linux/block/cfq-iosched.c
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   1/*
   2 *  CFQ, or complete fairness queueing, disk scheduler.
   3 *
   4 *  Based on ideas from a previously unfinished io
   5 *  scheduler (round robin per-process disk scheduling) and Andrea Arcangeli.
   6 *
   7 *  Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
   8 */
   9#include <linux/module.h>
  10#include <linux/slab.h>
  11#include <linux/blkdev.h>
  12#include <linux/elevator.h>
  13#include <linux/jiffies.h>
  14#include <linux/rbtree.h>
  15#include <linux/ioprio.h>
  16#include <linux/blktrace_api.h>
  17#include "blk.h"
  18#include "blk-cgroup.h"
  19
  20/*
  21 * tunables
  22 */
  23/* max queue in one round of service */
  24static const int cfq_quantum = 8;
  25static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 };
  26/* maximum backwards seek, in KiB */
  27static const int cfq_back_max = 16 * 1024;
  28/* penalty of a backwards seek */
  29static const int cfq_back_penalty = 2;
  30static const int cfq_slice_sync = HZ / 10;
  31static int cfq_slice_async = HZ / 25;
  32static const int cfq_slice_async_rq = 2;
  33static int cfq_slice_idle = HZ / 125;
  34static int cfq_group_idle = HZ / 125;
  35static const int cfq_target_latency = HZ * 3/10; /* 300 ms */
  36static const int cfq_hist_divisor = 4;
  37
  38/*
  39 * offset from end of service tree
  40 */
  41#define CFQ_IDLE_DELAY          (HZ / 5)
  42
  43/*
  44 * below this threshold, we consider thinktime immediate
  45 */
  46#define CFQ_MIN_TT              (2)
  47
  48#define CFQ_SLICE_SCALE         (5)
  49#define CFQ_HW_QUEUE_MIN        (5)
  50#define CFQ_SERVICE_SHIFT       12
  51
  52#define CFQQ_SEEK_THR           (sector_t)(8 * 100)
  53#define CFQQ_CLOSE_THR          (sector_t)(8 * 1024)
  54#define CFQQ_SECT_THR_NONROT    (sector_t)(2 * 32)
  55#define CFQQ_SEEKY(cfqq)        (hweight32(cfqq->seek_history) > 32/8)
  56
  57#define RQ_CIC(rq)              icq_to_cic((rq)->elv.icq)
  58#define RQ_CFQQ(rq)             (struct cfq_queue *) ((rq)->elv.priv[0])
  59#define RQ_CFQG(rq)             (struct cfq_group *) ((rq)->elv.priv[1])
  60
  61static struct kmem_cache *cfq_pool;
  62
  63#define CFQ_PRIO_LISTS          IOPRIO_BE_NR
  64#define cfq_class_idle(cfqq)    ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
  65#define cfq_class_rt(cfqq)      ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
  66
  67#define sample_valid(samples)   ((samples) > 80)
  68#define rb_entry_cfqg(node)     rb_entry((node), struct cfq_group, rb_node)
  69
  70struct cfq_ttime {
  71        unsigned long last_end_request;
  72
  73        unsigned long ttime_total;
  74        unsigned long ttime_samples;
  75        unsigned long ttime_mean;
  76};
  77
  78/*
  79 * Most of our rbtree usage is for sorting with min extraction, so
  80 * if we cache the leftmost node we don't have to walk down the tree
  81 * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should
  82 * move this into the elevator for the rq sorting as well.
  83 */
  84struct cfq_rb_root {
  85        struct rb_root rb;
  86        struct rb_node *left;
  87        unsigned count;
  88        unsigned total_weight;
  89        u64 min_vdisktime;
  90        struct cfq_ttime ttime;
  91};
  92#define CFQ_RB_ROOT     (struct cfq_rb_root) { .rb = RB_ROOT, \
  93                        .ttime = {.last_end_request = jiffies,},}
  94
  95/*
  96 * Per process-grouping structure
  97 */
  98struct cfq_queue {
  99        /* reference count */
 100        int ref;
 101        /* various state flags, see below */
 102        unsigned int flags;
 103        /* parent cfq_data */
 104        struct cfq_data *cfqd;
 105        /* service_tree member */
 106        struct rb_node rb_node;
 107        /* service_tree key */
 108        unsigned long rb_key;
 109        /* prio tree member */
 110        struct rb_node p_node;
 111        /* prio tree root we belong to, if any */
 112        struct rb_root *p_root;
 113        /* sorted list of pending requests */
 114        struct rb_root sort_list;
 115        /* if fifo isn't expired, next request to serve */
 116        struct request *next_rq;
 117        /* requests queued in sort_list */
 118        int queued[2];
 119        /* currently allocated requests */
 120        int allocated[2];
 121        /* fifo list of requests in sort_list */
 122        struct list_head fifo;
 123
 124        /* time when queue got scheduled in to dispatch first request. */
 125        unsigned long dispatch_start;
 126        unsigned int allocated_slice;
 127        unsigned int slice_dispatch;
 128        /* time when first request from queue completed and slice started. */
 129        unsigned long slice_start;
 130        unsigned long slice_end;
 131        long slice_resid;
 132
 133        /* pending priority requests */
 134        int prio_pending;
 135        /* number of requests that are on the dispatch list or inside driver */
 136        int dispatched;
 137
 138        /* io prio of this group */
 139        unsigned short ioprio, org_ioprio;
 140        unsigned short ioprio_class;
 141
 142        pid_t pid;
 143
 144        u32 seek_history;
 145        sector_t last_request_pos;
 146
 147        struct cfq_rb_root *service_tree;
 148        struct cfq_queue *new_cfqq;
 149        struct cfq_group *cfqg;
 150        /* Number of sectors dispatched from queue in single dispatch round */
 151        unsigned long nr_sectors;
 152};
 153
 154/*
 155 * First index in the service_trees.
 156 * IDLE is handled separately, so it has negative index
 157 */
 158enum wl_prio_t {
 159        BE_WORKLOAD = 0,
 160        RT_WORKLOAD = 1,
 161        IDLE_WORKLOAD = 2,
 162        CFQ_PRIO_NR,
 163};
 164
 165/*
 166 * Second index in the service_trees.
 167 */
 168enum wl_type_t {
 169        ASYNC_WORKLOAD = 0,
 170        SYNC_NOIDLE_WORKLOAD = 1,
 171        SYNC_WORKLOAD = 2
 172};
 173
 174struct cfqg_stats {
 175#ifdef CONFIG_CFQ_GROUP_IOSCHED
 176        /* total bytes transferred */
 177        struct blkg_rwstat              service_bytes;
 178        /* total IOs serviced, post merge */
 179        struct blkg_rwstat              serviced;
 180        /* number of ios merged */
 181        struct blkg_rwstat              merged;
 182        /* total time spent on device in ns, may not be accurate w/ queueing */
 183        struct blkg_rwstat              service_time;
 184        /* total time spent waiting in scheduler queue in ns */
 185        struct blkg_rwstat              wait_time;
 186        /* number of IOs queued up */
 187        struct blkg_rwstat              queued;
 188        /* total sectors transferred */
 189        struct blkg_stat                sectors;
 190        /* total disk time and nr sectors dispatched by this group */
 191        struct blkg_stat                time;
 192#ifdef CONFIG_DEBUG_BLK_CGROUP
 193        /* time not charged to this cgroup */
 194        struct blkg_stat                unaccounted_time;
 195        /* sum of number of ios queued across all samples */
 196        struct blkg_stat                avg_queue_size_sum;
 197        /* count of samples taken for average */
 198        struct blkg_stat                avg_queue_size_samples;
 199        /* how many times this group has been removed from service tree */
 200        struct blkg_stat                dequeue;
 201        /* total time spent waiting for it to be assigned a timeslice. */
 202        struct blkg_stat                group_wait_time;
 203        /* time spent idling for this blkcg_gq */
 204        struct blkg_stat                idle_time;
 205        /* total time with empty current active q with other requests queued */
 206        struct blkg_stat                empty_time;
 207        /* fields after this shouldn't be cleared on stat reset */
 208        uint64_t                        start_group_wait_time;
 209        uint64_t                        start_idle_time;
 210        uint64_t                        start_empty_time;
 211        uint16_t                        flags;
 212#endif  /* CONFIG_DEBUG_BLK_CGROUP */
 213#endif  /* CONFIG_CFQ_GROUP_IOSCHED */
 214};
 215
 216/* This is per cgroup per device grouping structure */
 217struct cfq_group {
 218        /* must be the first member */
 219        struct blkg_policy_data pd;
 220
 221        /* group service_tree member */
 222        struct rb_node rb_node;
 223
 224        /* group service_tree key */
 225        u64 vdisktime;
 226        unsigned int weight;
 227        unsigned int new_weight;
 228        unsigned int dev_weight;
 229
 230        /* number of cfqq currently on this group */
 231        int nr_cfqq;
 232
 233        /*
 234         * Per group busy queues average. Useful for workload slice calc. We
 235         * create the array for each prio class but at run time it is used
 236         * only for RT and BE class and slot for IDLE class remains unused.
 237         * This is primarily done to avoid confusion and a gcc warning.
 238         */
 239        unsigned int busy_queues_avg[CFQ_PRIO_NR];
 240        /*
 241         * rr lists of queues with requests. We maintain service trees for
 242         * RT and BE classes. These trees are subdivided in subclasses
 243         * of SYNC, SYNC_NOIDLE and ASYNC based on workload type. For IDLE
 244         * class there is no subclassification and all the cfq queues go on
 245         * a single tree service_tree_idle.
 246         * Counts are embedded in the cfq_rb_root
 247         */
 248        struct cfq_rb_root service_trees[2][3];
 249        struct cfq_rb_root service_tree_idle;
 250
 251        unsigned long saved_workload_slice;
 252        enum wl_type_t saved_workload;
 253        enum wl_prio_t saved_serving_prio;
 254
 255        /* number of requests that are on the dispatch list or inside driver */
 256        int dispatched;
 257        struct cfq_ttime ttime;
 258        struct cfqg_stats stats;
 259};
 260
 261struct cfq_io_cq {
 262        struct io_cq            icq;            /* must be the first member */
 263        struct cfq_queue        *cfqq[2];
 264        struct cfq_ttime        ttime;
 265        int                     ioprio;         /* the current ioprio */
 266#ifdef CONFIG_CFQ_GROUP_IOSCHED
 267        uint64_t                blkcg_id;       /* the current blkcg ID */
 268#endif
 269};
 270
 271/*
 272 * Per block device queue structure
 273 */
 274struct cfq_data {
 275        struct request_queue *queue;
 276        /* Root service tree for cfq_groups */
 277        struct cfq_rb_root grp_service_tree;
 278        struct cfq_group *root_group;
 279
 280        /*
 281         * The priority currently being served
 282         */
 283        enum wl_prio_t serving_prio;
 284        enum wl_type_t serving_type;
 285        unsigned long workload_expires;
 286        struct cfq_group *serving_group;
 287
 288        /*
 289         * Each priority tree is sorted by next_request position.  These
 290         * trees are used when determining if two or more queues are
 291         * interleaving requests (see cfq_close_cooperator).
 292         */
 293        struct rb_root prio_trees[CFQ_PRIO_LISTS];
 294
 295        unsigned int busy_queues;
 296        unsigned int busy_sync_queues;
 297
 298        int rq_in_driver;
 299        int rq_in_flight[2];
 300
 301        /*
 302         * queue-depth detection
 303         */
 304        int rq_queued;
 305        int hw_tag;
 306        /*
 307         * hw_tag can be
 308         * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection)
 309         *  1 => NCQ is present (hw_tag_est_depth is the estimated max depth)
 310         *  0 => no NCQ
 311         */
 312        int hw_tag_est_depth;
 313        unsigned int hw_tag_samples;
 314
 315        /*
 316         * idle window management
 317         */
 318        struct timer_list idle_slice_timer;
 319        struct work_struct unplug_work;
 320
 321        struct cfq_queue *active_queue;
 322        struct cfq_io_cq *active_cic;
 323
 324        /*
 325         * async queue for each priority case
 326         */
 327        struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR];
 328        struct cfq_queue *async_idle_cfqq;
 329
 330        sector_t last_position;
 331
 332        /*
 333         * tunables, see top of file
 334         */
 335        unsigned int cfq_quantum;
 336        unsigned int cfq_fifo_expire[2];
 337        unsigned int cfq_back_penalty;
 338        unsigned int cfq_back_max;
 339        unsigned int cfq_slice[2];
 340        unsigned int cfq_slice_async_rq;
 341        unsigned int cfq_slice_idle;
 342        unsigned int cfq_group_idle;
 343        unsigned int cfq_latency;
 344        unsigned int cfq_target_latency;
 345
 346        /*
 347         * Fallback dummy cfqq for extreme OOM conditions
 348         */
 349        struct cfq_queue oom_cfqq;
 350
 351        unsigned long last_delayed_sync;
 352};
 353
 354static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd);
 355
 356static struct cfq_rb_root *service_tree_for(struct cfq_group *cfqg,
 357                                            enum wl_prio_t prio,
 358                                            enum wl_type_t type)
 359{
 360        if (!cfqg)
 361                return NULL;
 362
 363        if (prio == IDLE_WORKLOAD)
 364                return &cfqg->service_tree_idle;
 365
 366        return &cfqg->service_trees[prio][type];
 367}
 368
 369enum cfqq_state_flags {
 370        CFQ_CFQQ_FLAG_on_rr = 0,        /* on round-robin busy list */
 371        CFQ_CFQQ_FLAG_wait_request,     /* waiting for a request */
 372        CFQ_CFQQ_FLAG_must_dispatch,    /* must be allowed a dispatch */
 373        CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */
 374        CFQ_CFQQ_FLAG_fifo_expire,      /* FIFO checked in this slice */
 375        CFQ_CFQQ_FLAG_idle_window,      /* slice idling enabled */
 376        CFQ_CFQQ_FLAG_prio_changed,     /* task priority has changed */
 377        CFQ_CFQQ_FLAG_slice_new,        /* no requests dispatched in slice */
 378        CFQ_CFQQ_FLAG_sync,             /* synchronous queue */
 379        CFQ_CFQQ_FLAG_coop,             /* cfqq is shared */
 380        CFQ_CFQQ_FLAG_split_coop,       /* shared cfqq will be splitted */
 381        CFQ_CFQQ_FLAG_deep,             /* sync cfqq experienced large depth */
 382        CFQ_CFQQ_FLAG_wait_busy,        /* Waiting for next request */
 383};
 384
 385#define CFQ_CFQQ_FNS(name)                                              \
 386static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq)         \
 387{                                                                       \
 388        (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name);                   \
 389}                                                                       \
 390static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq)        \
 391{                                                                       \
 392        (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name);                  \
 393}                                                                       \
 394static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq)         \
 395{                                                                       \
 396        return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0;      \
 397}
 398
 399CFQ_CFQQ_FNS(on_rr);
 400CFQ_CFQQ_FNS(wait_request);
 401CFQ_CFQQ_FNS(must_dispatch);
 402CFQ_CFQQ_FNS(must_alloc_slice);
 403CFQ_CFQQ_FNS(fifo_expire);
 404CFQ_CFQQ_FNS(idle_window);
 405CFQ_CFQQ_FNS(prio_changed);
 406CFQ_CFQQ_FNS(slice_new);
 407CFQ_CFQQ_FNS(sync);
 408CFQ_CFQQ_FNS(coop);
 409CFQ_CFQQ_FNS(split_coop);
 410CFQ_CFQQ_FNS(deep);
 411CFQ_CFQQ_FNS(wait_busy);
 412#undef CFQ_CFQQ_FNS
 413
 414static inline struct cfq_group *pd_to_cfqg(struct blkg_policy_data *pd)
 415{
 416        return pd ? container_of(pd, struct cfq_group, pd) : NULL;
 417}
 418
 419static inline struct blkcg_gq *cfqg_to_blkg(struct cfq_group *cfqg)
 420{
 421        return pd_to_blkg(&cfqg->pd);
 422}
 423
 424#if defined(CONFIG_CFQ_GROUP_IOSCHED) && defined(CONFIG_DEBUG_BLK_CGROUP)
 425
 426/* cfqg stats flags */
 427enum cfqg_stats_flags {
 428        CFQG_stats_waiting = 0,
 429        CFQG_stats_idling,
 430        CFQG_stats_empty,
 431};
 432
 433#define CFQG_FLAG_FNS(name)                                             \
 434static inline void cfqg_stats_mark_##name(struct cfqg_stats *stats)     \
 435{                                                                       \
 436        stats->flags |= (1 << CFQG_stats_##name);                       \
 437}                                                                       \
 438static inline void cfqg_stats_clear_##name(struct cfqg_stats *stats)    \
 439{                                                                       \
 440        stats->flags &= ~(1 << CFQG_stats_##name);                      \
 441}                                                                       \
 442static inline int cfqg_stats_##name(struct cfqg_stats *stats)           \
 443{                                                                       \
 444        return (stats->flags & (1 << CFQG_stats_##name)) != 0;          \
 445}                                                                       \
 446
 447CFQG_FLAG_FNS(waiting)
 448CFQG_FLAG_FNS(idling)
 449CFQG_FLAG_FNS(empty)
 450#undef CFQG_FLAG_FNS
 451
 452/* This should be called with the queue_lock held. */
 453static void cfqg_stats_update_group_wait_time(struct cfqg_stats *stats)
 454{
 455        unsigned long long now;
 456
 457        if (!cfqg_stats_waiting(stats))
 458                return;
 459
 460        now = sched_clock();
 461        if (time_after64(now, stats->start_group_wait_time))
 462                blkg_stat_add(&stats->group_wait_time,
 463                              now - stats->start_group_wait_time);
 464        cfqg_stats_clear_waiting(stats);
 465}
 466
 467/* This should be called with the queue_lock held. */
 468static void cfqg_stats_set_start_group_wait_time(struct cfq_group *cfqg,
 469                                                 struct cfq_group *curr_cfqg)
 470{
 471        struct cfqg_stats *stats = &cfqg->stats;
 472
 473        if (cfqg_stats_waiting(stats))
 474                return;
 475        if (cfqg == curr_cfqg)
 476                return;
 477        stats->start_group_wait_time = sched_clock();
 478        cfqg_stats_mark_waiting(stats);
 479}
 480
 481/* This should be called with the queue_lock held. */
 482static void cfqg_stats_end_empty_time(struct cfqg_stats *stats)
 483{
 484        unsigned long long now;
 485
 486        if (!cfqg_stats_empty(stats))
 487                return;
 488
 489        now = sched_clock();
 490        if (time_after64(now, stats->start_empty_time))
 491                blkg_stat_add(&stats->empty_time,
 492                              now - stats->start_empty_time);
 493        cfqg_stats_clear_empty(stats);
 494}
 495
 496static void cfqg_stats_update_dequeue(struct cfq_group *cfqg)
 497{
 498        blkg_stat_add(&cfqg->stats.dequeue, 1);
 499}
 500
 501static void cfqg_stats_set_start_empty_time(struct cfq_group *cfqg)
 502{
 503        struct cfqg_stats *stats = &cfqg->stats;
 504
 505        if (blkg_rwstat_sum(&stats->queued))
 506                return;
 507
 508        /*
 509         * group is already marked empty. This can happen if cfqq got new
 510         * request in parent group and moved to this group while being added
 511         * to service tree. Just ignore the event and move on.
 512         */
 513        if (cfqg_stats_empty(stats))
 514                return;
 515
 516        stats->start_empty_time = sched_clock();
 517        cfqg_stats_mark_empty(stats);
 518}
 519
 520static void cfqg_stats_update_idle_time(struct cfq_group *cfqg)
 521{
 522        struct cfqg_stats *stats = &cfqg->stats;
 523
 524        if (cfqg_stats_idling(stats)) {
 525                unsigned long long now = sched_clock();
 526
 527                if (time_after64(now, stats->start_idle_time))
 528                        blkg_stat_add(&stats->idle_time,
 529                                      now - stats->start_idle_time);
 530                cfqg_stats_clear_idling(stats);
 531        }
 532}
 533
 534static void cfqg_stats_set_start_idle_time(struct cfq_group *cfqg)
 535{
 536        struct cfqg_stats *stats = &cfqg->stats;
 537
 538        BUG_ON(cfqg_stats_idling(stats));
 539
 540        stats->start_idle_time = sched_clock();
 541        cfqg_stats_mark_idling(stats);
 542}
 543
 544static void cfqg_stats_update_avg_queue_size(struct cfq_group *cfqg)
 545{
 546        struct cfqg_stats *stats = &cfqg->stats;
 547
 548        blkg_stat_add(&stats->avg_queue_size_sum,
 549                      blkg_rwstat_sum(&stats->queued));
 550        blkg_stat_add(&stats->avg_queue_size_samples, 1);
 551        cfqg_stats_update_group_wait_time(stats);
 552}
 553
 554#else   /* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */
 555
 556static inline void cfqg_stats_set_start_group_wait_time(struct cfq_group *cfqg, struct cfq_group *curr_cfqg) { }
 557static inline void cfqg_stats_end_empty_time(struct cfqg_stats *stats) { }
 558static inline void cfqg_stats_update_dequeue(struct cfq_group *cfqg) { }
 559static inline void cfqg_stats_set_start_empty_time(struct cfq_group *cfqg) { }
 560static inline void cfqg_stats_update_idle_time(struct cfq_group *cfqg) { }
 561static inline void cfqg_stats_set_start_idle_time(struct cfq_group *cfqg) { }
 562static inline void cfqg_stats_update_avg_queue_size(struct cfq_group *cfqg) { }
 563
 564#endif  /* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */
 565
 566#ifdef CONFIG_CFQ_GROUP_IOSCHED
 567
 568static struct blkcg_policy blkcg_policy_cfq;
 569
 570static inline struct cfq_group *blkg_to_cfqg(struct blkcg_gq *blkg)
 571{
 572        return pd_to_cfqg(blkg_to_pd(blkg, &blkcg_policy_cfq));
 573}
 574
 575static inline void cfqg_get(struct cfq_group *cfqg)
 576{
 577        return blkg_get(cfqg_to_blkg(cfqg));
 578}
 579
 580static inline void cfqg_put(struct cfq_group *cfqg)
 581{
 582        return blkg_put(cfqg_to_blkg(cfqg));
 583}
 584
 585#define cfq_log_cfqq(cfqd, cfqq, fmt, args...)  do {                    \
 586        char __pbuf[128];                                               \
 587                                                                        \
 588        blkg_path(cfqg_to_blkg((cfqq)->cfqg), __pbuf, sizeof(__pbuf));  \
 589        blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \
 590                          cfq_cfqq_sync((cfqq)) ? 'S' : 'A',            \
 591                          __pbuf, ##args);                              \
 592} while (0)
 593
 594#define cfq_log_cfqg(cfqd, cfqg, fmt, args...)  do {                    \
 595        char __pbuf[128];                                               \
 596                                                                        \
 597        blkg_path(cfqg_to_blkg(cfqg), __pbuf, sizeof(__pbuf));          \
 598        blk_add_trace_msg((cfqd)->queue, "%s " fmt, __pbuf, ##args);    \
 599} while (0)
 600
 601static inline void cfqg_stats_update_io_add(struct cfq_group *cfqg,
 602                                            struct cfq_group *curr_cfqg, int rw)
 603{
 604        blkg_rwstat_add(&cfqg->stats.queued, rw, 1);
 605        cfqg_stats_end_empty_time(&cfqg->stats);
 606        cfqg_stats_set_start_group_wait_time(cfqg, curr_cfqg);
 607}
 608
 609static inline void cfqg_stats_update_timeslice_used(struct cfq_group *cfqg,
 610                        unsigned long time, unsigned long unaccounted_time)
 611{
 612        blkg_stat_add(&cfqg->stats.time, time);
 613#ifdef CONFIG_DEBUG_BLK_CGROUP
 614        blkg_stat_add(&cfqg->stats.unaccounted_time, unaccounted_time);
 615#endif
 616}
 617
 618static inline void cfqg_stats_update_io_remove(struct cfq_group *cfqg, int rw)
 619{
 620        blkg_rwstat_add(&cfqg->stats.queued, rw, -1);
 621}
 622
 623static inline void cfqg_stats_update_io_merged(struct cfq_group *cfqg, int rw)
 624{
 625        blkg_rwstat_add(&cfqg->stats.merged, rw, 1);
 626}
 627
 628static inline void cfqg_stats_update_dispatch(struct cfq_group *cfqg,
 629                                              uint64_t bytes, int rw)
 630{
 631        blkg_stat_add(&cfqg->stats.sectors, bytes >> 9);
 632        blkg_rwstat_add(&cfqg->stats.serviced, rw, 1);
 633        blkg_rwstat_add(&cfqg->stats.service_bytes, rw, bytes);
 634}
 635
 636static inline void cfqg_stats_update_completion(struct cfq_group *cfqg,
 637                        uint64_t start_time, uint64_t io_start_time, int rw)
 638{
 639        struct cfqg_stats *stats = &cfqg->stats;
 640        unsigned long long now = sched_clock();
 641
 642        if (time_after64(now, io_start_time))
 643                blkg_rwstat_add(&stats->service_time, rw, now - io_start_time);
 644        if (time_after64(io_start_time, start_time))
 645                blkg_rwstat_add(&stats->wait_time, rw,
 646                                io_start_time - start_time);
 647}
 648
 649static void cfq_pd_reset_stats(struct blkcg_gq *blkg)
 650{
 651        struct cfq_group *cfqg = blkg_to_cfqg(blkg);
 652        struct cfqg_stats *stats = &cfqg->stats;
 653
 654        /* queued stats shouldn't be cleared */
 655        blkg_rwstat_reset(&stats->service_bytes);
 656        blkg_rwstat_reset(&stats->serviced);
 657        blkg_rwstat_reset(&stats->merged);
 658        blkg_rwstat_reset(&stats->service_time);
 659        blkg_rwstat_reset(&stats->wait_time);
 660        blkg_stat_reset(&stats->time);
 661#ifdef CONFIG_DEBUG_BLK_CGROUP
 662        blkg_stat_reset(&stats->unaccounted_time);
 663        blkg_stat_reset(&stats->avg_queue_size_sum);
 664        blkg_stat_reset(&stats->avg_queue_size_samples);
 665        blkg_stat_reset(&stats->dequeue);
 666        blkg_stat_reset(&stats->group_wait_time);
 667        blkg_stat_reset(&stats->idle_time);
 668        blkg_stat_reset(&stats->empty_time);
 669#endif
 670}
 671
 672#else   /* CONFIG_CFQ_GROUP_IOSCHED */
 673
 674static inline void cfqg_get(struct cfq_group *cfqg) { }
 675static inline void cfqg_put(struct cfq_group *cfqg) { }
 676
 677#define cfq_log_cfqq(cfqd, cfqq, fmt, args...)  \
 678        blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
 679#define cfq_log_cfqg(cfqd, cfqg, fmt, args...)          do {} while (0)
 680
 681static inline void cfqg_stats_update_io_add(struct cfq_group *cfqg,
 682                        struct cfq_group *curr_cfqg, int rw) { }
 683static inline void cfqg_stats_update_timeslice_used(struct cfq_group *cfqg,
 684                        unsigned long time, unsigned long unaccounted_time) { }
 685static inline void cfqg_stats_update_io_remove(struct cfq_group *cfqg, int rw) { }
 686static inline void cfqg_stats_update_io_merged(struct cfq_group *cfqg, int rw) { }
 687static inline void cfqg_stats_update_dispatch(struct cfq_group *cfqg,
 688                                              uint64_t bytes, int rw) { }
 689static inline void cfqg_stats_update_completion(struct cfq_group *cfqg,
 690                        uint64_t start_time, uint64_t io_start_time, int rw) { }
 691
 692#endif  /* CONFIG_CFQ_GROUP_IOSCHED */
 693
 694#define cfq_log(cfqd, fmt, args...)     \
 695        blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
 696
 697/* Traverses through cfq group service trees */
 698#define for_each_cfqg_st(cfqg, i, j, st) \
 699        for (i = 0; i <= IDLE_WORKLOAD; i++) \
 700                for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
 701                        : &cfqg->service_tree_idle; \
 702                        (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \
 703                        (i == IDLE_WORKLOAD && j == 0); \
 704                        j++, st = i < IDLE_WORKLOAD ? \
 705                        &cfqg->service_trees[i][j]: NULL) \
 706
 707static inline bool cfq_io_thinktime_big(struct cfq_data *cfqd,
 708        struct cfq_ttime *ttime, bool group_idle)
 709{
 710        unsigned long slice;
 711        if (!sample_valid(ttime->ttime_samples))
 712                return false;
 713        if (group_idle)
 714                slice = cfqd->cfq_group_idle;
 715        else
 716                slice = cfqd->cfq_slice_idle;
 717        return ttime->ttime_mean > slice;
 718}
 719
 720static inline bool iops_mode(struct cfq_data *cfqd)
 721{
 722        /*
 723         * If we are not idling on queues and it is a NCQ drive, parallel
 724         * execution of requests is on and measuring time is not possible
 725         * in most of the cases until and unless we drive shallower queue
 726         * depths and that becomes a performance bottleneck. In such cases
 727         * switch to start providing fairness in terms of number of IOs.
 728         */
 729        if (!cfqd->cfq_slice_idle && cfqd->hw_tag)
 730                return true;
 731        else
 732                return false;
 733}
 734
 735static inline enum wl_prio_t cfqq_prio(struct cfq_queue *cfqq)
 736{
 737        if (cfq_class_idle(cfqq))
 738                return IDLE_WORKLOAD;
 739        if (cfq_class_rt(cfqq))
 740                return RT_WORKLOAD;
 741        return BE_WORKLOAD;
 742}
 743
 744
 745static enum wl_type_t cfqq_type(struct cfq_queue *cfqq)
 746{
 747        if (!cfq_cfqq_sync(cfqq))
 748                return ASYNC_WORKLOAD;
 749        if (!cfq_cfqq_idle_window(cfqq))
 750                return SYNC_NOIDLE_WORKLOAD;
 751        return SYNC_WORKLOAD;
 752}
 753
 754static inline int cfq_group_busy_queues_wl(enum wl_prio_t wl,
 755                                        struct cfq_data *cfqd,
 756                                        struct cfq_group *cfqg)
 757{
 758        if (wl == IDLE_WORKLOAD)
 759                return cfqg->service_tree_idle.count;
 760
 761        return cfqg->service_trees[wl][ASYNC_WORKLOAD].count
 762                + cfqg->service_trees[wl][SYNC_NOIDLE_WORKLOAD].count
 763                + cfqg->service_trees[wl][SYNC_WORKLOAD].count;
 764}
 765
 766static inline int cfqg_busy_async_queues(struct cfq_data *cfqd,
 767                                        struct cfq_group *cfqg)
 768{
 769        return cfqg->service_trees[RT_WORKLOAD][ASYNC_WORKLOAD].count
 770                + cfqg->service_trees[BE_WORKLOAD][ASYNC_WORKLOAD].count;
 771}
 772
 773static void cfq_dispatch_insert(struct request_queue *, struct request *);
 774static struct cfq_queue *cfq_get_queue(struct cfq_data *cfqd, bool is_sync,
 775                                       struct cfq_io_cq *cic, struct bio *bio,
 776                                       gfp_t gfp_mask);
 777
 778static inline struct cfq_io_cq *icq_to_cic(struct io_cq *icq)
 779{
 780        /* cic->icq is the first member, %NULL will convert to %NULL */
 781        return container_of(icq, struct cfq_io_cq, icq);
 782}
 783
 784static inline struct cfq_io_cq *cfq_cic_lookup(struct cfq_data *cfqd,
 785                                               struct io_context *ioc)
 786{
 787        if (ioc)
 788                return icq_to_cic(ioc_lookup_icq(ioc, cfqd->queue));
 789        return NULL;
 790}
 791
 792static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_cq *cic, bool is_sync)
 793{
 794        return cic->cfqq[is_sync];
 795}
 796
 797static inline void cic_set_cfqq(struct cfq_io_cq *cic, struct cfq_queue *cfqq,
 798                                bool is_sync)
 799{
 800        cic->cfqq[is_sync] = cfqq;
 801}
 802
 803static inline struct cfq_data *cic_to_cfqd(struct cfq_io_cq *cic)
 804{
 805        return cic->icq.q->elevator->elevator_data;
 806}
 807
 808/*
 809 * We regard a request as SYNC, if it's either a read or has the SYNC bit
 810 * set (in which case it could also be direct WRITE).
 811 */
 812static inline bool cfq_bio_sync(struct bio *bio)
 813{
 814        return bio_data_dir(bio) == READ || (bio->bi_rw & REQ_SYNC);
 815}
 816
 817/*
 818 * scheduler run of queue, if there are requests pending and no one in the
 819 * driver that will restart queueing
 820 */
 821static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
 822{
 823        if (cfqd->busy_queues) {
 824                cfq_log(cfqd, "schedule dispatch");
 825                kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work);
 826        }
 827}
 828
 829/*
 830 * Scale schedule slice based on io priority. Use the sync time slice only
 831 * if a queue is marked sync and has sync io queued. A sync queue with async
 832 * io only, should not get full sync slice length.
 833 */
 834static inline int cfq_prio_slice(struct cfq_data *cfqd, bool sync,
 835                                 unsigned short prio)
 836{
 837        const int base_slice = cfqd->cfq_slice[sync];
 838
 839        WARN_ON(prio >= IOPRIO_BE_NR);
 840
 841        return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio));
 842}
 843
 844static inline int
 845cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 846{
 847        return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
 848}
 849
 850static inline u64 cfq_scale_slice(unsigned long delta, struct cfq_group *cfqg)
 851{
 852        u64 d = delta << CFQ_SERVICE_SHIFT;
 853
 854        d = d * CFQ_WEIGHT_DEFAULT;
 855        do_div(d, cfqg->weight);
 856        return d;
 857}
 858
 859static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime)
 860{
 861        s64 delta = (s64)(vdisktime - min_vdisktime);
 862        if (delta > 0)
 863                min_vdisktime = vdisktime;
 864
 865        return min_vdisktime;
 866}
 867
 868static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime)
 869{
 870        s64 delta = (s64)(vdisktime - min_vdisktime);
 871        if (delta < 0)
 872                min_vdisktime = vdisktime;
 873
 874        return min_vdisktime;
 875}
 876
 877static void update_min_vdisktime(struct cfq_rb_root *st)
 878{
 879        struct cfq_group *cfqg;
 880
 881        if (st->left) {
 882                cfqg = rb_entry_cfqg(st->left);
 883                st->min_vdisktime = max_vdisktime(st->min_vdisktime,
 884                                                  cfqg->vdisktime);
 885        }
 886}
 887
 888/*
 889 * get averaged number of queues of RT/BE priority.
 890 * average is updated, with a formula that gives more weight to higher numbers,
 891 * to quickly follows sudden increases and decrease slowly
 892 */
 893
 894static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd,
 895                                        struct cfq_group *cfqg, bool rt)
 896{
 897        unsigned min_q, max_q;
 898        unsigned mult  = cfq_hist_divisor - 1;
 899        unsigned round = cfq_hist_divisor / 2;
 900        unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg);
 901
 902        min_q = min(cfqg->busy_queues_avg[rt], busy);
 903        max_q = max(cfqg->busy_queues_avg[rt], busy);
 904        cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) /
 905                cfq_hist_divisor;
 906        return cfqg->busy_queues_avg[rt];
 907}
 908
 909static inline unsigned
 910cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg)
 911{
 912        struct cfq_rb_root *st = &cfqd->grp_service_tree;
 913
 914        return cfqd->cfq_target_latency * cfqg->weight / st->total_weight;
 915}
 916
 917static inline unsigned
 918cfq_scaled_cfqq_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 919{
 920        unsigned slice = cfq_prio_to_slice(cfqd, cfqq);
 921        if (cfqd->cfq_latency) {
 922                /*
 923                 * interested queues (we consider only the ones with the same
 924                 * priority class in the cfq group)
 925                 */
 926                unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg,
 927                                                cfq_class_rt(cfqq));
 928                unsigned sync_slice = cfqd->cfq_slice[1];
 929                unsigned expect_latency = sync_slice * iq;
 930                unsigned group_slice = cfq_group_slice(cfqd, cfqq->cfqg);
 931
 932                if (expect_latency > group_slice) {
 933                        unsigned base_low_slice = 2 * cfqd->cfq_slice_idle;
 934                        /* scale low_slice according to IO priority
 935                         * and sync vs async */
 936                        unsigned low_slice =
 937                                min(slice, base_low_slice * slice / sync_slice);
 938                        /* the adapted slice value is scaled to fit all iqs
 939                         * into the target latency */
 940                        slice = max(slice * group_slice / expect_latency,
 941                                    low_slice);
 942                }
 943        }
 944        return slice;
 945}
 946
 947static inline void
 948cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 949{
 950        unsigned slice = cfq_scaled_cfqq_slice(cfqd, cfqq);
 951
 952        cfqq->slice_start = jiffies;
 953        cfqq->slice_end = jiffies + slice;
 954        cfqq->allocated_slice = slice;
 955        cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies);
 956}
 957
 958/*
 959 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
 960 * isn't valid until the first request from the dispatch is activated
 961 * and the slice time set.
 962 */
 963static inline bool cfq_slice_used(struct cfq_queue *cfqq)
 964{
 965        if (cfq_cfqq_slice_new(cfqq))
 966                return false;
 967        if (time_before(jiffies, cfqq->slice_end))
 968                return false;
 969
 970        return true;
 971}
 972
 973/*
 974 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
 975 * We choose the request that is closest to the head right now. Distance
 976 * behind the head is penalized and only allowed to a certain extent.
 977 */
 978static struct request *
 979cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last)
 980{
 981        sector_t s1, s2, d1 = 0, d2 = 0;
 982        unsigned long back_max;
 983#define CFQ_RQ1_WRAP    0x01 /* request 1 wraps */
 984#define CFQ_RQ2_WRAP    0x02 /* request 2 wraps */
 985        unsigned wrap = 0; /* bit mask: requests behind the disk head? */
 986
 987        if (rq1 == NULL || rq1 == rq2)
 988                return rq2;
 989        if (rq2 == NULL)
 990                return rq1;
 991
 992        if (rq_is_sync(rq1) != rq_is_sync(rq2))
 993                return rq_is_sync(rq1) ? rq1 : rq2;
 994
 995        if ((rq1->cmd_flags ^ rq2->cmd_flags) & REQ_PRIO)
 996                return rq1->cmd_flags & REQ_PRIO ? rq1 : rq2;
 997
 998        s1 = blk_rq_pos(rq1);
 999        s2 = blk_rq_pos(rq2);
1000
1001        /*
1002         * by definition, 1KiB is 2 sectors
1003         */
1004        back_max = cfqd->cfq_back_max * 2;
1005
1006        /*
1007         * Strict one way elevator _except_ in the case where we allow
1008         * short backward seeks which are biased as twice the cost of a
1009         * similar forward seek.
1010         */
1011        if (s1 >= last)
1012                d1 = s1 - last;
1013        else if (s1 + back_max >= last)
1014                d1 = (last - s1) * cfqd->cfq_back_penalty;
1015        else
1016                wrap |= CFQ_RQ1_WRAP;
1017
1018        if (s2 >= last)
1019                d2 = s2 - last;
1020        else if (s2 + back_max >= last)
1021                d2 = (last - s2) * cfqd->cfq_back_penalty;
1022        else
1023                wrap |= CFQ_RQ2_WRAP;
1024
1025        /* Found required data */
1026
1027        /*
1028         * By doing switch() on the bit mask "wrap" we avoid having to
1029         * check two variables for all permutations: --> faster!
1030         */
1031        switch (wrap) {
1032        case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
1033                if (d1 < d2)
1034                        return rq1;
1035                else if (d2 < d1)
1036                        return rq2;
1037                else {
1038                        if (s1 >= s2)
1039                                return rq1;
1040                        else
1041                                return rq2;
1042                }
1043
1044        case CFQ_RQ2_WRAP:
1045                return rq1;
1046        case CFQ_RQ1_WRAP:
1047                return rq2;
1048        case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */
1049        default:
1050                /*
1051                 * Since both rqs are wrapped,
1052                 * start with the one that's further behind head
1053                 * (--> only *one* back seek required),
1054                 * since back seek takes more time than forward.
1055                 */
1056                if (s1 <= s2)
1057                        return rq1;
1058                else
1059                        return rq2;
1060        }
1061}
1062
1063/*
1064 * The below is leftmost cache rbtree addon
1065 */
1066static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
1067{
1068        /* Service tree is empty */
1069        if (!root->count)
1070                return NULL;
1071
1072        if (!root->left)
1073                root->left = rb_first(&root->rb);
1074
1075        if (root->left)
1076                return rb_entry(root->left, struct cfq_queue, rb_node);
1077
1078        return NULL;
1079}
1080
1081static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root)
1082{
1083        if (!root->left)
1084                root->left = rb_first(&root->rb);
1085
1086        if (root->left)
1087                return rb_entry_cfqg(root->left);
1088
1089        return NULL;
1090}
1091
1092static void rb_erase_init(struct rb_node *n, struct rb_root *root)
1093{
1094        rb_erase(n, root);
1095        RB_CLEAR_NODE(n);
1096}
1097
1098static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)
1099{
1100        if (root->left == n)
1101                root->left = NULL;
1102        rb_erase_init(n, &root->rb);
1103        --root->count;
1104}
1105
1106/*
1107 * would be nice to take fifo expire time into account as well
1108 */
1109static struct request *
1110cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1111                  struct request *last)
1112{
1113        struct rb_node *rbnext = rb_next(&last->rb_node);
1114        struct rb_node *rbprev = rb_prev(&last->rb_node);
1115        struct request *next = NULL, *prev = NULL;
1116
1117        BUG_ON(RB_EMPTY_NODE(&last->rb_node));
1118
1119        if (rbprev)
1120                prev = rb_entry_rq(rbprev);
1121
1122        if (rbnext)
1123                next = rb_entry_rq(rbnext);
1124        else {
1125                rbnext = rb_first(&cfqq->sort_list);
1126                if (rbnext && rbnext != &last->rb_node)
1127                        next = rb_entry_rq(rbnext);
1128        }
1129
1130        return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last));
1131}
1132
1133static unsigned long cfq_slice_offset(struct cfq_data *cfqd,
1134                                      struct cfq_queue *cfqq)
1135{
1136        /*
1137         * just an approximation, should be ok.
1138         */
1139        return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) -
1140                       cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio));
1141}
1142
1143static inline s64
1144cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg)
1145{
1146        return cfqg->vdisktime - st->min_vdisktime;
1147}
1148
1149static void
1150__cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
1151{
1152        struct rb_node **node = &st->rb.rb_node;
1153        struct rb_node *parent = NULL;
1154        struct cfq_group *__cfqg;
1155        s64 key = cfqg_key(st, cfqg);
1156        int left = 1;
1157
1158        while (*node != NULL) {
1159                parent = *node;
1160                __cfqg = rb_entry_cfqg(parent);
1161
1162                if (key < cfqg_key(st, __cfqg))
1163                        node = &parent->rb_left;
1164                else {
1165                        node = &parent->rb_right;
1166                        left = 0;
1167                }
1168        }
1169
1170        if (left)
1171                st->left = &cfqg->rb_node;
1172
1173        rb_link_node(&cfqg->rb_node, parent, node);
1174        rb_insert_color(&cfqg->rb_node, &st->rb);
1175}
1176
1177static void
1178cfq_update_group_weight(struct cfq_group *cfqg)
1179{
1180        BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
1181        if (cfqg->new_weight) {
1182                cfqg->weight = cfqg->new_weight;
1183                cfqg->new_weight = 0;
1184        }
1185}
1186
1187static void
1188cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
1189{
1190        BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
1191
1192        cfq_update_group_weight(cfqg);
1193        __cfq_group_service_tree_add(st, cfqg);
1194        st->total_weight += cfqg->weight;
1195}
1196
1197static void
1198cfq_group_notify_queue_add(struct cfq_data *cfqd, struct cfq_group *cfqg)
1199{
1200        struct cfq_rb_root *st = &cfqd->grp_service_tree;
1201        struct cfq_group *__cfqg;
1202        struct rb_node *n;
1203
1204        cfqg->nr_cfqq++;
1205        if (!RB_EMPTY_NODE(&cfqg->rb_node))
1206                return;
1207
1208        /*
1209         * Currently put the group at the end. Later implement something
1210         * so that groups get lesser vtime based on their weights, so that
1211         * if group does not loose all if it was not continuously backlogged.
1212         */
1213        n = rb_last(&st->rb);
1214        if (n) {
1215                __cfqg = rb_entry_cfqg(n);
1216                cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY;
1217        } else
1218                cfqg->vdisktime = st->min_vdisktime;
1219        cfq_group_service_tree_add(st, cfqg);
1220}
1221
1222static void
1223cfq_group_service_tree_del(struct cfq_rb_root *st, struct cfq_group *cfqg)
1224{
1225        st->total_weight -= cfqg->weight;
1226        if (!RB_EMPTY_NODE(&cfqg->rb_node))
1227                cfq_rb_erase(&cfqg->rb_node, st);
1228}
1229
1230static void
1231cfq_group_notify_queue_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
1232{
1233        struct cfq_rb_root *st = &cfqd->grp_service_tree;
1234
1235        BUG_ON(cfqg->nr_cfqq < 1);
1236        cfqg->nr_cfqq--;
1237
1238        /* If there are other cfq queues under this group, don't delete it */
1239        if (cfqg->nr_cfqq)
1240                return;
1241
1242        cfq_log_cfqg(cfqd, cfqg, "del_from_rr group");
1243        cfq_group_service_tree_del(st, cfqg);
1244        cfqg->saved_workload_slice = 0;
1245        cfqg_stats_update_dequeue(cfqg);
1246}
1247
1248static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq,
1249                                                unsigned int *unaccounted_time)
1250{
1251        unsigned int slice_used;
1252
1253        /*
1254         * Queue got expired before even a single request completed or
1255         * got expired immediately after first request completion.
1256         */
1257        if (!cfqq->slice_start || cfqq->slice_start == jiffies) {
1258                /*
1259                 * Also charge the seek time incurred to the group, otherwise
1260                 * if there are mutiple queues in the group, each can dispatch
1261                 * a single request on seeky media and cause lots of seek time
1262                 * and group will never know it.
1263                 */
1264                slice_used = max_t(unsigned, (jiffies - cfqq->dispatch_start),
1265                                        1);
1266        } else {
1267                slice_used = jiffies - cfqq->slice_start;
1268                if (slice_used > cfqq->allocated_slice) {
1269                        *unaccounted_time = slice_used - cfqq->allocated_slice;
1270                        slice_used = cfqq->allocated_slice;
1271                }
1272                if (time_after(cfqq->slice_start, cfqq->dispatch_start))
1273                        *unaccounted_time += cfqq->slice_start -
1274                                        cfqq->dispatch_start;
1275        }
1276
1277        return slice_used;
1278}
1279
1280static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
1281                                struct cfq_queue *cfqq)
1282{
1283        struct cfq_rb_root *st = &cfqd->grp_service_tree;
1284        unsigned int used_sl, charge, unaccounted_sl = 0;
1285        int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg)
1286                        - cfqg->service_tree_idle.count;
1287
1288        BUG_ON(nr_sync < 0);
1289        used_sl = charge = cfq_cfqq_slice_usage(cfqq, &unaccounted_sl);
1290
1291        if (iops_mode(cfqd))
1292                charge = cfqq->slice_dispatch;
1293        else if (!cfq_cfqq_sync(cfqq) && !nr_sync)
1294                charge = cfqq->allocated_slice;
1295
1296        /* Can't update vdisktime while group is on service tree */
1297        cfq_group_service_tree_del(st, cfqg);
1298        cfqg->vdisktime += cfq_scale_slice(charge, cfqg);
1299        /* If a new weight was requested, update now, off tree */
1300        cfq_group_service_tree_add(st, cfqg);
1301
1302        /* This group is being expired. Save the context */
1303        if (time_after(cfqd->workload_expires, jiffies)) {
1304                cfqg->saved_workload_slice = cfqd->workload_expires
1305                                                - jiffies;
1306                cfqg->saved_workload = cfqd->serving_type;
1307                cfqg->saved_serving_prio = cfqd->serving_prio;
1308        } else
1309                cfqg->saved_workload_slice = 0;
1310
1311        cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime,
1312                                        st->min_vdisktime);
1313        cfq_log_cfqq(cfqq->cfqd, cfqq,
1314                     "sl_used=%u disp=%u charge=%u iops=%u sect=%lu",
1315                     used_sl, cfqq->slice_dispatch, charge,
1316                     iops_mode(cfqd), cfqq->nr_sectors);
1317        cfqg_stats_update_timeslice_used(cfqg, used_sl, unaccounted_sl);
1318        cfqg_stats_set_start_empty_time(cfqg);
1319}
1320
1321/**
1322 * cfq_init_cfqg_base - initialize base part of a cfq_group
1323 * @cfqg: cfq_group to initialize
1324 *
1325 * Initialize the base part which is used whether %CONFIG_CFQ_GROUP_IOSCHED
1326 * is enabled or not.
1327 */
1328static void cfq_init_cfqg_base(struct cfq_group *cfqg)
1329{
1330        struct cfq_rb_root *st;
1331        int i, j;
1332
1333        for_each_cfqg_st(cfqg, i, j, st)
1334                *st = CFQ_RB_ROOT;
1335        RB_CLEAR_NODE(&cfqg->rb_node);
1336
1337        cfqg->ttime.last_end_request = jiffies;
1338}
1339
1340#ifdef CONFIG_CFQ_GROUP_IOSCHED
1341static void cfq_pd_init(struct blkcg_gq *blkg)
1342{
1343        struct cfq_group *cfqg = blkg_to_cfqg(blkg);
1344
1345        cfq_init_cfqg_base(cfqg);
1346        cfqg->weight = blkg->blkcg->cfq_weight;
1347}
1348
1349/*
1350 * Search for the cfq group current task belongs to. request_queue lock must
1351 * be held.
1352 */
1353static struct cfq_group *cfq_lookup_create_cfqg(struct cfq_data *cfqd,
1354                                                struct blkcg *blkcg)
1355{
1356        struct request_queue *q = cfqd->queue;
1357        struct cfq_group *cfqg = NULL;
1358
1359        /* avoid lookup for the common case where there's no blkcg */
1360        if (blkcg == &blkcg_root) {
1361                cfqg = cfqd->root_group;
1362        } else {
1363                struct blkcg_gq *blkg;
1364
1365                blkg = blkg_lookup_create(blkcg, q);
1366                if (!IS_ERR(blkg))
1367                        cfqg = blkg_to_cfqg(blkg);
1368        }
1369
1370        return cfqg;
1371}
1372
1373static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg)
1374{
1375        /* Currently, all async queues are mapped to root group */
1376        if (!cfq_cfqq_sync(cfqq))
1377                cfqg = cfqq->cfqd->root_group;
1378
1379        cfqq->cfqg = cfqg;
1380        /* cfqq reference on cfqg */
1381        cfqg_get(cfqg);
1382}
1383
1384static u64 cfqg_prfill_weight_device(struct seq_file *sf,
1385                                     struct blkg_policy_data *pd, int off)
1386{
1387        struct cfq_group *cfqg = pd_to_cfqg(pd);
1388
1389        if (!cfqg->dev_weight)
1390                return 0;
1391        return __blkg_prfill_u64(sf, pd, cfqg->dev_weight);
1392}
1393
1394static int cfqg_print_weight_device(struct cgroup *cgrp, struct cftype *cft,
1395                                    struct seq_file *sf)
1396{
1397        blkcg_print_blkgs(sf, cgroup_to_blkcg(cgrp),
1398                          cfqg_prfill_weight_device, &blkcg_policy_cfq, 0,
1399                          false);
1400        return 0;
1401}
1402
1403static int cfq_print_weight(struct cgroup *cgrp, struct cftype *cft,
1404                            struct seq_file *sf)
1405{
1406        seq_printf(sf, "%u\n", cgroup_to_blkcg(cgrp)->cfq_weight);
1407        return 0;
1408}
1409
1410static int cfqg_set_weight_device(struct cgroup *cgrp, struct cftype *cft,
1411                                  const char *buf)
1412{
1413        struct blkcg *blkcg = cgroup_to_blkcg(cgrp);
1414        struct blkg_conf_ctx ctx;
1415        struct cfq_group *cfqg;
1416        int ret;
1417
1418        ret = blkg_conf_prep(blkcg, &blkcg_policy_cfq, buf, &ctx);
1419        if (ret)
1420                return ret;
1421
1422        ret = -EINVAL;
1423        cfqg = blkg_to_cfqg(ctx.blkg);
1424        if (!ctx.v || (ctx.v >= CFQ_WEIGHT_MIN && ctx.v <= CFQ_WEIGHT_MAX)) {
1425                cfqg->dev_weight = ctx.v;
1426                cfqg->new_weight = cfqg->dev_weight ?: blkcg->cfq_weight;
1427                ret = 0;
1428        }
1429
1430        blkg_conf_finish(&ctx);
1431        return ret;
1432}
1433
1434static int cfq_set_weight(struct cgroup *cgrp, struct cftype *cft, u64 val)
1435{
1436        struct blkcg *blkcg = cgroup_to_blkcg(cgrp);
1437        struct blkcg_gq *blkg;
1438        struct hlist_node *n;
1439
1440        if (val < CFQ_WEIGHT_MIN || val > CFQ_WEIGHT_MAX)
1441                return -EINVAL;
1442
1443        spin_lock_irq(&blkcg->lock);
1444        blkcg->cfq_weight = (unsigned int)val;
1445
1446        hlist_for_each_entry(blkg, n, &blkcg->blkg_list, blkcg_node) {
1447                struct cfq_group *cfqg = blkg_to_cfqg(blkg);
1448
1449                if (cfqg && !cfqg->dev_weight)
1450                        cfqg->new_weight = blkcg->cfq_weight;
1451        }
1452
1453        spin_unlock_irq(&blkcg->lock);
1454        return 0;
1455}
1456
1457static int cfqg_print_stat(struct cgroup *cgrp, struct cftype *cft,
1458                           struct seq_file *sf)
1459{
1460        struct blkcg *blkcg = cgroup_to_blkcg(cgrp);
1461
1462        blkcg_print_blkgs(sf, blkcg, blkg_prfill_stat, &blkcg_policy_cfq,
1463                          cft->private, false);
1464        return 0;
1465}
1466
1467static int cfqg_print_rwstat(struct cgroup *cgrp, struct cftype *cft,
1468                             struct seq_file *sf)
1469{
1470        struct blkcg *blkcg = cgroup_to_blkcg(cgrp);
1471
1472        blkcg_print_blkgs(sf, blkcg, blkg_prfill_rwstat, &blkcg_policy_cfq,
1473                          cft->private, true);
1474        return 0;
1475}
1476
1477#ifdef CONFIG_DEBUG_BLK_CGROUP
1478static u64 cfqg_prfill_avg_queue_size(struct seq_file *sf,
1479                                      struct blkg_policy_data *pd, int off)
1480{
1481        struct cfq_group *cfqg = pd_to_cfqg(pd);
1482        u64 samples = blkg_stat_read(&cfqg->stats.avg_queue_size_samples);
1483        u64 v = 0;
1484
1485        if (samples) {
1486                v = blkg_stat_read(&cfqg->stats.avg_queue_size_sum);
1487                do_div(v, samples);
1488        }
1489        __blkg_prfill_u64(sf, pd, v);
1490        return 0;
1491}
1492
1493/* print avg_queue_size */
1494static int cfqg_print_avg_queue_size(struct cgroup *cgrp, struct cftype *cft,
1495                                     struct seq_file *sf)
1496{
1497        struct blkcg *blkcg = cgroup_to_blkcg(cgrp);
1498
1499        blkcg_print_blkgs(sf, blkcg, cfqg_prfill_avg_queue_size,
1500                          &blkcg_policy_cfq, 0, false);
1501        return 0;
1502}
1503#endif  /* CONFIG_DEBUG_BLK_CGROUP */
1504
1505static struct cftype cfq_blkcg_files[] = {
1506        {
1507                .name = "weight_device",
1508                .read_seq_string = cfqg_print_weight_device,
1509                .write_string = cfqg_set_weight_device,
1510                .max_write_len = 256,
1511        },
1512        {
1513                .name = "weight",
1514                .read_seq_string = cfq_print_weight,
1515                .write_u64 = cfq_set_weight,
1516        },
1517        {
1518                .name = "time",
1519                .private = offsetof(struct cfq_group, stats.time),
1520                .read_seq_string = cfqg_print_stat,
1521        },
1522        {
1523                .name = "sectors",
1524                .private = offsetof(struct cfq_group, stats.sectors),
1525                .read_seq_string = cfqg_print_stat,
1526        },
1527        {
1528                .name = "io_service_bytes",
1529                .private = offsetof(struct cfq_group, stats.service_bytes),
1530                .read_seq_string = cfqg_print_rwstat,
1531        },
1532        {
1533                .name = "io_serviced",
1534                .private = offsetof(struct cfq_group, stats.serviced),
1535                .read_seq_string = cfqg_print_rwstat,
1536        },
1537        {
1538                .name = "io_service_time",
1539                .private = offsetof(struct cfq_group, stats.service_time),
1540                .read_seq_string = cfqg_print_rwstat,
1541        },
1542        {
1543                .name = "io_wait_time",
1544                .private = offsetof(struct cfq_group, stats.wait_time),
1545                .read_seq_string = cfqg_print_rwstat,
1546        },
1547        {
1548                .name = "io_merged",
1549                .private = offsetof(struct cfq_group, stats.merged),
1550                .read_seq_string = cfqg_print_rwstat,
1551        },
1552        {
1553                .name = "io_queued",
1554                .private = offsetof(struct cfq_group, stats.queued),
1555                .read_seq_string = cfqg_print_rwstat,
1556        },
1557#ifdef CONFIG_DEBUG_BLK_CGROUP
1558        {
1559                .name = "avg_queue_size",
1560                .read_seq_string = cfqg_print_avg_queue_size,
1561        },
1562        {
1563                .name = "group_wait_time",
1564                .private = offsetof(struct cfq_group, stats.group_wait_time),
1565                .read_seq_string = cfqg_print_stat,
1566        },
1567        {
1568                .name = "idle_time",
1569                .private = offsetof(struct cfq_group, stats.idle_time),
1570                .read_seq_string = cfqg_print_stat,
1571        },
1572        {
1573                .name = "empty_time",
1574                .private = offsetof(struct cfq_group, stats.empty_time),
1575                .read_seq_string = cfqg_print_stat,
1576        },
1577        {
1578                .name = "dequeue",
1579                .private = offsetof(struct cfq_group, stats.dequeue),
1580                .read_seq_string = cfqg_print_stat,
1581        },
1582        {
1583                .name = "unaccounted_time",
1584                .private = offsetof(struct cfq_group, stats.unaccounted_time),
1585                .read_seq_string = cfqg_print_stat,
1586        },
1587#endif  /* CONFIG_DEBUG_BLK_CGROUP */
1588        { }     /* terminate */
1589};
1590#else /* GROUP_IOSCHED */
1591static struct cfq_group *cfq_lookup_create_cfqg(struct cfq_data *cfqd,
1592                                                struct blkcg *blkcg)
1593{
1594        return cfqd->root_group;
1595}
1596
1597static inline void
1598cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) {
1599        cfqq->cfqg = cfqg;
1600}
1601
1602#endif /* GROUP_IOSCHED */
1603
1604/*
1605 * The cfqd->service_trees holds all pending cfq_queue's that have
1606 * requests waiting to be processed. It is sorted in the order that
1607 * we will service the queues.
1608 */
1609static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1610                                 bool add_front)
1611{
1612        struct rb_node **p, *parent;
1613        struct cfq_queue *__cfqq;
1614        unsigned long rb_key;
1615        struct cfq_rb_root *service_tree;
1616        int left;
1617        int new_cfqq = 1;
1618
1619        service_tree = service_tree_for(cfqq->cfqg, cfqq_prio(cfqq),
1620                                                cfqq_type(cfqq));
1621        if (cfq_class_idle(cfqq)) {
1622                rb_key = CFQ_IDLE_DELAY;
1623                parent = rb_last(&service_tree->rb);
1624                if (parent && parent != &cfqq->rb_node) {
1625                        __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
1626                        rb_key += __cfqq->rb_key;
1627                } else
1628                        rb_key += jiffies;
1629        } else if (!add_front) {
1630                /*
1631                 * Get our rb key offset. Subtract any residual slice
1632                 * value carried from last service. A negative resid
1633                 * count indicates slice overrun, and this should position
1634                 * the next service time further away in the tree.
1635                 */
1636                rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies;
1637                rb_key -= cfqq->slice_resid;
1638                cfqq->slice_resid = 0;
1639        } else {
1640                rb_key = -HZ;
1641                __cfqq = cfq_rb_first(service_tree);
1642                rb_key += __cfqq ? __cfqq->rb_key : jiffies;
1643        }
1644
1645        if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
1646                new_cfqq = 0;
1647                /*
1648                 * same position, nothing more to do
1649                 */
1650                if (rb_key == cfqq->rb_key &&
1651                    cfqq->service_tree == service_tree)
1652                        return;
1653
1654                cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
1655                cfqq->service_tree = NULL;
1656        }
1657
1658        left = 1;
1659        parent = NULL;
1660        cfqq->service_tree = service_tree;
1661        p = &service_tree->rb.rb_node;
1662        while (*p) {
1663                struct rb_node **n;
1664
1665                parent = *p;
1666                __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
1667
1668                /*
1669                 * sort by key, that represents service time.
1670                 */
1671                if (time_before(rb_key, __cfqq->rb_key))
1672                        n = &(*p)->rb_left;
1673                else {
1674                        n = &(*p)->rb_right;
1675                        left = 0;
1676                }
1677
1678                p = n;
1679        }
1680
1681        if (left)
1682                service_tree->left = &cfqq->rb_node;
1683
1684        cfqq->rb_key = rb_key;
1685        rb_link_node(&cfqq->rb_node, parent, p);
1686        rb_insert_color(&cfqq->rb_node, &service_tree->rb);
1687        service_tree->count++;
1688        if (add_front || !new_cfqq)
1689                return;
1690        cfq_group_notify_queue_add(cfqd, cfqq->cfqg);
1691}
1692
1693static struct cfq_queue *
1694cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root,
1695                     sector_t sector, struct rb_node **ret_parent,
1696                     struct rb_node ***rb_link)
1697{
1698        struct rb_node **p, *parent;
1699        struct cfq_queue *cfqq = NULL;
1700
1701        parent = NULL;
1702        p = &root->rb_node;
1703        while (*p) {
1704                struct rb_node **n;
1705
1706                parent = *p;
1707                cfqq = rb_entry(parent, struct cfq_queue, p_node);
1708
1709                /*
1710                 * Sort strictly based on sector.  Smallest to the left,
1711                 * largest to the right.
1712                 */
1713                if (sector > blk_rq_pos(cfqq->next_rq))
1714                        n = &(*p)->rb_right;
1715                else if (sector < blk_rq_pos(cfqq->next_rq))
1716                        n = &(*p)->rb_left;
1717                else
1718                        break;
1719                p = n;
1720                cfqq = NULL;
1721        }
1722
1723        *ret_parent = parent;
1724        if (rb_link)
1725                *rb_link = p;
1726        return cfqq;
1727}
1728
1729static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1730{
1731        struct rb_node **p, *parent;
1732        struct cfq_queue *__cfqq;
1733
1734        if (cfqq->p_root) {
1735                rb_erase(&cfqq->p_node, cfqq->p_root);
1736                cfqq->p_root = NULL;
1737        }
1738
1739        if (cfq_class_idle(cfqq))
1740                return;
1741        if (!cfqq->next_rq)
1742                return;
1743
1744        cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
1745        __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root,
1746                                      blk_rq_pos(cfqq->next_rq), &parent, &p);
1747        if (!__cfqq) {
1748                rb_link_node(&cfqq->p_node, parent, p);
1749                rb_insert_color(&cfqq->p_node, cfqq->p_root);
1750        } else
1751                cfqq->p_root = NULL;
1752}
1753
1754/*
1755 * Update cfqq's position in the service tree.
1756 */
1757static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1758{
1759        /*
1760         * Resorting requires the cfqq to be on the RR list already.
1761         */
1762        if (cfq_cfqq_on_rr(cfqq)) {
1763                cfq_service_tree_add(cfqd, cfqq, 0);
1764                cfq_prio_tree_add(cfqd, cfqq);
1765        }
1766}
1767
1768/*
1769 * add to busy list of queues for service, trying to be fair in ordering
1770 * the pending list according to last request service
1771 */
1772static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1773{
1774        cfq_log_cfqq(cfqd, cfqq, "add_to_rr");
1775        BUG_ON(cfq_cfqq_on_rr(cfqq));
1776        cfq_mark_cfqq_on_rr(cfqq);
1777        cfqd->busy_queues++;
1778        if (cfq_cfqq_sync(cfqq))
1779                cfqd->busy_sync_queues++;
1780
1781        cfq_resort_rr_list(cfqd, cfqq);
1782}
1783
1784/*
1785 * Called when the cfqq no longer has requests pending, remove it from
1786 * the service tree.
1787 */
1788static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1789{
1790        cfq_log_cfqq(cfqd, cfqq, "del_from_rr");
1791        BUG_ON(!cfq_cfqq_on_rr(cfqq));
1792        cfq_clear_cfqq_on_rr(cfqq);
1793
1794        if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
1795                cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
1796                cfqq->service_tree = NULL;
1797        }
1798        if (cfqq->p_root) {
1799                rb_erase(&cfqq->p_node, cfqq->p_root);
1800                cfqq->p_root = NULL;
1801        }
1802
1803        cfq_group_notify_queue_del(cfqd, cfqq->cfqg);
1804        BUG_ON(!cfqd->busy_queues);
1805        cfqd->busy_queues--;
1806        if (cfq_cfqq_sync(cfqq))
1807                cfqd->busy_sync_queues--;
1808}
1809
1810/*
1811 * rb tree support functions
1812 */
1813static void cfq_del_rq_rb(struct request *rq)
1814{
1815        struct cfq_queue *cfqq = RQ_CFQQ(rq);
1816        const int sync = rq_is_sync(rq);
1817
1818        BUG_ON(!cfqq->queued[sync]);
1819        cfqq->queued[sync]--;
1820
1821        elv_rb_del(&cfqq->sort_list, rq);
1822
1823        if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) {
1824                /*
1825                 * Queue will be deleted from service tree when we actually
1826                 * expire it later. Right now just remove it from prio tree
1827                 * as it is empty.
1828                 */
1829                if (cfqq->p_root) {
1830                        rb_erase(&cfqq->p_node, cfqq->p_root);
1831                        cfqq->p_root = NULL;
1832                }
1833        }
1834}
1835
1836static void cfq_add_rq_rb(struct request *rq)
1837{
1838        struct cfq_queue *cfqq = RQ_CFQQ(rq);
1839        struct cfq_data *cfqd = cfqq->cfqd;
1840        struct request *prev;
1841
1842        cfqq->queued[rq_is_sync(rq)]++;
1843
1844        elv_rb_add(&cfqq->sort_list, rq);
1845
1846        if (!cfq_cfqq_on_rr(cfqq))
1847                cfq_add_cfqq_rr(cfqd, cfqq);
1848
1849        /*
1850         * check if this request is a better next-serve candidate
1851         */
1852        prev = cfqq->next_rq;
1853        cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position);
1854
1855        /*
1856         * adjust priority tree position, if ->next_rq changes
1857         */
1858        if (prev != cfqq->next_rq)
1859                cfq_prio_tree_add(cfqd, cfqq);
1860
1861        BUG_ON(!cfqq->next_rq);
1862}
1863
1864static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq)
1865{
1866        elv_rb_del(&cfqq->sort_list, rq);
1867        cfqq->queued[rq_is_sync(rq)]--;
1868        cfqg_stats_update_io_remove(RQ_CFQG(rq), rq->cmd_flags);
1869        cfq_add_rq_rb(rq);
1870        cfqg_stats_update_io_add(RQ_CFQG(rq), cfqq->cfqd->serving_group,
1871                                 rq->cmd_flags);
1872}
1873
1874static struct request *
1875cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
1876{
1877        struct task_struct *tsk = current;
1878        struct cfq_io_cq *cic;
1879        struct cfq_queue *cfqq;
1880
1881        cic = cfq_cic_lookup(cfqd, tsk->io_context);
1882        if (!cic)
1883                return NULL;
1884
1885        cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
1886        if (cfqq) {
1887                sector_t sector = bio->bi_sector + bio_sectors(bio);
1888
1889                return elv_rb_find(&cfqq->sort_list, sector);
1890        }
1891
1892        return NULL;
1893}
1894
1895static void cfq_activate_request(struct request_queue *q, struct request *rq)
1896{
1897        struct cfq_data *cfqd = q->elevator->elevator_data;
1898
1899        cfqd->rq_in_driver++;
1900        cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
1901                                                cfqd->rq_in_driver);
1902
1903        cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
1904}
1905
1906static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
1907{
1908        struct cfq_data *cfqd = q->elevator->elevator_data;
1909
1910        WARN_ON(!cfqd->rq_in_driver);
1911        cfqd->rq_in_driver--;
1912        cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
1913                                                cfqd->rq_in_driver);
1914}
1915
1916static void cfq_remove_request(struct request *rq)
1917{
1918        struct cfq_queue *cfqq = RQ_CFQQ(rq);
1919
1920        if (cfqq->next_rq == rq)
1921                cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq);
1922
1923        list_del_init(&rq->queuelist);
1924        cfq_del_rq_rb(rq);
1925
1926        cfqq->cfqd->rq_queued--;
1927        cfqg_stats_update_io_remove(RQ_CFQG(rq), rq->cmd_flags);
1928        if (rq->cmd_flags & REQ_PRIO) {
1929                WARN_ON(!cfqq->prio_pending);
1930                cfqq->prio_pending--;
1931        }
1932}
1933
1934static int cfq_merge(struct request_queue *q, struct request **req,
1935                     struct bio *bio)
1936{
1937        struct cfq_data *cfqd = q->elevator->elevator_data;
1938        struct request *__rq;
1939
1940        __rq = cfq_find_rq_fmerge(cfqd, bio);
1941        if (__rq && elv_rq_merge_ok(__rq, bio)) {
1942                *req = __rq;
1943                return ELEVATOR_FRONT_MERGE;
1944        }
1945
1946        return ELEVATOR_NO_MERGE;
1947}
1948
1949static void cfq_merged_request(struct request_queue *q, struct request *req,
1950                               int type)
1951{
1952        if (type == ELEVATOR_FRONT_MERGE) {
1953                struct cfq_queue *cfqq = RQ_CFQQ(req);
1954
1955                cfq_reposition_rq_rb(cfqq, req);
1956        }
1957}
1958
1959static void cfq_bio_merged(struct request_queue *q, struct request *req,
1960                                struct bio *bio)
1961{
1962        cfqg_stats_update_io_merged(RQ_CFQG(req), bio->bi_rw);
1963}
1964
1965static void
1966cfq_merged_requests(struct request_queue *q, struct request *rq,
1967                    struct request *next)
1968{
1969        struct cfq_queue *cfqq = RQ_CFQQ(rq);
1970        struct cfq_data *cfqd = q->elevator->elevator_data;
1971
1972        /*
1973         * reposition in fifo if next is older than rq
1974         */
1975        if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
1976            time_before(rq_fifo_time(next), rq_fifo_time(rq)) &&
1977            cfqq == RQ_CFQQ(next)) {
1978                list_move(&rq->queuelist, &next->queuelist);
1979                rq_set_fifo_time(rq, rq_fifo_time(next));
1980        }
1981
1982        if (cfqq->next_rq == next)
1983                cfqq->next_rq = rq;
1984        cfq_remove_request(next);
1985        cfqg_stats_update_io_merged(RQ_CFQG(rq), next->cmd_flags);
1986
1987        cfqq = RQ_CFQQ(next);
1988        /*
1989         * all requests of this queue are merged to other queues, delete it
1990         * from the service tree. If it's the active_queue,
1991         * cfq_dispatch_requests() will choose to expire it or do idle
1992         */
1993        if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list) &&
1994            cfqq != cfqd->active_queue)
1995                cfq_del_cfqq_rr(cfqd, cfqq);
1996}
1997
1998static int cfq_allow_merge(struct request_queue *q, struct request *rq,
1999                           struct bio *bio)
2000{
2001        struct cfq_data *cfqd = q->elevator->elevator_data;
2002        struct cfq_io_cq *cic;
2003        struct cfq_queue *cfqq;
2004
2005        /*
2006         * Disallow merge of a sync bio into an async request.
2007         */
2008        if (cfq_bio_sync(bio) && !rq_is_sync(rq))
2009                return false;
2010
2011        /*
2012         * Lookup the cfqq that this bio will be queued with and allow
2013         * merge only if rq is queued there.
2014         */
2015        cic = cfq_cic_lookup(cfqd, current->io_context);
2016        if (!cic)
2017                return false;
2018
2019        cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
2020        return cfqq == RQ_CFQQ(rq);
2021}
2022
2023static inline void cfq_del_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2024{
2025        del_timer(&cfqd->idle_slice_timer);
2026        cfqg_stats_update_idle_time(cfqq->cfqg);
2027}
2028
2029static void __cfq_set_active_queue(struct cfq_data *cfqd,
2030                                   struct cfq_queue *cfqq)
2031{
2032        if (cfqq) {
2033                cfq_log_cfqq(cfqd, cfqq, "set_active wl_prio:%d wl_type:%d",
2034                                cfqd->serving_prio, cfqd->serving_type);
2035                cfqg_stats_update_avg_queue_size(cfqq->cfqg);
2036                cfqq->slice_start = 0;
2037                cfqq->dispatch_start = jiffies;
2038                cfqq->allocated_slice = 0;
2039                cfqq->slice_end = 0;
2040                cfqq->slice_dispatch = 0;
2041                cfqq->nr_sectors = 0;
2042
2043                cfq_clear_cfqq_wait_request(cfqq);
2044                cfq_clear_cfqq_must_dispatch(cfqq);
2045                cfq_clear_cfqq_must_alloc_slice(cfqq);
2046                cfq_clear_cfqq_fifo_expire(cfqq);
2047                cfq_mark_cfqq_slice_new(cfqq);
2048
2049                cfq_del_timer(cfqd, cfqq);
2050        }
2051
2052        cfqd->active_queue = cfqq;
2053}
2054
2055/*
2056 * current cfqq expired its slice (or was too idle), select new one
2057 */
2058static void
2059__cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2060                    bool timed_out)
2061{
2062        cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out);
2063
2064        if (cfq_cfqq_wait_request(cfqq))
2065                cfq_del_timer(cfqd, cfqq);
2066
2067        cfq_clear_cfqq_wait_request(cfqq);
2068        cfq_clear_cfqq_wait_busy(cfqq);
2069
2070        /*
2071         * If this cfqq is shared between multiple processes, check to
2072         * make sure that those processes are still issuing I/Os within
2073         * the mean seek distance.  If not, it may be time to break the
2074         * queues apart again.
2075         */
2076        if (cfq_cfqq_coop(cfqq) && CFQQ_SEEKY(cfqq))
2077                cfq_mark_cfqq_split_coop(cfqq);
2078
2079        /*
2080         * store what was left of this slice, if the queue idled/timed out
2081         */
2082        if (timed_out) {
2083                if (cfq_cfqq_slice_new(cfqq))
2084                        cfqq->slice_resid = cfq_scaled_cfqq_slice(cfqd, cfqq);
2085                else
2086                        cfqq->slice_resid = cfqq->slice_end - jiffies;
2087                cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
2088        }
2089
2090        cfq_group_served(cfqd, cfqq->cfqg, cfqq);
2091
2092        if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
2093                cfq_del_cfqq_rr(cfqd, cfqq);
2094
2095        cfq_resort_rr_list(cfqd, cfqq);
2096
2097        if (cfqq == cfqd->active_queue)
2098                cfqd->active_queue = NULL;
2099
2100        if (cfqd->active_cic) {
2101                put_io_context(cfqd->active_cic->icq.ioc);
2102                cfqd->active_cic = NULL;
2103        }
2104}
2105
2106static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out)
2107{
2108        struct cfq_queue *cfqq = cfqd->active_queue;
2109
2110        if (cfqq)
2111                __cfq_slice_expired(cfqd, cfqq, timed_out);
2112}
2113
2114/*
2115 * Get next queue for service. Unless we have a queue preemption,
2116 * we'll simply select the first cfqq in the service tree.
2117 */
2118static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
2119{
2120        struct cfq_rb_root *service_tree =
2121                service_tree_for(cfqd->serving_group, cfqd->serving_prio,
2122                                        cfqd->serving_type);
2123
2124        if (!cfqd->rq_queued)
2125                return NULL;
2126
2127        /* There is nothing to dispatch */
2128        if (!service_tree)
2129                return NULL;
2130        if (RB_EMPTY_ROOT(&service_tree->rb))
2131                return NULL;
2132        return cfq_rb_first(service_tree);
2133}
2134
2135static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd)
2136{
2137        struct cfq_group *cfqg;
2138        struct cfq_queue *cfqq;
2139        int i, j;
2140        struct cfq_rb_root *st;
2141
2142        if (!cfqd->rq_queued)
2143                return NULL;
2144
2145        cfqg = cfq_get_next_cfqg(cfqd);
2146        if (!cfqg)
2147                return NULL;
2148
2149        for_each_cfqg_st(cfqg, i, j, st)
2150                if ((cfqq = cfq_rb_first(st)) != NULL)
2151                        return cfqq;
2152        return NULL;
2153}
2154
2155/*
2156 * Get and set a new active queue for service.
2157 */
2158static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
2159                                              struct cfq_queue *cfqq)
2160{
2161        if (!cfqq)
2162                cfqq = cfq_get_next_queue(cfqd);
2163
2164        __cfq_set_active_queue(cfqd, cfqq);
2165        return cfqq;
2166}
2167
2168static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
2169                                          struct request *rq)
2170{
2171        if (blk_rq_pos(rq) >= cfqd->last_position)
2172                return blk_rq_pos(rq) - cfqd->last_position;
2173        else
2174                return cfqd->last_position - blk_rq_pos(rq);
2175}
2176
2177static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2178                               struct request *rq)
2179{
2180        return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR;
2181}
2182
2183static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
2184                                    struct cfq_queue *cur_cfqq)
2185{
2186        struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
2187        struct rb_node *parent, *node;
2188        struct cfq_queue *__cfqq;
2189        sector_t sector = cfqd->last_position;
2190
2191        if (RB_EMPTY_ROOT(root))
2192                return NULL;
2193
2194        /*
2195         * First, if we find a request starting at the end of the last
2196         * request, choose it.
2197         */
2198        __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
2199        if (__cfqq)
2200                return __cfqq;
2201
2202        /*
2203         * If the exact sector wasn't found, the parent of the NULL leaf
2204         * will contain the closest sector.
2205         */
2206        __cfqq = rb_entry(parent, struct cfq_queue, p_node);
2207        if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
2208                return __cfqq;
2209
2210        if (blk_rq_pos(__cfqq->next_rq) < sector)
2211                node = rb_next(&__cfqq->p_node);
2212        else
2213                node = rb_prev(&__cfqq->p_node);
2214        if (!node)
2215                return NULL;
2216
2217        __cfqq = rb_entry(node, struct cfq_queue, p_node);
2218        if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
2219                return __cfqq;
2220
2221        return NULL;
2222}
2223
2224/*
2225 * cfqd - obvious
2226 * cur_cfqq - passed in so that we don't decide that the current queue is
2227 *            closely cooperating with itself.
2228 *
2229 * So, basically we're assuming that that cur_cfqq has dispatched at least
2230 * one request, and that cfqd->last_position reflects a position on the disk
2231 * associated with the I/O issued by cur_cfqq.  I'm not sure this is a valid
2232 * assumption.
2233 */
2234static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
2235                                              struct cfq_queue *cur_cfqq)
2236{
2237        struct cfq_queue *cfqq;
2238
2239        if (cfq_class_idle(cur_cfqq))
2240                return NULL;
2241        if (!cfq_cfqq_sync(cur_cfqq))
2242                return NULL;
2243        if (CFQQ_SEEKY(cur_cfqq))
2244                return NULL;
2245
2246        /*
2247         * Don't search priority tree if it's the only queue in the group.
2248         */
2249        if (cur_cfqq->cfqg->nr_cfqq == 1)
2250                return NULL;
2251
2252        /*
2253         * We should notice if some of the queues are cooperating, eg
2254         * working closely on the same area of the disk. In that case,
2255         * we can group them together and don't waste time idling.
2256         */
2257        cfqq = cfqq_close(cfqd, cur_cfqq);
2258        if (!cfqq)
2259                return NULL;
2260
2261        /* If new queue belongs to different cfq_group, don't choose it */
2262        if (cur_cfqq->cfqg != cfqq->cfqg)
2263                return NULL;
2264
2265        /*
2266         * It only makes sense to merge sync queues.
2267         */
2268        if (!cfq_cfqq_sync(cfqq))
2269                return NULL;
2270        if (CFQQ_SEEKY(cfqq))
2271                return NULL;
2272
2273        /*
2274         * Do not merge queues of different priority classes
2275         */
2276        if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq))
2277                return NULL;
2278
2279        return cfqq;
2280}
2281
2282/*
2283 * Determine whether we should enforce idle window for this queue.
2284 */
2285
2286static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2287{
2288        enum wl_prio_t prio = cfqq_prio(cfqq);
2289        struct cfq_rb_root *service_tree = cfqq->service_tree;
2290
2291        BUG_ON(!service_tree);
2292        BUG_ON(!service_tree->count);
2293
2294        if (!cfqd->cfq_slice_idle)
2295                return false;
2296
2297        /* We never do for idle class queues. */
2298        if (prio == IDLE_WORKLOAD)
2299                return false;
2300
2301        /* We do for queues that were marked with idle window flag. */
2302        if (cfq_cfqq_idle_window(cfqq) &&
2303           !(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag))
2304                return true;
2305
2306        /*
2307         * Otherwise, we do only if they are the last ones
2308         * in their service tree.
2309         */
2310        if (service_tree->count == 1 && cfq_cfqq_sync(cfqq) &&
2311           !cfq_io_thinktime_big(cfqd, &service_tree->ttime, false))
2312                return true;
2313        cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d",
2314                        service_tree->count);
2315        return false;
2316}
2317
2318static void cfq_arm_slice_timer(struct cfq_data *cfqd)
2319{
2320        struct cfq_queue *cfqq = cfqd->active_queue;
2321        struct cfq_io_cq *cic;
2322        unsigned long sl, group_idle = 0;
2323
2324        /*
2325         * SSD device without seek penalty, disable idling. But only do so
2326         * for devices that support queuing, otherwise we still have a problem
2327         * with sync vs async workloads.
2328         */
2329        if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)
2330                return;
2331
2332        WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
2333        WARN_ON(cfq_cfqq_slice_new(cfqq));
2334
2335        /*
2336         * idle is disabled, either manually or by past process history
2337         */
2338        if (!cfq_should_idle(cfqd, cfqq)) {
2339                /* no queue idling. Check for group idling */
2340                if (cfqd->cfq_group_idle)
2341                        group_idle = cfqd->cfq_group_idle;
2342                else
2343                        return;
2344        }
2345
2346        /*
2347         * still active requests from this queue, don't idle
2348         */
2349        if (cfqq->dispatched)
2350                return;
2351
2352        /*
2353         * task has exited, don't wait
2354         */
2355        cic = cfqd->active_cic;
2356        if (!cic || !atomic_read(&cic->icq.ioc->active_ref))
2357                return;
2358
2359        /*
2360         * If our average think time is larger than the remaining time
2361         * slice, then don't idle. This avoids overrunning the allotted
2362         * time slice.
2363         */
2364        if (sample_valid(cic->ttime.ttime_samples) &&
2365            (cfqq->slice_end - jiffies < cic->ttime.ttime_mean)) {
2366                cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%lu",
2367                             cic->ttime.ttime_mean);
2368                return;
2369        }
2370
2371        /* There are other queues in the group, don't do group idle */
2372        if (group_idle && cfqq->cfqg->nr_cfqq > 1)
2373                return;
2374
2375        cfq_mark_cfqq_wait_request(cfqq);
2376
2377        if (group_idle)
2378                sl = cfqd->cfq_group_idle;
2379        else
2380                sl = cfqd->cfq_slice_idle;
2381
2382        mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
2383        cfqg_stats_set_start_idle_time(cfqq->cfqg);
2384        cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu group_idle: %d", sl,
2385                        group_idle ? 1 : 0);
2386}
2387
2388/*
2389 * Move request from internal lists to the request queue dispatch list.
2390 */
2391static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
2392{
2393        struct cfq_data *cfqd = q->elevator->elevator_data;
2394        struct cfq_queue *cfqq = RQ_CFQQ(rq);
2395
2396        cfq_log_cfqq(cfqd, cfqq, "dispatch_insert");
2397
2398        cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq);
2399        cfq_remove_request(rq);
2400        cfqq->dispatched++;
2401        (RQ_CFQG(rq))->dispatched++;
2402        elv_dispatch_sort(q, rq);
2403
2404        cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++;
2405        cfqq->nr_sectors += blk_rq_sectors(rq);
2406        cfqg_stats_update_dispatch(cfqq->cfqg, blk_rq_bytes(rq), rq->cmd_flags);
2407}
2408
2409/*
2410 * return expired entry, or NULL to just start from scratch in rbtree
2411 */
2412static struct request *cfq_check_fifo(struct cfq_queue *cfqq)
2413{
2414        struct request *rq = NULL;
2415
2416        if (cfq_cfqq_fifo_expire(cfqq))
2417                return NULL;
2418
2419        cfq_mark_cfqq_fifo_expire(cfqq);
2420
2421        if (list_empty(&cfqq->fifo))
2422                return NULL;
2423
2424        rq = rq_entry_fifo(cfqq->fifo.next);
2425        if (time_before(jiffies, rq_fifo_time(rq)))
2426                rq = NULL;
2427
2428        cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq);
2429        return rq;
2430}
2431
2432static inline int
2433cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2434{
2435        const int base_rq = cfqd->cfq_slice_async_rq;
2436
2437        WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
2438
2439        return 2 * base_rq * (IOPRIO_BE_NR - cfqq->ioprio);
2440}
2441
2442/*
2443 * Must be called with the queue_lock held.
2444 */
2445static int cfqq_process_refs(struct cfq_queue *cfqq)
2446{
2447        int process_refs, io_refs;
2448
2449        io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE];
2450        process_refs = cfqq->ref - io_refs;
2451        BUG_ON(process_refs < 0);
2452        return process_refs;
2453}
2454
2455static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq)
2456{
2457        int process_refs, new_process_refs;
2458        struct cfq_queue *__cfqq;
2459
2460        /*
2461         * If there are no process references on the new_cfqq, then it is
2462         * unsafe to follow the ->new_cfqq chain as other cfqq's in the
2463         * chain may have dropped their last reference (not just their
2464         * last process reference).
2465         */
2466        if (!cfqq_process_refs(new_cfqq))
2467                return;
2468
2469        /* Avoid a circular list and skip interim queue merges */
2470        while ((__cfqq = new_cfqq->new_cfqq)) {
2471                if (__cfqq == cfqq)
2472                        return;
2473                new_cfqq = __cfqq;
2474        }
2475
2476        process_refs = cfqq_process_refs(cfqq);
2477        new_process_refs = cfqq_process_refs(new_cfqq);
2478        /*
2479         * If the process for the cfqq has gone away, there is no
2480         * sense in merging the queues.
2481         */
2482        if (process_refs == 0 || new_process_refs == 0)
2483                return;
2484
2485        /*
2486         * Merge in the direction of the lesser amount of work.
2487         */
2488        if (new_process_refs >= process_refs) {
2489                cfqq->new_cfqq = new_cfqq;
2490                new_cfqq->ref += process_refs;
2491        } else {
2492                new_cfqq->new_cfqq = cfqq;
2493                cfqq->ref += new_process_refs;
2494        }
2495}
2496
2497static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd,
2498                                struct cfq_group *cfqg, enum wl_prio_t prio)
2499{
2500        struct cfq_queue *queue;
2501        int i;
2502        bool key_valid = false;
2503        unsigned long lowest_key = 0;
2504        enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD;
2505
2506        for (i = 0; i <= SYNC_WORKLOAD; ++i) {
2507                /* select the one with lowest rb_key */
2508                queue = cfq_rb_first(service_tree_for(cfqg, prio, i));
2509                if (queue &&
2510                    (!key_valid || time_before(queue->rb_key, lowest_key))) {
2511                        lowest_key = queue->rb_key;
2512                        cur_best = i;
2513                        key_valid = true;
2514                }
2515        }
2516
2517        return cur_best;
2518}
2519
2520static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg)
2521{
2522        unsigned slice;
2523        unsigned count;
2524        struct cfq_rb_root *st;
2525        unsigned group_slice;
2526        enum wl_prio_t original_prio = cfqd->serving_prio;
2527
2528        /* Choose next priority. RT > BE > IDLE */
2529        if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg))
2530                cfqd->serving_prio = RT_WORKLOAD;
2531        else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg))
2532                cfqd->serving_prio = BE_WORKLOAD;
2533        else {
2534                cfqd->serving_prio = IDLE_WORKLOAD;
2535                cfqd->workload_expires = jiffies + 1;
2536                return;
2537        }
2538
2539        if (original_prio != cfqd->serving_prio)
2540                goto new_workload;
2541
2542        /*
2543         * For RT and BE, we have to choose also the type
2544         * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
2545         * expiration time
2546         */
2547        st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type);
2548        count = st->count;
2549
2550        /*
2551         * check workload expiration, and that we still have other queues ready
2552         */
2553        if (count && !time_after(jiffies, cfqd->workload_expires))
2554                return;
2555
2556new_workload:
2557        /* otherwise select new workload type */
2558        cfqd->serving_type =
2559                cfq_choose_wl(cfqd, cfqg, cfqd->serving_prio);
2560        st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type);
2561        count = st->count;
2562
2563        /*
2564         * the workload slice is computed as a fraction of target latency
2565         * proportional to the number of queues in that workload, over
2566         * all the queues in the same priority class
2567         */
2568        group_slice = cfq_group_slice(cfqd, cfqg);
2569
2570        slice = group_slice * count /
2571                max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_prio],
2572                      cfq_group_busy_queues_wl(cfqd->serving_prio, cfqd, cfqg));
2573
2574        if (cfqd->serving_type == ASYNC_WORKLOAD) {
2575                unsigned int tmp;
2576
2577                /*
2578                 * Async queues are currently system wide. Just taking
2579                 * proportion of queues with-in same group will lead to higher
2580                 * async ratio system wide as generally root group is going
2581                 * to have higher weight. A more accurate thing would be to
2582                 * calculate system wide asnc/sync ratio.
2583                 */
2584                tmp = cfqd->cfq_target_latency *
2585                        cfqg_busy_async_queues(cfqd, cfqg);
2586                tmp = tmp/cfqd->busy_queues;
2587                slice = min_t(unsigned, slice, tmp);
2588
2589                /* async workload slice is scaled down according to
2590                 * the sync/async slice ratio. */
2591                slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1];
2592        } else
2593                /* sync workload slice is at least 2 * cfq_slice_idle */
2594                slice = max(slice, 2 * cfqd->cfq_slice_idle);
2595
2596        slice = max_t(unsigned, slice, CFQ_MIN_TT);
2597        cfq_log(cfqd, "workload slice:%d", slice);
2598        cfqd->workload_expires = jiffies + slice;
2599}
2600
2601static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd)
2602{
2603        struct cfq_rb_root *st = &cfqd->grp_service_tree;
2604        struct cfq_group *cfqg;
2605
2606        if (RB_EMPTY_ROOT(&st->rb))
2607                return NULL;
2608        cfqg = cfq_rb_first_group(st);
2609        update_min_vdisktime(st);
2610        return cfqg;
2611}
2612
2613static void cfq_choose_cfqg(struct cfq_data *cfqd)
2614{
2615        struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd);
2616
2617        cfqd->serving_group = cfqg;
2618
2619        /* Restore the workload type data */
2620        if (cfqg->saved_workload_slice) {
2621                cfqd->workload_expires = jiffies + cfqg->saved_workload_slice;
2622                cfqd->serving_type = cfqg->saved_workload;
2623                cfqd->serving_prio = cfqg->saved_serving_prio;
2624        } else
2625                cfqd->workload_expires = jiffies - 1;
2626
2627        choose_service_tree(cfqd, cfqg);
2628}
2629
2630/*
2631 * Select a queue for service. If we have a current active queue,
2632 * check whether to continue servicing it, or retrieve and set a new one.
2633 */
2634static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
2635{
2636        struct cfq_queue *cfqq, *new_cfqq = NULL;
2637
2638        cfqq = cfqd->active_queue;
2639        if (!cfqq)
2640                goto new_queue;
2641
2642        if (!cfqd->rq_queued)
2643                return NULL;
2644
2645        /*
2646         * We were waiting for group to get backlogged. Expire the queue
2647         */
2648        if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list))
2649                goto expire;
2650
2651        /*
2652         * The active queue has run out of time, expire it and select new.
2653         */
2654        if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) {
2655                /*
2656                 * If slice had not expired at the completion of last request
2657                 * we might not have turned on wait_busy flag. Don't expire
2658                 * the queue yet. Allow the group to get backlogged.
2659                 *
2660                 * The very fact that we have used the slice, that means we
2661                 * have been idling all along on this queue and it should be
2662                 * ok to wait for this request to complete.
2663                 */
2664                if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list)
2665                    && cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
2666                        cfqq = NULL;
2667                        goto keep_queue;
2668                } else
2669                        goto check_group_idle;
2670        }
2671
2672        /*
2673         * The active queue has requests and isn't expired, allow it to
2674         * dispatch.
2675         */
2676        if (!RB_EMPTY_ROOT(&cfqq->sort_list))
2677                goto keep_queue;
2678
2679        /*
2680         * If another queue has a request waiting within our mean seek
2681         * distance, let it run.  The expire code will check for close
2682         * cooperators and put the close queue at the front of the service
2683         * tree.  If possible, merge the expiring queue with the new cfqq.
2684         */
2685        new_cfqq = cfq_close_cooperator(cfqd, cfqq);
2686        if (new_cfqq) {
2687                if (!cfqq->new_cfqq)
2688                        cfq_setup_merge(cfqq, new_cfqq);
2689                goto expire;
2690        }
2691
2692        /*
2693         * No requests pending. If the active queue still has requests in
2694         * flight or is idling for a new request, allow either of these
2695         * conditions to happen (or time out) before selecting a new queue.
2696         */
2697        if (timer_pending(&cfqd->idle_slice_timer)) {
2698                cfqq = NULL;
2699                goto keep_queue;
2700        }
2701
2702        /*
2703         * This is a deep seek queue, but the device is much faster than
2704         * the queue can deliver, don't idle
2705         **/
2706        if (CFQQ_SEEKY(cfqq) && cfq_cfqq_idle_window(cfqq) &&
2707            (cfq_cfqq_slice_new(cfqq) ||
2708            (cfqq->slice_end - jiffies > jiffies - cfqq->slice_start))) {
2709                cfq_clear_cfqq_deep(cfqq);
2710                cfq_clear_cfqq_idle_window(cfqq);
2711        }
2712
2713        if (cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
2714                cfqq = NULL;
2715                goto keep_queue;
2716        }
2717
2718        /*
2719         * If group idle is enabled and there are requests dispatched from
2720         * this group, wait for requests to complete.
2721         */
2722check_group_idle:
2723        if (cfqd->cfq_group_idle && cfqq->cfqg->nr_cfqq == 1 &&
2724            cfqq->cfqg->dispatched &&
2725            !cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true)) {
2726                cfqq = NULL;
2727                goto keep_queue;
2728        }
2729
2730expire:
2731        cfq_slice_expired(cfqd, 0);
2732new_queue:
2733        /*
2734         * Current queue expired. Check if we have to switch to a new
2735         * service tree
2736         */
2737        if (!new_cfqq)
2738                cfq_choose_cfqg(cfqd);
2739
2740        cfqq = cfq_set_active_queue(cfqd, new_cfqq);
2741keep_queue:
2742        return cfqq;
2743}
2744
2745static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq)
2746{
2747        int dispatched = 0;
2748
2749        while (cfqq->next_rq) {
2750                cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq);
2751                dispatched++;
2752        }
2753
2754        BUG_ON(!list_empty(&cfqq->fifo));
2755
2756        /* By default cfqq is not expired if it is empty. Do it explicitly */
2757        __cfq_slice_expired(cfqq->cfqd, cfqq, 0);
2758        return dispatched;
2759}
2760
2761/*
2762 * Drain our current requests. Used for barriers and when switching
2763 * io schedulers on-the-fly.
2764 */
2765static int cfq_forced_dispatch(struct cfq_data *cfqd)
2766{
2767        struct cfq_queue *cfqq;
2768        int dispatched = 0;
2769
2770        /* Expire the timeslice of the current active queue first */
2771        cfq_slice_expired(cfqd, 0);
2772        while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) {
2773                __cfq_set_active_queue(cfqd, cfqq);
2774                dispatched += __cfq_forced_dispatch_cfqq(cfqq);
2775        }
2776
2777        BUG_ON(cfqd->busy_queues);
2778
2779        cfq_log(cfqd, "forced_dispatch=%d", dispatched);
2780        return dispatched;
2781}
2782
2783static inline bool cfq_slice_used_soon(struct cfq_data *cfqd,
2784        struct cfq_queue *cfqq)
2785{
2786        /* the queue hasn't finished any request, can't estimate */
2787        if (cfq_cfqq_slice_new(cfqq))
2788                return true;
2789        if (time_after(jiffies + cfqd->cfq_slice_idle * cfqq->dispatched,
2790                cfqq->slice_end))
2791                return true;
2792
2793        return false;
2794}
2795
2796static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2797{
2798        unsigned int max_dispatch;
2799
2800        /*
2801         * Drain async requests before we start sync IO
2802         */
2803        if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC])
2804                return false;
2805
2806        /*
2807         * If this is an async queue and we have sync IO in flight, let it wait
2808         */
2809        if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq))
2810                return false;
2811
2812        max_dispatch = max_t(unsigned int, cfqd->cfq_quantum / 2, 1);
2813        if (cfq_class_idle(cfqq))
2814                max_dispatch = 1;
2815
2816        /*
2817         * Does this cfqq already have too much IO in flight?
2818         */
2819        if (cfqq->dispatched >= max_dispatch) {
2820                bool promote_sync = false;
2821                /*
2822                 * idle queue must always only have a single IO in flight
2823                 */
2824                if (cfq_class_idle(cfqq))
2825                        return false;
2826
2827                /*
2828                 * If there is only one sync queue
2829                 * we can ignore async queue here and give the sync
2830                 * queue no dispatch limit. The reason is a sync queue can
2831                 * preempt async queue, limiting the sync queue doesn't make
2832                 * sense. This is useful for aiostress test.
2833                 */
2834                if (cfq_cfqq_sync(cfqq) && cfqd->busy_sync_queues == 1)
2835                        promote_sync = true;
2836
2837                /*
2838                 * We have other queues, don't allow more IO from this one
2839                 */
2840                if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq) &&
2841                                !promote_sync)
2842                        return false;
2843
2844                /*
2845                 * Sole queue user, no limit
2846                 */
2847                if (cfqd->busy_queues == 1 || promote_sync)
2848                        max_dispatch = -1;
2849                else
2850                        /*
2851                         * Normally we start throttling cfqq when cfq_quantum/2
2852                         * requests have been dispatched. But we can drive
2853                         * deeper queue depths at the beginning of slice
2854                         * subjected to upper limit of cfq_quantum.
2855                         * */
2856                        max_dispatch = cfqd->cfq_quantum;
2857        }
2858
2859        /*
2860         * Async queues must wait a bit before being allowed dispatch.
2861         * We also ramp up the dispatch depth gradually for async IO,
2862         * based on the last sync IO we serviced
2863         */
2864        if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) {
2865                unsigned long last_sync = jiffies - cfqd->last_delayed_sync;
2866                unsigned int depth;
2867
2868                depth = last_sync / cfqd->cfq_slice[1];
2869                if (!depth && !cfqq->dispatched)
2870                        depth = 1;
2871                if (depth < max_dispatch)
2872                        max_dispatch = depth;
2873        }
2874
2875        /*
2876         * If we're below the current max, allow a dispatch
2877         */
2878        return cfqq->dispatched < max_dispatch;
2879}
2880
2881/*
2882 * Dispatch a request from cfqq, moving them to the request queue
2883 * dispatch list.
2884 */
2885static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2886{
2887        struct request *rq;
2888
2889        BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list));
2890
2891        if (!cfq_may_dispatch(cfqd, cfqq))
2892                return false;
2893
2894        /*
2895         * follow expired path, else get first next available
2896         */
2897        rq = cfq_check_fifo(cfqq);
2898        if (!rq)
2899                rq = cfqq->next_rq;
2900
2901        /*
2902         * insert request into driver dispatch list
2903         */
2904        cfq_dispatch_insert(cfqd->queue, rq);
2905
2906        if (!cfqd->active_cic) {
2907                struct cfq_io_cq *cic = RQ_CIC(rq);
2908
2909                atomic_long_inc(&cic->icq.ioc->refcount);
2910                cfqd->active_cic = cic;
2911        }
2912
2913        return true;
2914}
2915
2916/*
2917 * Find the cfqq that we need to service and move a request from that to the
2918 * dispatch list
2919 */
2920static int cfq_dispatch_requests(struct request_queue *q, int force)
2921{
2922        struct cfq_data *cfqd = q->elevator->elevator_data;
2923        struct cfq_queue *cfqq;
2924
2925        if (!cfqd->busy_queues)
2926                return 0;
2927
2928        if (unlikely(force))
2929                return cfq_forced_dispatch(cfqd);
2930
2931        cfqq = cfq_select_queue(cfqd);
2932        if (!cfqq)
2933                return 0;
2934
2935        /*
2936         * Dispatch a request from this cfqq, if it is allowed
2937         */
2938        if (!cfq_dispatch_request(cfqd, cfqq))
2939                return 0;
2940
2941        cfqq->slice_dispatch++;
2942        cfq_clear_cfqq_must_dispatch(cfqq);
2943
2944        /*
2945         * expire an async queue immediately if it has used up its slice. idle
2946         * queue always expire after 1 dispatch round.
2947         */
2948        if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
2949            cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
2950            cfq_class_idle(cfqq))) {
2951                cfqq->slice_end = jiffies + 1;
2952                cfq_slice_expired(cfqd, 0);
2953        }
2954
2955        cfq_log_cfqq(cfqd, cfqq, "dispatched a request");
2956        return 1;
2957}
2958
2959/*
2960 * task holds one reference to the queue, dropped when task exits. each rq
2961 * in-flight on this queue also holds a reference, dropped when rq is freed.
2962 *
2963 * Each cfq queue took a reference on the parent group. Drop it now.
2964 * queue lock must be held here.
2965 */
2966static void cfq_put_queue(struct cfq_queue *cfqq)
2967{
2968        struct cfq_data *cfqd = cfqq->cfqd;
2969        struct cfq_group *cfqg;
2970
2971        BUG_ON(cfqq->ref <= 0);
2972
2973        cfqq->ref--;
2974        if (cfqq->ref)
2975                return;
2976
2977        cfq_log_cfqq(cfqd, cfqq, "put_queue");
2978        BUG_ON(rb_first(&cfqq->sort_list));
2979        BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
2980        cfqg = cfqq->cfqg;
2981
2982        if (unlikely(cfqd->active_queue == cfqq)) {
2983                __cfq_slice_expired(cfqd, cfqq, 0);
2984                cfq_schedule_dispatch(cfqd);
2985        }
2986
2987        BUG_ON(cfq_cfqq_on_rr(cfqq));
2988        kmem_cache_free(cfq_pool, cfqq);
2989        cfqg_put(cfqg);
2990}
2991
2992static void cfq_put_cooperator(struct cfq_queue *cfqq)
2993{
2994        struct cfq_queue *__cfqq, *next;
2995
2996        /*
2997         * If this queue was scheduled to merge with another queue, be
2998         * sure to drop the reference taken on that queue (and others in
2999         * the merge chain).  See cfq_setup_merge and cfq_merge_cfqqs.
3000         */
3001        __cfqq = cfqq->new_cfqq;
3002        while (__cfqq) {
3003                if (__cfqq == cfqq) {
3004                        WARN(1, "cfqq->new_cfqq loop detected\n");
3005                        break;
3006                }
3007                next = __cfqq->new_cfqq;
3008                cfq_put_queue(__cfqq);
3009                __cfqq = next;
3010        }
3011}
3012
3013static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3014{
3015        if (unlikely(cfqq == cfqd->active_queue)) {
3016                __cfq_slice_expired(cfqd, cfqq, 0);
3017                cfq_schedule_dispatch(cfqd);
3018        }
3019
3020        cfq_put_cooperator(cfqq);
3021
3022        cfq_put_queue(cfqq);
3023}
3024
3025static void cfq_init_icq(struct io_cq *icq)
3026{
3027        struct cfq_io_cq *cic = icq_to_cic(icq);
3028
3029        cic->ttime.last_end_request = jiffies;
3030}
3031
3032static void cfq_exit_icq(struct io_cq *icq)
3033{
3034        struct cfq_io_cq *cic = icq_to_cic(icq);
3035        struct cfq_data *cfqd = cic_to_cfqd(cic);
3036
3037        if (cic->cfqq[BLK_RW_ASYNC]) {
3038                cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]);
3039                cic->cfqq[BLK_RW_ASYNC] = NULL;
3040        }
3041
3042        if (cic->cfqq[BLK_RW_SYNC]) {
3043                cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]);
3044                cic->cfqq[BLK_RW_SYNC] = NULL;
3045        }
3046}
3047
3048static void cfq_init_prio_data(struct cfq_queue *cfqq, struct cfq_io_cq *cic)
3049{
3050        struct task_struct *tsk = current;
3051        int ioprio_class;
3052
3053        if (!cfq_cfqq_prio_changed(cfqq))
3054                return;
3055
3056        ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio);
3057        switch (ioprio_class) {
3058        default:
3059                printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
3060        case IOPRIO_CLASS_NONE:
3061                /*
3062                 * no prio set, inherit CPU scheduling settings
3063                 */
3064                cfqq->ioprio = task_nice_ioprio(tsk);
3065                cfqq->ioprio_class = task_nice_ioclass(tsk);
3066                break;
3067        case IOPRIO_CLASS_RT:
3068                cfqq->ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
3069                cfqq->ioprio_class = IOPRIO_CLASS_RT;
3070                break;
3071        case IOPRIO_CLASS_BE:
3072                cfqq->ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
3073                cfqq->ioprio_class = IOPRIO_CLASS_BE;
3074                break;
3075        case IOPRIO_CLASS_IDLE:
3076                cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
3077                cfqq->ioprio = 7;
3078                cfq_clear_cfqq_idle_window(cfqq);
3079                break;
3080        }
3081
3082        /*
3083         * keep track of original prio settings in case we have to temporarily
3084         * elevate the priority of this queue
3085         */
3086        cfqq->org_ioprio = cfqq->ioprio;
3087        cfq_clear_cfqq_prio_changed(cfqq);
3088}
3089
3090static void check_ioprio_changed(struct cfq_io_cq *cic, struct bio *bio)
3091{
3092        int ioprio = cic->icq.ioc->ioprio;
3093        struct cfq_data *cfqd = cic_to_cfqd(cic);
3094        struct cfq_queue *cfqq;
3095
3096        /*
3097         * Check whether ioprio has changed.  The condition may trigger
3098         * spuriously on a newly created cic but there's no harm.
3099         */
3100        if (unlikely(!cfqd) || likely(cic->ioprio == ioprio))
3101                return;
3102
3103        cfqq = cic->cfqq[BLK_RW_ASYNC];
3104        if (cfqq) {
3105                struct cfq_queue *new_cfqq;
3106                new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic, bio,
3107                                         GFP_ATOMIC);
3108                if (new_cfqq) {
3109                        cic->cfqq[BLK_RW_ASYNC] = new_cfqq;
3110                        cfq_put_queue(cfqq);
3111                }
3112        }
3113
3114        cfqq = cic->cfqq[BLK_RW_SYNC];
3115        if (cfqq)
3116                cfq_mark_cfqq_prio_changed(cfqq);
3117
3118        cic->ioprio = ioprio;
3119}
3120
3121static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3122                          pid_t pid, bool is_sync)
3123{
3124        RB_CLEAR_NODE(&cfqq->rb_node);
3125        RB_CLEAR_NODE(&cfqq->p_node);
3126        INIT_LIST_HEAD(&cfqq->fifo);
3127
3128        cfqq->ref = 0;
3129        cfqq->cfqd = cfqd;
3130
3131        cfq_mark_cfqq_prio_changed(cfqq);
3132
3133        if (is_sync) {
3134                if (!cfq_class_idle(cfqq))
3135                        cfq_mark_cfqq_idle_window(cfqq);
3136                cfq_mark_cfqq_sync(cfqq);
3137        }
3138        cfqq->pid = pid;
3139}
3140
3141#ifdef CONFIG_CFQ_GROUP_IOSCHED
3142static void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio)
3143{
3144        struct cfq_data *cfqd = cic_to_cfqd(cic);
3145        struct cfq_queue *sync_cfqq;
3146        uint64_t id;
3147
3148        rcu_read_lock();
3149        id = bio_blkcg(bio)->id;
3150        rcu_read_unlock();
3151
3152        /*
3153         * Check whether blkcg has changed.  The condition may trigger
3154         * spuriously on a newly created cic but there's no harm.
3155         */
3156        if (unlikely(!cfqd) || likely(cic->blkcg_id == id))
3157                return;
3158
3159        sync_cfqq = cic_to_cfqq(cic, 1);
3160        if (sync_cfqq) {
3161                /*
3162                 * Drop reference to sync queue. A new sync queue will be
3163                 * assigned in new group upon arrival of a fresh request.
3164                 */
3165                cfq_log_cfqq(cfqd, sync_cfqq, "changed cgroup");
3166                cic_set_cfqq(cic, NULL, 1);
3167                cfq_put_queue(sync_cfqq);
3168        }
3169
3170        cic->blkcg_id = id;
3171}
3172#else
3173static inline void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio) { }
3174#endif  /* CONFIG_CFQ_GROUP_IOSCHED */
3175
3176static struct cfq_queue *
3177cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic,
3178                     struct bio *bio, gfp_t gfp_mask)
3179{
3180        struct blkcg *blkcg;
3181        struct cfq_queue *cfqq, *new_cfqq = NULL;
3182        struct cfq_group *cfqg;
3183
3184retry:
3185        rcu_read_lock();
3186
3187        blkcg = bio_blkcg(bio);
3188        cfqg = cfq_lookup_create_cfqg(cfqd, blkcg);
3189        cfqq = cic_to_cfqq(cic, is_sync);
3190
3191        /*
3192         * Always try a new alloc if we fell back to the OOM cfqq
3193         * originally, since it should just be a temporary situation.
3194         */
3195        if (!cfqq || cfqq == &cfqd->oom_cfqq) {
3196                cfqq = NULL;
3197                if (new_cfqq) {
3198                        cfqq = new_cfqq;
3199                        new_cfqq = NULL;
3200                } else if (gfp_mask & __GFP_WAIT) {
3201                        rcu_read_unlock();
3202                        spin_unlock_irq(cfqd->queue->queue_lock);
3203                        new_cfqq = kmem_cache_alloc_node(cfq_pool,
3204                                        gfp_mask | __GFP_ZERO,
3205                                        cfqd->queue->node);
3206                        spin_lock_irq(cfqd->queue->queue_lock);
3207                        if (new_cfqq)
3208                                goto retry;
3209                } else {
3210                        cfqq = kmem_cache_alloc_node(cfq_pool,
3211                                        gfp_mask | __GFP_ZERO,
3212                                        cfqd->queue->node);
3213                }
3214
3215                if (cfqq) {
3216                        cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
3217                        cfq_init_prio_data(cfqq, cic);
3218                        cfq_link_cfqq_cfqg(cfqq, cfqg);
3219                        cfq_log_cfqq(cfqd, cfqq, "alloced");
3220                } else
3221                        cfqq = &cfqd->oom_cfqq;
3222        }
3223
3224        if (new_cfqq)
3225                kmem_cache_free(cfq_pool, new_cfqq);
3226
3227        rcu_read_unlock();
3228        return cfqq;
3229}
3230
3231static struct cfq_queue **
3232cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio)
3233{
3234        switch (ioprio_class) {
3235        case IOPRIO_CLASS_RT:
3236                return &cfqd->async_cfqq[0][ioprio];
3237        case IOPRIO_CLASS_NONE:
3238                ioprio = IOPRIO_NORM;
3239                /* fall through */
3240        case IOPRIO_CLASS_BE:
3241                return &cfqd->async_cfqq[1][ioprio];
3242        case IOPRIO_CLASS_IDLE:
3243                return &cfqd->async_idle_cfqq;
3244        default:
3245                BUG();
3246        }
3247}
3248
3249static struct cfq_queue *
3250cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic,
3251              struct bio *bio, gfp_t gfp_mask)
3252{
3253        const int ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio);
3254        const int ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
3255        struct cfq_queue **async_cfqq = NULL;
3256        struct cfq_queue *cfqq = NULL;
3257
3258        if (!is_sync) {
3259                async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio);
3260                cfqq = *async_cfqq;
3261        }
3262
3263        if (!cfqq)
3264                cfqq = cfq_find_alloc_queue(cfqd, is_sync, cic, bio, gfp_mask);
3265
3266        /*
3267         * pin the queue now that it's allocated, scheduler exit will prune it
3268         */
3269        if (!is_sync && !(*async_cfqq)) {
3270                cfqq->ref++;
3271                *async_cfqq = cfqq;
3272        }
3273
3274        cfqq->ref++;
3275        return cfqq;
3276}
3277
3278static void
3279__cfq_update_io_thinktime(struct cfq_ttime *ttime, unsigned long slice_idle)
3280{
3281        unsigned long elapsed = jiffies - ttime->last_end_request;
3282        elapsed = min(elapsed, 2UL * slice_idle);
3283
3284        ttime->ttime_samples = (7*ttime->ttime_samples + 256) / 8;
3285        ttime->ttime_total = (7*ttime->ttime_total + 256*elapsed) / 8;
3286        ttime->ttime_mean = (ttime->ttime_total + 128) / ttime->ttime_samples;
3287}
3288
3289static void
3290cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3291                        struct cfq_io_cq *cic)
3292{
3293        if (cfq_cfqq_sync(cfqq)) {
3294                __cfq_update_io_thinktime(&cic->ttime, cfqd->cfq_slice_idle);
3295                __cfq_update_io_thinktime(&cfqq->service_tree->ttime,
3296                        cfqd->cfq_slice_idle);
3297        }
3298#ifdef CONFIG_CFQ_GROUP_IOSCHED
3299        __cfq_update_io_thinktime(&cfqq->cfqg->ttime, cfqd->cfq_group_idle);
3300#endif
3301}
3302
3303static void
3304cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3305                       struct request *rq)
3306{
3307        sector_t sdist = 0;
3308        sector_t n_sec = blk_rq_sectors(rq);
3309        if (cfqq->last_request_pos) {
3310                if (cfqq->last_request_pos < blk_rq_pos(rq))
3311                        sdist = blk_rq_pos(rq) - cfqq->last_request_pos;
3312                else
3313                        sdist = cfqq->last_request_pos - blk_rq_pos(rq);
3314        }
3315
3316        cfqq->seek_history <<= 1;
3317        if (blk_queue_nonrot(cfqd->queue))
3318                cfqq->seek_history |= (n_sec < CFQQ_SECT_THR_NONROT);
3319        else
3320                cfqq->seek_history |= (sdist > CFQQ_SEEK_THR);
3321}
3322
3323/*
3324 * Disable idle window if the process thinks too long or seeks so much that
3325 * it doesn't matter
3326 */
3327static void
3328cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3329                       struct cfq_io_cq *cic)
3330{
3331        int old_idle, enable_idle;
3332
3333        /*
3334         * Don't idle for async or idle io prio class
3335         */
3336        if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq))
3337                return;
3338
3339        enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
3340
3341        if (cfqq->queued[0] + cfqq->queued[1] >= 4)
3342                cfq_mark_cfqq_deep(cfqq);
3343
3344        if (cfqq->next_rq && (cfqq->next_rq->cmd_flags & REQ_NOIDLE))
3345                enable_idle = 0;
3346        else if (!atomic_read(&cic->icq.ioc->active_ref) ||
3347                 !cfqd->cfq_slice_idle ||
3348                 (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq)))
3349                enable_idle = 0;
3350        else if (sample_valid(cic->ttime.ttime_samples)) {
3351                if (cic->ttime.ttime_mean > cfqd->cfq_slice_idle)
3352                        enable_idle = 0;
3353                else
3354                        enable_idle = 1;
3355        }
3356
3357        if (old_idle != enable_idle) {
3358                cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle);
3359                if (enable_idle)
3360                        cfq_mark_cfqq_idle_window(cfqq);
3361                else
3362                        cfq_clear_cfqq_idle_window(cfqq);
3363        }
3364}
3365
3366/*
3367 * Check if new_cfqq should preempt the currently active queue. Return 0 for
3368 * no or if we aren't sure, a 1 will cause a preempt.
3369 */
3370static bool
3371cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
3372                   struct request *rq)
3373{
3374        struct cfq_queue *cfqq;
3375
3376        cfqq = cfqd->active_queue;
3377        if (!cfqq)
3378                return false;
3379
3380        if (cfq_class_idle(new_cfqq))
3381                return false;
3382
3383        if (cfq_class_idle(cfqq))
3384                return true;
3385
3386        /*
3387         * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice.
3388         */
3389        if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq))
3390                return false;
3391
3392        /*
3393         * if the new request is sync, but the currently running queue is
3394         * not, let the sync request have priority.
3395         */
3396        if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq))
3397                return true;
3398
3399        if (new_cfqq->cfqg != cfqq->cfqg)
3400                return false;
3401
3402        if (cfq_slice_used(cfqq))
3403                return true;
3404
3405        /* Allow preemption only if we are idling on sync-noidle tree */
3406        if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD &&
3407            cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD &&
3408            new_cfqq->service_tree->count == 2 &&
3409            RB_EMPTY_ROOT(&cfqq->sort_list))
3410                return true;
3411
3412        /*
3413         * So both queues are sync. Let the new request get disk time if
3414         * it's a metadata request and the current queue is doing regular IO.
3415         */
3416        if ((rq->cmd_flags & REQ_PRIO) && !cfqq->prio_pending)
3417                return true;
3418
3419        /*
3420         * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
3421         */
3422        if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
3423                return true;
3424
3425        /* An idle queue should not be idle now for some reason */
3426        if (RB_EMPTY_ROOT(&cfqq->sort_list) && !cfq_should_idle(cfqd, cfqq))
3427                return true;
3428
3429        if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq))
3430                return false;
3431
3432        /*
3433         * if this request is as-good as one we would expect from the
3434         * current cfqq, let it preempt
3435         */
3436        if (cfq_rq_close(cfqd, cfqq, rq))
3437                return true;
3438
3439        return false;
3440}
3441
3442/*
3443 * cfqq preempts the active queue. if we allowed preempt with no slice left,
3444 * let it have half of its nominal slice.
3445 */
3446static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3447{
3448        enum wl_type_t old_type = cfqq_type(cfqd->active_queue);
3449
3450        cfq_log_cfqq(cfqd, cfqq, "preempt");
3451        cfq_slice_expired(cfqd, 1);
3452
3453        /*
3454         * workload type is changed, don't save slice, otherwise preempt
3455         * doesn't happen
3456         */
3457        if (old_type != cfqq_type(cfqq))
3458                cfqq->cfqg->saved_workload_slice = 0;
3459
3460        /*
3461         * Put the new queue at the front of the of the current list,
3462         * so we know that it will be selected next.
3463         */
3464        BUG_ON(!cfq_cfqq_on_rr(cfqq));
3465
3466        cfq_service_tree_add(cfqd, cfqq, 1);
3467
3468        cfqq->slice_end = 0;
3469        cfq_mark_cfqq_slice_new(cfqq);
3470}
3471
3472/*
3473 * Called when a new fs request (rq) is added (to cfqq). Check if there's
3474 * something we should do about it
3475 */
3476static void
3477cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3478                struct request *rq)
3479{
3480        struct cfq_io_cq *cic = RQ_CIC(rq);
3481
3482        cfqd->rq_queued++;
3483        if (rq->cmd_flags & REQ_PRIO)
3484                cfqq->prio_pending++;
3485
3486        cfq_update_io_thinktime(cfqd, cfqq, cic);
3487        cfq_update_io_seektime(cfqd, cfqq, rq);
3488        cfq_update_idle_window(cfqd, cfqq, cic);
3489
3490        cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
3491
3492        if (cfqq == cfqd->active_queue) {
3493                /*
3494                 * Remember that we saw a request from this process, but
3495                 * don't start queuing just yet. Otherwise we risk seeing lots
3496                 * of tiny requests, because we disrupt the normal plugging
3497                 * and merging. If the request is already larger than a single
3498                 * page, let it rip immediately. For that case we assume that
3499                 * merging is already done. Ditto for a busy system that
3500                 * has other work pending, don't risk delaying until the
3501                 * idle timer unplug to continue working.
3502                 */
3503                if (cfq_cfqq_wait_request(cfqq)) {
3504                        if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE ||
3505                            cfqd->busy_queues > 1) {
3506                                cfq_del_timer(cfqd, cfqq);
3507                                cfq_clear_cfqq_wait_request(cfqq);
3508                                __blk_run_queue(cfqd->queue);
3509                        } else {
3510                                cfqg_stats_update_idle_time(cfqq->cfqg);
3511                                cfq_mark_cfqq_must_dispatch(cfqq);
3512                        }
3513                }
3514        } else if (cfq_should_preempt(cfqd, cfqq, rq)) {
3515                /*
3516                 * not the active queue - expire current slice if it is
3517                 * idle and has expired it's mean thinktime or this new queue
3518                 * has some old slice time left and is of higher priority or
3519                 * this new queue is RT and the current one is BE
3520                 */
3521                cfq_preempt_queue(cfqd, cfqq);
3522                __blk_run_queue(cfqd->queue);
3523        }
3524}
3525
3526static void cfq_insert_request(struct request_queue *q, struct request *rq)
3527{
3528        struct cfq_data *cfqd = q->elevator->elevator_data;
3529        struct cfq_queue *cfqq = RQ_CFQQ(rq);
3530
3531        cfq_log_cfqq(cfqd, cfqq, "insert_request");
3532        cfq_init_prio_data(cfqq, RQ_CIC(rq));
3533
3534        rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]);
3535        list_add_tail(&rq->queuelist, &cfqq->fifo);
3536        cfq_add_rq_rb(rq);
3537        cfqg_stats_update_io_add(RQ_CFQG(rq), cfqd->serving_group,
3538                                 rq->cmd_flags);
3539        cfq_rq_enqueued(cfqd, cfqq, rq);
3540}
3541
3542/*
3543 * Update hw_tag based on peak queue depth over 50 samples under
3544 * sufficient load.
3545 */
3546static void cfq_update_hw_tag(struct cfq_data *cfqd)
3547{
3548        struct cfq_queue *cfqq = cfqd->active_queue;
3549
3550        if (cfqd->rq_in_driver > cfqd->hw_tag_est_depth)
3551                cfqd->hw_tag_est_depth = cfqd->rq_in_driver;
3552
3553        if (cfqd->hw_tag == 1)
3554                return;
3555
3556        if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
3557            cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN)
3558                return;
3559
3560        /*
3561         * If active queue hasn't enough requests and can idle, cfq might not
3562         * dispatch sufficient requests to hardware. Don't zero hw_tag in this
3563         * case
3564         */
3565        if (cfqq && cfq_cfqq_idle_window(cfqq) &&
3566            cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] <
3567            CFQ_HW_QUEUE_MIN && cfqd->rq_in_driver < CFQ_HW_QUEUE_MIN)
3568                return;
3569
3570        if (cfqd->hw_tag_samples++ < 50)
3571                return;
3572
3573        if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN)
3574                cfqd->hw_tag = 1;
3575        else
3576                cfqd->hw_tag = 0;
3577}
3578
3579static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3580{
3581        struct cfq_io_cq *cic = cfqd->active_cic;
3582
3583        /* If the queue already has requests, don't wait */
3584        if (!RB_EMPTY_ROOT(&cfqq->sort_list))
3585                return false;
3586
3587        /* If there are other queues in the group, don't wait */
3588        if (cfqq->cfqg->nr_cfqq > 1)
3589                return false;
3590
3591        /* the only queue in the group, but think time is big */
3592        if (cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true))
3593                return false;
3594
3595        if (cfq_slice_used(cfqq))
3596                return true;
3597
3598        /* if slice left is less than think time, wait busy */
3599        if (cic && sample_valid(cic->ttime.ttime_samples)
3600            && (cfqq->slice_end - jiffies < cic->ttime.ttime_mean))
3601                return true;
3602
3603        /*
3604         * If think times is less than a jiffy than ttime_mean=0 and above
3605         * will not be true. It might happen that slice has not expired yet
3606         * but will expire soon (4-5 ns) during select_queue(). To cover the
3607         * case where think time is less than a jiffy, mark the queue wait
3608         * busy if only 1 jiffy is left in the slice.
3609         */
3610        if (cfqq->slice_end - jiffies == 1)
3611                return true;
3612
3613        return false;
3614}
3615
3616static void cfq_completed_request(struct request_queue *q, struct request *rq)
3617{
3618        struct cfq_queue *cfqq = RQ_CFQQ(rq);
3619        struct cfq_data *cfqd = cfqq->cfqd;
3620        const int sync = rq_is_sync(rq);
3621        unsigned long now;
3622
3623        now = jiffies;
3624        cfq_log_cfqq(cfqd, cfqq, "complete rqnoidle %d",
3625                     !!(rq->cmd_flags & REQ_NOIDLE));
3626
3627        cfq_update_hw_tag(cfqd);
3628
3629        WARN_ON(!cfqd->rq_in_driver);
3630        WARN_ON(!cfqq->dispatched);
3631        cfqd->rq_in_driver--;
3632        cfqq->dispatched--;
3633        (RQ_CFQG(rq))->dispatched--;
3634        cfqg_stats_update_completion(cfqq->cfqg, rq_start_time_ns(rq),
3635                                     rq_io_start_time_ns(rq), rq->cmd_flags);
3636
3637        cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--;
3638
3639        if (sync) {
3640                struct cfq_rb_root *service_tree;
3641
3642                RQ_CIC(rq)->ttime.last_end_request = now;
3643
3644                if (cfq_cfqq_on_rr(cfqq))
3645                        service_tree = cfqq->service_tree;
3646                else
3647                        service_tree = service_tree_for(cfqq->cfqg,
3648                                cfqq_prio(cfqq), cfqq_type(cfqq));
3649                service_tree->ttime.last_end_request = now;
3650                if (!time_after(rq->start_time + cfqd->cfq_fifo_expire[1], now))
3651                        cfqd->last_delayed_sync = now;
3652        }
3653
3654#ifdef CONFIG_CFQ_GROUP_IOSCHED
3655        cfqq->cfqg->ttime.last_end_request = now;
3656#endif
3657
3658        /*
3659         * If this is the active queue, check if it needs to be expired,
3660         * or if we want to idle in case it has no pending requests.
3661         */
3662        if (cfqd->active_queue == cfqq) {
3663                const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list);
3664
3665                if (cfq_cfqq_slice_new(cfqq)) {
3666                        cfq_set_prio_slice(cfqd, cfqq);
3667                        cfq_clear_cfqq_slice_new(cfqq);
3668                }
3669
3670                /*
3671                 * Should we wait for next request to come in before we expire
3672                 * the queue.
3673                 */
3674                if (cfq_should_wait_busy(cfqd, cfqq)) {
3675                        unsigned long extend_sl = cfqd->cfq_slice_idle;
3676                        if (!cfqd->cfq_slice_idle)
3677                                extend_sl = cfqd->cfq_group_idle;
3678                        cfqq->slice_end = jiffies + extend_sl;
3679                        cfq_mark_cfqq_wait_busy(cfqq);
3680                        cfq_log_cfqq(cfqd, cfqq, "will busy wait");
3681                }
3682
3683                /*
3684                 * Idling is not enabled on:
3685                 * - expired queues
3686                 * - idle-priority queues
3687                 * - async queues
3688                 * - queues with still some requests queued
3689                 * - when there is a close cooperator
3690                 */
3691                if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq))
3692                        cfq_slice_expired(cfqd, 1);
3693                else if (sync && cfqq_empty &&
3694                         !cfq_close_cooperator(cfqd, cfqq)) {
3695                        cfq_arm_slice_timer(cfqd);
3696                }
3697        }
3698
3699        if (!cfqd->rq_in_driver)
3700                cfq_schedule_dispatch(cfqd);
3701}
3702
3703static inline int __cfq_may_queue(struct cfq_queue *cfqq)
3704{
3705        if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) {
3706                cfq_mark_cfqq_must_alloc_slice(cfqq);
3707                return ELV_MQUEUE_MUST;
3708        }
3709
3710        return ELV_MQUEUE_MAY;
3711}
3712
3713static int cfq_may_queue(struct request_queue *q, int rw)
3714{
3715        struct cfq_data *cfqd = q->elevator->elevator_data;
3716        struct task_struct *tsk = current;
3717        struct cfq_io_cq *cic;
3718        struct cfq_queue *cfqq;
3719
3720        /*
3721         * don't force setup of a queue from here, as a call to may_queue
3722         * does not necessarily imply that a request actually will be queued.
3723         * so just lookup a possibly existing queue, or return 'may queue'
3724         * if that fails
3725         */
3726        cic = cfq_cic_lookup(cfqd, tsk->io_context);
3727        if (!cic)
3728                return ELV_MQUEUE_MAY;
3729
3730        cfqq = cic_to_cfqq(cic, rw_is_sync(rw));
3731        if (cfqq) {
3732                cfq_init_prio_data(cfqq, cic);
3733
3734                return __cfq_may_queue(cfqq);
3735        }
3736
3737        return ELV_MQUEUE_MAY;
3738}
3739
3740/*
3741 * queue lock held here
3742 */
3743static void cfq_put_request(struct request *rq)
3744{
3745        struct cfq_queue *cfqq = RQ_CFQQ(rq);
3746
3747        if (cfqq) {
3748                const int rw = rq_data_dir(rq);
3749
3750                BUG_ON(!cfqq->allocated[rw]);
3751                cfqq->allocated[rw]--;
3752
3753                /* Put down rq reference on cfqg */
3754                cfqg_put(RQ_CFQG(rq));
3755                rq->elv.priv[0] = NULL;
3756                rq->elv.priv[1] = NULL;
3757
3758                cfq_put_queue(cfqq);
3759        }
3760}
3761
3762static struct cfq_queue *
3763cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_cq *cic,
3764                struct cfq_queue *cfqq)
3765{
3766        cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq);
3767        cic_set_cfqq(cic, cfqq->new_cfqq, 1);
3768        cfq_mark_cfqq_coop(cfqq->new_cfqq);
3769        cfq_put_queue(cfqq);
3770        return cic_to_cfqq(cic, 1);
3771}
3772
3773/*
3774 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
3775 * was the last process referring to said cfqq.
3776 */
3777static struct cfq_queue *
3778split_cfqq(struct cfq_io_cq *cic, struct cfq_queue *cfqq)
3779{
3780        if (cfqq_process_refs(cfqq) == 1) {
3781                cfqq->pid = current->pid;
3782                cfq_clear_cfqq_coop(cfqq);
3783                cfq_clear_cfqq_split_coop(cfqq);
3784                return cfqq;
3785        }
3786
3787        cic_set_cfqq(cic, NULL, 1);
3788
3789        cfq_put_cooperator(cfqq);
3790
3791        cfq_put_queue(cfqq);
3792        return NULL;
3793}
3794/*
3795 * Allocate cfq data structures associated with this request.
3796 */
3797static int
3798cfq_set_request(struct request_queue *q, struct request *rq, struct bio *bio,
3799                gfp_t gfp_mask)
3800{
3801        struct cfq_data *cfqd = q->elevator->elevator_data;
3802        struct cfq_io_cq *cic = icq_to_cic(rq->elv.icq);
3803        const int rw = rq_data_dir(rq);
3804        const bool is_sync = rq_is_sync(rq);
3805        struct cfq_queue *cfqq;
3806
3807        might_sleep_if(gfp_mask & __GFP_WAIT);
3808
3809        spin_lock_irq(q->queue_lock);
3810
3811        check_ioprio_changed(cic, bio);
3812        check_blkcg_changed(cic, bio);
3813new_queue:
3814        cfqq = cic_to_cfqq(cic, is_sync);
3815        if (!cfqq || cfqq == &cfqd->oom_cfqq) {
3816                cfqq = cfq_get_queue(cfqd, is_sync, cic, bio, gfp_mask);
3817                cic_set_cfqq(cic, cfqq, is_sync);
3818        } else {
3819                /*
3820                 * If the queue was seeky for too long, break it apart.
3821                 */
3822                if (cfq_cfqq_coop(cfqq) && cfq_cfqq_split_coop(cfqq)) {
3823                        cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq");
3824                        cfqq = split_cfqq(cic, cfqq);
3825                        if (!cfqq)
3826                                goto new_queue;
3827                }
3828
3829                /*
3830                 * Check to see if this queue is scheduled to merge with
3831                 * another, closely cooperating queue.  The merging of
3832                 * queues happens here as it must be done in process context.
3833                 * The reference on new_cfqq was taken in merge_cfqqs.
3834                 */
3835                if (cfqq->new_cfqq)
3836                        cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq);
3837        }
3838
3839        cfqq->allocated[rw]++;
3840
3841        cfqq->ref++;
3842        cfqg_get(cfqq->cfqg);
3843        rq->elv.priv[0] = cfqq;
3844        rq->elv.priv[1] = cfqq->cfqg;
3845        spin_unlock_irq(q->queue_lock);
3846        return 0;
3847}
3848
3849static void cfq_kick_queue(struct work_struct *work)
3850{
3851        struct cfq_data *cfqd =
3852                container_of(work, struct cfq_data, unplug_work);
3853        struct request_queue *q = cfqd->queue;
3854
3855        spin_lock_irq(q->queue_lock);
3856        __blk_run_queue(cfqd->queue);
3857        spin_unlock_irq(q->queue_lock);
3858}
3859
3860/*
3861 * Timer running if the active_queue is currently idling inside its time slice
3862 */
3863static void cfq_idle_slice_timer(unsigned long data)
3864{
3865        struct cfq_data *cfqd = (struct cfq_data *) data;
3866        struct cfq_queue *cfqq;
3867        unsigned long flags;
3868        int timed_out = 1;
3869
3870        cfq_log(cfqd, "idle timer fired");
3871
3872        spin_lock_irqsave(cfqd->queue->queue_lock, flags);
3873
3874        cfqq = cfqd->active_queue;
3875        if (cfqq) {
3876                timed_out = 0;
3877
3878                /*
3879                 * We saw a request before the queue expired, let it through
3880                 */
3881                if (cfq_cfqq_must_dispatch(cfqq))
3882                        goto out_kick;
3883
3884                /*
3885                 * expired
3886                 */
3887                if (cfq_slice_used(cfqq))
3888                        goto expire;
3889
3890                /*
3891                 * only expire and reinvoke request handler, if there are
3892                 * other queues with pending requests
3893                 */
3894                if (!cfqd->busy_queues)
3895                        goto out_cont;
3896
3897                /*
3898                 * not expired and it has a request pending, let it dispatch
3899                 */
3900                if (!RB_EMPTY_ROOT(&cfqq->sort_list))
3901                        goto out_kick;
3902
3903                /*
3904                 * Queue depth flag is reset only when the idle didn't succeed
3905                 */
3906                cfq_clear_cfqq_deep(cfqq);
3907        }
3908expire:
3909        cfq_slice_expired(cfqd, timed_out);
3910out_kick:
3911        cfq_schedule_dispatch(cfqd);
3912out_cont:
3913        spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
3914}
3915
3916static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
3917{
3918        del_timer_sync(&cfqd->idle_slice_timer);
3919        cancel_work_sync(&cfqd->unplug_work);
3920}
3921
3922static void cfq_put_async_queues(struct cfq_data *cfqd)
3923{
3924        int i;
3925
3926        for (i = 0; i < IOPRIO_BE_NR; i++) {
3927                if (cfqd->async_cfqq[0][i])
3928                        cfq_put_queue(cfqd->async_cfqq[0][i]);
3929                if (cfqd->async_cfqq[1][i])
3930                        cfq_put_queue(cfqd->async_cfqq[1][i]);
3931        }
3932
3933        if (cfqd->async_idle_cfqq)
3934                cfq_put_queue(cfqd->async_idle_cfqq);
3935}
3936
3937static void cfq_exit_queue(struct elevator_queue *e)
3938{
3939        struct cfq_data *cfqd = e->elevator_data;
3940        struct request_queue *q = cfqd->queue;
3941
3942        cfq_shutdown_timer_wq(cfqd);
3943
3944        spin_lock_irq(q->queue_lock);
3945
3946        if (cfqd->active_queue)
3947                __cfq_slice_expired(cfqd, cfqd->active_queue, 0);
3948
3949        cfq_put_async_queues(cfqd);
3950
3951        spin_unlock_irq(q->queue_lock);
3952
3953        cfq_shutdown_timer_wq(cfqd);
3954
3955#ifdef CONFIG_CFQ_GROUP_IOSCHED
3956        blkcg_deactivate_policy(q, &blkcg_policy_cfq);
3957#else
3958        kfree(cfqd->root_group);
3959#endif
3960        kfree(cfqd);
3961}
3962
3963static int cfq_init_queue(struct request_queue *q)
3964{
3965        struct cfq_data *cfqd;
3966        struct blkcg_gq *blkg __maybe_unused;
3967        int i, ret;
3968
3969        cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node);
3970        if (!cfqd)
3971                return -ENOMEM;
3972
3973        cfqd->queue = q;
3974        q->elevator->elevator_data = cfqd;
3975
3976        /* Init root service tree */
3977        cfqd->grp_service_tree = CFQ_RB_ROOT;
3978
3979        /* Init root group and prefer root group over other groups by default */
3980#ifdef CONFIG_CFQ_GROUP_IOSCHED
3981        ret = blkcg_activate_policy(q, &blkcg_policy_cfq);
3982        if (ret)
3983                goto out_free;
3984
3985        cfqd->root_group = blkg_to_cfqg(q->root_blkg);
3986#else
3987        ret = -ENOMEM;
3988        cfqd->root_group = kzalloc_node(sizeof(*cfqd->root_group),
3989                                        GFP_KERNEL, cfqd->queue->node);
3990        if (!cfqd->root_group)
3991                goto out_free;
3992
3993        cfq_init_cfqg_base(cfqd->root_group);
3994#endif
3995        cfqd->root_group->weight = 2 * CFQ_WEIGHT_DEFAULT;
3996
3997        /*
3998         * Not strictly needed (since RB_ROOT just clears the node and we
3999         * zeroed cfqd on alloc), but better be safe in case someone decides
4000         * to add magic to the rb code
4001         */
4002        for (i = 0; i < CFQ_PRIO_LISTS; i++)
4003                cfqd->prio_trees[i] = RB_ROOT;
4004
4005        /*
4006         * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
4007         * Grab a permanent reference to it, so that the normal code flow
4008         * will not attempt to free it.  oom_cfqq is linked to root_group
4009         * but shouldn't hold a reference as it'll never be unlinked.  Lose
4010         * the reference from linking right away.
4011         */
4012        cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0);
4013        cfqd->oom_cfqq.ref++;
4014
4015        spin_lock_irq(q->queue_lock);
4016        cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, cfqd->root_group);
4017        cfqg_put(cfqd->root_group);
4018        spin_unlock_irq(q->queue_lock);
4019
4020        init_timer(&cfqd->idle_slice_timer);
4021        cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
4022        cfqd->idle_slice_timer.data = (unsigned long) cfqd;
4023
4024        INIT_WORK(&cfqd->unplug_work, cfq_kick_queue);
4025
4026        cfqd->cfq_quantum = cfq_quantum;
4027        cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
4028        cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
4029        cfqd->cfq_back_max = cfq_back_max;
4030        cfqd->cfq_back_penalty = cfq_back_penalty;
4031        cfqd->cfq_slice[0] = cfq_slice_async;
4032        cfqd->cfq_slice[1] = cfq_slice_sync;
4033        cfqd->cfq_target_latency = cfq_target_latency;
4034        cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
4035        cfqd->cfq_slice_idle = cfq_slice_idle;
4036        cfqd->cfq_group_idle = cfq_group_idle;
4037        cfqd->cfq_latency = 1;
4038        cfqd->hw_tag = -1;
4039        /*
4040         * we optimistically start assuming sync ops weren't delayed in last
4041         * second, in order to have larger depth for async operations.
4042         */
4043        cfqd->last_delayed_sync = jiffies - HZ;
4044        return 0;
4045
4046out_free:
4047        kfree(cfqd);
4048        return ret;
4049}
4050
4051/*
4052 * sysfs parts below -->
4053 */
4054static ssize_t
4055cfq_var_show(unsigned int var, char *page)
4056{
4057        return sprintf(page, "%d\n", var);
4058}
4059
4060static ssize_t
4061cfq_var_store(unsigned int *var, const char *page, size_t count)
4062{
4063        char *p = (char *) page;
4064
4065        *var = simple_strtoul(p, &p, 10);
4066        return count;
4067}
4068
4069#define SHOW_FUNCTION(__FUNC, __VAR, __CONV)                            \
4070static ssize_t __FUNC(struct elevator_queue *e, char *page)             \
4071{                                                                       \
4072        struct cfq_data *cfqd = e->elevator_data;                       \
4073        unsigned int __data = __VAR;                                    \
4074        if (__CONV)                                                     \
4075                __data = jiffies_to_msecs(__data);                      \
4076        return cfq_var_show(__data, (page));                            \
4077}
4078SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
4079SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
4080SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
4081SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0);
4082SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0);
4083SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
4084SHOW_FUNCTION(cfq_group_idle_show, cfqd->cfq_group_idle, 1);
4085SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
4086SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
4087SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
4088SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0);
4089SHOW_FUNCTION(cfq_target_latency_show, cfqd->cfq_target_latency, 1);
4090#undef SHOW_FUNCTION
4091
4092#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV)                 \
4093static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
4094{                                                                       \
4095        struct cfq_data *cfqd = e->elevator_data;                       \
4096        unsigned int __data;                                            \
4097        int ret = cfq_var_store(&__data, (page), count);                \
4098        if (__data < (MIN))                                             \
4099                __data = (MIN);                                         \
4100        else if (__data > (MAX))                                        \
4101                __data = (MAX);                                         \
4102        if (__CONV)                                                     \
4103                *(__PTR) = msecs_to_jiffies(__data);                    \
4104        else                                                            \
4105                *(__PTR) = __data;                                      \
4106        return ret;                                                     \
4107}
4108STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
4109STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1,
4110                UINT_MAX, 1);
4111STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1,
4112                UINT_MAX, 1);
4113STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
4114STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1,
4115                UINT_MAX, 0);
4116STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
4117STORE_FUNCTION(cfq_group_idle_store, &cfqd->cfq_group_idle, 0, UINT_MAX, 1);
4118STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
4119STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
4120STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
4121                UINT_MAX, 0);
4122STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0);
4123STORE_FUNCTION(cfq_target_latency_store, &cfqd->cfq_target_latency, 1, UINT_MAX, 1);
4124#undef STORE_FUNCTION
4125
4126#define CFQ_ATTR(name) \
4127        __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
4128
4129static struct elv_fs_entry cfq_attrs[] = {
4130        CFQ_ATTR(quantum),
4131        CFQ_ATTR(fifo_expire_sync),
4132        CFQ_ATTR(fifo_expire_async),
4133        CFQ_ATTR(back_seek_max),
4134        CFQ_ATTR(back_seek_penalty),
4135        CFQ_ATTR(slice_sync),
4136        CFQ_ATTR(slice_async),
4137        CFQ_ATTR(slice_async_rq),
4138        CFQ_ATTR(slice_idle),
4139        CFQ_ATTR(group_idle),
4140        CFQ_ATTR(low_latency),
4141        CFQ_ATTR(target_latency),
4142        __ATTR_NULL
4143};
4144
4145static struct elevator_type iosched_cfq = {
4146        .ops = {
4147                .elevator_merge_fn =            cfq_merge,
4148                .elevator_merged_fn =           cfq_merged_request,
4149                .elevator_merge_req_fn =        cfq_merged_requests,
4150                .elevator_allow_merge_fn =      cfq_allow_merge,
4151                .elevator_bio_merged_fn =       cfq_bio_merged,
4152                .elevator_dispatch_fn =         cfq_dispatch_requests,
4153                .elevator_add_req_fn =          cfq_insert_request,
4154                .elevator_activate_req_fn =     cfq_activate_request,
4155                .elevator_deactivate_req_fn =   cfq_deactivate_request,
4156                .elevator_completed_req_fn =    cfq_completed_request,
4157                .elevator_former_req_fn =       elv_rb_former_request,
4158                .elevator_latter_req_fn =       elv_rb_latter_request,
4159                .elevator_init_icq_fn =         cfq_init_icq,
4160                .elevator_exit_icq_fn =         cfq_exit_icq,
4161                .elevator_set_req_fn =          cfq_set_request,
4162                .elevator_put_req_fn =          cfq_put_request,
4163                .elevator_may_queue_fn =        cfq_may_queue,
4164                .elevator_init_fn =             cfq_init_queue,
4165                .elevator_exit_fn =             cfq_exit_queue,
4166        },
4167        .icq_size       =       sizeof(struct cfq_io_cq),
4168        .icq_align      =       __alignof__(struct cfq_io_cq),
4169        .elevator_attrs =       cfq_attrs,
4170        .elevator_name  =       "cfq",
4171        .elevator_owner =       THIS_MODULE,
4172};
4173
4174#ifdef CONFIG_CFQ_GROUP_IOSCHED
4175static struct blkcg_policy blkcg_policy_cfq = {
4176        .pd_size                = sizeof(struct cfq_group),
4177        .cftypes                = cfq_blkcg_files,
4178
4179        .pd_init_fn             = cfq_pd_init,
4180        .pd_reset_stats_fn      = cfq_pd_reset_stats,
4181};
4182#endif
4183
4184static int __init cfq_init(void)
4185{
4186        int ret;
4187
4188        /*
4189         * could be 0 on HZ < 1000 setups
4190         */
4191        if (!cfq_slice_async)
4192                cfq_slice_async = 1;
4193        if (!cfq_slice_idle)
4194                cfq_slice_idle = 1;
4195
4196#ifdef CONFIG_CFQ_GROUP_IOSCHED
4197        if (!cfq_group_idle)
4198                cfq_group_idle = 1;
4199
4200        ret = blkcg_policy_register(&blkcg_policy_cfq);
4201        if (ret)
4202                return ret;
4203#else
4204        cfq_group_idle = 0;
4205#endif
4206
4207        ret = -ENOMEM;
4208        cfq_pool = KMEM_CACHE(cfq_queue, 0);
4209        if (!cfq_pool)
4210                goto err_pol_unreg;
4211
4212        ret = elv_register(&iosched_cfq);
4213        if (ret)
4214                goto err_free_pool;
4215
4216        return 0;
4217
4218err_free_pool:
4219        kmem_cache_destroy(cfq_pool);
4220err_pol_unreg:
4221#ifdef CONFIG_CFQ_GROUP_IOSCHED
4222        blkcg_policy_unregister(&blkcg_policy_cfq);
4223#endif
4224        return ret;
4225}
4226
4227static void __exit cfq_exit(void)
4228{
4229#ifdef CONFIG_CFQ_GROUP_IOSCHED
4230        blkcg_policy_unregister(&blkcg_policy_cfq);
4231#endif
4232        elv_unregister(&iosched_cfq);
4233        kmem_cache_destroy(cfq_pool);
4234}
4235
4236module_init(cfq_init);
4237module_exit(cfq_exit);
4238
4239MODULE_AUTHOR("Jens Axboe");
4240MODULE_LICENSE("GPL");
4241MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");
4242
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