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ext4: fix races of writeback with punch hole and zero range

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When doing delayed allocation, update of on-disk inode size is postponed
until IO submission time. However hole punch or zero range fallocate
calls can end up discarding the tail page cache page and thus on-disk
inode size would never be properly updated.

Make sure the on-disk inode size is updated before truncating page
cache.

Signed-off-by: Jan Kara <jack@suse.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Jan Kara
2015-12-07 14:34:49 -05:00
committed by Theodore Ts'o
parent 32ebffd3bb
commit 011278485e
3 changed files with 42 additions and 1 deletions
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5
fs/ext4/extents.c
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@@ -4847,6 +4847,11 @@ static long ext4_zero_range(struct file *file, loff_t offset,
* released from page cache.
*/
down_write(&EXT4_I(inode)->i_mmap_sem);
ret = ext4_update_disksize_before_punch(inode, offset, len);
if (ret) {
up_write(&EXT4_I(inode)->i_mmap_sem);
goto out_dio;
}
/* Now release the pages and zero block aligned part of pages */
truncate_pagecache_range(inode, start, end - 1);
inode->i_mtime = inode->i_ctime = ext4_current_time(inode);