[PATCH 3/4] xfs: use IOCB_DONTCACHE when falling back to buffered writes

[Christoph Hellwig]

Doing sub-block direct writes to COW inodes is not supported by XFS,
because new blocks need to be allocated as a whole.  Such writes
fall back to buffered I/O, and really should be using the
IOCB_DONTCACHE that didn't exist when the code was added to mimic
direct I/O semantics as closely as possible.  Also clear the
IOCB_DIRECT flags so that later code can't get confused by it being
set for something that at this point is not a direct I/O operation
any more.

Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
 fs/xfs/xfs_file.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 5703b6681b1d..e09ae86e118e 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -1119,6 +1119,9 @@ xfs_file_write_iter(
 		ret = xfs_file_dio_write(iocb, from);
 		if (ret != -ENOTBLK)
 			return ret;
+
+		iocb->ki_flags &= ~IOCB_DIRECT;
+		iocb->ki_flags |= IOCB_DONTCACHE;
 	}
 
 	if (xfs_is_zoned_inode(ip))
-- 
2.47.3