blk-mq: cleanup and improve list insertion

It's somewhat strange to have a list insertion function that
relies on the fact that the caller has mapped things correctly.
Pass in the hardware queue directly for insertion, which makes
for a much cleaner interface and implementation.

Reviewed-by: Keith Busch <keith.busch@intel.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index 641df3f..66fda19 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -395,17 +395,11 @@ void blk_mq_sched_insert_request(struct request *rq, bool at_head,
 		blk_mq_run_hw_queue(hctx, async);
 }
 
-void blk_mq_sched_insert_requests(struct request_queue *q,
+void blk_mq_sched_insert_requests(struct blk_mq_hw_ctx *hctx,
 				  struct blk_mq_ctx *ctx,
 				  struct list_head *list, bool run_queue_async)
 {
-	struct blk_mq_hw_ctx *hctx;
 	struct elevator_queue *e;
-	struct request *rq;
-
-	/* For list inserts, requests better be on the same hw queue */
-	rq = list_first_entry(list, struct request, queuelist);
-	hctx = rq->mq_hctx;
 
 	e = hctx->queue->elevator;
 	if (e && e->type->ops.insert_requests)