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 this per-policy data belongs to */
  85         struct blkcg_gq                 *blkg;
  86
  87         /* used during policy activation */
  88         struct list_head                alloc_node;
  89 };
  90
  91 /* association between a blk cgroup and a request queue */
  92 struct blkcg_gq {
  93         /* Pointer to the associated request_queue */
  94         struct request_queue            *q;
  95         struct list_head                q_node;
  96         struct hlist_node               blkcg_node;
  97         struct blkcg                    *blkcg;
  98
  99         /* all non-root blkcg_gq's are guaranteed to have access to parent */
 100         struct blkcg_gq                 *parent;
 101
 102         /* request allocation list for this blkcg-q pair */
 103         struct request_list             rl;
 104
 105         /* reference count */
 106         int                             refcnt;
 107
 108         struct blkg_policy_data         *pd[BLKCG_MAX_POLS];
 109
 110         struct rcu_head                 rcu_head;
 111 };
 112
 113 typedef void (blkcg_pol_init_pd_fn)(struct blkcg_gq *blkg);
 114 typedef void (blkcg_pol_exit_pd_fn)(struct blkcg_gq *blkg);
 115 typedef void (blkcg_pol_reset_pd_stats_fn)(struct blkcg_gq *blkg);
 116
 117 struct blkcg_policy {
 118         int                             plid;
 119         /* policy specific private data size */
 120         size_t                          pd_size;
 121         /* cgroup files for the policy */
 122         struct cftype                   *cftypes;
 123
 124         /* operations */
 125         blkcg_pol_init_pd_fn            *pd_init_fn;
 126         blkcg_pol_exit_pd_fn            *pd_exit_fn;
 127         blkcg_pol_reset_pd_stats_fn     *pd_reset_stats_fn;
 128 };
 129
 130 extern struct blkcg blkcg_root;
 131
 132 struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, struct request_queue *q);
 133 struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
 134                                     struct request_queue *q);
 135 int blkcg_init_queue(struct request_queue *q);
 136 void blkcg_drain_queue(struct request_queue *q);
 137 void blkcg_exit_queue(struct request_queue *q);
 138
 139 /* Blkio controller policy registration */
 140 int blkcg_policy_register(struct blkcg_policy *pol);
 141 void blkcg_policy_unregister(struct blkcg_policy *pol);
 142 int blkcg_activate_policy(struct request_queue *q,
 143                           const struct blkcg_policy *pol);
 144 void blkcg_deactivate_policy(struct request_queue *q,
 145                              const struct blkcg_policy *pol);
 146
 147 void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg,
 148                        u64 (*prfill)(struct seq_file *,
 149                                      struct blkg_policy_data *, int),
 150                        const struct blkcg_policy *pol, int data,
 151                        bool show_total);
 152 u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v);
 153 u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
 154                          const struct blkg_rwstat *rwstat);
 155 u64 blkg_prfill_stat(struct seq_file *sf, struct blkg_policy_data *pd, int off);
 156 u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
 157                        int off);
 158
 159 struct blkg_conf_ctx {
 160         struct gendisk                  *disk;
 161         struct blkcg_gq                 *blkg;
 162         u64                             v;
 163 };
 164
 165 int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
 166                    const char *input, struct blkg_conf_ctx *ctx);
 167 void blkg_conf_finish(struct blkg_conf_ctx *ctx);
 168
 169
 170 static inline struct blkcg *cgroup_to_blkcg(struct cgroup *cgroup)
 171 {
 172         return container_of(cgroup_subsys_state(cgroup, blkio_subsys_id),
 173                             struct blkcg, css);
 174 }
 175
 176 static inline struct blkcg *task_blkcg(struct task_struct *tsk)
 177 {
 178         return container_of(task_subsys_state(tsk, blkio_subsys_id),
 179                             struct blkcg, css);
 180 }
 181
 182 static inline struct blkcg *bio_blkcg(struct bio *bio)
 183 {
 184         if (bio && bio->bi_css)
 185                 return container_of(bio->bi_css, struct blkcg, css);
 186         return task_blkcg(current);
 187 }
 188
 189 /**
 190  * blkcg_parent - get the parent of a blkcg
 191  * @blkcg: blkcg of interest
 192  *
 193  * Return the parent blkcg of @blkcg.  Can be called anytime.
 194  */
 195 static inline struct blkcg *blkcg_parent(struct blkcg *blkcg)
 196 {
 197         struct cgroup *pcg = blkcg->css.cgroup->parent;
 198
 199         return pcg ? cgroup_to_blkcg(pcg) : NULL;
 200 }
 201
 202 /**
 203  * blkg_to_pdata - get policy private data
 204  * @blkg: blkg of interest
 205  * @pol: policy of interest
 206  *
 207  * Return pointer to private data associated with the @blkg-@pol pair.
 208  */
 209 static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
 210                                                   struct blkcg_policy *pol)
 211 {
 212         return blkg ? blkg->pd[pol->plid] : NULL;
 213 }
 214
 215 /**
 216  * pdata_to_blkg - get blkg associated with policy private data
 217  * @pd: policy private data of interest
 218  *
 219  * @pd is policy private data.  Determine the blkg it's associated with.
 220  */
 221 static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd)
 222 {
 223         return pd ? pd->blkg : NULL;
 224 }
 225
 226 /**
 227  * blkg_path - format cgroup path of blkg
 228  * @blkg: blkg of interest
 229  * @buf: target buffer
 230  * @buflen: target buffer length
 231  *
 232  * Format the path of the cgroup of @blkg into @buf.
 233  */
 234 static inline int blkg_path(struct blkcg_gq *blkg, char *buf, int buflen)
 235 {
 236         int ret;
 237
 238         rcu_read_lock();
 239         ret = cgroup_path(blkg->blkcg->css.cgroup, buf, buflen);
 240         rcu_read_unlock();
 241         if (ret)
 242                 strncpy(buf, "<unavailable>", buflen);
 243         return ret;
 244 }
 245
 246 /**
 247  * blkg_get - get a blkg reference
 248  * @blkg: blkg to get
 249  *
 250  * The caller should be holding queue_lock and an existing reference.
 251  */
 252 static inline void blkg_get(struct blkcg_gq *blkg)
 253 {
 254         lockdep_assert_held(blkg->q->queue_lock);
 255         WARN_ON_ONCE(!blkg->refcnt);
 256         blkg->refcnt++;
 257 }
 258
 259 void __blkg_release(struct blkcg_gq *blkg);
 260
 261 /**
 262  * blkg_put - put a blkg reference
 263  * @blkg: blkg to put
 264  *
 265  * The caller should be holding queue_lock.
 266  */
 267 static inline void blkg_put(struct blkcg_gq *blkg)
 268 {
 269         lockdep_assert_held(blkg->q->queue_lock);
 270         WARN_ON_ONCE(blkg->refcnt <= 0);
 271         if (!--blkg->refcnt)
 272                 __blkg_release(blkg);
 273 }
 274
 275 /**
 276  * blk_get_rl - get request_list to use
 277  * @q: request_queue of interest
 278  * @bio: bio which will be attached to the allocated request (may be %NULL)
 279  *
 280  * The caller wants to allocate a request from @q to use for @bio.  Find
 281  * the request_list to use and obtain a reference on it.  Should be called
 282  * under queue_lock.  This function is guaranteed to return non-%NULL
 283  * request_list.
 284  */
 285 static inline struct request_list *blk_get_rl(struct request_queue *q,
 286                                               struct bio *bio)
 287 {
 288         struct blkcg *blkcg;
 289         struct blkcg_gq *blkg;
 290
 291         rcu_read_lock();
 292
 293         blkcg = bio_blkcg(bio);
 294
 295         /* bypass blkg lookup and use @q->root_rl directly for root */
 296         if (blkcg == &blkcg_root)
 297                 goto root_rl;
 298
 299         /*
 300          * Try to use blkg->rl.  blkg lookup may fail under memory pressure
 301          * or if either the blkcg or queue is going away.  Fall back to
 302          * root_rl in such cases.
 303          */
 304         blkg = blkg_lookup_create(blkcg, q);
 305         if (unlikely(IS_ERR(blkg)))
 306                 goto root_rl;
 307
 308         blkg_get(blkg);
 309         rcu_read_unlock();
 310         return &blkg->rl;
 311 root_rl:
 312         rcu_read_unlock();
 313         return &q->root_rl;
 314 }
 315
 316 /**
 317  * blk_put_rl - put request_list
 318  * @rl: request_list to put
 319  *
 320  * Put the reference acquired by blk_get_rl().  Should be called under
 321  * queue_lock.
 322  */
 323 static inline void blk_put_rl(struct request_list *rl)
 324 {
 325         /* root_rl may not have blkg set */
 326         if (rl->blkg && rl->blkg->blkcg != &blkcg_root)
 327                 blkg_put(rl->blkg);
 328 }
 329
 330 /**
 331  * blk_rq_set_rl - associate a request with a request_list
 332  * @rq: request of interest
 333  * @rl: target request_list
 334  *
 335  * Associate @rq with @rl so that accounting and freeing can know the
 336  * request_list @rq came from.
 337  */
 338 static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl)
 339 {
 340         rq->rl = rl;
 341 }
 342
 343 /**
 344  * blk_rq_rl - return the request_list a request came from
 345  * @rq: request of interest
 346  *
 347  * Return the request_list @rq is allocated from.
 348  */
 349 static inline struct request_list *blk_rq_rl(struct request *rq)
 350 {
 351         return rq->rl;
 352 }
 353
 354 struct request_list *__blk_queue_next_rl(struct request_list *rl,
 355                                          struct request_queue *q);
 356 /**
 357  * blk_queue_for_each_rl - iterate through all request_lists of a request_queue
 358  *
 359  * Should be used under queue_lock.
 360  */
 361 #define blk_queue_for_each_rl(rl, q)    \
 362         for ((rl) = &(q)->root_rl; (rl); (rl) = __blk_queue_next_rl((rl), (q)))
 363
 364 /**
 365  * blkg_stat_add - add a value to a blkg_stat
 366  * @stat: target blkg_stat
 367  * @val: value to add
 368  *
 369  * Add @val to @stat.  The caller is responsible for synchronizing calls to
 370  * this function.
 371  */
 372 static inline void blkg_stat_add(struct blkg_stat *stat, uint64_t val)
 373 {
 374         u64_stats_update_begin(&stat->syncp);
 375         stat->cnt += val;
 376         u64_stats_update_end(&stat->syncp);
 377 }
 378
 379 /**
 380  * blkg_stat_read - read the current value of a blkg_stat
 381  * @stat: blkg_stat to read
 382  *
 383  * Read the current value of @stat.  This function can be called without
 384  * synchroniztion and takes care of u64 atomicity.
 385  */
 386 static inline uint64_t blkg_stat_read(struct blkg_stat *stat)
 387 {
 388         unsigned int start;
 389         uint64_t v;
 390
 391         do {
 392                 start = u64_stats_fetch_begin(&stat->syncp);
 393                 v = stat->cnt;
 394         } while (u64_stats_fetch_retry(&stat->syncp, start));
 395
 396         return v;
 397 }
 398
 399 /**
 400  * blkg_stat_reset - reset a blkg_stat
 401  * @stat: blkg_stat to reset
 402  */
 403 static inline void blkg_stat_reset(struct blkg_stat *stat)
 404 {
 405         stat->cnt = 0;
 406 }
 407
 408 /**
 409  * blkg_rwstat_add - add a value to a blkg_rwstat
 410  * @rwstat: target blkg_rwstat
 411  * @rw: mask of REQ_{WRITE|SYNC}
 412  * @val: value to add
 413  *
 414  * Add @val to @rwstat.  The counters are chosen according to @rw.  The
 415  * caller is responsible for synchronizing calls to this function.
 416  */
 417 static inline void blkg_rwstat_add(struct blkg_rwstat *rwstat,
 418                                    int rw, uint64_t val)
 419 {
 420         u64_stats_update_begin(&rwstat->syncp);
 421
 422         if (rw & REQ_WRITE)
 423                 rwstat->cnt[BLKG_RWSTAT_WRITE] += val;
 424         else
 425                 rwstat->cnt[BLKG_RWSTAT_READ] += val;
 426         if (rw & REQ_SYNC)
 427                 rwstat->cnt[BLKG_RWSTAT_SYNC] += val;
 428         else
 429                 rwstat->cnt[BLKG_RWSTAT_ASYNC] += val;
 430
 431         u64_stats_update_end(&rwstat->syncp);
 432 }
 433
 434 /**
 435  * blkg_rwstat_read - read the current values of a blkg_rwstat
 436  * @rwstat: blkg_rwstat to read
 437  *
 438  * Read the current snapshot of @rwstat and return it as the return value.
 439  * This function can be called without synchronization and takes care of
 440  * u64 atomicity.
 441  */
 442 static inline struct blkg_rwstat blkg_rwstat_read(struct blkg_rwstat *rwstat)
 443 {
 444         unsigned int start;
 445         struct blkg_rwstat tmp;
 446
 447         do {
 448                 start = u64_stats_fetch_begin(&rwstat->syncp);
 449                 tmp = *rwstat;
 450         } while (u64_stats_fetch_retry(&rwstat->syncp, start));
 451
 452         return tmp;
 453 }
 454
 455 /**
 456  * blkg_rwstat_sum - read the total count of a blkg_rwstat
 457  * @rwstat: blkg_rwstat to read
 458  *
 459  * Return the total count of @rwstat regardless of the IO direction.  This
 460  * function can be called without synchronization and takes care of u64
 461  * atomicity.
 462  */
 463 static inline uint64_t blkg_rwstat_sum(struct blkg_rwstat *rwstat)
 464 {
 465         struct blkg_rwstat tmp = blkg_rwstat_read(rwstat);
 466
 467         return tmp.cnt[BLKG_RWSTAT_READ] + tmp.cnt[BLKG_RWSTAT_WRITE];
 468 }
 469
 470 /**
 471  * blkg_rwstat_reset - reset a blkg_rwstat
 472  * @rwstat: blkg_rwstat to reset
 473  */
 474 static inline void blkg_rwstat_reset(struct blkg_rwstat *rwstat)
 475 {
 476         memset(rwstat->cnt, 0, sizeof(rwstat->cnt));
 477 }
 478
 479 #else   /* CONFIG_BLK_CGROUP */
 480
 481 struct cgroup;
 482 struct blkcg;
 483
 484 struct blkg_policy_data {
 485 };
 486
 487 struct blkcg_gq {
 488 };
 489
 490 struct blkcg_policy {
 491 };
 492
 493 static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, void *key) { return NULL; }
 494 static inline int blkcg_init_queue(struct request_queue *q) { return 0; }
 495 static inline void blkcg_drain_queue(struct request_queue *q) { }
 496 static inline void blkcg_exit_queue(struct request_queue *q) { }
 497 static inline int blkcg_policy_register(struct blkcg_policy *pol) { return 0; }
 498 static inline void blkcg_policy_unregister(struct blkcg_policy *pol) { }
 499 static inline int blkcg_activate_policy(struct request_queue *q,
 500                                         const struct blkcg_policy *pol) { return 0; }
 501 static inline void blkcg_deactivate_policy(struct request_queue *q,
 502                                            const struct blkcg_policy *pol) { }
 503
 504 static inline struct blkcg *cgroup_to_blkcg(struct cgroup *cgroup) { return NULL; }
 505 static inline struct blkcg *bio_blkcg(struct bio *bio) { return NULL; }
 506
 507 static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
 508                                                   struct blkcg_policy *pol) { return NULL; }
 509 static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd) { return NULL; }
 510 static inline char *blkg_path(struct blkcg_gq *blkg) { return NULL; }
 511 static inline void blkg_get(struct blkcg_gq *blkg) { }
 512 static inline void blkg_put(struct blkcg_gq *blkg) { }
 513
 514 static inline struct request_list *blk_get_rl(struct request_queue *q,
 515                                               struct bio *bio) { return &q->root_rl; }
 516 static inline void blk_put_rl(struct request_list *rl) { }
 517 static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl) { }
 518 static inline struct request_list *blk_rq_rl(struct request *rq) { return &rq->q->root_rl; }
 519
 520 #define blk_queue_for_each_rl(rl, q)    \
 521         for ((rl) = &(q)->root_rl; (rl); (rl) = NULL)
 522
 523 #endif  /* CONFIG_BLK_CGROUP */
 524 #endif  /* _BLK_CGROUP_H */