[mirror_ubuntu-artful-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>
#include <linux/radix-tree.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 blkcg_gq;

struct blkcg {
	struct cgroup_subsys_state	css;
	spinlock_t			lock;

	struct radix_tree_root		blkg_tree;
	struct blkcg_gq			*blkg_hint;
	struct hlist_head		blkg_list;

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

	/* TODO: per-policy storage in blkcg */
	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];
};

/*
 * A blkcg_gq (blkg) is association between a block cgroup (blkcg) and a
 * request_queue (q).  This is used by blkcg policies which need to track
 * information per blkcg - q pair.
 *
 * There can be multiple active blkcg policies and each has its private
 * data on each blkg, the size of which is determined by
 * blkcg_policy->pd_size.  blkcg core allocates and frees such areas
 * together with blkg and invokes pd_init/exit_fn() methods.
 *
 * Such private data must embed struct blkg_policy_data (pd) at the
 * beginning and pd_size can't be smaller than pd.
 */
struct blkg_policy_data {
	/* the blkg this per-policy data belongs to */
	struct blkcg_gq			*blkg;

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

/* association between a blk cgroup and a request queue */
struct blkcg_gq {
	/* Pointer to the associated request_queue */
	struct request_queue		*q;
	struct list_head		q_node;
	struct hlist_node		blkcg_node;
	struct blkcg			*blkcg;
	/* reference count */
	int				refcnt;

	struct blkg_policy_data		*pd[BLKCG_MAX_POLS];

	struct rcu_head			rcu_head;
};

typedef void (blkcg_pol_init_pd_fn)(struct blkcg_gq *blkg);
typedef void (blkcg_pol_exit_pd_fn)(struct blkcg_gq *blkg);
typedef void (blkcg_pol_reset_pd_stats_fn)(struct blkcg_gq *blkg);

struct blkcg_policy {
	int				plid;
	/* policy specific private data size */
	size_t				pd_size;
	/* cgroup files for the policy */
	struct cftype			*cftypes;

	/* operations */
	blkcg_pol_init_pd_fn		*pd_init_fn;
	blkcg_pol_exit_pd_fn		*pd_exit_fn;
	blkcg_pol_reset_pd_stats_fn	*pd_reset_stats_fn;
};

extern struct blkcg blkcg_root;

struct blkcg *cgroup_to_blkcg(struct cgroup *cgroup);
struct blkcg *bio_blkcg(struct bio *bio);
struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, struct request_queue *q);
struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
				    struct request_queue *q);
int blkcg_init_queue(struct request_queue *q);
void blkcg_drain_queue(struct request_queue *q);
void blkcg_exit_queue(struct request_queue *q);

/* Blkio controller policy registration */
int blkcg_policy_register(struct blkcg_policy *pol);
void blkcg_policy_unregister(struct blkcg_policy *pol);
int blkcg_activate_policy(struct request_queue *q,
			  const struct blkcg_policy *pol);
void blkcg_deactivate_policy(struct request_queue *q,
			     const struct blkcg_policy *pol);

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

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

int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *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 struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
						  struct blkcg_policy *pol)
{
	return blkg ? blkg->pd[pol->plid] : NULL;
}

/**
 * pdata_to_blkg - get blkg associated with policy private data
 * @pd: policy private data of interest
 *
 * @pd is policy private data.  Determine the blkg it's associated with.
 */
static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd)
{
	return pd ? pd->blkg : NULL;
}

/**
 * blkg_path - format cgroup path of blkg
 * @blkg: blkg of interest
 * @buf: target buffer
 * @buflen: target buffer length
 *
 * Format the path of the cgroup of @blkg into @buf.
 */
static inline int blkg_path(struct blkcg_gq *blkg, char *buf, int buflen)
{
	int ret;

	rcu_read_lock();
	ret = cgroup_path(blkg->blkcg->css.cgroup, buf, buflen);
	rcu_read_unlock();
	if (ret)
		strncpy(buf, "<unavailable>", buflen);
	return ret;
}

/**
 * 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 blkcg_gq *blkg)
{
	lockdep_assert_held(blkg->q->queue_lock);
	WARN_ON_ONCE(!blkg->refcnt);
	blkg->refcnt++;
}

void __blkg_release(struct blkcg_gq *blkg);

/**
 * blkg_put - put a blkg reference
 * @blkg: blkg to put
 *
 * The caller should be holding queue_lock.
 */
static inline void blkg_put(struct blkcg_gq *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	/* CONFIG_BLK_CGROUP */

struct cgroup;

struct blkg_policy_data {
};

struct blkcg_gq {
};

struct blkcg_policy {
};

static inline struct blkcg *cgroup_to_blkcg(struct cgroup *cgroup) { return NULL; }
static inline struct blkcg *bio_blkcg(struct bio *bio) { return NULL; }
static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, void *key) { return NULL; }
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 blkcg_policy_register(struct blkcg_policy *pol) { return 0; }
static inline void blkcg_policy_unregister(struct blkcg_policy *pol) { }
static inline int blkcg_activate_policy(struct request_queue *q,
					const struct blkcg_policy *pol) { return 0; }
static inline void blkcg_deactivate_policy(struct request_queue *q,
					   const struct blkcg_policy *pol) { }

static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
						  struct blkcg_policy *pol) { return NULL; }
static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd) { return NULL; }
static inline char *blkg_path(struct blkcg_gq *blkg) { return NULL; }
static inline void blkg_get(struct blkcg_gq *blkg) { }
static inline void blkg_put(struct blkcg_gq *blkg) { }

#endif	/* CONFIG_BLK_CGROUP */
#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>
a637120e	19	#include <linux/radix-tree.h>
31e4c28d	20
9355aede VG	21	/* Max limits for throttle policy */
	22	#define THROTL_IOPS_MAX UINT_MAX
	23
3381cb8d TH	24	/* CFQ specific, out here for blkcg->cfq_weight */
	25	#define CFQ_WEIGHT_MIN 10
	26	#define CFQ_WEIGHT_MAX 1000
	27	#define CFQ_WEIGHT_DEFAULT 500
	28
f48ec1d7 TH	29	#ifdef CONFIG_BLK_CGROUP
f48ec1d7 TH	30
edcb0722 TH	31	enum blkg_rwstat_type {
	32	BLKG_RWSTAT_READ,
	33	BLKG_RWSTAT_WRITE,
	34	BLKG_RWSTAT_SYNC,
	35	BLKG_RWSTAT_ASYNC,
	36
	37	BLKG_RWSTAT_NR,
	38	BLKG_RWSTAT_TOTAL = BLKG_RWSTAT_NR,
303a3acb DS	39	};
303a3acb DS	40
a637120e TH	41	struct blkcg_gq;
a637120e TH	42
3c798398	43	struct blkcg {
36558c8a TH	44	struct cgroup_subsys_state css;
36558c8a TH	45	spinlock_t lock;
a637120e TH	46
	47	struct radix_tree_root blkg_tree;
	48	struct blkcg_gq *blkg_hint;
36558c8a	49	struct hlist_head blkg_list;
9a9e8a26 TH	50
9a9e8a26 TH	51	/* for policies to test whether associated blkcg has changed */
36558c8a	52	uint64_t id;
3381cb8d	53
3c798398	54	/* TODO: per-policy storage in blkcg */
36558c8a	55	unsigned int cfq_weight; /* belongs to cfq */
31e4c28d VG	56	};
31e4c28d VG	57
edcb0722 TH	58	struct blkg_stat {
	59	struct u64_stats_sync syncp;
	60	uint64_t cnt;
	61	};
	62
	63	struct blkg_rwstat {
	64	struct u64_stats_sync syncp;
	65	uint64_t cnt[BLKG_RWSTAT_NR];
	66	};
	67
f95a04af TH	68	/*
	69	* A blkcg_gq (blkg) is association between a block cgroup (blkcg) and a
	70	* request_queue (q). This is used by blkcg policies which need to track
	71	* information per blkcg - q pair.
	72	*
	73	* There can be multiple active blkcg policies and each has its private
	74	* data on each blkg, the size of which is determined by
	75	* blkcg_policy->pd_size. blkcg core allocates and frees such areas
	76	* together with blkg and invokes pd_init/exit_fn() methods.
	77	*
	78	* Such private data must embed struct blkg_policy_data (pd) at the
	79	* beginning and pd_size can't be smaller than pd.
	80	*/
0381411e TH	81	struct blkg_policy_data {
0381411e TH	82	/* the blkg this per-policy data belongs to */
3c798398	83	struct blkcg_gq *blkg;
0381411e	84
a2b1693b	85	/* used during policy activation */
36558c8a	86	struct list_head alloc_node;
0381411e TH	87	};
0381411e TH	88
3c798398 TH	89	/* association between a blk cgroup and a request queue */
3c798398 TH	90	struct blkcg_gq {
c875f4d0	91	/* Pointer to the associated request_queue */
36558c8a TH	92	struct request_queue *q;
	93	struct list_head q_node;
	94	struct hlist_node blkcg_node;
3c798398	95	struct blkcg *blkcg;
1adaf3dd	96	/* reference count */
36558c8a	97	int refcnt;
22084190	98
36558c8a	99	struct blkg_policy_data *pd[BLKCG_MAX_POLS];
1adaf3dd	100
36558c8a	101	struct rcu_head rcu_head;
31e4c28d VG	102	};
31e4c28d VG	103
3c798398 TH	104	typedef void (blkcg_pol_init_pd_fn)(struct blkcg_gq *blkg);
	105	typedef void (blkcg_pol_exit_pd_fn)(struct blkcg_gq *blkg);
	106	typedef void (blkcg_pol_reset_pd_stats_fn)(struct blkcg_gq *blkg);
3e252066	107
3c798398	108	struct blkcg_policy {
36558c8a TH	109	int plid;
36558c8a TH	110	/* policy specific private data size */
f95a04af	111	size_t pd_size;
36558c8a TH	112	/* cgroup files for the policy */
36558c8a TH	113	struct cftype *cftypes;
f9fcc2d3 TH	114
	115	/* operations */
	116	blkcg_pol_init_pd_fn *pd_init_fn;
	117	blkcg_pol_exit_pd_fn *pd_exit_fn;
	118	blkcg_pol_reset_pd_stats_fn *pd_reset_stats_fn;
3e252066 VG	119	};
3e252066 VG	120
3c798398	121	extern struct blkcg blkcg_root;
36558c8a	122
3c798398 TH	123	struct blkcg cgroup_to_blkcg(struct cgroup cgroup);
	124	struct blkcg bio_blkcg(struct bio bio);
	125	struct blkcg_gq blkg_lookup(struct blkcg blkcg, struct request_queue *q);
	126	struct blkcg_gq blkg_lookup_create(struct blkcg blkcg,
	127	struct request_queue *q);
36558c8a TH	128	int blkcg_init_queue(struct request_queue *q);
	129	void blkcg_drain_queue(struct request_queue *q);
	130	void blkcg_exit_queue(struct request_queue *q);
5efd6113	131
3e252066	132	/* Blkio controller policy registration */
3c798398 TH	133	int blkcg_policy_register(struct blkcg_policy *pol);
3c798398 TH	134	void blkcg_policy_unregister(struct blkcg_policy *pol);
36558c8a	135	int blkcg_activate_policy(struct request_queue *q,
3c798398	136	const struct blkcg_policy *pol);
36558c8a	137	void blkcg_deactivate_policy(struct request_queue *q,
3c798398	138	const struct blkcg_policy *pol);
3e252066	139
3c798398	140	void blkcg_print_blkgs(struct seq_file sf, struct blkcg blkcg,
f95a04af TH	141	u64 (prfill)(struct seq_file ,
f95a04af TH	142	struct blkg_policy_data *, int),
3c798398	143	const struct blkcg_policy *pol, int data,
ec399347	144	bool show_total);
f95a04af TH	145	u64 __blkg_prfill_u64(struct seq_file sf, struct blkg_policy_data pd, u64 v);
f95a04af TH	146	u64 __blkg_prfill_rwstat(struct seq_file sf, struct blkg_policy_data pd,
829fdb50	147	const struct blkg_rwstat *rwstat);
f95a04af TH	148	u64 blkg_prfill_stat(struct seq_file sf, struct blkg_policy_data pd, int off);
	149	u64 blkg_prfill_rwstat(struct seq_file sf, struct blkg_policy_data pd,
	150	int off);
829fdb50 TH	151
829fdb50 TH	152	struct blkg_conf_ctx {
36558c8a	153	struct gendisk *disk;
3c798398	154	struct blkcg_gq *blkg;
36558c8a	155	u64 v;
829fdb50 TH	156	};
829fdb50 TH	157
3c798398 TH	158	int blkg_conf_prep(struct blkcg blkcg, const struct blkcg_policy pol,
3c798398 TH	159	const char input, struct blkg_conf_ctx ctx);
829fdb50 TH	160	void blkg_conf_finish(struct blkg_conf_ctx *ctx);
	161
	162
0381411e TH	163	/**
	164	* blkg_to_pdata - get policy private data
	165	* @blkg: blkg of interest
	166	* @pol: policy of interest
	167	*
	168	* Return pointer to private data associated with the @blkg-@pol pair.
	169	*/
f95a04af TH	170	static inline struct blkg_policy_data blkg_to_pd(struct blkcg_gq blkg,
f95a04af TH	171	struct blkcg_policy *pol)
0381411e	172	{
f95a04af	173	return blkg ? blkg->pd[pol->plid] : NULL;
0381411e TH	174	}
	175
	176	/**
	177	* pdata_to_blkg - get blkg associated with policy private data
f95a04af	178	* @pd: policy private data of interest
0381411e	179	*
f95a04af	180	* @pd is policy private data. Determine the blkg it's associated with.
0381411e	181	*/
f95a04af	182	static inline struct blkcg_gq pd_to_blkg(struct blkg_policy_data pd)
0381411e	183	{
f95a04af	184	return pd ? pd->blkg : NULL;
0381411e TH	185	}
0381411e TH	186
54e7ed12 TH	187	/**
	188	* blkg_path - format cgroup path of blkg
	189	* @blkg: blkg of interest
	190	* @buf: target buffer
	191	* @buflen: target buffer length
	192	*
	193	* Format the path of the cgroup of @blkg into @buf.
	194	*/
3c798398	195	static inline int blkg_path(struct blkcg_gq blkg, char buf, int buflen)
afc24d49	196	{
54e7ed12 TH	197	int ret;
	198
	199	rcu_read_lock();
	200	ret = cgroup_path(blkg->blkcg->css.cgroup, buf, buflen);
	201	rcu_read_unlock();
	202	if (ret)
	203	strncpy(buf, "<unavailable>", buflen);
	204	return ret;
afc24d49 VG	205	}
afc24d49 VG	206
1adaf3dd TH	207	/**
	208	* blkg_get - get a blkg reference
	209	* @blkg: blkg to get
	210	*
	211	* The caller should be holding queue_lock and an existing reference.
	212	*/
3c798398	213	static inline void blkg_get(struct blkcg_gq *blkg)
1adaf3dd TH	214	{
	215	lockdep_assert_held(blkg->q->queue_lock);
	216	WARN_ON_ONCE(!blkg->refcnt);
	217	blkg->refcnt++;
	218	}
	219
3c798398	220	void __blkg_release(struct blkcg_gq *blkg);
1adaf3dd TH	221
	222	/**
	223	* blkg_put - put a blkg reference
	224	* @blkg: blkg to put
	225	*
	226	* The caller should be holding queue_lock.
	227	*/
3c798398	228	static inline void blkg_put(struct blkcg_gq *blkg)
1adaf3dd TH	229	{
	230	lockdep_assert_held(blkg->q->queue_lock);
	231	WARN_ON_ONCE(blkg->refcnt <= 0);
	232	if (!--blkg->refcnt)
	233	__blkg_release(blkg);
	234	}
	235
edcb0722 TH	236	/**
	237	* blkg_stat_add - add a value to a blkg_stat
	238	* @stat: target blkg_stat
	239	* @val: value to add
	240	*
	241	* Add @val to @stat. The caller is responsible for synchronizing calls to
	242	* this function.
	243	*/
	244	static inline void blkg_stat_add(struct blkg_stat *stat, uint64_t val)
	245	{
	246	u64_stats_update_begin(&stat->syncp);
	247	stat->cnt += val;
	248	u64_stats_update_end(&stat->syncp);
	249	}
	250
	251	/**
	252	* blkg_stat_read - read the current value of a blkg_stat
	253	* @stat: blkg_stat to read
	254	*
	255	* Read the current value of @stat. This function can be called without
	256	* synchroniztion and takes care of u64 atomicity.
	257	*/
	258	static inline uint64_t blkg_stat_read(struct blkg_stat *stat)
	259	{
	260	unsigned int start;
	261	uint64_t v;
	262
	263	do {
	264	start = u64_stats_fetch_begin(&stat->syncp);
	265	v = stat->cnt;
	266	} while (u64_stats_fetch_retry(&stat->syncp, start));
	267
	268	return v;
	269	}
	270
	271	/**
	272	* blkg_stat_reset - reset a blkg_stat
	273	* @stat: blkg_stat to reset
	274	*/
	275	static inline void blkg_stat_reset(struct blkg_stat *stat)
	276	{
	277	stat->cnt = 0;
	278	}
	279
	280	/**
	281	* blkg_rwstat_add - add a value to a blkg_rwstat
	282	* @rwstat: target blkg_rwstat
	283	* @rw: mask of REQ_{WRITE\|SYNC}
	284	* @val: value to add
	285	*
	286	* Add @val to @rwstat. The counters are chosen according to @rw. The
	287	* caller is responsible for synchronizing calls to this function.
	288	*/
	289	static inline void blkg_rwstat_add(struct blkg_rwstat *rwstat,
	290	int rw, uint64_t val)
	291	{
	292	u64_stats_update_begin(&rwstat->syncp);
	293
	294	if (rw & REQ_WRITE)
	295	rwstat->cnt[BLKG_RWSTAT_WRITE] += val;
	296	else
	297	rwstat->cnt[BLKG_RWSTAT_READ] += val;
	298	if (rw & REQ_SYNC)
	299	rwstat->cnt[BLKG_RWSTAT_SYNC] += val;
300	else
301	rwstat->cnt[BLKG_RWSTAT_ASYNC] += val;
302
303	u64_stats_update_end(&rwstat->syncp);
304	}
305
306	/**
307	* blkg_rwstat_read - read the current values of a blkg_rwstat
308	* @rwstat: blkg_rwstat to read
309	*
310	* Read the current snapshot of @rwstat and return it as the return value.
311	* This function can be called without synchronization and takes care of
312	* u64 atomicity.
313	*/
c94bed89	314	static inline struct blkg_rwstat blkg_rwstat_read(struct blkg_rwstat *rwstat)
edcb0722 TH	315	{
	316	unsigned int start;
	317	struct blkg_rwstat tmp;
	318
	319	do {
	320	start = u64_stats_fetch_begin(&rwstat->syncp);
	321	tmp = *rwstat;
	322	} while (u64_stats_fetch_retry(&rwstat->syncp, start));
	323
	324	return tmp;
	325	}
	326
	327	/**
	328	* blkg_rwstat_sum - read the total count of a blkg_rwstat
	329	* @rwstat: blkg_rwstat to read
	330	*
	331	* Return the total count of @rwstat regardless of the IO direction. This
	332	* function can be called without synchronization and takes care of u64
	333	* atomicity.
	334	*/
	335	static inline uint64_t blkg_rwstat_sum(struct blkg_rwstat *rwstat)
	336	{
	337	struct blkg_rwstat tmp = blkg_rwstat_read(rwstat);
	338
	339	return tmp.cnt[BLKG_RWSTAT_READ] + tmp.cnt[BLKG_RWSTAT_WRITE];
	340	}
	341
	342	/**
	343	* blkg_rwstat_reset - reset a blkg_rwstat
	344	* @rwstat: blkg_rwstat to reset
	345	*/
	346	static inline void blkg_rwstat_reset(struct blkg_rwstat *rwstat)
	347	{
	348	memset(rwstat->cnt, 0, sizeof(rwstat->cnt));
	349	}
	350
36558c8a TH	351	#else /* CONFIG_BLK_CGROUP */
	352
	353	struct cgroup;
2f5ea477	354
f95a04af TH	355	struct blkg_policy_data {
	356	};
	357
3c798398	358	struct blkcg_gq {
2f5ea477 JA	359	};
2f5ea477 JA	360
3c798398	361	struct blkcg_policy {
3e252066 VG	362	};
3e252066 VG	363
3c798398 TH	364	static inline struct blkcg cgroup_to_blkcg(struct cgroup cgroup) { return NULL; }
	365	static inline struct blkcg bio_blkcg(struct bio bio) { return NULL; }
	366	static inline struct blkcg_gq blkg_lookup(struct blkcg blkcg, void *key) { return NULL; }
5efd6113 TH	367	static inline int blkcg_init_queue(struct request_queue *q) { return 0; }
	368	static inline void blkcg_drain_queue(struct request_queue *q) { }
	369	static inline void blkcg_exit_queue(struct request_queue *q) { }
3c798398 TH	370	static inline int blkcg_policy_register(struct blkcg_policy *pol) { return 0; }
3c798398 TH	371	static inline void blkcg_policy_unregister(struct blkcg_policy *pol) { }
a2b1693b	372	static inline int blkcg_activate_policy(struct request_queue *q,
3c798398	373	const struct blkcg_policy *pol) { return 0; }
a2b1693b	374	static inline void blkcg_deactivate_policy(struct request_queue *q,
3c798398 TH	375	const struct blkcg_policy *pol) { }
3c798398 TH	376
f95a04af TH	377	static inline struct blkg_policy_data blkg_to_pd(struct blkcg_gq blkg,
	378	struct blkcg_policy *pol) { return NULL; }
	379	static inline struct blkcg_gq pd_to_blkg(struct blkg_policy_data pd) { return NULL; }
3c798398 TH	380	static inline char blkg_path(struct blkcg_gq blkg) { return NULL; }
	381	static inline void blkg_get(struct blkcg_gq *blkg) { }
	382	static inline void blkg_put(struct blkcg_gq *blkg) { }
afc24d49	383
36558c8a TH	384	#endif /* CONFIG_BLK_CGROUP */
36558c8a TH	385	#endif /* _BLK_CGROUP_H */