1 #ifndef _BLK_CGROUP_H 2 #define _BLK_CGROUP_H 3 /* 4 * Common Block IO controller cgroup interface 5 * 6 * Based on ideas and code from CFQ, CFS and BFQ: 7 * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk> 8 * 9 * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it> 10 * Paolo Valente <paolo.valente@unimore.it> 11 * 12 * Copyright (C) 2009 Vivek Goyal <vgoyal@redhat.com> 13 * Nauman Rafique <nauman@google.com> 14 */ 15 16 #include <linux/cgroup.h> 17 #include <linux/u64_stats_sync.h> 18 #include <linux/seq_file.h> 19 #include <linux/radix-tree.h> 20 #include <linux/blkdev.h> 21 22 /* Max limits for throttle policy */ 23 #define THROTL_IOPS_MAX UINT_MAX 24 25 /* CFQ specific, out here for blkcg->cfq_weight */ 26 #define CFQ_WEIGHT_MIN 10 27 #define CFQ_WEIGHT_MAX 1000 28 #define CFQ_WEIGHT_DEFAULT 500 29 30 #ifdef CONFIG_BLK_CGROUP 31 32 enum blkg_rwstat_type { 33 BLKG_RWSTAT_READ, 34 BLKG_RWSTAT_WRITE, 35 BLKG_RWSTAT_SYNC, 36 BLKG_RWSTAT_ASYNC, 37 38 BLKG_RWSTAT_NR, 39 BLKG_RWSTAT_TOTAL = BLKG_RWSTAT_NR, 40 }; 41 42 struct blkcg_gq; 43 44 struct blkcg { 45 struct cgroup_subsys_state css; 46 spinlock_t lock; 47 48 struct radix_tree_root blkg_tree; 49 struct blkcg_gq *blkg_hint; 50 struct hlist_head blkg_list; 51 52 /* for policies to test whether associated blkcg has changed */ 53 uint64_t id; 54 55 /* TODO: per-policy storage in blkcg */ 56 unsigned int cfq_weight; /* belongs to cfq */ 57 unsigned int cfq_leaf_weight; 58 }; 59 60 struct blkg_stat { 61 struct u64_stats_sync syncp; 62 uint64_t cnt; 63 }; 64 65 struct blkg_rwstat { 66 struct u64_stats_sync syncp; 67 uint64_t cnt[BLKG_RWSTAT_NR]; 68 }; 69 70 /* 71 * A blkcg_gq (blkg) is association between a block cgroup (blkcg) and a 72 * request_queue (q). This is used by blkcg policies which need to track 73 * information per blkcg - q pair. 74 * 75 * There can be multiple active blkcg policies and each has its private 76 * data on each blkg, the size of which is determined by 77 * blkcg_policy->pd_size. blkcg core allocates and frees such areas 78 * together with blkg and invokes pd_init/exit_fn() methods. 79 * 80 * Such private data must embed struct blkg_policy_data (pd) at the 81 * beginning and pd_size can't be smaller than pd. 82 */ 83 struct blkg_policy_data { 84 /* the blkg and policy id this per-policy data belongs to */ 85 struct blkcg_gq *blkg; 86 int plid; 87 88 /* used during policy activation */ 89 struct list_head alloc_node; 90 }; 91 92 /* association between a blk cgroup and a request queue */ 93 struct blkcg_gq { 94 /* Pointer to the associated request_queue */ 95 struct request_queue *q; 96 struct list_head q_node; 97 struct hlist_node blkcg_node; 98 struct blkcg *blkcg; 99 100 /* all non-root blkcg_gq's are guaranteed to have access to parent */ 101 struct blkcg_gq *parent; 102 103 /* request allocation list for this blkcg-q pair */ 104 struct request_list rl; 105 106 /* reference count */ 107 int refcnt; 108 109 /* is this blkg online? protected by both blkcg and q locks */ 110 bool online; 111 112 struct blkg_policy_data *pd[BLKCG_MAX_POLS]; 113 114 struct rcu_head rcu_head; 115 }; 116 117 typedef void (blkcg_pol_init_pd_fn)(struct blkcg_gq *blkg); 118 typedef void (blkcg_pol_online_pd_fn)(struct blkcg_gq *blkg); 119 typedef void (blkcg_pol_offline_pd_fn)(struct blkcg_gq *blkg); 120 typedef void (blkcg_pol_exit_pd_fn)(struct blkcg_gq *blkg); 121 typedef void (blkcg_pol_reset_pd_stats_fn)(struct blkcg_gq *blkg); 122 123 struct blkcg_policy { 124 int plid; 125 /* policy specific private data size */ 126 size_t pd_size; 127 /* cgroup files for the policy */ 128 struct cftype *cftypes; 129 130 /* operations */ 131 blkcg_pol_init_pd_fn *pd_init_fn; 132 blkcg_pol_online_pd_fn *pd_online_fn; 133 blkcg_pol_offline_pd_fn *pd_offline_fn; 134 blkcg_pol_exit_pd_fn *pd_exit_fn; 135 blkcg_pol_reset_pd_stats_fn *pd_reset_stats_fn; 136 }; 137 138 extern struct blkcg blkcg_root; 139 140 struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, struct request_queue *q); 141 struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg, 142 struct request_queue *q); 143 int blkcg_init_queue(struct request_queue *q); 144 void blkcg_drain_queue(struct request_queue *q); 145 void blkcg_exit_queue(struct request_queue *q); 146 147 /* Blkio controller policy registration */ 148 int blkcg_policy_register(struct blkcg_policy *pol); 149 void blkcg_policy_unregister(struct blkcg_policy *pol); 150 int blkcg_activate_policy(struct request_queue *q, 151 const struct blkcg_policy *pol); 152 void blkcg_deactivate_policy(struct request_queue *q, 153 const struct blkcg_policy *pol); 154 155 void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg, 156 u64 (*prfill)(struct seq_file *, 157 struct blkg_policy_data *, int), 158 const struct blkcg_policy *pol, int data, 159 bool show_total); 160 u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v); 161 u64 __blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd, 162 const struct blkg_rwstat *rwstat); 163 u64 blkg_prfill_stat(struct seq_file *sf, struct blkg_policy_data *pd, int off); 164 u64 blkg_prfill_rwstat(struct seq_file *sf, struct blkg_policy_data *pd, 165 int off); 166 167 u64 blkg_stat_recursive_sum(struct blkg_policy_data *pd, int off); 168 struct blkg_rwstat blkg_rwstat_recursive_sum(struct blkg_policy_data *pd, 169 int off); 170 171 struct blkg_conf_ctx { 172 struct gendisk *disk; 173 struct blkcg_gq *blkg; 174 u64 v; 175 }; 176 177 int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol, 178 const char *input, struct blkg_conf_ctx *ctx); 179 void blkg_conf_finish(struct blkg_conf_ctx *ctx); 180 181 182 static inline struct blkcg *css_to_blkcg(struct cgroup_subsys_state *css) 183 { 184 return css ? container_of(css, struct blkcg, css) : NULL; 185 } 186 187 static inline struct blkcg *task_blkcg(struct task_struct *tsk) 188 { 189 return css_to_blkcg(task_css(tsk, blkio_subsys_id)); 190 } 191 192 static inline struct blkcg *bio_blkcg(struct bio *bio) 193 { 194 if (bio && bio->bi_css) 195 return css_to_blkcg(bio->bi_css); 196 return task_blkcg(current); 197 } 198 199 /** 200 * blkcg_parent - get the parent of a blkcg 201 * @blkcg: blkcg of interest 202 * 203 * Return the parent blkcg of @blkcg. Can be called anytime. 204 */ 205 static inline struct blkcg *blkcg_parent(struct blkcg *blkcg) 206 { 207 return css_to_blkcg(css_parent(&blkcg->css)); 208 } 209 210 /** 211 * blkg_to_pdata - get policy private data 212 * @blkg: blkg of interest 213 * @pol: policy of interest 214 * 215 * Return pointer to private data associated with the @blkg-@pol pair. 216 */ 217 static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg, 218 struct blkcg_policy *pol) 219 { 220 return blkg ? blkg->pd[pol->plid] : NULL; 221 } 222 223 /** 224 * pdata_to_blkg - get blkg associated with policy private data 225 * @pd: policy private data of interest 226 * 227 * @pd is policy private data. Determine the blkg it's associated with. 228 */ 229 static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd) 230 { 231 return pd ? pd->blkg : NULL; 232 } 233 234 /** 235 * blkg_path - format cgroup path of blkg 236 * @blkg: blkg of interest 237 * @buf: target buffer 238 * @buflen: target buffer length 239 * 240 * Format the path of the cgroup of @blkg into @buf. 241 */ 242 static inline int blkg_path(struct blkcg_gq *blkg, char *buf, int buflen) 243 { 244 int ret; 245 246 ret = cgroup_path(blkg->blkcg->css.cgroup, buf, buflen); 247 if (ret) 248 strncpy(buf, "<unavailable>", buflen); 249 return ret; 250 } 251 252 /** 253 * blkg_get - get a blkg reference 254 * @blkg: blkg to get 255 * 256 * The caller should be holding queue_lock and an existing reference. 257 */ 258 static inline void blkg_get(struct blkcg_gq *blkg) 259 { 260 lockdep_assert_held(blkg->q->queue_lock); 261 WARN_ON_ONCE(!blkg->refcnt); 262 blkg->refcnt++; 263 } 264 265 void __blkg_release_rcu(struct rcu_head *rcu); 266 267 /** 268 * blkg_put - put a blkg reference 269 * @blkg: blkg to put 270 * 271 * The caller should be holding queue_lock. 272 */ 273 static inline void blkg_put(struct blkcg_gq *blkg) 274 { 275 lockdep_assert_held(blkg->q->queue_lock); 276 WARN_ON_ONCE(blkg->refcnt <= 0); 277 if (!--blkg->refcnt) 278 call_rcu(&blkg->rcu_head, __blkg_release_rcu); 279 } 280 281 struct blkcg_gq *__blkg_lookup(struct blkcg *blkcg, struct request_queue *q, 282 bool update_hint); 283 284 /** 285 * blkg_for_each_descendant_pre - pre-order walk of a blkg's descendants 286 * @d_blkg: loop cursor pointing to the current descendant 287 * @pos_css: used for iteration 288 * @p_blkg: target blkg to walk descendants of 289 * 290 * Walk @c_blkg through the descendants of @p_blkg. Must be used with RCU 291 * read locked. If called under either blkcg or queue lock, the iteration 292 * is guaranteed to include all and only online blkgs. The caller may 293 * update @pos_css by calling css_rightmost_descendant() to skip subtree. 294 * @p_blkg is included in the iteration and the first node to be visited. 295 */ 296 #define blkg_for_each_descendant_pre(d_blkg, pos_css, p_blkg) \ 297 css_for_each_descendant_pre((pos_css), &(p_blkg)->blkcg->css) \ 298 if (((d_blkg) = __blkg_lookup(css_to_blkcg(pos_css), \ 299 (p_blkg)->q, false))) 300 301 /** 302 * blkg_for_each_descendant_post - post-order walk of a blkg's descendants 303 * @d_blkg: loop cursor pointing to the current descendant 304 * @pos_css: used for iteration 305 * @p_blkg: target blkg to walk descendants of 306 * 307 * Similar to blkg_for_each_descendant_pre() but performs post-order 308 * traversal instead. Synchronization rules are the same. @p_blkg is 309 * included in the iteration and the last node to be visited. 310 */ 311 #define blkg_for_each_descendant_post(d_blkg, pos_css, p_blkg) \ 312 css_for_each_descendant_post((pos_css), &(p_blkg)->blkcg->css) \ 313 if (((d_blkg) = __blkg_lookup(css_to_blkcg(pos_css), \ 314 (p_blkg)->q, false))) 315 316 /** 317 * blk_get_rl - get request_list to use 318 * @q: request_queue of interest 319 * @bio: bio which will be attached to the allocated request (may be %NULL) 320 * 321 * The caller wants to allocate a request from @q to use for @bio. Find 322 * the request_list to use and obtain a reference on it. Should be called 323 * under queue_lock. This function is guaranteed to return non-%NULL 324 * request_list. 325 */ 326 static inline struct request_list *blk_get_rl(struct request_queue *q, 327 struct bio *bio) 328 { 329 struct blkcg *blkcg; 330 struct blkcg_gq *blkg; 331 332 rcu_read_lock(); 333 334 blkcg = bio_blkcg(bio); 335 336 /* bypass blkg lookup and use @q->root_rl directly for root */ 337 if (blkcg == &blkcg_root) 338 goto root_rl; 339 340 /* 341 * Try to use blkg->rl. blkg lookup may fail under memory pressure 342 * or if either the blkcg or queue is going away. Fall back to 343 * root_rl in such cases. 344 */ 345 blkg = blkg_lookup_create(blkcg, q); 346 if (unlikely(IS_ERR(blkg))) 347 goto root_rl; 348 349 blkg_get(blkg); 350 rcu_read_unlock(); 351 return &blkg->rl; 352 root_rl: 353 rcu_read_unlock(); 354 return &q->root_rl; 355 } 356 357 /** 358 * blk_put_rl - put request_list 359 * @rl: request_list to put 360 * 361 * Put the reference acquired by blk_get_rl(). Should be called under 362 * queue_lock. 363 */ 364 static inline void blk_put_rl(struct request_list *rl) 365 { 366 /* root_rl may not have blkg set */ 367 if (rl->blkg && rl->blkg->blkcg != &blkcg_root) 368 blkg_put(rl->blkg); 369 } 370 371 /** 372 * blk_rq_set_rl - associate a request with a request_list 373 * @rq: request of interest 374 * @rl: target request_list 375 * 376 * Associate @rq with @rl so that accounting and freeing can know the 377 * request_list @rq came from. 378 */ 379 static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl) 380 { 381 rq->rl = rl; 382 } 383 384 /** 385 * blk_rq_rl - return the request_list a request came from 386 * @rq: request of interest 387 * 388 * Return the request_list @rq is allocated from. 389 */ 390 static inline struct request_list *blk_rq_rl(struct request *rq) 391 { 392 return rq->rl; 393 } 394 395 struct request_list *__blk_queue_next_rl(struct request_list *rl, 396 struct request_queue *q); 397 /** 398 * blk_queue_for_each_rl - iterate through all request_lists of a request_queue 399 * 400 * Should be used under queue_lock. 401 */ 402 #define blk_queue_for_each_rl(rl, q) \ 403 for ((rl) = &(q)->root_rl; (rl); (rl) = __blk_queue_next_rl((rl), (q))) 404 405 static inline void blkg_stat_init(struct blkg_stat *stat) 406 { 407 u64_stats_init(&stat->syncp); 408 } 409 410 /** 411 * blkg_stat_add - add a value to a blkg_stat 412 * @stat: target blkg_stat 413 * @val: value to add 414 * 415 * Add @val to @stat. The caller is responsible for synchronizing calls to 416 * this function. 417 */ 418 static inline void blkg_stat_add(struct blkg_stat *stat, uint64_t val) 419 { 420 u64_stats_update_begin(&stat->syncp); 421 stat->cnt += val; 422 u64_stats_update_end(&stat->syncp); 423 } 424 425 /** 426 * blkg_stat_read - read the current value of a blkg_stat 427 * @stat: blkg_stat to read 428 * 429 * Read the current value of @stat. This function can be called without 430 * synchroniztion and takes care of u64 atomicity. 431 */ 432 static inline uint64_t blkg_stat_read(struct blkg_stat *stat) 433 { 434 unsigned int start; 435 uint64_t v; 436 437 do { 438 start = u64_stats_fetch_begin_bh(&stat->syncp); 439 v = stat->cnt; 440 } while (u64_stats_fetch_retry_bh(&stat->syncp, start)); 441 442 return v; 443 } 444 445 /** 446 * blkg_stat_reset - reset a blkg_stat 447 * @stat: blkg_stat to reset 448 */ 449 static inline void blkg_stat_reset(struct blkg_stat *stat) 450 { 451 stat->cnt = 0; 452 } 453 454 /** 455 * blkg_stat_merge - merge a blkg_stat into another 456 * @to: the destination blkg_stat 457 * @from: the source 458 * 459 * Add @from's count to @to. 460 */ 461 static inline void blkg_stat_merge(struct blkg_stat *to, struct blkg_stat *from) 462 { 463 blkg_stat_add(to, blkg_stat_read(from)); 464 } 465 466 static inline void blkg_rwstat_init(struct blkg_rwstat *rwstat) 467 { 468 u64_stats_init(&rwstat->syncp); 469 } 470 471 /** 472 * blkg_rwstat_add - add a value to a blkg_rwstat 473 * @rwstat: target blkg_rwstat 474 * @rw: mask of REQ_{WRITE|SYNC} 475 * @val: value to add 476 * 477 * Add @val to @rwstat. The counters are chosen according to @rw. The 478 * caller is responsible for synchronizing calls to this function. 479 */ 480 static inline void blkg_rwstat_add(struct blkg_rwstat *rwstat, 481 int rw, uint64_t val) 482 { 483 u64_stats_update_begin(&rwstat->syncp); 484 485 if (rw & REQ_WRITE) 486 rwstat->cnt[BLKG_RWSTAT_WRITE] += val; 487 else 488 rwstat->cnt[BLKG_RWSTAT_READ] += val; 489 if (rw & REQ_SYNC) 490 rwstat->cnt[BLKG_RWSTAT_SYNC] += val; 491 else 492 rwstat->cnt[BLKG_RWSTAT_ASYNC] += val; 493 494 u64_stats_update_end(&rwstat->syncp); 495 } 496 497 /** 498 * blkg_rwstat_read - read the current values of a blkg_rwstat 499 * @rwstat: blkg_rwstat to read 500 * 501 * Read the current snapshot of @rwstat and return it as the return value. 502 * This function can be called without synchronization and takes care of 503 * u64 atomicity. 504 */ 505 static inline struct blkg_rwstat blkg_rwstat_read(struct blkg_rwstat *rwstat) 506 { 507 unsigned int start; 508 struct blkg_rwstat tmp; 509 510 do { 511 start = u64_stats_fetch_begin_bh(&rwstat->syncp); 512 tmp = *rwstat; 513 } while (u64_stats_fetch_retry_bh(&rwstat->syncp, start)); 514 515 return tmp; 516 } 517 518 /** 519 * blkg_rwstat_total - read the total count of a blkg_rwstat 520 * @rwstat: blkg_rwstat to read 521 * 522 * Return the total count of @rwstat regardless of the IO direction. This 523 * function can be called without synchronization and takes care of u64 524 * atomicity. 525 */ 526 static inline uint64_t blkg_rwstat_total(struct blkg_rwstat *rwstat) 527 { 528 struct blkg_rwstat tmp = blkg_rwstat_read(rwstat); 529 530 return tmp.cnt[BLKG_RWSTAT_READ] + tmp.cnt[BLKG_RWSTAT_WRITE]; 531 } 532 533 /** 534 * blkg_rwstat_reset - reset a blkg_rwstat 535 * @rwstat: blkg_rwstat to reset 536 */ 537 static inline void blkg_rwstat_reset(struct blkg_rwstat *rwstat) 538 { 539 memset(rwstat->cnt, 0, sizeof(rwstat->cnt)); 540 } 541 542 /** 543 * blkg_rwstat_merge - merge a blkg_rwstat into another 544 * @to: the destination blkg_rwstat 545 * @from: the source 546 * 547 * Add @from's counts to @to. 548 */ 549 static inline void blkg_rwstat_merge(struct blkg_rwstat *to, 550 struct blkg_rwstat *from) 551 { 552 struct blkg_rwstat v = blkg_rwstat_read(from); 553 int i; 554 555 u64_stats_update_begin(&to->syncp); 556 for (i = 0; i < BLKG_RWSTAT_NR; i++) 557 to->cnt[i] += v.cnt[i]; 558 u64_stats_update_end(&to->syncp); 559 } 560 561 #else /* CONFIG_BLK_CGROUP */ 562 563 struct cgroup; 564 struct blkcg; 565 566 struct blkg_policy_data { 567 }; 568 569 struct blkcg_gq { 570 }; 571 572 struct blkcg_policy { 573 }; 574 575 static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, void *key) { return NULL; } 576 static inline int blkcg_init_queue(struct request_queue *q) { return 0; } 577 static inline void blkcg_drain_queue(struct request_queue *q) { } 578 static inline void blkcg_exit_queue(struct request_queue *q) { } 579 static inline int blkcg_policy_register(struct blkcg_policy *pol) { return 0; } 580 static inline void blkcg_policy_unregister(struct blkcg_policy *pol) { } 581 static inline int blkcg_activate_policy(struct request_queue *q, 582 const struct blkcg_policy *pol) { return 0; } 583 static inline void blkcg_deactivate_policy(struct request_queue *q, 584 const struct blkcg_policy *pol) { } 585 586 static inline struct blkcg *bio_blkcg(struct bio *bio) { return NULL; } 587 588 static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg, 589 struct blkcg_policy *pol) { return NULL; } 590 static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd) { return NULL; } 591 static inline char *blkg_path(struct blkcg_gq *blkg) { return NULL; } 592 static inline void blkg_get(struct blkcg_gq *blkg) { } 593 static inline void blkg_put(struct blkcg_gq *blkg) { } 594 595 static inline struct request_list *blk_get_rl(struct request_queue *q, 596 struct bio *bio) { return &q->root_rl; } 597 static inline void blk_put_rl(struct request_list *rl) { } 598 static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl) { } 599 static inline struct request_list *blk_rq_rl(struct request *rq) { return &rq->q->root_rl; } 600 601 #define blk_queue_for_each_rl(rl, q) \ 602 for ((rl) = &(q)->root_rl; (rl); (rl) = NULL) 603 604 #endif /* CONFIG_BLK_CGROUP */ 605 #endif /* _BLK_CGROUP_H */ 606