netfs: Fix undifferentiation of DIO reads from unbuffered reads

On cifs, "DIO reads" (specified by O_DIRECT) need to be differentiated from
"unbuffered reads" (specified by cache=none in the mount parameters).  The
difference is flagged in the protocol and the server may behave
differently: Windows Server will, for example, mandate that DIO reads are
block aligned.

Fix this by adding a NETFS_UNBUFFERED_READ to differentiate this from
NETFS_DIO_READ, parallelling the write differentiation that already exists.
cifs will then do the right thing.

Fixes: 016dc8516aec ("netfs: Implement unbuffered/DIO read support")
Signed-off-by: David Howells <[email protected]>
Link: https://lore.kernel.org/[email protected]
Reviewed-by: "Paulo Alcantara (Red Hat)" <[email protected]>
Reviewed-by: Viacheslav Dubeyko <[email protected]>
cc: Steve French <[email protected]>
cc: [email protected]
cc: [email protected]
cc: [email protected]
cc: [email protected]
cc: [email protected]
cc: [email protected]
cc: [email protected]
Signed-off-by: Christian Brauner <[email protected]>

1 files changed, 2 insertions, 1 deletions

diff --git a/fs/netfs/direct_read.c b/fs/netfs/direct_read.c
index e72c8b69b147..a05e13472baf 100644
--- a/fs/netfs/direct_read.c
+++ b/fs/netfs/direct_read.c
@@ -185,7 +185,8 @@ ssize_t netfs_unbuffered_read_iter_locked(struct kiocb *iocb, struct iov_iter *i
 
 	rreq = netfs_alloc_request(iocb->ki_filp->f_mapping, iocb->ki_filp,
 				   iocb->ki_pos, orig_count,
-				   NETFS_DIO_READ);
+				   iocb->ki_flags & IOCB_DIRECT ?
+				   NETFS_DIO_READ : NETFS_UNBUFFERED_READ);
 	if (IS_ERR(rreq))
 		return PTR_ERR(rreq);