1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef _BLK_CGROUP_PRIVATE_H 3 #define _BLK_CGROUP_PRIVATE_H 4 /* 5 * block cgroup private header 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/blk-cgroup.h> 18 #include <linux/cgroup.h> 19 #include <linux/kthread.h> 20 #include <linux/blk-mq.h> 21 22 struct blkcg_gq; 23 struct blkg_policy_data; 24 25 26 /* percpu_counter batch for blkg_[rw]stats, per-cpu drift doesn't matter */ 27 #define BLKG_STAT_CPU_BATCH (INT_MAX / 2) 28 29 #ifdef CONFIG_BLK_CGROUP 30 31 enum blkg_iostat_type { 32 BLKG_IOSTAT_READ, 33 BLKG_IOSTAT_WRITE, 34 BLKG_IOSTAT_DISCARD, 35 36 BLKG_IOSTAT_NR, 37 }; 38 39 struct blkg_iostat { 40 u64 bytes[BLKG_IOSTAT_NR]; 41 u64 ios[BLKG_IOSTAT_NR]; 42 }; 43 44 struct blkg_iostat_set { 45 struct u64_stats_sync sync; 46 struct blkg_iostat cur; 47 struct blkg_iostat last; 48 }; 49 50 /* association between a blk cgroup and a request queue */ 51 struct blkcg_gq { 52 /* Pointer to the associated request_queue */ 53 struct request_queue *q; 54 struct list_head q_node; 55 struct hlist_node blkcg_node; 56 struct blkcg *blkcg; 57 58 /* all non-root blkcg_gq's are guaranteed to have access to parent */ 59 struct blkcg_gq *parent; 60 61 /* reference count */ 62 struct percpu_ref refcnt; 63 64 /* is this blkg online? protected by both blkcg and q locks */ 65 bool online; 66 67 struct blkg_iostat_set __percpu *iostat_cpu; 68 struct blkg_iostat_set iostat; 69 70 struct blkg_policy_data *pd[BLKCG_MAX_POLS]; 71 72 spinlock_t async_bio_lock; 73 struct bio_list async_bios; 74 union { 75 struct work_struct async_bio_work; 76 struct work_struct free_work; 77 }; 78 79 atomic_t use_delay; 80 atomic64_t delay_nsec; 81 atomic64_t delay_start; 82 u64 last_delay; 83 int last_use; 84 85 struct rcu_head rcu_head; 86 }; 87 88 struct blkcg { 89 struct cgroup_subsys_state css; 90 spinlock_t lock; 91 refcount_t online_pin; 92 93 struct radix_tree_root blkg_tree; 94 struct blkcg_gq __rcu *blkg_hint; 95 struct hlist_head blkg_list; 96 97 struct blkcg_policy_data *cpd[BLKCG_MAX_POLS]; 98 99 struct list_head all_blkcgs_node; 100 #ifdef CONFIG_BLK_CGROUP_FC_APPID 101 char fc_app_id[FC_APPID_LEN]; 102 #endif 103 #ifdef CONFIG_CGROUP_WRITEBACK 104 struct list_head cgwb_list; 105 #endif 106 }; 107 108 static inline struct blkcg *css_to_blkcg(struct cgroup_subsys_state *css) 109 { 110 return css ? container_of(css, struct blkcg, css) : NULL; 111 } 112 113 /* 114 * A blkcg_gq (blkg) is association between a block cgroup (blkcg) and a 115 * request_queue (q). This is used by blkcg policies which need to track 116 * information per blkcg - q pair. 117 * 118 * There can be multiple active blkcg policies and each blkg:policy pair is 119 * represented by a blkg_policy_data which is allocated and freed by each 120 * policy's pd_alloc/free_fn() methods. A policy can allocate private data 121 * area by allocating larger data structure which embeds blkg_policy_data 122 * at the beginning. 123 */ 124 struct blkg_policy_data { 125 /* the blkg and policy id this per-policy data belongs to */ 126 struct blkcg_gq *blkg; 127 int plid; 128 }; 129 130 /* 131 * Policies that need to keep per-blkcg data which is independent from any 132 * request_queue associated to it should implement cpd_alloc/free_fn() 133 * methods. A policy can allocate private data area by allocating larger 134 * data structure which embeds blkcg_policy_data at the beginning. 135 * cpd_init() is invoked to let each policy handle per-blkcg data. 136 */ 137 struct blkcg_policy_data { 138 /* the blkcg and policy id this per-policy data belongs to */ 139 struct blkcg *blkcg; 140 int plid; 141 }; 142 143 typedef struct blkcg_policy_data *(blkcg_pol_alloc_cpd_fn)(gfp_t gfp); 144 typedef void (blkcg_pol_init_cpd_fn)(struct blkcg_policy_data *cpd); 145 typedef void (blkcg_pol_free_cpd_fn)(struct blkcg_policy_data *cpd); 146 typedef void (blkcg_pol_bind_cpd_fn)(struct blkcg_policy_data *cpd); 147 typedef struct blkg_policy_data *(blkcg_pol_alloc_pd_fn)(gfp_t gfp, 148 struct request_queue *q, struct blkcg *blkcg); 149 typedef void (blkcg_pol_init_pd_fn)(struct blkg_policy_data *pd); 150 typedef void (blkcg_pol_online_pd_fn)(struct blkg_policy_data *pd); 151 typedef void (blkcg_pol_offline_pd_fn)(struct blkg_policy_data *pd); 152 typedef void (blkcg_pol_free_pd_fn)(struct blkg_policy_data *pd); 153 typedef void (blkcg_pol_reset_pd_stats_fn)(struct blkg_policy_data *pd); 154 typedef void (blkcg_pol_stat_pd_fn)(struct blkg_policy_data *pd, 155 struct seq_file *s); 156 157 struct blkcg_policy { 158 int plid; 159 /* cgroup files for the policy */ 160 struct cftype *dfl_cftypes; 161 struct cftype *legacy_cftypes; 162 163 /* operations */ 164 blkcg_pol_alloc_cpd_fn *cpd_alloc_fn; 165 blkcg_pol_init_cpd_fn *cpd_init_fn; 166 blkcg_pol_free_cpd_fn *cpd_free_fn; 167 blkcg_pol_bind_cpd_fn *cpd_bind_fn; 168 169 blkcg_pol_alloc_pd_fn *pd_alloc_fn; 170 blkcg_pol_init_pd_fn *pd_init_fn; 171 blkcg_pol_online_pd_fn *pd_online_fn; 172 blkcg_pol_offline_pd_fn *pd_offline_fn; 173 blkcg_pol_free_pd_fn *pd_free_fn; 174 blkcg_pol_reset_pd_stats_fn *pd_reset_stats_fn; 175 blkcg_pol_stat_pd_fn *pd_stat_fn; 176 }; 177 178 extern struct blkcg blkcg_root; 179 extern bool blkcg_debug_stats; 180 181 struct blkcg_gq *blkg_lookup_slowpath(struct blkcg *blkcg, 182 struct request_queue *q, bool update_hint); 183 int blkcg_init_queue(struct request_queue *q); 184 void blkcg_exit_queue(struct request_queue *q); 185 186 /* Blkio controller policy registration */ 187 int blkcg_policy_register(struct blkcg_policy *pol); 188 void blkcg_policy_unregister(struct blkcg_policy *pol); 189 int blkcg_activate_policy(struct request_queue *q, 190 const struct blkcg_policy *pol); 191 void blkcg_deactivate_policy(struct request_queue *q, 192 const struct blkcg_policy *pol); 193 194 const char *blkg_dev_name(struct blkcg_gq *blkg); 195 void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg, 196 u64 (*prfill)(struct seq_file *, 197 struct blkg_policy_data *, int), 198 const struct blkcg_policy *pol, int data, 199 bool show_total); 200 u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v); 201 202 struct blkg_conf_ctx { 203 struct block_device *bdev; 204 struct blkcg_gq *blkg; 205 char *body; 206 }; 207 208 struct block_device *blkcg_conf_open_bdev(char **inputp); 209 int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol, 210 char *input, struct blkg_conf_ctx *ctx); 211 void blkg_conf_finish(struct blkg_conf_ctx *ctx); 212 213 /** 214 * bio_issue_as_root_blkg - see if this bio needs to be issued as root blkg 215 * @return: true if this bio needs to be submitted with the root blkg context. 216 * 217 * In order to avoid priority inversions we sometimes need to issue a bio as if 218 * it were attached to the root blkg, and then backcharge to the actual owning 219 * blkg. The idea is we do bio_blkcg_css() to look up the actual context for 220 * the bio and attach the appropriate blkg to the bio. Then we call this helper 221 * and if it is true run with the root blkg for that queue and then do any 222 * backcharging to the originating cgroup once the io is complete. 223 */ 224 static inline bool bio_issue_as_root_blkg(struct bio *bio) 225 { 226 return (bio->bi_opf & (REQ_META | REQ_SWAP)) != 0; 227 } 228 229 /** 230 * __blkg_lookup - internal version of blkg_lookup() 231 * @blkcg: blkcg of interest 232 * @q: request_queue of interest 233 * @update_hint: whether to update lookup hint with the result or not 234 * 235 * This is internal version and shouldn't be used by policy 236 * implementations. Looks up blkgs for the @blkcg - @q pair regardless of 237 * @q's bypass state. If @update_hint is %true, the caller should be 238 * holding @q->queue_lock and lookup hint is updated on success. 239 */ 240 static inline struct blkcg_gq *__blkg_lookup(struct blkcg *blkcg, 241 struct request_queue *q, 242 bool update_hint) 243 { 244 struct blkcg_gq *blkg; 245 246 if (blkcg == &blkcg_root) 247 return q->root_blkg; 248 249 blkg = rcu_dereference(blkcg->blkg_hint); 250 if (blkg && blkg->q == q) 251 return blkg; 252 253 return blkg_lookup_slowpath(blkcg, q, update_hint); 254 } 255 256 /** 257 * blkg_lookup - lookup blkg for the specified blkcg - q pair 258 * @blkcg: blkcg of interest 259 * @q: request_queue of interest 260 * 261 * Lookup blkg for the @blkcg - @q pair. This function should be called 262 * under RCU read lock. 263 */ 264 static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, 265 struct request_queue *q) 266 { 267 WARN_ON_ONCE(!rcu_read_lock_held()); 268 return __blkg_lookup(blkcg, q, false); 269 } 270 271 /** 272 * blkg_to_pdata - get policy private data 273 * @blkg: blkg of interest 274 * @pol: policy of interest 275 * 276 * Return pointer to private data associated with the @blkg-@pol pair. 277 */ 278 static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg, 279 struct blkcg_policy *pol) 280 { 281 return blkg ? blkg->pd[pol->plid] : NULL; 282 } 283 284 static inline struct blkcg_policy_data *blkcg_to_cpd(struct blkcg *blkcg, 285 struct blkcg_policy *pol) 286 { 287 return blkcg ? blkcg->cpd[pol->plid] : NULL; 288 } 289 290 /** 291 * pdata_to_blkg - get blkg associated with policy private data 292 * @pd: policy private data of interest 293 * 294 * @pd is policy private data. Determine the blkg it's associated with. 295 */ 296 static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd) 297 { 298 return pd ? pd->blkg : NULL; 299 } 300 301 static inline struct blkcg *cpd_to_blkcg(struct blkcg_policy_data *cpd) 302 { 303 return cpd ? cpd->blkcg : NULL; 304 } 305 306 /** 307 * blkg_path - format cgroup path of blkg 308 * @blkg: blkg of interest 309 * @buf: target buffer 310 * @buflen: target buffer length 311 * 312 * Format the path of the cgroup of @blkg into @buf. 313 */ 314 static inline int blkg_path(struct blkcg_gq *blkg, char *buf, int buflen) 315 { 316 return cgroup_path(blkg->blkcg->css.cgroup, buf, buflen); 317 } 318 319 /** 320 * blkg_get - get a blkg reference 321 * @blkg: blkg to get 322 * 323 * The caller should be holding an existing reference. 324 */ 325 static inline void blkg_get(struct blkcg_gq *blkg) 326 { 327 percpu_ref_get(&blkg->refcnt); 328 } 329 330 /** 331 * blkg_tryget - try and get a blkg reference 332 * @blkg: blkg to get 333 * 334 * This is for use when doing an RCU lookup of the blkg. We may be in the midst 335 * of freeing this blkg, so we can only use it if the refcnt is not zero. 336 */ 337 static inline bool blkg_tryget(struct blkcg_gq *blkg) 338 { 339 return blkg && percpu_ref_tryget(&blkg->refcnt); 340 } 341 342 /** 343 * blkg_put - put a blkg reference 344 * @blkg: blkg to put 345 */ 346 static inline void blkg_put(struct blkcg_gq *blkg) 347 { 348 percpu_ref_put(&blkg->refcnt); 349 } 350 351 /** 352 * blkg_for_each_descendant_pre - pre-order walk of a blkg's descendants 353 * @d_blkg: loop cursor pointing to the current descendant 354 * @pos_css: used for iteration 355 * @p_blkg: target blkg to walk descendants of 356 * 357 * Walk @c_blkg through the descendants of @p_blkg. Must be used with RCU 358 * read locked. If called under either blkcg or queue lock, the iteration 359 * is guaranteed to include all and only online blkgs. The caller may 360 * update @pos_css by calling css_rightmost_descendant() to skip subtree. 361 * @p_blkg is included in the iteration and the first node to be visited. 362 */ 363 #define blkg_for_each_descendant_pre(d_blkg, pos_css, p_blkg) \ 364 css_for_each_descendant_pre((pos_css), &(p_blkg)->blkcg->css) \ 365 if (((d_blkg) = blkg_lookup(css_to_blkcg(pos_css), \ 366 (p_blkg)->q))) 367 368 /** 369 * blkg_for_each_descendant_post - post-order walk of a blkg's descendants 370 * @d_blkg: loop cursor pointing to the current descendant 371 * @pos_css: used for iteration 372 * @p_blkg: target blkg to walk descendants of 373 * 374 * Similar to blkg_for_each_descendant_pre() but performs post-order 375 * traversal instead. Synchronization rules are the same. @p_blkg is 376 * included in the iteration and the last node to be visited. 377 */ 378 #define blkg_for_each_descendant_post(d_blkg, pos_css, p_blkg) \ 379 css_for_each_descendant_post((pos_css), &(p_blkg)->blkcg->css) \ 380 if (((d_blkg) = blkg_lookup(css_to_blkcg(pos_css), \ 381 (p_blkg)->q))) 382 383 bool __blkcg_punt_bio_submit(struct bio *bio); 384 385 static inline bool blkcg_punt_bio_submit(struct bio *bio) 386 { 387 if (bio->bi_opf & REQ_CGROUP_PUNT) 388 return __blkcg_punt_bio_submit(bio); 389 else 390 return false; 391 } 392 393 static inline void blkcg_bio_issue_init(struct bio *bio) 394 { 395 bio_issue_init(&bio->bi_issue, bio_sectors(bio)); 396 } 397 398 static inline void blkcg_use_delay(struct blkcg_gq *blkg) 399 { 400 if (WARN_ON_ONCE(atomic_read(&blkg->use_delay) < 0)) 401 return; 402 if (atomic_add_return(1, &blkg->use_delay) == 1) 403 atomic_inc(&blkg->blkcg->css.cgroup->congestion_count); 404 } 405 406 static inline int blkcg_unuse_delay(struct blkcg_gq *blkg) 407 { 408 int old = atomic_read(&blkg->use_delay); 409 410 if (WARN_ON_ONCE(old < 0)) 411 return 0; 412 if (old == 0) 413 return 0; 414 415 /* 416 * We do this song and dance because we can race with somebody else 417 * adding or removing delay. If we just did an atomic_dec we'd end up 418 * negative and we'd already be in trouble. We need to subtract 1 and 419 * then check to see if we were the last delay so we can drop the 420 * congestion count on the cgroup. 421 */ 422 while (old && !atomic_try_cmpxchg(&blkg->use_delay, &old, old - 1)) 423 ; 424 425 if (old == 0) 426 return 0; 427 if (old == 1) 428 atomic_dec(&blkg->blkcg->css.cgroup->congestion_count); 429 return 1; 430 } 431 432 /** 433 * blkcg_set_delay - Enable allocator delay mechanism with the specified delay amount 434 * @blkg: target blkg 435 * @delay: delay duration in nsecs 436 * 437 * When enabled with this function, the delay is not decayed and must be 438 * explicitly cleared with blkcg_clear_delay(). Must not be mixed with 439 * blkcg_[un]use_delay() and blkcg_add_delay() usages. 440 */ 441 static inline void blkcg_set_delay(struct blkcg_gq *blkg, u64 delay) 442 { 443 int old = atomic_read(&blkg->use_delay); 444 445 /* We only want 1 person setting the congestion count for this blkg. */ 446 if (!old && atomic_try_cmpxchg(&blkg->use_delay, &old, -1)) 447 atomic_inc(&blkg->blkcg->css.cgroup->congestion_count); 448 449 atomic64_set(&blkg->delay_nsec, delay); 450 } 451 452 /** 453 * blkcg_clear_delay - Disable allocator delay mechanism 454 * @blkg: target blkg 455 * 456 * Disable use_delay mechanism. See blkcg_set_delay(). 457 */ 458 static inline void blkcg_clear_delay(struct blkcg_gq *blkg) 459 { 460 int old = atomic_read(&blkg->use_delay); 461 462 /* We only want 1 person clearing the congestion count for this blkg. */ 463 if (old && atomic_try_cmpxchg(&blkg->use_delay, &old, 0)) 464 atomic_dec(&blkg->blkcg->css.cgroup->congestion_count); 465 } 466 467 /** 468 * blk_cgroup_mergeable - Determine whether to allow or disallow merges 469 * @rq: request to merge into 470 * @bio: bio to merge 471 * 472 * @bio and @rq should belong to the same cgroup and their issue_as_root should 473 * match. The latter is necessary as we don't want to throttle e.g. a metadata 474 * update because it happens to be next to a regular IO. 475 */ 476 static inline bool blk_cgroup_mergeable(struct request *rq, struct bio *bio) 477 { 478 return rq->bio->bi_blkg == bio->bi_blkg && 479 bio_issue_as_root_blkg(rq->bio) == bio_issue_as_root_blkg(bio); 480 } 481 482 void blk_cgroup_bio_start(struct bio *bio); 483 void blkcg_add_delay(struct blkcg_gq *blkg, u64 now, u64 delta); 484 #else /* CONFIG_BLK_CGROUP */ 485 486 struct blkg_policy_data { 487 }; 488 489 struct blkcg_policy_data { 490 }; 491 492 struct blkcg_policy { 493 }; 494 495 struct blkcg { 496 }; 497 498 static inline struct blkcg_gq *blkg_lookup(struct blkcg *blkcg, void *key) { return NULL; } 499 static inline int blkcg_init_queue(struct request_queue *q) { return 0; } 500 static inline void blkcg_exit_queue(struct request_queue *q) { } 501 static inline int blkcg_policy_register(struct blkcg_policy *pol) { return 0; } 502 static inline void blkcg_policy_unregister(struct blkcg_policy *pol) { } 503 static inline int blkcg_activate_policy(struct request_queue *q, 504 const struct blkcg_policy *pol) { return 0; } 505 static inline void blkcg_deactivate_policy(struct request_queue *q, 506 const struct blkcg_policy *pol) { } 507 508 static inline struct blkg_policy_data *blkg_to_pd(struct blkcg_gq *blkg, 509 struct blkcg_policy *pol) { return NULL; } 510 static inline struct blkcg_gq *pd_to_blkg(struct blkg_policy_data *pd) { return NULL; } 511 static inline char *blkg_path(struct blkcg_gq *blkg) { return NULL; } 512 static inline void blkg_get(struct blkcg_gq *blkg) { } 513 static inline void blkg_put(struct blkcg_gq *blkg) { } 514 515 static inline bool blkcg_punt_bio_submit(struct bio *bio) { return false; } 516 static inline void blkcg_bio_issue_init(struct bio *bio) { } 517 static inline void blk_cgroup_bio_start(struct bio *bio) { } 518 static inline bool blk_cgroup_mergeable(struct request *rq, struct bio *bio) { return true; } 519 520 #define blk_queue_for_each_rl(rl, q) \ 521 for ((rl) = &(q)->root_rl; (rl); (rl) = NULL) 522 523 #endif /* CONFIG_BLK_CGROUP */ 524 525 #endif /* _BLK_CGROUP_PRIVATE_H */ 526