[PATCH 4/7] block: remove q->rqos_debugfs_dir

[Ming Lei <ming.lei@xxxxxxxxxx>]

For each request_queue, its rqos 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 | 12 ++++++++----
 block/blk-sysfs.c      |  1 -
 include/linux/blkdev.h |  1 -
 3 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index 3d3346fc4c4e..9ccaf506514e 100644
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -638,6 +638,8 @@ void blk_mq_debugfs_register(struct request_queue *q)
 			blk_mq_debugfs_register_sched_hctx(q, hctx);
 	}
 
+	debugfs_create_dir("rqos", q->debugfs_dir);
+
 	if (q->rq_qos) {
 		struct rq_qos *rqos = q->rq_qos;
 
@@ -798,17 +800,19 @@ void blk_mq_debugfs_register_rqos(struct rq_qos *rqos)
 {
 	struct request_queue *q = rqos->disk->queue;
 	const char *dir_name = rq_qos_id_to_name(rqos->id);
+	struct dentry *rqos_top;
 
 	lockdep_assert_held(&q->debugfs_mutex);
 
 	if (rqos->debugfs_dir || !rqos->ops->debugfs_attrs)
 		return;
 
-	if (!q->rqos_debugfs_dir)
-		q->rqos_debugfs_dir = debugfs_create_dir("rqos",
-							 q->debugfs_dir);
+	rqos_top = debugfs_lookup("rqos", q->debugfs_dir);
+	if (IS_ERR_OR_NULL(rqos_top))
+		return;
 
-	rqos->debugfs_dir = debugfs_create_dir(dir_name, q->rqos_debugfs_dir);
+	rqos->debugfs_dir = debugfs_create_dir(dir_name, rqos_top);
+	dput(rqos_top);
 	debugfs_create_files(rqos->debugfs_dir, rqos, rqos->ops->debugfs_attrs);
 }
 
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 35d92ed10fdb..0679116bb195 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->rqos_debugfs_dir = NULL;
 	mutex_unlock(&q->debugfs_mutex);
 }
 
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 5efe6f00d86f..7663f0c482de 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		*rqos_debugfs_dir;
 	/*
 	 * Serializes all debugfs metadata operations using the above dentries.
 	 */
-- 
2.47.0