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blkcg: implement blkcg_policy->on/offline_pd_fn() and blkcg_gq->online

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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>
This commit is contained in:
Tejun Heo 2013-01-09 08:05:12 -08:00
parent b276a876a0
commit f427d90964
2 changed files with 27 additions and 1 deletions
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21
block/blk-cgroup.c
View File

@ -182,7 +182,7 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg,
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 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg,
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 @@ EXPORT_SYMBOL_GPL(blkg_lookup_create);
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 @@ static void blkg_destroy(struct blkcg_gq *blkg)
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 @@ void blkcg_deactivate_policy(struct request_queue *q,
/* 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);

7
block/blk-cgroup.h
View File

@ -106,12 +106,17 @@ struct blkcg_gq {
/* 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 @@ struct blkcg_policy {
/* 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;
};