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From: David Howells <dhowells@redhat.com>
To: Steve French <stfrench@microsoft.com>
cc: dhowells@redhat.com, Jeff Layton <jlayton@kernel.org>,
    Enzo Matsumiya <ematsumiya@suse.de>, Jens Axboe <axboe@kernel.dk>,
    Matthew Wilcox <willy@infradead.org>,
    Christian Brauner <brauner@kernel.org>, netfs@lists.linux.dev,
    v9fs@lists.linux.dev, linux-afs@lists.infradead.org,
    linux-cifs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
    linux-kernel@vger.kernel.org
Subject: [PATCH] netfs: Fix setting of BDP_ASYNC from iocb flags
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Date: Tue, 21 May 2024 16:49:46 +0100
Message-ID: <316306.1716306586@warthog.procyon.org.uk>

Fix netfs_perform_write() to set BDP_ASYNC if IOCB_NOWAIT is set rather
than if IOCB_SYNC is not set.  It reflects asynchronicity in the sense of
not waiting rather than synchronicity in the sense of not returning until
the op is complete.

Without this, generic/590 fails on cifs in strict caching mode with a
complaint that one of the writes fails with EAGAIN.  The test can be
distilled down to:

        mount -t cifs /my/share /mnt -ostuff
        xfs_io -i -c 'falloc 0 8191M -c fsync -f /mnt/file
        xfs_io -i -c 'pwrite -b 1M -W 0 8191M' /mnt/file

Fixes: c38f4e96e605 ("netfs: Provide func to copy data to pagecache for bu=
ffered write")
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: Enzo Matsumiya <ematsumiya@suse.de>
cc: Jens Axboe <axboe@kernel.dk>
cc: Matthew Wilcox <willy@infradead.org>
cc: netfs@lists.linux.dev
cc: v9fs@lists.linux.dev
cc: linux-afs@lists.infradead.org
cc: linux-cifs@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
---
 fs/netfs/buffered_write.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/netfs/buffered_write.c b/fs/netfs/buffered_write.c
index 1121601536d1..07bc1fd43530 100644
--- a/fs/netfs/buffered_write.c
+++ b/fs/netfs/buffered_write.c
@@ -181,7 +181,7 @@ ssize_t netfs_perform_write(struct kiocb *iocb, struct=
 iov_iter *iter,
 	struct folio *folio, *writethrough =3D NULL;
 	enum netfs_how_to_modify howto;
 	enum netfs_folio_trace trace;
-	unsigned int bdp_flags =3D (iocb->ki_flags & IOCB_SYNC) ? 0: BDP_ASYNC;
+	unsigned int bdp_flags =3D (iocb->ki_flags & IOCB_NOWAIT) ? BDP_ASYNC : =
0;
 	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;