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 this per-policy data belongs to */
85 struct blkcg_gq *blkg;
87 /* used during policy activation */
88 struct list_head alloc_node;
91 /* association between a blk cgroup and a request queue */
93 /* Pointer to the associated request_queue */
94 struct request_queue *q;
95 struct list_head q_node;
96 struct hlist_node blkcg_node;
99 /* all non-root blkcg_gq's are guaranteed to have access to parent */
100 struct blkcg_gq *parent;
102 /* request allocation list for this blkcg-q pair */
103 struct request_list rl;
105 /* reference count */
108 struct blkg_policy_data *pd[BLKCG_MAX_POLS];
110 struct rcu_head rcu_head;
113 typedef void (blkcg_pol_init_pd_fn)(struct blkcg_gq *blkg);
114 typedef void (blkcg_pol_exit_pd_fn)(struct blkcg_gq *blkg);
115 typedef void (blkcg_pol_reset_pd_stats_fn)(struct blkcg_gq *blkg);
117 struct blkcg_policy {
119 /* policy specific private data size */
121 /* cgroup files for the policy */
122 struct cftype *cftypes;
125 blkcg_pol_init_pd_fn *pd_init_fn;
126 blkcg_pol_exit_pd_fn *pd_exit_fn;
127 blkcg_pol_reset_pd_stats_fn *pd_reset_stats_fn;
130 extern struct blkcg blkcg_root;
132 struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, struct request_queue *q);
133 struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
134 struct request_queue *q);
135 int blkcg_init_queue(struct request_queue *q);
136 void blkcg_drain_queue(struct request_queue *q);
137 void blkcg_exit_queue(struct request_queue *q);
139 /* Blkio controller policy registration */
140 int blkcg_policy_register(struct blkcg_policy *pol);
141 void blkcg_policy_unregister(struct blkcg_policy *pol);
142 int blkcg_activate_policy(struct request_queue *q,
143 const struct blkcg_policy *pol);
144 void blkcg_deactivate_policy(struct request_queue *q,
145 const struct blkcg_policy *pol);
147 void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg,
148 u64 (*prfill)(struct seq_file *,
149 struct blkg_policy_data *, int),
150 const struct blkcg_policy *pol, int data,
152 u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v);
153 u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
154 const struct blkg_rwstat *rwstat);
155 u64 blkg_prfill_stat(struct seq_file *sf, struct blkg_policy_data *pd, int off);
156 u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
159 struct blkg_conf_ctx {
160 struct gendisk *disk;
161 struct blkcg_gq *blkg;
165 int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
166 const char *input, struct blkg_conf_ctx *ctx);
167 void blkg_conf_finish(struct blkg_conf_ctx *ctx);
170 static inline struct blkcg *cgroup_to_blkcg(struct cgroup *cgroup)
172 return container_of(cgroup_subsys_state(cgroup, blkio_subsys_id),
176 static inline struct blkcg *task_blkcg(struct task_struct *tsk)
178 return container_of(task_subsys_state(tsk, blkio_subsys_id),
182 static inline struct blkcg *bio_blkcg(struct bio *bio)
184 if (bio && bio->bi_css)
185 return container_of(bio->bi_css, struct blkcg, css);
186 return task_blkcg(current);
190 * blkcg_parent - get the parent of a blkcg
191 * @blkcg: blkcg of interest
193 * Return the parent blkcg of @blkcg. Can be called anytime.
195 static inline struct blkcg *blkcg_parent(struct blkcg *blkcg)
197 struct cgroup *pcg = blkcg->css.cgroup->parent;
199 return pcg ? cgroup_to_blkcg(pcg) : NULL;
203 * blkg_to_pdata - get policy private data
204 * @blkg: blkg of interest
205 * @pol: policy of interest
207 * Return pointer to private data associated with the @blkg-@pol pair.
209 static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
210 struct blkcg_policy *pol)
212 return blkg ? blkg->pd[pol->plid] : NULL;
216 * pdata_to_blkg - get blkg associated with policy private data
217 * @pd: policy private data of interest
219 * @pd is policy private data. Determine the blkg it's associated with.
221 static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd)
223 return pd ? pd->blkg : NULL;
227 * blkg_path - format cgroup path of blkg
228 * @blkg: blkg of interest
229 * @buf: target buffer
230 * @buflen: target buffer length
232 * Format the path of the cgroup of @blkg into @buf.
234 static inline int blkg_path(struct blkcg_gq *blkg, char *buf, int buflen)
239 ret = cgroup_path(blkg->blkcg->css.cgroup, buf, buflen);
242 strncpy(buf, "<unavailable>", buflen);
247 * blkg_get - get a blkg reference
250 * The caller should be holding queue_lock and an existing reference.
252 static inline void blkg_get(struct blkcg_gq *blkg)
254 lockdep_assert_held(blkg->q->queue_lock);
255 WARN_ON_ONCE(!blkg->refcnt);
259 void __blkg_release(struct blkcg_gq *blkg);
262 * blkg_put - put a blkg reference
265 * The caller should be holding queue_lock.
267 static inline void blkg_put(struct blkcg_gq *blkg)
269 lockdep_assert_held(blkg->q->queue_lock);
270 WARN_ON_ONCE(blkg->refcnt <= 0);
272 __blkg_release(blkg);
276 * blk_get_rl - get request_list to use
277 * @q: request_queue of interest
278 * @bio: bio which will be attached to the allocated request (may be %NULL)
280 * The caller wants to allocate a request from @q to use for @bio. Find
281 * the request_list to use and obtain a reference on it. Should be called
282 * under queue_lock. This function is guaranteed to return non-%NULL
285 static inline struct request_list *blk_get_rl(struct request_queue *q,
289 struct blkcg_gq *blkg;
293 blkcg = bio_blkcg(bio);
295 /* bypass blkg lookup and use @q->root_rl directly for root */
296 if (blkcg == &blkcg_root)
300 * Try to use blkg->rl. blkg lookup may fail under memory pressure
301 * or if either the blkcg or queue is going away. Fall back to
302 * root_rl in such cases.
304 blkg = blkg_lookup_create(blkcg, q);
305 if (unlikely(IS_ERR(blkg)))
317 * blk_put_rl - put request_list
318 * @rl: request_list to put
320 * Put the reference acquired by blk_get_rl(). Should be called under
323 static inline void blk_put_rl(struct request_list *rl)
325 /* root_rl may not have blkg set */
326 if (rl->blkg && rl->blkg->blkcg != &blkcg_root)
331 * blk_rq_set_rl - associate a request with a request_list
332 * @rq: request of interest
333 * @rl: target request_list
335 * Associate @rq with @rl so that accounting and freeing can know the
336 * request_list @rq came from.
338 static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl)
344 * blk_rq_rl - return the request_list a request came from
345 * @rq: request of interest
347 * Return the request_list @rq is allocated from.
349 static inline struct request_list *blk_rq_rl(struct request *rq)
354 struct request_list *__blk_queue_next_rl(struct request_list *rl,
355 struct request_queue *q);
357 * blk_queue_for_each_rl - iterate through all request_lists of a request_queue
359 * Should be used under queue_lock.
361 #define blk_queue_for_each_rl(rl, q) \
362 for ((rl) = &(q)->root_rl; (rl); (rl) = __blk_queue_next_rl((rl), (q)))
365 * blkg_stat_add - add a value to a blkg_stat
366 * @stat: target blkg_stat
369 * Add @val to @stat. The caller is responsible for synchronizing calls to
372 static inline void blkg_stat_add(struct blkg_stat *stat, uint64_t val)
374 u64_stats_update_begin(&stat->syncp);
376 u64_stats_update_end(&stat->syncp);
380 * blkg_stat_read - read the current value of a blkg_stat
381 * @stat: blkg_stat to read
383 * Read the current value of @stat. This function can be called without
384 * synchroniztion and takes care of u64 atomicity.
386 static inline uint64_t blkg_stat_read(struct blkg_stat *stat)
392 start = u64_stats_fetch_begin(&stat->syncp);
394 } while (u64_stats_fetch_retry(&stat->syncp, start));
400 * blkg_stat_reset - reset a blkg_stat
401 * @stat: blkg_stat to reset
403 static inline void blkg_stat_reset(struct blkg_stat *stat)
409 * blkg_rwstat_add - add a value to a blkg_rwstat
410 * @rwstat: target blkg_rwstat
411 * @rw: mask of REQ_{WRITE|SYNC}
414 * Add @val to @rwstat. The counters are chosen according to @rw. The
415 * caller is responsible for synchronizing calls to this function.
417 static inline void blkg_rwstat_add(struct blkg_rwstat *rwstat,
418 int rw, uint64_t val)
420 u64_stats_update_begin(&rwstat->syncp);
423 rwstat->cnt[BLKG_RWSTAT_WRITE] += val;
425 rwstat->cnt[BLKG_RWSTAT_READ] += val;
427 rwstat->cnt[BLKG_RWSTAT_SYNC] += val;
429 rwstat->cnt[BLKG_RWSTAT_ASYNC] += val;
431 u64_stats_update_end(&rwstat->syncp);
435 * blkg_rwstat_read - read the current values of a blkg_rwstat
436 * @rwstat: blkg_rwstat to read
438 * Read the current snapshot of @rwstat and return it as the return value.
439 * This function can be called without synchronization and takes care of
442 static inline struct blkg_rwstat blkg_rwstat_read(struct blkg_rwstat *rwstat)
445 struct blkg_rwstat tmp;
448 start = u64_stats_fetch_begin(&rwstat->syncp);
450 } while (u64_stats_fetch_retry(&rwstat->syncp, start));
456 * blkg_rwstat_sum - read the total count of a blkg_rwstat
457 * @rwstat: blkg_rwstat to read
459 * Return the total count of @rwstat regardless of the IO direction. This
460 * function can be called without synchronization and takes care of u64
463 static inline uint64_t blkg_rwstat_sum(struct blkg_rwstat *rwstat)
465 struct blkg_rwstat tmp = blkg_rwstat_read(rwstat);
467 return tmp.cnt[BLKG_RWSTAT_READ] + tmp.cnt[BLKG_RWSTAT_WRITE];
471 * blkg_rwstat_reset - reset a blkg_rwstat
472 * @rwstat: blkg_rwstat to reset
474 static inline void blkg_rwstat_reset(struct blkg_rwstat *rwstat)
476 memset(rwstat->cnt, 0, sizeof(rwstat->cnt));
479 #else /* CONFIG_BLK_CGROUP */
484 struct blkg_policy_data {
490 struct blkcg_policy {
493 static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, void *key) { return NULL; }
494 static inline int blkcg_init_queue(struct request_queue *q) { return 0; }
495 static inline void blkcg_drain_queue(struct request_queue *q) { }
496 static inline void blkcg_exit_queue(struct request_queue *q) { }
497 static inline int blkcg_policy_register(struct blkcg_policy *pol) { return 0; }
498 static inline void blkcg_policy_unregister(struct blkcg_policy *pol) { }
499 static inline int blkcg_activate_policy(struct request_queue *q,
500 const struct blkcg_policy *pol) { return 0; }
501 static inline void blkcg_deactivate_policy(struct request_queue *q,
502 const struct blkcg_policy *pol) { }
504 static inline struct blkcg *cgroup_to_blkcg(struct cgroup *cgroup) { return NULL; }
505 static inline struct blkcg *bio_blkcg(struct bio *bio) { return NULL; }
507 static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
508 struct blkcg_policy *pol) { return NULL; }
509 static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd) { return NULL; }
510 static inline char *blkg_path(struct blkcg_gq *blkg) { return NULL; }
511 static inline void blkg_get(struct blkcg_gq *blkg) { }
512 static inline void blkg_put(struct blkcg_gq *blkg) { }
514 static inline struct request_list *blk_get_rl(struct request_queue *q,
515 struct bio *bio) { return &q->root_rl; }
516 static inline void blk_put_rl(struct request_list *rl) { }
517 static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl) { }
518 static inline struct request_list *blk_rq_rl(struct request *rq) { return &rq->q->root_rl; }
520 #define blk_queue_for_each_rl(rl, q) \
521 for ((rl) = &(q)->root_rl; (rl); (rl) = NULL)
523 #endif /* CONFIG_BLK_CGROUP */
524 #endif /* _BLK_CGROUP_H */