diff mbox series

[01/12] iomap: handle a post-direct I/O invalidate race in iomap_write_delalloc_release

Message ID 20240910043949.3481298-2-hch@lst.de (mailing list archive)
State New
Headers show
Series [01/12] iomap: handle a post-direct I/O invalidate race in iomap_write_delalloc_release | expand

Commit Message

Christoph Hellwig Sept. 10, 2024, 4:39 a.m. UTC 
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@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
---
 fs/iomap/buffered-io.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index f420c53d86acc5..69a931de1979b9 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -1241,7 +1241,15 @@  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,