blkio: Fix compile errors
[linux-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/blkdev.h>
12 #include <linux/elevator.h>
13 #include <linux/jiffies.h>
14 #include <linux/rbtree.h>
15 #include <linux/ioprio.h>
16 #include <linux/blktrace_api.h>
17 #include "blk-cgroup.h"
18
19 /*
20  * tunables
21  */
22 /* max queue in one round of service */
23 static const int cfq_quantum = 8;
24 static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 };
25 /* maximum backwards seek, in KiB */
26 static const int cfq_back_max = 16 * 1024;
27 /* penalty of a backwards seek */
28 static const int cfq_back_penalty = 2;
29 static const int cfq_slice_sync = HZ / 10;
30 static int cfq_slice_async = HZ / 25;
31 static const int cfq_slice_async_rq = 2;
32 static int cfq_slice_idle = HZ / 125;
33 static const int cfq_target_latency = HZ * 3/10; /* 300 ms */
34 static const int cfq_hist_divisor = 4;
35
36 /*
37  * offset from end of service tree
38  */
39 #define CFQ_IDLE_DELAY          (HZ / 5)
40
41 /*
42  * below this threshold, we consider thinktime immediate
43  */
44 #define CFQ_MIN_TT              (2)
45
46 #define CFQ_SLICE_SCALE         (5)
47 #define CFQ_HW_QUEUE_MIN        (5)
48 #define CFQ_SERVICE_SHIFT       12
49
50 #define CFQQ_SEEK_THR           (sector_t)(8 * 100)
51 #define CFQQ_CLOSE_THR          (sector_t)(8 * 1024)
52 #define CFQQ_SECT_THR_NONROT    (sector_t)(2 * 32)
53 #define CFQQ_SEEKY(cfqq)        (hweight32(cfqq->seek_history) > 32/8)
54
55 #define RQ_CIC(rq)              \
56         ((struct cfq_io_context *) (rq)->elevator_private)
57 #define RQ_CFQQ(rq)             (struct cfq_queue *) ((rq)->elevator_private2)
58
59 static struct kmem_cache *cfq_pool;
60 static struct kmem_cache *cfq_ioc_pool;
61
62 static DEFINE_PER_CPU(unsigned long, cfq_ioc_count);
63 static struct completion *ioc_gone;
64 static DEFINE_SPINLOCK(ioc_gone_lock);
65
66 #define CFQ_PRIO_LISTS          IOPRIO_BE_NR
67 #define cfq_class_idle(cfqq)    ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
68 #define cfq_class_rt(cfqq)      ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
69
70 #define sample_valid(samples)   ((samples) > 80)
71 #define rb_entry_cfqg(node)     rb_entry((node), struct cfq_group, rb_node)
72
73 /*
74  * Most of our rbtree usage is for sorting with min extraction, so
75  * if we cache the leftmost node we don't have to walk down the tree
76  * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should
77  * move this into the elevator for the rq sorting as well.
78  */
79 struct cfq_rb_root {
80         struct rb_root rb;
81         struct rb_node *left;
82         unsigned count;
83         unsigned total_weight;
84         u64 min_vdisktime;
85         struct rb_node *active;
86 };
87 #define CFQ_RB_ROOT     (struct cfq_rb_root) { .rb = RB_ROOT, .left = NULL, \
88                         .count = 0, .min_vdisktime = 0, }
89
90 /*
91  * Per process-grouping structure
92  */
93 struct cfq_queue {
94         /* reference count */
95         atomic_t ref;
96         /* various state flags, see below */
97         unsigned int flags;
98         /* parent cfq_data */
99         struct cfq_data *cfqd;
100         /* service_tree member */
101         struct rb_node rb_node;
102         /* service_tree key */
103         unsigned long rb_key;
104         /* prio tree member */
105         struct rb_node p_node;
106         /* prio tree root we belong to, if any */
107         struct rb_root *p_root;
108         /* sorted list of pending requests */
109         struct rb_root sort_list;
110         /* if fifo isn't expired, next request to serve */
111         struct request *next_rq;
112         /* requests queued in sort_list */
113         int queued[2];
114         /* currently allocated requests */
115         int allocated[2];
116         /* fifo list of requests in sort_list */
117         struct list_head fifo;
118
119         /* time when queue got scheduled in to dispatch first request. */
120         unsigned long dispatch_start;
121         unsigned int allocated_slice;
122         unsigned int slice_dispatch;
123         /* time when first request from queue completed and slice started. */
124         unsigned long slice_start;
125         unsigned long slice_end;
126         long slice_resid;
127
128         /* pending metadata requests */
129         int meta_pending;
130         /* number of requests that are on the dispatch list or inside driver */
131         int dispatched;
132
133         /* io prio of this group */
134         unsigned short ioprio, org_ioprio;
135         unsigned short ioprio_class, org_ioprio_class;
136
137         pid_t pid;
138
139         u32 seek_history;
140         sector_t last_request_pos;
141
142         struct cfq_rb_root *service_tree;
143         struct cfq_queue *new_cfqq;
144         struct cfq_group *cfqg;
145         struct cfq_group *orig_cfqg;
146 };
147
148 /*
149  * First index in the service_trees.
150  * IDLE is handled separately, so it has negative index
151  */
152 enum wl_prio_t {
153         BE_WORKLOAD = 0,
154         RT_WORKLOAD = 1,
155         IDLE_WORKLOAD = 2,
156 };
157
158 /*
159  * Second index in the service_trees.
160  */
161 enum wl_type_t {
162         ASYNC_WORKLOAD = 0,
163         SYNC_NOIDLE_WORKLOAD = 1,
164         SYNC_WORKLOAD = 2
165 };
166
167 /* This is per cgroup per device grouping structure */
168 struct cfq_group {
169         /* group service_tree member */
170         struct rb_node rb_node;
171
172         /* group service_tree key */
173         u64 vdisktime;
174         unsigned int weight;
175         bool on_st;
176
177         /* number of cfqq currently on this group */
178         int nr_cfqq;
179
180         /* Per group busy queus average. Useful for workload slice calc. */
181         unsigned int busy_queues_avg[2];
182         /*
183          * rr lists of queues with requests, onle rr for each priority class.
184          * Counts are embedded in the cfq_rb_root
185          */
186         struct cfq_rb_root service_trees[2][3];
187         struct cfq_rb_root service_tree_idle;
188
189         unsigned long saved_workload_slice;
190         enum wl_type_t saved_workload;
191         enum wl_prio_t saved_serving_prio;
192         struct blkio_group blkg;
193 #ifdef CONFIG_CFQ_GROUP_IOSCHED
194         struct hlist_node cfqd_node;
195         atomic_t ref;
196 #endif
197 };
198
199 /*
200  * Per block device queue structure
201  */
202 struct cfq_data {
203         struct request_queue *queue;
204         /* Root service tree for cfq_groups */
205         struct cfq_rb_root grp_service_tree;
206         struct cfq_group root_group;
207
208         /*
209          * The priority currently being served
210          */
211         enum wl_prio_t serving_prio;
212         enum wl_type_t serving_type;
213         unsigned long workload_expires;
214         struct cfq_group *serving_group;
215         bool noidle_tree_requires_idle;
216
217         /*
218          * Each priority tree is sorted by next_request position.  These
219          * trees are used when determining if two or more queues are
220          * interleaving requests (see cfq_close_cooperator).
221          */
222         struct rb_root prio_trees[CFQ_PRIO_LISTS];
223
224         unsigned int busy_queues;
225
226         int rq_in_driver;
227         int rq_in_flight[2];
228
229         /*
230          * queue-depth detection
231          */
232         int rq_queued;
233         int hw_tag;
234         /*
235          * hw_tag can be
236          * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection)
237          *  1 => NCQ is present (hw_tag_est_depth is the estimated max depth)
238          *  0 => no NCQ
239          */
240         int hw_tag_est_depth;
241         unsigned int hw_tag_samples;
242
243         /*
244          * idle window management
245          */
246         struct timer_list idle_slice_timer;
247         struct work_struct unplug_work;
248
249         struct cfq_queue *active_queue;
250         struct cfq_io_context *active_cic;
251
252         /*
253          * async queue for each priority case
254          */
255         struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR];
256         struct cfq_queue *async_idle_cfqq;
257
258         sector_t last_position;
259
260         /*
261          * tunables, see top of file
262          */
263         unsigned int cfq_quantum;
264         unsigned int cfq_fifo_expire[2];
265         unsigned int cfq_back_penalty;
266         unsigned int cfq_back_max;
267         unsigned int cfq_slice[2];
268         unsigned int cfq_slice_async_rq;
269         unsigned int cfq_slice_idle;
270         unsigned int cfq_latency;
271         unsigned int cfq_group_isolation;
272
273         struct list_head cic_list;
274
275         /*
276          * Fallback dummy cfqq for extreme OOM conditions
277          */
278         struct cfq_queue oom_cfqq;
279
280         unsigned long last_delayed_sync;
281
282         /* List of cfq groups being managed on this device*/
283         struct hlist_head cfqg_list;
284         struct rcu_head rcu;
285 };
286
287 static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd);
288
289 static struct cfq_rb_root *service_tree_for(struct cfq_group *cfqg,
290                                             enum wl_prio_t prio,
291                                             enum wl_type_t type)
292 {
293         if (!cfqg)
294                 return NULL;
295
296         if (prio == IDLE_WORKLOAD)
297                 return &cfqg->service_tree_idle;
298
299         return &cfqg->service_trees[prio][type];
300 }
301
302 enum cfqq_state_flags {
303         CFQ_CFQQ_FLAG_on_rr = 0,        /* on round-robin busy list */
304         CFQ_CFQQ_FLAG_wait_request,     /* waiting for a request */
305         CFQ_CFQQ_FLAG_must_dispatch,    /* must be allowed a dispatch */
306         CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */
307         CFQ_CFQQ_FLAG_fifo_expire,      /* FIFO checked in this slice */
308         CFQ_CFQQ_FLAG_idle_window,      /* slice idling enabled */
309         CFQ_CFQQ_FLAG_prio_changed,     /* task priority has changed */
310         CFQ_CFQQ_FLAG_slice_new,        /* no requests dispatched in slice */
311         CFQ_CFQQ_FLAG_sync,             /* synchronous queue */
312         CFQ_CFQQ_FLAG_coop,             /* cfqq is shared */
313         CFQ_CFQQ_FLAG_split_coop,       /* shared cfqq will be splitted */
314         CFQ_CFQQ_FLAG_deep,             /* sync cfqq experienced large depth */
315         CFQ_CFQQ_FLAG_wait_busy,        /* Waiting for next request */
316 };
317
318 #define CFQ_CFQQ_FNS(name)                                              \
319 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq)         \
320 {                                                                       \
321         (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name);                   \
322 }                                                                       \
323 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq)        \
324 {                                                                       \
325         (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name);                  \
326 }                                                                       \
327 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq)         \
328 {                                                                       \
329         return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0;      \
330 }
331
332 CFQ_CFQQ_FNS(on_rr);
333 CFQ_CFQQ_FNS(wait_request);
334 CFQ_CFQQ_FNS(must_dispatch);
335 CFQ_CFQQ_FNS(must_alloc_slice);
336 CFQ_CFQQ_FNS(fifo_expire);
337 CFQ_CFQQ_FNS(idle_window);
338 CFQ_CFQQ_FNS(prio_changed);
339 CFQ_CFQQ_FNS(slice_new);
340 CFQ_CFQQ_FNS(sync);
341 CFQ_CFQQ_FNS(coop);
342 CFQ_CFQQ_FNS(split_coop);
343 CFQ_CFQQ_FNS(deep);
344 CFQ_CFQQ_FNS(wait_busy);
345 #undef CFQ_CFQQ_FNS
346
347 #ifdef CONFIG_DEBUG_CFQ_IOSCHED
348 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...)  \
349         blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \
350                         cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
351                         blkg_path(&(cfqq)->cfqg->blkg), ##args);
352
353 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...)                          \
354         blk_add_trace_msg((cfqd)->queue, "%s " fmt,                     \
355                                 blkg_path(&(cfqg)->blkg), ##args);      \
356
357 #else
358 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...)  \
359         blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
360 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...)          do {} while (0);
361 #endif
362 #define cfq_log(cfqd, fmt, args...)     \
363         blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
364
365 /* Traverses through cfq group service trees */
366 #define for_each_cfqg_st(cfqg, i, j, st) \
367         for (i = 0; i <= IDLE_WORKLOAD; i++) \
368                 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
369                         : &cfqg->service_tree_idle; \
370                         (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \
371                         (i == IDLE_WORKLOAD && j == 0); \
372                         j++, st = i < IDLE_WORKLOAD ? \
373                         &cfqg->service_trees[i][j]: NULL) \
374
375
376 static inline enum wl_prio_t cfqq_prio(struct cfq_queue *cfqq)
377 {
378         if (cfq_class_idle(cfqq))
379                 return IDLE_WORKLOAD;
380         if (cfq_class_rt(cfqq))
381                 return RT_WORKLOAD;
382         return BE_WORKLOAD;
383 }
384
385
386 static enum wl_type_t cfqq_type(struct cfq_queue *cfqq)
387 {
388         if (!cfq_cfqq_sync(cfqq))
389                 return ASYNC_WORKLOAD;
390         if (!cfq_cfqq_idle_window(cfqq))
391                 return SYNC_NOIDLE_WORKLOAD;
392         return SYNC_WORKLOAD;
393 }
394
395 static inline int cfq_group_busy_queues_wl(enum wl_prio_t wl,
396                                         struct cfq_data *cfqd,
397                                         struct cfq_group *cfqg)
398 {
399         if (wl == IDLE_WORKLOAD)
400                 return cfqg->service_tree_idle.count;
401
402         return cfqg->service_trees[wl][ASYNC_WORKLOAD].count
403                 + cfqg->service_trees[wl][SYNC_NOIDLE_WORKLOAD].count
404                 + cfqg->service_trees[wl][SYNC_WORKLOAD].count;
405 }
406
407 static inline int cfqg_busy_async_queues(struct cfq_data *cfqd,
408                                         struct cfq_group *cfqg)
409 {
410         return cfqg->service_trees[RT_WORKLOAD][ASYNC_WORKLOAD].count
411                 + cfqg->service_trees[BE_WORKLOAD][ASYNC_WORKLOAD].count;
412 }
413
414 static void cfq_dispatch_insert(struct request_queue *, struct request *);
415 static struct cfq_queue *cfq_get_queue(struct cfq_data *, bool,
416                                        struct io_context *, gfp_t);
417 static struct cfq_io_context *cfq_cic_lookup(struct cfq_data *,
418                                                 struct io_context *);
419
420 static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic,
421                                             bool is_sync)
422 {
423         return cic->cfqq[is_sync];
424 }
425
426 static inline void cic_set_cfqq(struct cfq_io_context *cic,
427                                 struct cfq_queue *cfqq, bool is_sync)
428 {
429         cic->cfqq[is_sync] = cfqq;
430 }
431
432 /*
433  * We regard a request as SYNC, if it's either a read or has the SYNC bit
434  * set (in which case it could also be direct WRITE).
435  */
436 static inline bool cfq_bio_sync(struct bio *bio)
437 {
438         return bio_data_dir(bio) == READ || bio_rw_flagged(bio, BIO_RW_SYNCIO);
439 }
440
441 /*
442  * scheduler run of queue, if there are requests pending and no one in the
443  * driver that will restart queueing
444  */
445 static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
446 {
447         if (cfqd->busy_queues) {
448                 cfq_log(cfqd, "schedule dispatch");
449                 kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work);
450         }
451 }
452
453 static int cfq_queue_empty(struct request_queue *q)
454 {
455         struct cfq_data *cfqd = q->elevator->elevator_data;
456
457         return !cfqd->rq_queued;
458 }
459
460 /*
461  * Scale schedule slice based on io priority. Use the sync time slice only
462  * if a queue is marked sync and has sync io queued. A sync queue with async
463  * io only, should not get full sync slice length.
464  */
465 static inline int cfq_prio_slice(struct cfq_data *cfqd, bool sync,
466                                  unsigned short prio)
467 {
468         const int base_slice = cfqd->cfq_slice[sync];
469
470         WARN_ON(prio >= IOPRIO_BE_NR);
471
472         return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio));
473 }
474
475 static inline int
476 cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
477 {
478         return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
479 }
480
481 static inline u64 cfq_scale_slice(unsigned long delta, struct cfq_group *cfqg)
482 {
483         u64 d = delta << CFQ_SERVICE_SHIFT;
484
485         d = d * BLKIO_WEIGHT_DEFAULT;
486         do_div(d, cfqg->weight);
487         return d;
488 }
489
490 static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime)
491 {
492         s64 delta = (s64)(vdisktime - min_vdisktime);
493         if (delta > 0)
494                 min_vdisktime = vdisktime;
495
496         return min_vdisktime;
497 }
498
499 static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime)
500 {
501         s64 delta = (s64)(vdisktime - min_vdisktime);
502         if (delta < 0)
503                 min_vdisktime = vdisktime;
504
505         return min_vdisktime;
506 }
507
508 static void update_min_vdisktime(struct cfq_rb_root *st)
509 {
510         u64 vdisktime = st->min_vdisktime;
511         struct cfq_group *cfqg;
512
513         if (st->active) {
514                 cfqg = rb_entry_cfqg(st->active);
515                 vdisktime = cfqg->vdisktime;
516         }
517
518         if (st->left) {
519                 cfqg = rb_entry_cfqg(st->left);
520                 vdisktime = min_vdisktime(vdisktime, cfqg->vdisktime);
521         }
522
523         st->min_vdisktime = max_vdisktime(st->min_vdisktime, vdisktime);
524 }
525
526 /*
527  * get averaged number of queues of RT/BE priority.
528  * average is updated, with a formula that gives more weight to higher numbers,
529  * to quickly follows sudden increases and decrease slowly
530  */
531
532 static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd,
533                                         struct cfq_group *cfqg, bool rt)
534 {
535         unsigned min_q, max_q;
536         unsigned mult  = cfq_hist_divisor - 1;
537         unsigned round = cfq_hist_divisor / 2;
538         unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg);
539
540         min_q = min(cfqg->busy_queues_avg[rt], busy);
541         max_q = max(cfqg->busy_queues_avg[rt], busy);
542         cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) /
543                 cfq_hist_divisor;
544         return cfqg->busy_queues_avg[rt];
545 }
546
547 static inline unsigned
548 cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg)
549 {
550         struct cfq_rb_root *st = &cfqd->grp_service_tree;
551
552         return cfq_target_latency * cfqg->weight / st->total_weight;
553 }
554
555 static inline void
556 cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
557 {
558         unsigned slice = cfq_prio_to_slice(cfqd, cfqq);
559         if (cfqd->cfq_latency) {
560                 /*
561                  * interested queues (we consider only the ones with the same
562                  * priority class in the cfq group)
563                  */
564                 unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg,
565                                                 cfq_class_rt(cfqq));
566                 unsigned sync_slice = cfqd->cfq_slice[1];
567                 unsigned expect_latency = sync_slice * iq;
568                 unsigned group_slice = cfq_group_slice(cfqd, cfqq->cfqg);
569
570                 if (expect_latency > group_slice) {
571                         unsigned base_low_slice = 2 * cfqd->cfq_slice_idle;
572                         /* scale low_slice according to IO priority
573                          * and sync vs async */
574                         unsigned low_slice =
575                                 min(slice, base_low_slice * slice / sync_slice);
576                         /* the adapted slice value is scaled to fit all iqs
577                          * into the target latency */
578                         slice = max(slice * group_slice / expect_latency,
579                                     low_slice);
580                 }
581         }
582         cfqq->slice_start = jiffies;
583         cfqq->slice_end = jiffies + slice;
584         cfqq->allocated_slice = slice;
585         cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies);
586 }
587
588 /*
589  * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
590  * isn't valid until the first request from the dispatch is activated
591  * and the slice time set.
592  */
593 static inline bool cfq_slice_used(struct cfq_queue *cfqq)
594 {
595         if (cfq_cfqq_slice_new(cfqq))
596                 return 0;
597         if (time_before(jiffies, cfqq->slice_end))
598                 return 0;
599
600         return 1;
601 }
602
603 /*
604  * Lifted from AS - choose which of rq1 and rq2 that is best served now.
605  * We choose the request that is closest to the head right now. Distance
606  * behind the head is penalized and only allowed to a certain extent.
607  */
608 static struct request *
609 cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last)
610 {
611         sector_t s1, s2, d1 = 0, d2 = 0;
612         unsigned long back_max;
613 #define CFQ_RQ1_WRAP    0x01 /* request 1 wraps */
614 #define CFQ_RQ2_WRAP    0x02 /* request 2 wraps */
615         unsigned wrap = 0; /* bit mask: requests behind the disk head? */
616
617         if (rq1 == NULL || rq1 == rq2)
618                 return rq2;
619         if (rq2 == NULL)
620                 return rq1;
621
622         if (rq_is_sync(rq1) && !rq_is_sync(rq2))
623                 return rq1;
624         else if (rq_is_sync(rq2) && !rq_is_sync(rq1))
625                 return rq2;
626         if (rq_is_meta(rq1) && !rq_is_meta(rq2))
627                 return rq1;
628         else if (rq_is_meta(rq2) && !rq_is_meta(rq1))
629                 return rq2;
630
631         s1 = blk_rq_pos(rq1);
632         s2 = blk_rq_pos(rq2);
633
634         /*
635          * by definition, 1KiB is 2 sectors
636          */
637         back_max = cfqd->cfq_back_max * 2;
638
639         /*
640          * Strict one way elevator _except_ in the case where we allow
641          * short backward seeks which are biased as twice the cost of a
642          * similar forward seek.
643          */
644         if (s1 >= last)
645                 d1 = s1 - last;
646         else if (s1 + back_max >= last)
647                 d1 = (last - s1) * cfqd->cfq_back_penalty;
648         else
649                 wrap |= CFQ_RQ1_WRAP;
650
651         if (s2 >= last)
652                 d2 = s2 - last;
653         else if (s2 + back_max >= last)
654                 d2 = (last - s2) * cfqd->cfq_back_penalty;
655         else
656                 wrap |= CFQ_RQ2_WRAP;
657
658         /* Found required data */
659
660         /*
661          * By doing switch() on the bit mask "wrap" we avoid having to
662          * check two variables for all permutations: --> faster!
663          */
664         switch (wrap) {
665         case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
666                 if (d1 < d2)
667                         return rq1;
668                 else if (d2 < d1)
669                         return rq2;
670                 else {
671                         if (s1 >= s2)
672                                 return rq1;
673                         else
674                                 return rq2;
675                 }
676
677         case CFQ_RQ2_WRAP:
678                 return rq1;
679         case CFQ_RQ1_WRAP:
680                 return rq2;
681         case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */
682         default:
683                 /*
684                  * Since both rqs are wrapped,
685                  * start with the one that's further behind head
686                  * (--> only *one* back seek required),
687                  * since back seek takes more time than forward.
688                  */
689                 if (s1 <= s2)
690                         return rq1;
691                 else
692                         return rq2;
693         }
694 }
695
696 /*
697  * The below is leftmost cache rbtree addon
698  */
699 static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
700 {
701         /* Service tree is empty */
702         if (!root->count)
703                 return NULL;
704
705         if (!root->left)
706                 root->left = rb_first(&root->rb);
707
708         if (root->left)
709                 return rb_entry(root->left, struct cfq_queue, rb_node);
710
711         return NULL;
712 }
713
714 static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root)
715 {
716         if (!root->left)
717                 root->left = rb_first(&root->rb);
718
719         if (root->left)
720                 return rb_entry_cfqg(root->left);
721
722         return NULL;
723 }
724
725 static void rb_erase_init(struct rb_node *n, struct rb_root *root)
726 {
727         rb_erase(n, root);
728         RB_CLEAR_NODE(n);
729 }
730
731 static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)
732 {
733         if (root->left == n)
734                 root->left = NULL;
735         rb_erase_init(n, &root->rb);
736         --root->count;
737 }
738
739 /*
740  * would be nice to take fifo expire time into account as well
741  */
742 static struct request *
743 cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
744                   struct request *last)
745 {
746         struct rb_node *rbnext = rb_next(&last->rb_node);
747         struct rb_node *rbprev = rb_prev(&last->rb_node);
748         struct request *next = NULL, *prev = NULL;
749
750         BUG_ON(RB_EMPTY_NODE(&last->rb_node));
751
752         if (rbprev)
753                 prev = rb_entry_rq(rbprev);
754
755         if (rbnext)
756                 next = rb_entry_rq(rbnext);
757         else {
758                 rbnext = rb_first(&cfqq->sort_list);
759                 if (rbnext && rbnext != &last->rb_node)
760                         next = rb_entry_rq(rbnext);
761         }
762
763         return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last));
764 }
765
766 static unsigned long cfq_slice_offset(struct cfq_data *cfqd,
767                                       struct cfq_queue *cfqq)
768 {
769         /*
770          * just an approximation, should be ok.
771          */
772         return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) -
773                        cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio));
774 }
775
776 static inline s64
777 cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg)
778 {
779         return cfqg->vdisktime - st->min_vdisktime;
780 }
781
782 static void
783 __cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
784 {
785         struct rb_node **node = &st->rb.rb_node;
786         struct rb_node *parent = NULL;
787         struct cfq_group *__cfqg;
788         s64 key = cfqg_key(st, cfqg);
789         int left = 1;
790
791         while (*node != NULL) {
792                 parent = *node;
793                 __cfqg = rb_entry_cfqg(parent);
794
795                 if (key < cfqg_key(st, __cfqg))
796                         node = &parent->rb_left;
797                 else {
798                         node = &parent->rb_right;
799                         left = 0;
800                 }
801         }
802
803         if (left)
804                 st->left = &cfqg->rb_node;
805
806         rb_link_node(&cfqg->rb_node, parent, node);
807         rb_insert_color(&cfqg->rb_node, &st->rb);
808 }
809
810 static void
811 cfq_group_service_tree_add(struct cfq_data *cfqd, struct cfq_group *cfqg)
812 {
813         struct cfq_rb_root *st = &cfqd->grp_service_tree;
814         struct cfq_group *__cfqg;
815         struct rb_node *n;
816
817         cfqg->nr_cfqq++;
818         if (cfqg->on_st)
819                 return;
820
821         /*
822          * Currently put the group at the end. Later implement something
823          * so that groups get lesser vtime based on their weights, so that
824          * if group does not loose all if it was not continously backlogged.
825          */
826         n = rb_last(&st->rb);
827         if (n) {
828                 __cfqg = rb_entry_cfqg(n);
829                 cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY;
830         } else
831                 cfqg->vdisktime = st->min_vdisktime;
832
833         __cfq_group_service_tree_add(st, cfqg);
834         cfqg->on_st = true;
835         st->total_weight += cfqg->weight;
836 }
837
838 static void
839 cfq_group_service_tree_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
840 {
841         struct cfq_rb_root *st = &cfqd->grp_service_tree;
842
843         if (st->active == &cfqg->rb_node)
844                 st->active = NULL;
845
846         BUG_ON(cfqg->nr_cfqq < 1);
847         cfqg->nr_cfqq--;
848
849         /* If there are other cfq queues under this group, don't delete it */
850         if (cfqg->nr_cfqq)
851                 return;
852
853         cfq_log_cfqg(cfqd, cfqg, "del_from_rr group");
854         cfqg->on_st = false;
855         st->total_weight -= cfqg->weight;
856         if (!RB_EMPTY_NODE(&cfqg->rb_node))
857                 cfq_rb_erase(&cfqg->rb_node, st);
858         cfqg->saved_workload_slice = 0;
859         blkiocg_update_dequeue_stats(&cfqg->blkg, 1);
860 }
861
862 static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq)
863 {
864         unsigned int slice_used;
865
866         /*
867          * Queue got expired before even a single request completed or
868          * got expired immediately after first request completion.
869          */
870         if (!cfqq->slice_start || cfqq->slice_start == jiffies) {
871                 /*
872                  * Also charge the seek time incurred to the group, otherwise
873                  * if there are mutiple queues in the group, each can dispatch
874                  * a single request on seeky media and cause lots of seek time
875                  * and group will never know it.
876                  */
877                 slice_used = max_t(unsigned, (jiffies - cfqq->dispatch_start),
878                                         1);
879         } else {
880                 slice_used = jiffies - cfqq->slice_start;
881                 if (slice_used > cfqq->allocated_slice)
882                         slice_used = cfqq->allocated_slice;
883         }
884
885         cfq_log_cfqq(cfqq->cfqd, cfqq, "sl_used=%u", slice_used);
886         return slice_used;
887 }
888
889 static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
890                                 struct cfq_queue *cfqq, bool forced)
891 {
892         struct cfq_rb_root *st = &cfqd->grp_service_tree;
893         unsigned int used_sl, charge_sl;
894         int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg)
895                         - cfqg->service_tree_idle.count;
896
897         BUG_ON(nr_sync < 0);
898         used_sl = charge_sl = cfq_cfqq_slice_usage(cfqq);
899
900         if (!cfq_cfqq_sync(cfqq) && !nr_sync)
901                 charge_sl = cfqq->allocated_slice;
902
903         /* Can't update vdisktime while group is on service tree */
904         cfq_rb_erase(&cfqg->rb_node, st);
905         cfqg->vdisktime += cfq_scale_slice(charge_sl, cfqg);
906         __cfq_group_service_tree_add(st, cfqg);
907
908         /* This group is being expired. Save the context */
909         if (time_after(cfqd->workload_expires, jiffies)) {
910                 cfqg->saved_workload_slice = cfqd->workload_expires
911                                                 - jiffies;
912                 cfqg->saved_workload = cfqd->serving_type;
913                 cfqg->saved_serving_prio = cfqd->serving_prio;
914         } else
915                 cfqg->saved_workload_slice = 0;
916
917         cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime,
918                                         st->min_vdisktime);
919         blkiocg_update_timeslice_used(&cfqg->blkg, used_sl);
920         blkiocg_set_start_empty_time(&cfqg->blkg, forced);
921 }
922
923 #ifdef CONFIG_CFQ_GROUP_IOSCHED
924 static inline struct cfq_group *cfqg_of_blkg(struct blkio_group *blkg)
925 {
926         if (blkg)
927                 return container_of(blkg, struct cfq_group, blkg);
928         return NULL;
929 }
930
931 void
932 cfq_update_blkio_group_weight(struct blkio_group *blkg, unsigned int weight)
933 {
934         cfqg_of_blkg(blkg)->weight = weight;
935 }
936
937 static struct cfq_group *
938 cfq_find_alloc_cfqg(struct cfq_data *cfqd, struct cgroup *cgroup, int create)
939 {
940         struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup);
941         struct cfq_group *cfqg = NULL;
942         void *key = cfqd;
943         int i, j;
944         struct cfq_rb_root *st;
945         struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info;
946         unsigned int major, minor;
947
948         cfqg = cfqg_of_blkg(blkiocg_lookup_group(blkcg, key));
949         if (cfqg && !cfqg->blkg.dev && bdi->dev && dev_name(bdi->dev)) {
950                 sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
951                 cfqg->blkg.dev = MKDEV(major, minor);
952                 goto done;
953         }
954         if (cfqg || !create)
955                 goto done;
956
957         cfqg = kzalloc_node(sizeof(*cfqg), GFP_ATOMIC, cfqd->queue->node);
958         if (!cfqg)
959                 goto done;
960
961         for_each_cfqg_st(cfqg, i, j, st)
962                 *st = CFQ_RB_ROOT;
963         RB_CLEAR_NODE(&cfqg->rb_node);
964         blkio_group_init(&cfqg->blkg);
965
966         /*
967          * Take the initial reference that will be released on destroy
968          * This can be thought of a joint reference by cgroup and
969          * elevator which will be dropped by either elevator exit
970          * or cgroup deletion path depending on who is exiting first.
971          */
972         atomic_set(&cfqg->ref, 1);
973
974         /* Add group onto cgroup list */
975         sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
976         blkiocg_add_blkio_group(blkcg, &cfqg->blkg, (void *)cfqd,
977                                         MKDEV(major, minor));
978         cfqg->weight = blkcg_get_weight(blkcg, cfqg->blkg.dev);
979
980         /* Add group on cfqd list */
981         hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list);
982
983 done:
984         return cfqg;
985 }
986
987 /*
988  * Search for the cfq group current task belongs to. If create = 1, then also
989  * create the cfq group if it does not exist. request_queue lock must be held.
990  */
991 static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create)
992 {
993         struct cgroup *cgroup;
994         struct cfq_group *cfqg = NULL;
995
996         rcu_read_lock();
997         cgroup = task_cgroup(current, blkio_subsys_id);
998         cfqg = cfq_find_alloc_cfqg(cfqd, cgroup, create);
999         if (!cfqg && create)
1000                 cfqg = &cfqd->root_group;
1001         rcu_read_unlock();
1002         return cfqg;
1003 }
1004
1005 static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg)
1006 {
1007         /* Currently, all async queues are mapped to root group */
1008         if (!cfq_cfqq_sync(cfqq))
1009                 cfqg = &cfqq->cfqd->root_group;
1010
1011         cfqq->cfqg = cfqg;
1012         /* cfqq reference on cfqg */
1013         atomic_inc(&cfqq->cfqg->ref);
1014 }
1015
1016 static void cfq_put_cfqg(struct cfq_group *cfqg)
1017 {
1018         struct cfq_rb_root *st;
1019         int i, j;
1020
1021         BUG_ON(atomic_read(&cfqg->ref) <= 0);
1022         if (!atomic_dec_and_test(&cfqg->ref))
1023                 return;
1024         for_each_cfqg_st(cfqg, i, j, st)
1025                 BUG_ON(!RB_EMPTY_ROOT(&st->rb) || st->active != NULL);
1026         kfree(cfqg);
1027 }
1028
1029 static void cfq_destroy_cfqg(struct cfq_data *cfqd, struct cfq_group *cfqg)
1030 {
1031         /* Something wrong if we are trying to remove same group twice */
1032         BUG_ON(hlist_unhashed(&cfqg->cfqd_node));
1033
1034         hlist_del_init(&cfqg->cfqd_node);
1035
1036         /*
1037          * Put the reference taken at the time of creation so that when all
1038          * queues are gone, group can be destroyed.
1039          */
1040         cfq_put_cfqg(cfqg);
1041 }
1042
1043 static void cfq_release_cfq_groups(struct cfq_data *cfqd)
1044 {
1045         struct hlist_node *pos, *n;
1046         struct cfq_group *cfqg;
1047
1048         hlist_for_each_entry_safe(cfqg, pos, n, &cfqd->cfqg_list, cfqd_node) {
1049                 /*
1050                  * If cgroup removal path got to blk_group first and removed
1051                  * it from cgroup list, then it will take care of destroying
1052                  * cfqg also.
1053                  */
1054                 if (!blkiocg_del_blkio_group(&cfqg->blkg))
1055                         cfq_destroy_cfqg(cfqd, cfqg);
1056         }
1057 }
1058
1059 /*
1060  * Blk cgroup controller notification saying that blkio_group object is being
1061  * delinked as associated cgroup object is going away. That also means that
1062  * no new IO will come in this group. So get rid of this group as soon as
1063  * any pending IO in the group is finished.
1064  *
1065  * This function is called under rcu_read_lock(). key is the rcu protected
1066  * pointer. That means "key" is a valid cfq_data pointer as long as we are rcu
1067  * read lock.
1068  *
1069  * "key" was fetched from blkio_group under blkio_cgroup->lock. That means
1070  * it should not be NULL as even if elevator was exiting, cgroup deltion
1071  * path got to it first.
1072  */
1073 void cfq_unlink_blkio_group(void *key, struct blkio_group *blkg)
1074 {
1075         unsigned long  flags;
1076         struct cfq_data *cfqd = key;
1077
1078         spin_lock_irqsave(cfqd->queue->queue_lock, flags);
1079         cfq_destroy_cfqg(cfqd, cfqg_of_blkg(blkg));
1080         spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
1081 }
1082
1083 #else /* GROUP_IOSCHED */
1084 static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create)
1085 {
1086         return &cfqd->root_group;
1087 }
1088 static inline void
1089 cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) {
1090         cfqq->cfqg = cfqg;
1091 }
1092
1093 static void cfq_release_cfq_groups(struct cfq_data *cfqd) {}
1094 static inline void cfq_put_cfqg(struct cfq_group *cfqg) {}
1095
1096 #endif /* GROUP_IOSCHED */
1097
1098 /*
1099  * The cfqd->service_trees holds all pending cfq_queue's that have
1100  * requests waiting to be processed. It is sorted in the order that
1101  * we will service the queues.
1102  */
1103 static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1104                                  bool add_front)
1105 {
1106         struct rb_node **p, *parent;
1107         struct cfq_queue *__cfqq;
1108         unsigned long rb_key;
1109         struct cfq_rb_root *service_tree;
1110         int left;
1111         int new_cfqq = 1;
1112         int group_changed = 0;
1113
1114 #ifdef CONFIG_CFQ_GROUP_IOSCHED
1115         if (!cfqd->cfq_group_isolation
1116             && cfqq_type(cfqq) == SYNC_NOIDLE_WORKLOAD
1117             && cfqq->cfqg && cfqq->cfqg != &cfqd->root_group) {
1118                 /* Move this cfq to root group */
1119                 cfq_log_cfqq(cfqd, cfqq, "moving to root group");
1120                 if (!RB_EMPTY_NODE(&cfqq->rb_node))
1121                         cfq_group_service_tree_del(cfqd, cfqq->cfqg);
1122                 cfqq->orig_cfqg = cfqq->cfqg;
1123                 cfqq->cfqg = &cfqd->root_group;
1124                 atomic_inc(&cfqd->root_group.ref);
1125                 group_changed = 1;
1126         } else if (!cfqd->cfq_group_isolation
1127                    && cfqq_type(cfqq) == SYNC_WORKLOAD && cfqq->orig_cfqg) {
1128                 /* cfqq is sequential now needs to go to its original group */
1129                 BUG_ON(cfqq->cfqg != &cfqd->root_group);
1130                 if (!RB_EMPTY_NODE(&cfqq->rb_node))
1131                         cfq_group_service_tree_del(cfqd, cfqq->cfqg);
1132                 cfq_put_cfqg(cfqq->cfqg);
1133                 cfqq->cfqg = cfqq->orig_cfqg;
1134                 cfqq->orig_cfqg = NULL;
1135                 group_changed = 1;
1136                 cfq_log_cfqq(cfqd, cfqq, "moved to origin group");
1137         }
1138 #endif
1139
1140         service_tree = service_tree_for(cfqq->cfqg, cfqq_prio(cfqq),
1141                                                 cfqq_type(cfqq));
1142         if (cfq_class_idle(cfqq)) {
1143                 rb_key = CFQ_IDLE_DELAY;
1144                 parent = rb_last(&service_tree->rb);
1145                 if (parent && parent != &cfqq->rb_node) {
1146                         __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
1147                         rb_key += __cfqq->rb_key;
1148                 } else
1149                         rb_key += jiffies;
1150         } else if (!add_front) {
1151                 /*
1152                  * Get our rb key offset. Subtract any residual slice
1153                  * value carried from last service. A negative resid
1154                  * count indicates slice overrun, and this should position
1155                  * the next service time further away in the tree.
1156                  */
1157                 rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies;
1158                 rb_key -= cfqq->slice_resid;
1159                 cfqq->slice_resid = 0;
1160         } else {
1161                 rb_key = -HZ;
1162                 __cfqq = cfq_rb_first(service_tree);
1163                 rb_key += __cfqq ? __cfqq->rb_key : jiffies;
1164         }
1165
1166         if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
1167                 new_cfqq = 0;
1168                 /*
1169                  * same position, nothing more to do
1170                  */
1171                 if (rb_key == cfqq->rb_key &&
1172                     cfqq->service_tree == service_tree)
1173                         return;
1174
1175                 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
1176                 cfqq->service_tree = NULL;
1177         }
1178
1179         left = 1;
1180         parent = NULL;
1181         cfqq->service_tree = service_tree;
1182         p = &service_tree->rb.rb_node;
1183         while (*p) {
1184                 struct rb_node **n;
1185
1186                 parent = *p;
1187                 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
1188
1189                 /*
1190                  * sort by key, that represents service time.
1191                  */
1192                 if (time_before(rb_key, __cfqq->rb_key))
1193                         n = &(*p)->rb_left;
1194                 else {
1195                         n = &(*p)->rb_right;
1196                         left = 0;
1197                 }
1198
1199                 p = n;
1200         }
1201
1202         if (left)
1203                 service_tree->left = &cfqq->rb_node;
1204
1205         cfqq->rb_key = rb_key;
1206         rb_link_node(&cfqq->rb_node, parent, p);
1207         rb_insert_color(&cfqq->rb_node, &service_tree->rb);
1208         service_tree->count++;
1209         if ((add_front || !new_cfqq) && !group_changed)
1210                 return;
1211         cfq_group_service_tree_add(cfqd, cfqq->cfqg);
1212 }
1213
1214 static struct cfq_queue *
1215 cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root,
1216                      sector_t sector, struct rb_node **ret_parent,
1217                      struct rb_node ***rb_link)
1218 {
1219         struct rb_node **p, *parent;
1220         struct cfq_queue *cfqq = NULL;
1221
1222         parent = NULL;
1223         p = &root->rb_node;
1224         while (*p) {
1225                 struct rb_node **n;
1226
1227                 parent = *p;
1228                 cfqq = rb_entry(parent, struct cfq_queue, p_node);
1229
1230                 /*
1231                  * Sort strictly based on sector.  Smallest to the left,
1232                  * largest to the right.
1233                  */
1234                 if (sector > blk_rq_pos(cfqq->next_rq))
1235                         n = &(*p)->rb_right;
1236                 else if (sector < blk_rq_pos(cfqq->next_rq))
1237                         n = &(*p)->rb_left;
1238                 else
1239                         break;
1240                 p = n;
1241                 cfqq = NULL;
1242         }
1243
1244         *ret_parent = parent;
1245         if (rb_link)
1246                 *rb_link = p;
1247         return cfqq;
1248 }
1249
1250 static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1251 {
1252         struct rb_node **p, *parent;
1253         struct cfq_queue *__cfqq;
1254
1255         if (cfqq->p_root) {
1256                 rb_erase(&cfqq->p_node, cfqq->p_root);
1257                 cfqq->p_root = NULL;
1258         }
1259
1260         if (cfq_class_idle(cfqq))
1261                 return;
1262         if (!cfqq->next_rq)
1263                 return;
1264
1265         cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
1266         __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root,
1267                                       blk_rq_pos(cfqq->next_rq), &parent, &p);
1268         if (!__cfqq) {
1269                 rb_link_node(&cfqq->p_node, parent, p);
1270                 rb_insert_color(&cfqq->p_node, cfqq->p_root);
1271         } else
1272                 cfqq->p_root = NULL;
1273 }
1274
1275 /*
1276  * Update cfqq's position in the service tree.
1277  */
1278 static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1279 {
1280         /*
1281          * Resorting requires the cfqq to be on the RR list already.
1282          */
1283         if (cfq_cfqq_on_rr(cfqq)) {
1284                 cfq_service_tree_add(cfqd, cfqq, 0);
1285                 cfq_prio_tree_add(cfqd, cfqq);
1286         }
1287 }
1288
1289 /*
1290  * add to busy list of queues for service, trying to be fair in ordering
1291  * the pending list according to last request service
1292  */
1293 static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1294 {
1295         cfq_log_cfqq(cfqd, cfqq, "add_to_rr");
1296         BUG_ON(cfq_cfqq_on_rr(cfqq));
1297         cfq_mark_cfqq_on_rr(cfqq);
1298         cfqd->busy_queues++;
1299
1300         cfq_resort_rr_list(cfqd, cfqq);
1301 }
1302
1303 /*
1304  * Called when the cfqq no longer has requests pending, remove it from
1305  * the service tree.
1306  */
1307 static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1308 {
1309         cfq_log_cfqq(cfqd, cfqq, "del_from_rr");
1310         BUG_ON(!cfq_cfqq_on_rr(cfqq));
1311         cfq_clear_cfqq_on_rr(cfqq);
1312
1313         if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
1314                 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
1315                 cfqq->service_tree = NULL;
1316         }
1317         if (cfqq->p_root) {
1318                 rb_erase(&cfqq->p_node, cfqq->p_root);
1319                 cfqq->p_root = NULL;
1320         }
1321
1322         cfq_group_service_tree_del(cfqd, cfqq->cfqg);
1323         BUG_ON(!cfqd->busy_queues);
1324         cfqd->busy_queues--;
1325 }
1326
1327 /*
1328  * rb tree support functions
1329  */
1330 static void cfq_del_rq_rb(struct request *rq)
1331 {
1332         struct cfq_queue *cfqq = RQ_CFQQ(rq);
1333         const int sync = rq_is_sync(rq);
1334
1335         BUG_ON(!cfqq->queued[sync]);
1336         cfqq->queued[sync]--;
1337
1338         elv_rb_del(&cfqq->sort_list, rq);
1339
1340         if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) {
1341                 /*
1342                  * Queue will be deleted from service tree when we actually
1343                  * expire it later. Right now just remove it from prio tree
1344                  * as it is empty.
1345                  */
1346                 if (cfqq->p_root) {
1347                         rb_erase(&cfqq->p_node, cfqq->p_root);
1348                         cfqq->p_root = NULL;
1349                 }
1350         }
1351 }
1352
1353 static void cfq_add_rq_rb(struct request *rq)
1354 {
1355         struct cfq_queue *cfqq = RQ_CFQQ(rq);
1356         struct cfq_data *cfqd = cfqq->cfqd;
1357         struct request *__alias, *prev;
1358
1359         cfqq->queued[rq_is_sync(rq)]++;
1360
1361         /*
1362          * looks a little odd, but the first insert might return an alias.
1363          * if that happens, put the alias on the dispatch list
1364          */
1365         while ((__alias = elv_rb_add(&cfqq->sort_list, rq)) != NULL)
1366                 cfq_dispatch_insert(cfqd->queue, __alias);
1367
1368         if (!cfq_cfqq_on_rr(cfqq))
1369                 cfq_add_cfqq_rr(cfqd, cfqq);
1370
1371         /*
1372          * check if this request is a better next-serve candidate
1373          */
1374         prev = cfqq->next_rq;
1375         cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position);
1376
1377         /*
1378          * adjust priority tree position, if ->next_rq changes
1379          */
1380         if (prev != cfqq->next_rq)
1381                 cfq_prio_tree_add(cfqd, cfqq);
1382
1383         BUG_ON(!cfqq->next_rq);
1384 }
1385
1386 static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq)
1387 {
1388         elv_rb_del(&cfqq->sort_list, rq);
1389         cfqq->queued[rq_is_sync(rq)]--;
1390         blkiocg_update_io_remove_stats(&cfqq->cfqg->blkg, rq_data_dir(rq),
1391                                                 rq_is_sync(rq));
1392         cfq_add_rq_rb(rq);
1393         blkiocg_update_io_add_stats(
1394                         &cfqq->cfqg->blkg, &cfqq->cfqd->serving_group->blkg,
1395                         rq_data_dir(rq), rq_is_sync(rq));
1396 }
1397
1398 static struct request *
1399 cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
1400 {
1401         struct task_struct *tsk = current;
1402         struct cfq_io_context *cic;
1403         struct cfq_queue *cfqq;
1404
1405         cic = cfq_cic_lookup(cfqd, tsk->io_context);
1406         if (!cic)
1407                 return NULL;
1408
1409         cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
1410         if (cfqq) {
1411                 sector_t sector = bio->bi_sector + bio_sectors(bio);
1412
1413                 return elv_rb_find(&cfqq->sort_list, sector);
1414         }
1415
1416         return NULL;
1417 }
1418
1419 static void cfq_activate_request(struct request_queue *q, struct request *rq)
1420 {
1421         struct cfq_data *cfqd = q->elevator->elevator_data;
1422
1423         cfqd->rq_in_driver++;
1424         cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
1425                                                 cfqd->rq_in_driver);
1426
1427         cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
1428 }
1429
1430 static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
1431 {
1432         struct cfq_data *cfqd = q->elevator->elevator_data;
1433
1434         WARN_ON(!cfqd->rq_in_driver);
1435         cfqd->rq_in_driver--;
1436         cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
1437                                                 cfqd->rq_in_driver);
1438 }
1439
1440 static void cfq_remove_request(struct request *rq)
1441 {
1442         struct cfq_queue *cfqq = RQ_CFQQ(rq);
1443
1444         if (cfqq->next_rq == rq)
1445                 cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq);
1446
1447         list_del_init(&rq->queuelist);
1448         cfq_del_rq_rb(rq);
1449
1450         cfqq->cfqd->rq_queued--;
1451         blkiocg_update_io_remove_stats(&cfqq->cfqg->blkg, rq_data_dir(rq),
1452                                                 rq_is_sync(rq));
1453         if (rq_is_meta(rq)) {
1454                 WARN_ON(!cfqq->meta_pending);
1455                 cfqq->meta_pending--;
1456         }
1457 }
1458
1459 static int cfq_merge(struct request_queue *q, struct request **req,
1460                      struct bio *bio)
1461 {
1462         struct cfq_data *cfqd = q->elevator->elevator_data;
1463         struct request *__rq;
1464
1465         __rq = cfq_find_rq_fmerge(cfqd, bio);
1466         if (__rq && elv_rq_merge_ok(__rq, bio)) {
1467                 *req = __rq;
1468                 return ELEVATOR_FRONT_MERGE;
1469         }
1470
1471         return ELEVATOR_NO_MERGE;
1472 }
1473
1474 static void cfq_merged_request(struct request_queue *q, struct request *req,
1475                                int type)
1476 {
1477         if (type == ELEVATOR_FRONT_MERGE) {
1478                 struct cfq_queue *cfqq = RQ_CFQQ(req);
1479
1480                 cfq_reposition_rq_rb(cfqq, req);
1481         }
1482 }
1483
1484 static void cfq_bio_merged(struct request_queue *q, struct request *req,
1485                                 struct bio *bio)
1486 {
1487         struct cfq_queue *cfqq = RQ_CFQQ(req);
1488         blkiocg_update_io_merged_stats(&cfqq->cfqg->blkg, bio_data_dir(bio),
1489                                         cfq_bio_sync(bio));
1490 }
1491
1492 static void
1493 cfq_merged_requests(struct request_queue *q, struct request *rq,
1494                     struct request *next)
1495 {
1496         struct cfq_queue *cfqq = RQ_CFQQ(rq);
1497         /*
1498          * reposition in fifo if next is older than rq
1499          */
1500         if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
1501             time_before(rq_fifo_time(next), rq_fifo_time(rq))) {
1502                 list_move(&rq->queuelist, &next->queuelist);
1503                 rq_set_fifo_time(rq, rq_fifo_time(next));
1504         }
1505
1506         if (cfqq->next_rq == next)
1507                 cfqq->next_rq = rq;
1508         cfq_remove_request(next);
1509         blkiocg_update_io_merged_stats(&cfqq->cfqg->blkg, rq_data_dir(next),
1510                                         rq_is_sync(next));
1511 }
1512
1513 static int cfq_allow_merge(struct request_queue *q, struct request *rq,
1514                            struct bio *bio)
1515 {
1516         struct cfq_data *cfqd = q->elevator->elevator_data;
1517         struct cfq_io_context *cic;
1518         struct cfq_queue *cfqq;
1519
1520         /*
1521          * Disallow merge of a sync bio into an async request.
1522          */
1523         if (cfq_bio_sync(bio) && !rq_is_sync(rq))
1524                 return false;
1525
1526         /*
1527          * Lookup the cfqq that this bio will be queued with. Allow
1528          * merge only if rq is queued there.
1529          */
1530         cic = cfq_cic_lookup(cfqd, current->io_context);
1531         if (!cic)
1532                 return false;
1533
1534         cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
1535         return cfqq == RQ_CFQQ(rq);
1536 }
1537
1538 static inline void cfq_del_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1539 {
1540         del_timer(&cfqd->idle_slice_timer);
1541         blkiocg_update_idle_time_stats(&cfqq->cfqg->blkg);
1542 }
1543
1544 static void __cfq_set_active_queue(struct cfq_data *cfqd,
1545                                    struct cfq_queue *cfqq)
1546 {
1547         if (cfqq) {
1548                 cfq_log_cfqq(cfqd, cfqq, "set_active wl_prio:%d wl_type:%d",
1549                                 cfqd->serving_prio, cfqd->serving_type);
1550                 blkiocg_update_avg_queue_size_stats(&cfqq->cfqg->blkg);
1551                 cfqq->slice_start = 0;
1552                 cfqq->dispatch_start = jiffies;
1553                 cfqq->allocated_slice = 0;
1554                 cfqq->slice_end = 0;
1555                 cfqq->slice_dispatch = 0;
1556
1557                 cfq_clear_cfqq_wait_request(cfqq);
1558                 cfq_clear_cfqq_must_dispatch(cfqq);
1559                 cfq_clear_cfqq_must_alloc_slice(cfqq);
1560                 cfq_clear_cfqq_fifo_expire(cfqq);
1561                 cfq_mark_cfqq_slice_new(cfqq);
1562
1563                 cfq_del_timer(cfqd, cfqq);
1564         }
1565
1566         cfqd->active_queue = cfqq;
1567 }
1568
1569 /*
1570  * current cfqq expired its slice (or was too idle), select new one
1571  */
1572 static void
1573 __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1574                     bool timed_out, bool forced)
1575 {
1576         cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out);
1577
1578         if (cfq_cfqq_wait_request(cfqq))
1579                 cfq_del_timer(cfqd, cfqq);
1580
1581         cfq_clear_cfqq_wait_request(cfqq);
1582         cfq_clear_cfqq_wait_busy(cfqq);
1583
1584         /*
1585          * If this cfqq is shared between multiple processes, check to
1586          * make sure that those processes are still issuing I/Os within
1587          * the mean seek distance.  If not, it may be time to break the
1588          * queues apart again.
1589          */
1590         if (cfq_cfqq_coop(cfqq) && CFQQ_SEEKY(cfqq))
1591                 cfq_mark_cfqq_split_coop(cfqq);
1592
1593         /*
1594          * store what was left of this slice, if the queue idled/timed out
1595          */
1596         if (timed_out && !cfq_cfqq_slice_new(cfqq)) {
1597                 cfqq->slice_resid = cfqq->slice_end - jiffies;
1598                 cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
1599         }
1600
1601         cfq_group_served(cfqd, cfqq->cfqg, cfqq, forced);
1602
1603         if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
1604                 cfq_del_cfqq_rr(cfqd, cfqq);
1605
1606         cfq_resort_rr_list(cfqd, cfqq);
1607
1608         if (cfqq == cfqd->active_queue)
1609                 cfqd->active_queue = NULL;
1610
1611         if (&cfqq->cfqg->rb_node == cfqd->grp_service_tree.active)
1612                 cfqd->grp_service_tree.active = NULL;
1613
1614         if (cfqd->active_cic) {
1615                 put_io_context(cfqd->active_cic->ioc);
1616                 cfqd->active_cic = NULL;
1617         }
1618 }
1619
1620 static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out,
1621                                         bool forced)
1622 {
1623         struct cfq_queue *cfqq = cfqd->active_queue;
1624
1625         if (cfqq)
1626                 __cfq_slice_expired(cfqd, cfqq, timed_out, forced);
1627 }
1628
1629 /*
1630  * Get next queue for service. Unless we have a queue preemption,
1631  * we'll simply select the first cfqq in the service tree.
1632  */
1633 static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
1634 {
1635         struct cfq_rb_root *service_tree =
1636                 service_tree_for(cfqd->serving_group, cfqd->serving_prio,
1637                                         cfqd->serving_type);
1638
1639         if (!cfqd->rq_queued)
1640                 return NULL;
1641
1642         /* There is nothing to dispatch */
1643         if (!service_tree)
1644                 return NULL;
1645         if (RB_EMPTY_ROOT(&service_tree->rb))
1646                 return NULL;
1647         return cfq_rb_first(service_tree);
1648 }
1649
1650 static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd)
1651 {
1652         struct cfq_group *cfqg;
1653         struct cfq_queue *cfqq;
1654         int i, j;
1655         struct cfq_rb_root *st;
1656
1657         if (!cfqd->rq_queued)
1658                 return NULL;
1659
1660         cfqg = cfq_get_next_cfqg(cfqd);
1661         if (!cfqg)
1662                 return NULL;
1663
1664         for_each_cfqg_st(cfqg, i, j, st)
1665                 if ((cfqq = cfq_rb_first(st)) != NULL)
1666                         return cfqq;
1667         return NULL;
1668 }
1669
1670 /*
1671  * Get and set a new active queue for service.
1672  */
1673 static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
1674                                               struct cfq_queue *cfqq)
1675 {
1676         if (!cfqq)
1677                 cfqq = cfq_get_next_queue(cfqd);
1678
1679         __cfq_set_active_queue(cfqd, cfqq);
1680         return cfqq;
1681 }
1682
1683 static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
1684                                           struct request *rq)
1685 {
1686         if (blk_rq_pos(rq) >= cfqd->last_position)
1687                 return blk_rq_pos(rq) - cfqd->last_position;
1688         else
1689                 return cfqd->last_position - blk_rq_pos(rq);
1690 }
1691
1692 static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1693                                struct request *rq)
1694 {
1695         return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR;
1696 }
1697
1698 static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
1699                                     struct cfq_queue *cur_cfqq)
1700 {
1701         struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
1702         struct rb_node *parent, *node;
1703         struct cfq_queue *__cfqq;
1704         sector_t sector = cfqd->last_position;
1705
1706         if (RB_EMPTY_ROOT(root))
1707                 return NULL;
1708
1709         /*
1710          * First, if we find a request starting at the end of the last
1711          * request, choose it.
1712          */
1713         __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
1714         if (__cfqq)
1715                 return __cfqq;
1716
1717         /*
1718          * If the exact sector wasn't found, the parent of the NULL leaf
1719          * will contain the closest sector.
1720          */
1721         __cfqq = rb_entry(parent, struct cfq_queue, p_node);
1722         if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
1723                 return __cfqq;
1724
1725         if (blk_rq_pos(__cfqq->next_rq) < sector)
1726                 node = rb_next(&__cfqq->p_node);
1727         else
1728                 node = rb_prev(&__cfqq->p_node);
1729         if (!node)
1730                 return NULL;
1731
1732         __cfqq = rb_entry(node, struct cfq_queue, p_node);
1733         if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
1734                 return __cfqq;
1735
1736         return NULL;
1737 }
1738
1739 /*
1740  * cfqd - obvious
1741  * cur_cfqq - passed in so that we don't decide that the current queue is
1742  *            closely cooperating with itself.
1743  *
1744  * So, basically we're assuming that that cur_cfqq has dispatched at least
1745  * one request, and that cfqd->last_position reflects a position on the disk
1746  * associated with the I/O issued by cur_cfqq.  I'm not sure this is a valid
1747  * assumption.
1748  */
1749 static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
1750                                               struct cfq_queue *cur_cfqq)
1751 {
1752         struct cfq_queue *cfqq;
1753
1754         if (cfq_class_idle(cur_cfqq))
1755                 return NULL;
1756         if (!cfq_cfqq_sync(cur_cfqq))
1757                 return NULL;
1758         if (CFQQ_SEEKY(cur_cfqq))
1759                 return NULL;
1760
1761         /*
1762          * Don't search priority tree if it's the only queue in the group.
1763          */
1764         if (cur_cfqq->cfqg->nr_cfqq == 1)
1765                 return NULL;
1766
1767         /*
1768          * We should notice if some of the queues are cooperating, eg
1769          * working closely on the same area of the disk. In that case,
1770          * we can group them together and don't waste time idling.
1771          */
1772         cfqq = cfqq_close(cfqd, cur_cfqq);
1773         if (!cfqq)
1774                 return NULL;
1775
1776         /* If new queue belongs to different cfq_group, don't choose it */
1777         if (cur_cfqq->cfqg != cfqq->cfqg)
1778                 return NULL;
1779
1780         /*
1781          * It only makes sense to merge sync queues.
1782          */
1783         if (!cfq_cfqq_sync(cfqq))
1784                 return NULL;
1785         if (CFQQ_SEEKY(cfqq))
1786                 return NULL;
1787
1788         /*
1789          * Do not merge queues of different priority classes
1790          */
1791         if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq))
1792                 return NULL;
1793
1794         return cfqq;
1795 }
1796
1797 /*
1798  * Determine whether we should enforce idle window for this queue.
1799  */
1800
1801 static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1802 {
1803         enum wl_prio_t prio = cfqq_prio(cfqq);
1804         struct cfq_rb_root *service_tree = cfqq->service_tree;
1805
1806         BUG_ON(!service_tree);
1807         BUG_ON(!service_tree->count);
1808
1809         /* We never do for idle class queues. */
1810         if (prio == IDLE_WORKLOAD)
1811                 return false;
1812
1813         /* We do for queues that were marked with idle window flag. */
1814         if (cfq_cfqq_idle_window(cfqq) &&
1815            !(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag))
1816                 return true;
1817
1818         /*
1819          * Otherwise, we do only if they are the last ones
1820          * in their service tree.
1821          */
1822         if (service_tree->count == 1 && cfq_cfqq_sync(cfqq))
1823                 return 1;
1824         cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d",
1825                         service_tree->count);
1826         return 0;
1827 }
1828
1829 static void cfq_arm_slice_timer(struct cfq_data *cfqd)
1830 {
1831         struct cfq_queue *cfqq = cfqd->active_queue;
1832         struct cfq_io_context *cic;
1833         unsigned long sl;
1834
1835         /*
1836          * SSD device without seek penalty, disable idling. But only do so
1837          * for devices that support queuing, otherwise we still have a problem
1838          * with sync vs async workloads.
1839          */
1840         if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)
1841                 return;
1842
1843         WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
1844         WARN_ON(cfq_cfqq_slice_new(cfqq));
1845
1846         /*
1847          * idle is disabled, either manually or by past process history
1848          */
1849         if (!cfqd->cfq_slice_idle || !cfq_should_idle(cfqd, cfqq))
1850                 return;
1851
1852         /*
1853          * still active requests from this queue, don't idle
1854          */
1855         if (cfqq->dispatched)
1856                 return;
1857
1858         /*
1859          * task has exited, don't wait
1860          */
1861         cic = cfqd->active_cic;
1862         if (!cic || !atomic_read(&cic->ioc->nr_tasks))
1863                 return;
1864
1865         /*
1866          * If our average think time is larger than the remaining time
1867          * slice, then don't idle. This avoids overrunning the allotted
1868          * time slice.
1869          */
1870         if (sample_valid(cic->ttime_samples) &&
1871             (cfqq->slice_end - jiffies < cic->ttime_mean)) {
1872                 cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%d",
1873                                 cic->ttime_mean);
1874                 return;
1875         }
1876
1877         cfq_mark_cfqq_wait_request(cfqq);
1878
1879         sl = cfqd->cfq_slice_idle;
1880
1881         mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
1882         blkiocg_update_set_idle_time_stats(&cfqq->cfqg->blkg);
1883         cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu", sl);
1884 }
1885
1886 /*
1887  * Move request from internal lists to the request queue dispatch list.
1888  */
1889 static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
1890 {
1891         struct cfq_data *cfqd = q->elevator->elevator_data;
1892         struct cfq_queue *cfqq = RQ_CFQQ(rq);
1893
1894         cfq_log_cfqq(cfqd, cfqq, "dispatch_insert");
1895
1896         cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq);
1897         cfq_remove_request(rq);
1898         cfqq->dispatched++;
1899         elv_dispatch_sort(q, rq);
1900
1901         cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++;
1902         blkiocg_update_dispatch_stats(&cfqq->cfqg->blkg, blk_rq_bytes(rq),
1903                                         rq_data_dir(rq), rq_is_sync(rq));
1904 }
1905
1906 /*
1907  * return expired entry, or NULL to just start from scratch in rbtree
1908  */
1909 static struct request *cfq_check_fifo(struct cfq_queue *cfqq)
1910 {
1911         struct request *rq = NULL;
1912
1913         if (cfq_cfqq_fifo_expire(cfqq))
1914                 return NULL;
1915
1916         cfq_mark_cfqq_fifo_expire(cfqq);
1917
1918         if (list_empty(&cfqq->fifo))
1919                 return NULL;
1920
1921         rq = rq_entry_fifo(cfqq->fifo.next);
1922         if (time_before(jiffies, rq_fifo_time(rq)))
1923                 rq = NULL;
1924
1925         cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq);
1926         return rq;
1927 }
1928
1929 static inline int
1930 cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1931 {
1932         const int base_rq = cfqd->cfq_slice_async_rq;
1933
1934         WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
1935
1936         return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio));
1937 }
1938
1939 /*
1940  * Must be called with the queue_lock held.
1941  */
1942 static int cfqq_process_refs(struct cfq_queue *cfqq)
1943 {
1944         int process_refs, io_refs;
1945
1946         io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE];
1947         process_refs = atomic_read(&cfqq->ref) - io_refs;
1948         BUG_ON(process_refs < 0);
1949         return process_refs;
1950 }
1951
1952 static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq)
1953 {
1954         int process_refs, new_process_refs;
1955         struct cfq_queue *__cfqq;
1956
1957         /* Avoid a circular list and skip interim queue merges */
1958         while ((__cfqq = new_cfqq->new_cfqq)) {
1959                 if (__cfqq == cfqq)
1960                         return;
1961                 new_cfqq = __cfqq;
1962         }
1963
1964         process_refs = cfqq_process_refs(cfqq);
1965         /*
1966          * If the process for the cfqq has gone away, there is no
1967          * sense in merging the queues.
1968          */
1969         if (process_refs == 0)
1970                 return;
1971
1972         /*
1973          * Merge in the direction of the lesser amount of work.
1974          */
1975         new_process_refs = cfqq_process_refs(new_cfqq);
1976         if (new_process_refs >= process_refs) {
1977                 cfqq->new_cfqq = new_cfqq;
1978                 atomic_add(process_refs, &new_cfqq->ref);
1979         } else {
1980                 new_cfqq->new_cfqq = cfqq;
1981                 atomic_add(new_process_refs, &cfqq->ref);
1982         }
1983 }
1984
1985 static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd,
1986                                 struct cfq_group *cfqg, enum wl_prio_t prio)
1987 {
1988         struct cfq_queue *queue;
1989         int i;
1990         bool key_valid = false;
1991         unsigned long lowest_key = 0;
1992         enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD;
1993
1994         for (i = 0; i <= SYNC_WORKLOAD; ++i) {
1995                 /* select the one with lowest rb_key */
1996                 queue = cfq_rb_first(service_tree_for(cfqg, prio, i));
1997                 if (queue &&
1998                     (!key_valid || time_before(queue->rb_key, lowest_key))) {
1999                         lowest_key = queue->rb_key;
2000                         cur_best = i;
2001                         key_valid = true;
2002                 }
2003         }
2004
2005         return cur_best;
2006 }
2007
2008 static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg)
2009 {
2010         unsigned slice;
2011         unsigned count;
2012         struct cfq_rb_root *st;
2013         unsigned group_slice;
2014
2015         if (!cfqg) {
2016                 cfqd->serving_prio = IDLE_WORKLOAD;
2017                 cfqd->workload_expires = jiffies + 1;
2018                 return;
2019         }
2020
2021         /* Choose next priority. RT > BE > IDLE */
2022         if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg))
2023                 cfqd->serving_prio = RT_WORKLOAD;
2024         else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg))
2025                 cfqd->serving_prio = BE_WORKLOAD;
2026         else {
2027                 cfqd->serving_prio = IDLE_WORKLOAD;
2028                 cfqd->workload_expires = jiffies + 1;
2029                 return;
2030         }
2031
2032         /*
2033          * For RT and BE, we have to choose also the type
2034          * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
2035          * expiration time
2036          */
2037         st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type);
2038         count = st->count;
2039
2040         /*
2041          * check workload expiration, and that we still have other queues ready
2042          */
2043         if (count && !time_after(jiffies, cfqd->workload_expires))
2044                 return;
2045
2046         /* otherwise select new workload type */
2047         cfqd->serving_type =
2048                 cfq_choose_wl(cfqd, cfqg, cfqd->serving_prio);
2049         st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type);
2050         count = st->count;
2051
2052         /*
2053          * the workload slice is computed as a fraction of target latency
2054          * proportional to the number of queues in that workload, over
2055          * all the queues in the same priority class
2056          */
2057         group_slice = cfq_group_slice(cfqd, cfqg);
2058
2059         slice = group_slice * count /
2060                 max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_prio],
2061                       cfq_group_busy_queues_wl(cfqd->serving_prio, cfqd, cfqg));
2062
2063         if (cfqd->serving_type == ASYNC_WORKLOAD) {
2064                 unsigned int tmp;
2065
2066                 /*
2067                  * Async queues are currently system wide. Just taking
2068                  * proportion of queues with-in same group will lead to higher
2069                  * async ratio system wide as generally root group is going
2070                  * to have higher weight. A more accurate thing would be to
2071                  * calculate system wide asnc/sync ratio.
2072                  */
2073                 tmp = cfq_target_latency * cfqg_busy_async_queues(cfqd, cfqg);
2074                 tmp = tmp/cfqd->busy_queues;
2075                 slice = min_t(unsigned, slice, tmp);
2076
2077                 /* async workload slice is scaled down according to
2078                  * the sync/async slice ratio. */
2079                 slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1];
2080         } else
2081                 /* sync workload slice is at least 2 * cfq_slice_idle */
2082                 slice = max(slice, 2 * cfqd->cfq_slice_idle);
2083
2084         slice = max_t(unsigned, slice, CFQ_MIN_TT);
2085         cfq_log(cfqd, "workload slice:%d", slice);
2086         cfqd->workload_expires = jiffies + slice;
2087         cfqd->noidle_tree_requires_idle = false;
2088 }
2089
2090 static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd)
2091 {
2092         struct cfq_rb_root *st = &cfqd->grp_service_tree;
2093         struct cfq_group *cfqg;
2094
2095         if (RB_EMPTY_ROOT(&st->rb))
2096                 return NULL;
2097         cfqg = cfq_rb_first_group(st);
2098         st->active = &cfqg->rb_node;
2099         update_min_vdisktime(st);
2100         return cfqg;
2101 }
2102
2103 static void cfq_choose_cfqg(struct cfq_data *cfqd)
2104 {
2105         struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd);
2106
2107         cfqd->serving_group = cfqg;
2108
2109         /* Restore the workload type data */
2110         if (cfqg->saved_workload_slice) {
2111                 cfqd->workload_expires = jiffies + cfqg->saved_workload_slice;
2112                 cfqd->serving_type = cfqg->saved_workload;
2113                 cfqd->serving_prio = cfqg->saved_serving_prio;
2114         } else
2115                 cfqd->workload_expires = jiffies - 1;
2116
2117         choose_service_tree(cfqd, cfqg);
2118 }
2119
2120 /*
2121  * Select a queue for service. If we have a current active queue,
2122  * check whether to continue servicing it, or retrieve and set a new one.
2123  */
2124 static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
2125 {
2126         struct cfq_queue *cfqq, *new_cfqq = NULL;
2127
2128         cfqq = cfqd->active_queue;
2129         if (!cfqq)
2130                 goto new_queue;
2131
2132         if (!cfqd->rq_queued)
2133                 return NULL;
2134
2135         /*
2136          * We were waiting for group to get backlogged. Expire the queue
2137          */
2138         if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list))
2139                 goto expire;
2140
2141         /*
2142          * The active queue has run out of time, expire it and select new.
2143          */
2144         if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) {
2145                 /*
2146                  * If slice had not expired at the completion of last request
2147                  * we might not have turned on wait_busy flag. Don't expire
2148                  * the queue yet. Allow the group to get backlogged.
2149                  *
2150                  * The very fact that we have used the slice, that means we
2151                  * have been idling all along on this queue and it should be
2152                  * ok to wait for this request to complete.
2153                  */
2154                 if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list)
2155                     && cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
2156                         cfqq = NULL;
2157                         goto keep_queue;
2158                 } else
2159                         goto expire;
2160         }
2161
2162         /*
2163          * The active queue has requests and isn't expired, allow it to
2164          * dispatch.
2165          */
2166         if (!RB_EMPTY_ROOT(&cfqq->sort_list))
2167                 goto keep_queue;
2168
2169         /*
2170          * If another queue has a request waiting within our mean seek
2171          * distance, let it run.  The expire code will check for close
2172          * cooperators and put the close queue at the front of the service
2173          * tree.  If possible, merge the expiring queue with the new cfqq.
2174          */
2175         new_cfqq = cfq_close_cooperator(cfqd, cfqq);
2176         if (new_cfqq) {
2177                 if (!cfqq->new_cfqq)
2178                         cfq_setup_merge(cfqq, new_cfqq);
2179                 goto expire;
2180         }
2181
2182         /*
2183          * No requests pending. If the active queue still has requests in
2184          * flight or is idling for a new request, allow either of these
2185          * conditions to happen (or time out) before selecting a new queue.
2186          */
2187         if (timer_pending(&cfqd->idle_slice_timer) ||
2188             (cfqq->dispatched && cfq_should_idle(cfqd, cfqq))) {
2189                 cfqq = NULL;
2190                 goto keep_queue;
2191         }
2192
2193 expire:
2194         cfq_slice_expired(cfqd, 0, false);
2195 new_queue:
2196         /*
2197          * Current queue expired. Check if we have to switch to a new
2198          * service tree
2199          */
2200         if (!new_cfqq)
2201                 cfq_choose_cfqg(cfqd);
2202
2203         cfqq = cfq_set_active_queue(cfqd, new_cfqq);
2204 keep_queue:
2205         return cfqq;
2206 }
2207
2208 static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq)
2209 {
2210         int dispatched = 0;
2211
2212         while (cfqq->next_rq) {
2213                 cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq);
2214                 dispatched++;
2215         }
2216
2217         BUG_ON(!list_empty(&cfqq->fifo));
2218
2219         /* By default cfqq is not expired if it is empty. Do it explicitly */
2220         __cfq_slice_expired(cfqq->cfqd, cfqq, 0, true);
2221         return dispatched;
2222 }
2223
2224 /*
2225  * Drain our current requests. Used for barriers and when switching
2226  * io schedulers on-the-fly.
2227  */
2228 static int cfq_forced_dispatch(struct cfq_data *cfqd)
2229 {
2230         struct cfq_queue *cfqq;
2231         int dispatched = 0;
2232
2233         /* Expire the timeslice of the current active queue first */
2234         cfq_slice_expired(cfqd, 0, true);
2235         while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) {
2236                 __cfq_set_active_queue(cfqd, cfqq);
2237                 dispatched += __cfq_forced_dispatch_cfqq(cfqq);
2238         }
2239
2240         BUG_ON(cfqd->busy_queues);
2241
2242         cfq_log(cfqd, "forced_dispatch=%d", dispatched);
2243         return dispatched;
2244 }
2245
2246 static inline bool cfq_slice_used_soon(struct cfq_data *cfqd,
2247         struct cfq_queue *cfqq)
2248 {
2249         /* the queue hasn't finished any request, can't estimate */
2250         if (cfq_cfqq_slice_new(cfqq))
2251                 return 1;
2252         if (time_after(jiffies + cfqd->cfq_slice_idle * cfqq->dispatched,
2253                 cfqq->slice_end))
2254                 return 1;
2255
2256         return 0;
2257 }
2258
2259 static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2260 {
2261         unsigned int max_dispatch;
2262
2263         /*
2264          * Drain async requests before we start sync IO
2265          */
2266         if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC])
2267                 return false;
2268
2269         /*
2270          * If this is an async queue and we have sync IO in flight, let it wait
2271          */
2272         if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq))
2273                 return false;
2274
2275         max_dispatch = max_t(unsigned int, cfqd->cfq_quantum / 2, 1);
2276         if (cfq_class_idle(cfqq))
2277                 max_dispatch = 1;
2278
2279         /*
2280          * Does this cfqq already have too much IO in flight?
2281          */
2282         if (cfqq->dispatched >= max_dispatch) {
2283                 /*
2284                  * idle queue must always only have a single IO in flight
2285                  */
2286                 if (cfq_class_idle(cfqq))
2287                         return false;
2288
2289                 /*
2290                  * We have other queues, don't allow more IO from this one
2291                  */
2292                 if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq))
2293                         return false;
2294
2295                 /*
2296                  * Sole queue user, no limit
2297                  */
2298                 if (cfqd->busy_queues == 1)
2299                         max_dispatch = -1;
2300                 else
2301                         /*
2302                          * Normally we start throttling cfqq when cfq_quantum/2
2303                          * requests have been dispatched. But we can drive
2304                          * deeper queue depths at the beginning of slice
2305                          * subjected to upper limit of cfq_quantum.
2306                          * */
2307                         max_dispatch = cfqd->cfq_quantum;
2308         }
2309
2310         /*
2311          * Async queues must wait a bit before being allowed dispatch.
2312          * We also ramp up the dispatch depth gradually for async IO,
2313          * based on the last sync IO we serviced
2314          */
2315         if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) {
2316                 unsigned long last_sync = jiffies - cfqd->last_delayed_sync;
2317                 unsigned int depth;
2318
2319                 depth = last_sync / cfqd->cfq_slice[1];
2320                 if (!depth && !cfqq->dispatched)
2321                         depth = 1;
2322                 if (depth < max_dispatch)
2323                         max_dispatch = depth;
2324         }
2325
2326         /*
2327          * If we're below the current max, allow a dispatch
2328          */
2329         return cfqq->dispatched < max_dispatch;
2330 }
2331
2332 /*
2333  * Dispatch a request from cfqq, moving them to the request queue
2334  * dispatch list.
2335  */
2336 static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2337 {
2338         struct request *rq;
2339
2340         BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list));
2341
2342         if (!cfq_may_dispatch(cfqd, cfqq))
2343                 return false;
2344
2345         /*
2346          * follow expired path, else get first next available
2347          */
2348         rq = cfq_check_fifo(cfqq);
2349         if (!rq)
2350                 rq = cfqq->next_rq;
2351
2352         /*
2353          * insert request into driver dispatch list
2354          */
2355         cfq_dispatch_insert(cfqd->queue, rq);
2356
2357         if (!cfqd->active_cic) {
2358                 struct cfq_io_context *cic = RQ_CIC(rq);
2359
2360                 atomic_long_inc(&cic->ioc->refcount);
2361                 cfqd->active_cic = cic;
2362         }
2363
2364         return true;
2365 }
2366
2367 /*
2368  * Find the cfqq that we need to service and move a request from that to the
2369  * dispatch list
2370  */
2371 static int cfq_dispatch_requests(struct request_queue *q, int force)
2372 {
2373         struct cfq_data *cfqd = q->elevator->elevator_data;
2374         struct cfq_queue *cfqq;
2375
2376         if (!cfqd->busy_queues)
2377                 return 0;
2378
2379         if (unlikely(force))
2380                 return cfq_forced_dispatch(cfqd);
2381
2382         cfqq = cfq_select_queue(cfqd);
2383         if (!cfqq)
2384                 return 0;
2385
2386         /*
2387          * Dispatch a request from this cfqq, if it is allowed
2388          */
2389         if (!cfq_dispatch_request(cfqd, cfqq))
2390                 return 0;
2391
2392         cfqq->slice_dispatch++;
2393         cfq_clear_cfqq_must_dispatch(cfqq);
2394
2395         /*
2396          * expire an async queue immediately if it has used up its slice. idle
2397          * queue always expire after 1 dispatch round.
2398          */
2399         if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
2400             cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
2401             cfq_class_idle(cfqq))) {
2402                 cfqq->slice_end = jiffies + 1;
2403                 cfq_slice_expired(cfqd, 0, false);
2404         }
2405
2406         cfq_log_cfqq(cfqd, cfqq, "dispatched a request");
2407         return 1;
2408 }
2409
2410 /*
2411  * task holds one reference to the queue, dropped when task exits. each rq
2412  * in-flight on this queue also holds a reference, dropped when rq is freed.
2413  *
2414  * Each cfq queue took a reference on the parent group. Drop it now.
2415  * queue lock must be held here.
2416  */
2417 static void cfq_put_queue(struct cfq_queue *cfqq)
2418 {
2419         struct cfq_data *cfqd = cfqq->cfqd;
2420         struct cfq_group *cfqg, *orig_cfqg;
2421
2422         BUG_ON(atomic_read(&cfqq->ref) <= 0);
2423
2424         if (!atomic_dec_and_test(&cfqq->ref))
2425                 return;
2426
2427         cfq_log_cfqq(cfqd, cfqq, "put_queue");
2428         BUG_ON(rb_first(&cfqq->sort_list));
2429         BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
2430         cfqg = cfqq->cfqg;
2431         orig_cfqg = cfqq->orig_cfqg;
2432
2433         if (unlikely(cfqd->active_queue == cfqq)) {
2434                 __cfq_slice_expired(cfqd, cfqq, 0, false);
2435                 cfq_schedule_dispatch(cfqd);
2436         }
2437
2438         BUG_ON(cfq_cfqq_on_rr(cfqq));
2439         kmem_cache_free(cfq_pool, cfqq);
2440         cfq_put_cfqg(cfqg);
2441         if (orig_cfqg)
2442                 cfq_put_cfqg(orig_cfqg);
2443 }
2444
2445 /*
2446  * Must always be called with the rcu_read_lock() held
2447  */
2448 static void
2449 __call_for_each_cic(struct io_context *ioc,
2450                     void (*func)(struct io_context *, struct cfq_io_context *))
2451 {
2452         struct cfq_io_context *cic;
2453         struct hlist_node *n;
2454
2455         hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list)
2456                 func(ioc, cic);
2457 }
2458
2459 /*
2460  * Call func for each cic attached to this ioc.
2461  */
2462 static void
2463 call_for_each_cic(struct io_context *ioc,
2464                   void (*func)(struct io_context *, struct cfq_io_context *))
2465 {
2466         rcu_read_lock();
2467         __call_for_each_cic(ioc, func);
2468         rcu_read_unlock();
2469 }
2470
2471 static void cfq_cic_free_rcu(struct rcu_head *head)
2472 {
2473         struct cfq_io_context *cic;
2474
2475         cic = container_of(head, struct cfq_io_context, rcu_head);
2476
2477         kmem_cache_free(cfq_ioc_pool, cic);
2478         elv_ioc_count_dec(cfq_ioc_count);
2479
2480         if (ioc_gone) {
2481                 /*
2482                  * CFQ scheduler is exiting, grab exit lock and check
2483                  * the pending io context count. If it hits zero,
2484                  * complete ioc_gone and set it back to NULL
2485                  */
2486                 spin_lock(&ioc_gone_lock);
2487                 if (ioc_gone && !elv_ioc_count_read(cfq_ioc_count)) {
2488                         complete(ioc_gone);
2489                         ioc_gone = NULL;
2490                 }
2491                 spin_unlock(&ioc_gone_lock);
2492         }
2493 }
2494
2495 static void cfq_cic_free(struct cfq_io_context *cic)
2496 {
2497         call_rcu(&cic->rcu_head, cfq_cic_free_rcu);
2498 }
2499
2500 static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic)
2501 {
2502         unsigned long flags;
2503
2504         BUG_ON(!cic->dead_key);
2505
2506         spin_lock_irqsave(&ioc->lock, flags);
2507         radix_tree_delete(&ioc->radix_root, cic->dead_key);
2508         hlist_del_rcu(&cic->cic_list);
2509         spin_unlock_irqrestore(&ioc->lock, flags);
2510
2511         cfq_cic_free(cic);
2512 }
2513
2514 /*
2515  * Must be called with rcu_read_lock() held or preemption otherwise disabled.
2516  * Only two callers of this - ->dtor() which is called with the rcu_read_lock(),
2517  * and ->trim() which is called with the task lock held
2518  */
2519 static void cfq_free_io_context(struct io_context *ioc)
2520 {
2521         /*
2522          * ioc->refcount is zero here, or we are called from elv_unregister(),
2523          * so no more cic's are allowed to be linked into this ioc.  So it
2524          * should be ok to iterate over the known list, we will see all cic's
2525          * since no new ones are added.
2526          */
2527         __call_for_each_cic(ioc, cic_free_func);
2528 }
2529
2530 static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2531 {
2532         struct cfq_queue *__cfqq, *next;
2533
2534         if (unlikely(cfqq == cfqd->active_queue)) {
2535                 __cfq_slice_expired(cfqd, cfqq, 0, false);
2536                 cfq_schedule_dispatch(cfqd);
2537         }
2538
2539         /*
2540          * If this queue was scheduled to merge with another queue, be
2541          * sure to drop the reference taken on that queue (and others in
2542          * the merge chain).  See cfq_setup_merge and cfq_merge_cfqqs.
2543          */
2544         __cfqq = cfqq->new_cfqq;
2545         while (__cfqq) {
2546                 if (__cfqq == cfqq) {
2547                         WARN(1, "cfqq->new_cfqq loop detected\n");
2548                         break;
2549                 }
2550                 next = __cfqq->new_cfqq;
2551                 cfq_put_queue(__cfqq);
2552                 __cfqq = next;
2553         }
2554
2555         cfq_put_queue(cfqq);
2556 }
2557
2558 static void __cfq_exit_single_io_context(struct cfq_data *cfqd,
2559                                          struct cfq_io_context *cic)
2560 {
2561         struct io_context *ioc = cic->ioc;
2562
2563         list_del_init(&cic->queue_list);
2564
2565         /*
2566          * Make sure key == NULL is seen for dead queues
2567          */
2568         smp_wmb();
2569         cic->dead_key = (unsigned long) cic->key;
2570         cic->key = NULL;
2571
2572         if (ioc->ioc_data == cic)
2573                 rcu_assign_pointer(ioc->ioc_data, NULL);
2574
2575         if (cic->cfqq[BLK_RW_ASYNC]) {
2576                 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]);
2577                 cic->cfqq[BLK_RW_ASYNC] = NULL;
2578         }
2579
2580         if (cic->cfqq[BLK_RW_SYNC]) {
2581                 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]);
2582                 cic->cfqq[BLK_RW_SYNC] = NULL;
2583         }
2584 }
2585
2586 static void cfq_exit_single_io_context(struct io_context *ioc,
2587                                        struct cfq_io_context *cic)
2588 {
2589         struct cfq_data *cfqd = cic->key;
2590
2591         if (cfqd) {
2592                 struct request_queue *q = cfqd->queue;
2593                 unsigned long flags;
2594
2595                 spin_lock_irqsave(q->queue_lock, flags);
2596
2597                 /*
2598                  * Ensure we get a fresh copy of the ->key to prevent
2599                  * race between exiting task and queue
2600                  */
2601                 smp_read_barrier_depends();
2602                 if (cic->key)
2603                         __cfq_exit_single_io_context(cfqd, cic);
2604
2605                 spin_unlock_irqrestore(q->queue_lock, flags);
2606         }
2607 }
2608
2609 /*
2610  * The process that ioc belongs to has exited, we need to clean up
2611  * and put the internal structures we have that belongs to that process.
2612  */
2613 static void cfq_exit_io_context(struct io_context *ioc)
2614 {
2615         call_for_each_cic(ioc, cfq_exit_single_io_context);
2616 }
2617
2618 static struct cfq_io_context *
2619 cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
2620 {
2621         struct cfq_io_context *cic;
2622
2623         cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask | __GFP_ZERO,
2624                                                         cfqd->queue->node);
2625         if (cic) {
2626                 cic->last_end_request = jiffies;
2627                 INIT_LIST_HEAD(&cic->queue_list);
2628                 INIT_HLIST_NODE(&cic->cic_list);
2629                 cic->dtor = cfq_free_io_context;
2630                 cic->exit = cfq_exit_io_context;
2631                 elv_ioc_count_inc(cfq_ioc_count);
2632         }
2633
2634         return cic;
2635 }
2636
2637 static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc)
2638 {
2639         struct task_struct *tsk = current;
2640         int ioprio_class;
2641
2642         if (!cfq_cfqq_prio_changed(cfqq))
2643                 return;
2644
2645         ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio);
2646         switch (ioprio_class) {
2647         default:
2648                 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
2649         case IOPRIO_CLASS_NONE:
2650                 /*
2651                  * no prio set, inherit CPU scheduling settings
2652                  */
2653                 cfqq->ioprio = task_nice_ioprio(tsk);
2654                 cfqq->ioprio_class = task_nice_ioclass(tsk);
2655                 break;
2656         case IOPRIO_CLASS_RT:
2657                 cfqq->ioprio = task_ioprio(ioc);
2658                 cfqq->ioprio_class = IOPRIO_CLASS_RT;
2659                 break;
2660         case IOPRIO_CLASS_BE:
2661                 cfqq->ioprio = task_ioprio(ioc);
2662                 cfqq->ioprio_class = IOPRIO_CLASS_BE;
2663                 break;
2664         case IOPRIO_CLASS_IDLE:
2665                 cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
2666                 cfqq->ioprio = 7;
2667                 cfq_clear_cfqq_idle_window(cfqq);
2668                 break;
2669         }
2670
2671         /*
2672          * keep track of original prio settings in case we have to temporarily
2673          * elevate the priority of this queue
2674          */
2675         cfqq->org_ioprio = cfqq->ioprio;
2676         cfqq->org_ioprio_class = cfqq->ioprio_class;
2677         cfq_clear_cfqq_prio_changed(cfqq);
2678 }
2679
2680 static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic)
2681 {
2682         struct cfq_data *cfqd = cic->key;
2683         struct cfq_queue *cfqq;
2684         unsigned long flags;
2685
2686         if (unlikely(!cfqd))
2687                 return;
2688
2689         spin_lock_irqsave(cfqd->queue->queue_lock, flags);
2690
2691         cfqq = cic->cfqq[BLK_RW_ASYNC];
2692         if (cfqq) {
2693                 struct cfq_queue *new_cfqq;
2694                 new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->ioc,
2695                                                 GFP_ATOMIC);
2696                 if (new_cfqq) {
2697                         cic->cfqq[BLK_RW_ASYNC] = new_cfqq;
2698                         cfq_put_queue(cfqq);
2699                 }
2700         }
2701
2702         cfqq = cic->cfqq[BLK_RW_SYNC];
2703         if (cfqq)
2704                 cfq_mark_cfqq_prio_changed(cfqq);
2705
2706         spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
2707 }
2708
2709 static void cfq_ioc_set_ioprio(struct io_context *ioc)
2710 {
2711         call_for_each_cic(ioc, changed_ioprio);
2712         ioc->ioprio_changed = 0;
2713 }
2714
2715 static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2716                           pid_t pid, bool is_sync)
2717 {
2718         RB_CLEAR_NODE(&cfqq->rb_node);
2719         RB_CLEAR_NODE(&cfqq->p_node);
2720         INIT_LIST_HEAD(&cfqq->fifo);
2721
2722         atomic_set(&cfqq->ref, 0);
2723         cfqq->cfqd = cfqd;
2724
2725         cfq_mark_cfqq_prio_changed(cfqq);
2726
2727         if (is_sync) {
2728                 if (!cfq_class_idle(cfqq))
2729                         cfq_mark_cfqq_idle_window(cfqq);
2730                 cfq_mark_cfqq_sync(cfqq);
2731         }
2732         cfqq->pid = pid;
2733 }
2734
2735 #ifdef CONFIG_CFQ_GROUP_IOSCHED
2736 static void changed_cgroup(struct io_context *ioc, struct cfq_io_context *cic)
2737 {
2738         struct cfq_queue *sync_cfqq = cic_to_cfqq(cic, 1);
2739         struct cfq_data *cfqd = cic->key;
2740         unsigned long flags;
2741         struct request_queue *q;
2742
2743         if (unlikely(!cfqd))
2744                 return;
2745
2746         q = cfqd->queue;
2747
2748         spin_lock_irqsave(q->queue_lock, flags);
2749
2750         if (sync_cfqq) {
2751                 /*
2752                  * Drop reference to sync queue. A new sync queue will be
2753                  * assigned in new group upon arrival of a fresh request.
2754                  */
2755                 cfq_log_cfqq(cfqd, sync_cfqq, "changed cgroup");
2756                 cic_set_cfqq(cic, NULL, 1);
2757                 cfq_put_queue(sync_cfqq);
2758         }
2759
2760         spin_unlock_irqrestore(q->queue_lock, flags);
2761 }
2762
2763 static void cfq_ioc_set_cgroup(struct io_context *ioc)
2764 {
2765         call_for_each_cic(ioc, changed_cgroup);
2766         ioc->cgroup_changed = 0;
2767 }
2768 #endif  /* CONFIG_CFQ_GROUP_IOSCHED */
2769
2770 static struct cfq_queue *
2771 cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync,
2772                      struct io_context *ioc, gfp_t gfp_mask)
2773 {
2774         struct cfq_queue *cfqq, *new_cfqq = NULL;
2775         struct cfq_io_context *cic;
2776         struct cfq_group *cfqg;
2777
2778 retry:
2779         cfqg = cfq_get_cfqg(cfqd, 1);
2780         cic = cfq_cic_lookup(cfqd, ioc);
2781         /* cic always exists here */
2782         cfqq = cic_to_cfqq(cic, is_sync);
2783
2784         /*
2785          * Always try a new alloc if we fell back to the OOM cfqq
2786          * originally, since it should just be a temporary situation.
2787          */
2788         if (!cfqq || cfqq == &cfqd->oom_cfqq) {
2789                 cfqq = NULL;
2790                 if (new_cfqq) {
2791                         cfqq = new_cfqq;
2792                         new_cfqq = NULL;
2793                 } else if (gfp_mask & __GFP_WAIT) {
2794                         spin_unlock_irq(cfqd->queue->queue_lock);
2795                         new_cfqq = kmem_cache_alloc_node(cfq_pool,
2796                                         gfp_mask | __GFP_ZERO,
2797                                         cfqd->queue->node);
2798                         spin_lock_irq(cfqd->queue->queue_lock);
2799                         if (new_cfqq)
2800                                 goto retry;
2801                 } else {
2802                         cfqq = kmem_cache_alloc_node(cfq_pool,
2803                                         gfp_mask | __GFP_ZERO,
2804                                         cfqd->queue->node);
2805                 }
2806
2807                 if (cfqq) {
2808                         cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
2809                         cfq_init_prio_data(cfqq, ioc);
2810                         cfq_link_cfqq_cfqg(cfqq, cfqg);
2811                         cfq_log_cfqq(cfqd, cfqq, "alloced");
2812                 } else
2813                         cfqq = &cfqd->oom_cfqq;
2814         }
2815
2816         if (new_cfqq)
2817                 kmem_cache_free(cfq_pool, new_cfqq);
2818
2819         return cfqq;
2820 }
2821
2822 static struct cfq_queue **
2823 cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio)
2824 {
2825         switch (ioprio_class) {
2826         case IOPRIO_CLASS_RT:
2827                 return &cfqd->async_cfqq[0][ioprio];
2828         case IOPRIO_CLASS_BE:
2829                 return &cfqd->async_cfqq[1][ioprio];
2830         case IOPRIO_CLASS_IDLE:
2831                 return &cfqd->async_idle_cfqq;
2832         default:
2833                 BUG();
2834         }
2835 }
2836
2837 static struct cfq_queue *
2838 cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct io_context *ioc,
2839               gfp_t gfp_mask)
2840 {
2841         const int ioprio = task_ioprio(ioc);
2842         const int ioprio_class = task_ioprio_class(ioc);
2843         struct cfq_queue **async_cfqq = NULL;
2844         struct cfq_queue *cfqq = NULL;
2845
2846         if (!is_sync) {
2847                 async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio);
2848                 cfqq = *async_cfqq;
2849         }
2850
2851         if (!cfqq)
2852                 cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask);
2853
2854         /*
2855          * pin the queue now that it's allocated, scheduler exit will prune it
2856          */
2857         if (!is_sync && !(*async_cfqq)) {
2858                 atomic_inc(&cfqq->ref);
2859                 *async_cfqq = cfqq;
2860         }
2861
2862         atomic_inc(&cfqq->ref);
2863         return cfqq;
2864 }
2865
2866 /*
2867  * We drop cfq io contexts lazily, so we may find a dead one.
2868  */
2869 static void
2870 cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc,
2871                   struct cfq_io_context *cic)
2872 {
2873         unsigned long flags;
2874
2875         WARN_ON(!list_empty(&cic->queue_list));
2876
2877         spin_lock_irqsave(&ioc->lock, flags);
2878
2879         BUG_ON(ioc->ioc_data == cic);
2880
2881         radix_tree_delete(&ioc->radix_root, (unsigned long) cfqd);
2882         hlist_del_rcu(&cic->cic_list);
2883         spin_unlock_irqrestore(&ioc->lock, flags);
2884
2885         cfq_cic_free(cic);
2886 }
2887
2888 static struct cfq_io_context *
2889 cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc)
2890 {
2891         struct cfq_io_context *cic;
2892         unsigned long flags;
2893         void *k;
2894
2895         if (unlikely(!ioc))
2896                 return NULL;
2897
2898         rcu_read_lock();
2899
2900         /*
2901          * we maintain a last-hit cache, to avoid browsing over the tree
2902          */
2903         cic = rcu_dereference(ioc->ioc_data);
2904         if (cic && cic->key == cfqd) {
2905                 rcu_read_unlock();
2906                 return cic;
2907         }
2908
2909         do {
2910                 cic = radix_tree_lookup(&ioc->radix_root, (unsigned long) cfqd);
2911                 rcu_read_unlock();
2912                 if (!cic)
2913                         break;
2914                 /* ->key must be copied to avoid race with cfq_exit_queue() */
2915                 k = cic->key;
2916                 if (unlikely(!k)) {
2917                         cfq_drop_dead_cic(cfqd, ioc, cic);
2918                         rcu_read_lock();
2919                         continue;
2920                 }
2921
2922                 spin_lock_irqsave(&ioc->lock, flags);
2923                 rcu_assign_pointer(ioc->ioc_data, cic);
2924                 spin_unlock_irqrestore(&ioc->lock, flags);
2925                 break;
2926         } while (1);
2927
2928         return cic;
2929 }
2930
2931 /*
2932  * Add cic into ioc, using cfqd as the search key. This enables us to lookup
2933  * the process specific cfq io context when entered from the block layer.
2934  * Also adds the cic to a per-cfqd list, used when this queue is removed.
2935  */
2936 static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc,
2937                         struct cfq_io_context *cic, gfp_t gfp_mask)
2938 {
2939         unsigned long flags;
2940         int ret;
2941
2942         ret = radix_tree_preload(gfp_mask);
2943         if (!ret) {
2944                 cic->ioc = ioc;
2945                 cic->key = cfqd;
2946
2947                 spin_lock_irqsave(&ioc->lock, flags);
2948                 ret = radix_tree_insert(&ioc->radix_root,
2949                                                 (unsigned long) cfqd, cic);
2950                 if (!ret)
2951                         hlist_add_head_rcu(&cic->cic_list, &ioc->cic_list);
2952                 spin_unlock_irqrestore(&ioc->lock, flags);
2953
2954                 radix_tree_preload_end();
2955
2956                 if (!ret) {
2957                         spin_lock_irqsave(cfqd->queue->queue_lock, flags);
2958                         list_add(&cic->queue_list, &cfqd->cic_list);
2959                         spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
2960                 }
2961         }
2962
2963         if (ret)
2964                 printk(KERN_ERR "cfq: cic link failed!\n");
2965
2966         return ret;
2967 }
2968
2969 /*
2970  * Setup general io context and cfq io context. There can be several cfq
2971  * io contexts per general io context, if this process is doing io to more
2972  * than one device managed by cfq.
2973  */
2974 static struct cfq_io_context *
2975 cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
2976 {
2977         struct io_context *ioc = NULL;
2978         struct cfq_io_context *cic;
2979
2980         might_sleep_if(gfp_mask & __GFP_WAIT);
2981
2982         ioc = get_io_context(gfp_mask, cfqd->queue->node);
2983         if (!ioc)
2984                 return NULL;
2985
2986         cic = cfq_cic_lookup(cfqd, ioc);
2987         if (cic)
2988                 goto out;
2989
2990         cic = cfq_alloc_io_context(cfqd, gfp_mask);
2991         if (cic == NULL)
2992                 goto err;
2993
2994         if (cfq_cic_link(cfqd, ioc, cic, gfp_mask))
2995                 goto err_free;
2996
2997 out:
2998         smp_read_barrier_depends();
2999         if (unlikely(ioc->ioprio_changed))
3000                 cfq_ioc_set_ioprio(ioc);
3001
3002 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3003         if (unlikely(ioc->cgroup_changed))
3004                 cfq_ioc_set_cgroup(ioc);
3005 #endif
3006         return cic;
3007 err_free:
3008         cfq_cic_free(cic);
3009 err:
3010         put_io_context(ioc);
3011         return NULL;
3012 }
3013
3014 static void
3015 cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic)
3016 {
3017         unsigned long elapsed = jiffies - cic->last_end_request;
3018         unsigned long ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle);
3019
3020         cic->ttime_samples = (7*cic->ttime_samples + 256) / 8;
3021         cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8;
3022         cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples;
3023 }
3024
3025 static void
3026 cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3027                        struct request *rq)
3028 {
3029         sector_t sdist = 0;
3030         sector_t n_sec = blk_rq_sectors(rq);
3031         if (cfqq->last_request_pos) {
3032                 if (cfqq->last_request_pos < blk_rq_pos(rq))
3033                         sdist = blk_rq_pos(rq) - cfqq->last_request_pos;
3034                 else
3035                         sdist = cfqq->last_request_pos - blk_rq_pos(rq);
3036         }
3037
3038         cfqq->seek_history <<= 1;
3039         if (blk_queue_nonrot(cfqd->queue))
3040                 cfqq->seek_history |= (n_sec < CFQQ_SECT_THR_NONROT);
3041         else
3042                 cfqq->seek_history |= (sdist > CFQQ_SEEK_THR);
3043 }
3044
3045 /*
3046  * Disable idle window if the process thinks too long or seeks so much that
3047  * it doesn't matter
3048  */
3049 static void
3050 cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3051                        struct cfq_io_context *cic)
3052 {
3053         int old_idle, enable_idle;
3054
3055         /*
3056          * Don't idle for async or idle io prio class
3057          */
3058         if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq))
3059                 return;
3060
3061         enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
3062
3063         if (cfqq->queued[0] + cfqq->queued[1] >= 4)
3064                 cfq_mark_cfqq_deep(cfqq);
3065
3066         if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle ||
3067             (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq)))
3068                 enable_idle = 0;
3069         else if (sample_valid(cic->ttime_samples)) {
3070                 if (cic->ttime_mean > cfqd->cfq_slice_idle)
3071                         enable_idle = 0;
3072                 else
3073                         enable_idle = 1;
3074         }
3075
3076         if (old_idle != enable_idle) {
3077                 cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle);
3078                 if (enable_idle)
3079                         cfq_mark_cfqq_idle_window(cfqq);
3080                 else
3081                         cfq_clear_cfqq_idle_window(cfqq);
3082         }
3083 }
3084
3085 /*
3086  * Check if new_cfqq should preempt the currently active queue. Return 0 for
3087  * no or if we aren't sure, a 1 will cause a preempt.
3088  */
3089 static bool
3090 cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
3091                    struct request *rq)
3092 {
3093         struct cfq_queue *cfqq;
3094
3095         cfqq = cfqd->active_queue;
3096         if (!cfqq)
3097                 return false;
3098
3099         if (cfq_class_idle(new_cfqq))
3100                 return false;
3101
3102         if (cfq_class_idle(cfqq))
3103                 return true;
3104
3105         /*
3106          * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice.
3107          */
3108         if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq))
3109                 return false;
3110
3111         /*
3112          * if the new request is sync, but the currently running queue is
3113          * not, let the sync request have priority.
3114          */
3115         if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq))
3116                 return true;
3117
3118         if (new_cfqq->cfqg != cfqq->cfqg)
3119                 return false;
3120
3121         if (cfq_slice_used(cfqq))
3122                 return true;
3123
3124         /* Allow preemption only if we are idling on sync-noidle tree */
3125         if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD &&
3126             cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD &&
3127             new_cfqq->service_tree->count == 2 &&
3128             RB_EMPTY_ROOT(&cfqq->sort_list))
3129                 return true;
3130
3131         /*
3132          * So both queues are sync. Let the new request get disk time if
3133          * it's a metadata request and the current queue is doing regular IO.
3134          */
3135         if (rq_is_meta(rq) && !cfqq->meta_pending)
3136                 return true;
3137
3138         /*
3139          * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
3140          */
3141         if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
3142                 return true;
3143
3144         if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq))
3145                 return false;
3146
3147         /*
3148          * if this request is as-good as one we would expect from the
3149          * current cfqq, let it preempt
3150          */
3151         if (cfq_rq_close(cfqd, cfqq, rq))
3152                 return true;
3153
3154         return false;
3155 }
3156
3157 /*
3158  * cfqq preempts the active queue. if we allowed preempt with no slice left,
3159  * let it have half of its nominal slice.
3160  */
3161 static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3162 {
3163         cfq_log_cfqq(cfqd, cfqq, "preempt");
3164         cfq_slice_expired(cfqd, 1, false);
3165
3166         /*
3167          * Put the new queue at the front of the of the current list,
3168          * so we know that it will be selected next.
3169          */
3170         BUG_ON(!cfq_cfqq_on_rr(cfqq));
3171
3172         cfq_service_tree_add(cfqd, cfqq, 1);
3173
3174         cfqq->slice_end = 0;
3175         cfq_mark_cfqq_slice_new(cfqq);
3176 }
3177
3178 /*
3179  * Called when a new fs request (rq) is added (to cfqq). Check if there's
3180  * something we should do about it
3181  */
3182 static void
3183 cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3184                 struct request *rq)
3185 {
3186         struct cfq_io_context *cic = RQ_CIC(rq);
3187
3188         cfqd->rq_queued++;
3189         if (rq_is_meta(rq))
3190                 cfqq->meta_pending++;
3191
3192         cfq_update_io_thinktime(cfqd, cic);
3193         cfq_update_io_seektime(cfqd, cfqq, rq);
3194         cfq_update_idle_window(cfqd, cfqq, cic);
3195
3196         cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
3197
3198         if (cfqq == cfqd->active_queue) {
3199                 /*
3200                  * Remember that we saw a request from this process, but
3201                  * don't start queuing just yet. Otherwise we risk seeing lots
3202                  * of tiny requests, because we disrupt the normal plugging
3203                  * and merging. If the request is already larger than a single
3204                  * page, let it rip immediately. For that case we assume that
3205                  * merging is already done. Ditto for a busy system that
3206                  * has other work pending, don't risk delaying until the
3207                  * idle timer unplug to continue working.
3208                  */
3209                 if (cfq_cfqq_wait_request(cfqq)) {
3210                         if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE ||
3211                             cfqd->busy_queues > 1) {
3212                                 cfq_del_timer(cfqd, cfqq);
3213                                 cfq_clear_cfqq_wait_request(cfqq);
3214                                 __blk_run_queue(cfqd->queue);
3215                         } else {
3216                                 blkiocg_update_idle_time_stats(
3217                                                 &cfqq->cfqg->blkg);
3218                                 cfq_mark_cfqq_must_dispatch(cfqq);
3219                         }
3220                 }
3221         } else if (cfq_should_preempt(cfqd, cfqq, rq)) {
3222                 /*
3223                  * not the active queue - expire current slice if it is
3224                  * idle and has expired it's mean thinktime or this new queue
3225                  * has some old slice time left and is of higher priority or
3226                  * this new queue is RT and the current one is BE
3227                  */
3228                 cfq_preempt_queue(cfqd, cfqq);
3229                 __blk_run_queue(cfqd->queue);
3230         }
3231 }
3232
3233 static void cfq_insert_request(struct request_queue *q, struct request *rq)
3234 {
3235         struct cfq_data *cfqd = q->elevator->elevator_data;
3236         struct cfq_queue *cfqq = RQ_CFQQ(rq);
3237
3238         cfq_log_cfqq(cfqd, cfqq, "insert_request");
3239         cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc);
3240
3241         rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]);
3242         list_add_tail(&rq->queuelist, &cfqq->fifo);
3243         cfq_add_rq_rb(rq);
3244
3245         blkiocg_update_io_add_stats(&cfqq->cfqg->blkg,
3246                         &cfqd->serving_group->blkg, rq_data_dir(rq),
3247                         rq_is_sync(rq));
3248         cfq_rq_enqueued(cfqd, cfqq, rq);
3249 }
3250
3251 /*
3252  * Update hw_tag based on peak queue depth over 50 samples under
3253  * sufficient load.
3254  */
3255 static void cfq_update_hw_tag(struct cfq_data *cfqd)
3256 {
3257         struct cfq_queue *cfqq = cfqd->active_queue;
3258
3259         if (cfqd->rq_in_driver > cfqd->hw_tag_est_depth)
3260                 cfqd->hw_tag_est_depth = cfqd->rq_in_driver;
3261
3262         if (cfqd->hw_tag == 1)
3263                 return;
3264
3265         if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
3266             cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN)
3267                 return;
3268
3269         /*
3270          * If active queue hasn't enough requests and can idle, cfq might not
3271          * dispatch sufficient requests to hardware. Don't zero hw_tag in this
3272          * case
3273          */
3274         if (cfqq && cfq_cfqq_idle_window(cfqq) &&
3275             cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] <
3276             CFQ_HW_QUEUE_MIN && cfqd->rq_in_driver < CFQ_HW_QUEUE_MIN)
3277                 return;
3278
3279         if (cfqd->hw_tag_samples++ < 50)
3280                 return;
3281
3282         if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN)
3283                 cfqd->hw_tag = 1;
3284         else
3285                 cfqd->hw_tag = 0;
3286 }
3287
3288 static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3289 {
3290         struct cfq_io_context *cic = cfqd->active_cic;
3291
3292         /* If there are other queues in the group, don't wait */
3293         if (cfqq->cfqg->nr_cfqq > 1)
3294                 return false;
3295
3296         if (cfq_slice_used(cfqq))
3297                 return true;
3298
3299         /* if slice left is less than think time, wait busy */
3300         if (cic && sample_valid(cic->ttime_samples)
3301             && (cfqq->slice_end - jiffies < cic->ttime_mean))
3302                 return true;
3303
3304         /*
3305          * If think times is less than a jiffy than ttime_mean=0 and above
3306          * will not be true. It might happen that slice has not expired yet
3307          * but will expire soon (4-5 ns) during select_queue(). To cover the
3308          * case where think time is less than a jiffy, mark the queue wait
3309          * busy if only 1 jiffy is left in the slice.
3310          */
3311         if (cfqq->slice_end - jiffies == 1)
3312                 return true;
3313
3314         return false;
3315 }
3316
3317 static void cfq_completed_request(struct request_queue *q, struct request *rq)
3318 {
3319         struct cfq_queue *cfqq = RQ_CFQQ(rq);
3320         struct cfq_data *cfqd = cfqq->cfqd;
3321         const int sync = rq_is_sync(rq);
3322         unsigned long now;
3323
3324         now = jiffies;
3325         cfq_log_cfqq(cfqd, cfqq, "complete rqnoidle %d", !!rq_noidle(rq));
3326
3327         cfq_update_hw_tag(cfqd);
3328
3329         WARN_ON(!cfqd->rq_in_driver);
3330         WARN_ON(!cfqq->dispatched);
3331         cfqd->rq_in_driver--;
3332         cfqq->dispatched--;
3333         blkiocg_update_completion_stats(&cfqq->cfqg->blkg, rq_start_time_ns(rq),
3334                         rq_io_start_time_ns(rq), rq_data_dir(rq),
3335                         rq_is_sync(rq));
3336
3337         cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--;
3338
3339         if (sync) {
3340                 RQ_CIC(rq)->last_end_request = now;
3341                 if (!time_after(rq->start_time + cfqd->cfq_fifo_expire[1], now))
3342                         cfqd->last_delayed_sync = now;
3343         }
3344
3345         /*
3346          * If this is the active queue, check if it needs to be expired,
3347          * or if we want to idle in case it has no pending requests.
3348          */
3349         if (cfqd->active_queue == cfqq) {
3350                 const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list);
3351
3352                 if (cfq_cfqq_slice_new(cfqq)) {
3353                         cfq_set_prio_slice(cfqd, cfqq);
3354                         cfq_clear_cfqq_slice_new(cfqq);
3355                 }
3356
3357                 /*
3358                  * Should we wait for next request to come in before we expire
3359                  * the queue.
3360                  */
3361                 if (cfq_should_wait_busy(cfqd, cfqq)) {
3362                         cfqq->slice_end = jiffies + cfqd->cfq_slice_idle;
3363                         cfq_mark_cfqq_wait_busy(cfqq);
3364                         cfq_log_cfqq(cfqd, cfqq, "will busy wait");
3365                 }
3366
3367                 /*
3368                  * Idling is not enabled on:
3369                  * - expired queues
3370                  * - idle-priority queues
3371                  * - async queues
3372                  * - queues with still some requests queued
3373                  * - when there is a close cooperator
3374                  */
3375                 if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq))
3376                         cfq_slice_expired(cfqd, 1, false);
3377                 else if (sync && cfqq_empty &&
3378                          !cfq_close_cooperator(cfqd, cfqq)) {
3379                         cfqd->noidle_tree_requires_idle |= !rq_noidle(rq);
3380                         /*
3381                          * Idling is enabled for SYNC_WORKLOAD.
3382                          * SYNC_NOIDLE_WORKLOAD idles at the end of the tree
3383                          * only if we processed at least one !rq_noidle request
3384                          */
3385                         if (cfqd->serving_type == SYNC_WORKLOAD
3386                             || cfqd->noidle_tree_requires_idle
3387                             || cfqq->cfqg->nr_cfqq == 1)
3388                                 cfq_arm_slice_timer(cfqd);
3389                 }
3390         }
3391
3392         if (!cfqd->rq_in_driver)
3393                 cfq_schedule_dispatch(cfqd);
3394 }
3395
3396 /*
3397  * we temporarily boost lower priority queues if they are holding fs exclusive
3398  * resources. they are boosted to normal prio (CLASS_BE/4)
3399  */
3400 static void cfq_prio_boost(struct cfq_queue *cfqq)
3401 {
3402         if (has_fs_excl()) {
3403                 /*
3404                  * boost idle prio on transactions that would lock out other
3405                  * users of the filesystem
3406                  */
3407                 if (cfq_class_idle(cfqq))
3408                         cfqq->ioprio_class = IOPRIO_CLASS_BE;
3409                 if (cfqq->ioprio > IOPRIO_NORM)
3410                         cfqq->ioprio = IOPRIO_NORM;
3411         } else {
3412                 /*
3413                  * unboost the queue (if needed)
3414                  */
3415                 cfqq->ioprio_class = cfqq->org_ioprio_class;
3416                 cfqq->ioprio = cfqq->org_ioprio;
3417         }
3418 }
3419
3420 static inline int __cfq_may_queue(struct cfq_queue *cfqq)
3421 {
3422         if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) {
3423                 cfq_mark_cfqq_must_alloc_slice(cfqq);
3424                 return ELV_MQUEUE_MUST;
3425         }
3426
3427         return ELV_MQUEUE_MAY;
3428 }
3429
3430 static int cfq_may_queue(struct request_queue *q, int rw)
3431 {
3432         struct cfq_data *cfqd = q->elevator->elevator_data;
3433         struct task_struct *tsk = current;
3434         struct cfq_io_context *cic;
3435         struct cfq_queue *cfqq;
3436
3437         /*
3438          * don't force setup of a queue from here, as a call to may_queue
3439          * does not necessarily imply that a request actually will be queued.
3440          * so just lookup a possibly existing queue, or return 'may queue'
3441          * if that fails
3442          */
3443         cic = cfq_cic_lookup(cfqd, tsk->io_context);
3444         if (!cic)
3445                 return ELV_MQUEUE_MAY;
3446
3447         cfqq = cic_to_cfqq(cic, rw_is_sync(rw));
3448         if (cfqq) {
3449                 cfq_init_prio_data(cfqq, cic->ioc);
3450                 cfq_prio_boost(cfqq);
3451
3452                 return __cfq_may_queue(cfqq);
3453         }
3454
3455         return ELV_MQUEUE_MAY;
3456 }
3457
3458 /*
3459  * queue lock held here
3460  */
3461 static void cfq_put_request(struct request *rq)
3462 {
3463         struct cfq_queue *cfqq = RQ_CFQQ(rq);
3464
3465         if (cfqq) {
3466                 const int rw = rq_data_dir(rq);
3467
3468                 BUG_ON(!cfqq->allocated[rw]);
3469                 cfqq->allocated[rw]--;
3470
3471                 put_io_context(RQ_CIC(rq)->ioc);
3472
3473                 rq->elevator_private = NULL;
3474                 rq->elevator_private2 = NULL;
3475
3476                 cfq_put_queue(cfqq);
3477         }
3478 }
3479
3480 static struct cfq_queue *
3481 cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_context *cic,
3482                 struct cfq_queue *cfqq)
3483 {
3484         cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq);
3485         cic_set_cfqq(cic, cfqq->new_cfqq, 1);
3486         cfq_mark_cfqq_coop(cfqq->new_cfqq);
3487         cfq_put_queue(cfqq);
3488         return cic_to_cfqq(cic, 1);
3489 }
3490
3491 /*
3492  * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
3493  * was the last process referring to said cfqq.
3494  */
3495 static struct cfq_queue *
3496 split_cfqq(struct cfq_io_context *cic, struct cfq_queue *cfqq)
3497 {
3498         if (cfqq_process_refs(cfqq) == 1) {
3499                 cfqq->pid = current->pid;
3500                 cfq_clear_cfqq_coop(cfqq);
3501                 cfq_clear_cfqq_split_coop(cfqq);
3502                 return cfqq;
3503         }
3504
3505         cic_set_cfqq(cic, NULL, 1);
3506         cfq_put_queue(cfqq);
3507         return NULL;
3508 }
3509 /*
3510  * Allocate cfq data structures associated with this request.
3511  */
3512 static int
3513 cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask)
3514 {
3515         struct cfq_data *cfqd = q->elevator->elevator_data;
3516         struct cfq_io_context *cic;
3517         const int rw = rq_data_dir(rq);
3518         const bool is_sync = rq_is_sync(rq);
3519         struct cfq_queue *cfqq;
3520         unsigned long flags;
3521
3522         might_sleep_if(gfp_mask & __GFP_WAIT);
3523
3524         cic = cfq_get_io_context(cfqd, gfp_mask);
3525
3526         spin_lock_irqsave(q->queue_lock, flags);
3527
3528         if (!cic)
3529                 goto queue_fail;
3530
3531 new_queue:
3532         cfqq = cic_to_cfqq(cic, is_sync);
3533         if (!cfqq || cfqq == &cfqd->oom_cfqq) {
3534                 cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask);
3535                 cic_set_cfqq(cic, cfqq, is_sync);
3536         } else {
3537                 /*
3538                  * If the queue was seeky for too long, break it apart.
3539                  */
3540                 if (cfq_cfqq_coop(cfqq) && cfq_cfqq_split_coop(cfqq)) {
3541                         cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq");
3542                         cfqq = split_cfqq(cic, cfqq);
3543                         if (!cfqq)
3544                                 goto new_queue;
3545                 }
3546
3547                 /*
3548                  * Check to see if this queue is scheduled to merge with
3549                  * another, closely cooperating queue.  The merging of
3550                  * queues happens here as it must be done in process context.
3551                  * The reference on new_cfqq was taken in merge_cfqqs.
3552                  */
3553                 if (cfqq->new_cfqq)
3554                         cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq);
3555         }
3556
3557         cfqq->allocated[rw]++;
3558         atomic_inc(&cfqq->ref);
3559
3560         spin_unlock_irqrestore(q->queue_lock, flags);
3561
3562         rq->elevator_private = cic;
3563         rq->elevator_private2 = cfqq;
3564         return 0;
3565
3566 queue_fail:
3567         if (cic)
3568                 put_io_context(cic->ioc);
3569
3570         cfq_schedule_dispatch(cfqd);
3571         spin_unlock_irqrestore(q->queue_lock, flags);
3572         cfq_log(cfqd, "set_request fail");
3573         return 1;
3574 }
3575
3576 static void cfq_kick_queue(struct work_struct *work)
3577 {
3578         struct cfq_data *cfqd =
3579                 container_of(work, struct cfq_data, unplug_work);
3580         struct request_queue *q = cfqd->queue;
3581
3582         spin_lock_irq(q->queue_lock);
3583         __blk_run_queue(cfqd->queue);
3584         spin_unlock_irq(q->queue_lock);
3585 }
3586
3587 /*
3588  * Timer running if the active_queue is currently idling inside its time slice
3589  */
3590 static void cfq_idle_slice_timer(unsigned long data)
3591 {
3592         struct cfq_data *cfqd = (struct cfq_data *) data;
3593         struct cfq_queue *cfqq;
3594         unsigned long flags;
3595         int timed_out = 1;
3596
3597         cfq_log(cfqd, "idle timer fired");
3598
3599         spin_lock_irqsave(cfqd->queue->queue_lock, flags);
3600
3601         cfqq = cfqd->active_queue;
3602         if (cfqq) {
3603                 timed_out = 0;
3604
3605                 /*
3606                  * We saw a request before the queue expired, let it through
3607                  */
3608                 if (cfq_cfqq_must_dispatch(cfqq))
3609                         goto out_kick;
3610
3611                 /*
3612                  * expired
3613                  */
3614                 if (cfq_slice_used(cfqq))
3615                         goto expire;
3616
3617                 /*
3618                  * only expire and reinvoke request handler, if there are
3619                  * other queues with pending requests
3620                  */
3621                 if (!cfqd->busy_queues)
3622                         goto out_cont;
3623
3624                 /*
3625                  * not expired and it has a request pending, let it dispatch
3626                  */
3627                 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
3628                         goto out_kick;
3629
3630                 /*
3631                  * Queue depth flag is reset only when the idle didn't succeed
3632                  */
3633                 cfq_clear_cfqq_deep(cfqq);
3634         }
3635 expire:
3636         cfq_slice_expired(cfqd, timed_out, false);
3637 out_kick:
3638         cfq_schedule_dispatch(cfqd);
3639 out_cont:
3640         spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
3641 }
3642
3643 static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
3644 {
3645         del_timer_sync(&cfqd->idle_slice_timer);
3646         cancel_work_sync(&cfqd->unplug_work);
3647 }
3648
3649 static void cfq_put_async_queues(struct cfq_data *cfqd)
3650 {
3651         int i;
3652
3653         for (i = 0; i < IOPRIO_BE_NR; i++) {
3654                 if (cfqd->async_cfqq[0][i])
3655                         cfq_put_queue(cfqd->async_cfqq[0][i]);
3656                 if (cfqd->async_cfqq[1][i])
3657                         cfq_put_queue(cfqd->async_cfqq[1][i]);
3658         }
3659
3660         if (cfqd->async_idle_cfqq)
3661                 cfq_put_queue(cfqd->async_idle_cfqq);
3662 }
3663
3664 static void cfq_cfqd_free(struct rcu_head *head)
3665 {
3666         kfree(container_of(head, struct cfq_data, rcu));
3667 }
3668
3669 static void cfq_exit_queue(struct elevator_queue *e)
3670 {
3671         struct cfq_data *cfqd = e->elevator_data;
3672         struct request_queue *q = cfqd->queue;
3673
3674         cfq_shutdown_timer_wq(cfqd);
3675
3676         spin_lock_irq(q->queue_lock);
3677
3678         if (cfqd->active_queue)
3679                 __cfq_slice_expired(cfqd, cfqd->active_queue, 0, false);
3680
3681         while (!list_empty(&cfqd->cic_list)) {
3682                 struct cfq_io_context *cic = list_entry(cfqd->cic_list.next,
3683                                                         struct cfq_io_context,
3684                                                         queue_list);
3685
3686                 __cfq_exit_single_io_context(cfqd, cic);
3687         }
3688
3689         cfq_put_async_queues(cfqd);
3690         cfq_release_cfq_groups(cfqd);
3691         blkiocg_del_blkio_group(&cfqd->root_group.blkg);
3692
3693         spin_unlock_irq(q->queue_lock);
3694
3695         cfq_shutdown_timer_wq(cfqd);
3696
3697         /* Wait for cfqg->blkg->key accessors to exit their grace periods. */
3698         call_rcu(&cfqd->rcu, cfq_cfqd_free);
3699 }
3700
3701 static void *cfq_init_queue(struct request_queue *q)
3702 {
3703         struct cfq_data *cfqd;
3704         int i, j;
3705         struct cfq_group *cfqg;
3706         struct cfq_rb_root *st;
3707
3708         cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node);
3709         if (!cfqd)
3710                 return NULL;
3711
3712         /* Init root service tree */
3713         cfqd->grp_service_tree = CFQ_RB_ROOT;
3714
3715         /* Init root group */
3716         cfqg = &cfqd->root_group;
3717         for_each_cfqg_st(cfqg, i, j, st)
3718                 *st = CFQ_RB_ROOT;
3719         RB_CLEAR_NODE(&cfqg->rb_node);
3720
3721         /* Give preference to root group over other groups */
3722         cfqg->weight = 2*BLKIO_WEIGHT_DEFAULT;
3723
3724 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3725         /*
3726          * Take a reference to root group which we never drop. This is just
3727          * to make sure that cfq_put_cfqg() does not try to kfree root group
3728          */
3729         atomic_set(&cfqg->ref, 1);
3730         blkiocg_add_blkio_group(&blkio_root_cgroup, &cfqg->blkg, (void *)cfqd,
3731                                         0);
3732 #endif
3733         /*
3734          * Not strictly needed (since RB_ROOT just clears the node and we
3735          * zeroed cfqd on alloc), but better be safe in case someone decides
3736          * to add magic to the rb code
3737          */
3738         for (i = 0; i < CFQ_PRIO_LISTS; i++)
3739                 cfqd->prio_trees[i] = RB_ROOT;
3740
3741         /*
3742          * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
3743          * Grab a permanent reference to it, so that the normal code flow
3744          * will not attempt to free it.
3745          */
3746         cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0);
3747         atomic_inc(&cfqd->oom_cfqq.ref);
3748         cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, &cfqd->root_group);
3749
3750         INIT_LIST_HEAD(&cfqd->cic_list);
3751
3752         cfqd->queue = q;
3753
3754         init_timer(&cfqd->idle_slice_timer);
3755         cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
3756         cfqd->idle_slice_timer.data = (unsigned long) cfqd;
3757
3758         INIT_WORK(&cfqd->unplug_work, cfq_kick_queue);
3759
3760         cfqd->cfq_quantum = cfq_quantum;
3761         cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
3762         cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
3763         cfqd->cfq_back_max = cfq_back_max;
3764         cfqd->cfq_back_penalty = cfq_back_penalty;
3765         cfqd->cfq_slice[0] = cfq_slice_async;
3766         cfqd->cfq_slice[1] = cfq_slice_sync;
3767         cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
3768         cfqd->cfq_slice_idle = cfq_slice_idle;
3769         cfqd->cfq_latency = 1;
3770         cfqd->cfq_group_isolation = 0;
3771         cfqd->hw_tag = -1;
3772         /*
3773          * we optimistically start assuming sync ops weren't delayed in last
3774          * second, in order to have larger depth for async operations.
3775          */
3776         cfqd->last_delayed_sync = jiffies - HZ;
3777         INIT_RCU_HEAD(&cfqd->rcu);
3778         return cfqd;
3779 }
3780
3781 static void cfq_slab_kill(void)
3782 {
3783         /*
3784          * Caller already ensured that pending RCU callbacks are completed,
3785          * so we should have no busy allocations at this point.
3786          */
3787         if (cfq_pool)
3788                 kmem_cache_destroy(cfq_pool);
3789         if (cfq_ioc_pool)
3790                 kmem_cache_destroy(cfq_ioc_pool);
3791 }
3792
3793 static int __init cfq_slab_setup(void)
3794 {
3795         cfq_pool = KMEM_CACHE(cfq_queue, 0);
3796         if (!cfq_pool)
3797                 goto fail;
3798
3799         cfq_ioc_pool = KMEM_CACHE(cfq_io_context, 0);
3800         if (!cfq_ioc_pool)
3801                 goto fail;
3802
3803         return 0;
3804 fail:
3805         cfq_slab_kill();
3806         return -ENOMEM;
3807 }
3808
3809 /*
3810  * sysfs parts below -->
3811  */
3812 static ssize_t
3813 cfq_var_show(unsigned int var, char *page)
3814 {
3815         return sprintf(page, "%d\n", var);
3816 }
3817
3818 static ssize_t
3819 cfq_var_store(unsigned int *var, const char *page, size_t count)
3820 {
3821         char *p = (char *) page;
3822
3823         *var = simple_strtoul(p, &p, 10);
3824         return count;
3825 }
3826
3827 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV)                            \
3828 static ssize_t __FUNC(struct elevator_queue *e, char *page)             \
3829 {                                                                       \
3830         struct cfq_data *cfqd = e->elevator_data;                       \
3831         unsigned int __data = __VAR;                                    \
3832         if (__CONV)                                                     \
3833                 __data = jiffies_to_msecs(__data);                      \
3834         return cfq_var_show(__data, (page));                            \
3835 }
3836 SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
3837 SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
3838 SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
3839 SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0);
3840 SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0);
3841 SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
3842 SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
3843 SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
3844 SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
3845 SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0);
3846 SHOW_FUNCTION(cfq_group_isolation_show, cfqd->cfq_group_isolation, 0);
3847 #undef SHOW_FUNCTION
3848
3849 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV)                 \
3850 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
3851 {                                                                       \
3852         struct cfq_data *cfqd = e->elevator_data;                       \
3853         unsigned int __data;                                            \
3854         int ret = cfq_var_store(&__data, (page), count);                \
3855         if (__data < (MIN))                                             \
3856                 __data = (MIN);                                         \
3857         else if (__data > (MAX))                                        \
3858                 __data = (MAX);                                         \
3859         if (__CONV)                                                     \
3860                 *(__PTR) = msecs_to_jiffies(__data);                    \
3861         else                                                            \
3862                 *(__PTR) = __data;                                      \
3863         return ret;                                                     \
3864 }
3865 STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
3866 STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1,
3867                 UINT_MAX, 1);
3868 STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1,
3869                 UINT_MAX, 1);
3870 STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
3871 STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1,
3872                 UINT_MAX, 0);
3873 STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
3874 STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
3875 STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
3876 STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
3877                 UINT_MAX, 0);
3878 STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0);
3879 STORE_FUNCTION(cfq_group_isolation_store, &cfqd->cfq_group_isolation, 0, 1, 0);
3880 #undef STORE_FUNCTION
3881
3882 #define CFQ_ATTR(name) \
3883         __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
3884
3885 static struct elv_fs_entry cfq_attrs[] = {
3886         CFQ_ATTR(quantum),
3887         CFQ_ATTR(fifo_expire_sync),
3888         CFQ_ATTR(fifo_expire_async),
3889         CFQ_ATTR(back_seek_max),
3890         CFQ_ATTR(back_seek_penalty),
3891         CFQ_ATTR(slice_sync),
3892         CFQ_ATTR(slice_async),
3893         CFQ_ATTR(slice_async_rq),
3894         CFQ_ATTR(slice_idle),
3895         CFQ_ATTR(low_latency),
3896         CFQ_ATTR(group_isolation),
3897         __ATTR_NULL
3898 };
3899
3900 static struct elevator_type iosched_cfq = {
3901         .ops = {
3902                 .elevator_merge_fn =            cfq_merge,
3903                 .elevator_merged_fn =           cfq_merged_request,
3904                 .elevator_merge_req_fn =        cfq_merged_requests,
3905                 .elevator_allow_merge_fn =      cfq_allow_merge,
3906                 .elevator_bio_merged_fn =       cfq_bio_merged,
3907                 .elevator_dispatch_fn =         cfq_dispatch_requests,
3908                 .elevator_add_req_fn =          cfq_insert_request,
3909                 .elevator_activate_req_fn =     cfq_activate_request,
3910                 .elevator_deactivate_req_fn =   cfq_deactivate_request,
3911                 .elevator_queue_empty_fn =      cfq_queue_empty,
3912                 .elevator_completed_req_fn =    cfq_completed_request,
3913                 .elevator_former_req_fn =       elv_rb_former_request,
3914                 .elevator_latter_req_fn =       elv_rb_latter_request,
3915                 .elevator_set_req_fn =          cfq_set_request,
3916                 .elevator_put_req_fn =          cfq_put_request,
3917                 .elevator_may_queue_fn =        cfq_may_queue,
3918                 .elevator_init_fn =             cfq_init_queue,
3919                 .elevator_exit_fn =             cfq_exit_queue,
3920                 .trim =                         cfq_free_io_context,
3921         },
3922         .elevator_attrs =       cfq_attrs,
3923         .elevator_name =        "cfq",
3924         .elevator_owner =       THIS_MODULE,
3925 };
3926
3927 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3928 static struct blkio_policy_type blkio_policy_cfq = {
3929         .ops = {
3930                 .blkio_unlink_group_fn =        cfq_unlink_blkio_group,
3931                 .blkio_update_group_weight_fn = cfq_update_blkio_group_weight,
3932         },
3933 };
3934 #else
3935 static struct blkio_policy_type blkio_policy_cfq;
3936 #endif
3937
3938 static int __init cfq_init(void)
3939 {
3940         /*
3941          * could be 0 on HZ < 1000 setups
3942          */
3943         if (!cfq_slice_async)
3944                 cfq_slice_async = 1;
3945         if (!cfq_slice_idle)
3946                 cfq_slice_idle = 1;
3947
3948         if (cfq_slab_setup())
3949                 return -ENOMEM;
3950
3951         elv_register(&iosched_cfq);
3952         blkio_policy_register(&blkio_policy_cfq);
3953
3954         return 0;
3955 }
3956
3957 static void __exit cfq_exit(void)
3958 {
3959         DECLARE_COMPLETION_ONSTACK(all_gone);
3960         blkio_policy_unregister(&blkio_policy_cfq);
3961         elv_unregister(&iosched_cfq);
3962         ioc_gone = &all_gone;
3963         /* ioc_gone's update must be visible before reading ioc_count */
3964         smp_wmb();
3965
3966         /*
3967          * this also protects us from entering cfq_slab_kill() with
3968          * pending RCU callbacks
3969          */
3970         if (elv_ioc_count_read(cfq_ioc_count))
3971                 wait_for_completion(&all_gone);
3972         cfq_slab_kill();
3973 }
3974
3975 module_init(cfq_init);
3976 module_exit(cfq_exit);
3977
3978 MODULE_AUTHOR("Jens Axboe");
3979 MODULE_LICENSE("GPL");
3980 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");