linux/block/bfq-cgroup.c
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   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 * cgroups support for the BFQ I/O scheduler.
   4 */
   5#include <linux/module.h>
   6#include <linux/slab.h>
   7#include <linux/blkdev.h>
   8#include <linux/cgroup.h>
   9#include <linux/elevator.h>
  10#include <linux/ktime.h>
  11#include <linux/rbtree.h>
  12#include <linux/ioprio.h>
  13#include <linux/sbitmap.h>
  14#include <linux/delay.h>
  15
  16#include "bfq-iosched.h"
  17
  18#ifdef CONFIG_BFQ_CGROUP_DEBUG
  19static int bfq_stat_init(struct bfq_stat *stat, gfp_t gfp)
  20{
  21        int ret;
  22
  23        ret = percpu_counter_init(&stat->cpu_cnt, 0, gfp);
  24        if (ret)
  25                return ret;
  26
  27        atomic64_set(&stat->aux_cnt, 0);
  28        return 0;
  29}
  30
  31static void bfq_stat_exit(struct bfq_stat *stat)
  32{
  33        percpu_counter_destroy(&stat->cpu_cnt);
  34}
  35
  36/**
  37 * bfq_stat_add - add a value to a bfq_stat
  38 * @stat: target bfq_stat
  39 * @val: value to add
  40 *
  41 * Add @val to @stat.  The caller must ensure that IRQ on the same CPU
  42 * don't re-enter this function for the same counter.
  43 */
  44static inline void bfq_stat_add(struct bfq_stat *stat, uint64_t val)
  45{
  46        percpu_counter_add_batch(&stat->cpu_cnt, val, BLKG_STAT_CPU_BATCH);
  47}
  48
  49/**
  50 * bfq_stat_read - read the current value of a bfq_stat
  51 * @stat: bfq_stat to read
  52 */
  53static inline uint64_t bfq_stat_read(struct bfq_stat *stat)
  54{
  55        return percpu_counter_sum_positive(&stat->cpu_cnt);
  56}
  57
  58/**
  59 * bfq_stat_reset - reset a bfq_stat
  60 * @stat: bfq_stat to reset
  61 */
  62static inline void bfq_stat_reset(struct bfq_stat *stat)
  63{
  64        percpu_counter_set(&stat->cpu_cnt, 0);
  65        atomic64_set(&stat->aux_cnt, 0);
  66}
  67
  68/**
  69 * bfq_stat_add_aux - add a bfq_stat into another's aux count
  70 * @to: the destination bfq_stat
  71 * @from: the source
  72 *
  73 * Add @from's count including the aux one to @to's aux count.
  74 */
  75static inline void bfq_stat_add_aux(struct bfq_stat *to,
  76                                     struct bfq_stat *from)
  77{
  78        atomic64_add(bfq_stat_read(from) + atomic64_read(&from->aux_cnt),
  79                     &to->aux_cnt);
  80}
  81
  82/**
  83 * blkg_prfill_stat - prfill callback for bfq_stat
  84 * @sf: seq_file to print to
  85 * @pd: policy private data of interest
  86 * @off: offset to the bfq_stat in @pd
  87 *
  88 * prfill callback for printing a bfq_stat.
  89 */
  90static u64 blkg_prfill_stat(struct seq_file *sf, struct blkg_policy_data *pd,
  91                int off)
  92{
  93        return __blkg_prfill_u64(sf, pd, bfq_stat_read((void *)pd + off));
  94}
  95
  96/* bfqg stats flags */
  97enum bfqg_stats_flags {
  98        BFQG_stats_waiting = 0,
  99        BFQG_stats_idling,
 100        BFQG_stats_empty,
 101};
 102
 103#define BFQG_FLAG_FNS(name)                                             \
 104static void bfqg_stats_mark_##name(struct bfqg_stats *stats)    \
 105{                                                                       \
 106        stats->flags |= (1 << BFQG_stats_##name);                       \
 107}                                                                       \
 108static void bfqg_stats_clear_##name(struct bfqg_stats *stats)   \
 109{                                                                       \
 110        stats->flags &= ~(1 << BFQG_stats_##name);                      \
 111}                                                                       \
 112static int bfqg_stats_##name(struct bfqg_stats *stats)          \
 113{                                                                       \
 114        return (stats->flags & (1 << BFQG_stats_##name)) != 0;          \
 115}                                                                       \
 116
 117BFQG_FLAG_FNS(waiting)
 118BFQG_FLAG_FNS(idling)
 119BFQG_FLAG_FNS(empty)
 120#undef BFQG_FLAG_FNS
 121
 122/* This should be called with the scheduler lock held. */
 123static void bfqg_stats_update_group_wait_time(struct bfqg_stats *stats)
 124{
 125        u64 now;
 126
 127        if (!bfqg_stats_waiting(stats))
 128                return;
 129
 130        now = ktime_get_ns();
 131        if (now > stats->start_group_wait_time)
 132                bfq_stat_add(&stats->group_wait_time,
 133                              now - stats->start_group_wait_time);
 134        bfqg_stats_clear_waiting(stats);
 135}
 136
 137/* This should be called with the scheduler lock held. */
 138static void bfqg_stats_set_start_group_wait_time(struct bfq_group *bfqg,
 139                                                 struct bfq_group *curr_bfqg)
 140{
 141        struct bfqg_stats *stats = &bfqg->stats;
 142
 143        if (bfqg_stats_waiting(stats))
 144                return;
 145        if (bfqg == curr_bfqg)
 146                return;
 147        stats->start_group_wait_time = ktime_get_ns();
 148        bfqg_stats_mark_waiting(stats);
 149}
 150
 151/* This should be called with the scheduler lock held. */
 152static void bfqg_stats_end_empty_time(struct bfqg_stats *stats)
 153{
 154        u64 now;
 155
 156        if (!bfqg_stats_empty(stats))
 157                return;
 158
 159        now = ktime_get_ns();
 160        if (now > stats->start_empty_time)
 161                bfq_stat_add(&stats->empty_time,
 162                              now - stats->start_empty_time);
 163        bfqg_stats_clear_empty(stats);
 164}
 165
 166void bfqg_stats_update_dequeue(struct bfq_group *bfqg)
 167{
 168        bfq_stat_add(&bfqg->stats.dequeue, 1);
 169}
 170
 171void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg)
 172{
 173        struct bfqg_stats *stats = &bfqg->stats;
 174
 175        if (blkg_rwstat_total(&stats->queued))
 176                return;
 177
 178        /*
 179         * group is already marked empty. This can happen if bfqq got new
 180         * request in parent group and moved to this group while being added
 181         * to service tree. Just ignore the event and move on.
 182         */
 183        if (bfqg_stats_empty(stats))
 184                return;
 185
 186        stats->start_empty_time = ktime_get_ns();
 187        bfqg_stats_mark_empty(stats);
 188}
 189
 190void bfqg_stats_update_idle_time(struct bfq_group *bfqg)
 191{
 192        struct bfqg_stats *stats = &bfqg->stats;
 193
 194        if (bfqg_stats_idling(stats)) {
 195                u64 now = ktime_get_ns();
 196
 197                if (now > stats->start_idle_time)
 198                        bfq_stat_add(&stats->idle_time,
 199                                      now - stats->start_idle_time);
 200                bfqg_stats_clear_idling(stats);
 201        }
 202}
 203
 204void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg)
 205{
 206        struct bfqg_stats *stats = &bfqg->stats;
 207
 208        stats->start_idle_time = ktime_get_ns();
 209        bfqg_stats_mark_idling(stats);
 210}
 211
 212void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg)
 213{
 214        struct bfqg_stats *stats = &bfqg->stats;
 215
 216        bfq_stat_add(&stats->avg_queue_size_sum,
 217                      blkg_rwstat_total(&stats->queued));
 218        bfq_stat_add(&stats->avg_queue_size_samples, 1);
 219        bfqg_stats_update_group_wait_time(stats);
 220}
 221
 222void bfqg_stats_update_io_add(struct bfq_group *bfqg, struct bfq_queue *bfqq,
 223                              unsigned int op)
 224{
 225        blkg_rwstat_add(&bfqg->stats.queued, op, 1);
 226        bfqg_stats_end_empty_time(&bfqg->stats);
 227        if (!(bfqq == ((struct bfq_data *)bfqg->bfqd)->in_service_queue))
 228                bfqg_stats_set_start_group_wait_time(bfqg, bfqq_group(bfqq));
 229}
 230
 231void bfqg_stats_update_io_remove(struct bfq_group *bfqg, unsigned int op)
 232{
 233        blkg_rwstat_add(&bfqg->stats.queued, op, -1);
 234}
 235
 236void bfqg_stats_update_io_merged(struct bfq_group *bfqg, unsigned int op)
 237{
 238        blkg_rwstat_add(&bfqg->stats.merged, op, 1);
 239}
 240
 241void bfqg_stats_update_completion(struct bfq_group *bfqg, u64 start_time_ns,
 242                                  u64 io_start_time_ns, unsigned int op)
 243{
 244        struct bfqg_stats *stats = &bfqg->stats;
 245        u64 now = ktime_get_ns();
 246
 247        if (now > io_start_time_ns)
 248                blkg_rwstat_add(&stats->service_time, op,
 249                                now - io_start_time_ns);
 250        if (io_start_time_ns > start_time_ns)
 251                blkg_rwstat_add(&stats->wait_time, op,
 252                                io_start_time_ns - start_time_ns);
 253}
 254
 255#else /* CONFIG_BFQ_CGROUP_DEBUG */
 256
 257void bfqg_stats_update_io_add(struct bfq_group *bfqg, struct bfq_queue *bfqq,
 258                              unsigned int op) { }
 259void bfqg_stats_update_io_remove(struct bfq_group *bfqg, unsigned int op) { }
 260void bfqg_stats_update_io_merged(struct bfq_group *bfqg, unsigned int op) { }
 261void bfqg_stats_update_completion(struct bfq_group *bfqg, u64 start_time_ns,
 262                                  u64 io_start_time_ns, unsigned int op) { }
 263void bfqg_stats_update_dequeue(struct bfq_group *bfqg) { }
 264void bfqg_stats_set_start_empty_time(struct bfq_group *bfqg) { }
 265void bfqg_stats_update_idle_time(struct bfq_group *bfqg) { }
 266void bfqg_stats_set_start_idle_time(struct bfq_group *bfqg) { }
 267void bfqg_stats_update_avg_queue_size(struct bfq_group *bfqg) { }
 268
 269#endif /* CONFIG_BFQ_CGROUP_DEBUG */
 270
 271#ifdef CONFIG_BFQ_GROUP_IOSCHED
 272
 273/*
 274 * blk-cgroup policy-related handlers
 275 * The following functions help in converting between blk-cgroup
 276 * internal structures and BFQ-specific structures.
 277 */
 278
 279static struct bfq_group *pd_to_bfqg(struct blkg_policy_data *pd)
 280{
 281        return pd ? container_of(pd, struct bfq_group, pd) : NULL;
 282}
 283
 284struct blkcg_gq *bfqg_to_blkg(struct bfq_group *bfqg)
 285{
 286        return pd_to_blkg(&bfqg->pd);
 287}
 288
 289static struct bfq_group *blkg_to_bfqg(struct blkcg_gq *blkg)
 290{
 291        return pd_to_bfqg(blkg_to_pd(blkg, &blkcg_policy_bfq));
 292}
 293
 294/*
 295 * bfq_group handlers
 296 * The following functions help in navigating the bfq_group hierarchy
 297 * by allowing to find the parent of a bfq_group or the bfq_group
 298 * associated to a bfq_queue.
 299 */
 300
 301static struct bfq_group *bfqg_parent(struct bfq_group *bfqg)
 302{
 303        struct blkcg_gq *pblkg = bfqg_to_blkg(bfqg)->parent;
 304
 305        return pblkg ? blkg_to_bfqg(pblkg) : NULL;
 306}
 307
 308struct bfq_group *bfqq_group(struct bfq_queue *bfqq)
 309{
 310        struct bfq_entity *group_entity = bfqq->entity.parent;
 311
 312        return group_entity ? container_of(group_entity, struct bfq_group,
 313                                           entity) :
 314                              bfqq->bfqd->root_group;
 315}
 316
 317/*
 318 * The following two functions handle get and put of a bfq_group by
 319 * wrapping the related blk-cgroup hooks.
 320 */
 321
 322static void bfqg_get(struct bfq_group *bfqg)
 323{
 324        bfqg->ref++;
 325}
 326
 327static void bfqg_put(struct bfq_group *bfqg)
 328{
 329        bfqg->ref--;
 330
 331        if (bfqg->ref == 0)
 332                kfree(bfqg);
 333}
 334
 335void bfqg_and_blkg_get(struct bfq_group *bfqg)
 336{
 337        /* see comments in bfq_bic_update_cgroup for why refcounting bfqg */
 338        bfqg_get(bfqg);
 339
 340        blkg_get(bfqg_to_blkg(bfqg));
 341}
 342
 343void bfqg_and_blkg_put(struct bfq_group *bfqg)
 344{
 345        blkg_put(bfqg_to_blkg(bfqg));
 346
 347        bfqg_put(bfqg);
 348}
 349
 350void bfqg_stats_update_legacy_io(struct request_queue *q, struct request *rq)
 351{
 352        struct bfq_group *bfqg = blkg_to_bfqg(rq->bio->bi_blkg);
 353
 354        if (!bfqg)
 355                return;
 356
 357        blkg_rwstat_add(&bfqg->stats.bytes, rq->cmd_flags, blk_rq_bytes(rq));
 358        blkg_rwstat_add(&bfqg->stats.ios, rq->cmd_flags, 1);
 359}
 360
 361/* @stats = 0 */
 362static void bfqg_stats_reset(struct bfqg_stats *stats)
 363{
 364#ifdef CONFIG_BFQ_CGROUP_DEBUG
 365        /* queued stats shouldn't be cleared */
 366        blkg_rwstat_reset(&stats->merged);
 367        blkg_rwstat_reset(&stats->service_time);
 368        blkg_rwstat_reset(&stats->wait_time);
 369        bfq_stat_reset(&stats->time);
 370        bfq_stat_reset(&stats->avg_queue_size_sum);
 371        bfq_stat_reset(&stats->avg_queue_size_samples);
 372        bfq_stat_reset(&stats->dequeue);
 373        bfq_stat_reset(&stats->group_wait_time);
 374        bfq_stat_reset(&stats->idle_time);
 375        bfq_stat_reset(&stats->empty_time);
 376#endif
 377}
 378
 379/* @to += @from */
 380static void bfqg_stats_add_aux(struct bfqg_stats *to, struct bfqg_stats *from)
 381{
 382        if (!to || !from)
 383                return;
 384
 385#ifdef CONFIG_BFQ_CGROUP_DEBUG
 386        /* queued stats shouldn't be cleared */
 387        blkg_rwstat_add_aux(&to->merged, &from->merged);
 388        blkg_rwstat_add_aux(&to->service_time, &from->service_time);
 389        blkg_rwstat_add_aux(&to->wait_time, &from->wait_time);
 390        bfq_stat_add_aux(&from->time, &from->time);
 391        bfq_stat_add_aux(&to->avg_queue_size_sum, &from->avg_queue_size_sum);
 392        bfq_stat_add_aux(&to->avg_queue_size_samples,
 393                          &from->avg_queue_size_samples);
 394        bfq_stat_add_aux(&to->dequeue, &from->dequeue);
 395        bfq_stat_add_aux(&to->group_wait_time, &from->group_wait_time);
 396        bfq_stat_add_aux(&to->idle_time, &from->idle_time);
 397        bfq_stat_add_aux(&to->empty_time, &from->empty_time);
 398#endif
 399}
 400
 401/*
 402 * Transfer @bfqg's stats to its parent's aux counts so that the ancestors'
 403 * recursive stats can still account for the amount used by this bfqg after
 404 * it's gone.
 405 */
 406static void bfqg_stats_xfer_dead(struct bfq_group *bfqg)
 407{
 408        struct bfq_group *parent;
 409
 410        if (!bfqg) /* root_group */
 411                return;
 412
 413        parent = bfqg_parent(bfqg);
 414
 415        lockdep_assert_held(&bfqg_to_blkg(bfqg)->q->queue_lock);
 416
 417        if (unlikely(!parent))
 418                return;
 419
 420        bfqg_stats_add_aux(&parent->stats, &bfqg->stats);
 421        bfqg_stats_reset(&bfqg->stats);
 422}
 423
 424void bfq_init_entity(struct bfq_entity *entity, struct bfq_group *bfqg)
 425{
 426        struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
 427
 428        entity->weight = entity->new_weight;
 429        entity->orig_weight = entity->new_weight;
 430        if (bfqq) {
 431                bfqq->ioprio = bfqq->new_ioprio;
 432                bfqq->ioprio_class = bfqq->new_ioprio_class;
 433                /*
 434                 * Make sure that bfqg and its associated blkg do not
 435                 * disappear before entity.
 436                 */
 437                bfqg_and_blkg_get(bfqg);
 438        }
 439        entity->parent = bfqg->my_entity; /* NULL for root group */
 440        entity->sched_data = &bfqg->sched_data;
 441}
 442
 443static void bfqg_stats_exit(struct bfqg_stats *stats)
 444{
 445        blkg_rwstat_exit(&stats->bytes);
 446        blkg_rwstat_exit(&stats->ios);
 447#ifdef CONFIG_BFQ_CGROUP_DEBUG
 448        blkg_rwstat_exit(&stats->merged);
 449        blkg_rwstat_exit(&stats->service_time);
 450        blkg_rwstat_exit(&stats->wait_time);
 451        blkg_rwstat_exit(&stats->queued);
 452        bfq_stat_exit(&stats->time);
 453        bfq_stat_exit(&stats->avg_queue_size_sum);
 454        bfq_stat_exit(&stats->avg_queue_size_samples);
 455        bfq_stat_exit(&stats->dequeue);
 456        bfq_stat_exit(&stats->group_wait_time);
 457        bfq_stat_exit(&stats->idle_time);
 458        bfq_stat_exit(&stats->empty_time);
 459#endif
 460}
 461
 462static int bfqg_stats_init(struct bfqg_stats *stats, gfp_t gfp)
 463{
 464        if (blkg_rwstat_init(&stats->bytes, gfp) ||
 465            blkg_rwstat_init(&stats->ios, gfp))
 466                return -ENOMEM;
 467
 468#ifdef CONFIG_BFQ_CGROUP_DEBUG
 469        if (blkg_rwstat_init(&stats->merged, gfp) ||
 470            blkg_rwstat_init(&stats->service_time, gfp) ||
 471            blkg_rwstat_init(&stats->wait_time, gfp) ||
 472            blkg_rwstat_init(&stats->queued, gfp) ||
 473            bfq_stat_init(&stats->time, gfp) ||
 474            bfq_stat_init(&stats->avg_queue_size_sum, gfp) ||
 475            bfq_stat_init(&stats->avg_queue_size_samples, gfp) ||
 476            bfq_stat_init(&stats->dequeue, gfp) ||
 477            bfq_stat_init(&stats->group_wait_time, gfp) ||
 478            bfq_stat_init(&stats->idle_time, gfp) ||
 479            bfq_stat_init(&stats->empty_time, gfp)) {
 480                bfqg_stats_exit(stats);
 481                return -ENOMEM;
 482        }
 483#endif
 484
 485        return 0;
 486}
 487
 488static struct bfq_group_data *cpd_to_bfqgd(struct blkcg_policy_data *cpd)
 489{
 490        return cpd ? container_of(cpd, struct bfq_group_data, pd) : NULL;
 491}
 492
 493static struct bfq_group_data *blkcg_to_bfqgd(struct blkcg *blkcg)
 494{
 495        return cpd_to_bfqgd(blkcg_to_cpd(blkcg, &blkcg_policy_bfq));
 496}
 497
 498static struct blkcg_policy_data *bfq_cpd_alloc(gfp_t gfp)
 499{
 500        struct bfq_group_data *bgd;
 501
 502        bgd = kzalloc(sizeof(*bgd), gfp);
 503        if (!bgd)
 504                return NULL;
 505        return &bgd->pd;
 506}
 507
 508static void bfq_cpd_init(struct blkcg_policy_data *cpd)
 509{
 510        struct bfq_group_data *d = cpd_to_bfqgd(cpd);
 511
 512        d->weight = cgroup_subsys_on_dfl(io_cgrp_subsys) ?
 513                CGROUP_WEIGHT_DFL : BFQ_WEIGHT_LEGACY_DFL;
 514}
 515
 516static void bfq_cpd_free(struct blkcg_policy_data *cpd)
 517{
 518        kfree(cpd_to_bfqgd(cpd));
 519}
 520
 521static struct blkg_policy_data *bfq_pd_alloc(gfp_t gfp, struct request_queue *q,
 522                                             struct blkcg *blkcg)
 523{
 524        struct bfq_group *bfqg;
 525
 526        bfqg = kzalloc_node(sizeof(*bfqg), gfp, q->node);
 527        if (!bfqg)
 528                return NULL;
 529
 530        if (bfqg_stats_init(&bfqg->stats, gfp)) {
 531                kfree(bfqg);
 532                return NULL;
 533        }
 534
 535        /* see comments in bfq_bic_update_cgroup for why refcounting */
 536        bfqg_get(bfqg);
 537        return &bfqg->pd;
 538}
 539
 540static void bfq_pd_init(struct blkg_policy_data *pd)
 541{
 542        struct blkcg_gq *blkg = pd_to_blkg(pd);
 543        struct bfq_group *bfqg = blkg_to_bfqg(blkg);
 544        struct bfq_data *bfqd = blkg->q->elevator->elevator_data;
 545        struct bfq_entity *entity = &bfqg->entity;
 546        struct bfq_group_data *d = blkcg_to_bfqgd(blkg->blkcg);
 547
 548        entity->orig_weight = entity->weight = entity->new_weight = d->weight;
 549        entity->my_sched_data = &bfqg->sched_data;
 550        bfqg->my_entity = entity; /*
 551                                   * the root_group's will be set to NULL
 552                                   * in bfq_init_queue()
 553                                   */
 554        bfqg->bfqd = bfqd;
 555        bfqg->active_entities = 0;
 556        bfqg->rq_pos_tree = RB_ROOT;
 557}
 558
 559static void bfq_pd_free(struct blkg_policy_data *pd)
 560{
 561        struct bfq_group *bfqg = pd_to_bfqg(pd);
 562
 563        bfqg_stats_exit(&bfqg->stats);
 564        bfqg_put(bfqg);
 565}
 566
 567static void bfq_pd_reset_stats(struct blkg_policy_data *pd)
 568{
 569        struct bfq_group *bfqg = pd_to_bfqg(pd);
 570
 571        bfqg_stats_reset(&bfqg->stats);
 572}
 573
 574static void bfq_group_set_parent(struct bfq_group *bfqg,
 575                                        struct bfq_group *parent)
 576{
 577        struct bfq_entity *entity;
 578
 579        entity = &bfqg->entity;
 580        entity->parent = parent->my_entity;
 581        entity->sched_data = &parent->sched_data;
 582}
 583
 584static struct bfq_group *bfq_lookup_bfqg(struct bfq_data *bfqd,
 585                                         struct blkcg *blkcg)
 586{
 587        struct blkcg_gq *blkg;
 588
 589        blkg = blkg_lookup(blkcg, bfqd->queue);
 590        if (likely(blkg))
 591                return blkg_to_bfqg(blkg);
 592        return NULL;
 593}
 594
 595struct bfq_group *bfq_find_set_group(struct bfq_data *bfqd,
 596                                     struct blkcg *blkcg)
 597{
 598        struct bfq_group *bfqg, *parent;
 599        struct bfq_entity *entity;
 600
 601        bfqg = bfq_lookup_bfqg(bfqd, blkcg);
 602
 603        if (unlikely(!bfqg))
 604                return NULL;
 605
 606        /*
 607         * Update chain of bfq_groups as we might be handling a leaf group
 608         * which, along with some of its relatives, has not been hooked yet
 609         * to the private hierarchy of BFQ.
 610         */
 611        entity = &bfqg->entity;
 612        for_each_entity(entity) {
 613                struct bfq_group *curr_bfqg = container_of(entity,
 614                                                struct bfq_group, entity);
 615                if (curr_bfqg != bfqd->root_group) {
 616                        parent = bfqg_parent(curr_bfqg);
 617                        if (!parent)
 618                                parent = bfqd->root_group;
 619                        bfq_group_set_parent(curr_bfqg, parent);
 620                }
 621        }
 622
 623        return bfqg;
 624}
 625
 626/**
 627 * bfq_bfqq_move - migrate @bfqq to @bfqg.
 628 * @bfqd: queue descriptor.
 629 * @bfqq: the queue to move.
 630 * @bfqg: the group to move to.
 631 *
 632 * Move @bfqq to @bfqg, deactivating it from its old group and reactivating
 633 * it on the new one.  Avoid putting the entity on the old group idle tree.
 634 *
 635 * Must be called under the scheduler lock, to make sure that the blkg
 636 * owning @bfqg does not disappear (see comments in
 637 * bfq_bic_update_cgroup on guaranteeing the consistency of blkg
 638 * objects).
 639 */
 640void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
 641                   struct bfq_group *bfqg)
 642{
 643        struct bfq_entity *entity = &bfqq->entity;
 644
 645        /* If bfqq is empty, then bfq_bfqq_expire also invokes
 646         * bfq_del_bfqq_busy, thereby removing bfqq and its entity
 647         * from data structures related to current group. Otherwise we
 648         * need to remove bfqq explicitly with bfq_deactivate_bfqq, as
 649         * we do below.
 650         */
 651        if (bfqq == bfqd->in_service_queue)
 652                bfq_bfqq_expire(bfqd, bfqd->in_service_queue,
 653                                false, BFQQE_PREEMPTED);
 654
 655        /*
 656         * get extra reference to prevent bfqq from being freed in
 657         * next possible deactivate
 658         */
 659        bfqq->ref++;
 660
 661        if (bfq_bfqq_busy(bfqq))
 662                bfq_deactivate_bfqq(bfqd, bfqq, false, false);
 663        else if (entity->on_st_or_in_serv)
 664                bfq_put_idle_entity(bfq_entity_service_tree(entity), entity);
 665        bfqg_and_blkg_put(bfqq_group(bfqq));
 666
 667        entity->parent = bfqg->my_entity;
 668        entity->sched_data = &bfqg->sched_data;
 669        /* pin down bfqg and its associated blkg  */
 670        bfqg_and_blkg_get(bfqg);
 671
 672        if (bfq_bfqq_busy(bfqq)) {
 673                if (unlikely(!bfqd->nonrot_with_queueing))
 674                        bfq_pos_tree_add_move(bfqd, bfqq);
 675                bfq_activate_bfqq(bfqd, bfqq);
 676        }
 677
 678        if (!bfqd->in_service_queue && !bfqd->rq_in_driver)
 679                bfq_schedule_dispatch(bfqd);
 680        /* release extra ref taken above */
 681        bfq_put_queue(bfqq);
 682}
 683
 684/**
 685 * __bfq_bic_change_cgroup - move @bic to @cgroup.
 686 * @bfqd: the queue descriptor.
 687 * @bic: the bic to move.
 688 * @blkcg: the blk-cgroup to move to.
 689 *
 690 * Move bic to blkcg, assuming that bfqd->lock is held; which makes
 691 * sure that the reference to cgroup is valid across the call (see
 692 * comments in bfq_bic_update_cgroup on this issue)
 693 *
 694 * NOTE: an alternative approach might have been to store the current
 695 * cgroup in bfqq and getting a reference to it, reducing the lookup
 696 * time here, at the price of slightly more complex code.
 697 */
 698static struct bfq_group *__bfq_bic_change_cgroup(struct bfq_data *bfqd,
 699                                                struct bfq_io_cq *bic,
 700                                                struct blkcg *blkcg)
 701{
 702        struct bfq_queue *async_bfqq = bic_to_bfqq(bic, 0);
 703        struct bfq_queue *sync_bfqq = bic_to_bfqq(bic, 1);
 704        struct bfq_group *bfqg;
 705        struct bfq_entity *entity;
 706
 707        bfqg = bfq_find_set_group(bfqd, blkcg);
 708
 709        if (unlikely(!bfqg))
 710                bfqg = bfqd->root_group;
 711
 712        if (async_bfqq) {
 713                entity = &async_bfqq->entity;
 714
 715                if (entity->sched_data != &bfqg->sched_data) {
 716                        bic_set_bfqq(bic, NULL, 0);
 717                        bfq_log_bfqq(bfqd, async_bfqq,
 718                                     "bic_change_group: %p %d",
 719                                     async_bfqq, async_bfqq->ref);
 720                        bfq_put_queue(async_bfqq);
 721                }
 722        }
 723
 724        if (sync_bfqq) {
 725                entity = &sync_bfqq->entity;
 726                if (entity->sched_data != &bfqg->sched_data)
 727                        bfq_bfqq_move(bfqd, sync_bfqq, bfqg);
 728        }
 729
 730        return bfqg;
 731}
 732
 733void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio)
 734{
 735        struct bfq_data *bfqd = bic_to_bfqd(bic);
 736        struct bfq_group *bfqg = NULL;
 737        uint64_t serial_nr;
 738
 739        rcu_read_lock();
 740        serial_nr = __bio_blkcg(bio)->css.serial_nr;
 741
 742        /*
 743         * Check whether blkcg has changed.  The condition may trigger
 744         * spuriously on a newly created cic but there's no harm.
 745         */
 746        if (unlikely(!bfqd) || likely(bic->blkcg_serial_nr == serial_nr))
 747                goto out;
 748
 749        bfqg = __bfq_bic_change_cgroup(bfqd, bic, __bio_blkcg(bio));
 750        /*
 751         * Update blkg_path for bfq_log_* functions. We cache this
 752         * path, and update it here, for the following
 753         * reasons. Operations on blkg objects in blk-cgroup are
 754         * protected with the request_queue lock, and not with the
 755         * lock that protects the instances of this scheduler
 756         * (bfqd->lock). This exposes BFQ to the following sort of
 757         * race.
 758         *
 759         * The blkg_lookup performed in bfq_get_queue, protected
 760         * through rcu, may happen to return the address of a copy of
 761         * the original blkg. If this is the case, then the
 762         * bfqg_and_blkg_get performed in bfq_get_queue, to pin down
 763         * the blkg, is useless: it does not prevent blk-cgroup code
 764         * from destroying both the original blkg and all objects
 765         * directly or indirectly referred by the copy of the
 766         * blkg.
 767         *
 768         * On the bright side, destroy operations on a blkg invoke, as
 769         * a first step, hooks of the scheduler associated with the
 770         * blkg. And these hooks are executed with bfqd->lock held for
 771         * BFQ. As a consequence, for any blkg associated with the
 772         * request queue this instance of the scheduler is attached
 773         * to, we are guaranteed that such a blkg is not destroyed, and
 774         * that all the pointers it contains are consistent, while we
 775         * are holding bfqd->lock. A blkg_lookup performed with
 776         * bfqd->lock held then returns a fully consistent blkg, which
 777         * remains consistent until this lock is held.
 778         *
 779         * Thanks to the last fact, and to the fact that: (1) bfqg has
 780         * been obtained through a blkg_lookup in the above
 781         * assignment, and (2) bfqd->lock is being held, here we can
 782         * safely use the policy data for the involved blkg (i.e., the
 783         * field bfqg->pd) to get to the blkg associated with bfqg,
 784         * and then we can safely use any field of blkg. After we
 785         * release bfqd->lock, even just getting blkg through this
 786         * bfqg may cause dangling references to be traversed, as
 787         * bfqg->pd may not exist any more.
 788         *
 789         * In view of the above facts, here we cache, in the bfqg, any
 790         * blkg data we may need for this bic, and for its associated
 791         * bfq_queue. As of now, we need to cache only the path of the
 792         * blkg, which is used in the bfq_log_* functions.
 793         *
 794         * Finally, note that bfqg itself needs to be protected from
 795         * destruction on the blkg_free of the original blkg (which
 796         * invokes bfq_pd_free). We use an additional private
 797         * refcounter for bfqg, to let it disappear only after no
 798         * bfq_queue refers to it any longer.
 799         */
 800        blkg_path(bfqg_to_blkg(bfqg), bfqg->blkg_path, sizeof(bfqg->blkg_path));
 801        bic->blkcg_serial_nr = serial_nr;
 802out:
 803        rcu_read_unlock();
 804}
 805
 806/**
 807 * bfq_flush_idle_tree - deactivate any entity on the idle tree of @st.
 808 * @st: the service tree being flushed.
 809 */
 810static void bfq_flush_idle_tree(struct bfq_service_tree *st)
 811{
 812        struct bfq_entity *entity = st->first_idle;
 813
 814        for (; entity ; entity = st->first_idle)
 815                __bfq_deactivate_entity(entity, false);
 816}
 817
 818/**
 819 * bfq_reparent_leaf_entity - move leaf entity to the root_group.
 820 * @bfqd: the device data structure with the root group.
 821 * @entity: the entity to move.
 822 */
 823static void bfq_reparent_leaf_entity(struct bfq_data *bfqd,
 824                                     struct bfq_entity *entity)
 825{
 826        struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
 827
 828        bfq_bfqq_move(bfqd, bfqq, bfqd->root_group);
 829}
 830
 831/**
 832 * bfq_reparent_active_entities - move to the root group all active
 833 *                                entities.
 834 * @bfqd: the device data structure with the root group.
 835 * @bfqg: the group to move from.
 836 * @st: the service tree with the entities.
 837 */
 838static void bfq_reparent_active_entities(struct bfq_data *bfqd,
 839                                         struct bfq_group *bfqg,
 840                                         struct bfq_service_tree *st)
 841{
 842        struct rb_root *active = &st->active;
 843        struct bfq_entity *entity = NULL;
 844
 845        if (!RB_EMPTY_ROOT(&st->active))
 846                entity = bfq_entity_of(rb_first(active));
 847
 848        for (; entity ; entity = bfq_entity_of(rb_first(active)))
 849                bfq_reparent_leaf_entity(bfqd, entity);
 850
 851        if (bfqg->sched_data.in_service_entity)
 852                bfq_reparent_leaf_entity(bfqd,
 853                        bfqg->sched_data.in_service_entity);
 854}
 855
 856/**
 857 * bfq_pd_offline - deactivate the entity associated with @pd,
 858 *                  and reparent its children entities.
 859 * @pd: descriptor of the policy going offline.
 860 *
 861 * blkio already grabs the queue_lock for us, so no need to use
 862 * RCU-based magic
 863 */
 864static void bfq_pd_offline(struct blkg_policy_data *pd)
 865{
 866        struct bfq_service_tree *st;
 867        struct bfq_group *bfqg = pd_to_bfqg(pd);
 868        struct bfq_data *bfqd = bfqg->bfqd;
 869        struct bfq_entity *entity = bfqg->my_entity;
 870        unsigned long flags;
 871        int i;
 872
 873        spin_lock_irqsave(&bfqd->lock, flags);
 874
 875        if (!entity) /* root group */
 876                goto put_async_queues;
 877
 878        /*
 879         * Empty all service_trees belonging to this group before
 880         * deactivating the group itself.
 881         */
 882        for (i = 0; i < BFQ_IOPRIO_CLASSES; i++) {
 883                st = bfqg->sched_data.service_tree + i;
 884
 885                /*
 886                 * The idle tree may still contain bfq_queues belonging
 887                 * to exited task because they never migrated to a different
 888                 * cgroup from the one being destroyed now.
 889                 */
 890                bfq_flush_idle_tree(st);
 891
 892                /*
 893                 * It may happen that some queues are still active
 894                 * (busy) upon group destruction (if the corresponding
 895                 * processes have been forced to terminate). We move
 896                 * all the leaf entities corresponding to these queues
 897                 * to the root_group.
 898                 * Also, it may happen that the group has an entity
 899                 * in service, which is disconnected from the active
 900                 * tree: it must be moved, too.
 901                 * There is no need to put the sync queues, as the
 902                 * scheduler has taken no reference.
 903                 */
 904                bfq_reparent_active_entities(bfqd, bfqg, st);
 905        }
 906
 907        __bfq_deactivate_entity(entity, false);
 908
 909put_async_queues:
 910        bfq_put_async_queues(bfqd, bfqg);
 911
 912        spin_unlock_irqrestore(&bfqd->lock, flags);
 913        /*
 914         * @blkg is going offline and will be ignored by
 915         * blkg_[rw]stat_recursive_sum().  Transfer stats to the parent so
 916         * that they don't get lost.  If IOs complete after this point, the
 917         * stats for them will be lost.  Oh well...
 918         */
 919        bfqg_stats_xfer_dead(bfqg);
 920}
 921
 922void bfq_end_wr_async(struct bfq_data *bfqd)
 923{
 924        struct blkcg_gq *blkg;
 925
 926        list_for_each_entry(blkg, &bfqd->queue->blkg_list, q_node) {
 927                struct bfq_group *bfqg = blkg_to_bfqg(blkg);
 928
 929                bfq_end_wr_async_queues(bfqd, bfqg);
 930        }
 931        bfq_end_wr_async_queues(bfqd, bfqd->root_group);
 932}
 933
 934static int bfq_io_show_weight_legacy(struct seq_file *sf, void *v)
 935{
 936        struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
 937        struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg);
 938        unsigned int val = 0;
 939
 940        if (bfqgd)
 941                val = bfqgd->weight;
 942
 943        seq_printf(sf, "%u\n", val);
 944
 945        return 0;
 946}
 947
 948static u64 bfqg_prfill_weight_device(struct seq_file *sf,
 949                                     struct blkg_policy_data *pd, int off)
 950{
 951        struct bfq_group *bfqg = pd_to_bfqg(pd);
 952
 953        if (!bfqg->entity.dev_weight)
 954                return 0;
 955        return __blkg_prfill_u64(sf, pd, bfqg->entity.dev_weight);
 956}
 957
 958static int bfq_io_show_weight(struct seq_file *sf, void *v)
 959{
 960        struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
 961        struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg);
 962
 963        seq_printf(sf, "default %u\n", bfqgd->weight);
 964        blkcg_print_blkgs(sf, blkcg, bfqg_prfill_weight_device,
 965                          &blkcg_policy_bfq, 0, false);
 966        return 0;
 967}
 968
 969static void bfq_group_set_weight(struct bfq_group *bfqg, u64 weight, u64 dev_weight)
 970{
 971        weight = dev_weight ?: weight;
 972
 973        bfqg->entity.dev_weight = dev_weight;
 974        /*
 975         * Setting the prio_changed flag of the entity
 976         * to 1 with new_weight == weight would re-set
 977         * the value of the weight to its ioprio mapping.
 978         * Set the flag only if necessary.
 979         */
 980        if ((unsigned short)weight != bfqg->entity.new_weight) {
 981                bfqg->entity.new_weight = (unsigned short)weight;
 982                /*
 983                 * Make sure that the above new value has been
 984                 * stored in bfqg->entity.new_weight before
 985                 * setting the prio_changed flag. In fact,
 986                 * this flag may be read asynchronously (in
 987                 * critical sections protected by a different
 988                 * lock than that held here), and finding this
 989                 * flag set may cause the execution of the code
 990                 * for updating parameters whose value may
 991                 * depend also on bfqg->entity.new_weight (in
 992                 * __bfq_entity_update_weight_prio).
 993                 * This barrier makes sure that the new value
 994                 * of bfqg->entity.new_weight is correctly
 995                 * seen in that code.
 996                 */
 997                smp_wmb();
 998                bfqg->entity.prio_changed = 1;
 999        }
1000}
1001
1002static int bfq_io_set_weight_legacy(struct cgroup_subsys_state *css,
1003                                    struct cftype *cftype,
1004                                    u64 val)
1005{
1006        struct blkcg *blkcg = css_to_blkcg(css);
1007        struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg);
1008        struct blkcg_gq *blkg;
1009        int ret = -ERANGE;
1010
1011        if (val < BFQ_MIN_WEIGHT || val > BFQ_MAX_WEIGHT)
1012                return ret;
1013
1014        ret = 0;
1015        spin_lock_irq(&blkcg->lock);
1016        bfqgd->weight = (unsigned short)val;
1017        hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) {
1018                struct bfq_group *bfqg = blkg_to_bfqg(blkg);
1019
1020                if (bfqg)
1021                        bfq_group_set_weight(bfqg, val, 0);
1022        }
1023        spin_unlock_irq(&blkcg->lock);
1024
1025        return ret;
1026}
1027
1028static ssize_t bfq_io_set_device_weight(struct kernfs_open_file *of,
1029                                        char *buf, size_t nbytes,
1030                                        loff_t off)
1031{
1032        int ret;
1033        struct blkg_conf_ctx ctx;
1034        struct blkcg *blkcg = css_to_blkcg(of_css(of));
1035        struct bfq_group *bfqg;
1036        u64 v;
1037
1038        ret = blkg_conf_prep(blkcg, &blkcg_policy_bfq, buf, &ctx);
1039        if (ret)
1040                return ret;
1041
1042        if (sscanf(ctx.body, "%llu", &v) == 1) {
1043                /* require "default" on dfl */
1044                ret = -ERANGE;
1045                if (!v)
1046                        goto out;
1047        } else if (!strcmp(strim(ctx.body), "default")) {
1048                v = 0;
1049        } else {
1050                ret = -EINVAL;
1051                goto out;
1052        }
1053
1054        bfqg = blkg_to_bfqg(ctx.blkg);
1055
1056        ret = -ERANGE;
1057        if (!v || (v >= BFQ_MIN_WEIGHT && v <= BFQ_MAX_WEIGHT)) {
1058                bfq_group_set_weight(bfqg, bfqg->entity.weight, v);
1059                ret = 0;
1060        }
1061out:
1062        blkg_conf_finish(&ctx);
1063        return ret ?: nbytes;
1064}
1065
1066static ssize_t bfq_io_set_weight(struct kernfs_open_file *of,
1067                                 char *buf, size_t nbytes,
1068                                 loff_t off)
1069{
1070        char *endp;
1071        int ret;
1072        u64 v;
1073
1074        buf = strim(buf);
1075
1076        /* "WEIGHT" or "default WEIGHT" sets the default weight */
1077        v = simple_strtoull(buf, &endp, 0);
1078        if (*endp == '\0' || sscanf(buf, "default %llu", &v) == 1) {
1079                ret = bfq_io_set_weight_legacy(of_css(of), NULL, v);
1080                return ret ?: nbytes;
1081        }
1082
1083        return bfq_io_set_device_weight(of, buf, nbytes, off);
1084}
1085
1086static int bfqg_print_rwstat(struct seq_file *sf, void *v)
1087{
1088        blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_rwstat,
1089                          &blkcg_policy_bfq, seq_cft(sf)->private, true);
1090        return 0;
1091}
1092
1093static u64 bfqg_prfill_rwstat_recursive(struct seq_file *sf,
1094                                        struct blkg_policy_data *pd, int off)
1095{
1096        struct blkg_rwstat_sample sum;
1097
1098        blkg_rwstat_recursive_sum(pd_to_blkg(pd), &blkcg_policy_bfq, off, &sum);
1099        return __blkg_prfill_rwstat(sf, pd, &sum);
1100}
1101
1102static int bfqg_print_rwstat_recursive(struct seq_file *sf, void *v)
1103{
1104        blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1105                          bfqg_prfill_rwstat_recursive, &blkcg_policy_bfq,
1106                          seq_cft(sf)->private, true);
1107        return 0;
1108}
1109
1110#ifdef CONFIG_BFQ_CGROUP_DEBUG
1111static int bfqg_print_stat(struct seq_file *sf, void *v)
1112{
1113        blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_stat,
1114                          &blkcg_policy_bfq, seq_cft(sf)->private, false);
1115        return 0;
1116}
1117
1118static u64 bfqg_prfill_stat_recursive(struct seq_file *sf,
1119                                      struct blkg_policy_data *pd, int off)
1120{
1121        struct blkcg_gq *blkg = pd_to_blkg(pd);
1122        struct blkcg_gq *pos_blkg;
1123        struct cgroup_subsys_state *pos_css;
1124        u64 sum = 0;
1125
1126        lockdep_assert_held(&blkg->q->queue_lock);
1127
1128        rcu_read_lock();
1129        blkg_for_each_descendant_pre(pos_blkg, pos_css, blkg) {
1130                struct bfq_stat *stat;
1131
1132                if (!pos_blkg->online)
1133                        continue;
1134
1135                stat = (void *)blkg_to_pd(pos_blkg, &blkcg_policy_bfq) + off;
1136                sum += bfq_stat_read(stat) + atomic64_read(&stat->aux_cnt);
1137        }
1138        rcu_read_unlock();
1139
1140        return __blkg_prfill_u64(sf, pd, sum);
1141}
1142
1143static int bfqg_print_stat_recursive(struct seq_file *sf, void *v)
1144{
1145        blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1146                          bfqg_prfill_stat_recursive, &blkcg_policy_bfq,
1147                          seq_cft(sf)->private, false);
1148        return 0;
1149}
1150
1151static u64 bfqg_prfill_sectors(struct seq_file *sf, struct blkg_policy_data *pd,
1152                               int off)
1153{
1154        struct bfq_group *bfqg = blkg_to_bfqg(pd->blkg);
1155        u64 sum = blkg_rwstat_total(&bfqg->stats.bytes);
1156
1157        return __blkg_prfill_u64(sf, pd, sum >> 9);
1158}
1159
1160static int bfqg_print_stat_sectors(struct seq_file *sf, void *v)
1161{
1162        blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1163                          bfqg_prfill_sectors, &blkcg_policy_bfq, 0, false);
1164        return 0;
1165}
1166
1167static u64 bfqg_prfill_sectors_recursive(struct seq_file *sf,
1168                                         struct blkg_policy_data *pd, int off)
1169{
1170        struct blkg_rwstat_sample tmp;
1171
1172        blkg_rwstat_recursive_sum(pd->blkg, &blkcg_policy_bfq,
1173                        offsetof(struct bfq_group, stats.bytes), &tmp);
1174
1175        return __blkg_prfill_u64(sf, pd,
1176                (tmp.cnt[BLKG_RWSTAT_READ] + tmp.cnt[BLKG_RWSTAT_WRITE]) >> 9);
1177}
1178
1179static int bfqg_print_stat_sectors_recursive(struct seq_file *sf, void *v)
1180{
1181        blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1182                          bfqg_prfill_sectors_recursive, &blkcg_policy_bfq, 0,
1183                          false);
1184        return 0;
1185}
1186
1187static u64 bfqg_prfill_avg_queue_size(struct seq_file *sf,
1188                                      struct blkg_policy_data *pd, int off)
1189{
1190        struct bfq_group *bfqg = pd_to_bfqg(pd);
1191        u64 samples = bfq_stat_read(&bfqg->stats.avg_queue_size_samples);
1192        u64 v = 0;
1193
1194        if (samples) {
1195                v = bfq_stat_read(&bfqg->stats.avg_queue_size_sum);
1196                v = div64_u64(v, samples);
1197        }
1198        __blkg_prfill_u64(sf, pd, v);
1199        return 0;
1200}
1201
1202/* print avg_queue_size */
1203static int bfqg_print_avg_queue_size(struct seq_file *sf, void *v)
1204{
1205        blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1206                          bfqg_prfill_avg_queue_size, &blkcg_policy_bfq,
1207                          0, false);
1208        return 0;
1209}
1210#endif /* CONFIG_BFQ_CGROUP_DEBUG */
1211
1212struct bfq_group *bfq_create_group_hierarchy(struct bfq_data *bfqd, int node)
1213{
1214        int ret;
1215
1216        ret = blkcg_activate_policy(bfqd->queue, &blkcg_policy_bfq);
1217        if (ret)
1218                return NULL;
1219
1220        return blkg_to_bfqg(bfqd->queue->root_blkg);
1221}
1222
1223struct blkcg_policy blkcg_policy_bfq = {
1224        .dfl_cftypes            = bfq_blkg_files,
1225        .legacy_cftypes         = bfq_blkcg_legacy_files,
1226
1227        .cpd_alloc_fn           = bfq_cpd_alloc,
1228        .cpd_init_fn            = bfq_cpd_init,
1229        .cpd_bind_fn            = bfq_cpd_init,
1230        .cpd_free_fn            = bfq_cpd_free,
1231
1232        .pd_alloc_fn            = bfq_pd_alloc,
1233        .pd_init_fn             = bfq_pd_init,
1234        .pd_offline_fn          = bfq_pd_offline,
1235        .pd_free_fn             = bfq_pd_free,
1236        .pd_reset_stats_fn      = bfq_pd_reset_stats,
1237};
1238
1239struct cftype bfq_blkcg_legacy_files[] = {
1240        {
1241                .name = "bfq.weight",
1242                .flags = CFTYPE_NOT_ON_ROOT,
1243                .seq_show = bfq_io_show_weight_legacy,
1244                .write_u64 = bfq_io_set_weight_legacy,
1245        },
1246        {
1247                .name = "bfq.weight_device",
1248                .flags = CFTYPE_NOT_ON_ROOT,
1249                .seq_show = bfq_io_show_weight,
1250                .write = bfq_io_set_weight,
1251        },
1252
1253        /* statistics, covers only the tasks in the bfqg */
1254        {
1255                .name = "bfq.io_service_bytes",
1256                .private = offsetof(struct bfq_group, stats.bytes),
1257                .seq_show = bfqg_print_rwstat,
1258        },
1259        {
1260                .name = "bfq.io_serviced",
1261                .private = offsetof(struct bfq_group, stats.ios),
1262                .seq_show = bfqg_print_rwstat,
1263        },
1264#ifdef CONFIG_BFQ_CGROUP_DEBUG
1265        {
1266                .name = "bfq.time",
1267                .private = offsetof(struct bfq_group, stats.time),
1268                .seq_show = bfqg_print_stat,
1269        },
1270        {
1271                .name = "bfq.sectors",
1272                .seq_show = bfqg_print_stat_sectors,
1273        },
1274        {
1275                .name = "bfq.io_service_time",
1276                .private = offsetof(struct bfq_group, stats.service_time),
1277                .seq_show = bfqg_print_rwstat,
1278        },
1279        {
1280                .name = "bfq.io_wait_time",
1281                .private = offsetof(struct bfq_group, stats.wait_time),
1282                .seq_show = bfqg_print_rwstat,
1283        },
1284        {
1285                .name = "bfq.io_merged",
1286                .private = offsetof(struct bfq_group, stats.merged),
1287                .seq_show = bfqg_print_rwstat,
1288        },
1289        {
1290                .name = "bfq.io_queued",
1291                .private = offsetof(struct bfq_group, stats.queued),
1292                .seq_show = bfqg_print_rwstat,
1293        },
1294#endif /* CONFIG_BFQ_CGROUP_DEBUG */
1295
1296        /* the same statistics which cover the bfqg and its descendants */
1297        {
1298                .name = "bfq.io_service_bytes_recursive",
1299                .private = offsetof(struct bfq_group, stats.bytes),
1300                .seq_show = bfqg_print_rwstat_recursive,
1301        },
1302        {
1303                .name = "bfq.io_serviced_recursive",
1304                .private = offsetof(struct bfq_group, stats.ios),
1305                .seq_show = bfqg_print_rwstat_recursive,
1306        },
1307#ifdef CONFIG_BFQ_CGROUP_DEBUG
1308        {
1309                .name = "bfq.time_recursive",
1310                .private = offsetof(struct bfq_group, stats.time),
1311                .seq_show = bfqg_print_stat_recursive,
1312        },
1313        {
1314                .name = "bfq.sectors_recursive",
1315                .seq_show = bfqg_print_stat_sectors_recursive,
1316        },
1317        {
1318                .name = "bfq.io_service_time_recursive",
1319                .private = offsetof(struct bfq_group, stats.service_time),
1320                .seq_show = bfqg_print_rwstat_recursive,
1321        },
1322        {
1323                .name = "bfq.io_wait_time_recursive",
1324                .private = offsetof(struct bfq_group, stats.wait_time),
1325                .seq_show = bfqg_print_rwstat_recursive,
1326        },
1327        {
1328                .name = "bfq.io_merged_recursive",
1329                .private = offsetof(struct bfq_group, stats.merged),
1330                .seq_show = bfqg_print_rwstat_recursive,
1331        },
1332        {
1333                .name = "bfq.io_queued_recursive",
1334                .private = offsetof(struct bfq_group, stats.queued),
1335                .seq_show = bfqg_print_rwstat_recursive,
1336        },
1337        {
1338                .name = "bfq.avg_queue_size",
1339                .seq_show = bfqg_print_avg_queue_size,
1340        },
1341        {
1342                .name = "bfq.group_wait_time",
1343                .private = offsetof(struct bfq_group, stats.group_wait_time),
1344                .seq_show = bfqg_print_stat,
1345        },
1346        {
1347                .name = "bfq.idle_time",
1348                .private = offsetof(struct bfq_group, stats.idle_time),
1349                .seq_show = bfqg_print_stat,
1350        },
1351        {
1352                .name = "bfq.empty_time",
1353                .private = offsetof(struct bfq_group, stats.empty_time),
1354                .seq_show = bfqg_print_stat,
1355        },
1356        {
1357                .name = "bfq.dequeue",
1358                .private = offsetof(struct bfq_group, stats.dequeue),
1359                .seq_show = bfqg_print_stat,
1360        },
1361#endif  /* CONFIG_BFQ_CGROUP_DEBUG */
1362        { }     /* terminate */
1363};
1364
1365struct cftype bfq_blkg_files[] = {
1366        {
1367                .name = "bfq.weight",
1368                .flags = CFTYPE_NOT_ON_ROOT,
1369                .seq_show = bfq_io_show_weight,
1370                .write = bfq_io_set_weight,
1371        },
1372        {} /* terminate */
1373};
1374
1375#else   /* CONFIG_BFQ_GROUP_IOSCHED */
1376
1377void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq,
1378                   struct bfq_group *bfqg) {}
1379
1380void bfq_init_entity(struct bfq_entity *entity, struct bfq_group *bfqg)
1381{
1382        struct bfq_queue *bfqq = bfq_entity_to_bfqq(entity);
1383
1384        entity->weight = entity->new_weight;
1385        entity->orig_weight = entity->new_weight;
1386        if (bfqq) {
1387                bfqq->ioprio = bfqq->new_ioprio;
1388                bfqq->ioprio_class = bfqq->new_ioprio_class;
1389        }
1390        entity->sched_data = &bfqg->sched_data;
1391}
1392
1393void bfq_bic_update_cgroup(struct bfq_io_cq *bic, struct bio *bio) {}
1394
1395void bfq_end_wr_async(struct bfq_data *bfqd)
1396{
1397        bfq_end_wr_async_queues(bfqd, bfqd->root_group);
1398}
1399
1400struct bfq_group *bfq_find_set_group(struct bfq_data *bfqd, struct blkcg *blkcg)
1401{
1402        return bfqd->root_group;
1403}
1404
1405struct bfq_group *bfqq_group(struct bfq_queue *bfqq)
1406{
1407        return bfqq->bfqd->root_group;
1408}
1409
1410void bfqg_and_blkg_get(struct bfq_group *bfqg) {}
1411
1412void bfqg_and_blkg_put(struct bfq_group *bfqg) {}
1413
1414struct bfq_group *bfq_create_group_hierarchy(struct bfq_data *bfqd, int node)
1415{
1416        struct bfq_group *bfqg;
1417        int i;
1418
1419        bfqg = kmalloc_node(sizeof(*bfqg), GFP_KERNEL | __GFP_ZERO, node);
1420        if (!bfqg)
1421                return NULL;
1422
1423        for (i = 0; i < BFQ_IOPRIO_CLASSES; i++)
1424                bfqg->sched_data.service_tree[i] = BFQ_SERVICE_TREE_INIT;
1425
1426        return bfqg;
1427}
1428#endif  /* CONFIG_BFQ_GROUP_IOSCHED */
1429