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 #include <linux/atomic.h>
  22
  23 /* Max limits for throttle policy */
  24 #define THROTL_IOPS_MAX         UINT_MAX
  25
  26 /* CFQ specific, out here for blkcg->cfq_weight */
  27 #define CFQ_WEIGHT_MIN          10
  28 #define CFQ_WEIGHT_MAX          1000
  29 #define CFQ_WEIGHT_DEFAULT      500
  30
  31 #ifdef CONFIG_BLK_CGROUP
  32
  33 enum blkg_rwstat_type {
  34         BLKG_RWSTAT_READ,
  35         BLKG_RWSTAT_WRITE,
  36         BLKG_RWSTAT_SYNC,
  37         BLKG_RWSTAT_ASYNC,
  38
  39         BLKG_RWSTAT_NR,
  40         BLKG_RWSTAT_TOTAL = BLKG_RWSTAT_NR,
  41 };
  42
  43 struct blkcg_gq;
  44
  45 struct blkcg {
  46         struct cgroup_subsys_state      css;
  47         spinlock_t                      lock;
  48
  49         struct radix_tree_root          blkg_tree;
  50         struct blkcg_gq                 *blkg_hint;
  51         struct hlist_head               blkg_list;
  52
  53         /* TODO: per-policy storage in blkcg */
  54         unsigned int                    cfq_weight;     /* belongs to cfq */
  55         unsigned int                    cfq_leaf_weight;
  56 };
  57
  58 struct blkg_stat {
  59         struct u64_stats_sync           syncp;
  60         uint64_t                        cnt;
  61 };
  62
  63 struct blkg_rwstat {
  64         struct u64_stats_sync           syncp;
  65         uint64_t                        cnt[BLKG_RWSTAT_NR];
  66 };
  67
  68 /*
  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.
  72  *
  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.
  77  *
  78  * Such private data must embed struct blkg_policy_data (pd) at the
  79  * beginning and pd_size can't be smaller than pd.
  80  */
  81 struct blkg_policy_data {
  82         /* the blkg and policy id this per-policy data belongs to */
  83         struct blkcg_gq                 *blkg;
  84         int                             plid;
  85
  86         /* used during policy activation */
  87         struct list_head                alloc_node;
  88 };
  89
  90 /* association between a blk cgroup and a request queue */
  91 struct 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
  98         /* all non-root blkcg_gq's are guaranteed to have access to parent */
  99         struct blkcg_gq                 *parent;
 100
 101         /* request allocation list for this blkcg-q pair */
 102         struct request_list             rl;
 103
 104         /* reference count */
 105         atomic_t                        refcnt;
 106
 107         /* is this blkg online? protected by both blkcg and q locks */
 108         bool                            online;
 109
 110         struct blkg_policy_data         *pd[BLKCG_MAX_POLS];
 111
 112         struct rcu_head                 rcu_head;
 113 };
 114
 115 typedef void (blkcg_pol_init_pd_fn)(struct blkcg_gq *blkg);
 116 typedef void (blkcg_pol_online_pd_fn)(struct blkcg_gq *blkg);
 117 typedef void (blkcg_pol_offline_pd_fn)(struct blkcg_gq *blkg);
 118 typedef void (blkcg_pol_exit_pd_fn)(struct blkcg_gq *blkg);
 119 typedef void (blkcg_pol_reset_pd_stats_fn)(struct blkcg_gq *blkg);
 120
 121 struct blkcg_policy {
 122         int                             plid;
 123         /* policy specific private data size */
 124         size_t                          pd_size;
 125         /* cgroup files for the policy */
 126         struct cftype                   *cftypes;
 127
 128         /* operations */
 129         blkcg_pol_init_pd_fn            *pd_init_fn;
 130         blkcg_pol_online_pd_fn          *pd_online_fn;
 131         blkcg_pol_offline_pd_fn         *pd_offline_fn;
 132         blkcg_pol_exit_pd_fn            *pd_exit_fn;
 133         blkcg_pol_reset_pd_stats_fn     *pd_reset_stats_fn;
 134 };
 135
 136 extern struct blkcg blkcg_root;
 137
 138 struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, struct request_queue *q);
 139 struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
 140                                     struct request_queue *q);
 141 int blkcg_init_queue(struct request_queue *q);
 142 void blkcg_drain_queue(struct request_queue *q);
 143 void blkcg_exit_queue(struct request_queue *q);
 144
 145 /* Blkio controller policy registration */
 146 int blkcg_policy_register(struct blkcg_policy *pol);
 147 void blkcg_policy_unregister(struct blkcg_policy *pol);
 148 int blkcg_activate_policy(struct request_queue *q,
 149                           const struct blkcg_policy *pol);
 150 void blkcg_deactivate_policy(struct request_queue *q,
 151                              const struct blkcg_policy *pol);
 152
 153 void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg,
 154                        u64 (*prfill)(struct seq_file *,
 155                                      struct blkg_policy_data *, int),
 156                        const struct blkcg_policy *pol, int data,
 157                        bool show_total);
 158 u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v);
 159 u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
 160                          const struct blkg_rwstat *rwstat);
 161 u64 blkg_prfill_stat(struct seq_file *sf, struct blkg_policy_data *pd, int off);
 162 u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
 163                        int off);
 164
 165 u64 blkg_stat_recursive_sum(struct blkg_policy_data *pd, int off);
 166 struct blkg_rwstat blkg_rwstat_recursive_sum(struct blkg_policy_data *pd,
 167                                              int off);
 168
 169 struct blkg_conf_ctx {
 170         struct gendisk                  *disk;
 171         struct blkcg_gq                 *blkg;
 172         u64                             v;
 173 };
 174
 175 int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
 176                    const char *input, struct blkg_conf_ctx *ctx);
 177 void blkg_conf_finish(struct blkg_conf_ctx *ctx);
 178
 179
 180 static inline struct blkcg *css_to_blkcg(struct cgroup_subsys_state *css)
 181 {
 182         return css ? container_of(css, struct blkcg, css) : NULL;
 183 }
 184
 185 static inline struct blkcg *task_blkcg(struct task_struct *tsk)
 186 {
 187         return css_to_blkcg(task_css(tsk, blkio_cgrp_id));
 188 }
 189
 190 static inline struct blkcg *bio_blkcg(struct bio *bio)
 191 {
 192         if (bio && bio->bi_css)
 193                 return css_to_blkcg(bio->bi_css);
 194         return task_blkcg(current);
 195 }
 196
 197 /**
 198  * blkcg_parent - get the parent of a blkcg
 199  * @blkcg: blkcg of interest
 200  *
 201  * Return the parent blkcg of @blkcg.  Can be called anytime.
 202  */
 203 static inline struct blkcg *blkcg_parent(struct blkcg *blkcg)
 204 {
 205         return css_to_blkcg(blkcg->css.parent);
 206 }
 207
 208 /**
 209  * blkg_to_pdata - get policy private data
 210  * @blkg: blkg of interest
 211  * @pol: policy of interest
 212  *
 213  * Return pointer to private data associated with the @blkg-@pol pair.
 214  */
 215 static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
 216                                                   struct blkcg_policy *pol)
 217 {
 218         return blkg ? blkg->pd[pol->plid] : NULL;
 219 }
 220
 221 /**
 222  * pdata_to_blkg - get blkg associated with policy private data
 223  * @pd: policy private data of interest
 224  *
 225  * @pd is policy private data.  Determine the blkg it's associated with.
 226  */
 227 static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd)
 228 {
 229         return pd ? pd->blkg : NULL;
 230 }
 231
 232 /**
 233  * blkg_path - format cgroup path of blkg
 234  * @blkg: blkg of interest
 235  * @buf: target buffer
 236  * @buflen: target buffer length
 237  *
 238  * Format the path of the cgroup of @blkg into @buf.
 239  */
 240 static inline int blkg_path(struct blkcg_gq *blkg, char *buf, int buflen)
 241 {
 242         char *p;
 243
 244         p = cgroup_path(blkg->blkcg->css.cgroup, buf, buflen);
 245         if (!p) {
 246                 strncpy(buf, "<unavailable>", buflen);
 247                 return -ENAMETOOLONG;
 248         }
 249
 250         memmove(buf, p, buf + buflen - p);
 251         return 0;
 252 }
 253
 254 /**
 255  * blkg_get - get a blkg reference
 256  * @blkg: blkg to get
 257  *
 258  * The caller should be holding an existing reference.
 259  */
 260 static inline void blkg_get(struct blkcg_gq *blkg)
 261 {
 262         WARN_ON_ONCE(atomic_read(&blkg->refcnt) <= 0);
 263         atomic_inc(&blkg->refcnt);
 264 }
 265
 266 void __blkg_release_rcu(struct rcu_head *rcu);
 267
 268 /**
 269  * blkg_put - put a blkg reference
 270  * @blkg: blkg to put
 271  */
 272 static inline void blkg_put(struct blkcg_gq *blkg)
 273 {
 274         WARN_ON_ONCE(atomic_read(&blkg->refcnt) <= 0);
 275         if (atomic_dec_and_test(&blkg->refcnt))
 276                 call_rcu(&blkg->rcu_head, __blkg_release_rcu);
 277 }
 278
 279 struct blkcg_gq *__blkg_lookup(struct blkcg *blkcg, struct request_queue *q,
 280                                bool update_hint);
 281
 282 /**
 283  * blkg_for_each_descendant_pre - pre-order walk of a blkg's descendants
 284  * @d_blkg: loop cursor pointing to the current descendant
 285  * @pos_css: used for iteration
 286  * @p_blkg: target blkg to walk descendants of
 287  *
 288  * Walk @c_blkg through the descendants of @p_blkg.  Must be used with RCU
 289  * read locked.  If called under either blkcg or queue lock, the iteration
 290  * is guaranteed to include all and only online blkgs.  The caller may
 291  * update @pos_css by calling css_rightmost_descendant() to skip subtree.
 292  * @p_blkg is included in the iteration and the first node to be visited.
 293  */
 294 #define blkg_for_each_descendant_pre(d_blkg, pos_css, p_blkg)           \
 295         css_for_each_descendant_pre((pos_css), &(p_blkg)->blkcg->css)   \
 296                 if (((d_blkg) = __blkg_lookup(css_to_blkcg(pos_css),    \
 297                                               (p_blkg)->q, false)))
 298
 299 /**
 300  * blkg_for_each_descendant_post - post-order walk of a blkg's descendants
 301  * @d_blkg: loop cursor pointing to the current descendant
 302  * @pos_css: used for iteration
 303  * @p_blkg: target blkg to walk descendants of
 304  *
 305  * Similar to blkg_for_each_descendant_pre() but performs post-order
 306  * traversal instead.  Synchronization rules are the same.  @p_blkg is
 307  * included in the iteration and the last node to be visited.
 308  */
 309 #define blkg_for_each_descendant_post(d_blkg, pos_css, p_blkg)          \
 310         css_for_each_descendant_post((pos_css), &(p_blkg)->blkcg->css)  \
 311                 if (((d_blkg) = __blkg_lookup(css_to_blkcg(pos_css),    \
 312                                               (p_blkg)->q, false)))
 313
 314 /**
 315  * blk_get_rl - get request_list to use
 316  * @q: request_queue of interest
 317  * @bio: bio which will be attached to the allocated request (may be %NULL)
 318  *
 319  * The caller wants to allocate a request from @q to use for @bio.  Find
 320  * the request_list to use and obtain a reference on it.  Should be called
 321  * under queue_lock.  This function is guaranteed to return non-%NULL
 322  * request_list.
 323  */
 324 static inline struct request_list *blk_get_rl(struct request_queue *q,
 325                                               struct bio *bio)
 326 {
 327         struct blkcg *blkcg;
 328         struct blkcg_gq *blkg;
 329
 330         rcu_read_lock();
 331
 332         blkcg = bio_blkcg(bio);
 333
 334         /* bypass blkg lookup and use @q->root_rl directly for root */
 335         if (blkcg == &blkcg_root)
 336                 goto root_rl;
 337
 338         /*
 339          * Try to use blkg->rl.  blkg lookup may fail under memory pressure
 340          * or if either the blkcg or queue is going away.  Fall back to
 341          * root_rl in such cases.
 342          */
 343         blkg = blkg_lookup_create(blkcg, q);
 344         if (unlikely(IS_ERR(blkg)))
 345                 goto root_rl;
 346
 347         blkg_get(blkg);
 348         rcu_read_unlock();
 349         return &blkg->rl;
 350 root_rl:
 351         rcu_read_unlock();
 352         return &q->root_rl;
 353 }
 354
 355 /**
 356  * blk_put_rl - put request_list
 357  * @rl: request_list to put
 358  *
 359  * Put the reference acquired by blk_get_rl().  Should be called under
 360  * queue_lock.
 361  */
 362 static inline void blk_put_rl(struct request_list *rl)
 363 {
 364         /* root_rl may not have blkg set */
 365         if (rl->blkg && rl->blkg->blkcg != &blkcg_root)
 366                 blkg_put(rl->blkg);
 367 }
 368
 369 /**
 370  * blk_rq_set_rl - associate a request with a request_list
 371  * @rq: request of interest
 372  * @rl: target request_list
 373  *
 374  * Associate @rq with @rl so that accounting and freeing can know the
 375  * request_list @rq came from.
 376  */
 377 static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl)
 378 {
 379         rq->rl = rl;
 380 }
 381
 382 /**
 383  * blk_rq_rl - return the request_list a request came from
 384  * @rq: request of interest
 385  *
 386  * Return the request_list @rq is allocated from.
 387  */
 388 static inline struct request_list *blk_rq_rl(struct request *rq)
 389 {
 390         return rq->rl;
 391 }
 392
 393 struct request_list *__blk_queue_next_rl(struct request_list *rl,
 394                                          struct request_queue *q);
 395 /**
 396  * blk_queue_for_each_rl - iterate through all request_lists of a request_queue
 397  *
 398  * Should be used under queue_lock.
 399  */
 400 #define blk_queue_for_each_rl(rl, q)    \
 401         for ((rl) = &(q)->root_rl; (rl); (rl) = __blk_queue_next_rl((rl), (q)))
 402
 403 static inline void blkg_stat_init(struct blkg_stat *stat)
 404 {
 405         u64_stats_init(&stat->syncp);
 406 }
 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  */
 416 static 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  */
 430 static 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_irq(&stat->syncp);
 437                 v = stat->cnt;
 438         } while (u64_stats_fetch_retry_irq(&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  */
 447 static 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  */
 459 static 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 static inline void blkg_rwstat_init(struct blkg_rwstat *rwstat)
 465 {
 466         u64_stats_init(&rwstat->syncp);
 467 }
 468
 469 /**
 470  * blkg_rwstat_add - add a value to a blkg_rwstat
 471  * @rwstat: target blkg_rwstat
 472  * @rw: mask of REQ_{WRITE|SYNC}
 473  * @val: value to add
 474  *
 475  * Add @val to @rwstat.  The counters are chosen according to @rw.  The
 476  * caller is responsible for synchronizing calls to this function.
 477  */
 478 static inline void blkg_rwstat_add(struct blkg_rwstat *rwstat,
 479                                    int rw, uint64_t val)
 480 {
 481         u64_stats_update_begin(&rwstat->syncp);
 482
 483         if (rw & REQ_WRITE)
 484                 rwstat->cnt[BLKG_RWSTAT_WRITE] += val;
 485         else
 486                 rwstat->cnt[BLKG_RWSTAT_READ] += val;
 487         if (rw & REQ_SYNC)
 488                 rwstat->cnt[BLKG_RWSTAT_SYNC] += val;
 489         else
 490                 rwstat->cnt[BLKG_RWSTAT_ASYNC] += val;
 491
 492         u64_stats_update_end(&rwstat->syncp);
 493 }
 494
 495 /**
 496  * blkg_rwstat_read - read the current values of a blkg_rwstat
 497  * @rwstat: blkg_rwstat to read
 498  *
 499  * Read the current snapshot of @rwstat and return it as the return value.
 500  * This function can be called without synchronization and takes care of
 501  * u64 atomicity.
 502  */
 503 static inline struct blkg_rwstat blkg_rwstat_read(struct blkg_rwstat *rwstat)
 504 {
 505         unsigned int start;
 506         struct blkg_rwstat tmp;
 507
 508         do {
 509                 start = u64_stats_fetch_begin_irq(&rwstat->syncp);
 510                 tmp = *rwstat;
 511         } while (u64_stats_fetch_retry_irq(&rwstat->syncp, start));
 512
 513         return tmp;
 514 }
 515
 516 /**
 517  * blkg_rwstat_total - read the total count of a blkg_rwstat
 518  * @rwstat: blkg_rwstat to read
 519  *
 520  * Return the total count of @rwstat regardless of the IO direction.  This
 521  * function can be called without synchronization and takes care of u64
 522  * atomicity.
 523  */
 524 static inline uint64_t blkg_rwstat_total(struct blkg_rwstat *rwstat)
 525 {
 526         struct blkg_rwstat tmp = blkg_rwstat_read(rwstat);
 527
 528         return tmp.cnt[BLKG_RWSTAT_READ] + tmp.cnt[BLKG_RWSTAT_WRITE];
 529 }
 530
 531 /**
 532  * blkg_rwstat_reset - reset a blkg_rwstat
 533  * @rwstat: blkg_rwstat to reset
 534  */
 535 static inline void blkg_rwstat_reset(struct blkg_rwstat *rwstat)
 536 {
 537         memset(rwstat->cnt, 0, sizeof(rwstat->cnt));
 538 }
 539
 540 /**
 541  * blkg_rwstat_merge - merge a blkg_rwstat into another
 542  * @to: the destination blkg_rwstat
 543  * @from: the source
 544  *
 545  * Add @from's counts to @to.
 546  */
 547 static inline void blkg_rwstat_merge(struct blkg_rwstat *to,
 548                                      struct blkg_rwstat *from)
 549 {
 550         struct blkg_rwstat v = blkg_rwstat_read(from);
 551         int i;
 552
 553         u64_stats_update_begin(&to->syncp);
 554         for (i = 0; i < BLKG_RWSTAT_NR; i++)
 555                 to->cnt[i] += v.cnt[i];
 556         u64_stats_update_end(&to->syncp);
 557 }
 558
 559 #else   /* CONFIG_BLK_CGROUP */
 560
 561 struct cgroup;
 562 struct blkcg;
 563
 564 struct blkg_policy_data {
 565 };
 566
 567 struct blkcg_gq {
 568 };
 569
 570 struct blkcg_policy {
 571 };
 572
 573 static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, void *key) { return NULL; }
 574 static inline int blkcg_init_queue(struct request_queue *q) { return 0; }
 575 static inline void blkcg_drain_queue(struct request_queue *q) { }
 576 static inline void blkcg_exit_queue(struct request_queue *q) { }
 577 static inline int blkcg_policy_register(struct blkcg_policy *pol) { return 0; }
 578 static inline void blkcg_policy_unregister(struct blkcg_policy *pol) { }
 579 static inline int blkcg_activate_policy(struct request_queue *q,
 580                                         const struct blkcg_policy *pol) { return 0; }
 581 static inline void blkcg_deactivate_policy(struct request_queue *q,
 582                                            const struct blkcg_policy *pol) { }
 583
 584 static inline struct blkcg *bio_blkcg(struct bio *bio) { return NULL; }
 585
 586 static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
 587                                                   struct blkcg_policy *pol) { return NULL; }
 588 static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd) { return NULL; }
 589 static inline char *blkg_path(struct blkcg_gq *blkg) { return NULL; }
 590 static inline void blkg_get(struct blkcg_gq *blkg) { }
 591 static inline void blkg_put(struct blkcg_gq *blkg) { }
 592
 593 static inline struct request_list *blk_get_rl(struct request_queue *q,
 594                                               struct bio *bio) { return &q->root_rl; }
 595 static inline void blk_put_rl(struct request_list *rl) { }
 596 static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl) { }
 597 static inline struct request_list *blk_rq_rl(struct request *rq) { return &rq->q->root_rl; }
 598
 599 #define blk_queue_for_each_rl(rl, q)    \
 600         for ((rl) = &(q)->root_rl; (rl); (rl) = NULL)
 601
 602 #endif  /* CONFIG_BLK_CGROUP */
 603 #endif  /* _BLK_CGROUP_H */