[PATCH 09/14] blk-mq-sched: cleanup blk_mq_sched_dispatch_requests()

Ming Lei
2017-07-31T16:51:06Z

This patch split blk_mq_sched_dispatch_requests()
into two parts:

1) the 1st part is for checking if queue is busy, and
handle the busy situation

2) the 2nd part is moved to __blk_mq_sched_dispatch_requests()
which focuses on dispatch from sw queue or scheduler queue.

Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
block/blk-mq-sched.c | 42 +++++++++++++++++++++++++-----------------
1 file changed, 25 insertions(+), 17 deletions(-)

diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index cc0687a4d0ab..07ff53187617 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -89,16 +89,37 @@ static bool blk_mq_sched_restart_hctx(struct blk_mq_hw_ctx *hctx)
return false;
}

-void blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx)
+static void __blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx)
{
struct request_queue *q = hctx->queue;
struct elevator_queue *e = q->elevator;
const bool has_sched_dispatch = e && e->type->ops.mq.dispatch_request;
- bool can_go = true;
- LIST_HEAD(rq_list);
struct request *(*dispatch_fn)(struct blk_mq_hw_ctx *) =
has_sched_dispatch ? e->type->ops.mq.dispatch_request :
blk_mq_dispatch_rq_from_ctxs;
+ LIST_HEAD(rq_list);
+
+ if (!has_sched_dispatch && !(hctx->flags & BLK_MQ_F_SHARED_DEPTH)) {
+ blk_mq_flush_busy_ctxs(hctx, &rq_list);
+ blk_mq_dispatch_rq_list(q, &rq_list);
+ return;
+ }
+
+ do {
+ struct request *rq;
+
+ rq = dispatch_fn(hctx);
+ if (!rq)
+ break;
+ list_add(&rq->queuelist, &rq_list);
+ } while (blk_mq_dispatch_rq_list(q, &rq_list));
+}
+
+void blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx)
+{
+ struct request_queue *q = hctx->queue;
+ bool can_go = true;
+ LIST_HEAD(rq_list);

/* RCU or SRCU read lock is needed before checking quiesced flag */
if (unlikely(blk_mq_hctx_stopped(hctx) || blk_queue_quiesced(q)))
@@ -144,25 +165,12 @@ void blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx)
if (!can_go || test_bit(BLK_MQ_S_BUSY, &hctx->state))
return;

- if (!has_sched_dispatch && !(hctx->flags & BLK_MQ_F_SHARED_DEPTH)) {
- blk_mq_flush_busy_ctxs(hctx, &rq_list);
- blk_mq_dispatch_rq_list(q, &rq_list);
- return;
- }
-
/*
* We want to dispatch from the scheduler if we had no work left
* on the dispatch list, OR if we did have work but weren't able
* to make progress.
*/
- do {
- struct request *rq;
-
- rq = dispatch_fn(hctx);
- if (!rq)
- break;
- list_add(&rq->queuelist, &rq_list);
- } while (blk_mq_dispatch_rq_list(q, &rq_list));
+ __blk_mq_sched_dispatch_requests(hctx);
}

bool blk_mq_sched_try_merge(struct request_queue *q, struct bio *bio,
--
2.9.4