From 9ff7c42d8e6cefa882fec526eb899d9d1278c54d Mon Sep 17 00:00:00 2001
From: Sasha Levin <sashal@kernel.org>
Date: Wed, 5 Feb 2020 14:15:58 -0500
Subject: dax: pass NOWAIT flag to iomap_apply

From: Jeff Moyer <jmoyer@redhat.com>

[ Upstream commit 96222d53842dfe54869ec4e1b9d4856daf9105a2 ]

fstests generic/471 reports a failure when run with MOUNT_OPTIONS="-o
dax".  The reason is that the initial pwrite to an empty file with the
RWF_NOWAIT flag set does not return -EAGAIN.  It turns out that
dax_iomap_rw doesn't pass that flag through to iomap_apply.

With this patch applied, generic/471 passes for me.

Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/x49r1z86e1d.fsf@segfault.boston.devel.redhat.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/dax.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/dax.c b/fs/dax.c
index 1f1f0201cad18..0b0d8819cb1bb 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1207,6 +1207,9 @@ dax_iomap_rw(struct kiocb *iocb, struct iov_iter *iter,
 		lockdep_assert_held(&inode->i_rwsem);
 	}
 
+	if (iocb->ki_flags & IOCB_NOWAIT)
+		flags |= IOMAP_NOWAIT;
+
 	while (iov_iter_count(iter)) {
 		ret = iomap_apply(inode, pos, iov_iter_count(iter), flags, ops,
 				iter, dax_iomap_actor);
-- 
2.20.1