Commit e4a9bde9 authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe
Browse files

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: default avatarTejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Arianna Avanzini <avanzini.arianna@gmail.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 81437648

block/blk-cgroup.c

+24 −15
Original line number Diff line number Diff line
@@ -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;
@@ -866,6 +869,7 @@ blkcg_css_alloc(struct cgroup_subsys_state *parent_css) 
		blkcg->cpd[i] = cpd;

		cpd->blkcg = blkcg;

		cpd->plid = i;

		if (pol->cpd_init_fn)

			pol->cpd_init_fn(cpd);

	}
@@ -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;
@@ -1186,12 +1191,14 @@ 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]);

			if (blkcg->cpd[pol->plid]) {

				pol->cpd_free_fn(blkcg->cpd[pol->plid]);

				blkcg->cpd[pol->plid] = NULL;

			}

		}

	}

	blkcg_policy[pol->plid] = NULL;

err_unlock:

	mutex_unlock(&blkcg_pol_mutex);
@@ -1222,12 +1229,14 @@ 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]);

			if (blkcg->cpd[pol->plid]) {

				pol->cpd_free_fn(blkcg->cpd[pol->plid]);

				blkcg->cpd[pol->plid] = NULL;

			}

		}

	}

	blkcg_policy[pol->plid] = NULL;



	mutex_unlock(&blkcg_pol_mutex);

block/cfq-iosched.c

+18 −1
Original line number Diff line number Diff line
@@ -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,

include/linux/blk-cgroup.h

+10 −7
Original line number Diff line number Diff line
@@ -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;

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