Root/block/blk-cgroup.h

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
32enum 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
42struct blkcg_gq;
43
44struct 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
60struct blkg_stat {
61    struct u64_stats_sync syncp;
62    uint64_t cnt;
63};
64
65struct 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 */
83struct 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 */
93struct 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
117typedef void (blkcg_pol_init_pd_fn)(struct blkcg_gq *blkg);
118typedef void (blkcg_pol_online_pd_fn)(struct blkcg_gq *blkg);
119typedef void (blkcg_pol_offline_pd_fn)(struct blkcg_gq *blkg);
120typedef void (blkcg_pol_exit_pd_fn)(struct blkcg_gq *blkg);
121typedef void (blkcg_pol_reset_pd_stats_fn)(struct blkcg_gq *blkg);
122
123struct 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
138extern struct blkcg blkcg_root;
139
140struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, struct request_queue *q);
141struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
142                    struct request_queue *q);
143int blkcg_init_queue(struct request_queue *q);
144void blkcg_drain_queue(struct request_queue *q);
145void blkcg_exit_queue(struct request_queue *q);
146
147/* Blkio controller policy registration */
148int blkcg_policy_register(struct blkcg_policy *pol);
149void blkcg_policy_unregister(struct blkcg_policy *pol);
150int blkcg_activate_policy(struct request_queue *q,
151              const struct blkcg_policy *pol);
152void blkcg_deactivate_policy(struct request_queue *q,
153                 const struct blkcg_policy *pol);
154
155void 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);
160u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v);
161u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
162             const struct blkg_rwstat *rwstat);
163u64 blkg_prfill_stat(struct seq_file *sf, struct blkg_policy_data *pd, int off);
164u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
165               int off);
166
167u64 blkg_stat_recursive_sum(struct blkg_policy_data *pd, int off);
168struct blkg_rwstat blkg_rwstat_recursive_sum(struct blkg_policy_data *pd,
169                         int off);
170
171struct blkg_conf_ctx {
172    struct gendisk *disk;
173    struct blkcg_gq *blkg;
174    u64 v;
175};
176
177int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
178           const char *input, struct blkg_conf_ctx *ctx);
179void blkg_conf_finish(struct blkg_conf_ctx *ctx);
180
181
182static inline struct blkcg *cgroup_to_blkcg(struct cgroup *cgroup)
183{
184    return container_of(cgroup_subsys_state(cgroup, blkio_subsys_id),
185                struct blkcg, css);
186}
187
188static inline struct blkcg *task_blkcg(struct task_struct *tsk)
189{
190    return container_of(task_subsys_state(tsk, blkio_subsys_id),
191                struct blkcg, css);
192}
193
194static inline struct blkcg *bio_blkcg(struct bio *bio)
195{
196    if (bio && bio->bi_css)
197        return container_of(bio->bi_css, struct blkcg, css);
198    return task_blkcg(current);
199}
200
201/**
202 * blkcg_parent - get the parent of a blkcg
203 * @blkcg: blkcg of interest
204 *
205 * Return the parent blkcg of @blkcg. Can be called anytime.
206 */
207static inline struct blkcg *blkcg_parent(struct blkcg *blkcg)
208{
209    struct cgroup *pcg = blkcg->css.cgroup->parent;
210
211    return pcg ? cgroup_to_blkcg(pcg) : NULL;
212}
213
214/**
215 * blkg_to_pdata - get policy private data
216 * @blkg: blkg of interest
217 * @pol: policy of interest
218 *
219 * Return pointer to private data associated with the @blkg-@pol pair.
220 */
221static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
222                          struct blkcg_policy *pol)
223{
224    return blkg ? blkg->pd[pol->plid] : NULL;
225}
226
227/**
228 * pdata_to_blkg - get blkg associated with policy private data
229 * @pd: policy private data of interest
230 *
231 * @pd is policy private data. Determine the blkg it's associated with.
232 */
233static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd)
234{
235    return pd ? pd->blkg : NULL;
236}
237
238/**
239 * blkg_path - format cgroup path of blkg
240 * @blkg: blkg of interest
241 * @buf: target buffer
242 * @buflen: target buffer length
243 *
244 * Format the path of the cgroup of @blkg into @buf.
245 */
246static inline int blkg_path(struct blkcg_gq *blkg, char *buf, int buflen)
247{
248    int ret;
249
250    rcu_read_lock();
251    ret = cgroup_path(blkg->blkcg->css.cgroup, buf, buflen);
252    rcu_read_unlock();
253    if (ret)
254        strncpy(buf, "<unavailable>", buflen);
255    return ret;
256}
257
258/**
259 * blkg_get - get a blkg reference
260 * @blkg: blkg to get
261 *
262 * The caller should be holding queue_lock and an existing reference.
263 */
264static inline void blkg_get(struct blkcg_gq *blkg)
265{
266    lockdep_assert_held(blkg->q->queue_lock);
267    WARN_ON_ONCE(!blkg->refcnt);
268    blkg->refcnt++;
269}
270
271void __blkg_release(struct blkcg_gq *blkg);
272
273/**
274 * blkg_put - put a blkg reference
275 * @blkg: blkg to put
276 *
277 * The caller should be holding queue_lock.
278 */
279static inline void blkg_put(struct blkcg_gq *blkg)
280{
281    lockdep_assert_held(blkg->q->queue_lock);
282    WARN_ON_ONCE(blkg->refcnt <= 0);
283    if (!--blkg->refcnt)
284        __blkg_release(blkg);
285}
286
287/**
288 * blk_get_rl - get request_list to use
289 * @q: request_queue of interest
290 * @bio: bio which will be attached to the allocated request (may be %NULL)
291 *
292 * The caller wants to allocate a request from @q to use for @bio. Find
293 * the request_list to use and obtain a reference on it. Should be called
294 * under queue_lock. This function is guaranteed to return non-%NULL
295 * request_list.
296 */
297static inline struct request_list *blk_get_rl(struct request_queue *q,
298                          struct bio *bio)
299{
300    struct blkcg *blkcg;
301    struct blkcg_gq *blkg;
302
303    rcu_read_lock();
304
305    blkcg = bio_blkcg(bio);
306
307    /* bypass blkg lookup and use @q->root_rl directly for root */
308    if (blkcg == &blkcg_root)
309        goto root_rl;
310
311    /*
312     * Try to use blkg->rl. blkg lookup may fail under memory pressure
313     * or if either the blkcg or queue is going away. Fall back to
314     * root_rl in such cases.
315     */
316    blkg = blkg_lookup_create(blkcg, q);
317    if (unlikely(IS_ERR(blkg)))
318        goto root_rl;
319
320    blkg_get(blkg);
321    rcu_read_unlock();
322    return &blkg->rl;
323root_rl:
324    rcu_read_unlock();
325    return &q->root_rl;
326}
327
328/**
329 * blk_put_rl - put request_list
330 * @rl: request_list to put
331 *
332 * Put the reference acquired by blk_get_rl(). Should be called under
333 * queue_lock.
334 */
335static inline void blk_put_rl(struct request_list *rl)
336{
337    /* root_rl may not have blkg set */
338    if (rl->blkg && rl->blkg->blkcg != &blkcg_root)
339        blkg_put(rl->blkg);
340}
341
342/**
343 * blk_rq_set_rl - associate a request with a request_list
344 * @rq: request of interest
345 * @rl: target request_list
346 *
347 * Associate @rq with @rl so that accounting and freeing can know the
348 * request_list @rq came from.
349 */
350static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl)
351{
352    rq->rl = rl;
353}
354
355/**
356 * blk_rq_rl - return the request_list a request came from
357 * @rq: request of interest
358 *
359 * Return the request_list @rq is allocated from.
360 */
361static inline struct request_list *blk_rq_rl(struct request *rq)
362{
363    return rq->rl;
364}
365
366struct request_list *__blk_queue_next_rl(struct request_list *rl,
367                     struct request_queue *q);
368/**
369 * blk_queue_for_each_rl - iterate through all request_lists of a request_queue
370 *
371 * Should be used under queue_lock.
372 */
373#define blk_queue_for_each_rl(rl, q) \
374    for ((rl) = &(q)->root_rl; (rl); (rl) = __blk_queue_next_rl((rl), (q)))
375
376/**
377 * blkg_stat_add - add a value to a blkg_stat
378 * @stat: target blkg_stat
379 * @val: value to add
380 *
381 * Add @val to @stat. The caller is responsible for synchronizing calls to
382 * this function.
383 */
384static inline void blkg_stat_add(struct blkg_stat *stat, uint64_t val)
385{
386    u64_stats_update_begin(&stat->syncp);
387    stat->cnt += val;
388    u64_stats_update_end(&stat->syncp);
389}
390
391/**
392 * blkg_stat_read - read the current value of a blkg_stat
393 * @stat: blkg_stat to read
394 *
395 * Read the current value of @stat. This function can be called without
396 * synchroniztion and takes care of u64 atomicity.
397 */
398static inline uint64_t blkg_stat_read(struct blkg_stat *stat)
399{
400    unsigned int start;
401    uint64_t v;
402
403    do {
404        start = u64_stats_fetch_begin(&stat->syncp);
405        v = stat->cnt;
406    } while (u64_stats_fetch_retry(&stat->syncp, start));
407
408    return v;
409}
410
411/**
412 * blkg_stat_reset - reset a blkg_stat
413 * @stat: blkg_stat to reset
414 */
415static inline void blkg_stat_reset(struct blkg_stat *stat)
416{
417    stat->cnt = 0;
418}
419
420/**
421 * blkg_stat_merge - merge a blkg_stat into another
422 * @to: the destination blkg_stat
423 * @from: the source
424 *
425 * Add @from's count to @to.
426 */
427static inline void blkg_stat_merge(struct blkg_stat *to, struct blkg_stat *from)
428{
429    blkg_stat_add(to, blkg_stat_read(from));
430}
431
432/**
433 * blkg_rwstat_add - add a value to a blkg_rwstat
434 * @rwstat: target blkg_rwstat
435 * @rw: mask of REQ_{WRITE|SYNC}
436 * @val: value to add
437 *
438 * Add @val to @rwstat. The counters are chosen according to @rw. The
439 * caller is responsible for synchronizing calls to this function.
440 */
441static inline void blkg_rwstat_add(struct blkg_rwstat *rwstat,
442                   int rw, uint64_t val)
443{
444    u64_stats_update_begin(&rwstat->syncp);
445
446    if (rw & REQ_WRITE)
447        rwstat->cnt[BLKG_RWSTAT_WRITE] += val;
448    else
449        rwstat->cnt[BLKG_RWSTAT_READ] += val;
450    if (rw & REQ_SYNC)
451        rwstat->cnt[BLKG_RWSTAT_SYNC] += val;
452    else
453        rwstat->cnt[BLKG_RWSTAT_ASYNC] += val;
454
455    u64_stats_update_end(&rwstat->syncp);
456}
457
458/**
459 * blkg_rwstat_read - read the current values of a blkg_rwstat
460 * @rwstat: blkg_rwstat to read
461 *
462 * Read the current snapshot of @rwstat and return it as the return value.
463 * This function can be called without synchronization and takes care of
464 * u64 atomicity.
465 */
466static inline struct blkg_rwstat blkg_rwstat_read(struct blkg_rwstat *rwstat)
467{
468    unsigned int start;
469    struct blkg_rwstat tmp;
470
471    do {
472        start = u64_stats_fetch_begin(&rwstat->syncp);
473        tmp = *rwstat;
474    } while (u64_stats_fetch_retry(&rwstat->syncp, start));
475
476    return tmp;
477}
478
479/**
480 * blkg_rwstat_total - read the total count of a blkg_rwstat
481 * @rwstat: blkg_rwstat to read
482 *
483 * Return the total count of @rwstat regardless of the IO direction. This
484 * function can be called without synchronization and takes care of u64
485 * atomicity.
486 */
487static inline uint64_t blkg_rwstat_total(struct blkg_rwstat *rwstat)
488{
489    struct blkg_rwstat tmp = blkg_rwstat_read(rwstat);
490
491    return tmp.cnt[BLKG_RWSTAT_READ] + tmp.cnt[BLKG_RWSTAT_WRITE];
492}
493
494/**
495 * blkg_rwstat_reset - reset a blkg_rwstat
496 * @rwstat: blkg_rwstat to reset
497 */
498static inline void blkg_rwstat_reset(struct blkg_rwstat *rwstat)
499{
500    memset(rwstat->cnt, 0, sizeof(rwstat->cnt));
501}
502
503/**
504 * blkg_rwstat_merge - merge a blkg_rwstat into another
505 * @to: the destination blkg_rwstat
506 * @from: the source
507 *
508 * Add @from's counts to @to.
509 */
510static inline void blkg_rwstat_merge(struct blkg_rwstat *to,
511                     struct blkg_rwstat *from)
512{
513    struct blkg_rwstat v = blkg_rwstat_read(from);
514    int i;
515
516    u64_stats_update_begin(&to->syncp);
517    for (i = 0; i < BLKG_RWSTAT_NR; i++)
518        to->cnt[i] += v.cnt[i];
519    u64_stats_update_end(&to->syncp);
520}
521
522#else /* CONFIG_BLK_CGROUP */
523
524struct cgroup;
525struct blkcg;
526
527struct blkg_policy_data {
528};
529
530struct blkcg_gq {
531};
532
533struct blkcg_policy {
534};
535
536static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, void *key) { return NULL; }
537static inline int blkcg_init_queue(struct request_queue *q) { return 0; }
538static inline void blkcg_drain_queue(struct request_queue *q) { }
539static inline void blkcg_exit_queue(struct request_queue *q) { }
540static inline int blkcg_policy_register(struct blkcg_policy *pol) { return 0; }
541static inline void blkcg_policy_unregister(struct blkcg_policy *pol) { }
542static inline int blkcg_activate_policy(struct request_queue *q,
543                    const struct blkcg_policy *pol) { return 0; }
544static inline void blkcg_deactivate_policy(struct request_queue *q,
545                       const struct blkcg_policy *pol) { }
546
547static inline struct blkcg *cgroup_to_blkcg(struct cgroup *cgroup) { return NULL; }
548static inline struct blkcg *bio_blkcg(struct bio *bio) { return NULL; }
549
550static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
551                          struct blkcg_policy *pol) { return NULL; }
552static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd) { return NULL; }
553static inline char *blkg_path(struct blkcg_gq *blkg) { return NULL; }
554static inline void blkg_get(struct blkcg_gq *blkg) { }
555static inline void blkg_put(struct blkcg_gq *blkg) { }
556
557static inline struct request_list *blk_get_rl(struct request_queue *q,
558                          struct bio *bio) { return &q->root_rl; }
559static inline void blk_put_rl(struct request_list *rl) { }
560static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl) { }
561static inline struct request_list *blk_rq_rl(struct request *rq) { return &rq->q->root_rl; }
562
563#define blk_queue_for_each_rl(rl, q) \
564    for ((rl) = &(q)->root_rl; (rl); (rl) = NULL)
565
566#endif /* CONFIG_BLK_CGROUP */
567#endif /* _BLK_CGROUP_H */
568

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