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 *cgroup_to_blkcg(struct cgroup *cgroup) 183 { 184 return container_of(cgroup_subsys_state(cgroup, blkio_subsys_id), 185 struct blkcg, css); 186 } 187 188 static inline struct blkcg *task_blkcg(struct task_struct *tsk) 189 { 190 return container_of(task_subsys_state(tsk, blkio_subsys_id), 191 struct blkcg, css); 192 } 193 194 static inline struct blkcg *bio_blkcg(struct bio *bio) 195 { 196 if (bio && bio->bi_css) 197 return container_of(bio->bi_css, struct blkcg, css); 198 return task_blkcg(current); 199 } 200 201 /** 202 * blkcg_parent - get the parent of a blkcg 203 * @blkcg: blkcg of interest 204 * 205 * Return the parent blkcg of @blkcg. Can be called anytime. 206 */ 207 static inline struct blkcg *blkcg_parent(struct blkcg *blkcg) 208 { 209 struct cgroup *pcg = blkcg->css.cgroup->parent; 210 211 return pcg ? cgroup_to_blkcg(pcg) : NULL; 212 } 213 214 /** 215 * blkg_to_pdata - get policy private data 216 * @blkg: blkg of interest 217 * @pol: policy of interest 218 * 219 * Return pointer to private data associated with the @blkg-@pol pair. 220 */ 221 static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg, 222 struct blkcg_policy *pol) 223 { 224 return blkg ? blkg->pd[pol->plid] : NULL; 225 } 226 227 /** 228 * pdata_to_blkg - get blkg associated with policy private data 229 * @pd: policy private data of interest 230 * 231 * @pd is policy private data. Determine the blkg it's associated with. 232 */ 233 static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd) 234 { 235 return pd ? pd->blkg : NULL; 236 } 237 238 /** 239 * blkg_path - format cgroup path of blkg 240 * @blkg: blkg of interest 241 * @buf: target buffer 242 * @buflen: target buffer length 243 * 244 * Format the path of the cgroup of @blkg into @buf. 245 */ 246 static inline int blkg_path(struct blkcg_gq *blkg, char *buf, int buflen) 247 { 248 int ret; 249 250 rcu_read_lock(); 251 ret = cgroup_path(blkg->blkcg->css.cgroup, buf, buflen); 252 rcu_read_unlock(); 253 if (ret) 254 strncpy(buf, "<unavailable>", buflen); 255 return ret; 256 } 257 258 /** 259 * blkg_get - get a blkg reference 260 * @blkg: blkg to get 261 * 262 * The caller should be holding queue_lock and an existing reference. 263 */ 264 static inline void blkg_get(struct blkcg_gq *blkg) 265 { 266 lockdep_assert_held(blkg->q->queue_lock); 267 WARN_ON_ONCE(!blkg->refcnt); 268 blkg->refcnt++; 269 } 270 271 void __blkg_release(struct blkcg_gq *blkg); 272 273 /** 274 * blkg_put - put a blkg reference 275 * @blkg: blkg to put 276 * 277 * The caller should be holding queue_lock. 278 */ 279 static inline void blkg_put(struct blkcg_gq *blkg) 280 { 281 lockdep_assert_held(blkg->q->queue_lock); 282 WARN_ON_ONCE(blkg->refcnt <= 0); 283 if (!--blkg->refcnt) 284 __blkg_release(blkg); 285 } 286 287 /** 288 * blk_get_rl - get request_list to use 289 * @q: request_queue of interest 290 * @bio: bio which will be attached to the allocated request (may be %NULL) 291 * 292 * The caller wants to allocate a request from @q to use for @bio. Find 293 * the request_list to use and obtain a reference on it. Should be called 294 * under queue_lock. This function is guaranteed to return non-%NULL 295 * request_list. 296 */ 297 static inline struct request_list *blk_get_rl(struct request_queue *q, 298 struct bio *bio) 299 { 300 struct blkcg *blkcg; 301 struct blkcg_gq *blkg; 302 303 rcu_read_lock(); 304 305 blkcg = bio_blkcg(bio); 306 307 /* bypass blkg lookup and use @q->root_rl directly for root */ 308 if (blkcg == &blkcg_root) 309 goto root_rl; 310 311 /* 312 * Try to use blkg->rl. blkg lookup may fail under memory pressure 313 * or if either the blkcg or queue is going away. Fall back to 314 * root_rl in such cases. 315 */ 316 blkg = blkg_lookup_create(blkcg, q); 317 if (unlikely(IS_ERR(blkg))) 318 goto root_rl; 319 320 blkg_get(blkg); 321 rcu_read_unlock(); 322 return &blkg->rl; 323 root_rl: 324 rcu_read_unlock(); 325 return &q->root_rl; 326 } 327 328 /** 329 * blk_put_rl - put request_list 330 * @rl: request_list to put 331 * 332 * Put the reference acquired by blk_get_rl(). Should be called under 333 * queue_lock. 334 */ 335 static inline void blk_put_rl(struct request_list *rl) 336 { 337 /* root_rl may not have blkg set */ 338 if (rl->blkg && rl->blkg->blkcg != &blkcg_root) 339 blkg_put(rl->blkg); 340 } 341 342 /** 343 * blk_rq_set_rl - associate a request with a request_list 344 * @rq: request of interest 345 * @rl: target request_list 346 * 347 * Associate @rq with @rl so that accounting and freeing can know the 348 * request_list @rq came from. 349 */ 350 static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl) 351 { 352 rq->rl = rl; 353 } 354 355 /** 356 * blk_rq_rl - return the request_list a request came from 357 * @rq: request of interest 358 * 359 * Return the request_list @rq is allocated from. 360 */ 361 static inline struct request_list *blk_rq_rl(struct request *rq) 362 { 363 return rq->rl; 364 } 365 366 struct request_list *__blk_queue_next_rl(struct request_list *rl, 367 struct request_queue *q); 368 /** 369 * blk_queue_for_each_rl - iterate through all request_lists of a request_queue 370 * 371 * Should be used under queue_lock. 372 */ 373 #define blk_queue_for_each_rl(rl, q) \ 374 for ((rl) = &(q)->root_rl; (rl); (rl) = __blk_queue_next_rl((rl), (q))) 375 376 /** 377 * blkg_stat_add - add a value to a blkg_stat 378 * @stat: target blkg_stat 379 * @val: value to add 380 * 381 * Add @val to @stat. The caller is responsible for synchronizing calls to 382 * this function. 383 */ 384 static inline void blkg_stat_add(struct blkg_stat *stat, uint64_t val) 385 { 386 u64_stats_update_begin(&stat->syncp); 387 stat->cnt += val; 388 u64_stats_update_end(&stat->syncp); 389 } 390 391 /** 392 * blkg_stat_read - read the current value of a blkg_stat 393 * @stat: blkg_stat to read 394 * 395 * Read the current value of @stat. This function can be called without 396 * synchroniztion and takes care of u64 atomicity. 397 */ 398 static inline uint64_t blkg_stat_read(struct blkg_stat *stat) 399 { 400 unsigned int start; 401 uint64_t v; 402 403 do { 404 start = u64_stats_fetch_begin(&stat->syncp); 405 v = stat->cnt; 406 } while (u64_stats_fetch_retry(&stat->syncp, start)); 407 408 return v; 409 } 410 411 /** 412 * blkg_stat_reset - reset a blkg_stat 413 * @stat: blkg_stat to reset 414 */ 415 static inline void blkg_stat_reset(struct blkg_stat *stat) 416 { 417 stat->cnt = 0; 418 } 419 420 /** 421 * blkg_stat_merge - merge a blkg_stat into another 422 * @to: the destination blkg_stat 423 * @from: the source 424 * 425 * Add @from's count to @to. 426 */ 427 static inline void blkg_stat_merge(struct blkg_stat *to, struct blkg_stat *from) 428 { 429 blkg_stat_add(to, blkg_stat_read(from)); 430 } 431 432 /** 433 * blkg_rwstat_add - add a value to a blkg_rwstat 434 * @rwstat: target blkg_rwstat 435 * @rw: mask of REQ_{WRITE|SYNC} 436 * @val: value to add 437 * 438 * Add @val to @rwstat. The counters are chosen according to @rw. The 439 * caller is responsible for synchronizing calls to this function. 440 */ 441 static inline void blkg_rwstat_add(struct blkg_rwstat *rwstat, 442 int rw, uint64_t val) 443 { 444 u64_stats_update_begin(&rwstat->syncp); 445 446 if (rw & REQ_WRITE) 447 rwstat->cnt[BLKG_RWSTAT_WRITE] += val; 448 else 449 rwstat->cnt[BLKG_RWSTAT_READ] += val; 450 if (rw & REQ_SYNC) 451 rwstat->cnt[BLKG_RWSTAT_SYNC] += val; 452 else 453 rwstat->cnt[BLKG_RWSTAT_ASYNC] += val; 454 455 u64_stats_update_end(&rwstat->syncp); 456 } 457 458 /** 459 * blkg_rwstat_read - read the current values of a blkg_rwstat 460 * @rwstat: blkg_rwstat to read 461 * 462 * Read the current snapshot of @rwstat and return it as the return value. 463 * This function can be called without synchronization and takes care of 464 * u64 atomicity. 465 */ 466 static inline struct blkg_rwstat blkg_rwstat_read(struct blkg_rwstat *rwstat) 467 { 468 unsigned int start; 469 struct blkg_rwstat tmp; 470 471 do { 472 start = u64_stats_fetch_begin(&rwstat->syncp); 473 tmp = *rwstat; 474 } while (u64_stats_fetch_retry(&rwstat->syncp, start)); 475 476 return tmp; 477 } 478 479 /** 480 * blkg_rwstat_total - read the total count of a blkg_rwstat 481 * @rwstat: blkg_rwstat to read 482 * 483 * Return the total count of @rwstat regardless of the IO direction. This 484 * function can be called without synchronization and takes care of u64 485 * atomicity. 486 */ 487 static inline uint64_t blkg_rwstat_total(struct blkg_rwstat *rwstat) 488 { 489 struct blkg_rwstat tmp = blkg_rwstat_read(rwstat); 490 491 return tmp.cnt[BLKG_RWSTAT_READ] + tmp.cnt[BLKG_RWSTAT_WRITE]; 492 } 493 494 /** 495 * blkg_rwstat_reset - reset a blkg_rwstat 496 * @rwstat: blkg_rwstat to reset 497 */ 498 static inline void blkg_rwstat_reset(struct blkg_rwstat *rwstat) 499 { 500 memset(rwstat->cnt, 0, sizeof(rwstat->cnt)); 501 } 502 503 /** 504 * blkg_rwstat_merge - merge a blkg_rwstat into another 505 * @to: the destination blkg_rwstat 506 * @from: the source 507 * 508 * Add @from's counts to @to. 509 */ 510 static inline void blkg_rwstat_merge(struct blkg_rwstat *to, 511 struct blkg_rwstat *from) 512 { 513 struct blkg_rwstat v = blkg_rwstat_read(from); 514 int i; 515 516 u64_stats_update_begin(&to->syncp); 517 for (i = 0; i < BLKG_RWSTAT_NR; i++) 518 to->cnt[i] += v.cnt[i]; 519 u64_stats_update_end(&to->syncp); 520 } 521 522 #else /* CONFIG_BLK_CGROUP */ 523 524 struct cgroup; 525 struct blkcg; 526 527 struct blkg_policy_data { 528 }; 529 530 struct blkcg_gq { 531 }; 532 533 struct blkcg_policy { 534 }; 535 536 static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, void *key) { return NULL; } 537 static inline int blkcg_init_queue(struct request_queue *q) { return 0; } 538 static inline void blkcg_drain_queue(struct request_queue *q) { } 539 static inline void blkcg_exit_queue(struct request_queue *q) { } 540 static inline int blkcg_policy_register(struct blkcg_policy *pol) { return 0; } 541 static inline void blkcg_policy_unregister(struct blkcg_policy *pol) { } 542 static inline int blkcg_activate_policy(struct request_queue *q, 543 const struct blkcg_policy *pol) { return 0; } 544 static inline void blkcg_deactivate_policy(struct request_queue *q, 545 const struct blkcg_policy *pol) { } 546 547 static inline struct blkcg *cgroup_to_blkcg(struct cgroup *cgroup) { return NULL; } 548 static inline struct blkcg *bio_blkcg(struct bio *bio) { return NULL; } 549 550 static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg, 551 struct blkcg_policy *pol) { return NULL; } 552 static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd) { return NULL; } 553 static inline char *blkg_path(struct blkcg_gq *blkg) { return NULL; } 554 static inline void blkg_get(struct blkcg_gq *blkg) { } 555 static inline void blkg_put(struct blkcg_gq *blkg) { } 556 557 static inline struct request_list *blk_get_rl(struct request_queue *q, 558 struct bio *bio) { return &q->root_rl; } 559 static inline void blk_put_rl(struct request_list *rl) { } 560 static inline void blk_rq_set_rl(struct request *rq, struct request_list *rl) { } 561 static inline struct request_list *blk_rq_rl(struct request *rq) { return &rq->q->root_rl; } 562 563 #define blk_queue_for_each_rl(rl, q) \ 564 for ((rl) = &(q)->root_rl; (rl); (rl) = NULL) 565 566 #endif /* CONFIG_BLK_CGROUP */ 567 #endif /* _BLK_CGROUP_H */ 568