[PATCH V2 17/20] block: add check on elevator for supporting bio merge via hashtable from blk-mq sw queue

Ming Lei
2017-08-05T06:58:17Z

blk_mq_sched_try_merge() will be reused in following patches
to support bio merge to blk-mq sw queue, so add checkes to
related functions which are called from blk_mq_sched_try_merge().

Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
block/elevator.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)

diff --git a/block/elevator.c b/block/elevator.c
index 2fd2f777127b..eb56e2709291 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -71,6 +71,10 @@ bool elv_bio_merge_ok(struct request *rq, struct bio *bio)
if (!blk_rq_merge_ok(rq, bio))
return false;

+ /* We need to support to merge bio from sw queue */
+ if (!rq->q->elevator)
+ return true;
+
if (!elv_iosched_allow_bio_merge(rq, bio))
return false;

@@ -449,6 +453,10 @@ static inline enum elv_merge __elv_merge(struct request_queue *q,
return ELEVATOR_BACK_MERGE;
}

+ /* no elevator when merging bio to blk-mq sw queue */
+ if (!e)
+ return ELEVATOR_NO_MERGE;
+
if (e->uses_mq && e->type->ops.mq.request_merge)
return e->type->ops.mq.request_merge(q, req, bio);
else if (!e->uses_mq && e->type->ops.sq.elevator_merge_fn)
@@ -711,6 +719,10 @@ struct request *elv_latter_request(struct request_queue *q, struct request *rq)
{
struct elevator_queue *e = q->elevator;

+ /* no elevator when merging bio to blk-mq sw queue */
+ if (!e)
+ return NULL;
+
if (e->uses_mq && e->type->ops.mq.next_request)
return e->type->ops.mq.next_request(q, rq);
else if (!e->uses_mq && e->type->ops.sq.elevator_latter_req_fn)
@@ -723,6 +735,10 @@ struct request *elv_former_request(struct request_queue *q, struct request *rq)
{
struct elevator_queue *e = q->elevator;

+ /* no elevator when merging bio to blk-mq sw queue */
+ if (!e)
+ return NULL;
+
if (e->uses_mq && e->type->ops.mq.former_request)
return e->type->ops.mq.former_request(q, rq);
if (!e->uses_mq && e->type->ops.sq.elevator_former_req_fn)
--
2.9.4