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