From: Christoph Hellwig Date: Tue, 10 Sep 2024 04:39:03 +0000 (+0300) Subject: iomap: handle a post-direct I/O invalidate race in iomap_write_delalloc_release X-Git-Tag: v6.12-rc1~118^2~5 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=7a9d43eace888a0ee6095035997bb138425844d3;p=thirdparty%2Flinux.git iomap: handle a post-direct I/O invalidate race in iomap_write_delalloc_release 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 Link: https://lore.kernel.org/r/20240910043949.3481298-2-hch@lst.de Reviewed-by: Darrick J. Wong Signed-off-by: Christian Brauner --- diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c index de47698a029ac..db7a3ff92e61e 100644 --- a/fs/iomap/buffered-io.c +++ b/fs/iomap/buffered-io.c @@ -1242,7 +1242,15 @@ 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,