[PATCH RESEND] block/mq-deadline: adjust the timeout period of the per_prio->dispatch

[chengkaitao <pilgrimtao@gmail.com>]

From: chengkaitao <chengkaitao@kylinos.cn>

Reference function started_after()
Before modification:
	Timeout for dispatch{read}: 9.5s
	started_after - 0.5s < latest_start - 10s
	9.5s < latest_start - started_after

	Timeout for dispatch{write}: 5s
	started_after - 5s < latest_start - 10s
	5s < latest_start - started_after

At this point, write requests have higher priority than read requests.

After modification:
	Timeout for dispatch{read/write}: 5s
	prio_aging_expire / 2 < latest_start - started_after

Signed-off-by: chengkaitao <chengkaitao@kylinos.cn>
---
 block/mq-deadline.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/block/mq-deadline.c b/block/mq-deadline.c
index b9b7cdf1d3c9..f311168f8dfe 100644
--- a/block/mq-deadline.c
+++ b/block/mq-deadline.c
@@ -672,7 +672,8 @@ static void dd_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
 
 	if (flags & BLK_MQ_INSERT_AT_HEAD) {
 		list_add(&rq->queuelist, &per_prio->dispatch);
-		rq->fifo_time = jiffies;
+		rq->fifo_time = jiffies + dd->fifo_expire[data_dir]
+				- dd->prio_aging_expire / 2;
 	} else {
 		deadline_add_rq_rb(per_prio, rq);
 
-- 
2.50.1 (Apple Git-155)