netfs: Fix setting of BDP_ASYNC from iocb flags

[ Upstream commit c596bea1452ddf172ec9b588e4597228e9a1f4d5 ]

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 buffered write")
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/316306.1716306586@warthog.procyon.org.uk
Reviewed-by: Jens Axboe <axboe@kernel.dk>
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
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/fs/netfs/buffered_write.c b/fs/netfs/buffered_write.c
index 267b622d923b..912ad0a1df02 100644
--- a/fs/netfs/buffered_write.c
+++ b/fs/netfs/buffered_write.c
@@ -163,7 +163,7 @@ ssize_t netfs_perform_write(struct kiocb *iocb, struct iov_iter *iter,
 	struct folio *folio;
 	enum netfs_how_to_modify howto;
 	enum netfs_folio_trace trace;
-	unsigned int bdp_flags = (iocb->ki_flags & IOCB_SYNC) ? 0: BDP_ASYNC;
+	unsigned int bdp_flags = (iocb->ki_flags & IOCB_NOWAIT) ? BDP_ASYNC : 0;
 	ssize_t written = 0, ret, ret2;
 	loff_t i_size, pos = iocb->ki_pos, from, to;
 	size_t max_chunk = PAGE_SIZE << MAX_PAGECACHE_ORDER;