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_policy_parse_and_set(char *buf,
 772        struct blkio_policy_node *newpn, enum blkio_policy_id plid, int fileid)
 773{
 774        struct gendisk *disk = NULL;
 775        char *s[4], *p, *major_s = NULL, *minor_s = NULL;
 776        unsigned long major, minor;
 777        int i = 0, ret = -EINVAL;
 778        int part;
 779        dev_t dev;
 780        u64 temp;
 781
 782        memset(s, 0, sizeof(s));
 783
 784        while ((p = strsep(&buf, " ")) != NULL) {
 785                if (!*p)
 786                        continue;
 787
 788                s[i++] = p;
 789
 790                /* Prevent from inputing too many things */
 791                if (i == 3)
 792                        break;
 793        }
 794
 795        if (i != 2)
 796                goto out;
 797
 798        p = strsep(&s[0], ":");
 799        if (p != NULL)
 800                major_s = p;
 801        else
 802                goto out;
 803
 804        minor_s = s[0];
 805        if (!minor_s)
 806                goto out;
 807
 808        if (strict_strtoul(major_s, 10, &major))
 809                goto out;
 810
 811        if (strict_strtoul(minor_s, 10, &minor))
 812                goto out;
 813
 814        dev = MKDEV(major, minor);
 815
 816        if (strict_strtoull(s[1], 10, &temp))
 817                goto out;
 818
 819        /* For rule removal, do not check for device presence. */
 820        if (temp) {
 821                disk = get_gendisk(dev, &part);
 822                if (!disk || part) {
 823                        ret = -ENODEV;
 824                        goto out;
 825                }
 826        }
 827
 828        newpn->dev = dev;
 829
 830        switch (plid) {
 831        case BLKIO_POLICY_PROP:
 832                if ((temp < BLKIO_WEIGHT_MIN && temp > 0) ||
 833                     temp > BLKIO_WEIGHT_MAX)
 834                        goto out;
 835
 836                newpn->plid = plid;
 837                newpn->fileid = fileid;
 838                newpn->val.weight = temp;
 839                break;
 840        case BLKIO_POLICY_THROTL:
 841                switch(fileid) {
 842                case BLKIO_THROTL_read_bps_device:
 843                case BLKIO_THROTL_write_bps_device:
 844                        newpn->plid = plid;
 845                        newpn->fileid = fileid;
 846                        newpn->val.bps = temp;
 847                        break;
 848                case BLKIO_THROTL_read_iops_device:
 849                case BLKIO_THROTL_write_iops_device:
 850                        if (temp > THROTL_IOPS_MAX)
 851                                goto out;
 852
 853                        newpn->plid = plid;
 854                        newpn->fileid = fileid;
 855                        newpn->val.iops = (unsigned int)temp;
 856                        break;
 857                }
 858                break;
 859        default:
 860                BUG();
 861        }
 862        ret = 0;
 863out:
 864        put_disk(disk);
 865        return ret;
 866}
 867
 868unsigned int blkcg_get_weight(struct blkio_cgroup *blkcg,
 869                              dev_t dev)
 870{
 871        struct blkio_policy_node *pn;
 872        unsigned long flags;
 873        unsigned int weight;
 874
 875        spin_lock_irqsave(&blkcg->lock, flags);
 876
 877        pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_PROP,
 878                                BLKIO_PROP_weight_device);
 879        if (pn)
 880                weight = pn->val.weight;
 881        else
 882                weight = blkcg->weight;
 883
 884        spin_unlock_irqrestore(&blkcg->lock, flags);
 885
 886        return weight;
 887}
 888EXPORT_SYMBOL_GPL(blkcg_get_weight);
 889
 890uint64_t blkcg_get_read_bps(struct blkio_cgroup *blkcg, dev_t dev)
 891{
 892        struct blkio_policy_node *pn;
 893        unsigned long flags;
 894        uint64_t bps = -1;
 895
 896        spin_lock_irqsave(&blkcg->lock, flags);
 897        pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_THROTL,
 898                                BLKIO_THROTL_read_bps_device);
 899        if (pn)
 900                bps = pn->val.bps;
 901        spin_unlock_irqrestore(&blkcg->lock, flags);
 902
 903        return bps;
 904}
 905
 906uint64_t blkcg_get_write_bps(struct blkio_cgroup *blkcg, dev_t dev)
 907{
 908        struct blkio_policy_node *pn;
 909        unsigned long flags;
 910        uint64_t bps = -1;
 911
 912        spin_lock_irqsave(&blkcg->lock, flags);
 913        pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_THROTL,
 914                                BLKIO_THROTL_write_bps_device);
 915        if (pn)
 916                bps = pn->val.bps;
 917        spin_unlock_irqrestore(&blkcg->lock, flags);
 918
 919        return bps;
 920}
 921
 922unsigned int blkcg_get_read_iops(struct blkio_cgroup *blkcg, dev_t dev)
 923{
 924        struct blkio_policy_node *pn;
 925        unsigned long flags;
 926        unsigned int iops = -1;
 927
 928        spin_lock_irqsave(&blkcg->lock, flags);
 929        pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_THROTL,
 930                                BLKIO_THROTL_read_iops_device);
 931        if (pn)
 932                iops = pn->val.iops;
 933        spin_unlock_irqrestore(&blkcg->lock, flags);
 934
 935        return iops;
 936}
 937
 938unsigned int blkcg_get_write_iops(struct blkio_cgroup *blkcg, dev_t dev)
 939{
 940        struct blkio_policy_node *pn;
 941        unsigned long flags;
 942        unsigned int iops = -1;
 943
 944        spin_lock_irqsave(&blkcg->lock, flags);
 945        pn = blkio_policy_search_node(blkcg, dev, BLKIO_POLICY_THROTL,
 946                                BLKIO_THROTL_write_iops_device);
 947        if (pn)
 948                iops = pn->val.iops;
 949        spin_unlock_irqrestore(&blkcg->lock, flags);
 950
 951        return iops;
 952}
 953
 954/* Checks whether user asked for deleting a policy rule */
 955static bool blkio_delete_rule_command(struct blkio_policy_node *pn)
 956{
 957        switch(pn->plid) {
 958        case BLKIO_POLICY_PROP:
 959                if (pn->val.weight == 0)
 960                        return 1;
 961                break;
 962        case BLKIO_POLICY_THROTL:
 963                switch(pn->fileid) {
 964                case BLKIO_THROTL_read_bps_device:
 965                case BLKIO_THROTL_write_bps_device:
 966                        if (pn->val.bps == 0)
 967                                return 1;
 968                        break;
 969                case BLKIO_THROTL_read_iops_device:
 970                case BLKIO_THROTL_write_iops_device:
 971                        if (pn->val.iops == 0)
 972                                return 1;
 973                }
 974                break;
 975        default:
 976                BUG();
 977        }
 978
 979        return 0;
 980}
 981
 982static void blkio_update_policy_rule(struct blkio_policy_node *oldpn,
 983                                        struct blkio_policy_node *newpn)
 984{
 985        switch(oldpn->plid) {
 986        case BLKIO_POLICY_PROP:
 987                oldpn->val.weight = newpn->val.weight;
 988                break;
 989        case BLKIO_POLICY_THROTL:
 990                switch(newpn->fileid) {
 991                case BLKIO_THROTL_read_bps_device:
 992                case BLKIO_THROTL_write_bps_device:
 993                        oldpn->val.bps = newpn->val.bps;
 994                        break;
 995                case BLKIO_THROTL_read_iops_device:
 996                case BLKIO_THROTL_write_iops_device:
 997                        oldpn->val.iops = newpn->val.iops;
 998                }
 999                break;
1000        default:
1001                BUG();
1002        }
1003}
1004
1005/*
1006 * Some rules/values in blkg have changed. Propagate those to respective
1007 * policies.
1008 */
1009static void blkio_update_blkg_policy(struct blkio_cgroup *blkcg,
1010                struct blkio_group *blkg, struct blkio_policy_node *pn)
1011{
1012        unsigned int weight, iops;
1013        u64 bps;
1014
1015        switch(pn->plid) {
1016        case BLKIO_POLICY_PROP:
1017                weight = pn->val.weight ? pn->val.weight :
1018                                blkcg->weight;
1019                blkio_update_group_weight(blkg, weight);
1020                break;
1021        case BLKIO_POLICY_THROTL:
1022                switch(pn->fileid) {
1023                case BLKIO_THROTL_read_bps_device:
1024                case BLKIO_THROTL_write_bps_device:
1025                        bps = pn->val.bps ? pn->val.bps : (-1);
1026                        blkio_update_group_bps(blkg, bps, pn->fileid);
1027                        break;
1028                case BLKIO_THROTL_read_iops_device:
1029                case BLKIO_THROTL_write_iops_device:
1030                        iops = pn->val.iops ? pn->val.iops : (-1);
1031                        blkio_update_group_iops(blkg, iops, pn->fileid);
1032                        break;
1033                }
1034                break;
1035        default:
1036                BUG();
1037        }
1038}
1039
1040/*
1041 * A policy node rule has been updated. Propagate this update to all the
1042 * block groups which might be affected by this update.
1043 */
1044static void blkio_update_policy_node_blkg(struct blkio_cgroup *blkcg,
1045                                struct blkio_policy_node *pn)
1046{
1047        struct blkio_group *blkg;
1048        struct hlist_node *n;
1049
1050        spin_lock(&blkio_list_lock);
1051        spin_lock_irq(&blkcg->lock);
1052
1053        hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
1054                if (pn->dev != blkg->dev || pn->plid != blkg->plid)
1055                        continue;
1056                blkio_update_blkg_policy(blkcg, blkg, pn);
1057        }
1058
1059        spin_unlock_irq(&blkcg->lock);
1060        spin_unlock(&blkio_list_lock);
1061}
1062
1063static int blkiocg_file_write(struct cgroup *cgrp, struct cftype *cft,
1064                                       const char *buffer)
1065{
1066        int ret = 0;
1067        char *buf;
1068        struct blkio_policy_node *newpn, *pn;
1069        struct blkio_cgroup *blkcg;
1070        int keep_newpn = 0;
1071        enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private);
1072        int fileid = BLKIOFILE_ATTR(cft->private);
1073
1074        buf = kstrdup(buffer, GFP_KERNEL);
1075        if (!buf)
1076                return -ENOMEM;
1077
1078        newpn = kzalloc(sizeof(*newpn), GFP_KERNEL);
1079        if (!newpn) {
1080                ret = -ENOMEM;
1081                goto free_buf;
1082        }
1083
1084        ret = blkio_policy_parse_and_set(buf, newpn, plid, fileid);
1085        if (ret)
1086                goto free_newpn;
1087
1088        blkcg = cgroup_to_blkio_cgroup(cgrp);
1089
1090        spin_lock_irq(&blkcg->lock);
1091
1092        pn = blkio_policy_search_node(blkcg, newpn->dev, plid, fileid);
1093        if (!pn) {
1094                if (!blkio_delete_rule_command(newpn)) {
1095                        blkio_policy_insert_node(blkcg, newpn);
1096                        keep_newpn = 1;
1097                }
1098                spin_unlock_irq(&blkcg->lock);
1099                goto update_io_group;
1100        }
1101
1102        if (blkio_delete_rule_command(newpn)) {
1103                blkio_policy_delete_node(pn);
1104                kfree(pn);
1105                spin_unlock_irq(&blkcg->lock);
1106                goto update_io_group;
1107        }
1108        spin_unlock_irq(&blkcg->lock);
1109
1110        blkio_update_policy_rule(pn, newpn);
1111
1112update_io_group:
1113        blkio_update_policy_node_blkg(blkcg, newpn);
1114
1115free_newpn:
1116        if (!keep_newpn)
1117                kfree(newpn);
1118free_buf:
1119        kfree(buf);
1120        return ret;
1121}
1122
1123static void
1124blkio_print_policy_node(struct seq_file *m, struct blkio_policy_node *pn)
1125{
1126        switch(pn->plid) {
1127                case BLKIO_POLICY_PROP:
1128                        if (pn->fileid == BLKIO_PROP_weight_device)
1129                                seq_printf(m, "%u:%u\t%u\n", MAJOR(pn->dev),
1130                                        MINOR(pn->dev), pn->val.weight);
1131                        break;
1132                case BLKIO_POLICY_THROTL:
1133                        switch(pn->fileid) {
1134                        case BLKIO_THROTL_read_bps_device:
1135                        case BLKIO_THROTL_write_bps_device:
1136                                seq_printf(m, "%u:%u\t%llu\n", MAJOR(pn->dev),
1137                                        MINOR(pn->dev), pn->val.bps);
1138                                break;
1139                        case BLKIO_THROTL_read_iops_device:
1140                        case BLKIO_THROTL_write_iops_device:
1141                                seq_printf(m, "%u:%u\t%u\n", MAJOR(pn->dev),
1142                                        MINOR(pn->dev), pn->val.iops);
1143                                break;
1144                        }
1145                        break;
1146                default:
1147                        BUG();
1148        }
1149}
1150
1151/* cgroup files which read their data from policy nodes end up here */
1152static void blkio_read_policy_node_files(struct cftype *cft,
1153                        struct blkio_cgroup *blkcg, struct seq_file *m)
1154{
1155        struct blkio_policy_node *pn;
1156
1157        if (!list_empty(&blkcg->policy_list)) {
1158                spin_lock_irq(&blkcg->lock);
1159                list_for_each_entry(pn, &blkcg->policy_list, node) {
1160                        if (!pn_matches_cftype(cft, pn))
1161                                continue;
1162                        blkio_print_policy_node(m, pn);
1163                }
1164                spin_unlock_irq(&blkcg->lock);
1165        }
1166}
1167
1168static int blkiocg_file_read(struct cgroup *cgrp, struct cftype *cft,
1169                                struct seq_file *m)
1170{
1171        struct blkio_cgroup *blkcg;
1172        enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private);
1173        int name = BLKIOFILE_ATTR(cft->private);
1174
1175        blkcg = cgroup_to_blkio_cgroup(cgrp);
1176
1177        switch(plid) {
1178        case BLKIO_POLICY_PROP:
1179                switch(name) {
1180                case BLKIO_PROP_weight_device:
1181                        blkio_read_policy_node_files(cft, blkcg, m);
1182                        return 0;
1183                default:
1184                        BUG();
1185                }
1186                break;
1187        case BLKIO_POLICY_THROTL:
1188                switch(name){
1189                case BLKIO_THROTL_read_bps_device:
1190                case BLKIO_THROTL_write_bps_device:
1191                case BLKIO_THROTL_read_iops_device:
1192                case BLKIO_THROTL_write_iops_device:
1193                        blkio_read_policy_node_files(cft, blkcg, m);
1194                        return 0;
1195                default:
1196                        BUG();
1197                }
1198                break;
1199        default:
1200                BUG();
1201        }
1202
1203        return 0;
1204}
1205
1206static int blkio_read_blkg_stats(struct blkio_cgroup *blkcg,
1207                struct cftype *cft, struct cgroup_map_cb *cb,
1208                enum stat_type type, bool show_total, bool pcpu)
1209{
1210        struct blkio_group *blkg;
1211        struct hlist_node *n;
1212        uint64_t cgroup_total = 0;
1213
1214        rcu_read_lock();
1215        hlist_for_each_entry_rcu(blkg, n, &blkcg->blkg_list, blkcg_node) {
1216                if (blkg->dev) {
1217                        if (!cftype_blkg_same_policy(cft, blkg))
1218                                continue;
1219                        if (pcpu)
1220                                cgroup_total += blkio_get_stat_cpu(blkg, cb,
1221                                                blkg->dev, type);
1222                        else {
1223                                spin_lock_irq(&blkg->stats_lock);
1224                                cgroup_total += blkio_get_stat(blkg, cb,
1225                                                blkg->dev, type);
1226                                spin_unlock_irq(&blkg->stats_lock);
1227                        }
1228                }
1229        }
1230        if (show_total)
1231                cb->fill(cb, "Total", cgroup_total);
1232        rcu_read_unlock();
1233        return 0;
1234}
1235
1236/* All map kind of cgroup file get serviced by this function */
1237static int blkiocg_file_read_map(struct cgroup *cgrp, struct cftype *cft,
1238                                struct cgroup_map_cb *cb)
1239{
1240        struct blkio_cgroup *blkcg;
1241        enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private);
1242        int name = BLKIOFILE_ATTR(cft->private);
1243
1244        blkcg = cgroup_to_blkio_cgroup(cgrp);
1245
1246        switch(plid) {
1247        case BLKIO_POLICY_PROP:
1248                switch(name) {
1249                case BLKIO_PROP_time:
1250                        return blkio_read_blkg_stats(blkcg, cft, cb,
1251                                                BLKIO_STAT_TIME, 0, 0);
1252                case BLKIO_PROP_sectors:
1253                        return blkio_read_blkg_stats(blkcg, cft, cb,
1254                                                BLKIO_STAT_CPU_SECTORS, 0, 1);
1255                case BLKIO_PROP_io_service_bytes:
1256                        return blkio_read_blkg_stats(blkcg, cft, cb,
1257                                        BLKIO_STAT_CPU_SERVICE_BYTES, 1, 1);
1258                case BLKIO_PROP_io_serviced:
1259                        return blkio_read_blkg_stats(blkcg, cft, cb,
1260                                                BLKIO_STAT_CPU_SERVICED, 1, 1);
1261                case BLKIO_PROP_io_service_time:
1262                        return blkio_read_blkg_stats(blkcg, cft, cb,
1263                                                BLKIO_STAT_SERVICE_TIME, 1, 0);
1264                case BLKIO_PROP_io_wait_time:
1265                        return blkio_read_blkg_stats(blkcg, cft, cb,
1266                                                BLKIO_STAT_WAIT_TIME, 1, 0);
1267                case BLKIO_PROP_io_merged:
1268                        return blkio_read_blkg_stats(blkcg, cft, cb,
1269                                                BLKIO_STAT_CPU_MERGED, 1, 1);
1270                case BLKIO_PROP_io_queued:
1271                        return blkio_read_blkg_stats(blkcg, cft, cb,
1272                                                BLKIO_STAT_QUEUED, 1, 0);
1273#ifdef CONFIG_DEBUG_BLK_CGROUP
1274                case BLKIO_PROP_unaccounted_time:
1275                        return blkio_read_blkg_stats(blkcg, cft, cb,
1276                                        BLKIO_STAT_UNACCOUNTED_TIME, 0, 0);
1277                case BLKIO_PROP_dequeue:
1278                        return blkio_read_blkg_stats(blkcg, cft, cb,
1279                                                BLKIO_STAT_DEQUEUE, 0, 0);
1280                case BLKIO_PROP_avg_queue_size:
1281                        return blkio_read_blkg_stats(blkcg, cft, cb,
1282                                        BLKIO_STAT_AVG_QUEUE_SIZE, 0, 0);
1283                case BLKIO_PROP_group_wait_time:
1284                        return blkio_read_blkg_stats(blkcg, cft, cb,
1285                                        BLKIO_STAT_GROUP_WAIT_TIME, 0, 0);
1286                case BLKIO_PROP_idle_time:
1287                        return blkio_read_blkg_stats(blkcg, cft, cb,
1288                                                BLKIO_STAT_IDLE_TIME, 0, 0);
1289                case BLKIO_PROP_empty_time:
1290                        return blkio_read_blkg_stats(blkcg, cft, cb,
1291                                                BLKIO_STAT_EMPTY_TIME, 0, 0);
1292#endif
1293                default:
1294                        BUG();
1295                }
1296                break;
1297        case BLKIO_POLICY_THROTL:
1298                switch(name){
1299                case BLKIO_THROTL_io_service_bytes:
1300                        return blkio_read_blkg_stats(blkcg, cft, cb,
1301                                                BLKIO_STAT_CPU_SERVICE_BYTES, 1, 1);
1302                case BLKIO_THROTL_io_serviced:
1303                        return blkio_read_blkg_stats(blkcg, cft, cb,
1304                                                BLKIO_STAT_CPU_SERVICED, 1, 1);
1305                default:
1306                        BUG();
1307                }
1308                break;
1309        default:
1310                BUG();
1311        }
1312
1313        return 0;
1314}
1315
1316static int blkio_weight_write(struct blkio_cgroup *blkcg, u64 val)
1317{
1318        struct blkio_group *blkg;
1319        struct hlist_node *n;
1320        struct blkio_policy_node *pn;
1321
1322        if (val < BLKIO_WEIGHT_MIN || val > BLKIO_WEIGHT_MAX)
1323                return -EINVAL;
1324
1325        spin_lock(&blkio_list_lock);
1326        spin_lock_irq(&blkcg->lock);
1327        blkcg->weight = (unsigned int)val;
1328
1329        hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
1330                pn = blkio_policy_search_node(blkcg, blkg->dev,
1331                                BLKIO_POLICY_PROP, BLKIO_PROP_weight_device);
1332                if (pn)
1333                        continue;
1334
1335                blkio_update_group_weight(blkg, blkcg->weight);
1336        }
1337        spin_unlock_irq(&blkcg->lock);
1338        spin_unlock(&blkio_list_lock);
1339        return 0;
1340}
1341
1342static u64 blkiocg_file_read_u64 (struct cgroup *cgrp, struct cftype *cft) {
1343        struct blkio_cgroup *blkcg;
1344        enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private);
1345        int name = BLKIOFILE_ATTR(cft->private);
1346
1347        blkcg = cgroup_to_blkio_cgroup(cgrp);
1348
1349        switch(plid) {
1350        case BLKIO_POLICY_PROP:
1351                switch(name) {
1352                case BLKIO_PROP_weight:
1353                        return (u64)blkcg->weight;
1354                }
1355                break;
1356        default:
1357                BUG();
1358        }
1359        return 0;
1360}
1361
1362static int
1363blkiocg_file_write_u64(struct cgroup *cgrp, struct cftype *cft, u64 val)
1364{
1365        struct blkio_cgroup *blkcg;
1366        enum blkio_policy_id plid = BLKIOFILE_POLICY(cft->private);
1367        int name = BLKIOFILE_ATTR(cft->private);
1368
1369        blkcg = cgroup_to_blkio_cgroup(cgrp);
1370
1371        switch(plid) {
1372        case BLKIO_POLICY_PROP:
1373                switch(name) {
1374                case BLKIO_PROP_weight:
1375                        return blkio_weight_write(blkcg, val);
1376                }
1377                break;
1378        default:
1379                BUG();
1380        }
1381
1382        return 0;
1383}
1384
1385struct cftype blkio_files[] = {
1386        {
1387                .name = "weight_device",
1388                .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1389                                BLKIO_PROP_weight_device),
1390                .read_seq_string = blkiocg_file_read,
1391                .write_string = blkiocg_file_write,
1392                .max_write_len = 256,
1393        },
1394        {
1395                .name = "weight",
1396                .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1397                                BLKIO_PROP_weight),
1398                .read_u64 = blkiocg_file_read_u64,
1399                .write_u64 = blkiocg_file_write_u64,
1400        },
1401        {
1402                .name = "time",
1403                .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1404                                BLKIO_PROP_time),
1405                .read_map = blkiocg_file_read_map,
1406        },
1407        {
1408                .name = "sectors",
1409                .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1410                                BLKIO_PROP_sectors),
1411                .read_map = blkiocg_file_read_map,
1412        },
1413        {
1414                .name = "io_service_bytes",
1415                .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1416                                BLKIO_PROP_io_service_bytes),
1417                .read_map = blkiocg_file_read_map,
1418        },
1419        {
1420                .name = "io_serviced",
1421                .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1422                                BLKIO_PROP_io_serviced),
1423                .read_map = blkiocg_file_read_map,
1424        },
1425        {
1426                .name = "io_service_time",
1427                .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1428                                BLKIO_PROP_io_service_time),
1429                .read_map = blkiocg_file_read_map,
1430        },
1431        {
1432                .name = "io_wait_time",
1433                .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1434                                BLKIO_PROP_io_wait_time),
1435                .read_map = blkiocg_file_read_map,
1436        },
1437        {
1438                .name = "io_merged",
1439                .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1440                                BLKIO_PROP_io_merged),
1441                .read_map = blkiocg_file_read_map,
1442        },
1443        {
1444                .name = "io_queued",
1445                .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1446                                BLKIO_PROP_io_queued),
1447                .read_map = blkiocg_file_read_map,
1448        },
1449        {
1450                .name = "reset_stats",
1451                .write_u64 = blkiocg_reset_stats,
1452        },
1453#ifdef CONFIG_BLK_DEV_THROTTLING
1454        {
1455                .name = "throttle.read_bps_device",
1456                .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL,
1457                                BLKIO_THROTL_read_bps_device),
1458                .read_seq_string = blkiocg_file_read,
1459                .write_string = blkiocg_file_write,
1460                .max_write_len = 256,
1461        },
1462
1463        {
1464                .name = "throttle.write_bps_device",
1465                .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL,
1466                                BLKIO_THROTL_write_bps_device),
1467                .read_seq_string = blkiocg_file_read,
1468                .write_string = blkiocg_file_write,
1469                .max_write_len = 256,
1470        },
1471
1472        {
1473                .name = "throttle.read_iops_device",
1474                .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL,
1475                                BLKIO_THROTL_read_iops_device),
1476                .read_seq_string = blkiocg_file_read,
1477                .write_string = blkiocg_file_write,
1478                .max_write_len = 256,
1479        },
1480
1481        {
1482                .name = "throttle.write_iops_device",
1483                .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL,
1484                                BLKIO_THROTL_write_iops_device),
1485                .read_seq_string = blkiocg_file_read,
1486                .write_string = blkiocg_file_write,
1487                .max_write_len = 256,
1488        },
1489        {
1490                .name = "throttle.io_service_bytes",
1491                .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL,
1492                                BLKIO_THROTL_io_service_bytes),
1493                .read_map = blkiocg_file_read_map,
1494        },
1495        {
1496                .name = "throttle.io_serviced",
1497                .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_THROTL,
1498                                BLKIO_THROTL_io_serviced),
1499                .read_map = blkiocg_file_read_map,
1500        },
1501#endif /* CONFIG_BLK_DEV_THROTTLING */
1502
1503#ifdef CONFIG_DEBUG_BLK_CGROUP
1504        {
1505                .name = "avg_queue_size",
1506                .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1507                                BLKIO_PROP_avg_queue_size),
1508                .read_map = blkiocg_file_read_map,
1509        },
1510        {
1511                .name = "group_wait_time",
1512                .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1513                                BLKIO_PROP_group_wait_time),
1514                .read_map = blkiocg_file_read_map,
1515        },
1516        {
1517                .name = "idle_time",
1518                .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1519                                BLKIO_PROP_idle_time),
1520                .read_map = blkiocg_file_read_map,
1521        },
1522        {
1523                .name = "empty_time",
1524                .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1525                                BLKIO_PROP_empty_time),
1526                .read_map = blkiocg_file_read_map,
1527        },
1528        {
1529                .name = "dequeue",
1530                .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1531                                BLKIO_PROP_dequeue),
1532                .read_map = blkiocg_file_read_map,
1533        },
1534        {
1535                .name = "unaccounted_time",
1536                .private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
1537                                BLKIO_PROP_unaccounted_time),
1538                .read_map = blkiocg_file_read_map,
1539        },
1540#endif
1541};
1542
1543static int blkiocg_populate(struct cgroup_subsys *subsys, struct cgroup *cgroup)
1544{
1545        return cgroup_add_files(cgroup, subsys, blkio_files,
1546                                ARRAY_SIZE(blkio_files));
1547}
1548
1549static void blkiocg_destroy(struct cgroup_subsys *subsys, struct cgroup *cgroup)
1550{
1551        struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup);
1552        unsigned long flags;
1553        struct blkio_group *blkg;
1554        void *key;
1555        struct blkio_policy_type *blkiop;
1556        struct blkio_policy_node *pn, *pntmp;
1557
1558        rcu_read_lock();
1559        do {
1560                spin_lock_irqsave(&blkcg->lock, flags);
1561
1562                if (hlist_empty(&blkcg->blkg_list)) {
1563                        spin_unlock_irqrestore(&blkcg->lock, flags);
1564                        break;
1565                }
1566
1567                blkg = hlist_entry(blkcg->blkg_list.first, struct blkio_group,
1568                                        blkcg_node);
1569                key = rcu_dereference(blkg->key);
1570                __blkiocg_del_blkio_group(blkg);
1571
1572                spin_unlock_irqrestore(&blkcg->lock, flags);
1573
1574                /*
1575                 * This blkio_group is being unlinked as associated cgroup is
1576                 * going away. Let all the IO controlling policies know about
1577                 * this event.
1578                 */
1579                spin_lock(&blkio_list_lock);
1580                list_for_each_entry(blkiop, &blkio_list, list) {
1581                        if (blkiop->plid != blkg->plid)
1582                                continue;
1583                        blkiop->ops.blkio_unlink_group_fn(key, blkg);
1584                }
1585                spin_unlock(&blkio_list_lock);
1586        } while (1);
1587
1588        list_for_each_entry_safe(pn, pntmp, &blkcg->policy_list, node) {
1589                blkio_policy_delete_node(pn);
1590                kfree(pn);
1591        }
1592
1593        free_css_id(&blkio_subsys, &blkcg->css);
1594        rcu_read_unlock();
1595        if (blkcg != &blkio_root_cgroup)
1596                kfree(blkcg);
1597}
1598
1599static struct cgroup_subsys_state *
1600blkiocg_create(struct cgroup_subsys *subsys, struct cgroup *cgroup)
1601{
1602        struct blkio_cgroup *blkcg;
1603        struct cgroup *parent = cgroup->parent;
1604
1605        if (!parent) {
1606                blkcg = &blkio_root_cgroup;
1607                goto done;
1608        }
1609
1610        blkcg = kzalloc(sizeof(*blkcg), GFP_KERNEL);
1611        if (!blkcg)
1612                return ERR_PTR(-ENOMEM);
1613
1614        blkcg->weight = BLKIO_WEIGHT_DEFAULT;
1615done:
1616        spin_lock_init(&blkcg->lock);
1617        INIT_HLIST_HEAD(&blkcg->blkg_list);
1618
1619        INIT_LIST_HEAD(&blkcg->policy_list);
1620        return &blkcg->css;
1621}
1622
1623/*
1624 * We cannot support shared io contexts, as we have no mean to support
1625 * two tasks with the same ioc in two different groups without major rework
1626 * of the main cic data structures.  For now we allow a task to change
1627 * its cgroup only if it's the only owner of its ioc.
1628 */
1629static int blkiocg_can_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
1630{
1631        struct io_context *ioc;
1632        int ret = 0;
1633
1634        /* task_lock() is needed to avoid races with exit_io_context() */
1635        task_lock(tsk);
1636        ioc = tsk->io_context;
1637        if (ioc && atomic_read(&ioc->nr_tasks) > 1)
1638                ret = -EINVAL;
1639        task_unlock(tsk);
1640
1641        return ret;
1642}
1643
1644static void blkiocg_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
1645{
1646        struct io_context *ioc;
1647
1648        task_lock(tsk);
1649        ioc = tsk->io_context;
1650        if (ioc)
1651                ioc->cgroup_changed = 1;
1652        task_unlock(tsk);
1653}
1654
1655void blkio_policy_register(struct blkio_policy_type *blkiop)
1656{
1657        spin_lock(&blkio_list_lock);
1658        list_add_tail(&blkiop->list, &blkio_list);
1659        spin_unlock(&blkio_list_lock);
1660}
1661EXPORT_SYMBOL_GPL(blkio_policy_register);
1662
1663void blkio_policy_unregister(struct blkio_policy_type *blkiop)
1664{
1665        spin_lock(&blkio_list_lock);
1666        list_del_init(&blkiop->list);
1667        spin_unlock(&blkio_list_lock);
1668}
1669EXPORT_SYMBOL_GPL(blkio_policy_unregister);
1670
1671static int __init init_cgroup_blkio(void)
1672{
1673        return cgroup_load_subsys(&blkio_subsys);
1674}
1675
1676static void __exit exit_cgroup_blkio(void)
1677{
1678        cgroup_unload_subsys(&blkio_subsys);
1679}
1680
1681module_init(init_cgroup_blkio);
1682module_exit(exit_cgroup_blkio);
1683MODULE_LICENSE("GPL");
1684
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