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.h b/block/blk-cgroup.h
index 40f5b97..678e89e 100644
--- a/block/blk-cgroup.h
+++ b/block/blk-cgroup.h
@@ -106,12 +106,17 @@
/* reference count */
int refcnt;
+ /* is this blkg online? protected by both blkcg and q locks */
+ bool online;
+
struct blkg_policy_data *pd[BLKCG_MAX_POLS];
struct rcu_head rcu_head;
};
typedef void (blkcg_pol_init_pd_fn)(struct blkcg_gq *blkg);
+typedef void (blkcg_pol_online_pd_fn)(struct blkcg_gq *blkg);
+typedef void (blkcg_pol_offline_pd_fn)(struct blkcg_gq *blkg);
typedef void (blkcg_pol_exit_pd_fn)(struct blkcg_gq *blkg);
typedef void (blkcg_pol_reset_pd_stats_fn)(struct blkcg_gq *blkg);
@@ -124,6 +129,8 @@
/* operations */
blkcg_pol_init_pd_fn *pd_init_fn;
+ blkcg_pol_online_pd_fn *pd_online_fn;
+ blkcg_pol_offline_pd_fn *pd_offline_fn;
blkcg_pol_exit_pd_fn *pd_exit_fn;
blkcg_pol_reset_pd_stats_fn *pd_reset_stats_fn;
};