BUG_ON(list_empty(&req->queuelist));  list_del_init(&req->queuelist);  if (req->rl) elv_remove_request(req->q, req);
elv_dequeue_request(req->q, req);
static inline void blkdev_dequeue_request(struct request *req){	BUG_ON(list_empty(&req->queuelist));	list_del_init(&req->queuelist);	if (req->rl)		elv_remove_request(req->q, req);}