[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>

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

/* 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;

	/* 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[BLKIO_NR_POLICIES];

	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;
	enum blkio_policy_id 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 void 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,
				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 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 void blkio_policy_register(struct blkio_policy_type *blkiop) { }
static inline void blkio_policy_unregister(struct blkio_policy_type *blkiop) { }
static inline void blkg_destroy_all(struct request_queue *q,
				    bool destory_root) { }
static inline void update_root_blkg_pd(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,
				       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
062a644d VG	20	enum blkio_policy_id {
062a644d VG	21	BLKIO_POLICY_PROP = 0, /* Proportional Bandwidth division */
4c9eefa1	22	BLKIO_POLICY_THROTL, /* Throttling */
035d10b2 TH	23
035d10b2 TH	24	BLKIO_NR_POLICIES,
062a644d VG	25	};
062a644d VG	26
9355aede VG	27	/* Max limits for throttle policy */
	28	#define THROTL_IOPS_MAX UINT_MAX
	29
3381cb8d TH	30	/* CFQ specific, out here for blkcg->cfq_weight */
	31	#define CFQ_WEIGHT_MIN 10
	32	#define CFQ_WEIGHT_MAX 1000
	33	#define CFQ_WEIGHT_DEFAULT 500
	34
f48ec1d7 TH	35	#ifdef CONFIG_BLK_CGROUP
f48ec1d7 TH	36
edcb0722 TH	37	enum blkg_rwstat_type {
	38	BLKG_RWSTAT_READ,
	39	BLKG_RWSTAT_WRITE,
	40	BLKG_RWSTAT_SYNC,
	41	BLKG_RWSTAT_ASYNC,
	42
	43	BLKG_RWSTAT_NR,
	44	BLKG_RWSTAT_TOTAL = BLKG_RWSTAT_NR,
303a3acb DS	45	};
303a3acb DS	46
31e4c28d VG	47	struct blkio_cgroup {
31e4c28d VG	48	struct cgroup_subsys_state css;
31e4c28d VG	49	spinlock_t lock;
31e4c28d VG	50	struct hlist_head blkg_list;
9a9e8a26 TH	51
	52	/* for policies to test whether associated blkcg has changed */
	53	uint64_t id;
3381cb8d TH	54
	55	/* TODO: per-policy storage in blkio_cgroup */
	56	unsigned int cfq_weight; /* belongs to cfq */
31e4c28d VG	57	};
31e4c28d VG	58
edcb0722 TH	59	struct blkg_stat {
	60	struct u64_stats_sync syncp;
	61	uint64_t cnt;
	62	};
	63
	64	struct blkg_rwstat {
	65	struct u64_stats_sync syncp;
	66	uint64_t cnt[BLKG_RWSTAT_NR];
	67	};
	68
0381411e TH	69	/* per-blkg per-policy data */
	70	struct blkg_policy_data {
	71	/* the blkg this per-policy data belongs to */
	72	struct blkio_group *blkg;
	73
	74	/* pol->pdata_size bytes of private data used by policy impl */
	75	char pdata[] __aligned(__alignof__(unsigned long long));
	76	};
	77
31e4c28d	78	struct blkio_group {
c875f4d0 TH	79	/* Pointer to the associated request_queue */
c875f4d0 TH	80	struct request_queue *q;
e8989fae	81	struct list_head q_node;
31e4c28d	82	struct hlist_node blkcg_node;
7ee9c562	83	struct blkio_cgroup *blkcg;
2868ef7b VG	84	/* Store cgroup path */
2868ef7b VG	85	char path[128];
1adaf3dd TH	86	/* reference count */
1adaf3dd TH	87	int refcnt;
22084190	88
549d3aa8	89	struct blkg_policy_data *pd[BLKIO_NR_POLICIES];
1adaf3dd TH	90
1adaf3dd TH	91	struct rcu_head rcu_head;
31e4c28d VG	92	};
31e4c28d VG	93
0381411e	94	typedef void (blkio_init_group_fn)(struct blkio_group *blkg);
9ade5ea4 TH	95	typedef void (blkio_exit_group_fn)(struct blkio_group *blkg);
9ade5ea4 TH	96	typedef void (blkio_reset_group_stats_fn)(struct blkio_group *blkg);
3e252066 VG	97
3e252066 VG	98	struct blkio_policy_ops {
0381411e	99	blkio_init_group_fn *blkio_init_group_fn;
9ade5ea4 TH	100	blkio_exit_group_fn *blkio_exit_group_fn;
9ade5ea4 TH	101	blkio_reset_group_stats_fn *blkio_reset_group_stats_fn;
3e252066 VG	102	};
	103
	104	struct blkio_policy_type {
3e252066	105	struct blkio_policy_ops ops;
062a644d	106	enum blkio_policy_id plid;
0381411e	107	size_t pdata_size; /* policy specific private data size */
44ea53de	108	struct cftype cftypes; / cgroup files for the policy */
3e252066 VG	109	};
3e252066 VG	110
5efd6113 TH	111	extern int blkcg_init_queue(struct request_queue *q);
	112	extern void blkcg_drain_queue(struct request_queue *q);
	113	extern void blkcg_exit_queue(struct request_queue *q);
	114
3e252066 VG	115	/* Blkio controller policy registration */
	116	extern void blkio_policy_register(struct blkio_policy_type *);
	117	extern void blkio_policy_unregister(struct blkio_policy_type *);
e8989fae TH	118	extern void blkg_destroy_all(struct request_queue *q, bool destroy_root);
e8989fae TH	119	extern void update_root_blkg_pd(struct request_queue *q,
ec399347	120	const struct blkio_policy_type *pol);
3e252066	121
829fdb50	122	void blkcg_print_blkgs(struct seq_file sf, struct blkio_cgroup blkcg,
d366e7ec	123	u64 (prfill)(struct seq_file , void *, int),
ec399347 TH	124	const struct blkio_policy_type *pol, int data,
ec399347 TH	125	bool show_total);
d366e7ec TH	126	u64 __blkg_prfill_u64(struct seq_file sf, void pdata, u64 v);
d366e7ec TH	127	u64 __blkg_prfill_rwstat(struct seq_file sf, void pdata,
829fdb50	128	const struct blkg_rwstat *rwstat);
5bc4afb1 TH	129	u64 blkg_prfill_stat(struct seq_file sf, void pdata, int off);
5bc4afb1 TH	130	u64 blkg_prfill_rwstat(struct seq_file sf, void pdata, int off);
829fdb50 TH	131
	132	struct blkg_conf_ctx {
	133	struct gendisk *disk;
	134	struct blkio_group *blkg;
	135	u64 v;
	136	};
	137
	138	int blkg_conf_prep(struct blkio_cgroup blkcg, const char input,
	139	struct blkg_conf_ctx *ctx);
	140	void blkg_conf_finish(struct blkg_conf_ctx *ctx);
	141
	142
0381411e TH	143	/**
	144	* blkg_to_pdata - get policy private data
	145	* @blkg: blkg of interest
	146	* @pol: policy of interest
	147	*
	148	* Return pointer to private data associated with the @blkg-@pol pair.
	149	*/
	150	static inline void blkg_to_pdata(struct blkio_group blkg,
	151	struct blkio_policy_type *pol)
	152	{
549d3aa8	153	return blkg ? blkg->pd[pol->plid]->pdata : NULL;
0381411e TH	154	}
	155
	156	/**
	157	* pdata_to_blkg - get blkg associated with policy private data
	158	* @pdata: policy private data of interest
0381411e	159	*
aaec55a0	160	* @pdata is policy private data. Determine the blkg it's associated with.
0381411e	161	*/
aaec55a0	162	static inline struct blkio_group pdata_to_blkg(void pdata)
0381411e TH	163	{
	164	if (pdata) {
	165	struct blkg_policy_data *pd =
	166	container_of(pdata, struct blkg_policy_data, pdata);
	167	return pd->blkg;
	168	}
	169	return NULL;
	170	}
	171
afc24d49 VG	172	static inline char blkg_path(struct blkio_group blkg)
	173	{
	174	return blkg->path;
	175	}
	176
1adaf3dd TH	177	/**
	178	* blkg_get - get a blkg reference
	179	* @blkg: blkg to get
	180	*
	181	* The caller should be holding queue_lock and an existing reference.
	182	*/
	183	static inline void blkg_get(struct blkio_group *blkg)
	184	{
	185	lockdep_assert_held(blkg->q->queue_lock);
	186	WARN_ON_ONCE(!blkg->refcnt);
	187	blkg->refcnt++;
	188	}
	189
	190	void __blkg_release(struct blkio_group *blkg);
	191
	192	/**
	193	* blkg_put - put a blkg reference
	194	* @blkg: blkg to put
	195	*
	196	* The caller should be holding queue_lock.
	197	*/
	198	static inline void blkg_put(struct blkio_group *blkg)
	199	{
	200	lockdep_assert_held(blkg->q->queue_lock);
	201	WARN_ON_ONCE(blkg->refcnt <= 0);
	202	if (!--blkg->refcnt)
	203	__blkg_release(blkg);
	204	}
	205
edcb0722 TH	206	/**
	207	* blkg_stat_add - add a value to a blkg_stat
	208	* @stat: target blkg_stat
	209	* @val: value to add
	210	*
	211	* Add @val to @stat. The caller is responsible for synchronizing calls to
	212	* this function.
	213	*/
	214	static inline void blkg_stat_add(struct blkg_stat *stat, uint64_t val)
	215	{
	216	u64_stats_update_begin(&stat->syncp);
	217	stat->cnt += val;
	218	u64_stats_update_end(&stat->syncp);
	219	}
	220
	221	/**
	222	* blkg_stat_read - read the current value of a blkg_stat
	223	* @stat: blkg_stat to read
	224	*
	225	* Read the current value of @stat. This function can be called without
	226	* synchroniztion and takes care of u64 atomicity.
	227	*/
	228	static inline uint64_t blkg_stat_read(struct blkg_stat *stat)
	229	{
	230	unsigned int start;
	231	uint64_t v;
	232
	233	do {
	234	start = u64_stats_fetch_begin(&stat->syncp);
	235	v = stat->cnt;
	236	} while (u64_stats_fetch_retry(&stat->syncp, start));
	237
	238	return v;
	239	}
	240
	241	/**
	242	* blkg_stat_reset - reset a blkg_stat
	243	* @stat: blkg_stat to reset
	244	*/
	245	static inline void blkg_stat_reset(struct blkg_stat *stat)
	246	{
	247	stat->cnt = 0;
	248	}
	249
	250	/**
	251	* blkg_rwstat_add - add a value to a blkg_rwstat
	252	* @rwstat: target blkg_rwstat
	253	* @rw: mask of REQ_{WRITE\|SYNC}
	254	* @val: value to add
	255	*
	256	* Add @val to @rwstat. The counters are chosen according to @rw. The
	257	* caller is responsible for synchronizing calls to this function.
	258	*/
	259	static inline void blkg_rwstat_add(struct blkg_rwstat *rwstat,
	260	int rw, uint64_t val)
	261	{
	262	u64_stats_update_begin(&rwstat->syncp);
	263
	264	if (rw & REQ_WRITE)
	265	rwstat->cnt[BLKG_RWSTAT_WRITE] += val;
	266	else
	267	rwstat->cnt[BLKG_RWSTAT_READ] += val;
	268	if (rw & REQ_SYNC)
	269	rwstat->cnt[BLKG_RWSTAT_SYNC] += val;
270	else
271	rwstat->cnt[BLKG_RWSTAT_ASYNC] += val;
272
273	u64_stats_update_end(&rwstat->syncp);
274	}
275
276	/**
277	* blkg_rwstat_read - read the current values of a blkg_rwstat
278	* @rwstat: blkg_rwstat to read
279	*
280	* Read the current snapshot of @rwstat and return it as the return value.
281	* This function can be called without synchronization and takes care of
282	* u64 atomicity.
283	*/
284	static struct blkg_rwstat blkg_rwstat_read(struct blkg_rwstat *rwstat)
285	{
286	unsigned int start;
287	struct blkg_rwstat tmp;
288
289	do {
290	start = u64_stats_fetch_begin(&rwstat->syncp);
291	tmp = *rwstat;
292	} while (u64_stats_fetch_retry(&rwstat->syncp, start));
293
294	return tmp;
295	}
296
297	/**
298	* blkg_rwstat_sum - read the total count of a blkg_rwstat
299	* @rwstat: blkg_rwstat to read
300	*
301	* Return the total count of @rwstat regardless of the IO direction. This
302	* function can be called without synchronization and takes care of u64
303	* atomicity.
304	*/
305	static inline uint64_t blkg_rwstat_sum(struct blkg_rwstat *rwstat)
306	{
307	struct blkg_rwstat tmp = blkg_rwstat_read(rwstat);
308
309	return tmp.cnt[BLKG_RWSTAT_READ] + tmp.cnt[BLKG_RWSTAT_WRITE];
310	}
311
312	/**
313	* blkg_rwstat_reset - reset a blkg_rwstat
314	* @rwstat: blkg_rwstat to reset
315	*/
316	static inline void blkg_rwstat_reset(struct blkg_rwstat *rwstat)
317	{
318	memset(rwstat->cnt, 0, sizeof(rwstat->cnt));
319	}
320
2f5ea477 JA	321	#else
	322
	323	struct blkio_group {
	324	};
	325
3e252066 VG	326	struct blkio_policy_type {
	327	};
	328
5efd6113 TH	329	static inline int blkcg_init_queue(struct request_queue *q) { return 0; }
	330	static inline void blkcg_drain_queue(struct request_queue *q) { }
	331	static inline void blkcg_exit_queue(struct request_queue *q) { }
3e252066 VG	332	static inline void blkio_policy_register(struct blkio_policy_type *blkiop) { }
3e252066 VG	333	static inline void blkio_policy_unregister(struct blkio_policy_type *blkiop) { }
03aa264a	334	static inline void blkg_destroy_all(struct request_queue *q,
03aa264a	335	bool destory_root) { }
e8989fae	336	static inline void update_root_blkg_pd(struct request_queue *q,
ec399347	337	const struct blkio_policy_type *pol) { }
3e252066	338
0381411e TH	339	static inline void blkg_to_pdata(struct blkio_group blkg,
	340	struct blkio_policy_type *pol) { return NULL; }
	341	static inline struct blkio_group pdata_to_blkg(void pdata,
	342	struct blkio_policy_type *pol) { return NULL; }
afc24d49	343	static inline char blkg_path(struct blkio_group blkg) { return NULL; }
1adaf3dd TH	344	static inline void blkg_get(struct blkio_group *blkg) { }
1adaf3dd TH	345	static inline void blkg_put(struct blkio_group *blkg) { }
afc24d49	346
2f5ea477 JA	347	#endif
2f5ea477 JA	348
32e380ae	349	#ifdef CONFIG_BLK_CGROUP
31e4c28d VG	350	extern struct blkio_cgroup blkio_root_cgroup;
31e4c28d VG	351	extern struct blkio_cgroup cgroup_to_blkio_cgroup(struct cgroup cgroup);
4f85cb96	352	extern struct blkio_cgroup bio_blkio_cgroup(struct bio bio);
cd1604fa	353	extern struct blkio_group blkg_lookup(struct blkio_cgroup blkcg,
e8989fae	354	struct request_queue *q);
cd1604fa TH	355	struct blkio_group blkg_lookup_create(struct blkio_cgroup blkcg,
cd1604fa TH	356	struct request_queue *q,
cd1604fa	357	bool for_root);
31e4c28d	358	#else
2f5ea477	359	struct cgroup;
31e4c28d VG	360	static inline struct blkio_cgroup *
31e4c28d VG	361	cgroup_to_blkio_cgroup(struct cgroup *cgroup) { return NULL; }
70087dc3	362	static inline struct blkio_cgroup *
4f85cb96	363	bio_blkio_cgroup(struct bio *bio) { return NULL; }
31e4c28d	364
cd1604fa TH	365	static inline struct blkio_group blkg_lookup(struct blkio_cgroup blkcg,
cd1604fa TH	366	void *key) { return NULL; }
31e4c28d VG	367	#endif
31e4c28d VG	368	#endif /* _BLK_CGROUP_H */