Filesystems such as btrfs are unable to guarantee page invalidation
because pages could be locked as a part of the extent. Return zero
in case a page cache invalidation is unsuccessful so filesystems can
fallback to buffered I/O. This is similar to
generic_file_direct_write().
This takes care of the following invalidation warning during btrfs
mixed buffered and direct I/O using iomap_dio_rw():
Page cache invalidation failure on direct I/O. Possible data
corruption due to collision with buffered I/O!
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
index e4addfc58107..215315be6233 100644
--- a/fs/iomap/direct-io.c
+++ b/fs/iomap/direct-io.c
@@ -483,9 +483,15 @@ iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
*/
ret = invalidate_inode_pages2_range(mapping,
pos >> PAGE_SHIFT, end >> PAGE_SHIFT);
- if (ret)
- dio_warn_stale_pagecache(iocb->ki_filp);
- ret = 0;
+ /*
+ * If a page can not be invalidated, return 0 to fall back
+ * to buffered write.
+ */
+ if (ret) {
+ if (ret == -EBUSY)
+ ret = 0;
+ goto out_free_dio;
+ }
if (iov_iter_rw(iter) == WRITE && !wait_for_completion &&
!inode->i_sb->s_dio_done_wq) {
--
Goldwyn
