[patch v11 2/6] block, bfq: record how many queues have pending requests

[Yu Kuai]

From: Yu Kuai <yukuai3@xxxxxxxxxx>

Prepare to refactor the counting of 'num_groups_with_pending_reqs'.

Add a counter in bfq_group, update it while tracking if bfqq have pending
requests and when bfq_bfqq_move() is called.

Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
Reviewed-by: Jan Kara <jack@xxxxxxx>
---
 block/bfq-cgroup.c  | 10 ++++++++++
 block/bfq-iosched.h |  1 +
 block/bfq-wf2q.c    | 12 ++++++++++--
 3 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c
index 144bca006463..4c37398e0b99 100644
--- a/block/bfq-cgroup.c
+++ b/block/bfq-cgroup.c
@@ -552,6 +552,7 @@ static void bfq_pd_init(struct blkg_policy_data *pd)
 				   */
 	bfqg->bfqd = bfqd;
 	bfqg->active_entities = 0;
+	bfqg->num_queues_with_pending_reqs = 0;
 	bfqg->online = true;
 	bfqg->rq_pos_tree = RB_ROOT;
 }
@@ -641,6 +642,7 @@ void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
 {
 	struct bfq_entity *entity = &bfqq->entity;
 	struct bfq_group *old_parent = bfqq_group(bfqq);
+	bool has_pending_reqs = false;
 
 	/*
 	 * No point to move bfqq to the same group, which can happen when
@@ -661,6 +663,11 @@ void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
 	 */
 	bfqq->ref++;
 
+	if (entity->in_groups_with_pending_reqs) {
+		has_pending_reqs = true;
+		bfq_del_bfqq_in_groups_with_pending_reqs(bfqq);
+	}
+
 	/* If bfqq is empty, then bfq_bfqq_expire also invokes
 	 * bfq_del_bfqq_busy, thereby removing bfqq and its entity
 	 * from data structures related to current group. Otherwise we
@@ -688,6 +695,9 @@ void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
 	/* pin down bfqg and its associated blkg  */
 	bfqg_and_blkg_get(bfqg);
 
+	if (has_pending_reqs)
+		bfq_add_bfqq_in_groups_with_pending_reqs(bfqq);
+
 	if (bfq_bfqq_busy(bfqq)) {
 		if (unlikely(!bfqd->nonrot_with_queueing))
 			bfq_pos_tree_add_move(bfqd, bfqq);
diff --git a/block/bfq-iosched.h b/block/bfq-iosched.h
index 44e08b194749..338ff5418ea8 100644
--- a/block/bfq-iosched.h
+++ b/block/bfq-iosched.h
@@ -943,6 +943,7 @@ struct bfq_group {
 	struct bfq_entity *my_entity;
 
 	int active_entities;
+	int num_queues_with_pending_reqs;
 
 	struct rb_root rq_pos_tree;
 
diff --git a/block/bfq-wf2q.c b/block/bfq-wf2q.c
index bd8f4ed84848..5549ccf09cd2 100644
--- a/block/bfq-wf2q.c
+++ b/block/bfq-wf2q.c
@@ -1650,16 +1650,24 @@ void bfq_add_bfqq_in_groups_with_pending_reqs(struct bfq_queue *bfqq)
 {
 	struct bfq_entity *entity = &bfqq->entity;
 
-	if (!entity->in_groups_with_pending_reqs)
+	if (!entity->in_groups_with_pending_reqs) {
 		entity->in_groups_with_pending_reqs = true;
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+		bfqq_group(bfqq)->num_queues_with_pending_reqs++;
+#endif
+	}
 }
 
 void bfq_del_bfqq_in_groups_with_pending_reqs(struct bfq_queue *bfqq)
 {
 	struct bfq_entity *entity = &bfqq->entity;
 
-	if (entity->in_groups_with_pending_reqs)
+	if (entity->in_groups_with_pending_reqs) {
 		entity->in_groups_with_pending_reqs = false;
+#ifdef CONFIG_BFQ_GROUP_IOSCHED
+		bfqq_group(bfqq)->num_queues_with_pending_reqs--;
+#endif
+	}
 }
 
 /*
-- 
2.31.1