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-cgroup.c b/block/blk-cgroup.c
index 8ba0af7..2630f64 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -1223,7 +1223,11 @@ int blkcg_activate_policy(struct request_queue *q,
if (blkcg_policy_enabled(q, pol))
return 0;
- blk_queue_bypass_start(q);
+ if (q->mq_ops) {
+ blk_mq_freeze_queue(q);
+ blk_mq_quiesce_queue(q);
+ } else
+ blk_queue_bypass_start(q);
pd_prealloc:
if (!pd_prealloc) {
pd_prealloc = pol->pd_alloc_fn(GFP_KERNEL, q->node);
@@ -1261,7 +1265,10 @@ int blkcg_activate_policy(struct request_queue *q,
spin_unlock_irq(q->queue_lock);
out_bypass_end:
- blk_queue_bypass_end(q);
+ if (q->mq_ops)
+ blk_mq_unfreeze_queue(q);
+ else
+ blk_queue_bypass_end(q);
if (pd_prealloc)
pol->pd_free_fn(pd_prealloc);
return ret;
@@ -1284,7 +1291,12 @@ void blkcg_deactivate_policy(struct request_queue *q,
if (!blkcg_policy_enabled(q, pol))
return;
- blk_queue_bypass_start(q);
+ if (q->mq_ops) {
+ blk_mq_freeze_queue(q);
+ blk_mq_quiesce_queue(q);
+ } else
+ blk_queue_bypass_start(q);
+
spin_lock_irq(q->queue_lock);
__clear_bit(pol->plid, q->blkcg_pols);
@@ -1304,7 +1316,11 @@ void blkcg_deactivate_policy(struct request_queue *q,
}
spin_unlock_irq(q->queue_lock);
- blk_queue_bypass_end(q);
+
+ if (q->mq_ops)
+ blk_mq_unfreeze_queue(q);
+ else
+ blk_queue_bypass_end(q);
}
EXPORT_SYMBOL_GPL(blkcg_deactivate_policy);
