4 * Common Block IO controller cgroup interface
6 * Based on ideas and code from CFQ, CFS and BFQ:
7 * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
9 * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
10 * Paolo Valente <paolo.valente@unimore.it>
12 * Copyright (C) 2009 Vivek Goyal <vgoyal@redhat.com>
13 * Nauman Rafique <nauman@google.com>
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>
22 /* Max limits for throttle policy */
23 #define THROTL_IOPS_MAX UINT_MAX
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
30 #ifdef CONFIG_BLK_CGROUP
32 enum blkg_rwstat_type {
39 BLKG_RWSTAT_TOTAL = BLKG_RWSTAT_NR,
45 struct cgroup_subsys_state css;
48 struct radix_tree_root blkg_tree;
49 struct blkcg_gq *blkg_hint;
50 struct hlist_head blkg_list;
52 /* for policies to test whether associated blkcg has changed */
55 /* TODO: per-policy storage in blkcg */
56 unsigned int cfq_weight; /* belongs to cfq */
57 unsigned int cfq_leaf_weight;
61 struct u64_stats_sync syncp;
66 struct u64_stats_sync syncp;
67 uint64_t cnt[BLKG_RWSTAT_NR];
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.
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.
80 * Such private data must embed struct blkg_policy_data (pd) at the
81 * beginning and pd_size can't be smaller than pd.
83 struct blkg_policy_data {
84 /* the blkg and policy id this per-policy data belongs to */
85 struct blkcg_gq *blkg;
88 /* used during policy activation */
89 struct list_head alloc_node;
92 /* association between a blk cgroup and a request queue */
94 /* Pointer to the associated request_queue */
95 struct request_queue *q;
96 struct list_head q_node;
97 struct hlist_node blkcg_node;
100 /* all non-root blkcg_gq's are guaranteed to have access to parent */
101 struct blkcg_gq *parent;
103 /* request allocation list for this blkcg-q pair */
104 struct request_list rl;
106 /* reference count */
109 /* is this blkg online? protected by both blkcg and q locks */
112 struct blkg_policy_data *pd[BLKCG_MAX_POLS];
114 struct rcu_head rcu_head;
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);
123 struct blkcg_policy {
125 /* policy specific private data size */
127 /* cgroup files for the policy */
128 struct cftype *cftypes;
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;
138 extern struct blkcg blkcg_root;
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);
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);
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,
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,
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,
171 struct blkg_conf_ctx {
172 struct gendisk *disk;
173 struct blkcg_gq *blkg;
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);
182 static inline struct blkcg *css_to_blkcg(struct cgroup_subsys_state *css)
184 return css ? container_of(css, struct blkcg, css) : NULL;
187 static inline struct blkcg *task_blkcg(struct task_struct *tsk)
189 return css_to_blkcg(task_css(tsk, blkio_subsys_id));
192 static inline struct blkcg *bio_blkcg(struct bio *bio)
194 if (bio && bio->bi_css)
195 return css_to_blkcg(bio->bi_css);
196 return task_blkcg(current);
200 * blkcg_parent - get the parent of a blkcg
201 * @blkcg: blkcg of interest
203 * Return the parent blkcg of @blkcg. Can be called anytime.
205 static inline struct blkcg *blkcg_parent(struct blkcg *blkcg)
207 return css_to_blkcg(css_parent(&blkcg->css));
211 * blkg_to_pdata - get policy private data
212 * @blkg: blkg of interest
213 * @pol: policy of interest
215 * Return pointer to private data associated with the @blkg-@pol pair.
217 static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
218 struct blkcg_policy *pol)
220 return blkg ? blkg->pd[pol->plid] : NULL;
224 * pdata_to_blkg - get blkg associated with policy private data
225 * @pd: policy private data of interest
227 * @pd is policy private data. Determine the blkg it's associated with.
229 static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd)
231 return pd ? pd->blkg : NULL;
235 * blkg_path - format cgroup path of blkg
236 * @blkg: blkg of interest
237 * @buf: target buffer
238 * @buflen: target buffer length
240 * Format the path of the cgroup of @blkg into @buf.
242 static inline int blkg_path(struct blkcg_gq *blkg, char *buf, int buflen)
246 ret = cgroup_path(blkg->blkcg->css.cgroup, buf, buflen);
248 strncpy(buf, "<unavailable>", buflen);
253 * blkg_get - get a blkg reference
256 * The caller should be holding queue_lock and an existing reference.
258 static inline void blkg_get(struct blkcg_gq *blkg)
260 lockdep_assert_held(blkg->q->queue_lock);
261 WARN_ON_ONCE(!blkg->refcnt);
265 void __blkg_release_rcu(struct rcu_head *rcu);
268 * blkg_put - put a blkg reference
271 * The caller should be holding queue_lock.
273 static inline void blkg_put(struct blkcg_gq *blkg)
275 lockdep_assert_held(blkg->q->queue_lock);
276 WARN_ON_ONCE(blkg->refcnt <= 0);
278 call_rcu(&blkg->rcu_head, __blkg_release_rcu);
281 struct blkcg_gq *__blkg_lookup(struct blkcg *blkcg, struct request_queue *q,
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
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.
295 #define blkg_for_each_descendant_pre(d_blkg, pos_css, p_blkg) \
296 css_for_each_descendant_pre((pos_css), &(p_blkg)->blkcg->css) \
297 if (((d_blkg) = __blkg_lookup(css_to_blkcg(pos_css), \
298 (p_blkg)->q, false)))
301 * blkg_for_each_descendant_post - post-order walk of a blkg's descendants
302 * @d_blkg: loop cursor pointing to the current descendant
303 * @pos_css: used for iteration
304 * @p_blkg: target blkg to walk descendants of
306 * Similar to blkg_for_each_descendant_pre() but performs post-order
307 * traversal instead. Synchronization rules are the same.
309 #define blkg_for_each_descendant_post(d_blkg, pos_css, p_blkg) \
310 css_for_each_descendant_post((pos_css), &(p_blkg)->blkcg->css) \
311 if (((d_blkg) = __blkg_lookup(css_to_blkcg(pos_css), \
312 (p_blkg)->q, false)))
315 * blk_get_rl - get request_list to use
316 * @q: request_queue of interest
317 * @bio: bio which will be attached to the allocated request (may be %NULL)
319 * The caller wants to allocate a request from @q to use for @bio. Find
320 * the request_list to use and obtain a reference on it. Should be called
321 * under queue_lock. This function is guaranteed to return non-%NULL
324 static inline struct request_list *blk_get_rl(struct request_queue *q,
328 struct blkcg_gq *blkg;
332 blkcg = bio_blkcg(bio);
334 /* bypass blkg lookup and use @q->root_rl directly for root */
335 if (blkcg == &blkcg_root)
339 * Try to use blkg->rl. blkg lookup may fail under memory pressure
340 * or if either the blkcg or queue is going away. Fall back to
341 * root_rl in such cases.
343 blkg = blkg_lookup_create(blkcg, q);
344 if (unlikely(IS_ERR(blkg)))
356 * blk_put_rl - put request_list
357 * @rl: request_list to put
359 * Put the reference acquired by blk_get_rl(). Should be called under
362 static inline void blk_put_rl(struct request_list *rl)
364 /* root_rl may not have blkg set */
365 if (rl->blkg && rl->blkg->blkcg != &blkcg_root)
370 * blk_rq_set_rl - associate a request with a request_list
371 * @rq: request of interest
372 * @rl: target request_list
374 * Associate @rq with @rl so that accounting and freeing can know the
375 * request_list @rq came from.
377 static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl)
383 * blk_rq_rl - return the request_list a request came from
384 * @rq: request of interest
386 * Return the request_list @rq is allocated from.
388 static inline struct request_list *blk_rq_rl(struct request *rq)
393 struct request_list *__blk_queue_next_rl(struct request_list *rl,
394 struct request_queue *q);
396 * blk_queue_for_each_rl - iterate through all request_lists of a request_queue
398 * Should be used under queue_lock.
400 #define blk_queue_for_each_rl(rl, q) \
401 for ((rl) = &(q)->root_rl; (rl); (rl) = __blk_queue_next_rl((rl), (q)))
404 * blkg_stat_add - add a value to a blkg_stat
405 * @stat: target blkg_stat
408 * Add @val to @stat. The caller is responsible for synchronizing calls to
411 static inline void blkg_stat_add(struct blkg_stat *stat, uint64_t val)
413 u64_stats_update_begin(&stat->syncp);
415 u64_stats_update_end(&stat->syncp);
419 * blkg_stat_read - read the current value of a blkg_stat
420 * @stat: blkg_stat to read
422 * Read the current value of @stat. This function can be called without
423 * synchroniztion and takes care of u64 atomicity.
425 static inline uint64_t blkg_stat_read(struct blkg_stat *stat)
431 start = u64_stats_fetch_begin(&stat->syncp);
433 } while (u64_stats_fetch_retry(&stat->syncp, start));
439 * blkg_stat_reset - reset a blkg_stat
440 * @stat: blkg_stat to reset
442 static inline void blkg_stat_reset(struct blkg_stat *stat)
448 * blkg_stat_merge - merge a blkg_stat into another
449 * @to: the destination blkg_stat
452 * Add @from's count to @to.
454 static inline void blkg_stat_merge(struct blkg_stat *to, struct blkg_stat *from)
456 blkg_stat_add(to, blkg_stat_read(from));
460 * blkg_rwstat_add - add a value to a blkg_rwstat
461 * @rwstat: target blkg_rwstat
462 * @rw: mask of REQ_{WRITE|SYNC}
465 * Add @val to @rwstat. The counters are chosen according to @rw. The
466 * caller is responsible for synchronizing calls to this function.
468 static inline void blkg_rwstat_add(struct blkg_rwstat *rwstat,
469 int rw, uint64_t val)
471 u64_stats_update_begin(&rwstat->syncp);
474 rwstat->cnt[BLKG_RWSTAT_WRITE] += val;
476 rwstat->cnt[BLKG_RWSTAT_READ] += val;
478 rwstat->cnt[BLKG_RWSTAT_SYNC] += val;
480 rwstat->cnt[BLKG_RWSTAT_ASYNC] += val;
482 u64_stats_update_end(&rwstat->syncp);
486 * blkg_rwstat_read - read the current values of a blkg_rwstat
487 * @rwstat: blkg_rwstat to read
489 * Read the current snapshot of @rwstat and return it as the return value.
490 * This function can be called without synchronization and takes care of
493 static inline struct blkg_rwstat blkg_rwstat_read(struct blkg_rwstat *rwstat)
496 struct blkg_rwstat tmp;
499 start = u64_stats_fetch_begin(&rwstat->syncp);
501 } while (u64_stats_fetch_retry(&rwstat->syncp, start));
507 * blkg_rwstat_total - read the total count of a blkg_rwstat
508 * @rwstat: blkg_rwstat to read
510 * Return the total count of @rwstat regardless of the IO direction. This
511 * function can be called without synchronization and takes care of u64
514 static inline uint64_t blkg_rwstat_total(struct blkg_rwstat *rwstat)
516 struct blkg_rwstat tmp = blkg_rwstat_read(rwstat);
518 return tmp.cnt[BLKG_RWSTAT_READ] + tmp.cnt[BLKG_RWSTAT_WRITE];
522 * blkg_rwstat_reset - reset a blkg_rwstat
523 * @rwstat: blkg_rwstat to reset
525 static inline void blkg_rwstat_reset(struct blkg_rwstat *rwstat)
527 memset(rwstat->cnt, 0, sizeof(rwstat->cnt));
531 * blkg_rwstat_merge - merge a blkg_rwstat into another
532 * @to: the destination blkg_rwstat
535 * Add @from's counts to @to.
537 static inline void blkg_rwstat_merge(struct blkg_rwstat *to,
538 struct blkg_rwstat *from)
540 struct blkg_rwstat v = blkg_rwstat_read(from);
543 u64_stats_update_begin(&to->syncp);
544 for (i = 0; i < BLKG_RWSTAT_NR; i++)
545 to->cnt[i] += v.cnt[i];
546 u64_stats_update_end(&to->syncp);
549 #else /* CONFIG_BLK_CGROUP */
554 struct blkg_policy_data {
560 struct blkcg_policy {
563 static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, void *key) { return NULL; }
564 static inline int blkcg_init_queue(struct request_queue *q) { return 0; }
565 static inline void blkcg_drain_queue(struct request_queue *q) { }
566 static inline void blkcg_exit_queue(struct request_queue *q) { }
567 static inline int blkcg_policy_register(struct blkcg_policy *pol) { return 0; }
568 static inline void blkcg_policy_unregister(struct blkcg_policy *pol) { }
569 static inline int blkcg_activate_policy(struct request_queue *q,
570 const struct blkcg_policy *pol) { return 0; }
571 static inline void blkcg_deactivate_policy(struct request_queue *q,
572 const struct blkcg_policy *pol) { }
574 static inline struct blkcg *bio_blkcg(struct bio *bio) { return NULL; }
576 static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
577 struct blkcg_policy *pol) { return NULL; }
578 static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd) { return NULL; }
579 static inline char *blkg_path(struct blkcg_gq *blkg) { return NULL; }
580 static inline void blkg_get(struct blkcg_gq *blkg) { }
581 static inline void blkg_put(struct blkcg_gq *blkg) { }
583 static inline struct request_list *blk_get_rl(struct request_queue *q,
584 struct bio *bio) { return &q->root_rl; }
585 static inline void blk_put_rl(struct request_list *rl) { }
586 static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl) { }
587 static inline struct request_list *blk_rq_rl(struct request *rq) { return &rq->q->root_rl; }
589 #define blk_queue_for_each_rl(rl, q) \
590 for ((rl) = &(q)->root_rl; (rl); (rl) = NULL)
592 #endif /* CONFIG_BLK_CGROUP */
593 #endif /* _BLK_CGROUP_H */