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/ktime.h>
  14#include <linux/rbtree.h>
  15#include <linux/ioprio.h>
  16#include <linux/blktrace_api.h>
  17#include <linux/blk-cgroup.h>
  18#include "blk.h"
  19
  20/*
  21 * tunables
  22 */
  23/* max queue in one round of service */
  24static const int cfq_quantum = 8;
  25static const u64 cfq_fifo_expire[2] = { NSEC_PER_SEC / 4, NSEC_PER_SEC / 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 u64 cfq_slice_sync = NSEC_PER_SEC / 10;
  31static u64 cfq_slice_async = NSEC_PER_SEC / 25;
  32static const int cfq_slice_async_rq = 2;
  33static u64 cfq_slice_idle = NSEC_PER_SEC / 125;
  34static u64 cfq_group_idle = NSEC_PER_SEC / 125;
  35static const u64 cfq_target_latency = (u64)NSEC_PER_SEC * 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          (NSEC_PER_SEC / 5)
  42
  43/*
  44 * below this threshold, we consider thinktime immediate
  45 */
  46#define CFQ_MIN_TT              (2 * NSEC_PER_SEC / HZ)
  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
  70/* blkio-related constants */
  71#define CFQ_WEIGHT_LEGACY_MIN   10
  72#define CFQ_WEIGHT_LEGACY_DFL   500
  73#define CFQ_WEIGHT_LEGACY_MAX   1000
  74
  75struct cfq_ttime {
  76        u64 last_end_request;
  77
  78        u64 ttime_total;
  79        u64 ttime_mean;
  80        unsigned long ttime_samples;
  81};
  82
  83/*
  84 * Most of our rbtree usage is for sorting with min extraction, so
  85 * if we cache the leftmost node we don't have to walk down the tree
  86 * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should
  87 * move this into the elevator for the rq sorting as well.
  88 */
  89struct cfq_rb_root {
  90        struct rb_root rb;
  91        struct rb_node *left;
  92        unsigned count;
  93        u64 min_vdisktime;
  94        struct cfq_ttime ttime;
  95};
  96#define CFQ_RB_ROOT     (struct cfq_rb_root) { .rb = RB_ROOT, \
  97                        .ttime = {.last_end_request = ktime_get_ns(),},}
  98
  99/*
 100 * Per process-grouping structure
 101 */
 102struct cfq_queue {
 103        /* reference count */
 104        int ref;
 105        /* various state flags, see below */
 106        unsigned int flags;
 107        /* parent cfq_data */
 108        struct cfq_data *cfqd;
 109        /* service_tree member */
 110        struct rb_node rb_node;
 111        /* service_tree key */
 112        u64 rb_key;
 113        /* prio tree member */
 114        struct rb_node p_node;
 115        /* prio tree root we belong to, if any */
 116        struct rb_root *p_root;
 117        /* sorted list of pending requests */
 118        struct rb_root sort_list;
 119        /* if fifo isn't expired, next request to serve */
 120        struct request *next_rq;
 121        /* requests queued in sort_list */
 122        int queued[2];
 123        /* currently allocated requests */
 124        int allocated[2];
 125        /* fifo list of requests in sort_list */
 126        struct list_head fifo;
 127
 128        /* time when queue got scheduled in to dispatch first request. */
 129        u64 dispatch_start;
 130        u64 allocated_slice;
 131        u64 slice_dispatch;
 132        /* time when first request from queue completed and slice started. */
 133        u64 slice_start;
 134        u64 slice_end;
 135        s64 slice_resid;
 136
 137        /* pending priority requests */
 138        int prio_pending;
 139        /* number of requests that are on the dispatch list or inside driver */
 140        int dispatched;
 141
 142        /* io prio of this group */
 143        unsigned short ioprio, org_ioprio;
 144        unsigned short ioprio_class, org_ioprio_class;
 145
 146        pid_t pid;
 147
 148        u32 seek_history;
 149        sector_t last_request_pos;
 150
 151        struct cfq_rb_root *service_tree;
 152        struct cfq_queue *new_cfqq;
 153        struct cfq_group *cfqg;
 154        /* Number of sectors dispatched from queue in single dispatch round */
 155        unsigned long nr_sectors;
 156};
 157
 158/*
 159 * First index in the service_trees.
 160 * IDLE is handled separately, so it has negative index
 161 */
 162enum wl_class_t {
 163        BE_WORKLOAD = 0,
 164        RT_WORKLOAD = 1,
 165        IDLE_WORKLOAD = 2,
 166        CFQ_PRIO_NR,
 167};
 168
 169/*
 170 * Second index in the service_trees.
 171 */
 172enum wl_type_t {
 173        ASYNC_WORKLOAD = 0,
 174        SYNC_NOIDLE_WORKLOAD = 1,
 175        SYNC_WORKLOAD = 2
 176};
 177
 178struct cfqg_stats {
 179#ifdef CONFIG_CFQ_GROUP_IOSCHED
 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 disk time and nr sectors dispatched by this group */
 189        struct blkg_stat                time;
 190#ifdef CONFIG_DEBUG_BLK_CGROUP
 191        /* time not charged to this cgroup */
 192        struct blkg_stat                unaccounted_time;
 193        /* sum of number of ios queued across all samples */
 194        struct blkg_stat                avg_queue_size_sum;
 195        /* count of samples taken for average */
 196        struct blkg_stat                avg_queue_size_samples;
 197        /* how many times this group has been removed from service tree */
 198        struct blkg_stat                dequeue;
 199        /* total time spent waiting for it to be assigned a timeslice. */
 200        struct blkg_stat                group_wait_time;
 201        /* time spent idling for this blkcg_gq */
 202        struct blkg_stat                idle_time;
 203        /* total time with empty current active q with other requests queued */
 204        struct blkg_stat                empty_time;
 205        /* fields after this shouldn't be cleared on stat reset */
 206        uint64_t                        start_group_wait_time;
 207        uint64_t                        start_idle_time;
 208        uint64_t                        start_empty_time;
 209        uint16_t                        flags;
 210#endif  /* CONFIG_DEBUG_BLK_CGROUP */
 211#endif  /* CONFIG_CFQ_GROUP_IOSCHED */
 212};
 213
 214/* Per-cgroup data */
 215struct cfq_group_data {
 216        /* must be the first member */
 217        struct blkcg_policy_data cpd;
 218
 219        unsigned int weight;
 220        unsigned int leaf_weight;
 221};
 222
 223/* This is per cgroup per device grouping structure */
 224struct cfq_group {
 225        /* must be the first member */
 226        struct blkg_policy_data pd;
 227
 228        /* group service_tree member */
 229        struct rb_node rb_node;
 230
 231        /* group service_tree key */
 232        u64 vdisktime;
 233
 234        /*
 235         * The number of active cfqgs and sum of their weights under this
 236         * cfqg.  This covers this cfqg's leaf_weight and all children's
 237         * weights, but does not cover weights of further descendants.
 238         *
 239         * If a cfqg is on the service tree, it's active.  An active cfqg
 240         * also activates its parent and contributes to the children_weight
 241         * of the parent.
 242         */
 243        int nr_active;
 244        unsigned int children_weight;
 245
 246        /*
 247         * vfraction is the fraction of vdisktime that the tasks in this
 248         * cfqg are entitled to.  This is determined by compounding the
 249         * ratios walking up from this cfqg to the root.
 250         *
 251         * It is in fixed point w/ CFQ_SERVICE_SHIFT and the sum of all
 252         * vfractions on a service tree is approximately 1.  The sum may
 253         * deviate a bit due to rounding errors and fluctuations caused by
 254         * cfqgs entering and leaving the service tree.
 255         */
 256        unsigned int vfraction;
 257
 258        /*
 259         * There are two weights - (internal) weight is the weight of this
 260         * cfqg against the sibling cfqgs.  leaf_weight is the wight of
 261         * this cfqg against the child cfqgs.  For the root cfqg, both
 262         * weights are kept in sync for backward compatibility.
 263         */
 264        unsigned int weight;
 265        unsigned int new_weight;
 266        unsigned int dev_weight;
 267
 268        unsigned int leaf_weight;
 269        unsigned int new_leaf_weight;
 270        unsigned int dev_leaf_weight;
 271
 272        /* number of cfqq currently on this group */
 273        int nr_cfqq;
 274
 275        /*
 276         * Per group busy queues average. Useful for workload slice calc. We
 277         * create the array for each prio class but at run time it is used
 278         * only for RT and BE class and slot for IDLE class remains unused.
 279         * This is primarily done to avoid confusion and a gcc warning.
 280         */
 281        unsigned int busy_queues_avg[CFQ_PRIO_NR];
 282        /*
 283         * rr lists of queues with requests. We maintain service trees for
 284         * RT and BE classes. These trees are subdivided in subclasses
 285         * of SYNC, SYNC_NOIDLE and ASYNC based on workload type. For IDLE
 286         * class there is no subclassification and all the cfq queues go on
 287         * a single tree service_tree_idle.
 288         * Counts are embedded in the cfq_rb_root
 289         */
 290        struct cfq_rb_root service_trees[2][3];
 291        struct cfq_rb_root service_tree_idle;
 292
 293        u64 saved_wl_slice;
 294        enum wl_type_t saved_wl_type;
 295        enum wl_class_t saved_wl_class;
 296
 297        /* number of requests that are on the dispatch list or inside driver */
 298        int dispatched;
 299        struct cfq_ttime ttime;
 300        struct cfqg_stats stats;        /* stats for this cfqg */
 301
 302        /* async queue for each priority case */
 303        struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR];
 304        struct cfq_queue *async_idle_cfqq;
 305
 306};
 307
 308struct cfq_io_cq {
 309        struct io_cq            icq;            /* must be the first member */
 310        struct cfq_queue        *cfqq[2];
 311        struct cfq_ttime        ttime;
 312        int                     ioprio;         /* the current ioprio */
 313#ifdef CONFIG_CFQ_GROUP_IOSCHED
 314        uint64_t                blkcg_serial_nr; /* the current blkcg serial */
 315#endif
 316};
 317
 318/*
 319 * Per block device queue structure
 320 */
 321struct cfq_data {
 322        struct request_queue *queue;
 323        /* Root service tree for cfq_groups */
 324        struct cfq_rb_root grp_service_tree;
 325        struct cfq_group *root_group;
 326
 327        /*
 328         * The priority currently being served
 329         */
 330        enum wl_class_t serving_wl_class;
 331        enum wl_type_t serving_wl_type;
 332        u64 workload_expires;
 333        struct cfq_group *serving_group;
 334
 335        /*
 336         * Each priority tree is sorted by next_request position.  These
 337         * trees are used when determining if two or more queues are
 338         * interleaving requests (see cfq_close_cooperator).
 339         */
 340        struct rb_root prio_trees[CFQ_PRIO_LISTS];
 341
 342        unsigned int busy_queues;
 343        unsigned int busy_sync_queues;
 344
 345        int rq_in_driver;
 346        int rq_in_flight[2];
 347
 348        /*
 349         * queue-depth detection
 350         */
 351        int rq_queued;
 352        int hw_tag;
 353        /*
 354         * hw_tag can be
 355         * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection)
 356         *  1 => NCQ is present (hw_tag_est_depth is the estimated max depth)
 357         *  0 => no NCQ
 358         */
 359        int hw_tag_est_depth;
 360        unsigned int hw_tag_samples;
 361
 362        /*
 363         * idle window management
 364         */
 365        struct hrtimer idle_slice_timer;
 366        struct work_struct unplug_work;
 367
 368        struct cfq_queue *active_queue;
 369        struct cfq_io_cq *active_cic;
 370
 371        sector_t last_position;
 372
 373        /*
 374         * tunables, see top of file
 375         */
 376        unsigned int cfq_quantum;
 377        unsigned int cfq_back_penalty;
 378        unsigned int cfq_back_max;
 379        unsigned int cfq_slice_async_rq;
 380        unsigned int cfq_latency;
 381        u64 cfq_fifo_expire[2];
 382        u64 cfq_slice[2];
 383        u64 cfq_slice_idle;
 384        u64 cfq_group_idle;
 385        u64 cfq_target_latency;
 386
 387        /*
 388         * Fallback dummy cfqq for extreme OOM conditions
 389         */
 390        struct cfq_queue oom_cfqq;
 391
 392        u64 last_delayed_sync;
 393};
 394
 395static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd);
 396static void cfq_put_queue(struct cfq_queue *cfqq);
 397
 398static struct cfq_rb_root *st_for(struct cfq_group *cfqg,
 399                                            enum wl_class_t class,
 400                                            enum wl_type_t type)
 401{
 402        if (!cfqg)
 403                return NULL;
 404
 405        if (class == IDLE_WORKLOAD)
 406                return &cfqg->service_tree_idle;
 407
 408        return &cfqg->service_trees[class][type];
 409}
 410
 411enum cfqq_state_flags {
 412        CFQ_CFQQ_FLAG_on_rr = 0,        /* on round-robin busy list */
 413        CFQ_CFQQ_FLAG_wait_request,     /* waiting for a request */
 414        CFQ_CFQQ_FLAG_must_dispatch,    /* must be allowed a dispatch */
 415        CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */
 416        CFQ_CFQQ_FLAG_fifo_expire,      /* FIFO checked in this slice */
 417        CFQ_CFQQ_FLAG_idle_window,      /* slice idling enabled */
 418        CFQ_CFQQ_FLAG_prio_changed,     /* task priority has changed */
 419        CFQ_CFQQ_FLAG_slice_new,        /* no requests dispatched in slice */
 420        CFQ_CFQQ_FLAG_sync,             /* synchronous queue */
 421        CFQ_CFQQ_FLAG_coop,             /* cfqq is shared */
 422        CFQ_CFQQ_FLAG_split_coop,       /* shared cfqq will be splitted */
 423        CFQ_CFQQ_FLAG_deep,             /* sync cfqq experienced large depth */
 424        CFQ_CFQQ_FLAG_wait_busy,        /* Waiting for next request */
 425};
 426
 427#define CFQ_CFQQ_FNS(name)                                              \
 428static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq)         \
 429{                                                                       \
 430        (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name);                   \
 431}                                                                       \
 432static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq)        \
 433{                                                                       \
 434        (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name);                  \
 435}                                                                       \
 436static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq)         \
 437{                                                                       \
 438        return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0;      \
 439}
 440
 441CFQ_CFQQ_FNS(on_rr);
 442CFQ_CFQQ_FNS(wait_request);
 443CFQ_CFQQ_FNS(must_dispatch);
 444CFQ_CFQQ_FNS(must_alloc_slice);
 445CFQ_CFQQ_FNS(fifo_expire);
 446CFQ_CFQQ_FNS(idle_window);
 447CFQ_CFQQ_FNS(prio_changed);
 448CFQ_CFQQ_FNS(slice_new);
 449CFQ_CFQQ_FNS(sync);
 450CFQ_CFQQ_FNS(coop);
 451CFQ_CFQQ_FNS(split_coop);
 452CFQ_CFQQ_FNS(deep);
 453CFQ_CFQQ_FNS(wait_busy);
 454#undef CFQ_CFQQ_FNS
 455
 456#if defined(CONFIG_CFQ_GROUP_IOSCHED) && defined(CONFIG_DEBUG_BLK_CGROUP)
 457
 458/* cfqg stats flags */
 459enum cfqg_stats_flags {
 460        CFQG_stats_waiting = 0,
 461        CFQG_stats_idling,
 462        CFQG_stats_empty,
 463};
 464
 465#define CFQG_FLAG_FNS(name)                                             \
 466static inline void cfqg_stats_mark_##name(struct cfqg_stats *stats)     \
 467{                                                                       \
 468        stats->flags |= (1 << CFQG_stats_##name);                       \
 469}                                                                       \
 470static inline void cfqg_stats_clear_##name(struct cfqg_stats *stats)    \
 471{                                                                       \
 472        stats->flags &= ~(1 << CFQG_stats_##name);                      \
 473}                                                                       \
 474static inline int cfqg_stats_##name(struct cfqg_stats *stats)           \
 475{                                                                       \
 476        return (stats->flags & (1 << CFQG_stats_##name)) != 0;          \
 477}                                                                       \
 478
 479CFQG_FLAG_FNS(waiting)
 480CFQG_FLAG_FNS(idling)
 481CFQG_FLAG_FNS(empty)
 482#undef CFQG_FLAG_FNS
 483
 484/* This should be called with the queue_lock held. */
 485static void cfqg_stats_update_group_wait_time(struct cfqg_stats *stats)
 486{
 487        unsigned long long now;
 488
 489        if (!cfqg_stats_waiting(stats))
 490                return;
 491
 492        now = sched_clock();
 493        if (time_after64(now, stats->start_group_wait_time))
 494                blkg_stat_add(&stats->group_wait_time,
 495                              now - stats->start_group_wait_time);
 496        cfqg_stats_clear_waiting(stats);
 497}
 498
 499/* This should be called with the queue_lock held. */
 500static void cfqg_stats_set_start_group_wait_time(struct cfq_group *cfqg,
 501                                                 struct cfq_group *curr_cfqg)
 502{
 503        struct cfqg_stats *stats = &cfqg->stats;
 504
 505        if (cfqg_stats_waiting(stats))
 506                return;
 507        if (cfqg == curr_cfqg)
 508                return;
 509        stats->start_group_wait_time = sched_clock();
 510        cfqg_stats_mark_waiting(stats);
 511}
 512
 513/* This should be called with the queue_lock held. */
 514static void cfqg_stats_end_empty_time(struct cfqg_stats *stats)
 515{
 516        unsigned long long now;
 517
 518        if (!cfqg_stats_empty(stats))
 519                return;
 520
 521        now = sched_clock();
 522        if (time_after64(now, stats->start_empty_time))
 523                blkg_stat_add(&stats->empty_time,
 524                              now - stats->start_empty_time);
 525        cfqg_stats_clear_empty(stats);
 526}
 527
 528static void cfqg_stats_update_dequeue(struct cfq_group *cfqg)
 529{
 530        blkg_stat_add(&cfqg->stats.dequeue, 1);
 531}
 532
 533static void cfqg_stats_set_start_empty_time(struct cfq_group *cfqg)
 534{
 535        struct cfqg_stats *stats = &cfqg->stats;
 536
 537        if (blkg_rwstat_total(&stats->queued))
 538                return;
 539
 540        /*
 541         * group is already marked empty. This can happen if cfqq got new
 542         * request in parent group and moved to this group while being added
 543         * to service tree. Just ignore the event and move on.
 544         */
 545        if (cfqg_stats_empty(stats))
 546                return;
 547
 548        stats->start_empty_time = sched_clock();
 549        cfqg_stats_mark_empty(stats);
 550}
 551
 552static void cfqg_stats_update_idle_time(struct cfq_group *cfqg)
 553{
 554        struct cfqg_stats *stats = &cfqg->stats;
 555
 556        if (cfqg_stats_idling(stats)) {
 557                unsigned long long now = sched_clock();
 558
 559                if (time_after64(now, stats->start_idle_time))
 560                        blkg_stat_add(&stats->idle_time,
 561                                      now - stats->start_idle_time);
 562                cfqg_stats_clear_idling(stats);
 563        }
 564}
 565
 566static void cfqg_stats_set_start_idle_time(struct cfq_group *cfqg)
 567{
 568        struct cfqg_stats *stats = &cfqg->stats;
 569
 570        BUG_ON(cfqg_stats_idling(stats));
 571
 572        stats->start_idle_time = sched_clock();
 573        cfqg_stats_mark_idling(stats);
 574}
 575
 576static void cfqg_stats_update_avg_queue_size(struct cfq_group *cfqg)
 577{
 578        struct cfqg_stats *stats = &cfqg->stats;
 579
 580        blkg_stat_add(&stats->avg_queue_size_sum,
 581                      blkg_rwstat_total(&stats->queued));
 582        blkg_stat_add(&stats->avg_queue_size_samples, 1);
 583        cfqg_stats_update_group_wait_time(stats);
 584}
 585
 586#else   /* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */
 587
 588static inline void cfqg_stats_set_start_group_wait_time(struct cfq_group *cfqg, struct cfq_group *curr_cfqg) { }
 589static inline void cfqg_stats_end_empty_time(struct cfqg_stats *stats) { }
 590static inline void cfqg_stats_update_dequeue(struct cfq_group *cfqg) { }
 591static inline void cfqg_stats_set_start_empty_time(struct cfq_group *cfqg) { }
 592static inline void cfqg_stats_update_idle_time(struct cfq_group *cfqg) { }
 593static inline void cfqg_stats_set_start_idle_time(struct cfq_group *cfqg) { }
 594static inline void cfqg_stats_update_avg_queue_size(struct cfq_group *cfqg) { }
 595
 596#endif  /* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */
 597
 598#ifdef CONFIG_CFQ_GROUP_IOSCHED
 599
 600static inline struct cfq_group *pd_to_cfqg(struct blkg_policy_data *pd)
 601{
 602        return pd ? container_of(pd, struct cfq_group, pd) : NULL;
 603}
 604
 605static struct cfq_group_data
 606*cpd_to_cfqgd(struct blkcg_policy_data *cpd)
 607{
 608        return cpd ? container_of(cpd, struct cfq_group_data, cpd) : NULL;
 609}
 610
 611static inline struct blkcg_gq *cfqg_to_blkg(struct cfq_group *cfqg)
 612{
 613        return pd_to_blkg(&cfqg->pd);
 614}
 615
 616static struct blkcg_policy blkcg_policy_cfq;
 617
 618static inline struct cfq_group *blkg_to_cfqg(struct blkcg_gq *blkg)
 619{
 620        return pd_to_cfqg(blkg_to_pd(blkg, &blkcg_policy_cfq));
 621}
 622
 623static struct cfq_group_data *blkcg_to_cfqgd(struct blkcg *blkcg)
 624{
 625        return cpd_to_cfqgd(blkcg_to_cpd(blkcg, &blkcg_policy_cfq));
 626}
 627
 628static inline struct cfq_group *cfqg_parent(struct cfq_group *cfqg)
 629{
 630        struct blkcg_gq *pblkg = cfqg_to_blkg(cfqg)->parent;
 631
 632        return pblkg ? blkg_to_cfqg(pblkg) : NULL;
 633}
 634
 635static inline bool cfqg_is_descendant(struct cfq_group *cfqg,
 636                                      struct cfq_group *ancestor)
 637{
 638        return cgroup_is_descendant(cfqg_to_blkg(cfqg)->blkcg->css.cgroup,
 639                                    cfqg_to_blkg(ancestor)->blkcg->css.cgroup);
 640}
 641
 642static inline void cfqg_get(struct cfq_group *cfqg)
 643{
 644        return blkg_get(cfqg_to_blkg(cfqg));
 645}
 646
 647static inline void cfqg_put(struct cfq_group *cfqg)
 648{
 649        return blkg_put(cfqg_to_blkg(cfqg));
 650}
 651
 652#define cfq_log_cfqq(cfqd, cfqq, fmt, args...)  do {                    \
 653        char __pbuf[128];                                               \
 654                                                                        \
 655        blkg_path(cfqg_to_blkg((cfqq)->cfqg), __pbuf, sizeof(__pbuf));  \
 656        blk_add_trace_msg((cfqd)->queue, "cfq%d%c%c %s " fmt, (cfqq)->pid, \
 657                        cfq_cfqq_sync((cfqq)) ? 'S' : 'A',              \
 658                        cfqq_type((cfqq)) == SYNC_NOIDLE_WORKLOAD ? 'N' : ' ',\
 659                          __pbuf, ##args);                              \
 660} while (0)
 661
 662#define cfq_log_cfqg(cfqd, cfqg, fmt, args...)  do {                    \
 663        char __pbuf[128];                                               \
 664                                                                        \
 665        blkg_path(cfqg_to_blkg(cfqg), __pbuf, sizeof(__pbuf));          \
 666        blk_add_trace_msg((cfqd)->queue, "%s " fmt, __pbuf, ##args);    \
 667} while (0)
 668
 669static inline void cfqg_stats_update_io_add(struct cfq_group *cfqg,
 670                                            struct cfq_group *curr_cfqg, int op,
 671                                            int op_flags)
 672{
 673        blkg_rwstat_add(&cfqg->stats.queued, op, op_flags, 1);
 674        cfqg_stats_end_empty_time(&cfqg->stats);
 675        cfqg_stats_set_start_group_wait_time(cfqg, curr_cfqg);
 676}
 677
 678static inline void cfqg_stats_update_timeslice_used(struct cfq_group *cfqg,
 679                        uint64_t time, unsigned long unaccounted_time)
 680{
 681        blkg_stat_add(&cfqg->stats.time, time);
 682#ifdef CONFIG_DEBUG_BLK_CGROUP
 683        blkg_stat_add(&cfqg->stats.unaccounted_time, unaccounted_time);
 684#endif
 685}
 686
 687static inline void cfqg_stats_update_io_remove(struct cfq_group *cfqg, int op,
 688                                               int op_flags)
 689{
 690        blkg_rwstat_add(&cfqg->stats.queued, op, op_flags, -1);
 691}
 692
 693static inline void cfqg_stats_update_io_merged(struct cfq_group *cfqg, int op,
 694                                               int op_flags)
 695{
 696        blkg_rwstat_add(&cfqg->stats.merged, op, op_flags, 1);
 697}
 698
 699static inline void cfqg_stats_update_completion(struct cfq_group *cfqg,
 700                        uint64_t start_time, uint64_t io_start_time, int op,
 701                        int op_flags)
 702{
 703        struct cfqg_stats *stats = &cfqg->stats;
 704        unsigned long long now = sched_clock();
 705
 706        if (time_after64(now, io_start_time))
 707                blkg_rwstat_add(&stats->service_time, op, op_flags,
 708                                now - io_start_time);
 709        if (time_after64(io_start_time, start_time))
 710                blkg_rwstat_add(&stats->wait_time, op, op_flags,
 711                                io_start_time - start_time);
 712}
 713
 714/* @stats = 0 */
 715static void cfqg_stats_reset(struct cfqg_stats *stats)
 716{
 717        /* queued stats shouldn't be cleared */
 718        blkg_rwstat_reset(&stats->merged);
 719        blkg_rwstat_reset(&stats->service_time);
 720        blkg_rwstat_reset(&stats->wait_time);
 721        blkg_stat_reset(&stats->time);
 722#ifdef CONFIG_DEBUG_BLK_CGROUP
 723        blkg_stat_reset(&stats->unaccounted_time);
 724        blkg_stat_reset(&stats->avg_queue_size_sum);
 725        blkg_stat_reset(&stats->avg_queue_size_samples);
 726        blkg_stat_reset(&stats->dequeue);
 727        blkg_stat_reset(&stats->group_wait_time);
 728        blkg_stat_reset(&stats->idle_time);
 729        blkg_stat_reset(&stats->empty_time);
 730#endif
 731}
 732
 733/* @to += @from */
 734static void cfqg_stats_add_aux(struct cfqg_stats *to, struct cfqg_stats *from)
 735{
 736        /* queued stats shouldn't be cleared */
 737        blkg_rwstat_add_aux(&to->merged, &from->merged);
 738        blkg_rwstat_add_aux(&to->service_time, &from->service_time);
 739        blkg_rwstat_add_aux(&to->wait_time, &from->wait_time);
 740        blkg_stat_add_aux(&from->time, &from->time);
 741#ifdef CONFIG_DEBUG_BLK_CGROUP
 742        blkg_stat_add_aux(&to->unaccounted_time, &from->unaccounted_time);
 743        blkg_stat_add_aux(&to->avg_queue_size_sum, &from->avg_queue_size_sum);
 744        blkg_stat_add_aux(&to->avg_queue_size_samples, &from->avg_queue_size_samples);
 745        blkg_stat_add_aux(&to->dequeue, &from->dequeue);
 746        blkg_stat_add_aux(&to->group_wait_time, &from->group_wait_time);
 747        blkg_stat_add_aux(&to->idle_time, &from->idle_time);
 748        blkg_stat_add_aux(&to->empty_time, &from->empty_time);
 749#endif
 750}
 751
 752/*
 753 * Transfer @cfqg's stats to its parent's aux counts so that the ancestors'
 754 * recursive stats can still account for the amount used by this cfqg after
 755 * it's gone.
 756 */
 757static void cfqg_stats_xfer_dead(struct cfq_group *cfqg)
 758{
 759        struct cfq_group *parent = cfqg_parent(cfqg);
 760
 761        lockdep_assert_held(cfqg_to_blkg(cfqg)->q->queue_lock);
 762
 763        if (unlikely(!parent))
 764                return;
 765
 766        cfqg_stats_add_aux(&parent->stats, &cfqg->stats);
 767        cfqg_stats_reset(&cfqg->stats);
 768}
 769
 770#else   /* CONFIG_CFQ_GROUP_IOSCHED */
 771
 772static inline struct cfq_group *cfqg_parent(struct cfq_group *cfqg) { return NULL; }
 773static inline bool cfqg_is_descendant(struct cfq_group *cfqg,
 774                                      struct cfq_group *ancestor)
 775{
 776        return true;
 777}
 778static inline void cfqg_get(struct cfq_group *cfqg) { }
 779static inline void cfqg_put(struct cfq_group *cfqg) { }
 780
 781#define cfq_log_cfqq(cfqd, cfqq, fmt, args...)  \
 782        blk_add_trace_msg((cfqd)->queue, "cfq%d%c%c " fmt, (cfqq)->pid, \
 783                        cfq_cfqq_sync((cfqq)) ? 'S' : 'A',              \
 784                        cfqq_type((cfqq)) == SYNC_NOIDLE_WORKLOAD ? 'N' : ' ',\
 785                                ##args)
 786#define cfq_log_cfqg(cfqd, cfqg, fmt, args...)          do {} while (0)
 787
 788static inline void cfqg_stats_update_io_add(struct cfq_group *cfqg,
 789                        struct cfq_group *curr_cfqg, int op, int op_flags) { }
 790static inline void cfqg_stats_update_timeslice_used(struct cfq_group *cfqg,
 791                        uint64_t time, unsigned long unaccounted_time) { }
 792static inline void cfqg_stats_update_io_remove(struct cfq_group *cfqg, int op,
 793                        int op_flags) { }
 794static inline void cfqg_stats_update_io_merged(struct cfq_group *cfqg, int op,
 795                        int op_flags) { }
 796static inline void cfqg_stats_update_completion(struct cfq_group *cfqg,
 797                        uint64_t start_time, uint64_t io_start_time, int op,
 798                        int op_flags) { }
 799
 800#endif  /* CONFIG_CFQ_GROUP_IOSCHED */
 801
 802#define cfq_log(cfqd, fmt, args...)     \
 803        blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
 804
 805/* Traverses through cfq group service trees */
 806#define for_each_cfqg_st(cfqg, i, j, st) \
 807        for (i = 0; i <= IDLE_WORKLOAD; i++) \
 808                for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
 809                        : &cfqg->service_tree_idle; \
 810                        (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \
 811                        (i == IDLE_WORKLOAD && j == 0); \
 812                        j++, st = i < IDLE_WORKLOAD ? \
 813                        &cfqg->service_trees[i][j]: NULL) \
 814
 815static inline bool cfq_io_thinktime_big(struct cfq_data *cfqd,
 816        struct cfq_ttime *ttime, bool group_idle)
 817{
 818        u64 slice;
 819        if (!sample_valid(ttime->ttime_samples))
 820                return false;
 821        if (group_idle)
 822                slice = cfqd->cfq_group_idle;
 823        else
 824                slice = cfqd->cfq_slice_idle;
 825        return ttime->ttime_mean > slice;
 826}
 827
 828static inline bool iops_mode(struct cfq_data *cfqd)
 829{
 830        /*
 831         * If we are not idling on queues and it is a NCQ drive, parallel
 832         * execution of requests is on and measuring time is not possible
 833         * in most of the cases until and unless we drive shallower queue
 834         * depths and that becomes a performance bottleneck. In such cases
 835         * switch to start providing fairness in terms of number of IOs.
 836         */
 837        if (!cfqd->cfq_slice_idle && cfqd->hw_tag)
 838                return true;
 839        else
 840                return false;
 841}
 842
 843static inline enum wl_class_t cfqq_class(struct cfq_queue *cfqq)
 844{
 845        if (cfq_class_idle(cfqq))
 846                return IDLE_WORKLOAD;
 847        if (cfq_class_rt(cfqq))
 848                return RT_WORKLOAD;
 849        return BE_WORKLOAD;
 850}
 851
 852
 853static enum wl_type_t cfqq_type(struct cfq_queue *cfqq)
 854{
 855        if (!cfq_cfqq_sync(cfqq))
 856                return ASYNC_WORKLOAD;
 857        if (!cfq_cfqq_idle_window(cfqq))
 858                return SYNC_NOIDLE_WORKLOAD;
 859        return SYNC_WORKLOAD;
 860}
 861
 862static inline int cfq_group_busy_queues_wl(enum wl_class_t wl_class,
 863                                        struct cfq_data *cfqd,
 864                                        struct cfq_group *cfqg)
 865{
 866        if (wl_class == IDLE_WORKLOAD)
 867                return cfqg->service_tree_idle.count;
 868
 869        return cfqg->service_trees[wl_class][ASYNC_WORKLOAD].count +
 870                cfqg->service_trees[wl_class][SYNC_NOIDLE_WORKLOAD].count +
 871                cfqg->service_trees[wl_class][SYNC_WORKLOAD].count;
 872}
 873
 874static inline int cfqg_busy_async_queues(struct cfq_data *cfqd,
 875                                        struct cfq_group *cfqg)
 876{
 877        return cfqg->service_trees[RT_WORKLOAD][ASYNC_WORKLOAD].count +
 878                cfqg->service_trees[BE_WORKLOAD][ASYNC_WORKLOAD].count;
 879}
 880
 881static void cfq_dispatch_insert(struct request_queue *, struct request *);
 882static struct cfq_queue *cfq_get_queue(struct cfq_data *cfqd, bool is_sync,
 883                                       struct cfq_io_cq *cic, struct bio *bio);
 884
 885static inline struct cfq_io_cq *icq_to_cic(struct io_cq *icq)
 886{
 887        /* cic->icq is the first member, %NULL will convert to %NULL */
 888        return container_of(icq, struct cfq_io_cq, icq);
 889}
 890
 891static inline struct cfq_io_cq *cfq_cic_lookup(struct cfq_data *cfqd,
 892                                               struct io_context *ioc)
 893{
 894        if (ioc)
 895                return icq_to_cic(ioc_lookup_icq(ioc, cfqd->queue));
 896        return NULL;
 897}
 898
 899static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_cq *cic, bool is_sync)
 900{
 901        return cic->cfqq[is_sync];
 902}
 903
 904static inline void cic_set_cfqq(struct cfq_io_cq *cic, struct cfq_queue *cfqq,
 905                                bool is_sync)
 906{
 907        cic->cfqq[is_sync] = cfqq;
 908}
 909
 910static inline struct cfq_data *cic_to_cfqd(struct cfq_io_cq *cic)
 911{
 912        return cic->icq.q->elevator->elevator_data;
 913}
 914
 915/*
 916 * We regard a request as SYNC, if it's either a read or has the SYNC bit
 917 * set (in which case it could also be direct WRITE).
 918 */
 919static inline bool cfq_bio_sync(struct bio *bio)
 920{
 921        return bio_data_dir(bio) == READ || (bio->bi_opf & REQ_SYNC);
 922}
 923
 924/*
 925 * scheduler run of queue, if there are requests pending and no one in the
 926 * driver that will restart queueing
 927 */
 928static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
 929{
 930        if (cfqd->busy_queues) {
 931                cfq_log(cfqd, "schedule dispatch");
 932                kblockd_schedule_work(&cfqd->unplug_work);
 933        }
 934}
 935
 936/*
 937 * Scale schedule slice based on io priority. Use the sync time slice only
 938 * if a queue is marked sync and has sync io queued. A sync queue with async
 939 * io only, should not get full sync slice length.
 940 */
 941static inline u64 cfq_prio_slice(struct cfq_data *cfqd, bool sync,
 942                                 unsigned short prio)
 943{
 944        u64 base_slice = cfqd->cfq_slice[sync];
 945        u64 slice = div_u64(base_slice, CFQ_SLICE_SCALE);
 946
 947        WARN_ON(prio >= IOPRIO_BE_NR);
 948
 949        return base_slice + (slice * (4 - prio));
 950}
 951
 952static inline u64
 953cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 954{
 955        return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
 956}
 957
 958/**
 959 * cfqg_scale_charge - scale disk time charge according to cfqg weight
 960 * @charge: disk time being charged
 961 * @vfraction: vfraction of the cfqg, fixed point w/ CFQ_SERVICE_SHIFT
 962 *
 963 * Scale @charge according to @vfraction, which is in range (0, 1].  The
 964 * scaling is inversely proportional.
 965 *
 966 * scaled = charge / vfraction
 967 *
 968 * The result is also in fixed point w/ CFQ_SERVICE_SHIFT.
 969 */
 970static inline u64 cfqg_scale_charge(u64 charge,
 971                                    unsigned int vfraction)
 972{
 973        u64 c = charge << CFQ_SERVICE_SHIFT;    /* make it fixed point */
 974
 975        /* charge / vfraction */
 976        c <<= CFQ_SERVICE_SHIFT;
 977        return div_u64(c, vfraction);
 978}
 979
 980static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime)
 981{
 982        s64 delta = (s64)(vdisktime - min_vdisktime);
 983        if (delta > 0)
 984                min_vdisktime = vdisktime;
 985
 986        return min_vdisktime;
 987}
 988
 989static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime)
 990{
 991        s64 delta = (s64)(vdisktime - min_vdisktime);
 992        if (delta < 0)
 993                min_vdisktime = vdisktime;
 994
 995        return min_vdisktime;
 996}
 997
 998static void update_min_vdisktime(struct cfq_rb_root *st)
 999{
1000        struct cfq_group *cfqg;
1001
1002        if (st->left) {
1003                cfqg = rb_entry_cfqg(st->left);
1004                st->min_vdisktime = max_vdisktime(st->min_vdisktime,
1005                                                  cfqg->vdisktime);
1006        }
1007}
1008
1009/*
1010 * get averaged number of queues of RT/BE priority.
1011 * average is updated, with a formula that gives more weight to higher numbers,
1012 * to quickly follows sudden increases and decrease slowly
1013 */
1014
1015static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd,
1016                                        struct cfq_group *cfqg, bool rt)
1017{
1018        unsigned min_q, max_q;
1019        unsigned mult  = cfq_hist_divisor - 1;
1020        unsigned round = cfq_hist_divisor / 2;
1021        unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg);
1022
1023        min_q = min(cfqg->busy_queues_avg[rt], busy);
1024        max_q = max(cfqg->busy_queues_avg[rt], busy);
1025        cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) /
1026                cfq_hist_divisor;
1027        return cfqg->busy_queues_avg[rt];
1028}
1029
1030static inline u64
1031cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg)
1032{
1033        return cfqd->cfq_target_latency * cfqg->vfraction >> CFQ_SERVICE_SHIFT;
1034}
1035
1036static inline u64
1037cfq_scaled_cfqq_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1038{
1039        u64 slice = cfq_prio_to_slice(cfqd, cfqq);
1040        if (cfqd->cfq_latency) {
1041                /*
1042                 * interested queues (we consider only the ones with the same
1043                 * priority class in the cfq group)
1044                 */
1045                unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg,
1046                                                cfq_class_rt(cfqq));
1047                u64 sync_slice = cfqd->cfq_slice[1];
1048                u64 expect_latency = sync_slice * iq;
1049                u64 group_slice = cfq_group_slice(cfqd, cfqq->cfqg);
1050
1051                if (expect_latency > group_slice) {
1052                        u64 base_low_slice = 2 * cfqd->cfq_slice_idle;
1053                        u64 low_slice;
1054
1055                        /* scale low_slice according to IO priority
1056                         * and sync vs async */
1057                        low_slice = div64_u64(base_low_slice*slice, sync_slice);
1058                        low_slice = min(slice, low_slice);
1059                        /* the adapted slice value is scaled to fit all iqs
1060                         * into the target latency */
1061                        slice = div64_u64(slice*group_slice, expect_latency);
1062                        slice = max(slice, low_slice);
1063                }
1064        }
1065        return slice;
1066}
1067
1068static inline void
1069cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1070{
1071        u64 slice = cfq_scaled_cfqq_slice(cfqd, cfqq);
1072        u64 now = ktime_get_ns();
1073
1074        cfqq->slice_start = now;
1075        cfqq->slice_end = now + slice;
1076        cfqq->allocated_slice = slice;
1077        cfq_log_cfqq(cfqd, cfqq, "set_slice=%llu", cfqq->slice_end - now);
1078}
1079
1080/*
1081 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
1082 * isn't valid until the first request from the dispatch is activated
1083 * and the slice time set.
1084 */
1085static inline bool cfq_slice_used(struct cfq_queue *cfqq)
1086{
1087        if (cfq_cfqq_slice_new(cfqq))
1088                return false;
1089        if (ktime_get_ns() < cfqq->slice_end)
1090                return false;
1091
1092        return true;
1093}
1094
1095/*
1096 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
1097 * We choose the request that is closest to the head right now. Distance
1098 * behind the head is penalized and only allowed to a certain extent.
1099 */
1100static struct request *
1101cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last)
1102{
1103        sector_t s1, s2, d1 = 0, d2 = 0;
1104        unsigned long back_max;
1105#define CFQ_RQ1_WRAP    0x01 /* request 1 wraps */
1106#define CFQ_RQ2_WRAP    0x02 /* request 2 wraps */
1107        unsigned wrap = 0; /* bit mask: requests behind the disk head? */
1108
1109        if (rq1 == NULL || rq1 == rq2)
1110                return rq2;
1111        if (rq2 == NULL)
1112                return rq1;
1113
1114        if (rq_is_sync(rq1) != rq_is_sync(rq2))
1115                return rq_is_sync(rq1) ? rq1 : rq2;
1116
1117        if ((rq1->cmd_flags ^ rq2->cmd_flags) & REQ_PRIO)
1118                return rq1->cmd_flags & REQ_PRIO ? rq1 : rq2;
1119
1120        s1 = blk_rq_pos(rq1);
1121        s2 = blk_rq_pos(rq2);
1122
1123        /*
1124         * by definition, 1KiB is 2 sectors
1125         */
1126        back_max = cfqd->cfq_back_max * 2;
1127
1128        /*
1129         * Strict one way elevator _except_ in the case where we allow
1130         * short backward seeks which are biased as twice the cost of a
1131         * similar forward seek.
1132         */
1133        if (s1 >= last)
1134                d1 = s1 - last;
1135        else if (s1 + back_max >= last)
1136                d1 = (last - s1) * cfqd->cfq_back_penalty;
1137        else
1138                wrap |= CFQ_RQ1_WRAP;
1139
1140        if (s2 >= last)
1141                d2 = s2 - last;
1142        else if (s2 + back_max >= last)
1143                d2 = (last - s2) * cfqd->cfq_back_penalty;
1144        else
1145                wrap |= CFQ_RQ2_WRAP;
1146
1147        /* Found required data */
1148
1149        /*
1150         * By doing switch() on the bit mask "wrap" we avoid having to
1151         * check two variables for all permutations: --> faster!
1152         */
1153        switch (wrap) {
1154        case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
1155                if (d1 < d2)
1156                        return rq1;
1157                else if (d2 < d1)
1158                        return rq2;
1159                else {
1160                        if (s1 >= s2)
1161                                return rq1;
1162                        else
1163                                return rq2;
1164                }
1165
1166        case CFQ_RQ2_WRAP:
1167                return rq1;
1168        case CFQ_RQ1_WRAP:
1169                return rq2;
1170        case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */
1171        default:
1172                /*
1173                 * Since both rqs are wrapped,
1174                 * start with the one that's further behind head
1175                 * (--> only *one* back seek required),
1176                 * since back seek takes more time than forward.
1177                 */
1178                if (s1 <= s2)
1179                        return rq1;
1180                else
1181                        return rq2;
1182        }
1183}
1184
1185/*
1186 * The below is leftmost cache rbtree addon
1187 */
1188static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
1189{
1190        /* Service tree is empty */
1191        if (!root->count)
1192                return NULL;
1193
1194        if (!root->left)
1195                root->left = rb_first(&root->rb);
1196
1197        if (root->left)
1198                return rb_entry(root->left, struct cfq_queue, rb_node);
1199
1200        return NULL;
1201}
1202
1203static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root)
1204{
1205        if (!root->left)
1206                root->left = rb_first(&root->rb);
1207
1208        if (root->left)
1209                return rb_entry_cfqg(root->left);
1210
1211        return NULL;
1212}
1213
1214static void rb_erase_init(struct rb_node *n, struct rb_root *root)
1215{
1216        rb_erase(n, root);
1217        RB_CLEAR_NODE(n);
1218}
1219
1220static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)
1221{
1222        if (root->left == n)
1223                root->left = NULL;
1224        rb_erase_init(n, &root->rb);
1225        --root->count;
1226}
1227
1228/*
1229 * would be nice to take fifo expire time into account as well
1230 */
1231static struct request *
1232cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1233                  struct request *last)
1234{
1235        struct rb_node *rbnext = rb_next(&last->rb_node);
1236        struct rb_node *rbprev = rb_prev(&last->rb_node);
1237        struct request *next = NULL, *prev = NULL;
1238
1239        BUG_ON(RB_EMPTY_NODE(&last->rb_node));
1240
1241        if (rbprev)
1242                prev = rb_entry_rq(rbprev);
1243
1244        if (rbnext)
1245                next = rb_entry_rq(rbnext);
1246        else {
1247                rbnext = rb_first(&cfqq->sort_list);
1248                if (rbnext && rbnext != &last->rb_node)
1249                        next = rb_entry_rq(rbnext);
1250        }
1251
1252        return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last));
1253}
1254
1255static u64 cfq_slice_offset(struct cfq_data *cfqd,
1256                            struct cfq_queue *cfqq)
1257{
1258        /*
1259         * just an approximation, should be ok.
1260         */
1261        return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) -
1262                       cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio));
1263}
1264
1265static inline s64
1266cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg)
1267{
1268        return cfqg->vdisktime - st->min_vdisktime;
1269}
1270
1271static void
1272__cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
1273{
1274        struct rb_node **node = &st->rb.rb_node;
1275        struct rb_node *parent = NULL;
1276        struct cfq_group *__cfqg;
1277        s64 key = cfqg_key(st, cfqg);
1278        int left = 1;
1279
1280        while (*node != NULL) {
1281                parent = *node;
1282                __cfqg = rb_entry_cfqg(parent);
1283
1284                if (key < cfqg_key(st, __cfqg))
1285                        node = &parent->rb_left;
1286                else {
1287                        node = &parent->rb_right;
1288                        left = 0;
1289                }
1290        }
1291
1292        if (left)
1293                st->left = &cfqg->rb_node;
1294
1295        rb_link_node(&cfqg->rb_node, parent, node);
1296        rb_insert_color(&cfqg->rb_node, &st->rb);
1297}
1298
1299/*
1300 * This has to be called only on activation of cfqg
1301 */
1302static void
1303cfq_update_group_weight(struct cfq_group *cfqg)
1304{
1305        if (cfqg->new_weight) {
1306                cfqg->weight = cfqg->new_weight;
1307                cfqg->new_weight = 0;
1308        }
1309}
1310
1311static void
1312cfq_update_group_leaf_weight(struct cfq_group *cfqg)
1313{
1314        BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
1315
1316        if (cfqg->new_leaf_weight) {
1317                cfqg->leaf_weight = cfqg->new_leaf_weight;
1318                cfqg->new_leaf_weight = 0;
1319        }
1320}
1321
1322static void
1323cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
1324{
1325        unsigned int vfr = 1 << CFQ_SERVICE_SHIFT;      /* start with 1 */
1326        struct cfq_group *pos = cfqg;
1327        struct cfq_group *parent;
1328        bool propagate;
1329
1330        /* add to the service tree */
1331        BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
1332
1333        /*
1334         * Update leaf_weight.  We cannot update weight at this point
1335         * because cfqg might already have been activated and is
1336         * contributing its current weight to the parent's child_weight.
1337         */
1338        cfq_update_group_leaf_weight(cfqg);
1339        __cfq_group_service_tree_add(st, cfqg);
1340
1341        /*
1342         * Activate @cfqg and calculate the portion of vfraction @cfqg is
1343         * entitled to.  vfraction is calculated by walking the tree
1344         * towards the root calculating the fraction it has at each level.
1345         * The compounded ratio is how much vfraction @cfqg owns.
1346         *
1347         * Start with the proportion tasks in this cfqg has against active
1348         * children cfqgs - its leaf_weight against children_weight.
1349         */
1350        propagate = !pos->nr_active++;
1351        pos->children_weight += pos->leaf_weight;
1352        vfr = vfr * pos->leaf_weight / pos->children_weight;
1353
1354        /*
1355         * Compound ->weight walking up the tree.  Both activation and
1356         * vfraction calculation are done in the same loop.  Propagation
1357         * stops once an already activated node is met.  vfraction
1358         * calculation should always continue to the root.
1359         */
1360        while ((parent = cfqg_parent(pos))) {
1361                if (propagate) {
1362                        cfq_update_group_weight(pos);
1363                        propagate = !parent->nr_active++;
1364                        parent->children_weight += pos->weight;
1365                }
1366                vfr = vfr * pos->weight / parent->children_weight;
1367                pos = parent;
1368        }
1369
1370        cfqg->vfraction = max_t(unsigned, vfr, 1);
1371}
1372
1373static void
1374cfq_group_notify_queue_add(struct cfq_data *cfqd, struct cfq_group *cfqg)
1375{
1376        struct cfq_rb_root *st = &cfqd->grp_service_tree;
1377        struct cfq_group *__cfqg;
1378        struct rb_node *n;
1379
1380        cfqg->nr_cfqq++;
1381        if (!RB_EMPTY_NODE(&cfqg->rb_node))
1382                return;
1383
1384        /*
1385         * Currently put the group at the end. Later implement something
1386         * so that groups get lesser vtime based on their weights, so that
1387         * if group does not loose all if it was not continuously backlogged.
1388         */
1389        n = rb_last(&st->rb);
1390        if (n) {
1391                __cfqg = rb_entry_cfqg(n);
1392                cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY;
1393        } else
1394                cfqg->vdisktime = st->min_vdisktime;
1395        cfq_group_service_tree_add(st, cfqg);
1396}
1397
1398static void
1399cfq_group_service_tree_del(struct cfq_rb_root *st, struct cfq_group *cfqg)
1400{
1401        struct cfq_group *pos = cfqg;
1402        bool propagate;
1403
1404        /*
1405         * Undo activation from cfq_group_service_tree_add().  Deactivate
1406         * @cfqg and propagate deactivation upwards.
1407         */
1408        propagate = !--pos->nr_active;
1409        pos->children_weight -= pos->leaf_weight;
1410
1411        while (propagate) {
1412                struct cfq_group *parent = cfqg_parent(pos);
1413
1414                /* @pos has 0 nr_active at this point */
1415                WARN_ON_ONCE(pos->children_weight);
1416                pos->vfraction = 0;
1417
1418                if (!parent)
1419                        break;
1420
1421                propagate = !--parent->nr_active;
1422                parent->children_weight -= pos->weight;
1423                pos = parent;
1424        }
1425
1426        /* remove from the service tree */
1427        if (!RB_EMPTY_NODE(&cfqg->rb_node))
1428                cfq_rb_erase(&cfqg->rb_node, st);
1429}
1430
1431static void
1432cfq_group_notify_queue_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
1433{
1434        struct cfq_rb_root *st = &cfqd->grp_service_tree;
1435
1436        BUG_ON(cfqg->nr_cfqq < 1);
1437        cfqg->nr_cfqq--;
1438
1439        /* If there are other cfq queues under this group, don't delete it */
1440        if (cfqg->nr_cfqq)
1441                return;
1442
1443        cfq_log_cfqg(cfqd, cfqg, "del_from_rr group");
1444        cfq_group_service_tree_del(st, cfqg);
1445        cfqg->saved_wl_slice = 0;
1446        cfqg_stats_update_dequeue(cfqg);
1447}
1448
1449static inline u64 cfq_cfqq_slice_usage(struct cfq_queue *cfqq,
1450                                       u64 *unaccounted_time)
1451{
1452        u64 slice_used;
1453        u64 now = ktime_get_ns();
1454
1455        /*
1456         * Queue got expired before even a single request completed or
1457         * got expired immediately after first request completion.
1458         */
1459        if (!cfqq->slice_start || cfqq->slice_start == now) {
1460                /*
1461                 * Also charge the seek time incurred to the group, otherwise
1462                 * if there are mutiple queues in the group, each can dispatch
1463                 * a single request on seeky media and cause lots of seek time
1464                 * and group will never know it.
1465                 */
1466                slice_used = max_t(u64, (now - cfqq->dispatch_start),
1467                                        jiffies_to_nsecs(1));
1468        } else {
1469                slice_used = now - cfqq->slice_start;
1470                if (slice_used > cfqq->allocated_slice) {
1471                        *unaccounted_time = slice_used - cfqq->allocated_slice;
1472                        slice_used = cfqq->allocated_slice;
1473                }
1474                if (cfqq->slice_start > cfqq->dispatch_start)
1475                        *unaccounted_time += cfqq->slice_start -
1476                                        cfqq->dispatch_start;
1477        }
1478
1479        return slice_used;
1480}
1481
1482static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
1483                                struct cfq_queue *cfqq)
1484{
1485        struct cfq_rb_root *st = &cfqd->grp_service_tree;
1486        u64 used_sl, charge, unaccounted_sl = 0;
1487        int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg)
1488                        - cfqg->service_tree_idle.count;
1489        unsigned int vfr;
1490        u64 now = ktime_get_ns();
1491
1492        BUG_ON(nr_sync < 0);
1493        used_sl = charge = cfq_cfqq_slice_usage(cfqq, &unaccounted_sl);
1494
1495        if (iops_mode(cfqd))
1496                charge = cfqq->slice_dispatch;
1497        else if (!cfq_cfqq_sync(cfqq) && !nr_sync)
1498                charge = cfqq->allocated_slice;
1499
1500        /*
1501         * Can't update vdisktime while on service tree and cfqg->vfraction
1502         * is valid only while on it.  Cache vfr, leave the service tree,
1503         * update vdisktime and go back on.  The re-addition to the tree
1504         * will also update the weights as necessary.
1505         */
1506        vfr = cfqg->vfraction;
1507        cfq_group_service_tree_del(st, cfqg);
1508        cfqg->vdisktime += cfqg_scale_charge(charge, vfr);
1509        cfq_group_service_tree_add(st, cfqg);
1510
1511        /* This group is being expired. Save the context */
1512        if (cfqd->workload_expires > now) {
1513                cfqg->saved_wl_slice = cfqd->workload_expires - now;
1514                cfqg->saved_wl_type = cfqd->serving_wl_type;
1515                cfqg->saved_wl_class = cfqd->serving_wl_class;
1516        } else
1517                cfqg->saved_wl_slice = 0;
1518
1519        cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime,
1520                                        st->min_vdisktime);
1521        cfq_log_cfqq(cfqq->cfqd, cfqq,
1522                     "sl_used=%llu disp=%llu charge=%llu iops=%u sect=%lu",
1523                     used_sl, cfqq->slice_dispatch, charge,
1524                     iops_mode(cfqd), cfqq->nr_sectors);
1525        cfqg_stats_update_timeslice_used(cfqg, used_sl, unaccounted_sl);
1526        cfqg_stats_set_start_empty_time(cfqg);
1527}
1528
1529/**
1530 * cfq_init_cfqg_base - initialize base part of a cfq_group
1531 * @cfqg: cfq_group to initialize
1532 *
1533 * Initialize the base part which is used whether %CONFIG_CFQ_GROUP_IOSCHED
1534 * is enabled or not.
1535 */
1536static void cfq_init_cfqg_base(struct cfq_group *cfqg)
1537{
1538        struct cfq_rb_root *st;
1539        int i, j;
1540
1541        for_each_cfqg_st(cfqg, i, j, st)
1542                *st = CFQ_RB_ROOT;
1543        RB_CLEAR_NODE(&cfqg->rb_node);
1544
1545        cfqg->ttime.last_end_request = ktime_get_ns();
1546}
1547
1548#ifdef CONFIG_CFQ_GROUP_IOSCHED
1549static int __cfq_set_weight(struct cgroup_subsys_state *css, u64 val,
1550                            bool on_dfl, bool reset_dev, bool is_leaf_weight);
1551
1552static void cfqg_stats_exit(struct cfqg_stats *stats)
1553{
1554        blkg_rwstat_exit(&stats->merged);
1555        blkg_rwstat_exit(&stats->service_time);
1556        blkg_rwstat_exit(&stats->wait_time);
1557        blkg_rwstat_exit(&stats->queued);
1558        blkg_stat_exit(&stats->time);
1559#ifdef CONFIG_DEBUG_BLK_CGROUP
1560        blkg_stat_exit(&stats->unaccounted_time);
1561        blkg_stat_exit(&stats->avg_queue_size_sum);
1562        blkg_stat_exit(&stats->avg_queue_size_samples);
1563        blkg_stat_exit(&stats->dequeue);
1564        blkg_stat_exit(&stats->group_wait_time);
1565        blkg_stat_exit(&stats->idle_time);
1566        blkg_stat_exit(&stats->empty_time);
1567#endif
1568}
1569
1570static int cfqg_stats_init(struct cfqg_stats *stats, gfp_t gfp)
1571{
1572        if (blkg_rwstat_init(&stats->merged, gfp) ||
1573            blkg_rwstat_init(&stats->service_time, gfp) ||
1574            blkg_rwstat_init(&stats->wait_time, gfp) ||
1575            blkg_rwstat_init(&stats->queued, gfp) ||
1576            blkg_stat_init(&stats->time, gfp))
1577                goto err;
1578
1579#ifdef CONFIG_DEBUG_BLK_CGROUP
1580        if (blkg_stat_init(&stats->unaccounted_time, gfp) ||
1581            blkg_stat_init(&stats->avg_queue_size_sum, gfp) ||
1582            blkg_stat_init(&stats->avg_queue_size_samples, gfp) ||
1583            blkg_stat_init(&stats->dequeue, gfp) ||
1584            blkg_stat_init(&stats->group_wait_time, gfp) ||
1585            blkg_stat_init(&stats->idle_time, gfp) ||
1586            blkg_stat_init(&stats->empty_time, gfp))
1587                goto err;
1588#endif
1589        return 0;
1590err:
1591        cfqg_stats_exit(stats);
1592        return -ENOMEM;
1593}
1594
1595static struct blkcg_policy_data *cfq_cpd_alloc(gfp_t gfp)
1596{
1597        struct cfq_group_data *cgd;
1598
1599        cgd = kzalloc(sizeof(*cgd), GFP_KERNEL);
1600        if (!cgd)
1601                return NULL;
1602        return &cgd->cpd;
1603}
1604
1605static void cfq_cpd_init(struct blkcg_policy_data *cpd)
1606{
1607        struct cfq_group_data *cgd = cpd_to_cfqgd(cpd);
1608        unsigned int weight = cgroup_subsys_on_dfl(io_cgrp_subsys) ?
1609                              CGROUP_WEIGHT_DFL : CFQ_WEIGHT_LEGACY_DFL;
1610
1611        if (cpd_to_blkcg(cpd) == &blkcg_root)
1612                weight *= 2;
1613
1614        cgd->weight = weight;
1615        cgd->leaf_weight = weight;
1616}
1617
1618static void cfq_cpd_free(struct blkcg_policy_data *cpd)
1619{
1620        kfree(cpd_to_cfqgd(cpd));
1621}
1622
1623static void cfq_cpd_bind(struct blkcg_policy_data *cpd)
1624{
1625        struct blkcg *blkcg = cpd_to_blkcg(cpd);
1626        bool on_dfl = cgroup_subsys_on_dfl(io_cgrp_subsys);
1627        unsigned int weight = on_dfl ? CGROUP_WEIGHT_DFL : CFQ_WEIGHT_LEGACY_DFL;
1628
1629        if (blkcg == &blkcg_root)
1630                weight *= 2;
1631
1632        WARN_ON_ONCE(__cfq_set_weight(&blkcg->css, weight, on_dfl, true, false));
1633        WARN_ON_ONCE(__cfq_set_weight(&blkcg->css, weight, on_dfl, true, true));
1634}
1635
1636static struct blkg_policy_data *cfq_pd_alloc(gfp_t gfp, int node)
1637{
1638        struct cfq_group *cfqg;
1639
1640        cfqg = kzalloc_node(sizeof(*cfqg), gfp, node);
1641        if (!cfqg)
1642                return NULL;
1643
1644        cfq_init_cfqg_base(cfqg);
1645        if (cfqg_stats_init(&cfqg->stats, gfp)) {
1646                kfree(cfqg);
1647                return NULL;
1648        }
1649
1650        return &cfqg->pd;
1651}
1652
1653static void cfq_pd_init(struct blkg_policy_data *pd)
1654{
1655        struct cfq_group *cfqg = pd_to_cfqg(pd);
1656        struct cfq_group_data *cgd = blkcg_to_cfqgd(pd->blkg->blkcg);
1657
1658        cfqg->weight = cgd->weight;
1659        cfqg->leaf_weight = cgd->leaf_weight;
1660}
1661
1662static void cfq_pd_offline(struct blkg_policy_data *pd)
1663{
1664        struct cfq_group *cfqg = pd_to_cfqg(pd);
1665        int i;
1666
1667        for (i = 0; i < IOPRIO_BE_NR; i++) {
1668                if (cfqg->async_cfqq[0][i])
1669                        cfq_put_queue(cfqg->async_cfqq[0][i]);
1670                if (cfqg->async_cfqq[1][i])
1671                        cfq_put_queue(cfqg->async_cfqq[1][i]);
1672        }
1673
1674        if (cfqg->async_idle_cfqq)
1675                cfq_put_queue(cfqg->async_idle_cfqq);
1676
1677        /*
1678         * @blkg is going offline and will be ignored by
1679         * blkg_[rw]stat_recursive_sum().  Transfer stats to the parent so
1680         * that they don't get lost.  If IOs complete after this point, the
1681         * stats for them will be lost.  Oh well...
1682         */
1683        cfqg_stats_xfer_dead(cfqg);
1684}
1685
1686static void cfq_pd_free(struct blkg_policy_data *pd)
1687{
1688        struct cfq_group *cfqg = pd_to_cfqg(pd);
1689
1690        cfqg_stats_exit(&cfqg->stats);
1691        return kfree(cfqg);
1692}
1693
1694static void cfq_pd_reset_stats(struct blkg_policy_data *pd)
1695{
1696        struct cfq_group *cfqg = pd_to_cfqg(pd);
1697
1698        cfqg_stats_reset(&cfqg->stats);
1699}
1700
1701static struct cfq_group *cfq_lookup_cfqg(struct cfq_data *cfqd,
1702                                         struct blkcg *blkcg)
1703{
1704        struct blkcg_gq *blkg;
1705
1706        blkg = blkg_lookup(blkcg, cfqd->queue);
1707        if (likely(blkg))
1708                return blkg_to_cfqg(blkg);
1709        return NULL;
1710}
1711
1712static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg)
1713{
1714        cfqq->cfqg = cfqg;
1715        /* cfqq reference on cfqg */
1716        cfqg_get(cfqg);
1717}
1718
1719static u64 cfqg_prfill_weight_device(struct seq_file *sf,
1720                                     struct blkg_policy_data *pd, int off)
1721{
1722        struct cfq_group *cfqg = pd_to_cfqg(pd);
1723
1724        if (!cfqg->dev_weight)
1725                return 0;
1726        return __blkg_prfill_u64(sf, pd, cfqg->dev_weight);
1727}
1728
1729static int cfqg_print_weight_device(struct seq_file *sf, void *v)
1730{
1731        blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1732                          cfqg_prfill_weight_device, &blkcg_policy_cfq,
1733                          0, false);
1734        return 0;
1735}
1736
1737static u64 cfqg_prfill_leaf_weight_device(struct seq_file *sf,
1738                                          struct blkg_policy_data *pd, int off)
1739{
1740        struct cfq_group *cfqg = pd_to_cfqg(pd);
1741
1742        if (!cfqg->dev_leaf_weight)
1743                return 0;
1744        return __blkg_prfill_u64(sf, pd, cfqg->dev_leaf_weight);
1745}
1746
1747static int cfqg_print_leaf_weight_device(struct seq_file *sf, void *v)
1748{
1749        blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1750                          cfqg_prfill_leaf_weight_device, &blkcg_policy_cfq,
1751                          0, false);
1752        return 0;
1753}
1754
1755static int cfq_print_weight(struct seq_file *sf, void *v)
1756{
1757        struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
1758        struct cfq_group_data *cgd = blkcg_to_cfqgd(blkcg);
1759        unsigned int val = 0;
1760
1761        if (cgd)
1762                val = cgd->weight;
1763
1764        seq_printf(sf, "%u\n", val);
1765        return 0;
1766}
1767
1768static int cfq_print_leaf_weight(struct seq_file *sf, void *v)
1769{
1770        struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
1771        struct cfq_group_data *cgd = blkcg_to_cfqgd(blkcg);
1772        unsigned int val = 0;
1773
1774        if (cgd)
1775                val = cgd->leaf_weight;
1776
1777        seq_printf(sf, "%u\n", val);
1778        return 0;
1779}
1780
1781static ssize_t __cfqg_set_weight_device(struct kernfs_open_file *of,
1782                                        char *buf, size_t nbytes, loff_t off,
1783                                        bool on_dfl, bool is_leaf_weight)
1784{
1785        unsigned int min = on_dfl ? CGROUP_WEIGHT_MIN : CFQ_WEIGHT_LEGACY_MIN;
1786        unsigned int max = on_dfl ? CGROUP_WEIGHT_MAX : CFQ_WEIGHT_LEGACY_MAX;
1787        struct blkcg *blkcg = css_to_blkcg(of_css(of));
1788        struct blkg_conf_ctx ctx;
1789        struct cfq_group *cfqg;
1790        struct cfq_group_data *cfqgd;
1791        int ret;
1792        u64 v;
1793
1794        ret = blkg_conf_prep(blkcg, &blkcg_policy_cfq, buf, &ctx);
1795        if (ret)
1796                return ret;
1797
1798        if (sscanf(ctx.body, "%llu", &v) == 1) {
1799                /* require "default" on dfl */
1800                ret = -ERANGE;
1801                if (!v && on_dfl)
1802                        goto out_finish;
1803        } else if (!strcmp(strim(ctx.body), "default")) {
1804                v = 0;
1805        } else {
1806                ret = -EINVAL;
1807                goto out_finish;
1808        }
1809
1810        cfqg = blkg_to_cfqg(ctx.blkg);
1811        cfqgd = blkcg_to_cfqgd(blkcg);
1812
1813        ret = -ERANGE;
1814        if (!v || (v >= min && v <= max)) {
1815                if (!is_leaf_weight) {
1816                        cfqg->dev_weight = v;
1817                        cfqg->new_weight = v ?: cfqgd->weight;
1818                } else {
1819                        cfqg->dev_leaf_weight = v;
1820                        cfqg->new_leaf_weight = v ?: cfqgd->leaf_weight;
1821                }
1822                ret = 0;
1823        }
1824out_finish:
1825        blkg_conf_finish(&ctx);
1826        return ret ?: nbytes;
1827}
1828
1829static ssize_t cfqg_set_weight_device(struct kernfs_open_file *of,
1830                                      char *buf, size_t nbytes, loff_t off)
1831{
1832        return __cfqg_set_weight_device(of, buf, nbytes, off, false, false);
1833}
1834
1835static ssize_t cfqg_set_leaf_weight_device(struct kernfs_open_file *of,
1836                                           char *buf, size_t nbytes, loff_t off)
1837{
1838        return __cfqg_set_weight_device(of, buf, nbytes, off, false, true);
1839}
1840
1841static int __cfq_set_weight(struct cgroup_subsys_state *css, u64 val,
1842                            bool on_dfl, bool reset_dev, bool is_leaf_weight)
1843{
1844        unsigned int min = on_dfl ? CGROUP_WEIGHT_MIN : CFQ_WEIGHT_LEGACY_MIN;
1845        unsigned int max = on_dfl ? CGROUP_WEIGHT_MAX : CFQ_WEIGHT_LEGACY_MAX;
1846        struct blkcg *blkcg = css_to_blkcg(css);
1847        struct blkcg_gq *blkg;
1848        struct cfq_group_data *cfqgd;
1849        int ret = 0;
1850
1851        if (val < min || val > max)
1852                return -ERANGE;
1853
1854        spin_lock_irq(&blkcg->lock);
1855        cfqgd = blkcg_to_cfqgd(blkcg);
1856        if (!cfqgd) {
1857                ret = -EINVAL;
1858                goto out;
1859        }
1860
1861        if (!is_leaf_weight)
1862                cfqgd->weight = val;
1863        else
1864                cfqgd->leaf_weight = val;
1865
1866        hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) {
1867                struct cfq_group *cfqg = blkg_to_cfqg(blkg);
1868
1869                if (!cfqg)
1870                        continue;
1871
1872                if (!is_leaf_weight) {
1873                        if (reset_dev)
1874                                cfqg->dev_weight = 0;
1875                        if (!cfqg->dev_weight)
1876                                cfqg->new_weight = cfqgd->weight;
1877                } else {
1878                        if (reset_dev)
1879                                cfqg->dev_leaf_weight = 0;
1880                        if (!cfqg->dev_leaf_weight)
1881                                cfqg->new_leaf_weight = cfqgd->leaf_weight;
1882                }
1883        }
1884
1885out:
1886        spin_unlock_irq(&blkcg->lock);
1887        return ret;
1888}
1889
1890static int cfq_set_weight(struct cgroup_subsys_state *css, struct cftype *cft,
1891                          u64 val)
1892{
1893        return __cfq_set_weight(css, val, false, false, false);
1894}
1895
1896static int cfq_set_leaf_weight(struct cgroup_subsys_state *css,
1897                               struct cftype *cft, u64 val)
1898{
1899        return __cfq_set_weight(css, val, false, false, true);
1900}
1901
1902static int cfqg_print_stat(struct seq_file *sf, void *v)
1903{
1904        blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_stat,
1905                          &blkcg_policy_cfq, seq_cft(sf)->private, false);
1906        return 0;
1907}
1908
1909static int cfqg_print_rwstat(struct seq_file *sf, void *v)
1910{
1911        blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_rwstat,
1912                          &blkcg_policy_cfq, seq_cft(sf)->private, true);
1913        return 0;
1914}
1915
1916static u64 cfqg_prfill_stat_recursive(struct seq_file *sf,
1917                                      struct blkg_policy_data *pd, int off)
1918{
1919        u64 sum = blkg_stat_recursive_sum(pd_to_blkg(pd),
1920                                          &blkcg_policy_cfq, off);
1921        return __blkg_prfill_u64(sf, pd, sum);
1922}
1923
1924static u64 cfqg_prfill_rwstat_recursive(struct seq_file *sf,
1925                                        struct blkg_policy_data *pd, int off)
1926{
1927        struct blkg_rwstat sum = blkg_rwstat_recursive_sum(pd_to_blkg(pd),
1928                                                        &blkcg_policy_cfq, off);
1929        return __blkg_prfill_rwstat(sf, pd, &sum);
1930}
1931
1932static int cfqg_print_stat_recursive(struct seq_file *sf, void *v)
1933{
1934        blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1935                          cfqg_prfill_stat_recursive, &blkcg_policy_cfq,
1936                          seq_cft(sf)->private, false);
1937        return 0;
1938}
1939
1940static int cfqg_print_rwstat_recursive(struct seq_file *sf, void *v)
1941{
1942        blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1943                          cfqg_prfill_rwstat_recursive, &blkcg_policy_cfq,
1944                          seq_cft(sf)->private, true);
1945        return 0;
1946}
1947
1948static u64 cfqg_prfill_sectors(struct seq_file *sf, struct blkg_policy_data *pd,
1949                               int off)
1950{
1951        u64 sum = blkg_rwstat_total(&pd->blkg->stat_bytes);
1952
1953        return __blkg_prfill_u64(sf, pd, sum >> 9);
1954}
1955
1956static int cfqg_print_stat_sectors(struct seq_file *sf, void *v)
1957{
1958        blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1959                          cfqg_prfill_sectors, &blkcg_policy_cfq, 0, false);
1960        return 0;
1961}
1962
1963static u64 cfqg_prfill_sectors_recursive(struct seq_file *sf,
1964                                         struct blkg_policy_data *pd, int off)
1965{
1966        struct blkg_rwstat tmp = blkg_rwstat_recursive_sum(pd->blkg, NULL,
1967                                        offsetof(struct blkcg_gq, stat_bytes));
1968        u64 sum = atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_READ]) +
1969                atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_WRITE]);
1970
1971        return __blkg_prfill_u64(sf, pd, sum >> 9);
1972}
1973
1974static int cfqg_print_stat_sectors_recursive(struct seq_file *sf, void *v)
1975{
1976        blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1977                          cfqg_prfill_sectors_recursive, &blkcg_policy_cfq, 0,
1978                          false);
1979        return 0;
1980}
1981
1982#ifdef CONFIG_DEBUG_BLK_CGROUP
1983static u64 cfqg_prfill_avg_queue_size(struct seq_file *sf,
1984                                      struct blkg_policy_data *pd, int off)
1985{
1986        struct cfq_group *cfqg = pd_to_cfqg(pd);
1987        u64 samples = blkg_stat_read(&cfqg->stats.avg_queue_size_samples);
1988        u64 v = 0;
1989
1990        if (samples) {
1991                v = blkg_stat_read(&cfqg->stats.avg_queue_size_sum);
1992                v = div64_u64(v, samples);
1993        }
1994        __blkg_prfill_u64(sf, pd, v);
1995        return 0;
1996}
1997
1998/* print avg_queue_size */
1999static int cfqg_print_avg_queue_size(struct seq_file *sf, void *v)
2000{
2001        blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
2002                          cfqg_prfill_avg_queue_size, &blkcg_policy_cfq,
2003                          0, false);
2004        return 0;
2005}
2006#endif  /* CONFIG_DEBUG_BLK_CGROUP */
2007
2008static struct cftype cfq_blkcg_legacy_files[] = {
2009        /* on root, weight is mapped to leaf_weight */
2010        {
2011                .name = "weight_device",
2012                .flags = CFTYPE_ONLY_ON_ROOT,
2013                .seq_show = cfqg_print_leaf_weight_device,
2014                .write = cfqg_set_leaf_weight_device,
2015        },
2016        {
2017                .name = "weight",
2018                .flags = CFTYPE_ONLY_ON_ROOT,
2019                .seq_show = cfq_print_leaf_weight,
2020                .write_u64 = cfq_set_leaf_weight,
2021        },
2022
2023        /* no such mapping necessary for !roots */
2024        {
2025                .name = "weight_device",
2026                .flags = CFTYPE_NOT_ON_ROOT,
2027                .seq_show = cfqg_print_weight_device,
2028                .write = cfqg_set_weight_device,
2029        },
2030        {
2031                .name = "weight",
2032                .flags = CFTYPE_NOT_ON_ROOT,
2033                .seq_show = cfq_print_weight,
2034                .write_u64 = cfq_set_weight,
2035        },
2036
2037        {
2038                .name = "leaf_weight_device",
2039                .seq_show = cfqg_print_leaf_weight_device,
2040                .write = cfqg_set_leaf_weight_device,
2041        },
2042        {
2043                .name = "leaf_weight",
2044                .seq_show = cfq_print_leaf_weight,
2045                .write_u64 = cfq_set_leaf_weight,
2046        },
2047
2048        /* statistics, covers only the tasks in the cfqg */
2049        {
2050                .name = "time",
2051                .private = offsetof(struct cfq_group, stats.time),
2052                .seq_show = cfqg_print_stat,
2053        },
2054        {
2055                .name = "sectors",
2056                .seq_show = cfqg_print_stat_sectors,
2057        },
2058        {
2059                .name = "io_service_bytes",
2060                .private = (unsigned long)&blkcg_policy_cfq,
2061                .seq_show = blkg_print_stat_bytes,
2062        },
2063        {
2064                .name = "io_serviced",
2065                .private = (unsigned long)&blkcg_policy_cfq,
2066                .seq_show = blkg_print_stat_ios,
2067        },
2068        {
2069                .name = "io_service_time",
2070                .private = offsetof(struct cfq_group, stats.service_time),
2071                .seq_show = cfqg_print_rwstat,
2072        },
2073        {
2074                .name = "io_wait_time",
2075                .private = offsetof(struct cfq_group, stats.wait_time),
2076                .seq_show = cfqg_print_rwstat,
2077        },
2078        {
2079                .name = "io_merged",
2080                .private = offsetof(struct cfq_group, stats.merged),
2081                .seq_show = cfqg_print_rwstat,
2082        },
2083        {
2084                .name = "io_queued",
2085                .private = offsetof(struct cfq_group, stats.queued),
2086                .seq_show = cfqg_print_rwstat,
2087        },
2088
2089        /* the same statictics which cover the cfqg and its descendants */
2090        {
2091                .name = "time_recursive",
2092                .private = offsetof(struct cfq_group, stats.time),
2093                .seq_show = cfqg_print_stat_recursive,
2094        },
2095        {
2096                .name = "sectors_recursive",
2097                .seq_show = cfqg_print_stat_sectors_recursive,
2098        },
2099        {
2100                .name = "io_service_bytes_recursive",
2101                .private = (unsigned long)&blkcg_policy_cfq,
2102                .seq_show = blkg_print_stat_bytes_recursive,
2103        },
2104        {
2105                .name = "io_serviced_recursive",
2106                .private = (unsigned long)&blkcg_policy_cfq,
2107                .seq_show = blkg_print_stat_ios_recursive,
2108        },
2109        {
2110                .name = "io_service_time_recursive",
2111                .private = offsetof(struct cfq_group, stats.service_time),
2112                .seq_show = cfqg_print_rwstat_recursive,
2113        },
2114        {
2115                .name = "io_wait_time_recursive",
2116                .private = offsetof(struct cfq_group, stats.wait_time),
2117                .seq_show = cfqg_print_rwstat_recursive,
2118        },
2119        {
2120                .name = "io_merged_recursive",
2121                .private = offsetof(struct cfq_group, stats.merged),
2122                .seq_show = cfqg_print_rwstat_recursive,
2123        },
2124        {
2125                .name = "io_queued_recursive",
2126                .private = offsetof(struct cfq_group, stats.queued),
2127                .seq_show = cfqg_print_rwstat_recursive,
2128        },
2129#ifdef CONFIG_DEBUG_BLK_CGROUP
2130        {
2131                .name = "avg_queue_size",
2132                .seq_show = cfqg_print_avg_queue_size,
2133        },
2134        {
2135                .name = "group_wait_time",
2136                .private = offsetof(struct cfq_group, stats.group_wait_time),
2137                .seq_show = cfqg_print_stat,
2138        },
2139        {
2140                .name = "idle_time",
2141                .private = offsetof(struct cfq_group, stats.idle_time),
2142                .seq_show = cfqg_print_stat,
2143        },
2144        {
2145                .name = "empty_time",
2146                .private = offsetof(struct cfq_group, stats.empty_time),
2147                .seq_show = cfqg_print_stat,
2148        },
2149        {
2150                .name = "dequeue",
2151                .private = offsetof(struct cfq_group, stats.dequeue),
2152                .seq_show = cfqg_print_stat,
2153        },
2154        {
2155                .name = "unaccounted_time",
2156                .private = offsetof(struct cfq_group, stats.unaccounted_time),
2157                .seq_show = cfqg_print_stat,
2158        },
2159#endif  /* CONFIG_DEBUG_BLK_CGROUP */
2160        { }     /* terminate */
2161};
2162
2163static int cfq_print_weight_on_dfl(struct seq_file *sf, void *v)
2164{
2165        struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
2166        struct cfq_group_data *cgd = blkcg_to_cfqgd(blkcg);
2167
2168        seq_printf(sf, "default %u\n", cgd->weight);
2169        blkcg_print_blkgs(sf, blkcg, cfqg_prfill_weight_device,
2170                          &blkcg_policy_cfq, 0, false);
2171        return 0;
2172}
2173
2174static ssize_t cfq_set_weight_on_dfl(struct kernfs_open_file *of,
2175                                     char *buf, size_t nbytes, loff_t off)
2176{
2177        char *endp;
2178        int ret;
2179        u64 v;
2180
2181        buf = strim(buf);
2182
2183        /* "WEIGHT" or "default WEIGHT" sets the default weight */
2184        v = simple_strtoull(buf, &endp, 0);
2185        if (*endp == '\0' || sscanf(buf, "default %llu", &v) == 1) {
2186                ret = __cfq_set_weight(of_css(of), v, true, false, false);
2187                return ret ?: nbytes;
2188        }
2189
2190        /* "MAJ:MIN WEIGHT" */
2191        return __cfqg_set_weight_device(of, buf, nbytes, off, true, false);
2192}
2193
2194static struct cftype cfq_blkcg_files[] = {
2195        {
2196                .name = "weight",
2197                .flags = CFTYPE_NOT_ON_ROOT,
2198                .seq_show = cfq_print_weight_on_dfl,
2199                .write = cfq_set_weight_on_dfl,
2200        },
2201        { }     /* terminate */
2202};
2203
2204#else /* GROUP_IOSCHED */
2205static struct cfq_group *cfq_lookup_cfqg(struct cfq_data *cfqd,
2206                                         struct blkcg *blkcg)
2207{
2208        return cfqd->root_group;
2209}
2210
2211static inline void
2212cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) {
2213        cfqq->cfqg = cfqg;
2214}
2215
2216#endif /* GROUP_IOSCHED */
2217
2218/*
2219 * The cfqd->service_trees holds all pending cfq_queue's that have
2220 * requests waiting to be processed. It is sorted in the order that
2221 * we will service the queues.
2222 */
2223static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2224                                 bool add_front)
2225{
2226        struct rb_node **p, *parent;
2227        struct cfq_queue *__cfqq;
2228        u64 rb_key;
2229        struct cfq_rb_root *st;
2230        int left;
2231        int new_cfqq = 1;
2232        u64 now = ktime_get_ns();
2233
2234        st = st_for(cfqq->cfqg, cfqq_class(cfqq), cfqq_type(cfqq));
2235        if (cfq_class_idle(cfqq)) {
2236                rb_key = CFQ_IDLE_DELAY;
2237                parent = rb_last(&st->rb);
2238                if (parent && parent != &cfqq->rb_node) {
2239                        __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
2240                        rb_key += __cfqq->rb_key;
2241                } else
2242                        rb_key += now;
2243        } else if (!add_front) {
2244                /*
2245                 * Get our rb key offset. Subtract any residual slice
2246                 * value carried from last service. A negative resid
2247                 * count indicates slice overrun, and this should position
2248                 * the next service time further away in the tree.
2249                 */
2250                rb_key = cfq_slice_offset(cfqd, cfqq) + now;
2251                rb_key -= cfqq->slice_resid;
2252                cfqq->slice_resid = 0;
2253        } else {
2254                rb_key = -NSEC_PER_SEC;
2255                __cfqq = cfq_rb_first(st);
2256                rb_key += __cfqq ? __cfqq->rb_key : now;
2257        }
2258
2259        if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
2260                new_cfqq = 0;
2261                /*
2262                 * same position, nothing more to do
2263                 */
2264                if (rb_key == cfqq->rb_key && cfqq->service_tree == st)
2265                        return;
2266
2267                cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
2268                cfqq->service_tree = NULL;
2269        }
2270
2271        left = 1;
2272        parent = NULL;
2273        cfqq->service_tree = st;
2274        p = &st->rb.rb_node;
2275        while (*p) {
2276                parent = *p;
2277                __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
2278
2279                /*
2280                 * sort by key, that represents service time.
2281                 */
2282                if (rb_key < __cfqq->rb_key)
2283                        p = &parent->rb_left;
2284                else {
2285                        p = &parent->rb_right;
2286                        left = 0;
2287                }
2288        }
2289
2290        if (left)
2291                st->left = &cfqq->rb_node;
2292
2293        cfqq->rb_key = rb_key;
2294        rb_link_node(&cfqq->rb_node, parent, p);
2295        rb_insert_color(&cfqq->rb_node, &st->rb);
2296        st->count++;
2297        if (add_front || !new_cfqq)
2298                return;
2299        cfq_group_notify_queue_add(cfqd, cfqq->cfqg);
2300}
2301
2302static struct cfq_queue *
2303cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root,
2304                     sector_t sector, struct rb_node **ret_parent,
2305                     struct rb_node ***rb_link)
2306{
2307        struct rb_node **p, *parent;
2308        struct cfq_queue *cfqq = NULL;
2309
2310        parent = NULL;
2311        p = &root->rb_node;
2312        while (*p) {
2313                struct rb_node **n;
2314
2315                parent = *p;
2316                cfqq = rb_entry(parent, struct cfq_queue, p_node);
2317
2318                /*
2319                 * Sort strictly based on sector.  Smallest to the left,
2320                 * largest to the right.
2321                 */
2322                if (sector > blk_rq_pos(cfqq->next_rq))
2323                        n = &(*p)->rb_right;
2324                else if (sector < blk_rq_pos(cfqq->next_rq))
2325                        n = &(*p)->rb_left;
2326                else
2327                        break;
2328                p = n;
2329                cfqq = NULL;
2330        }
2331
2332        *ret_parent = parent;
2333        if (rb_link)
2334                *rb_link = p;
2335        return cfqq;
2336}
2337
2338static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2339{
2340        struct rb_node **p, *parent;
2341        struct cfq_queue *__cfqq;
2342
2343        if (cfqq->p_root) {
2344                rb_erase(&cfqq->p_node, cfqq->p_root);
2345                cfqq->p_root = NULL;
2346        }
2347
2348        if (cfq_class_idle(cfqq))
2349                return;
2350        if (!cfqq->next_rq)
2351                return;
2352
2353        cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
2354        __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root,
2355                                      blk_rq_pos(cfqq->next_rq), &parent, &p);
2356        if (!__cfqq) {
2357                rb_link_node(&cfqq->p_node, parent, p);
2358                rb_insert_color(&cfqq->p_node, cfqq->p_root);
2359        } else
2360                cfqq->p_root = NULL;
2361}
2362
2363/*
2364 * Update cfqq's position in the service tree.
2365 */
2366static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2367{
2368        /*
2369         * Resorting requires the cfqq to be on the RR list already.
2370         */
2371        if (cfq_cfqq_on_rr(cfqq)) {
2372                cfq_service_tree_add(cfqd, cfqq, 0);
2373                cfq_prio_tree_add(cfqd, cfqq);
2374        }
2375}
2376
2377/*
2378 * add to busy list of queues for service, trying to be fair in ordering
2379 * the pending list according to last request service
2380 */
2381static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2382{
2383        cfq_log_cfqq(cfqd, cfqq, "add_to_rr");
2384        BUG_ON(cfq_cfqq_on_rr(cfqq));
2385        cfq_mark_cfqq_on_rr(cfqq);
2386        cfqd->busy_queues++;
2387        if (cfq_cfqq_sync(cfqq))
2388                cfqd->busy_sync_queues++;
2389
2390        cfq_resort_rr_list(cfqd, cfqq);
2391}
2392
2393/*
2394 * Called when the cfqq no longer has requests pending, remove it from
2395 * the service tree.
2396 */
2397static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2398{
2399        cfq_log_cfqq(cfqd, cfqq, "del_from_rr");
2400        BUG_ON(!cfq_cfqq_on_rr(cfqq));
2401        cfq_clear_cfqq_on_rr(cfqq);
2402
2403        if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
2404                cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
2405                cfqq->service_tree = NULL;
2406        }
2407        if (cfqq->p_root) {
2408                rb_erase(&cfqq->p_node, cfqq->p_root);
2409                cfqq->p_root = NULL;
2410        }
2411
2412        cfq_group_notify_queue_del(cfqd, cfqq->cfqg);
2413        BUG_ON(!cfqd->busy_queues);
2414        cfqd->busy_queues--;
2415        if (cfq_cfqq_sync(cfqq))
2416                cfqd->busy_sync_queues--;
2417}
2418
2419/*
2420 * rb tree support functions
2421 */
2422static void cfq_del_rq_rb(struct request *rq)
2423{
2424        struct cfq_queue *cfqq = RQ_CFQQ(rq);
2425        const int sync = rq_is_sync(rq);
2426
2427        BUG_ON(!cfqq->queued[sync]);
2428        cfqq->queued[sync]--;
2429
2430        elv_rb_del(&cfqq->sort_list, rq);
2431
2432        if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) {
2433                /*
2434                 * Queue will be deleted from service tree when we actually
2435                 * expire it later. Right now just remove it from prio tree
2436                 * as it is empty.
2437                 */
2438                if (cfqq->p_root) {
2439                        rb_erase(&cfqq->p_node, cfqq->p_root);
2440                        cfqq->p_root = NULL;
2441                }
2442        }
2443}
2444
2445static void cfq_add_rq_rb(struct request *rq)
2446{
2447        struct cfq_queue *cfqq = RQ_CFQQ(rq);
2448        struct cfq_data *cfqd = cfqq->cfqd;
2449        struct request *prev;
2450
2451        cfqq->queued[rq_is_sync(rq)]++;
2452
2453        elv_rb_add(&cfqq->sort_list, rq);
2454
2455        if (!cfq_cfqq_on_rr(cfqq))
2456                cfq_add_cfqq_rr(cfqd, cfqq);
2457
2458        /*
2459         * check if this request is a better next-serve candidate
2460         */
2461        prev = cfqq->next_rq;
2462        cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position);
2463
2464        /*
2465         * adjust priority tree position, if ->next_rq changes
2466         */
2467        if (prev != cfqq->next_rq)
2468                cfq_prio_tree_add(cfqd, cfqq);
2469
2470        BUG_ON(!cfqq->next_rq);
2471}
2472
2473static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq)
2474{
2475        elv_rb_del(&cfqq->sort_list, rq);
2476        cfqq->queued[rq_is_sync(rq)]--;
2477        cfqg_stats_update_io_remove(RQ_CFQG(rq), req_op(rq), rq->cmd_flags);
2478        cfq_add_rq_rb(rq);
2479        cfqg_stats_update_io_add(RQ_CFQG(rq), cfqq->cfqd->serving_group,
2480                                 req_op(rq), rq->cmd_flags);
2481}
2482
2483static struct request *
2484cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
2485{
2486        struct task_struct *tsk = current;
2487        struct cfq_io_cq *cic;
2488        struct cfq_queue *cfqq;
2489
2490        cic = cfq_cic_lookup(cfqd, tsk->io_context);
2491        if (!cic)
2492                return NULL;
2493
2494        cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
2495        if (cfqq)
2496                return elv_rb_find(&cfqq->sort_list, bio_end_sector(bio));
2497
2498        return NULL;
2499}
2500
2501static void cfq_activate_request(struct request_queue *q, struct request *rq)
2502{
2503        struct cfq_data *cfqd = q->elevator->elevator_data;
2504
2505        cfqd->rq_in_driver++;
2506        cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
2507                                                cfqd->rq_in_driver);
2508
2509        cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
2510}
2511
2512static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
2513{
2514        struct cfq_data *cfqd = q->elevator->elevator_data;
2515
2516        WARN_ON(!cfqd->rq_in_driver);
2517        cfqd->rq_in_driver--;
2518        cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
2519                                                cfqd->rq_in_driver);
2520}
2521
2522static void cfq_remove_request(struct request *rq)
2523{
2524        struct cfq_queue *cfqq = RQ_CFQQ(rq);
2525
2526        if (cfqq->next_rq == rq)
2527                cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq);
2528
2529        list_del_init(&rq->queuelist);
2530        cfq_del_rq_rb(rq);
2531
2532        cfqq->cfqd->rq_queued--;
2533        cfqg_stats_update_io_remove(RQ_CFQG(rq), req_op(rq), rq->cmd_flags);
2534        if (rq->cmd_flags & REQ_PRIO) {
2535                WARN_ON(!cfqq->prio_pending);
2536                cfqq->prio_pending--;
2537        }
2538}
2539
2540static int cfq_merge(struct request_queue *q, struct request **req,
2541                     struct bio *bio)
2542{
2543        struct cfq_data *cfqd = q->elevator->elevator_data;
2544        struct request *__rq;
2545
2546        __rq = cfq_find_rq_fmerge(cfqd, bio);
2547        if (__rq && elv_bio_merge_ok(__rq, bio)) {
2548                *req = __rq;
2549                return ELEVATOR_FRONT_MERGE;
2550        }
2551
2552        return ELEVATOR_NO_MERGE;
2553}
2554
2555static void cfq_merged_request(struct request_queue *q, struct request *req,
2556                               int type)
2557{
2558        if (type == ELEVATOR_FRONT_MERGE) {
2559                struct cfq_queue *cfqq = RQ_CFQQ(req);
2560
2561                cfq_reposition_rq_rb(cfqq, req);
2562        }
2563}
2564
2565static void cfq_bio_merged(struct request_queue *q, struct request *req,
2566                                struct bio *bio)
2567{
2568        cfqg_stats_update_io_merged(RQ_CFQG(req), bio_op(bio), bio->bi_opf);
2569}
2570
2571static void
2572cfq_merged_requests(struct request_queue *q, struct request *rq,
2573                    struct request *next)
2574{
2575        struct cfq_queue *cfqq = RQ_CFQQ(rq);
2576        struct cfq_data *cfqd = q->elevator->elevator_data;
2577
2578        /*
2579         * reposition in fifo if next is older than rq
2580         */
2581        if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
2582            next->fifo_time < rq->fifo_time &&
2583            cfqq == RQ_CFQQ(next)) {
2584                list_move(&rq->queuelist, &next->queuelist);
2585                rq->fifo_time = next->fifo_time;
2586        }
2587
2588        if (cfqq->next_rq == next)
2589                cfqq->next_rq = rq;
2590        cfq_remove_request(next);
2591        cfqg_stats_update_io_merged(RQ_CFQG(rq), req_op(next), next->cmd_flags);
2592
2593        cfqq = RQ_CFQQ(next);
2594        /*
2595         * all requests of this queue are merged to other queues, delete it
2596         * from the service tree. If it's the active_queue,
2597         * cfq_dispatch_requests() will choose to expire it or do idle
2598         */
2599        if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list) &&
2600            cfqq != cfqd->active_queue)
2601                cfq_del_cfqq_rr(cfqd, cfqq);
2602}
2603
2604static int cfq_allow_bio_merge(struct request_queue *q, struct request *rq,
2605                               struct bio *bio)
2606{
2607        struct cfq_data *cfqd = q->elevator->elevator_data;
2608        struct cfq_io_cq *cic;
2609        struct cfq_queue *cfqq;
2610
2611        /*
2612         * Disallow merge of a sync bio into an async request.
2613         */
2614        if (cfq_bio_sync(bio) && !rq_is_sync(rq))
2615                return false;
2616
2617        /*
2618         * Lookup the cfqq that this bio will be queued with and allow
2619         * merge only if rq is queued there.
2620         */
2621        cic = cfq_cic_lookup(cfqd, current->io_context);
2622        if (!cic)
2623                return false;
2624
2625        cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
2626        return cfqq == RQ_CFQQ(rq);
2627}
2628
2629static int cfq_allow_rq_merge(struct request_queue *q, struct request *rq,
2630                              struct request *next)
2631{
2632        return RQ_CFQQ(rq) == RQ_CFQQ(next);
2633}
2634
2635static inline void cfq_del_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2636{
2637        hrtimer_try_to_cancel(&cfqd->idle_slice_timer);
2638        cfqg_stats_update_idle_time(cfqq->cfqg);
2639}
2640
2641static void __cfq_set_active_queue(struct cfq_data *cfqd,
2642                                   struct cfq_queue *cfqq)
2643{
2644        if (cfqq) {
2645                cfq_log_cfqq(cfqd, cfqq, "set_active wl_class:%d wl_type:%d",
2646                                cfqd->serving_wl_class, cfqd->serving_wl_type);
2647                cfqg_stats_update_avg_queue_size(cfqq->cfqg);
2648                cfqq->slice_start = 0;
2649                cfqq->dispatch_start = ktime_get_ns();
2650                cfqq->allocated_slice = 0;
2651                cfqq->slice_end = 0;
2652                cfqq->slice_dispatch = 0;
2653                cfqq->nr_sectors = 0;
2654
2655                cfq_clear_cfqq_wait_request(cfqq);
2656                cfq_clear_cfqq_must_dispatch(cfqq);
2657                cfq_clear_cfqq_must_alloc_slice(cfqq);
2658                cfq_clear_cfqq_fifo_expire(cfqq);
2659                cfq_mark_cfqq_slice_new(cfqq);
2660
2661                cfq_del_timer(cfqd, cfqq);
2662        }
2663
2664        cfqd->active_queue = cfqq;
2665}
2666
2667/*
2668 * current cfqq expired its slice (or was too idle), select new one
2669 */
2670static void
2671__cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2672                    bool timed_out)
2673{
2674        cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out);
2675
2676        if (cfq_cfqq_wait_request(cfqq))
2677                cfq_del_timer(cfqd, cfqq);
2678
2679        cfq_clear_cfqq_wait_request(cfqq);
2680        cfq_clear_cfqq_wait_busy(cfqq);
2681
2682        /*
2683         * If this cfqq is shared between multiple processes, check to
2684         * make sure that those processes are still issuing I/Os within
2685         * the mean seek distance.  If not, it may be time to break the
2686         * queues apart again.
2687         */
2688        if (cfq_cfqq_coop(cfqq) && CFQQ_SEEKY(cfqq))
2689                cfq_mark_cfqq_split_coop(cfqq);
2690
2691        /*
2692         * store what was left of this slice, if the queue idled/timed out
2693         */
2694        if (timed_out) {
2695                if (cfq_cfqq_slice_new(cfqq))
2696                        cfqq->slice_resid = cfq_scaled_cfqq_slice(cfqd, cfqq);
2697                else
2698                        cfqq->slice_resid = cfqq->slice_end - ktime_get_ns();
2699                cfq_log_cfqq(cfqd, cfqq, "resid=%lld", cfqq->slice_resid);
2700        }
2701
2702        cfq_group_served(cfqd, cfqq->cfqg, cfqq);
2703
2704        if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
2705                cfq_del_cfqq_rr(cfqd, cfqq);
2706
2707        cfq_resort_rr_list(cfqd, cfqq);
2708
2709        if (cfqq == cfqd->active_queue)
2710                cfqd->active_queue = NULL;
2711
2712        if (cfqd->active_cic) {
2713                put_io_context(cfqd->active_cic->icq.ioc);
2714                cfqd->active_cic = NULL;
2715        }
2716}
2717
2718static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out)
2719{
2720        struct cfq_queue *cfqq = cfqd->active_queue;
2721
2722        if (cfqq)
2723                __cfq_slice_expired(cfqd, cfqq, timed_out);
2724}
2725
2726/*
2727 * Get next queue for service. Unless we have a queue preemption,
2728 * we'll simply select the first cfqq in the service tree.
2729 */
2730static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
2731{
2732        struct cfq_rb_root *st = st_for(cfqd->serving_group,
2733                        cfqd->serving_wl_class, cfqd->serving_wl_type);
2734
2735        if (!cfqd->rq_queued)
2736                return NULL;
2737
2738        /* There is nothing to dispatch */
2739        if (!st)
2740                return NULL;
2741        if (RB_EMPTY_ROOT(&st->rb))
2742                return NULL;
2743        return cfq_rb_first(st);
2744}
2745
2746static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd)
2747{
2748        struct cfq_group *cfqg;
2749        struct cfq_queue *cfqq;
2750        int i, j;
2751        struct cfq_rb_root *st;
2752
2753        if (!cfqd->rq_queued)
2754                return NULL;
2755
2756        cfqg = cfq_get_next_cfqg(cfqd);
2757        if (!cfqg)
2758                return NULL;
2759
2760        for_each_cfqg_st(cfqg, i, j, st)
2761                if ((cfqq = cfq_rb_first(st)) != NULL)
2762                        return cfqq;
2763        return NULL;
2764}
2765
2766/*
2767 * Get and set a new active queue for service.
2768 */
2769static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
2770                                              struct cfq_queue *cfqq)
2771{
2772        if (!cfqq)
2773                cfqq = cfq_get_next_queue(cfqd);
2774
2775        __cfq_set_active_queue(cfqd, cfqq);
2776        return cfqq;
2777}
2778
2779static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
2780                                          struct request *rq)
2781{
2782        if (blk_rq_pos(rq) >= cfqd->last_position)
2783                return blk_rq_pos(rq) - cfqd->last_position;
2784        else
2785                return cfqd->last_position - blk_rq_pos(rq);
2786}
2787
2788static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2789                               struct request *rq)
2790{
2791        return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR;
2792}
2793
2794static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
2795                                    struct cfq_queue *cur_cfqq)
2796{
2797        struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
2798        struct rb_node *parent, *node;
2799        struct cfq_queue *__cfqq;
2800        sector_t sector = cfqd->last_position;
2801
2802        if (RB_EMPTY_ROOT(root))
2803                return NULL;
2804
2805        /*
2806         * First, if we find a request starting at the end of the last
2807         * request, choose it.
2808         */
2809        __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
2810        if (__cfqq)
2811                return __cfqq;
2812
2813        /*
2814         * If the exact sector wasn't found, the parent of the NULL leaf
2815         * will contain the closest sector.
2816         */
2817        __cfqq = rb_entry(parent, struct cfq_queue, p_node);
2818        if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
2819                return __cfqq;
2820
2821        if (blk_rq_pos(__cfqq->next_rq) < sector)
2822                node = rb_next(&__cfqq->p_node);
2823        else
2824                node = rb_prev(&__cfqq->p_node);
2825        if (!node)
2826                return NULL;
2827
2828        __cfqq = rb_entry(node, struct cfq_queue, p_node);
2829        if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
2830                return __cfqq;
2831
2832        return NULL;
2833}
2834
2835/*
2836 * cfqd - obvious
2837 * cur_cfqq - passed in so that we don't decide that the current queue is
2838 *            closely cooperating with itself.
2839 *
2840 * So, basically we're assuming that that cur_cfqq has dispatched at least
2841 * one request, and that cfqd->last_position reflects a position on the disk
2842 * associated with the I/O issued by cur_cfqq.  I'm not sure this is a valid
2843 * assumption.
2844 */
2845static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
2846                                              struct cfq_queue *cur_cfqq)
2847{
2848        struct cfq_queue *cfqq;
2849
2850        if (cfq_class_idle(cur_cfqq))
2851                return NULL;
2852        if (!cfq_cfqq_sync(cur_cfqq))
2853                return NULL;
2854        if (CFQQ_SEEKY(cur_cfqq))
2855                return NULL;
2856
2857        /*
2858         * Don't search priority tree if it's the only queue in the group.
2859         */
2860        if (cur_cfqq->cfqg->nr_cfqq == 1)
2861                return NULL;
2862
2863        /*
2864         * We should notice if some of the queues are cooperating, eg
2865         * working closely on the same area of the disk. In that case,
2866         * we can group them together and don't waste time idling.
2867         */
2868        cfqq = cfqq_close(cfqd, cur_cfqq);
2869        if (!cfqq)
2870                return NULL;
2871
2872        /* If new queue belongs to different cfq_group, don't choose it */
2873        if (cur_cfqq->cfqg != cfqq->cfqg)
2874                return NULL;
2875
2876        /*
2877         * It only makes sense to merge sync queues.
2878         */
2879        if (!cfq_cfqq_sync(cfqq))
2880                return NULL;
2881        if (CFQQ_SEEKY(cfqq))
2882                return NULL;
2883
2884        /*
2885         * Do not merge queues of different priority classes
2886         */
2887        if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq))
2888                return NULL;
2889
2890        return cfqq;
2891}
2892
2893/*
2894 * Determine whether we should enforce idle window for this queue.
2895 */
2896
2897static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2898{
2899        enum wl_class_t wl_class = cfqq_class(cfqq);
2900        struct cfq_rb_root *st = cfqq->service_tree;
2901
2902        BUG_ON(!st);
2903        BUG_ON(!st->count);
2904
2905        if (!cfqd->cfq_slice_idle)
2906                return false;
2907
2908        /* We never do for idle class queues. */
2909        if (wl_class == IDLE_WORKLOAD)
2910                return false;
2911
2912        /* We do for queues that were marked with idle window flag. */
2913        if (cfq_cfqq_idle_window(cfqq) &&
2914           !(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag))
2915                return true;
2916
2917        /*
2918         * Otherwise, we do only if they are the last ones
2919         * in their service tree.
2920         */
2921        if (st->count == 1 && cfq_cfqq_sync(cfqq) &&
2922           !cfq_io_thinktime_big(cfqd, &st->ttime, false))
2923                return true;
2924        cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d", st->count);
2925        return false;
2926}
2927
2928static void cfq_arm_slice_timer(struct cfq_data *cfqd)
2929{
2930        struct cfq_queue *cfqq = cfqd->active_queue;
2931        struct cfq_rb_root *st = cfqq->service_tree;
2932        struct cfq_io_cq *cic;
2933        u64 sl, group_idle = 0;
2934        u64 now = ktime_get_ns();
2935
2936        /*
2937         * SSD device without seek penalty, disable idling. But only do so
2938         * for devices that support queuing, otherwise we still have a problem
2939         * with sync vs async workloads.
2940         */
2941        if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)
2942                return;
2943
2944        WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
2945        WARN_ON(cfq_cfqq_slice_new(cfqq));
2946
2947        /*
2948         * idle is disabled, either manually or by past process history
2949         */
2950        if (!cfq_should_idle(cfqd, cfqq)) {
2951                /* no queue idling. Check for group idling */
2952                if (cfqd->cfq_group_idle)
2953                        group_idle = cfqd->cfq_group_idle;
2954                else
2955                        return;
2956        }
2957
2958        /*
2959         * still active requests from this queue, don't idle
2960         */
2961        if (cfqq->dispatched)
2962                return;
2963
2964        /*
2965         * task has exited, don't wait
2966         */
2967        cic = cfqd->active_cic;
2968        if (!cic || !atomic_read(&cic->icq.ioc->active_ref))
2969                return;
2970
2971        /*
2972         * If our average think time is larger than the remaining time
2973         * slice, then don't idle. This avoids overrunning the allotted
2974         * time slice.
2975         */
2976        if (sample_valid(cic->ttime.ttime_samples) &&
2977            (cfqq->slice_end - now < cic->ttime.ttime_mean)) {
2978                cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%llu",
2979                             cic->ttime.ttime_mean);
2980                return;
2981        }
2982
2983        /*
2984         * There are other queues in the group or this is the only group and
2985         * it has too big thinktime, don't do group idle.
2986         */
2987        if (group_idle &&
2988            (cfqq->cfqg->nr_cfqq > 1 ||
2989             cfq_io_thinktime_big(cfqd, &st->ttime, true)))
2990                return;
2991
2992        cfq_mark_cfqq_wait_request(cfqq);
2993
2994        if (group_idle)
2995                sl = cfqd->cfq_group_idle;
2996        else
2997                sl = cfqd->cfq_slice_idle;
2998
2999        hrtimer_start(&cfqd->idle_slice_timer, ns_to_ktime(sl),
3000                      HRTIMER_MODE_REL);
3001        cfqg_stats_set_start_idle_time(cfqq->cfqg);
3002        cfq_log_cfqq(cfqd, cfqq, "arm_idle: %llu group_idle: %d", sl,
3003                        group_idle ? 1 : 0);
3004}
3005
3006/*
3007 * Move request from internal lists to the request queue dispatch list.
3008 */
3009static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
3010{
3011        struct cfq_data *cfqd = q->elevator->elevator_data;
3012        struct cfq_queue *cfqq = RQ_CFQQ(rq);
3013
3014        cfq_log_cfqq(cfqd, cfqq, "dispatch_insert");
3015
3016        cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq);
3017        cfq_remove_request(rq);
3018        cfqq->dispatched++;
3019        (RQ_CFQG(rq))->dispatched++;
3020        elv_dispatch_sort(q, rq);
3021
3022        cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++;
3023        cfqq->nr_sectors += blk_rq_sectors(rq);
3024}
3025
3026/*
3027 * return expired entry, or NULL to just start from scratch in rbtree
3028 */
3029static struct request *cfq_check_fifo(struct cfq_queue *cfqq)
3030{
3031        struct request *rq = NULL;
3032
3033        if (cfq_cfqq_fifo_expire(cfqq))
3034                return NULL;
3035
3036        cfq_mark_cfqq_fifo_expire(cfqq);
3037
3038        if (list_empty(&cfqq->fifo))
3039                return NULL;
3040
3041        rq = rq_entry_fifo(cfqq->fifo.next);
3042        if (ktime_get_ns() < rq->fifo_time)
3043                rq = NULL;
3044
3045        return rq;
3046}
3047
3048static inline int
3049cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3050{
3051        const int base_rq = cfqd->cfq_slice_async_rq;
3052
3053        WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
3054
3055        return 2 * base_rq * (IOPRIO_BE_NR - cfqq->ioprio);
3056}
3057
3058/*
3059 * Must be called with the queue_lock held.
3060 */
3061static int cfqq_process_refs(struct cfq_queue *cfqq)
3062{
3063        int process_refs, io_refs;
3064
3065        io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE];
3066        process_refs = cfqq->ref - io_refs;
3067        BUG_ON(process_refs < 0);
3068        return process_refs;
3069}
3070
3071static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq)
3072{
3073        int process_refs, new_process_refs;
3074        struct cfq_queue *__cfqq;
3075
3076        /*
3077         * If there are no process references on the new_cfqq, then it is
3078         * unsafe to follow the ->new_cfqq chain as other cfqq's in the
3079         * chain may have dropped their last reference (not just their
3080         * last process reference).
3081         */
3082        if (!cfqq_process_refs(new_cfqq))
3083                return;
3084
3085        /* Avoid a circular list and skip interim queue merges */
3086        while ((__cfqq = new_cfqq->new_cfqq)) {
3087                if (__cfqq == cfqq)
3088                        return;
3089                new_cfqq = __cfqq;
3090        }
3091
3092        process_refs = cfqq_process_refs(cfqq);
3093        new_process_refs = cfqq_process_refs(new_cfqq);
3094        /*
3095         * If the process for the cfqq has gone away, there is no
3096         * sense in merging the queues.
3097         */
3098        if (process_refs == 0 || new_process_refs == 0)
3099                return;
3100
3101        /*
3102         * Merge in the direction of the lesser amount of work.
3103         */
3104        if (new_process_refs >= process_refs) {
3105                cfqq->new_cfqq = new_cfqq;
3106                new_cfqq->ref += process_refs;
3107        } else {
3108                new_cfqq->new_cfqq = cfqq;
3109                cfqq->ref += new_process_refs;
3110        }
3111}
3112
3113static enum wl_type_t cfq_choose_wl_type(struct cfq_data *cfqd,
3114                        struct cfq_group *cfqg, enum wl_class_t wl_class)
3115{
3116        struct cfq_queue *queue;
3117        int i;
3118        bool key_valid = false;
3119        u64 lowest_key = 0;
3120        enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD;
3121
3122        for (i = 0; i <= SYNC_WORKLOAD; ++i) {
3123                /* select the one with lowest rb_key */
3124                queue = cfq_rb_first(st_for(cfqg, wl_class, i));
3125                if (queue &&
3126                    (!key_valid || queue->rb_key < lowest_key)) {
3127                        lowest_key = queue->rb_key;
3128                        cur_best = i;
3129                        key_valid = true;
3130                }
3131        }
3132
3133        return cur_best;
3134}
3135
3136static void
3137choose_wl_class_and_type(struct cfq_data *cfqd, struct cfq_group *cfqg)
3138{
3139        u64 slice;
3140        unsigned count;
3141        struct cfq_rb_root *st;
3142        u64 group_slice;
3143        enum wl_class_t original_class = cfqd->serving_wl_class;
3144        u64 now = ktime_get_ns();
3145
3146        /* Choose next priority. RT > BE > IDLE */
3147        if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg))
3148                cfqd->serving_wl_class = RT_WORKLOAD;
3149        else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg))
3150                cfqd->serving_wl_class = BE_WORKLOAD;
3151        else {
3152                cfqd->serving_wl_class = IDLE_WORKLOAD;
3153                cfqd->workload_expires = now + jiffies_to_nsecs(1);
3154                return;
3155        }
3156
3157        if (original_class != cfqd->serving_wl_class)
3158                goto new_workload;
3159
3160        /*
3161         * For RT and BE, we have to choose also the type
3162         * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
3163         * expiration time
3164         */
3165        st = st_for(cfqg, cfqd->serving_wl_class, cfqd->serving_wl_type);
3166        count = st->count;
3167
3168        /*
3169         * check workload expiration, and that we still have other queues ready
3170         */
3171        if (count && !(now > cfqd->workload_expires))
3172                return;
3173
3174new_workload:
3175        /* otherwise select new workload type */
3176        cfqd->serving_wl_type = cfq_choose_wl_type(cfqd, cfqg,
3177                                        cfqd->serving_wl_class);
3178        st = st_for(cfqg, cfqd->serving_wl_class, cfqd->serving_wl_type);
3179        count = st->count;
3180
3181        /*
3182         * the workload slice is computed as a fraction of target latency
3183         * proportional to the number of queues in that workload, over
3184         * all the queues in the same priority class
3185         */
3186        group_slice = cfq_group_slice(cfqd, cfqg);
3187
3188        slice = div_u64(group_slice * count,
3189                max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_wl_class],
3190                      cfq_group_busy_queues_wl(cfqd->serving_wl_class, cfqd,
3191                                        cfqg)));
3192
3193        if (cfqd->serving_wl_type == ASYNC_WORKLOAD) {
3194                u64 tmp;
3195
3196                /*
3197                 * Async queues are currently system wide. Just taking
3198                 * proportion of queues with-in same group will lead to higher
3199                 * async ratio system wide as generally root group is going
3200                 * to have higher weight. A more accurate thing would be to
3201                 * calculate system wide asnc/sync ratio.
3202                 */
3203                tmp = cfqd->cfq_target_latency *
3204                        cfqg_busy_async_queues(cfqd, cfqg);
3205                tmp = div_u64(tmp, cfqd->busy_queues);
3206                slice = min_t(u64, slice, tmp);
3207
3208                /* async workload slice is scaled down according to
3209                 * the sync/async slice ratio. */
3210                slice = div64_u64(slice*cfqd->cfq_slice[0], cfqd->cfq_slice[1]);
3211        } else
3212                /* sync workload slice is at least 2 * cfq_slice_idle */
3213                slice = max(slice, 2 * cfqd->cfq_slice_idle);
3214
3215        slice = max_t(u64, slice, CFQ_MIN_TT);
3216        cfq_log(cfqd, "workload slice:%llu", slice);
3217        cfqd->workload_expires = now + slice;
3218}
3219
3220static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd)
3221{
3222        struct cfq_rb_root *st = &cfqd->grp_service_tree;
3223        struct cfq_group *cfqg;
3224
3225        if (RB_EMPTY_ROOT(&st->rb))
3226                return NULL;
3227        cfqg = cfq_rb_first_group(st);
3228        update_min_vdisktime(st);
3229        return cfqg;
3230}
3231
3232static void cfq_choose_cfqg(struct cfq_data *cfqd)
3233{
3234        struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd);
3235        u64 now = ktime_get_ns();
3236
3237        cfqd->serving_group = cfqg;
3238
3239        /* Restore the workload type data */
3240        if (cfqg->saved_wl_slice) {
3241                cfqd->workload_expires = now + cfqg->saved_wl_slice;
3242                cfqd->serving_wl_type = cfqg->saved_wl_type;
3243                cfqd->serving_wl_class = cfqg->saved_wl_class;
3244        } else
3245                cfqd->workload_expires = now - 1;
3246
3247        choose_wl_class_and_type(cfqd, cfqg);
3248}
3249
3250/*
3251 * Select a queue for service. If we have a current active queue,
3252 * check whether to continue servicing it, or retrieve and set a new one.
3253 */
3254static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
3255{
3256        struct cfq_queue *cfqq, *new_cfqq = NULL;
3257        u64 now = ktime_get_ns();
3258
3259        cfqq = cfqd->active_queue;
3260        if (!cfqq)
3261                goto new_queue;
3262
3263        if (!cfqd->rq_queued)
3264                return NULL;
3265
3266        /*
3267         * We were waiting for group to get backlogged. Expire the queue
3268         */
3269        if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list))
3270                goto expire;
3271
3272        /*
3273         * The active queue has run out of time, expire it and select new.
3274         */
3275        if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) {
3276                /*
3277                 * If slice had not expired at the completion of last request
3278                 * we might not have turned on wait_busy flag. Don't expire
3279                 * the queue yet. Allow the group to get backlogged.
3280                 *
3281                 * The very fact that we have used the slice, that means we
3282                 * have been idling all along on this queue and it should be
3283                 * ok to wait for this request to complete.
3284                 */
3285                if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list)
3286                    && cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
3287                        cfqq = NULL;
3288                        goto keep_queue;
3289                } else
3290                        goto check_group_idle;
3291        }
3292
3293        /*
3294         * The active queue has requests and isn't expired, allow it to
3295         * dispatch.
3296         */
3297        if (!RB_EMPTY_ROOT(&cfqq->sort_list))
3298                goto keep_queue;
3299
3300        /*
3301         * If another queue has a request waiting within our mean seek
3302         * distance, let it run.  The expire code will check for close
3303         * cooperators and put the close queue at the front of the service
3304         * tree.  If possible, merge the expiring queue with the new cfqq.
3305         */
3306        new_cfqq = cfq_close_cooperator(cfqd, cfqq);
3307        if (new_cfqq) {
3308                if (!cfqq->new_cfqq)
3309                        cfq_setup_merge(cfqq, new_cfqq);
3310                goto expire;
3311        }
3312
3313        /*
3314         * No requests pending. If the active queue still has requests in
3315         * flight or is idling for a new request, allow either of these
3316         * conditions to happen (or time out) before selecting a new queue.
3317         */
3318        if (hrtimer_active(&cfqd->idle_slice_timer)) {
3319                cfqq = NULL;
3320                goto keep_queue;
3321        }
3322
3323        /*
3324         * This is a deep seek queue, but the device is much faster than
3325         * the queue can deliver, don't idle
3326         **/
3327        if (CFQQ_SEEKY(cfqq) && cfq_cfqq_idle_window(cfqq) &&
3328            (cfq_cfqq_slice_new(cfqq) ||
3329            (cfqq->slice_end - now > now - cfqq->slice_start))) {
3330                cfq_clear_cfqq_deep(cfqq);
3331                cfq_clear_cfqq_idle_window(cfqq);
3332        }
3333
3334        if (cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
3335                cfqq = NULL;
3336                goto keep_queue;
3337        }
3338
3339        /*
3340         * If group idle is enabled and there are requests dispatched from
3341         * this group, wait for requests to complete.
3342         */
3343check_group_idle:
3344        if (cfqd->cfq_group_idle && cfqq->cfqg->nr_cfqq == 1 &&
3345            cfqq->cfqg->dispatched &&
3346            !cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true)) {
3347                cfqq = NULL;
3348                goto keep_queue;
3349        }
3350
3351expire:
3352        cfq_slice_expired(cfqd, 0);
3353new_queue:
3354        /*
3355         * Current queue expired. Check if we have to switch to a new
3356         * service tree
3357         */
3358        if (!new_cfqq)
3359                cfq_choose_cfqg(cfqd);
3360
3361        cfqq = cfq_set_active_queue(cfqd, new_cfqq);
3362keep_queue:
3363        return cfqq;
3364}
3365
3366static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq)
3367{
3368        int dispatched = 0;
3369
3370        while (cfqq->next_rq) {
3371                cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq);
3372                dispatched++;
3373        }
3374
3375        BUG_ON(!list_empty(&cfqq->fifo));
3376
3377        /* By default cfqq is not expired if it is empty. Do it explicitly */
3378        __cfq_slice_expired(cfqq->cfqd, cfqq, 0);
3379        return dispatched;
3380}
3381
3382/*
3383 * Drain our current requests. Used for barriers and when switching
3384 * io schedulers on-the-fly.
3385 */
3386static int cfq_forced_dispatch(struct cfq_data *cfqd)
3387{
3388        struct cfq_queue *cfqq;
3389        int dispatched = 0;
3390
3391        /* Expire the timeslice of the current active queue first */
3392        cfq_slice_expired(cfqd, 0);
3393        while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) {
3394                __cfq_set_active_queue(cfqd, cfqq);
3395                dispatched += __cfq_forced_dispatch_cfqq(cfqq);
3396        }
3397
3398        BUG_ON(cfqd->busy_queues);
3399
3400        cfq_log(cfqd, "forced_dispatch=%d", dispatched);
3401        return dispatched;
3402}
3403
3404static inline bool cfq_slice_used_soon(struct cfq_data *cfqd,
3405        struct cfq_queue *cfqq)
3406{
3407        u64 now = ktime_get_ns();
3408
3409        /* the queue hasn't finished any request, can't estimate */
3410        if (cfq_cfqq_slice_new(cfqq))
3411                return true;
3412        if (now + cfqd->cfq_slice_idle * cfqq->dispatched > cfqq->slice_end)
3413                return true;
3414
3415        return false;
3416}
3417
3418static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3419{
3420        unsigned int max_dispatch;
3421
3422        if (cfq_cfqq_must_dispatch(cfqq))
3423                return true;
3424
3425        /*
3426         * Drain async requests before we start sync IO
3427         */
3428        if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC])
3429                return false;
3430
3431        /*
3432         * If this is an async queue and we have sync IO in flight, let it wait
3433         */
3434        if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq))
3435                return false;
3436
3437        max_dispatch = max_t(unsigned int, cfqd->cfq_quantum / 2, 1);
3438        if (cfq_class_idle(cfqq))
3439                max_dispatch = 1;
3440
3441        /*
3442         * Does this cfqq already have too much IO in flight?
3443         */
3444        if (cfqq->dispatched >= max_dispatch) {
3445                bool promote_sync = false;
3446                /*
3447                 * idle queue must always only have a single IO in flight
3448                 */
3449                if (cfq_class_idle(cfqq))
3450                        return false;
3451
3452                /*
3453                 * If there is only one sync queue
3454                 * we can ignore async queue here and give the sync
3455                 * queue no dispatch limit. The reason is a sync queue can
3456                 * preempt async queue, limiting the sync queue doesn't make
3457                 * sense. This is useful for aiostress test.
3458                 */
3459                if (cfq_cfqq_sync(cfqq) && cfqd->busy_sync_queues == 1)
3460                        promote_sync = true;
3461
3462                /*
3463                 * We have other queues, don't allow more IO from this one
3464                 */
3465                if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq) &&
3466                                !promote_sync)
3467                        return false;
3468
3469                /*
3470                 * Sole queue user, no limit
3471                 */
3472                if (cfqd->busy_queues == 1 || promote_sync)
3473                        max_dispatch = -1;
3474                else
3475                        /*
3476                         * Normally we start throttling cfqq when cfq_quantum/2
3477                         * requests have been dispatched. But we can drive
3478                         * deeper queue depths at the beginning of slice
3479                         * subjected to upper limit of cfq_quantum.
3480                         * */
3481                        max_dispatch = cfqd->cfq_quantum;
3482        }
3483
3484        /*
3485         * Async queues must wait a bit before being allowed dispatch.
3486         * We also ramp up the dispatch depth gradually for async IO,
3487         * based on the last sync IO we serviced
3488         */
3489        if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) {
3490                u64 last_sync = ktime_get_ns() - cfqd->last_delayed_sync;
3491                unsigned int depth;
3492
3493                depth = div64_u64(last_sync, cfqd->cfq_slice[1]);
3494                if (!depth && !cfqq->dispatched)
3495                        depth = 1;
3496                if (depth < max_dispatch)
3497                        max_dispatch = depth;
3498        }
3499
3500        /*
3501         * If we're below the current max, allow a dispatch
3502         */
3503        return cfqq->dispatched < max_dispatch;
3504}
3505
3506/*
3507 * Dispatch a request from cfqq, moving them to the request queue
3508 * dispatch list.
3509 */
3510static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3511{
3512        struct request *rq;
3513
3514        BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list));
3515
3516        rq = cfq_check_fifo(cfqq);
3517        if (rq)
3518                cfq_mark_cfqq_must_dispatch(cfqq);
3519
3520        if (!cfq_may_dispatch(cfqd, cfqq))
3521                return false;
3522
3523        /*
3524         * follow expired path, else get first next available
3525         */
3526        if (!rq)
3527                rq = cfqq->next_rq;
3528        else
3529                cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq);
3530
3531        /*
3532         * insert request into driver dispatch list
3533         */
3534        cfq_dispatch_insert(cfqd->queue, rq);
3535
3536        if (!cfqd->active_cic) {
3537                struct cfq_io_cq *cic = RQ_CIC(rq);
3538
3539                atomic_long_inc(&cic->icq.ioc->refcount);
3540                cfqd->active_cic = cic;
3541        }
3542
3543        return true;
3544}
3545
3546/*
3547 * Find the cfqq that we need to service and move a request from that to the
3548 * dispatch list
3549 */
3550static int cfq_dispatch_requests(struct request_queue *q, int force)
3551{
3552        struct cfq_data *cfqd = q->elevator->elevator_data;
3553        struct cfq_queue *cfqq;
3554
3555        if (!cfqd->busy_queues)
3556                return 0;
3557
3558        if (unlikely(force))
3559                return cfq_forced_dispatch(cfqd);
3560
3561        cfqq = cfq_select_queue(cfqd);
3562        if (!cfqq)
3563                return 0;
3564
3565        /*
3566         * Dispatch a request from this cfqq, if it is allowed
3567         */
3568        if (!cfq_dispatch_request(cfqd, cfqq))
3569                return 0;
3570
3571        cfqq->slice_dispatch++;
3572        cfq_clear_cfqq_must_dispatch(cfqq);
3573
3574        /*
3575         * expire an async queue immediately if it has used up its slice. idle
3576         * queue always expire after 1 dispatch round.
3577         */
3578        if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
3579            cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
3580            cfq_class_idle(cfqq))) {
3581                cfqq->slice_end = ktime_get_ns() + 1;
3582                cfq_slice_expired(cfqd, 0);
3583        }
3584
3585        cfq_log_cfqq(cfqd, cfqq, "dispatched a request");
3586        return 1;
3587}
3588
3589/*
3590 * task holds one reference to the queue, dropped when task exits. each rq
3591 * in-flight on this queue also holds a reference, dropped when rq is freed.
3592 *
3593 * Each cfq queue took a reference on the parent group. Drop it now.
3594 * queue lock must be held here.
3595 */
3596static void cfq_put_queue(struct cfq_queue *cfqq)
3597{
3598        struct cfq_data *cfqd = cfqq->cfqd;
3599        struct cfq_group *cfqg;
3600
3601        BUG_ON(cfqq->ref <= 0);
3602
3603        cfqq->ref--;
3604        if (cfqq->ref)
3605                return;
3606
3607        cfq_log_cfqq(cfqd, cfqq, "put_queue");
3608        BUG_ON(rb_first(&cfqq->sort_list));
3609        BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
3610        cfqg = cfqq->cfqg;
3611
3612        if (unlikely(cfqd->active_queue == cfqq)) {
3613                __cfq_slice_expired(cfqd, cfqq, 0);
3614                cfq_schedule_dispatch(cfqd);
3615        }
3616
3617        BUG_ON(cfq_cfqq_on_rr(cfqq));
3618        kmem_cache_free(cfq_pool, cfqq);
3619        cfqg_put(cfqg);
3620}
3621
3622static void cfq_put_cooperator(struct cfq_queue *cfqq)
3623{
3624        struct cfq_queue *__cfqq, *next;
3625
3626        /*
3627         * If this queue was scheduled to merge with another queue, be
3628         * sure to drop the reference taken on that queue (and others in
3629         * the merge chain).  See cfq_setup_merge and cfq_merge_cfqqs.
3630         */
3631        __cfqq = cfqq->new_cfqq;
3632        while (__cfqq) {
3633                if (__cfqq == cfqq) {
3634                        WARN(1, "cfqq->new_cfqq loop detected\n");
3635                        break;
3636                }
3637                next = __cfqq->new_cfqq;
3638                cfq_put_queue(__cfqq);
3639                __cfqq = next;
3640        }
3641}
3642
3643static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3644{
3645        if (unlikely(cfqq == cfqd->active_queue)) {
3646                __cfq_slice_expired(cfqd, cfqq, 0);
3647                cfq_schedule_dispatch(cfqd);
3648        }
3649
3650        cfq_put_cooperator(cfqq);
3651
3652        cfq_put_queue(cfqq);
3653}
3654
3655static void cfq_init_icq(struct io_cq *icq)
3656{
3657        struct cfq_io_cq *cic = icq_to_cic(icq);
3658
3659        cic->ttime.last_end_request = ktime_get_ns();
3660}
3661
3662static void cfq_exit_icq(struct io_cq *icq)
3663{
3664        struct cfq_io_cq *cic = icq_to_cic(icq);
3665        struct cfq_data *cfqd = cic_to_cfqd(cic);
3666
3667        if (cic_to_cfqq(cic, false)) {
3668                cfq_exit_cfqq(cfqd, cic_to_cfqq(cic, false));
3669                cic_set_cfqq(cic, NULL, false);
3670        }
3671
3672        if (cic_to_cfqq(cic, true)) {
3673                cfq_exit_cfqq(cfqd, cic_to_cfqq(cic, true));
3674                cic_set_cfqq(cic, NULL, true);
3675        }
3676}
3677
3678static void cfq_init_prio_data(struct cfq_queue *cfqq, struct cfq_io_cq *cic)
3679{
3680        struct task_struct *tsk = current;
3681        int ioprio_class;
3682
3683        if (!cfq_cfqq_prio_changed(cfqq))
3684                return;
3685
3686        ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio);
3687        switch (ioprio_class) {
3688        default:
3689                printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
3690        case IOPRIO_CLASS_NONE:
3691                /*
3692                 * no prio set, inherit CPU scheduling settings
3693                 */
3694                cfqq->ioprio = task_nice_ioprio(tsk);
3695                cfqq->ioprio_class = task_nice_ioclass(tsk);
3696                break;
3697        case IOPRIO_CLASS_RT:
3698                cfqq->ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
3699                cfqq->ioprio_class = IOPRIO_CLASS_RT;
3700                break;
3701        case IOPRIO_CLASS_BE:
3702                cfqq->ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
3703                cfqq->ioprio_class = IOPRIO_CLASS_BE;
3704                break;
3705        case IOPRIO_CLASS_IDLE:
3706                cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
3707                cfqq->ioprio = 7;
3708                cfq_clear_cfqq_idle_window(cfqq);
3709                break;
3710        }
3711
3712        /*
3713         * keep track of original prio settings in case we have to temporarily
3714         * elevate the priority of this queue
3715         */
3716        cfqq->org_ioprio = cfqq->ioprio;
3717        cfqq->org_ioprio_class = cfqq->ioprio_class;
3718        cfq_clear_cfqq_prio_changed(cfqq);
3719}
3720
3721static void check_ioprio_changed(struct cfq_io_cq *cic, struct bio *bio)
3722{
3723        int ioprio = cic->icq.ioc->ioprio;
3724        struct cfq_data *cfqd = cic_to_cfqd(cic);
3725        struct cfq_queue *cfqq;
3726
3727        /*
3728         * Check whether ioprio has changed.  The condition may trigger
3729         * spuriously on a newly created cic but there's no harm.
3730         */
3731        if (unlikely(!cfqd) || likely(cic->ioprio == ioprio))
3732                return;
3733
3734        cfqq = cic_to_cfqq(cic, false);
3735        if (cfqq) {
3736                cfq_put_queue(cfqq);
3737                cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic, bio);
3738                cic_set_cfqq(cic, cfqq, false);
3739        }
3740
3741        cfqq = cic_to_cfqq(cic, true);
3742        if (cfqq)
3743                cfq_mark_cfqq_prio_changed(cfqq);
3744
3745        cic->ioprio = ioprio;
3746}
3747
3748static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3749                          pid_t pid, bool is_sync)
3750{
3751        RB_CLEAR_NODE(&cfqq->rb_node);
3752        RB_CLEAR_NODE(&cfqq->p_node);
3753        INIT_LIST_HEAD(&cfqq->fifo);
3754
3755        cfqq->ref = 0;
3756        cfqq->cfqd = cfqd;
3757
3758        cfq_mark_cfqq_prio_changed(cfqq);
3759
3760        if (is_sync) {
3761                if (!cfq_class_idle(cfqq))
3762                        cfq_mark_cfqq_idle_window(cfqq);
3763                cfq_mark_cfqq_sync(cfqq);
3764        }
3765        cfqq->pid = pid;
3766}
3767
3768#ifdef CONFIG_CFQ_GROUP_IOSCHED
3769static void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio)
3770{
3771        struct cfq_data *cfqd = cic_to_cfqd(cic);
3772        struct cfq_queue *cfqq;
3773        uint64_t serial_nr;
3774
3775        rcu_read_lock();
3776        serial_nr = bio_blkcg(bio)->css.serial_nr;
3777        rcu_read_unlock();
3778
3779        /*
3780         * Check whether blkcg has changed.  The condition may trigger
3781         * spuriously on a newly created cic but there's no harm.
3782         */
3783        if (unlikely(!cfqd) || likely(cic->blkcg_serial_nr == serial_nr))
3784                return;
3785
3786        /*
3787         * Drop reference to queues.  New queues will be assigned in new
3788         * group upon arrival of fresh requests.
3789         */
3790        cfqq = cic_to_cfqq(cic, false);
3791        if (cfqq) {
3792                cfq_log_cfqq(cfqd, cfqq, "changed cgroup");
3793                cic_set_cfqq(cic, NULL, false);
3794                cfq_put_queue(cfqq);
3795        }
3796
3797        cfqq = cic_to_cfqq(cic, true);
3798        if (cfqq) {
3799                cfq_log_cfqq(cfqd, cfqq, "changed cgroup");
3800                cic_set_cfqq(cic, NULL, true);
3801                cfq_put_queue(cfqq);
3802        }
3803
3804        cic->blkcg_serial_nr = serial_nr;
3805}
3806#else
3807static inline void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio) { }
3808#endif  /* CONFIG_CFQ_GROUP_IOSCHED */
3809
3810static struct cfq_queue **
3811cfq_async_queue_prio(struct cfq_group *cfqg, int ioprio_class, int ioprio)
3812{
3813        switch (ioprio_class) {
3814        case IOPRIO_CLASS_RT:
3815                return &cfqg->async_cfqq[0][ioprio];
3816        case IOPRIO_CLASS_NONE:
3817                ioprio = IOPRIO_NORM;
3818                /* fall through */
3819        case IOPRIO_CLASS_BE:
3820                return &cfqg->async_cfqq[1][ioprio];
3821        case IOPRIO_CLASS_IDLE:
3822                return &cfqg->async_idle_cfqq;
3823        default:
3824                BUG();
3825        }
3826}
3827
3828static struct cfq_queue *
3829cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic,
3830              struct bio *bio)
3831{
3832        int ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio);
3833        int ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
3834        struct cfq_queue **async_cfqq = NULL;
3835        struct cfq_queue *cfqq;
3836        struct cfq_group *cfqg;
3837
3838        rcu_read_lock();
3839        cfqg = cfq_lookup_cfqg(cfqd, bio_blkcg(bio));
3840        if (!cfqg) {
3841                cfqq = &cfqd->oom_cfqq;
3842                goto out;
3843        }
3844
3845        if (!is_sync) {
3846                if (!ioprio_valid(cic->ioprio)) {
3847                        struct task_struct *tsk = current;
3848                        ioprio = task_nice_ioprio(tsk);
3849                        ioprio_class = task_nice_ioclass(tsk);
3850                }
3851                async_cfqq = cfq_async_queue_prio(cfqg, ioprio_class, ioprio);
3852                cfqq = *async_cfqq;
3853                if (cfqq)
3854                        goto out;
3855        }
3856
3857        cfqq = kmem_cache_alloc_node(cfq_pool, GFP_NOWAIT | __GFP_ZERO,
3858                                     cfqd->queue->node);
3859        if (!cfqq) {
3860                cfqq = &cfqd->oom_cfqq;
3861                goto out;
3862        }
3863
3864        cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
3865        cfq_init_prio_data(cfqq, cic);
3866        cfq_link_cfqq_cfqg(cfqq, cfqg);
3867        cfq_log_cfqq(cfqd, cfqq, "alloced");
3868
3869        if (async_cfqq) {
3870                /* a new async queue is created, pin and remember */
3871                cfqq->ref++;
3872                *async_cfqq = cfqq;
3873        }
3874out:
3875        cfqq->ref++;
3876        rcu_read_unlock();
3877        return cfqq;
3878}
3879
3880static void
3881__cfq_update_io_thinktime(struct cfq_ttime *ttime, u64 slice_idle)
3882{
3883        u64 elapsed = ktime_get_ns() - ttime->last_end_request;
3884        elapsed = min(elapsed, 2UL * slice_idle);
3885
3886        ttime->ttime_samples = (7*ttime->ttime_samples + 256) / 8;
3887        ttime->ttime_total = div_u64(7*ttime->ttime_total + 256*elapsed,  8);
3888        ttime->ttime_mean = div64_ul(ttime->ttime_total + 128,
3889                                     ttime->ttime_samples);
3890}
3891
3892static void
3893cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3894                        struct cfq_io_cq *cic)
3895{
3896        if (cfq_cfqq_sync(cfqq)) {
3897                __cfq_update_io_thinktime(&cic->ttime, cfqd->cfq_slice_idle);
3898                __cfq_update_io_thinktime(&cfqq->service_tree->ttime,
3899                        cfqd->cfq_slice_idle);
3900        }
3901#ifdef CONFIG_CFQ_GROUP_IOSCHED
3902        __cfq_update_io_thinktime(&cfqq->cfqg->ttime, cfqd->cfq_group_idle);
3903#endif
3904}
3905
3906static void
3907cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3908                       struct request *rq)
3909{
3910        sector_t sdist = 0;
3911        sector_t n_sec = blk_rq_sectors(rq);
3912        if (cfqq->last_request_pos) {
3913                if (cfqq->last_request_pos < blk_rq_pos(rq))
3914                        sdist = blk_rq_pos(rq) - cfqq->last_request_pos;
3915                else
3916                        sdist = cfqq->last_request_pos - blk_rq_pos(rq);
3917        }
3918
3919        cfqq->seek_history <<= 1;
3920        if (blk_queue_nonrot(cfqd->queue))
3921                cfqq->seek_history |= (n_sec < CFQQ_SECT_THR_NONROT);
3922        else
3923                cfqq->seek_history |= (sdist > CFQQ_SEEK_THR);
3924}
3925
3926/*
3927 * Disable idle window if the process thinks too long or seeks so much that
3928 * it doesn't matter
3929 */
3930static void
3931cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3932                       struct cfq_io_cq *cic)
3933{
3934        int old_idle, enable_idle;
3935
3936        /*
3937         * Don't idle for async or idle io prio class
3938         */
3939        if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq))
3940                return;
3941
3942        enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
3943
3944        if (cfqq->queued[0] + cfqq->queued[1] >= 4)
3945                cfq_mark_cfqq_deep(cfqq);
3946
3947        if (cfqq->next_rq && (cfqq->next_rq->cmd_flags & REQ_NOIDLE))
3948                enable_idle = 0;
3949        else if (!atomic_read(&cic->icq.ioc->active_ref) ||
3950                 !cfqd->cfq_slice_idle ||
3951                 (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq)))
3952                enable_idle = 0;
3953        else if (sample_valid(cic->ttime.ttime_samples)) {
3954                if (cic->ttime.ttime_mean > cfqd->cfq_slice_idle)
3955                        enable_idle = 0;
3956                else
3957                        enable_idle = 1;
3958        }
3959
3960        if (old_idle != enable_idle) {
3961                cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle);
3962                if (enable_idle)
3963                        cfq_mark_cfqq_idle_window(cfqq);
3964                else
3965                        cfq_clear_cfqq_idle_window(cfqq);
3966        }
3967}
3968
3969/*
3970 * Check if new_cfqq should preempt the currently active queue. Return 0 for
3971 * no or if we aren't sure, a 1 will cause a preempt.
3972 */
3973static bool
3974cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
3975                   struct request *rq)
3976{
3977        struct cfq_queue *cfqq;
3978
3979        cfqq = cfqd->active_queue;
3980        if (!cfqq)
3981                return false;
3982
3983        if (cfq_class_idle(new_cfqq))
3984                return false;
3985
3986        if (cfq_class_idle(cfqq))
3987                return true;
3988
3989        /*
3990         * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice.
3991         */
3992        if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq))
3993                return false;
3994
3995        /*
3996         * if the new request is sync, but the currently running queue is
3997         * not, let the sync request have priority.
3998         */
3999        if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq) && !cfq_cfqq_must_dispatch(cfqq))
4000                return true;
4001
4002        /*
4003         * Treat ancestors of current cgroup the same way as current cgroup.
4004         * For anybody else we disallow preemption to guarantee service
4005         * fairness among cgroups.
4006         */
4007        if (!cfqg_is_descendant(cfqq->cfqg, new_cfqq->cfqg))
4008                return false;
4009
4010        if (cfq_slice_used(cfqq))
4011                return true;
4012
4013        /*
4014         * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
4015         */
4016        if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
4017                return true;
4018
4019        WARN_ON_ONCE(cfqq->ioprio_class != new_cfqq->ioprio_class);
4020        /* Allow preemption only if we are idling on sync-noidle tree */
4021        if (cfqd->serving_wl_type == SYNC_NOIDLE_WORKLOAD &&
4022            cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD &&
4023            RB_EMPTY_ROOT(&cfqq->sort_list))
4024                return true;
4025
4026        /*
4027         * So both queues are sync. Let the new request get disk time if
4028         * it's a metadata request and the current queue is doing regular IO.
4029         */
4030        if ((rq->cmd_flags & REQ_PRIO) && !cfqq->prio_pending)
4031                return true;
4032
4033        /* An idle queue should not be idle now for some reason */
4034        if (RB_EMPTY_ROOT(&cfqq->sort_list) && !cfq_should_idle(cfqd, cfqq))
4035                return true;
4036
4037        if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq))
4038                return false;
4039
4040        /*
4041         * if this request is as-good as one we would expect from the
4042         * current cfqq, let it preempt
4043         */
4044        if (cfq_rq_close(cfqd, cfqq, rq))
4045                return true;
4046
4047        return false;
4048}
4049
4050/*
4051 * cfqq preempts the active queue. if we allowed preempt with no slice left,
4052 * let it have half of its nominal slice.
4053 */
4054static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
4055{
4056        enum wl_type_t old_type = cfqq_type(cfqd->active_queue);
4057
4058        cfq_log_cfqq(cfqd, cfqq, "preempt");
4059        cfq_slice_expired(cfqd, 1);
4060
4061        /*
4062         * workload type is changed, don't save slice, otherwise preempt
4063         * doesn't happen
4064         */
4065        if (old_type != cfqq_type(cfqq))
4066                cfqq->cfqg->saved_wl_slice = 0;
4067
4068        /*
4069         * Put the new queue at the front of the of the current list,
4070         * so we know that it will be selected next.
4071         */
4072        BUG_ON(!cfq_cfqq_on_rr(cfqq));
4073
4074        cfq_service_tree_add(cfqd, cfqq, 1);
4075
4076        cfqq->slice_end = 0;
4077        cfq_mark_cfqq_slice_new(cfqq);
4078}
4079
4080/*
4081 * Called when a new fs request (rq) is added (to cfqq). Check if there's
4082 * something we should do about it
4083 */
4084static void
4085cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
4086                struct request *rq)
4087{
4088        struct cfq_io_cq *cic = RQ_CIC(rq);
4089
4090        cfqd->rq_queued++;
4091        if (rq->cmd_flags & REQ_PRIO)
4092                cfqq->prio_pending++;
4093
4094        cfq_update_io_thinktime(cfqd, cfqq, cic);
4095        cfq_update_io_seektime(cfqd, cfqq, rq);
4096        cfq_update_idle_window(cfqd, cfqq, cic);
4097
4098        cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
4099
4100        if (cfqq == cfqd->active_queue) {
4101                /*
4102                 * Remember that we saw a request from this process, but
4103                 * don't start queuing just yet. Otherwise we risk seeing lots
4104                 * of tiny requests, because we disrupt the normal plugging
4105                 * and merging. If the request is already larger than a single
4106                 * page, let it rip immediately. For that case we assume that
4107                 * merging is already done. Ditto for a busy system that
4108                 * has other work pending, don't risk delaying until the
4109                 * idle timer unplug to continue working.
4110                 */
4111                if (cfq_cfqq_wait_request(cfqq)) {
4112                        if (blk_rq_bytes(rq) > PAGE_SIZE ||
4113                            cfqd->busy_queues > 1) {
4114                                cfq_del_timer(cfqd, cfqq);
4115                                cfq_clear_cfqq_wait_request(cfqq);
4116                                __blk_run_queue(cfqd->queue);
4117                        } else {
4118                                cfqg_stats_update_idle_time(cfqq->cfqg);
4119                                cfq_mark_cfqq_must_dispatch(cfqq);
4120                        }
4121                }
4122        } else if (cfq_should_preempt(cfqd, cfqq, rq)) {
4123                /*
4124                 * not the active queue - expire current slice if it is
4125                 * idle and has expired it's mean thinktime or this new queue
4126                 * has some old slice time left and is of higher priority or
4127                 * this new queue is RT and the current one is BE
4128                 */
4129                cfq_preempt_queue(cfqd, cfqq);
4130                __blk_run_queue(cfqd->queue);
4131        }
4132}
4133
4134static void cfq_insert_request(struct request_queue *q, struct request *rq)
4135{
4136        struct cfq_data *cfqd = q->elevator->elevator_data;
4137        struct cfq_queue *cfqq = RQ_CFQQ(rq);
4138
4139        cfq_log_cfqq(cfqd, cfqq, "insert_request");
4140        cfq_init_prio_data(cfqq, RQ_CIC(rq));
4141
4142        rq->fifo_time = ktime_get_ns() + cfqd->cfq_fifo_expire[rq_is_sync(rq)];
4143        list_add_tail(&rq->queuelist, &cfqq->fifo);
4144        cfq_add_rq_rb(rq);
4145        cfqg_stats_update_io_add(RQ_CFQG(rq), cfqd->serving_group, req_op(rq),
4146                                 rq->cmd_flags);
4147        cfq_rq_enqueued(cfqd, cfqq, rq);
4148}
4149
4150/*
4151 * Update hw_tag based on peak queue depth over 50 samples under
4152 * sufficient load.
4153 */
4154static void cfq_update_hw_tag(struct cfq_data *cfqd)
4155{
4156        struct cfq_queue *cfqq = cfqd->active_queue;
4157
4158        if (cfqd->rq_in_driver > cfqd->hw_tag_est_depth)
4159                cfqd->hw_tag_est_depth = cfqd->rq_in_driver;
4160
4161        if (cfqd->hw_tag == 1)
4162                return;
4163
4164        if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
4165            cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN)
4166                return;
4167
4168        /*
4169         * If active queue hasn't enough requests and can idle, cfq might not
4170         * dispatch sufficient requests to hardware. Don't zero hw_tag in this
4171         * case
4172         */
4173        if (cfqq && cfq_cfqq_idle_window(cfqq) &&
4174            cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] <
4175            CFQ_HW_QUEUE_MIN && cfqd->rq_in_driver < CFQ_HW_QUEUE_MIN)
4176                return;
4177
4178        if (cfqd->hw_tag_samples++ < 50)
4179                return;
4180
4181        if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN)
4182                cfqd->hw_tag = 1;
4183        else
4184                cfqd->hw_tag = 0;
4185}
4186
4187static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq)
4188{
4189        struct cfq_io_cq *cic = cfqd->active_cic;
4190        u64 now = ktime_get_ns();
4191
4192        /* If the queue already has requests, don't wait */
4193        if (!RB_EMPTY_ROOT(&cfqq->sort_list))
4194                return false;
4195
4196        /* If there are other queues in the group, don't wait */
4197        if (cfqq->cfqg->nr_cfqq > 1)
4198                return false;
4199
4200        /* the only queue in the group, but think time is big */
4201        if (cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true))
4202                return false;
4203
4204        if (cfq_slice_used(cfqq))
4205                return true;
4206
4207        /* if slice left is less than think time, wait busy */
4208        if (cic && sample_valid(cic->ttime.ttime_samples)
4209            && (cfqq->slice_end - now < cic->ttime.ttime_mean))
4210                return true;
4211
4212        /*
4213         * If think times is less than a jiffy than ttime_mean=0 and above
4214         * will not be true. It might happen that slice has not expired yet
4215         * but will expire soon (4-5 ns) during select_queue(). To cover the
4216         * case where think time is less than a jiffy, mark the queue wait
4217         * busy if only 1 jiffy is left in the slice.
4218         */
4219        if (cfqq->slice_end - now <= jiffies_to_nsecs(1))
4220                return true;
4221
4222        return false;
4223}
4224
4225static void cfq_completed_request(struct request_queue *q, struct request *rq)
4226{
4227        struct cfq_queue *cfqq = RQ_CFQQ(rq);
4228        struct cfq_data *cfqd = cfqq->cfqd;
4229        const int sync = rq_is_sync(rq);
4230        u64 now = ktime_get_ns();
4231
4232        cfq_log_cfqq(cfqd, cfqq, "complete rqnoidle %d",
4233                     !!(rq->cmd_flags & REQ_NOIDLE));
4234
4235        cfq_update_hw_tag(cfqd);
4236
4237        WARN_ON(!cfqd->rq_in_driver);
4238        WARN_ON(!cfqq->dispatched);
4239        cfqd->rq_in_driver--;
4240        cfqq->dispatched--;
4241        (RQ_CFQG(rq))->dispatched--;
4242        cfqg_stats_update_completion(cfqq->cfqg, rq_start_time_ns(rq),
4243                                     rq_io_start_time_ns(rq), req_op(rq),
4244                                     rq->cmd_flags);
4245
4246        cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--;
4247
4248        if (sync) {
4249                struct cfq_rb_root *st;
4250
4251                RQ_CIC(rq)->ttime.last_end_request = now;
4252
4253                if (cfq_cfqq_on_rr(cfqq))
4254                        st = cfqq->service_tree;
4255                else
4256                        st = st_for(cfqq->cfqg, cfqq_class(cfqq),
4257                                        cfqq_type(cfqq));
4258
4259                st->ttime.last_end_request = now;
4260                /*
4261                 * We have to do this check in jiffies since start_time is in
4262                 * jiffies and it is not trivial to convert to ns. If
4263                 * cfq_fifo_expire[1] ever comes close to 1 jiffie, this test
4264                 * will become problematic but so far we are fine (the default
4265                 * is 128 ms).
4266                 */
4267                if (!time_after(rq->start_time +
4268                                  nsecs_to_jiffies(cfqd->cfq_fifo_expire[1]),
4269                                jiffies))
4270                        cfqd->last_delayed_sync = now;
4271        }
4272
4273#ifdef CONFIG_CFQ_GROUP_IOSCHED
4274        cfqq->cfqg->ttime.last_end_request = now;
4275#endif
4276
4277        /*
4278         * If this is the active queue, check if it needs to be expired,
4279         * or if we want to idle in case it has no pending requests.
4280         */
4281        if (cfqd->active_queue == cfqq) {
4282                const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list);
4283
4284                if (cfq_cfqq_slice_new(cfqq)) {
4285                        cfq_set_prio_slice(cfqd, cfqq);
4286                        cfq_clear_cfqq_slice_new(cfqq);
4287                }
4288
4289                /*
4290                 * Should we wait for next request to come in before we expire
4291                 * the queue.
4292                 */
4293                if (cfq_should_wait_busy(cfqd, cfqq)) {
4294                        u64 extend_sl = cfqd->cfq_slice_idle;
4295                        if (!cfqd->cfq_slice_idle)
4296                                extend_sl = cfqd->cfq_group_idle;
4297                        cfqq->slice_end = now + extend_sl;
4298                        cfq_mark_cfqq_wait_busy(cfqq);
4299                        cfq_log_cfqq(cfqd, cfqq, "will busy wait");
4300                }
4301
4302                /*
4303                 * Idling is not enabled on:
4304                 * - expired queues
4305                 * - idle-priority queues
4306                 * - async queues
4307                 * - queues with still some requests queued
4308                 * - when there is a close cooperator
4309                 */
4310                if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq))
4311                        cfq_slice_expired(cfqd, 1);
4312                else if (sync && cfqq_empty &&
4313                         !cfq_close_cooperator(cfqd, cfqq)) {
4314                        cfq_arm_slice_timer(cfqd);
4315                }
4316        }
4317
4318        if (!cfqd->rq_in_driver)
4319                cfq_schedule_dispatch(cfqd);
4320}
4321
4322static void cfqq_boost_on_prio(struct cfq_queue *cfqq, int op_flags)
4323{
4324        /*
4325         * If REQ_PRIO is set, boost class and prio level, if it's below
4326         * BE/NORM. If prio is not set, restore the potentially boosted
4327         * class/prio level.
4328         */
4329        if (!(op_flags & REQ_PRIO)) {
4330                cfqq->ioprio_class = cfqq->org_ioprio_class;
4331                cfqq->ioprio = cfqq->org_ioprio;
4332        } else {
4333                if (cfq_class_idle(cfqq))
4334                        cfqq->ioprio_class = IOPRIO_CLASS_BE;
4335                if (cfqq->ioprio > IOPRIO_NORM)
4336                        cfqq->ioprio = IOPRIO_NORM;
4337        }
4338}
4339
4340static inline int __cfq_may_queue(struct cfq_queue *cfqq)
4341{
4342        if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) {
4343                cfq_mark_cfqq_must_alloc_slice(cfqq);
4344                return ELV_MQUEUE_MUST;
4345        }
4346
4347        return ELV_MQUEUE_MAY;
4348}
4349
4350static int cfq_may_queue(struct request_queue *q, int op, int op_flags)
4351{
4352        struct cfq_data *cfqd = q->elevator->elevator_data;
4353        struct task_struct *tsk = current;
4354        struct cfq_io_cq *cic;
4355        struct cfq_queue *cfqq;
4356
4357        /*
4358         * don't force setup of a queue from here, as a call to may_queue
4359         * does not necessarily imply that a request actually will be queued.
4360         * so just lookup a possibly existing queue, or return 'may queue'
4361         * if that fails
4362         */
4363        cic = cfq_cic_lookup(cfqd, tsk->io_context);
4364        if (!cic)
4365                return ELV_MQUEUE_MAY;
4366
4367        cfqq = cic_to_cfqq(cic, rw_is_sync(op, op_flags));
4368        if (cfqq) {
4369                cfq_init_prio_data(cfqq, cic);
4370                cfqq_boost_on_prio(cfqq, op_flags);
4371
4372                return __cfq_may_queue(cfqq);
4373        }
4374
4375        return ELV_MQUEUE_MAY;
4376}
4377
4378/*
4379 * queue lock held here
4380 */
4381static void cfq_put_request(struct request *rq)
4382{
4383        struct cfq_queue *cfqq = RQ_CFQQ(rq);
4384
4385        if (cfqq) {
4386                const int rw = rq_data_dir(rq);
4387
4388                BUG_ON(!cfqq->allocated[rw]);
4389                cfqq->allocated[rw]--;
4390
4391                /* Put down rq reference on cfqg */
4392                cfqg_put(RQ_CFQG(rq));
4393                rq->elv.priv[0] = NULL;
4394                rq->elv.priv[1] = NULL;
4395
4396                cfq_put_queue(cfqq);
4397        }
4398}
4399
4400static struct cfq_queue *
4401cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_cq *cic,
4402                struct cfq_queue *cfqq)
4403{
4404        cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq);
4405        cic_set_cfqq(cic, cfqq->new_cfqq, 1);
4406        cfq_mark_cfqq_coop(cfqq->new_cfqq);
4407        cfq_put_queue(cfqq);
4408        return cic_to_cfqq(cic, 1);
4409}
4410
4411/*
4412 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
4413 * was the last process referring to said cfqq.
4414 */
4415static struct cfq_queue *
4416split_cfqq(struct cfq_io_cq *cic, struct cfq_queue *cfqq)
4417{
4418        if (cfqq_process_refs(cfqq) == 1) {
4419                cfqq->pid = current->pid;
4420                cfq_clear_cfqq_coop(cfqq);
4421                cfq_clear_cfqq_split_coop(cfqq);
4422                return cfqq;
4423        }
4424
4425        cic_set_cfqq(cic, NULL, 1);
4426
4427        cfq_put_cooperator(cfqq);
4428
4429        cfq_put_queue(cfqq);
4430        return NULL;
4431}
4432/*
4433 * Allocate cfq data structures associated with this request.
4434 */
4435static int
4436cfq_set_request(struct request_queue *q, struct request *rq, struct bio *bio,
4437                gfp_t gfp_mask)
4438{
4439        struct cfq_data *cfqd = q->elevator->elevator_data;
4440        struct cfq_io_cq *cic = icq_to_cic(rq->elv.icq);
4441        const int rw = rq_data_dir(rq);
4442        const bool is_sync = rq_is_sync(rq);
4443        struct cfq_queue *cfqq;
4444
4445        spin_lock_irq(q->queue_lock);
4446
4447        check_ioprio_changed(cic, bio);
4448        check_blkcg_changed(cic, bio);
4449new_queue:
4450        cfqq = cic_to_cfqq(cic, is_sync);
4451        if (!cfqq || cfqq == &cfqd->oom_cfqq) {
4452                if (cfqq)
4453                        cfq_put_queue(cfqq);
4454                cfqq = cfq_get_queue(cfqd, is_sync, cic, bio);
4455                cic_set_cfqq(cic, cfqq, is_sync);
4456        } else {
4457                /*
4458                 * If the queue was seeky for too long, break it apart.
4459                 */
4460                if (cfq_cfqq_coop(cfqq) && cfq_cfqq_split_coop(cfqq)) {
4461                        cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq");
4462                        cfqq = split_cfqq(cic, cfqq);
4463                        if (!cfqq)
4464                                goto new_queue;
4465                }
4466
4467                /*
4468                 * Check to see if this queue is scheduled to merge with
4469                 * another, closely cooperating queue.  The merging of
4470                 * queues happens here as it must be done in process context.
4471                 * The reference on new_cfqq was taken in merge_cfqqs.
4472                 */
4473                if (cfqq->new_cfqq)
4474                        cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq);
4475        }
4476
4477        cfqq->allocated[rw]++;
4478
4479        cfqq->ref++;
4480        cfqg_get(cfqq->cfqg);
4481        rq->elv.priv[0] = cfqq;
4482        rq->elv.priv[1] = cfqq->cfqg;
4483        spin_unlock_irq(q->queue_lock);
4484        return 0;
4485}
4486
4487static void cfq_kick_queue(struct work_struct *work)
4488{
4489        struct cfq_data *cfqd =
4490                container_of(work, struct cfq_data, unplug_work);
4491        struct request_queue *q = cfqd->queue;
4492
4493        spin_lock_irq(q->queue_lock);
4494        __blk_run_queue(cfqd->queue);
4495        spin_unlock_irq(q->queue_lock);
4496}
4497
4498/*
4499 * Timer running if the active_queue is currently idling inside its time slice
4500 */
4501static enum hrtimer_restart cfq_idle_slice_timer(struct hrtimer *timer)
4502{
4503        struct cfq_data *cfqd = container_of(timer, struct cfq_data,
4504                                             idle_slice_timer);
4505        struct cfq_queue *cfqq;
4506        unsigned long flags;
4507        int timed_out = 1;
4508
4509        cfq_log(cfqd, "idle timer fired");
4510
4511        spin_lock_irqsave(cfqd->queue->queue_lock, flags);
4512
4513        cfqq = cfqd->active_queue;
4514        if (cfqq) {
4515                timed_out = 0;
4516
4517                /*
4518                 * We saw a request before the queue expired, let it through
4519                 */
4520                if (cfq_cfqq_must_dispatch(cfqq))
4521                        goto out_kick;
4522
4523                /*
4524                 * expired
4525                 */
4526                if (cfq_slice_used(cfqq))
4527                        goto expire;
4528
4529                /*
4530                 * only expire and reinvoke request handler, if there are
4531                 * other queues with pending requests
4532                 */
4533                if (!cfqd->busy_queues)
4534                        goto out_cont;
4535
4536                /*
4537                 * not expired and it has a request pending, let it dispatch
4538                 */
4539                if (!RB_EMPTY_ROOT(&cfqq->sort_list))
4540                        goto out_kick;
4541
4542                /*
4543                 * Queue depth flag is reset only when the idle didn't succeed
4544                 */
4545                cfq_clear_cfqq_deep(cfqq);
4546        }
4547expire:
4548        cfq_slice_expired(cfqd, timed_out);
4549out_kick:
4550        cfq_schedule_dispatch(cfqd);
4551out_cont:
4552        spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
4553        return HRTIMER_NORESTART;
4554}
4555
4556static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
4557{
4558        hrtimer_cancel(&cfqd->idle_slice_timer);
4559        cancel_work_sync(&cfqd->unplug_work);
4560}
4561
4562static void cfq_exit_queue(struct elevator_queue *e)
4563{
4564        struct cfq_data *cfqd = e->elevator_data;
4565        struct request_queue *q = cfqd->queue;
4566
4567        cfq_shutdown_timer_wq(cfqd);
4568
4569        spin_lock_irq(q->queue_lock);
4570
4571        if (cfqd->active_queue)
4572                __cfq_slice_expired(cfqd, cfqd->active_queue, 0);
4573
4574        spin_unlock_irq(q->queue_lock);
4575
4576        cfq_shutdown_timer_wq(cfqd);
4577
4578#ifdef CONFIG_CFQ_GROUP_IOSCHED
4579        blkcg_deactivate_policy(q, &blkcg_policy_cfq);
4580#else
4581        kfree(cfqd->root_group);
4582#endif
4583        kfree(cfqd);
4584}
4585
4586static int cfq_init_queue(struct request_queue *q, struct elevator_type *e)
4587{
4588        struct cfq_data *cfqd;
4589        struct blkcg_gq *blkg __maybe_unused;
4590        int i, ret;
4591        struct elevator_queue *eq;
4592
4593        eq = elevator_alloc(q, e);
4594        if (!eq)
4595                return -ENOMEM;
4596
4597        cfqd = kzalloc_node(sizeof(*cfqd), GFP_KERNEL, q->node);
4598        if (!cfqd) {
4599                kobject_put(&eq->kobj);
4600                return -ENOMEM;
4601        }
4602        eq->elevator_data = cfqd;
4603
4604        cfqd->queue = q;
4605        spin_lock_irq(q->queue_lock);
4606        q->elevator = eq;
4607        spin_unlock_irq(q->queue_lock);
4608
4609        /* Init root service tree */
4610        cfqd->grp_service_tree = CFQ_RB_ROOT;
4611
4612        /* Init root group and prefer root group over other groups by default */
4613#ifdef CONFIG_CFQ_GROUP_IOSCHED
4614        ret = blkcg_activate_policy(q, &blkcg_policy_cfq);
4615        if (ret)
4616                goto out_free;
4617
4618        cfqd->root_group = blkg_to_cfqg(q->root_blkg);
4619#else
4620        ret = -ENOMEM;
4621        cfqd->root_group = kzalloc_node(sizeof(*cfqd->root_group),
4622                                        GFP_KERNEL, cfqd->queue->node);
4623        if (!cfqd->root_group)
4624                goto out_free;
4625
4626        cfq_init_cfqg_base(cfqd->root_group);
4627        cfqd->root_group->weight = 2 * CFQ_WEIGHT_LEGACY_DFL;
4628        cfqd->root_group->leaf_weight = 2 * CFQ_WEIGHT_LEGACY_DFL;
4629#endif
4630
4631        /*
4632         * Not strictly needed (since RB_ROOT just clears the node and we
4633         * zeroed cfqd on alloc), but better be safe in case someone decides
4634         * to add magic to the rb code
4635         */
4636        for (i = 0; i < CFQ_PRIO_LISTS; i++)
4637                cfqd->prio_trees[i] = RB_ROOT;
4638
4639        /*
4640         * Our fallback cfqq if cfq_get_queue() runs into OOM issues.
4641         * Grab a permanent reference to it, so that the normal code flow
4642         * will not attempt to free it.  oom_cfqq is linked to root_group
4643         * but shouldn't hold a reference as it'll never be unlinked.  Lose
4644         * the reference from linking right away.
4645         */
4646        cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0);
4647        cfqd->oom_cfqq.ref++;
4648
4649        spin_lock_irq(q->queue_lock);
4650        cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, cfqd->root_group);
4651        cfqg_put(cfqd->root_group);
4652        spin_unlock_irq(q->queue_lock);
4653
4654        hrtimer_init(&cfqd->idle_slice_timer, CLOCK_MONOTONIC,
4655                     HRTIMER_MODE_REL);
4656        cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
4657
4658        INIT_WORK(&cfqd->unplug_work, cfq_kick_queue);
4659
4660        cfqd->cfq_quantum = cfq_quantum;
4661        cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
4662        cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
4663        cfqd->cfq_back_max = cfq_back_max;
4664        cfqd->cfq_back_penalty = cfq_back_penalty;
4665        cfqd->cfq_slice[0] = cfq_slice_async;
4666        cfqd->cfq_slice[1] = cfq_slice_sync;
4667        cfqd->cfq_target_latency = cfq_target_latency;
4668        cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
4669        cfqd->cfq_slice_idle = cfq_slice_idle;
4670        cfqd->cfq_group_idle = cfq_group_idle;
4671        cfqd->cfq_latency = 1;
4672        cfqd->hw_tag = -1;
4673        /*
4674         * we optimistically start assuming sync ops weren't delayed in last
4675         * second, in order to have larger depth for async operations.
4676         */
4677        cfqd->last_delayed_sync = ktime_get_ns() - NSEC_PER_SEC;
4678        return 0;
4679
4680out_free:
4681        kfree(cfqd);
4682        kobject_put(&eq->kobj);
4683        return ret;
4684}
4685
4686static void cfq_registered_queue(struct request_queue *q)
4687{
4688        struct elevator_queue *e = q->elevator;
4689        struct cfq_data *cfqd = e->elevator_data;
4690
4691        /*
4692         * Default to IOPS mode with no idling for SSDs
4693         */
4694        if (blk_queue_nonrot(q))
4695                cfqd->cfq_slice_idle = 0;
4696}
4697
4698/*
4699 * sysfs parts below -->
4700 */
4701static ssize_t
4702cfq_var_show(unsigned int var, char *page)
4703{
4704        return sprintf(page, "%u\n", var);
4705}
4706
4707static ssize_t
4708cfq_var_store(unsigned int *var, const char *page, size_t count)
4709{
4710        char *p = (char *) page;
4711
4712        *var = simple_strtoul(p, &p, 10);
4713        return count;
4714}
4715
4716#define SHOW_FUNCTION(__FUNC, __VAR, __CONV)                            \
4717static ssize_t __FUNC(struct elevator_queue *e, char *page)             \
4718{                                                                       \
4719        struct cfq_data *cfqd = e->elevator_data;                       \
4720        u64 __data = __VAR;                                             \
4721        if (__CONV)                                                     \
4722                __data = div_u64(__data, NSEC_PER_MSEC);                        \
4723        return cfq_var_show(__data, (page));                            \
4724}
4725SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
4726SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
4727SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
4728SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0);
4729SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0);
4730SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
4731SHOW_FUNCTION(cfq_group_idle_show, cfqd->cfq_group_idle, 1);
4732SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
4733SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
4734SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
4735SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0);
4736SHOW_FUNCTION(cfq_target_latency_show, cfqd->cfq_target_latency, 1);
4737#undef SHOW_FUNCTION
4738
4739#define USEC_SHOW_FUNCTION(__FUNC, __VAR)                               \
4740static ssize_t __FUNC(struct elevator_queue *e, char *page)             \
4741{                                                                       \
4742        struct cfq_data *cfqd = e->elevator_data;                       \
4743        u64 __data = __VAR;                                             \
4744        __data = div_u64(__data, NSEC_PER_USEC);                        \
4745        return cfq_var_show(__data, (page));                            \
4746}
4747USEC_SHOW_FUNCTION(cfq_slice_idle_us_show, cfqd->cfq_slice_idle);
4748USEC_SHOW_FUNCTION(cfq_group_idle_us_show, cfqd->cfq_group_idle);
4749USEC_SHOW_FUNCTION(cfq_slice_sync_us_show, cfqd->cfq_slice[1]);
4750USEC_SHOW_FUNCTION(cfq_slice_async_us_show, cfqd->cfq_slice[0]);
4751USEC_SHOW_FUNCTION(cfq_target_latency_us_show, cfqd->cfq_target_latency);
4752#undef USEC_SHOW_FUNCTION
4753
4754#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV)                 \
4755static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
4756{                                                                       \
4757        struct cfq_data *cfqd = e->elevator_data;                       \
4758        unsigned int __data;                                            \
4759        int ret = cfq_var_store(&__data, (page), count);                \
4760        if (__data < (MIN))                                             \
4761                __data = (MIN);                                         \
4762        else if (__data > (MAX))                                        \
4763                __data = (MAX);                                         \
4764        if (__CONV)                                                     \
4765                *(__PTR) = (u64)__data * NSEC_PER_MSEC;                 \
4766        else                                                            \
4767                *(__PTR) = __data;                                      \
4768        return ret;                                                     \
4769}
4770STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
4771STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1,
4772                UINT_MAX, 1);
4773STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1,
4774                UINT_MAX, 1);
4775STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
4776STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1,
4777                UINT_MAX, 0);
4778STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
4779STORE_FUNCTION(cfq_group_idle_store, &cfqd->cfq_group_idle, 0, UINT_MAX, 1);
4780STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
4781STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
4782STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
4783                UINT_MAX, 0);
4784STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0);
4785STORE_FUNCTION(cfq_target_latency_store, &cfqd->cfq_target_latency, 1, UINT_MAX, 1);
4786#undef STORE_FUNCTION
4787
4788#define USEC_STORE_FUNCTION(__FUNC, __PTR, MIN, MAX)                    \
4789static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
4790{                                                                       \
4791        struct cfq_data *cfqd = e->elevator_data;                       \
4792        unsigned int __data;                                            \
4793        int ret = cfq_var_store(&__data, (page), count);                \
4794        if (__data < (MIN))                                             \
4795                __data = (MIN);                                         \
4796        else if (__data > (MAX))                                        \
4797                __data = (MAX);                                         \
4798        *(__PTR) = (u64)__data * NSEC_PER_USEC;                         \
4799        return ret;                                                     \
4800}
4801USEC_STORE_FUNCTION(cfq_slice_idle_us_store, &cfqd->cfq_slice_idle, 0, UINT_MAX);
4802USEC_STORE_FUNCTION(cfq_group_idle_us_store, &cfqd->cfq_group_idle, 0, UINT_MAX);
4803USEC_STORE_FUNCTION(cfq_slice_sync_us_store, &cfqd->cfq_slice[1], 1, UINT_MAX);
4804USEC_STORE_FUNCTION(cfq_slice_async_us_store, &cfqd->cfq_slice[0], 1, UINT_MAX);
4805USEC_STORE_FUNCTION(cfq_target_latency_us_store, &cfqd->cfq_target_latency, 1, UINT_MAX);
4806#undef USEC_STORE_FUNCTION
4807
4808#define CFQ_ATTR(name) \
4809        __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
4810
4811static struct elv_fs_entry cfq_attrs[] = {
4812        CFQ_ATTR(quantum),
4813        CFQ_ATTR(fifo_expire_sync),
4814        CFQ_ATTR(fifo_expire_async),
4815        CFQ_ATTR(back_seek_max),
4816        CFQ_ATTR(back_seek_penalty),
4817        CFQ_ATTR(slice_sync),
4818        CFQ_ATTR(slice_sync_us),
4819        CFQ_ATTR(slice_async),
4820        CFQ_ATTR(slice_async_us),
4821        CFQ_ATTR(slice_async_rq),
4822        CFQ_ATTR(slice_idle),
4823        CFQ_ATTR(slice_idle_us),
4824        CFQ_ATTR(group_idle),
4825        CFQ_ATTR(group_idle_us),
4826        CFQ_ATTR(low_latency),
4827        CFQ_ATTR(target_latency),
4828        CFQ_ATTR(target_latency_us),
4829        __ATTR_NULL
4830};
4831
4832static struct elevator_type iosched_cfq = {
4833        .ops = {
4834                .elevator_merge_fn =            cfq_merge,
4835                .elevator_merged_fn =           cfq_merged_request,
4836                .elevator_merge_req_fn =        cfq_merged_requests,
4837                .elevator_allow_bio_merge_fn =  cfq_allow_bio_merge,
4838                .elevator_allow_rq_merge_fn =   cfq_allow_rq_merge,
4839                .elevator_bio_merged_fn =       cfq_bio_merged,
4840                .elevator_dispatch_fn =         cfq_dispatch_requests,
4841                .elevator_add_req_fn =          cfq_insert_request,
4842                .elevator_activate_req_fn =     cfq_activate_request,
4843                .elevator_deactivate_req_fn =   cfq_deactivate_request,
4844                .elevator_completed_req_fn =    cfq_completed_request,
4845                .elevator_former_req_fn =       elv_rb_former_request,
4846                .elevator_latter_req_fn =       elv_rb_latter_request,
4847                .elevator_init_icq_fn =         cfq_init_icq,
4848                .elevator_exit_icq_fn =         cfq_exit_icq,
4849                .elevator_set_req_fn =          cfq_set_request,
4850                .elevator_put_req_fn =          cfq_put_request,
4851                .elevator_may_queue_fn =        cfq_may_queue,
4852                .elevator_init_fn =             cfq_init_queue,
4853                .elevator_exit_fn =             cfq_exit_queue,
4854                .elevator_registered_fn =       cfq_registered_queue,
4855        },
4856        .icq_size       =       sizeof(struct cfq_io_cq),
4857        .icq_align      =       __alignof__(struct cfq_io_cq),
4858        .elevator_attrs =       cfq_attrs,
4859        .elevator_name  =       "cfq",
4860        .elevator_owner =       THIS_MODULE,
4861};
4862
4863#ifdef CONFIG_CFQ_GROUP_IOSCHED
4864static struct blkcg_policy blkcg_policy_cfq = {
4865        .dfl_cftypes            = cfq_blkcg_files,
4866        .legacy_cftypes         = cfq_blkcg_legacy_files,
4867
4868        .cpd_alloc_fn           = cfq_cpd_alloc,
4869        .cpd_init_fn            = cfq_cpd_init,
4870        .cpd_free_fn            = cfq_cpd_free,
4871        .cpd_bind_fn            = cfq_cpd_bind,
4872
4873        .pd_alloc_fn            = cfq_pd_alloc,
4874        .pd_init_fn             = cfq_pd_init,
4875        .pd_offline_fn          = cfq_pd_offline,
4876        .pd_free_fn             = cfq_pd_free,
4877        .pd_reset_stats_fn      = cfq_pd_reset_stats,
4878};
4879#endif
4880
4881static int __init cfq_init(void)
4882{
4883        int ret;
4884
4885#ifdef CONFIG_CFQ_GROUP_IOSCHED
4886        ret = blkcg_policy_register(&blkcg_policy_cfq);
4887        if (ret)
4888                return ret;
4889#else
4890        cfq_group_idle = 0;
4891#endif
4892
4893        ret = -ENOMEM;
4894        cfq_pool = KMEM_CACHE(cfq_queue, 0);
4895        if (!cfq_pool)
4896                goto err_pol_unreg;
4897
4898        ret = elv_register(&iosched_cfq);
4899        if (ret)
4900                goto err_free_pool;
4901
4902        return 0;
4903
4904err_free_pool:
4905        kmem_cache_destroy(cfq_pool);
4906err_pol_unreg:
4907#ifdef CONFIG_CFQ_GROUP_IOSCHED
4908        blkcg_policy_unregister(&blkcg_policy_cfq);
4909#endif
4910        return ret;
4911}
4912
4913static void __exit cfq_exit(void)
4914{
4915#ifdef CONFIG_CFQ_GROUP_IOSCHED
4916        blkcg_policy_unregister(&blkcg_policy_cfq);
4917#endif
4918        elv_unregister(&iosched_cfq);
4919        kmem_cache_destroy(cfq_pool);
4920}
4921
4922module_init(cfq_init);
4923module_exit(cfq_exit);
4924
4925MODULE_AUTHOR("Jens Axboe");
4926MODULE_LICENSE("GPL");
4927MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");
4928