blk-throttle: cleanup tg_update_disptime()

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>
Link: https://lore.kernel.org/r/20220827101637.1775111-4-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 4c12df8..55f2d98 100644 (file)
--- 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;
        }
 }
@@ -1034,9 +1037,9 @@ 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;