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