Version:  2.0.40 2.2.26 2.4.37 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10

Linux/block/cfq-iosched.c

  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 #include "blk-wbt.h"
 20 
 21 /*
 22  * tunables
 23  */
 24 /* max queue in one round of service */
 25 static const int cfq_quantum = 8;
 26 static const u64 cfq_fifo_expire[2] = { NSEC_PER_SEC / 4, NSEC_PER_SEC / 8 };
 27 /* maximum backwards seek, in KiB */
 28 static const int cfq_back_max = 16 * 1024;
 29 /* penalty of a backwards seek */
 30 static const int cfq_back_penalty = 2;
 31 static const u64 cfq_slice_sync = NSEC_PER_SEC / 10;
 32 static u64 cfq_slice_async = NSEC_PER_SEC / 25;
 33 static const int cfq_slice_async_rq = 2;
 34 static u64 cfq_slice_idle = NSEC_PER_SEC / 125;
 35 static u64 cfq_group_idle = NSEC_PER_SEC / 125;
 36 static const u64 cfq_target_latency = (u64)NSEC_PER_SEC * 3/10; /* 300 ms */
 37 static const int cfq_hist_divisor = 4;
 38 
 39 /*
 40  * offset from end of service tree
 41  */
 42 #define CFQ_IDLE_DELAY          (NSEC_PER_SEC / 5)
 43 
 44 /*
 45  * below this threshold, we consider thinktime immediate
 46  */
 47 #define CFQ_MIN_TT              (2 * NSEC_PER_SEC / HZ)
 48 
 49 #define CFQ_SLICE_SCALE         (5)
 50 #define CFQ_HW_QUEUE_MIN        (5)
 51 #define CFQ_SERVICE_SHIFT       12
 52 
 53 #define CFQQ_SEEK_THR           (sector_t)(8 * 100)
 54 #define CFQQ_CLOSE_THR          (sector_t)(8 * 1024)
 55 #define CFQQ_SECT_THR_NONROT    (sector_t)(2 * 32)
 56 #define CFQQ_SEEKY(cfqq)        (hweight32(cfqq->seek_history) > 32/8)
 57 
 58 #define RQ_CIC(rq)              icq_to_cic((rq)->elv.icq)
 59 #define RQ_CFQQ(rq)             (struct cfq_queue *) ((rq)->elv.priv[0])
 60 #define RQ_CFQG(rq)             (struct cfq_group *) ((rq)->elv.priv[1])
 61 
 62 static struct kmem_cache *cfq_pool;
 63 
 64 #define CFQ_PRIO_LISTS          IOPRIO_BE_NR
 65 #define cfq_class_idle(cfqq)    ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
 66 #define cfq_class_rt(cfqq)      ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
 67 
 68 #define sample_valid(samples)   ((samples) > 80)
 69 #define rb_entry_cfqg(node)     rb_entry((node), struct cfq_group, rb_node)
 70 
 71 /* blkio-related constants */
 72 #define CFQ_WEIGHT_LEGACY_MIN   10
 73 #define CFQ_WEIGHT_LEGACY_DFL   500
 74 #define CFQ_WEIGHT_LEGACY_MAX   1000
 75 
 76 struct cfq_ttime {
 77         u64 last_end_request;
 78 
 79         u64 ttime_total;
 80         u64 ttime_mean;
 81         unsigned long ttime_samples;
 82 };
 83 
 84 /*
 85  * Most of our rbtree usage is for sorting with min extraction, so
 86  * if we cache the leftmost node we don't have to walk down the tree
 87  * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should
 88  * move this into the elevator for the rq sorting as well.
 89  */
 90 struct cfq_rb_root {
 91         struct rb_root rb;
 92         struct rb_node *left;
 93         unsigned count;
 94         u64 min_vdisktime;
 95         struct cfq_ttime ttime;
 96 };
 97 #define CFQ_RB_ROOT     (struct cfq_rb_root) { .rb = RB_ROOT, \
 98                         .ttime = {.last_end_request = ktime_get_ns(),},}
 99 
100 /*
101  * Per process-grouping structure
102  */
103 struct cfq_queue {
104         /* reference count */
105         int ref;
106         /* various state flags, see below */
107         unsigned int flags;
108         /* parent cfq_data */
109         struct cfq_data *cfqd;
110         /* service_tree member */
111         struct rb_node rb_node;
112         /* service_tree key */
113         u64 rb_key;
114         /* prio tree member */
115         struct rb_node p_node;
116         /* prio tree root we belong to, if any */
117         struct rb_root *p_root;
118         /* sorted list of pending requests */
119         struct rb_root sort_list;
120         /* if fifo isn't expired, next request to serve */
121         struct request *next_rq;
122         /* requests queued in sort_list */
123         int queued[2];
124         /* currently allocated requests */
125         int allocated[2];
126         /* fifo list of requests in sort_list */
127         struct list_head fifo;
128 
129         /* time when queue got scheduled in to dispatch first request. */
130         u64 dispatch_start;
131         u64 allocated_slice;
132         u64 slice_dispatch;
133         /* time when first request from queue completed and slice started. */
134         u64 slice_start;
135         u64 slice_end;
136         s64 slice_resid;
137 
138         /* pending priority requests */
139         int prio_pending;
140         /* number of requests that are on the dispatch list or inside driver */
141         int dispatched;
142 
143         /* io prio of this group */
144         unsigned short ioprio, org_ioprio;
145         unsigned short ioprio_class, org_ioprio_class;
146 
147         pid_t pid;
148 
149         u32 seek_history;
150         sector_t last_request_pos;
151 
152         struct cfq_rb_root *service_tree;
153         struct cfq_queue *new_cfqq;
154         struct cfq_group *cfqg;
155         /* Number of sectors dispatched from queue in single dispatch round */
156         unsigned long nr_sectors;
157 };
158 
159 /*
160  * First index in the service_trees.
161  * IDLE is handled separately, so it has negative index
162  */
163 enum wl_class_t {
164         BE_WORKLOAD = 0,
165         RT_WORKLOAD = 1,
166         IDLE_WORKLOAD = 2,
167         CFQ_PRIO_NR,
168 };
169 
170 /*
171  * Second index in the service_trees.
172  */
173 enum wl_type_t {
174         ASYNC_WORKLOAD = 0,
175         SYNC_NOIDLE_WORKLOAD = 1,
176         SYNC_WORKLOAD = 2
177 };
178 
179 struct cfqg_stats {
180 #ifdef CONFIG_CFQ_GROUP_IOSCHED
181         /* number of ios merged */
182         struct blkg_rwstat              merged;
183         /* total time spent on device in ns, may not be accurate w/ queueing */
184         struct blkg_rwstat              service_time;
185         /* total time spent waiting in scheduler queue in ns */
186         struct blkg_rwstat              wait_time;
187         /* number of IOs queued up */
188         struct blkg_rwstat              queued;
189         /* total disk time and nr sectors dispatched by this group */
190         struct blkg_stat                time;
191 #ifdef CONFIG_DEBUG_BLK_CGROUP
192         /* time not charged to this cgroup */
193         struct blkg_stat                unaccounted_time;
194         /* sum of number of ios queued across all samples */
195         struct blkg_stat                avg_queue_size_sum;
196         /* count of samples taken for average */
197         struct blkg_stat                avg_queue_size_samples;
198         /* how many times this group has been removed from service tree */
199         struct blkg_stat                dequeue;
200         /* total time spent waiting for it to be assigned a timeslice. */
201         struct blkg_stat                group_wait_time;
202         /* time spent idling for this blkcg_gq */
203         struct blkg_stat                idle_time;
204         /* total time with empty current active q with other requests queued */
205         struct blkg_stat                empty_time;
206         /* fields after this shouldn't be cleared on stat reset */
207         uint64_t                        start_group_wait_time;
208         uint64_t                        start_idle_time;
209         uint64_t                        start_empty_time;
210         uint16_t                        flags;
211 #endif  /* CONFIG_DEBUG_BLK_CGROUP */
212 #endif  /* CONFIG_CFQ_GROUP_IOSCHED */
213 };
214 
215 /* Per-cgroup data */
216 struct cfq_group_data {
217         /* must be the first member */
218         struct blkcg_policy_data cpd;
219 
220         unsigned int weight;
221         unsigned int leaf_weight;
222 };
223 
224 /* This is per cgroup per device grouping structure */
225 struct cfq_group {
226         /* must be the first member */
227         struct blkg_policy_data pd;
228 
229         /* group service_tree member */
230         struct rb_node rb_node;
231 
232         /* group service_tree key */
233         u64 vdisktime;
234 
235         /*
236          * The number of active cfqgs and sum of their weights under this
237          * cfqg.  This covers this cfqg's leaf_weight and all children's
238          * weights, but does not cover weights of further descendants.
239          *
240          * If a cfqg is on the service tree, it's active.  An active cfqg
241          * also activates its parent and contributes to the children_weight
242          * of the parent.
243          */
244         int nr_active;
245         unsigned int children_weight;
246 
247         /*
248          * vfraction is the fraction of vdisktime that the tasks in this
249          * cfqg are entitled to.  This is determined by compounding the
250          * ratios walking up from this cfqg to the root.
251          *
252          * It is in fixed point w/ CFQ_SERVICE_SHIFT and the sum of all
253          * vfractions on a service tree is approximately 1.  The sum may
254          * deviate a bit due to rounding errors and fluctuations caused by
255          * cfqgs entering and leaving the service tree.
256          */
257         unsigned int vfraction;
258 
259         /*
260          * There are two weights - (internal) weight is the weight of this
261          * cfqg against the sibling cfqgs.  leaf_weight is the wight of
262          * this cfqg against the child cfqgs.  For the root cfqg, both
263          * weights are kept in sync for backward compatibility.
264          */
265         unsigned int weight;
266         unsigned int new_weight;
267         unsigned int dev_weight;
268 
269         unsigned int leaf_weight;
270         unsigned int new_leaf_weight;
271         unsigned int dev_leaf_weight;
272 
273         /* number of cfqq currently on this group */
274         int nr_cfqq;
275 
276         /*
277          * Per group busy queues average. Useful for workload slice calc. We
278          * create the array for each prio class but at run time it is used
279          * only for RT and BE class and slot for IDLE class remains unused.
280          * This is primarily done to avoid confusion and a gcc warning.
281          */
282         unsigned int busy_queues_avg[CFQ_PRIO_NR];
283         /*
284          * rr lists of queues with requests. We maintain service trees for
285          * RT and BE classes. These trees are subdivided in subclasses
286          * of SYNC, SYNC_NOIDLE and ASYNC based on workload type. For IDLE
287          * class there is no subclassification and all the cfq queues go on
288          * a single tree service_tree_idle.
289          * Counts are embedded in the cfq_rb_root
290          */
291         struct cfq_rb_root service_trees[2][3];
292         struct cfq_rb_root service_tree_idle;
293 
294         u64 saved_wl_slice;
295         enum wl_type_t saved_wl_type;
296         enum wl_class_t saved_wl_class;
297 
298         /* number of requests that are on the dispatch list or inside driver */
299         int dispatched;
300         struct cfq_ttime ttime;
301         struct cfqg_stats stats;        /* stats for this cfqg */
302 
303         /* async queue for each priority case */
304         struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR];
305         struct cfq_queue *async_idle_cfqq;
306 
307 };
308 
309 struct cfq_io_cq {
310         struct io_cq            icq;            /* must be the first member */
311         struct cfq_queue        *cfqq[2];
312         struct cfq_ttime        ttime;
313         int                     ioprio;         /* the current ioprio */
314 #ifdef CONFIG_CFQ_GROUP_IOSCHED
315         uint64_t                blkcg_serial_nr; /* the current blkcg serial */
316 #endif
317 };
318 
319 /*
320  * Per block device queue structure
321  */
322 struct cfq_data {
323         struct request_queue *queue;
324         /* Root service tree for cfq_groups */
325         struct cfq_rb_root grp_service_tree;
326         struct cfq_group *root_group;
327 
328         /*
329          * The priority currently being served
330          */
331         enum wl_class_t serving_wl_class;
332         enum wl_type_t serving_wl_type;
333         u64 workload_expires;
334         struct cfq_group *serving_group;
335 
336         /*
337          * Each priority tree is sorted by next_request position.  These
338          * trees are used when determining if two or more queues are
339          * interleaving requests (see cfq_close_cooperator).
340          */
341         struct rb_root prio_trees[CFQ_PRIO_LISTS];
342 
343         unsigned int busy_queues;
344         unsigned int busy_sync_queues;
345 
346         int rq_in_driver;
347         int rq_in_flight[2];
348 
349         /*
350          * queue-depth detection
351          */
352         int rq_queued;
353         int hw_tag;
354         /*
355          * hw_tag can be
356          * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection)
357          *  1 => NCQ is present (hw_tag_est_depth is the estimated max depth)
358          *  0 => no NCQ
359          */
360         int hw_tag_est_depth;
361         unsigned int hw_tag_samples;
362 
363         /*
364          * idle window management
365          */
366         struct hrtimer idle_slice_timer;
367         struct work_struct unplug_work;
368 
369         struct cfq_queue *active_queue;
370         struct cfq_io_cq *active_cic;
371 
372         sector_t last_position;
373 
374         /*
375          * tunables, see top of file
376          */
377         unsigned int cfq_quantum;
378         unsigned int cfq_back_penalty;
379         unsigned int cfq_back_max;
380         unsigned int cfq_slice_async_rq;
381         unsigned int cfq_latency;
382         u64 cfq_fifo_expire[2];
383         u64 cfq_slice[2];
384         u64 cfq_slice_idle;
385         u64 cfq_group_idle;
386         u64 cfq_target_latency;
387 
388         /*
389          * Fallback dummy cfqq for extreme OOM conditions
390          */
391         struct cfq_queue oom_cfqq;
392 
393         u64 last_delayed_sync;
394 };
395 
396 static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd);
397 static void cfq_put_queue(struct cfq_queue *cfqq);
398 
399 static struct cfq_rb_root *st_for(struct cfq_group *cfqg,
400                                             enum wl_class_t class,
401                                             enum wl_type_t type)
402 {
403         if (!cfqg)
404                 return NULL;
405 
406         if (class == IDLE_WORKLOAD)
407                 return &cfqg->service_tree_idle;
408 
409         return &cfqg->service_trees[class][type];
410 }
411 
412 enum cfqq_state_flags {
413         CFQ_CFQQ_FLAG_on_rr = 0,        /* on round-robin busy list */
414         CFQ_CFQQ_FLAG_wait_request,     /* waiting for a request */
415         CFQ_CFQQ_FLAG_must_dispatch,    /* must be allowed a dispatch */
416         CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */
417         CFQ_CFQQ_FLAG_fifo_expire,      /* FIFO checked in this slice */
418         CFQ_CFQQ_FLAG_idle_window,      /* slice idling enabled */
419         CFQ_CFQQ_FLAG_prio_changed,     /* task priority has changed */
420         CFQ_CFQQ_FLAG_slice_new,        /* no requests dispatched in slice */
421         CFQ_CFQQ_FLAG_sync,             /* synchronous queue */
422         CFQ_CFQQ_FLAG_coop,             /* cfqq is shared */
423         CFQ_CFQQ_FLAG_split_coop,       /* shared cfqq will be splitted */
424         CFQ_CFQQ_FLAG_deep,             /* sync cfqq experienced large depth */
425         CFQ_CFQQ_FLAG_wait_busy,        /* Waiting for next request */
426 };
427 
428 #define CFQ_CFQQ_FNS(name)                                              \
429 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq)         \
430 {                                                                       \
431         (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name);                   \
432 }                                                                       \
433 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq)        \
434 {                                                                       \
435         (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name);                  \
436 }                                                                       \
437 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq)         \
438 {                                                                       \
439         return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0;      \
440 }
441 
442 CFQ_CFQQ_FNS(on_rr);
443 CFQ_CFQQ_FNS(wait_request);
444 CFQ_CFQQ_FNS(must_dispatch);
445 CFQ_CFQQ_FNS(must_alloc_slice);
446 CFQ_CFQQ_FNS(fifo_expire);
447 CFQ_CFQQ_FNS(idle_window);
448 CFQ_CFQQ_FNS(prio_changed);
449 CFQ_CFQQ_FNS(slice_new);
450 CFQ_CFQQ_FNS(sync);
451 CFQ_CFQQ_FNS(coop);
452 CFQ_CFQQ_FNS(split_coop);
453 CFQ_CFQQ_FNS(deep);
454 CFQ_CFQQ_FNS(wait_busy);
455 #undef CFQ_CFQQ_FNS
456 
457 #if defined(CONFIG_CFQ_GROUP_IOSCHED) && defined(CONFIG_DEBUG_BLK_CGROUP)
458 
459 /* cfqg stats flags */
460 enum cfqg_stats_flags {
461         CFQG_stats_waiting = 0,
462         CFQG_stats_idling,
463         CFQG_stats_empty,
464 };
465 
466 #define CFQG_FLAG_FNS(name)                                             \
467 static inline void cfqg_stats_mark_##name(struct cfqg_stats *stats)     \
468 {                                                                       \
469         stats->flags |= (1 << CFQG_stats_##name);                       \
470 }                                                                       \
471 static inline void cfqg_stats_clear_##name(struct cfqg_stats *stats)    \
472 {                                                                       \
473         stats->flags &= ~(1 << CFQG_stats_##name);                      \
474 }                                                                       \
475 static inline int cfqg_stats_##name(struct cfqg_stats *stats)           \
476 {                                                                       \
477         return (stats->flags & (1 << CFQG_stats_##name)) != 0;          \
478 }                                                                       \
479 
480 CFQG_FLAG_FNS(waiting)
481 CFQG_FLAG_FNS(idling)
482 CFQG_FLAG_FNS(empty)
483 #undef CFQG_FLAG_FNS
484 
485 /* This should be called with the queue_lock held. */
486 static void cfqg_stats_update_group_wait_time(struct cfqg_stats *stats)
487 {
488         unsigned long long now;
489 
490         if (!cfqg_stats_waiting(stats))
491                 return;
492 
493         now = sched_clock();
494         if (time_after64(now, stats->start_group_wait_time))
495                 blkg_stat_add(&stats->group_wait_time,
496                               now - stats->start_group_wait_time);
497         cfqg_stats_clear_waiting(stats);
498 }
499 
500 /* This should be called with the queue_lock held. */
501 static void cfqg_stats_set_start_group_wait_time(struct cfq_group *cfqg,
502                                                  struct cfq_group *curr_cfqg)
503 {
504         struct cfqg_stats *stats = &cfqg->stats;
505 
506         if (cfqg_stats_waiting(stats))
507                 return;
508         if (cfqg == curr_cfqg)
509                 return;
510         stats->start_group_wait_time = sched_clock();
511         cfqg_stats_mark_waiting(stats);
512 }
513 
514 /* This should be called with the queue_lock held. */
515 static void cfqg_stats_end_empty_time(struct cfqg_stats *stats)
516 {
517         unsigned long long now;
518 
519         if (!cfqg_stats_empty(stats))
520                 return;
521 
522         now = sched_clock();
523         if (time_after64(now, stats->start_empty_time))
524                 blkg_stat_add(&stats->empty_time,
525                               now - stats->start_empty_time);
526         cfqg_stats_clear_empty(stats);
527 }
528 
529 static void cfqg_stats_update_dequeue(struct cfq_group *cfqg)
530 {
531         blkg_stat_add(&cfqg->stats.dequeue, 1);
532 }
533 
534 static void cfqg_stats_set_start_empty_time(struct cfq_group *cfqg)
535 {
536         struct cfqg_stats *stats = &cfqg->stats;
537 
538         if (blkg_rwstat_total(&stats->queued))
539                 return;
540 
541         /*
542          * group is already marked empty. This can happen if cfqq got new
543          * request in parent group and moved to this group while being added
544          * to service tree. Just ignore the event and move on.
545          */
546         if (cfqg_stats_empty(stats))
547                 return;
548 
549         stats->start_empty_time = sched_clock();
550         cfqg_stats_mark_empty(stats);
551 }
552 
553 static void cfqg_stats_update_idle_time(struct cfq_group *cfqg)
554 {
555         struct cfqg_stats *stats = &cfqg->stats;
556 
557         if (cfqg_stats_idling(stats)) {
558                 unsigned long long now = sched_clock();
559 
560                 if (time_after64(now, stats->start_idle_time))
561                         blkg_stat_add(&stats->idle_time,
562                                       now - stats->start_idle_time);
563                 cfqg_stats_clear_idling(stats);
564         }
565 }
566 
567 static void cfqg_stats_set_start_idle_time(struct cfq_group *cfqg)
568 {
569         struct cfqg_stats *stats = &cfqg->stats;
570 
571         BUG_ON(cfqg_stats_idling(stats));
572 
573         stats->start_idle_time = sched_clock();
574         cfqg_stats_mark_idling(stats);
575 }
576 
577 static void cfqg_stats_update_avg_queue_size(struct cfq_group *cfqg)
578 {
579         struct cfqg_stats *stats = &cfqg->stats;
580 
581         blkg_stat_add(&stats->avg_queue_size_sum,
582                       blkg_rwstat_total(&stats->queued));
583         blkg_stat_add(&stats->avg_queue_size_samples, 1);
584         cfqg_stats_update_group_wait_time(stats);
585 }
586 
587 #else   /* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */
588 
589 static inline void cfqg_stats_set_start_group_wait_time(struct cfq_group *cfqg, struct cfq_group *curr_cfqg) { }
590 static inline void cfqg_stats_end_empty_time(struct cfqg_stats *stats) { }
591 static inline void cfqg_stats_update_dequeue(struct cfq_group *cfqg) { }
592 static inline void cfqg_stats_set_start_empty_time(struct cfq_group *cfqg) { }
593 static inline void cfqg_stats_update_idle_time(struct cfq_group *cfqg) { }
594 static inline void cfqg_stats_set_start_idle_time(struct cfq_group *cfqg) { }
595 static inline void cfqg_stats_update_avg_queue_size(struct cfq_group *cfqg) { }
596 
597 #endif  /* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */
598 
599 #ifdef CONFIG_CFQ_GROUP_IOSCHED
600 
601 static inline struct cfq_group *pd_to_cfqg(struct blkg_policy_data *pd)
602 {
603         return pd ? container_of(pd, struct cfq_group, pd) : NULL;
604 }
605 
606 static struct cfq_group_data
607 *cpd_to_cfqgd(struct blkcg_policy_data *cpd)
608 {
609         return cpd ? container_of(cpd, struct cfq_group_data, cpd) : NULL;
610 }
611 
612 static inline struct blkcg_gq *cfqg_to_blkg(struct cfq_group *cfqg)
613 {
614         return pd_to_blkg(&cfqg->pd);
615 }
616 
617 static struct blkcg_policy blkcg_policy_cfq;
618 
619 static inline struct cfq_group *blkg_to_cfqg(struct blkcg_gq *blkg)
620 {
621         return pd_to_cfqg(blkg_to_pd(blkg, &blkcg_policy_cfq));
622 }
623 
624 static struct cfq_group_data *blkcg_to_cfqgd(struct blkcg *blkcg)
625 {
626         return cpd_to_cfqgd(blkcg_to_cpd(blkcg, &blkcg_policy_cfq));
627 }
628 
629 static inline struct cfq_group *cfqg_parent(struct cfq_group *cfqg)
630 {
631         struct blkcg_gq *pblkg = cfqg_to_blkg(cfqg)->parent;
632 
633         return pblkg ? blkg_to_cfqg(pblkg) : NULL;
634 }
635 
636 static inline bool cfqg_is_descendant(struct cfq_group *cfqg,
637                                       struct cfq_group *ancestor)
638 {
639         return cgroup_is_descendant(cfqg_to_blkg(cfqg)->blkcg->css.cgroup,
640                                     cfqg_to_blkg(ancestor)->blkcg->css.cgroup);
641 }
642 
643 static inline void cfqg_get(struct cfq_group *cfqg)
644 {
645         return blkg_get(cfqg_to_blkg(cfqg));
646 }
647 
648 static inline void cfqg_put(struct cfq_group *cfqg)
649 {
650         return blkg_put(cfqg_to_blkg(cfqg));
651 }
652 
653 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...)  do {                    \
654         char __pbuf[128];                                               \
655                                                                         \
656         blkg_path(cfqg_to_blkg((cfqq)->cfqg), __pbuf, sizeof(__pbuf));  \
657         blk_add_trace_msg((cfqd)->queue, "cfq%d%c%c %s " fmt, (cfqq)->pid, \
658                         cfq_cfqq_sync((cfqq)) ? 'S' : 'A',              \
659                         cfqq_type((cfqq)) == SYNC_NOIDLE_WORKLOAD ? 'N' : ' ',\
660                           __pbuf, ##args);                              \
661 } while (0)
662 
663 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...)  do {                    \
664         char __pbuf[128];                                               \
665                                                                         \
666         blkg_path(cfqg_to_blkg(cfqg), __pbuf, sizeof(__pbuf));          \
667         blk_add_trace_msg((cfqd)->queue, "%s " fmt, __pbuf, ##args);    \
668 } while (0)
669 
670 static inline void cfqg_stats_update_io_add(struct cfq_group *cfqg,
671                                             struct cfq_group *curr_cfqg,
672                                             unsigned int op)
673 {
674         blkg_rwstat_add(&cfqg->stats.queued, op, 1);
675         cfqg_stats_end_empty_time(&cfqg->stats);
676         cfqg_stats_set_start_group_wait_time(cfqg, curr_cfqg);
677 }
678 
679 static inline void cfqg_stats_update_timeslice_used(struct cfq_group *cfqg,
680                         uint64_t time, unsigned long unaccounted_time)
681 {
682         blkg_stat_add(&cfqg->stats.time, time);
683 #ifdef CONFIG_DEBUG_BLK_CGROUP
684         blkg_stat_add(&cfqg->stats.unaccounted_time, unaccounted_time);
685 #endif
686 }
687 
688 static inline void cfqg_stats_update_io_remove(struct cfq_group *cfqg,
689                                                unsigned int op)
690 {
691         blkg_rwstat_add(&cfqg->stats.queued, op, -1);
692 }
693 
694 static inline void cfqg_stats_update_io_merged(struct cfq_group *cfqg,
695                                                unsigned int op)
696 {
697         blkg_rwstat_add(&cfqg->stats.merged, op, 1);
698 }
699 
700 static inline void cfqg_stats_update_completion(struct cfq_group *cfqg,
701                         uint64_t start_time, uint64_t io_start_time,
702                         unsigned int op)
703 {
704         struct cfqg_stats *stats = &cfqg->stats;
705         unsigned long long now = sched_clock();
706 
707         if (time_after64(now, io_start_time))
708                 blkg_rwstat_add(&stats->service_time, op, now - io_start_time);
709         if (time_after64(io_start_time, start_time))
710                 blkg_rwstat_add(&stats->wait_time, op,
711                                 io_start_time - start_time);
712 }
713 
714 /* @stats = 0 */
715 static 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 */
734 static 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  */
757 static 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 
772 static inline struct cfq_group *cfqg_parent(struct cfq_group *cfqg) { return NULL; }
773 static inline bool cfqg_is_descendant(struct cfq_group *cfqg,
774                                       struct cfq_group *ancestor)
775 {
776         return true;
777 }
778 static inline void cfqg_get(struct cfq_group *cfqg) { }
779 static 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 
788 static inline void cfqg_stats_update_io_add(struct cfq_group *cfqg,
789                         struct cfq_group *curr_cfqg, unsigned int op) { }
790 static inline void cfqg_stats_update_timeslice_used(struct cfq_group *cfqg,
791                         uint64_t time, unsigned long unaccounted_time) { }
792 static inline void cfqg_stats_update_io_remove(struct cfq_group *cfqg,
793                         unsigned int op) { }
794 static inline void cfqg_stats_update_io_merged(struct cfq_group *cfqg,
795                         unsigned int op) { }
796 static inline void cfqg_stats_update_completion(struct cfq_group *cfqg,
797                         uint64_t start_time, uint64_t io_start_time,
798                         unsigned int op) { }
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 
815 static 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 
828 static 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 
843 static 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 
853 static 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 
862 static 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 
874 static 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 
881 static void cfq_dispatch_insert(struct request_queue *, struct request *);
882 static struct cfq_queue *cfq_get_queue(struct cfq_data *cfqd, bool is_sync,
883                                        struct cfq_io_cq *cic, struct bio *bio);
884 
885 static 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 
891 static 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 
899 static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_cq *cic, bool is_sync)
900 {
901         return cic->cfqq[is_sync];
902 }
903 
904 static 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 
910 static 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  * scheduler run of queue, if there are requests pending and no one in the
917  * driver that will restart queueing
918  */
919 static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
920 {
921         if (cfqd->busy_queues) {
922                 cfq_log(cfqd, "schedule dispatch");
923                 kblockd_schedule_work(&cfqd->unplug_work);
924         }
925 }
926 
927 /*
928  * Scale schedule slice based on io priority. Use the sync time slice only
929  * if a queue is marked sync and has sync io queued. A sync queue with async
930  * io only, should not get full sync slice length.
931  */
932 static inline u64 cfq_prio_slice(struct cfq_data *cfqd, bool sync,
933                                  unsigned short prio)
934 {
935         u64 base_slice = cfqd->cfq_slice[sync];
936         u64 slice = div_u64(base_slice, CFQ_SLICE_SCALE);
937 
938         WARN_ON(prio >= IOPRIO_BE_NR);
939 
940         return base_slice + (slice * (4 - prio));
941 }
942 
943 static inline u64
944 cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
945 {
946         return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
947 }
948 
949 /**
950  * cfqg_scale_charge - scale disk time charge according to cfqg weight
951  * @charge: disk time being charged
952  * @vfraction: vfraction of the cfqg, fixed point w/ CFQ_SERVICE_SHIFT
953  *
954  * Scale @charge according to @vfraction, which is in range (0, 1].  The
955  * scaling is inversely proportional.
956  *
957  * scaled = charge / vfraction
958  *
959  * The result is also in fixed point w/ CFQ_SERVICE_SHIFT.
960  */
961 static inline u64 cfqg_scale_charge(u64 charge,
962                                     unsigned int vfraction)
963 {
964         u64 c = charge << CFQ_SERVICE_SHIFT;    /* make it fixed point */
965 
966         /* charge / vfraction */
967         c <<= CFQ_SERVICE_SHIFT;
968         return div_u64(c, vfraction);
969 }
970 
971 static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime)
972 {
973         s64 delta = (s64)(vdisktime - min_vdisktime);
974         if (delta > 0)
975                 min_vdisktime = vdisktime;
976 
977         return min_vdisktime;
978 }
979 
980 static inline u64 min_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 
989 static void update_min_vdisktime(struct cfq_rb_root *st)
990 {
991         struct cfq_group *cfqg;
992 
993         if (st->left) {
994                 cfqg = rb_entry_cfqg(st->left);
995                 st->min_vdisktime = max_vdisktime(st->min_vdisktime,
996                                                   cfqg->vdisktime);
997         }
998 }
999 
1000 /*
1001  * get averaged number of queues of RT/BE priority.
1002  * average is updated, with a formula that gives more weight to higher numbers,
1003  * to quickly follows sudden increases and decrease slowly
1004  */
1005 
1006 static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd,
1007                                         struct cfq_group *cfqg, bool rt)
1008 {
1009         unsigned min_q, max_q;
1010         unsigned mult  = cfq_hist_divisor - 1;
1011         unsigned round = cfq_hist_divisor / 2;
1012         unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg);
1013 
1014         min_q = min(cfqg->busy_queues_avg[rt], busy);
1015         max_q = max(cfqg->busy_queues_avg[rt], busy);
1016         cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) /
1017                 cfq_hist_divisor;
1018         return cfqg->busy_queues_avg[rt];
1019 }
1020 
1021 static inline u64
1022 cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg)
1023 {
1024         return cfqd->cfq_target_latency * cfqg->vfraction >> CFQ_SERVICE_SHIFT;
1025 }
1026 
1027 static inline u64
1028 cfq_scaled_cfqq_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1029 {
1030         u64 slice = cfq_prio_to_slice(cfqd, cfqq);
1031         if (cfqd->cfq_latency) {
1032                 /*
1033                  * interested queues (we consider only the ones with the same
1034                  * priority class in the cfq group)
1035                  */
1036                 unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg,
1037                                                 cfq_class_rt(cfqq));
1038                 u64 sync_slice = cfqd->cfq_slice[1];
1039                 u64 expect_latency = sync_slice * iq;
1040                 u64 group_slice = cfq_group_slice(cfqd, cfqq->cfqg);
1041 
1042                 if (expect_latency > group_slice) {
1043                         u64 base_low_slice = 2 * cfqd->cfq_slice_idle;
1044                         u64 low_slice;
1045 
1046                         /* scale low_slice according to IO priority
1047                          * and sync vs async */
1048                         low_slice = div64_u64(base_low_slice*slice, sync_slice);
1049                         low_slice = min(slice, low_slice);
1050                         /* the adapted slice value is scaled to fit all iqs
1051                          * into the target latency */
1052                         slice = div64_u64(slice*group_slice, expect_latency);
1053                         slice = max(slice, low_slice);
1054                 }
1055         }
1056         return slice;
1057 }
1058 
1059 static inline void
1060 cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1061 {
1062         u64 slice = cfq_scaled_cfqq_slice(cfqd, cfqq);
1063         u64 now = ktime_get_ns();
1064 
1065         cfqq->slice_start = now;
1066         cfqq->slice_end = now + slice;
1067         cfqq->allocated_slice = slice;
1068         cfq_log_cfqq(cfqd, cfqq, "set_slice=%llu", cfqq->slice_end - now);
1069 }
1070 
1071 /*
1072  * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
1073  * isn't valid until the first request from the dispatch is activated
1074  * and the slice time set.
1075  */
1076 static inline bool cfq_slice_used(struct cfq_queue *cfqq)
1077 {
1078         if (cfq_cfqq_slice_new(cfqq))
1079                 return false;
1080         if (ktime_get_ns() < cfqq->slice_end)
1081                 return false;
1082 
1083         return true;
1084 }
1085 
1086 /*
1087  * Lifted from AS - choose which of rq1 and rq2 that is best served now.
1088  * We choose the request that is closest to the head right now. Distance
1089  * behind the head is penalized and only allowed to a certain extent.
1090  */
1091 static struct request *
1092 cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last)
1093 {
1094         sector_t s1, s2, d1 = 0, d2 = 0;
1095         unsigned long back_max;
1096 #define CFQ_RQ1_WRAP    0x01 /* request 1 wraps */
1097 #define CFQ_RQ2_WRAP    0x02 /* request 2 wraps */
1098         unsigned wrap = 0; /* bit mask: requests behind the disk head? */
1099 
1100         if (rq1 == NULL || rq1 == rq2)
1101                 return rq2;
1102         if (rq2 == NULL)
1103                 return rq1;
1104 
1105         if (rq_is_sync(rq1) != rq_is_sync(rq2))
1106                 return rq_is_sync(rq1) ? rq1 : rq2;
1107 
1108         if ((rq1->cmd_flags ^ rq2->cmd_flags) & REQ_PRIO)
1109                 return rq1->cmd_flags & REQ_PRIO ? rq1 : rq2;
1110 
1111         s1 = blk_rq_pos(rq1);
1112         s2 = blk_rq_pos(rq2);
1113 
1114         /*
1115          * by definition, 1KiB is 2 sectors
1116          */
1117         back_max = cfqd->cfq_back_max * 2;
1118 
1119         /*
1120          * Strict one way elevator _except_ in the case where we allow
1121          * short backward seeks which are biased as twice the cost of a
1122          * similar forward seek.
1123          */
1124         if (s1 >= last)
1125                 d1 = s1 - last;
1126         else if (s1 + back_max >= last)
1127                 d1 = (last - s1) * cfqd->cfq_back_penalty;
1128         else
1129                 wrap |= CFQ_RQ1_WRAP;
1130 
1131         if (s2 >= last)
1132                 d2 = s2 - last;
1133         else if (s2 + back_max >= last)
1134                 d2 = (last - s2) * cfqd->cfq_back_penalty;
1135         else
1136                 wrap |= CFQ_RQ2_WRAP;
1137 
1138         /* Found required data */
1139 
1140         /*
1141          * By doing switch() on the bit mask "wrap" we avoid having to
1142          * check two variables for all permutations: --> faster!
1143          */
1144         switch (wrap) {
1145         case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
1146                 if (d1 < d2)
1147                         return rq1;
1148                 else if (d2 < d1)
1149                         return rq2;
1150                 else {
1151                         if (s1 >= s2)
1152                                 return rq1;
1153                         else
1154                                 return rq2;
1155                 }
1156 
1157         case CFQ_RQ2_WRAP:
1158                 return rq1;
1159         case CFQ_RQ1_WRAP:
1160                 return rq2;
1161         case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */
1162         default:
1163                 /*
1164                  * Since both rqs are wrapped,
1165                  * start with the one that's further behind head
1166                  * (--> only *one* back seek required),
1167                  * since back seek takes more time than forward.
1168                  */
1169                 if (s1 <= s2)
1170                         return rq1;
1171                 else
1172                         return rq2;
1173         }
1174 }
1175 
1176 /*
1177  * The below is leftmost cache rbtree addon
1178  */
1179 static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
1180 {
1181         /* Service tree is empty */
1182         if (!root->count)
1183                 return NULL;
1184 
1185         if (!root->left)
1186                 root->left = rb_first(&root->rb);
1187 
1188         if (root->left)
1189                 return rb_entry(root->left, struct cfq_queue, rb_node);
1190 
1191         return NULL;
1192 }
1193 
1194 static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root)
1195 {
1196         if (!root->left)
1197                 root->left = rb_first(&root->rb);
1198 
1199         if (root->left)
1200                 return rb_entry_cfqg(root->left);
1201 
1202         return NULL;
1203 }
1204 
1205 static void rb_erase_init(struct rb_node *n, struct rb_root *root)
1206 {
1207         rb_erase(n, root);
1208         RB_CLEAR_NODE(n);
1209 }
1210 
1211 static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)
1212 {
1213         if (root->left == n)
1214                 root->left = NULL;
1215         rb_erase_init(n, &root->rb);
1216         --root->count;
1217 }
1218 
1219 /*
1220  * would be nice to take fifo expire time into account as well
1221  */
1222 static struct request *
1223 cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1224                   struct request *last)
1225 {
1226         struct rb_node *rbnext = rb_next(&last->rb_node);
1227         struct rb_node *rbprev = rb_prev(&last->rb_node);
1228         struct request *next = NULL, *prev = NULL;
1229 
1230         BUG_ON(RB_EMPTY_NODE(&last->rb_node));
1231 
1232         if (rbprev)
1233                 prev = rb_entry_rq(rbprev);
1234 
1235         if (rbnext)
1236                 next = rb_entry_rq(rbnext);
1237         else {
1238                 rbnext = rb_first(&cfqq->sort_list);
1239                 if (rbnext && rbnext != &last->rb_node)
1240                         next = rb_entry_rq(rbnext);
1241         }
1242 
1243         return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last));
1244 }
1245 
1246 static u64 cfq_slice_offset(struct cfq_data *cfqd,
1247                             struct cfq_queue *cfqq)
1248 {
1249         /*
1250          * just an approximation, should be ok.
1251          */
1252         return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) -
1253                        cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio));
1254 }
1255 
1256 static inline s64
1257 cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg)
1258 {
1259         return cfqg->vdisktime - st->min_vdisktime;
1260 }
1261 
1262 static void
1263 __cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
1264 {
1265         struct rb_node **node = &st->rb.rb_node;
1266         struct rb_node *parent = NULL;
1267         struct cfq_group *__cfqg;
1268         s64 key = cfqg_key(st, cfqg);
1269         int left = 1;
1270 
1271         while (*node != NULL) {
1272                 parent = *node;
1273                 __cfqg = rb_entry_cfqg(parent);
1274 
1275                 if (key < cfqg_key(st, __cfqg))
1276                         node = &parent->rb_left;
1277                 else {
1278                         node = &parent->rb_right;
1279                         left = 0;
1280                 }
1281         }
1282 
1283         if (left)
1284                 st->left = &cfqg->rb_node;
1285 
1286         rb_link_node(&cfqg->rb_node, parent, node);
1287         rb_insert_color(&cfqg->rb_node, &st->rb);
1288 }
1289 
1290 /*
1291  * This has to be called only on activation of cfqg
1292  */
1293 static void
1294 cfq_update_group_weight(struct cfq_group *cfqg)
1295 {
1296         if (cfqg->new_weight) {
1297                 cfqg->weight = cfqg->new_weight;
1298                 cfqg->new_weight = 0;
1299         }
1300 }
1301 
1302 static void
1303 cfq_update_group_leaf_weight(struct cfq_group *cfqg)
1304 {
1305         BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
1306 
1307         if (cfqg->new_leaf_weight) {
1308                 cfqg->leaf_weight = cfqg->new_leaf_weight;
1309                 cfqg->new_leaf_weight = 0;
1310         }
1311 }
1312 
1313 static void
1314 cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
1315 {
1316         unsigned int vfr = 1 << CFQ_SERVICE_SHIFT;      /* start with 1 */
1317         struct cfq_group *pos = cfqg;
1318         struct cfq_group *parent;
1319         bool propagate;
1320 
1321         /* add to the service tree */
1322         BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
1323 
1324         /*
1325          * Update leaf_weight.  We cannot update weight at this point
1326          * because cfqg might already have been activated and is
1327          * contributing its current weight to the parent's child_weight.
1328          */
1329         cfq_update_group_leaf_weight(cfqg);
1330         __cfq_group_service_tree_add(st, cfqg);
1331 
1332         /*
1333          * Activate @cfqg and calculate the portion of vfraction @cfqg is
1334          * entitled to.  vfraction is calculated by walking the tree
1335          * towards the root calculating the fraction it has at each level.
1336          * The compounded ratio is how much vfraction @cfqg owns.
1337          *
1338          * Start with the proportion tasks in this cfqg has against active
1339          * children cfqgs - its leaf_weight against children_weight.
1340          */
1341         propagate = !pos->nr_active++;
1342         pos->children_weight += pos->leaf_weight;
1343         vfr = vfr * pos->leaf_weight / pos->children_weight;
1344 
1345         /*
1346          * Compound ->weight walking up the tree.  Both activation and
1347          * vfraction calculation are done in the same loop.  Propagation
1348          * stops once an already activated node is met.  vfraction
1349          * calculation should always continue to the root.
1350          */
1351         while ((parent = cfqg_parent(pos))) {
1352                 if (propagate) {
1353                         cfq_update_group_weight(pos);
1354                         propagate = !parent->nr_active++;
1355                         parent->children_weight += pos->weight;
1356                 }
1357                 vfr = vfr * pos->weight / parent->children_weight;
1358                 pos = parent;
1359         }
1360 
1361         cfqg->vfraction = max_t(unsigned, vfr, 1);
1362 }
1363 
1364 static void
1365 cfq_group_notify_queue_add(struct cfq_data *cfqd, struct cfq_group *cfqg)
1366 {
1367         struct cfq_rb_root *st = &cfqd->grp_service_tree;
1368         struct cfq_group *__cfqg;
1369         struct rb_node *n;
1370 
1371         cfqg->nr_cfqq++;
1372         if (!RB_EMPTY_NODE(&cfqg->rb_node))
1373                 return;
1374 
1375         /*
1376          * Currently put the group at the end. Later implement something
1377          * so that groups get lesser vtime based on their weights, so that
1378          * if group does not loose all if it was not continuously backlogged.
1379          */
1380         n = rb_last(&st->rb);
1381         if (n) {
1382                 __cfqg = rb_entry_cfqg(n);
1383                 cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY;
1384         } else
1385                 cfqg->vdisktime = st->min_vdisktime;
1386         cfq_group_service_tree_add(st, cfqg);
1387 }
1388 
1389 static void
1390 cfq_group_service_tree_del(struct cfq_rb_root *st, struct cfq_group *cfqg)
1391 {
1392         struct cfq_group *pos = cfqg;
1393         bool propagate;
1394 
1395         /*
1396          * Undo activation from cfq_group_service_tree_add().  Deactivate
1397          * @cfqg and propagate deactivation upwards.
1398          */
1399         propagate = !--pos->nr_active;
1400         pos->children_weight -= pos->leaf_weight;
1401 
1402         while (propagate) {
1403                 struct cfq_group *parent = cfqg_parent(pos);
1404 
1405                 /* @pos has 0 nr_active at this point */
1406                 WARN_ON_ONCE(pos->children_weight);
1407                 pos->vfraction = 0;
1408 
1409                 if (!parent)
1410                         break;
1411 
1412                 propagate = !--parent->nr_active;
1413                 parent->children_weight -= pos->weight;
1414                 pos = parent;
1415         }
1416 
1417         /* remove from the service tree */
1418         if (!RB_EMPTY_NODE(&cfqg->rb_node))
1419                 cfq_rb_erase(&cfqg->rb_node, st);
1420 }
1421 
1422 static void
1423 cfq_group_notify_queue_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
1424 {
1425         struct cfq_rb_root *st = &cfqd->grp_service_tree;
1426 
1427         BUG_ON(cfqg->nr_cfqq < 1);
1428         cfqg->nr_cfqq--;
1429 
1430         /* If there are other cfq queues under this group, don't delete it */
1431         if (cfqg->nr_cfqq)
1432                 return;
1433 
1434         cfq_log_cfqg(cfqd, cfqg, "del_from_rr group");
1435         cfq_group_service_tree_del(st, cfqg);
1436         cfqg->saved_wl_slice = 0;
1437         cfqg_stats_update_dequeue(cfqg);
1438 }
1439 
1440 static inline u64 cfq_cfqq_slice_usage(struct cfq_queue *cfqq,
1441                                        u64 *unaccounted_time)
1442 {
1443         u64 slice_used;
1444         u64 now = ktime_get_ns();
1445 
1446         /*
1447          * Queue got expired before even a single request completed or
1448          * got expired immediately after first request completion.
1449          */
1450         if (!cfqq->slice_start || cfqq->slice_start == now) {
1451                 /*
1452                  * Also charge the seek time incurred to the group, otherwise
1453                  * if there are mutiple queues in the group, each can dispatch
1454                  * a single request on seeky media and cause lots of seek time
1455                  * and group will never know it.
1456                  */
1457                 slice_used = max_t(u64, (now - cfqq->dispatch_start),
1458                                         jiffies_to_nsecs(1));
1459         } else {
1460                 slice_used = now - cfqq->slice_start;
1461                 if (slice_used > cfqq->allocated_slice) {
1462                         *unaccounted_time = slice_used - cfqq->allocated_slice;
1463                         slice_used = cfqq->allocated_slice;
1464                 }
1465                 if (cfqq->slice_start > cfqq->dispatch_start)
1466                         *unaccounted_time += cfqq->slice_start -
1467                                         cfqq->dispatch_start;
1468         }
1469 
1470         return slice_used;
1471 }
1472 
1473 static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
1474                                 struct cfq_queue *cfqq)
1475 {
1476         struct cfq_rb_root *st = &cfqd->grp_service_tree;
1477         u64 used_sl, charge, unaccounted_sl = 0;
1478         int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg)
1479                         - cfqg->service_tree_idle.count;
1480         unsigned int vfr;
1481         u64 now = ktime_get_ns();
1482 
1483         BUG_ON(nr_sync < 0);
1484         used_sl = charge = cfq_cfqq_slice_usage(cfqq, &unaccounted_sl);
1485 
1486         if (iops_mode(cfqd))
1487                 charge = cfqq->slice_dispatch;
1488         else if (!cfq_cfqq_sync(cfqq) && !nr_sync)
1489                 charge = cfqq->allocated_slice;
1490 
1491         /*
1492          * Can't update vdisktime while on service tree and cfqg->vfraction
1493          * is valid only while on it.  Cache vfr, leave the service tree,
1494          * update vdisktime and go back on.  The re-addition to the tree
1495          * will also update the weights as necessary.
1496          */
1497         vfr = cfqg->vfraction;
1498         cfq_group_service_tree_del(st, cfqg);
1499         cfqg->vdisktime += cfqg_scale_charge(charge, vfr);
1500         cfq_group_service_tree_add(st, cfqg);
1501 
1502         /* This group is being expired. Save the context */
1503         if (cfqd->workload_expires > now) {
1504                 cfqg->saved_wl_slice = cfqd->workload_expires - now;
1505                 cfqg->saved_wl_type = cfqd->serving_wl_type;
1506                 cfqg->saved_wl_class = cfqd->serving_wl_class;
1507         } else
1508                 cfqg->saved_wl_slice = 0;
1509 
1510         cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime,
1511                                         st->min_vdisktime);
1512         cfq_log_cfqq(cfqq->cfqd, cfqq,
1513                      "sl_used=%llu disp=%llu charge=%llu iops=%u sect=%lu",
1514                      used_sl, cfqq->slice_dispatch, charge,
1515                      iops_mode(cfqd), cfqq->nr_sectors);
1516         cfqg_stats_update_timeslice_used(cfqg, used_sl, unaccounted_sl);
1517         cfqg_stats_set_start_empty_time(cfqg);
1518 }
1519 
1520 /**
1521  * cfq_init_cfqg_base - initialize base part of a cfq_group
1522  * @cfqg: cfq_group to initialize
1523  *
1524  * Initialize the base part which is used whether %CONFIG_CFQ_GROUP_IOSCHED
1525  * is enabled or not.
1526  */
1527 static void cfq_init_cfqg_base(struct cfq_group *cfqg)
1528 {
1529         struct cfq_rb_root *st;
1530         int i, j;
1531 
1532         for_each_cfqg_st(cfqg, i, j, st)
1533                 *st = CFQ_RB_ROOT;
1534         RB_CLEAR_NODE(&cfqg->rb_node);
1535 
1536         cfqg->ttime.last_end_request = ktime_get_ns();
1537 }
1538 
1539 #ifdef CONFIG_CFQ_GROUP_IOSCHED
1540 static int __cfq_set_weight(struct cgroup_subsys_state *css, u64 val,
1541                             bool on_dfl, bool reset_dev, bool is_leaf_weight);
1542 
1543 static void cfqg_stats_exit(struct cfqg_stats *stats)
1544 {
1545         blkg_rwstat_exit(&stats->merged);
1546         blkg_rwstat_exit(&stats->service_time);
1547         blkg_rwstat_exit(&stats->wait_time);
1548         blkg_rwstat_exit(&stats->queued);
1549         blkg_stat_exit(&stats->time);
1550 #ifdef CONFIG_DEBUG_BLK_CGROUP
1551         blkg_stat_exit(&stats->unaccounted_time);
1552         blkg_stat_exit(&stats->avg_queue_size_sum);
1553         blkg_stat_exit(&stats->avg_queue_size_samples);
1554         blkg_stat_exit(&stats->dequeue);
1555         blkg_stat_exit(&stats->group_wait_time);
1556         blkg_stat_exit(&stats->idle_time);
1557         blkg_stat_exit(&stats->empty_time);
1558 #endif
1559 }
1560 
1561 static int cfqg_stats_init(struct cfqg_stats *stats, gfp_t gfp)
1562 {
1563         if (blkg_rwstat_init(&stats->merged, gfp) ||
1564             blkg_rwstat_init(&stats->service_time, gfp) ||
1565             blkg_rwstat_init(&stats->wait_time, gfp) ||
1566             blkg_rwstat_init(&stats->queued, gfp) ||
1567             blkg_stat_init(&stats->time, gfp))
1568                 goto err;
1569 
1570 #ifdef CONFIG_DEBUG_BLK_CGROUP
1571         if (blkg_stat_init(&stats->unaccounted_time, gfp) ||
1572             blkg_stat_init(&stats->avg_queue_size_sum, gfp) ||
1573             blkg_stat_init(&stats->avg_queue_size_samples, gfp) ||
1574             blkg_stat_init(&stats->dequeue, gfp) ||
1575             blkg_stat_init(&stats->group_wait_time, gfp) ||
1576             blkg_stat_init(&stats->idle_time, gfp) ||
1577             blkg_stat_init(&stats->empty_time, gfp))
1578                 goto err;
1579 #endif
1580         return 0;
1581 err:
1582         cfqg_stats_exit(stats);
1583         return -ENOMEM;
1584 }
1585 
1586 static struct blkcg_policy_data *cfq_cpd_alloc(gfp_t gfp)
1587 {
1588         struct cfq_group_data *cgd;
1589 
1590         cgd = kzalloc(sizeof(*cgd), gfp);
1591         if (!cgd)
1592                 return NULL;
1593         return &cgd->cpd;
1594 }
1595 
1596 static void cfq_cpd_init(struct blkcg_policy_data *cpd)
1597 {
1598         struct cfq_group_data *cgd = cpd_to_cfqgd(cpd);
1599         unsigned int weight = cgroup_subsys_on_dfl(io_cgrp_subsys) ?
1600                               CGROUP_WEIGHT_DFL : CFQ_WEIGHT_LEGACY_DFL;
1601 
1602         if (cpd_to_blkcg(cpd) == &blkcg_root)
1603                 weight *= 2;
1604 
1605         cgd->weight = weight;
1606         cgd->leaf_weight = weight;
1607 }
1608 
1609 static void cfq_cpd_free(struct blkcg_policy_data *cpd)
1610 {
1611         kfree(cpd_to_cfqgd(cpd));
1612 }
1613 
1614 static void cfq_cpd_bind(struct blkcg_policy_data *cpd)
1615 {
1616         struct blkcg *blkcg = cpd_to_blkcg(cpd);
1617         bool on_dfl = cgroup_subsys_on_dfl(io_cgrp_subsys);
1618         unsigned int weight = on_dfl ? CGROUP_WEIGHT_DFL : CFQ_WEIGHT_LEGACY_DFL;
1619 
1620         if (blkcg == &blkcg_root)
1621                 weight *= 2;
1622 
1623         WARN_ON_ONCE(__cfq_set_weight(&blkcg->css, weight, on_dfl, true, false));
1624         WARN_ON_ONCE(__cfq_set_weight(&blkcg->css, weight, on_dfl, true, true));
1625 }
1626 
1627 static struct blkg_policy_data *cfq_pd_alloc(gfp_t gfp, int node)
1628 {
1629         struct cfq_group *cfqg;
1630 
1631         cfqg = kzalloc_node(sizeof(*cfqg), gfp, node);
1632         if (!cfqg)
1633                 return NULL;
1634 
1635         cfq_init_cfqg_base(cfqg);
1636         if (cfqg_stats_init(&cfqg->stats, gfp)) {
1637                 kfree(cfqg);
1638                 return NULL;
1639         }
1640 
1641         return &cfqg->pd;
1642 }
1643 
1644 static void cfq_pd_init(struct blkg_policy_data *pd)
1645 {
1646         struct cfq_group *cfqg = pd_to_cfqg(pd);
1647         struct cfq_group_data *cgd = blkcg_to_cfqgd(pd->blkg->blkcg);
1648 
1649         cfqg->weight = cgd->weight;
1650         cfqg->leaf_weight = cgd->leaf_weight;
1651 }
1652 
1653 static void cfq_pd_offline(struct blkg_policy_data *pd)
1654 {
1655         struct cfq_group *cfqg = pd_to_cfqg(pd);
1656         int i;
1657 
1658         for (i = 0; i < IOPRIO_BE_NR; i++) {
1659                 if (cfqg->async_cfqq[0][i])
1660                         cfq_put_queue(cfqg->async_cfqq[0][i]);
1661                 if (cfqg->async_cfqq[1][i])
1662                         cfq_put_queue(cfqg->async_cfqq[1][i]);
1663         }
1664 
1665         if (cfqg->async_idle_cfqq)
1666                 cfq_put_queue(cfqg->async_idle_cfqq);
1667 
1668         /*
1669          * @blkg is going offline and will be ignored by
1670          * blkg_[rw]stat_recursive_sum().  Transfer stats to the parent so
1671          * that they don't get lost.  If IOs complete after this point, the
1672          * stats for them will be lost.  Oh well...
1673          */
1674         cfqg_stats_xfer_dead(cfqg);
1675 }
1676 
1677 static void cfq_pd_free(struct blkg_policy_data *pd)
1678 {
1679         struct cfq_group *cfqg = pd_to_cfqg(pd);
1680 
1681         cfqg_stats_exit(&cfqg->stats);
1682         return kfree(cfqg);
1683 }
1684 
1685 static void cfq_pd_reset_stats(struct blkg_policy_data *pd)
1686 {
1687         struct cfq_group *cfqg = pd_to_cfqg(pd);
1688 
1689         cfqg_stats_reset(&cfqg->stats);
1690 }
1691 
1692 static struct cfq_group *cfq_lookup_cfqg(struct cfq_data *cfqd,
1693                                          struct blkcg *blkcg)
1694 {
1695         struct blkcg_gq *blkg;
1696 
1697         blkg = blkg_lookup(blkcg, cfqd->queue);
1698         if (likely(blkg))
1699                 return blkg_to_cfqg(blkg);
1700         return NULL;
1701 }
1702 
1703 static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg)
1704 {
1705         cfqq->cfqg = cfqg;
1706         /* cfqq reference on cfqg */
1707         cfqg_get(cfqg);
1708 }
1709 
1710 static u64 cfqg_prfill_weight_device(struct seq_file *sf,
1711                                      struct blkg_policy_data *pd, int off)
1712 {
1713         struct cfq_group *cfqg = pd_to_cfqg(pd);
1714 
1715         if (!cfqg->dev_weight)
1716                 return 0;
1717         return __blkg_prfill_u64(sf, pd, cfqg->dev_weight);
1718 }
1719 
1720 static int cfqg_print_weight_device(struct seq_file *sf, void *v)
1721 {
1722         blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1723                           cfqg_prfill_weight_device, &blkcg_policy_cfq,
1724                           0, false);
1725         return 0;
1726 }
1727 
1728 static u64 cfqg_prfill_leaf_weight_device(struct seq_file *sf,
1729                                           struct blkg_policy_data *pd, int off)
1730 {
1731         struct cfq_group *cfqg = pd_to_cfqg(pd);
1732 
1733         if (!cfqg->dev_leaf_weight)
1734                 return 0;
1735         return __blkg_prfill_u64(sf, pd, cfqg->dev_leaf_weight);
1736 }
1737 
1738 static int cfqg_print_leaf_weight_device(struct seq_file *sf, void *v)
1739 {
1740         blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1741                           cfqg_prfill_leaf_weight_device, &blkcg_policy_cfq,
1742                           0, false);
1743         return 0;
1744 }
1745 
1746 static int cfq_print_weight(struct seq_file *sf, void *v)
1747 {
1748         struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
1749         struct cfq_group_data *cgd = blkcg_to_cfqgd(blkcg);
1750         unsigned int val = 0;
1751 
1752         if (cgd)
1753                 val = cgd->weight;
1754 
1755         seq_printf(sf, "%u\n", val);
1756         return 0;
1757 }
1758 
1759 static int cfq_print_leaf_weight(struct seq_file *sf, void *v)
1760 {
1761         struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
1762         struct cfq_group_data *cgd = blkcg_to_cfqgd(blkcg);
1763         unsigned int val = 0;
1764 
1765         if (cgd)
1766                 val = cgd->leaf_weight;
1767 
1768         seq_printf(sf, "%u\n", val);
1769         return 0;
1770 }
1771 
1772 static ssize_t __cfqg_set_weight_device(struct kernfs_open_file *of,
1773                                         char *buf, size_t nbytes, loff_t off,
1774                                         bool on_dfl, bool is_leaf_weight)
1775 {
1776         unsigned int min = on_dfl ? CGROUP_WEIGHT_MIN : CFQ_WEIGHT_LEGACY_MIN;
1777         unsigned int max = on_dfl ? CGROUP_WEIGHT_MAX : CFQ_WEIGHT_LEGACY_MAX;
1778         struct blkcg *blkcg = css_to_blkcg(of_css(of));
1779         struct blkg_conf_ctx ctx;
1780         struct cfq_group *cfqg;
1781         struct cfq_group_data *cfqgd;
1782         int ret;
1783         u64 v;
1784 
1785         ret = blkg_conf_prep(blkcg, &blkcg_policy_cfq, buf, &ctx);
1786         if (ret)
1787                 return ret;
1788 
1789         if (sscanf(ctx.body, "%llu", &v) == 1) {
1790                 /* require "default" on dfl */
1791                 ret = -ERANGE;
1792                 if (!v && on_dfl)
1793                         goto out_finish;
1794         } else if (!strcmp(strim(ctx.body), "default")) {
1795                 v = 0;
1796         } else {
1797                 ret = -EINVAL;
1798                 goto out_finish;
1799         }
1800 
1801         cfqg = blkg_to_cfqg(ctx.blkg);
1802         cfqgd = blkcg_to_cfqgd(blkcg);
1803 
1804         ret = -ERANGE;
1805         if (!v || (v >= min && v <= max)) {
1806                 if (!is_leaf_weight) {
1807                         cfqg->dev_weight = v;
1808                         cfqg->new_weight = v ?: cfqgd->weight;
1809                 } else {
1810                         cfqg->dev_leaf_weight = v;
1811                         cfqg->new_leaf_weight = v ?: cfqgd->leaf_weight;
1812                 }
1813                 ret = 0;
1814         }
1815 out_finish:
1816         blkg_conf_finish(&ctx);
1817         return ret ?: nbytes;
1818 }
1819 
1820 static ssize_t cfqg_set_weight_device(struct kernfs_open_file *of,
1821                                       char *buf, size_t nbytes, loff_t off)
1822 {
1823         return __cfqg_set_weight_device(of, buf, nbytes, off, false, false);
1824 }
1825 
1826 static ssize_t cfqg_set_leaf_weight_device(struct kernfs_open_file *of,
1827                                            char *buf, size_t nbytes, loff_t off)
1828 {
1829         return __cfqg_set_weight_device(of, buf, nbytes, off, false, true);
1830 }
1831 
1832 static int __cfq_set_weight(struct cgroup_subsys_state *css, u64 val,
1833                             bool on_dfl, bool reset_dev, bool is_leaf_weight)
1834 {
1835         unsigned int min = on_dfl ? CGROUP_WEIGHT_MIN : CFQ_WEIGHT_LEGACY_MIN;
1836         unsigned int max = on_dfl ? CGROUP_WEIGHT_MAX : CFQ_WEIGHT_LEGACY_MAX;
1837         struct blkcg *blkcg = css_to_blkcg(css);
1838         struct blkcg_gq *blkg;
1839         struct cfq_group_data *cfqgd;
1840         int ret = 0;
1841 
1842         if (val < min || val > max)
1843                 return -ERANGE;
1844 
1845         spin_lock_irq(&blkcg->lock);
1846         cfqgd = blkcg_to_cfqgd(blkcg);
1847         if (!cfqgd) {
1848                 ret = -EINVAL;
1849                 goto out;
1850         }
1851 
1852         if (!is_leaf_weight)
1853                 cfqgd->weight = val;
1854         else
1855                 cfqgd->leaf_weight = val;
1856 
1857         hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) {
1858                 struct cfq_group *cfqg = blkg_to_cfqg(blkg);
1859 
1860                 if (!cfqg)
1861                         continue;
1862 
1863                 if (!is_leaf_weight) {
1864                         if (reset_dev)
1865                                 cfqg->dev_weight = 0;
1866                         if (!cfqg->dev_weight)
1867                                 cfqg->new_weight = cfqgd->weight;
1868                 } else {
1869                         if (reset_dev)
1870                                 cfqg->dev_leaf_weight = 0;
1871                         if (!cfqg->dev_leaf_weight)
1872                                 cfqg->new_leaf_weight = cfqgd->leaf_weight;
1873                 }
1874         }
1875 
1876 out:
1877         spin_unlock_irq(&blkcg->lock);
1878         return ret;
1879 }
1880 
1881 static int cfq_set_weight(struct cgroup_subsys_state *css, struct cftype *cft,
1882                           u64 val)
1883 {
1884         return __cfq_set_weight(css, val, false, false, false);
1885 }
1886 
1887 static int cfq_set_leaf_weight(struct cgroup_subsys_state *css,
1888                                struct cftype *cft, u64 val)
1889 {
1890         return __cfq_set_weight(css, val, false, false, true);
1891 }
1892 
1893 static int cfqg_print_stat(struct seq_file *sf, void *v)
1894 {
1895         blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_stat,
1896                           &blkcg_policy_cfq, seq_cft(sf)->private, false);
1897         return 0;
1898 }
1899 
1900 static int cfqg_print_rwstat(struct seq_file *sf, void *v)
1901 {
1902         blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_rwstat,
1903                           &blkcg_policy_cfq, seq_cft(sf)->private, true);
1904         return 0;
1905 }
1906 
1907 static u64 cfqg_prfill_stat_recursive(struct seq_file *sf,
1908                                       struct blkg_policy_data *pd, int off)
1909 {
1910         u64 sum = blkg_stat_recursive_sum(pd_to_blkg(pd),
1911                                           &blkcg_policy_cfq, off);
1912         return __blkg_prfill_u64(sf, pd, sum);
1913 }
1914 
1915 static u64 cfqg_prfill_rwstat_recursive(struct seq_file *sf,
1916                                         struct blkg_policy_data *pd, int off)
1917 {
1918         struct blkg_rwstat sum = blkg_rwstat_recursive_sum(pd_to_blkg(pd),
1919                                                         &blkcg_policy_cfq, off);
1920         return __blkg_prfill_rwstat(sf, pd, &sum);
1921 }
1922 
1923 static int cfqg_print_stat_recursive(struct seq_file *sf, void *v)
1924 {
1925         blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1926                           cfqg_prfill_stat_recursive, &blkcg_policy_cfq,
1927                           seq_cft(sf)->private, false);
1928         return 0;
1929 }
1930 
1931 static int cfqg_print_rwstat_recursive(struct seq_file *sf, void *v)
1932 {
1933         blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1934                           cfqg_prfill_rwstat_recursive, &blkcg_policy_cfq,
1935                           seq_cft(sf)->private, true);
1936         return 0;
1937 }
1938 
1939 static u64 cfqg_prfill_sectors(struct seq_file *sf, struct blkg_policy_data *pd,
1940                                int off)
1941 {
1942         u64 sum = blkg_rwstat_total(&pd->blkg->stat_bytes);
1943 
1944         return __blkg_prfill_u64(sf, pd, sum >> 9);
1945 }
1946 
1947 static int cfqg_print_stat_sectors(struct seq_file *sf, void *v)
1948 {
1949         blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1950                           cfqg_prfill_sectors, &blkcg_policy_cfq, 0, false);
1951         return 0;
1952 }
1953 
1954 static u64 cfqg_prfill_sectors_recursive(struct seq_file *sf,
1955                                          struct blkg_policy_data *pd, int off)
1956 {
1957         struct blkg_rwstat tmp = blkg_rwstat_recursive_sum(pd->blkg, NULL,
1958                                         offsetof(struct blkcg_gq, stat_bytes));
1959         u64 sum = atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_READ]) +
1960                 atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_WRITE]);
1961 
1962         return __blkg_prfill_u64(sf, pd, sum >> 9);
1963 }
1964 
1965 static int cfqg_print_stat_sectors_recursive(struct seq_file *sf, void *v)
1966 {
1967         blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1968                           cfqg_prfill_sectors_recursive, &blkcg_policy_cfq, 0,
1969                           false);
1970         return 0;
1971 }
1972 
1973 #ifdef CONFIG_DEBUG_BLK_CGROUP
1974 static u64 cfqg_prfill_avg_queue_size(struct seq_file *sf,
1975                                       struct blkg_policy_data *pd, int off)
1976 {
1977         struct cfq_group *cfqg = pd_to_cfqg(pd);
1978         u64 samples = blkg_stat_read(&cfqg->stats.avg_queue_size_samples);
1979         u64 v = 0;
1980 
1981         if (samples) {
1982                 v = blkg_stat_read(&cfqg->stats.avg_queue_size_sum);
1983                 v = div64_u64(v, samples);
1984         }
1985         __blkg_prfill_u64(sf, pd, v);
1986         return 0;
1987 }
1988 
1989 /* print avg_queue_size */
1990 static int cfqg_print_avg_queue_size(struct seq_file *sf, void *v)
1991 {
1992         blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1993                           cfqg_prfill_avg_queue_size, &blkcg_policy_cfq,
1994                           0, false);
1995         return 0;
1996 }
1997 #endif  /* CONFIG_DEBUG_BLK_CGROUP */
1998 
1999 static struct cftype cfq_blkcg_legacy_files[] = {
2000         /* on root, weight is mapped to leaf_weight */
2001         {
2002                 .name = "weight_device",
2003                 .flags = CFTYPE_ONLY_ON_ROOT,
2004                 .seq_show = cfqg_print_leaf_weight_device,
2005                 .write = cfqg_set_leaf_weight_device,
2006         },
2007         {
2008                 .name = "weight",
2009                 .flags = CFTYPE_ONLY_ON_ROOT,
2010                 .seq_show = cfq_print_leaf_weight,
2011                 .write_u64 = cfq_set_leaf_weight,
2012         },
2013 
2014         /* no such mapping necessary for !roots */
2015         {
2016                 .name = "weight_device",
2017                 .flags = CFTYPE_NOT_ON_ROOT,
2018                 .seq_show = cfqg_print_weight_device,
2019                 .write = cfqg_set_weight_device,
2020         },
2021         {
2022                 .name = "weight",
2023                 .flags = CFTYPE_NOT_ON_ROOT,
2024                 .seq_show = cfq_print_weight,
2025                 .write_u64 = cfq_set_weight,
2026         },
2027 
2028         {
2029                 .name = "leaf_weight_device",
2030                 .seq_show = cfqg_print_leaf_weight_device,
2031                 .write = cfqg_set_leaf_weight_device,
2032         },
2033         {
2034                 .name = "leaf_weight",
2035                 .seq_show = cfq_print_leaf_weight,
2036                 .write_u64 = cfq_set_leaf_weight,
2037         },
2038 
2039         /* statistics, covers only the tasks in the cfqg */
2040         {
2041                 .name = "time",
2042                 .private = offsetof(struct cfq_group, stats.time),
2043                 .seq_show = cfqg_print_stat,
2044         },
2045         {
2046                 .name = "sectors",
2047                 .seq_show = cfqg_print_stat_sectors,
2048         },
2049         {
2050                 .name = "io_service_bytes",
2051                 .private = (unsigned long)&blkcg_policy_cfq,
2052                 .seq_show = blkg_print_stat_bytes,
2053         },
2054         {
2055                 .name = "io_serviced",
2056                 .private = (unsigned long)&blkcg_policy_cfq,
2057                 .seq_show = blkg_print_stat_ios,
2058         },
2059         {
2060                 .name = "io_service_time",
2061                 .private = offsetof(struct cfq_group, stats.service_time),
2062                 .seq_show = cfqg_print_rwstat,
2063         },
2064         {
2065                 .name = "io_wait_time",
2066                 .private = offsetof(struct cfq_group, stats.wait_time),
2067                 .seq_show = cfqg_print_rwstat,
2068         },
2069         {
2070                 .name = "io_merged",
2071                 .private = offsetof(struct cfq_group, stats.merged),
2072                 .seq_show = cfqg_print_rwstat,
2073         },
2074         {
2075                 .name = "io_queued",
2076                 .private = offsetof(struct cfq_group, stats.queued),
2077                 .seq_show = cfqg_print_rwstat,
2078         },
2079 
2080         /* the same statictics which cover the cfqg and its descendants */
2081         {
2082                 .name = "time_recursive",
2083                 .private = offsetof(struct cfq_group, stats.time),
2084                 .seq_show = cfqg_print_stat_recursive,
2085         },
2086         {
2087                 .name = "sectors_recursive",
2088                 .seq_show = cfqg_print_stat_sectors_recursive,
2089         },
2090         {
2091                 .name = "io_service_bytes_recursive",
2092                 .private = (unsigned long)&blkcg_policy_cfq,
2093                 .seq_show = blkg_print_stat_bytes_recursive,
2094         },
2095         {
2096                 .name = "io_serviced_recursive",
2097                 .private = (unsigned long)&blkcg_policy_cfq,
2098                 .seq_show = blkg_print_stat_ios_recursive,
2099         },
2100         {
2101                 .name = "io_service_time_recursive",
2102                 .private = offsetof(struct cfq_group, stats.service_time),
2103                 .seq_show = cfqg_print_rwstat_recursive,
2104         },
2105         {
2106                 .name = "io_wait_time_recursive",
2107                 .private = offsetof(struct cfq_group, stats.wait_time),
2108                 .seq_show = cfqg_print_rwstat_recursive,
2109         },
2110         {
2111                 .name = "io_merged_recursive",
2112                 .private = offsetof(struct cfq_group, stats.merged),
2113                 .seq_show = cfqg_print_rwstat_recursive,
2114         },
2115         {
2116                 .name = "io_queued_recursive",
2117                 .private = offsetof(struct cfq_group, stats.queued),
2118                 .seq_show = cfqg_print_rwstat_recursive,
2119         },
2120 #ifdef CONFIG_DEBUG_BLK_CGROUP
2121         {
2122                 .name = "avg_queue_size",
2123                 .seq_show = cfqg_print_avg_queue_size,
2124         },
2125         {
2126                 .name = "group_wait_time",
2127                 .private = offsetof(struct cfq_group, stats.group_wait_time),
2128                 .seq_show = cfqg_print_stat,
2129         },
2130         {
2131                 .name = "idle_time",
2132                 .private = offsetof(struct cfq_group, stats.idle_time),
2133                 .seq_show = cfqg_print_stat,
2134         },
2135         {
2136                 .name = "empty_time",
2137                 .private = offsetof(struct cfq_group, stats.empty_time),
2138                 .seq_show = cfqg_print_stat,
2139         },
2140         {
2141                 .name = "dequeue",
2142                 .private = offsetof(struct cfq_group, stats.dequeue),
2143                 .seq_show = cfqg_print_stat,
2144         },
2145         {
2146                 .name = "unaccounted_time",
2147                 .private = offsetof(struct cfq_group, stats.unaccounted_time),
2148                 .seq_show = cfqg_print_stat,
2149         },
2150 #endif  /* CONFIG_DEBUG_BLK_CGROUP */
2151         { }     /* terminate */
2152 };
2153 
2154 static int cfq_print_weight_on_dfl(struct seq_file *sf, void *v)
2155 {
2156         struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
2157         struct cfq_group_data *cgd = blkcg_to_cfqgd(blkcg);
2158 
2159         seq_printf(sf, "default %u\n", cgd->weight);
2160         blkcg_print_blkgs(sf, blkcg, cfqg_prfill_weight_device,
2161                           &blkcg_policy_cfq, 0, false);
2162         return 0;
2163 }
2164 
2165 static ssize_t cfq_set_weight_on_dfl(struct kernfs_open_file *of,
2166                                      char *buf, size_t nbytes, loff_t off)
2167 {
2168         char *endp;
2169         int ret;
2170         u64 v;
2171 
2172         buf = strim(buf);
2173 
2174         /* "WEIGHT" or "default WEIGHT" sets the default weight */
2175         v = simple_strtoull(buf, &endp, 0);
2176         if (*endp == '\0' || sscanf(buf, "default %llu", &v) == 1) {
2177                 ret = __cfq_set_weight(of_css(of), v, true, false, false);
2178                 return ret ?: nbytes;
2179         }
2180 
2181         /* "MAJ:MIN WEIGHT" */
2182         return __cfqg_set_weight_device(of, buf, nbytes, off, true, false);
2183 }
2184 
2185 static struct cftype cfq_blkcg_files[] = {
2186         {
2187                 .name = "weight",
2188                 .flags = CFTYPE_NOT_ON_ROOT,
2189                 .seq_show = cfq_print_weight_on_dfl,
2190                 .write = cfq_set_weight_on_dfl,
2191         },
2192         { }     /* terminate */
2193 };
2194 
2195 #else /* GROUP_IOSCHED */
2196 static struct cfq_group *cfq_lookup_cfqg(struct cfq_data *cfqd,
2197                                          struct blkcg *blkcg)
2198 {
2199         return cfqd->root_group;
2200 }
2201 
2202 static inline void
2203 cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) {
2204         cfqq->cfqg = cfqg;
2205 }
2206 
2207 #endif /* GROUP_IOSCHED */
2208 
2209 /*
2210  * The cfqd->service_trees holds all pending cfq_queue's that have
2211  * requests waiting to be processed. It is sorted in the order that
2212  * we will service the queues.
2213  */
2214 static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2215                                  bool add_front)
2216 {
2217         struct rb_node **p, *parent;
2218         struct cfq_queue *__cfqq;
2219         u64 rb_key;
2220         struct cfq_rb_root *st;
2221         int left;
2222         int new_cfqq = 1;
2223         u64 now = ktime_get_ns();
2224 
2225         st = st_for(cfqq->cfqg, cfqq_class(cfqq), cfqq_type(cfqq));
2226         if (cfq_class_idle(cfqq)) {
2227                 rb_key = CFQ_IDLE_DELAY;
2228                 parent = rb_last(&st->rb);
2229                 if (parent && parent != &cfqq->rb_node) {
2230                         __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
2231                         rb_key += __cfqq->rb_key;
2232                 } else
2233                         rb_key += now;
2234         } else if (!add_front) {
2235                 /*
2236                  * Get our rb key offset. Subtract any residual slice
2237                  * value carried from last service. A negative resid
2238                  * count indicates slice overrun, and this should position
2239                  * the next service time further away in the tree.
2240                  */
2241                 rb_key = cfq_slice_offset(cfqd, cfqq) + now;
2242                 rb_key -= cfqq->slice_resid;
2243                 cfqq->slice_resid = 0;
2244         } else {
2245                 rb_key = -NSEC_PER_SEC;
2246                 __cfqq = cfq_rb_first(st);
2247                 rb_key += __cfqq ? __cfqq->rb_key : now;
2248         }
2249 
2250         if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
2251                 new_cfqq = 0;
2252                 /*
2253                  * same position, nothing more to do
2254                  */
2255                 if (rb_key == cfqq->rb_key && cfqq->service_tree == st)
2256                         return;
2257 
2258                 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
2259                 cfqq->service_tree = NULL;
2260         }
2261 
2262         left = 1;
2263         parent = NULL;
2264         cfqq->service_tree = st;
2265         p = &st->rb.rb_node;
2266         while (*p) {
2267                 parent = *p;
2268                 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
2269 
2270                 /*
2271                  * sort by key, that represents service time.
2272                  */
2273                 if (rb_key < __cfqq->rb_key)
2274                         p = &parent->rb_left;
2275                 else {
2276                         p = &parent->rb_right;
2277                         left = 0;
2278                 }
2279         }
2280 
2281         if (left)
2282                 st->left = &cfqq->rb_node;
2283 
2284         cfqq->rb_key = rb_key;
2285         rb_link_node(&cfqq->rb_node, parent, p);
2286         rb_insert_color(&cfqq->rb_node, &st->rb);
2287         st->count++;
2288         if (add_front || !new_cfqq)
2289                 return;
2290         cfq_group_notify_queue_add(cfqd, cfqq->cfqg);
2291 }
2292 
2293 static struct cfq_queue *
2294 cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root,
2295                      sector_t sector, struct rb_node **ret_parent,
2296                      struct rb_node ***rb_link)
2297 {
2298         struct rb_node **p, *parent;
2299         struct cfq_queue *cfqq = NULL;
2300 
2301         parent = NULL;
2302         p = &root->rb_node;
2303         while (*p) {
2304                 struct rb_node **n;
2305 
2306                 parent = *p;
2307                 cfqq = rb_entry(parent, struct cfq_queue, p_node);
2308 
2309                 /*
2310                  * Sort strictly based on sector.  Smallest to the left,
2311                  * largest to the right.
2312                  */
2313                 if (sector > blk_rq_pos(cfqq->next_rq))
2314                         n = &(*p)->rb_right;
2315                 else if (sector < blk_rq_pos(cfqq->next_rq))
2316                         n = &(*p)->rb_left;
2317                 else
2318                         break;
2319                 p = n;
2320                 cfqq = NULL;
2321         }
2322 
2323         *ret_parent = parent;
2324         if (rb_link)
2325                 *rb_link = p;
2326         return cfqq;
2327 }
2328 
2329 static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2330 {
2331         struct rb_node **p, *parent;
2332         struct cfq_queue *__cfqq;
2333 
2334         if (cfqq->p_root) {
2335                 rb_erase(&cfqq->p_node, cfqq->p_root);
2336                 cfqq->p_root = NULL;
2337         }
2338 
2339         if (cfq_class_idle(cfqq))
2340                 return;
2341         if (!cfqq->next_rq)
2342                 return;
2343 
2344         cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
2345         __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root,
2346                                       blk_rq_pos(cfqq->next_rq), &parent, &p);
2347         if (!__cfqq) {
2348                 rb_link_node(&cfqq->p_node, parent, p);
2349                 rb_insert_color(&cfqq->p_node, cfqq->p_root);
2350         } else
2351                 cfqq->p_root = NULL;
2352 }
2353 
2354 /*
2355  * Update cfqq's position in the service tree.
2356  */
2357 static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2358 {
2359         /*
2360          * Resorting requires the cfqq to be on the RR list already.
2361          */
2362         if (cfq_cfqq_on_rr(cfqq)) {
2363                 cfq_service_tree_add(cfqd, cfqq, 0);
2364                 cfq_prio_tree_add(cfqd, cfqq);
2365         }
2366 }
2367 
2368 /*
2369  * add to busy list of queues for service, trying to be fair in ordering
2370  * the pending list according to last request service
2371  */
2372 static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2373 {
2374         cfq_log_cfqq(cfqd, cfqq, "add_to_rr");
2375         BUG_ON(cfq_cfqq_on_rr(cfqq));
2376         cfq_mark_cfqq_on_rr(cfqq);
2377         cfqd->busy_queues++;
2378         if (cfq_cfqq_sync(cfqq))
2379                 cfqd->busy_sync_queues++;
2380 
2381         cfq_resort_rr_list(cfqd, cfqq);
2382 }
2383 
2384 /*
2385  * Called when the cfqq no longer has requests pending, remove it from
2386  * the service tree.
2387  */
2388 static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2389 {
2390         cfq_log_cfqq(cfqd, cfqq, "del_from_rr");
2391         BUG_ON(!cfq_cfqq_on_rr(cfqq));
2392         cfq_clear_cfqq_on_rr(cfqq);
2393 
2394         if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
2395                 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
2396                 cfqq->service_tree = NULL;
2397         }
2398         if (cfqq->p_root) {
2399                 rb_erase(&cfqq->p_node, cfqq->p_root);
2400                 cfqq->p_root = NULL;
2401         }
2402 
2403         cfq_group_notify_queue_del(cfqd, cfqq->cfqg);
2404         BUG_ON(!cfqd->busy_queues);
2405         cfqd->busy_queues--;
2406         if (cfq_cfqq_sync(cfqq))
2407                 cfqd->busy_sync_queues--;
2408 }
2409 
2410 /*
2411  * rb tree support functions
2412  */
2413 static void cfq_del_rq_rb(struct request *rq)
2414 {
2415         struct cfq_queue *cfqq = RQ_CFQQ(rq);
2416         const int sync = rq_is_sync(rq);
2417 
2418         BUG_ON(!cfqq->queued[sync]);
2419         cfqq->queued[sync]--;
2420 
2421         elv_rb_del(&cfqq->sort_list, rq);
2422 
2423         if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) {
2424                 /*
2425                  * Queue will be deleted from service tree when we actually
2426                  * expire it later. Right now just remove it from prio tree
2427                  * as it is empty.
2428                  */
2429                 if (cfqq->p_root) {
2430                         rb_erase(&cfqq->p_node, cfqq->p_root);
2431                         cfqq->p_root = NULL;
2432                 }
2433         }
2434 }
2435 
2436 static void cfq_add_rq_rb(struct request *rq)
2437 {
2438         struct cfq_queue *cfqq = RQ_CFQQ(rq);
2439         struct cfq_data *cfqd = cfqq->cfqd;
2440         struct request *prev;
2441 
2442         cfqq->queued[rq_is_sync(rq)]++;
2443 
2444         elv_rb_add(&cfqq->sort_list, rq);
2445 
2446         if (!cfq_cfqq_on_rr(cfqq))
2447                 cfq_add_cfqq_rr(cfqd, cfqq);
2448 
2449         /*
2450          * check if this request is a better next-serve candidate
2451          */
2452         prev = cfqq->next_rq;
2453         cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position);
2454 
2455         /*
2456          * adjust priority tree position, if ->next_rq changes
2457          */
2458         if (prev != cfqq->next_rq)
2459                 cfq_prio_tree_add(cfqd, cfqq);
2460 
2461         BUG_ON(!cfqq->next_rq);
2462 }
2463 
2464 static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq)
2465 {
2466         elv_rb_del(&cfqq->sort_list, rq);
2467         cfqq->queued[rq_is_sync(rq)]--;
2468         cfqg_stats_update_io_remove(RQ_CFQG(rq), rq->cmd_flags);
2469         cfq_add_rq_rb(rq);
2470         cfqg_stats_update_io_add(RQ_CFQG(rq), cfqq->cfqd->serving_group,
2471                                  rq->cmd_flags);
2472 }
2473 
2474 static struct request *
2475 cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
2476 {
2477         struct task_struct *tsk = current;
2478         struct cfq_io_cq *cic;
2479         struct cfq_queue *cfqq;
2480 
2481         cic = cfq_cic_lookup(cfqd, tsk->io_context);
2482         if (!cic)
2483                 return NULL;
2484 
2485         cfqq = cic_to_cfqq(cic, op_is_sync(bio->bi_opf));
2486         if (cfqq)
2487                 return elv_rb_find(&cfqq->sort_list, bio_end_sector(bio));
2488 
2489         return NULL;
2490 }
2491 
2492 static void cfq_activate_request(struct request_queue *q, struct request *rq)
2493 {
2494         struct cfq_data *cfqd = q->elevator->elevator_data;
2495 
2496         cfqd->rq_in_driver++;
2497         cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
2498                                                 cfqd->rq_in_driver);
2499 
2500         cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
2501 }
2502 
2503 static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
2504 {
2505         struct cfq_data *cfqd = q->elevator->elevator_data;
2506 
2507         WARN_ON(!cfqd->rq_in_driver);
2508         cfqd->rq_in_driver--;
2509         cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
2510                                                 cfqd->rq_in_driver);
2511 }
2512 
2513 static void cfq_remove_request(struct request *rq)
2514 {
2515         struct cfq_queue *cfqq = RQ_CFQQ(rq);
2516 
2517         if (cfqq->next_rq == rq)
2518                 cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq);
2519 
2520         list_del_init(&rq->queuelist);
2521         cfq_del_rq_rb(rq);
2522 
2523         cfqq->cfqd->rq_queued--;
2524         cfqg_stats_update_io_remove(RQ_CFQG(rq), rq->cmd_flags);
2525         if (rq->cmd_flags & REQ_PRIO) {
2526                 WARN_ON(!cfqq->prio_pending);
2527                 cfqq->prio_pending--;
2528         }
2529 }
2530 
2531 static int cfq_merge(struct request_queue *q, struct request **req,
2532                      struct bio *bio)
2533 {
2534         struct cfq_data *cfqd = q->elevator->elevator_data;
2535         struct request *__rq;
2536 
2537         __rq = cfq_find_rq_fmerge(cfqd, bio);
2538         if (__rq && elv_bio_merge_ok(__rq, bio)) {
2539                 *req = __rq;
2540                 return ELEVATOR_FRONT_MERGE;
2541         }
2542 
2543         return ELEVATOR_NO_MERGE;
2544 }
2545 
2546 static void cfq_merged_request(struct request_queue *q, struct request *req,
2547                                int type)
2548 {
2549         if (type == ELEVATOR_FRONT_MERGE) {
2550                 struct cfq_queue *cfqq = RQ_CFQQ(req);
2551 
2552                 cfq_reposition_rq_rb(cfqq, req);
2553         }
2554 }
2555 
2556 static void cfq_bio_merged(struct request_queue *q, struct request *req,
2557                                 struct bio *bio)
2558 {
2559         cfqg_stats_update_io_merged(RQ_CFQG(req), bio->bi_opf);
2560 }
2561 
2562 static void
2563 cfq_merged_requests(struct request_queue *q, struct request *rq,
2564                     struct request *next)
2565 {
2566         struct cfq_queue *cfqq = RQ_CFQQ(rq);
2567         struct cfq_data *cfqd = q->elevator->elevator_data;
2568 
2569         /*
2570          * reposition in fifo if next is older than rq
2571          */
2572         if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
2573             next->fifo_time < rq->fifo_time &&
2574             cfqq == RQ_CFQQ(next)) {
2575                 list_move(&rq->queuelist, &next->queuelist);
2576                 rq->fifo_time = next->fifo_time;
2577         }
2578 
2579         if (cfqq->next_rq == next)
2580                 cfqq->next_rq = rq;
2581         cfq_remove_request(next);
2582         cfqg_stats_update_io_merged(RQ_CFQG(rq), next->cmd_flags);
2583 
2584         cfqq = RQ_CFQQ(next);
2585         /*
2586          * all requests of this queue are merged to other queues, delete it
2587          * from the service tree. If it's the active_queue,
2588          * cfq_dispatch_requests() will choose to expire it or do idle
2589          */
2590         if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list) &&
2591             cfqq != cfqd->active_queue)
2592                 cfq_del_cfqq_rr(cfqd, cfqq);
2593 }
2594 
2595 static int cfq_allow_bio_merge(struct request_queue *q, struct request *rq,
2596                                struct bio *bio)
2597 {
2598         struct cfq_data *cfqd = q->elevator->elevator_data;
2599         bool is_sync = op_is_sync(bio->bi_opf);
2600         struct cfq_io_cq *cic;
2601         struct cfq_queue *cfqq;
2602 
2603         /*
2604          * Disallow merge of a sync bio into an async request.
2605          */
2606         if (is_sync && !rq_is_sync(rq))
2607                 return false;
2608 
2609         /*
2610          * Lookup the cfqq that this bio will be queued with and allow
2611          * merge only if rq is queued there.
2612          */
2613         cic = cfq_cic_lookup(cfqd, current->io_context);
2614         if (!cic)
2615                 return false;
2616 
2617         cfqq = cic_to_cfqq(cic, is_sync);
2618         return cfqq == RQ_CFQQ(rq);
2619 }
2620 
2621 static int cfq_allow_rq_merge(struct request_queue *q, struct request *rq,
2622                               struct request *next)
2623 {
2624         return RQ_CFQQ(rq) == RQ_CFQQ(next);
2625 }
2626 
2627 static inline void cfq_del_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2628 {
2629         hrtimer_try_to_cancel(&cfqd->idle_slice_timer);
2630         cfqg_stats_update_idle_time(cfqq->cfqg);
2631 }
2632 
2633 static void __cfq_set_active_queue(struct cfq_data *cfqd,
2634                                    struct cfq_queue *cfqq)
2635 {
2636         if (cfqq) {
2637                 cfq_log_cfqq(cfqd, cfqq, "set_active wl_class:%d wl_type:%d",
2638                                 cfqd->serving_wl_class, cfqd->serving_wl_type);
2639                 cfqg_stats_update_avg_queue_size(cfqq->cfqg);
2640                 cfqq->slice_start = 0;
2641                 cfqq->dispatch_start = ktime_get_ns();
2642                 cfqq->allocated_slice = 0;
2643                 cfqq->slice_end = 0;
2644                 cfqq->slice_dispatch = 0;
2645                 cfqq->nr_sectors = 0;
2646 
2647                 cfq_clear_cfqq_wait_request(cfqq);
2648                 cfq_clear_cfqq_must_dispatch(cfqq);
2649                 cfq_clear_cfqq_must_alloc_slice(cfqq);
2650                 cfq_clear_cfqq_fifo_expire(cfqq);
2651                 cfq_mark_cfqq_slice_new(cfqq);
2652 
2653                 cfq_del_timer(cfqd, cfqq);
2654         }
2655 
2656         cfqd->active_queue = cfqq;
2657 }
2658 
2659 /*
2660  * current cfqq expired its slice (or was too idle), select new one
2661  */
2662 static void
2663 __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2664                     bool timed_out)
2665 {
2666         cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out);
2667 
2668         if (cfq_cfqq_wait_request(cfqq))
2669                 cfq_del_timer(cfqd, cfqq);
2670 
2671         cfq_clear_cfqq_wait_request(cfqq);
2672         cfq_clear_cfqq_wait_busy(cfqq);
2673 
2674         /*
2675          * If this cfqq is shared between multiple processes, check to
2676          * make sure that those processes are still issuing I/Os within
2677          * the mean seek distance.  If not, it may be time to break the
2678          * queues apart again.
2679          */
2680         if (cfq_cfqq_coop(cfqq) && CFQQ_SEEKY(cfqq))
2681                 cfq_mark_cfqq_split_coop(cfqq);
2682 
2683         /*
2684          * store what was left of this slice, if the queue idled/timed out
2685          */
2686         if (timed_out) {
2687                 if (cfq_cfqq_slice_new(cfqq))
2688                         cfqq->slice_resid = cfq_scaled_cfqq_slice(cfqd, cfqq);
2689                 else
2690                         cfqq->slice_resid = cfqq->slice_end - ktime_get_ns();
2691                 cfq_log_cfqq(cfqd, cfqq, "resid=%lld", cfqq->slice_resid);
2692         }
2693 
2694         cfq_group_served(cfqd, cfqq->cfqg, cfqq);
2695 
2696         if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
2697                 cfq_del_cfqq_rr(cfqd, cfqq);
2698 
2699         cfq_resort_rr_list(cfqd, cfqq);
2700 
2701         if (cfqq == cfqd->active_queue)
2702                 cfqd->active_queue = NULL;
2703 
2704         if (cfqd->active_cic) {
2705                 put_io_context(cfqd->active_cic->icq.ioc);
2706                 cfqd->active_cic = NULL;
2707         }
2708 }
2709 
2710 static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out)
2711 {
2712         struct cfq_queue *cfqq = cfqd->active_queue;
2713 
2714         if (cfqq)
2715                 __cfq_slice_expired(cfqd, cfqq, timed_out);
2716 }
2717 
2718 /*
2719  * Get next queue for service. Unless we have a queue preemption,
2720  * we'll simply select the first cfqq in the service tree.
2721  */
2722 static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
2723 {
2724         struct cfq_rb_root *st = st_for(cfqd->serving_group,
2725                         cfqd->serving_wl_class, cfqd->serving_wl_type);
2726 
2727         if (!cfqd->rq_queued)
2728                 return NULL;
2729 
2730         /* There is nothing to dispatch */
2731         if (!st)
2732                 return NULL;
2733         if (RB_EMPTY_ROOT(&st->rb))
2734                 return NULL;
2735         return cfq_rb_first(st);
2736 }
2737 
2738 static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd)
2739 {
2740         struct cfq_group *cfqg;
2741         struct cfq_queue *cfqq;
2742         int i, j;
2743         struct cfq_rb_root *st;
2744 
2745         if (!cfqd->rq_queued)
2746                 return NULL;
2747 
2748         cfqg = cfq_get_next_cfqg(cfqd);
2749         if (!cfqg)
2750                 return NULL;
2751 
2752         for_each_cfqg_st(cfqg, i, j, st)
2753                 if ((cfqq = cfq_rb_first(st)) != NULL)
2754                         return cfqq;
2755         return NULL;
2756 }
2757 
2758 /*
2759  * Get and set a new active queue for service.
2760  */
2761 static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
2762                                               struct cfq_queue *cfqq)
2763 {
2764         if (!cfqq)
2765                 cfqq = cfq_get_next_queue(cfqd);
2766 
2767         __cfq_set_active_queue(cfqd, cfqq);
2768         return cfqq;
2769 }
2770 
2771 static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
2772                                           struct request *rq)
2773 {
2774         if (blk_rq_pos(rq) >= cfqd->last_position)
2775                 return blk_rq_pos(rq) - cfqd->last_position;
2776         else
2777                 return cfqd->last_position - blk_rq_pos(rq);
2778 }
2779 
2780 static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2781                                struct request *rq)
2782 {
2783         return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR;
2784 }
2785 
2786 static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
2787                                     struct cfq_queue *cur_cfqq)
2788 {
2789         struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
2790         struct rb_node *parent, *node;
2791         struct cfq_queue *__cfqq;
2792         sector_t sector = cfqd->last_position;
2793 
2794         if (RB_EMPTY_ROOT(root))
2795                 return NULL;
2796 
2797         /*
2798          * First, if we find a request starting at the end of the last
2799          * request, choose it.
2800          */
2801         __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
2802         if (__cfqq)
2803                 return __cfqq;
2804 
2805         /*
2806          * If the exact sector wasn't found, the parent of the NULL leaf
2807          * will contain the closest sector.
2808          */
2809         __cfqq = rb_entry(parent, struct cfq_queue, p_node);
2810         if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
2811                 return __cfqq;
2812 
2813         if (blk_rq_pos(__cfqq->next_rq) < sector)
2814                 node = rb_next(&__cfqq->p_node);
2815         else
2816                 node = rb_prev(&__cfqq->p_node);
2817         if (!node)
2818                 return NULL;
2819 
2820         __cfqq = rb_entry(node, struct cfq_queue, p_node);
2821         if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
2822                 return __cfqq;
2823 
2824         return NULL;
2825 }
2826 
2827 /*
2828  * cfqd - obvious
2829  * cur_cfqq - passed in so that we don't decide that the current queue is
2830  *            closely cooperating with itself.
2831  *
2832  * So, basically we're assuming that that cur_cfqq has dispatched at least
2833  * one request, and that cfqd->last_position reflects a position on the disk
2834  * associated with the I/O issued by cur_cfqq.  I'm not sure this is a valid
2835  * assumption.
2836  */
2837 static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
2838                                               struct cfq_queue *cur_cfqq)
2839 {
2840         struct cfq_queue *cfqq;
2841 
2842         if (cfq_class_idle(cur_cfqq))
2843                 return NULL;
2844         if (!cfq_cfqq_sync(cur_cfqq))
2845                 return NULL;
2846         if (CFQQ_SEEKY(cur_cfqq))
2847                 return NULL;
2848 
2849         /*
2850          * Don't search priority tree if it's the only queue in the group.
2851          */
2852         if (cur_cfqq->cfqg->nr_cfqq == 1)
2853                 return NULL;
2854 
2855         /*
2856          * We should notice if some of the queues are cooperating, eg
2857          * working closely on the same area of the disk. In that case,
2858          * we can group them together and don't waste time idling.
2859          */
2860         cfqq = cfqq_close(cfqd, cur_cfqq);
2861         if (!cfqq)
2862                 return NULL;
2863 
2864         /* If new queue belongs to different cfq_group, don't choose it */
2865         if (cur_cfqq->cfqg != cfqq->cfqg)
2866                 return NULL;
2867 
2868         /*
2869          * It only makes sense to merge sync queues.
2870          */
2871         if (!cfq_cfqq_sync(cfqq))
2872                 return NULL;
2873         if (CFQQ_SEEKY(cfqq))
2874                 return NULL;
2875 
2876         /*
2877          * Do not merge queues of different priority classes
2878          */
2879         if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq))
2880                 return NULL;
2881 
2882         return cfqq;
2883 }
2884 
2885 /*
2886  * Determine whether we should enforce idle window for this queue.
2887  */
2888 
2889 static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2890 {
2891         enum wl_class_t wl_class = cfqq_class(cfqq);
2892         struct cfq_rb_root *st = cfqq->service_tree;
2893 
2894         BUG_ON(!st);
2895         BUG_ON(!st->count);
2896 
2897         if (!cfqd->cfq_slice_idle)
2898                 return false;
2899 
2900         /* We never do for idle class queues. */
2901         if (wl_class == IDLE_WORKLOAD)
2902                 return false;
2903 
2904         /* We do for queues that were marked with idle window flag. */
2905         if (cfq_cfqq_idle_window(cfqq) &&
2906            !(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag))
2907                 return true;
2908 
2909         /*
2910          * Otherwise, we do only if they are the last ones
2911          * in their service tree.
2912          */
2913         if (st->count == 1 && cfq_cfqq_sync(cfqq) &&
2914            !cfq_io_thinktime_big(cfqd, &st->ttime, false))
2915                 return true;
2916         cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d", st->count);
2917         return false;
2918 }
2919 
2920 static void cfq_arm_slice_timer(struct cfq_data *cfqd)
2921 {
2922         struct cfq_queue *cfqq = cfqd->active_queue;
2923         struct cfq_rb_root *st = cfqq->service_tree;
2924         struct cfq_io_cq *cic;
2925         u64 sl, group_idle = 0;
2926         u64 now = ktime_get_ns();
2927 
2928         /*
2929          * SSD device without seek penalty, disable idling. But only do so
2930          * for devices that support queuing, otherwise we still have a problem
2931          * with sync vs async workloads.
2932          */
2933         if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)
2934                 return;
2935 
2936         WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
2937         WARN_ON(cfq_cfqq_slice_new(cfqq));
2938 
2939         /*
2940          * idle is disabled, either manually or by past process history
2941          */
2942         if (!cfq_should_idle(cfqd, cfqq)) {
2943                 /* no queue idling. Check for group idling */
2944                 if (cfqd->cfq_group_idle)
2945                         group_idle = cfqd->cfq_group_idle;
2946                 else
2947                         return;
2948         }
2949 
2950         /*
2951          * still active requests from this queue, don't idle
2952          */
2953         if (cfqq->dispatched)
2954                 return;
2955 
2956         /*
2957          * task has exited, don't wait
2958          */
2959         cic = cfqd->active_cic;
2960         if (!cic || !atomic_read(&cic->icq.ioc->active_ref))
2961                 return;
2962 
2963         /*
2964          * If our average think time is larger than the remaining time
2965          * slice, then don't idle. This avoids overrunning the allotted
2966          * time slice.
2967          */
2968         if (sample_valid(cic->ttime.ttime_samples) &&
2969             (cfqq->slice_end - now < cic->ttime.ttime_mean)) {
2970                 cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%llu",
2971                              cic->ttime.ttime_mean);
2972                 return;
2973         }
2974 
2975         /*
2976          * There are other queues in the group or this is the only group and
2977          * it has too big thinktime, don't do group idle.
2978          */
2979         if (group_idle &&
2980             (cfqq->cfqg->nr_cfqq > 1 ||
2981              cfq_io_thinktime_big(cfqd, &st->ttime, true)))
2982                 return;
2983 
2984         cfq_mark_cfqq_wait_request(cfqq);
2985 
2986         if (group_idle)
2987                 sl = cfqd->cfq_group_idle;
2988         else
2989                 sl = cfqd->cfq_slice_idle;
2990 
2991         hrtimer_start(&cfqd->idle_slice_timer, ns_to_ktime(sl),
2992                       HRTIMER_MODE_REL);
2993         cfqg_stats_set_start_idle_time(cfqq->cfqg);
2994         cfq_log_cfqq(cfqd, cfqq, "arm_idle: %llu group_idle: %d", sl,
2995                         group_idle ? 1 : 0);
2996 }
2997 
2998 /*
2999  * Move request from internal lists to the request queue dispatch list.
3000  */
3001 static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
3002 {
3003         struct cfq_data *cfqd = q->elevator->elevator_data;
3004         struct cfq_queue *cfqq = RQ_CFQQ(rq);
3005 
3006         cfq_log_cfqq(cfqd, cfqq, "dispatch_insert");
3007 
3008         cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq);
3009         cfq_remove_request(rq);
3010         cfqq->dispatched++;
3011         (RQ_CFQG(rq))->dispatched++;
3012         elv_dispatch_sort(q, rq);
3013 
3014         cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++;
3015         cfqq->nr_sectors += blk_rq_sectors(rq);
3016 }
3017 
3018 /*
3019  * return expired entry, or NULL to just start from scratch in rbtree
3020  */
3021 static struct request *cfq_check_fifo(struct cfq_queue *cfqq)
3022 {
3023         struct request *rq = NULL;
3024 
3025         if (cfq_cfqq_fifo_expire(cfqq))
3026                 return NULL;
3027 
3028         cfq_mark_cfqq_fifo_expire(cfqq);
3029 
3030         if (list_empty(&cfqq->fifo))
3031                 return NULL;
3032 
3033         rq = rq_entry_fifo(cfqq->fifo.next);
3034         if (ktime_get_ns() < rq->fifo_time)
3035                 rq = NULL;
3036 
3037         return rq;
3038 }
3039 
3040 static inline int
3041 cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3042 {
3043         const int base_rq = cfqd->cfq_slice_async_rq;
3044 
3045         WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
3046 
3047         return 2 * base_rq * (IOPRIO_BE_NR - cfqq->ioprio);
3048 }
3049 
3050 /*
3051  * Must be called with the queue_lock held.
3052  */
3053 static int cfqq_process_refs(struct cfq_queue *cfqq)
3054 {
3055         int process_refs, io_refs;
3056 
3057         io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE];
3058         process_refs = cfqq->ref - io_refs;
3059         BUG_ON(process_refs < 0);
3060         return process_refs;
3061 }
3062 
3063 static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq)
3064 {
3065         int process_refs, new_process_refs;
3066         struct cfq_queue *__cfqq;
3067 
3068         /*
3069          * If there are no process references on the new_cfqq, then it is
3070          * unsafe to follow the ->new_cfqq chain as other cfqq's in the
3071          * chain may have dropped their last reference (not just their
3072          * last process reference).
3073          */
3074         if (!cfqq_process_refs(new_cfqq))
3075                 return;
3076 
3077         /* Avoid a circular list and skip interim queue merges */
3078         while ((__cfqq = new_cfqq->new_cfqq)) {
3079                 if (__cfqq == cfqq)
3080                         return;
3081                 new_cfqq = __cfqq;
3082         }
3083 
3084         process_refs = cfqq_process_refs(cfqq);
3085         new_process_refs = cfqq_process_refs(new_cfqq);
3086         /*
3087          * If the process for the cfqq has gone away, there is no
3088          * sense in merging the queues.
3089          */
3090         if (process_refs == 0 || new_process_refs == 0)
3091                 return;
3092 
3093         /*
3094          * Merge in the direction of the lesser amount of work.
3095          */
3096         if (new_process_refs >= process_refs) {
3097                 cfqq->new_cfqq = new_cfqq;
3098                 new_cfqq->ref += process_refs;
3099         } else {
3100                 new_cfqq->new_cfqq = cfqq;
3101                 cfqq->ref += new_process_refs;
3102         }
3103 }
3104 
3105 static enum wl_type_t cfq_choose_wl_type(struct cfq_data *cfqd,
3106                         struct cfq_group *cfqg, enum wl_class_t wl_class)
3107 {
3108         struct cfq_queue *queue;
3109         int i;
3110         bool key_valid = false;
3111         u64 lowest_key = 0;
3112         enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD;
3113 
3114         for (i = 0; i <= SYNC_WORKLOAD; ++i) {
3115                 /* select the one with lowest rb_key */
3116                 queue = cfq_rb_first(st_for(cfqg, wl_class, i));
3117                 if (queue &&
3118                     (!key_valid || queue->rb_key < lowest_key)) {
3119                         lowest_key = queue->rb_key;
3120                         cur_best = i;
3121                         key_valid = true;
3122                 }
3123         }
3124 
3125         return cur_best;
3126 }
3127 
3128 static void
3129 choose_wl_class_and_type(struct cfq_data *cfqd, struct cfq_group *cfqg)
3130 {
3131         u64 slice;
3132         unsigned count;
3133         struct cfq_rb_root *st;
3134         u64 group_slice;
3135         enum wl_class_t original_class = cfqd->serving_wl_class;
3136         u64 now = ktime_get_ns();
3137 
3138         /* Choose next priority. RT > BE > IDLE */
3139         if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg))
3140                 cfqd->serving_wl_class = RT_WORKLOAD;
3141         else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg))
3142                 cfqd->serving_wl_class = BE_WORKLOAD;
3143         else {
3144                 cfqd->serving_wl_class = IDLE_WORKLOAD;
3145                 cfqd->workload_expires = now + jiffies_to_nsecs(1);
3146                 return;
3147         }
3148 
3149         if (original_class != cfqd->serving_wl_class)
3150                 goto new_workload;
3151 
3152         /*
3153          * For RT and BE, we have to choose also the type
3154          * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
3155          * expiration time
3156          */
3157         st = st_for(cfqg, cfqd->serving_wl_class, cfqd->serving_wl_type);
3158         count = st->count;
3159 
3160         /*
3161          * check workload expiration, and that we still have other queues ready
3162          */
3163         if (count && !(now > cfqd->workload_expires))
3164                 return;
3165 
3166 new_workload:
3167         /* otherwise select new workload type */
3168         cfqd->serving_wl_type = cfq_choose_wl_type(cfqd, cfqg,
3169                                         cfqd->serving_wl_class);
3170         st = st_for(cfqg, cfqd->serving_wl_class, cfqd->serving_wl_type);
3171         count = st->count;
3172 
3173         /*
3174          * the workload slice is computed as a fraction of target latency
3175          * proportional to the number of queues in that workload, over
3176          * all the queues in the same priority class
3177          */
3178         group_slice = cfq_group_slice(cfqd, cfqg);
3179 
3180         slice = div_u64(group_slice * count,
3181                 max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_wl_class],
3182                       cfq_group_busy_queues_wl(cfqd->serving_wl_class, cfqd,
3183                                         cfqg)));
3184 
3185         if (cfqd->serving_wl_type == ASYNC_WORKLOAD) {
3186                 u64 tmp;
3187 
3188                 /*
3189                  * Async queues are currently system wide. Just taking
3190                  * proportion of queues with-in same group will lead to higher
3191                  * async ratio system wide as generally root group is going
3192                  * to have higher weight. A more accurate thing would be to
3193                  * calculate system wide asnc/sync ratio.
3194                  */
3195                 tmp = cfqd->cfq_target_latency *
3196                         cfqg_busy_async_queues(cfqd, cfqg);
3197                 tmp = div_u64(tmp, cfqd->busy_queues);
3198                 slice = min_t(u64, slice, tmp);
3199 
3200                 /* async workload slice is scaled down according to
3201                  * the sync/async slice ratio. */
3202                 slice = div64_u64(slice*cfqd->cfq_slice[0], cfqd->cfq_slice[1]);
3203         } else
3204                 /* sync workload slice is at least 2 * cfq_slice_idle */
3205                 slice = max(slice, 2 * cfqd->cfq_slice_idle);
3206 
3207         slice = max_t(u64, slice, CFQ_MIN_TT);
3208         cfq_log(cfqd, "workload slice:%llu", slice);
3209         cfqd->workload_expires = now + slice;
3210 }
3211 
3212 static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd)
3213 {
3214         struct cfq_rb_root *st = &cfqd->grp_service_tree;
3215         struct cfq_group *cfqg;
3216 
3217         if (RB_EMPTY_ROOT(&st->rb))
3218                 return NULL;
3219         cfqg = cfq_rb_first_group(st);
3220         update_min_vdisktime(st);
3221         return cfqg;
3222 }
3223 
3224 static void cfq_choose_cfqg(struct cfq_data *cfqd)
3225 {
3226         struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd);
3227         u64 now = ktime_get_ns();
3228 
3229         cfqd->serving_group = cfqg;
3230 
3231         /* Restore the workload type data */
3232         if (cfqg->saved_wl_slice) {
3233                 cfqd->workload_expires = now + cfqg->saved_wl_slice;
3234                 cfqd->serving_wl_type = cfqg->saved_wl_type;
3235                 cfqd->serving_wl_class = cfqg->saved_wl_class;
3236         } else
3237                 cfqd->workload_expires = now - 1;
3238 
3239         choose_wl_class_and_type(cfqd, cfqg);
3240 }
3241 
3242 /*
3243  * Select a queue for service. If we have a current active queue,
3244  * check whether to continue servicing it, or retrieve and set a new one.
3245  */
3246 static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
3247 {
3248         struct cfq_queue *cfqq, *new_cfqq = NULL;
3249         u64 now = ktime_get_ns();
3250 
3251         cfqq = cfqd->active_queue;
3252         if (!cfqq)
3253                 goto new_queue;
3254 
3255         if (!cfqd->rq_queued)
3256                 return NULL;
3257 
3258         /*
3259          * We were waiting for group to get backlogged. Expire the queue
3260          */
3261         if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list))
3262                 goto expire;
3263 
3264         /*
3265          * The active queue has run out of time, expire it and select new.
3266          */
3267         if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) {
3268                 /*
3269                  * If slice had not expired at the completion of last request
3270                  * we might not have turned on wait_busy flag. Don't expire
3271                  * the queue yet. Allow the group to get backlogged.
3272                  *
3273                  * The very fact that we have used the slice, that means we
3274                  * have been idling all along on this queue and it should be
3275                  * ok to wait for this request to complete.
3276                  */
3277                 if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list)
3278                     && cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
3279                         cfqq = NULL;
3280                         goto keep_queue;
3281                 } else
3282                         goto check_group_idle;
3283         }
3284 
3285         /*
3286          * The active queue has requests and isn't expired, allow it to
3287          * dispatch.
3288          */
3289         if (!RB_EMPTY_ROOT(&cfqq->sort_list))
3290                 goto keep_queue;
3291 
3292         /*
3293          * If another queue has a request waiting within our mean seek
3294          * distance, let it run.  The expire code will check for close
3295          * cooperators and put the close queue at the front of the service
3296          * tree.  If possible, merge the expiring queue with the new cfqq.
3297          */
3298         new_cfqq = cfq_close_cooperator(cfqd, cfqq);
3299         if (new_cfqq) {
3300                 if (!cfqq->new_cfqq)
3301                         cfq_setup_merge(cfqq, new_cfqq);
3302                 goto expire;
3303         }
3304 
3305         /*
3306          * No requests pending. If the active queue still has requests in
3307          * flight or is idling for a new request, allow either of these
3308          * conditions to happen (or time out) before selecting a new queue.
3309          */
3310         if (hrtimer_active(&cfqd->idle_slice_timer)) {
3311                 cfqq = NULL;
3312                 goto keep_queue;
3313         }
3314 
3315         /*
3316          * This is a deep seek queue, but the device is much faster than
3317          * the queue can deliver, don't idle
3318          **/
3319         if (CFQQ_SEEKY(cfqq) && cfq_cfqq_idle_window(cfqq) &&
3320             (cfq_cfqq_slice_new(cfqq) ||
3321             (cfqq->slice_end - now > now - cfqq->slice_start))) {
3322                 cfq_clear_cfqq_deep(cfqq);
3323                 cfq_clear_cfqq_idle_window(cfqq);
3324         }
3325 
3326         if (cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
3327                 cfqq = NULL;
3328                 goto keep_queue;
3329         }
3330 
3331         /*
3332          * If group idle is enabled and there are requests dispatched from
3333          * this group, wait for requests to complete.
3334          */
3335 check_group_idle:
3336         if (cfqd->cfq_group_idle && cfqq->cfqg->nr_cfqq == 1 &&
3337             cfqq->cfqg->dispatched &&
3338             !cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true)) {
3339                 cfqq = NULL;
3340                 goto keep_queue;
3341         }
3342 
3343 expire:
3344         cfq_slice_expired(cfqd, 0);
3345 new_queue:
3346         /*
3347          * Current queue expired. Check if we have to switch to a new
3348          * service tree
3349          */
3350         if (!new_cfqq)
3351                 cfq_choose_cfqg(cfqd);
3352 
3353         cfqq = cfq_set_active_queue(cfqd, new_cfqq);
3354 keep_queue:
3355         return cfqq;
3356 }
3357 
3358 static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq)
3359 {
3360         int dispatched = 0;
3361 
3362         while (cfqq->next_rq) {
3363                 cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq);
3364                 dispatched++;
3365         }
3366 
3367         BUG_ON(!list_empty(&cfqq->fifo));
3368 
3369         /* By default cfqq is not expired if it is empty. Do it explicitly */
3370         __cfq_slice_expired(cfqq->cfqd, cfqq, 0);
3371         return dispatched;
3372 }
3373 
3374 /*
3375  * Drain our current requests. Used for barriers and when switching
3376  * io schedulers on-the-fly.
3377  */
3378 static int cfq_forced_dispatch(struct cfq_data *cfqd)
3379 {
3380         struct cfq_queue *cfqq;
3381         int dispatched = 0;
3382 
3383         /* Expire the timeslice of the current active queue first */
3384         cfq_slice_expired(cfqd, 0);
3385         while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) {
3386                 __cfq_set_active_queue(cfqd, cfqq);
3387                 dispatched += __cfq_forced_dispatch_cfqq(cfqq);
3388         }
3389 
3390         BUG_ON(cfqd->busy_queues);
3391 
3392         cfq_log(cfqd, "forced_dispatch=%d", dispatched);
3393         return dispatched;
3394 }
3395 
3396 static inline bool cfq_slice_used_soon(struct cfq_data *cfqd,
3397         struct cfq_queue *cfqq)
3398 {
3399         u64 now = ktime_get_ns();
3400 
3401         /* the queue hasn't finished any request, can't estimate */
3402         if (cfq_cfqq_slice_new(cfqq))
3403                 return true;
3404         if (now + cfqd->cfq_slice_idle * cfqq->dispatched > cfqq->slice_end)
3405                 return true;
3406 
3407         return false;
3408 }
3409 
3410 static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3411 {
3412         unsigned int max_dispatch;
3413 
3414         if (cfq_cfqq_must_dispatch(cfqq))
3415                 return true;
3416 
3417         /*
3418          * Drain async requests before we start sync IO
3419          */
3420         if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC])
3421                 return false;
3422 
3423         /*
3424          * If this is an async queue and we have sync IO in flight, let it wait
3425          */
3426         if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq))
3427                 return false;
3428 
3429         max_dispatch = max_t(unsigned int, cfqd->cfq_quantum / 2, 1);
3430         if (cfq_class_idle(cfqq))
3431                 max_dispatch = 1;
3432 
3433         /*
3434          * Does this cfqq already have too much IO in flight?
3435          */
3436         if (cfqq->dispatched >= max_dispatch) {
3437                 bool promote_sync = false;
3438                 /*
3439                  * idle queue must always only have a single IO in flight
3440                  */
3441                 if (cfq_class_idle(cfqq))
3442                         return false;
3443 
3444                 /*
3445                  * If there is only one sync queue
3446                  * we can ignore async queue here and give the sync
3447                  * queue no dispatch limit. The reason is a sync queue can
3448                  * preempt async queue, limiting the sync queue doesn't make
3449                  * sense. This is useful for aiostress test.
3450                  */
3451                 if (cfq_cfqq_sync(cfqq) && cfqd->busy_sync_queues == 1)
3452                         promote_sync = true;
3453 
3454                 /*
3455                  * We have other queues, don't allow more IO from this one
3456                  */
3457                 if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq) &&
3458                                 !promote_sync)
3459                         return false;
3460 
3461                 /*
3462                  * Sole queue user, no limit
3463                  */
3464                 if (cfqd->busy_queues == 1 || promote_sync)
3465                         max_dispatch = -1;
3466                 else
3467                         /*
3468                          * Normally we start throttling cfqq when cfq_quantum/2
3469                          * requests have been dispatched. But we can drive
3470                          * deeper queue depths at the beginning of slice
3471                          * subjected to upper limit of cfq_quantum.
3472                          * */
3473                         max_dispatch = cfqd->cfq_quantum;
3474         }
3475 
3476         /*
3477          * Async queues must wait a bit before being allowed dispatch.
3478          * We also ramp up the dispatch depth gradually for async IO,
3479          * based on the last sync IO we serviced
3480          */
3481         if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) {
3482                 u64 last_sync = ktime_get_ns() - cfqd->last_delayed_sync;
3483                 unsigned int depth;
3484 
3485                 depth = div64_u64(last_sync, cfqd->cfq_slice[1]);
3486                 if (!depth && !cfqq->dispatched)
3487                         depth = 1;
3488                 if (depth < max_dispatch)
3489                         max_dispatch = depth;
3490         }
3491 
3492         /*
3493          * If we're below the current max, allow a dispatch
3494          */
3495         return cfqq->dispatched < max_dispatch;
3496 }
3497 
3498 /*
3499  * Dispatch a request from cfqq, moving them to the request queue
3500  * dispatch list.
3501  */
3502 static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3503 {
3504         struct request *rq;
3505 
3506         BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list));
3507 
3508         rq = cfq_check_fifo(cfqq);
3509         if (rq)
3510                 cfq_mark_cfqq_must_dispatch(cfqq);
3511 
3512         if (!cfq_may_dispatch(cfqd, cfqq))
3513                 return false;
3514 
3515         /*
3516          * follow expired path, else get first next available
3517          */
3518         if (!rq)
3519                 rq = cfqq->next_rq;
3520         else
3521                 cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq);
3522 
3523         /*
3524          * insert request into driver dispatch list
3525          */
3526         cfq_dispatch_insert(cfqd->queue, rq);
3527 
3528         if (!cfqd->active_cic) {
3529                 struct cfq_io_cq *cic = RQ_CIC(rq);
3530 
3531                 atomic_long_inc(&cic->icq.ioc->refcount);
3532                 cfqd->active_cic = cic;
3533         }
3534 
3535         return true;
3536 }
3537 
3538 /*
3539  * Find the cfqq that we need to service and move a request from that to the
3540  * dispatch list
3541  */
3542 static int cfq_dispatch_requests(struct request_queue *q, int force)
3543 {
3544         struct cfq_data *cfqd = q->elevator->elevator_data;
3545         struct cfq_queue *cfqq;
3546 
3547         if (!cfqd->busy_queues)
3548                 return 0;
3549 
3550         if (unlikely(force))
3551                 return cfq_forced_dispatch(cfqd);
3552 
3553         cfqq = cfq_select_queue(cfqd);
3554         if (!cfqq)
3555                 return 0;
3556 
3557         /*
3558          * Dispatch a request from this cfqq, if it is allowed
3559          */
3560         if (!cfq_dispatch_request(cfqd, cfqq))
3561                 return 0;
3562 
3563         cfqq->slice_dispatch++;
3564         cfq_clear_cfqq_must_dispatch(cfqq);
3565 
3566         /*
3567          * expire an async queue immediately if it has used up its slice. idle
3568          * queue always expire after 1 dispatch round.
3569          */
3570         if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
3571             cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
3572             cfq_class_idle(cfqq))) {
3573                 cfqq->slice_end = ktime_get_ns() + 1;
3574                 cfq_slice_expired(cfqd, 0);
3575         }
3576 
3577         cfq_log_cfqq(cfqd, cfqq, "dispatched a request");
3578         return 1;
3579 }
3580 
3581 /*
3582  * task holds one reference to the queue, dropped when task exits. each rq
3583  * in-flight on this queue also holds a reference, dropped when rq is freed.
3584  *
3585  * Each cfq queue took a reference on the parent group. Drop it now.
3586  * queue lock must be held here.
3587  */
3588 static void cfq_put_queue(struct cfq_queue *cfqq)
3589 {
3590         struct cfq_data *cfqd = cfqq->cfqd;
3591         struct cfq_group *cfqg;
3592 
3593         BUG_ON(cfqq->ref <= 0);
3594 
3595         cfqq->ref--;
3596         if (cfqq->ref)
3597                 return;
3598 
3599         cfq_log_cfqq(cfqd, cfqq, "put_queue");
3600         BUG_ON(rb_first(&cfqq->sort_list));
3601         BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
3602         cfqg = cfqq->cfqg;
3603 
3604         if (unlikely(cfqd->active_queue == cfqq)) {
3605                 __cfq_slice_expired(cfqd, cfqq, 0);
3606                 cfq_schedule_dispatch(cfqd);
3607         }
3608 
3609         BUG_ON(cfq_cfqq_on_rr(cfqq));
3610         kmem_cache_free(cfq_pool, cfqq);
3611         cfqg_put(cfqg);
3612 }
3613 
3614 static void cfq_put_cooperator(struct cfq_queue *cfqq)
3615 {
3616         struct cfq_queue *__cfqq, *next;
3617 
3618         /*
3619          * If this queue was scheduled to merge with another queue, be
3620          * sure to drop the reference taken on that queue (and others in
3621          * the merge chain).  See cfq_setup_merge and cfq_merge_cfqqs.
3622          */
3623         __cfqq = cfqq->new_cfqq;
3624         while (__cfqq) {
3625                 if (__cfqq == cfqq) {
3626                         WARN(1, "cfqq->new_cfqq loop detected\n");
3627                         break;
3628                 }
3629                 next = __cfqq->new_cfqq;
3630                 cfq_put_queue(__cfqq);
3631                 __cfqq = next;
3632         }
3633 }
3634 
3635 static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3636 {
3637         if (unlikely(cfqq == cfqd->active_queue)) {
3638                 __cfq_slice_expired(cfqd, cfqq, 0);
3639                 cfq_schedule_dispatch(cfqd);
3640         }
3641 
3642         cfq_put_cooperator(cfqq);
3643 
3644         cfq_put_queue(cfqq);
3645 }
3646 
3647 static void cfq_init_icq(struct io_cq *icq)
3648 {
3649         struct cfq_io_cq *cic = icq_to_cic(icq);
3650 
3651         cic->ttime.last_end_request = ktime_get_ns();
3652 }
3653 
3654 static void cfq_exit_icq(struct io_cq *icq)
3655 {
3656         struct cfq_io_cq *cic = icq_to_cic(icq);
3657         struct cfq_data *cfqd = cic_to_cfqd(cic);
3658 
3659         if (cic_to_cfqq(cic, false)) {
3660                 cfq_exit_cfqq(cfqd, cic_to_cfqq(cic, false));
3661                 cic_set_cfqq(cic, NULL, false);
3662         }
3663 
3664         if (cic_to_cfqq(cic, true)) {
3665                 cfq_exit_cfqq(cfqd, cic_to_cfqq(cic, true));
3666                 cic_set_cfqq(cic, NULL, true);
3667         }
3668 }
3669 
3670 static void cfq_init_prio_data(struct cfq_queue *cfqq, struct cfq_io_cq *cic)
3671 {
3672         struct task_struct *tsk = current;
3673         int ioprio_class;
3674 
3675         if (!cfq_cfqq_prio_changed(cfqq))
3676                 return;
3677 
3678         ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio);
3679         switch (ioprio_class) {
3680         default:
3681                 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
3682         case IOPRIO_CLASS_NONE:
3683                 /*
3684                  * no prio set, inherit CPU scheduling settings
3685                  */
3686                 cfqq->ioprio = task_nice_ioprio(tsk);
3687                 cfqq->ioprio_class = task_nice_ioclass(tsk);
3688                 break;
3689         case IOPRIO_CLASS_RT:
3690                 cfqq->ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
3691                 cfqq->ioprio_class = IOPRIO_CLASS_RT;
3692                 break;
3693         case IOPRIO_CLASS_BE:
3694                 cfqq->ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
3695                 cfqq->ioprio_class = IOPRIO_CLASS_BE;
3696                 break;
3697         case IOPRIO_CLASS_IDLE:
3698                 cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
3699                 cfqq->ioprio = 7;
3700                 cfq_clear_cfqq_idle_window(cfqq);
3701                 break;
3702         }
3703 
3704         /*
3705          * keep track of original prio settings in case we have to temporarily
3706          * elevate the priority of this queue
3707          */
3708         cfqq->org_ioprio = cfqq->ioprio;
3709         cfqq->org_ioprio_class = cfqq->ioprio_class;
3710         cfq_clear_cfqq_prio_changed(cfqq);
3711 }
3712 
3713 static void check_ioprio_changed(struct cfq_io_cq *cic, struct bio *bio)
3714 {
3715         int ioprio = cic->icq.ioc->ioprio;
3716         struct cfq_data *cfqd = cic_to_cfqd(cic);
3717         struct cfq_queue *cfqq;
3718 
3719         /*
3720          * Check whether ioprio has changed.  The condition may trigger
3721          * spuriously on a newly created cic but there's no harm.
3722          */
3723         if (unlikely(!cfqd) || likely(cic->ioprio == ioprio))
3724                 return;
3725 
3726         cfqq = cic_to_cfqq(cic, false);
3727         if (cfqq) {
3728                 cfq_put_queue(cfqq);
3729                 cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic, bio);
3730                 cic_set_cfqq(cic, cfqq, false);
3731         }
3732 
3733         cfqq = cic_to_cfqq(cic, true);
3734         if (cfqq)
3735                 cfq_mark_cfqq_prio_changed(cfqq);
3736 
3737         cic->ioprio = ioprio;
3738 }
3739 
3740 static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3741                           pid_t pid, bool is_sync)
3742 {
3743         RB_CLEAR_NODE(&cfqq->rb_node);
3744         RB_CLEAR_NODE(&cfqq->p_node);
3745         INIT_LIST_HEAD(&cfqq->fifo);
3746 
3747         cfqq->ref = 0;
3748         cfqq->cfqd = cfqd;
3749 
3750         cfq_mark_cfqq_prio_changed(cfqq);
3751 
3752         if (is_sync) {
3753                 if (!cfq_class_idle(cfqq))
3754                         cfq_mark_cfqq_idle_window(cfqq);
3755                 cfq_mark_cfqq_sync(cfqq);
3756         }
3757         cfqq->pid = pid;
3758 }
3759 
3760 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3761 static bool check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio)
3762 {
3763         struct cfq_data *cfqd = cic_to_cfqd(cic);
3764         struct cfq_queue *cfqq;
3765         uint64_t serial_nr;
3766         bool nonroot_cg;
3767 
3768         rcu_read_lock();
3769         serial_nr = bio_blkcg(bio)->css.serial_nr;
3770         nonroot_cg = bio_blkcg(bio) != &blkcg_root;
3771         rcu_read_unlock();
3772 
3773         /*
3774          * Check whether blkcg has changed.  The condition may trigger
3775          * spuriously on a newly created cic but there's no harm.
3776          */
3777         if (unlikely(!cfqd) || likely(cic->blkcg_serial_nr == serial_nr))
3778                 return nonroot_cg;
3779 
3780         /*
3781          * Drop reference to queues.  New queues will be assigned in new
3782          * group upon arrival of fresh requests.
3783          */
3784         cfqq = cic_to_cfqq(cic, false);
3785         if (cfqq) {
3786                 cfq_log_cfqq(cfqd, cfqq, "changed cgroup");
3787                 cic_set_cfqq(cic, NULL, false);
3788                 cfq_put_queue(cfqq);
3789         }
3790 
3791         cfqq = cic_to_cfqq(cic, true);
3792         if (cfqq) {
3793                 cfq_log_cfqq(cfqd, cfqq, "changed cgroup");
3794                 cic_set_cfqq(cic, NULL, true);
3795                 cfq_put_queue(cfqq);
3796         }
3797 
3798         cic->blkcg_serial_nr = serial_nr;
3799         return nonroot_cg;
3800 }
3801 #else
3802 static inline bool check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio)
3803 {
3804         return false;
3805 }
3806 #endif  /* CONFIG_CFQ_GROUP_IOSCHED */
3807 
3808 static struct cfq_queue **
3809 cfq_async_queue_prio(struct cfq_group *cfqg, int ioprio_class, int ioprio)
3810 {
3811         switch (ioprio_class) {
3812         case IOPRIO_CLASS_RT:
3813                 return &cfqg->async_cfqq[0][ioprio];
3814         case IOPRIO_CLASS_NONE:
3815                 ioprio = IOPRIO_NORM;
3816                 /* fall through */
3817         case IOPRIO_CLASS_BE:
3818                 return &cfqg->async_cfqq[1][ioprio];
3819         case IOPRIO_CLASS_IDLE:
3820                 return &cfqg->async_idle_cfqq;
3821         default:
3822                 BUG();
3823         }
3824 }
3825 
3826 static struct cfq_queue *
3827 cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic,
3828               struct bio *bio)
3829 {
3830         int ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio);
3831         int ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
3832         struct cfq_queue **async_cfqq = NULL;
3833         struct cfq_queue *cfqq;
3834         struct cfq_group *cfqg;
3835 
3836         rcu_read_lock();
3837         cfqg = cfq_lookup_cfqg(cfqd, bio_blkcg(bio));
3838         if (!cfqg) {
3839                 cfqq = &cfqd->oom_cfqq;
3840                 goto out;
3841         }
3842 
3843         if (!is_sync) {
3844                 if (!ioprio_valid(cic->ioprio)) {
3845                         struct task_struct *tsk = current;
3846                         ioprio = task_nice_ioprio(tsk);
3847                         ioprio_class = task_nice_ioclass(tsk);
3848                 }
3849                 async_cfqq = cfq_async_queue_prio(cfqg, ioprio_class, ioprio);
3850                 cfqq = *async_cfqq;
3851                 if (cfqq)
3852                         goto out;
3853         }
3854 
3855         cfqq = kmem_cache_alloc_node(cfq_pool,
3856                                      GFP_NOWAIT | __GFP_ZERO | __GFP_NOWARN,
3857                                      cfqd->queue->node);
3858         if (!cfqq) {
3859                 cfqq = &cfqd->oom_cfqq;
3860                 goto out;
3861         }
3862 
3863         cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
3864         cfq_init_prio_data(cfqq, cic);
3865         cfq_link_cfqq_cfqg(cfqq, cfqg);
3866         cfq_log_cfqq(cfqd, cfqq, "alloced");
3867 
3868         if (async_cfqq) {
3869                 /* a new async queue is created, pin and remember */
3870                 cfqq->ref++;
3871                 *async_cfqq = cfqq;
3872         }
3873 out:
3874         cfqq->ref++;
3875         rcu_read_unlock();
3876         return cfqq;
3877 }
3878 
3879 static void
3880 __cfq_update_io_thinktime(struct cfq_ttime *ttime, u64 slice_idle)
3881 {
3882         u64 elapsed = ktime_get_ns() - ttime->last_end_request;
3883         elapsed = min(elapsed, 2UL * slice_idle);
3884 
3885         ttime->ttime_samples = (7*ttime->ttime_samples + 256) / 8;
3886         ttime->ttime_total = div_u64(7*ttime->ttime_total + 256*elapsed,  8);
3887         ttime->ttime_mean = div64_ul(ttime->ttime_total + 128,
3888                                      ttime->ttime_samples);
3889 }
3890 
3891 static void
3892 cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3893                         struct cfq_io_cq *cic)
3894 {
3895         if (cfq_cfqq_sync(cfqq)) {
3896                 __cfq_update_io_thinktime(&cic->ttime, cfqd->cfq_slice_idle);
3897                 __cfq_update_io_thinktime(&cfqq->service_tree->ttime,
3898                         cfqd->cfq_slice_idle);
3899         }
3900 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3901         __cfq_update_io_thinktime(&cfqq->cfqg->ttime, cfqd->cfq_group_idle);
3902 #endif
3903 }
3904 
3905 static void
3906 cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3907                        struct request *rq)
3908 {
3909         sector_t sdist = 0;
3910         sector_t n_sec = blk_rq_sectors(rq);
3911         if (cfqq->last_request_pos) {
3912                 if (cfqq->last_request_pos < blk_rq_pos(rq))
3913                         sdist = blk_rq_pos(rq) - cfqq->last_request_pos;
3914                 else
3915                         sdist = cfqq->last_request_pos - blk_rq_pos(rq);
3916         }
3917 
3918         cfqq->seek_history <<= 1;
3919         if (blk_queue_nonrot(cfqd->queue))
3920                 cfqq->seek_history |= (n_sec < CFQQ_SECT_THR_NONROT);
3921         else
3922                 cfqq->seek_history |= (sdist > CFQQ_SEEK_THR);
3923 }
3924 
3925 static inline bool req_noidle(struct request *req)
3926 {
3927         return req_op(req) == REQ_OP_WRITE &&
3928                 (req->cmd_flags & (REQ_SYNC | REQ_IDLE)) == REQ_SYNC;
3929 }
3930 
3931 /*
3932  * Disable idle window if the process thinks too long or seeks so much that
3933  * it doesn't matter
3934  */
3935 static void
3936 cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3937                        struct cfq_io_cq *cic)
3938 {
3939         int old_idle, enable_idle;
3940 
3941         /*
3942          * Don't idle for async or idle io prio class
3943          */
3944         if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq))
3945                 return;
3946 
3947         enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
3948 
3949         if (cfqq->queued[0] + cfqq->queued[1] >= 4)
3950                 cfq_mark_cfqq_deep(cfqq);
3951 
3952         if (cfqq->next_rq && req_noidle(cfqq->next_rq))
3953                 enable_idle = 0;
3954         else if (!atomic_read(&cic->icq.ioc->active_ref) ||
3955                  !cfqd->cfq_slice_idle ||
3956                  (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq)))
3957                 enable_idle = 0;
3958         else if (sample_valid(cic->ttime.ttime_samples)) {
3959                 if (cic->ttime.ttime_mean > cfqd->cfq_slice_idle)
3960                         enable_idle = 0;
3961                 else
3962                         enable_idle = 1;
3963         }
3964 
3965         if (old_idle != enable_idle) {
3966                 cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle);
3967                 if (enable_idle)
3968                         cfq_mark_cfqq_idle_window(cfqq);
3969                 else
3970                         cfq_clear_cfqq_idle_window(cfqq);
3971         }
3972 }
3973 
3974 /*
3975  * Check if new_cfqq should preempt the currently active queue. Return 0 for
3976  * no or if we aren't sure, a 1 will cause a preempt.
3977  */
3978 static bool
3979 cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
3980                    struct request *rq)
3981 {
3982         struct cfq_queue *cfqq;
3983 
3984         cfqq = cfqd->active_queue;
3985         if (!cfqq)
3986                 return false;
3987 
3988         if (cfq_class_idle(new_cfqq))
3989                 return false;
3990 
3991         if (cfq_class_idle(cfqq))
3992                 return true;
3993 
3994         /*
3995          * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice.
3996          */
3997         if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq))
3998                 return false;
3999 
4000         /*
4001          * if the new request is sync, but the currently running queue is
4002          * not, let the sync request have priority.
4003          */
4004         if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq) && !cfq_cfqq_must_dispatch(cfqq))
4005                 return true;
4006 
4007         /*
4008          * Treat ancestors of current cgroup the same way as current cgroup.
4009          * For anybody else we disallow preemption to guarantee service
4010          * fairness among cgroups.
4011          */
4012         if (!cfqg_is_descendant(cfqq->cfqg, new_cfqq->cfqg))
4013                 return false;
4014 
4015         if (cfq_slice_used(cfqq))
4016                 return true;
4017 
4018         /*
4019          * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
4020          */
4021         if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
4022                 return true;
4023 
4024         WARN_ON_ONCE(cfqq->ioprio_class != new_cfqq->ioprio_class);
4025         /* Allow preemption only if we are idling on sync-noidle tree */
4026         if (cfqd->serving_wl_type == SYNC_NOIDLE_WORKLOAD &&
4027             cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD &&
4028             RB_EMPTY_ROOT(&cfqq->sort_list))
4029                 return true;
4030 
4031         /*
4032          * So both queues are sync. Let the new request get disk time if
4033          * it's a metadata request and the current queue is doing regular IO.
4034          */
4035         if ((rq->cmd_flags & REQ_PRIO) && !cfqq->prio_pending)
4036                 return true;
4037 
4038         /* An idle queue should not be idle now for some reason */
4039         if (RB_EMPTY_ROOT(&cfqq->sort_list) && !cfq_should_idle(cfqd, cfqq))
4040                 return true;
4041 
4042         if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq))
4043                 return false;
4044 
4045         /*
4046          * if this request is as-good as one we would expect from the
4047          * current cfqq, let it preempt
4048          */
4049         if (cfq_rq_close(cfqd, cfqq, rq))
4050                 return true;
4051 
4052         return false;
4053 }
4054 
4055 /*
4056  * cfqq preempts the active queue. if we allowed preempt with no slice left,
4057  * let it have half of its nominal slice.
4058  */
4059 static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
4060 {
4061         enum wl_type_t old_type = cfqq_type(cfqd->active_queue);
4062 
4063         cfq_log_cfqq(cfqd, cfqq, "preempt");
4064         cfq_slice_expired(cfqd, 1);
4065 
4066         /*
4067          * workload type is changed, don't save slice, otherwise preempt
4068          * doesn't happen
4069          */
4070         if (old_type != cfqq_type(cfqq))
4071                 cfqq->cfqg->saved_wl_slice = 0;
4072 
4073         /*
4074          * Put the new queue at the front of the of the current list,
4075          * so we know that it will be selected next.
4076          */
4077         BUG_ON(!cfq_cfqq_on_rr(cfqq));
4078 
4079         cfq_service_tree_add(cfqd, cfqq, 1);
4080 
4081         cfqq->slice_end = 0;
4082         cfq_mark_cfqq_slice_new(cfqq);
4083 }
4084 
4085 /*
4086  * Called when a new fs request (rq) is added (to cfqq). Check if there's
4087  * something we should do about it
4088  */
4089 static void
4090 cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
4091                 struct request *rq)
4092 {
4093         struct cfq_io_cq *cic = RQ_CIC(rq);
4094 
4095         cfqd->rq_queued++;
4096         if (rq->cmd_flags & REQ_PRIO)
4097                 cfqq->prio_pending++;
4098 
4099         cfq_update_io_thinktime(cfqd, cfqq, cic);
4100         cfq_update_io_seektime(cfqd, cfqq, rq);
4101         cfq_update_idle_window(cfqd, cfqq, cic);
4102 
4103         cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
4104 
4105         if (cfqq == cfqd->active_queue) {
4106                 /*
4107                  * Remember that we saw a request from this process, but
4108                  * don't start queuing just yet. Otherwise we risk seeing lots
4109                  * of tiny requests, because we disrupt the normal plugging
4110                  * and merging. If the request is already larger than a single
4111                  * page, let it rip immediately. For that case we assume that
4112                  * merging is already done. Ditto for a busy system that
4113                  * has other work pending, don't risk delaying until the
4114                  * idle timer unplug to continue working.
4115                  */
4116                 if (cfq_cfqq_wait_request(cfqq)) {
4117                         if (blk_rq_bytes(rq) > PAGE_SIZE ||
4118                             cfqd->busy_queues > 1) {
4119                                 cfq_del_timer(cfqd, cfqq);
4120                                 cfq_clear_cfqq_wait_request(cfqq);
4121                                 __blk_run_queue(cfqd->queue);
4122                         } else {
4123                                 cfqg_stats_update_idle_time(cfqq->cfqg);
4124                                 cfq_mark_cfqq_must_dispatch(cfqq);
4125                         }
4126                 }
4127         } else if (cfq_should_preempt(cfqd, cfqq, rq)) {
4128                 /*
4129                  * not the active queue - expire current slice if it is
4130                  * idle and has expired it's mean thinktime or this new queue
4131                  * has some old slice time left and is of higher priority or
4132                  * this new queue is RT and the current one is BE
4133                  */
4134                 cfq_preempt_queue(cfqd, cfqq);
4135                 __blk_run_queue(cfqd->queue);
4136         }
4137 }
4138 
4139 static void cfq_insert_request(struct request_queue *q, struct request *rq)
4140 {
4141         struct cfq_data *cfqd = q->elevator->elevator_data;
4142         struct cfq_queue *cfqq = RQ_CFQQ(rq);
4143 
4144         cfq_log_cfqq(cfqd, cfqq, "insert_request");
4145         cfq_init_prio_data(cfqq, RQ_CIC(rq));
4146 
4147         rq->fifo_time = ktime_get_ns() + cfqd->cfq_fifo_expire[rq_is_sync(rq)];
4148         list_add_tail(&rq->queuelist, &cfqq->fifo);
4149         cfq_add_rq_rb(rq);
4150         cfqg_stats_update_io_add(RQ_CFQG(rq), cfqd->serving_group,
4151                                  rq->cmd_flags);
4152         cfq_rq_enqueued(cfqd, cfqq, rq);
4153 }
4154 
4155 /*
4156  * Update hw_tag based on peak queue depth over 50 samples under
4157  * sufficient load.
4158  */
4159 static void cfq_update_hw_tag(struct cfq_data *cfqd)
4160 {
4161         struct cfq_queue *cfqq = cfqd->active_queue;
4162 
4163         if (cfqd->rq_in_driver > cfqd->hw_tag_est_depth)
4164                 cfqd->hw_tag_est_depth = cfqd->rq_in_driver;
4165 
4166         if (cfqd->hw_tag == 1)
4167                 return;
4168 
4169         if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
4170             cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN)
4171                 return;
4172 
4173         /*
4174          * If active queue hasn't enough requests and can idle, cfq might not
4175          * dispatch sufficient requests to hardware. Don't zero hw_tag in this
4176          * case
4177          */
4178         if (cfqq && cfq_cfqq_idle_window(cfqq) &&
4179             cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] <
4180             CFQ_HW_QUEUE_MIN && cfqd->rq_in_driver < CFQ_HW_QUEUE_MIN)
4181                 return;
4182 
4183         if (cfqd->hw_tag_samples++ < 50)
4184                 return;
4185 
4186         if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN)
4187                 cfqd->hw_tag = 1;
4188         else
4189                 cfqd->hw_tag = 0;
4190 }
4191 
4192 static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq)
4193 {
4194         struct cfq_io_cq *cic = cfqd->active_cic;
4195         u64 now = ktime_get_ns();
4196 
4197         /* If the queue already has requests, don't wait */
4198         if (!RB_EMPTY_ROOT(&cfqq->sort_list))
4199                 return false;
4200 
4201         /* If there are other queues in the group, don't wait */
4202         if (cfqq->cfqg->nr_cfqq > 1)
4203                 return false;
4204 
4205         /* the only queue in the group, but think time is big */
4206         if (cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true))
4207                 return false;
4208 
4209         if (cfq_slice_used(cfqq))
4210                 return true;
4211 
4212         /* if slice left is less than think time, wait busy */
4213         if (cic && sample_valid(cic->ttime.ttime_samples)
4214             && (cfqq->slice_end - now < cic->ttime.ttime_mean))
4215                 return true;
4216 
4217         /*
4218          * If think times is less than a jiffy than ttime_mean=0 and above
4219          * will not be true. It might happen that slice has not expired yet
4220          * but will expire soon (4-5 ns) during select_queue(). To cover the
4221          * case where think time is less than a jiffy, mark the queue wait
4222          * busy if only 1 jiffy is left in the slice.
4223          */
4224         if (cfqq->slice_end - now <= jiffies_to_nsecs(1))
4225                 return true;
4226 
4227         return false;
4228 }
4229 
4230 static void cfq_completed_request(struct request_queue *q, struct request *rq)
4231 {
4232         struct cfq_queue *cfqq = RQ_CFQQ(rq);
4233         struct cfq_data *cfqd = cfqq->cfqd;
4234         const int sync = rq_is_sync(rq);
4235         u64 now = ktime_get_ns();
4236 
4237         cfq_log_cfqq(cfqd, cfqq, "complete rqnoidle %d", req_noidle(rq));
4238 
4239         cfq_update_hw_tag(cfqd);
4240 
4241         WARN_ON(!cfqd->rq_in_driver);
4242         WARN_ON(!cfqq->dispatched);
4243         cfqd->rq_in_driver--;
4244         cfqq->dispatched--;
4245         (RQ_CFQG(rq))->dispatched--;
4246         cfqg_stats_update_completion(cfqq->cfqg, rq_start_time_ns(rq),
4247                                      rq_io_start_time_ns(rq), rq->cmd_flags);
4248 
4249         cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--;
4250 
4251         if (sync) {
4252                 struct cfq_rb_root *st;
4253 
4254                 RQ_CIC(rq)->ttime.last_end_request = now;
4255 
4256                 if (cfq_cfqq_on_rr(cfqq))
4257                         st = cfqq->service_tree;
4258                 else
4259                         st = st_for(cfqq->cfqg, cfqq_class(cfqq),
4260                                         cfqq_type(cfqq));
4261 
4262                 st->ttime.last_end_request = now;
4263                 /*
4264                  * We have to do this check in jiffies since start_time is in
4265                  * jiffies and it is not trivial to convert to ns. If
4266                  * cfq_fifo_expire[1] ever comes close to 1 jiffie, this test
4267                  * will become problematic but so far we are fine (the default
4268                  * is 128 ms).
4269                  */
4270                 if (!time_after(rq->start_time +
4271                                   nsecs_to_jiffies(cfqd->cfq_fifo_expire[1]),
4272                                 jiffies))
4273                         cfqd->last_delayed_sync = now;
4274         }
4275 
4276 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4277         cfqq->cfqg->ttime.last_end_request = now;
4278 #endif
4279 
4280         /*
4281          * If this is the active queue, check if it needs to be expired,
4282          * or if we want to idle in case it has no pending requests.
4283          */
4284         if (cfqd->active_queue == cfqq) {
4285                 const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list);
4286 
4287                 if (cfq_cfqq_slice_new(cfqq)) {
4288                         cfq_set_prio_slice(cfqd, cfqq);
4289                         cfq_clear_cfqq_slice_new(cfqq);
4290                 }
4291 
4292                 /*
4293                  * Should we wait for next request to come in before we expire
4294                  * the queue.
4295                  */
4296                 if (cfq_should_wait_busy(cfqd, cfqq)) {
4297                         u64 extend_sl = cfqd->cfq_slice_idle;
4298                         if (!cfqd->cfq_slice_idle)
4299                                 extend_sl = cfqd->cfq_group_idle;
4300                         cfqq->slice_end = now + extend_sl;
4301                         cfq_mark_cfqq_wait_busy(cfqq);
4302                         cfq_log_cfqq(cfqd, cfqq, "will busy wait");
4303                 }
4304 
4305                 /*
4306                  * Idling is not enabled on:
4307                  * - expired queues
4308                  * - idle-priority queues
4309                  * - async queues
4310                  * - queues with still some requests queued
4311                  * - when there is a close cooperator
4312                  */
4313                 if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq))
4314                         cfq_slice_expired(cfqd, 1);
4315                 else if (sync && cfqq_empty &&
4316                          !cfq_close_cooperator(cfqd, cfqq)) {
4317                         cfq_arm_slice_timer(cfqd);
4318                 }
4319         }
4320 
4321         if (!cfqd->rq_in_driver)
4322                 cfq_schedule_dispatch(cfqd);
4323 }
4324 
4325 static void cfqq_boost_on_prio(struct cfq_queue *cfqq, unsigned int op)
4326 {
4327         /*
4328          * If REQ_PRIO is set, boost class and prio level, if it's below
4329          * BE/NORM. If prio is not set, restore the potentially boosted
4330          * class/prio level.
4331          */
4332         if (!(op & REQ_PRIO)) {
4333                 cfqq->ioprio_class = cfqq->org_ioprio_class;
4334                 cfqq->ioprio = cfqq->org_ioprio;
4335         } else {
4336                 if (cfq_class_idle(cfqq))
4337                         cfqq->ioprio_class = IOPRIO_CLASS_BE;
4338                 if (cfqq->ioprio > IOPRIO_NORM)
4339                         cfqq->ioprio = IOPRIO_NORM;
4340         }
4341 }
4342 
4343 static inline int __cfq_may_queue(struct cfq_queue *cfqq)
4344 {
4345         if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) {
4346                 cfq_mark_cfqq_must_alloc_slice(cfqq);
4347                 return ELV_MQUEUE_MUST;
4348         }
4349 
4350         return ELV_MQUEUE_MAY;
4351 }
4352 
4353 static int cfq_may_queue(struct request_queue *q, unsigned int op)
4354 {
4355         struct cfq_data *cfqd = q->elevator->elevator_data;
4356         struct task_struct *tsk = current;
4357         struct cfq_io_cq *cic;
4358         struct cfq_queue *cfqq;
4359 
4360         /*
4361          * don't force setup of a queue from here, as a call to may_queue
4362          * does not necessarily imply that a request actually will be queued.
4363          * so just lookup a possibly existing queue, or return 'may queue'
4364          * if that fails
4365          */
4366         cic = cfq_cic_lookup(cfqd, tsk->io_context);
4367         if (!cic)
4368                 return ELV_MQUEUE_MAY;
4369 
4370         cfqq = cic_to_cfqq(cic, op_is_sync(op));
4371         if (cfqq) {
4372                 cfq_init_prio_data(cfqq, cic);
4373                 cfqq_boost_on_prio(cfqq, op);
4374 
4375                 return __cfq_may_queue(cfqq);
4376         }
4377 
4378         return ELV_MQUEUE_MAY;
4379 }
4380 
4381 /*
4382  * queue lock held here
4383  */
4384 static void cfq_put_request(struct request *rq)
4385 {
4386         struct cfq_queue *cfqq = RQ_CFQQ(rq);
4387 
4388         if (cfqq) {
4389                 const int rw = rq_data_dir(rq);
4390 
4391                 BUG_ON(!cfqq->allocated[rw]);
4392                 cfqq->allocated[rw]--;
4393 
4394                 /* Put down rq reference on cfqg */
4395                 cfqg_put(RQ_CFQG(rq));
4396                 rq->elv.priv[0] = NULL;
4397                 rq->elv.priv[1] = NULL;
4398 
4399                 cfq_put_queue(cfqq);
4400         }
4401 }
4402 
4403 static struct cfq_queue *
4404 cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_cq *cic,
4405                 struct cfq_queue *cfqq)
4406 {
4407         cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq);
4408         cic_set_cfqq(cic, cfqq->new_cfqq, 1);
4409         cfq_mark_cfqq_coop(cfqq->new_cfqq);
4410         cfq_put_queue(cfqq);
4411         return cic_to_cfqq(cic, 1);
4412 }
4413 
4414 /*
4415  * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
4416  * was the last process referring to said cfqq.
4417  */
4418 static struct cfq_queue *
4419 split_cfqq(struct cfq_io_cq *cic, struct cfq_queue *cfqq)
4420 {
4421         if (cfqq_process_refs(cfqq) == 1) {
4422                 cfqq->pid = current->pid;
4423                 cfq_clear_cfqq_coop(cfqq);
4424                 cfq_clear_cfqq_split_coop(cfqq);
4425                 return cfqq;
4426         }
4427 
4428         cic_set_cfqq(cic, NULL, 1);
4429 
4430         cfq_put_cooperator(cfqq);
4431 
4432         cfq_put_queue(cfqq);
4433         return NULL;
4434 }
4435 /*
4436  * Allocate cfq data structures associated with this request.
4437  */
4438 static int
4439 cfq_set_request(struct request_queue *q, struct request *rq, struct bio *bio,
4440                 gfp_t gfp_mask)
4441 {
4442         struct cfq_data *cfqd = q->elevator->elevator_data;
4443         struct cfq_io_cq *cic = icq_to_cic(rq->elv.icq);
4444         const int rw = rq_data_dir(rq);
4445         const bool is_sync = rq_is_sync(rq);
4446         struct cfq_queue *cfqq;
4447         bool disable_wbt;
4448 
4449         spin_lock_irq(q->queue_lock);
4450 
4451         check_ioprio_changed(cic, bio);
4452         disable_wbt = check_blkcg_changed(cic, bio);
4453 new_queue:
4454         cfqq = cic_to_cfqq(cic, is_sync);
4455         if (!cfqq || cfqq == &cfqd->oom_cfqq) {
4456                 if (cfqq)
4457                         cfq_put_queue(cfqq);
4458                 cfqq = cfq_get_queue(cfqd, is_sync, cic, bio);
4459                 cic_set_cfqq(cic, cfqq, is_sync);
4460         } else {
4461                 /*
4462                  * If the queue was seeky for too long, break it apart.
4463                  */
4464                 if (cfq_cfqq_coop(cfqq) && cfq_cfqq_split_coop(cfqq)) {
4465                         cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq");
4466                         cfqq = split_cfqq(cic, cfqq);
4467                         if (!cfqq)
4468                                 goto new_queue;
4469                 }
4470 
4471                 /*
4472                  * Check to see if this queue is scheduled to merge with
4473                  * another, closely cooperating queue.  The merging of
4474                  * queues happens here as it must be done in process context.
4475                  * The reference on new_cfqq was taken in merge_cfqqs.
4476                  */
4477                 if (cfqq->new_cfqq)
4478                         cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq);
4479         }
4480 
4481         cfqq->allocated[rw]++;
4482 
4483         cfqq->ref++;
4484         cfqg_get(cfqq->cfqg);
4485         rq->elv.priv[0] = cfqq;
4486         rq->elv.priv[1] = cfqq->cfqg;
4487         spin_unlock_irq(q->queue_lock);
4488 
4489         if (disable_wbt)
4490                 wbt_disable_default(q);
4491 
4492         return 0;
4493 }
4494 
4495 static void cfq_kick_queue(struct work_struct *work)
4496 {
4497         struct cfq_data *cfqd =
4498                 container_of(work, struct cfq_data, unplug_work);
4499         struct request_queue *q = cfqd->queue;
4500 
4501         spin_lock_irq(q->queue_lock);
4502         __blk_run_queue(cfqd->queue);
4503         spin_unlock_irq(q->queue_lock);
4504 }
4505 
4506 /*
4507  * Timer running if the active_queue is currently idling inside its time slice
4508  */
4509 static enum hrtimer_restart cfq_idle_slice_timer(struct hrtimer *timer)
4510 {
4511         struct cfq_data *cfqd = container_of(timer, struct cfq_data,
4512                                              idle_slice_timer);
4513         struct cfq_queue *cfqq;
4514         unsigned long flags;
4515         int timed_out = 1;
4516 
4517         cfq_log(cfqd, "idle timer fired");
4518 
4519         spin_lock_irqsave(cfqd->queue->queue_lock, flags);
4520 
4521         cfqq = cfqd->active_queue;
4522         if (cfqq) {
4523                 timed_out = 0;
4524 
4525                 /*
4526                  * We saw a request before the queue expired, let it through
4527                  */
4528                 if (cfq_cfqq_must_dispatch(cfqq))
4529                         goto out_kick;
4530 
4531                 /*
4532                  * expired
4533                  */
4534                 if (cfq_slice_used(cfqq))
4535                         goto expire;
4536 
4537                 /*
4538                  * only expire and reinvoke request handler, if there are
4539                  * other queues with pending requests
4540                  */
4541                 if (!cfqd->busy_queues)
4542                         goto out_cont;
4543 
4544                 /*
4545                  * not expired and it has a request pending, let it dispatch
4546                  */
4547                 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
4548                         goto out_kick;
4549 
4550                 /*
4551                  * Queue depth flag is reset only when the idle didn't succeed
4552                  */
4553                 cfq_clear_cfqq_deep(cfqq);
4554         }
4555 expire:
4556         cfq_slice_expired(cfqd, timed_out);
4557 out_kick:
4558         cfq_schedule_dispatch(cfqd);
4559 out_cont:
4560         spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
4561         return HRTIMER_NORESTART;
4562 }
4563 
4564 static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
4565 {
4566         hrtimer_cancel(&cfqd->idle_slice_timer);
4567         cancel_work_sync(&cfqd->unplug_work);
4568 }
4569 
4570 static void cfq_exit_queue(struct elevator_queue *e)
4571 {
4572         struct cfq_data *cfqd = e->elevator_data;
4573         struct request_queue *q = cfqd->queue;
4574 
4575         cfq_shutdown_timer_wq(cfqd);
4576 
4577         spin_lock_irq(q->queue_lock);
4578 
4579         if (cfqd->active_queue)
4580                 __cfq_slice_expired(cfqd, cfqd->active_queue, 0);
4581 
4582         spin_unlock_irq(q->queue_lock);
4583 
4584         cfq_shutdown_timer_wq(cfqd);
4585 
4586 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4587         blkcg_deactivate_policy(q, &blkcg_policy_cfq);
4588 #else
4589         kfree(cfqd->root_group);
4590 #endif
4591         kfree(cfqd);
4592 }
4593 
4594 static int cfq_init_queue(struct request_queue *q, struct elevator_type *e)
4595 {
4596         struct cfq_data *cfqd;
4597         struct blkcg_gq *blkg __maybe_unused;
4598         int i, ret;
4599         struct elevator_queue *eq;
4600 
4601         eq = elevator_alloc(q, e);
4602         if (!eq)
4603                 return -ENOMEM;
4604 
4605         cfqd = kzalloc_node(sizeof(*cfqd), GFP_KERNEL, q->node);
4606         if (!cfqd) {
4607                 kobject_put(&eq->kobj);
4608                 return -ENOMEM;
4609         }
4610         eq->elevator_data = cfqd;
4611 
4612         cfqd->queue = q;
4613         spin_lock_irq(q->queue_lock);
4614         q->elevator = eq;
4615         spin_unlock_irq(q->queue_lock);
4616 
4617         /* Init root service tree */
4618         cfqd->grp_service_tree = CFQ_RB_ROOT;
4619 
4620         /* Init root group and prefer root group over other groups by default */
4621 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4622         ret = blkcg_activate_policy(q, &blkcg_policy_cfq);
4623         if (ret)
4624                 goto out_free;
4625 
4626         cfqd->root_group = blkg_to_cfqg(q->root_blkg);
4627 #else
4628         ret = -ENOMEM;
4629         cfqd->root_group = kzalloc_node(sizeof(*cfqd->root_group),
4630                                         GFP_KERNEL, cfqd->queue->node);
4631         if (!cfqd->root_group)
4632                 goto out_free;
4633 
4634         cfq_init_cfqg_base(cfqd->root_group);
4635         cfqd->root_group->weight = 2 * CFQ_WEIGHT_LEGACY_DFL;
4636         cfqd->root_group->leaf_weight = 2 * CFQ_WEIGHT_LEGACY_DFL;
4637 #endif
4638 
4639         /*
4640          * Not strictly needed (since RB_ROOT just clears the node and we
4641          * zeroed cfqd on alloc), but better be safe in case someone decides
4642          * to add magic to the rb code
4643          */
4644         for (i = 0; i < CFQ_PRIO_LISTS; i++)
4645                 cfqd->prio_trees[i] = RB_ROOT;
4646 
4647         /*
4648          * Our fallback cfqq if cfq_get_queue() runs into OOM issues.
4649          * Grab a permanent reference to it, so that the normal code flow
4650          * will not attempt to free it.  oom_cfqq is linked to root_group
4651          * but shouldn't hold a reference as it'll never be unlinked.  Lose
4652          * the reference from linking right away.
4653          */
4654         cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0);
4655         cfqd->oom_cfqq.ref++;
4656 
4657         spin_lock_irq(q->queue_lock);
4658         cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, cfqd->root_group);
4659         cfqg_put(cfqd->root_group);
4660         spin_unlock_irq(q->queue_lock);
4661 
4662         hrtimer_init(&cfqd->idle_slice_timer, CLOCK_MONOTONIC,
4663                      HRTIMER_MODE_REL);
4664         cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
4665 
4666         INIT_WORK(&cfqd->unplug_work, cfq_kick_queue);
4667 
4668         cfqd->cfq_quantum = cfq_quantum;
4669         cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
4670         cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
4671         cfqd->cfq_back_max = cfq_back_max;
4672         cfqd->cfq_back_penalty = cfq_back_penalty;
4673         cfqd->cfq_slice[0] = cfq_slice_async;
4674         cfqd->cfq_slice[1] = cfq_slice_sync;
4675         cfqd->cfq_target_latency = cfq_target_latency;
4676         cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
4677         cfqd->cfq_slice_idle = cfq_slice_idle;
4678         cfqd->cfq_group_idle = cfq_group_idle;
4679         cfqd->cfq_latency = 1;
4680         cfqd->hw_tag = -1;
4681         /*
4682          * we optimistically start assuming sync ops weren't delayed in last
4683          * second, in order to have larger depth for async operations.
4684          */
4685         cfqd->last_delayed_sync = ktime_get_ns() - NSEC_PER_SEC;
4686         return 0;
4687 
4688 out_free:
4689         kfree(cfqd);
4690         kobject_put(&eq->kobj);
4691         return ret;
4692 }
4693 
4694 static void cfq_registered_queue(struct request_queue *q)
4695 {
4696         struct elevator_queue *e = q->elevator;
4697         struct cfq_data *cfqd = e->elevator_data;
4698 
4699         /*
4700          * Default to IOPS mode with no idling for SSDs
4701          */
4702         if (blk_queue_nonrot(q))
4703                 cfqd->cfq_slice_idle = 0;
4704 }
4705 
4706 /*
4707  * sysfs parts below -->
4708  */
4709 static ssize_t
4710 cfq_var_show(unsigned int var, char *page)
4711 {
4712         return sprintf(page, "%u\n", var);
4713 }
4714 
4715 static ssize_t
4716 cfq_var_store(unsigned int *var, const char *page, size_t count)
4717 {
4718         char *p = (char *) page;
4719 
4720         *var = simple_strtoul(p, &p, 10);
4721         return count;
4722 }
4723 
4724 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV)                            \
4725 static ssize_t __FUNC(struct elevator_queue *e, char *page)             \
4726 {                                                                       \
4727         struct cfq_data *cfqd = e->elevator_data;                       \
4728         u64 __data = __VAR;                                             \
4729         if (__CONV)                                                     \
4730                 __data = div_u64(__data, NSEC_PER_MSEC);                        \
4731         return cfq_var_show(__data, (page));                            \
4732 }
4733 SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
4734 SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
4735 SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
4736 SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0);
4737 SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0);
4738 SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
4739 SHOW_FUNCTION(cfq_group_idle_show, cfqd->cfq_group_idle, 1);
4740 SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
4741 SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
4742 SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
4743 SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0);
4744 SHOW_FUNCTION(cfq_target_latency_show, cfqd->cfq_target_latency, 1);
4745 #undef SHOW_FUNCTION
4746 
4747 #define USEC_SHOW_FUNCTION(__FUNC, __VAR)                               \
4748 static ssize_t __FUNC(struct elevator_queue *e, char *page)             \
4749 {                                                                       \
4750         struct cfq_data *cfqd = e->elevator_data;                       \
4751         u64 __data = __VAR;                                             \
4752         __data = div_u64(__data, NSEC_PER_USEC);                        \
4753         return cfq_var_show(__data, (page));                            \
4754 }
4755 USEC_SHOW_FUNCTION(cfq_slice_idle_us_show, cfqd->cfq_slice_idle);
4756 USEC_SHOW_FUNCTION(cfq_group_idle_us_show, cfqd->cfq_group_idle);
4757 USEC_SHOW_FUNCTION(cfq_slice_sync_us_show, cfqd->cfq_slice[1]);
4758 USEC_SHOW_FUNCTION(cfq_slice_async_us_show, cfqd->cfq_slice[0]);
4759 USEC_SHOW_FUNCTION(cfq_target_latency_us_show, cfqd->cfq_target_latency);
4760 #undef USEC_SHOW_FUNCTION
4761 
4762 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV)                 \
4763 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
4764 {                                                                       \
4765         struct cfq_data *cfqd = e->elevator_data;                       \
4766         unsigned int __data;                                            \
4767         int ret = cfq_var_store(&__data, (page), count);                \
4768         if (__data < (MIN))                                             \
4769                 __data = (MIN);                                         \
4770         else if (__data > (MAX))                                        \
4771                 __data = (MAX);                                         \
4772         if (__CONV)                                                     \
4773                 *(__PTR) = (u64)__data * NSEC_PER_MSEC;                 \
4774         else                                                            \
4775                 *(__PTR) = __data;                                      \
4776         return ret;                                                     \
4777 }
4778 STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
4779 STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1,
4780                 UINT_MAX, 1);
4781 STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1,
4782                 UINT_MAX, 1);
4783 STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
4784 STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1,
4785                 UINT_MAX, 0);
4786 STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
4787 STORE_FUNCTION(cfq_group_idle_store, &cfqd->cfq_group_idle, 0, UINT_MAX, 1);
4788 STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
4789 STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
4790 STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
4791                 UINT_MAX, 0);
4792 STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0);
4793 STORE_FUNCTION(cfq_target_latency_store, &cfqd->cfq_target_latency, 1, UINT_MAX, 1);
4794 #undef STORE_FUNCTION
4795 
4796 #define USEC_STORE_FUNCTION(__FUNC, __PTR, MIN, MAX)                    \
4797 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
4798 {                                                                       \
4799         struct cfq_data *cfqd = e->elevator_data;                       \
4800         unsigned int __data;                                            \
4801         int ret = cfq_var_store(&__data, (page), count);                \
4802         if (__data < (MIN))                                             \
4803                 __data = (MIN);                                         \
4804         else if (__data > (MAX))                                        \
4805                 __data = (MAX);                                         \
4806         *(__PTR) = (u64)__data * NSEC_PER_USEC;                         \
4807         return ret;                                                     \
4808 }
4809 USEC_STORE_FUNCTION(cfq_slice_idle_us_store, &cfqd->cfq_slice_idle, 0, UINT_MAX);
4810 USEC_STORE_FUNCTION(cfq_group_idle_us_store, &cfqd->cfq_group_idle, 0, UINT_MAX);
4811 USEC_STORE_FUNCTION(cfq_slice_sync_us_store, &cfqd->cfq_slice[1], 1, UINT_MAX);
4812 USEC_STORE_FUNCTION(cfq_slice_async_us_store, &cfqd->cfq_slice[0], 1, UINT_MAX);
4813 USEC_STORE_FUNCTION(cfq_target_latency_us_store, &cfqd->cfq_target_latency, 1, UINT_MAX);
4814 #undef USEC_STORE_FUNCTION
4815 
4816 #define CFQ_ATTR(name) \
4817         __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
4818 
4819 static struct elv_fs_entry cfq_attrs[] = {
4820         CFQ_ATTR(quantum),
4821         CFQ_ATTR(fifo_expire_sync),
4822         CFQ_ATTR(fifo_expire_async),
4823         CFQ_ATTR(back_seek_max),
4824         CFQ_ATTR(back_seek_penalty),
4825         CFQ_ATTR(slice_sync),
4826         CFQ_ATTR(slice_sync_us),
4827         CFQ_ATTR(slice_async),
4828         CFQ_ATTR(slice_async_us),
4829         CFQ_ATTR(slice_async_rq),
4830         CFQ_ATTR(slice_idle),
4831         CFQ_ATTR(slice_idle_us),
4832         CFQ_ATTR(group_idle),
4833         CFQ_ATTR(group_idle_us),
4834         CFQ_ATTR(low_latency),
4835         CFQ_ATTR(target_latency),
4836         CFQ_ATTR(target_latency_us),
4837         __ATTR_NULL
4838 };
4839 
4840 static struct elevator_type iosched_cfq = {
4841         .ops = {
4842                 .elevator_merge_fn =            cfq_merge,
4843                 .elevator_merged_fn =           cfq_merged_request,
4844                 .elevator_merge_req_fn =        cfq_merged_requests,
4845                 .elevator_allow_bio_merge_fn =  cfq_allow_bio_merge,
4846                 .elevator_allow_rq_merge_fn =   cfq_allow_rq_merge,
4847                 .elevator_bio_merged_fn =       cfq_bio_merged,
4848                 .elevator_dispatch_fn =         cfq_dispatch_requests,
4849                 .elevator_add_req_fn =          cfq_insert_request,
4850                 .elevator_activate_req_fn =     cfq_activate_request,
4851                 .elevator_deactivate_req_fn =   cfq_deactivate_request,
4852                 .elevator_completed_req_fn =    cfq_completed_request,
4853                 .elevator_former_req_fn =       elv_rb_former_request,
4854                 .elevator_latter_req_fn =       elv_rb_latter_request,
4855                 .elevator_init_icq_fn =         cfq_init_icq,
4856                 .elevator_exit_icq_fn =         cfq_exit_icq,
4857                 .elevator_set_req_fn =          cfq_set_request,
4858                 .elevator_put_req_fn =          cfq_put_request,
4859                 .elevator_may_queue_fn =        cfq_may_queue,
4860                 .elevator_init_fn =             cfq_init_queue,
4861                 .elevator_exit_fn =             cfq_exit_queue,
4862                 .elevator_registered_fn =       cfq_registered_queue,
4863         },
4864         .icq_size       =       sizeof(struct cfq_io_cq),
4865         .icq_align      =       __alignof__(struct cfq_io_cq),
4866         .elevator_attrs =       cfq_attrs,
4867         .elevator_name  =       "cfq",
4868         .elevator_owner =       THIS_MODULE,
4869 };
4870 
4871 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4872 static struct blkcg_policy blkcg_policy_cfq = {
4873         .dfl_cftypes            = cfq_blkcg_files,
4874         .legacy_cftypes         = cfq_blkcg_legacy_files,
4875 
4876         .cpd_alloc_fn           = cfq_cpd_alloc,
4877         .cpd_init_fn            = cfq_cpd_init,
4878         .cpd_free_fn            = cfq_cpd_free,
4879         .cpd_bind_fn            = cfq_cpd_bind,
4880 
4881         .pd_alloc_fn            = cfq_pd_alloc,
4882         .pd_init_fn             = cfq_pd_init,
4883         .pd_offline_fn          = cfq_pd_offline,
4884         .pd_free_fn             = cfq_pd_free,
4885         .pd_reset_stats_fn      = cfq_pd_reset_stats,
4886 };
4887 #endif
4888 
4889 static int __init cfq_init(void)
4890 {
4891         int ret;
4892 
4893 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4894         ret = blkcg_policy_register(&blkcg_policy_cfq);
4895         if (ret)
4896                 return ret;
4897 #else
4898         cfq_group_idle = 0;
4899 #endif
4900 
4901         ret = -ENOMEM;
4902         cfq_pool = KMEM_CACHE(cfq_queue, 0);
4903         if (!cfq_pool)
4904                 goto err_pol_unreg;
4905 
4906         ret = elv_register(&iosched_cfq);
4907         if (ret)
4908                 goto err_free_pool;
4909 
4910         return 0;
4911 
4912 err_free_pool:
4913         kmem_cache_destroy(cfq_pool);
4914 err_pol_unreg:
4915 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4916         blkcg_policy_unregister(&blkcg_policy_cfq);
4917 #endif
4918         return ret;
4919 }
4920 
4921 static void __exit cfq_exit(void)
4922 {
4923 #ifdef CONFIG_CFQ_GROUP_IOSCHED
4924         blkcg_policy_unregister(&blkcg_policy_cfq);
4925 #endif
4926         elv_unregister(&iosched_cfq);
4927         kmem_cache_destroy(cfq_pool);
4928 }
4929 
4930 module_init(cfq_init);
4931 module_exit(cfq_exit);
4932 
4933 MODULE_AUTHOR("Jens Axboe");
4934 MODULE_LICENSE("GPL");
4935 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");
4936 

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