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Subject[PATCH V10 2/8] blk-mq-sched: move actual dispatching into one helper
Date
So that it becomes easy to support to dispatch from sw queue in the
following patch.

No functional change.

Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Suggested-by: Christoph Hellwig <hch@lst.de> # for simplifying dispatch logic
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
block/blk-mq-sched.c | 43 ++++++++++++++++++++++++-------------------
1 file changed, 24 insertions(+), 19 deletions(-)

diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index eca011fdfa0e..be29ba849408 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -89,12 +89,26 @@ static bool blk_mq_sched_restart_hctx(struct blk_mq_hw_ctx *hctx)
return false;
}

+static void blk_mq_do_dispatch_sched(struct blk_mq_hw_ctx *hctx)
+{
+ struct request_queue *q = hctx->queue;
+ struct elevator_queue *e = q->elevator;
+ LIST_HEAD(rq_list);
+
+ do {
+ struct request *rq = e->type->ops.mq.dispatch_request(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;
struct elevator_queue *e = q->elevator;
const bool has_sched_dispatch = e && e->type->ops.mq.dispatch_request;
- bool do_sched_dispatch = true;
LIST_HEAD(rq_list);

/* RCU or SRCU read lock is needed before checking quiesced flag */
@@ -122,30 +136,21 @@ void blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx)
* scheduler, we can no longer merge or sort them. So it's best to
* leave them there for as long as we can. Mark the hw queue as
* needing a restart in that case.
+ *
+ * We want to dispatch from the scheduler if there was nothing
+ * on the dispatch list or we were able to dispatch from the
+ * dispatch list.
*/
if (!list_empty(&rq_list)) {
blk_mq_sched_mark_restart_hctx(hctx);
- do_sched_dispatch = blk_mq_dispatch_rq_list(q, &rq_list);
- } else if (!has_sched_dispatch) {
+ if (blk_mq_dispatch_rq_list(q, &rq_list) && has_sched_dispatch)
+ blk_mq_do_dispatch_sched(hctx);
+ } else if (has_sched_dispatch) {
+ blk_mq_do_dispatch_sched(hctx);
+ } else {
blk_mq_flush_busy_ctxs(hctx, &rq_list);
blk_mq_dispatch_rq_list(q, &rq_list);
}
-
- /*
- * We want to dispatch from the scheduler if there was nothing
- * on the dispatch list or we were able to dispatch from the
- * dispatch list.
- */
- if (do_sched_dispatch && has_sched_dispatch) {
- do {
- struct request *rq;
-
- rq = e->type->ops.mq.dispatch_request(hctx);
- if (!rq)
- break;
- list_add(&rq->queuelist, &rq_list);
- } while (blk_mq_dispatch_rq_list(q, &rq_list));
- }
}

bool blk_mq_sched_try_merge(struct request_queue *q, struct bio *bio,
--
2.9.5
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