block: add accessors for setting/querying request deadline

We reduce the resolution of request expiry, but since we're already
using jiffies for this where resolution depends on the kernel
configuration and since the timeout resolution is coarse anyway,
that should be fine.

Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-mq.c

@@ -858,7 +858,7 @@ static void blk_mq_check_expired(struct blk_mq_hw_ctx *hctx,
 	while (true) {
 		start = read_seqcount_begin(&rq->gstate_seq);
 		gstate = READ_ONCE(rq->gstate);
-		deadline = rq->deadline;
+		deadline = blk_rq_deadline(rq);
 		if (!read_seqcount_retry(&rq->gstate_seq, start))
 			break;
 		cond_resched();