[linux-2.6-block.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

#ifdef CONFIG_BLK_CGROUP

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

/* cft->private [un]packing for stat printing */
#define BLKCG_STAT_PRIV(pol, off)	(((unsigned)(pol) << 16) | (off))
#define BLKCG_STAT_POL(prv)		((unsigned)(prv) >> 16)
#define BLKCG_STAT_OFF(prv)		((unsigned)(prv) & 0xffff)

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 list_head list;
	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,
				enum blkio_policy_id plid);

void blkcg_print_blkgs(struct seq_file *sf, struct blkio_cgroup *blkcg,
		       u64 (*prfill)(struct seq_file *, struct blkg_policy_data *, int),
		       int 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);
int blkcg_print_stat(struct cgroup *cgrp, struct cftype *cft,
		     struct seq_file *sf);
int blkcg_print_rwstat(struct cgroup *cgrp, struct cftype *cft,
		       struct seq_file *sf);

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,
				       enum blkio_policy_id plid) { }

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
32e380ae	30	#ifdef CONFIG_BLK_CGROUP
2f5ea477	31
3381cb8d TH	32	/* CFQ specific, out here for blkcg->cfq_weight */
	33	#define CFQ_WEIGHT_MIN 10
	34	#define CFQ_WEIGHT_MAX 1000
	35	#define CFQ_WEIGHT_DEFAULT 500
	36
d3d32e69 TH	37	/* cft->private [un]packing for stat printing */
	38	#define BLKCG_STAT_PRIV(pol, off) (((unsigned)(pol) << 16) \| (off))
	39	#define BLKCG_STAT_POL(prv) ((unsigned)(prv) >> 16)
	40	#define BLKCG_STAT_OFF(prv) ((unsigned)(prv) & 0xffff)
2aa4a152	41
edcb0722 TH	42	enum blkg_rwstat_type {
	43	BLKG_RWSTAT_READ,
	44	BLKG_RWSTAT_WRITE,
	45	BLKG_RWSTAT_SYNC,
	46	BLKG_RWSTAT_ASYNC,
	47
	48	BLKG_RWSTAT_NR,
	49	BLKG_RWSTAT_TOTAL = BLKG_RWSTAT_NR,
303a3acb DS	50	};
303a3acb DS	51
31e4c28d VG	52	struct blkio_cgroup {
31e4c28d VG	53	struct cgroup_subsys_state css;
31e4c28d VG	54	spinlock_t lock;
31e4c28d VG	55	struct hlist_head blkg_list;
9a9e8a26 TH	56
	57	/* for policies to test whether associated blkcg has changed */
	58	uint64_t id;
3381cb8d TH	59
	60	/* TODO: per-policy storage in blkio_cgroup */
	61	unsigned int cfq_weight; /* belongs to cfq */
31e4c28d VG	62	};
31e4c28d VG	63
edcb0722 TH	64	struct blkg_stat {
	65	struct u64_stats_sync syncp;
	66	uint64_t cnt;
	67	};
	68
	69	struct blkg_rwstat {
	70	struct u64_stats_sync syncp;
	71	uint64_t cnt[BLKG_RWSTAT_NR];
	72	};
	73
0381411e TH	74	/* per-blkg per-policy data */
	75	struct blkg_policy_data {
	76	/* the blkg this per-policy data belongs to */
	77	struct blkio_group *blkg;
	78
	79	/* pol->pdata_size bytes of private data used by policy impl */
	80	char pdata[] __aligned(__alignof__(unsigned long long));
	81	};
	82
31e4c28d	83	struct blkio_group {
c875f4d0 TH	84	/* Pointer to the associated request_queue */
c875f4d0 TH	85	struct request_queue *q;
e8989fae	86	struct list_head q_node;
31e4c28d	87	struct hlist_node blkcg_node;
7ee9c562	88	struct blkio_cgroup *blkcg;
2868ef7b VG	89	/* Store cgroup path */
2868ef7b VG	90	char path[128];
1adaf3dd TH	91	/* reference count */
1adaf3dd TH	92	int refcnt;
22084190	93
549d3aa8	94	struct blkg_policy_data *pd[BLKIO_NR_POLICIES];
1adaf3dd TH	95
1adaf3dd TH	96	struct rcu_head rcu_head;
31e4c28d VG	97	};
31e4c28d VG	98
0381411e	99	typedef void (blkio_init_group_fn)(struct blkio_group *blkg);
9ade5ea4 TH	100	typedef void (blkio_exit_group_fn)(struct blkio_group *blkg);
9ade5ea4 TH	101	typedef void (blkio_reset_group_stats_fn)(struct blkio_group *blkg);
3e252066 VG	102
3e252066 VG	103	struct blkio_policy_ops {
0381411e	104	blkio_init_group_fn *blkio_init_group_fn;
9ade5ea4 TH	105	blkio_exit_group_fn *blkio_exit_group_fn;
9ade5ea4 TH	106	blkio_reset_group_stats_fn *blkio_reset_group_stats_fn;
3e252066 VG	107	};
	108
	109	struct blkio_policy_type {
	110	struct list_head list;
	111	struct blkio_policy_ops ops;
062a644d	112	enum blkio_policy_id plid;
0381411e	113	size_t pdata_size; /* policy specific private data size */
44ea53de	114	struct cftype cftypes; / cgroup files for the policy */
3e252066 VG	115	};
3e252066 VG	116
5efd6113 TH	117	extern int blkcg_init_queue(struct request_queue *q);
	118	extern void blkcg_drain_queue(struct request_queue *q);
	119	extern void blkcg_exit_queue(struct request_queue *q);
	120
3e252066 VG	121	/* Blkio controller policy registration */
	122	extern void blkio_policy_register(struct blkio_policy_type *);
	123	extern void blkio_policy_unregister(struct blkio_policy_type *);
e8989fae TH	124	extern void blkg_destroy_all(struct request_queue *q, bool destroy_root);
	125	extern void update_root_blkg_pd(struct request_queue *q,
	126	enum blkio_policy_id plid);
3e252066	127
829fdb50 TH	128	void blkcg_print_blkgs(struct seq_file sf, struct blkio_cgroup blkcg,
	129	u64 (prfill)(struct seq_file , struct blkg_policy_data *, int),
	130	int pol, int data, bool show_total);
	131	u64 __blkg_prfill_u64(struct seq_file sf, struct blkg_policy_data pd, u64 v);
	132	u64 __blkg_prfill_rwstat(struct seq_file sf, struct blkg_policy_data pd,
	133	const struct blkg_rwstat *rwstat);
	134	int blkcg_print_stat(struct cgroup cgrp, struct cftype cft,
	135	struct seq_file *sf);
	136	int blkcg_print_rwstat(struct cgroup cgrp, struct cftype cft,
	137	struct seq_file *sf);
829fdb50 TH	138
	139	struct blkg_conf_ctx {
	140	struct gendisk *disk;
	141	struct blkio_group *blkg;
	142	u64 v;
	143	};
	144
	145	int blkg_conf_prep(struct blkio_cgroup blkcg, const char input,
	146	struct blkg_conf_ctx *ctx);
	147	void blkg_conf_finish(struct blkg_conf_ctx *ctx);
	148
	149
0381411e TH	150	/**
	151	* blkg_to_pdata - get policy private data
	152	* @blkg: blkg of interest
	153	* @pol: policy of interest
	154	*
	155	* Return pointer to private data associated with the @blkg-@pol pair.
	156	*/
	157	static inline void blkg_to_pdata(struct blkio_group blkg,
	158	struct blkio_policy_type *pol)
	159	{
549d3aa8	160	return blkg ? blkg->pd[pol->plid]->pdata : NULL;
0381411e TH	161	}
	162
	163	/**
	164	* pdata_to_blkg - get blkg associated with policy private data
	165	* @pdata: policy private data of interest
0381411e	166	*
aaec55a0	167	* @pdata is policy private data. Determine the blkg it's associated with.
0381411e	168	*/
aaec55a0	169	static inline struct blkio_group pdata_to_blkg(void pdata)
0381411e TH	170	{
	171	if (pdata) {
	172	struct blkg_policy_data *pd =
	173	container_of(pdata, struct blkg_policy_data, pdata);
	174	return pd->blkg;
	175	}
	176	return NULL;
	177	}
	178
afc24d49 VG	179	static inline char blkg_path(struct blkio_group blkg)
	180	{
	181	return blkg->path;
	182	}
	183
1adaf3dd TH	184	/**
	185	* blkg_get - get a blkg reference
	186	* @blkg: blkg to get
	187	*
	188	* The caller should be holding queue_lock and an existing reference.
	189	*/
	190	static inline void blkg_get(struct blkio_group *blkg)
	191	{
	192	lockdep_assert_held(blkg->q->queue_lock);
	193	WARN_ON_ONCE(!blkg->refcnt);
	194	blkg->refcnt++;
	195	}
	196
	197	void __blkg_release(struct blkio_group *blkg);
	198
	199	/**
	200	* blkg_put - put a blkg reference
	201	* @blkg: blkg to put
	202	*
	203	* The caller should be holding queue_lock.
	204	*/
	205	static inline void blkg_put(struct blkio_group *blkg)
	206	{
	207	lockdep_assert_held(blkg->q->queue_lock);
	208	WARN_ON_ONCE(blkg->refcnt <= 0);
	209	if (!--blkg->refcnt)
	210	__blkg_release(blkg);
	211	}
	212
edcb0722 TH	213	/**
	214	* blkg_stat_add - add a value to a blkg_stat
	215	* @stat: target blkg_stat
	216	* @val: value to add
	217	*
	218	* Add @val to @stat. The caller is responsible for synchronizing calls to
	219	* this function.
	220	*/
	221	static inline void blkg_stat_add(struct blkg_stat *stat, uint64_t val)
	222	{
	223	u64_stats_update_begin(&stat->syncp);
	224	stat->cnt += val;
	225	u64_stats_update_end(&stat->syncp);
	226	}
	227
	228	/**
	229	* blkg_stat_read - read the current value of a blkg_stat
	230	* @stat: blkg_stat to read
	231	*
	232	* Read the current value of @stat. This function can be called without
	233	* synchroniztion and takes care of u64 atomicity.
	234	*/
	235	static inline uint64_t blkg_stat_read(struct blkg_stat *stat)
	236	{
	237	unsigned int start;
	238	uint64_t v;
	239
	240	do {
	241	start = u64_stats_fetch_begin(&stat->syncp);
	242	v = stat->cnt;
	243	} while (u64_stats_fetch_retry(&stat->syncp, start));
	244
	245	return v;
	246	}
	247
	248	/**
	249	* blkg_stat_reset - reset a blkg_stat
	250	* @stat: blkg_stat to reset
	251	*/
	252	static inline void blkg_stat_reset(struct blkg_stat *stat)
	253	{
	254	stat->cnt = 0;
	255	}
	256
	257	/**
	258	* blkg_rwstat_add - add a value to a blkg_rwstat
	259	* @rwstat: target blkg_rwstat
	260	* @rw: mask of REQ_{WRITE\|SYNC}
	261	* @val: value to add
	262	*
	263	* Add @val to @rwstat. The counters are chosen according to @rw. The
	264	* caller is responsible for synchronizing calls to this function.
	265	*/
	266	static inline void blkg_rwstat_add(struct blkg_rwstat *rwstat,
	267	int rw, uint64_t val)
	268	{
	269	u64_stats_update_begin(&rwstat->syncp);
	270
	271	if (rw & REQ_WRITE)
	272	rwstat->cnt[BLKG_RWSTAT_WRITE] += val;
	273	else
	274	rwstat->cnt[BLKG_RWSTAT_READ] += val;
	275	if (rw & REQ_SYNC)
	276	rwstat->cnt[BLKG_RWSTAT_SYNC] += val;
277	else
278	rwstat->cnt[BLKG_RWSTAT_ASYNC] += val;
279
280	u64_stats_update_end(&rwstat->syncp);
281	}
282
283	/**
284	* blkg_rwstat_read - read the current values of a blkg_rwstat
285	* @rwstat: blkg_rwstat to read
286	*
287	* Read the current snapshot of @rwstat and return it as the return value.
288	* This function can be called without synchronization and takes care of
289	* u64 atomicity.
290	*/
291	static struct blkg_rwstat blkg_rwstat_read(struct blkg_rwstat *rwstat)
292	{
293	unsigned int start;
294	struct blkg_rwstat tmp;
295
296	do {
297	start = u64_stats_fetch_begin(&rwstat->syncp);
298	tmp = *rwstat;
299	} while (u64_stats_fetch_retry(&rwstat->syncp, start));
300
301	return tmp;
302	}
303
304	/**
305	* blkg_rwstat_sum - read the total count of a blkg_rwstat
306	* @rwstat: blkg_rwstat to read
307	*
308	* Return the total count of @rwstat regardless of the IO direction. This
309	* function can be called without synchronization and takes care of u64
310	* atomicity.
311	*/
312	static inline uint64_t blkg_rwstat_sum(struct blkg_rwstat *rwstat)
313	{
314	struct blkg_rwstat tmp = blkg_rwstat_read(rwstat);
315
316	return tmp.cnt[BLKG_RWSTAT_READ] + tmp.cnt[BLKG_RWSTAT_WRITE];
317	}
318
319	/**
320	* blkg_rwstat_reset - reset a blkg_rwstat
321	* @rwstat: blkg_rwstat to reset
322	*/
323	static inline void blkg_rwstat_reset(struct blkg_rwstat *rwstat)
324	{
325	memset(rwstat->cnt, 0, sizeof(rwstat->cnt));
326	}
327
2f5ea477 JA	328	#else
	329
	330	struct blkio_group {
	331	};
	332
3e252066 VG	333	struct blkio_policy_type {
	334	};
	335
5efd6113 TH	336	static inline int blkcg_init_queue(struct request_queue *q) { return 0; }
	337	static inline void blkcg_drain_queue(struct request_queue *q) { }
	338	static inline void blkcg_exit_queue(struct request_queue *q) { }
3e252066 VG	339	static inline void blkio_policy_register(struct blkio_policy_type *blkiop) { }
3e252066 VG	340	static inline void blkio_policy_unregister(struct blkio_policy_type *blkiop) { }
03aa264a	341	static inline void blkg_destroy_all(struct request_queue *q,
03aa264a	342	bool destory_root) { }
e8989fae TH	343	static inline void update_root_blkg_pd(struct request_queue *q,
e8989fae TH	344	enum blkio_policy_id plid) { }
3e252066	345
0381411e TH	346	static inline void blkg_to_pdata(struct blkio_group blkg,
	347	struct blkio_policy_type *pol) { return NULL; }
	348	static inline struct blkio_group pdata_to_blkg(void pdata,
	349	struct blkio_policy_type *pol) { return NULL; }
afc24d49	350	static inline char blkg_path(struct blkio_group blkg) { return NULL; }
1adaf3dd TH	351	static inline void blkg_get(struct blkio_group *blkg) { }
1adaf3dd TH	352	static inline void blkg_put(struct blkio_group *blkg) { }
afc24d49	353
2f5ea477 JA	354	#endif
2f5ea477 JA	355
32e380ae	356	#ifdef CONFIG_BLK_CGROUP
31e4c28d VG	357	extern struct blkio_cgroup blkio_root_cgroup;
31e4c28d VG	358	extern struct blkio_cgroup cgroup_to_blkio_cgroup(struct cgroup cgroup);
4f85cb96	359	extern struct blkio_cgroup bio_blkio_cgroup(struct bio bio);
cd1604fa	360	extern struct blkio_group blkg_lookup(struct blkio_cgroup blkcg,
e8989fae	361	struct request_queue *q);
cd1604fa TH	362	struct blkio_group blkg_lookup_create(struct blkio_cgroup blkcg,
cd1604fa TH	363	struct request_queue *q,
cd1604fa	364	bool for_root);
31e4c28d	365	#else
2f5ea477	366	struct cgroup;
31e4c28d VG	367	static inline struct blkio_cgroup *
31e4c28d VG	368	cgroup_to_blkio_cgroup(struct cgroup *cgroup) { return NULL; }
70087dc3	369	static inline struct blkio_cgroup *
4f85cb96	370	bio_blkio_cgroup(struct bio *bio) { return NULL; }
31e4c28d	371
cd1604fa TH	372	static inline struct blkio_group blkg_lookup(struct blkio_cgroup blkcg,
cd1604fa TH	373	void *key) { return NULL; }
31e4c28d VG	374	#endif
31e4c28d VG	375	#endif /* _BLK_CGROUP_H */