From 3b1a4a59a2086badab391687a6a0b86e03048393 Mon Sep 17 00:00:00 2001 From: austinchang Date: Wed, 29 Oct 2025 09:35:27 +0000 Subject: btrfs: mark dirty extent range for out of bound prealloc extents In btrfs_fallocate(), when the allocated range overlaps with a prealloc extent and the extent starts after i_size, the range doesn't get marked dirty in file_extent_tree. This results in persisting an incorrect disk_i_size for the inode when not using the no-holes feature. This is reproducible since commit 41a2ee75aab0 ("btrfs: introduce per-inode file extent tree"), then became hidden since commit 3d7db6e8bd22 ("btrfs: don't allocate file extent tree for non regular files") and then visible again after commit 8679d2687c35 ("btrfs: initialize inode::file_extent_tree after i_mode has been set"), which fixes the previous commit. The following reproducer triggers the problem: $ cat test.sh MNT=/mnt/test DEV=/dev/vdb mkdir -p $MNT mkfs.btrfs -f -O ^no-holes $DEV mount $DEV $MNT touch $MNT/file1 fallocate -n -o 1M -l 2M $MNT/file1 umount $MNT mount $DEV $MNT len=$((1 * 1024 * 1024)) fallocate -o 1M -l $len $MNT/file1 du --bytes $MNT/file1 umount $MNT mount $DEV $MNT du --bytes $MNT/file1 umount $MNT Running the reproducer gives the following result: $ ./test.sh (...) 2097152 /mnt/test/file1 1048576 /mnt/test/file1 The difference is exactly 1048576 as we assigned. Fix by adding a call to btrfs_inode_set_file_extent_range() in btrfs_fallocate_update_isize(). Fixes: 41a2ee75aab0 ("btrfs: introduce per-inode file extent tree") Signed-off-by: austinchang Reviewed-by: Filipe Manana Signed-off-by: Filipe Manana Signed-off-by: David Sterba --- fs/btrfs/file.c | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'fs/btrfs/file.c') diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index 7efd1f8a1912..fa82def46e39 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -2854,12 +2854,22 @@ static int btrfs_fallocate_update_isize(struct inode *inode, { struct btrfs_trans_handle *trans; struct btrfs_root *root = BTRFS_I(inode)->root; + u64 range_start; + u64 range_end; int ret; int ret2; if (mode & FALLOC_FL_KEEP_SIZE || end <= i_size_read(inode)) return 0; + range_start = round_down(i_size_read(inode), root->fs_info->sectorsize); + range_end = round_up(end, root->fs_info->sectorsize); + + ret = btrfs_inode_set_file_extent_range(BTRFS_I(inode), range_start, + range_end - range_start); + if (ret) + return ret; + trans = btrfs_start_transaction(root, 1); if (IS_ERR(trans)) return PTR_ERR(trans); -- cgit v1.2.3