This is a note to let you know that I've just added the patch titled
iomap: handle a post-direct I/O invalidate race in iomap_write_delalloc_release
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
iomap-handle-a-post-direct-i-o-invalidate-race-in-io.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 4ea4bef2b9c0163497bba4c4ba2420cec44a489a
Author: Christoph Hellwig <hch@xxxxxx>
Date: Tue Sep 10 07:39:03 2024 +0300
iomap: handle a post-direct I/O invalidate race in iomap_write_delalloc_release
[ Upstream commit 7a9d43eace888a0ee6095035997bb138425844d3 ]
When direct I/O completions invalidates the page cache it holds neither the
i_rwsem nor the invalidate_lock so it can be racing with
iomap_write_delalloc_release. If the search for the end of the region that
contains data returns the start offset we hit such a race and just need to
look for the end of the newly created hole instead.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Link: https://lore.kernel.org/r/20240910043949.3481298-2-hch@xxxxxx
Reviewed-by: Darrick J. Wong <djwong@xxxxxxxxxx>
Signed-off-by: Christian Brauner <brauner@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 5371b16341fff..aedaad4c37d75 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -1177,7 +1177,15 @@ static int iomap_write_delalloc_release(struct inode *inode,
error = data_end;
goto out_unlock;
}
- WARN_ON_ONCE(data_end <= start_byte);
+
+ /*
+ * If we race with post-direct I/O invalidation of the page cache,
+ * there might be no data left at start_byte.
+ */
+ if (data_end == start_byte)
+ continue;
+
+ WARN_ON_ONCE(data_end < start_byte);
WARN_ON_ONCE(data_end > scan_end_byte);
error = iomap_write_delalloc_scan(inode, &punch_start_byte,
