
                     EXT_MAX_BLOCKS - 1);
             else
                 ext4_fc_track_range(
                     handle, inode,
                     (oldsize > 0 ? oldsize - 1 : oldsize) >>
                     inode->i_sb->s_blocksize_bits,
                     (attr->ia_size > 0 ? attr->ia_size - 1 : 0) >>
                     inode->i_sb->s_blocksize_bits);
 
             down_write(&EXT4_I(inode)->i_data_sem);
             old_disksize = EXT4_I(inode)->i_disksize;
             EXT4_I(inode)->i_disksize = attr->ia_size;
             rc = ext4_mark_inode_dirty(handle, inode);
             if (!error)
                 error = rc;
             /*
              * We have to update i_size under i_data_sem together
              * with i_disksize to avoid races with writeback code
              * running ext4_wb_update_i_disksize().
              */
             if (!error)
                 i_size_write(inode, attr->ia_size);
             else
                 EXT4_I(inode)->i_disksize = old_disksize;
             up_write(&EXT4_I(inode)->i_data_sem);
             ext4_journal_stop(handle);
             if (error)
                 goto out_mmap_sem;
             if (!shrink) {
                 pagecache_isize_extended(inode, oldsize,
                              inode->i_size);
             } else if (ext4_should_journal_data(inode)) {
                 ext4_wait_for_tail_page_commit(inode);
             }
         }
 
         /*
          * Truncate pagecache after we've waited for commit
          * in data=journal mode to make pages freeable.
          */
         truncate_pagecache(inode, inode->i_size);
         /*
          * Call ext4_truncate() even if i_size didn't change to
          * truncate possible preallocated blocks.
          */
         if (attr->ia_size <= oldsize) {
             rc = ext4_truncate(inode);
             if (rc)
                 error = rc;
         }
 out_mmap_sem:
         filemap_invalidate_unlock(inode->i_mapping);
     }
 
     if (!error) {
         setattr_copy(mnt_userns, inode, attr);
         mark_inode_dirty(inode);
     }
 
     /*
      * If the call to ext4_truncate failed to get a transaction handle at
      * all, we need to clean up the in-core orphan list manually.
      */
     if (orphan && inode->i_nlink)
         ext4_orphan_del(NULL, inode);
 
     if (!error && (ia_valid & ATTR_MODE))
         rc = posix_acl_chmod(mnt_userns, inode, inode->i_mode);
 
 err_out:
     if  (error)
         ext4_std_error(inode->i_sb, error);
     if (!error)
         error = rc;
     return error;
 }
 
 int ext4_getattr(struct user_namespace *mnt_userns, const struct path *path,
          struct kstat *stat, u32 request_mask, unsigned int query_flags)
 {
     struct inode *inode = d_inode(path->dentry);
     struct ext4_inode *raw_inode;
     struct ext4_inode_info *ei = EXT4_I(inode);
     unsigned int flags;
 
     if ((request_mask & STATX_BTIME) &&
         EXT4_FITS_IN_INODE(raw_inode, ei, i_crtime)) {
         stat->result_mask |= STATX_BTIME;
         stat->btime.tv_sec = ei->i_crtime.tv_sec;
         stat->btime.tv_nsec = ei->i_crtime.tv_nsec;
     }
 
     flags = ei->i_flags & EXT4_FL_USER_VISIBLE;
     if (flags & EXT4_APPEND_FL)
         stat->attributes |= STATX_ATTR_APPEND;
     if (flags & EXT4_COMPR_FL)
         stat->attributes |= STATX_ATTR_COMPRESSED;
     if (flags & EXT4_ENCRYPT_FL)
         stat->attributes |= STATX_ATTR_ENCRYPTED;
     if (flags & EXT4_IMMUTABLE_FL)
         stat->attributes |= STATX_ATTR_IMMUTABLE;
     if (flags & EXT4_NODUMP_FL)
         stat->attributes |= STATX_ATTR_NODUMP;
     if (flags & EXT4_VERITY_FL)
         stat->attributes |= STATX_ATTR_VERITY;
 
     stat->attributes_mask |= (STATX_ATTR_APPEND |
                   STATX_ATTR_COMPRESSED |
                   STATX_ATTR_ENCRYPTED |
                   STATX_ATTR_IMMUTABLE |
                   STATX_ATTR_NODUMP |
                   STATX_ATTR_VERITY);
 
     generic_fillattr(mnt_userns, inode, stat);
     return 0;
 }
 
 int ext4_file_getattr(struct user_namespace *mnt_userns,
               const struct path *path, struct kstat *stat,
               u32 request_mask, unsigned int query_flags)
 {
     struct inode *inode = d_inode(path->dentry);
     u64 delalloc_blocks;
 
     ext4_getattr(mnt_userns, path, stat, request_mask, query_flags);
 
     /*
      * If there is inline data in the inode, the inode will normally not
      * have data blocks allocated (it may have an external xattr block).
      * Report at least one sector for such files, so tools like tar, rsync,
      * others don't incorrectly think the file is completely sparse.
      */
     if (unlikely(ext4_has_inline_data(inode)))
         stat->blocks += (stat->size + 511) >> 9;
 
     /*
      * We can't update i_blocks if the block allocation is delayed
      * otherwise in the case of system crash before the real block
      * allocation is done, we will have i_blocks inconsistent with
      * on-disk file blocks.
      * We always keep i_blocks updated together with real
      * allocation. But to not confuse with user, stat
      * will return the blocks that include the delayed allocation
      * blocks for this file.
      */
     delalloc_blocks = EXT4_C2B(EXT4_SB(inode->i_sb),
                    EXT4_I(inode)->i_reserved_data_blocks);
     stat->blocks += delalloc_blocks << (inode->i_sb->s_blocksize_bits - 9);
     return 0;
 }
 
 static int ext4_index_trans_blocks(struct inode *inode, int lblocks,
                    int pextents)
 {
     if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
         return ext4_ind_trans_blocks(inode, lblocks);
     return ext4_ext_index_trans_blocks(inode, pextents);
 }
 
 /*
  * Account for index blocks, block groups bitmaps and block group
  * descriptor blocks if modify datablocks and index blocks
  * worse case, the indexs blocks spread over different block groups
  *
  * If datablocks are discontiguous, they are possible to spread over
  * different block groups too. If they are contiguous, with flexbg,
  * they could still across block group boundary.
  *
  * Also account for superblock, inode, quota and xattr blocks
  */
 static int ext4_meta_trans_blocks(struct inode *inode, int lblocks,
                   int pextents)
 {
     ext4_group_t groups, ngroups = ext4_get_groups_count(inode->i_sb);
     int gdpblocks;
     int idxblocks;
     int ret = 0;
 
     /*
      * How many index blocks need to touch to map @lblocks logical blocks
      * to @pextents physical extents?
      */
     idxblocks = ext4_index_trans_blocks(inode, lblocks, pextents);
 
     ret = idxblocks;
 
     /*
      * Now let's see how many group bitmaps and group descriptors need
      * to account
      */
     groups = idxblocks + pextents;
     gdpblocks = groups;
     if (groups > ngroups)
         groups = ngroups;
     if (groups > EXT4_SB(inode->i_sb)->s_gdb_count)
         gdpblocks = EXT4_SB(inode->i_sb)->s_gdb_count;
 
     /* bitmaps and block group descriptor blocks */
     ret += groups + gdpblocks;
 
     /* Blocks for super block, inode, quota and xattr blocks */
     ret += EXT4_META_TRANS_BLOCKS(inode->i_sb);
 
     return ret;
 }
 
 /*
  * Calculate the total number of credits to reserve to fit
  * the modification of a single pages into a single transaction,
  * which may include multiple chunks of block allocations.
  *
  * This could be called via ext4_write_begin()
  *
  * We need to consider the worse case, when
  * one new block per extent.
  */
 int ext4_writepage_trans_blocks(struct inode *inode)
 {
     int bpp = ext4_journal_blocks_per_page(inode);
     int ret;
 
     ret = ext4_meta_trans_blocks(inode, bpp, bpp);
 
     /* Account for data blocks for journalled mode */
     if (ext4_should_journal_data(inode))
         ret += bpp;
     return ret;
 }
 
 /*
  * Calculate the journal credits for a chunk of data modification.
  *
  * This is called from DIO, fallocate or whoever calling
  * ext4_map_blocks() to map/allocate a chunk of contiguous disk blocks.
  *
  * journal buffers for data blocks are not included here, as DIO
  * and fallocate do no need to journal data buffers.
  */
 int ext4_chunk_trans_blocks(struct inode *inode, int nrblocks)
 {
     return ext4_meta_trans_blocks(inode, nrblocks, 1);
 }
 
 /*
  * The caller must have previously called ext4_reserve_inode_write().
  * Give this, we know that the caller already has write access to iloc->bh.
  */
 int ext4_mark_iloc_dirty(handle_t *handle,
              struct inode *inode, struct ext4_iloc *iloc)
 {
     int err = 0;
 
     if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb)))) {
         put_bh(iloc->bh);
         return -EIO;
     }
     ext4_fc_track_inode(handle, inode);
 
     if (IS_I_VERSION(inode))
         inode_inc_iversion(inode);
 
     /* the do_update_inode consumes one bh->b_count */
     get_bh(iloc->bh);
 
     /* ext4_do_update_inode() does jbd2_journal_dirty_metadata */
     err = ext4_do_update_inode(handle, inode, iloc);
     put_bh(iloc->bh);
     return err;
 }
 
 /*
  * On success, We end up with an outstanding reference count against
  * iloc->bh.  This _must_ be cleaned up later.
  */
 
 int
 ext4_reserve_inode_write(handle_t *handle, struct inode *inode,
              struct ext4_iloc *iloc)
 {
     int err;
 
     if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
         return -EIO;
 
     err = ext4_get_inode_loc(inode, iloc);
     if (!err) {
         BUFFER_TRACE(iloc->bh, "get_write_access");
         err = ext4_journal_get_write_access(handle, inode->i_sb,
                             iloc->bh, EXT4_JTR_NONE);
         if (err) {
             brelse(iloc->bh);
             iloc->bh = NULL;
         }
     }
     ext4_std_error(inode->i_sb, err);
     return err;
 }
 
 static int __ext4_expand_extra_isize(struct inode *inode,
                      unsigned int new_extra_isize,
                      struct ext4_iloc *iloc,
                      handle_t *handle, int *no_expand)
 {
     struct ext4_inode *raw_inode;
     struct ext4_xattr_ibody_header *header;
     unsigned int inode_size = EXT4_INODE_SIZE(inode->i_sb);
     struct ext4_inode_info *ei = EXT4_I(inode);
     int error;
 
     /* this was checked at iget time, but double check for good measure */
     if ((EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize > inode_size) ||
         (ei->i_extra_isize & 3)) {
         EXT4_ERROR_INODE(inode, "bad extra_isize %u (inode size %u)",
                  ei->i_extra_isize,
                  EXT4_INODE_SIZE(inode->i_sb));
         return -EFSCORRUPTED;
     }
     if ((new_extra_isize < ei->i_extra_isize) ||
         (new_extra_isize < 4) ||
         (new_extra_isize > inode_size - EXT4_GOOD_OLD_INODE_SIZE))
         return -EINVAL; /* Should never happen */
 
     raw_inode = ext4_raw_inode(iloc);
 
     header = IHDR(inode, raw_inode);
 
     /* No extended attributes present */
     if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR) ||
         header->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC)) {
         memset((void *)raw_inode + EXT4_GOOD_OLD_INODE_SIZE +
                EXT4_I(inode)->i_extra_isize, 0,
                new_extra_isize - EXT4_I(inode)->i_extra_isize);
         EXT4_I(inode)->i_extra_isize = new_extra_isize;
         return 0;
     }
 
     /* try to expand with EAs present */
     error = ext4_expand_extra_isize_ea(inode, new_extra_isize,
                        raw_inode, handle);
     if (error) {
         /*
          * Inode size expansion failed; don't try again
          */
         *no_expand = 1;
     }
 
     return error;
 }
 
 /*
  * Expand an inode by new_extra_isize bytes.
  * Returns 0 on success or negative error number on failure.
  */
 static int ext4_try_to_expand_extra_isize(struct inode *inode,
                       unsigned int new_extra_isize,
                       struct ext4_iloc iloc,
                       handle_t *handle)
 {
     int no_expand;
     int error;
 
     if (ext4_test_inode_state(inode, EXT4_STATE_NO_EXPAND))
         return -EOVERFLOW;
 
     /*
      * In nojournal mode, we can immediately attempt to expand
      * the inode.  When journaled, we first need to obtain extra
      * buffer credits since we may write into the EA block
      * with this same handle. If journal_extend fails, then it will
      * only result in a minor loss of functionality for that inode.
      * If this is felt to be critical, then e2fsck should be run to
      * force a large enough s_min_extra_isize.
      */
     if (ext4_journal_extend(handle,
                 EXT4_DATA_TRANS_BLOCKS(inode->i_sb), 0) != 0)
         return -ENOSPC;
 
     if (ext4_write_trylock_xattr(inode, &no_expand) == 0)
         return -EBUSY;
 
     error = __ext4_expand_extra_isize(inode, new_extra_isize, &iloc,
                       handle, &no_expand);
     ext4_write_unlock_xattr(inode, &no_expand);
 
     return error;
 }
 
 int ext4_expand_extra_isize(struct inode *inode,
                 unsigned int new_extra_isize,
                 struct ext4_iloc *iloc)
 {
     handle_t *handle;
     int no_expand;
     int error, rc;
 
     if (ext4_test_inode_state(inode, EXT4_STATE_NO_EXPAND)) {
         brelse(iloc->bh);
         return -EOVERFLOW;
     }
 
     handle = ext4_journal_start(inode, EXT4_HT_INODE,
                     EXT4_DATA_TRANS_BLOCKS(inode->i_sb));
     if (IS_ERR(handle)) {
         error = PTR_ERR(handle);
         brelse(iloc->bh);
         return error;
     }
 
     ext4_write_lock_xattr(inode, &no_expand);
 
     BUFFER_TRACE(iloc->bh, "get_write_access");
     error = ext4_journal_get_write_access(handle, inode->i_sb, iloc->bh,
                           EXT4_JTR_NONE);
     if (error) {
         brelse(iloc->bh);
         goto out_unlock;
     }
 
     error = __ext4_expand_extra_isize(inode, new_extra_isize, iloc,
                       handle, &no_expand);
 
     rc = ext4_mark_iloc_dirty(handle, inode, iloc);
     if (!error)
         error = rc;
 
 out_unlock:
     ext4_write_unlock_xattr(inode, &no_expand);
     ext4_journal_stop(handle);
     return error;
 }
 
 /*
  * What we do here is to mark the in-core inode as clean with respect to inode
  * dirtiness (it may still be data-dirty).
  * This means that the in-core inode may be reaped by prune_icache
  * without having to perform any I/O.  This is a very good thing,
  * because *any* task may call prune_icache - even ones which
  * have a transaction open against a different journal.
  *
  * Is this cheating?  Not really.  Sure, we haven't written the
  * inode out, but prune_icache isn't a user-visible syncing function.
  * Whenever the user wants stuff synced (sys_sync, sys_msync, sys_fsync)
  * we start and wait on commits.
  */
 int __ext4_mark_inode_dirty(handle_t *handle, struct inode *inode,
                 const char *func, unsigned int line)
 {
     struct ext4_iloc iloc;
     struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
     int err;
 
     might_sleep();
     trace_ext4_mark_inode_dirty(inode, _RET_IP_);
     err = ext4_reserve_inode_write(handle, inode, &iloc);
     if (err)
         goto out;
 
     if (EXT4_I(inode)->i_extra_isize < sbi->s_want_extra_isize)
         ext4_try_to_expand_extra_isize(inode, sbi->s_want_extra_isize,
                            iloc, handle);
 
     err = ext4_mark_iloc_dirty(handle, inode, &iloc);
 out:
     if (unlikely(err))
         ext4_error_inode_err(inode, func, line, 0, err,
                     "mark_inode_dirty error");
     return err;
 }
 
 /*
  * ext4_dirty_inode() is called from __mark_inode_dirty()
  *
  * We're really interested in the case where a file is being extended.
  * i_size has been changed by generic_commit_write() and we thus need
  * to include the updated inode in the current transaction.
  *
  * Also, dquot_alloc_block() will always dirty the inode when blocks
  * are allocated to the file.
  *
  * If the inode is marked synchronous, we don't honour that here - doing
  * so would cause a commit on atime updates, which we don't bother doing.
  * We handle synchronous inodes at the highest possible level.
  */
 void ext4_dirty_inode(struct inode *inode, int flags)
 {
     handle_t *handle;
 
     handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
     if (IS_ERR(handle))
         return;
     ext4_mark_inode_dirty(handle, inode);
     ext4_journal_stop(handle);
 }
 
 int ext4_change_inode_journal_flag(struct inode *inode, int val)
 {
     journal_t *journal;
     handle_t *handle;
     int err;
     struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 
     /*
      * We have to be very careful here: changing a data block's
      * journaling status dynamically is dangerous.  If we write a
      * data block to the journal, change the status and then delete
      * that block, we risk forgetting to revoke the old log record
      * from the journal and so a subsequent replay can corrupt data.
      * So, first we make sure that the journal is empty and that
      * nobody is changing anything.
      */
 
     journal = EXT4_JOURNAL(inode);
     if (!journal)
         return 0;
     if (is_journal_aborted(journal))
         return -EROFS;
 
     /* Wait for all existing dio workers */
     inode_dio_wait(inode);
 
     /*
      * Before flushing the journal and switching inode's aops, we have
      * to flush all dirty data the inode has. There can be outstanding
      * delayed allocations, there can be unwritten extents created by
      * fallocate or buffered writes in dioread_nolock mode covered by
      * dirty data which can be converted only after flushing the dirty
      * data (and journalled aops don't know how to handle these cases).
      */
     if (val) {
         filemap_invalidate_lock(inode->i_mapping);
         err = filemap_write_and_wait(inode->i_mapping);
         if (err < 0) {
             filemap_invalidate_unlock(inode->i_mapping);
             return err;
         }
     }
 
     percpu_down_write(&sbi->s_writepages_rwsem);
     jbd2_journal_lock_updates(journal);
 
     /*
      * OK, there are no updates running now, and all cached data is
      * synced to disk.  We are now in a completely consistent state
      * which doesn't have anything in the journal, and we know that
      * no filesystem updates are running, so it is safe to modify
      * the inode's in-core data-journaling state flag now.
      */
 
     if (val)
         ext4_set_inode_flag(inode, EXT4_INODE_JOURNAL_DATA);
     else {
         err = jbd2_journal_flush(journal, 0);
         if (err < 0) {
             jbd2_journal_unlock_updates(journal);
             percpu_up_write(&sbi->s_writepages_rwsem);
             return err;
         }
         ext4_clear_inode_flag(inode, EXT4_INODE_JOURNAL_DATA);
     }
     ext4_set_aops(inode);
 
     jbd2_journal_unlock_updates(journal);
     percpu_up_write(&sbi->s_writepages_rwsem);
 
     if (val)
         filemap_invalidate_unlock(inode->i_mapping);
 
     /* Finally we can mark the inode as dirty. */
 
     handle = ext4_journal_start(inode, EXT4_HT_INODE, 1);
     if (IS_ERR(handle))
         return PTR_ERR(handle);
 
     ext4_fc_mark_ineligible(inode->i_sb,
         EXT4_FC_REASON_JOURNAL_FLAG_CHANGE, handle);
     err = ext4_mark_inode_dirty(handle, inode);
     ext4_handle_sync(handle);
     ext4_journal_stop(handle);
     ext4_std_error(inode->i_sb, err);
 
     return err;
 }
 
 static int ext4_bh_unmapped(handle_t *handle, struct inode *inode,
                 struct buffer_head *bh)
 {
     return !buffer_mapped(bh);
 }
 
 vm_fault_t ext4_page_mkwrite(struct vm_fault *vmf)
 {
     struct vm_area_struct *vma = vmf->vma;
     struct page *page = vmf->page;
     loff_t size;
     unsigned long len;
     int err;
     vm_fault_t ret;
     struct file *file = vma->vm_file;
     struct inode *inode = file_inode(file);
     struct address_space *mapping = inode->i_mapping;
     handle_t *handle;
     get_block_t *get_block;
     int retries = 0;
 
     if (unlikely(IS_IMMUTABLE(inode)))
         return VM_FAULT_SIGBUS;
 
     sb_start_pagefault(inode->i_sb);
     file_update_time(vma->vm_file);
 
     filemap_invalidate_lock_shared(mapping);
 
     err = ext4_convert_inline_data(inode);
     if (err)
         goto out_ret;
 
     /*
      * On data journalling we skip straight to the transaction handle:
      * there's no delalloc; page truncated will be checked later; the
      * early return w/ all buffers mapped (calculates size/len) can't
      * be used; and there's no dioread_nolock, so only ext4_get_block.
      */
     if (ext4_should_journal_data(inode))
         goto retry_alloc;
 
     /* Delalloc case is easy... */
     if (test_opt(inode->i_sb, DELALLOC) &&
         !ext4_nonda_switch(inode->i_sb)) {
         do {
             err = block_page_mkwrite(vma, vmf,
                            ext4_da_get_block_prep);
         } while (err == -ENOSPC &&
                ext4_should_retry_alloc(inode->i_sb, &retries));
         goto out_ret;
     }
 
     lock_page(page);
     size = i_size_read(inode);
     /* Page got truncated from under us? */
     if (page->mapping != mapping || page_offset(page) > size) {
         unlock_page(page);
         ret = VM_FAULT_NOPAGE;
         goto out;
     }
 
     if (page->index == size >> PAGE_SHIFT)
         len = size & ~PAGE_MASK;
     else
         len = PAGE_SIZE;
     /*
      * Return if we have all the buffers mapped. This avoids the need to do
      * journal_start/journal_stop which can block and take a long time
      *
      * This cannot be done for data journalling, as we have to add the
      * inode to the transaction's list to writeprotect pages on commit.
      */
     if (page_has_buffers(page)) {
         if (!ext4_walk_page_buffers(NULL, inode, page_buffers(page),
                         0, len, NULL,
                         ext4_bh_unmapped)) {
             /* Wait so that we don't change page under IO */
             wait_for_stable_page(page);
             ret = VM_FAULT_LOCKED;
             goto out;
         }
     }
     unlock_page(page);
     /* OK, we need to fill the hole... */
     if (ext4_should_dioread_nolock(inode))
         get_block = ext4_get_block_unwritten;
     else
         get_block = ext4_get_block;
 retry_alloc:
     handle = ext4_journal_start(inode, EXT4_HT_WRITE_PAGE,
                     ext4_writepage_trans_blocks(inode));
     if (IS_ERR(handle)) {
         ret = VM_FAULT_SIGBUS;
         goto out;
     }
     /*
      * Data journalling can't use block_page_mkwrite() because it
      * will set_buffer_dirty() before do_journal_get_write_access()
      * thus might hit warning messages for dirty metadata buffers.
      */
     if (!ext4_should_journal_data(inode)) {
         err = block_page_mkwrite(vma, vmf, get_block);
     } else {
         lock_page(page);
         size = i_size_read(inode);
         /* Page got truncated from under us? */
         if (page->mapping != mapping || page_offset(page) > size) {
             ret = VM_FAULT_NOPAGE;
             goto out_error;
         }
 
         if (page->index == size >> PAGE_SHIFT)
             len = size & ~PAGE_MASK;
         else
             len = PAGE_SIZE;
 
         err = __block_write_begin(page, 0, len, ext4_get_block);
         if (!err) {
             ret = VM_FAULT_SIGBUS;
             if (ext4_walk_page_buffers(handle, inode,
                     page_buffers(page), 0, len, NULL,
                     do_journal_get_write_access))
                 goto out_error;
             if (ext4_walk_page_buffers(handle, inode,
                     page_buffers(page), 0, len, NULL,
                     write_end_fn))
                 goto out_error;
             if (ext4_jbd2_inode_add_write(handle, inode,
                               page_offset(page), len))
                 goto out_error;
             ext4_set_inode_state(inode, EXT4_STATE_JDATA);
         } else {
             unlock_page(page);
         }
     }
     ext4_journal_stop(handle);
     if (err == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
         goto retry_alloc;
 out_ret:
     ret = block_page_mkwrite_return(err);
 out:
     filemap_invalidate_unlock_shared(mapping);
     sb_end_pagefault(inode->i_sb);
     return ret;
 out_error:
     unlock_page(page);
     ext4_journal_stop(handle);
     goto out;
 }