rbd: enable multiple blk-mq queues

Allocate one queue per CPU and get a performance boost from
higher parallelism.
Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

drivers/block/rbd.c

@@ -4970,7 +4970,7 @@ static int rbd_init_disk(struct rbd_device *rbd_dev)
 	rbd_dev->tag_set.queue_depth = rbd_dev->opts->queue_depth;
 	rbd_dev->tag_set.numa_node = NUMA_NO_NODE;
 	rbd_dev->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
-	rbd_dev->tag_set.nr_hw_queues = 1;
+	rbd_dev->tag_set.nr_hw_queues = num_present_cpus();
 	rbd_dev->tag_set.cmd_size = sizeof(struct rbd_img_request);
 
 	err = blk_mq_alloc_tag_set(&rbd_dev->tag_set);