1 /* 2 * cgroups support for the BFQ I/O scheduler. 3 * 4 * This program is free software; you can redistribute it and/or 5 * modify it under the terms of the GNU General Public License as 6 * published by the Free Software Foundation; either version 2 of the 7 * License, or (at your option) any later version. 8 * 9 * This program is distributed in the hope that it will be useful, 10 * but WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 12 * General Public License for more details. 13 */ 14 #include <linux/module.h> 15 #include <linux/slab.h> 16 #include <linux/blkdev.h> 17 #include <linux/cgroup.h> 18 #include <linux/elevator.h> 19 #include <linux/ktime.h> 20 #include <linux/rbtree.h> 21 #include <linux/ioprio.h> 22 #include <linux/sbitmap.h> 23 #include <linux/delay.h> 24 25 #include "bfq-iosched.h" 26 27 #ifdef CONFIG_BFQ_GROUP_IOSCHED 28 29 /* bfqg stats flags */ 30 enum bfqg_stats_flags { 31 BFQG_stats_waiting = 0, 32 BFQG_stats_idling, 33 BFQG_stats_empty, 34 }; 35 36 #define BFQG_FLAG_FNS(name) \ 37 static void bfqg_stats_mark_##name(struct bfqg_stats *stats) \ 38 { \ 39 stats->flags |= (1 << BFQG_stats_##name); \ 40 } \ 41 static void bfqg_stats_clear_##name(struct bfqg_stats *stats) \ 42 { \ 43 stats->flags &= ~(1 << BFQG_stats_##name); \ 44 } \ 45 static int bfqg_stats_##name(struct bfqg_stats *stats) \ 46 { \ 47 return (stats->flags & (1 << BFQG_stats_##name)) != 0; \ 48 } \ 49 50 BFQG_FLAG_FNS(waiting) 51 BFQG_FLAG_FNS(idling) 52 BFQG_FLAG_FNS(empty) 53 #undef BFQG_FLAG_FNS 54 55 /* This should be called with the scheduler lock held. */ 56 static void bfqg_stats_update_group_wait_time(struct bfqg_stats *stats) 57 { 58 unsigned long long now; 59 60 if (!bfqg_stats_waiting(stats)) 61 return; 62 63 now = sched_clock(); 64 if (time_after64(now, stats->start_group_wait_time)) 65 blkg_stat_add(&stats->group_wait_time, 66 now - stats->start_group_wait_time); 67 bfqg_stats_clear_waiting(stats); 68 } 69 70 /* This should be called with the scheduler lock held. */ 71 static void bfqg_stats_set_start_group_wait_time(struct bfq_group *bfqg, 72 struct bfq_group *curr_bfqg) 73 { 74 struct bfqg_stats *stats = &bfqg->stats; 75 76 if (bfqg_stats_waiting(stats)) 77 return; 78 if (bfqg == curr_bfqg) 79 return; 80 stats->start_group_wait_time = sched_clock(); 81 bfqg_stats_mark_waiting(stats); 82 } 83 84 /* This should be called with the scheduler lock held. */ 85 static void bfqg_stats_end_empty_time(struct bfqg_stats *stats) 86 { 87 unsigned long long now; 88 89 if (!bfqg_stats_empty(stats)) 90 return; 91 92 now = sched_clock(); 93 if (time_after64(now, stats->start_empty_time)) 94 blkg_stat_add(&stats->empty_time, 95 now - stats->start_empty_time); 96 bfqg_stats_clear_empty(stats); 97 } 98 99 void bfqg_stats_update_dequeue(struct bfq_group *bfqg) 100 { 101 blkg_stat_add(&bfqg->stats.dequeue, 1); 102 } 103 104 void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg) 105 { 106 struct bfqg_stats *stats = &bfqg->stats; 107 108 if (blkg_rwstat_total(&stats->queued)) 109 return; 110 111 /* 112 * group is already marked empty. This can happen if bfqq got new 113 * request in parent group and moved to this group while being added 114 * to service tree. Just ignore the event and move on. 115 */ 116 if (bfqg_stats_empty(stats)) 117 return; 118 119 stats->start_empty_time = sched_clock(); 120 bfqg_stats_mark_empty(stats); 121 } 122 123 void bfqg_stats_update_idle_time(struct bfq_group *bfqg) 124 { 125 struct bfqg_stats *stats = &bfqg->stats; 126 127 if (bfqg_stats_idling(stats)) { 128 unsigned long long now = sched_clock(); 129 130 if (time_after64(now, stats->start_idle_time)) 131 blkg_stat_add(&stats->idle_time, 132 now - stats->start_idle_time); 133 bfqg_stats_clear_idling(stats); 134 } 135 } 136 137 void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg) 138 { 139 struct bfqg_stats *stats = &bfqg->stats; 140 141 stats->start_idle_time = sched_clock(); 142 bfqg_stats_mark_idling(stats); 143 } 144 145 void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg) 146 { 147 struct bfqg_stats *stats = &bfqg->stats; 148 149 blkg_stat_add(&stats->avg_queue_size_sum, 150 blkg_rwstat_total(&stats->queued)); 151 blkg_stat_add(&stats->avg_queue_size_samples, 1); 152 bfqg_stats_update_group_wait_time(stats); 153 } 154 155 /* 156 * blk-cgroup policy-related handlers 157 * The following functions help in converting between blk-cgroup 158 * internal structures and BFQ-specific structures. 159 */ 160 161 static struct bfq_group *pd_to_bfqg(struct blkg_policy_data *pd) 162 { 163 return pd ? container_of(pd, struct bfq_group, pd) : NULL; 164 } 165 166 struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg) 167 { 168 return pd_to_blkg(&bfqg->pd); 169 } 170 171 static struct bfq_group *blkg_to_bfqg(struct blkcg_gq *blkg) 172 { 173 return pd_to_bfqg(blkg_to_pd(blkg, &blkcg_policy_bfq)); 174 } 175 176 /* 177 * bfq_group handlers 178 * The following functions help in navigating the bfq_group hierarchy 179 * by allowing to find the parent of a bfq_group or the bfq_group 180 * associated to a bfq_queue. 181 */ 182 183 static struct bfq_group *bfqg_parent(struct bfq_group *bfqg) 184 { 185 struct blkcg_gq *pblkg = bfqg_to_blkg(bfqg)->parent; 186 187 return pblkg ? blkg_to_bfqg(pblkg) : NULL; 188 } 189 190 struct bfq_group *bfqq_group(struct bfq_queue *bfqq) 191 { 192 struct bfq_entity *group_entity = bfqq->entity.parent; 193 194 return group_entity ? container_of(group_entity, struct bfq_group, 195 entity) : 196 bfqq->bfqd->root_group; 197 } 198 199 /* 200 * The following two functions handle get and put of a bfq_group by 201 * wrapping the related blk-cgroup hooks. 202 */ 203 204 static void bfqg_get(struct bfq_group *bfqg) 205 { 206 bfqg->ref++; 207 } 208 209 void bfqg_put(struct bfq_group *bfqg) 210 { 211 bfqg->ref--; 212 213 if (bfqg->ref == 0) 214 kfree(bfqg); 215 } 216 217 static void bfqg_and_blkg_get(struct bfq_group *bfqg) 218 { 219 /* see comments in bfq_bic_update_cgroup for why refcounting bfqg */ 220 bfqg_get(bfqg); 221 222 blkg_get(bfqg_to_blkg(bfqg)); 223 } 224 225 void bfqg_and_blkg_put(struct bfq_group *bfqg) 226 { 227 bfqg_put(bfqg); 228 229 blkg_put(bfqg_to_blkg(bfqg)); 230 } 231 232 void bfqg_stats_update_io_add(struct bfq_group *bfqg, struct bfq_queue *bfqq, 233 unsigned int op) 234 { 235 blkg_rwstat_add(&bfqg->stats.queued, op, 1); 236 bfqg_stats_end_empty_time(&bfqg->stats); 237 if (!(bfqq == ((struct bfq_data *)bfqg->bfqd)->in_service_queue)) 238 bfqg_stats_set_start_group_wait_time(bfqg, bfqq_group(bfqq)); 239 } 240 241 void bfqg_stats_update_io_remove(struct bfq_group *bfqg, unsigned int op) 242 { 243 blkg_rwstat_add(&bfqg->stats.queued, op, -1); 244 } 245 246 void bfqg_stats_update_io_merged(struct bfq_group *bfqg, unsigned int op) 247 { 248 blkg_rwstat_add(&bfqg->stats.merged, op, 1); 249 } 250 251 void bfqg_stats_update_completion(struct bfq_group *bfqg, uint64_t start_time, 252 uint64_t io_start_time, unsigned int op) 253 { 254 struct bfqg_stats *stats = &bfqg->stats; 255 unsigned long long now = sched_clock(); 256 257 if (time_after64(now, io_start_time)) 258 blkg_rwstat_add(&stats->service_time, op, 259 now - io_start_time); 260 if (time_after64(io_start_time, start_time)) 261 blkg_rwstat_add(&stats->wait_time, op, 262 io_start_time - start_time); 263 } 264 265 /* @stats = 0 */ 266 static void bfqg_stats_reset(struct bfqg_stats *stats) 267 { 268 /* queued stats shouldn't be cleared */ 269 blkg_rwstat_reset(&stats->merged); 270 blkg_rwstat_reset(&stats->service_time); 271 blkg_rwstat_reset(&stats->wait_time); 272 blkg_stat_reset(&stats->time); 273 blkg_stat_reset(&stats->avg_queue_size_sum); 274 blkg_stat_reset(&stats->avg_queue_size_samples); 275 blkg_stat_reset(&stats->dequeue); 276 blkg_stat_reset(&stats->group_wait_time); 277 blkg_stat_reset(&stats->idle_time); 278 blkg_stat_reset(&stats->empty_time); 279 } 280 281 /* @to += @from */ 282 static void bfqg_stats_add_aux(struct bfqg_stats *to, struct bfqg_stats *from) 283 { 284 if (!to || !from) 285 return; 286 287 /* queued stats shouldn't be cleared */ 288 blkg_rwstat_add_aux(&to->merged, &from->merged); 289 blkg_rwstat_add_aux(&to->service_time, &from->service_time); 290 blkg_rwstat_add_aux(&to->wait_time, &from->wait_time); 291 blkg_stat_add_aux(&from->time, &from->time); 292 blkg_stat_add_aux(&to->avg_queue_size_sum, &from->avg_queue_size_sum); 293 blkg_stat_add_aux(&to->avg_queue_size_samples, 294 &from->avg_queue_size_samples); 295 blkg_stat_add_aux(&to->dequeue, &from->dequeue); 296 blkg_stat_add_aux(&to->group_wait_time, &from->group_wait_time); 297 blkg_stat_add_aux(&to->idle_time, &from->idle_time); 298 blkg_stat_add_aux(&to->empty_time, &from->empty_time); 299 } 300 301 /* 302 * Transfer @bfqg's stats to its parent's aux counts so that the ancestors' 303 * recursive stats can still account for the amount used by this bfqg after 304 * it's gone. 305 */ 306 static void bfqg_stats_xfer_dead(struct bfq_group *bfqg) 307 { 308 struct bfq_group *parent; 309 310 if (!bfqg) /* root_group */ 311 return; 312 313 parent = bfqg_parent(bfqg); 314 315 lockdep_assert_held(bfqg_to_blkg(bfqg)->q->queue_lock); 316 317 if (unlikely(!parent)) 318 return; 319 320 bfqg_stats_add_aux(&parent->stats, &bfqg->stats); 321 bfqg_stats_reset(&bfqg->stats); 322 } 323 324 void bfq_init_entity(struct bfq_entity *entity, struct bfq_group *bfqg) 325 { 326 struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); 327 328 entity->weight = entity->new_weight; 329 entity->orig_weight = entity->new_weight; 330 if (bfqq) { 331 bfqq->ioprio = bfqq->new_ioprio; 332 bfqq->ioprio_class = bfqq->new_ioprio_class; 333 /* 334 * Make sure that bfqg and its associated blkg do not 335 * disappear before entity. 336 */ 337 bfqg_and_blkg_get(bfqg); 338 } 339 entity->parent = bfqg->my_entity; /* NULL for root group */ 340 entity->sched_data = &bfqg->sched_data; 341 } 342 343 static void bfqg_stats_exit(struct bfqg_stats *stats) 344 { 345 blkg_rwstat_exit(&stats->merged); 346 blkg_rwstat_exit(&stats->service_time); 347 blkg_rwstat_exit(&stats->wait_time); 348 blkg_rwstat_exit(&stats->queued); 349 blkg_stat_exit(&stats->time); 350 blkg_stat_exit(&stats->avg_queue_size_sum); 351 blkg_stat_exit(&stats->avg_queue_size_samples); 352 blkg_stat_exit(&stats->dequeue); 353 blkg_stat_exit(&stats->group_wait_time); 354 blkg_stat_exit(&stats->idle_time); 355 blkg_stat_exit(&stats->empty_time); 356 } 357 358 static int bfqg_stats_init(struct bfqg_stats *stats, gfp_t gfp) 359 { 360 if (blkg_rwstat_init(&stats->merged, gfp) || 361 blkg_rwstat_init(&stats->service_time, gfp) || 362 blkg_rwstat_init(&stats->wait_time, gfp) || 363 blkg_rwstat_init(&stats->queued, gfp) || 364 blkg_stat_init(&stats->time, gfp) || 365 blkg_stat_init(&stats->avg_queue_size_sum, gfp) || 366 blkg_stat_init(&stats->avg_queue_size_samples, gfp) || 367 blkg_stat_init(&stats->dequeue, gfp) || 368 blkg_stat_init(&stats->group_wait_time, gfp) || 369 blkg_stat_init(&stats->idle_time, gfp) || 370 blkg_stat_init(&stats->empty_time, gfp)) { 371 bfqg_stats_exit(stats); 372 return -ENOMEM; 373 } 374 375 return 0; 376 } 377 378 static struct bfq_group_data *cpd_to_bfqgd(struct blkcg_policy_data *cpd) 379 { 380 return cpd ? container_of(cpd, struct bfq_group_data, pd) : NULL; 381 } 382 383 static struct bfq_group_data *blkcg_to_bfqgd(struct blkcg *blkcg) 384 { 385 return cpd_to_bfqgd(blkcg_to_cpd(blkcg, &blkcg_policy_bfq)); 386 } 387 388 struct blkcg_policy_data *bfq_cpd_alloc(gfp_t gfp) 389 { 390 struct bfq_group_data *bgd; 391 392 bgd = kzalloc(sizeof(*bgd), gfp); 393 if (!bgd) 394 return NULL; 395 return &bgd->pd; 396 } 397 398 void bfq_cpd_init(struct blkcg_policy_data *cpd) 399 { 400 struct bfq_group_data *d = cpd_to_bfqgd(cpd); 401 402 d->weight = cgroup_subsys_on_dfl(io_cgrp_subsys) ? 403 CGROUP_WEIGHT_DFL : BFQ_WEIGHT_LEGACY_DFL; 404 } 405 406 void bfq_cpd_free(struct blkcg_policy_data *cpd) 407 { 408 kfree(cpd_to_bfqgd(cpd)); 409 } 410 411 struct blkg_policy_data *bfq_pd_alloc(gfp_t gfp, int node) 412 { 413 struct bfq_group *bfqg; 414 415 bfqg = kzalloc_node(sizeof(*bfqg), gfp, node); 416 if (!bfqg) 417 return NULL; 418 419 if (bfqg_stats_init(&bfqg->stats, gfp)) { 420 kfree(bfqg); 421 return NULL; 422 } 423 424 /* see comments in bfq_bic_update_cgroup for why refcounting */ 425 bfqg_get(bfqg); 426 return &bfqg->pd; 427 } 428 429 void bfq_pd_init(struct blkg_policy_data *pd) 430 { 431 struct blkcg_gq *blkg = pd_to_blkg(pd); 432 struct bfq_group *bfqg = blkg_to_bfqg(blkg); 433 struct bfq_data *bfqd = blkg->q->elevator->elevator_data; 434 struct bfq_entity *entity = &bfqg->entity; 435 struct bfq_group_data *d = blkcg_to_bfqgd(blkg->blkcg); 436 437 entity->orig_weight = entity->weight = entity->new_weight = d->weight; 438 entity->my_sched_data = &bfqg->sched_data; 439 bfqg->my_entity = entity; /* 440 * the root_group's will be set to NULL 441 * in bfq_init_queue() 442 */ 443 bfqg->bfqd = bfqd; 444 bfqg->active_entities = 0; 445 bfqg->rq_pos_tree = RB_ROOT; 446 } 447 448 void bfq_pd_free(struct blkg_policy_data *pd) 449 { 450 struct bfq_group *bfqg = pd_to_bfqg(pd); 451 452 bfqg_stats_exit(&bfqg->stats); 453 bfqg_put(bfqg); 454 } 455 456 void bfq_pd_reset_stats(struct blkg_policy_data *pd) 457 { 458 struct bfq_group *bfqg = pd_to_bfqg(pd); 459 460 bfqg_stats_reset(&bfqg->stats); 461 } 462 463 static void bfq_group_set_parent(struct bfq_group *bfqg, 464 struct bfq_group *parent) 465 { 466 struct bfq_entity *entity; 467 468 entity = &bfqg->entity; 469 entity->parent = parent->my_entity; 470 entity->sched_data = &parent->sched_data; 471 } 472 473 static struct bfq_group *bfq_lookup_bfqg(struct bfq_data *bfqd, 474 struct blkcg *blkcg) 475 { 476 struct blkcg_gq *blkg; 477 478 blkg = blkg_lookup(blkcg, bfqd->queue); 479 if (likely(blkg)) 480 return blkg_to_bfqg(blkg); 481 return NULL; 482 } 483 484 struct bfq_group *bfq_find_set_group(struct bfq_data *bfqd, 485 struct blkcg *blkcg) 486 { 487 struct bfq_group *bfqg, *parent; 488 struct bfq_entity *entity; 489 490 bfqg = bfq_lookup_bfqg(bfqd, blkcg); 491 492 if (unlikely(!bfqg)) 493 return NULL; 494 495 /* 496 * Update chain of bfq_groups as we might be handling a leaf group 497 * which, along with some of its relatives, has not been hooked yet 498 * to the private hierarchy of BFQ. 499 */ 500 entity = &bfqg->entity; 501 for_each_entity(entity) { 502 bfqg = container_of(entity, struct bfq_group, entity); 503 if (bfqg != bfqd->root_group) { 504 parent = bfqg_parent(bfqg); 505 if (!parent) 506 parent = bfqd->root_group; 507 bfq_group_set_parent(bfqg, parent); 508 } 509 } 510 511 return bfqg; 512 } 513 514 /** 515 * bfq_bfqq_move - migrate @bfqq to @bfqg. 516 * @bfqd: queue descriptor. 517 * @bfqq: the queue to move. 518 * @bfqg: the group to move to. 519 * 520 * Move @bfqq to @bfqg, deactivating it from its old group and reactivating 521 * it on the new one. Avoid putting the entity on the old group idle tree. 522 * 523 * Must be called under the scheduler lock, to make sure that the blkg 524 * owning @bfqg does not disappear (see comments in 525 * bfq_bic_update_cgroup on guaranteeing the consistency of blkg 526 * objects). 527 */ 528 void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq, 529 struct bfq_group *bfqg) 530 { 531 struct bfq_entity *entity = &bfqq->entity; 532 533 /* If bfqq is empty, then bfq_bfqq_expire also invokes 534 * bfq_del_bfqq_busy, thereby removing bfqq and its entity 535 * from data structures related to current group. Otherwise we 536 * need to remove bfqq explicitly with bfq_deactivate_bfqq, as 537 * we do below. 538 */ 539 if (bfqq == bfqd->in_service_queue) 540 bfq_bfqq_expire(bfqd, bfqd->in_service_queue, 541 false, BFQQE_PREEMPTED); 542 543 if (bfq_bfqq_busy(bfqq)) 544 bfq_deactivate_bfqq(bfqd, bfqq, false, false); 545 else if (entity->on_st) 546 bfq_put_idle_entity(bfq_entity_service_tree(entity), entity); 547 bfqg_and_blkg_put(bfqq_group(bfqq)); 548 549 entity->parent = bfqg->my_entity; 550 entity->sched_data = &bfqg->sched_data; 551 /* pin down bfqg and its associated blkg */ 552 bfqg_and_blkg_get(bfqg); 553 554 if (bfq_bfqq_busy(bfqq)) { 555 bfq_pos_tree_add_move(bfqd, bfqq); 556 bfq_activate_bfqq(bfqd, bfqq); 557 } 558 559 if (!bfqd->in_service_queue && !bfqd->rq_in_driver) 560 bfq_schedule_dispatch(bfqd); 561 } 562 563 /** 564 * __bfq_bic_change_cgroup - move @bic to @cgroup. 565 * @bfqd: the queue descriptor. 566 * @bic: the bic to move. 567 * @blkcg: the blk-cgroup to move to. 568 * 569 * Move bic to blkcg, assuming that bfqd->lock is held; which makes 570 * sure that the reference to cgroup is valid across the call (see 571 * comments in bfq_bic_update_cgroup on this issue) 572 * 573 * NOTE: an alternative approach might have been to store the current 574 * cgroup in bfqq and getting a reference to it, reducing the lookup 575 * time here, at the price of slightly more complex code. 576 */ 577 static struct bfq_group *__bfq_bic_change_cgroup(struct bfq_data *bfqd, 578 struct bfq_io_cq *bic, 579 struct blkcg *blkcg) 580 { 581 struct bfq_queue *async_bfqq = bic_to_bfqq(bic, 0); 582 struct bfq_queue *sync_bfqq = bic_to_bfqq(bic, 1); 583 struct bfq_group *bfqg; 584 struct bfq_entity *entity; 585 586 bfqg = bfq_find_set_group(bfqd, blkcg); 587 588 if (unlikely(!bfqg)) 589 bfqg = bfqd->root_group; 590 591 if (async_bfqq) { 592 entity = &async_bfqq->entity; 593 594 if (entity->sched_data != &bfqg->sched_data) { 595 bic_set_bfqq(bic, NULL, 0); 596 bfq_log_bfqq(bfqd, async_bfqq, 597 "bic_change_group: %p %d", 598 async_bfqq, async_bfqq->ref); 599 bfq_put_queue(async_bfqq); 600 } 601 } 602 603 if (sync_bfqq) { 604 entity = &sync_bfqq->entity; 605 if (entity->sched_data != &bfqg->sched_data) 606 bfq_bfqq_move(bfqd, sync_bfqq, bfqg); 607 } 608 609 return bfqg; 610 } 611 612 void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio) 613 { 614 struct bfq_data *bfqd = bic_to_bfqd(bic); 615 struct bfq_group *bfqg = NULL; 616 uint64_t serial_nr; 617 618 rcu_read_lock(); 619 serial_nr = bio_blkcg(bio)->css.serial_nr; 620 621 /* 622 * Check whether blkcg has changed. The condition may trigger 623 * spuriously on a newly created cic but there's no harm. 624 */ 625 if (unlikely(!bfqd) || likely(bic->blkcg_serial_nr == serial_nr)) 626 goto out; 627 628 bfqg = __bfq_bic_change_cgroup(bfqd, bic, bio_blkcg(bio)); 629 /* 630 * Update blkg_path for bfq_log_* functions. We cache this 631 * path, and update it here, for the following 632 * reasons. Operations on blkg objects in blk-cgroup are 633 * protected with the request_queue lock, and not with the 634 * lock that protects the instances of this scheduler 635 * (bfqd->lock). This exposes BFQ to the following sort of 636 * race. 637 * 638 * The blkg_lookup performed in bfq_get_queue, protected 639 * through rcu, may happen to return the address of a copy of 640 * the original blkg. If this is the case, then the 641 * bfqg_and_blkg_get performed in bfq_get_queue, to pin down 642 * the blkg, is useless: it does not prevent blk-cgroup code 643 * from destroying both the original blkg and all objects 644 * directly or indirectly referred by the copy of the 645 * blkg. 646 * 647 * On the bright side, destroy operations on a blkg invoke, as 648 * a first step, hooks of the scheduler associated with the 649 * blkg. And these hooks are executed with bfqd->lock held for 650 * BFQ. As a consequence, for any blkg associated with the 651 * request queue this instance of the scheduler is attached 652 * to, we are guaranteed that such a blkg is not destroyed, and 653 * that all the pointers it contains are consistent, while we 654 * are holding bfqd->lock. A blkg_lookup performed with 655 * bfqd->lock held then returns a fully consistent blkg, which 656 * remains consistent until this lock is held. 657 * 658 * Thanks to the last fact, and to the fact that: (1) bfqg has 659 * been obtained through a blkg_lookup in the above 660 * assignment, and (2) bfqd->lock is being held, here we can 661 * safely use the policy data for the involved blkg (i.e., the 662 * field bfqg->pd) to get to the blkg associated with bfqg, 663 * and then we can safely use any field of blkg. After we 664 * release bfqd->lock, even just getting blkg through this 665 * bfqg may cause dangling references to be traversed, as 666 * bfqg->pd may not exist any more. 667 * 668 * In view of the above facts, here we cache, in the bfqg, any 669 * blkg data we may need for this bic, and for its associated 670 * bfq_queue. As of now, we need to cache only the path of the 671 * blkg, which is used in the bfq_log_* functions. 672 * 673 * Finally, note that bfqg itself needs to be protected from 674 * destruction on the blkg_free of the original blkg (which 675 * invokes bfq_pd_free). We use an additional private 676 * refcounter for bfqg, to let it disappear only after no 677 * bfq_queue refers to it any longer. 678 */ 679 blkg_path(bfqg_to_blkg(bfqg), bfqg->blkg_path, sizeof(bfqg->blkg_path)); 680 bic->blkcg_serial_nr = serial_nr; 681 out: 682 rcu_read_unlock(); 683 } 684 685 /** 686 * bfq_flush_idle_tree - deactivate any entity on the idle tree of @st. 687 * @st: the service tree being flushed. 688 */ 689 static void bfq_flush_idle_tree(struct bfq_service_tree *st) 690 { 691 struct bfq_entity *entity = st->first_idle; 692 693 for (; entity ; entity = st->first_idle) 694 __bfq_deactivate_entity(entity, false); 695 } 696 697 /** 698 * bfq_reparent_leaf_entity - move leaf entity to the root_group. 699 * @bfqd: the device data structure with the root group. 700 * @entity: the entity to move. 701 */ 702 static void bfq_reparent_leaf_entity(struct bfq_data *bfqd, 703 struct bfq_entity *entity) 704 { 705 struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); 706 707 bfq_bfqq_move(bfqd, bfqq, bfqd->root_group); 708 } 709 710 /** 711 * bfq_reparent_active_entities - move to the root group all active 712 * entities. 713 * @bfqd: the device data structure with the root group. 714 * @bfqg: the group to move from. 715 * @st: the service tree with the entities. 716 */ 717 static void bfq_reparent_active_entities(struct bfq_data *bfqd, 718 struct bfq_group *bfqg, 719 struct bfq_service_tree *st) 720 { 721 struct rb_root *active = &st->active; 722 struct bfq_entity *entity = NULL; 723 724 if (!RB_EMPTY_ROOT(&st->active)) 725 entity = bfq_entity_of(rb_first(active)); 726 727 for (; entity ; entity = bfq_entity_of(rb_first(active))) 728 bfq_reparent_leaf_entity(bfqd, entity); 729 730 if (bfqg->sched_data.in_service_entity) 731 bfq_reparent_leaf_entity(bfqd, 732 bfqg->sched_data.in_service_entity); 733 } 734 735 /** 736 * bfq_pd_offline - deactivate the entity associated with @pd, 737 * and reparent its children entities. 738 * @pd: descriptor of the policy going offline. 739 * 740 * blkio already grabs the queue_lock for us, so no need to use 741 * RCU-based magic 742 */ 743 void bfq_pd_offline(struct blkg_policy_data *pd) 744 { 745 struct bfq_service_tree *st; 746 struct bfq_group *bfqg = pd_to_bfqg(pd); 747 struct bfq_data *bfqd = bfqg->bfqd; 748 struct bfq_entity *entity = bfqg->my_entity; 749 unsigned long flags; 750 int i; 751 752 if (!entity) /* root group */ 753 return; 754 755 spin_lock_irqsave(&bfqd->lock, flags); 756 /* 757 * Empty all service_trees belonging to this group before 758 * deactivating the group itself. 759 */ 760 for (i = 0; i < BFQ_IOPRIO_CLASSES; i++) { 761 st = bfqg->sched_data.service_tree + i; 762 763 /* 764 * The idle tree may still contain bfq_queues belonging 765 * to exited task because they never migrated to a different 766 * cgroup from the one being destroyed now. 767 */ 768 bfq_flush_idle_tree(st); 769 770 /* 771 * It may happen that some queues are still active 772 * (busy) upon group destruction (if the corresponding 773 * processes have been forced to terminate). We move 774 * all the leaf entities corresponding to these queues 775 * to the root_group. 776 * Also, it may happen that the group has an entity 777 * in service, which is disconnected from the active 778 * tree: it must be moved, too. 779 * There is no need to put the sync queues, as the 780 * scheduler has taken no reference. 781 */ 782 bfq_reparent_active_entities(bfqd, bfqg, st); 783 } 784 785 __bfq_deactivate_entity(entity, false); 786 bfq_put_async_queues(bfqd, bfqg); 787 788 spin_unlock_irqrestore(&bfqd->lock, flags); 789 /* 790 * @blkg is going offline and will be ignored by 791 * blkg_[rw]stat_recursive_sum(). Transfer stats to the parent so 792 * that they don't get lost. If IOs complete after this point, the 793 * stats for them will be lost. Oh well... 794 */ 795 bfqg_stats_xfer_dead(bfqg); 796 } 797 798 void bfq_end_wr_async(struct bfq_data *bfqd) 799 { 800 struct blkcg_gq *blkg; 801 802 list_for_each_entry(blkg, &bfqd->queue->blkg_list, q_node) { 803 struct bfq_group *bfqg = blkg_to_bfqg(blkg); 804 805 bfq_end_wr_async_queues(bfqd, bfqg); 806 } 807 bfq_end_wr_async_queues(bfqd, bfqd->root_group); 808 } 809 810 static int bfq_io_show_weight(struct seq_file *sf, void *v) 811 { 812 struct blkcg *blkcg = css_to_blkcg(seq_css(sf)); 813 struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg); 814 unsigned int val = 0; 815 816 if (bfqgd) 817 val = bfqgd->weight; 818 819 seq_printf(sf, "%u\n", val); 820 821 return 0; 822 } 823 824 static int bfq_io_set_weight_legacy(struct cgroup_subsys_state *css, 825 struct cftype *cftype, 826 u64 val) 827 { 828 struct blkcg *blkcg = css_to_blkcg(css); 829 struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg); 830 struct blkcg_gq *blkg; 831 int ret = -ERANGE; 832 833 if (val < BFQ_MIN_WEIGHT || val > BFQ_MAX_WEIGHT) 834 return ret; 835 836 ret = 0; 837 spin_lock_irq(&blkcg->lock); 838 bfqgd->weight = (unsigned short)val; 839 hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) { 840 struct bfq_group *bfqg = blkg_to_bfqg(blkg); 841 842 if (!bfqg) 843 continue; 844 /* 845 * Setting the prio_changed flag of the entity 846 * to 1 with new_weight == weight would re-set 847 * the value of the weight to its ioprio mapping. 848 * Set the flag only if necessary. 849 */ 850 if ((unsigned short)val != bfqg->entity.new_weight) { 851 bfqg->entity.new_weight = (unsigned short)val; 852 /* 853 * Make sure that the above new value has been 854 * stored in bfqg->entity.new_weight before 855 * setting the prio_changed flag. In fact, 856 * this flag may be read asynchronously (in 857 * critical sections protected by a different 858 * lock than that held here), and finding this 859 * flag set may cause the execution of the code 860 * for updating parameters whose value may 861 * depend also on bfqg->entity.new_weight (in 862 * __bfq_entity_update_weight_prio). 863 * This barrier makes sure that the new value 864 * of bfqg->entity.new_weight is correctly 865 * seen in that code. 866 */ 867 smp_wmb(); 868 bfqg->entity.prio_changed = 1; 869 } 870 } 871 spin_unlock_irq(&blkcg->lock); 872 873 return ret; 874 } 875 876 static ssize_t bfq_io_set_weight(struct kernfs_open_file *of, 877 char *buf, size_t nbytes, 878 loff_t off) 879 { 880 u64 weight; 881 /* First unsigned long found in the file is used */ 882 int ret = kstrtoull(strim(buf), 0, &weight); 883 884 if (ret) 885 return ret; 886 887 return bfq_io_set_weight_legacy(of_css(of), NULL, weight); 888 } 889 890 static int bfqg_print_stat(struct seq_file *sf, void *v) 891 { 892 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_stat, 893 &blkcg_policy_bfq, seq_cft(sf)->private, false); 894 return 0; 895 } 896 897 static int bfqg_print_rwstat(struct seq_file *sf, void *v) 898 { 899 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_rwstat, 900 &blkcg_policy_bfq, seq_cft(sf)->private, true); 901 return 0; 902 } 903 904 static u64 bfqg_prfill_stat_recursive(struct seq_file *sf, 905 struct blkg_policy_data *pd, int off) 906 { 907 u64 sum = blkg_stat_recursive_sum(pd_to_blkg(pd), 908 &blkcg_policy_bfq, off); 909 return __blkg_prfill_u64(sf, pd, sum); 910 } 911 912 static u64 bfqg_prfill_rwstat_recursive(struct seq_file *sf, 913 struct blkg_policy_data *pd, int off) 914 { 915 struct blkg_rwstat sum = blkg_rwstat_recursive_sum(pd_to_blkg(pd), 916 &blkcg_policy_bfq, 917 off); 918 return __blkg_prfill_rwstat(sf, pd, &sum); 919 } 920 921 static int bfqg_print_stat_recursive(struct seq_file *sf, void *v) 922 { 923 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), 924 bfqg_prfill_stat_recursive, &blkcg_policy_bfq, 925 seq_cft(sf)->private, false); 926 return 0; 927 } 928 929 static int bfqg_print_rwstat_recursive(struct seq_file *sf, void *v) 930 { 931 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), 932 bfqg_prfill_rwstat_recursive, &blkcg_policy_bfq, 933 seq_cft(sf)->private, true); 934 return 0; 935 } 936 937 static u64 bfqg_prfill_sectors(struct seq_file *sf, struct blkg_policy_data *pd, 938 int off) 939 { 940 u64 sum = blkg_rwstat_total(&pd->blkg->stat_bytes); 941 942 return __blkg_prfill_u64(sf, pd, sum >> 9); 943 } 944 945 static int bfqg_print_stat_sectors(struct seq_file *sf, void *v) 946 { 947 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), 948 bfqg_prfill_sectors, &blkcg_policy_bfq, 0, false); 949 return 0; 950 } 951 952 static u64 bfqg_prfill_sectors_recursive(struct seq_file *sf, 953 struct blkg_policy_data *pd, int off) 954 { 955 struct blkg_rwstat tmp = blkg_rwstat_recursive_sum(pd->blkg, NULL, 956 offsetof(struct blkcg_gq, stat_bytes)); 957 u64 sum = atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_READ]) + 958 atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_WRITE]); 959 960 return __blkg_prfill_u64(sf, pd, sum >> 9); 961 } 962 963 static int bfqg_print_stat_sectors_recursive(struct seq_file *sf, void *v) 964 { 965 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), 966 bfqg_prfill_sectors_recursive, &blkcg_policy_bfq, 0, 967 false); 968 return 0; 969 } 970 971 static u64 bfqg_prfill_avg_queue_size(struct seq_file *sf, 972 struct blkg_policy_data *pd, int off) 973 { 974 struct bfq_group *bfqg = pd_to_bfqg(pd); 975 u64 samples = blkg_stat_read(&bfqg->stats.avg_queue_size_samples); 976 u64 v = 0; 977 978 if (samples) { 979 v = blkg_stat_read(&bfqg->stats.avg_queue_size_sum); 980 v = div64_u64(v, samples); 981 } 982 __blkg_prfill_u64(sf, pd, v); 983 return 0; 984 } 985 986 /* print avg_queue_size */ 987 static int bfqg_print_avg_queue_size(struct seq_file *sf, void *v) 988 { 989 blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), 990 bfqg_prfill_avg_queue_size, &blkcg_policy_bfq, 991 0, false); 992 return 0; 993 } 994 995 struct bfq_group *bfq_create_group_hierarchy(struct bfq_data *bfqd, int node) 996 { 997 int ret; 998 999 ret = blkcg_activate_policy(bfqd->queue, &blkcg_policy_bfq); 1000 if (ret) 1001 return NULL; 1002 1003 return blkg_to_bfqg(bfqd->queue->root_blkg); 1004 } 1005 1006 struct blkcg_policy blkcg_policy_bfq = { 1007 .dfl_cftypes = bfq_blkg_files, 1008 .legacy_cftypes = bfq_blkcg_legacy_files, 1009 1010 .cpd_alloc_fn = bfq_cpd_alloc, 1011 .cpd_init_fn = bfq_cpd_init, 1012 .cpd_bind_fn = bfq_cpd_init, 1013 .cpd_free_fn = bfq_cpd_free, 1014 1015 .pd_alloc_fn = bfq_pd_alloc, 1016 .pd_init_fn = bfq_pd_init, 1017 .pd_offline_fn = bfq_pd_offline, 1018 .pd_free_fn = bfq_pd_free, 1019 .pd_reset_stats_fn = bfq_pd_reset_stats, 1020 }; 1021 1022 struct cftype bfq_blkcg_legacy_files[] = { 1023 { 1024 .name = "bfq.weight", 1025 .flags = CFTYPE_NOT_ON_ROOT, 1026 .seq_show = bfq_io_show_weight, 1027 .write_u64 = bfq_io_set_weight_legacy, 1028 }, 1029 1030 /* statistics, covers only the tasks in the bfqg */ 1031 { 1032 .name = "bfq.time", 1033 .private = offsetof(struct bfq_group, stats.time), 1034 .seq_show = bfqg_print_stat, 1035 }, 1036 { 1037 .name = "bfq.sectors", 1038 .seq_show = bfqg_print_stat_sectors, 1039 }, 1040 { 1041 .name = "bfq.io_service_bytes", 1042 .private = (unsigned long)&blkcg_policy_bfq, 1043 .seq_show = blkg_print_stat_bytes, 1044 }, 1045 { 1046 .name = "bfq.io_serviced", 1047 .private = (unsigned long)&blkcg_policy_bfq, 1048 .seq_show = blkg_print_stat_ios, 1049 }, 1050 { 1051 .name = "bfq.io_service_time", 1052 .private = offsetof(struct bfq_group, stats.service_time), 1053 .seq_show = bfqg_print_rwstat, 1054 }, 1055 { 1056 .name = "bfq.io_wait_time", 1057 .private = offsetof(struct bfq_group, stats.wait_time), 1058 .seq_show = bfqg_print_rwstat, 1059 }, 1060 { 1061 .name = "bfq.io_merged", 1062 .private = offsetof(struct bfq_group, stats.merged), 1063 .seq_show = bfqg_print_rwstat, 1064 }, 1065 { 1066 .name = "bfq.io_queued", 1067 .private = offsetof(struct bfq_group, stats.queued), 1068 .seq_show = bfqg_print_rwstat, 1069 }, 1070 1071 /* the same statictics which cover the bfqg and its descendants */ 1072 { 1073 .name = "bfq.time_recursive", 1074 .private = offsetof(struct bfq_group, stats.time), 1075 .seq_show = bfqg_print_stat_recursive, 1076 }, 1077 { 1078 .name = "bfq.sectors_recursive", 1079 .seq_show = bfqg_print_stat_sectors_recursive, 1080 }, 1081 { 1082 .name = "bfq.io_service_bytes_recursive", 1083 .private = (unsigned long)&blkcg_policy_bfq, 1084 .seq_show = blkg_print_stat_bytes_recursive, 1085 }, 1086 { 1087 .name = "bfq.io_serviced_recursive", 1088 .private = (unsigned long)&blkcg_policy_bfq, 1089 .seq_show = blkg_print_stat_ios_recursive, 1090 }, 1091 { 1092 .name = "bfq.io_service_time_recursive", 1093 .private = offsetof(struct bfq_group, stats.service_time), 1094 .seq_show = bfqg_print_rwstat_recursive, 1095 }, 1096 { 1097 .name = "bfq.io_wait_time_recursive", 1098 .private = offsetof(struct bfq_group, stats.wait_time), 1099 .seq_show = bfqg_print_rwstat_recursive, 1100 }, 1101 { 1102 .name = "bfq.io_merged_recursive", 1103 .private = offsetof(struct bfq_group, stats.merged), 1104 .seq_show = bfqg_print_rwstat_recursive, 1105 }, 1106 { 1107 .name = "bfq.io_queued_recursive", 1108 .private = offsetof(struct bfq_group, stats.queued), 1109 .seq_show = bfqg_print_rwstat_recursive, 1110 }, 1111 { 1112 .name = "bfq.avg_queue_size", 1113 .seq_show = bfqg_print_avg_queue_size, 1114 }, 1115 { 1116 .name = "bfq.group_wait_time", 1117 .private = offsetof(struct bfq_group, stats.group_wait_time), 1118 .seq_show = bfqg_print_stat, 1119 }, 1120 { 1121 .name = "bfq.idle_time", 1122 .private = offsetof(struct bfq_group, stats.idle_time), 1123 .seq_show = bfqg_print_stat, 1124 }, 1125 { 1126 .name = "bfq.empty_time", 1127 .private = offsetof(struct bfq_group, stats.empty_time), 1128 .seq_show = bfqg_print_stat, 1129 }, 1130 { 1131 .name = "bfq.dequeue", 1132 .private = offsetof(struct bfq_group, stats.dequeue), 1133 .seq_show = bfqg_print_stat, 1134 }, 1135 { } /* terminate */ 1136 }; 1137 1138 struct cftype bfq_blkg_files[] = { 1139 { 1140 .name = "bfq.weight", 1141 .flags = CFTYPE_NOT_ON_ROOT, 1142 .seq_show = bfq_io_show_weight, 1143 .write = bfq_io_set_weight, 1144 }, 1145 {} /* terminate */ 1146 }; 1147 1148 #else /* CONFIG_BFQ_GROUP_IOSCHED */ 1149 1150 void bfqg_stats_update_io_add(struct bfq_group *bfqg, struct bfq_queue *bfqq, 1151 unsigned int op) { } 1152 void bfqg_stats_update_io_remove(struct bfq_group *bfqg, unsigned int op) { } 1153 void bfqg_stats_update_io_merged(struct bfq_group *bfqg, unsigned int op) { } 1154 void bfqg_stats_update_completion(struct bfq_group *bfqg, uint64_t start_time, 1155 uint64_t io_start_time, unsigned int op) { } 1156 void bfqg_stats_update_dequeue(struct bfq_group *bfqg) { } 1157 void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg) { } 1158 void bfqg_stats_update_idle_time(struct bfq_group *bfqg) { } 1159 void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg) { } 1160 void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg) { } 1161 1162 void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq, 1163 struct bfq_group *bfqg) {} 1164 1165 void bfq_init_entity(struct bfq_entity *entity, struct bfq_group *bfqg) 1166 { 1167 struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity); 1168 1169 entity->weight = entity->new_weight; 1170 entity->orig_weight = entity->new_weight; 1171 if (bfqq) { 1172 bfqq->ioprio = bfqq->new_ioprio; 1173 bfqq->ioprio_class = bfqq->new_ioprio_class; 1174 } 1175 entity->sched_data = &bfqg->sched_data; 1176 } 1177 1178 void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio) {} 1179 1180 void bfq_end_wr_async(struct bfq_data *bfqd) 1181 { 1182 bfq_end_wr_async_queues(bfqd, bfqd->root_group); 1183 } 1184 1185 struct bfq_group *bfq_find_set_group(struct bfq_data *bfqd, struct blkcg *blkcg) 1186 { 1187 return bfqd->root_group; 1188 } 1189 1190 struct bfq_group *bfqq_group(struct bfq_queue *bfqq) 1191 { 1192 return bfqq->bfqd->root_group; 1193 } 1194 1195 struct bfq_group *bfq_create_group_hierarchy(struct bfq_data *bfqd, int node) 1196 { 1197 struct bfq_group *bfqg; 1198 int i; 1199 1200 bfqg = kmalloc_node(sizeof(*bfqg), GFP_KERNEL | __GFP_ZERO, node); 1201 if (!bfqg) 1202 return NULL; 1203 1204 for (i = 0; i < BFQ_IOPRIO_CLASSES; i++) 1205 bfqg->sched_data.service_tree[i] = BFQ_SERVICE_TREE_INIT; 1206 1207 return bfqg; 1208 } 1209 #endif /* CONFIG_BFQ_GROUP_IOSCHED */ 1210