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
  32 enum 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
  42 struct blkcg_gq;
  43
  44 struct 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
  60 struct blkg_stat {
  61         struct u64_stats_sync           syncp;
  62         uint64_t                        cnt;
  63 };
  64
  65 struct 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  */
  83 struct 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 */
  93 struct 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
 117 typedef void (blkcg_pol_init_pd_fn)(struct blkcg_gq *blkg);
 118 typedef void (blkcg_pol_online_pd_fn)(struct blkcg_gq *blkg);
 119 typedef void (blkcg_pol_offline_pd_fn)(struct blkcg_gq *blkg);
 120 typedef void (blkcg_pol_exit_pd_fn)(struct blkcg_gq *blkg);
 121 typedef void (blkcg_pol_reset_pd_stats_fn)(struct blkcg_gq *blkg);
 122
 123 struct 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
 138 extern struct blkcg blkcg_root;
 139
 140 struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, struct request_queue *q);
 141 struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
 142                                     struct request_queue *q);
 143 int blkcg_init_queue(struct request_queue *q);
 144 void blkcg_drain_queue(struct request_queue *q);
 145 void blkcg_exit_queue(struct request_queue *q);
 146
 147 /* Blkio controller policy registration */
 148 int blkcg_policy_register(struct blkcg_policy *pol);
 149 void blkcg_policy_unregister(struct blkcg_policy *pol);
 150 int blkcg_activate_policy(struct request_queue *q,
 151                           const struct blkcg_policy *pol);
 152 void blkcg_deactivate_policy(struct request_queue *q,
 153                              const struct blkcg_policy *pol);
 154
 155 void 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);
 160 u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v);
 161 u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
 162                          const struct blkg_rwstat *rwstat);
 163 u64 blkg_prfill_stat(struct seq_file *sf, struct blkg_policy_data *pd, int off);
 164 u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
 165                        int off);
 166
 167 u64 blkg_stat_recursive_sum(struct blkg_policy_data *pd, int off);
 168 struct blkg_rwstat blkg_rwstat_recursive_sum(struct blkg_policy_data *pd,
 169                                              int off);
 170
 171 struct blkg_conf_ctx {
 172         struct gendisk                  *disk;
 173         struct blkcg_gq                 *blkg;
 174         u64                             v;
 175 };
 176
 177 int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
 178                    const char *input, struct blkg_conf_ctx *ctx);
 179 void blkg_conf_finish(struct blkg_conf_ctx *ctx);
 180
 181
 182 static inline struct blkcg *css_to_blkcg(struct cgroup_subsys_state *css)
 183 {
 184         return css ? container_of(css, struct blkcg, css) : NULL;
 185 }
 186
 187 static inline struct blkcg *task_blkcg(struct task_struct *tsk)
 188 {
 189         return css_to_blkcg(task_css(tsk, blkio_subsys_id));
 190 }
 191
 192 static inline struct blkcg *bio_blkcg(struct bio *bio)
 193 {
 194         if (bio && bio->bi_css)
 195                 return css_to_blkcg(bio->bi_css);
 196         return task_blkcg(current);
 197 }
 198
 199 /**
 200  * blkcg_parent - get the parent of a blkcg
 201  * @blkcg: blkcg of interest
 202  *
 203  * Return the parent blkcg of @blkcg.  Can be called anytime.
 204  */
 205 static inline struct blkcg *blkcg_parent(struct blkcg *blkcg)
 206 {
 207         return css_to_blkcg(css_parent(&blkcg->css));
 208 }
 209
 210 /**
 211  * blkg_to_pdata - get policy private data
 212  * @blkg: blkg of interest
 213  * @pol: policy of interest
 214  *
 215  * Return pointer to private data associated with the @blkg-@pol pair.
 216  */
 217 static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
 218                                                   struct blkcg_policy *pol)
 219 {
 220         return blkg ? blkg->pd[pol->plid] : NULL;
 221 }
 222
 223 /**
 224  * pdata_to_blkg - get blkg associated with policy private data
 225  * @pd: policy private data of interest
 226  *
 227  * @pd is policy private data.  Determine the blkg it's associated with.
 228  */
 229 static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd)
 230 {
 231         return pd ? pd->blkg : NULL;
 232 }
 233
 234 /**
 235  * blkg_path - format cgroup path of blkg
 236  * @blkg: blkg of interest
 237  * @buf: target buffer
 238  * @buflen: target buffer length
 239  *
 240  * Format the path of the cgroup of @blkg into @buf.
 241  */
 242 static inline int blkg_path(struct blkcg_gq *blkg, char *buf, int buflen)
 243 {
 244         int ret;
 245
 246         ret = cgroup_path(blkg->blkcg->css.cgroup, buf, buflen);
 247         if (ret)
 248                 strncpy(buf, "<unavailable>", buflen);
 249         return ret;
 250 }
 251
 252 /**
 253  * blkg_get - get a blkg reference
 254  * @blkg: blkg to get
 255  *
 256  * The caller should be holding queue_lock and an existing reference.
 257  */
 258 static inline void blkg_get(struct blkcg_gq *blkg)
 259 {
 260         lockdep_assert_held(blkg->q->queue_lock);
 261         WARN_ON_ONCE(!blkg->refcnt);
 262         blkg->refcnt++;
 263 }
 264
 265 void __blkg_release_rcu(struct rcu_head *rcu);
 266
 267 /**
 268  * blkg_put - put a blkg reference
 269  * @blkg: blkg to put
 270  *
 271  * The caller should be holding queue_lock.
 272  */
 273 static inline void blkg_put(struct blkcg_gq *blkg)
 274 {
 275         lockdep_assert_held(blkg->q->queue_lock);
 276         WARN_ON_ONCE(blkg->refcnt <= 0);
 277         if (!--blkg->refcnt)
 278                 call_rcu(&blkg->rcu_head, __blkg_release_rcu);
 279 }
 280
 281 struct blkcg_gq *__blkg_lookup(struct blkcg *blkcg, struct request_queue *q,
 282                                bool update_hint);
 283
 284 /**
 285  * blkg_for_each_descendant_pre - pre-order walk of a blkg's descendants
 286  * @d_blkg: loop cursor pointing to the current descendant
 287  * @pos_css: used for iteration
 288  * @p_blkg: target blkg to walk descendants of
 289  *
 290  * Walk @c_blkg through the descendants of @p_blkg.  Must be used with RCU
 291  * read locked.  If called under either blkcg or queue lock, the iteration
 292  * is guaranteed to include all and only online blkgs.  The caller may
 293  * update @pos_css by calling css_rightmost_descendant() to skip subtree.
 294  * @p_blkg is included in the iteration and the first node to be visited.
 295  */
 296 #define blkg_for_each_descendant_pre(d_blkg, pos_css, p_blkg)           \
 297         css_for_each_descendant_pre((pos_css), &(p_blkg)->blkcg->css)   \
 298                 if (((d_blkg) = __blkg_lookup(css_to_blkcg(pos_css),    \
 299                                               (p_blkg)->q, false)))
 300
 301 /**
 302  * blkg_for_each_descendant_post - post-order walk of a blkg's descendants
 303  * @d_blkg: loop cursor pointing to the current descendant
 304  * @pos_css: used for iteration
 305  * @p_blkg: target blkg to walk descendants of
 306  *
 307  * Similar to blkg_for_each_descendant_pre() but performs post-order
 308  * traversal instead.  Synchronization rules are the same.  @p_blkg is
 309  * included in the iteration and the last node to be visited.
 310  */
 311 #define blkg_for_each_descendant_post(d_blkg, pos_css, p_blkg)          \
 312         css_for_each_descendant_post((pos_css), &(p_blkg)->blkcg->css)  \
 313                 if (((d_blkg) = __blkg_lookup(css_to_blkcg(pos_css),    \
 314                                               (p_blkg)->q, false)))
 315
 316 /**
 317  * blk_get_rl - get request_list to use
 318  * @q: request_queue of interest
 319  * @bio: bio which will be attached to the allocated request (may be %NULL)
 320  *
 321  * The caller wants to allocate a request from @q to use for @bio.  Find
 322  * the request_list to use and obtain a reference on it.  Should be called
 323  * under queue_lock.  This function is guaranteed to return non-%NULL
 324  * request_list.
 325  */
 326 static inline struct request_list *blk_get_rl(struct request_queue *q,
 327                                               struct bio *bio)
 328 {
 329         struct blkcg *blkcg;
 330         struct blkcg_gq *blkg;
 331
 332         rcu_read_lock();
 333
 334         blkcg = bio_blkcg(bio);
 335
 336         /* bypass blkg lookup and use @q->root_rl directly for root */
 337         if (blkcg == &blkcg_root)
 338                 goto root_rl;
 339
 340         /*
 341          * Try to use blkg->rl.  blkg lookup may fail under memory pressure
 342          * or if either the blkcg or queue is going away.  Fall back to
 343          * root_rl in such cases.
 344          */
 345         blkg = blkg_lookup_create(blkcg, q);
 346         if (unlikely(IS_ERR(blkg)))
 347                 goto root_rl;
 348
 349         blkg_get(blkg);
 350         rcu_read_unlock();
 351         return &blkg->rl;
 352 root_rl:
 353         rcu_read_unlock();
 354         return &q->root_rl;
 355 }
 356
 357 /**
 358  * blk_put_rl - put request_list
 359  * @rl: request_list to put
 360  *
 361  * Put the reference acquired by blk_get_rl().  Should be called under
 362  * queue_lock.
 363  */
 364 static inline void blk_put_rl(struct request_list *rl)
 365 {
 366         /* root_rl may not have blkg set */
 367         if (rl->blkg && rl->blkg->blkcg != &blkcg_root)
 368                 blkg_put(rl->blkg);
 369 }
 370
 371 /**
 372  * blk_rq_set_rl - associate a request with a request_list
 373  * @rq: request of interest
 374  * @rl: target request_list
 375  *
 376  * Associate @rq with @rl so that accounting and freeing can know the
 377  * request_list @rq came from.
 378  */
 379 static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl)
 380 {
 381         rq->rl = rl;
 382 }
 383
 384 /**
 385  * blk_rq_rl - return the request_list a request came from
 386  * @rq: request of interest
 387  *
 388  * Return the request_list @rq is allocated from.
 389  */
 390 static inline struct request_list *blk_rq_rl(struct request *rq)
 391 {
 392         return rq->rl;
 393 }
 394
 395 struct request_list *__blk_queue_next_rl(struct request_list *rl,
 396                                          struct request_queue *q);
 397 /**
 398  * blk_queue_for_each_rl - iterate through all request_lists of a request_queue
 399  *
 400  * Should be used under queue_lock.
 401  */
 402 #define blk_queue_for_each_rl(rl, q)    \
 403         for ((rl) = &(q)->root_rl; (rl); (rl) = __blk_queue_next_rl((rl), (q)))
 404
 405 /**
 406  * blkg_stat_add - add a value to a blkg_stat
 407  * @stat: target blkg_stat
 408  * @val: value to add
 409  *
 410  * Add @val to @stat.  The caller is responsible for synchronizing calls to
 411  * this function.
 412  */
 413 static inline void blkg_stat_add(struct blkg_stat *stat, uint64_t val)
 414 {
 415         u64_stats_update_begin(&stat->syncp);
 416         stat->cnt += val;
 417         u64_stats_update_end(&stat->syncp);
 418 }
 419
 420 /**
 421  * blkg_stat_read - read the current value of a blkg_stat
 422  * @stat: blkg_stat to read
 423  *
 424  * Read the current value of @stat.  This function can be called without
 425  * synchroniztion and takes care of u64 atomicity.
 426  */
 427 static inline uint64_t blkg_stat_read(struct blkg_stat *stat)
 428 {
 429         unsigned int start;
 430         uint64_t v;
 431
 432         do {
 433                 start = u64_stats_fetch_begin(&stat->syncp);
 434                 v = stat->cnt;
 435         } while (u64_stats_fetch_retry(&stat->syncp, start));
 436
 437         return v;
 438 }
 439
 440 /**
 441  * blkg_stat_reset - reset a blkg_stat
 442  * @stat: blkg_stat to reset
 443  */
 444 static inline void blkg_stat_reset(struct blkg_stat *stat)
 445 {
 446         stat->cnt = 0;
 447 }
 448
 449 /**
 450  * blkg_stat_merge - merge a blkg_stat into another
 451  * @to: the destination blkg_stat
 452  * @from: the source
 453  *
 454  * Add @from's count to @to.
 455  */
 456 static inline void blkg_stat_merge(struct blkg_stat *to, struct blkg_stat *from)
 457 {
 458         blkg_stat_add(to, blkg_stat_read(from));
 459 }
 460
 461 /**
 462  * blkg_rwstat_add - add a value to a blkg_rwstat
 463  * @rwstat: target blkg_rwstat
 464  * @rw: mask of REQ_{WRITE|SYNC}
 465  * @val: value to add
 466  *
 467  * Add @val to @rwstat.  The counters are chosen according to @rw.  The
 468  * caller is responsible for synchronizing calls to this function.
 469  */
 470 static inline void blkg_rwstat_add(struct blkg_rwstat *rwstat,
 471                                    int rw, uint64_t val)
 472 {
 473         u64_stats_update_begin(&rwstat->syncp);
 474
 475         if (rw & REQ_WRITE)
 476                 rwstat->cnt[BLKG_RWSTAT_WRITE] += val;
 477         else
 478                 rwstat->cnt[BLKG_RWSTAT_READ] += val;
 479         if (rw & REQ_SYNC)
 480                 rwstat->cnt[BLKG_RWSTAT_SYNC] += val;
 481         else
 482                 rwstat->cnt[BLKG_RWSTAT_ASYNC] += val;
 483
 484         u64_stats_update_end(&rwstat->syncp);
 485 }
 486
 487 /**
 488  * blkg_rwstat_read - read the current values of a blkg_rwstat
 489  * @rwstat: blkg_rwstat to read
 490  *
 491  * Read the current snapshot of @rwstat and return it as the return value.
 492  * This function can be called without synchronization and takes care of
 493  * u64 atomicity.
 494  */
 495 static inline struct blkg_rwstat blkg_rwstat_read(struct blkg_rwstat *rwstat)
 496 {
 497         unsigned int start;
 498         struct blkg_rwstat tmp;
 499
 500         do {
 501                 start = u64_stats_fetch_begin(&rwstat->syncp);
 502                 tmp = *rwstat;
 503         } while (u64_stats_fetch_retry(&rwstat->syncp, start));
 504
 505         return tmp;
 506 }
 507
 508 /**
 509  * blkg_rwstat_total - read the total count of a blkg_rwstat
 510  * @rwstat: blkg_rwstat to read
 511  *
 512  * Return the total count of @rwstat regardless of the IO direction.  This
 513  * function can be called without synchronization and takes care of u64
 514  * atomicity.
 515  */
 516 static inline uint64_t blkg_rwstat_total(struct blkg_rwstat *rwstat)
 517 {
 518         struct blkg_rwstat tmp = blkg_rwstat_read(rwstat);
 519
 520         return tmp.cnt[BLKG_RWSTAT_READ] + tmp.cnt[BLKG_RWSTAT_WRITE];
 521 }
 522
 523 /**
 524  * blkg_rwstat_reset - reset a blkg_rwstat
 525  * @rwstat: blkg_rwstat to reset
 526  */
 527 static inline void blkg_rwstat_reset(struct blkg_rwstat *rwstat)
 528 {
 529         memset(rwstat->cnt, 0, sizeof(rwstat->cnt));
 530 }
 531
 532 /**
 533  * blkg_rwstat_merge - merge a blkg_rwstat into another
 534  * @to: the destination blkg_rwstat
 535  * @from: the source
 536  *
 537  * Add @from's counts to @to.
 538  */
 539 static inline void blkg_rwstat_merge(struct blkg_rwstat *to,
 540                                      struct blkg_rwstat *from)
 541 {
 542         struct blkg_rwstat v = blkg_rwstat_read(from);
 543         int i;
 544
 545         u64_stats_update_begin(&to->syncp);
 546         for (i = 0; i < BLKG_RWSTAT_NR; i++)
 547                 to->cnt[i] += v.cnt[i];
 548         u64_stats_update_end(&to->syncp);
 549 }
 550
 551 #else   /* CONFIG_BLK_CGROUP */
 552
 553 struct cgroup;
 554 struct blkcg;
 555
 556 struct blkg_policy_data {
 557 };
 558
 559 struct blkcg_gq {
 560 };
 561
 562 struct blkcg_policy {
 563 };
 564
 565 static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, void *key) { return NULL; }
 566 static inline int blkcg_init_queue(struct request_queue *q) { return 0; }
 567 static inline void blkcg_drain_queue(struct request_queue *q) { }
 568 static inline void blkcg_exit_queue(struct request_queue *q) { }
 569 static inline int blkcg_policy_register(struct blkcg_policy *pol) { return 0; }
 570 static inline void blkcg_policy_unregister(struct blkcg_policy *pol) { }
 571 static inline int blkcg_activate_policy(struct request_queue *q,
 572                                         const struct blkcg_policy *pol) { return 0; }
 573 static inline void blkcg_deactivate_policy(struct request_queue *q,
 574                                            const struct blkcg_policy *pol) { }
 575
 576 static inline struct blkcg *bio_blkcg(struct bio *bio) { return NULL; }
 577
 578 static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
 579                                                   struct blkcg_policy *pol) { return NULL; }
 580 static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd) { return NULL; }
 581 static inline char *blkg_path(struct blkcg_gq *blkg) { return NULL; }
 582 static inline void blkg_get(struct blkcg_gq *blkg) { }
 583 static inline void blkg_put(struct blkcg_gq *blkg) { }
 584
 585 static inline struct request_list *blk_get_rl(struct request_queue *q,
 586                                               struct bio *bio) { return &q->root_rl; }
 587 static inline void blk_put_rl(struct request_list *rl) { }
 588 static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl) { }
 589 static inline struct request_list *blk_rq_rl(struct request *rq) { return &rq->q->root_rl; }
 590
 591 #define blk_queue_for_each_rl(rl, q)    \
 592         for ((rl) = &(q)->root_rl; (rl); (rl) = NULL)
 593
 594 #endif  /* CONFIG_BLK_CGROUP */
 595 #endif  /* _BLK_CGROUP_H */