[PATCH 3/7] block: remove q->sched_debugfs_dir

[Ming Lei <ming.lei@xxxxxxxxxx>]

For each request_queue, its sched debugfs path is fixed, which can be
queried from its parent dentry directly, so it isn't necessary to cache
it in request_queue instance because it isn't used in fast path.

Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
---
 block/blk-mq-debugfs.c | 10 +++++-----
 block/blk-sysfs.c      |  1 -
 include/linux/blkdev.h |  1 -
 3 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index 3abb38ea2577..3d3346fc4c4e 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -628,7 +628,7 @@ void blk_mq_debugfs_register(struct request_queue *q)
 	 * didn't exist yet (because we don't know what to name the directory
 	 * until the queue is registered to a gendisk).
 	 */
-	if (q->elevator && !q->sched_debugfs_dir)
+	if (q->elevator)
 		blk_mq_debugfs_register_sched(q);
 
 	/* Similarly, blk_mq_init_hctx() couldn't do this previously. */
@@ -745,6 +745,7 @@ void blk_mq_debugfs_unregister_hctxs(struct request_queue *q)
 void blk_mq_debugfs_register_sched(struct request_queue *q)
 {
 	struct elevator_type *e = q->elevator->type;
+	struct dentry *sched_dir;
 
 	lockdep_assert_held(&q->debugfs_mutex);
 
@@ -758,17 +759,16 @@ void blk_mq_debugfs_register_sched(struct request_queue *q)
 	if (!e->queue_debugfs_attrs)
 		return;
 
-	q->sched_debugfs_dir = debugfs_create_dir("sched", q->debugfs_dir);
+	sched_dir = debugfs_create_dir("sched", q->debugfs_dir);
 
-	debugfs_create_files(q->sched_debugfs_dir, q, e->queue_debugfs_attrs);
+	debugfs_create_files(sched_dir, q, e->queue_debugfs_attrs);
 }
 
 void blk_mq_debugfs_unregister_sched(struct request_queue *q)
 {
 	lockdep_assert_held(&q->debugfs_mutex);
 
-	debugfs_remove_recursive(q->sched_debugfs_dir);
-	q->sched_debugfs_dir = NULL;
+	debugfs_lookup_and_remove("sched", q->debugfs_dir);
 }
 
 static const char *rq_qos_id_to_name(enum rq_qos_id id)
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 6f548a4376aa..35d92ed10fdb 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -748,7 +748,6 @@ static void blk_debugfs_remove(struct gendisk *disk)
 	blk_trace_shutdown(q);
 	debugfs_remove_recursive(q->debugfs_dir);
 	q->debugfs_dir = NULL;
-	q->sched_debugfs_dir = NULL;
 	q->rqos_debugfs_dir = NULL;
 	mutex_unlock(&q->debugfs_mutex);
 }
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 248416ecd01c..5efe6f00d86f 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -598,7 +598,6 @@ struct request_queue {
 	struct list_head	tag_set_list;
 
 	struct dentry		*debugfs_dir;
-	struct dentry		*sched_debugfs_dir;
 	struct dentry		*rqos_debugfs_dir;
 	/*
 	 * Serializes all debugfs metadata operations using the above dentries.
-- 
2.47.0