Received-SPF: pass (google.com: domain of linux-kernel+bounces-148170-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:4601:e00::3 as permitted sender) client-ip=2604:1380:4601:e00::3;
Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley
	Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United
	Kingdom.
	Registered in England and Wales under Company Registration No. 3798903
To: Christian Brauner <brauner@kernel.org>
cc: dhowells@redhat.com, Jeff Layton <jlayton@kernel.org>,
    Eric Van Hensbergen <ericvh@kernel.org>,
    Latchesar Ionkov <lucho@ionkov.net>,
    Dominique Martinet <asmadeus@codewreck.org>,
    Christian Schoenebeck <linux_oss@crudebyte.com>,
    Marc Dionne <marc.dionne@auristor.com>, netfs@lists.linux.dev,
    linux-fsdevel@vger.kernel.org, v9fs@lists.linux.dev,
    linux-afs@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: [PATCH] netfs: Fix writethrough-mode error handling
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-ID: <6634.1713343604.1@warthog.procyon.org.uk>
Content-Transfer-Encoding: quoted-printable
From: David Howells <dhowells@redhat.com>
Date: Wed, 17 Apr 2024 09:47:19 +0100
Message-ID: <6736.1713343639@warthog.procyon.org.uk>

Fix the error return in netfs_perform_write() acting in writethrough-mode
to return any cached error in the case that netfs_end_writethrough()
returns 0.

This can affect the use of O_SYNC/O_DSYNC/RWF_SYNC/RWF_DSYNC in 9p and afs=
.

Fixes: 41d8e7673a77 ("netfs: Implement a write-through caching option")
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: Eric Van Hensbergen <ericvh@kernel.org>
cc: Latchesar Ionkov <lucho@ionkov.net>
cc: Dominique Martinet <asmadeus@codewreck.org>
cc: Christian Schoenebeck <linux_oss@crudebyte.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
cc: v9fs@lists.linux.dev
cc: linux-afs@lists.infradead.org
---
 fs/netfs/buffered_write.c |   10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/fs/netfs/buffered_write.c b/fs/netfs/buffered_write.c
index 9a0d32e4b422..8f13ca8fbc74 100644
--- a/fs/netfs/buffered_write.c
+++ b/fs/netfs/buffered_write.c
@@ -164,7 +164,7 @@ ssize_t netfs_perform_write(struct kiocb *iocb, struct=
 iov_iter *iter,
 	enum netfs_how_to_modify howto;
 	enum netfs_folio_trace trace;
 	unsigned int bdp_flags =3D (iocb->ki_flags & IOCB_SYNC) ? 0: BDP_ASYNC;
-	ssize_t written =3D 0, ret;
+	ssize_t written =3D 0, ret, ret2;
 	loff_t i_size, pos =3D iocb->ki_pos, from, to;
 	size_t max_chunk =3D PAGE_SIZE << MAX_PAGECACHE_ORDER;
 	bool maybe_trouble =3D false;
@@ -395,10 +395,12 @@ ssize_t netfs_perform_write(struct kiocb *iocb, stru=
ct iov_iter *iter,
 =

 out:
 	if (unlikely(wreq)) {
-		ret =3D netfs_end_writethrough(wreq, iocb);
+		ret2 =3D netfs_end_writethrough(wreq, iocb);
 		wbc_detach_inode(&wbc);
-		if (ret =3D=3D -EIOCBQUEUED)
-			return ret;
+		if (ret2 =3D=3D -EIOCBQUEUED)
+			return ret2;
+		if (ret =3D=3D 0)
+			ret =3D ret2;
 	}
 =

 	iocb->ki_pos +=3D written;