[PATCH] xfs: Do not fallback to buffered-io for DIO atomic write

[Ritesh Harjani (IBM)]

iomap can return -ENOTBLK if pagecache invalidation fails.
Let's make sure if -ENOTBLK is ever returned for atomic
writes than we fail the write request (-EIO) instead of
fallback to buffered-io.

Suggested-by: Darrick J. Wong <djwong@xxxxxxxxxx>
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@xxxxxxxxx>
---

This should be on top of John's atomic write series [1].
[1]: https://lore.kernel.org/linux-xfs/20241019125113.369994-1-john.g.garry@xxxxxxxxxx/

 fs/xfs/xfs_file.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index ca47cae5a40a..b819a9273511 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -876,6 +876,14 @@ xfs_file_write_iter(
 		ret = xfs_file_dio_write(iocb, from);
 		if (ret != -ENOTBLK)
 			return ret;
+		/*
+		 * iomap can return -ENOTBLK if pagecache invalidation fails.
+		 * Let's make sure if -ENOTBLK is ever returned for atomic
+		 * writes than we fail the write request instead of fallback
+		 * to buffered-io.
+		 */
+		if (iocb->ki_flags & IOCB_ATOMIC)
+			return -EIO;
 	}

 	return xfs_file_buffered_write(iocb, from);
--
2.39.5