[mirror_ubuntu-zesty-kernel.git] / block / blk-cgroup.h

#ifndef _BLK_CGROUP_H
#define _BLK_CGROUP_H
/*
 * Common Block IO controller cgroup interface
 *
 * Based on ideas and code from CFQ, CFS and BFQ:
 * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
 *
 * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
 *		      Paolo Valente <paolo.valente@unimore.it>
 *
 * Copyright (C) 2009 Vivek Goyal <vgoyal@redhat.com>
 * 	              Nauman Rafique <nauman@google.com>
 */

#include <linux/cgroup.h>
#include <linux/u64_stats_sync.h>
#include <linux/seq_file.h>

/* Max limits for throttle policy */
#define THROTL_IOPS_MAX		UINT_MAX

/* CFQ specific, out here for blkcg->cfq_weight */
#define CFQ_WEIGHT_MIN		10
#define CFQ_WEIGHT_MAX		1000
#define CFQ_WEIGHT_DEFAULT	500

#ifdef CONFIG_BLK_CGROUP

enum blkg_rwstat_type {
	BLKG_RWSTAT_READ,
	BLKG_RWSTAT_WRITE,
	BLKG_RWSTAT_SYNC,
	BLKG_RWSTAT_ASYNC,

	BLKG_RWSTAT_NR,
	BLKG_RWSTAT_TOTAL = BLKG_RWSTAT_NR,
};

struct blkio_cgroup {
	struct cgroup_subsys_state css;
	spinlock_t lock;
	struct hlist_head blkg_list;

	/* for policies to test whether associated blkcg has changed */
	uint64_t id;

	/* TODO: per-policy storage in blkio_cgroup */
	unsigned int cfq_weight;	/* belongs to cfq */
};

struct blkg_stat {
	struct u64_stats_sync		syncp;
	uint64_t			cnt;
};

struct blkg_rwstat {
	struct u64_stats_sync		syncp;
	uint64_t			cnt[BLKG_RWSTAT_NR];
};

/* per-blkg per-policy data */
struct blkg_policy_data {
	/* the blkg this per-policy data belongs to */
	struct blkio_group *blkg;

	/* used during policy activation */
	struct list_head alloc_node;

	/* pol->pdata_size bytes of private data used by policy impl */
	char pdata[] __aligned(__alignof__(unsigned long long));
};

struct blkio_group {
	/* Pointer to the associated request_queue */
	struct request_queue *q;
	struct list_head q_node;
	struct hlist_node blkcg_node;
	struct blkio_cgroup *blkcg;
	/* Store cgroup path */
	char path[128];
	/* reference count */
	int refcnt;

	struct blkg_policy_data *pd[BLKCG_MAX_POLS];

	struct rcu_head rcu_head;
};

typedef void (blkio_init_group_fn)(struct blkio_group *blkg);
typedef void (blkio_exit_group_fn)(struct blkio_group *blkg);
typedef void (blkio_reset_group_stats_fn)(struct blkio_group *blkg);

struct blkio_policy_ops {
	blkio_init_group_fn *blkio_init_group_fn;
	blkio_exit_group_fn *blkio_exit_group_fn;
	blkio_reset_group_stats_fn *blkio_reset_group_stats_fn;
};

struct blkio_policy_type {
	struct blkio_policy_ops ops;
	int plid;
	size_t pdata_size;		/* policy specific private data size */
	struct cftype *cftypes;		/* cgroup files for the policy */
};

extern int blkcg_init_queue(struct request_queue *q);
extern void blkcg_drain_queue(struct request_queue *q);
extern void blkcg_exit_queue(struct request_queue *q);

/* Blkio controller policy registration */
extern int blkio_policy_register(struct blkio_policy_type *);
extern void blkio_policy_unregister(struct blkio_policy_type *);
extern int blkcg_activate_policy(struct request_queue *q,
				 const struct blkio_policy_type *pol);
extern void blkcg_deactivate_policy(struct request_queue *q,
				    const struct blkio_policy_type *pol);

void blkcg_print_blkgs(struct seq_file *sf, struct blkio_cgroup *blkcg,
		       u64 (*prfill)(struct seq_file *, void *, int),
		       const struct blkio_policy_type *pol, int data,
		       bool show_total);
u64 __blkg_prfill_u64(struct seq_file *sf, void *pdata, u64 v);
u64 __blkg_prfill_rwstat(struct seq_file *sf, void *pdata,
			 const struct blkg_rwstat *rwstat);
u64 blkg_prfill_stat(struct seq_file *sf, void *pdata, int off);
u64 blkg_prfill_rwstat(struct seq_file *sf, void *pdata, int off);

struct blkg_conf_ctx {
	struct gendisk		*disk;
	struct blkio_group	*blkg;
	u64			v;
};

int blkg_conf_prep(struct blkio_cgroup *blkcg,
		   const struct blkio_policy_type *pol, const char *input,
		   struct blkg_conf_ctx *ctx);
void blkg_conf_finish(struct blkg_conf_ctx *ctx);


/**
 * blkg_to_pdata - get policy private data
 * @blkg: blkg of interest
 * @pol: policy of interest
 *
 * Return pointer to private data associated with the @blkg-@pol pair.
 */
static inline void *blkg_to_pdata(struct blkio_group *blkg,
			      struct blkio_policy_type *pol)
{
	return blkg ? blkg->pd[pol->plid]->pdata : NULL;
}

/**
 * pdata_to_blkg - get blkg associated with policy private data
 * @pdata: policy private data of interest
 *
 * @pdata is policy private data.  Determine the blkg it's associated with.
 */
static inline struct blkio_group *pdata_to_blkg(void *pdata)
{
	if (pdata) {
		struct blkg_policy_data *pd =
			container_of(pdata, struct blkg_policy_data, pdata);
		return pd->blkg;
	}
	return NULL;
}

static inline char *blkg_path(struct blkio_group *blkg)
{
	return blkg->path;
}

/**
 * blkg_get - get a blkg reference
 * @blkg: blkg to get
 *
 * The caller should be holding queue_lock and an existing reference.
 */
static inline void blkg_get(struct blkio_group *blkg)
{
	lockdep_assert_held(blkg->q->queue_lock);
	WARN_ON_ONCE(!blkg->refcnt);
	blkg->refcnt++;
}

void __blkg_release(struct blkio_group *blkg);

/**
 * blkg_put - put a blkg reference
 * @blkg: blkg to put
 *
 * The caller should be holding queue_lock.
 */
static inline void blkg_put(struct blkio_group *blkg)
{
	lockdep_assert_held(blkg->q->queue_lock);
	WARN_ON_ONCE(blkg->refcnt <= 0);
	if (!--blkg->refcnt)
		__blkg_release(blkg);
}

/**
 * blkg_stat_add - add a value to a blkg_stat
 * @stat: target blkg_stat
 * @val: value to add
 *
 * Add @val to @stat.  The caller is responsible for synchronizing calls to
 * this function.
 */
static inline void blkg_stat_add(struct blkg_stat *stat, uint64_t val)
{
	u64_stats_update_begin(&stat->syncp);
	stat->cnt += val;
	u64_stats_update_end(&stat->syncp);
}

/**
 * blkg_stat_read - read the current value of a blkg_stat
 * @stat: blkg_stat to read
 *
 * Read the current value of @stat.  This function can be called without
 * synchroniztion and takes care of u64 atomicity.
 */
static inline uint64_t blkg_stat_read(struct blkg_stat *stat)
{
	unsigned int start;
	uint64_t v;

	do {
		start = u64_stats_fetch_begin(&stat->syncp);
		v = stat->cnt;
	} while (u64_stats_fetch_retry(&stat->syncp, start));

	return v;
}

/**
 * blkg_stat_reset - reset a blkg_stat
 * @stat: blkg_stat to reset
 */
static inline void blkg_stat_reset(struct blkg_stat *stat)
{
	stat->cnt = 0;
}

/**
 * blkg_rwstat_add - add a value to a blkg_rwstat
 * @rwstat: target blkg_rwstat
 * @rw: mask of REQ_{WRITE|SYNC}
 * @val: value to add
 *
 * Add @val to @rwstat.  The counters are chosen according to @rw.  The
 * caller is responsible for synchronizing calls to this function.
 */
static inline void blkg_rwstat_add(struct blkg_rwstat *rwstat,
				   int rw, uint64_t val)
{
	u64_stats_update_begin(&rwstat->syncp);

	if (rw & REQ_WRITE)
		rwstat->cnt[BLKG_RWSTAT_WRITE] += val;
	else
		rwstat->cnt[BLKG_RWSTAT_READ] += val;
	if (rw & REQ_SYNC)
		rwstat->cnt[BLKG_RWSTAT_SYNC] += val;
	else
		rwstat->cnt[BLKG_RWSTAT_ASYNC] += val;

	u64_stats_update_end(&rwstat->syncp);
}

/**
 * blkg_rwstat_read - read the current values of a blkg_rwstat
 * @rwstat: blkg_rwstat to read
 *
 * Read the current snapshot of @rwstat and return it as the return value.
 * This function can be called without synchronization and takes care of
 * u64 atomicity.
 */
static inline struct blkg_rwstat blkg_rwstat_read(struct blkg_rwstat *rwstat)
{
	unsigned int start;
	struct blkg_rwstat tmp;

	do {
		start = u64_stats_fetch_begin(&rwstat->syncp);
		tmp = *rwstat;
	} while (u64_stats_fetch_retry(&rwstat->syncp, start));

	return tmp;
}

/**
 * blkg_rwstat_sum - read the total count of a blkg_rwstat
 * @rwstat: blkg_rwstat to read
 *
 * Return the total count of @rwstat regardless of the IO direction.  This
 * function can be called without synchronization and takes care of u64
 * atomicity.
 */
static inline uint64_t blkg_rwstat_sum(struct blkg_rwstat *rwstat)
{
	struct blkg_rwstat tmp = blkg_rwstat_read(rwstat);

	return tmp.cnt[BLKG_RWSTAT_READ] + tmp.cnt[BLKG_RWSTAT_WRITE];
}

/**
 * blkg_rwstat_reset - reset a blkg_rwstat
 * @rwstat: blkg_rwstat to reset
 */
static inline void blkg_rwstat_reset(struct blkg_rwstat *rwstat)
{
	memset(rwstat->cnt, 0, sizeof(rwstat->cnt));
}

#else

struct blkio_group {
};

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 int blkio_policy_register(struct blkio_policy_type *blkiop) { return 0; }
static inline void blkio_policy_unregister(struct blkio_policy_type *blkiop) { }
static inline int blkcg_activate_policy(struct request_queue *q,
					const struct blkio_policy_type *pol) { return 0; }
static inline void blkcg_deactivate_policy(struct request_queue *q,
					   const struct blkio_policy_type *pol) { }

static inline void *blkg_to_pdata(struct blkio_group *blkg,
				struct blkio_policy_type *pol) { return NULL; }
static inline struct blkio_group *pdata_to_blkg(void *pdata,
				struct blkio_policy_type *pol) { return NULL; }
static inline char *blkg_path(struct blkio_group *blkg) { return NULL; }
static inline void blkg_get(struct blkio_group *blkg) { }
static inline void blkg_put(struct blkio_group *blkg) { }

#endif

#ifdef CONFIG_BLK_CGROUP
extern struct blkio_cgroup blkio_root_cgroup;
extern struct blkio_cgroup *cgroup_to_blkio_cgroup(struct cgroup *cgroup);
extern struct blkio_cgroup *bio_blkio_cgroup(struct bio *bio);
extern struct blkio_group *blkg_lookup(struct blkio_cgroup *blkcg,
				       struct request_queue *q);
struct blkio_group *blkg_lookup_create(struct blkio_cgroup *blkcg,
				       struct request_queue *q);
#else
struct cgroup;
static inline struct blkio_cgroup *
cgroup_to_blkio_cgroup(struct cgroup *cgroup) { return NULL; }
static inline struct blkio_cgroup *
bio_blkio_cgroup(struct bio *bio) { return NULL; }

static inline struct blkio_group *blkg_lookup(struct blkio_cgroup *blkcg,
					      void *key) { return NULL; }
#endif
#endif /* _BLK_CGROUP_H */
Commit	Line	Data
31e4c28d VG	1	#ifndef _BLK_CGROUP_H
	2	#define _BLK_CGROUP_H
	3	/*
	4	* Common Block IO controller cgroup interface
	5	*
	6	* Based on ideas and code from CFQ, CFS and BFQ:
	7	* Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
	8	*
	9	* Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
	10	* Paolo Valente <paolo.valente@unimore.it>
	11	*
	12	* Copyright (C) 2009 Vivek Goyal <vgoyal@redhat.com>
	13	* Nauman Rafique <nauman@google.com>
	14	*/
	15
	16	#include <linux/cgroup.h>
575969a0	17	#include <linux/u64_stats_sync.h>
829fdb50	18	#include <linux/seq_file.h>
31e4c28d	19
9355aede VG	20	/* Max limits for throttle policy */
	21	#define THROTL_IOPS_MAX UINT_MAX
	22
3381cb8d TH	23	/* CFQ specific, out here for blkcg->cfq_weight */
	24	#define CFQ_WEIGHT_MIN 10
	25	#define CFQ_WEIGHT_MAX 1000
	26	#define CFQ_WEIGHT_DEFAULT 500
	27
f48ec1d7 TH	28	#ifdef CONFIG_BLK_CGROUP
f48ec1d7 TH	29
edcb0722 TH	30	enum blkg_rwstat_type {
	31	BLKG_RWSTAT_READ,
	32	BLKG_RWSTAT_WRITE,
	33	BLKG_RWSTAT_SYNC,
	34	BLKG_RWSTAT_ASYNC,
	35
	36	BLKG_RWSTAT_NR,
	37	BLKG_RWSTAT_TOTAL = BLKG_RWSTAT_NR,
303a3acb DS	38	};
303a3acb DS	39
31e4c28d VG	40	struct blkio_cgroup {
31e4c28d VG	41	struct cgroup_subsys_state css;
31e4c28d VG	42	spinlock_t lock;
31e4c28d VG	43	struct hlist_head blkg_list;
9a9e8a26 TH	44
	45	/* for policies to test whether associated blkcg has changed */
	46	uint64_t id;
3381cb8d TH	47
	48	/* TODO: per-policy storage in blkio_cgroup */
	49	unsigned int cfq_weight; /* belongs to cfq */
31e4c28d VG	50	};
31e4c28d VG	51
edcb0722 TH	52	struct blkg_stat {
	53	struct u64_stats_sync syncp;
	54	uint64_t cnt;
	55	};
	56
	57	struct blkg_rwstat {
	58	struct u64_stats_sync syncp;
	59	uint64_t cnt[BLKG_RWSTAT_NR];
	60	};
	61
0381411e TH	62	/* per-blkg per-policy data */
	63	struct blkg_policy_data {
	64	/* the blkg this per-policy data belongs to */
	65	struct blkio_group *blkg;
	66
a2b1693b TH	67	/* used during policy activation */
	68	struct list_head alloc_node;
	69
0381411e TH	70	/* pol->pdata_size bytes of private data used by policy impl */
	71	char pdata[] __aligned(__alignof__(unsigned long long));
	72	};
	73
31e4c28d	74	struct blkio_group {
c875f4d0 TH	75	/* Pointer to the associated request_queue */
c875f4d0 TH	76	struct request_queue *q;
e8989fae	77	struct list_head q_node;
31e4c28d	78	struct hlist_node blkcg_node;
7ee9c562	79	struct blkio_cgroup *blkcg;
2868ef7b VG	80	/* Store cgroup path */
2868ef7b VG	81	char path[128];
1adaf3dd TH	82	/* reference count */
1adaf3dd TH	83	int refcnt;
22084190	84
8bd435b3	85	struct blkg_policy_data *pd[BLKCG_MAX_POLS];
1adaf3dd TH	86
1adaf3dd TH	87	struct rcu_head rcu_head;
31e4c28d VG	88	};
31e4c28d VG	89
0381411e	90	typedef void (blkio_init_group_fn)(struct blkio_group *blkg);
9ade5ea4 TH	91	typedef void (blkio_exit_group_fn)(struct blkio_group *blkg);
9ade5ea4 TH	92	typedef void (blkio_reset_group_stats_fn)(struct blkio_group *blkg);
3e252066 VG	93
3e252066 VG	94	struct blkio_policy_ops {
0381411e	95	blkio_init_group_fn *blkio_init_group_fn;
9ade5ea4 TH	96	blkio_exit_group_fn *blkio_exit_group_fn;
9ade5ea4 TH	97	blkio_reset_group_stats_fn *blkio_reset_group_stats_fn;
3e252066 VG	98	};
	99
	100	struct blkio_policy_type {
3e252066	101	struct blkio_policy_ops ops;
8bd435b3	102	int plid;
0381411e	103	size_t pdata_size; /* policy specific private data size */
44ea53de	104	struct cftype cftypes; / cgroup files for the policy */
3e252066 VG	105	};
3e252066 VG	106
5efd6113 TH	107	extern int blkcg_init_queue(struct request_queue *q);
	108	extern void blkcg_drain_queue(struct request_queue *q);
	109	extern void blkcg_exit_queue(struct request_queue *q);
	110
3e252066	111	/* Blkio controller policy registration */
8bd435b3	112	extern int blkio_policy_register(struct blkio_policy_type *);
3e252066	113	extern void blkio_policy_unregister(struct blkio_policy_type *);
a2b1693b TH	114	extern int blkcg_activate_policy(struct request_queue *q,
	115	const struct blkio_policy_type *pol);
	116	extern void blkcg_deactivate_policy(struct request_queue *q,
	117	const struct blkio_policy_type *pol);
3e252066	118
829fdb50	119	void blkcg_print_blkgs(struct seq_file sf, struct blkio_cgroup blkcg,
d366e7ec	120	u64 (prfill)(struct seq_file , void *, int),
ec399347 TH	121	const struct blkio_policy_type *pol, int data,
ec399347 TH	122	bool show_total);
d366e7ec TH	123	u64 __blkg_prfill_u64(struct seq_file sf, void pdata, u64 v);
d366e7ec TH	124	u64 __blkg_prfill_rwstat(struct seq_file sf, void pdata,
829fdb50	125	const struct blkg_rwstat *rwstat);
5bc4afb1 TH	126	u64 blkg_prfill_stat(struct seq_file sf, void pdata, int off);
5bc4afb1 TH	127	u64 blkg_prfill_rwstat(struct seq_file sf, void pdata, int off);
829fdb50 TH	128
	129	struct blkg_conf_ctx {
	130	struct gendisk *disk;
	131	struct blkio_group *blkg;
	132	u64 v;
	133	};
	134
da8b0662 TH	135	int blkg_conf_prep(struct blkio_cgroup *blkcg,
da8b0662 TH	136	const struct blkio_policy_type pol, const char input,
829fdb50 TH	137	struct blkg_conf_ctx *ctx);
	138	void blkg_conf_finish(struct blkg_conf_ctx *ctx);
	139
	140
0381411e TH	141	/**
	142	* blkg_to_pdata - get policy private data
	143	* @blkg: blkg of interest
	144	* @pol: policy of interest
	145	*
	146	* Return pointer to private data associated with the @blkg-@pol pair.
	147	*/
	148	static inline void blkg_to_pdata(struct blkio_group blkg,
	149	struct blkio_policy_type *pol)
	150	{
549d3aa8	151	return blkg ? blkg->pd[pol->plid]->pdata : NULL;
0381411e TH	152	}
	153
	154	/**
	155	* pdata_to_blkg - get blkg associated with policy private data
	156	* @pdata: policy private data of interest
0381411e	157	*
aaec55a0	158	* @pdata is policy private data. Determine the blkg it's associated with.
0381411e	159	*/
aaec55a0	160	static inline struct blkio_group pdata_to_blkg(void pdata)
0381411e TH	161	{
	162	if (pdata) {
	163	struct blkg_policy_data *pd =
	164	container_of(pdata, struct blkg_policy_data, pdata);
	165	return pd->blkg;
	166	}
	167	return NULL;
	168	}
	169
afc24d49 VG	170	static inline char blkg_path(struct blkio_group blkg)
	171	{
	172	return blkg->path;
	173	}
	174
1adaf3dd TH	175	/**
	176	* blkg_get - get a blkg reference
	177	* @blkg: blkg to get
	178	*
	179	* The caller should be holding queue_lock and an existing reference.
	180	*/
	181	static inline void blkg_get(struct blkio_group *blkg)
	182	{
	183	lockdep_assert_held(blkg->q->queue_lock);
	184	WARN_ON_ONCE(!blkg->refcnt);
	185	blkg->refcnt++;
	186	}
	187
	188	void __blkg_release(struct blkio_group *blkg);
	189
	190	/**
	191	* blkg_put - put a blkg reference
	192	* @blkg: blkg to put
	193	*
	194	* The caller should be holding queue_lock.
	195	*/
	196	static inline void blkg_put(struct blkio_group *blkg)
	197	{
	198	lockdep_assert_held(blkg->q->queue_lock);
	199	WARN_ON_ONCE(blkg->refcnt <= 0);
	200	if (!--blkg->refcnt)
	201	__blkg_release(blkg);
	202	}
	203
edcb0722 TH	204	/**
	205	* blkg_stat_add - add a value to a blkg_stat
	206	* @stat: target blkg_stat
	207	* @val: value to add
	208	*
	209	* Add @val to @stat. The caller is responsible for synchronizing calls to
	210	* this function.
	211	*/
	212	static inline void blkg_stat_add(struct blkg_stat *stat, uint64_t val)
	213	{
	214	u64_stats_update_begin(&stat->syncp);
	215	stat->cnt += val;
	216	u64_stats_update_end(&stat->syncp);
	217	}
	218
	219	/**
	220	* blkg_stat_read - read the current value of a blkg_stat
	221	* @stat: blkg_stat to read
	222	*
	223	* Read the current value of @stat. This function can be called without
	224	* synchroniztion and takes care of u64 atomicity.
	225	*/
	226	static inline uint64_t blkg_stat_read(struct blkg_stat *stat)
	227	{
	228	unsigned int start;
	229	uint64_t v;
	230
	231	do {
	232	start = u64_stats_fetch_begin(&stat->syncp);
	233	v = stat->cnt;
	234	} while (u64_stats_fetch_retry(&stat->syncp, start));
	235
	236	return v;
	237	}
	238
	239	/**
	240	* blkg_stat_reset - reset a blkg_stat
	241	* @stat: blkg_stat to reset
	242	*/
	243	static inline void blkg_stat_reset(struct blkg_stat *stat)
	244	{
	245	stat->cnt = 0;
	246	}
	247
	248	/**
	249	* blkg_rwstat_add - add a value to a blkg_rwstat
	250	* @rwstat: target blkg_rwstat
	251	* @rw: mask of REQ_{WRITE\|SYNC}
	252	* @val: value to add
	253	*
	254	* Add @val to @rwstat. The counters are chosen according to @rw. The
	255	* caller is responsible for synchronizing calls to this function.
	256	*/
	257	static inline void blkg_rwstat_add(struct blkg_rwstat *rwstat,
	258	int rw, uint64_t val)
	259	{
	260	u64_stats_update_begin(&rwstat->syncp);
	261
	262	if (rw & REQ_WRITE)
	263	rwstat->cnt[BLKG_RWSTAT_WRITE] += val;
	264	else
	265	rwstat->cnt[BLKG_RWSTAT_READ] += val;
	266	if (rw & REQ_SYNC)
	267	rwstat->cnt[BLKG_RWSTAT_SYNC] += val;
268	else
269	rwstat->cnt[BLKG_RWSTAT_ASYNC] += val;
270
271	u64_stats_update_end(&rwstat->syncp);
272	}
273
274	/**
275	* blkg_rwstat_read - read the current values of a blkg_rwstat
276	* @rwstat: blkg_rwstat to read
277	*
278	* Read the current snapshot of @rwstat and return it as the return value.
279	* This function can be called without synchronization and takes care of
280	* u64 atomicity.
281	*/
c94bed89	282	static inline struct blkg_rwstat blkg_rwstat_read(struct blkg_rwstat *rwstat)
edcb0722 TH	283	{
	284	unsigned int start;
	285	struct blkg_rwstat tmp;
	286
	287	do {
	288	start = u64_stats_fetch_begin(&rwstat->syncp);
	289	tmp = *rwstat;
	290	} while (u64_stats_fetch_retry(&rwstat->syncp, start));
	291
	292	return tmp;
	293	}
	294
	295	/**
	296	* blkg_rwstat_sum - read the total count of a blkg_rwstat
	297	* @rwstat: blkg_rwstat to read
	298	*
	299	* Return the total count of @rwstat regardless of the IO direction. This
	300	* function can be called without synchronization and takes care of u64
	301	* atomicity.
	302	*/
	303	static inline uint64_t blkg_rwstat_sum(struct blkg_rwstat *rwstat)
	304	{
	305	struct blkg_rwstat tmp = blkg_rwstat_read(rwstat);
	306
	307	return tmp.cnt[BLKG_RWSTAT_READ] + tmp.cnt[BLKG_RWSTAT_WRITE];
	308	}
	309
	310	/**
	311	* blkg_rwstat_reset - reset a blkg_rwstat
	312	* @rwstat: blkg_rwstat to reset
	313	*/
	314	static inline void blkg_rwstat_reset(struct blkg_rwstat *rwstat)
	315	{
	316	memset(rwstat->cnt, 0, sizeof(rwstat->cnt));
	317	}
	318
2f5ea477 JA	319	#else
	320
	321	struct blkio_group {
	322	};
	323
3e252066 VG	324	struct blkio_policy_type {
	325	};
	326
5efd6113 TH	327	static inline int blkcg_init_queue(struct request_queue *q) { return 0; }
	328	static inline void blkcg_drain_queue(struct request_queue *q) { }
	329	static inline void blkcg_exit_queue(struct request_queue *q) { }
8bd435b3	330	static inline int blkio_policy_register(struct blkio_policy_type *blkiop) { return 0; }
3e252066	331	static inline void blkio_policy_unregister(struct blkio_policy_type *blkiop) { }
a2b1693b TH	332	static inline int blkcg_activate_policy(struct request_queue *q,
	333	const struct blkio_policy_type *pol) { return 0; }
	334	static inline void blkcg_deactivate_policy(struct request_queue *q,
	335	const struct blkio_policy_type *pol) { }
3e252066	336
0381411e TH	337	static inline void blkg_to_pdata(struct blkio_group blkg,
	338	struct blkio_policy_type *pol) { return NULL; }
	339	static inline struct blkio_group pdata_to_blkg(void pdata,
	340	struct blkio_policy_type *pol) { return NULL; }
afc24d49	341	static inline char blkg_path(struct blkio_group blkg) { return NULL; }
1adaf3dd TH	342	static inline void blkg_get(struct blkio_group *blkg) { }
1adaf3dd TH	343	static inline void blkg_put(struct blkio_group *blkg) { }
afc24d49	344
2f5ea477 JA	345	#endif
2f5ea477 JA	346
32e380ae	347	#ifdef CONFIG_BLK_CGROUP
31e4c28d VG	348	extern struct blkio_cgroup blkio_root_cgroup;
31e4c28d VG	349	extern struct blkio_cgroup cgroup_to_blkio_cgroup(struct cgroup cgroup);
4f85cb96	350	extern struct blkio_cgroup bio_blkio_cgroup(struct bio bio);
cd1604fa	351	extern struct blkio_group blkg_lookup(struct blkio_cgroup blkcg,
e8989fae	352	struct request_queue *q);
cd1604fa	353	struct blkio_group blkg_lookup_create(struct blkio_cgroup blkcg,
3c96cb32	354	struct request_queue *q);
31e4c28d	355	#else
2f5ea477	356	struct cgroup;
31e4c28d VG	357	static inline struct blkio_cgroup *
31e4c28d VG	358	cgroup_to_blkio_cgroup(struct cgroup *cgroup) { return NULL; }
70087dc3	359	static inline struct blkio_cgroup *
4f85cb96	360	bio_blkio_cgroup(struct bio *bio) { return NULL; }
31e4c28d	361
cd1604fa TH	362	static inline struct blkio_group blkg_lookup(struct blkio_cgroup blkcg,
cd1604fa TH	363	void *key) { return NULL; }
31e4c28d VG	364	#endif
31e4c28d VG	365	#endif /* _BLK_CGROUP_H */