xref: /linux/block/blk-cgroup.h (revision c4ee0af3fa0dc65f690fc908f02b8355f9576ea0)
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>
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 
22 /* Max limits for throttle policy */
23 #define THROTL_IOPS_MAX		UINT_MAX
24 
25 /* CFQ specific, out here for blkcg->cfq_weight */
26 #define CFQ_WEIGHT_MIN		10
27 #define CFQ_WEIGHT_MAX		1000
28 #define CFQ_WEIGHT_DEFAULT	500
29 
30 #ifdef CONFIG_BLK_CGROUP
31 
32 enum blkg_rwstat_type {
33 	BLKG_RWSTAT_READ,
34 	BLKG_RWSTAT_WRITE,
35 	BLKG_RWSTAT_SYNC,
36 	BLKG_RWSTAT_ASYNC,
37 
38 	BLKG_RWSTAT_NR,
39 	BLKG_RWSTAT_TOTAL = BLKG_RWSTAT_NR,
40 };
41 
42 struct blkcg_gq;
43 
44 struct blkcg {
45 	struct cgroup_subsys_state	css;
46 	spinlock_t			lock;
47 
48 	struct radix_tree_root		blkg_tree;
49 	struct blkcg_gq			*blkg_hint;
50 	struct hlist_head		blkg_list;
51 
52 	/* for policies to test whether associated blkcg has changed */
53 	uint64_t			id;
54 
55 	/* TODO: per-policy storage in blkcg */
56 	unsigned int			cfq_weight;	/* belongs to cfq */
57 	unsigned int			cfq_leaf_weight;
58 };
59 
60 struct blkg_stat {
61 	struct u64_stats_sync		syncp;
62 	uint64_t			cnt;
63 };
64 
65 struct blkg_rwstat {
66 	struct u64_stats_sync		syncp;
67 	uint64_t			cnt[BLKG_RWSTAT_NR];
68 };
69 
70 /*
71  * A blkcg_gq (blkg) is association between a block cgroup (blkcg) and a
72  * request_queue (q).  This is used by blkcg policies which need to track
73  * information per blkcg - q pair.
74  *
75  * There can be multiple active blkcg policies and each has its private
76  * data on each blkg, the size of which is determined by
77  * blkcg_policy->pd_size.  blkcg core allocates and frees such areas
78  * together with blkg and invokes pd_init/exit_fn() methods.
79  *
80  * Such private data must embed struct blkg_policy_data (pd) at the
81  * beginning and pd_size can't be smaller than pd.
82  */
83 struct blkg_policy_data {
84 	/* the blkg and policy id this per-policy data belongs to */
85 	struct blkcg_gq			*blkg;
86 	int				plid;
87 
88 	/* used during policy activation */
89 	struct list_head		alloc_node;
90 };
91 
92 /* association between a blk cgroup and a request queue */
93 struct blkcg_gq {
94 	/* Pointer to the associated request_queue */
95 	struct request_queue		*q;
96 	struct list_head		q_node;
97 	struct hlist_node		blkcg_node;
98 	struct blkcg			*blkcg;
99 
100 	/* all non-root blkcg_gq's are guaranteed to have access to parent */
101 	struct blkcg_gq			*parent;
102 
103 	/* request allocation list for this blkcg-q pair */
104 	struct request_list		rl;
105 
106 	/* reference count */
107 	int				refcnt;
108 
109 	/* is this blkg online? protected by both blkcg and q locks */
110 	bool				online;
111 
112 	struct blkg_policy_data		*pd[BLKCG_MAX_POLS];
113 
114 	struct rcu_head			rcu_head;
115 };
116 
117 typedef void (blkcg_pol_init_pd_fn)(struct blkcg_gq *blkg);
118 typedef void (blkcg_pol_online_pd_fn)(struct blkcg_gq *blkg);
119 typedef void (blkcg_pol_offline_pd_fn)(struct blkcg_gq *blkg);
120 typedef void (blkcg_pol_exit_pd_fn)(struct blkcg_gq *blkg);
121 typedef void (blkcg_pol_reset_pd_stats_fn)(struct blkcg_gq *blkg);
122 
123 struct blkcg_policy {
124 	int				plid;
125 	/* policy specific private data size */
126 	size_t				pd_size;
127 	/* cgroup files for the policy */
128 	struct cftype			*cftypes;
129 
130 	/* operations */
131 	blkcg_pol_init_pd_fn		*pd_init_fn;
132 	blkcg_pol_online_pd_fn		*pd_online_fn;
133 	blkcg_pol_offline_pd_fn		*pd_offline_fn;
134 	blkcg_pol_exit_pd_fn		*pd_exit_fn;
135 	blkcg_pol_reset_pd_stats_fn	*pd_reset_stats_fn;
136 };
137 
138 extern struct blkcg blkcg_root;
139 
140 struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, struct request_queue *q);
141 struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
142 				    struct request_queue *q);
143 int blkcg_init_queue(struct request_queue *q);
144 void blkcg_drain_queue(struct request_queue *q);
145 void blkcg_exit_queue(struct request_queue *q);
146 
147 /* Blkio controller policy registration */
148 int blkcg_policy_register(struct blkcg_policy *pol);
149 void blkcg_policy_unregister(struct blkcg_policy *pol);
150 int blkcg_activate_policy(struct request_queue *q,
151 			  const struct blkcg_policy *pol);
152 void blkcg_deactivate_policy(struct request_queue *q,
153 			     const struct blkcg_policy *pol);
154 
155 void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg,
156 		       u64 (*prfill)(struct seq_file *,
157 				     struct blkg_policy_data *, int),
158 		       const struct blkcg_policy *pol, int data,
159 		       bool show_total);
160 u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v);
161 u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
162 			 const struct blkg_rwstat *rwstat);
163 u64 blkg_prfill_stat(struct seq_file *sf, struct blkg_policy_data *pd, int off);
164 u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
165 		       int off);
166 
167 u64 blkg_stat_recursive_sum(struct blkg_policy_data *pd, int off);
168 struct blkg_rwstat blkg_rwstat_recursive_sum(struct blkg_policy_data *pd,
169 					     int off);
170 
171 struct blkg_conf_ctx {
172 	struct gendisk			*disk;
173 	struct blkcg_gq			*blkg;
174 	u64				v;
175 };
176 
177 int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
178 		   const char *input, struct blkg_conf_ctx *ctx);
179 void blkg_conf_finish(struct blkg_conf_ctx *ctx);
180 
181 
182 static inline struct blkcg *css_to_blkcg(struct cgroup_subsys_state *css)
183 {
184 	return css ? container_of(css, struct blkcg, css) : NULL;
185 }
186 
187 static inline struct blkcg *task_blkcg(struct task_struct *tsk)
188 {
189 	return css_to_blkcg(task_css(tsk, blkio_subsys_id));
190 }
191 
192 static inline struct blkcg *bio_blkcg(struct bio *bio)
193 {
194 	if (bio && bio->bi_css)
195 		return css_to_blkcg(bio->bi_css);
196 	return task_blkcg(current);
197 }
198 
199 /**
200  * blkcg_parent - get the parent of a blkcg
201  * @blkcg: blkcg of interest
202  *
203  * Return the parent blkcg of @blkcg.  Can be called anytime.
204  */
205 static inline struct blkcg *blkcg_parent(struct blkcg *blkcg)
206 {
207 	return css_to_blkcg(css_parent(&blkcg->css));
208 }
209 
210 /**
211  * blkg_to_pdata - get policy private data
212  * @blkg: blkg of interest
213  * @pol: policy of interest
214  *
215  * Return pointer to private data associated with the @blkg-@pol pair.
216  */
217 static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
218 						  struct blkcg_policy *pol)
219 {
220 	return blkg ? blkg->pd[pol->plid] : NULL;
221 }
222 
223 /**
224  * pdata_to_blkg - get blkg associated with policy private data
225  * @pd: policy private data of interest
226  *
227  * @pd is policy private data.  Determine the blkg it's associated with.
228  */
229 static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd)
230 {
231 	return pd ? pd->blkg : NULL;
232 }
233 
234 /**
235  * blkg_path - format cgroup path of blkg
236  * @blkg: blkg of interest
237  * @buf: target buffer
238  * @buflen: target buffer length
239  *
240  * Format the path of the cgroup of @blkg into @buf.
241  */
242 static inline int blkg_path(struct blkcg_gq *blkg, char *buf, int buflen)
243 {
244 	int ret;
245 
246 	ret = cgroup_path(blkg->blkcg->css.cgroup, buf, buflen);
247 	if (ret)
248 		strncpy(buf, "<unavailable>", buflen);
249 	return ret;
250 }
251 
252 /**
253  * blkg_get - get a blkg reference
254  * @blkg: blkg to get
255  *
256  * The caller should be holding queue_lock and an existing reference.
257  */
258 static inline void blkg_get(struct blkcg_gq *blkg)
259 {
260 	lockdep_assert_held(blkg->q->queue_lock);
261 	WARN_ON_ONCE(!blkg->refcnt);
262 	blkg->refcnt++;
263 }
264 
265 void __blkg_release_rcu(struct rcu_head *rcu);
266 
267 /**
268  * blkg_put - put a blkg reference
269  * @blkg: blkg to put
270  *
271  * The caller should be holding queue_lock.
272  */
273 static inline void blkg_put(struct blkcg_gq *blkg)
274 {
275 	lockdep_assert_held(blkg->q->queue_lock);
276 	WARN_ON_ONCE(blkg->refcnt <= 0);
277 	if (!--blkg->refcnt)
278 		call_rcu(&blkg->rcu_head, __blkg_release_rcu);
279 }
280 
281 struct blkcg_gq *__blkg_lookup(struct blkcg *blkcg, struct request_queue *q,
282 			       bool update_hint);
283 
284 /**
285  * blkg_for_each_descendant_pre - pre-order walk of a blkg's descendants
286  * @d_blkg: loop cursor pointing to the current descendant
287  * @pos_css: used for iteration
288  * @p_blkg: target blkg to walk descendants of
289  *
290  * Walk @c_blkg through the descendants of @p_blkg.  Must be used with RCU
291  * read locked.  If called under either blkcg or queue lock, the iteration
292  * is guaranteed to include all and only online blkgs.  The caller may
293  * update @pos_css by calling css_rightmost_descendant() to skip subtree.
294  * @p_blkg is included in the iteration and the first node to be visited.
295  */
296 #define blkg_for_each_descendant_pre(d_blkg, pos_css, p_blkg)		\
297 	css_for_each_descendant_pre((pos_css), &(p_blkg)->blkcg->css)	\
298 		if (((d_blkg) = __blkg_lookup(css_to_blkcg(pos_css),	\
299 					      (p_blkg)->q, false)))
300 
301 /**
302  * blkg_for_each_descendant_post - post-order walk of a blkg's descendants
303  * @d_blkg: loop cursor pointing to the current descendant
304  * @pos_css: used for iteration
305  * @p_blkg: target blkg to walk descendants of
306  *
307  * Similar to blkg_for_each_descendant_pre() but performs post-order
308  * traversal instead.  Synchronization rules are the same.  @p_blkg is
309  * included in the iteration and the last node to be visited.
310  */
311 #define blkg_for_each_descendant_post(d_blkg, pos_css, p_blkg)		\
312 	css_for_each_descendant_post((pos_css), &(p_blkg)->blkcg->css)	\
313 		if (((d_blkg) = __blkg_lookup(css_to_blkcg(pos_css),	\
314 					      (p_blkg)->q, false)))
315 
316 /**
317  * blk_get_rl - get request_list to use
318  * @q: request_queue of interest
319  * @bio: bio which will be attached to the allocated request (may be %NULL)
320  *
321  * The caller wants to allocate a request from @q to use for @bio.  Find
322  * the request_list to use and obtain a reference on it.  Should be called
323  * under queue_lock.  This function is guaranteed to return non-%NULL
324  * request_list.
325  */
326 static inline struct request_list *blk_get_rl(struct request_queue *q,
327 					      struct bio *bio)
328 {
329 	struct blkcg *blkcg;
330 	struct blkcg_gq *blkg;
331 
332 	rcu_read_lock();
333 
334 	blkcg = bio_blkcg(bio);
335 
336 	/* bypass blkg lookup and use @q->root_rl directly for root */
337 	if (blkcg == &blkcg_root)
338 		goto root_rl;
339 
340 	/*
341 	 * Try to use blkg->rl.  blkg lookup may fail under memory pressure
342 	 * or if either the blkcg or queue is going away.  Fall back to
343 	 * root_rl in such cases.
344 	 */
345 	blkg = blkg_lookup_create(blkcg, q);
346 	if (unlikely(IS_ERR(blkg)))
347 		goto root_rl;
348 
349 	blkg_get(blkg);
350 	rcu_read_unlock();
351 	return &blkg->rl;
352 root_rl:
353 	rcu_read_unlock();
354 	return &q->root_rl;
355 }
356 
357 /**
358  * blk_put_rl - put request_list
359  * @rl: request_list to put
360  *
361  * Put the reference acquired by blk_get_rl().  Should be called under
362  * queue_lock.
363  */
364 static inline void blk_put_rl(struct request_list *rl)
365 {
366 	/* root_rl may not have blkg set */
367 	if (rl->blkg && rl->blkg->blkcg != &blkcg_root)
368 		blkg_put(rl->blkg);
369 }
370 
371 /**
372  * blk_rq_set_rl - associate a request with a request_list
373  * @rq: request of interest
374  * @rl: target request_list
375  *
376  * Associate @rq with @rl so that accounting and freeing can know the
377  * request_list @rq came from.
378  */
379 static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl)
380 {
381 	rq->rl = rl;
382 }
383 
384 /**
385  * blk_rq_rl - return the request_list a request came from
386  * @rq: request of interest
387  *
388  * Return the request_list @rq is allocated from.
389  */
390 static inline struct request_list *blk_rq_rl(struct request *rq)
391 {
392 	return rq->rl;
393 }
394 
395 struct request_list *__blk_queue_next_rl(struct request_list *rl,
396 					 struct request_queue *q);
397 /**
398  * blk_queue_for_each_rl - iterate through all request_lists of a request_queue
399  *
400  * Should be used under queue_lock.
401  */
402 #define blk_queue_for_each_rl(rl, q)	\
403 	for ((rl) = &(q)->root_rl; (rl); (rl) = __blk_queue_next_rl((rl), (q)))
404 
405 static inline void blkg_stat_init(struct blkg_stat *stat)
406 {
407 	u64_stats_init(&stat->syncp);
408 }
409 
410 /**
411  * blkg_stat_add - add a value to a blkg_stat
412  * @stat: target blkg_stat
413  * @val: value to add
414  *
415  * Add @val to @stat.  The caller is responsible for synchronizing calls to
416  * this function.
417  */
418 static inline void blkg_stat_add(struct blkg_stat *stat, uint64_t val)
419 {
420 	u64_stats_update_begin(&stat->syncp);
421 	stat->cnt += val;
422 	u64_stats_update_end(&stat->syncp);
423 }
424 
425 /**
426  * blkg_stat_read - read the current value of a blkg_stat
427  * @stat: blkg_stat to read
428  *
429  * Read the current value of @stat.  This function can be called without
430  * synchroniztion and takes care of u64 atomicity.
431  */
432 static inline uint64_t blkg_stat_read(struct blkg_stat *stat)
433 {
434 	unsigned int start;
435 	uint64_t v;
436 
437 	do {
438 		start = u64_stats_fetch_begin_bh(&stat->syncp);
439 		v = stat->cnt;
440 	} while (u64_stats_fetch_retry_bh(&stat->syncp, start));
441 
442 	return v;
443 }
444 
445 /**
446  * blkg_stat_reset - reset a blkg_stat
447  * @stat: blkg_stat to reset
448  */
449 static inline void blkg_stat_reset(struct blkg_stat *stat)
450 {
451 	stat->cnt = 0;
452 }
453 
454 /**
455  * blkg_stat_merge - merge a blkg_stat into another
456  * @to: the destination blkg_stat
457  * @from: the source
458  *
459  * Add @from's count to @to.
460  */
461 static inline void blkg_stat_merge(struct blkg_stat *to, struct blkg_stat *from)
462 {
463 	blkg_stat_add(to, blkg_stat_read(from));
464 }
465 
466 static inline void blkg_rwstat_init(struct blkg_rwstat *rwstat)
467 {
468 	u64_stats_init(&rwstat->syncp);
469 }
470 
471 /**
472  * blkg_rwstat_add - add a value to a blkg_rwstat
473  * @rwstat: target blkg_rwstat
474  * @rw: mask of REQ_{WRITE|SYNC}
475  * @val: value to add
476  *
477  * Add @val to @rwstat.  The counters are chosen according to @rw.  The
478  * caller is responsible for synchronizing calls to this function.
479  */
480 static inline void blkg_rwstat_add(struct blkg_rwstat *rwstat,
481 				   int rw, uint64_t val)
482 {
483 	u64_stats_update_begin(&rwstat->syncp);
484 
485 	if (rw & REQ_WRITE)
486 		rwstat->cnt[BLKG_RWSTAT_WRITE] += val;
487 	else
488 		rwstat->cnt[BLKG_RWSTAT_READ] += val;
489 	if (rw & REQ_SYNC)
490 		rwstat->cnt[BLKG_RWSTAT_SYNC] += val;
491 	else
492 		rwstat->cnt[BLKG_RWSTAT_ASYNC] += val;
493 
494 	u64_stats_update_end(&rwstat->syncp);
495 }
496 
497 /**
498  * blkg_rwstat_read - read the current values of a blkg_rwstat
499  * @rwstat: blkg_rwstat to read
500  *
501  * Read the current snapshot of @rwstat and return it as the return value.
502  * This function can be called without synchronization and takes care of
503  * u64 atomicity.
504  */
505 static inline struct blkg_rwstat blkg_rwstat_read(struct blkg_rwstat *rwstat)
506 {
507 	unsigned int start;
508 	struct blkg_rwstat tmp;
509 
510 	do {
511 		start = u64_stats_fetch_begin_bh(&rwstat->syncp);
512 		tmp = *rwstat;
513 	} while (u64_stats_fetch_retry_bh(&rwstat->syncp, start));
514 
515 	return tmp;
516 }
517 
518 /**
519  * blkg_rwstat_total - read the total count of a blkg_rwstat
520  * @rwstat: blkg_rwstat to read
521  *
522  * Return the total count of @rwstat regardless of the IO direction.  This
523  * function can be called without synchronization and takes care of u64
524  * atomicity.
525  */
526 static inline uint64_t blkg_rwstat_total(struct blkg_rwstat *rwstat)
527 {
528 	struct blkg_rwstat tmp = blkg_rwstat_read(rwstat);
529 
530 	return tmp.cnt[BLKG_RWSTAT_READ] + tmp.cnt[BLKG_RWSTAT_WRITE];
531 }
532 
533 /**
534  * blkg_rwstat_reset - reset a blkg_rwstat
535  * @rwstat: blkg_rwstat to reset
536  */
537 static inline void blkg_rwstat_reset(struct blkg_rwstat *rwstat)
538 {
539 	memset(rwstat->cnt, 0, sizeof(rwstat->cnt));
540 }
541 
542 /**
543  * blkg_rwstat_merge - merge a blkg_rwstat into another
544  * @to: the destination blkg_rwstat
545  * @from: the source
546  *
547  * Add @from's counts to @to.
548  */
549 static inline void blkg_rwstat_merge(struct blkg_rwstat *to,
550 				     struct blkg_rwstat *from)
551 {
552 	struct blkg_rwstat v = blkg_rwstat_read(from);
553 	int i;
554 
555 	u64_stats_update_begin(&to->syncp);
556 	for (i = 0; i < BLKG_RWSTAT_NR; i++)
557 		to->cnt[i] += v.cnt[i];
558 	u64_stats_update_end(&to->syncp);
559 }
560 
561 #else	/* CONFIG_BLK_CGROUP */
562 
563 struct cgroup;
564 struct blkcg;
565 
566 struct blkg_policy_data {
567 };
568 
569 struct blkcg_gq {
570 };
571 
572 struct blkcg_policy {
573 };
574 
575 static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, void *key) { return NULL; }
576 static inline int blkcg_init_queue(struct request_queue *q) { return 0; }
577 static inline void blkcg_drain_queue(struct request_queue *q) { }
578 static inline void blkcg_exit_queue(struct request_queue *q) { }
579 static inline int blkcg_policy_register(struct blkcg_policy *pol) { return 0; }
580 static inline void blkcg_policy_unregister(struct blkcg_policy *pol) { }
581 static inline int blkcg_activate_policy(struct request_queue *q,
582 					const struct blkcg_policy *pol) { return 0; }
583 static inline void blkcg_deactivate_policy(struct request_queue *q,
584 					   const struct blkcg_policy *pol) { }
585 
586 static inline struct blkcg *bio_blkcg(struct bio *bio) { return NULL; }
587 
588 static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
589 						  struct blkcg_policy *pol) { return NULL; }
590 static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd) { return NULL; }
591 static inline char *blkg_path(struct blkcg_gq *blkg) { return NULL; }
592 static inline void blkg_get(struct blkcg_gq *blkg) { }
593 static inline void blkg_put(struct blkcg_gq *blkg) { }
594 
595 static inline struct request_list *blk_get_rl(struct request_queue *q,
596 					      struct bio *bio) { return &q->root_rl; }
597 static inline void blk_put_rl(struct request_list *rl) { }
598 static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl) { }
599 static inline struct request_list *blk_rq_rl(struct request *rq) { return &rq->q->root_rl; }
600 
601 #define blk_queue_for_each_rl(rl, q)	\
602 	for ((rl) = &(q)->root_rl; (rl); (rl) = NULL)
603 
604 #endif	/* CONFIG_BLK_CGROUP */
605 #endif	/* _BLK_CGROUP_H */
606