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 <linux/genhd.h>
  21 #include <linux/delay.h>
  22 #include "blk-cgroup.h"
  23
  24 #define MAX_KEY_LEN 100
  25
  26 static DEFINE_SPINLOCK(blkio_list_lock);
  27 static LIST_HEAD(blkio_list);
  28
  29 struct blkio_cgroup blkio_root_cgroup = { .weight = 2*BLKIO_WEIGHT_DEFAULT };
  30 EXPORT_SYMBOL_GPL(blkio_root_cgroup);
  31
  32 static struct blkio_policy_type *blkio_policy[BLKIO_NR_POLICIES];
  33
  34 static struct cgroup_subsys_state *blkiocg_create(struct cgroup_subsys *,
  35                                                   struct cgroup *);
  36 static int blkiocg_can_attach(struct cgroup_subsys *, struct cgroup *,
  37                               struct cgroup_taskset *);
  38 static void blkiocg_attach(struct cgroup_subsys *, struct cgroup *,
  39                            struct cgroup_taskset *);
  40 static void blkiocg_destroy(struct cgroup_subsys *, struct cgroup *);
  41 static int blkiocg_populate(struct cgroup_subsys *, struct cgroup *);
  42
  43 /* for encoding cft->private value on file */
  44 #define BLKIOFILE_PRIVATE(x, val)       (((x) << 16) | (val))
  45 /* What policy owns the file, proportional or throttle */
  46 #define BLKIOFILE_POLICY(val)           (((val) >> 16) & 0xffff)
  47 #define BLKIOFILE_ATTR(val)             ((val) & 0xffff)
  48
  49 struct cgroup_subsys blkio_subsys = {
  50         .name = "blkio",
  51         .create = blkiocg_create,
  52         .can_attach = blkiocg_can_attach,
  53         .attach = blkiocg_attach,
  54         .destroy = blkiocg_destroy,
  55         .populate = blkiocg_populate,
  56         .subsys_id = blkio_subsys_id,
  57         .use_id = 1,
  58         .module = THIS_MODULE,
  59 };
  60 EXPORT_SYMBOL_GPL(blkio_subsys);
  61
  62 static inline void blkio_policy_insert_node(struct blkio_cgroup *blkcg,
  63                                             struct blkio_policy_node *pn)
  64 {
  65         list_add(&pn->node, &blkcg->policy_list);
  66 }
  67
  68 static inline bool cftype_blkg_same_policy(struct cftype *cft,
  69                         struct blkio_group *blkg)
  70 {
  71         enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private);
  72
  73         if (blkg->plid == plid)
  74                 return 1;
  75
  76         return 0;
  77 }
  78
  79 /* Determines if policy node matches cgroup file being accessed */
  80 static inline bool pn_matches_cftype(struct cftype *cft,
  81                         struct blkio_policy_node *pn)
  82 {
  83         enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private);
  84         int fileid = BLKIOFILE_ATTR(cft->private);
  85
  86         return (plid == pn->plid && fileid == pn->fileid);
  87 }
  88
  89 /* Must be called with blkcg->lock held */
  90 static inline void blkio_policy_delete_node(struct blkio_policy_node *pn)
  91 {
  92         list_del(&pn->node);
  93 }
  94
  95 /* Must be called with blkcg->lock held */
  96 static struct blkio_policy_node *
  97 blkio_policy_search_node(const struct blkio_cgroup *blkcg, dev_t dev,
  98                 enum blkio_policy_id plid, int fileid)
  99 {
 100         struct blkio_policy_node *pn;
 101
 102         list_for_each_entry(pn, &blkcg->policy_list, node) {
 103                 if (pn->dev == dev && pn->plid == plid && pn->fileid == fileid)
 104                         return pn;
 105         }
 106
 107         return NULL;
 108 }
 109
 110 struct blkio_cgroup *cgroup_to_blkio_cgroup(struct cgroup *cgroup)
 111 {
 112         return container_of(cgroup_subsys_state(cgroup, blkio_subsys_id),
 113                             struct blkio_cgroup, css);
 114 }
 115 EXPORT_SYMBOL_GPL(cgroup_to_blkio_cgroup);
 116
 117 struct blkio_cgroup *task_blkio_cgroup(struct task_struct *tsk)
 118 {
 119         return container_of(task_subsys_state(tsk, blkio_subsys_id),
 120                             struct blkio_cgroup, css);
 121 }
 122 EXPORT_SYMBOL_GPL(task_blkio_cgroup);
 123
 124 static inline void
 125 blkio_update_group_weight(struct blkio_group *blkg, unsigned int weight)
 126 {
 127         struct blkio_policy_type *blkiop;
 128
 129         list_for_each_entry(blkiop, &blkio_list, list) {
 130                 /* If this policy does not own the blkg, do not send updates */
 131                 if (blkiop->plid != blkg->plid)
 132                         continue;
 133                 if (blkiop->ops.blkio_update_group_weight_fn)
 134                         blkiop->ops.blkio_update_group_weight_fn(blkg->q,
 135                                                         blkg, weight);
 136         }
 137 }
 138
 139 static inline void blkio_update_group_bps(struct blkio_group *blkg, u64 bps,
 140                                 int fileid)
 141 {
 142         struct blkio_policy_type *blkiop;
 143
 144         list_for_each_entry(blkiop, &blkio_list, list) {
 145
 146                 /* If this policy does not own the blkg, do not send updates */
 147                 if (blkiop->plid != blkg->plid)
 148                         continue;
 149
 150                 if (fileid == BLKIO_THROTL_read_bps_device
 151                     && blkiop->ops.blkio_update_group_read_bps_fn)
 152                         blkiop->ops.blkio_update_group_read_bps_fn(blkg->q,
 153                                                                 blkg, bps);
 154
 155                 if (fileid == BLKIO_THROTL_write_bps_device
 156                     && blkiop->ops.blkio_update_group_write_bps_fn)
 157                         blkiop->ops.blkio_update_group_write_bps_fn(blkg->q,
 158                                                                 blkg, bps);
 159         }
 160 }
 161
 162 static inline void blkio_update_group_iops(struct blkio_group *blkg,
 163                         unsigned int iops, int fileid)
 164 {
 165         struct blkio_policy_type *blkiop;
 166
 167         list_for_each_entry(blkiop, &blkio_list, list) {
 168
 169                 /* If this policy does not own the blkg, do not send updates */
 170                 if (blkiop->plid != blkg->plid)
 171                         continue;
 172
 173                 if (fileid == BLKIO_THROTL_read_iops_device
 174                     && blkiop->ops.blkio_update_group_read_iops_fn)
 175                         blkiop->ops.blkio_update_group_read_iops_fn(blkg->q,
 176                                                                 blkg, iops);
 177
 178                 if (fileid == BLKIO_THROTL_write_iops_device
 179                     && blkiop->ops.blkio_update_group_write_iops_fn)
 180                         blkiop->ops.blkio_update_group_write_iops_fn(blkg->q,
 181                                                                 blkg,iops);
 182         }
 183 }
 184
 185 /*
 186  * Add to the appropriate stat variable depending on the request type.
 187  * This should be called with the blkg->stats_lock held.
 188  */
 189 static void blkio_add_stat(uint64_t *stat, uint64_t add, bool direction,
 190                                 bool sync)
 191 {
 192         if (direction)
 193                 stat[BLKIO_STAT_WRITE] += add;
 194         else
 195                 stat[BLKIO_STAT_READ] += add;
 196         if (sync)
 197                 stat[BLKIO_STAT_SYNC] += add;
 198         else
 199                 stat[BLKIO_STAT_ASYNC] += add;
 200 }
 201
 202 /*
 203  * Decrements the appropriate stat variable if non-zero depending on the
 204  * request type. Panics on value being zero.
 205  * This should be called with the blkg->stats_lock held.
 206  */
 207 static void blkio_check_and_dec_stat(uint64_t *stat, bool direction, bool sync)
 208 {
 209         if (direction) {
 210                 BUG_ON(stat[BLKIO_STAT_WRITE] == 0);
 211                 stat[BLKIO_STAT_WRITE]--;
 212         } else {
 213                 BUG_ON(stat[BLKIO_STAT_READ] == 0);
 214                 stat[BLKIO_STAT_READ]--;
 215         }
 216         if (sync) {
 217                 BUG_ON(stat[BLKIO_STAT_SYNC] == 0);
 218                 stat[BLKIO_STAT_SYNC]--;
 219         } else {
 220                 BUG_ON(stat[BLKIO_STAT_ASYNC] == 0);
 221                 stat[BLKIO_STAT_ASYNC]--;
 222         }
 223 }
 224
 225 #ifdef CONFIG_DEBUG_BLK_CGROUP
 226 /* This should be called with the blkg->stats_lock held. */
 227 static void blkio_set_start_group_wait_time(struct blkio_group *blkg,
 228                                                 struct blkio_group *curr_blkg)
 229 {
 230         if (blkio_blkg_waiting(&blkg->stats))
 231                 return;
 232         if (blkg == curr_blkg)
 233                 return;
 234         blkg->stats.start_group_wait_time = sched_clock();
 235         blkio_mark_blkg_waiting(&blkg->stats);
 236 }
 237
 238 /* This should be called with the blkg->stats_lock held. */
 239 static void blkio_update_group_wait_time(struct blkio_group_stats *stats)
 240 {
 241         unsigned long long now;
 242
 243         if (!blkio_blkg_waiting(stats))
 244                 return;
 245
 246         now = sched_clock();
 247         if (time_after64(now, stats->start_group_wait_time))
 248                 stats->group_wait_time += now - stats->start_group_wait_time;
 249         blkio_clear_blkg_waiting(stats);
 250 }
 251
 252 /* This should be called with the blkg->stats_lock held. */
 253 static void blkio_end_empty_time(struct blkio_group_stats *stats)
 254 {
 255         unsigned long long now;
 256
 257         if (!blkio_blkg_empty(stats))
 258                 return;
 259
 260         now = sched_clock();
 261         if (time_after64(now, stats->start_empty_time))
 262                 stats->empty_time += now - stats->start_empty_time;
 263         blkio_clear_blkg_empty(stats);
 264 }
 265
 266 void blkiocg_update_set_idle_time_stats(struct blkio_group *blkg)
 267 {
 268         unsigned long flags;
 269
 270         spin_lock_irqsave(&blkg->stats_lock, flags);
 271         BUG_ON(blkio_blkg_idling(&blkg->stats));
 272         blkg->stats.start_idle_time = sched_clock();
 273         blkio_mark_blkg_idling(&blkg->stats);
 274         spin_unlock_irqrestore(&blkg->stats_lock, flags);
 275 }
 276 EXPORT_SYMBOL_GPL(blkiocg_update_set_idle_time_stats);
 277
 278 void blkiocg_update_idle_time_stats(struct blkio_group *blkg)
 279 {
 280         unsigned long flags;
 281         unsigned long long now;
 282         struct blkio_group_stats *stats;
 283
 284         spin_lock_irqsave(&blkg->stats_lock, flags);
 285         stats = &blkg->stats;
 286         if (blkio_blkg_idling(stats)) {
 287                 now = sched_clock();
 288                 if (time_after64(now, stats->start_idle_time))
 289                         stats->idle_time += now - stats->start_idle_time;
 290                 blkio_clear_blkg_idling(stats);
 291         }
 292         spin_unlock_irqrestore(&blkg->stats_lock, flags);
 293 }
 294 EXPORT_SYMBOL_GPL(blkiocg_update_idle_time_stats);
 295
 296 void blkiocg_update_avg_queue_size_stats(struct blkio_group *blkg)
 297 {
 298         unsigned long flags;
 299         struct blkio_group_stats *stats;
 300
 301         spin_lock_irqsave(&blkg->stats_lock, flags);
 302         stats = &blkg->stats;
 303         stats->avg_queue_size_sum +=
 304                         stats->stat_arr[BLKIO_STAT_QUEUED][BLKIO_STAT_READ] +
 305                         stats->stat_arr[BLKIO_STAT_QUEUED][BLKIO_STAT_WRITE];
 306         stats->avg_queue_size_samples++;
 307         blkio_update_group_wait_time(stats);
 308         spin_unlock_irqrestore(&blkg->stats_lock, flags);
 309 }
 310 EXPORT_SYMBOL_GPL(blkiocg_update_avg_queue_size_stats);
 311
 312 void blkiocg_set_start_empty_time(struct blkio_group *blkg)
 313 {
 314         unsigned long flags;
 315         struct blkio_group_stats *stats;
 316
 317         spin_lock_irqsave(&blkg->stats_lock, flags);
 318         stats = &blkg->stats;
 319
 320         if (stats->stat_arr[BLKIO_STAT_QUEUED][BLKIO_STAT_READ] ||
 321                         stats->stat_arr[BLKIO_STAT_QUEUED][BLKIO_STAT_WRITE]) {
 322                 spin_unlock_irqrestore(&blkg->stats_lock, flags);
 323                 return;
 324         }
 325
 326         /*
 327          * group is already marked empty. This can happen if cfqq got new
 328          * request in parent group and moved to this group while being added
 329          * to service tree. Just ignore the event and move on.
 330          */
 331         if(blkio_blkg_empty(stats)) {
 332                 spin_unlock_irqrestore(&blkg->stats_lock, flags);
 333                 return;
 334         }
 335
 336         stats->start_empty_time = sched_clock();
 337         blkio_mark_blkg_empty(stats);
 338         spin_unlock_irqrestore(&blkg->stats_lock, flags);
 339 }
 340 EXPORT_SYMBOL_GPL(blkiocg_set_start_empty_time);
 341
 342 void blkiocg_update_dequeue_stats(struct blkio_group *blkg,
 343                         unsigned long dequeue)
 344 {
 345         blkg->stats.dequeue += dequeue;
 346 }
 347 EXPORT_SYMBOL_GPL(blkiocg_update_dequeue_stats);
 348 #else
 349 static inline void blkio_set_start_group_wait_time(struct blkio_group *blkg,
 350                                         struct blkio_group *curr_blkg) {}
 351 static inline void blkio_end_empty_time(struct blkio_group_stats *stats) {}
 352 #endif
 353
 354 void blkiocg_update_io_add_stats(struct blkio_group *blkg,
 355                         struct blkio_group *curr_blkg, bool direction,
 356                         bool sync)
 357 {
 358         unsigned long flags;
 359
 360         spin_lock_irqsave(&blkg->stats_lock, flags);
 361         blkio_add_stat(blkg->stats.stat_arr[BLKIO_STAT_QUEUED], 1, direction,
 362                         sync);
 363         blkio_end_empty_time(&blkg->stats);
 364         blkio_set_start_group_wait_time(blkg, curr_blkg);
 365         spin_unlock_irqrestore(&blkg->stats_lock, flags);
 366 }
 367 EXPORT_SYMBOL_GPL(blkiocg_update_io_add_stats);
 368
 369 void blkiocg_update_io_remove_stats(struct blkio_group *blkg,
 370                                                 bool direction, bool sync)
 371 {
 372         unsigned long flags;
 373
 374         spin_lock_irqsave(&blkg->stats_lock, flags);
 375         blkio_check_and_dec_stat(blkg->stats.stat_arr[BLKIO_STAT_QUEUED],
 376                                         direction, sync);
 377         spin_unlock_irqrestore(&blkg->stats_lock, flags);
 378 }
 379 EXPORT_SYMBOL_GPL(blkiocg_update_io_remove_stats);
 380
 381 void blkiocg_update_timeslice_used(struct blkio_group *blkg, unsigned long time,
 382                                 unsigned long unaccounted_time)
 383 {
 384         unsigned long flags;
 385
 386         spin_lock_irqsave(&blkg->stats_lock, flags);
 387         blkg->stats.time += time;
 388 #ifdef CONFIG_DEBUG_BLK_CGROUP
 389         blkg->stats.unaccounted_time += unaccounted_time;
 390 #endif
 391         spin_unlock_irqrestore(&blkg->stats_lock, flags);
 392 }
 393 EXPORT_SYMBOL_GPL(blkiocg_update_timeslice_used);
 394
 395 /*
 396  * should be called under rcu read lock or queue lock to make sure blkg pointer
 397  * is valid.
 398  */
 399 void blkiocg_update_dispatch_stats(struct blkio_group *blkg,
 400                                 uint64_t bytes, bool direction, bool sync)
 401 {
 402         struct blkio_group_stats_cpu *stats_cpu;
 403         unsigned long flags;
 404
 405         /*
 406          * Disabling interrupts to provide mutual exclusion between two
 407          * writes on same cpu. It probably is not needed for 64bit. Not
 408          * optimizing that case yet.
 409          */
 410         local_irq_save(flags);
 411
 412         stats_cpu = this_cpu_ptr(blkg->stats_cpu);
 413
 414         u64_stats_update_begin(&stats_cpu->syncp);
 415         stats_cpu->sectors += bytes >> 9;
 416         blkio_add_stat(stats_cpu->stat_arr_cpu[BLKIO_STAT_CPU_SERVICED],
 417                         1, direction, sync);
 418         blkio_add_stat(stats_cpu->stat_arr_cpu[BLKIO_STAT_CPU_SERVICE_BYTES],
 419                         bytes, direction, sync);
 420         u64_stats_update_end(&stats_cpu->syncp);
 421         local_irq_restore(flags);
 422 }
 423 EXPORT_SYMBOL_GPL(blkiocg_update_dispatch_stats);
 424
 425 void blkiocg_update_completion_stats(struct blkio_group *blkg,
 426         uint64_t start_time, uint64_t io_start_time, bool direction, bool sync)
 427 {
 428         struct blkio_group_stats *stats;
 429         unsigned long flags;
 430         unsigned long long now = sched_clock();
 431
 432         spin_lock_irqsave(&blkg->stats_lock, flags);
 433         stats = &blkg->stats;
 434         if (time_after64(now, io_start_time))
 435                 blkio_add_stat(stats->stat_arr[BLKIO_STAT_SERVICE_TIME],
 436                                 now - io_start_time, direction, sync);
 437         if (time_after64(io_start_time, start_time))
 438                 blkio_add_stat(stats->stat_arr[BLKIO_STAT_WAIT_TIME],
 439                                 io_start_time - start_time, direction, sync);
 440         spin_unlock_irqrestore(&blkg->stats_lock, flags);
 441 }
 442 EXPORT_SYMBOL_GPL(blkiocg_update_completion_stats);
 443
 444 /*  Merged stats are per cpu.  */
 445 void blkiocg_update_io_merged_stats(struct blkio_group *blkg, bool direction,
 446                                         bool sync)
 447 {
 448         struct blkio_group_stats_cpu *stats_cpu;
 449         unsigned long flags;
 450
 451         /*
 452          * Disabling interrupts to provide mutual exclusion between two
 453          * writes on same cpu. It probably is not needed for 64bit. Not
 454          * optimizing that case yet.
 455          */
 456         local_irq_save(flags);
 457
 458         stats_cpu = this_cpu_ptr(blkg->stats_cpu);
 459
 460         u64_stats_update_begin(&stats_cpu->syncp);
 461         blkio_add_stat(stats_cpu->stat_arr_cpu[BLKIO_STAT_CPU_MERGED], 1,
 462                                 direction, sync);
 463         u64_stats_update_end(&stats_cpu->syncp);
 464         local_irq_restore(flags);
 465 }
 466 EXPORT_SYMBOL_GPL(blkiocg_update_io_merged_stats);
 467
 468 /*
 469  * This function allocates the per cpu stats for blkio_group. Should be called
 470  * from sleepable context as alloc_per_cpu() requires that.
 471  */
 472 int blkio_alloc_blkg_stats(struct blkio_group *blkg)
 473 {
 474         /* Allocate memory for per cpu stats */
 475         blkg->stats_cpu = alloc_percpu(struct blkio_group_stats_cpu);
 476         if (!blkg->stats_cpu)
 477                 return -ENOMEM;
 478         return 0;
 479 }
 480 EXPORT_SYMBOL_GPL(blkio_alloc_blkg_stats);
 481
 482 void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg,
 483                 struct blkio_group *blkg, struct request_queue *q, dev_t dev,
 484                 enum blkio_policy_id plid)
 485 {
 486         unsigned long flags;
 487
 488         spin_lock_irqsave(&blkcg->lock, flags);
 489         spin_lock_init(&blkg->stats_lock);
 490         rcu_assign_pointer(blkg->q, q);
 491         blkg->blkcg_id = css_id(&blkcg->css);
 492         hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list);
 493         blkg->plid = plid;
 494         spin_unlock_irqrestore(&blkcg->lock, flags);
 495         /* Need to take css reference ? */
 496         cgroup_path(blkcg->css.cgroup, blkg->path, sizeof(blkg->path));
 497         blkg->dev = dev;
 498 }
 499 EXPORT_SYMBOL_GPL(blkiocg_add_blkio_group);
 500
 501 static void __blkiocg_del_blkio_group(struct blkio_group *blkg)
 502 {
 503         hlist_del_init_rcu(&blkg->blkcg_node);
 504         blkg->blkcg_id = 0;
 505 }
 506
 507 /*
 508  * returns 0 if blkio_group was still on cgroup list. Otherwise returns 1
 509  * indicating that blk_group was unhashed by the time we got to it.
 510  */
 511 int blkiocg_del_blkio_group(struct blkio_group *blkg)
 512 {
 513         struct blkio_cgroup *blkcg;
 514         unsigned long flags;
 515         struct cgroup_subsys_state *css;
 516         int ret = 1;
 517
 518         rcu_read_lock();
 519         css = css_lookup(&blkio_subsys, blkg->blkcg_id);
 520         if (css) {
 521                 blkcg = container_of(css, struct blkio_cgroup, css);
 522                 spin_lock_irqsave(&blkcg->lock, flags);
 523                 if (!hlist_unhashed(&blkg->blkcg_node)) {
 524                         __blkiocg_del_blkio_group(blkg);
 525                         ret = 0;
 526                 }
 527                 spin_unlock_irqrestore(&blkcg->lock, flags);
 528         }
 529
 530         rcu_read_unlock();
 531         return ret;
 532 }
 533 EXPORT_SYMBOL_GPL(blkiocg_del_blkio_group);
 534
 535 /* called under rcu_read_lock(). */
 536 struct blkio_group *blkiocg_lookup_group(struct blkio_cgroup *blkcg,
 537                                          struct request_queue *q,
 538                                          enum blkio_policy_id plid)
 539 {
 540         struct blkio_group *blkg;
 541         struct hlist_node *n;
 542
 543         hlist_for_each_entry_rcu(blkg, n, &blkcg->blkg_list, blkcg_node)
 544                 if (blkg->q == q && blkg->plid == plid)
 545                         return blkg;
 546         return NULL;
 547 }
 548 EXPORT_SYMBOL_GPL(blkiocg_lookup_group);
 549
 550 void blkg_destroy_all(struct request_queue *q)
 551 {
 552         struct blkio_policy_type *pol;
 553
 554         while (true) {
 555                 bool done = true;
 556
 557                 spin_lock(&blkio_list_lock);
 558                 spin_lock_irq(q->queue_lock);
 559
 560                 /*
 561                  * clear_queue_fn() might return with non-empty group list
 562                  * if it raced cgroup removal and lost.  cgroup removal is
 563                  * guaranteed to make forward progress and retrying after a
 564                  * while is enough.  This ugliness is scheduled to be
 565                  * removed after locking update.
 566                  */
 567                 list_for_each_entry(pol, &blkio_list, list)
 568                         if (!pol->ops.blkio_clear_queue_fn(q))
 569                                 done = false;
 570
 571                 spin_unlock_irq(q->queue_lock);
 572                 spin_unlock(&blkio_list_lock);
 573
 574                 if (done)
 575                         break;
 576
 577                 msleep(10);     /* just some random duration I like */
 578         }
 579 }
 580
 581 static void blkio_reset_stats_cpu(struct blkio_group *blkg)
 582 {
 583         struct blkio_group_stats_cpu *stats_cpu;
 584         int i, j, k;
 585         /*
 586          * Note: On 64 bit arch this should not be an issue. This has the
 587          * possibility of returning some inconsistent value on 32bit arch
 588          * as 64bit update on 32bit is non atomic. Taking care of this
 589          * corner case makes code very complicated, like sending IPIs to
 590          * cpus, taking care of stats of offline cpus etc.
 591          *
 592          * reset stats is anyway more of a debug feature and this sounds a
 593          * corner case. So I am not complicating the code yet until and
 594          * unless this becomes a real issue.
 595          */
 596         for_each_possible_cpu(i) {
 597                 stats_cpu = per_cpu_ptr(blkg->stats_cpu, i);
 598                 stats_cpu->sectors = 0;
 599                 for(j = 0; j < BLKIO_STAT_CPU_NR; j++)
 600                         for (k = 0; k < BLKIO_STAT_TOTAL; k++)
 601                                 stats_cpu->stat_arr_cpu[j][k] = 0;
 602         }
 603 }
 604
 605 static int
 606 blkiocg_reset_stats(struct cgroup *cgroup, struct cftype *cftype, u64 val)
 607 {
 608         struct blkio_cgroup *blkcg;
 609         struct blkio_group *blkg;
 610         struct blkio_group_stats *stats;
 611         struct hlist_node *n;
 612         uint64_t queued[BLKIO_STAT_TOTAL];
 613         int i;
 614 #ifdef CONFIG_DEBUG_BLK_CGROUP
 615         bool idling, waiting, empty;
 616         unsigned long long now = sched_clock();
 617 #endif
 618
 619         blkcg = cgroup_to_blkio_cgroup(cgroup);
 620         spin_lock_irq(&blkcg->lock);
 621         hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
 622                 spin_lock(&blkg->stats_lock);
 623                 stats = &blkg->stats;
 624 #ifdef CONFIG_DEBUG_BLK_CGROUP
 625                 idling = blkio_blkg_idling(stats);
 626                 waiting = blkio_blkg_waiting(stats);
 627                 empty = blkio_blkg_empty(stats);
 628 #endif
 629                 for (i = 0; i < BLKIO_STAT_TOTAL; i++)
 630                         queued[i] = stats->stat_arr[BLKIO_STAT_QUEUED][i];
 631                 memset(stats, 0, sizeof(struct blkio_group_stats));
 632                 for (i = 0; i < BLKIO_STAT_TOTAL; i++)
 633                         stats->stat_arr[BLKIO_STAT_QUEUED][i] = queued[i];
 634 #ifdef CONFIG_DEBUG_BLK_CGROUP
 635                 if (idling) {
 636                         blkio_mark_blkg_idling(stats);
 637                         stats->start_idle_time = now;
 638                 }
 639                 if (waiting) {
 640                         blkio_mark_blkg_waiting(stats);
 641                         stats->start_group_wait_time = now;
 642                 }
 643                 if (empty) {
 644                         blkio_mark_blkg_empty(stats);
 645                         stats->start_empty_time = now;
 646                 }
 647 #endif
 648                 spin_unlock(&blkg->stats_lock);
 649
 650                 /* Reset Per cpu stats which don't take blkg->stats_lock */
 651                 blkio_reset_stats_cpu(blkg);
 652         }
 653
 654         spin_unlock_irq(&blkcg->lock);
 655         return 0;
 656 }
 657
 658 static void blkio_get_key_name(enum stat_sub_type type, dev_t dev, char *str,
 659                                 int chars_left, bool diskname_only)
 660 {
 661         snprintf(str, chars_left, "%d:%d", MAJOR(dev), MINOR(dev));
 662         chars_left -= strlen(str);
 663         if (chars_left <= 0) {
 664                 printk(KERN_WARNING
 665                         "Possibly incorrect cgroup stat display format");
 666                 return;
 667         }
 668         if (diskname_only)
 669                 return;
 670         switch (type) {
 671         case BLKIO_STAT_READ:
 672                 strlcat(str, " Read", chars_left);
 673                 break;
 674         case BLKIO_STAT_WRITE:
 675                 strlcat(str, " Write", chars_left);
 676                 break;
 677         case BLKIO_STAT_SYNC:
 678                 strlcat(str, " Sync", chars_left);
 679                 break;
 680         case BLKIO_STAT_ASYNC:
 681                 strlcat(str, " Async", chars_left);
 682                 break;
 683         case BLKIO_STAT_TOTAL:
 684                 strlcat(str, " Total", chars_left);
 685                 break;
 686         default:
 687                 strlcat(str, " Invalid", chars_left);
 688         }
 689 }
 690
 691 static uint64_t blkio_fill_stat(char *str, int chars_left, uint64_t val,
 692                                 struct cgroup_map_cb *cb, dev_t dev)
 693 {
 694         blkio_get_key_name(0, dev, str, chars_left, true);
 695         cb->fill(cb, str, val);
 696         return val;
 697 }
 698
 699
 700 static uint64_t blkio_read_stat_cpu(struct blkio_group *blkg,
 701                         enum stat_type_cpu type, enum stat_sub_type sub_type)
 702 {
 703         int cpu;
 704         struct blkio_group_stats_cpu *stats_cpu;
 705         u64 val = 0, tval;
 706
 707         for_each_possible_cpu(cpu) {
 708                 unsigned int start;
 709                 stats_cpu  = per_cpu_ptr(blkg->stats_cpu, cpu);
 710
 711                 do {
 712                         start = u64_stats_fetch_begin(&stats_cpu->syncp);
 713                         if (type == BLKIO_STAT_CPU_SECTORS)
 714                                 tval = stats_cpu->sectors;
 715                         else
 716                                 tval = stats_cpu->stat_arr_cpu[type][sub_type];
 717                 } while(u64_stats_fetch_retry(&stats_cpu->syncp, start));
 718
 719                 val += tval;
 720         }
 721
 722         return val;
 723 }
 724
 725 static uint64_t blkio_get_stat_cpu(struct blkio_group *blkg,
 726                 struct cgroup_map_cb *cb, dev_t dev, enum stat_type_cpu type)
 727 {
 728         uint64_t disk_total, val;
 729         char key_str[MAX_KEY_LEN];
 730         enum stat_sub_type sub_type;
 731
 732         if (type == BLKIO_STAT_CPU_SECTORS) {
 733                 val = blkio_read_stat_cpu(blkg, type, 0);
 734                 return blkio_fill_stat(key_str, MAX_KEY_LEN - 1, val, cb, dev);
 735         }
 736
 737         for (sub_type = BLKIO_STAT_READ; sub_type < BLKIO_STAT_TOTAL;
 738                         sub_type++) {
 739                 blkio_get_key_name(sub_type, dev, key_str, MAX_KEY_LEN, false);
 740                 val = blkio_read_stat_cpu(blkg, type, sub_type);
 741                 cb->fill(cb, key_str, val);
 742         }
 743
 744         disk_total = blkio_read_stat_cpu(blkg, type, BLKIO_STAT_READ) +
 745                         blkio_read_stat_cpu(blkg, type, BLKIO_STAT_WRITE);
 746
 747         blkio_get_key_name(BLKIO_STAT_TOTAL, dev, key_str, MAX_KEY_LEN, false);
 748         cb->fill(cb, key_str, disk_total);
 749         return disk_total;
 750 }
 751
 752 /* This should be called with blkg->stats_lock held */
 753 static uint64_t blkio_get_stat(struct blkio_group *blkg,
 754                 struct cgroup_map_cb *cb, dev_t dev, enum stat_type type)
 755 {
 756         uint64_t disk_total;
 757         char key_str[MAX_KEY_LEN];
 758         enum stat_sub_type sub_type;
 759
 760         if (type == BLKIO_STAT_TIME)
 761                 return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
 762                                         blkg->stats.time, cb, dev);
 763 #ifdef CONFIG_DEBUG_BLK_CGROUP
 764         if (type == BLKIO_STAT_UNACCOUNTED_TIME)
 765                 return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
 766                                         blkg->stats.unaccounted_time, cb, dev);
 767         if (type == BLKIO_STAT_AVG_QUEUE_SIZE) {
 768                 uint64_t sum = blkg->stats.avg_queue_size_sum;
 769                 uint64_t samples = blkg->stats.avg_queue_size_samples;
 770                 if (samples)
 771                         do_div(sum, samples);
 772                 else
 773                         sum = 0;
 774                 return blkio_fill_stat(key_str, MAX_KEY_LEN - 1, sum, cb, dev);
 775         }
 776         if (type == BLKIO_STAT_GROUP_WAIT_TIME)
 777                 return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
 778                                         blkg->stats.group_wait_time, cb, dev);
 779         if (type == BLKIO_STAT_IDLE_TIME)
 780                 return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
 781                                         blkg->stats.idle_time, cb, dev);
 782         if (type == BLKIO_STAT_EMPTY_TIME)
 783                 return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
 784                                         blkg->stats.empty_time, cb, dev);
 785         if (type == BLKIO_STAT_DEQUEUE)
 786                 return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
 787                                         blkg->stats.dequeue, cb, dev);
 788 #endif
 789
 790         for (sub_type = BLKIO_STAT_READ; sub_type < BLKIO_STAT_TOTAL;
 791                         sub_type++) {
 792                 blkio_get_key_name(sub_type, dev, key_str, MAX_KEY_LEN, false);
 793                 cb->fill(cb, key_str, blkg->stats.stat_arr[type][sub_type]);
 794         }
 795         disk_total = blkg->stats.stat_arr[type][BLKIO_STAT_READ] +
 796                         blkg->stats.stat_arr[type][BLKIO_STAT_WRITE];
 797         blkio_get_key_name(BLKIO_STAT_TOTAL, dev, key_str, MAX_KEY_LEN, false);
 798         cb->fill(cb, key_str, disk_total);
 799         return disk_total;
 800 }
 801
 802 static int blkio_policy_parse_and_set(char *buf,
 803         struct blkio_policy_node *newpn, enum blkio_policy_id plid, int fileid)
 804 {
 805         struct gendisk *disk = NULL;
 806         char *s[4], *p, *major_s = NULL, *minor_s = NULL;
 807         unsigned long major, minor;
 808         int i = 0, ret = -EINVAL;
 809         int part;
 810         dev_t dev;
 811         u64 temp;
 812
 813         memset(s, 0, sizeof(s));
 814
 815         while ((p = strsep(&buf, " ")) != NULL) {
 816                 if (!*p)
 817                         continue;
 818
 819                 s[i++] = p;
 820
 821                 /* Prevent from inputing too many things */
 822                 if (i == 3)
 823                         break;
 824         }
 825
 826         if (i != 2)
 827                 goto out;
 828
 829         p = strsep(&s[0], ":");
 830         if (p != NULL)
 831                 major_s = p;
 832         else
 833                 goto out;
 834
 835         minor_s = s[0];
 836         if (!minor_s)
 837                 goto out;
 838
 839         if (strict_strtoul(major_s, 10, &major))
 840                 goto out;
 841
 842         if (strict_strtoul(minor_s, 10, &minor))
 843                 goto out;
 844
 845         dev = MKDEV(major, minor);
 846
 847         if (strict_strtoull(s[1], 10, &temp))
 848                 goto out;
 849
 850         /* For rule removal, do not check for device presence. */
 851         if (temp) {
 852                 disk = get_gendisk(dev, &part);
 853                 if (!disk || part) {
 854                         ret = -ENODEV;
 855                         goto out;
 856                 }
 857         }
 858
 859         newpn->dev = dev;
 860
 861         switch (plid) {
 862         case BLKIO_POLICY_PROP:
 863                 if ((temp < BLKIO_WEIGHT_MIN && temp > 0) ||
 864                      temp > BLKIO_WEIGHT_MAX)
 865                         goto out;
 866
 867                 newpn->plid = plid;
 868                 newpn->fileid = fileid;
 869                 newpn->val.weight = temp;
 870                 break;
 871         case BLKIO_POLICY_THROTL:
 872                 switch(fileid) {
 873                 case BLKIO_THROTL_read_bps_device:
 874                 case BLKIO_THROTL_write_bps_device:
 875                         newpn->plid = plid;
 876                         newpn->fileid = fileid;
 877                         newpn->val.bps = temp;
 878                         break;
 879                 case BLKIO_THROTL_read_iops_device:
 880                 case BLKIO_THROTL_write_iops_device:
 881                         if (temp > THROTL_IOPS_MAX)
 882                                 goto out;
 883
 884                         newpn->plid = plid;
 885                         newpn->fileid = fileid;
 886                         newpn->val.iops = (unsigned int)temp;
 887                         break;
 888                 }
 889                 break;
 890         default:
 891                 BUG();
 892         }
 893         ret = 0;
 894 out:
 895         put_disk(disk);
 896         return ret;
 897 }
 898
 899 unsigned int blkcg_get_weight(struct blkio_cgroup *blkcg,
 900                               dev_t dev)
 901 {
 902         struct blkio_policy_node *pn;
 903         unsigned long flags;
 904         unsigned int weight;
 905
 906         spin_lock_irqsave(&blkcg->lock, flags);
 907
 908         pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_PROP,
 909                                 BLKIO_PROP_weight_device);
 910         if (pn)
 911                 weight = pn->val.weight;
 912         else
 913                 weight = blkcg->weight;
 914
 915         spin_unlock_irqrestore(&blkcg->lock, flags);
 916
 917         return weight;
 918 }
 919 EXPORT_SYMBOL_GPL(blkcg_get_weight);
 920
 921 uint64_t blkcg_get_read_bps(struct blkio_cgroup *blkcg, dev_t dev)
 922 {
 923         struct blkio_policy_node *pn;
 924         unsigned long flags;
 925         uint64_t bps = -1;
 926
 927         spin_lock_irqsave(&blkcg->lock, flags);
 928         pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_THROTL,
 929                                 BLKIO_THROTL_read_bps_device);
 930         if (pn)
 931                 bps = pn->val.bps;
 932         spin_unlock_irqrestore(&blkcg->lock, flags);
 933
 934         return bps;
 935 }
 936
 937 uint64_t blkcg_get_write_bps(struct blkio_cgroup *blkcg, dev_t dev)
 938 {
 939         struct blkio_policy_node *pn;
 940         unsigned long flags;
 941         uint64_t bps = -1;
 942
 943         spin_lock_irqsave(&blkcg->lock, flags);
 944         pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_THROTL,
 945                                 BLKIO_THROTL_write_bps_device);
 946         if (pn)
 947                 bps = pn->val.bps;
 948         spin_unlock_irqrestore(&blkcg->lock, flags);
 949
 950         return bps;
 951 }
 952
 953 unsigned int blkcg_get_read_iops(struct blkio_cgroup *blkcg, dev_t dev)
 954 {
 955         struct blkio_policy_node *pn;
 956         unsigned long flags;
 957         unsigned int iops = -1;
 958
 959         spin_lock_irqsave(&blkcg->lock, flags);
 960         pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_THROTL,
 961                                 BLKIO_THROTL_read_iops_device);
 962         if (pn)
 963                 iops = pn->val.iops;
 964         spin_unlock_irqrestore(&blkcg->lock, flags);
 965
 966         return iops;
 967 }
 968
 969 unsigned int blkcg_get_write_iops(struct blkio_cgroup *blkcg, dev_t dev)
 970 {
 971         struct blkio_policy_node *pn;
 972         unsigned long flags;
 973         unsigned int iops = -1;
 974
 975         spin_lock_irqsave(&blkcg->lock, flags);
 976         pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_THROTL,
 977                                 BLKIO_THROTL_write_iops_device);
 978         if (pn)
 979                 iops = pn->val.iops;
 980         spin_unlock_irqrestore(&blkcg->lock, flags);
 981
 982         return iops;
 983 }
 984
 985 /* Checks whether user asked for deleting a policy rule */
 986 static bool blkio_delete_rule_command(struct blkio_policy_node *pn)
 987 {
 988         switch(pn->plid) {
 989         case BLKIO_POLICY_PROP:
 990                 if (pn->val.weight == 0)
 991                         return 1;
 992                 break;
 993         case BLKIO_POLICY_THROTL:
 994                 switch(pn->fileid) {
 995                 case BLKIO_THROTL_read_bps_device:
 996                 case BLKIO_THROTL_write_bps_device:
 997                         if (pn->val.bps == 0)
 998                                 return 1;
 999                         break;
1000                 case BLKIO_THROTL_read_iops_device:
1001                 case BLKIO_THROTL_write_iops_device:
1002                         if (pn->val.iops == 0)
1003                                 return 1;
1004                 }
1005                 break;
1006         default:
1007                 BUG();
1008         }
1009
1010         return 0;
1011 }
1012
1013 static void blkio_update_policy_rule(struct blkio_policy_node *oldpn,
1014                                         struct blkio_policy_node *newpn)
1015 {
1016         switch(oldpn->plid) {
1017         case BLKIO_POLICY_PROP:
1018                 oldpn->val.weight = newpn->val.weight;
1019                 break;
1020         case BLKIO_POLICY_THROTL:
1021                 switch(newpn->fileid) {
1022                 case BLKIO_THROTL_read_bps_device:
1023                 case BLKIO_THROTL_write_bps_device:
1024                         oldpn->val.bps = newpn->val.bps;
1025                         break;
1026                 case BLKIO_THROTL_read_iops_device:
1027                 case BLKIO_THROTL_write_iops_device:
1028                         oldpn->val.iops = newpn->val.iops;
1029                 }
1030                 break;
1031         default:
1032                 BUG();
1033         }
1034 }
1035
1036 /*
1037  * Some rules/values in blkg have changed. Propagate those to respective
1038  * policies.
1039  */
1040 static void blkio_update_blkg_policy(struct blkio_cgroup *blkcg,
1041                 struct blkio_group *blkg, struct blkio_policy_node *pn)
1042 {
1043         unsigned int weight, iops;
1044         u64 bps;
1045
1046         switch(pn->plid) {
1047         case BLKIO_POLICY_PROP:
1048                 weight = pn->val.weight ? pn->val.weight :
1049                                 blkcg->weight;
1050                 blkio_update_group_weight(blkg, weight);
1051                 break;
1052         case BLKIO_POLICY_THROTL:
1053                 switch(pn->fileid) {
1054                 case BLKIO_THROTL_read_bps_device:
1055                 case BLKIO_THROTL_write_bps_device:
1056                         bps = pn->val.bps ? pn->val.bps : (-1);
1057                         blkio_update_group_bps(blkg, bps, pn->fileid);
1058                         break;
1059                 case BLKIO_THROTL_read_iops_device:
1060                 case BLKIO_THROTL_write_iops_device:
1061                         iops = pn->val.iops ? pn->val.iops : (-1);
1062                         blkio_update_group_iops(blkg, iops, pn->fileid);
1063                         break;
1064                 }
1065                 break;
1066         default:
1067                 BUG();
1068         }
1069 }
1070
1071 /*
1072  * A policy node rule has been updated. Propagate this update to all the
1073  * block groups which might be affected by this update.
1074  */
1075 static void blkio_update_policy_node_blkg(struct blkio_cgroup *blkcg,
1076                                 struct blkio_policy_node *pn)
1077 {
1078         struct blkio_group *blkg;
1079         struct hlist_node *n;
1080
1081         spin_lock(&blkio_list_lock);
1082         spin_lock_irq(&blkcg->lock);
1083
1084         hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
1085                 if (pn->dev != blkg->dev || pn->plid != blkg->plid)
1086                         continue;
1087                 blkio_update_blkg_policy(blkcg, blkg, pn);
1088         }
1089
1090         spin_unlock_irq(&blkcg->lock);
1091         spin_unlock(&blkio_list_lock);
1092 }
1093
1094 static int blkiocg_file_write(struct cgroup *cgrp, struct cftype *cft,
1095                                        const char *buffer)
1096 {
1097         int ret = 0;
1098         char *buf;
1099         struct blkio_policy_node *newpn, *pn;
1100         struct blkio_cgroup *blkcg;
1101         int keep_newpn = 0;
1102         enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private);
1103         int fileid = BLKIOFILE_ATTR(cft->private);
1104
1105         buf = kstrdup(buffer, GFP_KERNEL);
1106         if (!buf)
1107                 return -ENOMEM;
1108
1109         newpn = kzalloc(sizeof(*newpn), GFP_KERNEL);
1110         if (!newpn) {
1111                 ret = -ENOMEM;
1112                 goto free_buf;
1113         }
1114
1115         ret = blkio_policy_parse_and_set(buf, newpn, plid, fileid);
1116         if (ret)
1117                 goto free_newpn;
1118
1119         blkcg = cgroup_to_blkio_cgroup(cgrp);
1120
1121         spin_lock_irq(&blkcg->lock);
1122
1123         pn = blkio_policy_search_node(blkcg, newpn->dev, plid, fileid);
1124         if (!pn) {
1125                 if (!blkio_delete_rule_command(newpn)) {
1126                         blkio_policy_insert_node(blkcg, newpn);
1127                         keep_newpn = 1;
1128                 }
1129                 spin_unlock_irq(&blkcg->lock);
1130                 goto update_io_group;
1131         }
1132
1133         if (blkio_delete_rule_command(newpn)) {
1134                 blkio_policy_delete_node(pn);
1135                 kfree(pn);
1136                 spin_unlock_irq(&blkcg->lock);
1137                 goto update_io_group;
1138         }
1139         spin_unlock_irq(&blkcg->lock);
1140
1141         blkio_update_policy_rule(pn, newpn);
1142
1143 update_io_group:
1144         blkio_update_policy_node_blkg(blkcg, newpn);
1145
1146 free_newpn:
1147         if (!keep_newpn)
1148                 kfree(newpn);
1149 free_buf:
1150         kfree(buf);
1151         return ret;
1152 }
1153
1154 static void
1155 blkio_print_policy_node(struct seq_file *m, struct blkio_policy_node *pn)
1156 {
1157         switch(pn->plid) {
1158                 case BLKIO_POLICY_PROP:
1159                         if (pn->fileid == BLKIO_PROP_weight_device)
1160                                 seq_printf(m, "%u:%u\t%u\n", MAJOR(pn->dev),
1161                                         MINOR(pn->dev), pn->val.weight);
1162                         break;
1163                 case BLKIO_POLICY_THROTL:
1164                         switch(pn->fileid) {
1165                         case BLKIO_THROTL_read_bps_device:
1166                         case BLKIO_THROTL_write_bps_device:
1167                                 seq_printf(m, "%u:%u\t%llu\n", MAJOR(pn->dev),
1168                                         MINOR(pn->dev), pn->val.bps);
1169                                 break;
1170                         case BLKIO_THROTL_read_iops_device:
1171                         case BLKIO_THROTL_write_iops_device:
1172                                 seq_printf(m, "%u:%u\t%u\n", MAJOR(pn->dev),
1173                                         MINOR(pn->dev), pn->val.iops);
1174                                 break;
1175                         }
1176                         break;
1177                 default:
1178                         BUG();
1179         }
1180 }
1181
1182 /* cgroup files which read their data from policy nodes end up here */
1183 static void blkio_read_policy_node_files(struct cftype *cft,
1184                         struct blkio_cgroup *blkcg, struct seq_file *m)
1185 {
1186         struct blkio_policy_node *pn;
1187
1188         if (!list_empty(&blkcg->policy_list)) {
1189                 spin_lock_irq(&blkcg->lock);
1190                 list_for_each_entry(pn, &blkcg->policy_list, node) {
1191                         if (!pn_matches_cftype(cft, pn))
1192                                 continue;
1193                         blkio_print_policy_node(m, pn);
1194                 }
1195                 spin_unlock_irq(&blkcg->lock);
1196         }
1197 }
1198
1199 static int blkiocg_file_read(struct cgroup *cgrp, struct cftype *cft,
1200                                 struct seq_file *m)
1201 {
1202         struct blkio_cgroup *blkcg;
1203         enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private);
1204         int name = BLKIOFILE_ATTR(cft->private);
1205
1206         blkcg = cgroup_to_blkio_cgroup(cgrp);
1207
1208         switch(plid) {
1209         case BLKIO_POLICY_PROP:
1210                 switch(name) {
1211                 case BLKIO_PROP_weight_device:
1212                         blkio_read_policy_node_files(cft, blkcg, m);
1213                         return 0;
1214                 default:
1215                         BUG();
1216                 }
1217                 break;
1218         case BLKIO_POLICY_THROTL:
1219                 switch(name){
1220                 case BLKIO_THROTL_read_bps_device:
1221                 case BLKIO_THROTL_write_bps_device:
1222                 case BLKIO_THROTL_read_iops_device:
1223                 case BLKIO_THROTL_write_iops_device:
1224                         blkio_read_policy_node_files(cft, blkcg, m);
1225                         return 0;
1226                 default:
1227                         BUG();
1228                 }
1229                 break;
1230         default:
1231                 BUG();
1232         }
1233
1234         return 0;
1235 }
1236
1237 static int blkio_read_blkg_stats(struct blkio_cgroup *blkcg,
1238                 struct cftype *cft, struct cgroup_map_cb *cb,
1239                 enum stat_type type, bool show_total, bool pcpu)
1240 {
1241         struct blkio_group *blkg;
1242         struct hlist_node *n;
1243         uint64_t cgroup_total = 0;
1244
1245         rcu_read_lock();
1246         hlist_for_each_entry_rcu(blkg, n, &blkcg->blkg_list, blkcg_node) {
1247                 if (blkg->dev) {
1248                         if (!cftype_blkg_same_policy(cft, blkg))
1249                                 continue;
1250                         if (pcpu)
1251                                 cgroup_total += blkio_get_stat_cpu(blkg, cb,
1252                                                 blkg->dev, type);
1253                         else {
1254                                 spin_lock_irq(&blkg->stats_lock);
1255                                 cgroup_total += blkio_get_stat(blkg, cb,
1256                                                 blkg->dev, type);
1257                                 spin_unlock_irq(&blkg->stats_lock);
1258                         }
1259                 }
1260         }
1261         if (show_total)
1262                 cb->fill(cb, "Total", cgroup_total);
1263         rcu_read_unlock();
1264         return 0;
1265 }
1266
1267 /* All map kind of cgroup file get serviced by this function */
1268 static int blkiocg_file_read_map(struct cgroup *cgrp, struct cftype *cft,
1269                                 struct cgroup_map_cb *cb)
1270 {
1271         struct blkio_cgroup *blkcg;
1272         enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private);
1273         int name = BLKIOFILE_ATTR(cft->private);
1274
1275         blkcg = cgroup_to_blkio_cgroup(cgrp);
1276
1277         switch(plid) {
1278         case BLKIO_POLICY_PROP:
1279                 switch(name) {
1280                 case BLKIO_PROP_time:
1281                         return blkio_read_blkg_stats(blkcg, cft, cb,
1282                                                 BLKIO_STAT_TIME, 0, 0);
1283                 case BLKIO_PROP_sectors:
1284                         return blkio_read_blkg_stats(blkcg, cft, cb,
1285                                                 BLKIO_STAT_CPU_SECTORS, 0, 1);
1286                 case BLKIO_PROP_io_service_bytes:
1287                         return blkio_read_blkg_stats(blkcg, cft, cb,
1288                                         BLKIO_STAT_CPU_SERVICE_BYTES, 1, 1);
1289                 case BLKIO_PROP_io_serviced:
1290                         return blkio_read_blkg_stats(blkcg, cft, cb,
1291                                                 BLKIO_STAT_CPU_SERVICED, 1, 1);
1292                 case BLKIO_PROP_io_service_time:
1293                         return blkio_read_blkg_stats(blkcg, cft, cb,
1294                                                 BLKIO_STAT_SERVICE_TIME, 1, 0);
1295                 case BLKIO_PROP_io_wait_time:
1296                         return blkio_read_blkg_stats(blkcg, cft, cb,
1297                                                 BLKIO_STAT_WAIT_TIME, 1, 0);
1298                 case BLKIO_PROP_io_merged:
1299                         return blkio_read_blkg_stats(blkcg, cft, cb,
1300                                                 BLKIO_STAT_CPU_MERGED, 1, 1);
1301                 case BLKIO_PROP_io_queued:
1302                         return blkio_read_blkg_stats(blkcg, cft, cb,
1303                                                 BLKIO_STAT_QUEUED, 1, 0);
1304 #ifdef CONFIG_DEBUG_BLK_CGROUP
1305                 case BLKIO_PROP_unaccounted_time:
1306                         return blkio_read_blkg_stats(blkcg, cft, cb,
1307                                         BLKIO_STAT_UNACCOUNTED_TIME, 0, 0);
1308                 case BLKIO_PROP_dequeue:
1309                         return blkio_read_blkg_stats(blkcg, cft, cb,
1310                                                 BLKIO_STAT_DEQUEUE, 0, 0);
1311                 case BLKIO_PROP_avg_queue_size:
1312                         return blkio_read_blkg_stats(blkcg, cft, cb,
1313                                         BLKIO_STAT_AVG_QUEUE_SIZE, 0, 0);
1314                 case BLKIO_PROP_group_wait_time:
1315                         return blkio_read_blkg_stats(blkcg, cft, cb,
1316                                         BLKIO_STAT_GROUP_WAIT_TIME, 0, 0);
1317                 case BLKIO_PROP_idle_time:
1318                         return blkio_read_blkg_stats(blkcg, cft, cb,
1319                                                 BLKIO_STAT_IDLE_TIME, 0, 0);
1320                 case BLKIO_PROP_empty_time:
1321                         return blkio_read_blkg_stats(blkcg, cft, cb,
1322                                                 BLKIO_STAT_EMPTY_TIME, 0, 0);
1323 #endif
1324                 default:
1325                         BUG();
1326                 }
1327                 break;
1328         case BLKIO_POLICY_THROTL:
1329                 switch(name){
1330                 case BLKIO_THROTL_io_service_bytes:
1331                         return blkio_read_blkg_stats(blkcg, cft, cb,
1332                                                 BLKIO_STAT_CPU_SERVICE_BYTES, 1, 1);
1333                 case BLKIO_THROTL_io_serviced:
1334                         return blkio_read_blkg_stats(blkcg, cft, cb,
1335                                                 BLKIO_STAT_CPU_SERVICED, 1, 1);
1336                 default:
1337                         BUG();
1338                 }
1339                 break;
1340         default:
1341                 BUG();
1342         }
1343
1344         return 0;
1345 }
1346
1347 static int blkio_weight_write(struct blkio_cgroup *blkcg, u64 val)
1348 {
1349         struct blkio_group *blkg;
1350         struct hlist_node *n;
1351         struct blkio_policy_node *pn;
1352
1353         if (val < BLKIO_WEIGHT_MIN || val > BLKIO_WEIGHT_MAX)
1354                 return -EINVAL;
1355
1356         spin_lock(&blkio_list_lock);
1357         spin_lock_irq(&blkcg->lock);
1358         blkcg->weight = (unsigned int)val;
1359
1360         hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
1361                 pn = blkio_policy_search_node(blkcg, blkg->dev,
1362                                 BLKIO_POLICY_PROP, BLKIO_PROP_weight_device);
1363                 if (pn)
1364                         continue;
1365
1366                 blkio_update_group_weight(blkg, blkcg->weight);
1367         }
1368         spin_unlock_irq(&blkcg->lock);
1369         spin_unlock(&blkio_list_lock);
1370         return 0;
1371 }
1372
1373 static u64 blkiocg_file_read_u64 (struct cgroup *cgrp, struct cftype *cft) {
1374         struct blkio_cgroup *blkcg;
1375         enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private);
1376         int name = BLKIOFILE_ATTR(cft->private);
1377
1378         blkcg = cgroup_to_blkio_cgroup(cgrp);
1379
1380         switch(plid) {
1381         case BLKIO_POLICY_PROP:
1382                 switch(name) {
1383                 case BLKIO_PROP_weight:
1384                         return (u64)blkcg->weight;
1385                 }
1386                 break;
1387         default:
1388                 BUG();
1389         }
1390         return 0;
1391 }
1392
1393 static int
1394 blkiocg_file_write_u64(struct cgroup *cgrp, struct cftype *cft, u64 val)
1395 {
1396         struct blkio_cgroup *blkcg;
1397         enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private);
1398         int name = BLKIOFILE_ATTR(cft->private);
1399
1400         blkcg = cgroup_to_blkio_cgroup(cgrp);
1401
1402         switch(plid) {
1403         case BLKIO_POLICY_PROP:
1404                 switch(name) {
1405                 case BLKIO_PROP_weight:
1406                         return blkio_weight_write(blkcg, val);
1407                 }
1408                 break;
1409         default:
1410                 BUG();
1411         }
1412
1413         return 0;
1414 }
1415
1416 struct cftype blkio_files[] = {
1417         {
1418                 .name = "weight_device",
1419                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1420                                 BLKIO_PROP_weight_device),
1421                 .read_seq_string = blkiocg_file_read,
1422                 .write_string = blkiocg_file_write,
1423                 .max_write_len = 256,
1424         },
1425         {
1426                 .name = "weight",
1427                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1428                                 BLKIO_PROP_weight),
1429                 .read_u64 = blkiocg_file_read_u64,
1430                 .write_u64 = blkiocg_file_write_u64,
1431         },
1432         {
1433                 .name = "time",
1434                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1435                                 BLKIO_PROP_time),
1436                 .read_map = blkiocg_file_read_map,
1437         },
1438         {
1439                 .name = "sectors",
1440                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1441                                 BLKIO_PROP_sectors),
1442                 .read_map = blkiocg_file_read_map,
1443         },
1444         {
1445                 .name = "io_service_bytes",
1446                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1447                                 BLKIO_PROP_io_service_bytes),
1448                 .read_map = blkiocg_file_read_map,
1449         },
1450         {
1451                 .name = "io_serviced",
1452                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1453                                 BLKIO_PROP_io_serviced),
1454                 .read_map = blkiocg_file_read_map,
1455         },
1456         {
1457                 .name = "io_service_time",
1458                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1459                                 BLKIO_PROP_io_service_time),
1460                 .read_map = blkiocg_file_read_map,
1461         },
1462         {
1463                 .name = "io_wait_time",
1464                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1465                                 BLKIO_PROP_io_wait_time),
1466                 .read_map = blkiocg_file_read_map,
1467         },
1468         {
1469                 .name = "io_merged",
1470                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1471                                 BLKIO_PROP_io_merged),
1472                 .read_map = blkiocg_file_read_map,
1473         },
1474         {
1475                 .name = "io_queued",
1476                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1477                                 BLKIO_PROP_io_queued),
1478                 .read_map = blkiocg_file_read_map,
1479         },
1480         {
1481                 .name = "reset_stats",
1482                 .write_u64 = blkiocg_reset_stats,
1483         },
1484 #ifdef CONFIG_BLK_DEV_THROTTLING
1485         {
1486                 .name = "throttle.read_bps_device",
1487                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL,
1488                                 BLKIO_THROTL_read_bps_device),
1489                 .read_seq_string = blkiocg_file_read,
1490                 .write_string = blkiocg_file_write,
1491                 .max_write_len = 256,
1492         },
1493
1494         {
1495                 .name = "throttle.write_bps_device",
1496                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL,
1497                                 BLKIO_THROTL_write_bps_device),
1498                 .read_seq_string = blkiocg_file_read,
1499                 .write_string = blkiocg_file_write,
1500                 .max_write_len = 256,
1501         },
1502
1503         {
1504                 .name = "throttle.read_iops_device",
1505                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL,
1506                                 BLKIO_THROTL_read_iops_device),
1507                 .read_seq_string = blkiocg_file_read,
1508                 .write_string = blkiocg_file_write,
1509                 .max_write_len = 256,
1510         },
1511
1512         {
1513                 .name = "throttle.write_iops_device",
1514                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL,
1515                                 BLKIO_THROTL_write_iops_device),
1516                 .read_seq_string = blkiocg_file_read,
1517                 .write_string = blkiocg_file_write,
1518                 .max_write_len = 256,
1519         },
1520         {
1521                 .name = "throttle.io_service_bytes",
1522                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL,
1523                                 BLKIO_THROTL_io_service_bytes),
1524                 .read_map = blkiocg_file_read_map,
1525         },
1526         {
1527                 .name = "throttle.io_serviced",
1528                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL,
1529                                 BLKIO_THROTL_io_serviced),
1530                 .read_map = blkiocg_file_read_map,
1531         },
1532 #endif /* CONFIG_BLK_DEV_THROTTLING */
1533
1534 #ifdef CONFIG_DEBUG_BLK_CGROUP
1535         {
1536                 .name = "avg_queue_size",
1537                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1538                                 BLKIO_PROP_avg_queue_size),
1539                 .read_map = blkiocg_file_read_map,
1540         },
1541         {
1542                 .name = "group_wait_time",
1543                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1544                                 BLKIO_PROP_group_wait_time),
1545                 .read_map = blkiocg_file_read_map,
1546         },
1547         {
1548                 .name = "idle_time",
1549                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1550                                 BLKIO_PROP_idle_time),
1551                 .read_map = blkiocg_file_read_map,
1552         },
1553         {
1554                 .name = "empty_time",
1555                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1556                                 BLKIO_PROP_empty_time),
1557                 .read_map = blkiocg_file_read_map,
1558         },
1559         {
1560                 .name = "dequeue",
1561                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1562                                 BLKIO_PROP_dequeue),
1563                 .read_map = blkiocg_file_read_map,
1564         },
1565         {
1566                 .name = "unaccounted_time",
1567                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1568                                 BLKIO_PROP_unaccounted_time),
1569                 .read_map = blkiocg_file_read_map,
1570         },
1571 #endif
1572 };
1573
1574 static int blkiocg_populate(struct cgroup_subsys *subsys, struct cgroup *cgroup)
1575 {
1576         return cgroup_add_files(cgroup, subsys, blkio_files,
1577                                 ARRAY_SIZE(blkio_files));
1578 }
1579
1580 static void blkiocg_destroy(struct cgroup_subsys *subsys, struct cgroup *cgroup)
1581 {
1582         struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup);
1583         unsigned long flags;
1584         struct blkio_group *blkg;
1585         struct request_queue *q;
1586         struct blkio_policy_type *blkiop;
1587         struct blkio_policy_node *pn, *pntmp;
1588
1589         rcu_read_lock();
1590         do {
1591                 spin_lock_irqsave(&blkcg->lock, flags);
1592
1593                 if (hlist_empty(&blkcg->blkg_list)) {
1594                         spin_unlock_irqrestore(&blkcg->lock, flags);
1595                         break;
1596                 }
1597
1598                 blkg = hlist_entry(blkcg->blkg_list.first, struct blkio_group,
1599                                         blkcg_node);
1600                 q = rcu_dereference(blkg->q);
1601                 __blkiocg_del_blkio_group(blkg);
1602
1603                 spin_unlock_irqrestore(&blkcg->lock, flags);
1604
1605                 /*
1606                  * This blkio_group is being unlinked as associated cgroup is
1607                  * going away. Let all the IO controlling policies know about
1608                  * this event.
1609                  */
1610                 spin_lock(&blkio_list_lock);
1611                 list_for_each_entry(blkiop, &blkio_list, list) {
1612                         if (blkiop->plid != blkg->plid)
1613                                 continue;
1614                         blkiop->ops.blkio_unlink_group_fn(q, blkg);
1615                 }
1616                 spin_unlock(&blkio_list_lock);
1617         } while (1);
1618
1619         list_for_each_entry_safe(pn, pntmp, &blkcg->policy_list, node) {
1620                 blkio_policy_delete_node(pn);
1621                 kfree(pn);
1622         }
1623
1624         free_css_id(&blkio_subsys, &blkcg->css);
1625         rcu_read_unlock();
1626         if (blkcg != &blkio_root_cgroup)
1627                 kfree(blkcg);
1628 }
1629
1630 static struct cgroup_subsys_state *
1631 blkiocg_create(struct cgroup_subsys *subsys, struct cgroup *cgroup)
1632 {
1633         struct blkio_cgroup *blkcg;
1634         struct cgroup *parent = cgroup->parent;
1635
1636         if (!parent) {
1637                 blkcg = &blkio_root_cgroup;
1638                 goto done;
1639         }
1640
1641         blkcg = kzalloc(sizeof(*blkcg), GFP_KERNEL);
1642         if (!blkcg)
1643                 return ERR_PTR(-ENOMEM);
1644
1645         blkcg->weight = BLKIO_WEIGHT_DEFAULT;
1646 done:
1647         spin_lock_init(&blkcg->lock);
1648         INIT_HLIST_HEAD(&blkcg->blkg_list);
1649
1650         INIT_LIST_HEAD(&blkcg->policy_list);
1651         return &blkcg->css;
1652 }
1653
1654 /*
1655  * We cannot support shared io contexts, as we have no mean to support
1656  * two tasks with the same ioc in two different groups without major rework
1657  * of the main cic data structures.  For now we allow a task to change
1658  * its cgroup only if it's the only owner of its ioc.
1659  */
1660 static int blkiocg_can_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
1661                               struct cgroup_taskset *tset)
1662 {
1663         struct task_struct *task;
1664         struct io_context *ioc;
1665         int ret = 0;
1666
1667         /* task_lock() is needed to avoid races with exit_io_context() */
1668         cgroup_taskset_for_each(task, cgrp, tset) {
1669                 task_lock(task);
1670                 ioc = task->io_context;
1671                 if (ioc && atomic_read(&ioc->nr_tasks) > 1)
1672                         ret = -EINVAL;
1673                 task_unlock(task);
1674                 if (ret)
1675                         break;
1676         }
1677         return ret;
1678 }
1679
1680 static void blkiocg_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
1681                            struct cgroup_taskset *tset)
1682 {
1683         struct task_struct *task;
1684         struct io_context *ioc;
1685
1686         cgroup_taskset_for_each(task, cgrp, tset) {
1687                 /* we don't lose anything even if ioc allocation fails */
1688                 ioc = get_task_io_context(task, GFP_ATOMIC, NUMA_NO_NODE);
1689                 if (ioc) {
1690                         ioc_cgroup_changed(ioc);
1691                         put_io_context(ioc);
1692                 }
1693         }
1694 }
1695
1696 void blkio_policy_register(struct blkio_policy_type *blkiop)
1697 {
1698         spin_lock(&blkio_list_lock);
1699
1700         BUG_ON(blkio_policy[blkiop->plid]);
1701         blkio_policy[blkiop->plid] = blkiop;
1702         list_add_tail(&blkiop->list, &blkio_list);
1703
1704         spin_unlock(&blkio_list_lock);
1705 }
1706 EXPORT_SYMBOL_GPL(blkio_policy_register);
1707
1708 void blkio_policy_unregister(struct blkio_policy_type *blkiop)
1709 {
1710         spin_lock(&blkio_list_lock);
1711
1712         BUG_ON(blkio_policy[blkiop->plid] != blkiop);
1713         blkio_policy[blkiop->plid] = NULL;
1714         list_del_init(&blkiop->list);
1715
1716         spin_unlock(&blkio_list_lock);
1717 }
1718 EXPORT_SYMBOL_GPL(blkio_policy_unregister);