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