include/linux/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/percpu_counter.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 /* percpu_counter batch for blkg_[rw]stats, per-cpu drift doesn't matter */
  24 #define BLKG_STAT_CPU_BATCH     (INT_MAX / 2)
  25
  26 /* Max limits for throttle policy */
  27 #define THROTL_IOPS_MAX         UINT_MAX
  28
  29 #ifdef CONFIG_BLK_CGROUP
  30
  31 enum blkg_rwstat_type {
  32         BLKG_RWSTAT_READ,
  33         BLKG_RWSTAT_WRITE,
  34         BLKG_RWSTAT_SYNC,
  35         BLKG_RWSTAT_ASYNC,
  36
  37         BLKG_RWSTAT_NR,
  38         BLKG_RWSTAT_TOTAL = BLKG_RWSTAT_NR,
  39 };
  40
  41 struct blkcg_gq;
  42
  43 struct blkcg {
  44         struct cgroup_subsys_state      css;
  45         spinlock_t                      lock;
  46
  47         struct radix_tree_root          blkg_tree;
  48         struct blkcg_gq                 *blkg_hint;
  49         struct hlist_head               blkg_list;
  50
  51         struct blkcg_policy_data        *cpd[BLKCG_MAX_POLS];
  52
  53         struct list_head                all_blkcgs_node;
  54 #ifdef CONFIG_CGROUP_WRITEBACK
  55         struct list_head                cgwb_list;
  56 #endif
  57 };
  58
  59 /*
  60  * blkg_[rw]stat->aux_cnt is excluded for local stats but included for
  61  * recursive.  Used to carry stats of dead children, and, for blkg_rwstat,
  62  * to carry result values from read and sum operations.
  63  */
  64 struct blkg_stat {
  65         struct percpu_counter           cpu_cnt;
  66         atomic64_t                      aux_cnt;
  67 };
  68
  69 struct blkg_rwstat {
  70         struct percpu_counter           cpu_cnt[BLKG_RWSTAT_NR];
  71         atomic64_t                      aux_cnt[BLKG_RWSTAT_NR];
  72 };
  73
  74 /*
  75  * A blkcg_gq (blkg) is association between a block cgroup (blkcg) and a
  76  * request_queue (q).  This is used by blkcg policies which need to track
  77  * information per blkcg - q pair.
  78  *
  79  * There can be multiple active blkcg policies and each blkg:policy pair is
  80  * represented by a blkg_policy_data which is allocated and freed by each
  81  * policy's pd_alloc/free_fn() methods.  A policy can allocate private data
  82  * area by allocating larger data structure which embeds blkg_policy_data
  83  * at the beginning.
  84  */
  85 struct blkg_policy_data {
  86         /* the blkg and policy id this per-policy data belongs to */
  87         struct blkcg_gq                 *blkg;
  88         int                             plid;
  89 };
  90
  91 /*
  92  * Policies that need to keep per-blkcg data which is independent from any
  93  * request_queue associated to it should implement cpd_alloc/free_fn()
  94  * methods.  A policy can allocate private data area by allocating larger
  95  * data structure which embeds blkcg_policy_data at the beginning.
  96  * cpd_init() is invoked to let each policy handle per-blkcg data.
  97  */
  98 struct blkcg_policy_data {
  99         /* the blkcg and policy id this per-policy data belongs to */
 100         struct blkcg                    *blkcg;
 101         int                             plid;
 102 };
 103
 104 /* association between a blk cgroup and a request queue */
 105 struct blkcg_gq {
 106         /* Pointer to the associated request_queue */
 107         struct request_queue            *q;
 108         struct list_head                q_node;
 109         struct hlist_node               blkcg_node;
 110         struct blkcg                    *blkcg;
 111
 112         /*
 113          * Each blkg gets congested separately and the congestion state is
 114          * propagated to the matching bdi_writeback_congested.
 115          */
 116         struct bdi_writeback_congested  *wb_congested;
 117
 118         /* all non-root blkcg_gq's are guaranteed to have access to parent */
 119         struct blkcg_gq                 *parent;
 120
 121         /* request allocation list for this blkcg-q pair */
 122         struct request_list             rl;
 123
 124         /* reference count */
 125         atomic_t                        refcnt;
 126
 127         /* is this blkg online? protected by both blkcg and q locks */
 128         bool                            online;
 129
 130         struct blkg_rwstat              stat_bytes;
 131         struct blkg_rwstat              stat_ios;
 132
 133         struct blkg_policy_data         *pd[BLKCG_MAX_POLS];
 134
 135         struct rcu_head                 rcu_head;
 136 };
 137
 138 typedef struct blkcg_policy_data *(blkcg_pol_alloc_cpd_fn)(gfp_t gfp);
 139 typedef void (blkcg_pol_init_cpd_fn)(struct blkcg_policy_data *cpd);
 140 typedef void (blkcg_pol_free_cpd_fn)(struct blkcg_policy_data *cpd);
 141 typedef void (blkcg_pol_bind_cpd_fn)(struct blkcg_policy_data *cpd);
 142 typedef struct blkg_policy_data *(blkcg_pol_alloc_pd_fn)(gfp_t gfp, int node);
 143 typedef void (blkcg_pol_init_pd_fn)(struct blkg_policy_data *pd);
 144 typedef void (blkcg_pol_online_pd_fn)(struct blkg_policy_data *pd);
 145 typedef void (blkcg_pol_offline_pd_fn)(struct blkg_policy_data *pd);
 146 typedef void (blkcg_pol_free_pd_fn)(struct blkg_policy_data *pd);
 147 typedef void (blkcg_pol_reset_pd_stats_fn)(struct blkg_policy_data *pd);
 148
 149 struct blkcg_policy {
 150         int                             plid;
 151         /* cgroup files for the policy */
 152         struct cftype                   *dfl_cftypes;
 153         struct cftype                   *legacy_cftypes;
 154
 155         /* operations */
 156         blkcg_pol_alloc_cpd_fn          *cpd_alloc_fn;
 157         blkcg_pol_init_cpd_fn           *cpd_init_fn;
 158         blkcg_pol_free_cpd_fn           *cpd_free_fn;
 159         blkcg_pol_bind_cpd_fn           *cpd_bind_fn;
 160
 161         blkcg_pol_alloc_pd_fn           *pd_alloc_fn;
 162         blkcg_pol_init_pd_fn            *pd_init_fn;
 163         blkcg_pol_online_pd_fn          *pd_online_fn;
 164         blkcg_pol_offline_pd_fn         *pd_offline_fn;
 165         blkcg_pol_free_pd_fn            *pd_free_fn;
 166         blkcg_pol_reset_pd_stats_fn     *pd_reset_stats_fn;
 167 };
 168
 169 extern struct blkcg blkcg_root;
 170 extern struct cgroup_subsys_state * const blkcg_root_css;
 171
 172 struct blkcg_gq *blkg_lookup_slowpath(struct blkcg *blkcg,
 173                                       struct request_queue *q, bool update_hint);
 174 struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
 175                                     struct request_queue *q);
 176 int blkcg_init_queue(struct request_queue *q);
 177 void blkcg_drain_queue(struct request_queue *q);
 178 void blkcg_exit_queue(struct request_queue *q);
 179
 180 /* Blkio controller policy registration */
 181 int blkcg_policy_register(struct blkcg_policy *pol);
 182 void blkcg_policy_unregister(struct blkcg_policy *pol);
 183 int blkcg_activate_policy(struct request_queue *q,
 184                           const struct blkcg_policy *pol);
 185 void blkcg_deactivate_policy(struct request_queue *q,
 186                              const struct blkcg_policy *pol);
 187
 188 const char *blkg_dev_name(struct blkcg_gq *blkg);
 189 void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg,
 190                        u64 (*prfill)(struct seq_file *,
 191                                      struct blkg_policy_data *, int),
 192                        const struct blkcg_policy *pol, int data,
 193                        bool show_total);
 194 u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v);
 195 u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
 196                          const struct blkg_rwstat *rwstat);
 197 u64 blkg_prfill_stat(struct seq_file *sf, struct blkg_policy_data *pd, int off);
 198 u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
 199                        int off);
 200 int blkg_print_stat_bytes(struct seq_file *sf, void *v);
 201 int blkg_print_stat_ios(struct seq_file *sf, void *v);
 202 int blkg_print_stat_bytes_recursive(struct seq_file *sf, void *v);
 203 int blkg_print_stat_ios_recursive(struct seq_file *sf, void *v);
 204
 205 u64 blkg_stat_recursive_sum(struct blkcg_gq *blkg,
 206                             struct blkcg_policy *pol, int off);
 207 struct blkg_rwstat blkg_rwstat_recursive_sum(struct blkcg_gq *blkg,
 208                                              struct blkcg_policy *pol, int off);
 209
 210 struct blkg_conf_ctx {
 211         struct gendisk                  *disk;
 212         struct blkcg_gq                 *blkg;
 213         char                            *body;
 214 };
 215
 216 int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
 217                    char *input, struct blkg_conf_ctx *ctx);
 218 void blkg_conf_finish(struct blkg_conf_ctx *ctx);
 219
 220
 221 static inline struct blkcg *css_to_blkcg(struct cgroup_subsys_state *css)
 222 {
 223         return css ? container_of(css, struct blkcg, css) : NULL;
 224 }
 225
 226 static inline struct blkcg *task_blkcg(struct task_struct *tsk)
 227 {
 228         return css_to_blkcg(task_css(tsk, io_cgrp_id));
 229 }
 230
 231 static inline struct blkcg *bio_blkcg(struct bio *bio)
 232 {
 233         if (bio && bio->bi_css)
 234                 return css_to_blkcg(bio->bi_css);
 235         return task_blkcg(current);
 236 }
 237
 238 static inline struct cgroup_subsys_state *
 239 task_get_blkcg_css(struct task_struct *task)
 240 {
 241         return task_get_css(task, io_cgrp_id);
 242 }
 243
 244 /**
 245  * blkcg_parent - get the parent of a blkcg
 246  * @blkcg: blkcg of interest
 247  *
 248  * Return the parent blkcg of @blkcg.  Can be called anytime.
 249  */
 250 static inline struct blkcg *blkcg_parent(struct blkcg *blkcg)
 251 {
 252         return css_to_blkcg(blkcg->css.parent);
 253 }
 254
 255 /**
 256  * __blkg_lookup - internal version of blkg_lookup()
 257  * @blkcg: blkcg of interest
 258  * @q: request_queue of interest
 259  * @update_hint: whether to update lookup hint with the result or not
 260  *
 261  * This is internal version and shouldn't be used by policy
 262  * implementations.  Looks up blkgs for the @blkcg - @q pair regardless of
 263  * @q's bypass state.  If @update_hint is %true, the caller should be
 264  * holding @q->queue_lock and lookup hint is updated on success.
 265  */
 266 static inline struct blkcg_gq *__blkg_lookup(struct blkcg *blkcg,
 267                                              struct request_queue *q,
 268                                              bool update_hint)
 269 {
 270         struct blkcg_gq *blkg;
 271
 272         if (blkcg == &blkcg_root)
 273                 return q->root_blkg;
 274
 275         blkg = rcu_dereference(blkcg->blkg_hint);
 276         if (blkg && blkg->q == q)
 277                 return blkg;
 278
 279         return blkg_lookup_slowpath(blkcg, q, update_hint);
 280 }
 281
 282 /**
 283  * blkg_lookup - lookup blkg for the specified blkcg - q pair
 284  * @blkcg: blkcg of interest
 285  * @q: request_queue of interest
 286  *
 287  * Lookup blkg for the @blkcg - @q pair.  This function should be called
 288  * under RCU read lock and is guaranteed to return %NULL if @q is bypassing
 289  * - see blk_queue_bypass_start() for details.
 290  */
 291 static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg,
 292                                            struct request_queue *q)
 293 {
 294         WARN_ON_ONCE(!rcu_read_lock_held());
 295
 296         if (unlikely(blk_queue_bypass(q)))
 297                 return NULL;
 298         return __blkg_lookup(blkcg, q, false);
 299 }
 300
 301 /**
 302  * blkg_to_pdata - get policy private data
 303  * @blkg: blkg of interest
 304  * @pol: policy of interest
 305  *
 306  * Return pointer to private data associated with the @blkg-@pol pair.
 307  */
 308 static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
 309                                                   struct blkcg_policy *pol)
 310 {
 311         return blkg ? blkg->pd[pol->plid] : NULL;
 312 }
 313
 314 static inline struct blkcg_policy_data *blkcg_to_cpd(struct blkcg *blkcg,
 315                                                      struct blkcg_policy *pol)
 316 {
 317         return blkcg ? blkcg->cpd[pol->plid] : NULL;
 318 }
 319
 320 /**
 321  * pdata_to_blkg - get blkg associated with policy private data
 322  * @pd: policy private data of interest
 323  *
 324  * @pd is policy private data.  Determine the blkg it's associated with.
 325  */
 326 static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd)
 327 {
 328         return pd ? pd->blkg : NULL;
 329 }
 330
 331 static inline struct blkcg *cpd_to_blkcg(struct blkcg_policy_data *cpd)
 332 {
 333         return cpd ? cpd->blkcg : NULL;
 334 }
 335
 336 /**
 337  * blkg_path - format cgroup path of blkg
 338  * @blkg: blkg of interest
 339  * @buf: target buffer
 340  * @buflen: target buffer length
 341  *
 342  * Format the path of the cgroup of @blkg into @buf.
 343  */
 344 static inline int blkg_path(struct blkcg_gq *blkg, char *buf, int buflen)
 345 {
 346         char *p;
 347
 348         p = cgroup_path(blkg->blkcg->css.cgroup, buf, buflen);
 349         if (!p) {
 350                 strncpy(buf, "<unavailable>", buflen);
 351                 return -ENAMETOOLONG;
 352         }
 353
 354         memmove(buf, p, buf + buflen - p);
 355         return 0;
 356 }
 357
 358 /**
 359  * blkg_get - get a blkg reference
 360  * @blkg: blkg to get
 361  *
 362  * The caller should be holding an existing reference.
 363  */
 364 static inline void blkg_get(struct blkcg_gq *blkg)
 365 {
 366         WARN_ON_ONCE(atomic_read(&blkg->refcnt) <= 0);
 367         atomic_inc(&blkg->refcnt);
 368 }
 369
 370 void __blkg_release_rcu(struct rcu_head *rcu);
 371
 372 /**
 373  * blkg_put - put a blkg reference
 374  * @blkg: blkg to put
 375  */
 376 static inline void blkg_put(struct blkcg_gq *blkg)
 377 {
 378         WARN_ON_ONCE(atomic_read(&blkg->refcnt) <= 0);
 379         if (atomic_dec_and_test(&blkg->refcnt))
 380                 call_rcu(&blkg->rcu_head, __blkg_release_rcu);
 381 }
 382
 383 /**
 384  * blkg_for_each_descendant_pre - pre-order walk of a blkg's descendants
 385  * @d_blkg: loop cursor pointing to the current descendant
 386  * @pos_css: used for iteration
 387  * @p_blkg: target blkg to walk descendants of
 388  *
 389  * Walk @c_blkg through the descendants of @p_blkg.  Must be used with RCU
 390  * read locked.  If called under either blkcg or queue lock, the iteration
 391  * is guaranteed to include all and only online blkgs.  The caller may
 392  * update @pos_css by calling css_rightmost_descendant() to skip subtree.
 393  * @p_blkg is included in the iteration and the first node to be visited.
 394  */
 395 #define blkg_for_each_descendant_pre(d_blkg, pos_css, p_blkg)           \
 396         css_for_each_descendant_pre((pos_css), &(p_blkg)->blkcg->css)   \
 397                 if (((d_blkg) = __blkg_lookup(css_to_blkcg(pos_css),    \
 398                                               (p_blkg)->q, false)))
 399
 400 /**
 401  * blkg_for_each_descendant_post - post-order walk of a blkg's descendants
 402  * @d_blkg: loop cursor pointing to the current descendant
 403  * @pos_css: used for iteration
 404  * @p_blkg: target blkg to walk descendants of
 405  *
 406  * Similar to blkg_for_each_descendant_pre() but performs post-order
 407  * traversal instead.  Synchronization rules are the same.  @p_blkg is
 408  * included in the iteration and the last node to be visited.
 409  */
 410 #define blkg_for_each_descendant_post(d_blkg, pos_css, p_blkg)          \
 411         css_for_each_descendant_post((pos_css), &(p_blkg)->blkcg->css)  \
 412                 if (((d_blkg) = __blkg_lookup(css_to_blkcg(pos_css),    \
 413                                               (p_blkg)->q, false)))
 414
 415 /**
 416  * blk_get_rl - get request_list to use
 417  * @q: request_queue of interest
 418  * @bio: bio which will be attached to the allocated request (may be %NULL)
 419  *
 420  * The caller wants to allocate a request from @q to use for @bio.  Find
 421  * the request_list to use and obtain a reference on it.  Should be called
 422  * under queue_lock.  This function is guaranteed to return non-%NULL
 423  * request_list.
 424  */
 425 static inline struct request_list *blk_get_rl(struct request_queue *q,
 426                                               struct bio *bio)
 427 {
 428         struct blkcg *blkcg;
 429         struct blkcg_gq *blkg;
 430
 431         rcu_read_lock();
 432
 433         blkcg = bio_blkcg(bio);
 434
 435         /* bypass blkg lookup and use @q->root_rl directly for root */
 436         if (blkcg == &blkcg_root)
 437                 goto root_rl;
 438
 439         /*
 440          * Try to use blkg->rl.  blkg lookup may fail under memory pressure
 441          * or if either the blkcg or queue is going away.  Fall back to
 442          * root_rl in such cases.
 443          */
 444         blkg = blkg_lookup(blkcg, q);
 445         if (unlikely(!blkg))
 446                 goto root_rl;
 447
 448         blkg_get(blkg);
 449         rcu_read_unlock();
 450         return &blkg->rl;
 451 root_rl:
 452         rcu_read_unlock();
 453         return &q->root_rl;
 454 }
 455
 456 /**
 457  * blk_put_rl - put request_list
 458  * @rl: request_list to put
 459  *
 460  * Put the reference acquired by blk_get_rl().  Should be called under
 461  * queue_lock.
 462  */
 463 static inline void blk_put_rl(struct request_list *rl)
 464 {
 465         if (rl->blkg->blkcg != &blkcg_root)
 466                 blkg_put(rl->blkg);
 467 }
 468
 469 /**
 470  * blk_rq_set_rl - associate a request with a request_list
 471  * @rq: request of interest
 472  * @rl: target request_list
 473  *
 474  * Associate @rq with @rl so that accounting and freeing can know the
 475  * request_list @rq came from.
 476  */
 477 static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl)
 478 {
 479         rq->rl = rl;
 480 }
 481
 482 /**
 483  * blk_rq_rl - return the request_list a request came from
 484  * @rq: request of interest
 485  *
 486  * Return the request_list @rq is allocated from.
 487  */
 488 static inline struct request_list *blk_rq_rl(struct request *rq)
 489 {
 490         return rq->rl;
 491 }
 492
 493 struct request_list *__blk_queue_next_rl(struct request_list *rl,
 494                                          struct request_queue *q);
 495 /**
 496  * blk_queue_for_each_rl - iterate through all request_lists of a request_queue
 497  *
 498  * Should be used under queue_lock.
 499  */
 500 #define blk_queue_for_each_rl(rl, q)    \
 501         for ((rl) = &(q)->root_rl; (rl); (rl) = __blk_queue_next_rl((rl), (q)))
 502
 503 static inline int blkg_stat_init(struct blkg_stat *stat, gfp_t gfp)
 504 {
 505         int ret;
 506
 507         ret = percpu_counter_init(&stat->cpu_cnt, 0, gfp);
 508         if (ret)
 509                 return ret;
 510
 511         atomic64_set(&stat->aux_cnt, 0);
 512         return 0;
 513 }
 514
 515 static inline void blkg_stat_exit(struct blkg_stat *stat)
 516 {
 517         percpu_counter_destroy(&stat->cpu_cnt);
 518 }
 519
 520 /**
 521  * blkg_stat_add - add a value to a blkg_stat
 522  * @stat: target blkg_stat
 523  * @val: value to add
 524  *
 525  * Add @val to @stat.  The caller must ensure that IRQ on the same CPU
 526  * don't re-enter this function for the same counter.
 527  */
 528 static inline void blkg_stat_add(struct blkg_stat *stat, uint64_t val)
 529 {
 530         __percpu_counter_add(&stat->cpu_cnt, val, BLKG_STAT_CPU_BATCH);
 531 }
 532
 533 /**
 534  * blkg_stat_read - read the current value of a blkg_stat
 535  * @stat: blkg_stat to read
 536  */
 537 static inline uint64_t blkg_stat_read(struct blkg_stat *stat)
 538 {
 539         return percpu_counter_sum_positive(&stat->cpu_cnt);
 540 }
 541
 542 /**
 543  * blkg_stat_reset - reset a blkg_stat
 544  * @stat: blkg_stat to reset
 545  */
 546 static inline void blkg_stat_reset(struct blkg_stat *stat)
 547 {
 548         percpu_counter_set(&stat->cpu_cnt, 0);
 549         atomic64_set(&stat->aux_cnt, 0);
 550 }
 551
 552 /**
 553  * blkg_stat_add_aux - add a blkg_stat into another's aux count
 554  * @to: the destination blkg_stat
 555  * @from: the source
 556  *
 557  * Add @from's count including the aux one to @to's aux count.
 558  */
 559 static inline void blkg_stat_add_aux(struct blkg_stat *to,
 560                                      struct blkg_stat *from)
 561 {
 562         atomic64_add(blkg_stat_read(from) + atomic64_read(&from->aux_cnt),
 563                      &to->aux_cnt);
 564 }
 565
 566 static inline int blkg_rwstat_init(struct blkg_rwstat *rwstat, gfp_t gfp)
 567 {
 568         int i, ret;
 569
 570         for (i = 0; i < BLKG_RWSTAT_NR; i++) {
 571                 ret = percpu_counter_init(&rwstat->cpu_cnt[i], 0, gfp);
 572                 if (ret) {
 573                         while (--i >= 0)
 574                                 percpu_counter_destroy(&rwstat->cpu_cnt[i]);
 575                         return ret;
 576                 }
 577                 atomic64_set(&rwstat->aux_cnt[i], 0);
 578         }
 579         return 0;
 580 }
 581
 582 static inline void blkg_rwstat_exit(struct blkg_rwstat *rwstat)
 583 {
 584         int i;
 585
 586         for (i = 0; i < BLKG_RWSTAT_NR; i++)
 587                 percpu_counter_destroy(&rwstat->cpu_cnt[i]);
 588 }
 589
 590 /**
 591  * blkg_rwstat_add - add a value to a blkg_rwstat
 592  * @rwstat: target blkg_rwstat
 593  * @rw: mask of REQ_{WRITE|SYNC}
 594  * @val: value to add
 595  *
 596  * Add @val to @rwstat.  The counters are chosen according to @rw.  The
 597  * caller is responsible for synchronizing calls to this function.
 598  */
 599 static inline void blkg_rwstat_add(struct blkg_rwstat *rwstat,
 600                                    int rw, uint64_t val)
 601 {
 602         struct percpu_counter *cnt;
 603
 604         if (rw & REQ_WRITE)
 605                 cnt = &rwstat->cpu_cnt[BLKG_RWSTAT_WRITE];
 606         else
 607                 cnt = &rwstat->cpu_cnt[BLKG_RWSTAT_READ];
 608
 609         __percpu_counter_add(cnt, val, BLKG_STAT_CPU_BATCH);
 610
 611         if (rw & REQ_SYNC)
 612                 cnt = &rwstat->cpu_cnt[BLKG_RWSTAT_SYNC];
 613         else
 614                 cnt = &rwstat->cpu_cnt[BLKG_RWSTAT_ASYNC];
 615
 616         __percpu_counter_add(cnt, val, BLKG_STAT_CPU_BATCH);
 617 }
 618
 619 /**
 620  * blkg_rwstat_read - read the current values of a blkg_rwstat
 621  * @rwstat: blkg_rwstat to read
 622  *
 623  * Read the current snapshot of @rwstat and return it in the aux counts.
 624  */
 625 static inline struct blkg_rwstat blkg_rwstat_read(struct blkg_rwstat *rwstat)
 626 {
 627         struct blkg_rwstat result;
 628         int i;
 629
 630         for (i = 0; i < BLKG_RWSTAT_NR; i++)
 631                 atomic64_set(&result.aux_cnt[i],
 632                              percpu_counter_sum_positive(&rwstat->cpu_cnt[i]));
 633         return result;
 634 }
 635
 636 /**
 637  * blkg_rwstat_total - read the total count of a blkg_rwstat
 638  * @rwstat: blkg_rwstat to read
 639  *
 640  * Return the total count of @rwstat regardless of the IO direction.  This
 641  * function can be called without synchronization and takes care of u64
 642  * atomicity.
 643  */
 644 static inline uint64_t blkg_rwstat_total(struct blkg_rwstat *rwstat)
 645 {
 646         struct blkg_rwstat tmp = blkg_rwstat_read(rwstat);
 647
 648         return atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_READ]) +
 649                 atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_WRITE]);
 650 }
 651
 652 /**
 653  * blkg_rwstat_reset - reset a blkg_rwstat
 654  * @rwstat: blkg_rwstat to reset
 655  */
 656 static inline void blkg_rwstat_reset(struct blkg_rwstat *rwstat)
 657 {
 658         int i;
 659
 660         for (i = 0; i < BLKG_RWSTAT_NR; i++) {
 661                 percpu_counter_set(&rwstat->cpu_cnt[i], 0);
 662                 atomic64_set(&rwstat->aux_cnt[i], 0);
 663         }
 664 }
 665
 666 /**
 667  * blkg_rwstat_add_aux - add a blkg_rwstat into another's aux count
 668  * @to: the destination blkg_rwstat
 669  * @from: the source
 670  *
 671  * Add @from's count including the aux one to @to's aux count.
 672  */
 673 static inline void blkg_rwstat_add_aux(struct blkg_rwstat *to,
 674                                        struct blkg_rwstat *from)
 675 {
 676         struct blkg_rwstat v = blkg_rwstat_read(from);
 677         int i;
 678
 679         for (i = 0; i < BLKG_RWSTAT_NR; i++)
 680                 atomic64_add(atomic64_read(&v.aux_cnt[i]) +
 681                              atomic64_read(&from->aux_cnt[i]),
 682                              &to->aux_cnt[i]);
 683 }
 684
 685 #ifdef CONFIG_BLK_DEV_THROTTLING
 686 extern bool blk_throtl_bio(struct request_queue *q, struct blkcg_gq *blkg,
 687                            struct bio *bio);
 688 #else
 689 static inline bool blk_throtl_bio(struct request_queue *q, struct blkcg_gq *blkg,
 690                                   struct bio *bio) { return false; }
 691 #endif
 692
 693 static inline bool blkcg_bio_issue_check(struct request_queue *q,
 694                                          struct bio *bio)
 695 {
 696         struct blkcg *blkcg;
 697         struct blkcg_gq *blkg;
 698         bool throtl = false;
 699
 700         rcu_read_lock();
 701         blkcg = bio_blkcg(bio);
 702
 703         blkg = blkg_lookup(blkcg, q);
 704         if (unlikely(!blkg)) {
 705                 spin_lock_irq(q->queue_lock);
 706                 blkg = blkg_lookup_create(blkcg, q);
 707                 if (IS_ERR(blkg))
 708                         blkg = NULL;
 709                 spin_unlock_irq(q->queue_lock);
 710         }
 711
 712         throtl = blk_throtl_bio(q, blkg, bio);
 713
 714         if (!throtl) {
 715                 blkg = blkg ?: q->root_blkg;
 716                 blkg_rwstat_add(&blkg->stat_bytes, bio->bi_rw,
 717                                 bio->bi_iter.bi_size);
 718                 blkg_rwstat_add(&blkg->stat_ios, bio->bi_rw, 1);
 719         }
 720
 721         rcu_read_unlock();
 722         return !throtl;
 723 }
 724
 725 #else   /* CONFIG_BLK_CGROUP */
 726
 727 struct blkcg {
 728 };
 729
 730 struct blkg_policy_data {
 731 };
 732
 733 struct blkcg_policy_data {
 734 };
 735
 736 struct blkcg_gq {
 737 };
 738
 739 struct blkcg_policy {
 740 };
 741
 742 #define blkcg_root_css  ((struct cgroup_subsys_state *)ERR_PTR(-EINVAL))
 743
 744 static inline struct cgroup_subsys_state *
 745 task_get_blkcg_css(struct task_struct *task)
 746 {
 747         return NULL;
 748 }
 749
 750 #ifdef CONFIG_BLOCK
 751
 752 static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, void *key) { return NULL; }
 753 static inline int blkcg_init_queue(struct request_queue *q) { return 0; }
 754 static inline void blkcg_drain_queue(struct request_queue *q) { }
 755 static inline void blkcg_exit_queue(struct request_queue *q) { }
 756 static inline int blkcg_policy_register(struct blkcg_policy *pol) { return 0; }
 757 static inline void blkcg_policy_unregister(struct blkcg_policy *pol) { }
 758 static inline int blkcg_activate_policy(struct request_queue *q,
 759                                         const struct blkcg_policy *pol) { return 0; }
 760 static inline void blkcg_deactivate_policy(struct request_queue *q,
 761                                            const struct blkcg_policy *pol) { }
 762
 763 static inline struct blkcg *bio_blkcg(struct bio *bio) { return NULL; }
 764
 765 static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
 766                                                   struct blkcg_policy *pol) { return NULL; }
 767 static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd) { return NULL; }
 768 static inline char *blkg_path(struct blkcg_gq *blkg) { return NULL; }
 769 static inline void blkg_get(struct blkcg_gq *blkg) { }
 770 static inline void blkg_put(struct blkcg_gq *blkg) { }
 771
 772 static inline struct request_list *blk_get_rl(struct request_queue *q,
 773                                               struct bio *bio) { return &q->root_rl; }
 774 static inline void blk_put_rl(struct request_list *rl) { }
 775 static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl) { }
 776 static inline struct request_list *blk_rq_rl(struct request *rq) { return &rq->q->root_rl; }
 777
 778 static inline bool blkcg_bio_issue_check(struct request_queue *q,
 779                                          struct bio *bio) { return true; }
 780
 781 #define blk_queue_for_each_rl(rl, q)    \
 782         for ((rl) = &(q)->root_rl; (rl); (rl) = NULL)
 783
 784 #endif  /* CONFIG_BLOCK */
 785 #endif  /* CONFIG_BLK_CGROUP */
 786 #endif  /* _BLK_CGROUP_H */