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         /* for policies to test whether associated blkcg has changed */
  54         uint64_t                        id;
  55
  56         /* TODO: per-policy storage in blkcg */
  57         unsigned int                    cfq_weight;     /* belongs to cfq */
  58         unsigned int                    cfq_leaf_weight;
  59 };
  60
  61 struct blkg_stat {
  62         struct u64_stats_sync           syncp;
  63         uint64_t                        cnt;
  64 };
  65
  66 struct blkg_rwstat {
  67         struct u64_stats_sync           syncp;
  68         uint64_t                        cnt[BLKG_RWSTAT_NR];
  69 };
  70
  71 /*
  72  * A blkcg_gq (blkg) is association between a block cgroup (blkcg) and a
  73  * request_queue (q).  This is used by blkcg policies which need to track
  74  * information per blkcg - q pair.
  75  *
  76  * There can be multiple active blkcg policies and each has its private
  77  * data on each blkg, the size of which is determined by
  78  * blkcg_policy->pd_size.  blkcg core allocates and frees such areas
  79  * together with blkg and invokes pd_init/exit_fn() methods.
  80  *
  81  * Such private data must embed struct blkg_policy_data (pd) at the
  82  * beginning and pd_size can't be smaller than pd.
  83  */
  84 struct blkg_policy_data {
  85         /* the blkg and policy id this per-policy data belongs to */
  86         struct blkcg_gq                 *blkg;
  87         int                             plid;
  88
  89         /* used during policy activation */
  90         struct list_head                alloc_node;
  91 };
  92
  93 /* association between a blk cgroup and a request queue */
  94 struct blkcg_gq {
  95         /* Pointer to the associated request_queue */
  96         struct request_queue            *q;
  97         struct list_head                q_node;
  98         struct hlist_node               blkcg_node;
  99         struct blkcg                    *blkcg;
 100
 101         /* all non-root blkcg_gq's are guaranteed to have access to parent */
 102         struct blkcg_gq                 *parent;
 103
 104         /* request allocation list for this blkcg-q pair */
 105         struct request_list             rl;
 106
 107         /* reference count */
 108         atomic_t                        refcnt;
 109
 110         /* is this blkg online? protected by both blkcg and q locks */
 111         bool                            online;
 112
 113         struct blkg_policy_data         *pd[BLKCG_MAX_POLS];
 114
 115         struct rcu_head                 rcu_head;
 116 };
 117
 118 typedef void (blkcg_pol_init_pd_fn)(struct blkcg_gq *blkg);
 119 typedef void (blkcg_pol_online_pd_fn)(struct blkcg_gq *blkg);
 120 typedef void (blkcg_pol_offline_pd_fn)(struct blkcg_gq *blkg);
 121 typedef void (blkcg_pol_exit_pd_fn)(struct blkcg_gq *blkg);
 122 typedef void (blkcg_pol_reset_pd_stats_fn)(struct blkcg_gq *blkg);
 123
 124 struct blkcg_policy {
 125         int                             plid;
 126         /* policy specific private data size */
 127         size_t                          pd_size;
 128         /* cgroup files for the policy */
 129         struct cftype                   *cftypes;
 130
 131         /* operations */
 132         blkcg_pol_init_pd_fn            *pd_init_fn;
 133         blkcg_pol_online_pd_fn          *pd_online_fn;
 134         blkcg_pol_offline_pd_fn         *pd_offline_fn;
 135         blkcg_pol_exit_pd_fn            *pd_exit_fn;
 136         blkcg_pol_reset_pd_stats_fn     *pd_reset_stats_fn;
 137 };
 138
 139 extern struct blkcg blkcg_root;
 140
 141 struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, struct request_queue *q);
 142 struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
 143                                     struct request_queue *q);
 144 int blkcg_init_queue(struct request_queue *q);
 145 void blkcg_drain_queue(struct request_queue *q);
 146 void blkcg_exit_queue(struct request_queue *q);
 147
 148 /* Blkio controller policy registration */
 149 int blkcg_policy_register(struct blkcg_policy *pol);
 150 void blkcg_policy_unregister(struct blkcg_policy *pol);
 151 int blkcg_activate_policy(struct request_queue *q,
 152                           const struct blkcg_policy *pol);
 153 void blkcg_deactivate_policy(struct request_queue *q,
 154                              const struct blkcg_policy *pol);
 155
 156 void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg,
 157                        u64 (*prfill)(struct seq_file *,
 158                                      struct blkg_policy_data *, int),
 159                        const struct blkcg_policy *pol, int data,
 160                        bool show_total);
 161 u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v);
 162 u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
 163                          const struct blkg_rwstat *rwstat);
 164 u64 blkg_prfill_stat(struct seq_file *sf, struct blkg_policy_data *pd, int off);
 165 u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
 166                        int off);
 167
 168 u64 blkg_stat_recursive_sum(struct blkg_policy_data *pd, int off);
 169 struct blkg_rwstat blkg_rwstat_recursive_sum(struct blkg_policy_data *pd,
 170                                              int off);
 171
 172 struct blkg_conf_ctx {
 173         struct gendisk                  *disk;
 174         struct blkcg_gq                 *blkg;
 175         u64                             v;
 176 };
 177
 178 int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
 179                    const char *input, struct blkg_conf_ctx *ctx);
 180 void blkg_conf_finish(struct blkg_conf_ctx *ctx);
 181
 182
 183 static inline struct blkcg *css_to_blkcg(struct cgroup_subsys_state *css)
 184 {
 185         return css ? container_of(css, struct blkcg, css) : NULL;
 186 }
 187
 188 static inline struct blkcg *task_blkcg(struct task_struct *tsk)
 189 {
 190         return css_to_blkcg(task_css(tsk, blkio_cgrp_id));
 191 }
 192
 193 static inline struct blkcg *bio_blkcg(struct bio *bio)
 194 {
 195         if (bio && bio->bi_css)
 196                 return css_to_blkcg(bio->bi_css);
 197         return task_blkcg(current);
 198 }
 199
 200 /**
 201  * blkcg_parent - get the parent of a blkcg
 202  * @blkcg: blkcg of interest
 203  *
 204  * Return the parent blkcg of @blkcg.  Can be called anytime.
 205  */
 206 static inline struct blkcg *blkcg_parent(struct blkcg *blkcg)
 207 {
 208         return css_to_blkcg(blkcg->css.parent);
 209 }
 210
 211 /**
 212  * blkg_to_pdata - get policy private data
 213  * @blkg: blkg of interest
 214  * @pol: policy of interest
 215  *
 216  * Return pointer to private data associated with the @blkg-@pol pair.
 217  */
 218 static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
 219                                                   struct blkcg_policy *pol)
 220 {
 221         return blkg ? blkg->pd[pol->plid] : NULL;
 222 }
 223
 224 /**
 225  * pdata_to_blkg - get blkg associated with policy private data
 226  * @pd: policy private data of interest
 227  *
 228  * @pd is policy private data.  Determine the blkg it's associated with.
 229  */
 230 static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd)
 231 {
 232         return pd ? pd->blkg : NULL;
 233 }
 234
 235 /**
 236  * blkg_path - format cgroup path of blkg
 237  * @blkg: blkg of interest
 238  * @buf: target buffer
 239  * @buflen: target buffer length
 240  *
 241  * Format the path of the cgroup of @blkg into @buf.
 242  */
 243 static inline int blkg_path(struct blkcg_gq *blkg, char *buf, int buflen)
 244 {
 245         char *p;
 246
 247         p = cgroup_path(blkg->blkcg->css.cgroup, buf, buflen);
 248         if (!p) {
 249                 strncpy(buf, "<unavailable>", buflen);
 250                 return -ENAMETOOLONG;
 251         }
 252
 253         memmove(buf, p, buf + buflen - p);
 254         return 0;
 255 }
 256
 257 /**
 258  * blkg_get - get a blkg reference
 259  * @blkg: blkg to get
 260  *
 261  * The caller should be holding an existing reference.
 262  */
 263 static inline void blkg_get(struct blkcg_gq *blkg)
 264 {
 265         WARN_ON_ONCE(atomic_read(&blkg->refcnt) <= 0);
 266         atomic_inc(&blkg->refcnt);
 267 }
 268
 269 void __blkg_release_rcu(struct rcu_head *rcu);
 270
 271 /**
 272  * blkg_put - put a blkg reference
 273  * @blkg: blkg to put
 274  */
 275 static inline void blkg_put(struct blkcg_gq *blkg)
 276 {
 277         WARN_ON_ONCE(atomic_read(&blkg->refcnt) <= 0);
 278         if (atomic_dec_and_test(&blkg->refcnt))
 279                 call_rcu(&blkg->rcu_head, __blkg_release_rcu);
 280 }
 281
 282 struct blkcg_gq *__blkg_lookup(struct blkcg *blkcg, struct request_queue *q,
 283                                bool update_hint);
 284
 285 /**
 286  * blkg_for_each_descendant_pre - pre-order walk of a blkg's descendants
 287  * @d_blkg: loop cursor pointing to the current descendant
 288  * @pos_css: used for iteration
 289  * @p_blkg: target blkg to walk descendants of
 290  *
 291  * Walk @c_blkg through the descendants of @p_blkg.  Must be used with RCU
 292  * read locked.  If called under either blkcg or queue lock, the iteration
 293  * is guaranteed to include all and only online blkgs.  The caller may
 294  * update @pos_css by calling css_rightmost_descendant() to skip subtree.
 295  * @p_blkg is included in the iteration and the first node to be visited.
 296  */
 297 #define blkg_for_each_descendant_pre(d_blkg, pos_css, p_blkg)           \
 298         css_for_each_descendant_pre((pos_css), &(p_blkg)->blkcg->css)   \
 299                 if (((d_blkg) = __blkg_lookup(css_to_blkcg(pos_css),    \
 300                                               (p_blkg)->q, false)))
 301
 302 /**
 303  * blkg_for_each_descendant_post - post-order walk of a blkg's descendants
 304  * @d_blkg: loop cursor pointing to the current descendant
 305  * @pos_css: used for iteration
 306  * @p_blkg: target blkg to walk descendants of
 307  *
 308  * Similar to blkg_for_each_descendant_pre() but performs post-order
 309  * traversal instead.  Synchronization rules are the same.  @p_blkg is
 310  * included in the iteration and the last node to be visited.
 311  */
 312 #define blkg_for_each_descendant_post(d_blkg, pos_css, p_blkg)          \
 313         css_for_each_descendant_post((pos_css), &(p_blkg)->blkcg->css)  \
 314                 if (((d_blkg) = __blkg_lookup(css_to_blkcg(pos_css),    \
 315                                               (p_blkg)->q, false)))
 316
 317 /**
 318  * blk_get_rl - get request_list to use
 319  * @q: request_queue of interest
 320  * @bio: bio which will be attached to the allocated request (may be %NULL)
 321  *
 322  * The caller wants to allocate a request from @q to use for @bio.  Find
 323  * the request_list to use and obtain a reference on it.  Should be called
 324  * under queue_lock.  This function is guaranteed to return non-%NULL
 325  * request_list.
 326  */
 327 static inline struct request_list *blk_get_rl(struct request_queue *q,
 328                                               struct bio *bio)
 329 {
 330         struct blkcg *blkcg;
 331         struct blkcg_gq *blkg;
 332
 333         rcu_read_lock();
 334
 335         blkcg = bio_blkcg(bio);
 336
 337         /* bypass blkg lookup and use @q->root_rl directly for root */
 338         if (blkcg == &blkcg_root)
 339                 goto root_rl;
 340
 341         /*
 342          * Try to use blkg->rl.  blkg lookup may fail under memory pressure
 343          * or if either the blkcg or queue is going away.  Fall back to
 344          * root_rl in such cases.
 345          */
 346         blkg = blkg_lookup_create(blkcg, q);
 347         if (unlikely(IS_ERR(blkg)))
 348                 goto root_rl;
 349
 350         blkg_get(blkg);
 351         rcu_read_unlock();
 352         return &blkg->rl;
 353 root_rl:
 354         rcu_read_unlock();
 355         return &q->root_rl;
 356 }
 357
 358 /**
 359  * blk_put_rl - put request_list
 360  * @rl: request_list to put
 361  *
 362  * Put the reference acquired by blk_get_rl().  Should be called under
 363  * queue_lock.
 364  */
 365 static inline void blk_put_rl(struct request_list *rl)
 366 {
 367         /* root_rl may not have blkg set */
 368         if (rl->blkg && rl->blkg->blkcg != &blkcg_root)
 369                 blkg_put(rl->blkg);
 370 }
 371
 372 /**
 373  * blk_rq_set_rl - associate a request with a request_list
 374  * @rq: request of interest
 375  * @rl: target request_list
 376  *
 377  * Associate @rq with @rl so that accounting and freeing can know the
 378  * request_list @rq came from.
 379  */
 380 static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl)
 381 {
 382         rq->rl = rl;
 383 }
 384
 385 /**
 386  * blk_rq_rl - return the request_list a request came from
 387  * @rq: request of interest
 388  *
 389  * Return the request_list @rq is allocated from.
 390  */
 391 static inline struct request_list *blk_rq_rl(struct request *rq)
 392 {
 393         return rq->rl;
 394 }
 395
 396 struct request_list *__blk_queue_next_rl(struct request_list *rl,
 397                                          struct request_queue *q);
 398 /**
 399  * blk_queue_for_each_rl - iterate through all request_lists of a request_queue
 400  *
 401  * Should be used under queue_lock.
 402  */
 403 #define blk_queue_for_each_rl(rl, q)    \
 404         for ((rl) = &(q)->root_rl; (rl); (rl) = __blk_queue_next_rl((rl), (q)))
 405
 406 static inline void blkg_stat_init(struct blkg_stat *stat)
 407 {
 408         u64_stats_init(&stat->syncp);
 409 }
 410
 411 /**
 412  * blkg_stat_add - add a value to a blkg_stat
 413  * @stat: target blkg_stat
 414  * @val: value to add
 415  *
 416  * Add @val to @stat.  The caller is responsible for synchronizing calls to
 417  * this function.
 418  */
 419 static inline void blkg_stat_add(struct blkg_stat *stat, uint64_t val)
 420 {
 421         u64_stats_update_begin(&stat->syncp);
 422         stat->cnt += val;
 423         u64_stats_update_end(&stat->syncp);
 424 }
 425
 426 /**
 427  * blkg_stat_read - read the current value of a blkg_stat
 428  * @stat: blkg_stat to read
 429  *
 430  * Read the current value of @stat.  This function can be called without
 431  * synchroniztion and takes care of u64 atomicity.
 432  */
 433 static inline uint64_t blkg_stat_read(struct blkg_stat *stat)
 434 {
 435         unsigned int start;
 436         uint64_t v;
 437
 438         do {
 439                 start = u64_stats_fetch_begin_irq(&stat->syncp);
 440                 v = stat->cnt;
 441         } while (u64_stats_fetch_retry_irq(&stat->syncp, start));
 442
 443         return v;
 444 }
 445
 446 /**
 447  * blkg_stat_reset - reset a blkg_stat
 448  * @stat: blkg_stat to reset
 449  */
 450 static inline void blkg_stat_reset(struct blkg_stat *stat)
 451 {
 452         stat->cnt = 0;
 453 }
 454
 455 /**
 456  * blkg_stat_merge - merge a blkg_stat into another
 457  * @to: the destination blkg_stat
 458  * @from: the source
 459  *
 460  * Add @from's count to @to.
 461  */
 462 static inline void blkg_stat_merge(struct blkg_stat *to, struct blkg_stat *from)
 463 {
 464         blkg_stat_add(to, blkg_stat_read(from));
 465 }
 466
 467 static inline void blkg_rwstat_init(struct blkg_rwstat *rwstat)
 468 {
 469         u64_stats_init(&rwstat->syncp);
 470 }
 471
 472 /**
 473  * blkg_rwstat_add - add a value to a blkg_rwstat
 474  * @rwstat: target blkg_rwstat
 475  * @rw: mask of REQ_{WRITE|SYNC}
 476  * @val: value to add
 477  *
 478  * Add @val to @rwstat.  The counters are chosen according to @rw.  The
 479  * caller is responsible for synchronizing calls to this function.
 480  */
 481 static inline void blkg_rwstat_add(struct blkg_rwstat *rwstat,
 482                                    int rw, uint64_t val)
 483 {
 484         u64_stats_update_begin(&rwstat->syncp);
 485
 486         if (rw & REQ_WRITE)
 487                 rwstat->cnt[BLKG_RWSTAT_WRITE] += val;
 488         else
 489                 rwstat->cnt[BLKG_RWSTAT_READ] += val;
 490         if (rw & REQ_SYNC)
 491                 rwstat->cnt[BLKG_RWSTAT_SYNC] += val;
 492         else
 493                 rwstat->cnt[BLKG_RWSTAT_ASYNC] += val;
 494
 495         u64_stats_update_end(&rwstat->syncp);
 496 }
 497
 498 /**
 499  * blkg_rwstat_read - read the current values of a blkg_rwstat
 500  * @rwstat: blkg_rwstat to read
 501  *
 502  * Read the current snapshot of @rwstat and return it as the return value.
 503  * This function can be called without synchronization and takes care of
 504  * u64 atomicity.
 505  */
 506 static inline struct blkg_rwstat blkg_rwstat_read(struct blkg_rwstat *rwstat)
 507 {
 508         unsigned int start;
 509         struct blkg_rwstat tmp;
 510
 511         do {
 512                 start = u64_stats_fetch_begin_irq(&rwstat->syncp);
 513                 tmp = *rwstat;
 514         } while (u64_stats_fetch_retry_irq(&rwstat->syncp, start));
 515
 516         return tmp;
 517 }
 518
 519 /**
 520  * blkg_rwstat_total - read the total count of a blkg_rwstat
 521  * @rwstat: blkg_rwstat to read
 522  *
 523  * Return the total count of @rwstat regardless of the IO direction.  This
 524  * function can be called without synchronization and takes care of u64
 525  * atomicity.
 526  */
 527 static inline uint64_t blkg_rwstat_total(struct blkg_rwstat *rwstat)
 528 {
 529         struct blkg_rwstat tmp = blkg_rwstat_read(rwstat);
 530
 531         return tmp.cnt[BLKG_RWSTAT_READ] + tmp.cnt[BLKG_RWSTAT_WRITE];
 532 }
 533
 534 /**
 535  * blkg_rwstat_reset - reset a blkg_rwstat
 536  * @rwstat: blkg_rwstat to reset
 537  */
 538 static inline void blkg_rwstat_reset(struct blkg_rwstat *rwstat)
 539 {
 540         memset(rwstat->cnt, 0, sizeof(rwstat->cnt));
 541 }
 542
 543 /**
 544  * blkg_rwstat_merge - merge a blkg_rwstat into another
 545  * @to: the destination blkg_rwstat
 546  * @from: the source
 547  *
 548  * Add @from's counts to @to.
 549  */
 550 static inline void blkg_rwstat_merge(struct blkg_rwstat *to,
 551                                      struct blkg_rwstat *from)
 552 {
 553         struct blkg_rwstat v = blkg_rwstat_read(from);
 554         int i;
 555
 556         u64_stats_update_begin(&to->syncp);
 557         for (i = 0; i < BLKG_RWSTAT_NR; i++)
 558                 to->cnt[i] += v.cnt[i];
 559         u64_stats_update_end(&to->syncp);
 560 }
 561
 562 #else   /* CONFIG_BLK_CGROUP */
 563
 564 struct cgroup;
 565 struct blkcg;
 566
 567 struct blkg_policy_data {
 568 };
 569
 570 struct blkcg_gq {
 571 };
 572
 573 struct blkcg_policy {
 574 };
 575
 576 static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, void *key) { return NULL; }
 577 static inline int blkcg_init_queue(struct request_queue *q) { return 0; }
 578 static inline void blkcg_drain_queue(struct request_queue *q) { }
 579 static inline void blkcg_exit_queue(struct request_queue *q) { }
 580 static inline int blkcg_policy_register(struct blkcg_policy *pol) { return 0; }
 581 static inline void blkcg_policy_unregister(struct blkcg_policy *pol) { }
 582 static inline int blkcg_activate_policy(struct request_queue *q,
 583                                         const struct blkcg_policy *pol) { return 0; }
 584 static inline void blkcg_deactivate_policy(struct request_queue *q,
 585                                            const struct blkcg_policy *pol) { }
 586
 587 static inline struct blkcg *bio_blkcg(struct bio *bio) { return NULL; }
 588
 589 static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
 590                                                   struct blkcg_policy *pol) { return NULL; }
 591 static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd) { return NULL; }
 592 static inline char *blkg_path(struct blkcg_gq *blkg) { return NULL; }
 593 static inline void blkg_get(struct blkcg_gq *blkg) { }
 594 static inline void blkg_put(struct blkcg_gq *blkg) { }
 595
 596 static inline struct request_list *blk_get_rl(struct request_queue *q,
 597                                               struct bio *bio) { return &q->root_rl; }
 598 static inline void blk_put_rl(struct request_list *rl) { }
 599 static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl) { }
 600 static inline struct request_list *blk_rq_rl(struct request *rq) { return &rq->q->root_rl; }
 601
 602 #define blk_queue_for_each_rl(rl, q)    \
 603         for ((rl) = &(q)->root_rl; (rl); (rl) = NULL)
 604
 605 #endif  /* CONFIG_BLK_CGROUP */
 606 #endif  /* _BLK_CGROUP_H */