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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/file.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/file.c
  *
  *  Copyright (C) 1991, 1992  Linus Torvalds
  *
  *  ext4 fs regular file handling primitives
  *
  *  64-bit file support on 64-bit platforms by Jakub Jelinek
  *  (jj@sunsite.ms.mff.cuni.cz)
  */
 
 #include <linux/time.h>
 #include <linux/fs.h>
 #include <linux/iomap.h>
 #include <linux/mount.h>
 #include <linux/path.h>
 #include <linux/dax.h>
 #include <linux/quotaops.h>
 #include <linux/pagevec.h>
 #include <linux/uio.h>
 #include <linux/mman.h>
 #include <linux/backing-dev.h>
 #include "ext4.h"
 #include "ext4_jbd2.h"
 #include "xattr.h"
 #include "acl.h"
 #include "truncate.h"
 
 static bool ext4_dio_supported(struct kiocb *iocb, struct iov_iter *iter)
 {
     struct inode *inode = file_inode(iocb->ki_filp);
 
     if (!fscrypt_dio_supported(iocb, iter))
         return false;
     if (fsverity_active(inode))
         return false;
     if (ext4_should_journal_data(inode))
         return false;
     if (ext4_has_inline_data(inode))
         return false;
     return true;
 }
 
 static ssize_t ext4_dio_read_iter(struct kiocb *iocb, struct iov_iter *to)
 {
     ssize_t ret;
     struct inode *inode = file_inode(iocb->ki_filp);
 
     if (iocb->ki_flags & IOCB_NOWAIT) {
         if (!inode_trylock_shared(inode))
             return -EAGAIN;
     } else {
         inode_lock_shared(inode);
     }
 
     if (!ext4_dio_supported(iocb, to)) {
         inode_unlock_shared(inode);
         /*
          * Fallback to buffered I/O if the operation being performed on
          * the inode is not supported by direct I/O. The IOCB_DIRECT
          * flag needs to be cleared here in order to ensure that the
          * direct I/O path within generic_file_read_iter() is not
          * taken.
          */
         iocb->ki_flags &= ~IOCB_DIRECT;
         return generic_file_read_iter(iocb, to);
     }
 
     ret = iomap_dio_rw(iocb, to, &ext4_iomap_ops, NULL, 0, NULL, 0);
     inode_unlock_shared(inode);
 
     file_accessed(iocb->ki_filp);
     return ret;
 }
 
 #ifdef CONFIG_FS_DAX
 static ssize_t ext4_dax_read_iter(struct kiocb *iocb, struct iov_iter *to)
 {
     struct inode *inode = file_inode(iocb->ki_filp);
     ssize_t ret;
 
     if (iocb->ki_flags & IOCB_NOWAIT) {
         if (!inode_trylock_shared(inode))
             return -EAGAIN;
     } else {
         inode_lock_shared(inode);
     }
     /*
      * Recheck under inode lock - at this point we are sure it cannot
      * change anymore
      */
     if (!IS_DAX(inode)) {
         inode_unlock_shared(inode);
         /* Fallback to buffered IO in case we cannot support DAX */
         return generic_file_read_iter(iocb, to);
     }
     ret = dax_iomap_rw(iocb, to, &ext4_iomap_ops);
     inode_unlock_shared(inode);
 
     file_accessed(iocb->ki_filp);
     return ret;
 }
 #endif
 
 static ssize_t ext4_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
 {
     struct inode *inode = file_inode(iocb->ki_filp);
 
     if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
         return -EIO;
 
     if (!iov_iter_count(to))
         return 0; /* skip atime */
 
 #ifdef CONFIG_FS_DAX
     if (IS_DAX(inode))
         return ext4_dax_read_iter(iocb, to);
 #endif
     if (iocb->ki_flags & IOCB_DIRECT)
         return ext4_dio_read_iter(iocb, to);
 
     return generic_file_read_iter(iocb, to);
 }
 
 /*
  * Called when an inode is released. Note that this is different
  * from ext4_file_open: open gets called at every open, but release
  * gets called only when /all/ the files are closed.
  */
 static int ext4_release_file(struct inode *inode, struct file *filp)
 {
     if (ext4_test_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE)) {
         ext4_alloc_da_blocks(inode);
         ext4_clear_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE);
     }
     /* if we are the last writer on the inode, drop the block reservation */
     if ((filp->f_mode & FMODE_WRITE) &&
             (atomic_read(&inode->i_writecount) == 1) &&
             !EXT4_I(inode)->i_reserved_data_blocks) {
         down_write(&EXT4_I(inode)->i_data_sem);
         ext4_discard_preallocations(inode, 0);
         up_write(&EXT4_I(inode)->i_data_sem);
     }
     if (is_dx(inode) && filp->private_data)
         ext4_htree_free_dir_info(filp->private_data);
 
     return 0;
 }
 
 /*
  * This tests whether the IO in question is block-aligned or not.
  * Ext4 utilizes unwritten extents when hole-filling during direct IO, and they
  * are converted to written only after the IO is complete.  Until they are
  * mapped, these blocks appear as holes, so dio_zero_block() will assume that
  * it needs to zero out portions of the start and/or end block.  If 2 AIO
  * threads are at work on the same unwritten block, they must be synchronized
  * or one thread will zero the other's data, causing corruption.
  */
 static bool
 ext4_unaligned_io(struct inode *inode, struct iov_iter *from, loff_t pos)
 {
     struct super_block *sb = inode->i_sb;
     unsigned long blockmask = sb->s_blocksize - 1;
 
     if ((pos | iov_iter_alignment(from)) & blockmask)
         return true;
 
     return false;
 }
 
 static bool
 ext4_extending_io(struct inode *inode, loff_t offset, size_t len)
 {
     if (offset + len > i_size_read(inode) ||
         offset + len > EXT4_I(inode)->i_disksize)
         return true;
     return false;
 }
 
 /* Is IO overwriting allocated and initialized blocks? */
 static bool ext4_overwrite_io(struct inode *inode, loff_t pos, loff_t len)
 {
     struct ext4_map_blocks map;
     unsigned int blkbits = inode->i_blkbits;
     int err, blklen;
 
     if (pos + len > i_size_read(inode))
         return false;
 
     map.m_lblk = pos >> blkbits;
     map.m_len = EXT4_MAX_BLOCKS(len, pos, blkbits);
     blklen = map.m_len;
 
     err = ext4_map_blocks(NULL, inode, &map, 0);
     /*
      * 'err==len' means that all of the blocks have been preallocated,
      * regardless of whether they have been initialized or not. To exclude
      * unwritten extents, we need to check m_flags.
      */
     return err == blklen && (map.m_flags & EXT4_MAP_MAPPED);
 }
 
 static ssize_t ext4_generic_write_checks(struct kiocb *iocb,
                      struct iov_iter *from)
 {
     struct inode *inode = file_inode(iocb->ki_filp);
     ssize_t ret;
 
     if (unlikely(IS_IMMUTABLE(inode)))
         return -EPERM;
 
     ret = generic_write_checks(iocb, from);
     if (ret <= 0)
         return ret;
 
     /*
      * If we have encountered a bitmap-format file, the size limit
      * is smaller than s_maxbytes, which is for extent-mapped files.
      */
     if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
 
         if (iocb->ki_pos >= sbi->s_bitmap_maxbytes)
             return -EFBIG;
         iov_iter_truncate(from, sbi->s_bitmap_maxbytes - iocb->ki_pos);
     }
 
     return iov_iter_count(from);
 }
 
 static ssize_t ext4_write_checks(struct kiocb *iocb, struct iov_iter *from)
 {
     ssize_t ret, count;
 
     count = ext4_generic_write_checks(iocb, from);
     if (count <= 0)
         return count;
 
     ret = file_modified(iocb->ki_filp);
     if (ret)
         return ret;
     return count;
 }
 
 static ssize_t ext4_buffered_write_iter(struct kiocb *iocb,
                     struct iov_iter *from)
 {
     ssize_t ret;
     struct inode *inode = file_inode(iocb->ki_filp);
 
     if (iocb->ki_flags & IOCB_NOWAIT)
         return -EOPNOTSUPP;
 
     inode_lock(inode);
     ret = ext4_write_checks(iocb, from);
     if (ret <= 0)
         goto out;
 
     current->backing_dev_info = inode_to_bdi(inode);
     ret = generic_perform_write(iocb, from);
     current->backing_dev_info = NULL;
 
 out:
     inode_unlock(inode);
     if (likely(ret > 0)) {
         iocb->ki_pos += ret;
         ret = generic_write_sync(iocb, ret);
     }
 
     return ret;
 }
 
 static ssize_t ext4_handle_inode_extension(struct inode *inode, loff_t offset,
                        ssize_t written, size_t count)
 {
     handle_t *handle;
     bool truncate = false;
     u8 blkbits = inode->i_blkbits;
     ext4_lblk_t written_blk, end_blk;
     int ret;
 
     /*
      * Note that EXT4_I(inode)->i_disksize can get extended up to
      * inode->i_size while the I/O was running due to writeback of delalloc
      * blocks. But, the code in ext4_iomap_alloc() is careful to use
      * zeroed/unwritten extents if this is possible; thus we won't leave
      * uninitialized blocks in a file even if we didn't succeed in writing
      * as much as we intended.
      */
     WARN_ON_ONCE(i_size_read(inode) < EXT4_I(inode)->i_disksize);
     if (offset + count <= EXT4_I(inode)->i_disksize) {
         /*
          * We need to ensure that the inode is removed from the orphan
          * list if it has been added prematurely, due to writeback of
          * delalloc blocks.
          */
         if (!list_empty(&EXT4_I(inode)->i_orphan) && inode->i_nlink) {
             handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
 
             if (IS_ERR(handle)) {
                 ext4_orphan_del(NULL, inode);
                 return PTR_ERR(handle);
             }
 
             ext4_orphan_del(handle, inode);
             ext4_journal_stop(handle);
         }
 
         return written;
     }
 
     if (written < 0)
         goto truncate;
 
     handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
     if (IS_ERR(handle)) {
         written = PTR_ERR(handle);
         goto truncate;
     }
 
     if (ext4_update_inode_size(inode, offset + written)) {
         ret = ext4_mark_inode_dirty(handle, inode);
         if (unlikely(ret)) {
             written = ret;
             ext4_journal_stop(handle);
             goto truncate;
         }
     }
 
     /*
      * We may need to truncate allocated but not written blocks beyond EOF.
      */
     written_blk = ALIGN(offset + written, 1 << blkbits);
     end_blk = ALIGN(offset + count, 1 << blkbits);
     if (written_blk < end_blk && ext4_can_truncate(inode))
         truncate = true;
 
     /*
      * Remove the inode from the orphan list if it has been extended and
      * everything went OK.
      */
     if (!truncate && inode->i_nlink)
         ext4_orphan_del(handle, inode);
     ext4_journal_stop(handle);
 
     if (truncate) {
 truncate:
         ext4_truncate_failed_write(inode);
         /*
          * If the truncate operation failed early, then the inode may
          * still be on the orphan list. In that case, we need to try
          * remove the inode from the in-memory linked list.
          */
         if (inode->i_nlink)
             ext4_orphan_del(NULL, inode);
     }
 
     return written;
 }
 
 static int ext4_dio_write_end_io(struct kiocb *iocb, ssize_t size,
                  int error, unsigned int flags)
 {
     loff_t pos = iocb->ki_pos;
     struct inode *inode = file_inode(iocb->ki_filp);
 
     if (error)
         return error;
 
     if (size && flags & IOMAP_DIO_UNWRITTEN) {
         error = ext4_convert_unwritten_extents(NULL, inode, pos, size);
         if (error < 0)
             return error;
     }
     /*
      * If we are extending the file, we have to update i_size here before
      * page cache gets invalidated in iomap_dio_rw(). Otherwise racing
      * buffered reads could zero out too much from page cache pages. Update
      * of on-disk size will happen later in ext4_dio_write_iter() where
      * we have enough information to also perform orphan list handling etc.
      * Note that we perform all extending writes synchronously under
      * i_rwsem held exclusively so i_size update is safe here in that case.
      * If the write was not extending, we cannot see pos > i_size here
      * because operations reducing i_size like truncate wait for all
      * outstanding DIO before updating i_size.
      */
     pos += size;
     if (pos > i_size_read(inode))
         i_size_write(inode, pos);
 
     return 0;
 }
 
 static const struct iomap_dio_ops ext4_dio_write_ops = {
     .end_io = ext4_dio_write_end_io,
 };
 
 /*
  * The intention here is to start with shared lock acquired then see if any
  * condition requires an exclusive inode lock. If yes, then we restart the
  * whole operation by releasing the shared lock and acquiring exclusive lock.
  *
  * - For unaligned_io we never take shared lock as it may cause data corruption
  *   when two unaligned IO tries to modify the same block e.g. while zeroing.
  *
  * - For extending writes case we don't take the shared lock, since it requires
  *   updating inode i_disksize and/or orphan handling with exclusive lock.
  *
  * - shared locking will only be true mostly with overwrites. Otherwise we will
  *   switch to exclusive i_rwsem lock.
  */
 static ssize_t ext4_dio_write_checks(struct kiocb *iocb, struct iov_iter *from,
                      bool *ilock_shared, bool *extend)
 {
     struct file *file = iocb->ki_filp;
     struct inode *inode = file_inode(file);
     loff_t offset;
     size_t count;
     ssize_t ret;
 
 restart:
     ret = ext4_generic_write_checks(iocb, from);
     if (ret <= 0)
         goto out;
 
     offset = iocb->ki_pos;
     count = ret;
     if (ext4_extending_io(inode, offset, count))
         *extend = true;
     /*
      * Determine whether the IO operation will overwrite allocated
      * and initialized blocks.
      * We need exclusive i_rwsem for changing security info
      * in file_modified().
      */
     if (*ilock_shared && (!IS_NOSEC(inode) || *extend ||
          !ext4_overwrite_io(inode, offset, count))) {
         if (iocb->ki_flags & IOCB_NOWAIT) {
             ret = -EAGAIN;
             goto out;
         }
         inode_unlock_shared(inode);
         *ilock_shared = false;
         inode_lock(inode);
         goto restart;
     }
 
     ret = file_modified(file);
     if (ret < 0)
         goto out;
 
     return count;
 out:
     if (*ilock_shared)
         inode_unlock_shared(inode);
     else
         inode_unlock(inode);
     return ret;
 }
 
 static ssize_t ext4_dio_write_iter(struct kiocb *iocb, struct iov_iter *from)
 {
     ssize_t ret;
     handle_t *handle;
     struct inode *inode = file_inode(iocb->ki_filp);
     loff_t offset = iocb->ki_pos;
     size_t count = iov_iter_count(from);
     const struct iomap_ops *iomap_ops = &ext4_iomap_ops;
     bool extend = false, unaligned_io = false;
     bool ilock_shared = true;
 
     /*
      * We initially start with shared inode lock unless it is
      * unaligned IO which needs exclusive lock anyways.
      */
     if (ext4_unaligned_io(inode, from, offset)) {
         unaligned_io = true;
         ilock_shared = false;
     }
     /*
      * Quick check here without any i_rwsem lock to see if it is extending
      * IO. A more reliable check is done in ext4_dio_write_checks() with
      * proper locking in place.
      */
     if (offset + count > i_size_read(inode))
         ilock_shared = false;
 
     if (iocb->ki_flags & IOCB_NOWAIT) {
         if (ilock_shared) {
             if (!inode_trylock_shared(inode))
                 return -EAGAIN;
         } else {
             if (!inode_trylock(inode))
                 return -EAGAIN;
         }
     } else {
         if (ilock_shared)
             inode_lock_shared(inode);
         else
             inode_lock(inode);
     }
 
     /* Fallback to buffered I/O if the inode does not support direct I/O. */
     if (!ext4_dio_supported(iocb, from)) {
         if (ilock_shared)
             inode_unlock_shared(inode);
         else
             inode_unlock(inode);
         return ext4_buffered_write_iter(iocb, from);
     }
 
     ret = ext4_dio_write_checks(iocb, from, &ilock_shared, &extend);
     if (ret <= 0)
         return ret;
 
     /* if we're going to block and IOCB_NOWAIT is set, return -EAGAIN */
     if ((iocb->ki_flags & IOCB_NOWAIT) && (unaligned_io || extend)) {
         ret = -EAGAIN;
         goto out;
     }
 
     offset = iocb->ki_pos;
     count = ret;
 
     /*
      * Unaligned direct IO must be serialized among each other as zeroing
      * of partial blocks of two competing unaligned IOs can result in data
      * corruption.
      *
      * So we make sure we don't allow any unaligned IO in flight.
      * For IOs where we need not wait (like unaligned non-AIO DIO),
      * below inode_dio_wait() may anyway become a no-op, since we start
      * with exclusive lock.
      */
     if (unaligned_io)
         inode_dio_wait(inode);
 
     if (extend) {
         handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
         if (IS_ERR(handle)) {
             ret = PTR_ERR(handle);
             goto out;
         }
 
         ret = ext4_orphan_add(handle, inode);
         if (ret) {
             ext4_journal_stop(handle);
             goto out;
         }
 
         ext4_journal_stop(handle);
     }
 
     if (ilock_shared)
         iomap_ops = &ext4_iomap_overwrite_ops;
     ret = iomap_dio_rw(iocb, from, iomap_ops, &ext4_dio_write_ops,
                (unaligned_io || extend) ? IOMAP_DIO_FORCE_WAIT : 0,
                NULL, 0);
     if (ret == -ENOTBLK)
         ret = 0;
 
     if (extend)
         ret = ext4_handle_inode_extension(inode, offset, ret, count);
 
 out:
     if (ilock_shared)
         inode_unlock_shared(inode);
     else
         inode_unlock(inode);
 
     if (ret >= 0 && iov_iter_count(from)) {
         ssize_t err;
         loff_t endbyte;
 
         offset = iocb->ki_pos;
         err = ext4_buffered_write_iter(iocb, from);
         if (err < 0)
             return err;
 
         /*
          * We need to ensure that the pages within the page cache for
          * the range covered by this I/O are written to disk and
          * invalidated. This is in attempt to preserve the expected
          * direct I/O semantics in the case we fallback to buffered I/O
          * to complete off the I/O request.
          */
         ret += err;
         endbyte = offset + err - 1;
         err = filemap_write_and_wait_range(iocb->ki_filp->f_mapping,
                            offset, endbyte);
         if (!err)
             invalidate_mapping_pages(iocb->ki_filp->f_mapping,
                          offset >> PAGE_SHIFT,
                          endbyte >> PAGE_SHIFT);
     }
 
     return ret;
 }
 
 #ifdef CONFIG_FS_DAX
 static ssize_t
 ext4_dax_write_iter(struct kiocb *iocb, struct iov_iter *from)
 {
     ssize_t ret;
     size_t count;
     loff_t offset;
     handle_t *handle;
     bool extend = false;
     struct inode *inode = file_inode(iocb->ki_filp);
 
     if (iocb->ki_flags & IOCB_NOWAIT) {
         if (!inode_trylock(inode))
             return -EAGAIN;
     } else {
         inode_lock(inode);
     }
 
     ret = ext4_write_checks(iocb, from);
     if (ret <= 0)
         goto out;
 
     offset = iocb->ki_pos;
     count = iov_iter_count(from);
 
     if (offset + count > EXT4_I(inode)->i_disksize) {
         handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
         if (IS_ERR(handle)) {
             ret = PTR_ERR(handle);
             goto out;
         }
 
         ret = ext4_orphan_add(handle, inode);
         if (ret) {
             ext4_journal_stop(handle);
             goto out;
         }
 
         extend = true;
         ext4_journal_stop(handle);
     }
 
     ret = dax_iomap_rw(iocb, from, &ext4_iomap_ops);
 
     if (extend)
         ret = ext4_handle_inode_extension(inode, offset, ret, count);
 out:
     inode_unlock(inode);
     if (ret > 0)
         ret = generic_write_sync(iocb, ret);
     return ret;
 }
 #endif
 
 static ssize_t
 ext4_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
 {
     struct inode *inode = file_inode(iocb->ki_filp);
 
     if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
         return -EIO;
 
 #ifdef CONFIG_FS_DAX
     if (IS_DAX(inode))
         return ext4_dax_write_iter(iocb, from);
 #endif
     if (iocb->ki_flags & IOCB_DIRECT)
         return ext4_dio_write_iter(iocb, from);
     else
         return ext4_buffered_write_iter(iocb, from);
 }
 
 #ifdef CONFIG_FS_DAX
 static vm_fault_t ext4_dax_huge_fault(struct vm_fault *vmf,
         enum page_entry_size pe_size)
 {
     int error = 0;
     vm_fault_t result;
     int retries = 0;
     handle_t *handle = NULL;
     struct inode *inode = file_inode(vmf->vma->vm_file);
     struct super_block *sb = inode->i_sb;
 
     /*
      * We have to distinguish real writes from writes which will result in a
      * COW page; COW writes should *not* poke the journal (the file will not
      * be changed). Doing so would cause unintended failures when mounted
      * read-only.
      *
      * We check for VM_SHARED rather than vmf->cow_page since the latter is
      * unset for pe_size != PE_SIZE_PTE (i.e. only in do_cow_fault); for
      * other sizes, dax_iomap_fault will handle splitting / fallback so that
      * we eventually come back with a COW page.
      */
     bool write = (vmf->flags & FAULT_FLAG_WRITE) &&
         (vmf->vma->vm_flags & VM_SHARED);
     struct address_space *mapping = vmf->vma->vm_file->f_mapping;
     pfn_t pfn;
 
     if (write) {
         sb_start_pagefault(sb);
         file_update_time(vmf->vma->vm_file);
         filemap_invalidate_lock_shared(mapping);
 retry:
         handle = ext4_journal_start_sb(sb, EXT4_HT_WRITE_PAGE,
                            EXT4_DATA_TRANS_BLOCKS(sb));
         if (IS_ERR(handle)) {
             filemap_invalidate_unlock_shared(mapping);
             sb_end_pagefault(sb);
             return VM_FAULT_SIGBUS;
         }
     } else {
         filemap_invalidate_lock_shared(mapping);
     }
     result = dax_iomap_fault(vmf, pe_size, &pfn, &error, &ext4_iomap_ops);
     if (write) {
         ext4_journal_stop(handle);
 
         if ((result & VM_FAULT_ERROR) && error == -ENOSPC &&
             ext4_should_retry_alloc(sb, &retries))
             goto retry;
         /* Handling synchronous page fault? */
         if (result & VM_FAULT_NEEDDSYNC)
             result = dax_finish_sync_fault(vmf, pe_size, pfn);
         filemap_invalidate_unlock_shared(mapping);
         sb_end_pagefault(sb);
     } else {
         filemap_invalidate_unlock_shared(mapping);
     }
 
     return result;
 }
 
 static vm_fault_t ext4_dax_fault(struct vm_fault *vmf)
 {
     return ext4_dax_huge_fault(vmf, PE_SIZE_PTE);
 }
 
 static const struct vm_operations_struct ext4_dax_vm_ops = {
     .fault      = ext4_dax_fault,
     .huge_fault = ext4_dax_huge_fault,
     .page_mkwrite   = ext4_dax_fault,
     .pfn_mkwrite    = ext4_dax_fault,
 };
 #else
 #define ext4_dax_vm_ops ext4_file_vm_ops
 #endif
 
 static const struct vm_operations_struct ext4_file_vm_ops = {
     .fault      = filemap_fault,
     .map_pages  = filemap_map_pages,
     .page_mkwrite   = ext4_page_mkwrite,
 };
 
 static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
 {
     struct inode *inode = file->f_mapping->host;
     struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
     struct dax_device *dax_dev = sbi->s_daxdev;
 
     if (unlikely(ext4_forced_shutdown(sbi)))
         return -EIO;
 
     /*
      * We don't support synchronous mappings for non-DAX files and
      * for DAX files if underneath dax_device is not synchronous.
      */
     if (!daxdev_mapping_supported(vma, dax_dev))
         return -EOPNOTSUPP;
 
     file_accessed(file);
     if (IS_DAX(file_inode(file))) {
         vma->vm_ops = &ext4_dax_vm_ops;
         vma->vm_flags |= VM_HUGEPAGE;
     } else {
         vma->vm_ops = &ext4_file_vm_ops;
     }
     return 0;
 }
 
 static int ext4_sample_last_mounted(struct super_block *sb,
                     struct vfsmount *mnt)
 {
     struct ext4_sb_info *sbi = EXT4_SB(sb);
     struct path path;
     char buf[64], *cp;
     handle_t *handle;
     int err;
 
     if (likely(ext4_test_mount_flag(sb, EXT4_MF_MNTDIR_SAMPLED)))
         return 0;
 
     if (sb_rdonly(sb) || !sb_start_intwrite_trylock(sb))
         return 0;
 
     ext4_set_mount_flag(sb, EXT4_MF_MNTDIR_SAMPLED);
     /*
      * Sample where the filesystem has been mounted and
      * store it in the superblock for sysadmin convenience
      * when trying to sort through large numbers of block
      * devices or filesystem images.
      */
     memset(buf, 0, sizeof(buf));
     path.mnt = mnt;
     path.dentry = mnt->mnt_root;
     cp = d_path(&path, buf, sizeof(buf));
     err = 0;
     if (IS_ERR(cp))
         goto out;
 
     handle = ext4_journal_start_sb(sb, EXT4_HT_MISC, 1);
     err = PTR_ERR(handle);
     if (IS_ERR(handle))
         goto out;
     BUFFER_TRACE(sbi->s_sbh, "get_write_access");
     err = ext4_journal_get_write_access(handle, sb, sbi->s_sbh,
                         EXT4_JTR_NONE);
     if (err)
         goto out_journal;
     lock_buffer(sbi->s_sbh);
     strncpy(sbi->s_es->s_last_mounted, cp,
         sizeof(sbi->s_es->s_last_mounted));
     ext4_superblock_csum_set(sb);
     unlock_buffer(sbi->s_sbh);
     ext4_handle_dirty_metadata(handle, NULL, sbi->s_sbh);
 out_journal:
     ext4_journal_stop(handle);
 out:
     sb_end_intwrite(sb);
     return err;
 }
 
 static int ext4_file_open(struct inode *inode, struct file *filp)
 {
     int ret;
 
     if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
         return -EIO;
 
     ret = ext4_sample_last_mounted(inode->i_sb, filp->f_path.mnt);
     if (ret)
         return ret;
 
     ret = fscrypt_file_open(inode, filp);
     if (ret)
         return ret;
 
     ret = fsverity_file_open(inode, filp);
     if (ret)
         return ret;
 
     /*
      * Set up the jbd2_inode if we are opening the inode for
      * writing and the journal is present
      */
     if (filp->f_mode & FMODE_WRITE) {
         ret = ext4_inode_attach_jinode(inode);
         if (ret < 0)
             return ret;
     }
 
     filp->f_mode |= FMODE_NOWAIT | FMODE_BUF_RASYNC;
     return dquot_file_open(inode, filp);
 }
 
 /*
  * ext4_llseek() handles both block-mapped and extent-mapped maxbytes values
  * by calling generic_file_llseek_size() with the appropriate maxbytes
  * value for each.
  */
 loff_t ext4_llseek(struct file *file, loff_t offset, int whence)
 {
     struct inode *inode = file->f_mapping->host;
     loff_t maxbytes;
 
     if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
         maxbytes = EXT4_SB(inode->i_sb)->s_bitmap_maxbytes;
     else
         maxbytes = inode->i_sb->s_maxbytes;
 
     switch (whence) {
     default:
         return generic_file_llseek_size(file, offset, whence,
                         maxbytes, i_size_read(inode));
     case SEEK_HOLE:
         inode_lock_shared(inode);
         offset = iomap_seek_hole(inode, offset,
                      &ext4_iomap_report_ops);
         inode_unlock_shared(inode);
         break;
     case SEEK_DATA:
         inode_lock_shared(inode);
         offset = iomap_seek_data(inode, offset,
                      &ext4_iomap_report_ops);
         inode_unlock_shared(inode);
         break;
     }
 
     if (offset < 0)
         return offset;
     return vfs_setpos(file, offset, maxbytes);
 }
 
 const struct file_operations ext4_file_operations = {
     .llseek     = ext4_llseek,
     .read_iter  = ext4_file_read_iter,
     .write_iter = ext4_file_write_iter,
     .iopoll     = iocb_bio_iopoll,
     .unlocked_ioctl = ext4_ioctl,
 #ifdef CONFIG_COMPAT
     .compat_ioctl   = ext4_compat_ioctl,
 #endif
     .mmap       = ext4_file_mmap,
     .mmap_supported_flags = MAP_SYNC,
     .open       = ext4_file_open,
     .release    = ext4_release_file,
     .fsync      = ext4_sync_file,
     .get_unmapped_area = thp_get_unmapped_area,
     .splice_read    = generic_file_splice_read,
     .splice_write   = iter_file_splice_write,
     .fallocate  = ext4_fallocate,
 };
 
 const struct inode_operations ext4_file_inode_operations = {
     .setattr    = ext4_setattr,
     .getattr    = ext4_file_getattr,
     .listxattr  = ext4_listxattr,
     .get_acl    = ext4_get_acl,
     .set_acl    = ext4_set_acl,
     .fiemap     = ext4_fiemap,
     .fileattr_get   = ext4_fileattr_get,
     .fileattr_set   = ext4_fileattr_set,
 };
 

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