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From:   Yu Kuai <yukuai1@huaweicloud.com>
To:     tj@kernel.org, axboe@kernel.dk
Cc:     cgroups@vger.kernel.org, linux-block@vger.kernel.org,
        linux-kernel@vger.kernel.org, yukuai3@huawei.com,
        yukuai1@huaweicloud.com, yi.zhang@huawei.com
Subject: [PATCH v2 3/3] blk-throttle: cleanup tg_update_disptime()
Date:   Sat, 27 Aug 2022 18:16:37 +0800
Message-Id: <20220827101637.1775111-4-yukuai1@huaweicloud.com>
In-Reply-To: <20220827101637.1775111-1-yukuai1@huaweicloud.com>
References: <20220827101637.1775111-1-yukuai1@huaweicloud.com>
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From: Yu Kuai <yukuai3@huawei.com>

tg_update_disptime() only need to adjust postion for 'tg' in
'parent_sq', there is no need to call throtl_enqueue/dequeue_tg(),
since they will set/clear flag THROTL_TG_PENDING and increase/decrease
nr_pending, which is useless. By the way, clear the flag/decrease
nr_pending while there are still throttled bios is not good for debugging.

There are no functional changes.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
---
 block/blk-throttle.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 64002435fa43..47142a1dd102 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -520,7 +520,6 @@ static void throtl_rb_erase(struct rb_node *n,
 {
 	rb_erase_cached(n, &parent_sq->pending_tree);
 	RB_CLEAR_NODE(n);
-	--parent_sq->nr_pending;
 }
 
 static void update_min_dispatch_time(struct throtl_service_queue *parent_sq)
@@ -572,7 +571,11 @@ static void throtl_enqueue_tg(struct throtl_grp *tg)
 static void throtl_dequeue_tg(struct throtl_grp *tg)
 {
 	if (tg->flags & THROTL_TG_PENDING) {
-		throtl_rb_erase(&tg->rb_node, tg->service_queue.parent_sq);
+		struct throtl_service_queue *parent_sq =
+			tg->service_queue.parent_sq;
+
+		throtl_rb_erase(&tg->rb_node, parent_sq);
+		--parent_sq->nr_pending;
 		tg->flags &= ~THROTL_TG_PENDING;
 	}
 }
@@ -990,9 +993,9 @@ static void tg_update_disptime(struct throtl_grp *tg)
 	disptime = jiffies + min_wait;
 
 	/* Update dispatch time */
-	throtl_dequeue_tg(tg);
+	throtl_rb_erase(&tg->rb_node, tg->service_queue.parent_sq);
 	tg->disptime = disptime;
-	throtl_enqueue_tg(tg);
+	tg_service_queue_add(tg);
 
 	/* see throtl_add_bio_tg() */
 	tg->flags &= ~THROTL_TG_WAS_EMPTY;
-- 
2.31.1