From 6d18b008daf46bcd82b8ae250aae0785f9714096 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 13 Apr 2012 13:11:35 -0700 Subject: [PATCH] blkcg: shoot down blkgs if all policies are deactivated There's no reason to keep blkgs around if no policy is activated for the queue. This patch moves queue locking out of blkg_destroy_all() and call it from blkg_deactivate_policy() on deactivation of the last policy on the queue. This change was suggested by Vivek. Signed-off-by: Tejun Heo Cc: Vivek Goyal Signed-off-by: Jens Axboe --- block/blk-cgroup.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index 10f0d2fc0b23..b1807d4ecedb 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -258,7 +258,7 @@ static void blkg_destroy_all(struct request_queue *q) { struct blkio_group *blkg, *n; - spin_lock_irq(q->queue_lock); + lockdep_assert_held(q->queue_lock); list_for_each_entry_safe(blkg, n, &q->blkg_list, q_node) { struct blkio_cgroup *blkcg = blkg->blkcg; @@ -267,8 +267,6 @@ static void blkg_destroy_all(struct request_queue *q) blkg_destroy(blkg); spin_unlock(&blkcg->lock); } - - spin_unlock_irq(q->queue_lock); } static void blkg_rcu_free(struct rcu_head *rcu_head) @@ -646,7 +644,10 @@ void blkcg_drain_queue(struct request_queue *q) */ void blkcg_exit_queue(struct request_queue *q) { + spin_lock_irq(q->queue_lock); blkg_destroy_all(q); + spin_unlock_irq(q->queue_lock); + blk_throtl_exit(q); } @@ -802,6 +803,10 @@ void blkcg_deactivate_policy(struct request_queue *q, __clear_bit(pol->plid, q->blkcg_pols); + /* if no policy is left, no need for blkgs - shoot them down */ + if (bitmap_empty(q->blkcg_pols, BLKCG_MAX_POLS)) + blkg_destroy_all(q); + list_for_each_entry(blkg, &q->blkg_list, q_node) { /* grab blkcg lock too while removing @pd from @blkg */ spin_lock(&blkg->blkcg->lock);