block: Stop abusing rq->csd.list in blk-softirq

	while (!list_empty(&local_list)) {

		struct request *rq;

		rq = list_entry(local_list.next, struct request, csd.list);

		list_del_init(&rq->csd.list);

		rq = list_entry(local_list.next, struct request, queuelist);

		list_del_init(&rq->queuelist);

		rq->q->softirq_done_fn(rq);

	}

}

	local_irq_save(flags);

	list = this_cpu_ptr(&blk_cpu_done);

	list_add_tail(&rq->csd.list, list);

	/*

	 * We reuse queuelist for a list of requests to process. Since the

	 * queuelist is used by the block layer only for requests waiting to be

	 * submitted to the device it is unused now.

	 */

	list_add_tail(&rq->queuelist, list);

	if (list->next == &rq->csd.list)

	if (list->next == &rq->queuelist)

		raise_softirq_irqoff(BLOCK_SOFTIRQ);

	local_irq_restore(flags);

		struct list_head *list;

do_local:

		list = this_cpu_ptr(&blk_cpu_done);

		list_add_tail(&req->csd.list, list);

		list_add_tail(&req->queuelist, list);

		/*

		 * if the list only contains our just added request,

		 * entries there, someone already raised the irq but it

		 * hasn't run yet.

		 */

		if (list->next == &req->csd.list)

		if (list->next == &req->queuelist)

			raise_softirq_irqoff(BLOCK_SOFTIRQ);

	} else if (raise_blk_irq(ccpu, req))

		goto do_local;