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         struct blkg_policy_data         *pd[BLKCG_MAX_POLS];
 110
 111         struct rcu_head                 rcu_head;
 112 };
 113
 114 typedef void (blkcg_pol_init_pd_fn)(struct blkcg_gq *blkg);
 115 typedef void (blkcg_pol_exit_pd_fn)(struct blkcg_gq *blkg);
 116 typedef void (blkcg_pol_reset_pd_stats_fn)(struct blkcg_gq *blkg);
 117
 118 struct blkcg_policy {
 119         int                             plid;
 120         /* policy specific private data size */
 121         size_t                          pd_size;
 122         /* cgroup files for the policy */
 123         struct cftype                   *cftypes;
 124
 125         /* operations */
 126         blkcg_pol_init_pd_fn            *pd_init_fn;
 127         blkcg_pol_exit_pd_fn            *pd_exit_fn;
 128         blkcg_pol_reset_pd_stats_fn     *pd_reset_stats_fn;
 129 };
 130
 131 extern struct blkcg blkcg_root;
 132
 133 struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, struct request_queue *q);
 134 struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
 135                                     struct request_queue *q);
 136 int blkcg_init_queue(struct request_queue *q);
 137 void blkcg_drain_queue(struct request_queue *q);
 138 void blkcg_exit_queue(struct request_queue *q);
 139
 140 /* Blkio controller policy registration */
 141 int blkcg_policy_register(struct blkcg_policy *pol);
 142 void blkcg_policy_unregister(struct blkcg_policy *pol);
 143 int blkcg_activate_policy(struct request_queue *q,
 144                           const struct blkcg_policy *pol);
 145 void blkcg_deactivate_policy(struct request_queue *q,
 146                              const struct blkcg_policy *pol);
 147
 148 void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg,
 149                        u64 (*prfill)(struct seq_file *,
 150                                      struct blkg_policy_data *, int),
 151                        const struct blkcg_policy *pol, int data,
 152                        bool show_total);
 153 u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v);
 154 u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
 155                          const struct blkg_rwstat *rwstat);
 156 u64 blkg_prfill_stat(struct seq_file *sf, struct blkg_policy_data *pd, int off);
 157 u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
 158                        int off);
 159
 160 struct blkg_conf_ctx {
 161         struct gendisk                  *disk;
 162         struct blkcg_gq                 *blkg;
 163         u64                             v;
 164 };
 165
 166 int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
 167                    const char *input, struct blkg_conf_ctx *ctx);
 168 void blkg_conf_finish(struct blkg_conf_ctx *ctx);
 169
 170
 171 static inline struct blkcg *cgroup_to_blkcg(struct cgroup *cgroup)
 172 {
 173         return container_of(cgroup_subsys_state(cgroup, blkio_subsys_id),
 174                             struct blkcg, css);
 175 }
 176
 177 static inline struct blkcg *task_blkcg(struct task_struct *tsk)
 178 {
 179         return container_of(task_subsys_state(tsk, blkio_subsys_id),
 180                             struct blkcg, css);
 181 }
 182
 183 static inline struct blkcg *bio_blkcg(struct bio *bio)
 184 {
 185         if (bio && bio->bi_css)
 186                 return container_of(bio->bi_css, struct blkcg, css);
 187         return task_blkcg(current);
 188 }
 189
 190 /**
 191  * blkcg_parent - get the parent of a blkcg
 192  * @blkcg: blkcg of interest
 193  *
 194  * Return the parent blkcg of @blkcg.  Can be called anytime.
 195  */
 196 static inline struct blkcg *blkcg_parent(struct blkcg *blkcg)
 197 {
 198         struct cgroup *pcg = blkcg->css.cgroup->parent;
 199
 200         return pcg ? cgroup_to_blkcg(pcg) : NULL;
 201 }
 202
 203 /**
 204  * blkg_to_pdata - get policy private data
 205  * @blkg: blkg of interest
 206  * @pol: policy of interest
 207  *
 208  * Return pointer to private data associated with the @blkg-@pol pair.
 209  */
 210 static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
 211                                                   struct blkcg_policy *pol)
 212 {
 213         return blkg ? blkg->pd[pol->plid] : NULL;
 214 }
 215
 216 /**
 217  * pdata_to_blkg - get blkg associated with policy private data
 218  * @pd: policy private data of interest
 219  *
 220  * @pd is policy private data.  Determine the blkg it's associated with.
 221  */
 222 static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd)
 223 {
 224         return pd ? pd->blkg : NULL;
 225 }
 226
 227 /**
 228  * blkg_path - format cgroup path of blkg
 229  * @blkg: blkg of interest
 230  * @buf: target buffer
 231  * @buflen: target buffer length
 232  *
 233  * Format the path of the cgroup of @blkg into @buf.
 234  */
 235 static inline int blkg_path(struct blkcg_gq *blkg, char *buf, int buflen)
 236 {
 237         int ret;
 238
 239         rcu_read_lock();
 240         ret = cgroup_path(blkg->blkcg->css.cgroup, buf, buflen);
 241         rcu_read_unlock();
 242         if (ret)
 243                 strncpy(buf, "<unavailable>", buflen);
 244         return ret;
 245 }
 246
 247 /**
 248  * blkg_get - get a blkg reference
 249  * @blkg: blkg to get
 250  *
 251  * The caller should be holding queue_lock and an existing reference.
 252  */
 253 static inline void blkg_get(struct blkcg_gq *blkg)
 254 {
 255         lockdep_assert_held(blkg->q->queue_lock);
 256         WARN_ON_ONCE(!blkg->refcnt);
 257         blkg->refcnt++;
 258 }
 259
 260 void __blkg_release(struct blkcg_gq *blkg);
 261
 262 /**
 263  * blkg_put - put a blkg reference
 264  * @blkg: blkg to put
 265  *
 266  * The caller should be holding queue_lock.
 267  */
 268 static inline void blkg_put(struct blkcg_gq *blkg)
 269 {
 270         lockdep_assert_held(blkg->q->queue_lock);
 271         WARN_ON_ONCE(blkg->refcnt <= 0);
 272         if (!--blkg->refcnt)
 273                 __blkg_release(blkg);
 274 }
 275
 276 /**
 277  * blk_get_rl - get request_list to use
 278  * @q: request_queue of interest
 279  * @bio: bio which will be attached to the allocated request (may be %NULL)
 280  *
 281  * The caller wants to allocate a request from @q to use for @bio.  Find
 282  * the request_list to use and obtain a reference on it.  Should be called
 283  * under queue_lock.  This function is guaranteed to return non-%NULL
 284  * request_list.
 285  */
 286 static inline struct request_list *blk_get_rl(struct request_queue *q,
 287                                               struct bio *bio)
 288 {
 289         struct blkcg *blkcg;
 290         struct blkcg_gq *blkg;
 291
 292         rcu_read_lock();
 293
 294         blkcg = bio_blkcg(bio);
 295
 296         /* bypass blkg lookup and use @q->root_rl directly for root */
 297         if (blkcg == &blkcg_root)
 298                 goto root_rl;
 299
 300         /*
 301          * Try to use blkg->rl.  blkg lookup may fail under memory pressure
 302          * or if either the blkcg or queue is going away.  Fall back to
 303          * root_rl in such cases.
 304          */
 305         blkg = blkg_lookup_create(blkcg, q);
 306         if (unlikely(IS_ERR(blkg)))
 307                 goto root_rl;
 308
 309         blkg_get(blkg);
 310         rcu_read_unlock();
 311         return &blkg->rl;
 312 root_rl:
 313         rcu_read_unlock();
 314         return &q->root_rl;
 315 }
 316
 317 /**
 318  * blk_put_rl - put request_list
 319  * @rl: request_list to put
 320  *
 321  * Put the reference acquired by blk_get_rl().  Should be called under
 322  * queue_lock.
 323  */
 324 static inline void blk_put_rl(struct request_list *rl)
 325 {
 326         /* root_rl may not have blkg set */
 327         if (rl->blkg && rl->blkg->blkcg != &blkcg_root)
 328                 blkg_put(rl->blkg);
 329 }
 330
 331 /**
 332  * blk_rq_set_rl - associate a request with a request_list
 333  * @rq: request of interest
 334  * @rl: target request_list
 335  *
 336  * Associate @rq with @rl so that accounting and freeing can know the
 337  * request_list @rq came from.
 338  */
 339 static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl)
 340 {
 341         rq->rl = rl;
 342 }
 343
 344 /**
 345  * blk_rq_rl - return the request_list a request came from
 346  * @rq: request of interest
 347  *
 348  * Return the request_list @rq is allocated from.
 349  */
 350 static inline struct request_list *blk_rq_rl(struct request *rq)
 351 {
 352         return rq->rl;
 353 }
 354
 355 struct request_list *__blk_queue_next_rl(struct request_list *rl,
 356                                          struct request_queue *q);
 357 /**
 358  * blk_queue_for_each_rl - iterate through all request_lists of a request_queue
 359  *
 360  * Should be used under queue_lock.
 361  */
 362 #define blk_queue_for_each_rl(rl, q)    \
 363         for ((rl) = &(q)->root_rl; (rl); (rl) = __blk_queue_next_rl((rl), (q)))
 364
 365 /**
 366  * blkg_stat_add - add a value to a blkg_stat
 367  * @stat: target blkg_stat
 368  * @val: value to add
 369  *
 370  * Add @val to @stat.  The caller is responsible for synchronizing calls to
 371  * this function.
 372  */
 373 static inline void blkg_stat_add(struct blkg_stat *stat, uint64_t val)
 374 {
 375         u64_stats_update_begin(&stat->syncp);
 376         stat->cnt += val;
 377         u64_stats_update_end(&stat->syncp);
 378 }
 379
 380 /**
 381  * blkg_stat_read - read the current value of a blkg_stat
 382  * @stat: blkg_stat to read
 383  *
 384  * Read the current value of @stat.  This function can be called without
 385  * synchroniztion and takes care of u64 atomicity.
 386  */
 387 static inline uint64_t blkg_stat_read(struct blkg_stat *stat)
 388 {
 389         unsigned int start;
 390         uint64_t v;
 391
 392         do {
 393                 start = u64_stats_fetch_begin(&stat->syncp);
 394                 v = stat->cnt;
 395         } while (u64_stats_fetch_retry(&stat->syncp, start));
 396
 397         return v;
 398 }
 399
 400 /**
 401  * blkg_stat_reset - reset a blkg_stat
 402  * @stat: blkg_stat to reset
 403  */
 404 static inline void blkg_stat_reset(struct blkg_stat *stat)
 405 {
 406         stat->cnt = 0;
 407 }
 408
 409 /**
 410  * blkg_rwstat_add - add a value to a blkg_rwstat
 411  * @rwstat: target blkg_rwstat
 412  * @rw: mask of REQ_{WRITE|SYNC}
 413  * @val: value to add
 414  *
 415  * Add @val to @rwstat.  The counters are chosen according to @rw.  The
 416  * caller is responsible for synchronizing calls to this function.
 417  */
 418 static inline void blkg_rwstat_add(struct blkg_rwstat *rwstat,
 419                                    int rw, uint64_t val)
 420 {
 421         u64_stats_update_begin(&rwstat->syncp);
 422
 423         if (rw & REQ_WRITE)
 424                 rwstat->cnt[BLKG_RWSTAT_WRITE] += val;
 425         else
 426                 rwstat->cnt[BLKG_RWSTAT_READ] += val;
 427         if (rw & REQ_SYNC)
 428                 rwstat->cnt[BLKG_RWSTAT_SYNC] += val;
 429         else
 430                 rwstat->cnt[BLKG_RWSTAT_ASYNC] += val;
 431
 432         u64_stats_update_end(&rwstat->syncp);
 433 }
 434
 435 /**
 436  * blkg_rwstat_read - read the current values of a blkg_rwstat
 437  * @rwstat: blkg_rwstat to read
 438  *
 439  * Read the current snapshot of @rwstat and return it as the return value.
 440  * This function can be called without synchronization and takes care of
 441  * u64 atomicity.
 442  */
 443 static inline struct blkg_rwstat blkg_rwstat_read(struct blkg_rwstat *rwstat)
 444 {
 445         unsigned int start;
 446         struct blkg_rwstat tmp;
 447
 448         do {
 449                 start = u64_stats_fetch_begin(&rwstat->syncp);
 450                 tmp = *rwstat;
 451         } while (u64_stats_fetch_retry(&rwstat->syncp, start));
 452
 453         return tmp;
 454 }
 455
 456 /**
 457  * blkg_rwstat_sum - read the total count of a blkg_rwstat
 458  * @rwstat: blkg_rwstat to read
 459  *
 460  * Return the total count of @rwstat regardless of the IO direction.  This
 461  * function can be called without synchronization and takes care of u64
 462  * atomicity.
 463  */
 464 static inline uint64_t blkg_rwstat_sum(struct blkg_rwstat *rwstat)
 465 {
 466         struct blkg_rwstat tmp = blkg_rwstat_read(rwstat);
 467
 468         return tmp.cnt[BLKG_RWSTAT_READ] + tmp.cnt[BLKG_RWSTAT_WRITE];
 469 }
 470
 471 /**
 472  * blkg_rwstat_reset - reset a blkg_rwstat
 473  * @rwstat: blkg_rwstat to reset
 474  */
 475 static inline void blkg_rwstat_reset(struct blkg_rwstat *rwstat)
 476 {
 477         memset(rwstat->cnt, 0, sizeof(rwstat->cnt));
 478 }
 479
 480 #else   /* CONFIG_BLK_CGROUP */
 481
 482 struct cgroup;
 483 struct blkcg;
 484
 485 struct blkg_policy_data {
 486 };
 487
 488 struct blkcg_gq {
 489 };
 490
 491 struct blkcg_policy {
 492 };
 493
 494 static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, void *key) { return NULL; }
 495 static inline int blkcg_init_queue(struct request_queue *q) { return 0; }
 496 static inline void blkcg_drain_queue(struct request_queue *q) { }
 497 static inline void blkcg_exit_queue(struct request_queue *q) { }
 498 static inline int blkcg_policy_register(struct blkcg_policy *pol) { return 0; }
 499 static inline void blkcg_policy_unregister(struct blkcg_policy *pol) { }
 500 static inline int blkcg_activate_policy(struct request_queue *q,
 501                                         const struct blkcg_policy *pol) { return 0; }
 502 static inline void blkcg_deactivate_policy(struct request_queue *q,
 503                                            const struct blkcg_policy *pol) { }
 504
 505 static inline struct blkcg *cgroup_to_blkcg(struct cgroup *cgroup) { return NULL; }
 506 static inline struct blkcg *bio_blkcg(struct bio *bio) { return NULL; }
 507
 508 static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
 509                                                   struct blkcg_policy *pol) { return NULL; }
 510 static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd) { return NULL; }
 511 static inline char *blkg_path(struct blkcg_gq *blkg) { return NULL; }
 512 static inline void blkg_get(struct blkcg_gq *blkg) { }
 513 static inline void blkg_put(struct blkcg_gq *blkg) { }
 514
 515 static inline struct request_list *blk_get_rl(struct request_queue *q,
 516                                               struct bio *bio) { return &q->root_rl; }
 517 static inline void blk_put_rl(struct request_list *rl) { }
 518 static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl) { }
 519 static inline struct request_list *blk_rq_rl(struct request *rq) { return &rq->q->root_rl; }
 520
 521 #define blk_queue_for_each_rl(rl, q)    \
 522         for ((rl) = &(q)->root_rl; (rl); (rl) = NULL)
 523
 524 #endif  /* CONFIG_BLK_CGROUP */
 525 #endif  /* _BLK_CGROUP_H */