fifo_time
if (rq == last || blk_time_get_ns() < rq->fifo_time)
next->fifo_time < rq->fifo_time) {
rq->fifo_time = next->fifo_time;
rq->fifo_time = blk_time_get_ns() + bfqd->bfq_fifo_expire[rq_is_sync(rq)];
if (time_before((unsigned long)next->fifo_time,
(unsigned long)req->fifo_time)) {
req->fifo_time = next->fifo_time;
return time_is_before_eq_jiffies((unsigned long)rq->fifo_time);
unsigned long start_time = (unsigned long)rq->fifo_time;
rq->fifo_time = jiffies;
rq->fifo_time = jiffies + dd->fifo_expire[data_dir];