blk-cgroup.h 20.2 KB
Newer Older
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
#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>
17
#include <linux/u64_stats_sync.h>
18
#include <linux/seq_file.h>
19
#include <linux/radix-tree.h>
20
#include <linux/blkdev.h>
21
#include <linux/atomic.h>
22

23
24
25
/* Max limits for throttle policy */
#define THROTL_IOPS_MAX		UINT_MAX

Tejun Heo's avatar
Tejun Heo committed
26
27
#ifdef CONFIG_BLK_CGROUP

28
29
30
31
32
33
34
35
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,
36
37
};

38
39
struct blkcg_gq;

Tejun Heo's avatar
Tejun Heo committed
40
struct blkcg {
41
42
	struct cgroup_subsys_state	css;
	spinlock_t			lock;
43
44
45

	struct radix_tree_root		blkg_tree;
	struct blkcg_gq			*blkg_hint;
46
	struct hlist_head		blkg_list;
Tejun Heo's avatar
Tejun Heo committed
47

48
	struct blkcg_policy_data	*cpd[BLKCG_MAX_POLS];
49

Tejun Heo's avatar
Tejun Heo committed
50
	struct list_head		all_blkcgs_node;
51
52
53
#ifdef CONFIG_CGROUP_WRITEBACK
	struct list_head		cgwb_list;
#endif
54
55
};

56
57
58
59
60
61
62
63
64
65
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];
};

66
67
68
69
70
/*
 * 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.
 *
71
72
73
74
75
 * There can be multiple active blkcg policies and each blkg:policy pair is
 * represented by a blkg_policy_data which is allocated and freed by each
 * policy's pd_alloc/free_fn() methods.  A policy can allocate private data
 * area by allocating larger data structure which embeds blkg_policy_data
 * at the beginning.
76
 */
77
struct blkg_policy_data {
Tejun Heo's avatar
Tejun Heo committed
78
	/* the blkg and policy id this per-policy data belongs to */
Tejun Heo's avatar
Tejun Heo committed
79
	struct blkcg_gq			*blkg;
Tejun Heo's avatar
Tejun Heo committed
80
	int				plid;
81
82
};

83
/*
84
85
86
87
88
 * Policies that need to keep per-blkcg data which is independent from any
 * request_queue associated to it should implement cpd_alloc/free_fn()
 * methods.  A policy can allocate private data area by allocating larger
 * data structure which embeds blkcg_policy_data at the beginning.
 * cpd_init() is invoked to let each policy handle per-blkcg data.
89
90
 */
struct blkcg_policy_data {
91
92
	/* the blkcg and policy id this per-policy data belongs to */
	struct blkcg			*blkcg;
93
94
95
	int				plid;
};

Tejun Heo's avatar
Tejun Heo committed
96
97
/* association between a blk cgroup and a request queue */
struct blkcg_gq {
98
	/* Pointer to the associated request_queue */
99
100
101
	struct request_queue		*q;
	struct list_head		q_node;
	struct hlist_node		blkcg_node;
Tejun Heo's avatar
Tejun Heo committed
102
	struct blkcg			*blkcg;
103

104
105
106
107
108
109
	/*
	 * Each blkg gets congested separately and the congestion state is
	 * propagated to the matching bdi_writeback_congested.
	 */
	struct bdi_writeback_congested	*wb_congested;

110
111
112
	/* all non-root blkcg_gq's are guaranteed to have access to parent */
	struct blkcg_gq			*parent;

113
114
	/* request allocation list for this blkcg-q pair */
	struct request_list		rl;
115

Tejun Heo's avatar
Tejun Heo committed
116
	/* reference count */
117
	atomic_t			refcnt;
118

119
120
121
	/* is this blkg online? protected by both blkcg and q locks */
	bool				online;

122
	struct blkg_policy_data		*pd[BLKCG_MAX_POLS];
Tejun Heo's avatar
Tejun Heo committed
123

124
	struct rcu_head			rcu_head;
125
126
};

127
typedef struct blkcg_policy_data *(blkcg_pol_alloc_cpd_fn)(gfp_t gfp);
128
typedef void (blkcg_pol_init_cpd_fn)(struct blkcg_policy_data *cpd);
129
typedef void (blkcg_pol_free_cpd_fn)(struct blkcg_policy_data *cpd);
130
typedef struct blkg_policy_data *(blkcg_pol_alloc_pd_fn)(gfp_t gfp, int node);
131
132
133
typedef void (blkcg_pol_init_pd_fn)(struct blkg_policy_data *pd);
typedef void (blkcg_pol_online_pd_fn)(struct blkg_policy_data *pd);
typedef void (blkcg_pol_offline_pd_fn)(struct blkg_policy_data *pd);
134
typedef void (blkcg_pol_free_pd_fn)(struct blkg_policy_data *pd);
135
typedef void (blkcg_pol_reset_pd_stats_fn)(struct blkg_policy_data *pd);
136

Tejun Heo's avatar
Tejun Heo committed
137
struct blkcg_policy {
138
139
140
	int				plid;
	/* cgroup files for the policy */
	struct cftype			*cftypes;
141
142

	/* operations */
143
	blkcg_pol_alloc_cpd_fn		*cpd_alloc_fn;
144
	blkcg_pol_init_cpd_fn		*cpd_init_fn;
145
146
	blkcg_pol_free_cpd_fn		*cpd_free_fn;

147
	blkcg_pol_alloc_pd_fn		*pd_alloc_fn;
148
	blkcg_pol_init_pd_fn		*pd_init_fn;
149
150
	blkcg_pol_online_pd_fn		*pd_online_fn;
	blkcg_pol_offline_pd_fn		*pd_offline_fn;
151
	blkcg_pol_free_pd_fn		*pd_free_fn;
152
	blkcg_pol_reset_pd_stats_fn	*pd_reset_stats_fn;
153
154
};

Tejun Heo's avatar
Tejun Heo committed
155
extern struct blkcg blkcg_root;
Tejun Heo's avatar
Tejun Heo committed
156
extern struct cgroup_subsys_state * const blkcg_root_css;
157

Tejun Heo's avatar
Tejun Heo committed
158
159
struct blkcg_gq *blkg_lookup_slowpath(struct blkcg *blkcg,
				      struct request_queue *q, bool update_hint);
Tejun Heo's avatar
Tejun Heo committed
160
161
struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
				    struct request_queue *q);
162
163
164
int blkcg_init_queue(struct request_queue *q);
void blkcg_drain_queue(struct request_queue *q);
void blkcg_exit_queue(struct request_queue *q);
165

166
/* Blkio controller policy registration */
167
int blkcg_policy_register(struct blkcg_policy *pol);
Tejun Heo's avatar
Tejun Heo committed
168
void blkcg_policy_unregister(struct blkcg_policy *pol);
169
int blkcg_activate_policy(struct request_queue *q,
Tejun Heo's avatar
Tejun Heo committed
170
			  const struct blkcg_policy *pol);
171
void blkcg_deactivate_policy(struct request_queue *q,
Tejun Heo's avatar
Tejun Heo committed
172
			     const struct blkcg_policy *pol);
173

Tejun Heo's avatar
Tejun Heo committed
174
void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg,
175
176
		       u64 (*prfill)(struct seq_file *,
				     struct blkg_policy_data *, int),
Tejun Heo's avatar
Tejun Heo committed
177
		       const struct blkcg_policy *pol, int data,
178
		       bool show_total);
179
180
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,
181
			 const struct blkg_rwstat *rwstat);
182
183
184
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);
185

186
187
188
189
u64 blkg_stat_recursive_sum(struct blkg_policy_data *pd, int off);
struct blkg_rwstat blkg_rwstat_recursive_sum(struct blkg_policy_data *pd,
					     int off);

190
struct blkg_conf_ctx {
191
	struct gendisk			*disk;
Tejun Heo's avatar
Tejun Heo committed
192
	struct blkcg_gq			*blkg;
193
	u64				v;
194
195
};

Tejun Heo's avatar
Tejun Heo committed
196
197
int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
		   const char *input, struct blkg_conf_ctx *ctx);
198
199
200
void blkg_conf_finish(struct blkg_conf_ctx *ctx);


201
202
203
204
205
static inline struct blkcg *css_to_blkcg(struct cgroup_subsys_state *css)
{
	return css ? container_of(css, struct blkcg, css) : NULL;
}

206
207
static inline struct blkcg *task_blkcg(struct task_struct *tsk)
{
208
	return css_to_blkcg(task_css(tsk, blkio_cgrp_id));
209
210
211
212
213
}

static inline struct blkcg *bio_blkcg(struct bio *bio)
{
	if (bio && bio->bi_css)
214
		return css_to_blkcg(bio->bi_css);
215
216
217
	return task_blkcg(current);
}

218
219
220
221
222
223
static inline struct cgroup_subsys_state *
task_get_blkcg_css(struct task_struct *task)
{
	return task_get_css(task, blkio_cgrp_id);
}

224
225
226
227
228
229
230
231
/**
 * blkcg_parent - get the parent of a blkcg
 * @blkcg: blkcg of interest
 *
 * Return the parent blkcg of @blkcg.  Can be called anytime.
 */
static inline struct blkcg *blkcg_parent(struct blkcg *blkcg)
{
Tejun Heo's avatar
Tejun Heo committed
232
	return css_to_blkcg(blkcg->css.parent);
233
234
}

Tejun Heo's avatar
Tejun Heo committed
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
/**
 * __blkg_lookup - internal version of blkg_lookup()
 * @blkcg: blkcg of interest
 * @q: request_queue of interest
 * @update_hint: whether to update lookup hint with the result or not
 *
 * This is internal version and shouldn't be used by policy
 * implementations.  Looks up blkgs for the @blkcg - @q pair regardless of
 * @q's bypass state.  If @update_hint is %true, the caller should be
 * holding @q->queue_lock and lookup hint is updated on success.
 */
static inline struct blkcg_gq *__blkg_lookup(struct blkcg *blkcg,
					     struct request_queue *q,
					     bool update_hint)
{
	struct blkcg_gq *blkg;

252
253
254
	if (blkcg == &blkcg_root)
		return q->root_blkg;

Tejun Heo's avatar
Tejun Heo committed
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
	blkg = rcu_dereference(blkcg->blkg_hint);
	if (blkg && blkg->q == q)
		return blkg;

	return blkg_lookup_slowpath(blkcg, q, update_hint);
}

/**
 * blkg_lookup - lookup blkg for the specified blkcg - q pair
 * @blkcg: blkcg of interest
 * @q: request_queue of interest
 *
 * Lookup blkg for the @blkcg - @q pair.  This function should be called
 * under RCU read lock and is guaranteed to return %NULL if @q is bypassing
 * - see blk_queue_bypass_start() for details.
 */
static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg,
					   struct request_queue *q)
{
	WARN_ON_ONCE(!rcu_read_lock_held());

	if (unlikely(blk_queue_bypass(q)))
		return NULL;
	return __blkg_lookup(blkcg, q, false);
}

281
282
283
284
285
286
287
/**
 * 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.
 */
288
289
static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
						  struct blkcg_policy *pol)
290
{
291
	return blkg ? blkg->pd[pol->plid] : NULL;
292
293
}

294
295
296
static inline struct blkcg_policy_data *blkcg_to_cpd(struct blkcg *blkcg,
						     struct blkcg_policy *pol)
{
297
	return blkcg ? blkcg->cpd[pol->plid] : NULL;
298
299
}

300
301
/**
 * pdata_to_blkg - get blkg associated with policy private data
302
 * @pd: policy private data of interest
303
 *
304
 * @pd is policy private data.  Determine the blkg it's associated with.
305
 */
306
static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd)
307
{
308
	return pd ? pd->blkg : NULL;
309
310
}

311
312
313
314
315
static inline struct blkcg *cpd_to_blkcg(struct blkcg_policy_data *cpd)
{
	return cpd ? cpd->blkcg : NULL;
}

Tejun Heo's avatar
Tejun Heo committed
316
317
318
319
320
321
322
323
/**
 * 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.
 */
Tejun Heo's avatar
Tejun Heo committed
324
static inline int blkg_path(struct blkcg_gq *blkg, char *buf, int buflen)
325
{
Tejun Heo's avatar
Tejun Heo committed
326
	char *p;
Tejun Heo's avatar
Tejun Heo committed
327

Tejun Heo's avatar
Tejun Heo committed
328
329
	p = cgroup_path(blkg->blkcg->css.cgroup, buf, buflen);
	if (!p) {
Tejun Heo's avatar
Tejun Heo committed
330
		strncpy(buf, "<unavailable>", buflen);
Tejun Heo's avatar
Tejun Heo committed
331
332
333
334
335
		return -ENAMETOOLONG;
	}

	memmove(buf, p, buf + buflen - p);
	return 0;
336
337
}

Tejun Heo's avatar
Tejun Heo committed
338
339
340
341
/**
 * blkg_get - get a blkg reference
 * @blkg: blkg to get
 *
342
 * The caller should be holding an existing reference.
Tejun Heo's avatar
Tejun Heo committed
343
 */
Tejun Heo's avatar
Tejun Heo committed
344
static inline void blkg_get(struct blkcg_gq *blkg)
Tejun Heo's avatar
Tejun Heo committed
345
{
346
347
	WARN_ON_ONCE(atomic_read(&blkg->refcnt) <= 0);
	atomic_inc(&blkg->refcnt);
Tejun Heo's avatar
Tejun Heo committed
348
349
}

350
void __blkg_release_rcu(struct rcu_head *rcu);
Tejun Heo's avatar
Tejun Heo committed
351
352
353
354
355

/**
 * blkg_put - put a blkg reference
 * @blkg: blkg to put
 */
Tejun Heo's avatar
Tejun Heo committed
356
static inline void blkg_put(struct blkcg_gq *blkg)
Tejun Heo's avatar
Tejun Heo committed
357
{
358
359
	WARN_ON_ONCE(atomic_read(&blkg->refcnt) <= 0);
	if (atomic_dec_and_test(&blkg->refcnt))
360
		call_rcu(&blkg->rcu_head, __blkg_release_rcu);
Tejun Heo's avatar
Tejun Heo committed
361
362
}

363
364
365
/**
 * blkg_for_each_descendant_pre - pre-order walk of a blkg's descendants
 * @d_blkg: loop cursor pointing to the current descendant
366
 * @pos_css: used for iteration
367
368
369
370
371
 * @p_blkg: target blkg to walk descendants of
 *
 * Walk @c_blkg through the descendants of @p_blkg.  Must be used with RCU
 * read locked.  If called under either blkcg or queue lock, the iteration
 * is guaranteed to include all and only online blkgs.  The caller may
372
 * update @pos_css by calling css_rightmost_descendant() to skip subtree.
373
 * @p_blkg is included in the iteration and the first node to be visited.
374
 */
375
376
377
#define blkg_for_each_descendant_pre(d_blkg, pos_css, p_blkg)		\
	css_for_each_descendant_pre((pos_css), &(p_blkg)->blkcg->css)	\
		if (((d_blkg) = __blkg_lookup(css_to_blkcg(pos_css),	\
378
379
					      (p_blkg)->q, false)))

380
381
382
/**
 * blkg_for_each_descendant_post - post-order walk of a blkg's descendants
 * @d_blkg: loop cursor pointing to the current descendant
383
 * @pos_css: used for iteration
384
385
386
 * @p_blkg: target blkg to walk descendants of
 *
 * Similar to blkg_for_each_descendant_pre() but performs post-order
387
388
 * traversal instead.  Synchronization rules are the same.  @p_blkg is
 * included in the iteration and the last node to be visited.
389
 */
390
391
392
#define blkg_for_each_descendant_post(d_blkg, pos_css, p_blkg)		\
	css_for_each_descendant_post((pos_css), &(p_blkg)->blkcg->css)	\
		if (((d_blkg) = __blkg_lookup(css_to_blkcg(pos_css),	\
393
394
					      (p_blkg)->q, false)))

395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
/**
 * blk_get_rl - get request_list to use
 * @q: request_queue of interest
 * @bio: bio which will be attached to the allocated request (may be %NULL)
 *
 * The caller wants to allocate a request from @q to use for @bio.  Find
 * the request_list to use and obtain a reference on it.  Should be called
 * under queue_lock.  This function is guaranteed to return non-%NULL
 * request_list.
 */
static inline struct request_list *blk_get_rl(struct request_queue *q,
					      struct bio *bio)
{
	struct blkcg *blkcg;
	struct blkcg_gq *blkg;

	rcu_read_lock();

	blkcg = bio_blkcg(bio);

	/* bypass blkg lookup and use @q->root_rl directly for root */
	if (blkcg == &blkcg_root)
		goto root_rl;

	/*
	 * Try to use blkg->rl.  blkg lookup may fail under memory pressure
	 * or if either the blkcg or queue is going away.  Fall back to
	 * root_rl in such cases.
	 */
424
425
	blkg = blkg_lookup(blkcg, q);
	if (unlikely(!blkg))
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
		goto root_rl;

	blkg_get(blkg);
	rcu_read_unlock();
	return &blkg->rl;
root_rl:
	rcu_read_unlock();
	return &q->root_rl;
}

/**
 * blk_put_rl - put request_list
 * @rl: request_list to put
 *
 * Put the reference acquired by blk_get_rl().  Should be called under
 * queue_lock.
 */
static inline void blk_put_rl(struct request_list *rl)
{
445
	if (rl->blkg->blkcg != &blkcg_root)
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
		blkg_put(rl->blkg);
}

/**
 * blk_rq_set_rl - associate a request with a request_list
 * @rq: request of interest
 * @rl: target request_list
 *
 * Associate @rq with @rl so that accounting and freeing can know the
 * request_list @rq came from.
 */
static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl)
{
	rq->rl = rl;
}

/**
 * blk_rq_rl - return the request_list a request came from
 * @rq: request of interest
 *
 * Return the request_list @rq is allocated from.
 */
static inline struct request_list *blk_rq_rl(struct request *rq)
{
	return rq->rl;
}

struct request_list *__blk_queue_next_rl(struct request_list *rl,
					 struct request_queue *q);
/**
 * blk_queue_for_each_rl - iterate through all request_lists of a request_queue
 *
 * Should be used under queue_lock.
 */
#define blk_queue_for_each_rl(rl, q)	\
	for ((rl) = &(q)->root_rl; (rl); (rl) = __blk_queue_next_rl((rl), (q)))

483
484
485
486
487
static inline void blkg_stat_init(struct blkg_stat *stat)
{
	u64_stats_init(&stat->syncp);
}

488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
/**
 * 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 {
516
		start = u64_stats_fetch_begin_irq(&stat->syncp);
517
		v = stat->cnt;
518
	} while (u64_stats_fetch_retry_irq(&stat->syncp, start));
519
520
521
522
523
524
525
526
527
528
529
530
531

	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;
}

532
533
534
535
536
537
538
539
540
541
542
543
/**
 * blkg_stat_merge - merge a blkg_stat into another
 * @to: the destination blkg_stat
 * @from: the source
 *
 * Add @from's count to @to.
 */
static inline void blkg_stat_merge(struct blkg_stat *to, struct blkg_stat *from)
{
	blkg_stat_add(to, blkg_stat_read(from));
}

544
545
546
547
548
static inline void blkg_rwstat_init(struct blkg_rwstat *rwstat)
{
	u64_stats_init(&rwstat->syncp);
}

549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
/**
 * 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.
 */
583
static inline struct blkg_rwstat blkg_rwstat_read(struct blkg_rwstat *rwstat)
584
585
586
587
588
{
	unsigned int start;
	struct blkg_rwstat tmp;

	do {
589
		start = u64_stats_fetch_begin_irq(&rwstat->syncp);
590
		tmp = *rwstat;
591
	} while (u64_stats_fetch_retry_irq(&rwstat->syncp, start));
592
593
594
595
596

	return tmp;
}

/**
597
 * blkg_rwstat_total - read the total count of a blkg_rwstat
598
599
600
601
602
603
 * @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.
 */
604
static inline uint64_t blkg_rwstat_total(struct blkg_rwstat *rwstat)
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
{
	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));
}

620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
/**
 * blkg_rwstat_merge - merge a blkg_rwstat into another
 * @to: the destination blkg_rwstat
 * @from: the source
 *
 * Add @from's counts to @to.
 */
static inline void blkg_rwstat_merge(struct blkg_rwstat *to,
				     struct blkg_rwstat *from)
{
	struct blkg_rwstat v = blkg_rwstat_read(from);
	int i;

	u64_stats_update_begin(&to->syncp);
	for (i = 0; i < BLKG_RWSTAT_NR; i++)
		to->cnt[i] += v.cnt[i];
	u64_stats_update_end(&to->syncp);
}

639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
#ifdef CONFIG_BLK_DEV_THROTTLING
extern bool blk_throtl_bio(struct request_queue *q, struct blkcg_gq *blkg,
			   struct bio *bio);
#else
static inline bool blk_throtl_bio(struct request_queue *q, struct blkcg_gq *blkg,
				  struct bio *bio) { return false; }
#endif

static inline bool blkcg_bio_issue_check(struct request_queue *q,
					 struct bio *bio)
{
	struct blkcg *blkcg;
	struct blkcg_gq *blkg;
	bool throtl = false;

	rcu_read_lock();
	blkcg = bio_blkcg(bio);

	blkg = blkg_lookup(blkcg, q);
	if (unlikely(!blkg)) {
		spin_lock_irq(q->queue_lock);
		blkg = blkg_lookup_create(blkcg, q);
		if (IS_ERR(blkg))
			blkg = NULL;
		spin_unlock_irq(q->queue_lock);
	}

	throtl = blk_throtl_bio(q, blkg, bio);

	rcu_read_unlock();
	return !throtl;
}

672
673
#else	/* CONFIG_BLK_CGROUP */

674
675
struct blkcg {
};
676

677
678
679
struct blkg_policy_data {
};

680
681
682
struct blkcg_policy_data {
};

Tejun Heo's avatar
Tejun Heo committed
683
struct blkcg_gq {
684
685
};

Tejun Heo's avatar
Tejun Heo committed
686
struct blkcg_policy {
687
688
};

Tejun Heo's avatar
Tejun Heo committed
689
690
#define blkcg_root_css	((struct cgroup_subsys_state *)ERR_PTR(-EINVAL))

691
692
693
694
695
696
static inline struct cgroup_subsys_state *
task_get_blkcg_css(struct task_struct *task)
{
	return NULL;
}

697
698
#ifdef CONFIG_BLOCK

Tejun Heo's avatar
Tejun Heo committed
699
static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, void *key) { return NULL; }
700
701
702
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) { }
703
static inline int blkcg_policy_register(struct blkcg_policy *pol) { return 0; }
Tejun Heo's avatar
Tejun Heo committed
704
static inline void blkcg_policy_unregister(struct blkcg_policy *pol) { }
705
static inline int blkcg_activate_policy(struct request_queue *q,
Tejun Heo's avatar
Tejun Heo committed
706
					const struct blkcg_policy *pol) { return 0; }
707
static inline void blkcg_deactivate_policy(struct request_queue *q,
Tejun Heo's avatar
Tejun Heo committed
708
709
					   const struct blkcg_policy *pol) { }

710
static inline struct blkcg *bio_blkcg(struct bio *bio) { return NULL; }
711

712
713
714
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; }
Tejun Heo's avatar
Tejun Heo committed
715
716
717
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) { }
718

719
720
721
722
723
724
static inline struct request_list *blk_get_rl(struct request_queue *q,
					      struct bio *bio) { return &q->root_rl; }
static inline void blk_put_rl(struct request_list *rl) { }
static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl) { }
static inline struct request_list *blk_rq_rl(struct request *rq) { return &rq->q->root_rl; }

725
726
727
static inline bool blkcg_bio_issue_check(struct request_queue *q,
					 struct bio *bio) { return true; }

728
729
730
#define blk_queue_for_each_rl(rl, q)	\
	for ((rl) = &(q)->root_rl; (rl); (rl) = NULL)

731
#endif	/* CONFIG_BLOCK */
732
733
#endif	/* CONFIG_BLK_CGROUP */
#endif	/* _BLK_CGROUP_H */