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