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    ret = cgroup_path(blkg->blkcg->css.cgroup, buf, buflen);
251    if (ret)
252        strncpy(buf, "<unavailable>", buflen);
253    return ret;
254}
255
256/**
257 * blkg_get - get a blkg reference
258 * @blkg: blkg to get
259 *
260 * The caller should be holding queue_lock and an existing reference.
261 */
262static inline void blkg_get(struct blkcg_gq *blkg)
263{
264    lockdep_assert_held(blkg->q->queue_lock);
265    WARN_ON_ONCE(!blkg->refcnt);
266    blkg->refcnt++;
267}
268
269void __blkg_release_rcu(struct rcu_head *rcu);
270
271/**
272 * blkg_put - put a blkg reference
273 * @blkg: blkg to put
274 *
275 * The caller should be holding queue_lock.
276 */
277static inline void blkg_put(struct blkcg_gq *blkg)
278{
279    lockdep_assert_held(blkg->q->queue_lock);
280    WARN_ON_ONCE(blkg->refcnt <= 0);
281    if (!--blkg->refcnt)
282        call_rcu(&blkg->rcu_head, __blkg_release_rcu);
283}
284
285struct blkcg_gq *__blkg_lookup(struct blkcg *blkcg, struct request_queue *q,
286                   bool update_hint);
287
288/**
289 * blkg_for_each_descendant_pre - pre-order walk of a blkg's descendants
290 * @d_blkg: loop cursor pointing to the current descendant
291 * @pos_cgrp: used for iteration
292 * @p_blkg: target blkg to walk descendants of
293 *
294 * Walk @c_blkg through the descendants of @p_blkg. Must be used with RCU
295 * read locked. If called under either blkcg or queue lock, the iteration
296 * is guaranteed to include all and only online blkgs. The caller may
297 * update @pos_cgrp by calling cgroup_rightmost_descendant() to skip
298 * subtree.
299 */
300#define blkg_for_each_descendant_pre(d_blkg, pos_cgrp, p_blkg) \
301    cgroup_for_each_descendant_pre((pos_cgrp), (p_blkg)->blkcg->css.cgroup) \
302        if (((d_blkg) = __blkg_lookup(cgroup_to_blkcg(pos_cgrp), \
303                          (p_blkg)->q, false)))
304
305/**
306 * blkg_for_each_descendant_post - post-order walk of a blkg's descendants
307 * @d_blkg: loop cursor pointing to the current descendant
308 * @pos_cgrp: used for iteration
309 * @p_blkg: target blkg to walk descendants of
310 *
311 * Similar to blkg_for_each_descendant_pre() but performs post-order
312 * traversal instead. Synchronization rules are the same.
313 */
314#define blkg_for_each_descendant_post(d_blkg, pos_cgrp, p_blkg) \
315    cgroup_for_each_descendant_post((pos_cgrp), (p_blkg)->blkcg->css.cgroup) \
316        if (((d_blkg) = __blkg_lookup(cgroup_to_blkcg(pos_cgrp), \
317                          (p_blkg)->q, false)))
318
319/**
320 * blk_get_rl - get request_list to use
321 * @q: request_queue of interest
322 * @bio: bio which will be attached to the allocated request (may be %NULL)
323 *
324 * The caller wants to allocate a request from @q to use for @bio. Find
325 * the request_list to use and obtain a reference on it. Should be called
326 * under queue_lock. This function is guaranteed to return non-%NULL
327 * request_list.
328 */
329static inline struct request_list *blk_get_rl(struct request_queue *q,
330                          struct bio *bio)
331{
332    struct blkcg *blkcg;
333    struct blkcg_gq *blkg;
334
335    rcu_read_lock();
336
337    blkcg = bio_blkcg(bio);
338
339    /* bypass blkg lookup and use @q->root_rl directly for root */
340    if (blkcg == &blkcg_root)
341        goto root_rl;
342
343    /*
344     * Try to use blkg->rl. blkg lookup may fail under memory pressure
345     * or if either the blkcg or queue is going away. Fall back to
346     * root_rl in such cases.
347     */
348    blkg = blkg_lookup_create(blkcg, q);
349    if (unlikely(IS_ERR(blkg)))
350        goto root_rl;
351
352    blkg_get(blkg);
353    rcu_read_unlock();
354    return &blkg->rl;
355root_rl:
356    rcu_read_unlock();
357    return &q->root_rl;
358}
359
360/**
361 * blk_put_rl - put request_list
362 * @rl: request_list to put
363 *
364 * Put the reference acquired by blk_get_rl(). Should be called under
365 * queue_lock.
366 */
367static inline void blk_put_rl(struct request_list *rl)
368{
369    /* root_rl may not have blkg set */
370    if (rl->blkg && rl->blkg->blkcg != &blkcg_root)
371        blkg_put(rl->blkg);
372}
373
374/**
375 * blk_rq_set_rl - associate a request with a request_list
376 * @rq: request of interest
377 * @rl: target request_list
378 *
379 * Associate @rq with @rl so that accounting and freeing can know the
380 * request_list @rq came from.
381 */
382static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl)
383{
384    rq->rl = rl;
385}
386
387/**
388 * blk_rq_rl - return the request_list a request came from
389 * @rq: request of interest
390 *
391 * Return the request_list @rq is allocated from.
392 */
393static inline struct request_list *blk_rq_rl(struct request *rq)
394{
395    return rq->rl;
396}
397
398struct request_list *__blk_queue_next_rl(struct request_list *rl,
399                     struct request_queue *q);
400/**
401 * blk_queue_for_each_rl - iterate through all request_lists of a request_queue
402 *
403 * Should be used under queue_lock.
404 */
405#define blk_queue_for_each_rl(rl, q) \
406    for ((rl) = &(q)->root_rl; (rl); (rl) = __blk_queue_next_rl((rl), (q)))
407
408/**
409 * blkg_stat_add - add a value to a blkg_stat
410 * @stat: target blkg_stat
411 * @val: value to add
412 *
413 * Add @val to @stat. The caller is responsible for synchronizing calls to
414 * this function.
415 */
416static inline void blkg_stat_add(struct blkg_stat *stat, uint64_t val)
417{
418    u64_stats_update_begin(&stat->syncp);
419    stat->cnt += val;
420    u64_stats_update_end(&stat->syncp);
421}
422
423/**
424 * blkg_stat_read - read the current value of a blkg_stat
425 * @stat: blkg_stat to read
426 *
427 * Read the current value of @stat. This function can be called without
428 * synchroniztion and takes care of u64 atomicity.
429 */
430static inline uint64_t blkg_stat_read(struct blkg_stat *stat)
431{
432    unsigned int start;
433    uint64_t v;
434
435    do {
436        start = u64_stats_fetch_begin(&stat->syncp);
437        v = stat->cnt;
438    } while (u64_stats_fetch_retry(&stat->syncp, start));
439
440    return v;
441}
442
443/**
444 * blkg_stat_reset - reset a blkg_stat
445 * @stat: blkg_stat to reset
446 */
447static inline void blkg_stat_reset(struct blkg_stat *stat)
448{
449    stat->cnt = 0;
450}
451
452/**
453 * blkg_stat_merge - merge a blkg_stat into another
454 * @to: the destination blkg_stat
455 * @from: the source
456 *
457 * Add @from's count to @to.
458 */
459static inline void blkg_stat_merge(struct blkg_stat *to, struct blkg_stat *from)
460{
461    blkg_stat_add(to, blkg_stat_read(from));
462}
463
464/**
465 * blkg_rwstat_add - add a value to a blkg_rwstat
466 * @rwstat: target blkg_rwstat
467 * @rw: mask of REQ_{WRITE|SYNC}
468 * @val: value to add
469 *
470 * Add @val to @rwstat. The counters are chosen according to @rw. The
471 * caller is responsible for synchronizing calls to this function.
472 */
473static inline void blkg_rwstat_add(struct blkg_rwstat *rwstat,
474                   int rw, uint64_t val)
475{
476    u64_stats_update_begin(&rwstat->syncp);
477
478    if (rw & REQ_WRITE)
479        rwstat->cnt[BLKG_RWSTAT_WRITE] += val;
480    else
481        rwstat->cnt[BLKG_RWSTAT_READ] += val;
482    if (rw & REQ_SYNC)
483        rwstat->cnt[BLKG_RWSTAT_SYNC] += val;
484    else
485        rwstat->cnt[BLKG_RWSTAT_ASYNC] += val;
486
487    u64_stats_update_end(&rwstat->syncp);
488}
489
490/**
491 * blkg_rwstat_read - read the current values of a blkg_rwstat
492 * @rwstat: blkg_rwstat to read
493 *
494 * Read the current snapshot of @rwstat and return it as the return value.
495 * This function can be called without synchronization and takes care of
496 * u64 atomicity.
497 */
498static inline struct blkg_rwstat blkg_rwstat_read(struct blkg_rwstat *rwstat)
499{
500    unsigned int start;
501    struct blkg_rwstat tmp;
502
503    do {
504        start = u64_stats_fetch_begin(&rwstat->syncp);
505        tmp = *rwstat;
506    } while (u64_stats_fetch_retry(&rwstat->syncp, start));
507
508    return tmp;
509}
510
511/**
512 * blkg_rwstat_total - read the total count of a blkg_rwstat
513 * @rwstat: blkg_rwstat to read
514 *
515 * Return the total count of @rwstat regardless of the IO direction. This
516 * function can be called without synchronization and takes care of u64
517 * atomicity.
518 */
519static inline uint64_t blkg_rwstat_total(struct blkg_rwstat *rwstat)
520{
521    struct blkg_rwstat tmp = blkg_rwstat_read(rwstat);
522
523    return tmp.cnt[BLKG_RWSTAT_READ] + tmp.cnt[BLKG_RWSTAT_WRITE];
524}
525
526/**
527 * blkg_rwstat_reset - reset a blkg_rwstat
528 * @rwstat: blkg_rwstat to reset
529 */
530static inline void blkg_rwstat_reset(struct blkg_rwstat *rwstat)
531{
532    memset(rwstat->cnt, 0, sizeof(rwstat->cnt));
533}
534
535/**
536 * blkg_rwstat_merge - merge a blkg_rwstat into another
537 * @to: the destination blkg_rwstat
538 * @from: the source
539 *
540 * Add @from's counts to @to.
541 */
542static inline void blkg_rwstat_merge(struct blkg_rwstat *to,
543                     struct blkg_rwstat *from)
544{
545    struct blkg_rwstat v = blkg_rwstat_read(from);
546    int i;
547
548    u64_stats_update_begin(&to->syncp);
549    for (i = 0; i < BLKG_RWSTAT_NR; i++)
550        to->cnt[i] += v.cnt[i];
551    u64_stats_update_end(&to->syncp);
552}
553
554#else /* CONFIG_BLK_CGROUP */
555
556struct cgroup;
557struct blkcg;
558
559struct blkg_policy_data {
560};
561
562struct blkcg_gq {
563};
564
565struct blkcg_policy {
566};
567
568static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, void *key) { return NULL; }
569static inline int blkcg_init_queue(struct request_queue *q) { return 0; }
570static inline void blkcg_drain_queue(struct request_queue *q) { }
571static inline void blkcg_exit_queue(struct request_queue *q) { }
572static inline int blkcg_policy_register(struct blkcg_policy *pol) { return 0; }
573static inline void blkcg_policy_unregister(struct blkcg_policy *pol) { }
574static inline int blkcg_activate_policy(struct request_queue *q,
575                    const struct blkcg_policy *pol) { return 0; }
576static inline void blkcg_deactivate_policy(struct request_queue *q,
577                       const struct blkcg_policy *pol) { }
578
579static inline struct blkcg *cgroup_to_blkcg(struct cgroup *cgroup) { return NULL; }
580static inline struct blkcg *bio_blkcg(struct bio *bio) { return NULL; }
581
582static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
583                          struct blkcg_policy *pol) { return NULL; }
584static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd) { return NULL; }
585static inline char *blkg_path(struct blkcg_gq *blkg) { return NULL; }
586static inline void blkg_get(struct blkcg_gq *blkg) { }
587static inline void blkg_put(struct blkcg_gq *blkg) { }
588
589static inline struct request_list *blk_get_rl(struct request_queue *q,
590                          struct bio *bio) { return &q->root_rl; }
591static inline void blk_put_rl(struct request_list *rl) { }
592static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl) { }
593static inline struct request_list *blk_rq_rl(struct request *rq) { return &rq->q->root_rl; }
594
595#define blk_queue_for_each_rl(rl, q) \
596    for ((rl) = &(q)->root_rl; (rl); (rl) = NULL)
597
598#endif /* CONFIG_BLK_CGROUP */
599#endif /* _BLK_CGROUP_H */
600

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od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9



interactive