ed41aa978c4abc66cd2845f4c18177c97387a881
[sfrench/cifs-2.6.git] / 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/sched/clock.h>
12 #include <linux/blkdev.h>
13 #include <linux/elevator.h>
14 #include <linux/ktime.h>
15 #include <linux/rbtree.h>
16 #include <linux/ioprio.h>
17 #include <linux/blktrace_api.h>
18 #include <linux/blk-cgroup.h>
19 #include "blk.h"
20 #include "blk-wbt.h"
21
22 /*
23  * tunables
24  */
25 /* max queue in one round of service */
26 static const int cfq_quantum = 8;
27 static const u64 cfq_fifo_expire[2] = { NSEC_PER_SEC / 4, NSEC_PER_SEC / 8 };
28 /* maximum backwards seek, in KiB */
29 static const int cfq_back_max = 16 * 1024;
30 /* penalty of a backwards seek */
31 static const int cfq_back_penalty = 2;
32 static const u64 cfq_slice_sync = NSEC_PER_SEC / 10;
33 static u64 cfq_slice_async = NSEC_PER_SEC / 25;
34 static const int cfq_slice_async_rq = 2;
35 static u64 cfq_slice_idle = NSEC_PER_SEC / 125;
36 static u64 cfq_group_idle = NSEC_PER_SEC / 125;
37 static const u64 cfq_target_latency = (u64)NSEC_PER_SEC * 3/10; /* 300 ms */
38 static const int cfq_hist_divisor = 4;
39
40 /*
41  * offset from end of queue service tree for idle class
42  */
43 #define CFQ_IDLE_DELAY          (NSEC_PER_SEC / 5)
44 /* offset from end of group service tree under time slice mode */
45 #define CFQ_SLICE_MODE_GROUP_DELAY (NSEC_PER_SEC / 5)
46 /* offset from end of group service under IOPS mode */
47 #define CFQ_IOPS_MODE_GROUP_DELAY (HZ / 5)
48
49 /*
50  * below this threshold, we consider thinktime immediate
51  */
52 #define CFQ_MIN_TT              (2 * NSEC_PER_SEC / HZ)
53
54 #define CFQ_SLICE_SCALE         (5)
55 #define CFQ_HW_QUEUE_MIN        (5)
56 #define CFQ_SERVICE_SHIFT       12
57
58 #define CFQQ_SEEK_THR           (sector_t)(8 * 100)
59 #define CFQQ_CLOSE_THR          (sector_t)(8 * 1024)
60 #define CFQQ_SECT_THR_NONROT    (sector_t)(2 * 32)
61 #define CFQQ_SEEKY(cfqq)        (hweight32(cfqq->seek_history) > 32/8)
62
63 #define RQ_CIC(rq)              icq_to_cic((rq)->elv.icq)
64 #define RQ_CFQQ(rq)             (struct cfq_queue *) ((rq)->elv.priv[0])
65 #define RQ_CFQG(rq)             (struct cfq_group *) ((rq)->elv.priv[1])
66
67 static struct kmem_cache *cfq_pool;
68
69 #define CFQ_PRIO_LISTS          IOPRIO_BE_NR
70 #define cfq_class_idle(cfqq)    ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
71 #define cfq_class_rt(cfqq)      ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
72
73 #define sample_valid(samples)   ((samples) > 80)
74 #define rb_entry_cfqg(node)     rb_entry((node), struct cfq_group, rb_node)
75
76 /* blkio-related constants */
77 #define CFQ_WEIGHT_LEGACY_MIN   10
78 #define CFQ_WEIGHT_LEGACY_DFL   500
79 #define CFQ_WEIGHT_LEGACY_MAX   1000
80
81 struct cfq_ttime {
82         u64 last_end_request;
83
84         u64 ttime_total;
85         u64 ttime_mean;
86         unsigned long ttime_samples;
87 };
88
89 /*
90  * Most of our rbtree usage is for sorting with min extraction, so
91  * if we cache the leftmost node we don't have to walk down the tree
92  * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should
93  * move this into the elevator for the rq sorting as well.
94  */
95 struct cfq_rb_root {
96         struct rb_root_cached rb;
97         struct rb_node *rb_rightmost;
98         unsigned count;
99         u64 min_vdisktime;
100         struct cfq_ttime ttime;
101 };
102 #define CFQ_RB_ROOT     (struct cfq_rb_root) { .rb = RB_ROOT_CACHED, \
103                         .rb_rightmost = NULL,                        \
104                         .ttime = {.last_end_request = ktime_get_ns(),},}
105
106 /*
107  * Per process-grouping structure
108  */
109 struct cfq_queue {
110         /* reference count */
111         int ref;
112         /* various state flags, see below */
113         unsigned int flags;
114         /* parent cfq_data */
115         struct cfq_data *cfqd;
116         /* service_tree member */
117         struct rb_node rb_node;
118         /* service_tree key */
119         u64 rb_key;
120         /* prio tree member */
121         struct rb_node p_node;
122         /* prio tree root we belong to, if any */
123         struct rb_root *p_root;
124         /* sorted list of pending requests */
125         struct rb_root sort_list;
126         /* if fifo isn't expired, next request to serve */
127         struct request *next_rq;
128         /* requests queued in sort_list */
129         int queued[2];
130         /* currently allocated requests */
131         int allocated[2];
132         /* fifo list of requests in sort_list */
133         struct list_head fifo;
134
135         /* time when queue got scheduled in to dispatch first request. */
136         u64 dispatch_start;
137         u64 allocated_slice;
138         u64 slice_dispatch;
139         /* time when first request from queue completed and slice started. */
140         u64 slice_start;
141         u64 slice_end;
142         s64 slice_resid;
143
144         /* pending priority requests */
145         int prio_pending;
146         /* number of requests that are on the dispatch list or inside driver */
147         int dispatched;
148
149         /* io prio of this group */
150         unsigned short ioprio, org_ioprio;
151         unsigned short ioprio_class, org_ioprio_class;
152
153         pid_t pid;
154
155         u32 seek_history;
156         sector_t last_request_pos;
157
158         struct cfq_rb_root *service_tree;
159         struct cfq_queue *new_cfqq;
160         struct cfq_group *cfqg;
161         /* Number of sectors dispatched from queue in single dispatch round */
162         unsigned long nr_sectors;
163 };
164
165 /*
166  * First index in the service_trees.
167  * IDLE is handled separately, so it has negative index
168  */
169 enum wl_class_t {
170         BE_WORKLOAD = 0,
171         RT_WORKLOAD = 1,
172         IDLE_WORKLOAD = 2,
173         CFQ_PRIO_NR,
174 };
175
176 /*
177  * Second index in the service_trees.
178  */
179 enum wl_type_t {
180         ASYNC_WORKLOAD = 0,
181         SYNC_NOIDLE_WORKLOAD = 1,
182         SYNC_WORKLOAD = 2
183 };
184
185 struct cfqg_stats {
186 #ifdef CONFIG_CFQ_GROUP_IOSCHED
187         /* number of ios merged */
188         struct blkg_rwstat              merged;
189         /* total time spent on device in ns, may not be accurate w/ queueing */
190         struct blkg_rwstat              service_time;
191         /* total time spent waiting in scheduler queue in ns */
192         struct blkg_rwstat              wait_time;
193         /* number of IOs queued up */
194         struct blkg_rwstat              queued;
195         /* total disk time and nr sectors dispatched by this group */
196         struct blkg_stat                time;
197 #ifdef CONFIG_DEBUG_BLK_CGROUP
198         /* time not charged to this cgroup */
199         struct blkg_stat                unaccounted_time;
200         /* sum of number of ios queued across all samples */
201         struct blkg_stat                avg_queue_size_sum;
202         /* count of samples taken for average */
203         struct blkg_stat                avg_queue_size_samples;
204         /* how many times this group has been removed from service tree */
205         struct blkg_stat                dequeue;
206         /* total time spent waiting for it to be assigned a timeslice. */
207         struct blkg_stat                group_wait_time;
208         /* time spent idling for this blkcg_gq */
209         struct blkg_stat                idle_time;
210         /* total time with empty current active q with other requests queued */
211         struct blkg_stat                empty_time;
212         /* fields after this shouldn't be cleared on stat reset */
213         u64                             start_group_wait_time;
214         u64                             start_idle_time;
215         u64                             start_empty_time;
216         uint16_t                        flags;
217 #endif  /* CONFIG_DEBUG_BLK_CGROUP */
218 #endif  /* CONFIG_CFQ_GROUP_IOSCHED */
219 };
220
221 /* Per-cgroup data */
222 struct cfq_group_data {
223         /* must be the first member */
224         struct blkcg_policy_data cpd;
225
226         unsigned int weight;
227         unsigned int leaf_weight;
228 };
229
230 /* This is per cgroup per device grouping structure */
231 struct cfq_group {
232         /* must be the first member */
233         struct blkg_policy_data pd;
234
235         /* group service_tree member */
236         struct rb_node rb_node;
237
238         /* group service_tree key */
239         u64 vdisktime;
240
241         /*
242          * The number of active cfqgs and sum of their weights under this
243          * cfqg.  This covers this cfqg's leaf_weight and all children's
244          * weights, but does not cover weights of further descendants.
245          *
246          * If a cfqg is on the service tree, it's active.  An active cfqg
247          * also activates its parent and contributes to the children_weight
248          * of the parent.
249          */
250         int nr_active;
251         unsigned int children_weight;
252
253         /*
254          * vfraction is the fraction of vdisktime that the tasks in this
255          * cfqg are entitled to.  This is determined by compounding the
256          * ratios walking up from this cfqg to the root.
257          *
258          * It is in fixed point w/ CFQ_SERVICE_SHIFT and the sum of all
259          * vfractions on a service tree is approximately 1.  The sum may
260          * deviate a bit due to rounding errors and fluctuations caused by
261          * cfqgs entering and leaving the service tree.
262          */
263         unsigned int vfraction;
264
265         /*
266          * There are two weights - (internal) weight is the weight of this
267          * cfqg against the sibling cfqgs.  leaf_weight is the wight of
268          * this cfqg against the child cfqgs.  For the root cfqg, both
269          * weights are kept in sync for backward compatibility.
270          */
271         unsigned int weight;
272         unsigned int new_weight;
273         unsigned int dev_weight;
274
275         unsigned int leaf_weight;
276         unsigned int new_leaf_weight;
277         unsigned int dev_leaf_weight;
278
279         /* number of cfqq currently on this group */
280         int nr_cfqq;
281
282         /*
283          * Per group busy queues average. Useful for workload slice calc. We
284          * create the array for each prio class but at run time it is used
285          * only for RT and BE class and slot for IDLE class remains unused.
286          * This is primarily done to avoid confusion and a gcc warning.
287          */
288         unsigned int busy_queues_avg[CFQ_PRIO_NR];
289         /*
290          * rr lists of queues with requests. We maintain service trees for
291          * RT and BE classes. These trees are subdivided in subclasses
292          * of SYNC, SYNC_NOIDLE and ASYNC based on workload type. For IDLE
293          * class there is no subclassification and all the cfq queues go on
294          * a single tree service_tree_idle.
295          * Counts are embedded in the cfq_rb_root
296          */
297         struct cfq_rb_root service_trees[2][3];
298         struct cfq_rb_root service_tree_idle;
299
300         u64 saved_wl_slice;
301         enum wl_type_t saved_wl_type;
302         enum wl_class_t saved_wl_class;
303
304         /* number of requests that are on the dispatch list or inside driver */
305         int dispatched;
306         struct cfq_ttime ttime;
307         struct cfqg_stats stats;        /* stats for this cfqg */
308
309         /* async queue for each priority case */
310         struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR];
311         struct cfq_queue *async_idle_cfqq;
312
313 };
314
315 struct cfq_io_cq {
316         struct io_cq            icq;            /* must be the first member */
317         struct cfq_queue        *cfqq[2];
318         struct cfq_ttime        ttime;
319         int                     ioprio;         /* the current ioprio */
320 #ifdef CONFIG_CFQ_GROUP_IOSCHED
321         uint64_t                blkcg_serial_nr; /* the current blkcg serial */
322 #endif
323 };
324
325 /*
326  * Per block device queue structure
327  */
328 struct cfq_data {
329         struct request_queue *queue;
330         /* Root service tree for cfq_groups */
331         struct cfq_rb_root grp_service_tree;
332         struct cfq_group *root_group;
333
334         /*
335          * The priority currently being served
336          */
337         enum wl_class_t serving_wl_class;
338         enum wl_type_t serving_wl_type;
339         u64 workload_expires;
340         struct cfq_group *serving_group;
341
342         /*
343          * Each priority tree is sorted by next_request position.  These
344          * trees are used when determining if two or more queues are
345          * interleaving requests (see cfq_close_cooperator).
346          */
347         struct rb_root prio_trees[CFQ_PRIO_LISTS];
348
349         unsigned int busy_queues;
350         unsigned int busy_sync_queues;
351
352         int rq_in_driver;
353         int rq_in_flight[2];
354
355         /*
356          * queue-depth detection
357          */
358         int rq_queued;
359         int hw_tag;
360         /*
361          * hw_tag can be
362          * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection)
363          *  1 => NCQ is present (hw_tag_est_depth is the estimated max depth)
364          *  0 => no NCQ
365          */
366         int hw_tag_est_depth;
367         unsigned int hw_tag_samples;
368
369         /*
370          * idle window management
371          */
372         struct hrtimer idle_slice_timer;
373         struct work_struct unplug_work;
374
375         struct cfq_queue *active_queue;
376         struct cfq_io_cq *active_cic;
377
378         sector_t last_position;
379
380         /*
381          * tunables, see top of file
382          */
383         unsigned int cfq_quantum;
384         unsigned int cfq_back_penalty;
385         unsigned int cfq_back_max;
386         unsigned int cfq_slice_async_rq;
387         unsigned int cfq_latency;
388         u64 cfq_fifo_expire[2];
389         u64 cfq_slice[2];
390         u64 cfq_slice_idle;
391         u64 cfq_group_idle;
392         u64 cfq_target_latency;
393
394         /*
395          * Fallback dummy cfqq for extreme OOM conditions
396          */
397         struct cfq_queue oom_cfqq;
398
399         u64 last_delayed_sync;
400 };
401
402 static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd);
403 static void cfq_put_queue(struct cfq_queue *cfqq);
404
405 static struct cfq_rb_root *st_for(struct cfq_group *cfqg,
406                                             enum wl_class_t class,
407                                             enum wl_type_t type)
408 {
409         if (!cfqg)
410                 return NULL;
411
412         if (class == IDLE_WORKLOAD)
413                 return &cfqg->service_tree_idle;
414
415         return &cfqg->service_trees[class][type];
416 }
417
418 enum cfqq_state_flags {
419         CFQ_CFQQ_FLAG_on_rr = 0,        /* on round-robin busy list */
420         CFQ_CFQQ_FLAG_wait_request,     /* waiting for a request */
421         CFQ_CFQQ_FLAG_must_dispatch,    /* must be allowed a dispatch */
422         CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */
423         CFQ_CFQQ_FLAG_fifo_expire,      /* FIFO checked in this slice */
424         CFQ_CFQQ_FLAG_idle_window,      /* slice idling enabled */
425         CFQ_CFQQ_FLAG_prio_changed,     /* task priority has changed */
426         CFQ_CFQQ_FLAG_slice_new,        /* no requests dispatched in slice */
427         CFQ_CFQQ_FLAG_sync,             /* synchronous queue */
428         CFQ_CFQQ_FLAG_coop,             /* cfqq is shared */
429         CFQ_CFQQ_FLAG_split_coop,       /* shared cfqq will be splitted */
430         CFQ_CFQQ_FLAG_deep,             /* sync cfqq experienced large depth */
431         CFQ_CFQQ_FLAG_wait_busy,        /* Waiting for next request */
432 };
433
434 #define CFQ_CFQQ_FNS(name)                                              \
435 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq)         \
436 {                                                                       \
437         (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name);                   \
438 }                                                                       \
439 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq)        \
440 {                                                                       \
441         (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name);                  \
442 }                                                                       \
443 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq)         \
444 {                                                                       \
445         return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0;      \
446 }
447
448 CFQ_CFQQ_FNS(on_rr);
449 CFQ_CFQQ_FNS(wait_request);
450 CFQ_CFQQ_FNS(must_dispatch);
451 CFQ_CFQQ_FNS(must_alloc_slice);
452 CFQ_CFQQ_FNS(fifo_expire);
453 CFQ_CFQQ_FNS(idle_window);
454 CFQ_CFQQ_FNS(prio_changed);
455 CFQ_CFQQ_FNS(slice_new);
456 CFQ_CFQQ_FNS(sync);
457 CFQ_CFQQ_FNS(coop);
458 CFQ_CFQQ_FNS(split_coop);
459 CFQ_CFQQ_FNS(deep);
460 CFQ_CFQQ_FNS(wait_busy);
461 #undef CFQ_CFQQ_FNS
462
463 #if defined(CONFIG_CFQ_GROUP_IOSCHED) && defined(CONFIG_DEBUG_BLK_CGROUP)
464
465 /* cfqg stats flags */
466 enum cfqg_stats_flags {
467         CFQG_stats_waiting = 0,
468         CFQG_stats_idling,
469         CFQG_stats_empty,
470 };
471
472 #define CFQG_FLAG_FNS(name)                                             \
473 static inline void cfqg_stats_mark_##name(struct cfqg_stats *stats)     \
474 {                                                                       \
475         stats->flags |= (1 << CFQG_stats_##name);                       \
476 }                                                                       \
477 static inline void cfqg_stats_clear_##name(struct cfqg_stats *stats)    \
478 {                                                                       \
479         stats->flags &= ~(1 << CFQG_stats_##name);                      \
480 }                                                                       \
481 static inline int cfqg_stats_##name(struct cfqg_stats *stats)           \
482 {                                                                       \
483         return (stats->flags & (1 << CFQG_stats_##name)) != 0;          \
484 }                                                                       \
485
486 CFQG_FLAG_FNS(waiting)
487 CFQG_FLAG_FNS(idling)
488 CFQG_FLAG_FNS(empty)
489 #undef CFQG_FLAG_FNS
490
491 /* This should be called with the queue_lock held. */
492 static void cfqg_stats_update_group_wait_time(struct cfqg_stats *stats)
493 {
494         u64 now;
495
496         if (!cfqg_stats_waiting(stats))
497                 return;
498
499         now = ktime_get_ns();
500         if (now > stats->start_group_wait_time)
501                 blkg_stat_add(&stats->group_wait_time,
502                               now - stats->start_group_wait_time);
503         cfqg_stats_clear_waiting(stats);
504 }
505
506 /* This should be called with the queue_lock held. */
507 static void cfqg_stats_set_start_group_wait_time(struct cfq_group *cfqg,
508                                                  struct cfq_group *curr_cfqg)
509 {
510         struct cfqg_stats *stats = &cfqg->stats;
511
512         if (cfqg_stats_waiting(stats))
513                 return;
514         if (cfqg == curr_cfqg)
515                 return;
516         stats->start_group_wait_time = ktime_get_ns();
517         cfqg_stats_mark_waiting(stats);
518 }
519
520 /* This should be called with the queue_lock held. */
521 static void cfqg_stats_end_empty_time(struct cfqg_stats *stats)
522 {
523         u64 now;
524
525         if (!cfqg_stats_empty(stats))
526                 return;
527
528         now = ktime_get_ns();
529         if (now > stats->start_empty_time)
530                 blkg_stat_add(&stats->empty_time,
531                               now - stats->start_empty_time);
532         cfqg_stats_clear_empty(stats);
533 }
534
535 static void cfqg_stats_update_dequeue(struct cfq_group *cfqg)
536 {
537         blkg_stat_add(&cfqg->stats.dequeue, 1);
538 }
539
540 static void cfqg_stats_set_start_empty_time(struct cfq_group *cfqg)
541 {
542         struct cfqg_stats *stats = &cfqg->stats;
543
544         if (blkg_rwstat_total(&stats->queued))
545                 return;
546
547         /*
548          * group is already marked empty. This can happen if cfqq got new
549          * request in parent group and moved to this group while being added
550          * to service tree. Just ignore the event and move on.
551          */
552         if (cfqg_stats_empty(stats))
553                 return;
554
555         stats->start_empty_time = ktime_get_ns();
556         cfqg_stats_mark_empty(stats);
557 }
558
559 static void cfqg_stats_update_idle_time(struct cfq_group *cfqg)
560 {
561         struct cfqg_stats *stats = &cfqg->stats;
562
563         if (cfqg_stats_idling(stats)) {
564                 u64 now = ktime_get_ns();
565
566                 if (now > stats->start_idle_time)
567                         blkg_stat_add(&stats->idle_time,
568                                       now - stats->start_idle_time);
569                 cfqg_stats_clear_idling(stats);
570         }
571 }
572
573 static void cfqg_stats_set_start_idle_time(struct cfq_group *cfqg)
574 {
575         struct cfqg_stats *stats = &cfqg->stats;
576
577         BUG_ON(cfqg_stats_idling(stats));
578
579         stats->start_idle_time = ktime_get_ns();
580         cfqg_stats_mark_idling(stats);
581 }
582
583 static void cfqg_stats_update_avg_queue_size(struct cfq_group *cfqg)
584 {
585         struct cfqg_stats *stats = &cfqg->stats;
586
587         blkg_stat_add(&stats->avg_queue_size_sum,
588                       blkg_rwstat_total(&stats->queued));
589         blkg_stat_add(&stats->avg_queue_size_samples, 1);
590         cfqg_stats_update_group_wait_time(stats);
591 }
592
593 #else   /* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */
594
595 static inline void cfqg_stats_set_start_group_wait_time(struct cfq_group *cfqg, struct cfq_group *curr_cfqg) { }
596 static inline void cfqg_stats_end_empty_time(struct cfqg_stats *stats) { }
597 static inline void cfqg_stats_update_dequeue(struct cfq_group *cfqg) { }
598 static inline void cfqg_stats_set_start_empty_time(struct cfq_group *cfqg) { }
599 static inline void cfqg_stats_update_idle_time(struct cfq_group *cfqg) { }
600 static inline void cfqg_stats_set_start_idle_time(struct cfq_group *cfqg) { }
601 static inline void cfqg_stats_update_avg_queue_size(struct cfq_group *cfqg) { }
602
603 #endif  /* CONFIG_CFQ_GROUP_IOSCHED && CONFIG_DEBUG_BLK_CGROUP */
604
605 #ifdef CONFIG_CFQ_GROUP_IOSCHED
606
607 static inline struct cfq_group *pd_to_cfqg(struct blkg_policy_data *pd)
608 {
609         return pd ? container_of(pd, struct cfq_group, pd) : NULL;
610 }
611
612 static struct cfq_group_data
613 *cpd_to_cfqgd(struct blkcg_policy_data *cpd)
614 {
615         return cpd ? container_of(cpd, struct cfq_group_data, cpd) : NULL;
616 }
617
618 static inline struct blkcg_gq *cfqg_to_blkg(struct cfq_group *cfqg)
619 {
620         return pd_to_blkg(&cfqg->pd);
621 }
622
623 static struct blkcg_policy blkcg_policy_cfq;
624
625 static inline struct cfq_group *blkg_to_cfqg(struct blkcg_gq *blkg)
626 {
627         return pd_to_cfqg(blkg_to_pd(blkg, &blkcg_policy_cfq));
628 }
629
630 static struct cfq_group_data *blkcg_to_cfqgd(struct blkcg *blkcg)
631 {
632         return cpd_to_cfqgd(blkcg_to_cpd(blkcg, &blkcg_policy_cfq));
633 }
634
635 static inline struct cfq_group *cfqg_parent(struct cfq_group *cfqg)
636 {
637         struct blkcg_gq *pblkg = cfqg_to_blkg(cfqg)->parent;
638
639         return pblkg ? blkg_to_cfqg(pblkg) : NULL;
640 }
641
642 static inline bool cfqg_is_descendant(struct cfq_group *cfqg,
643                                       struct cfq_group *ancestor)
644 {
645         return cgroup_is_descendant(cfqg_to_blkg(cfqg)->blkcg->css.cgroup,
646                                     cfqg_to_blkg(ancestor)->blkcg->css.cgroup);
647 }
648
649 static inline void cfqg_get(struct cfq_group *cfqg)
650 {
651         return blkg_get(cfqg_to_blkg(cfqg));
652 }
653
654 static inline void cfqg_put(struct cfq_group *cfqg)
655 {
656         return blkg_put(cfqg_to_blkg(cfqg));
657 }
658
659 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...)  do {                    \
660         blk_add_cgroup_trace_msg((cfqd)->queue,                         \
661                         cfqg_to_blkg((cfqq)->cfqg)->blkcg,              \
662                         "cfq%d%c%c " fmt, (cfqq)->pid,                  \
663                         cfq_cfqq_sync((cfqq)) ? 'S' : 'A',              \
664                         cfqq_type((cfqq)) == SYNC_NOIDLE_WORKLOAD ? 'N' : ' ',\
665                           ##args);                                      \
666 } while (0)
667
668 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...)  do {                    \
669         blk_add_cgroup_trace_msg((cfqd)->queue,                         \
670                         cfqg_to_blkg(cfqg)->blkcg, fmt, ##args);        \
671 } while (0)
672
673 static inline void cfqg_stats_update_io_add(struct cfq_group *cfqg,
674                                             struct cfq_group *curr_cfqg,
675                                             unsigned int op)
676 {
677         blkg_rwstat_add(&cfqg->stats.queued, op, 1);
678         cfqg_stats_end_empty_time(&cfqg->stats);
679         cfqg_stats_set_start_group_wait_time(cfqg, curr_cfqg);
680 }
681
682 static inline void cfqg_stats_update_timeslice_used(struct cfq_group *cfqg,
683                         uint64_t time, unsigned long unaccounted_time)
684 {
685         blkg_stat_add(&cfqg->stats.time, time);
686 #ifdef CONFIG_DEBUG_BLK_CGROUP
687         blkg_stat_add(&cfqg->stats.unaccounted_time, unaccounted_time);
688 #endif
689 }
690
691 static inline void cfqg_stats_update_io_remove(struct cfq_group *cfqg,
692                                                unsigned int op)
693 {
694         blkg_rwstat_add(&cfqg->stats.queued, op, -1);
695 }
696
697 static inline void cfqg_stats_update_io_merged(struct cfq_group *cfqg,
698                                                unsigned int op)
699 {
700         blkg_rwstat_add(&cfqg->stats.merged, op, 1);
701 }
702
703 static inline void cfqg_stats_update_completion(struct cfq_group *cfqg,
704                                                 u64 start_time_ns,
705                                                 u64 io_start_time_ns,
706                                                 unsigned int op)
707 {
708         struct cfqg_stats *stats = &cfqg->stats;
709         u64 now = ktime_get_ns();
710
711         if (now > io_start_time_ns)
712                 blkg_rwstat_add(&stats->service_time, op,
713                                 now - io_start_time_ns);
714         if (io_start_time_ns > start_time_ns)
715                 blkg_rwstat_add(&stats->wait_time, op,
716                                 io_start_time_ns - start_time_ns);
717 }
718
719 /* @stats = 0 */
720 static void cfqg_stats_reset(struct cfqg_stats *stats)
721 {
722         /* queued stats shouldn't be cleared */
723         blkg_rwstat_reset(&stats->merged);
724         blkg_rwstat_reset(&stats->service_time);
725         blkg_rwstat_reset(&stats->wait_time);
726         blkg_stat_reset(&stats->time);
727 #ifdef CONFIG_DEBUG_BLK_CGROUP
728         blkg_stat_reset(&stats->unaccounted_time);
729         blkg_stat_reset(&stats->avg_queue_size_sum);
730         blkg_stat_reset(&stats->avg_queue_size_samples);
731         blkg_stat_reset(&stats->dequeue);
732         blkg_stat_reset(&stats->group_wait_time);
733         blkg_stat_reset(&stats->idle_time);
734         blkg_stat_reset(&stats->empty_time);
735 #endif
736 }
737
738 /* @to += @from */
739 static void cfqg_stats_add_aux(struct cfqg_stats *to, struct cfqg_stats *from)
740 {
741         /* queued stats shouldn't be cleared */
742         blkg_rwstat_add_aux(&to->merged, &from->merged);
743         blkg_rwstat_add_aux(&to->service_time, &from->service_time);
744         blkg_rwstat_add_aux(&to->wait_time, &from->wait_time);
745         blkg_stat_add_aux(&from->time, &from->time);
746 #ifdef CONFIG_DEBUG_BLK_CGROUP
747         blkg_stat_add_aux(&to->unaccounted_time, &from->unaccounted_time);
748         blkg_stat_add_aux(&to->avg_queue_size_sum, &from->avg_queue_size_sum);
749         blkg_stat_add_aux(&to->avg_queue_size_samples, &from->avg_queue_size_samples);
750         blkg_stat_add_aux(&to->dequeue, &from->dequeue);
751         blkg_stat_add_aux(&to->group_wait_time, &from->group_wait_time);
752         blkg_stat_add_aux(&to->idle_time, &from->idle_time);
753         blkg_stat_add_aux(&to->empty_time, &from->empty_time);
754 #endif
755 }
756
757 /*
758  * Transfer @cfqg's stats to its parent's aux counts so that the ancestors'
759  * recursive stats can still account for the amount used by this cfqg after
760  * it's gone.
761  */
762 static void cfqg_stats_xfer_dead(struct cfq_group *cfqg)
763 {
764         struct cfq_group *parent = cfqg_parent(cfqg);
765
766         lockdep_assert_held(cfqg_to_blkg(cfqg)->q->queue_lock);
767
768         if (unlikely(!parent))
769                 return;
770
771         cfqg_stats_add_aux(&parent->stats, &cfqg->stats);
772         cfqg_stats_reset(&cfqg->stats);
773 }
774
775 #else   /* CONFIG_CFQ_GROUP_IOSCHED */
776
777 static inline struct cfq_group *cfqg_parent(struct cfq_group *cfqg) { return NULL; }
778 static inline bool cfqg_is_descendant(struct cfq_group *cfqg,
779                                       struct cfq_group *ancestor)
780 {
781         return true;
782 }
783 static inline void cfqg_get(struct cfq_group *cfqg) { }
784 static inline void cfqg_put(struct cfq_group *cfqg) { }
785
786 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...)  \
787         blk_add_trace_msg((cfqd)->queue, "cfq%d%c%c " fmt, (cfqq)->pid, \
788                         cfq_cfqq_sync((cfqq)) ? 'S' : 'A',              \
789                         cfqq_type((cfqq)) == SYNC_NOIDLE_WORKLOAD ? 'N' : ' ',\
790                                 ##args)
791 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...)          do {} while (0)
792
793 static inline void cfqg_stats_update_io_add(struct cfq_group *cfqg,
794                         struct cfq_group *curr_cfqg, unsigned int op) { }
795 static inline void cfqg_stats_update_timeslice_used(struct cfq_group *cfqg,
796                         uint64_t time, unsigned long unaccounted_time) { }
797 static inline void cfqg_stats_update_io_remove(struct cfq_group *cfqg,
798                         unsigned int op) { }
799 static inline void cfqg_stats_update_io_merged(struct cfq_group *cfqg,
800                         unsigned int op) { }
801 static inline void cfqg_stats_update_completion(struct cfq_group *cfqg,
802                                                 u64 start_time_ns,
803                                                 u64 io_start_time_ns,
804                                                 unsigned int op) { }
805
806 #endif  /* CONFIG_CFQ_GROUP_IOSCHED */
807
808 #define cfq_log(cfqd, fmt, args...)     \
809         blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
810
811 /* Traverses through cfq group service trees */
812 #define for_each_cfqg_st(cfqg, i, j, st) \
813         for (i = 0; i <= IDLE_WORKLOAD; i++) \
814                 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
815                         : &cfqg->service_tree_idle; \
816                         (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \
817                         (i == IDLE_WORKLOAD && j == 0); \
818                         j++, st = i < IDLE_WORKLOAD ? \
819                         &cfqg->service_trees[i][j]: NULL) \
820
821 static inline bool cfq_io_thinktime_big(struct cfq_data *cfqd,
822         struct cfq_ttime *ttime, bool group_idle)
823 {
824         u64 slice;
825         if (!sample_valid(ttime->ttime_samples))
826                 return false;
827         if (group_idle)
828                 slice = cfqd->cfq_group_idle;
829         else
830                 slice = cfqd->cfq_slice_idle;
831         return ttime->ttime_mean > slice;
832 }
833
834 static inline bool iops_mode(struct cfq_data *cfqd)
835 {
836         /*
837          * If we are not idling on queues and it is a NCQ drive, parallel
838          * execution of requests is on and measuring time is not possible
839          * in most of the cases until and unless we drive shallower queue
840          * depths and that becomes a performance bottleneck. In such cases
841          * switch to start providing fairness in terms of number of IOs.
842          */
843         if (!cfqd->cfq_slice_idle && cfqd->hw_tag)
844                 return true;
845         else
846                 return false;
847 }
848
849 static inline enum wl_class_t cfqq_class(struct cfq_queue *cfqq)
850 {
851         if (cfq_class_idle(cfqq))
852                 return IDLE_WORKLOAD;
853         if (cfq_class_rt(cfqq))
854                 return RT_WORKLOAD;
855         return BE_WORKLOAD;
856 }
857
858
859 static enum wl_type_t cfqq_type(struct cfq_queue *cfqq)
860 {
861         if (!cfq_cfqq_sync(cfqq))
862                 return ASYNC_WORKLOAD;
863         if (!cfq_cfqq_idle_window(cfqq))
864                 return SYNC_NOIDLE_WORKLOAD;
865         return SYNC_WORKLOAD;
866 }
867
868 static inline int cfq_group_busy_queues_wl(enum wl_class_t wl_class,
869                                         struct cfq_data *cfqd,
870                                         struct cfq_group *cfqg)
871 {
872         if (wl_class == IDLE_WORKLOAD)
873                 return cfqg->service_tree_idle.count;
874
875         return cfqg->service_trees[wl_class][ASYNC_WORKLOAD].count +
876                 cfqg->service_trees[wl_class][SYNC_NOIDLE_WORKLOAD].count +
877                 cfqg->service_trees[wl_class][SYNC_WORKLOAD].count;
878 }
879
880 static inline int cfqg_busy_async_queues(struct cfq_data *cfqd,
881                                         struct cfq_group *cfqg)
882 {
883         return cfqg->service_trees[RT_WORKLOAD][ASYNC_WORKLOAD].count +
884                 cfqg->service_trees[BE_WORKLOAD][ASYNC_WORKLOAD].count;
885 }
886
887 static void cfq_dispatch_insert(struct request_queue *, struct request *);
888 static struct cfq_queue *cfq_get_queue(struct cfq_data *cfqd, bool is_sync,
889                                        struct cfq_io_cq *cic, struct bio *bio);
890
891 static inline struct cfq_io_cq *icq_to_cic(struct io_cq *icq)
892 {
893         /* cic->icq is the first member, %NULL will convert to %NULL */
894         return container_of(icq, struct cfq_io_cq, icq);
895 }
896
897 static inline struct cfq_io_cq *cfq_cic_lookup(struct cfq_data *cfqd,
898                                                struct io_context *ioc)
899 {
900         if (ioc)
901                 return icq_to_cic(ioc_lookup_icq(ioc, cfqd->queue));
902         return NULL;
903 }
904
905 static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_cq *cic, bool is_sync)
906 {
907         return cic->cfqq[is_sync];
908 }
909
910 static inline void cic_set_cfqq(struct cfq_io_cq *cic, struct cfq_queue *cfqq,
911                                 bool is_sync)
912 {
913         cic->cfqq[is_sync] = cfqq;
914 }
915
916 static inline struct cfq_data *cic_to_cfqd(struct cfq_io_cq *cic)
917 {
918         return cic->icq.q->elevator->elevator_data;
919 }
920
921 /*
922  * scheduler run of queue, if there are requests pending and no one in the
923  * driver that will restart queueing
924  */
925 static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
926 {
927         if (cfqd->busy_queues) {
928                 cfq_log(cfqd, "schedule dispatch");
929                 kblockd_schedule_work(&cfqd->unplug_work);
930         }
931 }
932
933 /*
934  * Scale schedule slice based on io priority. Use the sync time slice only
935  * if a queue is marked sync and has sync io queued. A sync queue with async
936  * io only, should not get full sync slice length.
937  */
938 static inline u64 cfq_prio_slice(struct cfq_data *cfqd, bool sync,
939                                  unsigned short prio)
940 {
941         u64 base_slice = cfqd->cfq_slice[sync];
942         u64 slice = div_u64(base_slice, CFQ_SLICE_SCALE);
943
944         WARN_ON(prio >= IOPRIO_BE_NR);
945
946         return base_slice + (slice * (4 - prio));
947 }
948
949 static inline u64
950 cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
951 {
952         return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
953 }
954
955 /**
956  * cfqg_scale_charge - scale disk time charge according to cfqg weight
957  * @charge: disk time being charged
958  * @vfraction: vfraction of the cfqg, fixed point w/ CFQ_SERVICE_SHIFT
959  *
960  * Scale @charge according to @vfraction, which is in range (0, 1].  The
961  * scaling is inversely proportional.
962  *
963  * scaled = charge / vfraction
964  *
965  * The result is also in fixed point w/ CFQ_SERVICE_SHIFT.
966  */
967 static inline u64 cfqg_scale_charge(u64 charge,
968                                     unsigned int vfraction)
969 {
970         u64 c = charge << CFQ_SERVICE_SHIFT;    /* make it fixed point */
971
972         /* charge / vfraction */
973         c <<= CFQ_SERVICE_SHIFT;
974         return div_u64(c, vfraction);
975 }
976
977 static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime)
978 {
979         s64 delta = (s64)(vdisktime - min_vdisktime);
980         if (delta > 0)
981                 min_vdisktime = vdisktime;
982
983         return min_vdisktime;
984 }
985
986 static void update_min_vdisktime(struct cfq_rb_root *st)
987 {
988         if (!RB_EMPTY_ROOT(&st->rb.rb_root)) {
989                 struct cfq_group *cfqg = rb_entry_cfqg(st->rb.rb_leftmost);
990
991                 st->min_vdisktime = max_vdisktime(st->min_vdisktime,
992                                                   cfqg->vdisktime);
993         }
994 }
995
996 /*
997  * get averaged number of queues of RT/BE priority.
998  * average is updated, with a formula that gives more weight to higher numbers,
999  * to quickly follows sudden increases and decrease slowly
1000  */
1001
1002 static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd,
1003                                         struct cfq_group *cfqg, bool rt)
1004 {
1005         unsigned min_q, max_q;
1006         unsigned mult  = cfq_hist_divisor - 1;
1007         unsigned round = cfq_hist_divisor / 2;
1008         unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg);
1009
1010         min_q = min(cfqg->busy_queues_avg[rt], busy);
1011         max_q = max(cfqg->busy_queues_avg[rt], busy);
1012         cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) /
1013                 cfq_hist_divisor;
1014         return cfqg->busy_queues_avg[rt];
1015 }
1016
1017 static inline u64
1018 cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg)
1019 {
1020         return cfqd->cfq_target_latency * cfqg->vfraction >> CFQ_SERVICE_SHIFT;
1021 }
1022
1023 static inline u64
1024 cfq_scaled_cfqq_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1025 {
1026         u64 slice = cfq_prio_to_slice(cfqd, cfqq);
1027         if (cfqd->cfq_latency) {
1028                 /*
1029                  * interested queues (we consider only the ones with the same
1030                  * priority class in the cfq group)
1031                  */
1032                 unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg,
1033                                                 cfq_class_rt(cfqq));
1034                 u64 sync_slice = cfqd->cfq_slice[1];
1035                 u64 expect_latency = sync_slice * iq;
1036                 u64 group_slice = cfq_group_slice(cfqd, cfqq->cfqg);
1037
1038                 if (expect_latency > group_slice) {
1039                         u64 base_low_slice = 2 * cfqd->cfq_slice_idle;
1040                         u64 low_slice;
1041
1042                         /* scale low_slice according to IO priority
1043                          * and sync vs async */
1044                         low_slice = div64_u64(base_low_slice*slice, sync_slice);
1045                         low_slice = min(slice, low_slice);
1046                         /* the adapted slice value is scaled to fit all iqs
1047                          * into the target latency */
1048                         slice = div64_u64(slice*group_slice, expect_latency);
1049                         slice = max(slice, low_slice);
1050                 }
1051         }
1052         return slice;
1053 }
1054
1055 static inline void
1056 cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1057 {
1058         u64 slice = cfq_scaled_cfqq_slice(cfqd, cfqq);
1059         u64 now = ktime_get_ns();
1060
1061         cfqq->slice_start = now;
1062         cfqq->slice_end = now + slice;
1063         cfqq->allocated_slice = slice;
1064         cfq_log_cfqq(cfqd, cfqq, "set_slice=%llu", cfqq->slice_end - now);
1065 }
1066
1067 /*
1068  * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
1069  * isn't valid until the first request from the dispatch is activated
1070  * and the slice time set.
1071  */
1072 static inline bool cfq_slice_used(struct cfq_queue *cfqq)
1073 {
1074         if (cfq_cfqq_slice_new(cfqq))
1075                 return false;
1076         if (ktime_get_ns() < cfqq->slice_end)
1077                 return false;
1078
1079         return true;
1080 }
1081
1082 /*
1083  * Lifted from AS - choose which of rq1 and rq2 that is best served now.
1084  * We choose the request that is closest to the head right now. Distance
1085  * behind the head is penalized and only allowed to a certain extent.
1086  */
1087 static struct request *
1088 cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last)
1089 {
1090         sector_t s1, s2, d1 = 0, d2 = 0;
1091         unsigned long back_max;
1092 #define CFQ_RQ1_WRAP    0x01 /* request 1 wraps */
1093 #define CFQ_RQ2_WRAP    0x02 /* request 2 wraps */
1094         unsigned wrap = 0; /* bit mask: requests behind the disk head? */
1095
1096         if (rq1 == NULL || rq1 == rq2)
1097                 return rq2;
1098         if (rq2 == NULL)
1099                 return rq1;
1100
1101         if (rq_is_sync(rq1) != rq_is_sync(rq2))
1102                 return rq_is_sync(rq1) ? rq1 : rq2;
1103
1104         if ((rq1->cmd_flags ^ rq2->cmd_flags) & REQ_PRIO)
1105                 return rq1->cmd_flags & REQ_PRIO ? rq1 : rq2;
1106
1107         s1 = blk_rq_pos(rq1);
1108         s2 = blk_rq_pos(rq2);
1109
1110         /*
1111          * by definition, 1KiB is 2 sectors
1112          */
1113         back_max = cfqd->cfq_back_max * 2;
1114
1115         /*
1116          * Strict one way elevator _except_ in the case where we allow
1117          * short backward seeks which are biased as twice the cost of a
1118          * similar forward seek.
1119          */
1120         if (s1 >= last)
1121                 d1 = s1 - last;
1122         else if (s1 + back_max >= last)
1123                 d1 = (last - s1) * cfqd->cfq_back_penalty;
1124         else
1125                 wrap |= CFQ_RQ1_WRAP;
1126
1127         if (s2 >= last)
1128                 d2 = s2 - last;
1129         else if (s2 + back_max >= last)
1130                 d2 = (last - s2) * cfqd->cfq_back_penalty;
1131         else
1132                 wrap |= CFQ_RQ2_WRAP;
1133
1134         /* Found required data */
1135
1136         /*
1137          * By doing switch() on the bit mask "wrap" we avoid having to
1138          * check two variables for all permutations: --> faster!
1139          */
1140         switch (wrap) {
1141         case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
1142                 if (d1 < d2)
1143                         return rq1;
1144                 else if (d2 < d1)
1145                         return rq2;
1146                 else {
1147                         if (s1 >= s2)
1148                                 return rq1;
1149                         else
1150                                 return rq2;
1151                 }
1152
1153         case CFQ_RQ2_WRAP:
1154                 return rq1;
1155         case CFQ_RQ1_WRAP:
1156                 return rq2;
1157         case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */
1158         default:
1159                 /*
1160                  * Since both rqs are wrapped,
1161                  * start with the one that's further behind head
1162                  * (--> only *one* back seek required),
1163                  * since back seek takes more time than forward.
1164                  */
1165                 if (s1 <= s2)
1166                         return rq1;
1167                 else
1168                         return rq2;
1169         }
1170 }
1171
1172 static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
1173 {
1174         /* Service tree is empty */
1175         if (!root->count)
1176                 return NULL;
1177
1178         return rb_entry(rb_first_cached(&root->rb), struct cfq_queue, rb_node);
1179 }
1180
1181 static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root)
1182 {
1183         return rb_entry_cfqg(rb_first_cached(&root->rb));
1184 }
1185
1186 static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)
1187 {
1188         if (root->rb_rightmost == n)
1189                 root->rb_rightmost = rb_prev(n);
1190
1191         rb_erase_cached(n, &root->rb);
1192         RB_CLEAR_NODE(n);
1193
1194         --root->count;
1195 }
1196
1197 /*
1198  * would be nice to take fifo expire time into account as well
1199  */
1200 static struct request *
1201 cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1202                   struct request *last)
1203 {
1204         struct rb_node *rbnext = rb_next(&last->rb_node);
1205         struct rb_node *rbprev = rb_prev(&last->rb_node);
1206         struct request *next = NULL, *prev = NULL;
1207
1208         BUG_ON(RB_EMPTY_NODE(&last->rb_node));
1209
1210         if (rbprev)
1211                 prev = rb_entry_rq(rbprev);
1212
1213         if (rbnext)
1214                 next = rb_entry_rq(rbnext);
1215         else {
1216                 rbnext = rb_first(&cfqq->sort_list);
1217                 if (rbnext && rbnext != &last->rb_node)
1218                         next = rb_entry_rq(rbnext);
1219         }
1220
1221         return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last));
1222 }
1223
1224 static u64 cfq_slice_offset(struct cfq_data *cfqd,
1225                             struct cfq_queue *cfqq)
1226 {
1227         /*
1228          * just an approximation, should be ok.
1229          */
1230         return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) -
1231                        cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio));
1232 }
1233
1234 static inline s64
1235 cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg)
1236 {
1237         return cfqg->vdisktime - st->min_vdisktime;
1238 }
1239
1240 static void
1241 __cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
1242 {
1243         struct rb_node **node = &st->rb.rb_root.rb_node;
1244         struct rb_node *parent = NULL;
1245         struct cfq_group *__cfqg;
1246         s64 key = cfqg_key(st, cfqg);
1247         bool leftmost = true, rightmost = true;
1248
1249         while (*node != NULL) {
1250                 parent = *node;
1251                 __cfqg = rb_entry_cfqg(parent);
1252
1253                 if (key < cfqg_key(st, __cfqg)) {
1254                         node = &parent->rb_left;
1255                         rightmost = false;
1256                 } else {
1257                         node = &parent->rb_right;
1258                         leftmost = false;
1259                 }
1260         }
1261
1262         if (rightmost)
1263                 st->rb_rightmost = &cfqg->rb_node;
1264
1265         rb_link_node(&cfqg->rb_node, parent, node);
1266         rb_insert_color_cached(&cfqg->rb_node, &st->rb, leftmost);
1267 }
1268
1269 /*
1270  * This has to be called only on activation of cfqg
1271  */
1272 static void
1273 cfq_update_group_weight(struct cfq_group *cfqg)
1274 {
1275         if (cfqg->new_weight) {
1276                 cfqg->weight = cfqg->new_weight;
1277                 cfqg->new_weight = 0;
1278         }
1279 }
1280
1281 static void
1282 cfq_update_group_leaf_weight(struct cfq_group *cfqg)
1283 {
1284         BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
1285
1286         if (cfqg->new_leaf_weight) {
1287                 cfqg->leaf_weight = cfqg->new_leaf_weight;
1288                 cfqg->new_leaf_weight = 0;
1289         }
1290 }
1291
1292 static void
1293 cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
1294 {
1295         unsigned int vfr = 1 << CFQ_SERVICE_SHIFT;      /* start with 1 */
1296         struct cfq_group *pos = cfqg;
1297         struct cfq_group *parent;
1298         bool propagate;
1299
1300         /* add to the service tree */
1301         BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node));
1302
1303         /*
1304          * Update leaf_weight.  We cannot update weight at this point
1305          * because cfqg might already have been activated and is
1306          * contributing its current weight to the parent's child_weight.
1307          */
1308         cfq_update_group_leaf_weight(cfqg);
1309         __cfq_group_service_tree_add(st, cfqg);
1310
1311         /*
1312          * Activate @cfqg and calculate the portion of vfraction @cfqg is
1313          * entitled to.  vfraction is calculated by walking the tree
1314          * towards the root calculating the fraction it has at each level.
1315          * The compounded ratio is how much vfraction @cfqg owns.
1316          *
1317          * Start with the proportion tasks in this cfqg has against active
1318          * children cfqgs - its leaf_weight against children_weight.
1319          */
1320         propagate = !pos->nr_active++;
1321         pos->children_weight += pos->leaf_weight;
1322         vfr = vfr * pos->leaf_weight / pos->children_weight;
1323
1324         /*
1325          * Compound ->weight walking up the tree.  Both activation and
1326          * vfraction calculation are done in the same loop.  Propagation
1327          * stops once an already activated node is met.  vfraction
1328          * calculation should always continue to the root.
1329          */
1330         while ((parent = cfqg_parent(pos))) {
1331                 if (propagate) {
1332                         cfq_update_group_weight(pos);
1333                         propagate = !parent->nr_active++;
1334                         parent->children_weight += pos->weight;
1335                 }
1336                 vfr = vfr * pos->weight / parent->children_weight;
1337                 pos = parent;
1338         }
1339
1340         cfqg->vfraction = max_t(unsigned, vfr, 1);
1341 }
1342
1343 static inline u64 cfq_get_cfqg_vdisktime_delay(struct cfq_data *cfqd)
1344 {
1345         if (!iops_mode(cfqd))
1346                 return CFQ_SLICE_MODE_GROUP_DELAY;
1347         else
1348                 return CFQ_IOPS_MODE_GROUP_DELAY;
1349 }
1350
1351 static void
1352 cfq_group_notify_queue_add(struct cfq_data *cfqd, struct cfq_group *cfqg)
1353 {
1354         struct cfq_rb_root *st = &cfqd->grp_service_tree;
1355         struct cfq_group *__cfqg;
1356         struct rb_node *n;
1357
1358         cfqg->nr_cfqq++;
1359         if (!RB_EMPTY_NODE(&cfqg->rb_node))
1360                 return;
1361
1362         /*
1363          * Currently put the group at the end. Later implement something
1364          * so that groups get lesser vtime based on their weights, so that
1365          * if group does not loose all if it was not continuously backlogged.
1366          */
1367         n = st->rb_rightmost;
1368         if (n) {
1369                 __cfqg = rb_entry_cfqg(n);
1370                 cfqg->vdisktime = __cfqg->vdisktime +
1371                         cfq_get_cfqg_vdisktime_delay(cfqd);
1372         } else
1373                 cfqg->vdisktime = st->min_vdisktime;
1374         cfq_group_service_tree_add(st, cfqg);
1375 }
1376
1377 static void
1378 cfq_group_service_tree_del(struct cfq_rb_root *st, struct cfq_group *cfqg)
1379 {
1380         struct cfq_group *pos = cfqg;
1381         bool propagate;
1382
1383         /*
1384          * Undo activation from cfq_group_service_tree_add().  Deactivate
1385          * @cfqg and propagate deactivation upwards.
1386          */
1387         propagate = !--pos->nr_active;
1388         pos->children_weight -= pos->leaf_weight;
1389
1390         while (propagate) {
1391                 struct cfq_group *parent = cfqg_parent(pos);
1392
1393                 /* @pos has 0 nr_active at this point */
1394                 WARN_ON_ONCE(pos->children_weight);
1395                 pos->vfraction = 0;
1396
1397                 if (!parent)
1398                         break;
1399
1400                 propagate = !--parent->nr_active;
1401                 parent->children_weight -= pos->weight;
1402                 pos = parent;
1403         }
1404
1405         /* remove from the service tree */
1406         if (!RB_EMPTY_NODE(&cfqg->rb_node))
1407                 cfq_rb_erase(&cfqg->rb_node, st);
1408 }
1409
1410 static void
1411 cfq_group_notify_queue_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
1412 {
1413         struct cfq_rb_root *st = &cfqd->grp_service_tree;
1414
1415         BUG_ON(cfqg->nr_cfqq < 1);
1416         cfqg->nr_cfqq--;
1417
1418         /* If there are other cfq queues under this group, don't delete it */
1419         if (cfqg->nr_cfqq)
1420                 return;
1421
1422         cfq_log_cfqg(cfqd, cfqg, "del_from_rr group");
1423         cfq_group_service_tree_del(st, cfqg);
1424         cfqg->saved_wl_slice = 0;
1425         cfqg_stats_update_dequeue(cfqg);
1426 }
1427
1428 static inline u64 cfq_cfqq_slice_usage(struct cfq_queue *cfqq,
1429                                        u64 *unaccounted_time)
1430 {
1431         u64 slice_used;
1432         u64 now = ktime_get_ns();
1433
1434         /*
1435          * Queue got expired before even a single request completed or
1436          * got expired immediately after first request completion.
1437          */
1438         if (!cfqq->slice_start || cfqq->slice_start == now) {
1439                 /*
1440                  * Also charge the seek time incurred to the group, otherwise
1441                  * if there are mutiple queues in the group, each can dispatch
1442                  * a single request on seeky media and cause lots of seek time
1443                  * and group will never know it.
1444                  */
1445                 slice_used = max_t(u64, (now - cfqq->dispatch_start),
1446                                         jiffies_to_nsecs(1));
1447         } else {
1448                 slice_used = now - cfqq->slice_start;
1449                 if (slice_used > cfqq->allocated_slice) {
1450                         *unaccounted_time = slice_used - cfqq->allocated_slice;
1451                         slice_used = cfqq->allocated_slice;
1452                 }
1453                 if (cfqq->slice_start > cfqq->dispatch_start)
1454                         *unaccounted_time += cfqq->slice_start -
1455                                         cfqq->dispatch_start;
1456         }
1457
1458         return slice_used;
1459 }
1460
1461 static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
1462                                 struct cfq_queue *cfqq)
1463 {
1464         struct cfq_rb_root *st = &cfqd->grp_service_tree;
1465         u64 used_sl, charge, unaccounted_sl = 0;
1466         int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg)
1467                         - cfqg->service_tree_idle.count;
1468         unsigned int vfr;
1469         u64 now = ktime_get_ns();
1470
1471         BUG_ON(nr_sync < 0);
1472         used_sl = charge = cfq_cfqq_slice_usage(cfqq, &unaccounted_sl);
1473
1474         if (iops_mode(cfqd))
1475                 charge = cfqq->slice_dispatch;
1476         else if (!cfq_cfqq_sync(cfqq) && !nr_sync)
1477                 charge = cfqq->allocated_slice;
1478
1479         /*
1480          * Can't update vdisktime while on service tree and cfqg->vfraction
1481          * is valid only while on it.  Cache vfr, leave the service tree,
1482          * update vdisktime and go back on.  The re-addition to the tree
1483          * will also update the weights as necessary.
1484          */
1485         vfr = cfqg->vfraction;
1486         cfq_group_service_tree_del(st, cfqg);
1487         cfqg->vdisktime += cfqg_scale_charge(charge, vfr);
1488         cfq_group_service_tree_add(st, cfqg);
1489
1490         /* This group is being expired. Save the context */
1491         if (cfqd->workload_expires > now) {
1492                 cfqg->saved_wl_slice = cfqd->workload_expires - now;
1493                 cfqg->saved_wl_type = cfqd->serving_wl_type;
1494                 cfqg->saved_wl_class = cfqd->serving_wl_class;
1495         } else
1496                 cfqg->saved_wl_slice = 0;
1497
1498         cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime,
1499                                         st->min_vdisktime);
1500         cfq_log_cfqq(cfqq->cfqd, cfqq,
1501                      "sl_used=%llu disp=%llu charge=%llu iops=%u sect=%lu",
1502                      used_sl, cfqq->slice_dispatch, charge,
1503                      iops_mode(cfqd), cfqq->nr_sectors);
1504         cfqg_stats_update_timeslice_used(cfqg, used_sl, unaccounted_sl);
1505         cfqg_stats_set_start_empty_time(cfqg);
1506 }
1507
1508 /**
1509  * cfq_init_cfqg_base - initialize base part of a cfq_group
1510  * @cfqg: cfq_group to initialize
1511  *
1512  * Initialize the base part which is used whether %CONFIG_CFQ_GROUP_IOSCHED
1513  * is enabled or not.
1514  */
1515 static void cfq_init_cfqg_base(struct cfq_group *cfqg)
1516 {
1517         struct cfq_rb_root *st;
1518         int i, j;
1519
1520         for_each_cfqg_st(cfqg, i, j, st)
1521                 *st = CFQ_RB_ROOT;
1522         RB_CLEAR_NODE(&cfqg->rb_node);
1523
1524         cfqg->ttime.last_end_request = ktime_get_ns();
1525 }
1526
1527 #ifdef CONFIG_CFQ_GROUP_IOSCHED
1528 static int __cfq_set_weight(struct cgroup_subsys_state *css, u64 val,
1529                             bool on_dfl, bool reset_dev, bool is_leaf_weight);
1530
1531 static void cfqg_stats_exit(struct cfqg_stats *stats)
1532 {
1533         blkg_rwstat_exit(&stats->merged);
1534         blkg_rwstat_exit(&stats->service_time);
1535         blkg_rwstat_exit(&stats->wait_time);
1536         blkg_rwstat_exit(&stats->queued);
1537         blkg_stat_exit(&stats->time);
1538 #ifdef CONFIG_DEBUG_BLK_CGROUP
1539         blkg_stat_exit(&stats->unaccounted_time);
1540         blkg_stat_exit(&stats->avg_queue_size_sum);
1541         blkg_stat_exit(&stats->avg_queue_size_samples);
1542         blkg_stat_exit(&stats->dequeue);
1543         blkg_stat_exit(&stats->group_wait_time);
1544         blkg_stat_exit(&stats->idle_time);
1545         blkg_stat_exit(&stats->empty_time);
1546 #endif
1547 }
1548
1549 static int cfqg_stats_init(struct cfqg_stats *stats, gfp_t gfp)
1550 {
1551         if (blkg_rwstat_init(&stats->merged, gfp) ||
1552             blkg_rwstat_init(&stats->service_time, gfp) ||
1553             blkg_rwstat_init(&stats->wait_time, gfp) ||
1554             blkg_rwstat_init(&stats->queued, gfp) ||
1555             blkg_stat_init(&stats->time, gfp))
1556                 goto err;
1557
1558 #ifdef CONFIG_DEBUG_BLK_CGROUP
1559         if (blkg_stat_init(&stats->unaccounted_time, gfp) ||
1560             blkg_stat_init(&stats->avg_queue_size_sum, gfp) ||
1561             blkg_stat_init(&stats->avg_queue_size_samples, gfp) ||
1562             blkg_stat_init(&stats->dequeue, gfp) ||
1563             blkg_stat_init(&stats->group_wait_time, gfp) ||
1564             blkg_stat_init(&stats->idle_time, gfp) ||
1565             blkg_stat_init(&stats->empty_time, gfp))
1566                 goto err;
1567 #endif
1568         return 0;
1569 err:
1570         cfqg_stats_exit(stats);
1571         return -ENOMEM;
1572 }
1573
1574 static struct blkcg_policy_data *cfq_cpd_alloc(gfp_t gfp)
1575 {
1576         struct cfq_group_data *cgd;
1577
1578         cgd = kzalloc(sizeof(*cgd), gfp);
1579         if (!cgd)
1580                 return NULL;
1581         return &cgd->cpd;
1582 }
1583
1584 static void cfq_cpd_init(struct blkcg_policy_data *cpd)
1585 {
1586         struct cfq_group_data *cgd = cpd_to_cfqgd(cpd);
1587         unsigned int weight = cgroup_subsys_on_dfl(io_cgrp_subsys) ?
1588                               CGROUP_WEIGHT_DFL : CFQ_WEIGHT_LEGACY_DFL;
1589
1590         if (cpd_to_blkcg(cpd) == &blkcg_root)
1591                 weight *= 2;
1592
1593         cgd->weight = weight;
1594         cgd->leaf_weight = weight;
1595 }
1596
1597 static void cfq_cpd_free(struct blkcg_policy_data *cpd)
1598 {
1599         kfree(cpd_to_cfqgd(cpd));
1600 }
1601
1602 static void cfq_cpd_bind(struct blkcg_policy_data *cpd)
1603 {
1604         struct blkcg *blkcg = cpd_to_blkcg(cpd);
1605         bool on_dfl = cgroup_subsys_on_dfl(io_cgrp_subsys);
1606         unsigned int weight = on_dfl ? CGROUP_WEIGHT_DFL : CFQ_WEIGHT_LEGACY_DFL;
1607
1608         if (blkcg == &blkcg_root)
1609                 weight *= 2;
1610
1611         WARN_ON_ONCE(__cfq_set_weight(&blkcg->css, weight, on_dfl, true, false));
1612         WARN_ON_ONCE(__cfq_set_weight(&blkcg->css, weight, on_dfl, true, true));
1613 }
1614
1615 static struct blkg_policy_data *cfq_pd_alloc(gfp_t gfp, int node)
1616 {
1617         struct cfq_group *cfqg;
1618
1619         cfqg = kzalloc_node(sizeof(*cfqg), gfp, node);
1620         if (!cfqg)
1621                 return NULL;
1622
1623         cfq_init_cfqg_base(cfqg);
1624         if (cfqg_stats_init(&cfqg->stats, gfp)) {
1625                 kfree(cfqg);
1626                 return NULL;
1627         }
1628
1629         return &cfqg->pd;
1630 }
1631
1632 static void cfq_pd_init(struct blkg_policy_data *pd)
1633 {
1634         struct cfq_group *cfqg = pd_to_cfqg(pd);
1635         struct cfq_group_data *cgd = blkcg_to_cfqgd(pd->blkg->blkcg);
1636
1637         cfqg->weight = cgd->weight;
1638         cfqg->leaf_weight = cgd->leaf_weight;
1639 }
1640
1641 static void cfq_pd_offline(struct blkg_policy_data *pd)
1642 {
1643         struct cfq_group *cfqg = pd_to_cfqg(pd);
1644         int i;
1645
1646         for (i = 0; i < IOPRIO_BE_NR; i++) {
1647                 if (cfqg->async_cfqq[0][i]) {
1648                         cfq_put_queue(cfqg->async_cfqq[0][i]);
1649                         cfqg->async_cfqq[0][i] = NULL;
1650                 }
1651                 if (cfqg->async_cfqq[1][i]) {
1652                         cfq_put_queue(cfqg->async_cfqq[1][i]);
1653                         cfqg->async_cfqq[1][i] = NULL;
1654                 }
1655         }
1656
1657         if (cfqg->async_idle_cfqq) {
1658                 cfq_put_queue(cfqg->async_idle_cfqq);
1659                 cfqg->async_idle_cfqq = NULL;
1660         }
1661
1662         /*
1663          * @blkg is going offline and will be ignored by
1664          * blkg_[rw]stat_recursive_sum().  Transfer stats to the parent so
1665          * that they don't get lost.  If IOs complete after this point, the
1666          * stats for them will be lost.  Oh well...
1667          */
1668         cfqg_stats_xfer_dead(cfqg);
1669 }
1670
1671 static void cfq_pd_free(struct blkg_policy_data *pd)
1672 {
1673         struct cfq_group *cfqg = pd_to_cfqg(pd);
1674
1675         cfqg_stats_exit(&cfqg->stats);
1676         return kfree(cfqg);
1677 }
1678
1679 static void cfq_pd_reset_stats(struct blkg_policy_data *pd)
1680 {
1681         struct cfq_group *cfqg = pd_to_cfqg(pd);
1682
1683         cfqg_stats_reset(&cfqg->stats);
1684 }
1685
1686 static struct cfq_group *cfq_lookup_cfqg(struct cfq_data *cfqd,
1687                                          struct blkcg *blkcg)
1688 {
1689         struct blkcg_gq *blkg;
1690
1691         blkg = blkg_lookup(blkcg, cfqd->queue);
1692         if (likely(blkg))
1693                 return blkg_to_cfqg(blkg);
1694         return NULL;
1695 }
1696
1697 static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg)
1698 {
1699         cfqq->cfqg = cfqg;
1700         /* cfqq reference on cfqg */
1701         cfqg_get(cfqg);
1702 }
1703
1704 static u64 cfqg_prfill_weight_device(struct seq_file *sf,
1705                                      struct blkg_policy_data *pd, int off)
1706 {
1707         struct cfq_group *cfqg = pd_to_cfqg(pd);
1708
1709         if (!cfqg->dev_weight)
1710                 return 0;
1711         return __blkg_prfill_u64(sf, pd, cfqg->dev_weight);
1712 }
1713
1714 static int cfqg_print_weight_device(struct seq_file *sf, void *v)
1715 {
1716         blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1717                           cfqg_prfill_weight_device, &blkcg_policy_cfq,
1718                           0, false);
1719         return 0;
1720 }
1721
1722 static u64 cfqg_prfill_leaf_weight_device(struct seq_file *sf,
1723                                           struct blkg_policy_data *pd, int off)
1724 {
1725         struct cfq_group *cfqg = pd_to_cfqg(pd);
1726
1727         if (!cfqg->dev_leaf_weight)
1728                 return 0;
1729         return __blkg_prfill_u64(sf, pd, cfqg->dev_leaf_weight);
1730 }
1731
1732 static int cfqg_print_leaf_weight_device(struct seq_file *sf, void *v)
1733 {
1734         blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1735                           cfqg_prfill_leaf_weight_device, &blkcg_policy_cfq,
1736                           0, false);
1737         return 0;
1738 }
1739
1740 static int cfq_print_weight(struct seq_file *sf, void *v)
1741 {
1742         struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
1743         struct cfq_group_data *cgd = blkcg_to_cfqgd(blkcg);
1744         unsigned int val = 0;
1745
1746         if (cgd)
1747                 val = cgd->weight;
1748
1749         seq_printf(sf, "%u\n", val);
1750         return 0;
1751 }
1752
1753 static int cfq_print_leaf_weight(struct seq_file *sf, void *v)
1754 {
1755         struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
1756         struct cfq_group_data *cgd = blkcg_to_cfqgd(blkcg);
1757         unsigned int val = 0;
1758
1759         if (cgd)
1760                 val = cgd->leaf_weight;
1761
1762         seq_printf(sf, "%u\n", val);
1763         return 0;
1764 }
1765
1766 static ssize_t __cfqg_set_weight_device(struct kernfs_open_file *of,
1767                                         char *buf, size_t nbytes, loff_t off,
1768                                         bool on_dfl, bool is_leaf_weight)
1769 {
1770         unsigned int min = on_dfl ? CGROUP_WEIGHT_MIN : CFQ_WEIGHT_LEGACY_MIN;
1771         unsigned int max = on_dfl ? CGROUP_WEIGHT_MAX : CFQ_WEIGHT_LEGACY_MAX;
1772         struct blkcg *blkcg = css_to_blkcg(of_css(of));
1773         struct blkg_conf_ctx ctx;
1774         struct cfq_group *cfqg;
1775         struct cfq_group_data *cfqgd;
1776         int ret;
1777         u64 v;
1778
1779         ret = blkg_conf_prep(blkcg, &blkcg_policy_cfq, buf, &ctx);
1780         if (ret)
1781                 return ret;
1782
1783         if (sscanf(ctx.body, "%llu", &v) == 1) {
1784                 /* require "default" on dfl */
1785                 ret = -ERANGE;
1786                 if (!v && on_dfl)
1787                         goto out_finish;
1788         } else if (!strcmp(strim(ctx.body), "default")) {
1789                 v = 0;
1790         } else {
1791                 ret = -EINVAL;
1792                 goto out_finish;
1793         }
1794
1795         cfqg = blkg_to_cfqg(ctx.blkg);
1796         cfqgd = blkcg_to_cfqgd(blkcg);
1797
1798         ret = -ERANGE;
1799         if (!v || (v >= min && v <= max)) {
1800                 if (!is_leaf_weight) {
1801                         cfqg->dev_weight = v;
1802                         cfqg->new_weight = v ?: cfqgd->weight;
1803                 } else {
1804                         cfqg->dev_leaf_weight = v;
1805                         cfqg->new_leaf_weight = v ?: cfqgd->leaf_weight;
1806                 }
1807                 ret = 0;
1808         }
1809 out_finish:
1810         blkg_conf_finish(&ctx);
1811         return ret ?: nbytes;
1812 }
1813
1814 static ssize_t cfqg_set_weight_device(struct kernfs_open_file *of,
1815                                       char *buf, size_t nbytes, loff_t off)
1816 {
1817         return __cfqg_set_weight_device(of, buf, nbytes, off, false, false);
1818 }
1819
1820 static ssize_t cfqg_set_leaf_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, true);
1824 }
1825
1826 static int __cfq_set_weight(struct cgroup_subsys_state *css, u64 val,
1827                             bool on_dfl, bool reset_dev, bool is_leaf_weight)
1828 {
1829         unsigned int min = on_dfl ? CGROUP_WEIGHT_MIN : CFQ_WEIGHT_LEGACY_MIN;
1830         unsigned int max = on_dfl ? CGROUP_WEIGHT_MAX : CFQ_WEIGHT_LEGACY_MAX;
1831         struct blkcg *blkcg = css_to_blkcg(css);
1832         struct blkcg_gq *blkg;
1833         struct cfq_group_data *cfqgd;
1834         int ret = 0;
1835
1836         if (val < min || val > max)
1837                 return -ERANGE;
1838
1839         spin_lock_irq(&blkcg->lock);
1840         cfqgd = blkcg_to_cfqgd(blkcg);
1841         if (!cfqgd) {
1842                 ret = -EINVAL;
1843                 goto out;
1844         }
1845
1846         if (!is_leaf_weight)
1847                 cfqgd->weight = val;
1848         else
1849                 cfqgd->leaf_weight = val;
1850
1851         hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) {
1852                 struct cfq_group *cfqg = blkg_to_cfqg(blkg);
1853
1854                 if (!cfqg)
1855                         continue;
1856
1857                 if (!is_leaf_weight) {
1858                         if (reset_dev)
1859                                 cfqg->dev_weight = 0;
1860                         if (!cfqg->dev_weight)
1861                                 cfqg->new_weight = cfqgd->weight;
1862                 } else {
1863                         if (reset_dev)
1864                                 cfqg->dev_leaf_weight = 0;
1865                         if (!cfqg->dev_leaf_weight)
1866                                 cfqg->new_leaf_weight = cfqgd->leaf_weight;
1867                 }
1868         }
1869
1870 out:
1871         spin_unlock_irq(&blkcg->lock);
1872         return ret;
1873 }
1874
1875 static int cfq_set_weight(struct cgroup_subsys_state *css, struct cftype *cft,
1876                           u64 val)
1877 {
1878         return __cfq_set_weight(css, val, false, false, false);
1879 }
1880
1881 static int cfq_set_leaf_weight(struct cgroup_subsys_state *css,
1882                                struct cftype *cft, u64 val)
1883 {
1884         return __cfq_set_weight(css, val, false, false, true);
1885 }
1886
1887 static int cfqg_print_stat(struct seq_file *sf, void *v)
1888 {
1889         blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_stat,
1890                           &blkcg_policy_cfq, seq_cft(sf)->private, false);
1891         return 0;
1892 }
1893
1894 static int cfqg_print_rwstat(struct seq_file *sf, void *v)
1895 {
1896         blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)), blkg_prfill_rwstat,
1897                           &blkcg_policy_cfq, seq_cft(sf)->private, true);
1898         return 0;
1899 }
1900
1901 static u64 cfqg_prfill_stat_recursive(struct seq_file *sf,
1902                                       struct blkg_policy_data *pd, int off)
1903 {
1904         u64 sum = blkg_stat_recursive_sum(pd_to_blkg(pd),
1905                                           &blkcg_policy_cfq, off);
1906         return __blkg_prfill_u64(sf, pd, sum);
1907 }
1908
1909 static u64 cfqg_prfill_rwstat_recursive(struct seq_file *sf,
1910                                         struct blkg_policy_data *pd, int off)
1911 {
1912         struct blkg_rwstat sum = blkg_rwstat_recursive_sum(pd_to_blkg(pd),
1913                                                         &blkcg_policy_cfq, off);
1914         return __blkg_prfill_rwstat(sf, pd, &sum);
1915 }
1916
1917 static int cfqg_print_stat_recursive(struct seq_file *sf, void *v)
1918 {
1919         blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1920                           cfqg_prfill_stat_recursive, &blkcg_policy_cfq,
1921                           seq_cft(sf)->private, false);
1922         return 0;
1923 }
1924
1925 static int cfqg_print_rwstat_recursive(struct seq_file *sf, void *v)
1926 {
1927         blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1928                           cfqg_prfill_rwstat_recursive, &blkcg_policy_cfq,
1929                           seq_cft(sf)->private, true);
1930         return 0;
1931 }
1932
1933 static u64 cfqg_prfill_sectors(struct seq_file *sf, struct blkg_policy_data *pd,
1934                                int off)
1935 {
1936         u64 sum = blkg_rwstat_total(&pd->blkg->stat_bytes);
1937
1938         return __blkg_prfill_u64(sf, pd, sum >> 9);
1939 }
1940
1941 static int cfqg_print_stat_sectors(struct seq_file *sf, void *v)
1942 {
1943         blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1944                           cfqg_prfill_sectors, &blkcg_policy_cfq, 0, false);
1945         return 0;
1946 }
1947
1948 static u64 cfqg_prfill_sectors_recursive(struct seq_file *sf,
1949                                          struct blkg_policy_data *pd, int off)
1950 {
1951         struct blkg_rwstat tmp = blkg_rwstat_recursive_sum(pd->blkg, NULL,
1952                                         offsetof(struct blkcg_gq, stat_bytes));
1953         u64 sum = atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_READ]) +
1954                 atomic64_read(&tmp.aux_cnt[BLKG_RWSTAT_WRITE]);
1955
1956         return __blkg_prfill_u64(sf, pd, sum >> 9);
1957 }
1958
1959 static int cfqg_print_stat_sectors_recursive(struct seq_file *sf, void *v)
1960 {
1961         blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1962                           cfqg_prfill_sectors_recursive, &blkcg_policy_cfq, 0,
1963                           false);
1964         return 0;
1965 }
1966
1967 #ifdef CONFIG_DEBUG_BLK_CGROUP
1968 static u64 cfqg_prfill_avg_queue_size(struct seq_file *sf,
1969                                       struct blkg_policy_data *pd, int off)
1970 {
1971         struct cfq_group *cfqg = pd_to_cfqg(pd);
1972         u64 samples = blkg_stat_read(&cfqg->stats.avg_queue_size_samples);
1973         u64 v = 0;
1974
1975         if (samples) {
1976                 v = blkg_stat_read(&cfqg->stats.avg_queue_size_sum);
1977                 v = div64_u64(v, samples);
1978         }
1979         __blkg_prfill_u64(sf, pd, v);
1980         return 0;
1981 }
1982
1983 /* print avg_queue_size */
1984 static int cfqg_print_avg_queue_size(struct seq_file *sf, void *v)
1985 {
1986         blkcg_print_blkgs(sf, css_to_blkcg(seq_css(sf)),
1987                           cfqg_prfill_avg_queue_size, &blkcg_policy_cfq,
1988                           0, false);
1989         return 0;
1990 }
1991 #endif  /* CONFIG_DEBUG_BLK_CGROUP */
1992
1993 static struct cftype cfq_blkcg_legacy_files[] = {
1994         /* on root, weight is mapped to leaf_weight */
1995         {
1996                 .name = "weight_device",
1997                 .flags = CFTYPE_ONLY_ON_ROOT,
1998                 .seq_show = cfqg_print_leaf_weight_device,
1999                 .write = cfqg_set_leaf_weight_device,
2000         },
2001         {
2002                 .name = "weight",
2003                 .flags = CFTYPE_ONLY_ON_ROOT,
2004                 .seq_show = cfq_print_leaf_weight,
2005                 .write_u64 = cfq_set_leaf_weight,
2006         },
2007
2008         /* no such mapping necessary for !roots */
2009         {
2010                 .name = "weight_device",
2011                 .flags = CFTYPE_NOT_ON_ROOT,
2012                 .seq_show = cfqg_print_weight_device,
2013                 .write = cfqg_set_weight_device,
2014         },
2015         {
2016                 .name = "weight",
2017                 .flags = CFTYPE_NOT_ON_ROOT,
2018                 .seq_show = cfq_print_weight,
2019                 .write_u64 = cfq_set_weight,
2020         },
2021
2022         {
2023                 .name = "leaf_weight_device",
2024                 .seq_show = cfqg_print_leaf_weight_device,
2025                 .write = cfqg_set_leaf_weight_device,
2026         },
2027         {
2028                 .name = "leaf_weight",
2029                 .seq_show = cfq_print_leaf_weight,
2030                 .write_u64 = cfq_set_leaf_weight,
2031         },
2032
2033         /* statistics, covers only the tasks in the cfqg */
2034         {
2035                 .name = "time",
2036                 .private = offsetof(struct cfq_group, stats.time),
2037                 .seq_show = cfqg_print_stat,
2038         },
2039         {
2040                 .name = "sectors",
2041                 .seq_show = cfqg_print_stat_sectors,
2042         },
2043         {
2044                 .name = "io_service_bytes",
2045                 .private = (unsigned long)&blkcg_policy_cfq,
2046                 .seq_show = blkg_print_stat_bytes,
2047         },
2048         {
2049                 .name = "io_serviced",
2050                 .private = (unsigned long)&blkcg_policy_cfq,
2051                 .seq_show = blkg_print_stat_ios,
2052         },
2053         {
2054                 .name = "io_service_time",
2055                 .private = offsetof(struct cfq_group, stats.service_time),
2056                 .seq_show = cfqg_print_rwstat,
2057         },
2058         {
2059                 .name = "io_wait_time",
2060                 .private = offsetof(struct cfq_group, stats.wait_time),
2061                 .seq_show = cfqg_print_rwstat,
2062         },
2063         {
2064                 .name = "io_merged",
2065                 .private = offsetof(struct cfq_group, stats.merged),
2066                 .seq_show = cfqg_print_rwstat,
2067         },
2068         {
2069                 .name = "io_queued",
2070                 .private = offsetof(struct cfq_group, stats.queued),
2071                 .seq_show = cfqg_print_rwstat,
2072         },
2073
2074         /* the same statictics which cover the cfqg and its descendants */
2075         {
2076                 .name = "time_recursive",
2077                 .private = offsetof(struct cfq_group, stats.time),
2078                 .seq_show = cfqg_print_stat_recursive,
2079         },
2080         {
2081                 .name = "sectors_recursive",
2082                 .seq_show = cfqg_print_stat_sectors_recursive,
2083         },
2084         {
2085                 .name = "io_service_bytes_recursive",
2086                 .private = (unsigned long)&blkcg_policy_cfq,
2087                 .seq_show = blkg_print_stat_bytes_recursive,
2088         },
2089         {
2090                 .name = "io_serviced_recursive",
2091                 .private = (unsigned long)&blkcg_policy_cfq,
2092                 .seq_show = blkg_print_stat_ios_recursive,
2093         },
2094         {
2095                 .name = "io_service_time_recursive",
2096                 .private = offsetof(struct cfq_group, stats.service_time),
2097                 .seq_show = cfqg_print_rwstat_recursive,
2098         },
2099         {
2100                 .name = "io_wait_time_recursive",
2101                 .private = offsetof(struct cfq_group, stats.wait_time),
2102                 .seq_show = cfqg_print_rwstat_recursive,
2103         },
2104         {
2105                 .name = "io_merged_recursive",
2106                 .private = offsetof(struct cfq_group, stats.merged),
2107                 .seq_show = cfqg_print_rwstat_recursive,
2108         },
2109         {
2110                 .name = "io_queued_recursive",
2111                 .private = offsetof(struct cfq_group, stats.queued),
2112                 .seq_show = cfqg_print_rwstat_recursive,
2113         },
2114 #ifdef CONFIG_DEBUG_BLK_CGROUP
2115         {
2116                 .name = "avg_queue_size",
2117                 .seq_show = cfqg_print_avg_queue_size,
2118         },
2119         {
2120                 .name = "group_wait_time",
2121                 .private = offsetof(struct cfq_group, stats.group_wait_time),
2122                 .seq_show = cfqg_print_stat,
2123         },
2124         {
2125                 .name = "idle_time",
2126                 .private = offsetof(struct cfq_group, stats.idle_time),
2127                 .seq_show = cfqg_print_stat,
2128         },
2129         {
2130                 .name = "empty_time",
2131                 .private = offsetof(struct cfq_group, stats.empty_time),
2132                 .seq_show = cfqg_print_stat,
2133         },
2134         {
2135                 .name = "dequeue",
2136                 .private = offsetof(struct cfq_group, stats.dequeue),
2137                 .seq_show = cfqg_print_stat,
2138         },
2139         {
2140                 .name = "unaccounted_time",
2141                 .private = offsetof(struct cfq_group, stats.unaccounted_time),
2142                 .seq_show = cfqg_print_stat,
2143         },
2144 #endif  /* CONFIG_DEBUG_BLK_CGROUP */
2145         { }     /* terminate */
2146 };
2147
2148 static int cfq_print_weight_on_dfl(struct seq_file *sf, void *v)
2149 {
2150         struct blkcg *blkcg = css_to_blkcg(seq_css(sf));
2151         struct cfq_group_data *cgd = blkcg_to_cfqgd(blkcg);
2152
2153         seq_printf(sf, "default %u\n", cgd->weight);
2154         blkcg_print_blkgs(sf, blkcg, cfqg_prfill_weight_device,
2155                           &blkcg_policy_cfq, 0, false);
2156         return 0;
2157 }
2158
2159 static ssize_t cfq_set_weight_on_dfl(struct kernfs_open_file *of,
2160                                      char *buf, size_t nbytes, loff_t off)
2161 {
2162         char *endp;
2163         int ret;
2164         u64 v;
2165
2166         buf = strim(buf);
2167
2168         /* "WEIGHT" or "default WEIGHT" sets the default weight */
2169         v = simple_strtoull(buf, &endp, 0);
2170         if (*endp == '\0' || sscanf(buf, "default %llu", &v) == 1) {
2171                 ret = __cfq_set_weight(of_css(of), v, true, false, false);
2172                 return ret ?: nbytes;
2173         }
2174
2175         /* "MAJ:MIN WEIGHT" */
2176         return __cfqg_set_weight_device(of, buf, nbytes, off, true, false);
2177 }
2178
2179 static struct cftype cfq_blkcg_files[] = {
2180         {
2181                 .name = "weight",
2182                 .flags = CFTYPE_NOT_ON_ROOT,
2183                 .seq_show = cfq_print_weight_on_dfl,
2184                 .write = cfq_set_weight_on_dfl,
2185         },
2186         { }     /* terminate */
2187 };
2188
2189 #else /* GROUP_IOSCHED */
2190 static struct cfq_group *cfq_lookup_cfqg(struct cfq_data *cfqd,
2191                                          struct blkcg *blkcg)
2192 {
2193         return cfqd->root_group;
2194 }
2195
2196 static inline void
2197 cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) {
2198         cfqq->cfqg = cfqg;
2199 }
2200
2201 #endif /* GROUP_IOSCHED */
2202
2203 /*
2204  * The cfqd->service_trees holds all pending cfq_queue's that have
2205  * requests waiting to be processed. It is sorted in the order that
2206  * we will service the queues.
2207  */
2208 static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2209                                  bool add_front)
2210 {
2211         struct rb_node **p, *parent;
2212         struct cfq_queue *__cfqq;
2213         u64 rb_key;
2214         struct cfq_rb_root *st;
2215         bool leftmost = true;
2216         int new_cfqq = 1;
2217         u64 now = ktime_get_ns();
2218
2219         st = st_for(cfqq->cfqg, cfqq_class(cfqq), cfqq_type(cfqq));
2220         if (cfq_class_idle(cfqq)) {
2221                 rb_key = CFQ_IDLE_DELAY;
2222                 parent = st->rb_rightmost;
2223                 if (parent && parent != &cfqq->rb_node) {
2224                         __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
2225                         rb_key += __cfqq->rb_key;
2226                 } else
2227                         rb_key += now;
2228         } else if (!add_front) {
2229                 /*
2230                  * Get our rb key offset. Subtract any residual slice
2231                  * value carried from last service. A negative resid
2232                  * count indicates slice overrun, and this should position
2233                  * the next service time further away in the tree.
2234                  */
2235                 rb_key = cfq_slice_offset(cfqd, cfqq) + now;
2236                 rb_key -= cfqq->slice_resid;
2237                 cfqq->slice_resid = 0;
2238         } else {
2239                 rb_key = -NSEC_PER_SEC;
2240                 __cfqq = cfq_rb_first(st);
2241                 rb_key += __cfqq ? __cfqq->rb_key : now;
2242         }
2243
2244         if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
2245                 new_cfqq = 0;
2246                 /*
2247                  * same position, nothing more to do
2248                  */
2249                 if (rb_key == cfqq->rb_key && cfqq->service_tree == st)
2250                         return;
2251
2252                 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
2253                 cfqq->service_tree = NULL;
2254         }
2255
2256         parent = NULL;
2257         cfqq->service_tree = st;
2258         p = &st->rb.rb_root.rb_node;
2259         while (*p) {
2260                 parent = *p;
2261                 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
2262
2263                 /*
2264                  * sort by key, that represents service time.
2265                  */
2266                 if (rb_key < __cfqq->rb_key)
2267                         p = &parent->rb_left;
2268                 else {
2269                         p = &parent->rb_right;
2270                         leftmost = false;
2271                 }
2272         }
2273
2274         cfqq->rb_key = rb_key;
2275         rb_link_node(&cfqq->rb_node, parent, p);
2276         rb_insert_color_cached(&cfqq->rb_node, &st->rb, leftmost);
2277         st->count++;
2278         if (add_front || !new_cfqq)
2279                 return;
2280         cfq_group_notify_queue_add(cfqd, cfqq->cfqg);
2281 }
2282
2283 static struct cfq_queue *
2284 cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root,
2285                      sector_t sector, struct rb_node **ret_parent,
2286                      struct rb_node ***rb_link)
2287 {
2288         struct rb_node **p, *parent;
2289         struct cfq_queue *cfqq = NULL;
2290
2291         parent = NULL;
2292         p = &root->rb_node;
2293         while (*p) {
2294                 struct rb_node **n;
2295
2296                 parent = *p;
2297                 cfqq = rb_entry(parent, struct cfq_queue, p_node);
2298
2299                 /*
2300                  * Sort strictly based on sector.  Smallest to the left,
2301                  * largest to the right.
2302                  */
2303                 if (sector > blk_rq_pos(cfqq->next_rq))
2304                         n = &(*p)->rb_right;
2305                 else if (sector < blk_rq_pos(cfqq->next_rq))
2306                         n = &(*p)->rb_left;
2307                 else
2308                         break;
2309                 p = n;
2310                 cfqq = NULL;
2311         }
2312
2313         *ret_parent = parent;
2314         if (rb_link)
2315                 *rb_link = p;
2316         return cfqq;
2317 }
2318
2319 static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2320 {
2321         struct rb_node **p, *parent;
2322         struct cfq_queue *__cfqq;
2323
2324         if (cfqq->p_root) {
2325                 rb_erase(&cfqq->p_node, cfqq->p_root);
2326                 cfqq->p_root = NULL;
2327         }
2328
2329         if (cfq_class_idle(cfqq))
2330                 return;
2331         if (!cfqq->next_rq)
2332                 return;
2333
2334         cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
2335         __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root,
2336                                       blk_rq_pos(cfqq->next_rq), &parent, &p);
2337         if (!__cfqq) {
2338                 rb_link_node(&cfqq->p_node, parent, p);
2339                 rb_insert_color(&cfqq->p_node, cfqq->p_root);
2340         } else
2341                 cfqq->p_root = NULL;
2342 }
2343
2344 /*
2345  * Update cfqq's position in the service tree.
2346  */
2347 static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2348 {
2349         /*
2350          * Resorting requires the cfqq to be on the RR list already.
2351          */
2352         if (cfq_cfqq_on_rr(cfqq)) {
2353                 cfq_service_tree_add(cfqd, cfqq, 0);
2354                 cfq_prio_tree_add(cfqd, cfqq);
2355         }
2356 }
2357
2358 /*
2359  * add to busy list of queues for service, trying to be fair in ordering
2360  * the pending list according to last request service
2361  */
2362 static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2363 {
2364         cfq_log_cfqq(cfqd, cfqq, "add_to_rr");
2365         BUG_ON(cfq_cfqq_on_rr(cfqq));
2366         cfq_mark_cfqq_on_rr(cfqq);
2367         cfqd->busy_queues++;
2368         if (cfq_cfqq_sync(cfqq))
2369                 cfqd->busy_sync_queues++;
2370
2371         cfq_resort_rr_list(cfqd, cfqq);
2372 }
2373
2374 /*
2375  * Called when the cfqq no longer has requests pending, remove it from
2376  * the service tree.
2377  */
2378 static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2379 {
2380         cfq_log_cfqq(cfqd, cfqq, "del_from_rr");
2381         BUG_ON(!cfq_cfqq_on_rr(cfqq));
2382         cfq_clear_cfqq_on_rr(cfqq);
2383
2384         if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
2385                 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
2386                 cfqq->service_tree = NULL;
2387         }
2388         if (cfqq->p_root) {
2389                 rb_erase(&cfqq->p_node, cfqq->p_root);
2390                 cfqq->p_root = NULL;
2391         }
2392
2393         cfq_group_notify_queue_del(cfqd, cfqq->cfqg);
2394         BUG_ON(!cfqd->busy_queues);
2395         cfqd->busy_queues--;
2396         if (cfq_cfqq_sync(cfqq))
2397                 cfqd->busy_sync_queues--;
2398 }
2399
2400 /*
2401  * rb tree support functions
2402  */
2403 static void cfq_del_rq_rb(struct request *rq)
2404 {
2405         struct cfq_queue *cfqq = RQ_CFQQ(rq);
2406         const int sync = rq_is_sync(rq);
2407
2408         BUG_ON(!cfqq->queued[sync]);
2409         cfqq->queued[sync]--;
2410
2411         elv_rb_del(&cfqq->sort_list, rq);
2412
2413         if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) {
2414                 /*
2415                  * Queue will be deleted from service tree when we actually
2416                  * expire it later. Right now just remove it from prio tree
2417                  * as it is empty.
2418                  */
2419                 if (cfqq->p_root) {
2420                         rb_erase(&cfqq->p_node, cfqq->p_root);
2421                         cfqq->p_root = NULL;
2422                 }
2423         }
2424 }
2425
2426 static void cfq_add_rq_rb(struct request *rq)
2427 {
2428         struct cfq_queue *cfqq = RQ_CFQQ(rq);
2429         struct cfq_data *cfqd = cfqq->cfqd;
2430         struct request *prev;
2431
2432         cfqq->queued[rq_is_sync(rq)]++;
2433
2434         elv_rb_add(&cfqq->sort_list, rq);
2435
2436         if (!cfq_cfqq_on_rr(cfqq))
2437                 cfq_add_cfqq_rr(cfqd, cfqq);
2438
2439         /*
2440          * check if this request is a better next-serve candidate
2441          */
2442         prev = cfqq->next_rq;
2443         cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position);
2444
2445         /*
2446          * adjust priority tree position, if ->next_rq changes
2447          */
2448         if (prev != cfqq->next_rq)
2449                 cfq_prio_tree_add(cfqd, cfqq);
2450
2451         BUG_ON(!cfqq->next_rq);
2452 }
2453
2454 static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq)
2455 {
2456         elv_rb_del(&cfqq->sort_list, rq);
2457         cfqq->queued[rq_is_sync(rq)]--;
2458         cfqg_stats_update_io_remove(RQ_CFQG(rq), rq->cmd_flags);
2459         cfq_add_rq_rb(rq);
2460         cfqg_stats_update_io_add(RQ_CFQG(rq), cfqq->cfqd->serving_group,
2461                                  rq->cmd_flags);
2462 }
2463
2464 static struct request *
2465 cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
2466 {
2467         struct task_struct *tsk = current;
2468         struct cfq_io_cq *cic;
2469         struct cfq_queue *cfqq;
2470
2471         cic = cfq_cic_lookup(cfqd, tsk->io_context);
2472         if (!cic)
2473                 return NULL;
2474
2475         cfqq = cic_to_cfqq(cic, op_is_sync(bio->bi_opf));
2476         if (cfqq)
2477                 return elv_rb_find(&cfqq->sort_list, bio_end_sector(bio));
2478
2479         return NULL;
2480 }
2481
2482 static void cfq_activate_request(struct request_queue *q, struct request *rq)
2483 {
2484         struct cfq_data *cfqd = q->elevator->elevator_data;
2485
2486         cfqd->rq_in_driver++;
2487         cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
2488                                                 cfqd->rq_in_driver);
2489
2490         cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
2491 }
2492
2493 static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
2494 {
2495         struct cfq_data *cfqd = q->elevator->elevator_data;
2496
2497         WARN_ON(!cfqd->rq_in_driver);
2498         cfqd->rq_in_driver--;
2499         cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
2500                                                 cfqd->rq_in_driver);
2501 }
2502
2503 static void cfq_remove_request(struct request *rq)
2504 {
2505         struct cfq_queue *cfqq = RQ_CFQQ(rq);
2506
2507         if (cfqq->next_rq == rq)
2508                 cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq);
2509
2510         list_del_init(&rq->queuelist);
2511         cfq_del_rq_rb(rq);
2512
2513         cfqq->cfqd->rq_queued--;
2514         cfqg_stats_update_io_remove(RQ_CFQG(rq), rq->cmd_flags);
2515         if (rq->cmd_flags & REQ_PRIO) {
2516                 WARN_ON(!cfqq->prio_pending);
2517                 cfqq->prio_pending--;
2518         }
2519 }
2520
2521 static enum elv_merge cfq_merge(struct request_queue *q, struct request **req,
2522                      struct bio *bio)
2523 {
2524         struct cfq_data *cfqd = q->elevator->elevator_data;
2525         struct request *__rq;
2526
2527         __rq = cfq_find_rq_fmerge(cfqd, bio);
2528         if (__rq && elv_bio_merge_ok(__rq, bio)) {
2529                 *req = __rq;
2530                 return ELEVATOR_FRONT_MERGE;
2531         }
2532
2533         return ELEVATOR_NO_MERGE;
2534 }
2535
2536 static void cfq_merged_request(struct request_queue *q, struct request *req,
2537                                enum elv_merge type)
2538 {
2539         if (type == ELEVATOR_FRONT_MERGE) {
2540                 struct cfq_queue *cfqq = RQ_CFQQ(req);
2541
2542                 cfq_reposition_rq_rb(cfqq, req);
2543         }
2544 }
2545
2546 static void cfq_bio_merged(struct request_queue *q, struct request *req,
2547                                 struct bio *bio)
2548 {
2549         cfqg_stats_update_io_merged(RQ_CFQG(req), bio->bi_opf);
2550 }
2551
2552 static void
2553 cfq_merged_requests(struct request_queue *q, struct request *rq,
2554                     struct request *next)
2555 {
2556         struct cfq_queue *cfqq = RQ_CFQQ(rq);
2557         struct cfq_data *cfqd = q->elevator->elevator_data;
2558
2559         /*
2560          * reposition in fifo if next is older than rq
2561          */
2562         if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
2563             next->fifo_time < rq->fifo_time &&
2564             cfqq == RQ_CFQQ(next)) {
2565                 list_move(&rq->queuelist, &next->queuelist);
2566                 rq->fifo_time = next->fifo_time;
2567         }
2568
2569         if (cfqq->next_rq == next)
2570                 cfqq->next_rq = rq;
2571         cfq_remove_request(next);
2572         cfqg_stats_update_io_merged(RQ_CFQG(rq), next->cmd_flags);
2573
2574         cfqq = RQ_CFQQ(next);
2575         /*
2576          * all requests of this queue are merged to other queues, delete it
2577          * from the service tree. If it's the active_queue,
2578          * cfq_dispatch_requests() will choose to expire it or do idle
2579          */
2580         if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list) &&
2581             cfqq != cfqd->active_queue)
2582                 cfq_del_cfqq_rr(cfqd, cfqq);
2583 }
2584
2585 static int cfq_allow_bio_merge(struct request_queue *q, struct request *rq,
2586                                struct bio *bio)
2587 {
2588         struct cfq_data *cfqd = q->elevator->elevator_data;
2589         bool is_sync = op_is_sync(bio->bi_opf);
2590         struct cfq_io_cq *cic;
2591         struct cfq_queue *cfqq;
2592
2593         /*
2594          * Disallow merge of a sync bio into an async request.
2595          */
2596         if (is_sync && !rq_is_sync(rq))
2597                 return false;
2598
2599         /*
2600          * Lookup the cfqq that this bio will be queued with and allow
2601          * merge only if rq is queued there.
2602          */
2603         cic = cfq_cic_lookup(cfqd, current->io_context);
2604         if (!cic)
2605                 return false;
2606
2607         cfqq = cic_to_cfqq(cic, is_sync);
2608         return cfqq == RQ_CFQQ(rq);
2609 }
2610
2611 static int cfq_allow_rq_merge(struct request_queue *q, struct request *rq,
2612                               struct request *next)
2613 {
2614         return RQ_CFQQ(rq) == RQ_CFQQ(next);
2615 }
2616
2617 static inline void cfq_del_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2618 {
2619         hrtimer_try_to_cancel(&cfqd->idle_slice_timer);
2620         cfqg_stats_update_idle_time(cfqq->cfqg);
2621 }
2622
2623 static void __cfq_set_active_queue(struct cfq_data *cfqd,
2624                                    struct cfq_queue *cfqq)
2625 {
2626         if (cfqq) {
2627                 cfq_log_cfqq(cfqd, cfqq, "set_active wl_class:%d wl_type:%d",
2628                                 cfqd->serving_wl_class, cfqd->serving_wl_type);
2629                 cfqg_stats_update_avg_queue_size(cfqq->cfqg);
2630                 cfqq->slice_start = 0;
2631                 cfqq->dispatch_start = ktime_get_ns();
2632                 cfqq->allocated_slice = 0;
2633                 cfqq->slice_end = 0;
2634                 cfqq->slice_dispatch = 0;
2635                 cfqq->nr_sectors = 0;
2636
2637                 cfq_clear_cfqq_wait_request(cfqq);
2638                 cfq_clear_cfqq_must_dispatch(cfqq);
2639                 cfq_clear_cfqq_must_alloc_slice(cfqq);
2640                 cfq_clear_cfqq_fifo_expire(cfqq);
2641                 cfq_mark_cfqq_slice_new(cfqq);
2642
2643                 cfq_del_timer(cfqd, cfqq);
2644         }
2645
2646         cfqd->active_queue = cfqq;
2647 }
2648
2649 /*
2650  * current cfqq expired its slice (or was too idle), select new one
2651  */
2652 static void
2653 __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2654                     bool timed_out)
2655 {
2656         cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out);
2657
2658         if (cfq_cfqq_wait_request(cfqq))
2659                 cfq_del_timer(cfqd, cfqq);
2660
2661         cfq_clear_cfqq_wait_request(cfqq);
2662         cfq_clear_cfqq_wait_busy(cfqq);
2663
2664         /*
2665          * If this cfqq is shared between multiple processes, check to
2666          * make sure that those processes are still issuing I/Os within
2667          * the mean seek distance.  If not, it may be time to break the
2668          * queues apart again.
2669          */
2670         if (cfq_cfqq_coop(cfqq) && CFQQ_SEEKY(cfqq))
2671                 cfq_mark_cfqq_split_coop(cfqq);
2672
2673         /*
2674          * store what was left of this slice, if the queue idled/timed out
2675          */
2676         if (timed_out) {
2677                 if (cfq_cfqq_slice_new(cfqq))
2678                         cfqq->slice_resid = cfq_scaled_cfqq_slice(cfqd, cfqq);
2679                 else
2680                         cfqq->slice_resid = cfqq->slice_end - ktime_get_ns();
2681                 cfq_log_cfqq(cfqd, cfqq, "resid=%lld", cfqq->slice_resid);
2682         }
2683
2684         cfq_group_served(cfqd, cfqq->cfqg, cfqq);
2685
2686         if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
2687                 cfq_del_cfqq_rr(cfqd, cfqq);
2688
2689         cfq_resort_rr_list(cfqd, cfqq);
2690
2691         if (cfqq == cfqd->active_queue)
2692                 cfqd->active_queue = NULL;
2693
2694         if (cfqd->active_cic) {
2695                 put_io_context(cfqd->active_cic->icq.ioc);
2696                 cfqd->active_cic = NULL;
2697         }
2698 }
2699
2700 static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out)
2701 {
2702         struct cfq_queue *cfqq = cfqd->active_queue;
2703
2704         if (cfqq)
2705                 __cfq_slice_expired(cfqd, cfqq, timed_out);
2706 }
2707
2708 /*
2709  * Get next queue for service. Unless we have a queue preemption,
2710  * we'll simply select the first cfqq in the service tree.
2711  */
2712 static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
2713 {
2714         struct cfq_rb_root *st = st_for(cfqd->serving_group,
2715                         cfqd->serving_wl_class, cfqd->serving_wl_type);
2716
2717         if (!cfqd->rq_queued)
2718                 return NULL;
2719
2720         /* There is nothing to dispatch */
2721         if (!st)
2722                 return NULL;
2723         if (RB_EMPTY_ROOT(&st->rb.rb_root))
2724                 return NULL;
2725         return cfq_rb_first(st);
2726 }
2727
2728 static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd)
2729 {
2730         struct cfq_group *cfqg;
2731         struct cfq_queue *cfqq;
2732         int i, j;
2733         struct cfq_rb_root *st;
2734
2735         if (!cfqd->rq_queued)
2736                 return NULL;
2737
2738         cfqg = cfq_get_next_cfqg(cfqd);
2739         if (!cfqg)
2740                 return NULL;
2741
2742         for_each_cfqg_st(cfqg, i, j, st) {
2743                 cfqq = cfq_rb_first(st);
2744                 if (cfqq)
2745                         return cfqq;
2746         }
2747         return NULL;
2748 }
2749
2750 /*
2751  * Get and set a new active queue for service.
2752  */
2753 static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
2754                                               struct cfq_queue *cfqq)
2755 {
2756         if (!cfqq)
2757                 cfqq = cfq_get_next_queue(cfqd);
2758
2759         __cfq_set_active_queue(cfqd, cfqq);
2760         return cfqq;
2761 }
2762
2763 static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
2764                                           struct request *rq)
2765 {
2766         if (blk_rq_pos(rq) >= cfqd->last_position)
2767                 return blk_rq_pos(rq) - cfqd->last_position;
2768         else
2769                 return cfqd->last_position - blk_rq_pos(rq);
2770 }
2771
2772 static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2773                                struct request *rq)
2774 {
2775         return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR;
2776 }
2777
2778 static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
2779                                     struct cfq_queue *cur_cfqq)
2780 {
2781         struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
2782         struct rb_node *parent, *node;
2783         struct cfq_queue *__cfqq;
2784         sector_t sector = cfqd->last_position;
2785
2786         if (RB_EMPTY_ROOT(root))
2787                 return NULL;
2788
2789         /*
2790          * First, if we find a request starting at the end of the last
2791          * request, choose it.
2792          */
2793         __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
2794         if (__cfqq)
2795                 return __cfqq;
2796
2797         /*
2798          * If the exact sector wasn't found, the parent of the NULL leaf
2799          * will contain the closest sector.
2800          */
2801         __cfqq = rb_entry(parent, struct cfq_queue, p_node);
2802         if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
2803                 return __cfqq;
2804
2805         if (blk_rq_pos(__cfqq->next_rq) < sector)
2806                 node = rb_next(&__cfqq->p_node);
2807         else
2808                 node = rb_prev(&__cfqq->p_node);
2809         if (!node)
2810                 return NULL;
2811
2812         __cfqq = rb_entry(node, struct cfq_queue, p_node);
2813         if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
2814                 return __cfqq;
2815
2816         return NULL;
2817 }
2818
2819 /*
2820  * cfqd - obvious
2821  * cur_cfqq - passed in so that we don't decide that the current queue is
2822  *            closely cooperating with itself.
2823  *
2824  * So, basically we're assuming that that cur_cfqq has dispatched at least
2825  * one request, and that cfqd->last_position reflects a position on the disk
2826  * associated with the I/O issued by cur_cfqq.  I'm not sure this is a valid
2827  * assumption.
2828  */
2829 static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
2830                                               struct cfq_queue *cur_cfqq)
2831 {
2832         struct cfq_queue *cfqq;
2833
2834         if (cfq_class_idle(cur_cfqq))
2835                 return NULL;
2836         if (!cfq_cfqq_sync(cur_cfqq))
2837                 return NULL;
2838         if (CFQQ_SEEKY(cur_cfqq))
2839                 return NULL;
2840
2841         /*
2842          * Don't search priority tree if it's the only queue in the group.
2843          */
2844         if (cur_cfqq->cfqg->nr_cfqq == 1)
2845                 return NULL;
2846
2847         /*
2848          * We should notice if some of the queues are cooperating, eg
2849          * working closely on the same area of the disk. In that case,
2850          * we can group them together and don't waste time idling.
2851          */
2852         cfqq = cfqq_close(cfqd, cur_cfqq);
2853         if (!cfqq)
2854                 return NULL;
2855
2856         /* If new queue belongs to different cfq_group, don't choose it */
2857         if (cur_cfqq->cfqg != cfqq->cfqg)
2858                 return NULL;
2859
2860         /*
2861          * It only makes sense to merge sync queues.
2862          */
2863         if (!cfq_cfqq_sync(cfqq))
2864                 return NULL;
2865         if (CFQQ_SEEKY(cfqq))
2866                 return NULL;
2867
2868         /*
2869          * Do not merge queues of different priority classes
2870          */
2871         if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq))
2872                 return NULL;
2873
2874         return cfqq;
2875 }
2876
2877 /*
2878  * Determine whether we should enforce idle window for this queue.
2879  */
2880
2881 static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2882 {
2883         enum wl_class_t wl_class = cfqq_class(cfqq);
2884         struct cfq_rb_root *st = cfqq->service_tree;
2885
2886         BUG_ON(!st);
2887         BUG_ON(!st->count);
2888
2889         if (!cfqd->cfq_slice_idle)
2890                 return false;
2891
2892         /* We never do for idle class queues. */
2893         if (wl_class == IDLE_WORKLOAD)
2894                 return false;
2895
2896         /* We do for queues that were marked with idle window flag. */
2897         if (cfq_cfqq_idle_window(cfqq) &&
2898            !(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag))
2899                 return true;
2900
2901         /*
2902          * Otherwise, we do only if they are the last ones
2903          * in their service tree.
2904          */
2905         if (st->count == 1 && cfq_cfqq_sync(cfqq) &&
2906            !cfq_io_thinktime_big(cfqd, &st->ttime, false))
2907                 return true;
2908         cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d", st->count);
2909         return false;
2910 }
2911
2912 static void cfq_arm_slice_timer(struct cfq_data *cfqd)
2913 {
2914         struct cfq_queue *cfqq = cfqd->active_queue;
2915         struct cfq_rb_root *st = cfqq->service_tree;
2916         struct cfq_io_cq *cic;
2917         u64 sl, group_idle = 0;
2918         u64 now = ktime_get_ns();
2919
2920         /*
2921          * SSD device without seek penalty, disable idling. But only do so
2922          * for devices that support queuing, otherwise we still have a problem
2923          * with sync vs async workloads.
2924          */
2925         if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag &&
2926                 !cfqd->cfq_group_idle)
2927                 return;
2928
2929         WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
2930         WARN_ON(cfq_cfqq_slice_new(cfqq));
2931
2932         /*
2933          * idle is disabled, either manually or by past process history
2934          */
2935         if (!cfq_should_idle(cfqd, cfqq)) {
2936                 /* no queue idling. Check for group idling */
2937                 if (cfqd->cfq_group_idle)
2938                         group_idle = cfqd->cfq_group_idle;
2939                 else
2940                         return;
2941         }
2942
2943         /*
2944          * still active requests from this queue, don't idle
2945          */
2946         if (cfqq->dispatched)
2947                 return;
2948
2949         /*
2950          * task has exited, don't wait
2951          */
2952         cic = cfqd->active_cic;
2953         if (!cic || !atomic_read(&cic->icq.ioc->active_ref))
2954                 return;
2955
2956         /*
2957          * If our average think time is larger than the remaining time
2958          * slice, then don't idle. This avoids overrunning the allotted
2959          * time slice.
2960          */
2961         if (sample_valid(cic->ttime.ttime_samples) &&
2962             (cfqq->slice_end - now < cic->ttime.ttime_mean)) {
2963                 cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%llu",
2964                              cic->ttime.ttime_mean);
2965                 return;
2966         }
2967
2968         /*
2969          * There are other queues in the group or this is the only group and
2970          * it has too big thinktime, don't do group idle.
2971          */
2972         if (group_idle &&
2973             (cfqq->cfqg->nr_cfqq > 1 ||
2974              cfq_io_thinktime_big(cfqd, &st->ttime, true)))
2975                 return;
2976
2977         cfq_mark_cfqq_wait_request(cfqq);
2978
2979         if (group_idle)
2980                 sl = cfqd->cfq_group_idle;
2981         else
2982                 sl = cfqd->cfq_slice_idle;
2983
2984         hrtimer_start(&cfqd->idle_slice_timer, ns_to_ktime(sl),
2985                       HRTIMER_MODE_REL);
2986         cfqg_stats_set_start_idle_time(cfqq->cfqg);
2987         cfq_log_cfqq(cfqd, cfqq, "arm_idle: %llu group_idle: %d", sl,
2988                         group_idle ? 1 : 0);
2989 }
2990
2991 /*
2992  * Move request from internal lists to the request queue dispatch list.
2993  */
2994 static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
2995 {
2996         struct cfq_data *cfqd = q->elevator->elevator_data;
2997         struct cfq_queue *cfqq = RQ_CFQQ(rq);
2998
2999         cfq_log_cfqq(cfqd, cfqq, "dispatch_insert");
3000
3001         cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq);
3002         cfq_remove_request(rq);
3003         cfqq->dispatched++;
3004         (RQ_CFQG(rq))->dispatched++;
3005         elv_dispatch_sort(q, rq);
3006
3007         cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++;
3008         cfqq->nr_sectors += blk_rq_sectors(rq);
3009 }
3010
3011 /*
3012  * return expired entry, or NULL to just start from scratch in rbtree
3013  */
3014 static struct request *cfq_check_fifo(struct cfq_queue *cfqq)
3015 {
3016         struct request *rq = NULL;
3017
3018         if (cfq_cfqq_fifo_expire(cfqq))
3019                 return NULL;
3020
3021         cfq_mark_cfqq_fifo_expire(cfqq);
3022
3023         if (list_empty(&cfqq->fifo))
3024                 return NULL;
3025
3026         rq = rq_entry_fifo(cfqq->fifo.next);
3027         if (ktime_get_ns() < rq->fifo_time)
3028                 rq = NULL;
3029
3030         return rq;
3031 }
3032
3033 static inline int
3034 cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3035 {
3036         const int base_rq = cfqd->cfq_slice_async_rq;
3037
3038         WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
3039
3040         return 2 * base_rq * (IOPRIO_BE_NR - cfqq->ioprio);
3041 }
3042
3043 /*
3044  * Must be called with the queue_lock held.
3045  */
3046 static int cfqq_process_refs(struct cfq_queue *cfqq)
3047 {
3048         int process_refs, io_refs;
3049
3050         io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE];
3051         process_refs = cfqq->ref - io_refs;
3052         BUG_ON(process_refs < 0);
3053         return process_refs;
3054 }
3055
3056 static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq)
3057 {
3058         int process_refs, new_process_refs;
3059         struct cfq_queue *__cfqq;
3060
3061         /*
3062          * If there are no process references on the new_cfqq, then it is
3063          * unsafe to follow the ->new_cfqq chain as other cfqq's in the
3064          * chain may have dropped their last reference (not just their
3065          * last process reference).
3066          */
3067         if (!cfqq_process_refs(new_cfqq))
3068                 return;
3069
3070         /* Avoid a circular list and skip interim queue merges */
3071         while ((__cfqq = new_cfqq->new_cfqq)) {
3072                 if (__cfqq == cfqq)
3073                         return;
3074                 new_cfqq = __cfqq;
3075         }
3076
3077         process_refs = cfqq_process_refs(cfqq);
3078         new_process_refs = cfqq_process_refs(new_cfqq);
3079         /*
3080          * If the process for the cfqq has gone away, there is no
3081          * sense in merging the queues.
3082          */
3083         if (process_refs == 0 || new_process_refs == 0)
3084                 return;
3085
3086         /*
3087          * Merge in the direction of the lesser amount of work.
3088          */
3089         if (new_process_refs >= process_refs) {
3090                 cfqq->new_cfqq = new_cfqq;
3091                 new_cfqq->ref += process_refs;
3092         } else {
3093                 new_cfqq->new_cfqq = cfqq;
3094                 cfqq->ref += new_process_refs;
3095         }
3096 }
3097
3098 static enum wl_type_t cfq_choose_wl_type(struct cfq_data *cfqd,
3099                         struct cfq_group *cfqg, enum wl_class_t wl_class)
3100 {
3101         struct cfq_queue *queue;
3102         int i;
3103         bool key_valid = false;
3104         u64 lowest_key = 0;
3105         enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD;
3106
3107         for (i = 0; i <= SYNC_WORKLOAD; ++i) {
3108                 /* select the one with lowest rb_key */
3109                 queue = cfq_rb_first(st_for(cfqg, wl_class, i));
3110                 if (queue &&
3111                     (!key_valid || queue->rb_key < lowest_key)) {
3112                         lowest_key = queue->rb_key;
3113                         cur_best = i;
3114                         key_valid = true;
3115                 }
3116         }
3117
3118         return cur_best;
3119 }
3120
3121 static void
3122 choose_wl_class_and_type(struct cfq_data *cfqd, struct cfq_group *cfqg)
3123 {
3124         u64 slice;
3125         unsigned count;
3126         struct cfq_rb_root *st;
3127         u64 group_slice;
3128         enum wl_class_t original_class = cfqd->serving_wl_class;
3129         u64 now = ktime_get_ns();
3130
3131         /* Choose next priority. RT > BE > IDLE */
3132         if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg))
3133                 cfqd->serving_wl_class = RT_WORKLOAD;
3134         else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg))
3135                 cfqd->serving_wl_class = BE_WORKLOAD;
3136         else {
3137                 cfqd->serving_wl_class = IDLE_WORKLOAD;
3138                 cfqd->workload_expires = now + jiffies_to_nsecs(1);
3139                 return;
3140         }
3141
3142         if (original_class != cfqd->serving_wl_class)
3143                 goto new_workload;
3144
3145         /*
3146          * For RT and BE, we have to choose also the type
3147          * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
3148          * expiration time
3149          */
3150         st = st_for(cfqg, cfqd->serving_wl_class, cfqd->serving_wl_type);
3151         count = st->count;
3152
3153         /*
3154          * check workload expiration, and that we still have other queues ready
3155          */
3156         if (count && !(now > cfqd->workload_expires))
3157                 return;
3158
3159 new_workload:
3160         /* otherwise select new workload type */
3161         cfqd->serving_wl_type = cfq_choose_wl_type(cfqd, cfqg,
3162                                         cfqd->serving_wl_class);
3163         st = st_for(cfqg, cfqd->serving_wl_class, cfqd->serving_wl_type);
3164         count = st->count;
3165
3166         /*
3167          * the workload slice is computed as a fraction of target latency
3168          * proportional to the number of queues in that workload, over
3169          * all the queues in the same priority class
3170          */
3171         group_slice = cfq_group_slice(cfqd, cfqg);
3172
3173         slice = div_u64(group_slice * count,
3174                 max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_wl_class],
3175                       cfq_group_busy_queues_wl(cfqd->serving_wl_class, cfqd,
3176                                         cfqg)));
3177
3178         if (cfqd->serving_wl_type == ASYNC_WORKLOAD) {
3179                 u64 tmp;
3180
3181                 /*
3182                  * Async queues are currently system wide. Just taking
3183                  * proportion of queues with-in same group will lead to higher
3184                  * async ratio system wide as generally root group is going
3185                  * to have higher weight. A more accurate thing would be to
3186                  * calculate system wide asnc/sync ratio.
3187                  */
3188                 tmp = cfqd->cfq_target_latency *
3189                         cfqg_busy_async_queues(cfqd, cfqg);
3190                 tmp = div_u64(tmp, cfqd->busy_queues);
3191                 slice = min_t(u64, slice, tmp);
3192
3193                 /* async workload slice is scaled down according to
3194                  * the sync/async slice ratio. */
3195                 slice = div64_u64(slice*cfqd->cfq_slice[0], cfqd->cfq_slice[1]);
3196         } else
3197                 /* sync workload slice is at least 2 * cfq_slice_idle */
3198                 slice = max(slice, 2 * cfqd->cfq_slice_idle);
3199
3200         slice = max_t(u64, slice, CFQ_MIN_TT);
3201         cfq_log(cfqd, "workload slice:%llu", slice);
3202         cfqd->workload_expires = now + slice;
3203 }
3204
3205 static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd)
3206 {
3207         struct cfq_rb_root *st = &cfqd->grp_service_tree;
3208         struct cfq_group *cfqg;
3209
3210         if (RB_EMPTY_ROOT(&st->rb.rb_root))
3211                 return NULL;
3212         cfqg = cfq_rb_first_group(st);
3213         update_min_vdisktime(st);
3214         return cfqg;
3215 }
3216
3217 static void cfq_choose_cfqg(struct cfq_data *cfqd)
3218 {
3219         struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd);
3220         u64 now = ktime_get_ns();
3221
3222         cfqd->serving_group = cfqg;
3223
3224         /* Restore the workload type data */
3225         if (cfqg->saved_wl_slice) {
3226                 cfqd->workload_expires = now + cfqg->saved_wl_slice;
3227                 cfqd->serving_wl_type = cfqg->saved_wl_type;
3228                 cfqd->serving_wl_class = cfqg->saved_wl_class;
3229         } else
3230                 cfqd->workload_expires = now - 1;
3231
3232         choose_wl_class_and_type(cfqd, cfqg);
3233 }
3234
3235 /*
3236  * Select a queue for service. If we have a current active queue,
3237  * check whether to continue servicing it, or retrieve and set a new one.
3238  */
3239 static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
3240 {
3241         struct cfq_queue *cfqq, *new_cfqq = NULL;
3242         u64 now = ktime_get_ns();
3243
3244         cfqq = cfqd->active_queue;
3245         if (!cfqq)
3246                 goto new_queue;
3247
3248         if (!cfqd->rq_queued)
3249                 return NULL;
3250
3251         /*
3252          * We were waiting for group to get backlogged. Expire the queue
3253          */
3254         if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list))
3255                 goto expire;
3256
3257         /*
3258          * The active queue has run out of time, expire it and select new.
3259          */
3260         if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) {
3261                 /*
3262                  * If slice had not expired at the completion of last request
3263                  * we might not have turned on wait_busy flag. Don't expire
3264                  * the queue yet. Allow the group to get backlogged.
3265                  *
3266                  * The very fact that we have used the slice, that means we
3267                  * have been idling all along on this queue and it should be
3268                  * ok to wait for this request to complete.
3269                  */
3270                 if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list)
3271                     && cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
3272                         cfqq = NULL;
3273                         goto keep_queue;
3274                 } else
3275                         goto check_group_idle;
3276         }
3277
3278         /*
3279          * The active queue has requests and isn't expired, allow it to
3280          * dispatch.
3281          */
3282         if (!RB_EMPTY_ROOT(&cfqq->sort_list))
3283                 goto keep_queue;
3284
3285         /*
3286          * If another queue has a request waiting within our mean seek
3287          * distance, let it run.  The expire code will check for close
3288          * cooperators and put the close queue at the front of the service
3289          * tree.  If possible, merge the expiring queue with the new cfqq.
3290          */
3291         new_cfqq = cfq_close_cooperator(cfqd, cfqq);
3292         if (new_cfqq) {
3293                 if (!cfqq->new_cfqq)
3294                         cfq_setup_merge(cfqq, new_cfqq);
3295                 goto expire;
3296         }
3297
3298         /*
3299          * No requests pending. If the active queue still has requests in
3300          * flight or is idling for a new request, allow either of these
3301          * conditions to happen (or time out) before selecting a new queue.
3302          */
3303         if (hrtimer_active(&cfqd->idle_slice_timer)) {
3304                 cfqq = NULL;
3305                 goto keep_queue;
3306         }
3307
3308         /*
3309          * This is a deep seek queue, but the device is much faster than
3310          * the queue can deliver, don't idle
3311          **/
3312         if (CFQQ_SEEKY(cfqq) && cfq_cfqq_idle_window(cfqq) &&
3313             (cfq_cfqq_slice_new(cfqq) ||
3314             (cfqq->slice_end - now > now - cfqq->slice_start))) {
3315                 cfq_clear_cfqq_deep(cfqq);
3316                 cfq_clear_cfqq_idle_window(cfqq);
3317         }
3318
3319         if (cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
3320                 cfqq = NULL;
3321                 goto keep_queue;
3322         }
3323
3324         /*
3325          * If group idle is enabled and there are requests dispatched from
3326          * this group, wait for requests to complete.
3327          */
3328 check_group_idle:
3329         if (cfqd->cfq_group_idle && cfqq->cfqg->nr_cfqq == 1 &&
3330             cfqq->cfqg->dispatched &&
3331             !cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true)) {
3332                 cfqq = NULL;
3333                 goto keep_queue;
3334         }
3335
3336 expire:
3337         cfq_slice_expired(cfqd, 0);
3338 new_queue:
3339         /*
3340          * Current queue expired. Check if we have to switch to a new
3341          * service tree
3342          */
3343         if (!new_cfqq)
3344                 cfq_choose_cfqg(cfqd);
3345
3346         cfqq = cfq_set_active_queue(cfqd, new_cfqq);
3347 keep_queue:
3348         return cfqq;
3349 }
3350
3351 static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq)
3352 {
3353         int dispatched = 0;
3354
3355         while (cfqq->next_rq) {
3356                 cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq);
3357                 dispatched++;
3358         }
3359
3360         BUG_ON(!list_empty(&cfqq->fifo));
3361
3362         /* By default cfqq is not expired if it is empty. Do it explicitly */
3363         __cfq_slice_expired(cfqq->cfqd, cfqq, 0);
3364         return dispatched;
3365 }
3366
3367 /*
3368  * Drain our current requests. Used for barriers and when switching
3369  * io schedulers on-the-fly.
3370  */
3371 static int cfq_forced_dispatch(struct cfq_data *cfqd)
3372 {
3373         struct cfq_queue *cfqq;
3374         int dispatched = 0;
3375
3376         /* Expire the timeslice of the current active queue first */
3377         cfq_slice_expired(cfqd, 0);
3378         while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) {
3379                 __cfq_set_active_queue(cfqd, cfqq);
3380                 dispatched += __cfq_forced_dispatch_cfqq(cfqq);
3381         }
3382
3383         BUG_ON(cfqd->busy_queues);
3384
3385         cfq_log(cfqd, "forced_dispatch=%d", dispatched);
3386         return dispatched;
3387 }
3388
3389 static inline bool cfq_slice_used_soon(struct cfq_data *cfqd,
3390         struct cfq_queue *cfqq)
3391 {
3392         u64 now = ktime_get_ns();
3393
3394         /* the queue hasn't finished any request, can't estimate */
3395         if (cfq_cfqq_slice_new(cfqq))
3396                 return true;
3397         if (now + cfqd->cfq_slice_idle * cfqq->dispatched > cfqq->slice_end)
3398                 return true;
3399
3400         return false;
3401 }
3402
3403 static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3404 {
3405         unsigned int max_dispatch;
3406
3407         if (cfq_cfqq_must_dispatch(cfqq))
3408                 return true;
3409
3410         /*
3411          * Drain async requests before we start sync IO
3412          */
3413         if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC])
3414                 return false;
3415
3416         /*
3417          * If this is an async queue and we have sync IO in flight, let it wait
3418          */
3419         if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq))
3420                 return false;
3421
3422         max_dispatch = max_t(unsigned int, cfqd->cfq_quantum / 2, 1);
3423         if (cfq_class_idle(cfqq))
3424                 max_dispatch = 1;
3425
3426         /*
3427          * Does this cfqq already have too much IO in flight?
3428          */
3429         if (cfqq->dispatched >= max_dispatch) {
3430                 bool promote_sync = false;
3431                 /*
3432                  * idle queue must always only have a single IO in flight
3433                  */
3434                 if (cfq_class_idle(cfqq))
3435                         return false;
3436
3437                 /*
3438                  * If there is only one sync queue
3439                  * we can ignore async queue here and give the sync
3440                  * queue no dispatch limit. The reason is a sync queue can
3441                  * preempt async queue, limiting the sync queue doesn't make
3442                  * sense. This is useful for aiostress test.
3443                  */
3444                 if (cfq_cfqq_sync(cfqq) && cfqd->busy_sync_queues == 1)
3445                         promote_sync = true;
3446
3447                 /*
3448                  * We have other queues, don't allow more IO from this one
3449                  */
3450                 if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq) &&
3451                                 !promote_sync)
3452                         return false;
3453
3454                 /*
3455                  * Sole queue user, no limit
3456                  */
3457                 if (cfqd->busy_queues == 1 || promote_sync)
3458                         max_dispatch = -1;
3459                 else
3460                         /*
3461                          * Normally we start throttling cfqq when cfq_quantum/2
3462                          * requests have been dispatched. But we can drive
3463                          * deeper queue depths at the beginning of slice
3464                          * subjected to upper limit of cfq_quantum.
3465                          * */
3466                         max_dispatch = cfqd->cfq_quantum;
3467         }
3468
3469         /*
3470          * Async queues must wait a bit before being allowed dispatch.
3471          * We also ramp up the dispatch depth gradually for async IO,
3472          * based on the last sync IO we serviced
3473          */
3474         if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) {
3475                 u64 last_sync = ktime_get_ns() - cfqd->last_delayed_sync;
3476                 unsigned int depth;
3477
3478                 depth = div64_u64(last_sync, cfqd->cfq_slice[1]);
3479                 if (!depth && !cfqq->dispatched)
3480                         depth = 1;
3481                 if (depth < max_dispatch)
3482                         max_dispatch = depth;
3483         }
3484
3485         /*
3486          * If we're below the current max, allow a dispatch
3487          */
3488         return cfqq->dispatched < max_dispatch;
3489 }
3490
3491 /*
3492  * Dispatch a request from cfqq, moving them to the request queue
3493  * dispatch list.
3494  */
3495 static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3496 {
3497         struct request *rq;
3498
3499         BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list));
3500
3501         rq = cfq_check_fifo(cfqq);
3502         if (rq)
3503                 cfq_mark_cfqq_must_dispatch(cfqq);
3504
3505         if (!cfq_may_dispatch(cfqd, cfqq))
3506                 return false;
3507
3508         /*
3509          * follow expired path, else get first next available
3510          */
3511         if (!rq)
3512                 rq = cfqq->next_rq;
3513         else
3514                 cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq);
3515
3516         /*
3517          * insert request into driver dispatch list
3518          */
3519         cfq_dispatch_insert(cfqd->queue, rq);
3520
3521         if (!cfqd->active_cic) {
3522                 struct cfq_io_cq *cic = RQ_CIC(rq);
3523
3524                 atomic_long_inc(&cic->icq.ioc->refcount);
3525                 cfqd->active_cic = cic;
3526         }
3527
3528         return true;
3529 }
3530
3531 /*
3532  * Find the cfqq that we need to service and move a request from that to the
3533  * dispatch list
3534  */
3535 static int cfq_dispatch_requests(struct request_queue *q, int force)
3536 {
3537         struct cfq_data *cfqd = q->elevator->elevator_data;
3538         struct cfq_queue *cfqq;
3539
3540         if (!cfqd->busy_queues)
3541                 return 0;
3542
3543         if (unlikely(force))
3544                 return cfq_forced_dispatch(cfqd);
3545
3546         cfqq = cfq_select_queue(cfqd);
3547         if (!cfqq)
3548                 return 0;
3549
3550         /*
3551          * Dispatch a request from this cfqq, if it is allowed
3552          */
3553         if (!cfq_dispatch_request(cfqd, cfqq))
3554                 return 0;
3555
3556         cfqq->slice_dispatch++;
3557         cfq_clear_cfqq_must_dispatch(cfqq);
3558
3559         /*
3560          * expire an async queue immediately if it has used up its slice. idle
3561          * queue always expire after 1 dispatch round.
3562          */
3563         if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
3564             cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
3565             cfq_class_idle(cfqq))) {
3566                 cfqq->slice_end = ktime_get_ns() + 1;
3567                 cfq_slice_expired(cfqd, 0);
3568         }
3569
3570         cfq_log_cfqq(cfqd, cfqq, "dispatched a request");
3571         return 1;
3572 }
3573
3574 /*
3575  * task holds one reference to the queue, dropped when task exits. each rq
3576  * in-flight on this queue also holds a reference, dropped when rq is freed.
3577  *
3578  * Each cfq queue took a reference on the parent group. Drop it now.
3579  * queue lock must be held here.
3580  */
3581 static void cfq_put_queue(struct cfq_queue *cfqq)
3582 {
3583         struct cfq_data *cfqd = cfqq->cfqd;
3584         struct cfq_group *cfqg;
3585
3586         BUG_ON(cfqq->ref <= 0);
3587
3588         cfqq->ref--;
3589         if (cfqq->ref)
3590                 return;
3591
3592         cfq_log_cfqq(cfqd, cfqq, "put_queue");
3593         BUG_ON(rb_first(&cfqq->sort_list));
3594         BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
3595         cfqg = cfqq->cfqg;
3596
3597         if (unlikely(cfqd->active_queue == cfqq)) {
3598                 __cfq_slice_expired(cfqd, cfqq, 0);
3599                 cfq_schedule_dispatch(cfqd);
3600         }
3601
3602         BUG_ON(cfq_cfqq_on_rr(cfqq));
3603         kmem_cache_free(cfq_pool, cfqq);
3604         cfqg_put(cfqg);
3605 }
3606
3607 static void cfq_put_cooperator(struct cfq_queue *cfqq)
3608 {
3609         struct cfq_queue *__cfqq, *next;
3610
3611         /*
3612          * If this queue was scheduled to merge with another queue, be
3613          * sure to drop the reference taken on that queue (and others in
3614          * the merge chain).  See cfq_setup_merge and cfq_merge_cfqqs.
3615          */
3616         __cfqq = cfqq->new_cfqq;
3617         while (__cfqq) {
3618                 if (__cfqq == cfqq) {
3619                         WARN(1, "cfqq->new_cfqq loop detected\n");
3620                         break;
3621                 }
3622                 next = __cfqq->new_cfqq;
3623                 cfq_put_queue(__cfqq);
3624                 __cfqq = next;
3625         }
3626 }
3627
3628 static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3629 {
3630         if (unlikely(cfqq == cfqd->active_queue)) {
3631                 __cfq_slice_expired(cfqd, cfqq, 0);
3632                 cfq_schedule_dispatch(cfqd);
3633         }
3634
3635         cfq_put_cooperator(cfqq);
3636
3637         cfq_put_queue(cfqq);
3638 }
3639
3640 static void cfq_init_icq(struct io_cq *icq)
3641 {
3642         struct cfq_io_cq *cic = icq_to_cic(icq);
3643
3644         cic->ttime.last_end_request = ktime_get_ns();
3645 }
3646
3647 static void cfq_exit_icq(struct io_cq *icq)
3648 {
3649         struct cfq_io_cq *cic = icq_to_cic(icq);
3650         struct cfq_data *cfqd = cic_to_cfqd(cic);
3651
3652         if (cic_to_cfqq(cic, false)) {
3653                 cfq_exit_cfqq(cfqd, cic_to_cfqq(cic, false));
3654                 cic_set_cfqq(cic, NULL, false);
3655         }
3656
3657         if (cic_to_cfqq(cic, true)) {
3658                 cfq_exit_cfqq(cfqd, cic_to_cfqq(cic, true));
3659                 cic_set_cfqq(cic, NULL, true);
3660         }
3661 }
3662
3663 static void cfq_init_prio_data(struct cfq_queue *cfqq, struct cfq_io_cq *cic)
3664 {
3665         struct task_struct *tsk = current;
3666         int ioprio_class;
3667
3668         if (!cfq_cfqq_prio_changed(cfqq))
3669                 return;
3670
3671         ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio);
3672         switch (ioprio_class) {
3673         default:
3674                 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
3675                 /* fall through */
3676         case IOPRIO_CLASS_NONE:
3677                 /*
3678                  * no prio set, inherit CPU scheduling settings
3679                  */
3680                 cfqq->ioprio = task_nice_ioprio(tsk);
3681                 cfqq->ioprio_class = task_nice_ioclass(tsk);
3682                 break;
3683         case IOPRIO_CLASS_RT:
3684                 cfqq->ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
3685                 cfqq->ioprio_class = IOPRIO_CLASS_RT;
3686                 break;
3687         case IOPRIO_CLASS_BE:
3688                 cfqq->ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
3689                 cfqq->ioprio_class = IOPRIO_CLASS_BE;
3690                 break;
3691         case IOPRIO_CLASS_IDLE:
3692                 cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
3693                 cfqq->ioprio = 7;
3694                 cfq_clear_cfqq_idle_window(cfqq);
3695                 break;
3696         }
3697
3698         /*
3699          * keep track of original prio settings in case we have to temporarily
3700          * elevate the priority of this queue
3701          */
3702         cfqq->org_ioprio = cfqq->ioprio;
3703         cfqq->org_ioprio_class = cfqq->ioprio_class;
3704         cfq_clear_cfqq_prio_changed(cfqq);
3705 }
3706
3707 static void check_ioprio_changed(struct cfq_io_cq *cic, struct bio *bio)
3708 {
3709         int ioprio = cic->icq.ioc->ioprio;
3710         struct cfq_data *cfqd = cic_to_cfqd(cic);
3711         struct cfq_queue *cfqq;
3712
3713         /*
3714          * Check whether ioprio has changed.  The condition may trigger
3715          * spuriously on a newly created cic but there's no harm.
3716          */
3717         if (unlikely(!cfqd) || likely(cic->ioprio == ioprio))
3718                 return;
3719
3720         cfqq = cic_to_cfqq(cic, false);
3721         if (cfqq) {
3722                 cfq_put_queue(cfqq);
3723                 cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic, bio);
3724                 cic_set_cfqq(cic, cfqq, false);
3725         }
3726
3727         cfqq = cic_to_cfqq(cic, true);
3728         if (cfqq)
3729                 cfq_mark_cfqq_prio_changed(cfqq);
3730
3731         cic->ioprio = ioprio;
3732 }
3733
3734 static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3735                           pid_t pid, bool is_sync)
3736 {
3737         RB_CLEAR_NODE(&cfqq->rb_node);
3738         RB_CLEAR_NODE(&cfqq->p_node);
3739         INIT_LIST_HEAD(&cfqq->fifo);
3740
3741         cfqq->ref = 0;
3742         cfqq->cfqd = cfqd;
3743
3744         cfq_mark_cfqq_prio_changed(cfqq);
3745
3746         if (is_sync) {
3747                 if (!cfq_class_idle(cfqq))
3748                         cfq_mark_cfqq_idle_window(cfqq);
3749                 cfq_mark_cfqq_sync(cfqq);
3750         }
3751         cfqq->pid = pid;
3752 }
3753
3754 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3755 static void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio)
3756 {
3757         struct cfq_data *cfqd = cic_to_cfqd(cic);
3758         struct cfq_queue *cfqq;
3759         uint64_t serial_nr;
3760
3761         rcu_read_lock();
3762         serial_nr = bio_blkcg(bio)->css.serial_nr;
3763         rcu_read_unlock();
3764
3765         /*
3766          * Check whether blkcg has changed.  The condition may trigger
3767          * spuriously on a newly created cic but there's no harm.
3768          */
3769         if (unlikely(!cfqd) || likely(cic->blkcg_serial_nr == serial_nr))
3770                 return;
3771
3772         /*
3773          * Drop reference to queues.  New queues will be assigned in new
3774          * group upon arrival of fresh requests.
3775          */
3776         cfqq = cic_to_cfqq(cic, false);
3777         if (cfqq) {
3778                 cfq_log_cfqq(cfqd, cfqq, "changed cgroup");
3779                 cic_set_cfqq(cic, NULL, false);
3780                 cfq_put_queue(cfqq);
3781         }
3782
3783         cfqq = cic_to_cfqq(cic, true);
3784         if (cfqq) {
3785                 cfq_log_cfqq(cfqd, cfqq, "changed cgroup");
3786                 cic_set_cfqq(cic, NULL, true);
3787                 cfq_put_queue(cfqq);
3788         }
3789
3790         cic->blkcg_serial_nr = serial_nr;
3791 }
3792 #else
3793 static inline void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio)
3794 {
3795 }
3796 #endif  /* CONFIG_CFQ_GROUP_IOSCHED */
3797
3798 static struct cfq_queue **
3799 cfq_async_queue_prio(struct cfq_group *cfqg, int ioprio_class, int ioprio)
3800 {
3801         switch (ioprio_class) {
3802         case IOPRIO_CLASS_RT:
3803                 return &cfqg->async_cfqq[0][ioprio];
3804         case IOPRIO_CLASS_NONE:
3805                 ioprio = IOPRIO_NORM;
3806                 /* fall through */
3807         case IOPRIO_CLASS_BE:
3808                 return &cfqg->async_cfqq[1][ioprio];
3809         case IOPRIO_CLASS_IDLE:
3810                 return &cfqg->async_idle_cfqq;
3811         default:
3812                 BUG();
3813         }
3814 }
3815
3816 static struct cfq_queue *
3817 cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct cfq_io_cq *cic,
3818               struct bio *bio)
3819 {
3820         int ioprio_class = IOPRIO_PRIO_CLASS(cic->ioprio);
3821         int ioprio = IOPRIO_PRIO_DATA(cic->ioprio);
3822         struct cfq_queue **async_cfqq = NULL;
3823         struct cfq_queue *cfqq;
3824         struct cfq_group *cfqg;
3825
3826         rcu_read_lock();
3827         cfqg = cfq_lookup_cfqg(cfqd, bio_blkcg(bio));
3828         if (!cfqg) {
3829                 cfqq = &cfqd->oom_cfqq;
3830                 goto out;
3831         }
3832
3833         if (!is_sync) {
3834                 if (!ioprio_valid(cic->ioprio)) {
3835                         struct task_struct *tsk = current;
3836                         ioprio = task_nice_ioprio(tsk);
3837                         ioprio_class = task_nice_ioclass(tsk);
3838                 }
3839                 async_cfqq = cfq_async_queue_prio(cfqg, ioprio_class, ioprio);
3840                 cfqq = *async_cfqq;
3841                 if (cfqq)
3842                         goto out;
3843         }
3844
3845         cfqq = kmem_cache_alloc_node(cfq_pool,
3846                                      GFP_NOWAIT | __GFP_ZERO | __GFP_NOWARN,
3847                                      cfqd->queue->node);
3848         if (!cfqq) {
3849                 cfqq = &cfqd->oom_cfqq;
3850                 goto out;
3851         }
3852
3853         /* cfq_init_cfqq() assumes cfqq->ioprio_class is initialized. */
3854         cfqq->ioprio_class = IOPRIO_CLASS_NONE;
3855         cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
3856         cfq_init_prio_data(cfqq, cic);
3857         cfq_link_cfqq_cfqg(cfqq, cfqg);
3858         cfq_log_cfqq(cfqd, cfqq, "alloced");
3859
3860         if (async_cfqq) {
3861                 /* a new async queue is created, pin and remember */
3862                 cfqq->ref++;
3863                 *async_cfqq = cfqq;
3864         }
3865 out:
3866         cfqq->ref++;
3867         rcu_read_unlock();
3868         return cfqq;
3869 }
3870
3871 static void
3872 __cfq_update_io_thinktime(struct cfq_ttime *ttime, u64 slice_idle)
3873 {
3874         u64 elapsed = ktime_get_ns() - ttime->last_end_request;
3875         elapsed = min(elapsed, 2UL * slice_idle);
3876
3877         ttime->ttime_samples = (7*ttime->ttime_samples + 256) / 8;
3878         ttime->ttime_total = div_u64(7*ttime->ttime_total + 256*elapsed,  8);
3879         ttime->ttime_mean = div64_ul(ttime->ttime_total + 128,
3880                                      ttime->ttime_samples);
3881 }
3882
3883 static void
3884 cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3885                         struct cfq_io_cq *cic)
3886 {
3887         if (cfq_cfqq_sync(cfqq)) {
3888                 __cfq_update_io_thinktime(&cic->ttime, cfqd->cfq_slice_idle);
3889                 __cfq_update_io_thinktime(&cfqq->service_tree->ttime,
3890                         cfqd->cfq_slice_idle);
3891         }
3892 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3893         __cfq_update_io_thinktime(&cfqq->cfqg->ttime, cfqd->cfq_group_idle);
3894 #endif
3895 }
3896
3897 static void
3898 cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3899                        struct request *rq)
3900 {
3901         sector_t sdist = 0;
3902         sector_t n_sec = blk_rq_sectors(rq);
3903         if (cfqq->last_request_pos) {
3904                 if (cfqq->last_request_pos < blk_rq_pos(rq))
3905                         sdist = blk_rq_pos(rq) - cfqq->last_request_pos;
3906                 else
3907                         sdist = cfqq->last_request_pos - blk_rq_pos(rq);
3908         }
3909
3910         cfqq->seek_history <<= 1;
3911         if (blk_queue_nonrot(cfqd->queue))
3912                 cfqq->seek_history |= (n_sec < CFQQ_SECT_THR_NONROT);
3913         else
3914                 cfqq->seek_history |= (sdist > CFQQ_SEEK_THR);
3915 }
3916
3917 static inline bool req_noidle(struct request *req)
3918 {
3919         return req_op(req) == REQ_OP_WRITE &&
3920                 (req->cmd_flags & (REQ_SYNC&nb