5.10-stable review patch. If anyone has any objections, please let me know.
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From: austinchang austinchang@synology.com
[ Upstream commit 3b1a4a59a2086badab391687a6a0b86e03048393 ]
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 austinchang@synology.com Reviewed-by: Filipe Manana fdmanana@suse.com Signed-off-by: Filipe Manana fdmanana@suse.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/btrfs/file.c | 10 ++++++++++ 1 file changed, 10 insertions(+)
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index 53a3c32a0f8ce..38a293a9d0644 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -3049,12 +3049,22 @@ 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);