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 };
  58
  59 struct blkg_stat {
  60         struct u64_stats_sync           syncp;
  61         uint64_t                        cnt;
  62 };
  63
  64 struct blkg_rwstat {
  65         struct u64_stats_sync           syncp;
  66         uint64_t                        cnt[BLKG_RWSTAT_NR];
  67 };
  68
  69 /*
  70  * A blkcg_gq (blkg) is association between a block cgroup (blkcg) and a
  71  * request_queue (q).  This is used by blkcg policies which need to track
  72  * information per blkcg - q pair.
  73  *
  74  * There can be multiple active blkcg policies and each has its private
  75  * data on each blkg, the size of which is determined by
  76  * blkcg_policy->pd_size.  blkcg core allocates and frees such areas
  77  * together with blkg and invokes pd_init/exit_fn() methods.
  78  *
  79  * Such private data must embed struct blkg_policy_data (pd) at the
  80  * beginning and pd_size can't be smaller than pd.
  81  */
  82 struct blkg_policy_data {
  83         /* the blkg this per-policy data belongs to */
  84         struct blkcg_gq                 *blkg;
  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         /* request allocation list for this blkcg-q pair */
  98         struct request_list             rl;
  99         /* reference count */
 100         int                             refcnt;
 101
 102         struct blkg_policy_data         *pd[BLKCG_MAX_POLS];
 103
 104         struct rcu_head                 rcu_head;
 105 };
 106
 107 typedef void (blkcg_pol_init_pd_fn)(struct blkcg_gq *blkg);
 108 typedef void (blkcg_pol_exit_pd_fn)(struct blkcg_gq *blkg);
 109 typedef void (blkcg_pol_reset_pd_stats_fn)(struct blkcg_gq *blkg);
 110
 111 struct blkcg_policy {
 112         int                             plid;
 113         /* policy specific private data size */
 114         size_t                          pd_size;
 115         /* cgroup files for the policy */
 116         struct cftype                   *cftypes;
 117
 118         /* operations */
 119         blkcg_pol_init_pd_fn            *pd_init_fn;
 120         blkcg_pol_exit_pd_fn            *pd_exit_fn;
 121         blkcg_pol_reset_pd_stats_fn     *pd_reset_stats_fn;
 122 };
 123
 124 extern struct blkcg blkcg_root;
 125
 126 struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, struct request_queue *q);
 127 struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
 128                                     struct request_queue *q);
 129 int blkcg_init_queue(struct request_queue *q);
 130 void blkcg_drain_queue(struct request_queue *q);
 131 void blkcg_exit_queue(struct request_queue *q);
 132
 133 /* Blkio controller policy registration */
 134 int blkcg_policy_register(struct blkcg_policy *pol);
 135 void blkcg_policy_unregister(struct blkcg_policy *pol);
 136 int blkcg_activate_policy(struct request_queue *q,
 137                           const struct blkcg_policy *pol);
 138 void blkcg_deactivate_policy(struct request_queue *q,
 139                              const struct blkcg_policy *pol);
 140
 141 void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg,
 142                        u64 (*prfill)(struct seq_file *,
 143                                      struct blkg_policy_data *, int),
 144                        const struct blkcg_policy *pol, int data,
 145                        bool show_total);
 146 u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v);
 147 u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
 148                          const struct blkg_rwstat *rwstat);
 149 u64 blkg_prfill_stat(struct seq_file *sf, struct blkg_policy_data *pd, int off);
 150 u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
 151                        int off);
 152
 153 struct blkg_conf_ctx {
 154         struct gendisk                  *disk;
 155         struct blkcg_gq                 *blkg;
 156         u64                             v;
 157 };
 158
 159 int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
 160                    const char *input, struct blkg_conf_ctx *ctx);
 161 void blkg_conf_finish(struct blkg_conf_ctx *ctx);
 162
 163
 164 static inline struct blkcg *cgroup_to_blkcg(struct cgroup *cgroup)
 165 {
 166         return container_of(cgroup_subsys_state(cgroup, blkio_subsys_id),
 167                             struct blkcg, css);
 168 }
 169
 170 static inline struct blkcg *task_blkcg(struct task_struct *tsk)
 171 {
 172         return container_of(task_subsys_state(tsk, blkio_subsys_id),
 173                             struct blkcg, css);
 174 }
 175
 176 static inline struct blkcg *bio_blkcg(struct bio *bio)
 177 {
 178         if (bio && bio->bi_css)
 179                 return container_of(bio->bi_css, struct blkcg, css);
 180         return task_blkcg(current);
 181 }
 182
 183 /**
 184  * blkg_to_pdata - get policy private data
 185  * @blkg: blkg of interest
 186  * @pol: policy of interest
 187  *
 188  * Return pointer to private data associated with the @blkg-@pol pair.
 189  */
 190 static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
 191                                                   struct blkcg_policy *pol)
 192 {
 193         return blkg ? blkg->pd[pol->plid] : NULL;
 194 }
 195
 196 /**
 197  * pdata_to_blkg - get blkg associated with policy private data
 198  * @pd: policy private data of interest
 199  *
 200  * @pd is policy private data.  Determine the blkg it's associated with.
 201  */
 202 static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd)
 203 {
 204         return pd ? pd->blkg : NULL;
 205 }
 206
 207 /**
 208  * blkg_path - format cgroup path of blkg
 209  * @blkg: blkg of interest
 210  * @buf: target buffer
 211  * @buflen: target buffer length
 212  *
 213  * Format the path of the cgroup of @blkg into @buf.
 214  */
 215 static inline int blkg_path(struct blkcg_gq *blkg, char *buf, int buflen)
 216 {
 217         int ret;
 218
 219         rcu_read_lock();
 220         ret = cgroup_path(blkg->blkcg->css.cgroup, buf, buflen);
 221         rcu_read_unlock();
 222         if (ret)
 223                 strncpy(buf, "<unavailable>", buflen);
 224         return ret;
 225 }
 226
 227 /**
 228  * blkg_get - get a blkg reference
 229  * @blkg: blkg to get
 230  *
 231  * The caller should be holding queue_lock and an existing reference.
 232  */
 233 static inline void blkg_get(struct blkcg_gq *blkg)
 234 {
 235         lockdep_assert_held(blkg->q->queue_lock);
 236         WARN_ON_ONCE(!blkg->refcnt);
 237         blkg->refcnt++;
 238 }
 239
 240 void __blkg_release(struct blkcg_gq *blkg);
 241
 242 /**
 243  * blkg_put - put a blkg reference
 244  * @blkg: blkg to put
 245  *
 246  * The caller should be holding queue_lock.
 247  */
 248 static inline void blkg_put(struct blkcg_gq *blkg)
 249 {
 250         lockdep_assert_held(blkg->q->queue_lock);
 251         WARN_ON_ONCE(blkg->refcnt <= 0);
 252         if (!--blkg->refcnt)
 253                 __blkg_release(blkg);
 254 }
 255
 256 /**
 257  * blk_get_rl - get request_list to use
 258  * @q: request_queue of interest
 259  * @bio: bio which will be attached to the allocated request (may be %NULL)
 260  *
 261  * The caller wants to allocate a request from @q to use for @bio.  Find
 262  * the request_list to use and obtain a reference on it.  Should be called
 263  * under queue_lock.  This function is guaranteed to return non-%NULL
 264  * request_list.
 265  */
 266 static inline struct request_list *blk_get_rl(struct request_queue *q,
 267                                               struct bio *bio)
 268 {
 269         struct blkcg *blkcg;
 270         struct blkcg_gq *blkg;
 271
 272         rcu_read_lock();
 273
 274         blkcg = bio_blkcg(bio);
 275
 276         /* bypass blkg lookup and use @q->root_rl directly for root */
 277         if (blkcg == &blkcg_root)
 278                 goto root_rl;
 279
 280         /*
 281          * Try to use blkg->rl.  blkg lookup may fail under memory pressure
 282          * or if either the blkcg or queue is going away.  Fall back to
 283          * root_rl in such cases.
 284          */
 285         blkg = blkg_lookup_create(blkcg, q);
 286         if (unlikely(IS_ERR(blkg)))
 287                 goto root_rl;
 288
 289         blkg_get(blkg);
 290         rcu_read_unlock();
 291         return &blkg->rl;
 292 root_rl:
 293         rcu_read_unlock();
 294         return &q->root_rl;
 295 }
 296
 297 /**
 298  * blk_put_rl - put request_list
 299  * @rl: request_list to put
 300  *
 301  * Put the reference acquired by blk_get_rl().  Should be called under
 302  * queue_lock.
 303  */
 304 static inline void blk_put_rl(struct request_list *rl)
 305 {
 306         /* root_rl may not have blkg set */
 307         if (rl->blkg && rl->blkg->blkcg != &blkcg_root)
 308                 blkg_put(rl->blkg);
 309 }
 310
 311 /**
 312  * blk_rq_set_rl - associate a request with a request_list
 313  * @rq: request of interest
 314  * @rl: target request_list
 315  *
 316  * Associate @rq with @rl so that accounting and freeing can know the
 317  * request_list @rq came from.
 318  */
 319 static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl)
 320 {
 321         rq->rl = rl;
 322 }
 323
 324 /**
 325  * blk_rq_rl - return the request_list a request came from
 326  * @rq: request of interest
 327  *
 328  * Return the request_list @rq is allocated from.
 329  */
 330 static inline struct request_list *blk_rq_rl(struct request *rq)
 331 {
 332         return rq->rl;
 333 }
 334
 335 struct request_list *__blk_queue_next_rl(struct request_list *rl,
 336                                          struct request_queue *q);
 337 /**
 338  * blk_queue_for_each_rl - iterate through all request_lists of a request_queue
 339  *
 340  * Should be used under queue_lock.
 341  */
 342 #define blk_queue_for_each_rl(rl, q)    \
 343         for ((rl) = &(q)->root_rl; (rl); (rl) = __blk_queue_next_rl((rl), (q)))
 344
 345 /**
 346  * blkg_stat_add - add a value to a blkg_stat
 347  * @stat: target blkg_stat
 348  * @val: value to add
 349  *
 350  * Add @val to @stat.  The caller is responsible for synchronizing calls to
 351  * this function.
 352  */
 353 static inline void blkg_stat_add(struct blkg_stat *stat, uint64_t val)
 354 {
 355         u64_stats_update_begin(&stat->syncp);
 356         stat->cnt += val;
 357         u64_stats_update_end(&stat->syncp);
 358 }
 359
 360 /**
 361  * blkg_stat_read - read the current value of a blkg_stat
 362  * @stat: blkg_stat to read
 363  *
 364  * Read the current value of @stat.  This function can be called without
 365  * synchroniztion and takes care of u64 atomicity.
 366  */
 367 static inline uint64_t blkg_stat_read(struct blkg_stat *stat)
 368 {
 369         unsigned int start;
 370         uint64_t v;
 371
 372         do {
 373                 start = u64_stats_fetch_begin(&stat->syncp);
 374                 v = stat->cnt;
 375         } while (u64_stats_fetch_retry(&stat->syncp, start));
 376
 377         return v;
 378 }
 379
 380 /**
 381  * blkg_stat_reset - reset a blkg_stat
 382  * @stat: blkg_stat to reset
 383  */
 384 static inline void blkg_stat_reset(struct blkg_stat *stat)
 385 {
 386         stat->cnt = 0;
 387 }
 388
 389 /**
 390  * blkg_rwstat_add - add a value to a blkg_rwstat
 391  * @rwstat: target blkg_rwstat
 392  * @rw: mask of REQ_{WRITE|SYNC}
 393  * @val: value to add
 394  *
 395  * Add @val to @rwstat.  The counters are chosen according to @rw.  The
 396  * caller is responsible for synchronizing calls to this function.
 397  */
 398 static inline void blkg_rwstat_add(struct blkg_rwstat *rwstat,
 399                                    int rw, uint64_t val)
 400 {
 401         u64_stats_update_begin(&rwstat->syncp);
 402
 403         if (rw & REQ_WRITE)
 404                 rwstat->cnt[BLKG_RWSTAT_WRITE] += val;
 405         else
 406                 rwstat->cnt[BLKG_RWSTAT_READ] += val;
 407         if (rw & REQ_SYNC)
 408                 rwstat->cnt[BLKG_RWSTAT_SYNC] += val;
 409         else
 410                 rwstat->cnt[BLKG_RWSTAT_ASYNC] += val;
 411
 412         u64_stats_update_end(&rwstat->syncp);
 413 }
 414
 415 /**
 416  * blkg_rwstat_read - read the current values of a blkg_rwstat
 417  * @rwstat: blkg_rwstat to read
 418  *
 419  * Read the current snapshot of @rwstat and return it as the return value.
 420  * This function can be called without synchronization and takes care of
 421  * u64 atomicity.
 422  */
 423 static inline struct blkg_rwstat blkg_rwstat_read(struct blkg_rwstat *rwstat)
 424 {
 425         unsigned int start;
 426         struct blkg_rwstat tmp;
 427
 428         do {
 429                 start = u64_stats_fetch_begin(&rwstat->syncp);
 430                 tmp = *rwstat;
 431         } while (u64_stats_fetch_retry(&rwstat->syncp, start));
 432
 433         return tmp;
 434 }
 435
 436 /**
 437  * blkg_rwstat_sum - read the total count of a blkg_rwstat
 438  * @rwstat: blkg_rwstat to read
 439  *
 440  * Return the total count of @rwstat regardless of the IO direction.  This
 441  * function can be called without synchronization and takes care of u64
 442  * atomicity.
 443  */
 444 static inline uint64_t blkg_rwstat_sum(struct blkg_rwstat *rwstat)
 445 {
 446         struct blkg_rwstat tmp = blkg_rwstat_read(rwstat);
 447
 448         return tmp.cnt[BLKG_RWSTAT_READ] + tmp.cnt[BLKG_RWSTAT_WRITE];
 449 }
 450
 451 /**
 452  * blkg_rwstat_reset - reset a blkg_rwstat
 453  * @rwstat: blkg_rwstat to reset
 454  */
 455 static inline void blkg_rwstat_reset(struct blkg_rwstat *rwstat)
 456 {
 457         memset(rwstat->cnt, 0, sizeof(rwstat->cnt));
 458 }
 459
 460 #else   /* CONFIG_BLK_CGROUP */
 461
 462 struct cgroup;
 463 struct blkcg;
 464
 465 struct blkg_policy_data {
 466 };
 467
 468 struct blkcg_gq {
 469 };
 470
 471 struct blkcg_policy {
 472 };
 473
 474 static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, void *key) { return NULL; }
 475 static inline int blkcg_init_queue(struct request_queue *q) { return 0; }
 476 static inline void blkcg_drain_queue(struct request_queue *q) { }
 477 static inline void blkcg_exit_queue(struct request_queue *q) { }
 478 static inline int blkcg_policy_register(struct blkcg_policy *pol) { return 0; }
 479 static inline void blkcg_policy_unregister(struct blkcg_policy *pol) { }
 480 static inline int blkcg_activate_policy(struct request_queue *q,
 481                                         const struct blkcg_policy *pol) { return 0; }
 482 static inline void blkcg_deactivate_policy(struct request_queue *q,
 483                                            const struct blkcg_policy *pol) { }
 484
 485 static inline struct blkcg *cgroup_to_blkcg(struct cgroup *cgroup) { return NULL; }
 486 static inline struct blkcg *bio_blkcg(struct bio *bio) { return NULL; }
 487
 488 static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
 489                                                   struct blkcg_policy *pol) { return NULL; }
 490 static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd) { return NULL; }
 491 static inline char *blkg_path(struct blkcg_gq *blkg) { return NULL; }
 492 static inline void blkg_get(struct blkcg_gq *blkg) { }
 493 static inline void blkg_put(struct blkcg_gq *blkg) { }
 494
 495 static inline struct request_list *blk_get_rl(struct request_queue *q,
 496                                               struct bio *bio) { return &q->root_rl; }
 497 static inline void blk_put_rl(struct request_list *rl) { }
 498 static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl) { }
 499 static inline struct request_list *blk_rq_rl(struct request *rq) { return &rq->q->root_rl; }
 500
 501 #define blk_queue_for_each_rl(rl, q)    \
 502         for ((rl) = &(q)->root_rl; (rl); (rl) = NULL)
 503
 504 #endif  /* CONFIG_BLK_CGROUP */
 505 #endif  /* _BLK_CGROUP_H */