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 <tj@xxxxxxxxxx>
Cc: Vivek Goyal <vgoyal@xxxxxxxxxx>
---
block/blk-cgroup.c | 11 ++++++++---
1 files changed, 8 insertions(+), 3 deletions(-)
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 10f0d2f..b1807d4 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);
--
1.7.7.3
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