block/rq_qos: implement rq_qos_ops->queue_depth_changed()

mainline inclusion
from mainline-5.4-rc1
commit 9677a3e01f838622d2efc9a3ccb97090a2c3156a
category: feature
bugzilla: 38688
CVE: NA

---------------------------

wbt already gets queue depth changed notification through
wbt_set_queue_depth().  Generalize it into
rq_qos_ops->queue_depth_changed() so that other rq_qos policies can
easily hook into the events too.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Conflict:
  block/blk-rq-qos.c
  block/blk-rq-qos.h
  block/blk-wbt.c
Signed-off-by: NYu Kuai <yukuai3@huawei.com>
Reviewed-by: NHou Tao <houtao1@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

block/blk-rq-qos.c

@@ -109,6 +109,16 @@ void rq_qos_done_bio(struct request_queue *q, struct bio *bio)
 	}
 }
 
+void rq_qos_queue_depth_changed(struct request_queue *q)
+{
+	struct rq_qos *rqos;
+
+	for (rqos = q->rq_qos; rqos; rqos = rqos->next) {
+		if (rqos->ops->queue_depth_changed)
+			rqos->ops->queue_depth_changed(rqos);
+	}
+}
+
 /*
  * Return true, if we can't increase the depth further by scaling
  */

block/blk-rq-qos.h

@@ -33,6 +33,7 @@ struct rq_qos_ops {
 	void (*done)(struct rq_qos *, struct request *);
 	void (*done_bio)(struct rq_qos *, struct bio *);
 	void (*cleanup)(struct rq_qos *, struct bio *);
+	void (*queue_depth_changed)(struct rq_qos *);
 	void (*exit)(struct rq_qos *);
 };
 
@@ -104,5 +105,6 @@ void rq_qos_done_bio(struct request_queue *q, struct bio *bio);
 void rq_qos_throttle(struct request_queue *, struct bio *, spinlock_t *);
 void rq_qos_track(struct request_queue *q, struct request *, struct bio *);
 void rq_qos_merge(struct request_queue *q, struct request *rq, struct bio *bio);
+void rq_qos_queue_depth_changed(struct request_queue *q);
 void rq_qos_exit(struct request_queue *);
 #endif

block/blk-settings.c

@@ -884,7 +884,7 @@ EXPORT_SYMBOL_GPL(blk_queue_flush_queueable);
 void blk_set_queue_depth(struct request_queue *q, unsigned int depth)
 {
 	q->queue_depth = depth;
-	wbt_set_queue_depth(q, depth);
+	rq_qos_queue_depth_changed(q);
 }
 EXPORT_SYMBOL(blk_set_queue_depth);
 

block/blk-wbt.c

@@ -686,15 +686,6 @@ void wbt_requeue(struct rq_qos *rqos, struct request *rq)
 	}
 }
 
-void wbt_set_queue_depth(struct request_queue *q, unsigned int depth)
-{
-	struct rq_qos *rqos = wbt_rq_qos(q);
-	if (rqos) {
-		RQWB(rqos)->rq_depth.queue_depth = depth;
-		__wbt_update_limits(RQWB(rqos));
-	}
-}
-
 void wbt_set_write_cache(struct request_queue *q, bool write_cache_on)
 {
 	struct rq_qos *rqos = wbt_rq_qos(q);
@@ -747,6 +738,12 @@ static int wbt_data_dir(const struct request *rq)
 	return -1;
 }
 
+static void wbt_queue_depth_changed(struct rq_qos *rqos)
+{
+	RQWB(rqos)->rq_depth.queue_depth = blk_queue_depth(rqos->q);
+	__wbt_update_limits(RQWB(rqos));
+}
+
 static void wbt_exit(struct rq_qos *rqos)
 {
 	struct rq_wb *rwb = RQWB(rqos);
@@ -782,6 +779,7 @@ static struct rq_qos_ops wbt_rqos_ops = {
 	.requeue = wbt_requeue,
 	.done = wbt_done,
 	.cleanup = wbt_cleanup,
+	.queue_depth_changed = wbt_queue_depth_changed,
 	.exit = wbt_exit,
 };
 
@@ -821,7 +819,7 @@ int wbt_init(struct request_queue *q)
 
 	rwb->min_lat_nsec = wbt_default_latency_nsec(q);
 
-	wbt_set_queue_depth(q, blk_queue_depth(q));
+	wbt_queue_depth_changed(&rwb->rqos);
 	wbt_set_write_cache(q, test_bit(QUEUE_FLAG_WC, &q->queue_flags));
 
 	return 0;

block/blk-wbt.h

@@ -95,7 +95,6 @@ void wbt_enable_default(struct request_queue *);
 u64 wbt_get_min_lat(struct request_queue *q);
 void wbt_set_min_lat(struct request_queue *q, u64 val);
 
-void wbt_set_queue_depth(struct request_queue *, unsigned int);
 void wbt_set_write_cache(struct request_queue *, bool);
 
 u64 wbt_default_latency_nsec(struct request_queue *);
@@ -118,9 +117,6 @@ static inline void wbt_disable_default(struct request_queue *q)
 static inline void wbt_enable_default(struct request_queue *q)
 {
 }
-static inline void wbt_set_queue_depth(struct request_queue *q, unsigned int depth)
-{
-}
 static inline void wbt_set_write_cache(struct request_queue *q, bool wc)
 {
 }