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(struct cgroup_subsys *, struct cgroup *,
  34                               struct task_struct *, bool);
  35 static void blkiocg_attach(struct cgroup_subsys *, struct cgroup *,
  36                            struct cgroup *, struct task_struct *, bool);
  37 static void blkiocg_destroy(struct cgroup_subsys *, struct cgroup *);
  38 static int blkiocg_populate(struct cgroup_subsys *, struct cgroup *);
  39
  40 /* for encoding cft->private value on file */
  41 #define BLKIOFILE_PRIVATE(x, val)       (((x) << 16) | (val))
  42 /* What policy owns the file, proportional or throttle */
  43 #define BLKIOFILE_POLICY(val)           (((val) >> 16) & 0xffff)
  44 #define BLKIOFILE_ATTR(val)             ((val) & 0xffff)
  45
  46 struct cgroup_subsys blkio_subsys = {
  47         .name = "blkio",
  48         .create = blkiocg_create,
  49         .can_attach = blkiocg_can_attach,
  50         .attach = blkiocg_attach,
  51         .destroy = blkiocg_destroy,
  52         .populate = blkiocg_populate,
  53 #ifdef CONFIG_BLK_CGROUP
  54         /* note: blkio_subsys_id is otherwise defined in blk-cgroup.h */
  55         .subsys_id = blkio_subsys_id,
  56 #endif
  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->key,
 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->key,
 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->key,
 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->key,
 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->key,
 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         blkg->stats.unaccounted_time += unaccounted_time;
 389         spin_unlock_irqrestore(&blkg->stats_lock, flags);
 390 }
 391 EXPORT_SYMBOL_GPL(blkiocg_update_timeslice_used);
 392
 393 void blkiocg_update_dispatch_stats(struct blkio_group *blkg,
 394                                 uint64_t bytes, bool direction, bool sync)
 395 {
 396         struct blkio_group_stats *stats;
 397         unsigned long flags;
 398
 399         spin_lock_irqsave(&blkg->stats_lock, flags);
 400         stats = &blkg->stats;
 401         stats->sectors += bytes >> 9;
 402         blkio_add_stat(stats->stat_arr[BLKIO_STAT_SERVICED], 1, direction,
 403                         sync);
 404         blkio_add_stat(stats->stat_arr[BLKIO_STAT_SERVICE_BYTES], bytes,
 405                         direction, sync);
 406         spin_unlock_irqrestore(&blkg->stats_lock, flags);
 407 }
 408 EXPORT_SYMBOL_GPL(blkiocg_update_dispatch_stats);
 409
 410 void blkiocg_update_completion_stats(struct blkio_group *blkg,
 411         uint64_t start_time, uint64_t io_start_time, bool direction, bool sync)
 412 {
 413         struct blkio_group_stats *stats;
 414         unsigned long flags;
 415         unsigned long long now = sched_clock();
 416
 417         spin_lock_irqsave(&blkg->stats_lock, flags);
 418         stats = &blkg->stats;
 419         if (time_after64(now, io_start_time))
 420                 blkio_add_stat(stats->stat_arr[BLKIO_STAT_SERVICE_TIME],
 421                                 now - io_start_time, direction, sync);
 422         if (time_after64(io_start_time, start_time))
 423                 blkio_add_stat(stats->stat_arr[BLKIO_STAT_WAIT_TIME],
 424                                 io_start_time - start_time, direction, sync);
 425         spin_unlock_irqrestore(&blkg->stats_lock, flags);
 426 }
 427 EXPORT_SYMBOL_GPL(blkiocg_update_completion_stats);
 428
 429 void blkiocg_update_io_merged_stats(struct blkio_group *blkg, bool direction,
 430                                         bool sync)
 431 {
 432         unsigned long flags;
 433
 434         spin_lock_irqsave(&blkg->stats_lock, flags);
 435         blkio_add_stat(blkg->stats.stat_arr[BLKIO_STAT_MERGED], 1, direction,
 436                         sync);
 437         spin_unlock_irqrestore(&blkg->stats_lock, flags);
 438 }
 439 EXPORT_SYMBOL_GPL(blkiocg_update_io_merged_stats);
 440
 441 void blkiocg_add_blkio_group(struct blkio_cgroup *blkcg,
 442                 struct blkio_group *blkg, void *key, dev_t dev,
 443                 enum blkio_policy_id plid)
 444 {
 445         unsigned long flags;
 446
 447         spin_lock_irqsave(&blkcg->lock, flags);
 448         spin_lock_init(&blkg->stats_lock);
 449         rcu_assign_pointer(blkg->key, key);
 450         blkg->blkcg_id = css_id(&blkcg->css);
 451         hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list);
 452         blkg->plid = plid;
 453         spin_unlock_irqrestore(&blkcg->lock, flags);
 454         /* Need to take css reference ? */
 455         cgroup_path(blkcg->css.cgroup, blkg->path, sizeof(blkg->path));
 456         blkg->dev = dev;
 457 }
 458 EXPORT_SYMBOL_GPL(blkiocg_add_blkio_group);
 459
 460 static void __blkiocg_del_blkio_group(struct blkio_group *blkg)
 461 {
 462         hlist_del_init_rcu(&blkg->blkcg_node);
 463         blkg->blkcg_id = 0;
 464 }
 465
 466 /*
 467  * returns 0 if blkio_group was still on cgroup list. Otherwise returns 1
 468  * indicating that blk_group was unhashed by the time we got to it.
 469  */
 470 int blkiocg_del_blkio_group(struct blkio_group *blkg)
 471 {
 472         struct blkio_cgroup *blkcg;
 473         unsigned long flags;
 474         struct cgroup_subsys_state *css;
 475         int ret = 1;
 476
 477         rcu_read_lock();
 478         css = css_lookup(&blkio_subsys, blkg->blkcg_id);
 479         if (css) {
 480                 blkcg = container_of(css, struct blkio_cgroup, css);
 481                 spin_lock_irqsave(&blkcg->lock, flags);
 482                 if (!hlist_unhashed(&blkg->blkcg_node)) {
 483                         __blkiocg_del_blkio_group(blkg);
 484                         ret = 0;
 485                 }
 486                 spin_unlock_irqrestore(&blkcg->lock, flags);
 487         }
 488
 489         rcu_read_unlock();
 490         return ret;
 491 }
 492 EXPORT_SYMBOL_GPL(blkiocg_del_blkio_group);
 493
 494 /* called under rcu_read_lock(). */
 495 struct blkio_group *blkiocg_lookup_group(struct blkio_cgroup *blkcg, void *key)
 496 {
 497         struct blkio_group *blkg;
 498         struct hlist_node *n;
 499         void *__key;
 500
 501         hlist_for_each_entry_rcu(blkg, n, &blkcg->blkg_list, blkcg_node) {
 502                 __key = blkg->key;
 503                 if (__key == key)
 504                         return blkg;
 505         }
 506
 507         return NULL;
 508 }
 509 EXPORT_SYMBOL_GPL(blkiocg_lookup_group);
 510
 511 static int
 512 blkiocg_reset_stats(struct cgroup *cgroup, struct cftype *cftype, u64 val)
 513 {
 514         struct blkio_cgroup *blkcg;
 515         struct blkio_group *blkg;
 516         struct blkio_group_stats *stats;
 517         struct hlist_node *n;
 518         uint64_t queued[BLKIO_STAT_TOTAL];
 519         int i;
 520 #ifdef CONFIG_DEBUG_BLK_CGROUP
 521         bool idling, waiting, empty;
 522         unsigned long long now = sched_clock();
 523 #endif
 524
 525         blkcg = cgroup_to_blkio_cgroup(cgroup);
 526         spin_lock_irq(&blkcg->lock);
 527         hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
 528                 spin_lock(&blkg->stats_lock);
 529                 stats = &blkg->stats;
 530 #ifdef CONFIG_DEBUG_BLK_CGROUP
 531                 idling = blkio_blkg_idling(stats);
 532                 waiting = blkio_blkg_waiting(stats);
 533                 empty = blkio_blkg_empty(stats);
 534 #endif
 535                 for (i = 0; i < BLKIO_STAT_TOTAL; i++)
 536                         queued[i] = stats->stat_arr[BLKIO_STAT_QUEUED][i];
 537                 memset(stats, 0, sizeof(struct blkio_group_stats));
 538                 for (i = 0; i < BLKIO_STAT_TOTAL; i++)
 539                         stats->stat_arr[BLKIO_STAT_QUEUED][i] = queued[i];
 540 #ifdef CONFIG_DEBUG_BLK_CGROUP
 541                 if (idling) {
 542                         blkio_mark_blkg_idling(stats);
 543                         stats->start_idle_time = now;
 544                 }
 545                 if (waiting) {
 546                         blkio_mark_blkg_waiting(stats);
 547                         stats->start_group_wait_time = now;
 548                 }
 549                 if (empty) {
 550                         blkio_mark_blkg_empty(stats);
 551                         stats->start_empty_time = now;
 552                 }
 553 #endif
 554                 spin_unlock(&blkg->stats_lock);
 555         }
 556         spin_unlock_irq(&blkcg->lock);
 557         return 0;
 558 }
 559
 560 static void blkio_get_key_name(enum stat_sub_type type, dev_t dev, char *str,
 561                                 int chars_left, bool diskname_only)
 562 {
 563         snprintf(str, chars_left, "%d:%d", MAJOR(dev), MINOR(dev));
 564         chars_left -= strlen(str);
 565         if (chars_left <= 0) {
 566                 printk(KERN_WARNING
 567                         "Possibly incorrect cgroup stat display format");
 568                 return;
 569         }
 570         if (diskname_only)
 571                 return;
 572         switch (type) {
 573         case BLKIO_STAT_READ:
 574                 strlcat(str, " Read", chars_left);
 575                 break;
 576         case BLKIO_STAT_WRITE:
 577                 strlcat(str, " Write", chars_left);
 578                 break;
 579         case BLKIO_STAT_SYNC:
 580                 strlcat(str, " Sync", chars_left);
 581                 break;
 582         case BLKIO_STAT_ASYNC:
 583                 strlcat(str, " Async", chars_left);
 584                 break;
 585         case BLKIO_STAT_TOTAL:
 586                 strlcat(str, " Total", chars_left);
 587                 break;
 588         default:
 589                 strlcat(str, " Invalid", chars_left);
 590         }
 591 }
 592
 593 static uint64_t blkio_fill_stat(char *str, int chars_left, uint64_t val,
 594                                 struct cgroup_map_cb *cb, dev_t dev)
 595 {
 596         blkio_get_key_name(0, dev, str, chars_left, true);
 597         cb->fill(cb, str, val);
 598         return val;
 599 }
 600
 601 /* This should be called with blkg->stats_lock held */
 602 static uint64_t blkio_get_stat(struct blkio_group *blkg,
 603                 struct cgroup_map_cb *cb, dev_t dev, enum stat_type type)
 604 {
 605         uint64_t disk_total;
 606         char key_str[MAX_KEY_LEN];
 607         enum stat_sub_type sub_type;
 608
 609         if (type == BLKIO_STAT_TIME)
 610                 return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
 611                                         blkg->stats.time, cb, dev);
 612         if (type == BLKIO_STAT_SECTORS)
 613                 return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
 614                                         blkg->stats.sectors, cb, dev);
 615 #ifdef CONFIG_DEBUG_BLK_CGROUP
 616         if (type == BLKIO_STAT_UNACCOUNTED_TIME)
 617                 return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
 618                                         blkg->stats.unaccounted_time, cb, dev);
 619         if (type == BLKIO_STAT_AVG_QUEUE_SIZE) {
 620                 uint64_t sum = blkg->stats.avg_queue_size_sum;
 621                 uint64_t samples = blkg->stats.avg_queue_size_samples;
 622                 if (samples)
 623                         do_div(sum, samples);
 624                 else
 625                         sum = 0;
 626                 return blkio_fill_stat(key_str, MAX_KEY_LEN - 1, sum, cb, dev);
 627         }
 628         if (type == BLKIO_STAT_GROUP_WAIT_TIME)
 629                 return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
 630                                         blkg->stats.group_wait_time, cb, dev);
 631         if (type == BLKIO_STAT_IDLE_TIME)
 632                 return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
 633                                         blkg->stats.idle_time, cb, dev);
 634         if (type == BLKIO_STAT_EMPTY_TIME)
 635                 return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
 636                                         blkg->stats.empty_time, cb, dev);
 637         if (type == BLKIO_STAT_DEQUEUE)
 638                 return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
 639                                         blkg->stats.dequeue, cb, dev);
 640 #endif
 641
 642         for (sub_type = BLKIO_STAT_READ; sub_type < BLKIO_STAT_TOTAL;
 643                         sub_type++) {
 644                 blkio_get_key_name(sub_type, dev, key_str, MAX_KEY_LEN, false);
 645                 cb->fill(cb, key_str, blkg->stats.stat_arr[type][sub_type]);
 646         }
 647         disk_total = blkg->stats.stat_arr[type][BLKIO_STAT_READ] +
 648                         blkg->stats.stat_arr[type][BLKIO_STAT_WRITE];
 649         blkio_get_key_name(BLKIO_STAT_TOTAL, dev, key_str, MAX_KEY_LEN, false);
 650         cb->fill(cb, key_str, disk_total);
 651         return disk_total;
 652 }
 653
 654 static int blkio_check_dev_num(dev_t dev)
 655 {
 656         int part = 0;
 657         struct gendisk *disk;
 658
 659         disk = get_gendisk(dev, &part);
 660         if (!disk || part)
 661                 return -ENODEV;
 662
 663         return 0;
 664 }
 665
 666 static int blkio_policy_parse_and_set(char *buf,
 667         struct blkio_policy_node *newpn, enum blkio_policy_id plid, int fileid)
 668 {
 669         char *s[4], *p, *major_s = NULL, *minor_s = NULL;
 670         int ret;
 671         unsigned long major, minor, temp;
 672         int i = 0;
 673         dev_t dev;
 674         u64 bps, iops;
 675
 676         memset(s, 0, sizeof(s));
 677
 678         while ((p = strsep(&buf, " ")) != NULL) {
 679                 if (!*p)
 680                         continue;
 681
 682                 s[i++] = p;
 683
 684                 /* Prevent from inputing too many things */
 685                 if (i == 3)
 686                         break;
 687         }
 688
 689         if (i != 2)
 690                 return -EINVAL;
 691
 692         p = strsep(&s[0], ":");
 693         if (p != NULL)
 694                 major_s = p;
 695         else
 696                 return -EINVAL;
 697
 698         minor_s = s[0];
 699         if (!minor_s)
 700                 return -EINVAL;
 701
 702         ret = strict_strtoul(major_s, 10, &major);
 703         if (ret)
 704                 return -EINVAL;
 705
 706         ret = strict_strtoul(minor_s, 10, &minor);
 707         if (ret)
 708                 return -EINVAL;
 709
 710         dev = MKDEV(major, minor);
 711
 712         ret = blkio_check_dev_num(dev);
 713         if (ret)
 714                 return ret;
 715
 716         newpn->dev = dev;
 717
 718         if (s[1] == NULL)
 719                 return -EINVAL;
 720
 721         switch (plid) {
 722         case BLKIO_POLICY_PROP:
 723                 ret = strict_strtoul(s[1], 10, &temp);
 724                 if (ret || (temp < BLKIO_WEIGHT_MIN && temp > 0) ||
 725                         temp > BLKIO_WEIGHT_MAX)
 726                         return -EINVAL;
 727
 728                 newpn->plid = plid;
 729                 newpn->fileid = fileid;
 730                 newpn->val.weight = temp;
 731                 break;
 732         case BLKIO_POLICY_THROTL:
 733                 switch(fileid) {
 734                 case BLKIO_THROTL_read_bps_device:
 735                 case BLKIO_THROTL_write_bps_device:
 736                         ret = strict_strtoull(s[1], 10, &bps);
 737                         if (ret)
 738                                 return -EINVAL;
 739
 740                         newpn->plid = plid;
 741                         newpn->fileid = fileid;
 742                         newpn->val.bps = bps;
 743                         break;
 744                 case BLKIO_THROTL_read_iops_device:
 745                 case BLKIO_THROTL_write_iops_device:
 746                         ret = strict_strtoull(s[1], 10, &iops);
 747                         if (ret)
 748                                 return -EINVAL;
 749
 750                         if (iops > THROTL_IOPS_MAX)
 751                                 return -EINVAL;
 752
 753                         newpn->plid = plid;
 754                         newpn->fileid = fileid;
 755                         newpn->val.iops = (unsigned int)iops;
 756                         break;
 757                 }
 758                 break;
 759         default:
 760                 BUG();
 761         }
 762
 763         return 0;
 764 }
 765
 766 unsigned int blkcg_get_weight(struct blkio_cgroup *blkcg,
 767                               dev_t dev)
 768 {
 769         struct blkio_policy_node *pn;
 770
 771         pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_PROP,
 772                                 BLKIO_PROP_weight_device);
 773         if (pn)
 774                 return pn->val.weight;
 775         else
 776                 return blkcg->weight;
 777 }
 778 EXPORT_SYMBOL_GPL(blkcg_get_weight);
 779
 780 uint64_t blkcg_get_read_bps(struct blkio_cgroup *blkcg, dev_t dev)
 781 {
 782         struct blkio_policy_node *pn;
 783
 784         pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_THROTL,
 785                                 BLKIO_THROTL_read_bps_device);
 786         if (pn)
 787                 return pn->val.bps;
 788         else
 789                 return -1;
 790 }
 791
 792 uint64_t blkcg_get_write_bps(struct blkio_cgroup *blkcg, dev_t dev)
 793 {
 794         struct blkio_policy_node *pn;
 795         pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_THROTL,
 796                                 BLKIO_THROTL_write_bps_device);
 797         if (pn)
 798                 return pn->val.bps;
 799         else
 800                 return -1;
 801 }
 802
 803 unsigned int blkcg_get_read_iops(struct blkio_cgroup *blkcg, dev_t dev)
 804 {
 805         struct blkio_policy_node *pn;
 806
 807         pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_THROTL,
 808                                 BLKIO_THROTL_read_iops_device);
 809         if (pn)
 810                 return pn->val.iops;
 811         else
 812                 return -1;
 813 }
 814
 815 unsigned int blkcg_get_write_iops(struct blkio_cgroup *blkcg, dev_t dev)
 816 {
 817         struct blkio_policy_node *pn;
 818         pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_THROTL,
 819                                 BLKIO_THROTL_write_iops_device);
 820         if (pn)
 821                 return pn->val.iops;
 822         else
 823                 return -1;
 824 }
 825
 826 /* Checks whether user asked for deleting a policy rule */
 827 static bool blkio_delete_rule_command(struct blkio_policy_node *pn)
 828 {
 829         switch(pn->plid) {
 830         case BLKIO_POLICY_PROP:
 831                 if (pn->val.weight == 0)
 832                         return 1;
 833                 break;
 834         case BLKIO_POLICY_THROTL:
 835                 switch(pn->fileid) {
 836                 case BLKIO_THROTL_read_bps_device:
 837                 case BLKIO_THROTL_write_bps_device:
 838                         if (pn->val.bps == 0)
 839                                 return 1;
 840                         break;
 841                 case BLKIO_THROTL_read_iops_device:
 842                 case BLKIO_THROTL_write_iops_device:
 843                         if (pn->val.iops == 0)
 844                                 return 1;
 845                 }
 846                 break;
 847         default:
 848                 BUG();
 849         }
 850
 851         return 0;
 852 }
 853
 854 static void blkio_update_policy_rule(struct blkio_policy_node *oldpn,
 855                                         struct blkio_policy_node *newpn)
 856 {
 857         switch(oldpn->plid) {
 858         case BLKIO_POLICY_PROP:
 859                 oldpn->val.weight = newpn->val.weight;
 860                 break;
 861         case BLKIO_POLICY_THROTL:
 862                 switch(newpn->fileid) {
 863                 case BLKIO_THROTL_read_bps_device:
 864                 case BLKIO_THROTL_write_bps_device:
 865                         oldpn->val.bps = newpn->val.bps;
 866                         break;
 867                 case BLKIO_THROTL_read_iops_device:
 868                 case BLKIO_THROTL_write_iops_device:
 869                         oldpn->val.iops = newpn->val.iops;
 870                 }
 871                 break;
 872         default:
 873                 BUG();
 874         }
 875 }
 876
 877 /*
 878  * Some rules/values in blkg have changed. Propagate those to respective
 879  * policies.
 880  */
 881 static void blkio_update_blkg_policy(struct blkio_cgroup *blkcg,
 882                 struct blkio_group *blkg, struct blkio_policy_node *pn)
 883 {
 884         unsigned int weight, iops;
 885         u64 bps;
 886
 887         switch(pn->plid) {
 888         case BLKIO_POLICY_PROP:
 889                 weight = pn->val.weight ? pn->val.weight :
 890                                 blkcg->weight;
 891                 blkio_update_group_weight(blkg, weight);
 892                 break;
 893         case BLKIO_POLICY_THROTL:
 894                 switch(pn->fileid) {
 895                 case BLKIO_THROTL_read_bps_device:
 896                 case BLKIO_THROTL_write_bps_device:
 897                         bps = pn->val.bps ? pn->val.bps : (-1);
 898                         blkio_update_group_bps(blkg, bps, pn->fileid);
 899                         break;
 900                 case BLKIO_THROTL_read_iops_device:
 901                 case BLKIO_THROTL_write_iops_device:
 902                         iops = pn->val.iops ? pn->val.iops : (-1);
 903                         blkio_update_group_iops(blkg, iops, pn->fileid);
 904                         break;
 905                 }
 906                 break;
 907         default:
 908                 BUG();
 909         }
 910 }
 911
 912 /*
 913  * A policy node rule has been updated. Propagate this update to all the
 914  * block groups which might be affected by this update.
 915  */
 916 static void blkio_update_policy_node_blkg(struct blkio_cgroup *blkcg,
 917                                 struct blkio_policy_node *pn)
 918 {
 919         struct blkio_group *blkg;
 920         struct hlist_node *n;
 921
 922         spin_lock(&blkio_list_lock);
 923         spin_lock_irq(&blkcg->lock);
 924
 925         hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
 926                 if (pn->dev != blkg->dev || pn->plid != blkg->plid)
 927                         continue;
 928                 blkio_update_blkg_policy(blkcg, blkg, pn);
 929         }
 930
 931         spin_unlock_irq(&blkcg->lock);
 932         spin_unlock(&blkio_list_lock);
 933 }
 934
 935 static int blkiocg_file_write(struct cgroup *cgrp, struct cftype *cft,
 936                                        const char *buffer)
 937 {
 938         int ret = 0;
 939         char *buf;
 940         struct blkio_policy_node *newpn, *pn;
 941         struct blkio_cgroup *blkcg;
 942         int keep_newpn = 0;
 943         enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private);
 944         int fileid = BLKIOFILE_ATTR(cft->private);
 945
 946         buf = kstrdup(buffer, GFP_KERNEL);
 947         if (!buf)
 948                 return -ENOMEM;
 949
 950         newpn = kzalloc(sizeof(*newpn), GFP_KERNEL);
 951         if (!newpn) {
 952                 ret = -ENOMEM;
 953                 goto free_buf;
 954         }
 955
 956         ret = blkio_policy_parse_and_set(buf, newpn, plid, fileid);
 957         if (ret)
 958                 goto free_newpn;
 959
 960         blkcg = cgroup_to_blkio_cgroup(cgrp);
 961
 962         spin_lock_irq(&blkcg->lock);
 963
 964         pn = blkio_policy_search_node(blkcg, newpn->dev, plid, fileid);
 965         if (!pn) {
 966                 if (!blkio_delete_rule_command(newpn)) {
 967                         blkio_policy_insert_node(blkcg, newpn);
 968                         keep_newpn = 1;
 969                 }
 970                 spin_unlock_irq(&blkcg->lock);
 971                 goto update_io_group;
 972         }
 973
 974         if (blkio_delete_rule_command(newpn)) {
 975                 blkio_policy_delete_node(pn);
 976                 spin_unlock_irq(&blkcg->lock);
 977                 goto update_io_group;
 978         }
 979         spin_unlock_irq(&blkcg->lock);
 980
 981         blkio_update_policy_rule(pn, newpn);
 982
 983 update_io_group:
 984         blkio_update_policy_node_blkg(blkcg, newpn);
 985
 986 free_newpn:
 987         if (!keep_newpn)
 988                 kfree(newpn);
 989 free_buf:
 990         kfree(buf);
 991         return ret;
 992 }
 993
 994 static void
 995 blkio_print_policy_node(struct seq_file *m, struct blkio_policy_node *pn)
 996 {
 997         switch(pn->plid) {
 998                 case BLKIO_POLICY_PROP:
 999                         if (pn->fileid == BLKIO_PROP_weight_device)
1000                                 seq_printf(m, "%u:%u\t%u\n", MAJOR(pn->dev),
1001                                         MINOR(pn->dev), pn->val.weight);
1002                         break;
1003                 case BLKIO_POLICY_THROTL:
1004                         switch(pn->fileid) {
1005                         case BLKIO_THROTL_read_bps_device:
1006                         case BLKIO_THROTL_write_bps_device:
1007                                 seq_printf(m, "%u:%u\t%llu\n", MAJOR(pn->dev),
1008                                         MINOR(pn->dev), pn->val.bps);
1009                                 break;
1010                         case BLKIO_THROTL_read_iops_device:
1011                         case BLKIO_THROTL_write_iops_device:
1012                                 seq_printf(m, "%u:%u\t%u\n", MAJOR(pn->dev),
1013                                         MINOR(pn->dev), pn->val.iops);
1014                                 break;
1015                         }
1016                         break;
1017                 default:
1018                         BUG();
1019         }
1020 }
1021
1022 /* cgroup files which read their data from policy nodes end up here */
1023 static void blkio_read_policy_node_files(struct cftype *cft,
1024                         struct blkio_cgroup *blkcg, struct seq_file *m)
1025 {
1026         struct blkio_policy_node *pn;
1027
1028         if (!list_empty(&blkcg->policy_list)) {
1029                 spin_lock_irq(&blkcg->lock);
1030                 list_for_each_entry(pn, &blkcg->policy_list, node) {
1031                         if (!pn_matches_cftype(cft, pn))
1032                                 continue;
1033                         blkio_print_policy_node(m, pn);
1034                 }
1035                 spin_unlock_irq(&blkcg->lock);
1036         }
1037 }
1038
1039 static int blkiocg_file_read(struct cgroup *cgrp, struct cftype *cft,
1040                                 struct seq_file *m)
1041 {
1042         struct blkio_cgroup *blkcg;
1043         enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private);
1044         int name = BLKIOFILE_ATTR(cft->private);
1045
1046         blkcg = cgroup_to_blkio_cgroup(cgrp);
1047
1048         switch(plid) {
1049         case BLKIO_POLICY_PROP:
1050                 switch(name) {
1051                 case BLKIO_PROP_weight_device:
1052                         blkio_read_policy_node_files(cft, blkcg, m);
1053                         return 0;
1054                 default:
1055                         BUG();
1056                 }
1057                 break;
1058         case BLKIO_POLICY_THROTL:
1059                 switch(name){
1060                 case BLKIO_THROTL_read_bps_device:
1061                 case BLKIO_THROTL_write_bps_device:
1062                 case BLKIO_THROTL_read_iops_device:
1063                 case BLKIO_THROTL_write_iops_device:
1064                         blkio_read_policy_node_files(cft, blkcg, m);
1065                         return 0;
1066                 default:
1067                         BUG();
1068                 }
1069                 break;
1070         default:
1071                 BUG();
1072         }
1073
1074         return 0;
1075 }
1076
1077 static int blkio_read_blkg_stats(struct blkio_cgroup *blkcg,
1078                 struct cftype *cft, struct cgroup_map_cb *cb, enum stat_type type,
1079                 bool show_total)
1080 {
1081         struct blkio_group *blkg;
1082         struct hlist_node *n;
1083         uint64_t cgroup_total = 0;
1084
1085         rcu_read_lock();
1086         hlist_for_each_entry_rcu(blkg, n, &blkcg->blkg_list, blkcg_node) {
1087                 if (blkg->dev) {
1088                         if (!cftype_blkg_same_policy(cft, blkg))
1089                                 continue;
1090                         spin_lock_irq(&blkg->stats_lock);
1091                         cgroup_total += blkio_get_stat(blkg, cb, blkg->dev,
1092                                                 type);
1093                         spin_unlock_irq(&blkg->stats_lock);
1094                 }
1095         }
1096         if (show_total)
1097                 cb->fill(cb, "Total", cgroup_total);
1098         rcu_read_unlock();
1099         return 0;
1100 }
1101
1102 /* All map kind of cgroup file get serviced by this function */
1103 static int blkiocg_file_read_map(struct cgroup *cgrp, struct cftype *cft,
1104                                 struct cgroup_map_cb *cb)
1105 {
1106         struct blkio_cgroup *blkcg;
1107         enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private);
1108         int name = BLKIOFILE_ATTR(cft->private);
1109
1110         blkcg = cgroup_to_blkio_cgroup(cgrp);
1111
1112         switch(plid) {
1113         case BLKIO_POLICY_PROP:
1114                 switch(name) {
1115                 case BLKIO_PROP_time:
1116                         return blkio_read_blkg_stats(blkcg, cft, cb,
1117                                                 BLKIO_STAT_TIME, 0);
1118                 case BLKIO_PROP_sectors:
1119                         return blkio_read_blkg_stats(blkcg, cft, cb,
1120                                                 BLKIO_STAT_SECTORS, 0);
1121                 case BLKIO_PROP_io_service_bytes:
1122                         return blkio_read_blkg_stats(blkcg, cft, cb,
1123                                                 BLKIO_STAT_SERVICE_BYTES, 1);
1124                 case BLKIO_PROP_io_serviced:
1125                         return blkio_read_blkg_stats(blkcg, cft, cb,
1126                                                 BLKIO_STAT_SERVICED, 1);
1127                 case BLKIO_PROP_io_service_time:
1128                         return blkio_read_blkg_stats(blkcg, cft, cb,
1129                                                 BLKIO_STAT_SERVICE_TIME, 1);
1130                 case BLKIO_PROP_io_wait_time:
1131                         return blkio_read_blkg_stats(blkcg, cft, cb,
1132                                                 BLKIO_STAT_WAIT_TIME, 1);
1133                 case BLKIO_PROP_io_merged:
1134                         return blkio_read_blkg_stats(blkcg, cft, cb,
1135                                                 BLKIO_STAT_MERGED, 1);
1136                 case BLKIO_PROP_io_queued:
1137                         return blkio_read_blkg_stats(blkcg, cft, cb,
1138                                                 BLKIO_STAT_QUEUED, 1);
1139 #ifdef CONFIG_DEBUG_BLK_CGROUP
1140                 case BLKIO_PROP_unaccounted_time:
1141                         return blkio_read_blkg_stats(blkcg, cft, cb,
1142                                                 BLKIO_STAT_UNACCOUNTED_TIME, 0);
1143                 case BLKIO_PROP_dequeue:
1144                         return blkio_read_blkg_stats(blkcg, cft, cb,
1145                                                 BLKIO_STAT_DEQUEUE, 0);
1146                 case BLKIO_PROP_avg_queue_size:
1147                         return blkio_read_blkg_stats(blkcg, cft, cb,
1148                                                 BLKIO_STAT_AVG_QUEUE_SIZE, 0);
1149                 case BLKIO_PROP_group_wait_time:
1150                         return blkio_read_blkg_stats(blkcg, cft, cb,
1151                                                 BLKIO_STAT_GROUP_WAIT_TIME, 0);
1152                 case BLKIO_PROP_idle_time:
1153                         return blkio_read_blkg_stats(blkcg, cft, cb,
1154                                                 BLKIO_STAT_IDLE_TIME, 0);
1155                 case BLKIO_PROP_empty_time:
1156                         return blkio_read_blkg_stats(blkcg, cft, cb,
1157                                                 BLKIO_STAT_EMPTY_TIME, 0);
1158 #endif
1159                 default:
1160                         BUG();
1161                 }
1162                 break;
1163         case BLKIO_POLICY_THROTL:
1164                 switch(name){
1165                 case BLKIO_THROTL_io_service_bytes:
1166                         return blkio_read_blkg_stats(blkcg, cft, cb,
1167                                                 BLKIO_STAT_SERVICE_BYTES, 1);
1168                 case BLKIO_THROTL_io_serviced:
1169                         return blkio_read_blkg_stats(blkcg, cft, cb,
1170                                                 BLKIO_STAT_SERVICED, 1);
1171                 default:
1172                         BUG();
1173                 }
1174                 break;
1175         default:
1176                 BUG();
1177         }
1178
1179         return 0;
1180 }
1181
1182 static int blkio_weight_write(struct blkio_cgroup *blkcg, u64 val)
1183 {
1184         struct blkio_group *blkg;
1185         struct hlist_node *n;
1186         struct blkio_policy_node *pn;
1187
1188         if (val < BLKIO_WEIGHT_MIN || val > BLKIO_WEIGHT_MAX)
1189                 return -EINVAL;
1190
1191         spin_lock(&blkio_list_lock);
1192         spin_lock_irq(&blkcg->lock);
1193         blkcg->weight = (unsigned int)val;
1194
1195         hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
1196                 pn = blkio_policy_search_node(blkcg, blkg->dev,
1197                                 BLKIO_POLICY_PROP, BLKIO_PROP_weight_device);
1198                 if (pn)
1199                         continue;
1200
1201                 blkio_update_group_weight(blkg, blkcg->weight);
1202         }
1203         spin_unlock_irq(&blkcg->lock);
1204         spin_unlock(&blkio_list_lock);
1205         return 0;
1206 }
1207
1208 static u64 blkiocg_file_read_u64 (struct cgroup *cgrp, struct cftype *cft) {
1209         struct blkio_cgroup *blkcg;
1210         enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private);
1211         int name = BLKIOFILE_ATTR(cft->private);
1212
1213         blkcg = cgroup_to_blkio_cgroup(cgrp);
1214
1215         switch(plid) {
1216         case BLKIO_POLICY_PROP:
1217                 switch(name) {
1218                 case BLKIO_PROP_weight:
1219                         return (u64)blkcg->weight;
1220                 }
1221                 break;
1222         default:
1223                 BUG();
1224         }
1225         return 0;
1226 }
1227
1228 static int
1229 blkiocg_file_write_u64(struct cgroup *cgrp, struct cftype *cft, u64 val)
1230 {
1231         struct blkio_cgroup *blkcg;
1232         enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private);
1233         int name = BLKIOFILE_ATTR(cft->private);
1234
1235         blkcg = cgroup_to_blkio_cgroup(cgrp);
1236
1237         switch(plid) {
1238         case BLKIO_POLICY_PROP:
1239                 switch(name) {
1240                 case BLKIO_PROP_weight:
1241                         return blkio_weight_write(blkcg, val);
1242                 }
1243                 break;
1244         default:
1245                 BUG();
1246         }
1247
1248         return 0;
1249 }
1250
1251 struct cftype blkio_files[] = {
1252         {
1253                 .name = "weight_device",
1254                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1255                                 BLKIO_PROP_weight_device),
1256                 .read_seq_string = blkiocg_file_read,
1257                 .write_string = blkiocg_file_write,
1258                 .max_write_len = 256,
1259         },
1260         {
1261                 .name = "weight",
1262                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1263                                 BLKIO_PROP_weight),
1264                 .read_u64 = blkiocg_file_read_u64,
1265                 .write_u64 = blkiocg_file_write_u64,
1266         },
1267         {
1268                 .name = "time",
1269                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1270                                 BLKIO_PROP_time),
1271                 .read_map = blkiocg_file_read_map,
1272         },
1273         {
1274                 .name = "sectors",
1275                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1276                                 BLKIO_PROP_sectors),
1277                 .read_map = blkiocg_file_read_map,
1278         },
1279         {
1280                 .name = "io_service_bytes",
1281                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1282                                 BLKIO_PROP_io_service_bytes),
1283                 .read_map = blkiocg_file_read_map,
1284         },
1285         {
1286                 .name = "io_serviced",
1287                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1288                                 BLKIO_PROP_io_serviced),
1289                 .read_map = blkiocg_file_read_map,
1290         },
1291         {
1292                 .name = "io_service_time",
1293                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1294                                 BLKIO_PROP_io_service_time),
1295                 .read_map = blkiocg_file_read_map,
1296         },
1297         {
1298                 .name = "io_wait_time",
1299                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1300                                 BLKIO_PROP_io_wait_time),
1301                 .read_map = blkiocg_file_read_map,
1302         },
1303         {
1304                 .name = "io_merged",
1305                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1306                                 BLKIO_PROP_io_merged),
1307                 .read_map = blkiocg_file_read_map,
1308         },
1309         {
1310                 .name = "io_queued",
1311                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1312                                 BLKIO_PROP_io_queued),
1313                 .read_map = blkiocg_file_read_map,
1314         },
1315         {
1316                 .name = "reset_stats",
1317                 .write_u64 = blkiocg_reset_stats,
1318         },
1319 #ifdef CONFIG_BLK_DEV_THROTTLING
1320         {
1321                 .name = "throttle.read_bps_device",
1322                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL,
1323                                 BLKIO_THROTL_read_bps_device),
1324                 .read_seq_string = blkiocg_file_read,
1325                 .write_string = blkiocg_file_write,
1326                 .max_write_len = 256,
1327         },
1328
1329         {
1330                 .name = "throttle.write_bps_device",
1331                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL,
1332                                 BLKIO_THROTL_write_bps_device),
1333                 .read_seq_string = blkiocg_file_read,
1334                 .write_string = blkiocg_file_write,
1335                 .max_write_len = 256,
1336         },
1337
1338         {
1339                 .name = "throttle.read_iops_device",
1340                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL,
1341                                 BLKIO_THROTL_read_iops_device),
1342                 .read_seq_string = blkiocg_file_read,
1343                 .write_string = blkiocg_file_write,
1344                 .max_write_len = 256,
1345         },
1346
1347         {
1348                 .name = "throttle.write_iops_device",
1349                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL,
1350                                 BLKIO_THROTL_write_iops_device),
1351                 .read_seq_string = blkiocg_file_read,
1352                 .write_string = blkiocg_file_write,
1353                 .max_write_len = 256,
1354         },
1355         {
1356                 .name = "throttle.io_service_bytes",
1357                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL,
1358                                 BLKIO_THROTL_io_service_bytes),
1359                 .read_map = blkiocg_file_read_map,
1360         },
1361         {
1362                 .name = "throttle.io_serviced",
1363                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL,
1364                                 BLKIO_THROTL_io_serviced),
1365                 .read_map = blkiocg_file_read_map,
1366         },
1367 #endif /* CONFIG_BLK_DEV_THROTTLING */
1368
1369 #ifdef CONFIG_DEBUG_BLK_CGROUP
1370         {
1371                 .name = "avg_queue_size",
1372                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1373                                 BLKIO_PROP_avg_queue_size),
1374                 .read_map = blkiocg_file_read_map,
1375         },
1376         {
1377                 .name = "group_wait_time",
1378                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1379                                 BLKIO_PROP_group_wait_time),
1380                 .read_map = blkiocg_file_read_map,
1381         },
1382         {
1383                 .name = "idle_time",
1384                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1385                                 BLKIO_PROP_idle_time),
1386                 .read_map = blkiocg_file_read_map,
1387         },
1388         {
1389                 .name = "empty_time",
1390                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1391                                 BLKIO_PROP_empty_time),
1392                 .read_map = blkiocg_file_read_map,
1393         },
1394         {
1395                 .name = "dequeue",
1396                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1397                                 BLKIO_PROP_dequeue),
1398                 .read_map = blkiocg_file_read_map,
1399         },
1400         {
1401                 .name = "unaccounted_time",
1402                 .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1403                                 BLKIO_PROP_unaccounted_time),
1404                 .read_map = blkiocg_file_read_map,
1405         },
1406 #endif
1407 };
1408
1409 static int blkiocg_populate(struct cgroup_subsys *subsys, struct cgroup *cgroup)
1410 {
1411         return cgroup_add_files(cgroup, subsys, blkio_files,
1412                                 ARRAY_SIZE(blkio_files));
1413 }
1414
1415 static void blkiocg_destroy(struct cgroup_subsys *subsys, struct cgroup *cgroup)
1416 {
1417         struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup);
1418         unsigned long flags;
1419         struct blkio_group *blkg;
1420         void *key;
1421         struct blkio_policy_type *blkiop;
1422         struct blkio_policy_node *pn, *pntmp;
1423
1424         rcu_read_lock();
1425         do {
1426                 spin_lock_irqsave(&blkcg->lock, flags);
1427
1428                 if (hlist_empty(&blkcg->blkg_list)) {
1429                         spin_unlock_irqrestore(&blkcg->lock, flags);
1430                         break;
1431                 }
1432
1433                 blkg = hlist_entry(blkcg->blkg_list.first, struct blkio_group,
1434                                         blkcg_node);
1435                 key = rcu_dereference(blkg->key);
1436                 __blkiocg_del_blkio_group(blkg);
1437
1438                 spin_unlock_irqrestore(&blkcg->lock, flags);
1439
1440                 /*
1441                  * This blkio_group is being unlinked as associated cgroup is
1442                  * going away. Let all the IO controlling policies know about
1443                  * this event.
1444                  */
1445                 spin_lock(&blkio_list_lock);
1446                 list_for_each_entry(blkiop, &blkio_list, list) {
1447                         if (blkiop->plid != blkg->plid)
1448                                 continue;
1449                         blkiop->ops.blkio_unlink_group_fn(key, blkg);
1450                 }
1451                 spin_unlock(&blkio_list_lock);
1452         } while (1);
1453
1454         list_for_each_entry_safe(pn, pntmp, &blkcg->policy_list, node) {
1455                 blkio_policy_delete_node(pn);
1456                 kfree(pn);
1457         }
1458
1459         free_css_id(&blkio_subsys, &blkcg->css);
1460         rcu_read_unlock();
1461         if (blkcg != &blkio_root_cgroup)
1462                 kfree(blkcg);
1463 }
1464
1465 static struct cgroup_subsys_state *
1466 blkiocg_create(struct cgroup_subsys *subsys, struct cgroup *cgroup)
1467 {
1468         struct blkio_cgroup *blkcg;
1469         struct cgroup *parent = cgroup->parent;
1470
1471         if (!parent) {
1472                 blkcg = &blkio_root_cgroup;
1473                 goto done;
1474         }
1475
1476         blkcg = kzalloc(sizeof(*blkcg), GFP_KERNEL);
1477         if (!blkcg)
1478                 return ERR_PTR(-ENOMEM);
1479
1480         blkcg->weight = BLKIO_WEIGHT_DEFAULT;
1481 done:
1482         spin_lock_init(&blkcg->lock);
1483         INIT_HLIST_HEAD(&blkcg->blkg_list);
1484
1485         INIT_LIST_HEAD(&blkcg->policy_list);
1486         return &blkcg->css;
1487 }
1488
1489 /*
1490  * We cannot support shared io contexts, as we have no mean to support
1491  * two tasks with the same ioc in two different groups without major rework
1492  * of the main cic data structures.  For now we allow a task to change
1493  * its cgroup only if it's the only owner of its ioc.
1494  */
1495 static int blkiocg_can_attach(struct cgroup_subsys *subsys,
1496                                 struct cgroup *cgroup, struct task_struct *tsk,
1497                                 bool threadgroup)
1498 {
1499         struct io_context *ioc;
1500         int ret = 0;
1501
1502         /* task_lock() is needed to avoid races with exit_io_context() */
1503         task_lock(tsk);
1504         ioc = tsk->io_context;
1505         if (ioc && atomic_read(&ioc->nr_tasks) > 1)
1506                 ret = -EINVAL;
1507         task_unlock(tsk);
1508
1509         return ret;
1510 }
1511
1512 static void blkiocg_attach(struct cgroup_subsys *subsys, struct cgroup *cgroup,
1513                                 struct cgroup *prev, struct task_struct *tsk,
1514                                 bool threadgroup)
1515 {
1516         struct io_context *ioc;
1517
1518         task_lock(tsk);
1519         ioc = tsk->io_context;
1520         if (ioc)
1521                 ioc->cgroup_changed = 1;
1522         task_unlock(tsk);
1523 }
1524
1525 void blkio_policy_register(struct blkio_policy_type *blkiop)
1526 {
1527         spin_lock(&blkio_list_lock);
1528         list_add_tail(&blkiop->list, &blkio_list);
1529         spin_unlock(&blkio_list_lock);
1530 }
1531 EXPORT_SYMBOL_GPL(blkio_policy_register);
1532
1533 void blkio_policy_unregister(struct blkio_policy_type *blkiop)
1534 {
1535         spin_lock(&blkio_list_lock);
1536         list_del_init(&blkiop->list);
1537         spin_unlock(&blkio_list_lock);
1538 }
1539 EXPORT_SYMBOL_GPL(blkio_policy_unregister);
1540
1541 static int __init init_cgroup_blkio(void)
1542 {
1543         return cgroup_load_subsys(&blkio_subsys);
1544 }
1545
1546 static void __exit exit_cgroup_blkio(void)
1547 {
1548         cgroup_unload_subsys(&blkio_subsys);
1549 }
1550
1551 module_init(init_cgroup_blkio);
1552 module_exit(exit_cgroup_blkio);
1553 MODULE_LICENSE("GPL");