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