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