block: add rq_qos_wait to rq_qos

Originally when I split out the common code from blk-wbt into rq_qos I
left the wbt_wait() where it was and simply copied and modified it
slightly to work for io-latency.  However they are both basically the
same thing, and as time has gone on wbt_wait() has ended up much smarter
and kinder than it was when I copied it into io-latency, which means
io-latency has lost out on these improvements.

Since they are the same thing essentially except for a few minor things,
create rq_qos_wait() that replicates what wbt_wait() currently does with
callbacks that can be passed in for the snowflakes to do their own thing
as appropriate.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 6 insertions, 0 deletions

diff --git a/block/blk-rq-qos.h b/block/blk-rq-qos.h
index 6e09e98b93ea..8678875de420 100644
--- a/block/blk-rq-qos.h
+++ b/block/blk-rq-qos.h
@@ -93,6 +93,12 @@ static inline void rq_qos_del(struct request_queue *q, struct rq_qos *rqos)
 	}
 }
 
+typedef bool (acquire_inflight_cb_t)(struct rq_wait *rqw, void *private_data);
+typedef void (cleanup_cb_t)(struct rq_wait *rqw, void *private_data);
+
+void rq_qos_wait(struct rq_wait *rqw, void *private_data,
+		 acquire_inflight_cb_t *acquire_inflight_cb,
+		 cleanup_cb_t *cleanup_cb);
 bool rq_wait_inc_below(struct rq_wait *rq_wait, unsigned int limit);
 void rq_depth_scale_up(struct rq_depth *rqd);
 void rq_depth_scale_down(struct rq_depth *rqd, bool hard_throttle);