From cadfbb6ec2e55171479191046142c927a8b12d87 Mon Sep 17 00:00:00 2001
From: Al Viro <viro@ZenIV.linux.org.uk>
Date: Tue, 10 Nov 2015 19:42:49 -0700
Subject: [PATCH] dax_io(): don't let non-error value escape via retval instead
 of EFAULT

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Cc: stable@vger.kernel.org # 4.0+
Signed-off-by: Jens Axboe <axboe@fb.com>
---
 fs/dax.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/dax.c b/fs/dax.c
index a86d3cc2b389..7b653e9aa8d1 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -169,8 +169,10 @@ static ssize_t dax_io(struct inode *inode, struct iov_iter *iter,
 		else
 			len = iov_iter_zero(max - pos, iter);
 
-		if (!len)
+		if (!len) {
+			retval = -EFAULT;
 			break;
+		}
 
 		pos += len;
 		addr += len;