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blkcg: replace blkcg_policy->cpd_size with ->cpd_alloc/free_fn() methods 

Each active policy has a cpd (blkcg_policy_data) on each blkcg.  The
cpd's were allocated by blkcg core and each policy could request to
allocate extra space at the end by setting blkcg_policy->cpd_size
larger than the size of cpd.

This is a bit unusual but blkg (blkcg_gq) policy data used to be
handled this way too so it made sense to be consistent; however, blkg
policy data switched to alloc/free callbacks.

This patch makes similar changes to cpd handling.
blkcg_policy->cpd_alloc/free_fn() are added to replace ->cpd_size.  As
cpd allocation is now done from policy side, it can simply allocate a
larger area which embeds cpd at the beginning.

As ->cpd_alloc_fn() may be able to perform all necessary
initializations, this patch makes ->cpd_init_fn() optional.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Arianna Avanzini <avanzini.arianna@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Tejun Heo 2015-08-18 14:55:16 -07:00 committed by Jens Axboe
parent 814376483e
commit e4a9bde958
3 changed files with 52 additions and 23 deletions
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39
block/blk-cgroup.c
View File

@ -817,11 +817,15 @@ static void blkcg_css_free(struct cgroup_subsys_state *css)
int i;
mutex_lock(&blkcg_pol_mutex);
list_del(&blkcg->all_blkcgs_node);
mutex_unlock(&blkcg_pol_mutex);
for (i = 0; i < BLKCG_MAX_POLS; i++)
kfree(blkcg->cpd[i]);
if (blkcg->cpd[i])
blkcg_policy[i]->cpd_free_fn(blkcg->cpd[i]);
mutex_unlock(&blkcg_pol_mutex);
kfree(blkcg);
}
@ -854,11 +858,10 @@ blkcg_css_alloc(struct cgroup_subsys_state *parent_css)
* check if the policy requires any specific per-cgroup
* data: if it does, allocate and initialize it.
*/
if (!pol || !pol->cpd_size)
if (!pol || !pol->cpd_alloc_fn)
continue;
BUG_ON(blkcg->cpd[i]);
cpd = kzalloc(pol->cpd_size, GFP_KERNEL);
cpd = pol->cpd_alloc_fn(GFP_KERNEL);
if (!cpd) {
ret = ERR_PTR(-ENOMEM);
goto free_pd_blkcg;
@ -866,7 +869,8 @@ blkcg_css_alloc(struct cgroup_subsys_state *parent_css)
blkcg->cpd[i] = cpd;
cpd->blkcg = blkcg;
cpd->plid = i;
pol->cpd_init_fn(cpd);
if (pol->cpd_init_fn)
pol->cpd_init_fn(cpd);
}
spin_lock_init(&blkcg->lock);
@ -882,7 +886,8 @@ blkcg_css_alloc(struct cgroup_subsys_state *parent_css)
free_pd_blkcg:
for (i--; i >= 0; i--)
kfree(blkcg->cpd[i]);
if (blkcg->cpd[i])
blkcg_policy[i]->cpd_free_fn(blkcg->cpd[i]);
free_blkcg:
kfree(blkcg);
mutex_unlock(&blkcg_pol_mutex);
@ -1159,11 +1164,11 @@ int blkcg_policy_register(struct blkcg_policy *pol)
blkcg_policy[pol->plid] = pol;
/* allocate and install cpd's */
if (pol->cpd_size) {
if (pol->cpd_alloc_fn) {
list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) {
struct blkcg_policy_data *cpd;
cpd = kzalloc(pol->cpd_size, GFP_KERNEL);
cpd = pol->cpd_alloc_fn(GFP_KERNEL);
if (!cpd) {
mutex_unlock(&blkcg_pol_mutex);
goto err_free_cpds;
@ -1186,10 +1191,12 @@ int blkcg_policy_register(struct blkcg_policy *pol)
return 0;
err_free_cpds:
if (pol->cpd_size) {
if (pol->cpd_alloc_fn) {
list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) {
kfree(blkcg->cpd[pol->plid]);
blkcg->cpd[pol->plid] = NULL;
if (blkcg->cpd[pol->plid]) {
pol->cpd_free_fn(blkcg->cpd[pol->plid]);
blkcg->cpd[pol->plid] = NULL;
}
}
}
blkcg_policy[pol->plid] = NULL;
@ -1222,10 +1229,12 @@ void blkcg_policy_unregister(struct blkcg_policy *pol)
/* remove cpds and unregister */
mutex_lock(&blkcg_pol_mutex);
if (pol->cpd_size) {
if (pol->cpd_alloc_fn) {
list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) {
kfree(blkcg->cpd[pol->plid]);
blkcg->cpd[pol->plid] = NULL;
if (blkcg->cpd[pol->plid]) {
pol->cpd_free_fn(blkcg->cpd[pol->plid]);
blkcg->cpd[pol->plid] = NULL;
}
}
}
blkcg_policy[pol->plid] = NULL;

19
block/cfq-iosched.c
View File

@ -1568,6 +1568,16 @@ static void cfqg_stats_init(struct cfqg_stats *stats)
#endif
}
static struct blkcg_policy_data *cfq_cpd_alloc(gfp_t gfp)
{
struct cfq_group_data *cgd;
cgd = kzalloc(sizeof(*cgd), GFP_KERNEL);
if (!cgd)
return NULL;
return &cgd->cpd;
}
static void cfq_cpd_init(struct blkcg_policy_data *cpd)
{
struct cfq_group_data *cgd = cpd_to_cfqgd(cpd);
@ -1581,6 +1591,11 @@ static void cfq_cpd_init(struct blkcg_policy_data *cpd)
}
}
static void cfq_cpd_free(struct blkcg_policy_data *cpd)
{
kfree(cpd_to_cfqgd(cpd));
}
static struct blkg_policy_data *cfq_pd_alloc(gfp_t gfp, int node)
{
struct cfq_group *cfqg;
@ -4649,10 +4664,12 @@ static struct elevator_type iosched_cfq = {
#ifdef CONFIG_CFQ_GROUP_IOSCHED
static struct blkcg_policy blkcg_policy_cfq = {
.cpd_size = sizeof(struct cfq_group_data),
.cftypes = cfq_blkcg_files,
.cpd_alloc_fn = cfq_cpd_alloc,
.cpd_init_fn = cfq_cpd_init,
.cpd_free_fn = cfq_cpd_free,
.pd_alloc_fn = cfq_pd_alloc,
.pd_init_fn = cfq_pd_init,
.pd_offline_fn = cfq_pd_offline,

17
include/linux/blk-cgroup.h
View File

@ -81,11 +81,11 @@ struct blkg_policy_data {
};
/*
* Policies that need to keep per-blkcg data which is independent
* from any request_queue associated to it must specify its size
* with the cpd_size field of the blkcg_policy structure and
* embed a blkcg_policy_data in it. cpd_init() is invoked to let
* each policy handle per-blkcg data.
* Policies that need to keep per-blkcg data which is independent from any
* request_queue associated to it should implement cpd_alloc/free_fn()
* methods. A policy can allocate private data area by allocating larger
* data structure which embeds blkcg_policy_data at the beginning.
* cpd_init() is invoked to let each policy handle per-blkcg data.
*/
struct blkcg_policy_data {
/* the blkcg and policy id this per-policy data belongs to */
@ -124,7 +124,9 @@ struct blkcg_gq {
struct rcu_head rcu_head;
};
typedef struct blkcg_policy_data *(blkcg_pol_alloc_cpd_fn)(gfp_t gfp);
typedef void (blkcg_pol_init_cpd_fn)(struct blkcg_policy_data *cpd);
typedef void (blkcg_pol_free_cpd_fn)(struct blkcg_policy_data *cpd);
typedef struct blkg_policy_data *(blkcg_pol_alloc_pd_fn)(gfp_t gfp, int node);
typedef void (blkcg_pol_init_pd_fn)(struct blkg_policy_data *pd);
typedef void (blkcg_pol_online_pd_fn)(struct blkg_policy_data *pd);
@ -134,13 +136,14 @@ typedef void (blkcg_pol_reset_pd_stats_fn)(struct blkg_policy_data *pd);
struct blkcg_policy {
int plid;
/* policy specific per-blkcg data size */
size_t cpd_size;
/* cgroup files for the policy */
struct cftype *cftypes;
/* operations */
blkcg_pol_alloc_cpd_fn *cpd_alloc_fn;
blkcg_pol_init_cpd_fn *cpd_init_fn;
blkcg_pol_free_cpd_fn *cpd_free_fn;
blkcg_pol_alloc_pd_fn *pd_alloc_fn;
blkcg_pol_init_pd_fn *pd_init_fn;
blkcg_pol_online_pd_fn *pd_online_fn;