nvme: redirect commands on dying queue

If a command send through nvme-multipath failed on a dying queue, resend it
on another path.

Signed-off-by: Chao Leng <lengchao@huawei.com>
[hch: rebased on top of the completion refactoring]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/nvme/host/core.c

@@ -274,13 +274,14 @@ static inline enum nvme_disposition nvme_decide_disposition(struct request *req)
 		return COMPLETE;
 
 	if (req->cmd_flags & REQ_NVME_MPATH) {
-		if (nvme_is_path_error(nvme_req(req)->status))
+		if (nvme_is_path_error(nvme_req(req)->status) ||
+		    blk_queue_dying(req->q))
 			return FAILOVER;
+	} else {
+		if (blk_queue_dying(req->q))
+			return COMPLETE;
 	}
 
-	if (blk_queue_dying(req->q))
-		return COMPLETE;
-
 	return RETRY;
 }