block: prepare for multiple request_lists
[linux-2.6/libata-dev.git] / block / blk-cgroup.h
blobe74cce1fbac9476ab8940e0aa8ca810600dbd1a1
1 #ifndef _BLK_CGROUP_H
2 #define _BLK_CGROUP_H
3 /*
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>
21 /* Max limits for throttle policy */
22 #define THROTL_IOPS_MAX UINT_MAX
24 /* CFQ specific, out here for blkcg->cfq_weight */
25 #define CFQ_WEIGHT_MIN 10
26 #define CFQ_WEIGHT_MAX 1000
27 #define CFQ_WEIGHT_DEFAULT 500
29 #ifdef CONFIG_BLK_CGROUP
31 enum blkg_rwstat_type {
32 BLKG_RWSTAT_READ,
33 BLKG_RWSTAT_WRITE,
34 BLKG_RWSTAT_SYNC,
35 BLKG_RWSTAT_ASYNC,
37 BLKG_RWSTAT_NR,
38 BLKG_RWSTAT_TOTAL = BLKG_RWSTAT_NR,
41 struct blkcg_gq;
43 struct blkcg {
44 struct cgroup_subsys_state css;
45 spinlock_t lock;
47 struct radix_tree_root blkg_tree;
48 struct blkcg_gq *blkg_hint;
49 struct hlist_head blkg_list;
51 /* for policies to test whether associated blkcg has changed */
52 uint64_t id;
54 /* TODO: per-policy storage in blkcg */
55 unsigned int cfq_weight; /* belongs to cfq */
58 struct blkg_stat {
59 struct u64_stats_sync syncp;
60 uint64_t cnt;
63 struct blkg_rwstat {
64 struct u64_stats_sync syncp;
65 uint64_t cnt[BLKG_RWSTAT_NR];
69 * A blkcg_gq (blkg) is association between a block cgroup (blkcg) and a
70 * request_queue (q). This is used by blkcg policies which need to track
71 * information per blkcg - q pair.
73 * There can be multiple active blkcg policies and each has its private
74 * data on each blkg, the size of which is determined by
75 * blkcg_policy->pd_size. blkcg core allocates and frees such areas
76 * together with blkg and invokes pd_init/exit_fn() methods.
78 * Such private data must embed struct blkg_policy_data (pd) at the
79 * beginning and pd_size can't be smaller than pd.
81 struct blkg_policy_data {
82 /* the blkg this per-policy data belongs to */
83 struct blkcg_gq *blkg;
85 /* used during policy activation */
86 struct list_head alloc_node;
89 /* association between a blk cgroup and a request queue */
90 struct blkcg_gq {
91 /* Pointer to the associated request_queue */
92 struct request_queue *q;
93 struct list_head q_node;
94 struct hlist_node blkcg_node;
95 struct blkcg *blkcg;
96 /* reference count */
97 int refcnt;
99 struct blkg_policy_data *pd[BLKCG_MAX_POLS];
101 struct rcu_head rcu_head;
104 typedef void (blkcg_pol_init_pd_fn)(struct blkcg_gq *blkg);
105 typedef void (blkcg_pol_exit_pd_fn)(struct blkcg_gq *blkg);
106 typedef void (blkcg_pol_reset_pd_stats_fn)(struct blkcg_gq *blkg);
108 struct blkcg_policy {
109 int plid;
110 /* policy specific private data size */
111 size_t pd_size;
112 /* cgroup files for the policy */
113 struct cftype *cftypes;
115 /* operations */
116 blkcg_pol_init_pd_fn *pd_init_fn;
117 blkcg_pol_exit_pd_fn *pd_exit_fn;
118 blkcg_pol_reset_pd_stats_fn *pd_reset_stats_fn;
121 extern struct blkcg blkcg_root;
123 struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, struct request_queue *q);
124 struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
125 struct request_queue *q);
126 int blkcg_init_queue(struct request_queue *q);
127 void blkcg_drain_queue(struct request_queue *q);
128 void blkcg_exit_queue(struct request_queue *q);
130 /* Blkio controller policy registration */
131 int blkcg_policy_register(struct blkcg_policy *pol);
132 void blkcg_policy_unregister(struct blkcg_policy *pol);
133 int blkcg_activate_policy(struct request_queue *q,
134 const struct blkcg_policy *pol);
135 void blkcg_deactivate_policy(struct request_queue *q,
136 const struct blkcg_policy *pol);
138 void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg,
139 u64 (*prfill)(struct seq_file *,
140 struct blkg_policy_data *, int),
141 const struct blkcg_policy *pol, int data,
142 bool show_total);
143 u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v);
144 u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
145 const struct blkg_rwstat *rwstat);
146 u64 blkg_prfill_stat(struct seq_file *sf, struct blkg_policy_data *pd, int off);
147 u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
148 int off);
150 struct blkg_conf_ctx {
151 struct gendisk *disk;
152 struct blkcg_gq *blkg;
153 u64 v;
156 int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
157 const char *input, struct blkg_conf_ctx *ctx);
158 void blkg_conf_finish(struct blkg_conf_ctx *ctx);
161 static inline struct blkcg *cgroup_to_blkcg(struct cgroup *cgroup)
163 return container_of(cgroup_subsys_state(cgroup, blkio_subsys_id),
164 struct blkcg, css);
167 static inline struct blkcg *task_blkcg(struct task_struct *tsk)
169 return container_of(task_subsys_state(tsk, blkio_subsys_id),
170 struct blkcg, css);
173 static inline struct blkcg *bio_blkcg(struct bio *bio)
175 if (bio && bio->bi_css)
176 return container_of(bio->bi_css, struct blkcg, css);
177 return task_blkcg(current);
181 * blkg_to_pdata - get policy private data
182 * @blkg: blkg of interest
183 * @pol: policy of interest
185 * Return pointer to private data associated with the @blkg-@pol pair.
187 static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
188 struct blkcg_policy *pol)
190 return blkg ? blkg->pd[pol->plid] : NULL;
194 * pdata_to_blkg - get blkg associated with policy private data
195 * @pd: policy private data of interest
197 * @pd is policy private data. Determine the blkg it's associated with.
199 static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd)
201 return pd ? pd->blkg : NULL;
205 * blkg_path - format cgroup path of blkg
206 * @blkg: blkg of interest
207 * @buf: target buffer
208 * @buflen: target buffer length
210 * Format the path of the cgroup of @blkg into @buf.
212 static inline int blkg_path(struct blkcg_gq *blkg, char *buf, int buflen)
214 int ret;
216 rcu_read_lock();
217 ret = cgroup_path(blkg->blkcg->css.cgroup, buf, buflen);
218 rcu_read_unlock();
219 if (ret)
220 strncpy(buf, "<unavailable>", buflen);
221 return ret;
225 * blkg_get - get a blkg reference
226 * @blkg: blkg to get
228 * The caller should be holding queue_lock and an existing reference.
230 static inline void blkg_get(struct blkcg_gq *blkg)
232 lockdep_assert_held(blkg->q->queue_lock);
233 WARN_ON_ONCE(!blkg->refcnt);
234 blkg->refcnt++;
237 void __blkg_release(struct blkcg_gq *blkg);
240 * blkg_put - put a blkg reference
241 * @blkg: blkg to put
243 * The caller should be holding queue_lock.
245 static inline void blkg_put(struct blkcg_gq *blkg)
247 lockdep_assert_held(blkg->q->queue_lock);
248 WARN_ON_ONCE(blkg->refcnt <= 0);
249 if (!--blkg->refcnt)
250 __blkg_release(blkg);
254 * blkg_stat_add - add a value to a blkg_stat
255 * @stat: target blkg_stat
256 * @val: value to add
258 * Add @val to @stat. The caller is responsible for synchronizing calls to
259 * this function.
261 static inline void blkg_stat_add(struct blkg_stat *stat, uint64_t val)
263 u64_stats_update_begin(&stat->syncp);
264 stat->cnt += val;
265 u64_stats_update_end(&stat->syncp);
269 * blkg_stat_read - read the current value of a blkg_stat
270 * @stat: blkg_stat to read
272 * Read the current value of @stat. This function can be called without
273 * synchroniztion and takes care of u64 atomicity.
275 static inline uint64_t blkg_stat_read(struct blkg_stat *stat)
277 unsigned int start;
278 uint64_t v;
280 do {
281 start = u64_stats_fetch_begin(&stat->syncp);
282 v = stat->cnt;
283 } while (u64_stats_fetch_retry(&stat->syncp, start));
285 return v;
289 * blkg_stat_reset - reset a blkg_stat
290 * @stat: blkg_stat to reset
292 static inline void blkg_stat_reset(struct blkg_stat *stat)
294 stat->cnt = 0;
298 * blkg_rwstat_add - add a value to a blkg_rwstat
299 * @rwstat: target blkg_rwstat
300 * @rw: mask of REQ_{WRITE|SYNC}
301 * @val: value to add
303 * Add @val to @rwstat. The counters are chosen according to @rw. The
304 * caller is responsible for synchronizing calls to this function.
306 static inline void blkg_rwstat_add(struct blkg_rwstat *rwstat,
307 int rw, uint64_t val)
309 u64_stats_update_begin(&rwstat->syncp);
311 if (rw & REQ_WRITE)
312 rwstat->cnt[BLKG_RWSTAT_WRITE] += val;
313 else
314 rwstat->cnt[BLKG_RWSTAT_READ] += val;
315 if (rw & REQ_SYNC)
316 rwstat->cnt[BLKG_RWSTAT_SYNC] += val;
317 else
318 rwstat->cnt[BLKG_RWSTAT_ASYNC] += val;
320 u64_stats_update_end(&rwstat->syncp);
324 * blkg_rwstat_read - read the current values of a blkg_rwstat
325 * @rwstat: blkg_rwstat to read
327 * Read the current snapshot of @rwstat and return it as the return value.
328 * This function can be called without synchronization and takes care of
329 * u64 atomicity.
331 static inline struct blkg_rwstat blkg_rwstat_read(struct blkg_rwstat *rwstat)
333 unsigned int start;
334 struct blkg_rwstat tmp;
336 do {
337 start = u64_stats_fetch_begin(&rwstat->syncp);
338 tmp = *rwstat;
339 } while (u64_stats_fetch_retry(&rwstat->syncp, start));
341 return tmp;
345 * blkg_rwstat_sum - read the total count of a blkg_rwstat
346 * @rwstat: blkg_rwstat to read
348 * Return the total count of @rwstat regardless of the IO direction. This
349 * function can be called without synchronization and takes care of u64
350 * atomicity.
352 static inline uint64_t blkg_rwstat_sum(struct blkg_rwstat *rwstat)
354 struct blkg_rwstat tmp = blkg_rwstat_read(rwstat);
356 return tmp.cnt[BLKG_RWSTAT_READ] + tmp.cnt[BLKG_RWSTAT_WRITE];
360 * blkg_rwstat_reset - reset a blkg_rwstat
361 * @rwstat: blkg_rwstat to reset
363 static inline void blkg_rwstat_reset(struct blkg_rwstat *rwstat)
365 memset(rwstat->cnt, 0, sizeof(rwstat->cnt));
368 #else /* CONFIG_BLK_CGROUP */
370 struct cgroup;
371 struct blkcg;
373 struct blkg_policy_data {
376 struct blkcg_gq {
379 struct blkcg_policy {
382 static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, void *key) { return NULL; }
383 static inline int blkcg_init_queue(struct request_queue *q) { return 0; }
384 static inline void blkcg_drain_queue(struct request_queue *q) { }
385 static inline void blkcg_exit_queue(struct request_queue *q) { }
386 static inline int blkcg_policy_register(struct blkcg_policy *pol) { return 0; }
387 static inline void blkcg_policy_unregister(struct blkcg_policy *pol) { }
388 static inline int blkcg_activate_policy(struct request_queue *q,
389 const struct blkcg_policy *pol) { return 0; }
390 static inline void blkcg_deactivate_policy(struct request_queue *q,
391 const struct blkcg_policy *pol) { }
393 static inline struct blkcg *cgroup_to_blkcg(struct cgroup *cgroup) { return NULL; }
394 static inline struct blkcg *bio_blkcg(struct bio *bio) { return NULL; }
395 static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
396 struct blkcg_policy *pol) { return NULL; }
397 static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd) { return NULL; }
398 static inline char *blkg_path(struct blkcg_gq *blkg) { return NULL; }
399 static inline void blkg_get(struct blkcg_gq *blkg) { }
400 static inline void blkg_put(struct blkcg_gq *blkg) { }
402 #endif /* CONFIG_BLK_CGROUP */
403 #endif /* _BLK_CGROUP_H */