[RFC] [PATCH 6/8] cfq-iosched: Get rid of on_st flag

[RFC] [PATCH 6/8] cfq-iosched: Get rid of on_st flag

[Gui Jianfeng]

It's able to check whether a CFQ group on a service tree by
checking "entity->rb_node". There's no need to maintain an
extra flag here.


Signed-off-by: Gui Jianfeng <guijianfeng@cn.fujitsu.com>
---
 block/cfq-iosched.c |    9 +--------
 1 files changed, 1 insertions(+), 8 deletions(-)

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 1b9b4b2..1df0928 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -103,7 +103,6 @@ struct io_sched_entity {
 	struct rb_node rb_node;
 	/* service_tree key */
 	u64 vdisktime;
-	bool on_st;
 	bool is_group_entity;
 	unsigned int weight;
 };
@@ -890,8 +889,6 @@ io_entity_service_tree_add(struct cfq_rb_root *st,
 	__io_entity_service_tree_add(st, io_entity);
 	st->count++;
 	st->total_weight += io_entity->weight;
-	if (io_entity->is_group_entity)
-		io_entity->on_st = true;
 }
 
 static void
@@ -903,7 +900,7 @@ cfq_group_service_tree_add(struct cfq_data *cfqd, struct cfq_group *cfqg)
 	struct io_sched_entity *__group_entity;
 
 	cfqg->nr_cfqq++;
-	if (group_entity->on_st)
+	if (!RB_EMPTY_NODE(&group_entity->rb_node))
 		return;
 
 	/*
@@ -936,8 +933,6 @@ io_entity_service_tree_del(struct cfq_rb_root *st,
 	if (!RB_EMPTY_NODE(&io_entity->rb_node)) {
 		__io_entity_service_tree_del(st, io_entity);
 		st->total_weight -= io_entity->weight;
-		if (io_entity->is_group_entity)
-			io_entity->on_st = false;
 		io_entity->service_tree = NULL;
 	}
 }
@@ -1070,7 +1065,6 @@ cfq_find_alloc_cfqg(struct cfq_data *cfqd, struct cgroup *cgroup, int create)
 	RB_CLEAR_NODE(&cfqg->group_entity.rb_node);
 
 	cfqg->group_entity.is_group_entity = true;
-	cfqg->group_entity.on_st = false;
 
 	/*
 	 * Take the initial reference that will be released on destroy
@@ -3972,7 +3966,6 @@ static void *cfq_init_queue(struct request_queue *q)
 	/* Give preference to root group over other groups */
 	cfqg->group_entity.weight = 2*BLKIO_WEIGHT_DEFAULT;
 	cfqg->group_entity.is_group_entity = true;
-	cfqg->group_entity.on_st = false;
 
 #ifdef CONFIG_CFQ_GROUP_IOSCHED
 	/*
-- 
1.6.5.2