dm mpath: do not modify *__clone if blk_mq_alloc_request() fails

Purely cleanup, avoids potential for strange coding bugs.  But in
reality if __multipath_map() fails the caller has no business looking at
*__clone.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index 373e5e3..0caab4b 100644 (file)
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -580,16 +580,17 @@ static int __multipath_map(struct dm_target *ti, struct request *clone,
                 * .request_fn stacked on blk-mq path(s) and
                 * blk-mq stacked on blk-mq path(s).
                 */
-               *__clone = blk_mq_alloc_request(bdev_get_queue(bdev),
-                                               rq_data_dir(rq), BLK_MQ_REQ_NOWAIT);
-               if (IS_ERR(*__clone)) {
-                       /* ENOMEM, requeue */
+               clone = blk_mq_alloc_request(bdev_get_queue(bdev),
+                                            rq_data_dir(rq), BLK_MQ_REQ_NOWAIT);
+               if (IS_ERR(clone)) {
+                       /* EBUSY, ENODEV or EWOULDBLOCK: requeue */
                        clear_request_fn_mpio(m, map_context);
                        return r;
                }
-               (*__clone)->bio = (*__clone)->biotail = NULL;
-               (*__clone)->rq_disk = bdev->bd_disk;
-               (*__clone)->cmd_flags |= REQ_FAILFAST_TRANSPORT;
+               clone->bio = clone->biotail = NULL;
+               clone->rq_disk = bdev->bd_disk;
+               clone->cmd_flags |= REQ_FAILFAST_TRANSPORT;
+               *__clone = clone;
        }
 
        if (pgpath->pg->ps.type->start_io)