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[v2,1/2] btrfs: set correct ram_bytes when splitting ordered extent

Message ID 294cfed81888b2ea5ed4fffeb79ef9892443a3d3.1713329516.git.wqu@suse.com (mailing list archive)
State New
Headers show
Series btrfs: fix btrfs_file_extent_item::ram_bytes of btrfs_split_ordered_extent() | expand

Commit Message

Qu Wenruo April 17, 2024, 4:54 a.m. UTC 
[BUG]
When running generic/287, the following file extent items can be
generated:

        item 16 key (258 EXTENT_DATA 2682880) itemoff 15305 itemsize 53
                generation 9 type 1 (regular)
                extent data disk byte 1378414592 nr 462848
                extent data offset 0 nr 462848 ram 2097152
                extent compression 0 (none)

Note that file extent item is not a compressed one, but its ram_bytes is
way larger than its disk_num_bytes.

According to btrfs on-disk scheme, ram_bytes should match disk_num_bytes
if it's not a compressed one.

[CAUSE]
Since commit b73a6fd1b1ef ("btrfs: split partial dio bios before
submit"), for partial dio writes, we would split the ordered extent.

However the function btrfs_split_ordered_extent() doesn't update the
ram_bytes even it has already shrunk the disk_num_bytes.

Originally the function btrfs_split_ordered_extent() is only introduced
for zoned devices in commit d22002fd37bd ("btrfs: zoned: split ordered
extent when bio is sent"), but later commit b73a6fd1b1ef ("btrfs: split
partial dio bios before submit") makes non-zoned btrfs affected.

Thankfully for un-compressed file extent, we do not really utilize the
ram_bytes member, thus it won't cause any real problem.

[FIX]
Also update btrfs_ordered_extent::ram_bytes inside
btrfs_split_ordered_extent().

Fixes: d22002fd37bd ("btrfs: zoned: split ordered extent when bio is sent")
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
---
 fs/btrfs/ordered-data.c | 1 +
 1 file changed, 1 insertion(+)
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Patch

diff --git a/fs/btrfs/ordered-data.c b/fs/btrfs/ordered-data.c
index b749ba45da2b..c2a42bcde98e 100644
--- a/fs/btrfs/ordered-data.c
+++ b/fs/btrfs/ordered-data.c
@@ -1188,6 +1188,7 @@  struct btrfs_ordered_extent *btrfs_split_ordered_extent(
 	ordered->disk_bytenr += len;
 	ordered->num_bytes -= len;
 	ordered->disk_num_bytes -= len;
+	ordered->ram_bytes -= len;
 
 	if (test_bit(BTRFS_ORDERED_IO_DONE, &ordered->flags)) {
 		ASSERT(ordered->bytes_left == 0);