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Commit 8bd435b3 authored by Tejun Heo's avatar Tejun Heo Committed by Jens Axboe
Browse files

blkcg: remove static policy ID enums 



Remove BLKIO_POLICY_* enums and let blkio_policy_register() allocate
@pol->plid dynamically on registration.  The maximum number of blkcg
policies which can be registered at the same time is defined by
BLKCG_MAX_POLS constant added to include/linux/blkdev.h.

Note that blkio_policy_register() now may fail.  Policy init functions
updated accordingly and unnecessary ifdefs removed from cfq_init().

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent ec399347

block/blk-cgroup.c

+44 −15
Original line number Diff line number Diff line
@@ -31,7 +31,7 @@ static LIST_HEAD(all_q_list); 
struct blkio_cgroup blkio_root_cgroup = { .cfq_weight = 2 * CFQ_WEIGHT_DEFAULT };

EXPORT_SYMBOL_GPL(blkio_root_cgroup);



static struct blkio_policy_type *blkio_policy[BLKIO_NR_POLICIES];

static struct blkio_policy_type *blkio_policy[BLKCG_MAX_POLS];



struct blkio_cgroup *cgroup_to_blkio_cgroup(struct cgroup *cgroup)

{
@@ -67,7 +67,7 @@ static void blkg_free(struct blkio_group *blkg) 
	if (!blkg)

		return;



	for (i = 0; i < BLKIO_NR_POLICIES; i++) {

	for (i = 0; i < BLKCG_MAX_POLS; i++) {

		struct blkio_policy_type *pol = blkio_policy[i];

		struct blkg_policy_data *pd = blkg->pd[i];
@@ -107,7 +107,7 @@ static struct blkio_group *blkg_alloc(struct blkio_cgroup *blkcg, 
	blkg->refcnt = 1;

	cgroup_path(blkcg->css.cgroup, blkg->path, sizeof(blkg->path));



	for (i = 0; i < BLKIO_NR_POLICIES; i++) {

	for (i = 0; i < BLKCG_MAX_POLS; i++) {

		struct blkio_policy_type *pol = blkio_policy[i];

		struct blkg_policy_data *pd;
@@ -127,7 +127,7 @@ static struct blkio_group *blkg_alloc(struct blkio_cgroup *blkcg, 
	}



	/* invoke per-policy init */

	for (i = 0; i < BLKIO_NR_POLICIES; i++) {

	for (i = 0; i < BLKCG_MAX_POLS; i++) {

		struct blkio_policy_type *pol = blkio_policy[i];



		if (pol)
@@ -320,7 +320,7 @@ 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) {

		for (i = 0; i < BLKIO_NR_POLICIES; i++) {

		for (i = 0; i < BLKCG_MAX_POLS; i++) {

			struct blkio_policy_type *pol = blkio_policy[i];



			if (pol && pol->ops.blkio_reset_group_stats_fn)
@@ -729,46 +729,75 @@ struct cgroup_subsys blkio_subsys = { 
};

EXPORT_SYMBOL_GPL(blkio_subsys);



void blkio_policy_register(struct blkio_policy_type *blkiop)

/**

 * blkio_policy_register - register a blkcg policy

 * @blkiop: blkcg policy to register

 *

 * Register @blkiop with blkcg core.  Might sleep and @blkiop may be

 * modified on successful registration.  Returns 0 on success and -errno on

 * failure.

 */

int blkio_policy_register(struct blkio_policy_type *blkiop)

{

	struct request_queue *q;

	int i, ret;



	mutex_lock(&blkcg_pol_mutex);



	blkcg_bypass_start();

	/* find an empty slot */

	ret = -ENOSPC;

	for (i = 0; i < BLKCG_MAX_POLS; i++)

		if (!blkio_policy[i])

			break;

	if (i >= BLKCG_MAX_POLS)

		goto out_unlock;



	BUG_ON(blkio_policy[blkiop->plid]);

	blkio_policy[blkiop->plid] = blkiop;

	/* register and update blkgs */

	blkiop->plid = i;

	blkio_policy[i] = blkiop;



	blkcg_bypass_start();

	list_for_each_entry(q, &all_q_list, all_q_node)

		update_root_blkg_pd(q, blkiop);



	blkcg_bypass_end();



	/* everything is in place, add intf files for the new policy */

	if (blkiop->cftypes)

		WARN_ON(cgroup_add_cftypes(&blkio_subsys, blkiop->cftypes));



	ret = 0;

out_unlock:

	mutex_unlock(&blkcg_pol_mutex);

	return ret;

}

EXPORT_SYMBOL_GPL(blkio_policy_register);



/**

 * blkiop_policy_unregister - unregister a blkcg policy

 * @blkiop: blkcg policy to unregister

 *

 * Undo blkio_policy_register(@blkiop).  Might sleep.

 */

void blkio_policy_unregister(struct blkio_policy_type *blkiop)

{

	struct request_queue *q;



	mutex_lock(&blkcg_pol_mutex);



	if (WARN_ON(blkio_policy[blkiop->plid] != blkiop))

		goto out_unlock;



	/* kill the intf files first */

	if (blkiop->cftypes)

		cgroup_rm_cftypes(&blkio_subsys, blkiop->cftypes);



	blkcg_bypass_start();



	BUG_ON(blkio_policy[blkiop->plid] != blkiop);

	/* unregister and update blkgs */

	blkio_policy[blkiop->plid] = NULL;



	blkcg_bypass_start();

	list_for_each_entry(q, &all_q_list, all_q_node)

		update_root_blkg_pd(q, blkiop);

	blkcg_bypass_end();



out_unlock:

	mutex_unlock(&blkcg_pol_mutex);

}

EXPORT_SYMBOL_GPL(blkio_policy_unregister);

block/blk-cgroup.h

+4 −11
Original line number Diff line number Diff line
@@ -17,13 +17,6 @@ 
#include <linux/u64_stats_sync.h>

#include <linux/seq_file.h>



enum blkio_policy_id {

	BLKIO_POLICY_PROP = 0,		/* Proportional Bandwidth division */

	BLKIO_POLICY_THROTL,		/* Throttling */



	BLKIO_NR_POLICIES,

};



/* Max limits for throttle policy */

#define THROTL_IOPS_MAX		UINT_MAX
@@ -86,7 +79,7 @@ struct blkio_group { 
	/* reference count */

	int refcnt;



	struct blkg_policy_data *pd[BLKIO_NR_POLICIES];

	struct blkg_policy_data *pd[BLKCG_MAX_POLS];



	struct rcu_head rcu_head;

};
@@ -103,7 +96,7 @@ struct blkio_policy_ops { 


struct blkio_policy_type {

	struct blkio_policy_ops ops;

	enum blkio_policy_id plid;

	int plid;

	size_t pdata_size;		/* policy specific private data size */

	struct cftype *cftypes;		/* cgroup files for the policy */

};
@@ -113,7 +106,7 @@ extern void blkcg_drain_queue(struct request_queue *q); 
extern void blkcg_exit_queue(struct request_queue *q);



/* Blkio controller policy registration */

extern void blkio_policy_register(struct blkio_policy_type *);

extern int blkio_policy_register(struct blkio_policy_type *);

extern void blkio_policy_unregister(struct blkio_policy_type *);

extern void blkg_destroy_all(struct request_queue *q, bool destroy_root);

extern void update_root_blkg_pd(struct request_queue *q,
@@ -329,7 +322,7 @@ struct blkio_policy_type { 
static inline int blkcg_init_queue(struct request_queue *q) { return 0; }

static inline void blkcg_drain_queue(struct request_queue *q) { }

static inline void blkcg_exit_queue(struct request_queue *q) { }

static inline void blkio_policy_register(struct blkio_policy_type *blkiop) { }

static inline int blkio_policy_register(struct blkio_policy_type *blkiop) { return 0; }

static inline void blkio_policy_unregister(struct blkio_policy_type *blkiop) { }

static inline void blkg_destroy_all(struct request_queue *q,

				    bool destory_root) { }

block/blk-throttle.c

+1 −3
Original line number Diff line number Diff line
@@ -1089,7 +1089,6 @@ static struct blkio_policy_type blkio_policy_throtl = { 
		.blkio_exit_group_fn = throtl_exit_blkio_group,

		.blkio_reset_group_stats_fn = throtl_reset_group_stats,

	},

	.plid = BLKIO_POLICY_THROTL,

	.pdata_size = sizeof(struct throtl_grp),

	.cftypes = throtl_files,

};
@@ -1271,8 +1270,7 @@ static int __init throtl_init(void) 
	if (!kthrotld_workqueue)

		panic("Failed to create kthrotld\n");



	blkio_policy_register(&blkio_policy_throtl);

	return 0;

	return blkio_policy_register(&blkio_policy_throtl);

}



module_init(throtl_init);

block/cfq-iosched.c

+14 −11
Original line number Diff line number Diff line
@@ -4157,7 +4157,6 @@ static struct blkio_policy_type blkio_policy_cfq = { 
		.blkio_init_group_fn =		cfq_init_blkio_group,

		.blkio_reset_group_stats_fn =	cfqg_stats_reset,

	},

	.plid = BLKIO_POLICY_PROP,

	.pdata_size = sizeof(struct cfq_group),

	.cftypes = cfq_blkcg_files,

};
@@ -4181,27 +4180,31 @@ static int __init cfq_init(void) 
#else

		cfq_group_idle = 0;

#endif



	ret = blkio_policy_register(&blkio_policy_cfq);

	if (ret)

		return ret;



	cfq_pool = KMEM_CACHE(cfq_queue, 0);

	if (!cfq_pool)

		return -ENOMEM;

		goto err_pol_unreg;



	ret = elv_register(&iosched_cfq);

	if (ret) {

		kmem_cache_destroy(cfq_pool);

		return ret;

	}

	if (ret)

		goto err_free_pool;



#ifdef CONFIG_CFQ_GROUP_IOSCHED

	blkio_policy_register(&blkio_policy_cfq);

#endif

	return 0;



err_free_pool:

	kmem_cache_destroy(cfq_pool);

err_pol_unreg:

	blkio_policy_unregister(&blkio_policy_cfq);

	return ret;

}



static void __exit cfq_exit(void)

{

#ifdef CONFIG_CFQ_GROUP_IOSCHED

	blkio_policy_unregister(&blkio_policy_cfq);

#endif

	elv_unregister(&iosched_cfq);

	kmem_cache_destroy(cfq_pool);

}

include/linux/blkdev.h

+6 −1
Original line number Diff line number Diff line
@@ -35,6 +35,12 @@ struct bsg_job; 
#define BLKDEV_MIN_RQ	4

#define BLKDEV_MAX_RQ	128	/* Default maximum */



/*

 * Maximum number of blkcg policies allowed to be registered concurrently.

 * Defined here to simplify include dependency.

 */

#define BLKCG_MAX_POLS		2



struct request;

typedef void (rq_end_io_fn)(struct request *, int);
@@ -363,7 +369,6 @@ struct request_queue { 


	struct list_head	icq_list;

#ifdef CONFIG_BLK_CGROUP

	/* XXX: array size hardcoded to avoid include dependency (temporary) */

	struct list_head	blkg_list;

#endif