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blkcg: kill blkio_list and replace blkio_list_lock with a mutex

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With blkio_policy[], blkio_list is redundant and hinders with
per-queue policy activation.  Remove it.  Also, replace
blkio_list_lock with a mutex blkcg_pol_mutex and let it protect the
whole [un]registration.

This is to prepare for per-queue policy activation and doesn't cause
any functional difference.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Tejun Heo 2012-04-13 13:11:26 -07:00 committed by Jens Axboe
parent f48ec1d788
commit bc0d6501a8
2 changed files with 17 additions and 16 deletions
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32
block/blk-cgroup.c
View file

@ -24,9 +24,7 @@
#define MAX_KEY_LEN 100
static DEFINE_SPINLOCK(blkio_list_lock);
static LIST_HEAD(blkio_list);
static DEFINE_MUTEX(blkcg_pol_mutex);
static DEFINE_MUTEX(all_q_mutex);
static LIST_HEAD(all_q_list);
@ -311,8 +309,9 @@ blkiocg_reset_stats(struct cgroup *cgroup, struct cftype *cftype, u64 val)
struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup);
struct blkio_group *blkg;
struct hlist_node *n;
int i;
spin_lock(&blkio_list_lock);
mutex_lock(&blkcg_pol_mutex);
spin_lock_irq(&blkcg->lock);
/*
@ -321,15 +320,16 @@ blkiocg_reset_stats(struct cgroup *cgroup, struct cftype *cftype, u64 val)
* anyway. If you get hit by a race, retry.
*/
hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
struct blkio_policy_type *pol;
for (i = 0; i < BLKIO_NR_POLICIES; i++) {
struct blkio_policy_type *pol = blkio_policy[i];
list_for_each_entry(pol, &blkio_list, list)
if (pol->ops.blkio_reset_group_stats_fn)
if (pol && pol->ops.blkio_reset_group_stats_fn)
pol->ops.blkio_reset_group_stats_fn(blkg);
}
}
spin_unlock_irq(&blkcg->lock);
spin_unlock(&blkio_list_lock);
mutex_unlock(&blkcg_pol_mutex);
return 0;
}
@ -732,20 +732,21 @@ void blkio_policy_register(struct blkio_policy_type *blkiop)
{
struct request_queue *q;
mutex_lock(&blkcg_pol_mutex);
blkcg_bypass_start();
spin_lock(&blkio_list_lock);
BUG_ON(blkio_policy[blkiop->plid]);
blkio_policy[blkiop->plid] = blkiop;
list_add_tail(&blkiop->list, &blkio_list);
spin_unlock(&blkio_list_lock);
list_for_each_entry(q, &all_q_list, all_q_node)
update_root_blkg_pd(q, blkiop->plid);
blkcg_bypass_end();
if (blkiop->cftypes)
WARN_ON(cgroup_add_cftypes(&blkio_subsys, blkiop->cftypes));
mutex_unlock(&blkcg_pol_mutex);
}
EXPORT_SYMBOL_GPL(blkio_policy_register);
@ -753,19 +754,20 @@ void blkio_policy_unregister(struct blkio_policy_type *blkiop)
{
struct request_queue *q;
mutex_lock(&blkcg_pol_mutex);
if (blkiop->cftypes)
cgroup_rm_cftypes(&blkio_subsys, blkiop->cftypes);
blkcg_bypass_start();
spin_lock(&blkio_list_lock);
BUG_ON(blkio_policy[blkiop->plid] != blkiop);
blkio_policy[blkiop->plid] = NULL;
list_del_init(&blkiop->list);
spin_unlock(&blkio_list_lock);
list_for_each_entry(q, &all_q_list, all_q_node)
update_root_blkg_pd(q, blkiop->plid);
blkcg_bypass_end();
mutex_unlock(&blkcg_pol_mutex);
}
EXPORT_SYMBOL_GPL(blkio_policy_unregister);

1
block/blk-cgroup.h
View file

@ -102,7 +102,6 @@ struct blkio_policy_ops {
};
struct blkio_policy_type {
struct list_head list;
struct blkio_policy_ops ops;
enum blkio_policy_id plid;
size_t pdata_size; /* policy specific private data size */