[thirdparty/linux.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);
extern void blkg_destroy_all(struct request_queue *q, bool destroy_root);

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 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_destroy_all(struct request_queue *q,
				    bool destory_root) { }

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,
				       bool for_root);
#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);
e8989fae	118	extern void blkg_destroy_all(struct request_queue *q, bool destroy_root);
3e252066	119
829fdb50	120	void blkcg_print_blkgs(struct seq_file sf, struct blkio_cgroup blkcg,
d366e7ec	121	u64 (prfill)(struct seq_file , void *, int),
ec399347 TH	122	const struct blkio_policy_type *pol, int data,
ec399347 TH	123	bool show_total);
d366e7ec TH	124	u64 __blkg_prfill_u64(struct seq_file sf, void pdata, u64 v);
d366e7ec TH	125	u64 __blkg_prfill_rwstat(struct seq_file sf, void pdata,
829fdb50	126	const struct blkg_rwstat *rwstat);
5bc4afb1 TH	127	u64 blkg_prfill_stat(struct seq_file sf, void pdata, int off);
5bc4afb1 TH	128	u64 blkg_prfill_rwstat(struct seq_file sf, void pdata, int off);
829fdb50 TH	129
	130	struct blkg_conf_ctx {
	131	struct gendisk *disk;
	132	struct blkio_group *blkg;
	133	u64 v;
	134	};
	135
da8b0662 TH	136	int blkg_conf_prep(struct blkio_cgroup *blkcg,
da8b0662 TH	137	const struct blkio_policy_type pol, const char input,
829fdb50 TH	138	struct blkg_conf_ctx *ctx);
	139	void blkg_conf_finish(struct blkg_conf_ctx *ctx);
	140
	141
0381411e TH	142	/**
	143	* blkg_to_pdata - get policy private data
	144	* @blkg: blkg of interest
	145	* @pol: policy of interest
	146	*
	147	* Return pointer to private data associated with the @blkg-@pol pair.
	148	*/
	149	static inline void blkg_to_pdata(struct blkio_group blkg,
	150	struct blkio_policy_type *pol)
	151	{
549d3aa8	152	return blkg ? blkg->pd[pol->plid]->pdata : NULL;
0381411e TH	153	}
	154
	155	/**
	156	* pdata_to_blkg - get blkg associated with policy private data
	157	* @pdata: policy private data of interest
0381411e	158	*
aaec55a0	159	* @pdata is policy private data. Determine the blkg it's associated with.
0381411e	160	*/
aaec55a0	161	static inline struct blkio_group pdata_to_blkg(void pdata)
0381411e TH	162	{
	163	if (pdata) {
	164	struct blkg_policy_data *pd =
	165	container_of(pdata, struct blkg_policy_data, pdata);
	166	return pd->blkg;
	167	}
	168	return NULL;
	169	}
	170
afc24d49 VG	171	static inline char blkg_path(struct blkio_group blkg)
	172	{
	173	return blkg->path;
	174	}
	175
1adaf3dd TH	176	/**
	177	* blkg_get - get a blkg reference
	178	* @blkg: blkg to get
	179	*
	180	* The caller should be holding queue_lock and an existing reference.
	181	*/
	182	static inline void blkg_get(struct blkio_group *blkg)
	183	{
	184	lockdep_assert_held(blkg->q->queue_lock);
	185	WARN_ON_ONCE(!blkg->refcnt);
	186	blkg->refcnt++;
	187	}
	188
	189	void __blkg_release(struct blkio_group *blkg);
	190
	191	/**
	192	* blkg_put - put a blkg reference
	193	* @blkg: blkg to put
	194	*
	195	* The caller should be holding queue_lock.
	196	*/
	197	static inline void blkg_put(struct blkio_group *blkg)
	198	{
	199	lockdep_assert_held(blkg->q->queue_lock);
	200	WARN_ON_ONCE(blkg->refcnt <= 0);
	201	if (!--blkg->refcnt)
	202	__blkg_release(blkg);
	203	}
	204
edcb0722 TH	205	/**
	206	* blkg_stat_add - add a value to a blkg_stat
	207	* @stat: target blkg_stat
	208	* @val: value to add
	209	*
	210	* Add @val to @stat. The caller is responsible for synchronizing calls to
	211	* this function.
	212	*/
	213	static inline void blkg_stat_add(struct blkg_stat *stat, uint64_t val)
	214	{
	215	u64_stats_update_begin(&stat->syncp);
	216	stat->cnt += val;
	217	u64_stats_update_end(&stat->syncp);
	218	}
	219
	220	/**
	221	* blkg_stat_read - read the current value of a blkg_stat
	222	* @stat: blkg_stat to read
	223	*
	224	* Read the current value of @stat. This function can be called without
	225	* synchroniztion and takes care of u64 atomicity.
	226	*/
	227	static inline uint64_t blkg_stat_read(struct blkg_stat *stat)
	228	{
	229	unsigned int start;
	230	uint64_t v;
	231
	232	do {
	233	start = u64_stats_fetch_begin(&stat->syncp);
	234	v = stat->cnt;
	235	} while (u64_stats_fetch_retry(&stat->syncp, start));
	236
	237	return v;
	238	}
	239
	240	/**
	241	* blkg_stat_reset - reset a blkg_stat
	242	* @stat: blkg_stat to reset
	243	*/
	244	static inline void blkg_stat_reset(struct blkg_stat *stat)
	245	{
	246	stat->cnt = 0;
	247	}
	248
	249	/**
	250	* blkg_rwstat_add - add a value to a blkg_rwstat
	251	* @rwstat: target blkg_rwstat
	252	* @rw: mask of REQ_{WRITE\|SYNC}
	253	* @val: value to add
	254	*
	255	* Add @val to @rwstat. The counters are chosen according to @rw. The
	256	* caller is responsible for synchronizing calls to this function.
	257	*/
	258	static inline void blkg_rwstat_add(struct blkg_rwstat *rwstat,
	259	int rw, uint64_t val)
	260	{
	261	u64_stats_update_begin(&rwstat->syncp);
	262
	263	if (rw & REQ_WRITE)
	264	rwstat->cnt[BLKG_RWSTAT_WRITE] += val;
	265	else
	266	rwstat->cnt[BLKG_RWSTAT_READ] += val;
	267	if (rw & REQ_SYNC)
	268	rwstat->cnt[BLKG_RWSTAT_SYNC] += val;
269	else
270	rwstat->cnt[BLKG_RWSTAT_ASYNC] += val;
271
272	u64_stats_update_end(&rwstat->syncp);
273	}
274
275	/**
276	* blkg_rwstat_read - read the current values of a blkg_rwstat
277	* @rwstat: blkg_rwstat to read
278	*
279	* Read the current snapshot of @rwstat and return it as the return value.
280	* This function can be called without synchronization and takes care of
281	* u64 atomicity.
282	*/
283	static struct blkg_rwstat blkg_rwstat_read(struct blkg_rwstat *rwstat)
284	{
285	unsigned int start;
286	struct blkg_rwstat tmp;
287
288	do {
289	start = u64_stats_fetch_begin(&rwstat->syncp);
290	tmp = *rwstat;
291	} while (u64_stats_fetch_retry(&rwstat->syncp, start));
292
293	return tmp;
294	}
295
296	/**
297	* blkg_rwstat_sum - read the total count of a blkg_rwstat
298	* @rwstat: blkg_rwstat to read
299	*
300	* Return the total count of @rwstat regardless of the IO direction. This
301	* function can be called without synchronization and takes care of u64
302	* atomicity.
303	*/
304	static inline uint64_t blkg_rwstat_sum(struct blkg_rwstat *rwstat)
305	{
306	struct blkg_rwstat tmp = blkg_rwstat_read(rwstat);
307
308	return tmp.cnt[BLKG_RWSTAT_READ] + tmp.cnt[BLKG_RWSTAT_WRITE];
309	}
310
311	/**
312	* blkg_rwstat_reset - reset a blkg_rwstat
313	* @rwstat: blkg_rwstat to reset
314	*/
315	static inline void blkg_rwstat_reset(struct blkg_rwstat *rwstat)
316	{
317	memset(rwstat->cnt, 0, sizeof(rwstat->cnt));
318	}
319
2f5ea477 JA	320	#else
	321
	322	struct blkio_group {
	323	};
	324
3e252066 VG	325	struct blkio_policy_type {
	326	};
	327
5efd6113 TH	328	static inline int blkcg_init_queue(struct request_queue *q) { return 0; }
	329	static inline void blkcg_drain_queue(struct request_queue *q) { }
	330	static inline void blkcg_exit_queue(struct request_queue *q) { }
8bd435b3	331	static inline int blkio_policy_register(struct blkio_policy_type *blkiop) { return 0; }
3e252066	332	static inline void blkio_policy_unregister(struct blkio_policy_type *blkiop) { }
a2b1693b TH	333	static inline int blkcg_activate_policy(struct request_queue *q,
	334	const struct blkio_policy_type *pol) { return 0; }
	335	static inline void blkcg_deactivate_policy(struct request_queue *q,
	336	const struct blkio_policy_type *pol) { }
03aa264a	337	static inline void blkg_destroy_all(struct request_queue *q,
03aa264a	338	bool destory_root) { }
3e252066	339
0381411e TH	340	static inline void blkg_to_pdata(struct blkio_group blkg,
	341	struct blkio_policy_type *pol) { return NULL; }
	342	static inline struct blkio_group pdata_to_blkg(void pdata,
	343	struct blkio_policy_type *pol) { return NULL; }
afc24d49	344	static inline char blkg_path(struct blkio_group blkg) { return NULL; }
1adaf3dd TH	345	static inline void blkg_get(struct blkio_group *blkg) { }
1adaf3dd TH	346	static inline void blkg_put(struct blkio_group *blkg) { }
afc24d49	347
2f5ea477 JA	348	#endif
2f5ea477 JA	349
32e380ae	350	#ifdef CONFIG_BLK_CGROUP
31e4c28d VG	351	extern struct blkio_cgroup blkio_root_cgroup;
31e4c28d VG	352	extern struct blkio_cgroup cgroup_to_blkio_cgroup(struct cgroup cgroup);
4f85cb96	353	extern struct blkio_cgroup bio_blkio_cgroup(struct bio bio);
cd1604fa	354	extern struct blkio_group blkg_lookup(struct blkio_cgroup blkcg,
e8989fae	355	struct request_queue *q);
cd1604fa TH	356	struct blkio_group blkg_lookup_create(struct blkio_cgroup blkcg,
cd1604fa TH	357	struct request_queue *q,
cd1604fa	358	bool for_root);
31e4c28d	359	#else
2f5ea477	360	struct cgroup;
31e4c28d VG	361	static inline struct blkio_cgroup *
31e4c28d VG	362	cgroup_to_blkio_cgroup(struct cgroup *cgroup) { return NULL; }
70087dc3	363	static inline struct blkio_cgroup *
4f85cb96	364	bio_blkio_cgroup(struct bio *bio) { return NULL; }
31e4c28d	365
cd1604fa TH	366	static inline struct blkio_group blkg_lookup(struct blkio_cgroup blkcg,
cd1604fa TH	367	void *key) { return NULL; }
31e4c28d VG	368	#endif
31e4c28d VG	369	#endif /* _BLK_CGROUP_H */