linux/block/blk-cgroup.h
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   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};
  58
  59struct blkg_stat {
  60        struct u64_stats_sync           syncp;
  61        uint64_t                        cnt;
  62};
  63
  64struct blkg_rwstat {
  65        struct u64_stats_sync           syncp;
  66        uint64_t                        cnt[BLKG_RWSTAT_NR];
  67};
  68
  69/*
  70 * A blkcg_gq (blkg) is association between a block cgroup (blkcg) and a
  71 * request_queue (q).  This is used by blkcg policies which need to track
  72 * information per blkcg - q pair.
  73 *
  74 * There can be multiple active blkcg policies and each has its private
  75 * data on each blkg, the size of which is determined by
  76 * blkcg_policy->pd_size.  blkcg core allocates and frees such areas
  77 * together with blkg and invokes pd_init/exit_fn() methods.
  78 *
  79 * Such private data must embed struct blkg_policy_data (pd) at the
  80 * beginning and pd_size can't be smaller than pd.
  81 */
  82struct blkg_policy_data {
  83        /* the blkg this per-policy data belongs to */
  84        struct blkcg_gq                 *blkg;
  85
  86        /* used during policy activation */
  87        struct list_head                alloc_node;
  88};
  89
  90/* association between a blk cgroup and a request queue */
  91struct blkcg_gq {
  92        /* Pointer to the associated request_queue */
  93        struct request_queue            *q;
  94        struct list_head                q_node;
  95        struct hlist_node               blkcg_node;
  96        struct blkcg                    *blkcg;
  97        /* request allocation list for this blkcg-q pair */
  98        struct request_list             rl;
  99        /* reference count */
 100        int                             refcnt;
 101
 102        struct blkg_policy_data         *pd[BLKCG_MAX_POLS];
 103
 104        struct rcu_head                 rcu_head;
 105};
 106
 107typedef void (blkcg_pol_init_pd_fn)(struct blkcg_gq *blkg);
 108typedef void (blkcg_pol_exit_pd_fn)(struct blkcg_gq *blkg);
 109typedef void (blkcg_pol_reset_pd_stats_fn)(struct blkcg_gq *blkg);
 110
 111struct blkcg_policy {
 112        int                             plid;
 113        /* policy specific private data size */
 114        size_t                          pd_size;
 115        /* cgroup files for the policy */
 116        struct cftype                   *cftypes;
 117
 118        /* operations */
 119        blkcg_pol_init_pd_fn            *pd_init_fn;
 120        blkcg_pol_exit_pd_fn            *pd_exit_fn;
 121        blkcg_pol_reset_pd_stats_fn     *pd_reset_stats_fn;
 122};
 123
 124extern struct blkcg blkcg_root;
 125
 126struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, struct request_queue *q);
 127struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
 128                                    struct request_queue *q);
 129int blkcg_init_queue(struct request_queue *q);
 130void blkcg_drain_queue(struct request_queue *q);
 131void blkcg_exit_queue(struct request_queue *q);
 132
 133/* Blkio controller policy registration */
 134int blkcg_policy_register(struct blkcg_policy *pol);
 135void blkcg_policy_unregister(struct blkcg_policy *pol);
 136int blkcg_activate_policy(struct request_queue *q,
 137                          const struct blkcg_policy *pol);
 138void blkcg_deactivate_policy(struct request_queue *q,
 139                             const struct blkcg_policy *pol);
 140
 141void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg,
 142                       u64 (*prfill)(struct seq_file *,
 143                                     struct blkg_policy_data *, int),
 144                       const struct blkcg_policy *pol, int data,
 145                       bool show_total);
 146u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v);
 147u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
 148                         const struct blkg_rwstat *rwstat);
 149u64 blkg_prfill_stat(struct seq_file *sf, struct blkg_policy_data *pd, int off);
 150u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
 151                       int off);
 152
 153struct blkg_conf_ctx {
 154        struct gendisk                  *disk;
 155        struct blkcg_gq                 *blkg;
 156        u64                             v;
 157};
 158
 159int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
 160                   const char *input, struct blkg_conf_ctx *ctx);
 161void blkg_conf_finish(struct blkg_conf_ctx *ctx);
 162
 163
 164static inline struct blkcg *cgroup_to_blkcg(struct cgroup *cgroup)
 165{
 166        return container_of(cgroup_subsys_state(cgroup, blkio_subsys_id),
 167                            struct blkcg, css);
 168}
 169
 170static inline struct blkcg *task_blkcg(struct task_struct *tsk)
 171{
 172        return container_of(task_subsys_state(tsk, blkio_subsys_id),
 173                            struct blkcg, css);
 174}
 175
 176static inline struct blkcg *bio_blkcg(struct bio *bio)
 177{
 178        if (bio && bio->bi_css)
 179                return container_of(bio->bi_css, struct blkcg, css);
 180        return task_blkcg(current);
 181}
 182
 183/**
 184 * blkg_to_pdata - get policy private data
 185 * @blkg: blkg of interest
 186 * @pol: policy of interest
 187 *
 188 * Return pointer to private data associated with the @blkg-@pol pair.
 189 */
 190static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
 191                                                  struct blkcg_policy *pol)
 192{
 193        return blkg ? blkg->pd[pol->plid] : NULL;
 194}
 195
 196/**
 197 * pdata_to_blkg - get blkg associated with policy private data
 198 * @pd: policy private data of interest
 199 *
 200 * @pd is policy private data.  Determine the blkg it's associated with.
 201 */
 202static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd)
 203{
 204        return pd ? pd->blkg : NULL;
 205}
 206
 207/**
 208 * blkg_path - format cgroup path of blkg
 209 * @blkg: blkg of interest
 210 * @buf: target buffer
 211 * @buflen: target buffer length
 212 *
 213 * Format the path of the cgroup of @blkg into @buf.
 214 */
 215static inline int blkg_path(struct blkcg_gq *blkg, char *buf, int buflen)
 216{
 217        int ret;
 218
 219        rcu_read_lock();
 220        ret = cgroup_path(blkg->blkcg->css.cgroup, buf, buflen);
 221        rcu_read_unlock();
 222        if (ret)
 223                strncpy(buf, "<unavailable>", buflen);
 224        return ret;
 225}
 226
 227/**
 228 * blkg_get - get a blkg reference
 229 * @blkg: blkg to get
 230 *
 231 * The caller should be holding queue_lock and an existing reference.
 232 */
 233static inline void blkg_get(struct blkcg_gq *blkg)
 234{
 235        lockdep_assert_held(blkg->q->queue_lock);
 236        WARN_ON_ONCE(!blkg->refcnt);
 237        blkg->refcnt++;
 238}
 239
 240void __blkg_release(struct blkcg_gq *blkg);
 241
 242/**
 243 * blkg_put - put a blkg reference
 244 * @blkg: blkg to put
 245 *
 246 * The caller should be holding queue_lock.
 247 */
 248static inline void blkg_put(struct blkcg_gq *blkg)
 249{
 250        lockdep_assert_held(blkg->q->queue_lock);
 251        WARN_ON_ONCE(blkg->refcnt <= 0);
 252        if (!--blkg->refcnt)
 253                __blkg_release(blkg);
 254}
 255
 256/**
 257 * blk_get_rl - get request_list to use
 258 * @q: request_queue of interest
 259 * @bio: bio which will be attached to the allocated request (may be %NULL)
 260 *
 261 * The caller wants to allocate a request from @q to use for @bio.  Find
 262 * the request_list to use and obtain a reference on it.  Should be called
 263 * under queue_lock.  This function is guaranteed to return non-%NULL
 264 * request_list.
 265 */
 266static inline struct request_list *blk_get_rl(struct request_queue *q,
 267                                              struct bio *bio)
 268{
 269        struct blkcg *blkcg;
 270        struct blkcg_gq *blkg;
 271
 272        rcu_read_lock();
 273
 274        blkcg = bio_blkcg(bio);
 275
 276        /* bypass blkg lookup and use @q->root_rl directly for root */
 277        if (blkcg == &blkcg_root)
 278                goto root_rl;
 279
 280        /*
 281         * Try to use blkg->rl.  blkg lookup may fail under memory pressure
 282         * or if either the blkcg or queue is going away.  Fall back to
 283         * root_rl in such cases.
 284         */
 285        blkg = blkg_lookup_create(blkcg, q);
 286        if (unlikely(IS_ERR(blkg)))
 287                goto root_rl;
 288
 289        blkg_get(blkg);
 290        rcu_read_unlock();
 291        return &blkg->rl;
 292root_rl:
 293        rcu_read_unlock();
 294        return &q->root_rl;
 295}
 296
 297/**
 298 * blk_put_rl - put request_list
 299 * @rl: request_list to put
 300 *
 301 * Put the reference acquired by blk_get_rl().  Should be called under
 302 * queue_lock.
 303 */
 304static inline void blk_put_rl(struct request_list *rl)
 305{
 306        /* root_rl may not have blkg set */
 307        if (rl->blkg && rl->blkg->blkcg != &blkcg_root)
 308                blkg_put(rl->blkg);
 309}
 310
 311/**
 312 * blk_rq_set_rl - associate a request with a request_list
 313 * @rq: request of interest
 314 * @rl: target request_list
 315 *
 316 * Associate @rq with @rl so that accounting and freeing can know the
 317 * request_list @rq came from.
 318 */
 319static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl)
 320{
 321        rq->rl = rl;
 322}
 323
 324/**
 325 * blk_rq_rl - return the request_list a request came from
 326 * @rq: request of interest
 327 *
 328 * Return the request_list @rq is allocated from.
 329 */
 330static inline struct request_list *blk_rq_rl(struct request *rq)
 331{
 332        return rq->rl;
 333}
 334
 335struct request_list *__blk_queue_next_rl(struct request_list *rl,
 336                                         struct request_queue *q);
 337/**
 338 * blk_queue_for_each_rl - iterate through all request_lists of a request_queue
 339 *
 340 * Should be used under queue_lock.
 341 */
 342#define blk_queue_for_each_rl(rl, q)    \
 343        for ((rl) = &(q)->root_rl; (rl); (rl) = __blk_queue_next_rl((rl), (q)))
 344
 345/**
 346 * blkg_stat_add - add a value to a blkg_stat
 347 * @stat: target blkg_stat
 348 * @val: value to add
 349 *
 350 * Add @val to @stat.  The caller is responsible for synchronizing calls to
 351 * this function.
 352 */
 353static inline void blkg_stat_add(struct blkg_stat *stat, uint64_t val)
 354{
 355        u64_stats_update_begin(&stat->syncp);
 356        stat->cnt += val;
 357        u64_stats_update_end(&stat->syncp);
 358}
 359
 360/**
 361 * blkg_stat_read - read the current value of a blkg_stat
 362 * @stat: blkg_stat to read
 363 *
 364 * Read the current value of @stat.  This function can be called without
 365 * synchroniztion and takes care of u64 atomicity.
 366 */
 367static inline uint64_t blkg_stat_read(struct blkg_stat *stat)
 368{
 369        unsigned int start;
 370        uint64_t v;
 371
 372        do {
 373                start = u64_stats_fetch_begin(&stat->syncp);
 374                v = stat->cnt;
 375        } while (u64_stats_fetch_retry(&stat->syncp, start));
 376
 377        return v;
 378}
 379
 380/**
 381 * blkg_stat_reset - reset a blkg_stat
 382 * @stat: blkg_stat to reset
 383 */
 384static inline void blkg_stat_reset(struct blkg_stat *stat)
 385{
 386        stat->cnt = 0;
 387}
 388
 389/**
 390 * blkg_rwstat_add - add a value to a blkg_rwstat
 391 * @rwstat: target blkg_rwstat
 392 * @rw: mask of REQ_{WRITE|SYNC}
 393 * @val: value to add
 394 *
 395 * Add @val to @rwstat.  The counters are chosen according to @rw.  The
 396 * caller is responsible for synchronizing calls to this function.
 397 */
 398static inline void blkg_rwstat_add(struct blkg_rwstat *rwstat,
 399                                   int rw, uint64_t val)
 400{
 401        u64_stats_update_begin(&rwstat->syncp);
 402
 403        if (rw & REQ_WRITE)
 404                rwstat->cnt[BLKG_RWSTAT_WRITE] += val;
 405        else
 406                rwstat->cnt[BLKG_RWSTAT_READ] += val;
 407        if (rw & REQ_SYNC)
 408                rwstat->cnt[BLKG_RWSTAT_SYNC] += val;
 409        else
 410                rwstat->cnt[BLKG_RWSTAT_ASYNC] += val;
 411
 412        u64_stats_update_end(&rwstat->syncp);
 413}
 414
 415/**
 416 * blkg_rwstat_read - read the current values of a blkg_rwstat
 417 * @rwstat: blkg_rwstat to read
 418 *
 419 * Read the current snapshot of @rwstat and return it as the return value.
 420 * This function can be called without synchronization and takes care of
 421 * u64 atomicity.
 422 */
 423static inline struct blkg_rwstat blkg_rwstat_read(struct blkg_rwstat *rwstat)
 424{
 425        unsigned int start;
 426        struct blkg_rwstat tmp;
 427
 428        do {
 429                start = u64_stats_fetch_begin(&rwstat->syncp);
 430                tmp = *rwstat;
 431        } while (u64_stats_fetch_retry(&rwstat->syncp, start));
 432
 433        return tmp;
 434}
 435
 436/**
 437 * blkg_rwstat_sum - read the total count of a blkg_rwstat
 438 * @rwstat: blkg_rwstat to read
 439 *
 440 * Return the total count of @rwstat regardless of the IO direction.  This
 441 * function can be called without synchronization and takes care of u64
 442 * atomicity.
 443 */
 444static inline uint64_t blkg_rwstat_sum(struct blkg_rwstat *rwstat)
 445{
 446        struct blkg_rwstat tmp = blkg_rwstat_read(rwstat);
 447
 448        return tmp.cnt[BLKG_RWSTAT_READ] + tmp.cnt[BLKG_RWSTAT_WRITE];
 449}
 450
 451/**
 452 * blkg_rwstat_reset - reset a blkg_rwstat
 453 * @rwstat: blkg_rwstat to reset
 454 */
 455static inline void blkg_rwstat_reset(struct blkg_rwstat *rwstat)
 456{
 457        memset(rwstat->cnt, 0, sizeof(rwstat->cnt));
 458}
 459
 460#else   /* CONFIG_BLK_CGROUP */
 461
 462struct cgroup;
 463struct blkcg;
 464
 465struct blkg_policy_data {
 466};
 467
 468struct blkcg_gq {
 469};
 470
 471struct blkcg_policy {
 472};
 473
 474static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, void *key) { return NULL; }
 475static inline int blkcg_init_queue(struct request_queue *q) { return 0; }
 476static inline void blkcg_drain_queue(struct request_queue *q) { }
 477static inline void blkcg_exit_queue(struct request_queue *q) { }
 478static inline int blkcg_policy_register(struct blkcg_policy *pol) { return 0; }
 479static inline void blkcg_policy_unregister(struct blkcg_policy *pol) { }
 480static inline int blkcg_activate_policy(struct request_queue *q,
 481                                        const struct blkcg_policy *pol) { return 0; }
 482static inline void blkcg_deactivate_policy(struct request_queue *q,
 483                                           const struct blkcg_policy *pol) { }
 484
 485static inline struct blkcg *cgroup_to_blkcg(struct cgroup *cgroup) { return NULL; }
 486static inline struct blkcg *bio_blkcg(struct bio *bio) { return NULL; }
 487
 488static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
 489                                                  struct blkcg_policy *pol) { return NULL; }
 490static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd) { return NULL; }
 491static inline char *blkg_path(struct blkcg_gq *blkg) { return NULL; }
 492static inline void blkg_get(struct blkcg_gq *blkg) { }
 493static inline void blkg_put(struct blkcg_gq *blkg) { }
 494
 495static inline struct request_list *blk_get_rl(struct request_queue *q,
 496                                              struct bio *bio) { return &q->root_rl; }
 497static inline void blk_put_rl(struct request_list *rl) { }
 498static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl) { }
 499static inline struct request_list *blk_rq_rl(struct request *rq) { return &rq->q->root_rl; }
 500
 501#define blk_queue_for_each_rl(rl, q)    \
 502        for ((rl) = &(q)->root_rl; (rl); (rl) = NULL)
 503
 504#endif  /* CONFIG_BLK_CGROUP */
 505#endif  /* _BLK_CGROUP_H */
 506
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