blkcg: implement blkcg_policy->on/offline_pd_fn() and blkcg_gq->online
Add two blkcg_policy methods, ->online_pd_fn() and ->offline_pd_fn(),
which are invoked as the policy_data gets activated and deactivated
while holding both blkcg and q locks.
Also, add blkcg_gq->online bool, which is set and cleared as the
blkcg_gq gets activated and deactivated. This flag also is toggled
while holding both blkcg and q locks.
These will be used to implement hierarchical stats.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 3a8de32..4d625d2 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -182,7 +182,7 @@
struct blkcg_gq *new_blkg)
{
struct blkcg_gq *blkg;
- int ret;
+ int i, ret;
WARN_ON_ONCE(!rcu_read_lock_held());
lockdep_assert_held(q->queue_lock);
@@ -218,7 +218,15 @@
if (likely(!ret)) {
hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list);
list_add(&blkg->q_node, &q->blkg_list);
+
+ for (i = 0; i < BLKCG_MAX_POLS; i++) {
+ struct blkcg_policy *pol = blkcg_policy[i];
+
+ if (blkg->pd[i] && pol->pd_online_fn)
+ pol->pd_online_fn(blkg);
+ }
}
+ blkg->online = true;
spin_unlock(&blkcg->lock);
if (!ret)
@@ -291,6 +299,7 @@
static void blkg_destroy(struct blkcg_gq *blkg)
{
struct blkcg *blkcg = blkg->blkcg;
+ int i;
lockdep_assert_held(blkg->q->queue_lock);
lockdep_assert_held(&blkcg->lock);
@@ -299,6 +308,14 @@
WARN_ON_ONCE(list_empty(&blkg->q_node));
WARN_ON_ONCE(hlist_unhashed(&blkg->blkcg_node));
+ for (i = 0; i < BLKCG_MAX_POLS; i++) {
+ struct blkcg_policy *pol = blkcg_policy[i];
+
+ if (blkg->pd[i] && pol->pd_offline_fn)
+ pol->pd_offline_fn(blkg);
+ }
+ blkg->online = false;
+
radix_tree_delete(&blkcg->blkg_tree, blkg->q->id);
list_del_init(&blkg->q_node);
hlist_del_init_rcu(&blkg->blkcg_node);
@@ -956,6 +973,8 @@
/* grab blkcg lock too while removing @pd from @blkg */
spin_lock(&blkg->blkcg->lock);
+ if (pol->pd_offline_fn)
+ pol->pd_offline_fn(blkg);
if (pol->pd_exit_fn)
pol->pd_exit_fn(blkg);