blk-mq-sched: add framework for MQ capable IO schedulers
This adds a set of hooks that intercepts the blk-mq path of
allocating/inserting/issuing/completing requests, allowing
us to develop a scheduler within that framework.
We reuse the existing elevator scheduler API on the registration
side, but augment that with the scheduler flagging support for
the blk-mq interfce, and with a separate set of ops hooks for MQ
devices.
We split driver and scheduler tags, so we can run the scheduling
independently of device queue depth.
Signed-off-by: Jens Axboe <axboe@fb.com>
Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
diff --git a/block/blk-ioc.c b/block/blk-ioc.c
index ab37209..fe186a9 100644
--- a/block/blk-ioc.c
+++ b/block/blk-ioc.c
@@ -43,7 +43,9 @@
if (icq->flags & ICQ_EXITED)
return;
- if (et->ops.sq.elevator_exit_icq_fn)
+ if (et->uses_mq && et->ops.mq.exit_icq)
+ et->ops.mq.exit_icq(icq);
+ else if (!et->uses_mq && et->ops.sq.elevator_exit_icq_fn)
et->ops.sq.elevator_exit_icq_fn(icq);
icq->flags |= ICQ_EXITED;
@@ -383,7 +385,9 @@
if (likely(!radix_tree_insert(&ioc->icq_tree, q->id, icq))) {
hlist_add_head(&icq->ioc_node, &ioc->icq_list);
list_add(&icq->q_node, &q->icq_list);
- if (et->ops.sq.elevator_init_icq_fn)
+ if (et->uses_mq && et->ops.mq.init_icq)
+ et->ops.mq.init_icq(icq);
+ else if (!et->uses_mq && et->ops.sq.elevator_init_icq_fn)
et->ops.sq.elevator_init_icq_fn(icq);
} else {
kmem_cache_free(et->icq_cache, icq);