dm: return correct error code in dm_resume()'s retry loop

commit 8dc2365 upstream.

dm_resume() will return success (0) rather than -EINVAL if
!dm_suspended_md() upon retry within dm_resume().

Reset the error code at the start of dm_resume()'s retry loop.
Also, remove a useless assignment at the end of dm_resume().

Fixes: ffcc393 ("dm: enhance internal suspend and resume interface")
Signed-off-by: Minfei Huang <mnghuan@gmail.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/md/dm.c

@@ -3250,10 +3250,11 @@ static int __dm_resume(struct mapped_device *md, struct dm_table *map)
 
 int dm_resume(struct mapped_device *md)
 {
-	int r = -EINVAL;
+	int r;
 	struct dm_table *map = NULL;
 
 retry:
+	r = -EINVAL;
 	mutex_lock_nested(&md->suspend_lock, SINGLE_DEPTH_NESTING);
 
 	if (!dm_suspended_md(md))
@@ -3277,8 +3278,6 @@ int dm_resume(struct mapped_device *md)
 		goto out;
 
 	clear_bit(DMF_SUSPENDED, &md->flags);
-
-	r = 0;
 out:
 	mutex_unlock(&md->suspend_lock);