blk-mq: skip non-mq queues in blk_mq_quiesce_queue

For submit_bio based queues there is no (S)RCU critical section during
I/O submission and thus nothing to wait for in blk_mq_wait_quiesce_done,
so skip doing any synchronization.  No non-mq driver should be calling
this, but for now we have core callers that unconditionally call into it.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20221101150050.3510-11-hch@lst.deSigned-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-mq.c

@@ -280,7 +280,9 @@ EXPORT_SYMBOL_GPL(blk_mq_wait_quiesce_done);
 void blk_mq_quiesce_queue(struct request_queue *q)
 {
 	blk_mq_quiesce_queue_nowait(q);
-	blk_mq_wait_quiesce_done(q);
+	/* nothing to wait for non-mq queues */
+	if (queue_is_mq(q))
+		blk_mq_wait_quiesce_done(q);
 }
 EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue);