elv_completed_request(q, flush_rq);
static void blk_pre_flush_end_io(struct request *flush_rq){	struct request *rq = flush_rq->end_io_data;	request_queue_t *q = rq->q;	rq->flags |= REQ_BAR_PREFLUSH;	if (!flush_rq->errors)		elv_requeue_request(q, rq);	else {		q->end_flush_fn(q, flush_rq);		clear_bit(QUEUE_FLAG_FLUSH, &q->queue_flags);		q->request_fn(q);	}}