block/blk-cgroup.c

   1 /*
   2  * Common Block IO controller cgroup interface
   3  *
   4  * Based on ideas and code from CFQ, CFS and BFQ:
   5  * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
   6  *
   7  * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it>
   8  *                    Paolo Valente <paolo.valente@unimore.it>
   9  *
  10  * Copyright (C) 2009 Vivek Goyal <vgoyal@redhat.com>
  11  *                    Nauman Rafique <nauman@google.com>
  12  */
  13 #include <linux/ioprio.h>
  14 #include <linux/seq_file.h>
  15 #include <linux/kdev_t.h>
  16 #include <linux/module.h>
  17 #include <linux/err.h>
  18 #include <linux/blkdev.h>
  19 #include <linux/slab.h>
  20 #include "blk-cgroup.h"
  21 #include <linux/genhd.h>
  22
  23 #define MAX_KEY_LEN 100
  24
  25 static DEFINE_SPINLOCK(blkio_list_lock);
  26 static LIST_HEAD(blkio_list);
  27
  28 struct blkio_cgroup blkio_root_cgroup = { .weight = 2*BLKIO_WEIGHT_DEFAULT };
  29 EXPORT_SYMBOL_GPL(blkio_root_cgroup);
  30
  31 static struct cgroup_subsys_state *blkiocg_create(struct cgroup_subsys *,
  32                                                   struct cgroup *);
  33 static int blkiocg_can_attach_task(struct cgroup *, struct task_struct *);
  34 static void blkiocg_attach_task(struct cgroup *, struct task_struct *);
  35 static void blkiocg_destroy(struct cgroup_subsys *, struct cgroup *);
  36 static int blkiocg_populate(struct cgroup_subsys *, struct cgroup *);
  37
  38 /* for encoding cft->private value on file */
  39 #define BLKIOFILE_PRIVATE(x, val)       (((x) << 16) | (val))
  40 /* What policy owns the file, proportional or throttle */
  41 #define BLKIOFILE_POLICY(val)           (((val) >> 16) & 0xffff)
  42 #define BLKIOFILE_ATTR(val)             ((val) & 0xffff)
  43
  44 struct cgroup_subsys blkio_subsys = {
  45         .name = "blkio",
  46         .create = blkiocg_create,
  47         .can_attach_task = blkiocg_can_attach_task,
  48         .attach_task = blkiocg_attach_task,
  49         .destroy = blkiocg_destroy,
  50         .populate = blkiocg_populate,
  51 #ifdef CONFIG_BLK_CGROUP
  52         /* note: blkio_subsys_id is otherwise defined in blk-cgroup.h */
  53         .subsys_id = blkio_subsys_id,
  54 #endif
  55         .use_id = 1,
  56         .module = THIS_MODULE,
  57 };
  58 EXPORT_SYMBOL_GPL(blkio_subsys);
  59
  60 static inline void blkio_policy_insert_node(struct blkio_cgroup *blkcg,
  61                                             struct blkio_policy_node *pn)
  62 {
  63         list_add(&pn->node, &blkcg->policy_list);
  64 }
  65
  66 static inline bool cftype_blkg_same_policy(struct cftype *cft,
  67                         struct blkio_group *blkg)
  68 {
  69         enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private);
  70
  71         if (blkg->plid == plid)
  72                 return 1;
  73
  74         return 0;
  75 }
  76
  77 /* Determines if policy node matches cgroup file being accessed */
  78 static inline bool pn_matches_cftype(struct cftype *cft,
  79                         struct blkio_policy_node *pn)
  80 {
  81         enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private);
  82         int fileid = BLKIOFILE_ATTR(cft->private);
  83
  84         return (plid == pn->plid && fileid == pn->fileid);
  85 }
  86
  87 /* Must be called with blkcg->lock held */
  88 static inline void blkio_policy_delete_node(struct blkio_policy_node *pn)
  89 {
  90         list_del(&pn->node);
  91 }
  92
  93 /* Must be called with blkcg->lock held */
  94 static struct blkio_policy_node *
  95 blkio_policy_search_node(const struct blkio_cgroup *blkcg, dev_t dev,
  96                 enum blkio_policy_id plid, int fileid)
  97 {
  98         struct blkio_policy_node *pn;
  99
 100         list_for_each_entry(pn, &blkcg->policy_list, node) {
 101                 if (pn->dev == dev && pn->plid == plid && pn->fileid == fileid)
 102                         return pn;
 103         }
 104
 105         return NULL;
 106 }
 107
 108 struct blkio_cgroup *cgroup_to_blkio_cgroup(struct cgroup *cgroup)
 109 {
 110         return container_of(cgroup_subsys_state(cgroup, blkio_subsys_id),
 111                             struct blkio_cgroup, css);
 112 }
 113 EXPORT_SYMBOL_GPL(cgroup_to_blkio_cgroup);
 114
 115 struct blkio_cgroup *task_blkio_cgroup(struct task_struct *tsk)
 116 {
 117         return container_of(task_subsys_state(tsk, blkio_subsys_id),
 118                             struct blkio_cgroup, css);
 119 }
 120 EXPORT_SYMBOL_GPL(task_blkio_cgroup);
 121
 122 static inline void
 123 blkio_update_group_weight(struct blkio_group *blkg, unsigned int weight)
 124 {
 125         struct blkio_policy_type *blkiop;
 126
 127         list_for_each_entry(blkiop, &blkio_list, list) {
 128                 /* If this policy does not own the blkg, do not send updates */
 129                 if (blkiop->plid != blkg->plid)
 130                         continue;
 131                 if (blkiop->ops.blkio_update_group_weight_fn)
 132                         blkiop->ops.blkio_update_group_weight_fn(blkg->key,
 133                                                         blkg, weight);
 134         }
 135 }
 136
 137 static inline void blkio_update_group_bps(struct blkio_group *blkg, u64 bps,
 138                                 int fileid)
 139 {
 140         struct blkio_policy_type *blkiop;
 141
 142         list_for_each_entry(blkiop, &blkio_list, list) {
 143
 144                 /* If this policy does not own the blkg, do not send updates */
 145                 if (blkiop->plid != blkg->plid)
 146                         continue;
 147
 148                 if (fileid == BLKIO_THROTL_read_bps_device
 149                     && blkiop->ops.blkio_update_group_read_bps_fn)
 150                         blkiop->ops.blkio_update_group_read_bps_fn(blkg->key,
 151                                                                 blkg, bps);
 152
 153                 if (fileid == BLKIO_THROTL_write_bps_device
 154                     && blkiop->ops.blkio_update_group_write_bps_fn)
 155                         blkiop->ops.blkio_update_group_write_bps_fn(blkg->key,
 156                                                                 blkg, bps);
 157         }
 158 }
 159
 160 static inline void blkio_update_group_iops(struct blkio_group *blkg,
 161                         unsigned int iops, int fileid)
 162 {
 163         struct blkio_policy_type *blkiop;
 164
 165         list_for_each_entry(blkiop, &blkio_list, list) {
 166
 167                 /* If this policy does not own the blkg, do not send updates */
 168                 if (blkiop->plid != blkg->plid)
 169                         continue;
 170
 171                 if (fileid == BLKIO_THROTL_read_iops_device
 172                     && blkiop->ops.blkio_update_group_read_iops_fn)
 173                         blkiop->ops.blkio_update_group_read_iops_fn(blkg->key,
 174                                                                 blkg, iops);
 175
 176                 if (fileid == BLKIO_THROTL_write_iops_device
 177                     && blkiop->ops.blkio_update_group_write_iops_fn)
 178                         blkiop->ops.blkio_update_group_write_iops_fn(blkg->key,
 179                                                                 blkg,iops);
 180         }
 181 }
 182
 183 /*
 184  * Add to the appropriate stat variable depending on the request type.
 185  * This should be called with the blkg->stats_lock held.
 186  */
 187 static void blkio_add_stat(uint64_t *stat, uint64_t add, bool direction,
 188                                 bool sync)
 189 {
 190         if (direction)
 191                 stat[BLKIO_STAT_WRITE] += add;
 192         else
 193                 stat[BLKIO_STAT_READ] += add;
 194         if (sync)
 195                 stat[BLKIO_STAT_SYNC] += add;
 196         else
 197                 stat[BLKIO_STAT_ASYNC] += add;
 198 }
 199
 200 /*
 201  * Decrements the appropriate stat variable if non-zero depending on the
 202  * request type. Panics on value being zero.
 203  * This should be called with the blkg->stats_lock held.
 204  */
 205 static void blkio_check_and_dec_stat(uint64_t *stat, bool direction, bool sync)
 206 {
 207         if (direction) {
 208                 BUG_ON(stat[BLKIO_STAT_WRITE] == 0);
 209                 stat[BLKIO_STAT_WRITE]--;
 210         } else {
 211                 BUG_ON(stat[BLKIO_STAT_READ] == 0);
 212                 stat[BLKIO_STAT_READ]--;
 213         }
 214         if (sync) {
 215                 BUG_ON(stat[BLKIO_STAT_SYNC] == 0);
 216                 stat[BLKIO_STAT_SYNC]--;
 217         } else {
 218                 BUG_ON(stat[BLKIO_STAT_ASYNC] == 0);
 219                 stat[BLKIO_STAT_ASYNC]--;
 220         }
 221 }
 222
 223 #ifdef CONFIG_DEBUG_BLK_CGROUP
 224 /* This should be called with the blkg->stats_lock held. */
 225 static void blkio_set_start_group_wait_time(struct blkio_group *blkg,
 226                                                 struct blkio_group *curr_blkg)
 227 {
 228         if (blkio_blkg_waiting(&blkg->stats))
 229                 return;
 230         if (blkg == curr_blkg)
 231                 return;
 232         blkg->stats.start_group_wait_time = sched_clock();
 233         blkio_mark_blkg_waiting(&blkg->stats);
 234 }
 235
 236 /* This should be called with the blkg->stats_lock held. */
 237 static void blkio_update_group_wait_time(struct blkio_group_stats *stats)
 238 {
 239         unsigned long long now;
 240
 241         if (!blkio_blkg_waiting(stats))
 242                 return;
 243
 244         now = sched_clock();
 245         if (time_after64(now, stats->start_group_wait_time))
 246                 stats->group_wait_time += now - stats->start_group_wait_time;
 247         blkio_clear_blkg_waiting(stats);
 248 }
 249
 250 /* This should be called with the blkg->stats_lock held. */
 251 static void blkio_end_empty_time(struct blkio_group_stats *stats)
 252 {
 253         unsigned long long now;
 254
 255         if (!blkio_blkg_empty(stats))
 256                 return;
 257
 258         now = sched_clock();
 259         if (time_after64(now, stats->start_empty_time))
 260                 stats->empty_time += now - stats->start_empty_time;
 261         blkio_clear_blkg_empty(stats);
 262 }
 263
 264 void blkiocg_update_set_idle_time_stats(struct blkio_group *blkg)
 265 {
 266         unsigned long flags;
 267
 268         spin_lock_irqsave(&blkg->stats_lock, flags);
 269         BUG_ON(blkio_blkg_idling(&blkg->stats));
 270         blkg->stats.start_idle_time = sched_clock();
 271         blkio_mark_blkg_idling(&blkg->stats);
 272         spin_unlock_irqrestore(&blkg->stats_lock, flags);
 273 }
 274 EXPORT_SYMBOL_GPL(blkiocg_update_set_idle_time_stats);
 275
 276 void blkiocg_update_idle_time_stats(struct blkio_group *blkg)
 277 {
 278         unsigned long flags;
 279         unsigned long long now;
 280         struct blkio_group_stats *stats;
 281
 282         spin_lock_irqsave(&blkg->stats_lock, flags);
 283         stats = &blkg->stats;
 284         if (blkio_blkg_idling(stats)) {
 285                 now = sched_clock();
 286                 if (time_after64(now, stats->start_idle_time))
 287                         stats->idle_time += now - stats->start_idle_time;
 288                 blkio_clear_blkg_idling(stats);
 289         }
 290         spin_unlock_irqrestore(&blkg->stats_lock, flags);
 291 }
 292 EXPORT_SYMBOL_GPL(blkiocg_update_idle_time_stats);
 293
 294 void blkiocg_update_avg_queue_size_stats(struct blkio_group *blkg)
 295 {
 296         unsigned long flags;
 297         struct blkio_group_stats *stats;
 298
 299         spin_lock_irqsave(&blkg->stats_lock, flags);
 300         stats = &blkg->stats;
 301         stats->avg_queue_size_sum +=
 302                         stats->stat_arr[BLKIO_STAT_QUEUED][BLKIO_STAT_READ] +
 303                         stats->stat_arr[BLKIO_STAT_QUEUED][BLKIO_STAT_WRITE];
 304         stats->avg_queue_size_samples++;
 305         blkio_update_group_wait_time(stats);
 306         spin_unlock_irqrestore(&blkg->stats_lock, flags);
 307 }
 308 EXPORT_SYMBOL_GPL(blkiocg_update_avg_queue_size_stats);
 309
 310 void blkiocg_set_start_empty_time(struct blkio_group *blkg)
 311 {
 312         unsigned long flags;
 313         struct blkio_group_stats *stats;
 314
 315         spin_lock_irqsave(&blkg->stats_lock, flags);
 316         stats = &blkg->stats;
 317
 318         if (stats->stat_arr[BLKIO_STAT_QUEUED][BLKIO_STAT_READ] ||
 319                         stats->stat_arr[BLKIO_STAT_QUEUED][BLKIO_STAT_WRITE]) {
 320                 spin_unlock_irqrestore(&blkg->stats_lock, flags);
 321                 return;
 322         }
 323
 324         /*
 325          * group is already marked empty. This can happen if cfqq got new
 326          * request in parent group and moved to this group while being added
 327          * to service tree. Just ignore the event and move on.
 328          */
 329         if(blkio_blkg_empty(stats)) {
 330                 spin_unlock_irqrestore(&blkg->stats_lock, flags);
 331                 return;
 332         }
 333
 334         stats->start_empty_time = sched_clock();
 335         blkio_mark_blkg_empty(stats);
 336         spin_unlock_irqrestore(&blkg->stats_lock, flags);
 337 }
 338 EXPORT_SYMBOL_GPL(blkiocg_set_start_empty_time);
 339
 340 void blkiocg_update_dequeue_stats(struct blkio_group *blkg,
 341                         unsigned long dequeue)
 342 {
 343         blkg->stats.dequeue += dequeue;
 344 }
 345 EXPORT_SYMBOL_GPL(blkiocg_update_dequeue_stats);
 346 #else
 347 static inline void blkio_set_start_group_wait_time(struct blkio_group *blkg,
 348                                         struct blkio_group *curr_blkg) {}
 349 static inline void blkio_end_empty_time(struct blkio_group_stats *stats) {}
 350 #endif
 351
 352 void blkiocg_update_io_add_stats(struct blkio_group *blkg,
 353                         struct blkio_group *curr_blkg, bool direction,
 354                         bool sync)
 355 {
 356         unsigned long flags;
 357
 358         spin_lock_irqsave(&blkg->stats_lock, flags);
 359         blkio_add_stat(blkg->stats.stat_arr[BLKIO_STAT_QUEUED], 1, direction,
 360                         sync);
 361         blkio_end_empty_time(&blkg->stats);
 362         blkio_set_start_group_wait_time(blkg, curr_blkg);
 363         spin_unlock_irqrestore(&blkg->stats_lock, flags);
 364 }
 365 EXPORT_SYMBOL_GPL(blkiocg_update_io_add_stats);
 366
 367 void blkiocg_update_io_remove_stats(struct blkio_group *blkg,
 368                                                 bool direction, bool sync)
 369 {
 370         unsigned long flags;
 371
 372         spin_lock_irqsave(&blkg->stats_lock, flags);
 373         blkio_check_and_dec_stat(blkg->stats.stat_arr[BLKIO_STAT_QUEUED],
 374                                         direction, sync);
 375         spin_unlock_irqrestore(&blkg->stats_lock, flags);
 376 }
 377 EXPORT_SYMBOL_GPL(blkiocg_update_io_remove_stats);
 378
 379 void blkiocg_update_timeslice_used(struct blkio_group *blkg, unsigned long time,
 380                                 unsigned long unaccounted_time)
 381 {
 382         unsigned long flags;
 383
 384         spin_lock_irqsave(&blkg->stats_lock, flags);
 385         blkg->stats.time += time;
 386 #ifdef CONFIG_DEBUG_BLK_CGROUP
 387         blkg->stats.unaccounted_time += unaccounted_time;
 388 #endif
 389         spin_unlock_irqrestore(&blkg->stats_lock, flags);
 390 }
 391 EXPORT_SYMBOL_GPL(blkiocg_update_timeslice_used);
 392
 393 /*
 394  * should be called under rcu read lock or queue lock to make sure blkg pointer
 395  * is valid.
 396  */
 397 void blkiocg_update_dispatch_stats(struct blkio_group *blkg,
 398                                 uint64_t bytes, bool direction, bool sync)
 399 {
 400         struct blkio_group_stats_cpu *stats_cpu;
 401         unsigned long flags;
 402
 403         /*
 404          * Disabling interrupts to provide mutual exclusion between two
 405          * writes on same cpu. It probably is not needed for 64bit. Not
 406          * optimizing that case yet.
 407          */
 408         local_irq_save(flags);
 409
 410         stats_cpu = this_cpu_ptr(blkg->stats_cpu);
 411
 412         u64_stats_update_begin(&stats_cpu->syncp);
 413         stats_cpu->sectors += bytes >> 9;
 414         blkio_add_stat(stats_cpu->stat_arr_cpu[BLKIO_STAT_CPU_SERVICED],
 415                         1, direction, sync);
 416         blkio_add_stat(stats_cpu->stat_arr_cpu[BLKIO_STAT_CPU_SERVICE_BYTES],
 417                         bytes, direction, sync);
 418         u64_stats_update_end(&stats_cpu->syncp);
 419         local_irq_restore(flags);
 420 }
 421 EXPORT_SYMBOL_GPL(blkiocg_update_dispatch_stats);
 422
 423 void blkiocg_update_completion_stats(struct blkio_group *blkg,
 424         uint64_t start_time, uint64_t io_start_time, bool direction, bool sync)
 425 {
 426         struct blkio_group_stats *stats;
 427         unsigned long flags;
 428         unsigned long long now = sched_clock();
 429
 430         spin_lock_irqsave(&blkg->stats_lock, flags);
 431         stats = &blkg->stats;
 432         if (time_after64(now, io_start_time))
 433                 blkio_add_stat(stats->stat_arr[BLKIO_STAT_SERVICE_TIME],
 434                                 now - io_start_time, direction, sync);
 435         if (time_after64(io_start_time, start_time))
 436                 blkio_add_stat(stats->stat_arr[BLKIO_STAT_WAIT_TIME],
 437                                 io_start_time - start_time, direction, sync);
 438         spin_unlock_irqrestore(&blkg->stats_lock, flags);
 439 }
 440 EXPORT_SYMBOL_GPL(blkiocg_update_completion_stats);
 441
 442 /*  Merged stats are per cpu.  */
 443 void blkiocg_update_io_merged_stats(struct blkio_group *blkg, bool direction,
 444                                         bool sync)
 445 {
 446         struct blkio_group_stats_cpu *stats_cpu;
 447         unsigned long flags;
 448
 449         /*
 450          * Disabling interrupts to provide mutual exclusion between two
 451          * writes on same cpu. It probably is not needed for 64bit. Not
 452          * optimizing that case yet.
 453          */
 454         local_irq_save(flags);
 455
 456         stats_cpu = this_cpu_ptr(blkg->stats_cpu);
 457
 458         u64_stats_update_begin(&stats_cpu->syncp);
 459         blkio_add_stat(stats_cpu->stat_arr_cpu[BLKIO_STAT_CPU_MERGED], 1,
 460                                 direction, sync);
 461         u64_stats_update_end(&stats_cpu->syncp);
 462         local_irq_restore(flags);
 463 }
 464 EXPORT_SYMBOL_GPL(blkiocg_update_io_merged_stats);
 465
 466 /*
 467  * This function allocates the per cpu stats for blkio_group. Should be called
 468  * from sleepable context as alloc_per_cpu() requires that.
 469  */
 470 int blkio_alloc_blkg_stats(struct blkio_group *blkg)
 471 {
 472         /* Allocate memory for per cpu stats */
 473         blkg->stats_cpu = alloc_percpu(struct blkio_group_stats_cpu);
 474         if (!blkg->stats_cpu)
 475                 return -ENOMEM;
 476         return 0;
 477 }
 478 EXPORT_SYMBOL_GPL(blkio_alloc_blkg_stats);
 479
 480 void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg,
 481                 struct blkio_group *blkg, void *key, dev_t dev,
 482                 enum blkio_policy_id plid)
 483 {
 484         unsigned long flags;
 485
 486         spin_lock_irqsave(&blkcg->lock, flags);
 487         spin_lock_init(&blkg->stats_lock);
 488         rcu_assign_pointer(blkg->key, key);
 489         blkg->blkcg_id = css_id(&blkcg->css);
 490         hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list);
 491         blkg->plid = plid;
 492         spin_unlock_irqrestore(&blkcg->lock, flags);
 493         /* Need to take css reference ? */
 494         cgroup_path(blkcg->css.cgroup, blkg->path, sizeof(blkg->path));
 495         blkg->dev = dev;
 496 }
 497 EXPORT_SYMBOL_GPL(blkiocg_add_blkio_group);
 498
 499 static void __blkiocg_del_blkio_group(struct blkio_group *blkg)
 500 {
 501         hlist_del_init_rcu(&blkg->blkcg_node);
 502         blkg->blkcg_id = 0;
 503 }
 504
 505 /*
 506  * returns 0 if blkio_group was still on cgroup list. Otherwise returns 1
 507  * indicating that blk_group was unhashed by the time we got to it.
 508  */
 509 int blkiocg_del_blkio_group(struct blkio_group *blkg)
 510 {
 511         struct blkio_cgroup *blkcg;
 512         unsigned long flags;
 513         struct cgroup_subsys_state *css;
 514         int ret = 1;
 515
 516         rcu_read_lock();
 517         css = css_lookup(&blkio_subsys, blkg->blkcg_id);
 518         if (css) {
 519                 blkcg = container_of(css, struct blkio_cgroup, css);
 520                 spin_lock_irqsave(&blkcg->lock, flags);
 521                 if (!hlist_unhashed(&blkg->blkcg_node)) {
 522                         __blkiocg_del_blkio_group(blkg);
 523                         ret = 0;
 524                 }
 525                 spin_unlock_irqrestore(&blkcg->lock, flags);
 526         }
 527
 528         rcu_read_unlock();
 529         return ret;
 530 }
 531 EXPORT_SYMBOL_GPL(blkiocg_del_blkio_group);
 532
 533 /* called under rcu_read_lock(). */
 534 struct blkio_group *blkiocg_lookup_group(struct blkio_cgroup *blkcg, void *key)
 535 {
 536         struct blkio_group *blkg;
 537         struct hlist_node *n;
 538         void *__key;
 539
 540         hlist_for_each_entry_rcu(blkg, n, &blkcg->blkg_list, blkcg_node) {
 541                 __key = blkg->key;
 542                 if (__key == key)
 543                         return blkg;
 544         }
 545
 546         return NULL;
 547 }
 548 EXPORT_SYMBOL_GPL(blkiocg_lookup_group);
 549
 550 static void blkio_reset_stats_cpu(struct blkio_group *blkg)
 551 {
 552         struct blkio_group_stats_cpu *stats_cpu;
 553         int i, j, k;
 554         /*
 555          * Note: On 64 bit arch this should not be an issue. This has the
 556          * possibility of returning some inconsistent value on 32bit arch
 557          * as 64bit update on 32bit is non atomic. Taking care of this
 558          * corner case makes code very complicated, like sending IPIs to
 559          * cpus, taking care of stats of offline cpus etc.
 560          *
 561          * reset stats is anyway more of a debug feature and this sounds a
 562          * corner case. So I am not complicating the code yet until and
 563          * unless this becomes a real issue.
 564          */
 565         for_each_possible_cpu(i) {
 566                 stats_cpu = per_cpu_ptr(blkg->stats_cpu, i);
 567                 stats_cpu->sectors = 0;
 568                 for(j = 0; j < BLKIO_STAT_CPU_NR; j++)
 569                         for (k = 0; k < BLKIO_STAT_TOTAL; k++)
 570                                 stats_cpu->stat_arr_cpu[j][k] = 0;
 571         }
 572 }
 573
 574 static int
 575 blkiocg_reset_stats(struct cgroup *cgroup, struct cftype *cftype, u64 val)
 576 {
 577         struct blkio_cgroup *blkcg;
 578         struct blkio_group *blkg;
 579         struct blkio_group_stats *stats;
 580         struct hlist_node *n;
 581         uint64_t queued[BLKIO_STAT_TOTAL];
 582         int i;
 583 #ifdef CONFIG_DEBUG_BLK_CGROUP
 584         bool idling, waiting, empty;
 585         unsigned long long now = sched_clock();
 586 #endif
 587
 588         blkcg = cgroup_to_blkio_cgroup(cgroup);
 589         spin_lock_irq(&blkcg->lock);
 590         hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
 591                 spin_lock(&blkg->stats_lock);
 592                 stats = &blkg->stats;
 593 #ifdef CONFIG_DEBUG_BLK_CGROUP
 594                 idling = blkio_blkg_idling(stats);
 595                 waiting = blkio_blkg_waiting(stats);
 596                 empty = blkio_blkg_empty(stats);
 597 #endif
 598                 for (i = 0; i < BLKIO_STAT_TOTAL; i++)
 599                         queued[i] = stats->stat_arr[BLKIO_STAT_QUEUED][i];
 600                 memset(stats, 0, sizeof(struct blkio_group_stats));
 601                 for (i = 0; i < BLKIO_STAT_TOTAL; i++)
 602                         stats->stat_arr[BLKIO_STAT_QUEUED][i] = queued[i];
 603 #ifdef CONFIG_DEBUG_BLK_CGROUP
 604                 if (idling) {
 605                         blkio_mark_blkg_idling(stats);
 606                         stats->start_idle_time = now;
 607                 }
 608                 if (waiting) {
 609                         blkio_mark_blkg_waiting(stats);
 610                         stats->start_group_wait_time = now;
 611                 }
 612                 if (empty) {
 613                         blkio_mark_blkg_empty(stats);
 614                         stats->start_empty_time = now;
 615                 }
 616 #endif
 617                 spin_unlock(&blkg->stats_lock);
 618
 619                 /* Reset Per cpu stats which don't take blkg->stats_lock */
 620                 blkio_reset_stats_cpu(blkg);
 621         }
 622
 623         spin_unlock_irq(&blkcg->lock);
 624         return 0;
 625 }
 626
 627 static void blkio_get_key_name(enum stat_sub_type type, dev_t dev, char *str,
 628                                 int chars_left, bool diskname_only)
 629 {
 630         snprintf(str, chars_left, "%d:%d", MAJOR(dev), MINOR(dev));
 631         chars_left -= strlen(str);
 632         if (chars_left <= 0) {
 633                 printk(KERN_WARNING
 634                         "Possibly incorrect cgroup stat display format");
 635                 return;
 636         }
 637         if (diskname_only)
 638                 return;
 639         switch (type) {
 640         case BLKIO_STAT_READ:
 641                 strlcat(str, " Read", chars_left);
 642                 break;
 643         case BLKIO_STAT_WRITE:
 644                 strlcat(str, " Write", chars_left);
 645                 break;
 646         case BLKIO_STAT_SYNC:
 647                 strlcat(str, " Sync", chars_left);
 648                 break;
 649         case BLKIO_STAT_ASYNC:
 650                 strlcat(str, " Async", chars_left);
 651                 break;
 652         case BLKIO_STAT_TOTAL:
 653                 strlcat(str, " Total", chars_left);
 654                 break;
 655         default:
 656                 strlcat(str, " Invalid", chars_left);
 657         }
 658 }
 659
 660 static uint64_t blkio_fill_stat(char *str, int chars_left, uint64_t val,
 661                                 struct cgroup_map_cb *cb, dev_t dev)
 662 {
 663         blkio_get_key_name(0, dev, str, chars_left, true);
 664         cb->fill(cb, str, val);
 665         return val;
 666 }
 667
 668
 669 static uint64_t blkio_read_stat_cpu(struct blkio_group *blkg,
 670                         enum stat_type_cpu type, enum stat_sub_type sub_type)
 671 {
 672         int cpu;
 673         struct blkio_group_stats_cpu *stats_cpu;
 674         u64 val = 0, tval;
 675
 676         for_each_possible_cpu(cpu) {
 677                 unsigned int start;
 678                 stats_cpu  = per_cpu_ptr(blkg->stats_cpu, cpu);
 679
 680                 do {
 681                         start = u64_stats_fetch_begin(&stats_cpu->syncp);
 682                         if (type == BLKIO_STAT_CPU_SECTORS)
 683                                 tval = stats_cpu->sectors;
 684                         else
 685                                 tval = stats_cpu->stat_arr_cpu[type][sub_type];
 686                 } while(u64_stats_fetch_retry(&stats_cpu->syncp, start));
 687
 688                 val += tval;
 689         }
 690
 691         return val;
 692 }
 693
 694 static uint64_t blkio_get_stat_cpu(struct blkio_group *blkg,
 695                 struct cgroup_map_cb *cb, dev_t dev, enum stat_type_cpu type)
 696 {
 697         uint64_t disk_total, val;
 698         char key_str[MAX_KEY_LEN];
 699         enum stat_sub_type sub_type;
 700
 701         if (type == BLKIO_STAT_CPU_SECTORS) {
 702                 val = blkio_read_stat_cpu(blkg, type, 0);
 703                 return blkio_fill_stat(key_str, MAX_KEY_LEN - 1, val, cb, dev);
 704         }
 705
 706         for (sub_type = BLKIO_STAT_READ; sub_type < BLKIO_STAT_TOTAL;
 707                         sub_type++) {
 708                 blkio_get_key_name(sub_type, dev, key_str, MAX_KEY_LEN, false);
 709                 val = blkio_read_stat_cpu(blkg, type, sub_type);
 710                 cb->fill(cb, key_str, val);
 711         }
 712
 713         disk_total = blkio_read_stat_cpu(blkg, type, BLKIO_STAT_READ) +
 714                         blkio_read_stat_cpu(blkg, type, BLKIO_STAT_WRITE);
 715
 716         blkio_get_key_name(BLKIO_STAT_TOTAL, dev, key_str, MAX_KEY_LEN, false);
 717         cb->fill(cb, key_str, disk_total);
 718         return disk_total;
 719 }
 720
 721 /* This should be called with blkg->stats_lock held */
 722 static uint64_t blkio_get_stat(struct blkio_group *blkg,
 723                 struct cgroup_map_cb *cb, dev_t dev, enum stat_type type)
 724 {
 725         uint64_t disk_total;
 726         char key_str[MAX_KEY_LEN];
 727         enum stat_sub_type sub_type;
 728
 729         if (type == BLKIO_STAT_TIME)
 730                 return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
 731                                         blkg->stats.time, cb, dev);
 732 #ifdef CONFIG_DEBUG_BLK_CGROUP
 733         if (type == BLKIO_STAT_UNACCOUNTED_TIME)
 734                 return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
 735                                         blkg->stats.unaccounted_time, cb, dev);
 736         if (type == BLKIO_STAT_AVG_QUEUE_SIZE) {
 737                 uint64_t sum = blkg->stats.avg_queue_size_sum;
 738                 uint64_t samples = blkg->stats.avg_queue_size_samples;
 739                 if (samples)
 740                         do_div(sum, samples);
 741                 else
 742                         sum = 0;
 743                 return blkio_fill_stat(key_str, MAX_KEY_LEN - 1, sum, cb, dev);
 744         }
 745         if (type == BLKIO_STAT_GROUP_WAIT_TIME)
 746                 return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
 747                                         blkg->stats.group_wait_time, cb, dev);
 748         if (type == BLKIO_STAT_IDLE_TIME)
 749                 return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
 750                                         blkg->stats.idle_time, cb, dev);
 751         if (type == BLKIO_STAT_EMPTY_TIME)
 752                 return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
 753                                         blkg->stats.empty_time, cb, dev);
 754         if (type == BLKIO_STAT_DEQUEUE)
 755                 return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
 756                                         blkg->stats.dequeue, cb, dev);
 757 #endif
 758
 759         for (sub_type = BLKIO_STAT_READ; sub_type < BLKIO_STAT_TOTAL;
 760                         sub_type++) {
 761                 blkio_get_key_name(sub_type, dev, key_str, MAX_KEY_LEN, false);
 762                 cb->fill(cb, key_str, blkg->stats.stat_arr[type][sub_type]);
 763         }
 764         disk_total = blkg->stats.stat_arr[type][BLKIO_STAT_READ] +
 765                         blkg->stats.stat_arr[type][BLKIO_STAT_WRITE];
 766         blkio_get_key_name(BLKIO_STAT_TOTAL, dev, key_str, MAX_KEY_LEN, false);
 767         cb->fill(cb, key_str, disk_total);
 768         return disk_total;
 769 }
 770
 771 static int blkio_policy_parse_and_set(char *buf,
 772         struct blkio_policy_node *newpn, enum blkio_policy_id plid, int fileid)
 773 {
 774         struct gendisk *disk = NULL;
 775         char *s[4], *p, *major_s = NULL, *minor_s = NULL;
 776         unsigned long major, minor;
 777         int i = 0, ret = -EINVAL;
 778         int part;
 779         dev_t dev;
 780         u64 temp;
 781
 782         memset(s, 0, sizeof(s));
 783
 784         while ((p = strsep(&buf, " ")) != NULL) {
 785                 if (!*p)
 786                         continue;
 787
 788                 s[i++] = p;
 789
 790                 /* Prevent from inputing too many things */
 791                 if (i == 3)
 792                         break;
 793         }
 794
 795         if (i != 2)
 796                 goto out;
 797
 798         p = strsep(&s[0], ":");
 799         if (p != NULL)
 800                 major_s = p;
 801         else
 802                 goto out;
 803
 804         minor_s = s[0];
 805         if (!minor_s)
 806                 goto out;
 807
 808         if (strict_strtoul(major_s, 10, &major))
 809                 goto out;
 810
 811         if (strict_strtoul(minor_s, 10, &minor))
 812                 goto out;
 813
 814         dev = MKDEV(major, minor);
 815
 816         if (strict_strtoull(s[1], 10, &temp))
 817                 goto out;
 818
 819         /* For rule removal, do not check for device presence. */
 820         if (temp) {
 821                 disk = get_gendisk(dev, &part);
 822                 if (!disk || part) {
 823                         ret = -ENODEV;
 824                         goto out;
 825                 }
 826         }
 827
 828         newpn->dev = dev;
 829
 830         switch (plid) {
 831         case BLKIO_POLICY_PROP:
 832                 if ((temp < BLKIO_WEIGHT_MIN && temp > 0) ||
 833                      temp > BLKIO_WEIGHT_MAX)
 834                         goto out;
 835
 836                 newpn->plid = plid;
 837                 newpn->fileid = fileid;
 838                 newpn->val.weight = temp;
 839                 break;
 840         case BLKIO_POLICY_THROTL:
 841                 switch(fileid) {
 842                 case BLKIO_THROTL_read_bps_device:
 843                 case BLKIO_THROTL_write_bps_device:
 844                         newpn->plid = plid;
 845                         newpn->fileid = fileid;
 846                         newpn->val.bps = temp;
 847                         break;
 848                 case BLKIO_THROTL_read_iops_device:
 849                 case BLKIO_THROTL_write_iops_device:
 850                         if (temp > THROTL_IOPS_MAX)
 851                                 goto out;
 852
 853                         newpn->plid = plid;
 854                         newpn->fileid = fileid;
 855                         newpn->val.iops = (unsigned int)temp;
 856                         break;
 857                 }
 858                 break;
 859         default:
 860                 BUG();
 861         }
 862         ret = 0;
 863 out:
 864         put_disk(disk);
 865         return ret;
 866 }
 867
 868 unsigned int blkcg_get_weight(struct blkio_cgroup *blkcg,
 869                               dev_t dev)
 870 {
 871         struct blkio_policy_node *pn;
 872         unsigned long flags;
 873         unsigned int weight;
 874
 875         spin_lock_irqsave(&blkcg->lock, flags);
 876
 877         pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_PROP,
 878                                 BLKIO_PROP_weight_device);
 879         if (pn)
 880                 weight = pn->val.weight;
 881         else
 882                 weight = blkcg->weight;
 883
 884         spin_unlock_irqrestore(&blkcg->lock, flags);
 885
 886         return weight;
 887 }
 888 EXPORT_SYMBOL_GPL(blkcg_get_weight);
 889
 890 uint64_t blkcg_get_read_bps(struct blkio_cgroup *blkcg, dev_t dev)
 891 {
 892         struct blkio_policy_node *pn;
 893         unsigned long flags;
 894         uint64_t bps = -1;
 895
 896         spin_lock_irqsave(&blkcg->lock, flags);
 897         pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_THROTL,
 898                                 BLKIO_THROTL_read_bps_device);
 899         if (pn)
 900                 bps = pn->val.bps;
 901         spin_unlock_irqrestore(&blkcg->lock, flags);
 902
 903         return bps;
 904 }
 905
 906 uint64_t blkcg_get_write_bps(struct blkio_cgroup *blkcg, dev_t dev)
 907 {
 908         struct blkio_policy_node *pn;
 909         unsigned long flags;
 910         uint64_t bps = -1;
 911
 912         spin_lock_irqsave(&blkcg->lock, flags);
 913         pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_THROTL,
 914                                 BLKIO_THROTL_write_bps_device);
 915         if (pn)
 916                 bps = pn->val.bps;
 917         spin_unlock_irqrestore(&blkcg->lock, flags);
 918
 919         return bps;
 920 }
 921
 922 unsigned int blkcg_get_read_iops(struct blkio_cgroup *blkcg, dev_t dev)
 923 {
 924         struct blkio_policy_node *pn;
 925         unsigned long flags;
 926         unsigned int iops = -1;
 927
 928         spin_lock_irqsave(&blkcg->lock, flags);
 929         pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_THROTL,
 930                                 BLKIO_THROTL_read_iops_device);
 931         if (pn)
 932                 iops = pn->val.iops;
 933         spin_unlock_irqrestore(&blkcg->lock, flags);
 934
 935         return iops;
 936 }
 937
 938 unsigned int blkcg_get_write_iops(struct blkio_cgroup *blkcg, dev_t dev)
 939 {
 940         struct blkio_policy_node *pn;
 941         unsigned long flags;
 942         unsigned int iops = -1;
 943
 944         spin_lock_irqsave(&blkcg->lock, flags);
 945         pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_THROTL,
 946                                 BLKIO_THROTL_write_iops_device);
 947         if (pn)
 948                 iops = pn->val.iops;
 949         spin_unlock_irqrestore(&blkcg->lock, flags);
 950
 951         return iops;
 952 }
 953
 954 /* Checks whether user asked for deleting a policy rule */
 955 static bool blkio_delete_rule_command(struct blkio_policy_node *pn)
 956 {
 957         switch(pn->plid) {
 958         case BLKIO_POLICY_PROP:
 959                 if (pn->val.weight == 0)
 960                         return 1;
 961                 break;
 962         case BLKIO_POLICY_THROTL:
 963                 switch(pn->fileid) {
 964                 case BLKIO_THROTL_read_bps_device:
 965                 case BLKIO_THROTL_write_bps_device:
 966                         if (pn->val.bps == 0)
 967                                 return 1;
 968                         break;
 969                 case BLKIO_THROTL_read_iops_device:
 970                 case BLKIO_THROTL_write_iops_device:
 971                         if (pn->val.iops == 0)
 972                                 return 1;
 973                 }
 974                 break;
 975         default:
 976                 BUG();
 977         }
 978
 979         return 0;
 980 }
 981
 982 static void blkio_update_policy_rule(struct blkio_policy_node *oldpn,
 983                                         struct blkio_policy_node *newpn)
 984 {
 985         switch(oldpn->plid) {
 986         case BLKIO_POLICY_PROP:
 987                 oldpn->val.weight = newpn->val.weight;
 988                 break;
 989         case BLKIO_POLICY_THROTL:
 990                 switch(newpn->fileid) {
 991                 case BLKIO_THROTL_read_bps_device:
 992                 case BLKIO_THROTL_write_bps_device:
 993                         oldpn->val.bps = newpn->val.bps;
 994                         break;
 995                 case BLKIO_THROTL_read_iops_device:
 996                 case BLKIO_THROTL_write_iops_device:
 997                         oldpn->val.iops = newpn->val.iops;
 998                 }
 999                 break;
1000         default:
1001                 BUG();
1002         }
1003 }
1004
1005 /*
1006  * Some rules/values in blkg have changed. Propagate those to respective
1007  * policies.
1008  */
1009 static void blkio_update_blkg_policy(struct blkio_cgroup *blkcg,
1010                 struct blkio_group *blkg, struct blkio_policy_node *pn)
1011 {
1012         unsigned int weight, iops;
1013         u64 bps;
1014
1015         switch(pn->plid) {
1016         case BLKIO_POLICY_PROP:
1017                 weight = pn->val.weight ? pn->val.weight :
1018                                 blkcg->weight;
1019                 blkio_update_group_weight(blkg, weight);
1020                 break;
1021         case BLKIO_POLICY_THROTL:
1022                 switch(pn->fileid) {
1023                 case BLKIO_THROTL_read_bps_device:
1024                 case BLKIO_THROTL_write_bps_device:
1025                         bps = pn->val.bps ? pn->val.bps : (-1);
1026                         blkio_update_group_bps(blkg, bps, pn->fileid);
1027                         break;
1028                 case BLKIO_THROTL_read_iops_device:
1029                 case BLKIO_THROTL_write_iops_device:
1030                         iops = pn->val.iops ? pn->val.iops : (-1);
1031                         blkio_update_group_iops(blkg, iops, pn->fileid);
1032                         break;
1033                 }
1034                 break;
1035         default:
1036                 BUG();
1037         }
1038 }
1039
1040 /*
1041  * A policy node rule has been updated. Propagate this update to all the
1042  * block groups which might be affected by this update.
1043  */
1044 static void blkio_update_policy_node_blkg(struct blkio_cgroup *blkcg,
1045                                 struct blkio_policy_node *pn)
1046 {
1047         struct blkio_group *blkg;
1048         struct hlist_node *n;
1049
1050         spin_lock(&blkio_list_lock);
1051         spin_lock_irq(&blkcg->lock);
1052
1053         hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
1054                 if (pn->dev != blkg->dev || pn->plid != blkg->plid)
1055                         continue;
1056                 blkio_update_blkg_policy(blkcg, blkg, pn);
1057         }
1058
1059         spin_unlock_irq(&blkcg->lock);
1060         spin_unlock(&blkio_list_lock);
1061 }
1062
1063 static int blkiocg_file_write(struct cgroup *cgrp, struct cftype *cft,
1064                                        const char *buffer)
1065 {
1066         int ret = 0;
1067         char *buf;
1068         struct blkio_policy_node *newpn, *pn;
1069         struct blkio_cgroup *blkcg;
1070         int keep_newpn = 0;
1071         enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private);
1072         int fileid = BLKIOFILE_ATTR(cft->private);
1073
1074         buf = kstrdup(buffer, GFP_KERNEL);
1075         if (!buf)
1076                 return -ENOMEM;
1077
1078         newpn = kzalloc(sizeof(*newpn), GFP_KERNEL);
1079         if (!newpn) {
1080                 ret = -ENOMEM;
1081                 goto free_buf;
1082         }
1083
1084         ret = blkio_policy_parse_and_set(buf, newpn, plid, fileid);
1085         if (ret)
1086                 goto free_newpn;
1087
1088         blkcg = cgroup_to_blkio_cgroup(cgrp);
1089
1090         spin_lock_irq(&blkcg->lock);
1091
1092         pn = blkio_policy_search_node(blkcg, newpn->dev, plid, fileid);
1093         if (!pn) {
1094                 if (!blkio_delete_rule_command(newpn)) {
1095                         blkio_policy_insert_node(blkcg, newpn);
1096                         keep_newpn = 1;
1097                 }
1098                 spin_unlock_irq(&blkcg->lock);
1099                 goto update_io_group;
1100         }
1101
1102         if (blkio_delete_rule_command(newpn)) {
1103                 blkio_policy_delete_node(pn);
1104                 kfree(pn);
1105                 spin_unlock_irq(&blkcg->lock);
1106                 goto update_io_group;
1107         }
1108         spin_unlock_irq(&blkcg->lock);
1109
1110         blkio_update_policy_rule(pn, newpn);
1111
1112 update_io_group:
1113         blkio_update_policy_node_blkg(blkcg, newpn);
1114
1115 free_newpn:
1116         if (!keep_newpn)
1117                 kfree(newpn);
1118 free_buf:
1119         kfree(buf);
1120         return ret;
1121 }
1122
1123 static void
1124 blkio_print_policy_node(struct seq_file *m, struct blkio_policy_node *pn)
1125 {
1126         switch(pn->plid) {
1127                 case BLKIO_POLICY_PROP:
1128                         if (pn->fileid == BLKIO_PROP_weight_device)
1129                                 seq_printf(m, "%u:%u\t%u\n", MAJOR(pn->dev),
1130                                         MINOR(pn->dev), pn->val.weight);
1131                         break;
1132                 case BLKIO_POLICY_THROTL:
1133                         switch(pn->fileid) {
1134                         case BLKIO_THROTL_read_bps_device:
1135                         case BLKIO_THROTL_write_bps_device:
1136                                 seq_printf(m, "%u:%u\t%llu\n", MAJOR(pn->dev),
1137                                         MINOR(pn->dev), pn->val.bps);
1138                                 break;
1139                         case BLKIO_THROTL_read_iops_device:
1140                         case BLKIO_THROTL_write_iops_device:
1141                                 seq_printf(m, "%u:%u\t%u\n", MAJOR(pn->dev),
1142                                         MINOR(pn->dev), pn->val.iops);
1143                                 break;
1144                         }
1145                         break;
1146                 default:
1147                         BUG();
1148         }
1149 }
1150
1151 /* cgroup files which read their data from policy nodes end up here */
1152 static void blkio_read_policy_node_files(struct cftype *cft,
1153                         struct blkio_cgroup *blkcg, struct seq_file *m)
1154 {
1155         struct blkio_policy_node *pn;
1156
1157         if (!list_empty(&blkcg->policy_list)) {
1158                 spin_lock_irq(&blkcg->lock);
1159                 list_for_each_entry(pn, &blkcg->policy_list, node) {
1160                         if (!pn_matches_cftype(cft, pn))
1161                                 continue;
1162                         blkio_print_policy_node(m, pn);
1163                 }
1164                 spin_unlock_irq(&blkcg->lock);
1165         }
1166 }
1167
1168 static int blkiocg_file_read(struct cgroup *cgrp, struct cftype *cft,
1169                                 struct seq_file *m)
1170 {
1171         struct blkio_cgroup *blkcg;
1172         enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private);
1173         int name = BLKIOFILE_ATTR(cft->private);
1174
1175         blkcg = cgroup_to_blkio_cgroup(cgrp);
1176
1177         switch(plid) {
1178         case BLKIO_POLICY_PROP:
1179                 switch(name) {
1180                 case BLKIO_PROP_weight_device:
1181                         blkio_read_policy_node_files(cft, blkcg, m);
1182                         return 0;
1183                 default:
1184                         BUG();
1185                 }
1186                 break;
1187         case BLKIO_POLICY_THROTL:
1188                 switch(name){
1189                 case BLKIO_THROTL_read_bps_device:
1190                 case BLKIO_THROTL_write_bps_device:
1191                 case BLKIO_THROTL_read_iops_device:
1192                 case BLKIO_THROTL_write_iops_device:
1193                         blkio_read_policy_node_files(cft, blkcg, m);
1194                         return 0;
1195                 default:
1196                         BUG();
1197                 }
1198                 break;
1199         default:
1200                 BUG();
1201         }
1202
1203         return 0;
1204 }
1205
1206 static int blkio_read_blkg_stats(struct blkio_cgroup *blkcg,
1207                 struct cftype *cft, struct cgroup_map_cb *cb,
1208                 enum stat_type type, bool show_total, bool pcpu)
1209 {
1210         struct blkio_group *blkg;
1211         struct hlist_node *n;
1212         uint64_t cgroup_total = 0;
1213
1214         rcu_read_lock();
1215         hlist_for_each_entry_rcu(blkg, n, &blkcg->blkg_list, blkcg_node) {
1216                 if (blkg->dev) {
1217                         if (!cftype_blkg_same_policy(cft, blkg))
1218                                 continue;
1219                         if (pcpu)
1220                                 cgroup_total += blkio_get_stat_cpu(blkg, cb,
1221                                                 blkg->dev, type);
1222                         else {
1223                                 spin_lock_irq(&blkg->stats_lock);
1224                                 cgroup_total += blkio_get_stat(blkg, cb,
1225                                                 blkg->dev, type);
1226                                 spin_unlock_irq(&blkg->stats_lock);
1227                         }
1228                 }
1229         }
1230         if (show_total)
1231                 cb->fill(cb, "Total", cgroup_total);
1232         rcu_read_unlock();
1233         return 0;
1234 }
1235
1236 /* All map kind of cgroup file get serviced by this function */
1237 static int blkiocg_file_read_map(struct cgroup *cgrp, struct cftype *cft,
1238                                 struct cgroup_map_cb *cb)
1239 {
1240         struct blkio_cgroup *blkcg;
1241         enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private);
1242         int name = BLKIOFILE_ATTR(cft->private);
1243
1244         blkcg = cgroup_to_blkio_cgroup(cgrp);
1245
1246         switch(plid) {
1247         case BLKIO_POLICY_PROP:
1248                 switch(name) {
1249                 case BLKIO_PROP_time:
1250                         return blkio_read_blkg_stats(blkcg, cft, cb,
1251                                                 BLKIO_STAT_TIME, 0, 0);
1252                 case BLKIO_PROP_sectors:
1253                         return blkio_read_blkg_stats(blkcg, cft, cb,
1254                                                 BLKIO_STAT_CPU_SECTORS, 0, 1);
1255                 case BLKIO_PROP_io_service_bytes:
1256                         return blkio_read_blkg_stats(blkcg, cft, cb,
1257                                         BLKIO_STAT_CPU_SERVICE_BYTES, 1, 1);
1258                 case BLKIO_PROP_io_serviced:
1259                         return blkio_read_blkg_stats(blkcg, cft, cb,
1260                                                 BLKIO_STAT_CPU_SERVICED, 1, 1);
1261                 case BLKIO_PROP_io_service_time:
1262                         return blkio_read_blkg_stats(blkcg, cft, cb,
1263                                                 BLKIO_STAT_SERVICE_TIME, 1, 0);
1264                 case BLKIO_PROP_io_wait_time:
1265                         return blkio_read_blkg_stats(blkcg, cft, cb,
1266                                                 BLKIO_STAT_WAIT_TIME, 1, 0);
1267                 case BLKIO_PROP_io_merged:
1268                         return blkio_read_blkg_stats(blkcg, cft, cb,
1269                                                 BLKIO_STAT_CPU_MERGED, 1, 1);
1270                 case BLKIO_PROP_io_queued:
1271                         return blkio_read_blkg_stats(blkcg, cft, cb,
1272                                                 BLKIO_STAT_QUEUED, 1, 0);
1273 #ifdef CONFIG_DEBUG_BLK_CGROUP
1274                 case BLKIO_PROP_unaccounted_time:
1275                         return blkio_read_blkg_stats(blkcg, cft, cb,
1276                                         BLKIO_STAT_UNACCOUNTED_TIME, 0, 0);
1277                 case BLKIO_PROP_dequeue:
1278                         return blkio_read_blkg_stats(blkcg, cft, cb,
1279                                                 BLKIO_STAT_DEQUEUE, 0, 0);
1280                 case BLKIO_PROP_avg_queue_size:
1281                         return blkio_read_blkg_stats(blkcg, cft, cb,
1282                                         BLKIO_STAT_AVG_QUEUE_SIZE, 0, 0);
1283                 case BLKIO_PROP_group_wait_time:
1284                         return blkio_read_blkg_stats(blkcg, cft, cb,
1285                                         BLKIO_STAT_GROUP_WAIT_TIME, 0, 0);
1286                 case BLKIO_PROP_idle_time:
1287                         return blkio_read_blkg_stats(blkcg, cft, cb,
1288                                                 BLKIO_STAT_IDLE_TIME, 0, 0);
1289                 case BLKIO_PROP_empty_time:
1290                         return blkio_read_blkg_stats(blkcg, cft, cb,
1291                                                 BLKIO_STAT_EMPTY_TIME, 0, 0);
1292 #endif
1293                 default:
1294                         BUG();
1295                 }
1296                 break;
1297         case BLKIO_POLICY_THROTL:
1298                 switch(name){
1299                 case BLKIO_THROTL_io_service_bytes:
1300                         return blkio_read_blkg_stats(blkcg, cft, cb,
1301                                                 BLKIO_STAT_CPU_SERVICE_BYTES, 1, 1);
1302                 case BLKIO_THROTL_io_serviced:
1303                         return blkio_read_blkg_stats(blkcg, cft, cb,
1304                                                 BLKIO_STAT_CPU_SERVICED, 1, 1);
1305                 default:
1306                         BUG();
1307                 }
1308                 break;
1309         default:
1310                 BUG();
1311         }
1312
1313         return 0;
1314 }
1315
1316 static int blkio_weight_write(struct blkio_cgroup *blkcg, u64 val)
1317 {
1318         struct blkio_group *blkg;
1319         struct hlist_node *n;
1320         struct blkio_policy_node *pn;
1321
1322         if (val < BLKIO_WEIGHT_MIN || val > BLKIO_WEIGHT_MAX)
1323                 return -EINVAL;
1324
1325         spin_lock(&blkio_list_lock);
1326         spin_lock_irq(&blkcg->lock);
1327         blkcg->weight = (unsigned int)val;
1328
1329         hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
1330                 pn = blkio_policy_search_node(blkcg, blkg->dev,
1331                                 BLKIO_POLICY_PROP, BLKIO_PROP_weight_device);
1332                 if (pn)
1333                         continue;
1334
1335                 blkio_update_group_weight(blkg, blkcg->weight);
1336         }
1337         spin_unlock_irq(&blkcg->lock);
1338         spin_unlock(&blkio_list_lock);
1339         return 0;
1340 }
1341
1342 static u64 blkiocg_file_read_u64 (struct cgroup *cgrp, struct cftype *cft) {
1343         struct blkio_cgroup *blkcg;
1344         enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private);
1345         int name = BLKIOFILE_ATTR(cft->private);
1346
1347         blkcg = cgroup_to_blkio_cgroup(cgrp);
1348
1349         switch(plid) {
1350         case BLKIO_POLICY_PROP:
1351                 switch(name) {
1352                 case BLKIO_PROP_weight:
1353                         return (u64)blkcg->weight;
1354                 }
1355                 break;
1356         default:
1357                 BUG();
1358         }
1359         return 0;
1360 }
1361
1362 static int
1363 blkiocg_file_write_u64(struct cgroup *cgrp, struct cftype *cft, u64 val)
1364 {
1365         struct blkio_cgroup *blkcg;
1366         enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private);
1367         int name = BLKIOFILE_ATTR(cft->private);
1368
1369         blkcg = cgroup_to_blkio_cgroup(cgrp);
1370
1371         switch(plid) {
1372         case BLKIO_POLICY_PROP:
1373                 switch(name) {
1374                 case BLKIO_PROP_weight:
1375                         return blkio_weight_write(blkcg, val);
1376                 }
1377                 break;
1378         default:
1379                 BUG();
1380         }
1381
1382         return 0;
1383 }
1384
1385 struct cftype blkio_files[] = {
1386         {
1387                 .name = "weight_device",
1388                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1389                                 BLKIO_PROP_weight_device),
1390                 .read_seq_string = blkiocg_file_read,
1391                 .write_string = blkiocg_file_write,
1392                 .max_write_len = 256,
1393         },
1394         {
1395                 .name = "weight",
1396                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1397                                 BLKIO_PROP_weight),
1398                 .read_u64 = blkiocg_file_read_u64,
1399                 .write_u64 = blkiocg_file_write_u64,
1400         },
1401         {
1402                 .name = "time",
1403                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1404                                 BLKIO_PROP_time),
1405                 .read_map = blkiocg_file_read_map,
1406         },
1407         {
1408                 .name = "sectors",
1409                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1410                                 BLKIO_PROP_sectors),
1411                 .read_map = blkiocg_file_read_map,
1412         },
1413         {
1414                 .name = "io_service_bytes",
1415                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1416                                 BLKIO_PROP_io_service_bytes),
1417                 .read_map = blkiocg_file_read_map,
1418         },
1419         {
1420                 .name = "io_serviced",
1421                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1422                                 BLKIO_PROP_io_serviced),
1423                 .read_map = blkiocg_file_read_map,
1424         },
1425         {
1426                 .name = "io_service_time",
1427                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1428                                 BLKIO_PROP_io_service_time),
1429                 .read_map = blkiocg_file_read_map,
1430         },
1431         {
1432                 .name = "io_wait_time",
1433                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1434                                 BLKIO_PROP_io_wait_time),
1435                 .read_map = blkiocg_file_read_map,
1436         },
1437         {
1438                 .name = "io_merged",
1439                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1440                                 BLKIO_PROP_io_merged),
1441                 .read_map = blkiocg_file_read_map,
1442         },
1443         {
1444                 .name = "io_queued",
1445                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1446                                 BLKIO_PROP_io_queued),
1447                 .read_map = blkiocg_file_read_map,
1448         },
1449         {
1450                 .name = "reset_stats",
1451                 .write_u64 = blkiocg_reset_stats,
1452         },
1453 #ifdef CONFIG_BLK_DEV_THROTTLING
1454         {
1455                 .name = "throttle.read_bps_device",
1456                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL,
1457                                 BLKIO_THROTL_read_bps_device),
1458                 .read_seq_string = blkiocg_file_read,
1459                 .write_string = blkiocg_file_write,
1460                 .max_write_len = 256,
1461         },
1462
1463         {
1464                 .name = "throttle.write_bps_device",
1465                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL,
1466                                 BLKIO_THROTL_write_bps_device),
1467                 .read_seq_string = blkiocg_file_read,
1468                 .write_string = blkiocg_file_write,
1469                 .max_write_len = 256,
1470         },
1471
1472         {
1473                 .name = "throttle.read_iops_device",
1474                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL,
1475                                 BLKIO_THROTL_read_iops_device),
1476                 .read_seq_string = blkiocg_file_read,
1477                 .write_string = blkiocg_file_write,
1478                 .max_write_len = 256,
1479         },
1480
1481         {
1482                 .name = "throttle.write_iops_device",
1483                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL,
1484                                 BLKIO_THROTL_write_iops_device),
1485                 .read_seq_string = blkiocg_file_read,
1486                 .write_string = blkiocg_file_write,
1487                 .max_write_len = 256,
1488         },
1489         {
1490                 .name = "throttle.io_service_bytes",
1491                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL,
1492                                 BLKIO_THROTL_io_service_bytes),
1493                 .read_map = blkiocg_file_read_map,
1494         },
1495         {
1496                 .name = "throttle.io_serviced",
1497                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL,
1498                                 BLKIO_THROTL_io_serviced),
1499                 .read_map = blkiocg_file_read_map,
1500         },
1501 #endif /* CONFIG_BLK_DEV_THROTTLING */
1502
1503 #ifdef CONFIG_DEBUG_BLK_CGROUP
1504         {
1505                 .name = "avg_queue_size",
1506                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1507                                 BLKIO_PROP_avg_queue_size),
1508                 .read_map = blkiocg_file_read_map,
1509         },
1510         {
1511                 .name = "group_wait_time",
1512                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1513                                 BLKIO_PROP_group_wait_time),
1514                 .read_map = blkiocg_file_read_map,
1515         },
1516         {
1517                 .name = "idle_time",
1518                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1519                                 BLKIO_PROP_idle_time),
1520                 .read_map = blkiocg_file_read_map,
1521         },
1522         {
1523                 .name = "empty_time",
1524                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1525                                 BLKIO_PROP_empty_time),
1526                 .read_map = blkiocg_file_read_map,
1527         },
1528         {
1529                 .name = "dequeue",
1530                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1531                                 BLKIO_PROP_dequeue),
1532                 .read_map = blkiocg_file_read_map,
1533         },
1534         {
1535                 .name = "unaccounted_time",
1536                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1537                                 BLKIO_PROP_unaccounted_time),
1538                 .read_map = blkiocg_file_read_map,
1539         },
1540 #endif
1541 };
1542
1543 static int blkiocg_populate(struct cgroup_subsys *subsys, struct cgroup *cgroup)
1544 {
1545         return cgroup_add_files(cgroup, subsys, blkio_files,
1546                                 ARRAY_SIZE(blkio_files));
1547 }
1548
1549 static void blkiocg_destroy(struct cgroup_subsys *subsys, struct cgroup *cgroup)
1550 {
1551         struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup);
1552         unsigned long flags;
1553         struct blkio_group *blkg;
1554         void *key;
1555         struct blkio_policy_type *blkiop;
1556         struct blkio_policy_node *pn, *pntmp;
1557
1558         rcu_read_lock();
1559         do {
1560                 spin_lock_irqsave(&blkcg->lock, flags);
1561
1562                 if (hlist_empty(&blkcg->blkg_list)) {
1563                         spin_unlock_irqrestore(&blkcg->lock, flags);
1564                         break;
1565                 }
1566
1567                 blkg = hlist_entry(blkcg->blkg_list.first, struct blkio_group,
1568                                         blkcg_node);
1569                 key = rcu_dereference(blkg->key);
1570                 __blkiocg_del_blkio_group(blkg);
1571
1572                 spin_unlock_irqrestore(&blkcg->lock, flags);
1573
1574                 /*
1575                  * This blkio_group is being unlinked as associated cgroup is
1576                  * going away. Let all the IO controlling policies know about
1577                  * this event.
1578                  */
1579                 spin_lock(&blkio_list_lock);
1580                 list_for_each_entry(blkiop, &blkio_list, list) {
1581                         if (blkiop->plid != blkg->plid)
1582                                 continue;
1583                         blkiop->ops.blkio_unlink_group_fn(key, blkg);
1584                 }
1585                 spin_unlock(&blkio_list_lock);
1586         } while (1);
1587
1588         list_for_each_entry_safe(pn, pntmp, &blkcg->policy_list, node) {
1589                 blkio_policy_delete_node(pn);
1590                 kfree(pn);
1591         }
1592
1593         free_css_id(&blkio_subsys, &blkcg->css);
1594         rcu_read_unlock();
1595         if (blkcg != &blkio_root_cgroup)
1596                 kfree(blkcg);
1597 }
1598
1599 static struct cgroup_subsys_state *
1600 blkiocg_create(struct cgroup_subsys *subsys, struct cgroup *cgroup)
1601 {
1602         struct blkio_cgroup *blkcg;
1603         struct cgroup *parent = cgroup->parent;
1604
1605         if (!parent) {
1606                 blkcg = &blkio_root_cgroup;
1607                 goto done;
1608         }
1609
1610         blkcg = kzalloc(sizeof(*blkcg), GFP_KERNEL);
1611         if (!blkcg)
1612                 return ERR_PTR(-ENOMEM);
1613
1614         blkcg->weight = BLKIO_WEIGHT_DEFAULT;
1615 done:
1616         spin_lock_init(&blkcg->lock);
1617         INIT_HLIST_HEAD(&blkcg->blkg_list);
1618
1619         INIT_LIST_HEAD(&blkcg->policy_list);
1620         return &blkcg->css;
1621 }
1622
1623 /*
1624  * We cannot support shared io contexts, as we have no mean to support
1625  * two tasks with the same ioc in two different groups without major rework
1626  * of the main cic data structures.  For now we allow a task to change
1627  * its cgroup only if it's the only owner of its ioc.
1628  */
1629 static int blkiocg_can_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
1630 {
1631         struct io_context *ioc;
1632         int ret = 0;
1633
1634         /* task_lock() is needed to avoid races with exit_io_context() */
1635         task_lock(tsk);
1636         ioc = tsk->io_context;
1637         if (ioc && atomic_read(&ioc->nr_tasks) > 1)
1638                 ret = -EINVAL;
1639         task_unlock(tsk);
1640
1641         return ret;
1642 }
1643
1644 static void blkiocg_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
1645 {
1646         struct io_context *ioc;
1647
1648         /* we don't lose anything even if ioc allocation fails */
1649         ioc = get_task_io_context(tsk, GFP_ATOMIC, NUMA_NO_NODE);
1650         if (ioc) {
1651                 ioc->cgroup_changed = 1;
1652                 put_io_context(ioc);
1653         }
1654 }
1655
1656 void blkio_policy_register(struct blkio_policy_type *blkiop)
1657 {
1658         spin_lock(&blkio_list_lock);
1659         list_add_tail(&blkiop->list, &blkio_list);
1660         spin_unlock(&blkio_list_lock);
1661 }
1662 EXPORT_SYMBOL_GPL(blkio_policy_register);
1663
1664 void blkio_policy_unregister(struct blkio_policy_type *blkiop)
1665 {
1666         spin_lock(&blkio_list_lock);
1667         list_del_init(&blkiop->list);
1668         spin_unlock(&blkio_list_lock);
1669 }
1670 EXPORT_SYMBOL_GPL(blkio_policy_unregister);
1671
1672 static int __init init_cgroup_blkio(void)
1673 {
1674         return cgroup_load_subsys(&blkio_subsys);
1675 }
1676
1677 static void __exit exit_cgroup_blkio(void)
1678 {
1679         cgroup_unload_subsys(&blkio_subsys);
1680 }
1681
1682 module_init(init_cgroup_blkio);
1683 module_exit(exit_cgroup_blkio);
1684 MODULE_LICENSE("GPL");