From: Qu Wenruo <wqu@xxxxxxxx>
[ Upstream commit a4ef54dbb576032ba31a646a5ffc8a26a83cb92c ]
For btrfs with sector size < page size (e.g. 4K sector size, 64K page
size), and enable the sector perfect compression support, then the
following dirty range can lead to problems:
0 32K 64K 96K 128K
| |///////||//////| |/|
124K
In above case, if we start writeback for that inode, the last dirty
range [124K, 128K) will not be submitted and cause reserved space
leakage:
- Start writeback for page 0
We find the range [32K, 96K) is suitable for compression, and queue it
into a workqueue to do the delayed compression and submission.
- Compression happens for range [32K, 96K)
Function extent_range_clear_dirty_for_io() is called, however it is
only doing full page handling, not considering any the extra bitmaps
for subpage cases.
That function will clear page dirty for both page 0 and page 64K.
- Writeback for the inode is done
Because page 64K has its dirty flag cleared, it will not be considered
as a writeback target.
This means the range [124K, 128K) will not be submitted, and reserved
space for it will be leaked.
Fix this problem by using the subpage helper to clear the dirty flag.
Signed-off-by: Qu Wenruo <wqu@xxxxxxxx>
Signed-off-by: David Sterba <dsterba@xxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
fs/btrfs/inode.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 1e4ca1e7d2e58..686d39309410f 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -902,7 +902,8 @@ static int extent_range_clear_dirty_for_io(struct inode *inode, u64 start, u64 e
ret = PTR_ERR(folio);
continue;
}
- folio_clear_dirty_for_io(folio);
+ btrfs_folio_clamp_clear_dirty(inode_to_fs_info(inode), folio, start,
+ end + 1 - start);
folio_put(folio);
}
return ret;
--
2.43.0
