include/linux/blk-cgroup.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _BLK_CGROUP_H
   3 #define _BLK_CGROUP_H
   4 /*
   5  * Common Block IO controller cgroup interface
   6  *
   7  * Based on ideas and code from CFQ, CFS and BFQ:
   8  * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
   9  *
  10  * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
  11  *                    Paolo Valente <paolo.valente@unimore.it>
  12  *
  13  * Copyright (C) 2009 Vivek Goyal <vgoyal@redhat.com>
  14  *                    Nauman Rafique <nauman@google.com>
  15  */
  16
  17 #include <linux/cgroup.h>
  18 #include <linux/percpu_counter.h>
  19 #include <linux/seq_file.h>
  20 #include <linux/radix-tree.h>
  21 #include <linux/blkdev.h>
  22 #include <linux/atomic.h>
  23 #include <linux/kthread.h>
  24
  25 /* percpu_counter batch for blkg_[rw]stats, per-cpu drift doesn't matter */
  26 #define BLKG_STAT_CPU_BATCH     (INT_MAX / 2)
  27
  28 /* Max limits for throttle policy */
  29 #define THROTL_IOPS_MAX         UINT_MAX
  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 __rcu           *blkg_hint;
  51         struct hlist_head               blkg_list;
  52
  53         struct blkcg_policy_data        *cpd[BLKCG_MAX_POLS];
  54
  55         struct list_head                all_blkcgs_node;
  56 #ifdef CONFIG_CGROUP_WRITEBACK
  57         struct list_head                cgwb_list;
  58 #endif
  59 };
  60
  61 /*
  62  * blkg_[rw]stat->aux_cnt is excluded for local stats but included for
  63  * recursive.  Used to carry stats of dead children, and, for blkg_rwstat,
  64  * to carry result values from read and sum operations.
  65  */
  66 struct blkg_stat {
  67         struct percpu_counter           cpu_cnt;
  68         atomic64_t                      aux_cnt;
  69 };
  70
  71 struct blkg_rwstat {
  72         struct percpu_counter           cpu_cnt[BLKG_RWSTAT_NR];
  73         atomic64_t                      aux_cnt[BLKG_RWSTAT_NR];
  74 };
  75
  76 /*
  77  * A blkcg_gq (blkg) is association between a block cgroup (blkcg) and a
  78  * request_queue (q).  This is used by blkcg policies which need to track
  79  * information per blkcg - q pair.
  80  *
  81  * There can be multiple active blkcg policies and each blkg:policy pair is
  82  * represented by a blkg_policy_data which is allocated and freed by each
  83  * policy's pd_alloc/free_fn() methods.  A policy can allocate private data
  84  * area by allocating larger data structure which embeds blkg_policy_data
  85  * at the beginning.
  86  */
  87 struct blkg_policy_data {
  88         /* the blkg and policy id this per-policy data belongs to */
  89         struct blkcg_gq                 *blkg;
  90         int                             plid;
  91 };
  92
  93 /*
  94  * Policies that need to keep per-blkcg data which is independent from any
  95  * request_queue associated to it should implement cpd_alloc/free_fn()
  96  * methods.  A policy can allocate private data area by allocating larger
  97  * data structure which embeds blkcg_policy_data at the beginning.
  98  * cpd_init() is invoked to let each policy handle per-blkcg data.
  99  */
 100 struct blkcg_policy_data {
 101         /* the blkcg and policy id this per-policy data belongs to */
 102         struct blkcg                    *blkcg;
 103         int                             plid;
 104 };
 105
 106 /* association between a blk cgroup and a request queue */
 107 struct blkcg_gq {
 108         /* Pointer to the associated request_queue */
 109         struct request_queue            *q;
 110         struct list_head                q_node;
 111         struct hlist_node               blkcg_node;
 112         struct blkcg                    *blkcg;
 113
 114         /*
 115          * Each blkg gets congested separately and the congestion state is
 116          * propagated to the matching bdi_writeback_congested.
 117          */
 118         struct bdi_writeback_congested  *wb_congested;
 119
 120         /* all non-root blkcg_gq's are guaranteed to have access to parent */
 121         struct blkcg_gq                 *parent;
 122
 123         /* request allocation list for this blkcg-q pair */
 124         struct request_list             rl;
 125
 126         /* reference count */
 127         atomic_t                        refcnt;
 128
 129         /* is this blkg online? protected by both blkcg and q locks */
 130         bool                            online;
 131
 132         struct blkg_rwstat              stat_bytes;
 133         struct blkg_rwstat              stat_ios;
 134
 135         struct blkg_policy_data         *pd[BLKCG_MAX_POLS];
 136
 137         struct rcu_head                 rcu_head;
 138 };
 139
 140 typedef struct blkcg_policy_data *(blkcg_pol_alloc_cpd_fn)(gfp_t gfp);
 141 typedef void (blkcg_pol_init_cpd_fn)(struct blkcg_policy_data *cpd);
 142 typedef void (blkcg_pol_free_cpd_fn)(struct blkcg_policy_data *cpd);
 143 typedef void (blkcg_pol_bind_cpd_fn)(struct blkcg_policy_data *cpd);
 144 typedef struct blkg_policy_data *(blkcg_pol_alloc_pd_fn)(gfp_t gfp, int node);
 145 typedef void (blkcg_pol_init_pd_fn)(struct blkg_policy_data *pd);
 146 typedef void (blkcg_pol_online_pd_fn)(struct blkg_policy_data *pd);
 147 typedef void (blkcg_pol_offline_pd_fn)(struct blkg_policy_data *pd);
 148 typedef void (blkcg_pol_free_pd_fn)(struct blkg_policy_data *pd);
 149 typedef void (blkcg_pol_reset_pd_stats_fn)(struct blkg_policy_data *pd);
 150
 151 struct blkcg_policy {
 152         int                             plid;
 153         /* cgroup files for the policy */
 154         struct cftype                   *dfl_cftypes;
 155         struct cftype                   *legacy_cftypes;
 156
 157         /* operations */
 158         blkcg_pol_alloc_cpd_fn          *cpd_alloc_fn;
 159         blkcg_pol_init_cpd_fn           *cpd_init_fn;
 160         blkcg_pol_free_cpd_fn           *cpd_free_fn;
 161         blkcg_pol_bind_cpd_fn           *cpd_bind_fn;
 162
 163         blkcg_pol_alloc_pd_fn           *pd_alloc_fn;
 164         blkcg_pol_init_pd_fn            *pd_init_fn;
 165         blkcg_pol_online_pd_fn          *pd_online_fn;
 166         blkcg_pol_offline_pd_fn         *pd_offline_fn;
 167         blkcg_pol_free_pd_fn            *pd_free_fn;
 168         blkcg_pol_reset_pd_stats_fn     *pd_reset_stats_fn;
 169 };
 170
 171 extern struct blkcg blkcg_root;
 172 extern struct cgroup_subsys_state * const blkcg_root_css;
 173
 174 struct blkcg_gq *blkg_lookup_slowpath(struct blkcg *blkcg,
 175                                       struct request_queue *q, bool update_hint);
 176 struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg,
 177                                     struct request_queue *q);
 178 int blkcg_init_queue(struct request_queue *q);
 179 void blkcg_drain_queue(struct request_queue *q);
 180 void blkcg_exit_queue(struct request_queue *q);
 181
 182 /* Blkio controller policy registration */
 183 int blkcg_policy_register(struct blkcg_policy *pol);
 184 void blkcg_policy_unregister(struct blkcg_policy *pol);
 185 int blkcg_activate_policy(struct request_queue *q,
 186                           const struct blkcg_policy *pol);
 187 void blkcg_deactivate_policy(struct request_queue *q,
 188                              const struct blkcg_policy *pol);
 189
 190 const char *blkg_dev_name(struct blkcg_gq *blkg);
 191 void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg,
 192                        u64 (*prfill)(struct seq_file *,
 193                                      struct blkg_policy_data *, int),
 194                        const struct blkcg_policy *pol, int data,
 195                        bool show_total);
 196 u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v);
 197 u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
 198                          const struct blkg_rwstat *rwstat);
 199 u64 blkg_prfill_stat(struct seq_file *sf, struct blkg_policy_data *pd, int off);
 200 u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd,
 201                        int off);
 202 int blkg_print_stat_bytes(struct seq_file *sf, void *v);
 203 int blkg_print_stat_ios(struct seq_file *sf, void *v);
 204 int blkg_print_stat_bytes_recursive(struct seq_file *sf, void *v);
 205 int blkg_print_stat_ios_recursive(struct seq_file *sf, void *v);
 206
 207 u64 blkg_stat_recursive_sum(struct blkcg_gq *blkg,
 208                             struct blkcg_policy *pol, int off);
 209 struct blkg_rwstat blkg_rwstat_recursive_sum(struct blkcg_gq *blkg,
 210                                              struct blkcg_policy *pol, int off);
 211
 212 struct blkg_conf_ctx {
 213         struct gendisk                  *disk;
 214         struct blkcg_gq                 *blkg;
 215         char                            *body;
 216 };
 217
 218 int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
 219                    char *input, struct blkg_conf_ctx *ctx);
 220 void blkg_conf_finish(struct blkg_conf_ctx *ctx);
 221
 222
 223 static inline struct blkcg *css_to_blkcg(struct cgroup_subsys_state *css)
 224 {
 225         return css ? container_of(css, struct blkcg, css) : NULL;
 226 }
 227
 228 static inline struct blkcg *bio_blkcg(struct bio *bio)
 229 {
 230         struct cgroup_subsys_state *css;
 231
 232         if (bio && bio->bi_css)
 233                 return css_to_blkcg(bio->bi_css);
 234         css = kthread_blkcg();
 235         if (css)
 236                 return css_to_blkcg(css);
 237         return css_to_blkcg(task_css(current, io_cgrp_id));
 238 }
 239
 240 /**
 241  * blkcg_parent - get the parent of a blkcg
 242  * @blkcg: blkcg of interest
 243  *
 244  * Return the parent blkcg of @blkcg.  Can be called anytime.
 245  */
 246 static inline struct blkcg *blkcg_parent(struct blkcg *blkcg)
 247 {
 248         return css_to_blkcg(blkcg->css.parent);
 249 }
 250
 251 /**
 252  * __blkg_lookup - internal version of blkg_lookup()
 253  * @blkcg: blkcg of interest
 254  * @q: request_queue of interest
 255  * @update_hint: whether to update lookup hint with the result or not
 256  *
 257  * This is internal version and shouldn't be used by policy
 258  * implementations.  Looks up blkgs for the @blkcg - @q pair regardless of
 259  * @q's bypass state.  If @update_hint is %true, the caller should be
 260  * holding @q->queue_lock and lookup hint is updated on success.
 261  */
 262 static inline struct blkcg_gq *__blkg_lookup(struct blkcg *blkcg,
 263                                              struct request_queue *q,
 264                                              bool update_hint)
 265 {
 266         struct blkcg_gq *blkg;
 267
 268         if (blkcg == &blkcg_root)
 269                 return q->root_blkg;
 270
 271         blkg = rcu_dereference(blkcg->blkg_hint);
 272         if (blkg && blkg->q == q)
 273                 return blkg;
 274
 275         return blkg_lookup_slowpath(blkcg, q, update_hint);
 276 }
 277
 278 /**
 279  * blkg_lookup - lookup blkg for the specified blkcg - q pair
 280  * @blkcg: blkcg of interest
 281  * @q: request_queue of interest
 282  *
 283  * Lookup blkg for the @blkcg - @q pair.  This function should be called
 284  * under RCU read lock and is guaranteed to return %NULL if @q is bypassing
 285  * - see blk_queue_bypass_start() for details.
 286  */
 287 static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg,
 288                                            struct request_queue *q)
 289 {
 290         WARN_ON_ONCE(!rcu_read_lock_held());
 291
 292         if (unlikely(blk_queue_bypass(q)))
 293                 return NULL;
 294         return __blkg_lookup(blkcg, q, false);
 295 }
 296
 297 /**
 298  * blkg_lookup - look up blkg for the specified request queue
 299  * @q: request_queue of interest
 300  *
 301  * Lookup blkg for @q at the root level. See also blkg_lookup().
 302  */
 303 static inline struct blkcg_gq *blkg_root_lookup(struct request_queue *q)
 304 {
 305         struct blkcg_gq *blkg;
 306
 307         rcu_read_lock();
 308         blkg = blkg_lookup(&blkcg_root, q);
 309         rcu_read_unlock();
 310
 311         return blkg;
 312 }
 313
 314 /**
 315  * blkg_to_pdata - get policy private data
 316  * @blkg: blkg of interest
 317  * @pol: policy of interest
 318  *
 319  * Return pointer to private data associated with the @blkg-@pol pair.
 320  */
 321 static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
 322                                                   struct blkcg_policy *pol)
 323 {
 324         return blkg ? blkg->pd[pol->plid] : NULL;
 325 }
 326
 327 static inline struct blkcg_policy_data *blkcg_to_cpd(struct blkcg *blkcg,
 328                                                      struct blkcg_policy *pol)
 329 {
 330         return blkcg ? blkcg->cpd[pol->plid] : NULL;
 331 }
 332
 333 /**
 334  * pdata_to_blkg - get blkg associated with policy private data
 335  * @pd: policy private data of interest
 336  *
 337  * @pd is policy private data.  Determine the blkg it's associated with.
 338  */
 339 static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd)
 340 {
 341         return pd ? pd->blkg : NULL;
 342 }
 343
 344 static inline struct blkcg *cpd_to_blkcg(struct blkcg_policy_data *cpd)
 345 {
 346         return cpd ? cpd->blkcg : NULL;
 347 }
 348
 349 /**
 350  * blkg_path - format cgroup path of blkg
 351  * @blkg: blkg of interest
 352  * @buf: target buffer
 353  * @buflen: target buffer length
 354  *
 355  * Format the path of the cgroup of @blkg into @buf.
 356  */
 357 static inline int blkg_path(struct blkcg_gq *blkg, char *buf, int buflen)
 358 {
 359         return cgroup_path(blkg->blkcg->css.cgroup, buf, buflen);
 360 }
 361
 362 /**
 363  * blkg_get - get a blkg reference
 364  * @blkg: blkg to get
 365  *
 366  * The caller should be holding an existing reference.
 367  */
 368 static inline void blkg_get(struct blkcg_gq *blkg)
 369 {
 370         WARN_ON_ONCE(atomic_read(&blkg->refcnt) <= 0);
 371         atomic_inc(&blkg->refcnt);
 372 }
 373
 374 void __blkg_release_rcu(struct rcu_head *rcu);
 375
 376 /**
 377  * blkg_put - put a blkg reference
 378  * @blkg: blkg to put
 379  */
 380 static inline void blkg_put(struct blkcg_gq *blkg)
 381 {
 382         WARN_ON_ONCE(atomic_read(&blkg->refcnt) <= 0);
 383         if (atomic_dec_and_test(&blkg->refcnt))
 384                 call_rcu(&blkg->rcu_head, __blkg_release_rcu);
 385 }
 386
 387 /**
 388  * blkg_for_each_descendant_pre - pre-order walk of a blkg's descendants
 389  * @d_blkg: loop cursor pointing to the current descendant
 390  * @pos_css: used for iteration
 391  * @p_blkg: target blkg to walk descendants of
 392  *
 393  * Walk @c_blkg through the descendants of @p_blkg.  Must be used with RCU
 394  * read locked.  If called under either blkcg or queue lock, the iteration
 395  * is guaranteed to include all and only online blkgs.  The caller may
 396  * update @pos_css by calling css_rightmost_descendant() to skip subtree.
 397  * @p_blkg is included in the iteration and the first node to be visited.
 398  */
 399 #define blkg_for_each_descendant_pre(d_blkg, pos_css, p_blkg)           \
 400         css_for_each_descendant_pre((pos_css), &(p_blkg)->blkcg->css)   \
 401                 if (((d_blkg) = __blkg_lookup(css_to_blkcg(pos_css),    \
 402                                               (p_blkg)->q, false)))
 403
 404 /**
 405  * blkg_for_each_descendant_post - post-order walk of a blkg's descendants
 406  * @d_blkg: loop cursor pointing to the current descendant
 407  * @pos_css: used for iteration
 408  * @p_blkg: target blkg to walk descendants of
 409  *
 410  * Similar to blkg_for_each_descendant_pre() but performs post-order
 411  * traversal instead.  Synchronization rules are the same.  @p_blkg is
 412  * included in the iteration and the last node to be visited.
 413  */
 414 #define blkg_for_each_descendant_post(d_blkg, pos_css, p_blkg)          \
 415         css_for_each_descendant_post((pos_css), &(p_blkg)->blkcg->css)  \
 416                 if (((d_blkg) = __blkg_lookup(css_to_blkcg(pos_css),    \
 417                                               (p_blkg)->q, false)))
 418
 419 /**
 420  * blk_get_rl - get request_list to use
 421  * @q: request_queue of interest
 422  * @bio: bio which will be attached to the allocated request (may be %NULL)
 423  *
 424  * The caller wants to allocate a request from @q to use for @bio.  Find
 425  * the request_list to use and obtain a reference on it.  Should be called
 426  * under queue_lock.  This function is guaranteed to return non-%NULL
 427  * request_list.
 428  */
 429 static inline struct request_list *blk_get_rl(struct request_queue *q,
 430                                               struct bio *bio)
 431 {
 432         struct blkcg *blkcg;
 433         struct blkcg_gq *blkg;
 434
 435         rcu_read_lock();
 436
 437         blkcg = bio_blkcg(bio);
 438
 439         /* bypass blkg lookup and use @q->root_rl directly for root */
 440         if (blkcg == &blkcg_root)
 441                 goto root_rl;
 442
 443         /*
 444          * Try to use blkg->rl.  blkg lookup may fail under memory pressure
 445          * or if either the blkcg or queue is going away.  Fall back to
 446          * root_rl in such cases.
 447          */
 448         blkg = blkg_lookup(blkcg, q);
 449         if (unlikely(!blkg))
 450                 goto root_rl;
 451
 452         blkg_get(blkg);
 453         rcu_read_unlock();
 454         return &blkg->rl;
 455 root_rl:
 456         rcu_read_unlock();
 457         return &q->root_rl;
 458 }
 459
 460 /**
 461  * blk_put_rl - put request_list
 462  * @rl: request_list to put
 463  *
 464  * Put the reference acquired by blk_get_rl().  Should be called under
 465  * queue_lock.
 466  */
 467 static inline void blk_put_rl(struct request_list *rl)
 468 {
 469         if (rl->blkg->blkcg != &blkcg_root)
 470                 blkg_put(rl->blkg);
 471 }
 472
 473 /**
 474  * blk_rq_set_rl - associate a request with a request_list
 475  * @rq: request of interest
 476  * @rl: target request_list
 477  *
 478  * Associate @rq with @rl so that accounting and freeing can know the
 479  * request_list @rq came from.
 480  */
 481 static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl)
 482 {
 483         rq->rl = rl;
 484 }
 485
 486 /**
 487  * blk_rq_rl - return the request_list a request came from
 488  * @rq: request of interest
 489  *
 490  * Return the request_list @rq is allocated from.
 491  */
 492 static inline struct request_list *blk_rq_rl(struct request *rq)
 493 {
 494         return rq->rl;
 495 }
 496
 497 struct request_list *__blk_queue_next_rl(struct request_list *rl,
 498                                          struct request_queue *q);
 499 /**
 500  * blk_queue_for_each_rl - iterate through all request_lists of a request_queue
 501  *
 502  * Should be used under queue_lock.
 503  */
 504 #define blk_queue_for_each_rl(rl, q)    \
 505         for ((rl) = &(q)->root_rl; (rl); (rl) = __blk_queue_next_rl((rl), (q)))
 506
 507 static inline int blkg_stat_init(struct blkg_stat *stat, gfp_t gfp)
 508 {
 509         int ret;
 510
 511         ret = percpu_counter_init(&stat->cpu_cnt, 0, gfp);
 512         if (ret)
 513                 return ret;
 514
 515         atomic64_set(&stat->aux_cnt, 0);
 516         return 0;
 517 }
 518
 519 static inline void blkg_stat_exit(struct blkg_stat *stat)
 520 {
 521         percpu_counter_destroy(&stat->cpu_cnt);
 522 }
 523
 524 /**
 525  * blkg_stat_add - add a value to a blkg_stat
 526  * @stat: target blkg_stat
 527  * @val: value to add
 528  *
 529  * Add @val to @stat.  The caller must ensure that IRQ on the same CPU
 530  * don't re-enter this function for the same counter.
 531  */
 532 static inline void blkg_stat_add(struct blkg_stat *stat, uint64_t val)
 533 {
 534         percpu_counter_add_batch(&stat->cpu_cnt, val, BLKG_STAT_CPU_BATCH);
 535 }
 536
 537 /**
 538  * blkg_stat_read - read the current value of a blkg_stat
 539  * @stat: blkg_stat to read
 540  */
 541 static inline uint64_t blkg_stat_read(struct blkg_stat *stat)
 542 {
 543         return percpu_counter_sum_positive(&stat->cpu_cnt);
 544 }
 545
 546 /**
 547  * blkg_stat_reset - reset a blkg_stat
 548  * @stat: blkg_stat to reset
 549  */
 550 static inline void blkg_stat_reset(struct blkg_stat *stat)
 551 {
 552         percpu_counter_set(&stat->cpu_cnt, 0);
 553         atomic64_set(&stat->aux_cnt, 0);
 554 }
 555
 556 /**
 557  * blkg_stat_add_aux - add a blkg_stat into another's aux count
 558  * @to: the destination blkg_stat
 559  * @from: the source
 560  *
 561  * Add @from's count including the aux one to @to's aux count.
 562  */
 563 static inline void blkg_stat_add_aux(struct blkg_stat *to,
 564                                      struct blkg_stat *from)
 565 {
 566         atomic64_add(blkg_stat_read(from) + atomic64_read(&from->aux_cnt),
 567                      &to->aux_cnt);
 568 }
 569
 570 static inline int blkg_rwstat_init(struct blkg_rwstat *rwstat, gfp_t gfp)
 571 {
 572         int i, ret;
 573
 574         for (i = 0; i < BLKG_RWSTAT_NR; i++) {
 575                 ret = percpu_counter_init(&rwstat->cpu_cnt[i], 0, gfp);
 576                 if (ret) {
 577                         while (--i >= 0)
 578                                 percpu_counter_destroy(&rwstat->cpu_cnt[i]);
 579                         return ret;
 580                 }
 581                 atomic64_set(&rwstat->aux_cnt[i], 0);
 582         }
 583         return 0;
 584 }
 585
 586 static inline void blkg_rwstat_exit(struct blkg_rwstat *rwstat)
 587 {
 588         int i;
 589
 590         for (i = 0; i < BLKG_RWSTAT_NR; i++)
 591                 percpu_counter_destroy(&rwstat->cpu_cnt[i]);
 592 }
 593
 594 /**
 595  * blkg_rwstat_add - add a value to a blkg_rwstat
 596  * @rwstat: target blkg_rwstat
 597  * @op: REQ_OP and flags
 598  * @val: value to add
 599  *
 600  * Add @val to @rwstat.  The counters are chosen according to @rw.  The
 601  * caller is responsible for synchronizing calls to this function.
 602  */
 603 static inline void blkg_rwstat_add(struct blkg_rwstat *rwstat,
 604                                    unsigned int op, uint64_t val)
 605 {
 606         struct percpu_counter *cnt;
 607
 608         if (op_is_write(op))
 609                 cnt = &rwstat->cpu_cnt[BLKG_RWSTAT_WRITE];
 610         else
 611                 cnt = &rwstat->cpu_cnt[BLKG_RWSTAT_READ];
 612
 613         percpu_counter_add_batch(cnt, val, BLKG_STAT_CPU_BATCH);
 614
 615         if (op_is_sync(op))
 616                 cnt = &rwstat->cpu_cnt[BLKG_RWSTAT_SYNC];
 617         else
 618                 cnt = &rwstat->cpu_cnt[BLKG_RWSTAT_ASYNC];
 619
 620         percpu_counter_add_batch(cnt, val, BLKG_STAT_CPU_BATCH);
 621 }
 622
 623 /**
 624  * blkg_rwstat_read - read the current values of a blkg_rwstat
 625  * @rwstat: blkg_rwstat to read
 626  *
 627  * Read the current snapshot of @rwstat and return it in the aux counts.
 628  */
 629 static inline struct blkg_rwstat blkg_rwstat_read(struct blkg_rwstat *rwstat)
 630 {
 631         struct blkg_rwstat result;
 632         int i;
 633
 634         for (i = 0; i < BLKG_RWSTAT_NR; i++)
 635                 atomic64_set(&result.aux_cnt[i],
 636                              percpu_counter_sum_positive(&rwstat->cpu_cnt[i]));
 637         return result;
 638 }
 639
 640 /**
 641  * blkg_rwstat_total - read the total count of a blkg_rwstat
 642  * @rwstat: blkg_rwstat to read
 643  *
 644  * Return the total count of @rwstat regardless of the IO direction.  This
 645  * function can be called without synchronization and takes care of u64
 646  * atomicity.
 647  */
 648 static inline uint64_t blkg_rwstat_total(struct blkg_rwstat *rwstat)
 649 {
 650         struct blkg_rwstat tmp = blkg_rwstat_read(rwstat);
 651
 652         return atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_READ]) +
 653                 atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_WRITE]);
 654 }
 655
 656 /**
 657  * blkg_rwstat_reset - reset a blkg_rwstat
 658  * @rwstat: blkg_rwstat to reset
 659  */
 660 static inline void blkg_rwstat_reset(struct blkg_rwstat *rwstat)
 661 {
 662         int i;
 663
 664         for (i = 0; i < BLKG_RWSTAT_NR; i++) {
 665                 percpu_counter_set(&rwstat->cpu_cnt[i], 0);
 666                 atomic64_set(&rwstat->aux_cnt[i], 0);
 667         }
 668 }
 669
 670 /**
 671  * blkg_rwstat_add_aux - add a blkg_rwstat into another's aux count
 672  * @to: the destination blkg_rwstat
 673  * @from: the source
 674  *
 675  * Add @from's count including the aux one to @to's aux count.
 676  */
 677 static inline void blkg_rwstat_add_aux(struct blkg_rwstat *to,
 678                                        struct blkg_rwstat *from)
 679 {
 680         struct blkg_rwstat v = blkg_rwstat_read(from);
 681         int i;
 682
 683         for (i = 0; i < BLKG_RWSTAT_NR; i++)
 684                 atomic64_add(atomic64_read(&v.aux_cnt[i]) +
 685                              atomic64_read(&from->aux_cnt[i]),
 686                              &to->aux_cnt[i]);
 687 }
 688
 689 #ifdef CONFIG_BLK_DEV_THROTTLING
 690 extern bool blk_throtl_bio(struct request_queue *q, struct blkcg_gq *blkg,
 691                            struct bio *bio);
 692 #else
 693 static inline bool blk_throtl_bio(struct request_queue *q, struct blkcg_gq *blkg,
 694                                   struct bio *bio) { return false; }
 695 #endif
 696
 697 static inline bool blkcg_bio_issue_check(struct request_queue *q,
 698                                          struct bio *bio)
 699 {
 700         struct blkcg *blkcg;
 701         struct blkcg_gq *blkg;
 702         bool throtl = false;
 703
 704         rcu_read_lock();
 705         blkcg = bio_blkcg(bio);
 706
 707         /* associate blkcg if bio hasn't attached one */
 708         bio_associate_blkcg(bio, &blkcg->css);
 709
 710         blkg = blkg_lookup(blkcg, q);
 711         if (unlikely(!blkg)) {
 712                 spin_lock_irq(q->queue_lock);
 713                 blkg = blkg_lookup_create(blkcg, q);
 714                 if (IS_ERR(blkg))
 715                         blkg = NULL;
 716                 spin_unlock_irq(q->queue_lock);
 717         }
 718
 719         throtl = blk_throtl_bio(q, blkg, bio);
 720
 721         if (!throtl) {
 722                 blkg = blkg ?: q->root_blkg;
 723                 blkg_rwstat_add(&blkg->stat_bytes, bio->bi_opf,
 724                                 bio->bi_iter.bi_size);
 725                 blkg_rwstat_add(&blkg->stat_ios, bio->bi_opf, 1);
 726         }
 727
 728         rcu_read_unlock();
 729         return !throtl;
 730 }
 731
 732 #else   /* CONFIG_BLK_CGROUP */
 733
 734 struct blkcg {
 735 };
 736
 737 struct blkg_policy_data {
 738 };
 739
 740 struct blkcg_policy_data {
 741 };
 742
 743 struct blkcg_gq {
 744 };
 745
 746 struct blkcg_policy {
 747 };
 748
 749 #define blkcg_root_css  ((struct cgroup_subsys_state *)ERR_PTR(-EINVAL))
 750
 751 #ifdef CONFIG_BLOCK
 752
 753 static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, void *key) { return NULL; }
 754 static inline struct blkcg_gq *blkg_root_lookup(struct request_queue *q) { return NULL; }
 755 static inline int blkcg_init_queue(struct request_queue *q) { return 0; }
 756 static inline void blkcg_drain_queue(struct request_queue *q) { }
 757 static inline void blkcg_exit_queue(struct request_queue *q) { }
 758 static inline int blkcg_policy_register(struct blkcg_policy *pol) { return 0; }
 759 static inline void blkcg_policy_unregister(struct blkcg_policy *pol) { }
 760 static inline int blkcg_activate_policy(struct request_queue *q,
 761                                         const struct blkcg_policy *pol) { return 0; }
 762 static inline void blkcg_deactivate_policy(struct request_queue *q,
 763                                            const struct blkcg_policy *pol) { }
 764
 765 static inline struct blkcg *bio_blkcg(struct bio *bio) { return NULL; }
 766
 767 static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg,
 768                                                   struct blkcg_policy *pol) { return NULL; }
 769 static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd) { return NULL; }
 770 static inline char *blkg_path(struct blkcg_gq *blkg) { return NULL; }
 771 static inline void blkg_get(struct blkcg_gq *blkg) { }
 772 static inline void blkg_put(struct blkcg_gq *blkg) { }
 773
 774 static inline struct request_list *blk_get_rl(struct request_queue *q,
 775                                               struct bio *bio) { return &q->root_rl; }
 776 static inline void blk_put_rl(struct request_list *rl) { }
 777 static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl) { }
 778 static inline struct request_list *blk_rq_rl(struct request *rq) { return &rq->q->root_rl; }
 779
 780 static inline bool blkcg_bio_issue_check(struct request_queue *q,
 781                                          struct bio *bio) { return true; }
 782
 783 #define blk_queue_for_each_rl(rl, q)    \
 784         for ((rl) = &(q)->root_rl; (rl); (rl) = NULL)
 785
 786 #endif  /* CONFIG_BLOCK */
 787 #endif  /* CONFIG_BLK_CGROUP */
 788 #endif  /* _BLK_CGROUP_H */