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 struct blkg_conf_ctx {
168 struct gendisk *disk;
169 struct blkcg_gq *blkg;
173 int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
174 const char *input, struct blkg_conf_ctx *ctx);
175 void blkg_conf_finish(struct blkg_conf_ctx *ctx);
178 static inline struct blkcg *cgroup_to_blkcg(struct cgroup *cgroup)
180 return container_of(cgroup_subsys_state(cgroup, blkio_subsys_id),
184 static inline struct blkcg *task_blkcg(struct task_struct *tsk)
186 return container_of(task_subsys_state(tsk, blkio_subsys_id),
190 static inline struct blkcg *bio_blkcg(struct bio *bio)
192 if (bio && bio->bi_css)
193 return container_of(bio->bi_css, struct blkcg, css);
194 return task_blkcg(current);
198 * blkcg_parent - get the parent of a blkcg
199 * @blkcg: blkcg of interest
201 * Return the parent blkcg of @blkcg. Can be called anytime.
203 static inline struct blkcg *blkcg_parent(struct blkcg *blkcg)
205 struct cgroup *pcg = blkcg->css.cgroup->parent;
207 return pcg ? cgroup_to_blkcg(pcg) : NULL;
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)
247 ret = cgroup_path(blkg->blkcg->css.cgroup, buf, buflen);
250 strncpy(buf, "<unavailable>", buflen);
255 * blkg_get - get a blkg reference
258 * The caller should be holding queue_lock and an existing reference.
260 static inline void blkg_get(struct blkcg_gq *blkg)
262 lockdep_assert_held(blkg->q->queue_lock);
263 WARN_ON_ONCE(!blkg->refcnt);
267 void __blkg_release(struct blkcg_gq *blkg);
270 * blkg_put - put a blkg reference
273 * The caller should be holding queue_lock.
275 static inline void blkg_put(struct blkcg_gq *blkg)
277 lockdep_assert_held(blkg->q->queue_lock);
278 WARN_ON_ONCE(blkg->refcnt <= 0);
280 __blkg_release(blkg);
284 * blk_get_rl - get request_list to use
285 * @q: request_queue of interest
286 * @bio: bio which will be attached to the allocated request (may be %NULL)
288 * The caller wants to allocate a request from @q to use for @bio. Find
289 * the request_list to use and obtain a reference on it. Should be called
290 * under queue_lock. This function is guaranteed to return non-%NULL
293 static inline struct request_list *blk_get_rl(struct request_queue *q,
297 struct blkcg_gq *blkg;
301 blkcg = bio_blkcg(bio);
303 /* bypass blkg lookup and use @q->root_rl directly for root */
304 if (blkcg == &blkcg_root)
308 * Try to use blkg->rl. blkg lookup may fail under memory pressure
309 * or if either the blkcg or queue is going away. Fall back to
310 * root_rl in such cases.
312 blkg = blkg_lookup_create(blkcg, q);
313 if (unlikely(IS_ERR(blkg)))
325 * blk_put_rl - put request_list
326 * @rl: request_list to put
328 * Put the reference acquired by blk_get_rl(). Should be called under
331 static inline void blk_put_rl(struct request_list *rl)
333 /* root_rl may not have blkg set */
334 if (rl->blkg && rl->blkg->blkcg != &blkcg_root)
339 * blk_rq_set_rl - associate a request with a request_list
340 * @rq: request of interest
341 * @rl: target request_list
343 * Associate @rq with @rl so that accounting and freeing can know the
344 * request_list @rq came from.
346 static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl)
352 * blk_rq_rl - return the request_list a request came from
353 * @rq: request of interest
355 * Return the request_list @rq is allocated from.
357 static inline struct request_list *blk_rq_rl(struct request *rq)
362 struct request_list *__blk_queue_next_rl(struct request_list *rl,
363 struct request_queue *q);
365 * blk_queue_for_each_rl - iterate through all request_lists of a request_queue
367 * Should be used under queue_lock.
369 #define blk_queue_for_each_rl(rl, q) \
370 for ((rl) = &(q)->root_rl; (rl); (rl) = __blk_queue_next_rl((rl), (q)))
373 * blkg_stat_add - add a value to a blkg_stat
374 * @stat: target blkg_stat
377 * Add @val to @stat. The caller is responsible for synchronizing calls to
380 static inline void blkg_stat_add(struct blkg_stat *stat, uint64_t val)
382 u64_stats_update_begin(&stat->syncp);
384 u64_stats_update_end(&stat->syncp);
388 * blkg_stat_read - read the current value of a blkg_stat
389 * @stat: blkg_stat to read
391 * Read the current value of @stat. This function can be called without
392 * synchroniztion and takes care of u64 atomicity.
394 static inline uint64_t blkg_stat_read(struct blkg_stat *stat)
400 start = u64_stats_fetch_begin(&stat->syncp);
402 } while (u64_stats_fetch_retry(&stat->syncp, start));
408 * blkg_stat_reset - reset a blkg_stat
409 * @stat: blkg_stat to reset
411 static inline void blkg_stat_reset(struct blkg_stat *stat)
417 * blkg_rwstat_add - add a value to a blkg_rwstat
418 * @rwstat: target blkg_rwstat
419 * @rw: mask of REQ_{WRITE|SYNC}
422 * Add @val to @rwstat. The counters are chosen according to @rw. The
423 * caller is responsible for synchronizing calls to this function.
425 static inline void blkg_rwstat_add(struct blkg_rwstat *rwstat,
426 int rw, uint64_t val)
428 u64_stats_update_begin(&rwstat->syncp);
431 rwstat->cnt[BLKG_RWSTAT_WRITE] += val;
433 rwstat->cnt[BLKG_RWSTAT_READ] += val;
435 rwstat->cnt[BLKG_RWSTAT_SYNC] += val;
437 rwstat->cnt[BLKG_RWSTAT_ASYNC] += val;
439 u64_stats_update_end(&rwstat->syncp);
443 * blkg_rwstat_read - read the current values of a blkg_rwstat
444 * @rwstat: blkg_rwstat to read
446 * Read the current snapshot of @rwstat and return it as the return value.
447 * This function can be called without synchronization and takes care of
450 static inline struct blkg_rwstat blkg_rwstat_read(struct blkg_rwstat *rwstat)
453 struct blkg_rwstat tmp;
456 start = u64_stats_fetch_begin(&rwstat->syncp);
458 } while (u64_stats_fetch_retry(&rwstat->syncp, start));
464 * blkg_rwstat_sum - read the total count of a blkg_rwstat
465 * @rwstat: blkg_rwstat to read
467 * Return the total count of @rwstat regardless of the IO direction. This
468 * function can be called without synchronization and takes care of u64
471 static inline uint64_t blkg_rwstat_sum(struct blkg_rwstat *rwstat)
473 struct blkg_rwstat tmp = blkg_rwstat_read(rwstat);
475 return tmp.cnt[BLKG_RWSTAT_READ] + tmp.cnt[BLKG_RWSTAT_WRITE];
479 * blkg_rwstat_reset - reset a blkg_rwstat
480 * @rwstat: blkg_rwstat to reset
482 static inline void blkg_rwstat_reset(struct blkg_rwstat *rwstat)
484 memset(rwstat->cnt, 0, sizeof(rwstat->cnt));
487 #else /* CONFIG_BLK_CGROUP */
492 struct blkg_policy_data {
498 struct blkcg_policy {
501 static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, void *key) { return NULL; }
502 static inline int blkcg_init_queue(struct request_queue *q) { return 0; }
503 static inline void blkcg_drain_queue(struct request_queue *q) { }
504 static inline void blkcg_exit_queue(struct request_queue *q) { }
505 static inline int blkcg_policy_register(struct blkcg_policy *pol) { return 0; }
506 static inline void blkcg_policy_unregister(struct blkcg_policy *pol) { }
507 static inline int blkcg_activate_policy(struct request_queue *q,
508 const struct blkcg_policy *pol) { return 0; }
509 static inline void blkcg_deactivate_policy(struct request_queue *q,
510 const struct blkcg_policy *pol) { }
512 static inline struct blkcg *cgroup_to_blkcg(struct cgroup *cgroup) { return NULL; }
513 static inline struct blkcg *bio_blkcg(struct bio *bio) { return NULL; }
515 static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
516 struct blkcg_policy *pol) { return NULL; }
517 static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd) { return NULL; }
518 static inline char *blkg_path(struct blkcg_gq *blkg) { return NULL; }
519 static inline void blkg_get(struct blkcg_gq *blkg) { }
520 static inline void blkg_put(struct blkcg_gq *blkg) { }
522 static inline struct request_list *blk_get_rl(struct request_queue *q,
523 struct bio *bio) { return &q->root_rl; }
524 static inline void blk_put_rl(struct request_list *rl) { }
525 static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl) { }
526 static inline struct request_list *blk_rq_rl(struct request *rq) { return &rq->q->root_rl; }
528 #define blk_queue_for_each_rl(rl, q) \
529 for ((rl) = &(q)->root_rl; (rl); (rl) = NULL)
531 #endif /* CONFIG_BLK_CGROUP */
532 #endif /* _BLK_CGROUP_H */