[RFC V4 6/6] blk: export the sysfs for switching qos

["Wang Jianchao (Kuaishou)" <jianchao.wan9@gmail.com>]

All of the blk-rq-qos policies has been changed to use the new
interfaces. Thus we can export the sysfs interface, namely
/sys/block/xxx/queue/qos and get rid of the unused interfaces.

Signed-off-by: Wang Jianchao (Kuaishou) <jianchao.wan9@gmail.com>
---
 block/blk-mq-debugfs.c | 10 +------
 block/blk-rq-qos.h     | 63 +-----------------------------------------
 block/blk-sysfs.c      |  2 ++
 3 files changed, 4 insertions(+), 71 deletions(-)

diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index cbbd668029a1..3defd5cb1cea 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -823,11 +823,6 @@ void blk_mq_debugfs_unregister_sched(struct request_queue *q)
 	q->sched_debugfs_dir = NULL;
 }
 
-static const char *rq_qos_id_to_name(enum rq_qos_id id)
-{
-	return "unknown";
-}
-
 void blk_mq_debugfs_unregister_rqos(struct rq_qos *rqos)
 {
 	debugfs_remove_recursive(rqos->debugfs_dir);
@@ -837,9 +832,6 @@ void blk_mq_debugfs_unregister_rqos(struct rq_qos *rqos)
 void blk_mq_debugfs_register_rqos(struct rq_qos *rqos)
 {
 	struct request_queue *q = rqos->q;
-	const char *dir_name;
-
-	dir_name = rqos->ops->name ? rqos->ops->name : rq_qos_id_to_name(rqos->id);
 
 	if (rqos->debugfs_dir || !rqos->ops->debugfs_attrs)
 		return;
@@ -848,7 +840,7 @@ void blk_mq_debugfs_register_rqos(struct rq_qos *rqos)
 		q->rqos_debugfs_dir = debugfs_create_dir("rqos",
 							 q->debugfs_dir);
 
-	rqos->debugfs_dir = debugfs_create_dir(dir_name,
+	rqos->debugfs_dir = debugfs_create_dir(rqos->ops->name,
 					       rqos->q->rqos_debugfs_dir);
 
 	debugfs_create_files(rqos->debugfs_dir, rqos, rqos->ops->debugfs_attrs);
diff --git a/block/blk-rq-qos.h b/block/blk-rq-qos.h
index bba829bbb461..262d221794f5 100644
--- a/block/blk-rq-qos.h
+++ b/block/blk-rq-qos.h
@@ -13,10 +13,6 @@
 
 struct blk_mq_debugfs_attr;
 
-enum rq_qos_id {
-	RQ_QOS_UNUSED,
-};
-
 struct rq_wait {
 	wait_queue_head_t wait;
 	atomic_t inflight;
@@ -25,7 +21,7 @@ struct rq_wait {
 struct rq_qos {
 	const struct rq_qos_ops *ops;
 	struct request_queue *q;
-	enum rq_qos_id id;
+	int id;
 	refcount_t ref;
 	wait_queue_head_t waitq;
 	bool dying;
@@ -69,17 +65,6 @@ struct rq_depth {
 	unsigned int default_depth;
 };
 
-static inline struct rq_qos *rq_qos_id(struct request_queue *q,
-				       enum rq_qos_id id)
-{
-	struct rq_qos *rqos;
-	for (rqos = q->rq_qos; rqos; rqos = rqos->next) {
-		if (rqos->id == id)
-			break;
-	}
-	return rqos;
-}
-
 static inline struct rq_qos *rq_qos_by_id(struct request_queue *q, int id)
 {
 	struct rq_qos *rqos;
@@ -99,52 +84,6 @@ static inline void rq_wait_init(struct rq_wait *rq_wait)
 	init_waitqueue_head(&rq_wait->wait);
 }
 
-static inline void rq_qos_add(struct request_queue *q, struct rq_qos *rqos)
-{
-	/*
-	 * No IO can be in-flight when adding rqos, so freeze queue, which
-	 * is fine since we only support rq_qos for blk-mq queue.
-	 *
-	 * Reuse ->queue_lock for protecting against other concurrent
-	 * rq_qos adding/deleting
-	 */
-	blk_mq_freeze_queue(q);
-
-	spin_lock_irq(&q->queue_lock);
-	rqos->next = q->rq_qos;
-	q->rq_qos = rqos;
-	spin_unlock_irq(&q->queue_lock);
-
-	blk_mq_unfreeze_queue(q);
-
-	if (rqos->ops->debugfs_attrs)
-		blk_mq_debugfs_register_rqos(rqos);
-}
-
-static inline void rq_qos_del(struct request_queue *q, struct rq_qos *rqos)
-{
-	struct rq_qos **cur;
-
-	/*
-	 * See comment in rq_qos_add() about freezing queue & using
-	 * ->queue_lock.
-	 */
-	blk_mq_freeze_queue(q);
-
-	spin_lock_irq(&q->queue_lock);
-	for (cur = &q->rq_qos; *cur; cur = &(*cur)->next) {
-		if (*cur == rqos) {
-			*cur = rqos->next;
-			break;
-		}
-	}
-	spin_unlock_irq(&q->queue_lock);
-
-	blk_mq_unfreeze_queue(q);
-
-	blk_mq_debugfs_unregister_rqos(rqos);
-}
-
 int rq_qos_register(struct rq_qos_ops *ops);
 void rq_qos_unregister(struct rq_qos_ops *ops);
 void rq_qos_activate(struct request_queue *q,
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 9f32882ceb2f..c02747db4e3b 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -574,6 +574,7 @@ QUEUE_RO_ENTRY(queue_max_segments, "max_segments");
 QUEUE_RO_ENTRY(queue_max_integrity_segments, "max_integrity_segments");
 QUEUE_RO_ENTRY(queue_max_segment_size, "max_segment_size");
 QUEUE_RW_ENTRY(elv_iosched, "scheduler");
+QUEUE_RW_ENTRY(queue_qos, "qos");
 
 QUEUE_RO_ENTRY(queue_logical_block_size, "logical_block_size");
 QUEUE_RO_ENTRY(queue_physical_block_size, "physical_block_size");
@@ -633,6 +634,7 @@ static struct attribute *queue_attrs[] = {
 	&queue_max_integrity_segments_entry.attr,
 	&queue_max_segment_size_entry.attr,
 	&elv_iosched_entry.attr,
+	&queue_qos_entry.attr,
 	&queue_hw_sector_size_entry.attr,
 	&queue_logical_block_size_entry.attr,
 	&queue_physical_block_size_entry.attr,
-- 
2.17.1