block: move initialization of q->blkg_list into blkcg_init_queue

q->blkg_list is only used by blkcg code, so move it into
blkcg_init_queue.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20220211101149.2368042-3-ming.lei@redhat.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-cgroup.c

@@ -1175,6 +1175,8 @@ int blkcg_init_queue(struct request_queue *q)
 	bool preloaded;
 	int ret;
 
+	INIT_LIST_HEAD(&q->blkg_list);
+
 	new_blkg = blkg_alloc(&blkcg_root, q, GFP_KERNEL);
 	if (!new_blkg)
 		return -ENOMEM;

block/blk-core.c

@@ -476,9 +476,6 @@ struct request_queue *blk_alloc_queue(int node_id, bool alloc_srcu)
 	timer_setup(&q->timeout, blk_rq_timed_out_timer, 0);
 	INIT_WORK(&q->timeout_work, blk_timeout_work);
 	INIT_LIST_HEAD(&q->icq_list);
-#ifdef CONFIG_BLK_CGROUP
-	INIT_LIST_HEAD(&q->blkg_list);
-#endif
 
 	kobject_init(&q->kobj, &blk_queue_ktype);