block/bfq-cgroup.c

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