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1 /*
2 * CFQ, or complete fairness queueing, disk scheduler.
3 *
4 * Based on ideas from a previously unfinished io
5 * scheduler (round robin per-process disk scheduling) and Andrea Arcangeli.
6 *
7 * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
8 */
9 #include <linux/module.h>
10 #include <linux/slab.h>
11 #include <linux/blkdev.h>
12 #include <linux/elevator.h>
13 #include <linux/jiffies.h>
14 #include <linux/rbtree.h>
15 #include <linux/ioprio.h>
16 #include <linux/blktrace_api.h>
17 #include "blk-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 #define RQ_CFQG(rq) (struct cfq_group *) ((rq)->elevator_private3)
59
60 static struct kmem_cache *cfq_pool;
61 static struct kmem_cache *cfq_ioc_pool;
62
63 static DEFINE_PER_CPU(unsigned long, cfq_ioc_count);
64 static struct completion *ioc_gone;
65 static DEFINE_SPINLOCK(ioc_gone_lock);
66
67 #define CFQ_PRIO_LISTS IOPRIO_BE_NR
68 #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
69 #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
70
71 #define sample_valid(samples) ((samples) > 80)
72 #define rb_entry_cfqg(node) rb_entry((node), struct cfq_group, rb_node)
73
74 /*
75 * Most of our rbtree usage is for sorting with min extraction, so
76 * if we cache the leftmost node we don't have to walk down the tree
77 * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should
78 * move this into the elevator for the rq sorting as well.
79 */
80 struct cfq_rb_root {
81 struct rb_root rb;
82 struct rb_node *left;
83 unsigned count;
84 unsigned total_weight;
85 u64 min_vdisktime;
86 struct rb_node *active;
87 };
88 #define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT, .left = NULL, \
89 .count = 0, .min_vdisktime = 0, }
90
91 /*
92 * Per process-grouping structure
93 */
94 struct cfq_queue {
95 /* reference count */
96 atomic_t ref;
97 /* various state flags, see below */
98 unsigned int flags;
99 /* parent cfq_data */
100 struct cfq_data *cfqd;
101 /* service_tree member */
102 struct rb_node rb_node;
103 /* service_tree key */
104 unsigned long rb_key;
105 /* prio tree member */
106 struct rb_node p_node;
107 /* prio tree root we belong to, if any */
108 struct rb_root *p_root;
109 /* sorted list of pending requests */
110 struct rb_root sort_list;
111 /* if fifo isn't expired, next request to serve */
112 struct request *next_rq;
113 /* requests queued in sort_list */
114 int queued[2];
115 /* currently allocated requests */
116 int allocated[2];
117 /* fifo list of requests in sort_list */
118 struct list_head fifo;
119
120 /* time when queue got scheduled in to dispatch first request. */
121 unsigned long dispatch_start;
122 unsigned int allocated_slice;
123 unsigned int slice_dispatch;
124 /* time when first request from queue completed and slice started. */
125 unsigned long slice_start;
126 unsigned long slice_end;
127 long slice_resid;
128
129 /* pending metadata requests */
130 int meta_pending;
131 /* number of requests that are on the dispatch list or inside driver */
132 int dispatched;
133
134 /* io prio of this group */
135 unsigned short ioprio, org_ioprio;
136 unsigned short ioprio_class, org_ioprio_class;
137
138 pid_t pid;
139
140 u32 seek_history;
141 sector_t last_request_pos;
142
143 struct cfq_rb_root *service_tree;
144 struct cfq_queue *new_cfqq;
145 struct cfq_group *cfqg;
146 struct cfq_group *orig_cfqg;
147 };
148
149 /*
150 * First index in the service_trees.
151 * IDLE is handled separately, so it has negative index
152 */
153 enum wl_prio_t {
154 BE_WORKLOAD = 0,
155 RT_WORKLOAD = 1,
156 IDLE_WORKLOAD = 2,
157 };
158
159 /*
160 * Second index in the service_trees.
161 */
162 enum wl_type_t {
163 ASYNC_WORKLOAD = 0,
164 SYNC_NOIDLE_WORKLOAD = 1,
165 SYNC_WORKLOAD = 2
166 };
167
168 /* This is per cgroup per device grouping structure */
169 struct cfq_group {
170 /* group service_tree member */
171 struct rb_node rb_node;
172
173 /* group service_tree key */
174 u64 vdisktime;
175 unsigned int weight;
176 bool on_st;
177
178 /* number of cfqq currently on this group */
179 int nr_cfqq;
180
181 /* Per group busy queus average. Useful for workload slice calc. */
182 unsigned int busy_queues_avg[2];
183 /*
184 * rr lists of queues with requests, onle rr for each priority class.
185 * Counts are embedded in the cfq_rb_root
186 */
187 struct cfq_rb_root service_trees[2][3];
188 struct cfq_rb_root service_tree_idle;
189
190 unsigned long saved_workload_slice;
191 enum wl_type_t saved_workload;
192 enum wl_prio_t saved_serving_prio;
193 struct blkio_group blkg;
194 #ifdef CONFIG_CFQ_GROUP_IOSCHED
195 struct hlist_node cfqd_node;
196 atomic_t ref;
197 #endif
198 };
199
200 /*
201 * Per block device queue structure
202 */
203 struct cfq_data {
204 struct request_queue *queue;
205 /* Root service tree for cfq_groups */
206 struct cfq_rb_root grp_service_tree;
207 struct cfq_group root_group;
208
209 /*
210 * The priority currently being served
211 */
212 enum wl_prio_t serving_prio;
213 enum wl_type_t serving_type;
214 unsigned long workload_expires;
215 struct cfq_group *serving_group;
216 bool noidle_tree_requires_idle;
217
218 /*
219 * Each priority tree is sorted by next_request position. These
220 * trees are used when determining if two or more queues are
221 * interleaving requests (see cfq_close_cooperator).
222 */
223 struct rb_root prio_trees[CFQ_PRIO_LISTS];
224
225 unsigned int busy_queues;
226
227 int rq_in_driver;
228 int rq_in_flight[2];
229
230 /*
231 * queue-depth detection
232 */
233 int rq_queued;
234 int hw_tag;
235 /*
236 * hw_tag can be
237 * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection)
238 * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth)
239 * 0 => no NCQ
240 */
241 int hw_tag_est_depth;
242 unsigned int hw_tag_samples;
243
244 /*
245 * idle window management
246 */
247 struct timer_list idle_slice_timer;
248 struct work_struct unplug_work;
249
250 struct cfq_queue *active_queue;
251 struct cfq_io_context *active_cic;
252
253 /*
254 * async queue for each priority case
255 */
256 struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR];
257 struct cfq_queue *async_idle_cfqq;
258
259 sector_t last_position;
260
261 /*
262 * tunables, see top of file
263 */
264 unsigned int cfq_quantum;
265 unsigned int cfq_fifo_expire[2];
266 unsigned int cfq_back_penalty;
267 unsigned int cfq_back_max;
268 unsigned int cfq_slice[2];
269 unsigned int cfq_slice_async_rq;
270 unsigned int cfq_slice_idle;
271 unsigned int cfq_latency;
272 unsigned int cfq_group_isolation;
273
274 struct list_head cic_list;
275
276 /*
277 * Fallback dummy cfqq for extreme OOM conditions
278 */
279 struct cfq_queue oom_cfqq;
280
281 unsigned long last_delayed_sync;
282
283 /* List of cfq groups being managed on this device*/
284 struct hlist_head cfqg_list;
285 struct rcu_head rcu;
286 };
287
288 static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd);
289
290 static struct cfq_rb_root *service_tree_for(struct cfq_group *cfqg,
291 enum wl_prio_t prio,
292 enum wl_type_t type)
293 {
294 if (!cfqg)
295 return NULL;
296
297 if (prio == IDLE_WORKLOAD)
298 return &cfqg->service_tree_idle;
299
300 return &cfqg->service_trees[prio][type];
301 }
302
303 enum cfqq_state_flags {
304 CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */
305 CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */
306 CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */
307 CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */
308 CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */
309 CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */
310 CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */
311 CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */
312 CFQ_CFQQ_FLAG_sync, /* synchronous queue */
313 CFQ_CFQQ_FLAG_coop, /* cfqq is shared */
314 CFQ_CFQQ_FLAG_split_coop, /* shared cfqq will be splitted */
315 CFQ_CFQQ_FLAG_deep, /* sync cfqq experienced large depth */
316 CFQ_CFQQ_FLAG_wait_busy, /* Waiting for next request */
317 };
318
319 #define CFQ_CFQQ_FNS(name) \
320 static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
321 { \
322 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
323 } \
324 static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
325 { \
326 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
327 } \
328 static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
329 { \
330 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
331 }
332
333 CFQ_CFQQ_FNS(on_rr);
334 CFQ_CFQQ_FNS(wait_request);
335 CFQ_CFQQ_FNS(must_dispatch);
336 CFQ_CFQQ_FNS(must_alloc_slice);
337 CFQ_CFQQ_FNS(fifo_expire);
338 CFQ_CFQQ_FNS(idle_window);
339 CFQ_CFQQ_FNS(prio_changed);
340 CFQ_CFQQ_FNS(slice_new);
341 CFQ_CFQQ_FNS(sync);
342 CFQ_CFQQ_FNS(coop);
343 CFQ_CFQQ_FNS(split_coop);
344 CFQ_CFQQ_FNS(deep);
345 CFQ_CFQQ_FNS(wait_busy);
346 #undef CFQ_CFQQ_FNS
347
348 #ifdef CONFIG_CFQ_GROUP_IOSCHED
349 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
350 blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \
351 cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \
352 blkg_path(&(cfqq)->cfqg->blkg), ##args);
353
354 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) \
355 blk_add_trace_msg((cfqd)->queue, "%s " fmt, \
356 blkg_path(&(cfqg)->blkg), ##args); \
357
358 #else
359 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
360 blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
361 #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0);
362 #endif
363 #define cfq_log(cfqd, fmt, args...) \
364 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
365
366 /* Traverses through cfq group service trees */
367 #define for_each_cfqg_st(cfqg, i, j, st) \
368 for (i = 0; i <= IDLE_WORKLOAD; i++) \
369 for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\
370 : &cfqg->service_tree_idle; \
371 (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \
372 (i == IDLE_WORKLOAD && j == 0); \
373 j++, st = i < IDLE_WORKLOAD ? \
374 &cfqg->service_trees[i][j]: NULL) \
375
376
377 static inline enum wl_prio_t cfqq_prio(struct cfq_queue *cfqq)
378 {
379 if (cfq_class_idle(cfqq))
380 return IDLE_WORKLOAD;
381 if (cfq_class_rt(cfqq))
382 return RT_WORKLOAD;
383 return BE_WORKLOAD;
384 }
385
386
387 static enum wl_type_t cfqq_type(struct cfq_queue *cfqq)
388 {
389 if (!cfq_cfqq_sync(cfqq))
390 return ASYNC_WORKLOAD;
391 if (!cfq_cfqq_idle_window(cfqq))
392 return SYNC_NOIDLE_WORKLOAD;
393 return SYNC_WORKLOAD;
394 }
395
396 static inline int cfq_group_busy_queues_wl(enum wl_prio_t wl,
397 struct cfq_data *cfqd,
398 struct cfq_group *cfqg)
399 {
400 if (wl == IDLE_WORKLOAD)
401 return cfqg->service_tree_idle.count;
402
403 return cfqg->service_trees[wl][ASYNC_WORKLOAD].count
404 + cfqg->service_trees[wl][SYNC_NOIDLE_WORKLOAD].count
405 + cfqg->service_trees[wl][SYNC_WORKLOAD].count;
406 }
407
408 static inline int cfqg_busy_async_queues(struct cfq_data *cfqd,
409 struct cfq_group *cfqg)
410 {
411 return cfqg->service_trees[RT_WORKLOAD][ASYNC_WORKLOAD].count
412 + cfqg->service_trees[BE_WORKLOAD][ASYNC_WORKLOAD].count;
413 }
414
415 static void cfq_dispatch_insert(struct request_queue *, struct request *);
416 static struct cfq_queue *cfq_get_queue(struct cfq_data *, bool,
417 struct io_context *, gfp_t);
418 static struct cfq_io_context *cfq_cic_lookup(struct cfq_data *,
419 struct io_context *);
420
421 static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic,
422 bool is_sync)
423 {
424 return cic->cfqq[is_sync];
425 }
426
427 static inline void cic_set_cfqq(struct cfq_io_context *cic,
428 struct cfq_queue *cfqq, bool is_sync)
429 {
430 cic->cfqq[is_sync] = cfqq;
431 }
432
433 #define CIC_DEAD_KEY 1ul
434
435 static inline void *cfqd_dead_key(struct cfq_data *cfqd)
436 {
437 return (void *)((unsigned long) cfqd | CIC_DEAD_KEY);
438 }
439
440 static inline struct cfq_data *cic_to_cfqd(struct cfq_io_context *cic)
441 {
442 struct cfq_data *cfqd = cic->key;
443
444 if (unlikely((unsigned long) cfqd & CIC_DEAD_KEY))
445 return NULL;
446
447 return cfqd;
448 }
449
450 /*
451 * We regard a request as SYNC, if it's either a read or has the SYNC bit
452 * set (in which case it could also be direct WRITE).
453 */
454 static inline bool cfq_bio_sync(struct bio *bio)
455 {
456 return bio_data_dir(bio) == READ || bio_rw_flagged(bio, BIO_RW_SYNCIO);
457 }
458
459 /*
460 * scheduler run of queue, if there are requests pending and no one in the
461 * driver that will restart queueing
462 */
463 static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
464 {
465 if (cfqd->busy_queues) {
466 cfq_log(cfqd, "schedule dispatch");
467 kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work);
468 }
469 }
470
471 static int cfq_queue_empty(struct request_queue *q)
472 {
473 struct cfq_data *cfqd = q->elevator->elevator_data;
474
475 return !cfqd->rq_queued;
476 }
477
478 /*
479 * Scale schedule slice based on io priority. Use the sync time slice only
480 * if a queue is marked sync and has sync io queued. A sync queue with async
481 * io only, should not get full sync slice length.
482 */
483 static inline int cfq_prio_slice(struct cfq_data *cfqd, bool sync,
484 unsigned short prio)
485 {
486 const int base_slice = cfqd->cfq_slice[sync];
487
488 WARN_ON(prio >= IOPRIO_BE_NR);
489
490 return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio));
491 }
492
493 static inline int
494 cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
495 {
496 return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
497 }
498
499 static inline u64 cfq_scale_slice(unsigned long delta, struct cfq_group *cfqg)
500 {
501 u64 d = delta << CFQ_SERVICE_SHIFT;
502
503 d = d * BLKIO_WEIGHT_DEFAULT;
504 do_div(d, cfqg->weight);
505 return d;
506 }
507
508 static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime)
509 {
510 s64 delta = (s64)(vdisktime - min_vdisktime);
511 if (delta > 0)
512 min_vdisktime = vdisktime;
513
514 return min_vdisktime;
515 }
516
517 static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime)
518 {
519 s64 delta = (s64)(vdisktime - min_vdisktime);
520 if (delta < 0)
521 min_vdisktime = vdisktime;
522
523 return min_vdisktime;
524 }
525
526 static void update_min_vdisktime(struct cfq_rb_root *st)
527 {
528 u64 vdisktime = st->min_vdisktime;
529 struct cfq_group *cfqg;
530
531 if (st->active) {
532 cfqg = rb_entry_cfqg(st->active);
533 vdisktime = cfqg->vdisktime;
534 }
535
536 if (st->left) {
537 cfqg = rb_entry_cfqg(st->left);
538 vdisktime = min_vdisktime(vdisktime, cfqg->vdisktime);
539 }
540
541 st->min_vdisktime = max_vdisktime(st->min_vdisktime, vdisktime);
542 }
543
544 /*
545 * get averaged number of queues of RT/BE priority.
546 * average is updated, with a formula that gives more weight to higher numbers,
547 * to quickly follows sudden increases and decrease slowly
548 */
549
550 static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd,
551 struct cfq_group *cfqg, bool rt)
552 {
553 unsigned min_q, max_q;
554 unsigned mult = cfq_hist_divisor - 1;
555 unsigned round = cfq_hist_divisor / 2;
556 unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg);
557
558 min_q = min(cfqg->busy_queues_avg[rt], busy);
559 max_q = max(cfqg->busy_queues_avg[rt], busy);
560 cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) /
561 cfq_hist_divisor;
562 return cfqg->busy_queues_avg[rt];
563 }
564
565 static inline unsigned
566 cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg)
567 {
568 struct cfq_rb_root *st = &cfqd->grp_service_tree;
569
570 return cfq_target_latency * cfqg->weight / st->total_weight;
571 }
572
573 static inline void
574 cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
575 {
576 unsigned slice = cfq_prio_to_slice(cfqd, cfqq);
577 if (cfqd->cfq_latency) {
578 /*
579 * interested queues (we consider only the ones with the same
580 * priority class in the cfq group)
581 */
582 unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg,
583 cfq_class_rt(cfqq));
584 unsigned sync_slice = cfqd->cfq_slice[1];
585 unsigned expect_latency = sync_slice * iq;
586 unsigned group_slice = cfq_group_slice(cfqd, cfqq->cfqg);
587
588 if (expect_latency > group_slice) {
589 unsigned base_low_slice = 2 * cfqd->cfq_slice_idle;
590 /* scale low_slice according to IO priority
591 * and sync vs async */
592 unsigned low_slice =
593 min(slice, base_low_slice * slice / sync_slice);
594 /* the adapted slice value is scaled to fit all iqs
595 * into the target latency */
596 slice = max(slice * group_slice / expect_latency,
597 low_slice);
598 }
599 }
600 cfqq->slice_start = jiffies;
601 cfqq->slice_end = jiffies + slice;
602 cfqq->allocated_slice = slice;
603 cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies);
604 }
605
606 /*
607 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
608 * isn't valid until the first request from the dispatch is activated
609 * and the slice time set.
610 */
611 static inline bool cfq_slice_used(struct cfq_queue *cfqq)
612 {
613 if (cfq_cfqq_slice_new(cfqq))
614 return 0;
615 if (time_before(jiffies, cfqq->slice_end))
616 return 0;
617
618 return 1;
619 }
620
621 /*
622 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
623 * We choose the request that is closest to the head right now. Distance
624 * behind the head is penalized and only allowed to a certain extent.
625 */
626 static struct request *
627 cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last)
628 {
629 sector_t s1, s2, d1 = 0, d2 = 0;
630 unsigned long back_max;
631 #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
632 #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
633 unsigned wrap = 0; /* bit mask: requests behind the disk head? */
634
635 if (rq1 == NULL || rq1 == rq2)
636 return rq2;
637 if (rq2 == NULL)
638 return rq1;
639
640 if (rq_is_sync(rq1) && !rq_is_sync(rq2))
641 return rq1;
642 else if (rq_is_sync(rq2) && !rq_is_sync(rq1))
643 return rq2;
644 if (rq_is_meta(rq1) && !rq_is_meta(rq2))
645 return rq1;
646 else if (rq_is_meta(rq2) && !rq_is_meta(rq1))
647 return rq2;
648
649 s1 = blk_rq_pos(rq1);
650 s2 = blk_rq_pos(rq2);
651
652 /*
653 * by definition, 1KiB is 2 sectors
654 */
655 back_max = cfqd->cfq_back_max * 2;
656
657 /*
658 * Strict one way elevator _except_ in the case where we allow
659 * short backward seeks which are biased as twice the cost of a
660 * similar forward seek.
661 */
662 if (s1 >= last)
663 d1 = s1 - last;
664 else if (s1 + back_max >= last)
665 d1 = (last - s1) * cfqd->cfq_back_penalty;
666 else
667 wrap |= CFQ_RQ1_WRAP;
668
669 if (s2 >= last)
670 d2 = s2 - last;
671 else if (s2 + back_max >= last)
672 d2 = (last - s2) * cfqd->cfq_back_penalty;
673 else
674 wrap |= CFQ_RQ2_WRAP;
675
676 /* Found required data */
677
678 /*
679 * By doing switch() on the bit mask "wrap" we avoid having to
680 * check two variables for all permutations: --> faster!
681 */
682 switch (wrap) {
683 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
684 if (d1 < d2)
685 return rq1;
686 else if (d2 < d1)
687 return rq2;
688 else {
689 if (s1 >= s2)
690 return rq1;
691 else
692 return rq2;
693 }
694
695 case CFQ_RQ2_WRAP:
696 return rq1;
697 case CFQ_RQ1_WRAP:
698 return rq2;
699 case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */
700 default:
701 /*
702 * Since both rqs are wrapped,
703 * start with the one that's further behind head
704 * (--> only *one* back seek required),
705 * since back seek takes more time than forward.
706 */
707 if (s1 <= s2)
708 return rq1;
709 else
710 return rq2;
711 }
712 }
713
714 /*
715 * The below is leftmost cache rbtree addon
716 */
717 static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
718 {
719 /* Service tree is empty */
720 if (!root->count)
721 return NULL;
722
723 if (!root->left)
724 root->left = rb_first(&root->rb);
725
726 if (root->left)
727 return rb_entry(root->left, struct cfq_queue, rb_node);
728
729 return NULL;
730 }
731
732 static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root)
733 {
734 if (!root->left)
735 root->left = rb_first(&root->rb);
736
737 if (root->left)
738 return rb_entry_cfqg(root->left);
739
740 return NULL;
741 }
742
743 static void rb_erase_init(struct rb_node *n, struct rb_root *root)
744 {
745 rb_erase(n, root);
746 RB_CLEAR_NODE(n);
747 }
748
749 static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)
750 {
751 if (root->left == n)
752 root->left = NULL;
753 rb_erase_init(n, &root->rb);
754 --root->count;
755 }
756
757 /*
758 * would be nice to take fifo expire time into account as well
759 */
760 static struct request *
761 cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
762 struct request *last)
763 {
764 struct rb_node *rbnext = rb_next(&last->rb_node);
765 struct rb_node *rbprev = rb_prev(&last->rb_node);
766 struct request *next = NULL, *prev = NULL;
767
768 BUG_ON(RB_EMPTY_NODE(&last->rb_node));
769
770 if (rbprev)
771 prev = rb_entry_rq(rbprev);
772
773 if (rbnext)
774 next = rb_entry_rq(rbnext);
775 else {
776 rbnext = rb_first(&cfqq->sort_list);
777 if (rbnext && rbnext != &last->rb_node)
778 next = rb_entry_rq(rbnext);
779 }
780
781 return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last));
782 }
783
784 static unsigned long cfq_slice_offset(struct cfq_data *cfqd,
785 struct cfq_queue *cfqq)
786 {
787 /*
788 * just an approximation, should be ok.
789 */
790 return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) -
791 cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio));
792 }
793
794 static inline s64
795 cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg)
796 {
797 return cfqg->vdisktime - st->min_vdisktime;
798 }
799
800 static void
801 __cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg)
802 {
803 struct rb_node **node = &st->rb.rb_node;
804 struct rb_node *parent = NULL;
805 struct cfq_group *__cfqg;
806 s64 key = cfqg_key(st, cfqg);
807 int left = 1;
808
809 while (*node != NULL) {
810 parent = *node;
811 __cfqg = rb_entry_cfqg(parent);
812
813 if (key < cfqg_key(st, __cfqg))
814 node = &parent->rb_left;
815 else {
816 node = &parent->rb_right;
817 left = 0;
818 }
819 }
820
821 if (left)
822 st->left = &cfqg->rb_node;
823
824 rb_link_node(&cfqg->rb_node, parent, node);
825 rb_insert_color(&cfqg->rb_node, &st->rb);
826 }
827
828 static void
829 cfq_group_service_tree_add(struct cfq_data *cfqd, struct cfq_group *cfqg)
830 {
831 struct cfq_rb_root *st = &cfqd->grp_service_tree;
832 struct cfq_group *__cfqg;
833 struct rb_node *n;
834
835 cfqg->nr_cfqq++;
836 if (cfqg->on_st)
837 return;
838
839 /*
840 * Currently put the group at the end. Later implement something
841 * so that groups get lesser vtime based on their weights, so that
842 * if group does not loose all if it was not continously backlogged.
843 */
844 n = rb_last(&st->rb);
845 if (n) {
846 __cfqg = rb_entry_cfqg(n);
847 cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY;
848 } else
849 cfqg->vdisktime = st->min_vdisktime;
850
851 __cfq_group_service_tree_add(st, cfqg);
852 cfqg->on_st = true;
853 st->total_weight += cfqg->weight;
854 }
855
856 static void
857 cfq_group_service_tree_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
858 {
859 struct cfq_rb_root *st = &cfqd->grp_service_tree;
860
861 if (st->active == &cfqg->rb_node)
862 st->active = NULL;
863
864 BUG_ON(cfqg->nr_cfqq < 1);
865 cfqg->nr_cfqq--;
866
867 /* If there are other cfq queues under this group, don't delete it */
868 if (cfqg->nr_cfqq)
869 return;
870
871 cfq_log_cfqg(cfqd, cfqg, "del_from_rr group");
872 cfqg->on_st = false;
873 st->total_weight -= cfqg->weight;
874 if (!RB_EMPTY_NODE(&cfqg->rb_node))
875 cfq_rb_erase(&cfqg->rb_node, st);
876 cfqg->saved_workload_slice = 0;
877 blkiocg_update_dequeue_stats(&cfqg->blkg, 1);
878 }
879
880 static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq)
881 {
882 unsigned int slice_used;
883
884 /*
885 * Queue got expired before even a single request completed or
886 * got expired immediately after first request completion.
887 */
888 if (!cfqq->slice_start || cfqq->slice_start == jiffies) {
889 /*
890 * Also charge the seek time incurred to the group, otherwise
891 * if there are mutiple queues in the group, each can dispatch
892 * a single request on seeky media and cause lots of seek time
893 * and group will never know it.
894 */
895 slice_used = max_t(unsigned, (jiffies - cfqq->dispatch_start),
896 1);
897 } else {
898 slice_used = jiffies - cfqq->slice_start;
899 if (slice_used > cfqq->allocated_slice)
900 slice_used = cfqq->allocated_slice;
901 }
902
903 cfq_log_cfqq(cfqq->cfqd, cfqq, "sl_used=%u", slice_used);
904 return slice_used;
905 }
906
907 static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
908 struct cfq_queue *cfqq)
909 {
910 struct cfq_rb_root *st = &cfqd->grp_service_tree;
911 unsigned int used_sl, charge_sl;
912 int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg)
913 - cfqg->service_tree_idle.count;
914
915 BUG_ON(nr_sync < 0);
916 used_sl = charge_sl = cfq_cfqq_slice_usage(cfqq);
917
918 if (!cfq_cfqq_sync(cfqq) && !nr_sync)
919 charge_sl = cfqq->allocated_slice;
920
921 /* Can't update vdisktime while group is on service tree */
922 cfq_rb_erase(&cfqg->rb_node, st);
923 cfqg->vdisktime += cfq_scale_slice(charge_sl, cfqg);
924 __cfq_group_service_tree_add(st, cfqg);
925
926 /* This group is being expired. Save the context */
927 if (time_after(cfqd->workload_expires, jiffies)) {
928 cfqg->saved_workload_slice = cfqd->workload_expires
929 - jiffies;
930 cfqg->saved_workload = cfqd->serving_type;
931 cfqg->saved_serving_prio = cfqd->serving_prio;
932 } else
933 cfqg->saved_workload_slice = 0;
934
935 cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime,
936 st->min_vdisktime);
937 blkiocg_update_timeslice_used(&cfqg->blkg, used_sl);
938 blkiocg_set_start_empty_time(&cfqg->blkg);
939 }
940
941 #ifdef CONFIG_CFQ_GROUP_IOSCHED
942 static inline struct cfq_group *cfqg_of_blkg(struct blkio_group *blkg)
943 {
944 if (blkg)
945 return container_of(blkg, struct cfq_group, blkg);
946 return NULL;
947 }
948
949 void
950 cfq_update_blkio_group_weight(struct blkio_group *blkg, unsigned int weight)
951 {
952 cfqg_of_blkg(blkg)->weight = weight;
953 }
954
955 static struct cfq_group *
956 cfq_find_alloc_cfqg(struct cfq_data *cfqd, struct cgroup *cgroup, int create)
957 {
958 struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup);
959 struct cfq_group *cfqg = NULL;
960 void *key = cfqd;
961 int i, j;
962 struct cfq_rb_root *st;
963 struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info;
964 unsigned int major, minor;
965
966 cfqg = cfqg_of_blkg(blkiocg_lookup_group(blkcg, key));
967 if (cfqg && !cfqg->blkg.dev && bdi->dev && dev_name(bdi->dev)) {
968 sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
969 cfqg->blkg.dev = MKDEV(major, minor);
970 goto done;
971 }
972 if (cfqg || !create)
973 goto done;
974
975 cfqg = kzalloc_node(sizeof(*cfqg), GFP_ATOMIC, cfqd->queue->node);
976 if (!cfqg)
977 goto done;
978
979 for_each_cfqg_st(cfqg, i, j, st)
980 *st = CFQ_RB_ROOT;
981 RB_CLEAR_NODE(&cfqg->rb_node);
982
983 /*
984 * Take the initial reference that will be released on destroy
985 * This can be thought of a joint reference by cgroup and
986 * elevator which will be dropped by either elevator exit
987 * or cgroup deletion path depending on who is exiting first.
988 */
989 atomic_set(&cfqg->ref, 1);
990
991 /* Add group onto cgroup list */
992 sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
993 blkiocg_add_blkio_group(blkcg, &cfqg->blkg, (void *)cfqd,
994 MKDEV(major, minor));
995 cfqg->weight = blkcg_get_weight(blkcg, cfqg->blkg.dev);
996
997 /* Add group on cfqd list */
998 hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list);
999
1000 done:
1001 return cfqg;
1002 }
1003
1004 /*
1005 * Search for the cfq group current task belongs to. If create = 1, then also
1006 * create the cfq group if it does not exist. request_queue lock must be held.
1007 */
1008 static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create)
1009 {
1010 struct cgroup *cgroup;
1011 struct cfq_group *cfqg = NULL;
1012
1013 rcu_read_lock();
1014 cgroup = task_cgroup(current, blkio_subsys_id);
1015 cfqg = cfq_find_alloc_cfqg(cfqd, cgroup, create);
1016 if (!cfqg && create)
1017 cfqg = &cfqd->root_group;
1018 rcu_read_unlock();
1019 return cfqg;
1020 }
1021
1022 static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg)
1023 {
1024 atomic_inc(&cfqg->ref);
1025 return cfqg;
1026 }
1027
1028 static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg)
1029 {
1030 /* Currently, all async queues are mapped to root group */
1031 if (!cfq_cfqq_sync(cfqq))
1032 cfqg = &cfqq->cfqd->root_group;
1033
1034 cfqq->cfqg = cfqg;
1035 /* cfqq reference on cfqg */
1036 atomic_inc(&cfqq->cfqg->ref);
1037 }
1038
1039 static void cfq_put_cfqg(struct cfq_group *cfqg)
1040 {
1041 struct cfq_rb_root *st;
1042 int i, j;
1043
1044 BUG_ON(atomic_read(&cfqg->ref) <= 0);
1045 if (!atomic_dec_and_test(&cfqg->ref))
1046 return;
1047 for_each_cfqg_st(cfqg, i, j, st)
1048 BUG_ON(!RB_EMPTY_ROOT(&st->rb) || st->active != NULL);
1049 kfree(cfqg);
1050 }
1051
1052 static void cfq_destroy_cfqg(struct cfq_data *cfqd, struct cfq_group *cfqg)
1053 {
1054 /* Something wrong if we are trying to remove same group twice */
1055 BUG_ON(hlist_unhashed(&cfqg->cfqd_node));
1056
1057 hlist_del_init(&cfqg->cfqd_node);
1058
1059 /*
1060 * Put the reference taken at the time of creation so that when all
1061 * queues are gone, group can be destroyed.
1062 */
1063 cfq_put_cfqg(cfqg);
1064 }
1065
1066 static void cfq_release_cfq_groups(struct cfq_data *cfqd)
1067 {
1068 struct hlist_node *pos, *n;
1069 struct cfq_group *cfqg;
1070
1071 hlist_for_each_entry_safe(cfqg, pos, n, &cfqd->cfqg_list, cfqd_node) {
1072 /*
1073 * If cgroup removal path got to blk_group first and removed
1074 * it from cgroup list, then it will take care of destroying
1075 * cfqg also.
1076 */
1077 if (!blkiocg_del_blkio_group(&cfqg->blkg))
1078 cfq_destroy_cfqg(cfqd, cfqg);
1079 }
1080 }
1081
1082 /*
1083 * Blk cgroup controller notification saying that blkio_group object is being
1084 * delinked as associated cgroup object is going away. That also means that
1085 * no new IO will come in this group. So get rid of this group as soon as
1086 * any pending IO in the group is finished.
1087 *
1088 * This function is called under rcu_read_lock(). key is the rcu protected
1089 * pointer. That means "key" is a valid cfq_data pointer as long as we are rcu
1090 * read lock.
1091 *
1092 * "key" was fetched from blkio_group under blkio_cgroup->lock. That means
1093 * it should not be NULL as even if elevator was exiting, cgroup deltion
1094 * path got to it first.
1095 */
1096 void cfq_unlink_blkio_group(void *key, struct blkio_group *blkg)
1097 {
1098 unsigned long flags;
1099 struct cfq_data *cfqd = key;
1100
1101 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
1102 cfq_destroy_cfqg(cfqd, cfqg_of_blkg(blkg));
1103 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
1104 }
1105
1106 #else /* GROUP_IOSCHED */
1107 static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create)
1108 {
1109 return &cfqd->root_group;
1110 }
1111
1112 static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg)
1113 {
1114 return cfqg;
1115 }
1116
1117 static inline void
1118 cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) {
1119 cfqq->cfqg = cfqg;
1120 }
1121
1122 static void cfq_release_cfq_groups(struct cfq_data *cfqd) {}
1123 static inline void cfq_put_cfqg(struct cfq_group *cfqg) {}
1124
1125 #endif /* GROUP_IOSCHED */
1126
1127 /*
1128 * The cfqd->service_trees holds all pending cfq_queue's that have
1129 * requests waiting to be processed. It is sorted in the order that
1130 * we will service the queues.
1131 */
1132 static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1133 bool add_front)
1134 {
1135 struct rb_node **p, *parent;
1136 struct cfq_queue *__cfqq;
1137 unsigned long rb_key;
1138 struct cfq_rb_root *service_tree;
1139 int left;
1140 int new_cfqq = 1;
1141 int group_changed = 0;
1142
1143 #ifdef CONFIG_CFQ_GROUP_IOSCHED
1144 if (!cfqd->cfq_group_isolation
1145 && cfqq_type(cfqq) == SYNC_NOIDLE_WORKLOAD
1146 && cfqq->cfqg && cfqq->cfqg != &cfqd->root_group) {
1147 /* Move this cfq to root group */
1148 cfq_log_cfqq(cfqd, cfqq, "moving to root group");
1149 if (!RB_EMPTY_NODE(&cfqq->rb_node))
1150 cfq_group_service_tree_del(cfqd, cfqq->cfqg);
1151 cfqq->orig_cfqg = cfqq->cfqg;
1152 cfqq->cfqg = &cfqd->root_group;
1153 atomic_inc(&cfqd->root_group.ref);
1154 group_changed = 1;
1155 } else if (!cfqd->cfq_group_isolation
1156 && cfqq_type(cfqq) == SYNC_WORKLOAD && cfqq->orig_cfqg) {
1157 /* cfqq is sequential now needs to go to its original group */
1158 BUG_ON(cfqq->cfqg != &cfqd->root_group);
1159 if (!RB_EMPTY_NODE(&cfqq->rb_node))
1160 cfq_group_service_tree_del(cfqd, cfqq->cfqg);
1161 cfq_put_cfqg(cfqq->cfqg);
1162 cfqq->cfqg = cfqq->orig_cfqg;
1163 cfqq->orig_cfqg = NULL;
1164 group_changed = 1;
1165 cfq_log_cfqq(cfqd, cfqq, "moved to origin group");
1166 }
1167 #endif
1168
1169 service_tree = service_tree_for(cfqq->cfqg, cfqq_prio(cfqq),
1170 cfqq_type(cfqq));
1171 if (cfq_class_idle(cfqq)) {
1172 rb_key = CFQ_IDLE_DELAY;
1173 parent = rb_last(&service_tree->rb);
1174 if (parent && parent != &cfqq->rb_node) {
1175 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
1176 rb_key += __cfqq->rb_key;
1177 } else
1178 rb_key += jiffies;
1179 } else if (!add_front) {
1180 /*
1181 * Get our rb key offset. Subtract any residual slice
1182 * value carried from last service. A negative resid
1183 * count indicates slice overrun, and this should position
1184 * the next service time further away in the tree.
1185 */
1186 rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies;
1187 rb_key -= cfqq->slice_resid;
1188 cfqq->slice_resid = 0;
1189 } else {
1190 rb_key = -HZ;
1191 __cfqq = cfq_rb_first(service_tree);
1192 rb_key += __cfqq ? __cfqq->rb_key : jiffies;
1193 }
1194
1195 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
1196 new_cfqq = 0;
1197 /*
1198 * same position, nothing more to do
1199 */
1200 if (rb_key == cfqq->rb_key &&
1201 cfqq->service_tree == service_tree)
1202 return;
1203
1204 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
1205 cfqq->service_tree = NULL;
1206 }
1207
1208 left = 1;
1209 parent = NULL;
1210 cfqq->service_tree = service_tree;
1211 p = &service_tree->rb.rb_node;
1212 while (*p) {
1213 struct rb_node **n;
1214
1215 parent = *p;
1216 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
1217
1218 /*
1219 * sort by key, that represents service time.
1220 */
1221 if (time_before(rb_key, __cfqq->rb_key))
1222 n = &(*p)->rb_left;
1223 else {
1224 n = &(*p)->rb_right;
1225 left = 0;
1226 }
1227
1228 p = n;
1229 }
1230
1231 if (left)
1232 service_tree->left = &cfqq->rb_node;
1233
1234 cfqq->rb_key = rb_key;
1235 rb_link_node(&cfqq->rb_node, parent, p);
1236 rb_insert_color(&cfqq->rb_node, &service_tree->rb);
1237 service_tree->count++;
1238 if ((add_front || !new_cfqq) && !group_changed)
1239 return;
1240 cfq_group_service_tree_add(cfqd, cfqq->cfqg);
1241 }
1242
1243 static struct cfq_queue *
1244 cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root,
1245 sector_t sector, struct rb_node **ret_parent,
1246 struct rb_node ***rb_link)
1247 {
1248 struct rb_node **p, *parent;
1249 struct cfq_queue *cfqq = NULL;
1250
1251 parent = NULL;
1252 p = &root->rb_node;
1253 while (*p) {
1254 struct rb_node **n;
1255
1256 parent = *p;
1257 cfqq = rb_entry(parent, struct cfq_queue, p_node);
1258
1259 /*
1260 * Sort strictly based on sector. Smallest to the left,
1261 * largest to the right.
1262 */
1263 if (sector > blk_rq_pos(cfqq->next_rq))
1264 n = &(*p)->rb_right;
1265 else if (sector < blk_rq_pos(cfqq->next_rq))
1266 n = &(*p)->rb_left;
1267 else
1268 break;
1269 p = n;
1270 cfqq = NULL;
1271 }
1272
1273 *ret_parent = parent;
1274 if (rb_link)
1275 *rb_link = p;
1276 return cfqq;
1277 }
1278
1279 static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1280 {
1281 struct rb_node **p, *parent;
1282 struct cfq_queue *__cfqq;
1283
1284 if (cfqq->p_root) {
1285 rb_erase(&cfqq->p_node, cfqq->p_root);
1286 cfqq->p_root = NULL;
1287 }
1288
1289 if (cfq_class_idle(cfqq))
1290 return;
1291 if (!cfqq->next_rq)
1292 return;
1293
1294 cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
1295 __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root,
1296 blk_rq_pos(cfqq->next_rq), &parent, &p);
1297 if (!__cfqq) {
1298 rb_link_node(&cfqq->p_node, parent, p);
1299 rb_insert_color(&cfqq->p_node, cfqq->p_root);
1300 } else
1301 cfqq->p_root = NULL;
1302 }
1303
1304 /*
1305 * Update cfqq's position in the service tree.
1306 */
1307 static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1308 {
1309 /*
1310 * Resorting requires the cfqq to be on the RR list already.
1311 */
1312 if (cfq_cfqq_on_rr(cfqq)) {
1313 cfq_service_tree_add(cfqd, cfqq, 0);
1314 cfq_prio_tree_add(cfqd, cfqq);
1315 }
1316 }
1317
1318 /*
1319 * add to busy list of queues for service, trying to be fair in ordering
1320 * the pending list according to last request service
1321 */
1322 static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1323 {
1324 cfq_log_cfqq(cfqd, cfqq, "add_to_rr");
1325 BUG_ON(cfq_cfqq_on_rr(cfqq));
1326 cfq_mark_cfqq_on_rr(cfqq);
1327 cfqd->busy_queues++;
1328
1329 cfq_resort_rr_list(cfqd, cfqq);
1330 }
1331
1332 /*
1333 * Called when the cfqq no longer has requests pending, remove it from
1334 * the service tree.
1335 */
1336 static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1337 {
1338 cfq_log_cfqq(cfqd, cfqq, "del_from_rr");
1339 BUG_ON(!cfq_cfqq_on_rr(cfqq));
1340 cfq_clear_cfqq_on_rr(cfqq);
1341
1342 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
1343 cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree);
1344 cfqq->service_tree = NULL;
1345 }
1346 if (cfqq->p_root) {
1347 rb_erase(&cfqq->p_node, cfqq->p_root);
1348 cfqq->p_root = NULL;
1349 }
1350
1351 cfq_group_service_tree_del(cfqd, cfqq->cfqg);
1352 BUG_ON(!cfqd->busy_queues);
1353 cfqd->busy_queues--;
1354 }
1355
1356 /*
1357 * rb tree support functions
1358 */
1359 static void cfq_del_rq_rb(struct request *rq)
1360 {
1361 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1362 const int sync = rq_is_sync(rq);
1363
1364 BUG_ON(!cfqq->queued[sync]);
1365 cfqq->queued[sync]--;
1366
1367 elv_rb_del(&cfqq->sort_list, rq);
1368
1369 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) {
1370 /*
1371 * Queue will be deleted from service tree when we actually
1372 * expire it later. Right now just remove it from prio tree
1373 * as it is empty.
1374 */
1375 if (cfqq->p_root) {
1376 rb_erase(&cfqq->p_node, cfqq->p_root);
1377 cfqq->p_root = NULL;
1378 }
1379 }
1380 }
1381
1382 static void cfq_add_rq_rb(struct request *rq)
1383 {
1384 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1385 struct cfq_data *cfqd = cfqq->cfqd;
1386 struct request *__alias, *prev;
1387
1388 cfqq->queued[rq_is_sync(rq)]++;
1389
1390 /*
1391 * looks a little odd, but the first insert might return an alias.
1392 * if that happens, put the alias on the dispatch list
1393 */
1394 while ((__alias = elv_rb_add(&cfqq->sort_list, rq)) != NULL)
1395 cfq_dispatch_insert(cfqd->queue, __alias);
1396
1397 if (!cfq_cfqq_on_rr(cfqq))
1398 cfq_add_cfqq_rr(cfqd, cfqq);
1399
1400 /*
1401 * check if this request is a better next-serve candidate
1402 */
1403 prev = cfqq->next_rq;
1404 cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position);
1405
1406 /*
1407 * adjust priority tree position, if ->next_rq changes
1408 */
1409 if (prev != cfqq->next_rq)
1410 cfq_prio_tree_add(cfqd, cfqq);
1411
1412 BUG_ON(!cfqq->next_rq);
1413 }
1414
1415 static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq)
1416 {
1417 elv_rb_del(&cfqq->sort_list, rq);
1418 cfqq->queued[rq_is_sync(rq)]--;
1419 blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg, rq_data_dir(rq),
1420 rq_is_sync(rq));
1421 cfq_add_rq_rb(rq);
1422 blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg,
1423 &cfqq->cfqd->serving_group->blkg, rq_data_dir(rq),
1424 rq_is_sync(rq));
1425 }
1426
1427 static struct request *
1428 cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
1429 {
1430 struct task_struct *tsk = current;
1431 struct cfq_io_context *cic;
1432 struct cfq_queue *cfqq;
1433
1434 cic = cfq_cic_lookup(cfqd, tsk->io_context);
1435 if (!cic)
1436 return NULL;
1437
1438 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
1439 if (cfqq) {
1440 sector_t sector = bio->bi_sector + bio_sectors(bio);
1441
1442 return elv_rb_find(&cfqq->sort_list, sector);
1443 }
1444
1445 return NULL;
1446 }
1447
1448 static void cfq_activate_request(struct request_queue *q, struct request *rq)
1449 {
1450 struct cfq_data *cfqd = q->elevator->elevator_data;
1451
1452 cfqd->rq_in_driver++;
1453 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
1454 cfqd->rq_in_driver);
1455
1456 cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
1457 }
1458
1459 static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
1460 {
1461 struct cfq_data *cfqd = q->elevator->elevator_data;
1462
1463 WARN_ON(!cfqd->rq_in_driver);
1464 cfqd->rq_in_driver--;
1465 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
1466 cfqd->rq_in_driver);
1467 }
1468
1469 static void cfq_remove_request(struct request *rq)
1470 {
1471 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1472
1473 if (cfqq->next_rq == rq)
1474 cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq);
1475
1476 list_del_init(&rq->queuelist);
1477 cfq_del_rq_rb(rq);
1478
1479 cfqq->cfqd->rq_queued--;
1480 blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg, rq_data_dir(rq),
1481 rq_is_sync(rq));
1482 if (rq_is_meta(rq)) {
1483 WARN_ON(!cfqq->meta_pending);
1484 cfqq->meta_pending--;
1485 }
1486 }
1487
1488 static int cfq_merge(struct request_queue *q, struct request **req,
1489 struct bio *bio)
1490 {
1491 struct cfq_data *cfqd = q->elevator->elevator_data;
1492 struct request *__rq;
1493
1494 __rq = cfq_find_rq_fmerge(cfqd, bio);
1495 if (__rq && elv_rq_merge_ok(__rq, bio)) {
1496 *req = __rq;
1497 return ELEVATOR_FRONT_MERGE;
1498 }
1499
1500 return ELEVATOR_NO_MERGE;
1501 }
1502
1503 static void cfq_merged_request(struct request_queue *q, struct request *req,
1504 int type)
1505 {
1506 if (type == ELEVATOR_FRONT_MERGE) {
1507 struct cfq_queue *cfqq = RQ_CFQQ(req);
1508
1509 cfq_reposition_rq_rb(cfqq, req);
1510 }
1511 }
1512
1513 static void cfq_bio_merged(struct request_queue *q, struct request *req,
1514 struct bio *bio)
1515 {
1516 blkiocg_update_io_merged_stats(&(RQ_CFQG(req))->blkg, bio_data_dir(bio),
1517 cfq_bio_sync(bio));
1518 }
1519
1520 static void
1521 cfq_merged_requests(struct request_queue *q, struct request *rq,
1522 struct request *next)
1523 {
1524 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1525 /*
1526 * reposition in fifo if next is older than rq
1527 */
1528 if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
1529 time_before(rq_fifo_time(next), rq_fifo_time(rq))) {
1530 list_move(&rq->queuelist, &next->queuelist);
1531 rq_set_fifo_time(rq, rq_fifo_time(next));
1532 }
1533
1534 if (cfqq->next_rq == next)
1535 cfqq->next_rq = rq;
1536 cfq_remove_request(next);
1537 blkiocg_update_io_merged_stats(&(RQ_CFQG(rq))->blkg, rq_data_dir(next),
1538 rq_is_sync(next));
1539 }
1540
1541 static int cfq_allow_merge(struct request_queue *q, struct request *rq,
1542 struct bio *bio)
1543 {
1544 struct cfq_data *cfqd = q->elevator->elevator_data;
1545 struct cfq_io_context *cic;
1546 struct cfq_queue *cfqq;
1547
1548 /*
1549 * Disallow merge of a sync bio into an async request.
1550 */
1551 if (cfq_bio_sync(bio) && !rq_is_sync(rq))
1552 return false;
1553
1554 /*
1555 * Lookup the cfqq that this bio will be queued with. Allow
1556 * merge only if rq is queued there.
1557 */
1558 cic = cfq_cic_lookup(cfqd, current->io_context);
1559 if (!cic)
1560 return false;
1561
1562 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
1563 return cfqq == RQ_CFQQ(rq);
1564 }
1565
1566 static inline void cfq_del_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1567 {
1568 del_timer(&cfqd->idle_slice_timer);
1569 blkiocg_update_idle_time_stats(&cfqq->cfqg->blkg);
1570 }
1571
1572 static void __cfq_set_active_queue(struct cfq_data *cfqd,
1573 struct cfq_queue *cfqq)
1574 {
1575 if (cfqq) {
1576 cfq_log_cfqq(cfqd, cfqq, "set_active wl_prio:%d wl_type:%d",
1577 cfqd->serving_prio, cfqd->serving_type);
1578 blkiocg_update_avg_queue_size_stats(&cfqq->cfqg->blkg);
1579 cfqq->slice_start = 0;
1580 cfqq->dispatch_start = jiffies;
1581 cfqq->allocated_slice = 0;
1582 cfqq->slice_end = 0;
1583 cfqq->slice_dispatch = 0;
1584
1585 cfq_clear_cfqq_wait_request(cfqq);
1586 cfq_clear_cfqq_must_dispatch(cfqq);
1587 cfq_clear_cfqq_must_alloc_slice(cfqq);
1588 cfq_clear_cfqq_fifo_expire(cfqq);
1589 cfq_mark_cfqq_slice_new(cfqq);
1590
1591 cfq_del_timer(cfqd, cfqq);
1592 }
1593
1594 cfqd->active_queue = cfqq;
1595 }
1596
1597 /*
1598 * current cfqq expired its slice (or was too idle), select new one
1599 */
1600 static void
1601 __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1602 bool timed_out)
1603 {
1604 cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out);
1605
1606 if (cfq_cfqq_wait_request(cfqq))
1607 cfq_del_timer(cfqd, cfqq);
1608
1609 cfq_clear_cfqq_wait_request(cfqq);
1610 cfq_clear_cfqq_wait_busy(cfqq);
1611
1612 /*
1613 * If this cfqq is shared between multiple processes, check to
1614 * make sure that those processes are still issuing I/Os within
1615 * the mean seek distance. If not, it may be time to break the
1616 * queues apart again.
1617 */
1618 if (cfq_cfqq_coop(cfqq) && CFQQ_SEEKY(cfqq))
1619 cfq_mark_cfqq_split_coop(cfqq);
1620
1621 /*
1622 * store what was left of this slice, if the queue idled/timed out
1623 */
1624 if (timed_out && !cfq_cfqq_slice_new(cfqq)) {
1625 cfqq->slice_resid = cfqq->slice_end - jiffies;
1626 cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
1627 }
1628
1629 cfq_group_served(cfqd, cfqq->cfqg, cfqq);
1630
1631 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
1632 cfq_del_cfqq_rr(cfqd, cfqq);
1633
1634 cfq_resort_rr_list(cfqd, cfqq);
1635
1636 if (cfqq == cfqd->active_queue)
1637 cfqd->active_queue = NULL;
1638
1639 if (&cfqq->cfqg->rb_node == cfqd->grp_service_tree.active)
1640 cfqd->grp_service_tree.active = NULL;
1641
1642 if (cfqd->active_cic) {
1643 put_io_context(cfqd->active_cic->ioc);
1644 cfqd->active_cic = NULL;
1645 }
1646 }
1647
1648 static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out)
1649 {
1650 struct cfq_queue *cfqq = cfqd->active_queue;
1651
1652 if (cfqq)
1653 __cfq_slice_expired(cfqd, cfqq, timed_out);
1654 }
1655
1656 /*
1657 * Get next queue for service. Unless we have a queue preemption,
1658 * we'll simply select the first cfqq in the service tree.
1659 */
1660 static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
1661 {
1662 struct cfq_rb_root *service_tree =
1663 service_tree_for(cfqd->serving_group, cfqd->serving_prio,
1664 cfqd->serving_type);
1665
1666 if (!cfqd->rq_queued)
1667 return NULL;
1668
1669 /* There is nothing to dispatch */
1670 if (!service_tree)
1671 return NULL;
1672 if (RB_EMPTY_ROOT(&service_tree->rb))
1673 return NULL;
1674 return cfq_rb_first(service_tree);
1675 }
1676
1677 static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd)
1678 {
1679 struct cfq_group *cfqg;
1680 struct cfq_queue *cfqq;
1681 int i, j;
1682 struct cfq_rb_root *st;
1683
1684 if (!cfqd->rq_queued)
1685 return NULL;
1686
1687 cfqg = cfq_get_next_cfqg(cfqd);
1688 if (!cfqg)
1689 return NULL;
1690
1691 for_each_cfqg_st(cfqg, i, j, st)
1692 if ((cfqq = cfq_rb_first(st)) != NULL)
1693 return cfqq;
1694 return NULL;
1695 }
1696
1697 /*
1698 * Get and set a new active queue for service.
1699 */
1700 static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
1701 struct cfq_queue *cfqq)
1702 {
1703 if (!cfqq)
1704 cfqq = cfq_get_next_queue(cfqd);
1705
1706 __cfq_set_active_queue(cfqd, cfqq);
1707 return cfqq;
1708 }
1709
1710 static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
1711 struct request *rq)
1712 {
1713 if (blk_rq_pos(rq) >= cfqd->last_position)
1714 return blk_rq_pos(rq) - cfqd->last_position;
1715 else
1716 return cfqd->last_position - blk_rq_pos(rq);
1717 }
1718
1719 static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1720 struct request *rq)
1721 {
1722 return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR;
1723 }
1724
1725 static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
1726 struct cfq_queue *cur_cfqq)
1727 {
1728 struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
1729 struct rb_node *parent, *node;
1730 struct cfq_queue *__cfqq;
1731 sector_t sector = cfqd->last_position;
1732
1733 if (RB_EMPTY_ROOT(root))
1734 return NULL;
1735
1736 /*
1737 * First, if we find a request starting at the end of the last
1738 * request, choose it.
1739 */
1740 __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
1741 if (__cfqq)
1742 return __cfqq;
1743
1744 /*
1745 * If the exact sector wasn't found, the parent of the NULL leaf
1746 * will contain the closest sector.
1747 */
1748 __cfqq = rb_entry(parent, struct cfq_queue, p_node);
1749 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
1750 return __cfqq;
1751
1752 if (blk_rq_pos(__cfqq->next_rq) < sector)
1753 node = rb_next(&__cfqq->p_node);
1754 else
1755 node = rb_prev(&__cfqq->p_node);
1756 if (!node)
1757 return NULL;
1758
1759 __cfqq = rb_entry(node, struct cfq_queue, p_node);
1760 if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq))
1761 return __cfqq;
1762
1763 return NULL;
1764 }
1765
1766 /*
1767 * cfqd - obvious
1768 * cur_cfqq - passed in so that we don't decide that the current queue is
1769 * closely cooperating with itself.
1770 *
1771 * So, basically we're assuming that that cur_cfqq has dispatched at least
1772 * one request, and that cfqd->last_position reflects a position on the disk
1773 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
1774 * assumption.
1775 */
1776 static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
1777 struct cfq_queue *cur_cfqq)
1778 {
1779 struct cfq_queue *cfqq;
1780
1781 if (cfq_class_idle(cur_cfqq))
1782 return NULL;
1783 if (!cfq_cfqq_sync(cur_cfqq))
1784 return NULL;
1785 if (CFQQ_SEEKY(cur_cfqq))
1786 return NULL;
1787
1788 /*
1789 * Don't search priority tree if it's the only queue in the group.
1790 */
1791 if (cur_cfqq->cfqg->nr_cfqq == 1)
1792 return NULL;
1793
1794 /*
1795 * We should notice if some of the queues are cooperating, eg
1796 * working closely on the same area of the disk. In that case,
1797 * we can group them together and don't waste time idling.
1798 */
1799 cfqq = cfqq_close(cfqd, cur_cfqq);
1800 if (!cfqq)
1801 return NULL;
1802
1803 /* If new queue belongs to different cfq_group, don't choose it */
1804 if (cur_cfqq->cfqg != cfqq->cfqg)
1805 return NULL;
1806
1807 /*
1808 * It only makes sense to merge sync queues.
1809 */
1810 if (!cfq_cfqq_sync(cfqq))
1811 return NULL;
1812 if (CFQQ_SEEKY(cfqq))
1813 return NULL;
1814
1815 /*
1816 * Do not merge queues of different priority classes
1817 */
1818 if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq))
1819 return NULL;
1820
1821 return cfqq;
1822 }
1823
1824 /*
1825 * Determine whether we should enforce idle window for this queue.
1826 */
1827
1828 static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1829 {
1830 enum wl_prio_t prio = cfqq_prio(cfqq);
1831 struct cfq_rb_root *service_tree = cfqq->service_tree;
1832
1833 BUG_ON(!service_tree);
1834 BUG_ON(!service_tree->count);
1835
1836 /* We never do for idle class queues. */
1837 if (prio == IDLE_WORKLOAD)
1838 return false;
1839
1840 /* We do for queues that were marked with idle window flag. */
1841 if (cfq_cfqq_idle_window(cfqq) &&
1842 !(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag))
1843 return true;
1844
1845 /*
1846 * Otherwise, we do only if they are the last ones
1847 * in their service tree.
1848 */
1849 if (service_tree->count == 1 && cfq_cfqq_sync(cfqq))
1850 return 1;
1851 cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d",
1852 service_tree->count);
1853 return 0;
1854 }
1855
1856 static void cfq_arm_slice_timer(struct cfq_data *cfqd)
1857 {
1858 struct cfq_queue *cfqq = cfqd->active_queue;
1859 struct cfq_io_context *cic;
1860 unsigned long sl;
1861
1862 /*
1863 * SSD device without seek penalty, disable idling. But only do so
1864 * for devices that support queuing, otherwise we still have a problem
1865 * with sync vs async workloads.
1866 */
1867 if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)
1868 return;
1869
1870 WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
1871 WARN_ON(cfq_cfqq_slice_new(cfqq));
1872
1873 /*
1874 * idle is disabled, either manually or by past process history
1875 */
1876 if (!cfqd->cfq_slice_idle || !cfq_should_idle(cfqd, cfqq))
1877 return;
1878
1879 /*
1880 * still active requests from this queue, don't idle
1881 */
1882 if (cfqq->dispatched)
1883 return;
1884
1885 /*
1886 * task has exited, don't wait
1887 */
1888 cic = cfqd->active_cic;
1889 if (!cic || !atomic_read(&cic->ioc->nr_tasks))
1890 return;
1891
1892 /*
1893 * If our average think time is larger than the remaining time
1894 * slice, then don't idle. This avoids overrunning the allotted
1895 * time slice.
1896 */
1897 if (sample_valid(cic->ttime_samples) &&
1898 (cfqq->slice_end - jiffies < cic->ttime_mean)) {
1899 cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%d",
1900 cic->ttime_mean);
1901 return;
1902 }
1903
1904 cfq_mark_cfqq_wait_request(cfqq);
1905
1906 sl = cfqd->cfq_slice_idle;
1907
1908 mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
1909 blkiocg_update_set_idle_time_stats(&cfqq->cfqg->blkg);
1910 cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu", sl);
1911 }
1912
1913 /*
1914 * Move request from internal lists to the request queue dispatch list.
1915 */
1916 static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
1917 {
1918 struct cfq_data *cfqd = q->elevator->elevator_data;
1919 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1920
1921 cfq_log_cfqq(cfqd, cfqq, "dispatch_insert");
1922
1923 cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq);
1924 cfq_remove_request(rq);
1925 cfqq->dispatched++;
1926 elv_dispatch_sort(q, rq);
1927
1928 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++;
1929 blkiocg_update_dispatch_stats(&cfqq->cfqg->blkg, blk_rq_bytes(rq),
1930 rq_data_dir(rq), rq_is_sync(rq));
1931 }
1932
1933 /*
1934 * return expired entry, or NULL to just start from scratch in rbtree
1935 */
1936 static struct request *cfq_check_fifo(struct cfq_queue *cfqq)
1937 {
1938 struct request *rq = NULL;
1939
1940 if (cfq_cfqq_fifo_expire(cfqq))
1941 return NULL;
1942
1943 cfq_mark_cfqq_fifo_expire(cfqq);
1944
1945 if (list_empty(&cfqq->fifo))
1946 return NULL;
1947
1948 rq = rq_entry_fifo(cfqq->fifo.next);
1949 if (time_before(jiffies, rq_fifo_time(rq)))
1950 rq = NULL;
1951
1952 cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq);
1953 return rq;
1954 }
1955
1956 static inline int
1957 cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1958 {
1959 const int base_rq = cfqd->cfq_slice_async_rq;
1960
1961 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
1962
1963 return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio));
1964 }
1965
1966 /*
1967 * Must be called with the queue_lock held.
1968 */
1969 static int cfqq_process_refs(struct cfq_queue *cfqq)
1970 {
1971 int process_refs, io_refs;
1972
1973 io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE];
1974 process_refs = atomic_read(&cfqq->ref) - io_refs;
1975 BUG_ON(process_refs < 0);
1976 return process_refs;
1977 }
1978
1979 static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq)
1980 {
1981 int process_refs, new_process_refs;
1982 struct cfq_queue *__cfqq;
1983
1984 /* Avoid a circular list and skip interim queue merges */
1985 while ((__cfqq = new_cfqq->new_cfqq)) {
1986 if (__cfqq == cfqq)
1987 return;
1988 new_cfqq = __cfqq;
1989 }
1990
1991 process_refs = cfqq_process_refs(cfqq);
1992 /*
1993 * If the process for the cfqq has gone away, there is no
1994 * sense in merging the queues.
1995 */
1996 if (process_refs == 0)
1997 return;
1998
1999 /*
2000 * Merge in the direction of the lesser amount of work.
2001 */
2002 new_process_refs = cfqq_process_refs(new_cfqq);
2003 if (new_process_refs >= process_refs) {
2004 cfqq->new_cfqq = new_cfqq;
2005 atomic_add(process_refs, &new_cfqq->ref);
2006 } else {
2007 new_cfqq->new_cfqq = cfqq;
2008 atomic_add(new_process_refs, &cfqq->ref);
2009 }
2010 }
2011
2012 static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd,
2013 struct cfq_group *cfqg, enum wl_prio_t prio)
2014 {
2015 struct cfq_queue *queue;
2016 int i;
2017 bool key_valid = false;
2018 unsigned long lowest_key = 0;
2019 enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD;
2020
2021 for (i = 0; i <= SYNC_WORKLOAD; ++i) {
2022 /* select the one with lowest rb_key */
2023 queue = cfq_rb_first(service_tree_for(cfqg, prio, i));
2024 if (queue &&
2025 (!key_valid || time_before(queue->rb_key, lowest_key))) {
2026 lowest_key = queue->rb_key;
2027 cur_best = i;
2028 key_valid = true;
2029 }
2030 }
2031
2032 return cur_best;
2033 }
2034
2035 static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg)
2036 {
2037 unsigned slice;
2038 unsigned count;
2039 struct cfq_rb_root *st;
2040 unsigned group_slice;
2041
2042 if (!cfqg) {
2043 cfqd->serving_prio = IDLE_WORKLOAD;
2044 cfqd->workload_expires = jiffies + 1;
2045 return;
2046 }
2047
2048 /* Choose next priority. RT > BE > IDLE */
2049 if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg))
2050 cfqd->serving_prio = RT_WORKLOAD;
2051 else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg))
2052 cfqd->serving_prio = BE_WORKLOAD;
2053 else {
2054 cfqd->serving_prio = IDLE_WORKLOAD;
2055 cfqd->workload_expires = jiffies + 1;
2056 return;
2057 }
2058
2059 /*
2060 * For RT and BE, we have to choose also the type
2061 * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload
2062 * expiration time
2063 */
2064 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type);
2065 count = st->count;
2066
2067 /*
2068 * check workload expiration, and that we still have other queues ready
2069 */
2070 if (count && !time_after(jiffies, cfqd->workload_expires))
2071 return;
2072
2073 /* otherwise select new workload type */
2074 cfqd->serving_type =
2075 cfq_choose_wl(cfqd, cfqg, cfqd->serving_prio);
2076 st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type);
2077 count = st->count;
2078
2079 /*
2080 * the workload slice is computed as a fraction of target latency
2081 * proportional to the number of queues in that workload, over
2082 * all the queues in the same priority class
2083 */
2084 group_slice = cfq_group_slice(cfqd, cfqg);
2085
2086 slice = group_slice * count /
2087 max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_prio],
2088 cfq_group_busy_queues_wl(cfqd->serving_prio, cfqd, cfqg));
2089
2090 if (cfqd->serving_type == ASYNC_WORKLOAD) {
2091 unsigned int tmp;
2092
2093 /*
2094 * Async queues are currently system wide. Just taking
2095 * proportion of queues with-in same group will lead to higher
2096 * async ratio system wide as generally root group is going
2097 * to have higher weight. A more accurate thing would be to
2098 * calculate system wide asnc/sync ratio.
2099 */
2100 tmp = cfq_target_latency * cfqg_busy_async_queues(cfqd, cfqg);
2101 tmp = tmp/cfqd->busy_queues;
2102 slice = min_t(unsigned, slice, tmp);
2103
2104 /* async workload slice is scaled down according to
2105 * the sync/async slice ratio. */
2106 slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1];
2107 } else
2108 /* sync workload slice is at least 2 * cfq_slice_idle */
2109 slice = max(slice, 2 * cfqd->cfq_slice_idle);
2110
2111 slice = max_t(unsigned, slice, CFQ_MIN_TT);
2112 cfq_log(cfqd, "workload slice:%d", slice);
2113 cfqd->workload_expires = jiffies + slice;
2114 cfqd->noidle_tree_requires_idle = false;
2115 }
2116
2117 static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd)
2118 {
2119 struct cfq_rb_root *st = &cfqd->grp_service_tree;
2120 struct cfq_group *cfqg;
2121
2122 if (RB_EMPTY_ROOT(&st->rb))
2123 return NULL;
2124 cfqg = cfq_rb_first_group(st);
2125 st->active = &cfqg->rb_node;
2126 update_min_vdisktime(st);
2127 return cfqg;
2128 }
2129
2130 static void cfq_choose_cfqg(struct cfq_data *cfqd)
2131 {
2132 struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd);
2133
2134 cfqd->serving_group = cfqg;
2135
2136 /* Restore the workload type data */
2137 if (cfqg->saved_workload_slice) {
2138 cfqd->workload_expires = jiffies + cfqg->saved_workload_slice;
2139 cfqd->serving_type = cfqg->saved_workload;
2140 cfqd->serving_prio = cfqg->saved_serving_prio;
2141 } else
2142 cfqd->workload_expires = jiffies - 1;
2143
2144 choose_service_tree(cfqd, cfqg);
2145 }
2146
2147 /*
2148 * Select a queue for service. If we have a current active queue,
2149 * check whether to continue servicing it, or retrieve and set a new one.
2150 */
2151 static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
2152 {
2153 struct cfq_queue *cfqq, *new_cfqq = NULL;
2154
2155 cfqq = cfqd->active_queue;
2156 if (!cfqq)
2157 goto new_queue;
2158
2159 if (!cfqd->rq_queued)
2160 return NULL;
2161
2162 /*
2163 * We were waiting for group to get backlogged. Expire the queue
2164 */
2165 if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list))
2166 goto expire;
2167
2168 /*
2169 * The active queue has run out of time, expire it and select new.
2170 */
2171 if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) {
2172 /*
2173 * If slice had not expired at the completion of last request
2174 * we might not have turned on wait_busy flag. Don't expire
2175 * the queue yet. Allow the group to get backlogged.
2176 *
2177 * The very fact that we have used the slice, that means we
2178 * have been idling all along on this queue and it should be
2179 * ok to wait for this request to complete.
2180 */
2181 if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list)
2182 && cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
2183 cfqq = NULL;
2184 goto keep_queue;
2185 } else
2186 goto expire;
2187 }
2188
2189 /*
2190 * The active queue has requests and isn't expired, allow it to
2191 * dispatch.
2192 */
2193 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
2194 goto keep_queue;
2195
2196 /*
2197 * If another queue has a request waiting within our mean seek
2198 * distance, let it run. The expire code will check for close
2199 * cooperators and put the close queue at the front of the service
2200 * tree. If possible, merge the expiring queue with the new cfqq.
2201 */
2202 new_cfqq = cfq_close_cooperator(cfqd, cfqq);
2203 if (new_cfqq) {
2204 if (!cfqq->new_cfqq)
2205 cfq_setup_merge(cfqq, new_cfqq);
2206 goto expire;
2207 }
2208
2209 /*
2210 * No requests pending. If the active queue still has requests in
2211 * flight or is idling for a new request, allow either of these
2212 * conditions to happen (or time out) before selecting a new queue.
2213 */
2214 if (timer_pending(&cfqd->idle_slice_timer) ||
2215 (cfqq->dispatched && cfq_should_idle(cfqd, cfqq))) {
2216 cfqq = NULL;
2217 goto keep_queue;
2218 }
2219
2220 expire:
2221 cfq_slice_expired(cfqd, 0);
2222 new_queue:
2223 /*
2224 * Current queue expired. Check if we have to switch to a new
2225 * service tree
2226 */
2227 if (!new_cfqq)
2228 cfq_choose_cfqg(cfqd);
2229
2230 cfqq = cfq_set_active_queue(cfqd, new_cfqq);
2231 keep_queue:
2232 return cfqq;
2233 }
2234
2235 static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq)
2236 {
2237 int dispatched = 0;
2238
2239 while (cfqq->next_rq) {
2240 cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq);
2241 dispatched++;
2242 }
2243
2244 BUG_ON(!list_empty(&cfqq->fifo));
2245
2246 /* By default cfqq is not expired if it is empty. Do it explicitly */
2247 __cfq_slice_expired(cfqq->cfqd, cfqq, 0);
2248 return dispatched;
2249 }
2250
2251 /*
2252 * Drain our current requests. Used for barriers and when switching
2253 * io schedulers on-the-fly.
2254 */
2255 static int cfq_forced_dispatch(struct cfq_data *cfqd)
2256 {
2257 struct cfq_queue *cfqq;
2258 int dispatched = 0;
2259
2260 /* Expire the timeslice of the current active queue first */
2261 cfq_slice_expired(cfqd, 0);
2262 while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) {
2263 __cfq_set_active_queue(cfqd, cfqq);
2264 dispatched += __cfq_forced_dispatch_cfqq(cfqq);
2265 }
2266
2267 BUG_ON(cfqd->busy_queues);
2268
2269 cfq_log(cfqd, "forced_dispatch=%d", dispatched);
2270 return dispatched;
2271 }
2272
2273 static inline bool cfq_slice_used_soon(struct cfq_data *cfqd,
2274 struct cfq_queue *cfqq)
2275 {
2276 /* the queue hasn't finished any request, can't estimate */
2277 if (cfq_cfqq_slice_new(cfqq))
2278 return 1;
2279 if (time_after(jiffies + cfqd->cfq_slice_idle * cfqq->dispatched,
2280 cfqq->slice_end))
2281 return 1;
2282
2283 return 0;
2284 }
2285
2286 static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2287 {
2288 unsigned int max_dispatch;
2289
2290 /*
2291 * Drain async requests before we start sync IO
2292 */
2293 if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC])
2294 return false;
2295
2296 /*
2297 * If this is an async queue and we have sync IO in flight, let it wait
2298 */
2299 if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq))
2300 return false;
2301
2302 max_dispatch = max_t(unsigned int, cfqd->cfq_quantum / 2, 1);
2303 if (cfq_class_idle(cfqq))
2304 max_dispatch = 1;
2305
2306 /*
2307 * Does this cfqq already have too much IO in flight?
2308 */
2309 if (cfqq->dispatched >= max_dispatch) {
2310 /*
2311 * idle queue must always only have a single IO in flight
2312 */
2313 if (cfq_class_idle(cfqq))
2314 return false;
2315
2316 /*
2317 * We have other queues, don't allow more IO from this one
2318 */
2319 if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq))
2320 return false;
2321
2322 /*
2323 * Sole queue user, no limit
2324 */
2325 if (cfqd->busy_queues == 1)
2326 max_dispatch = -1;
2327 else
2328 /*
2329 * Normally we start throttling cfqq when cfq_quantum/2
2330 * requests have been dispatched. But we can drive
2331 * deeper queue depths at the beginning of slice
2332 * subjected to upper limit of cfq_quantum.
2333 * */
2334 max_dispatch = cfqd->cfq_quantum;
2335 }
2336
2337 /*
2338 * Async queues must wait a bit before being allowed dispatch.
2339 * We also ramp up the dispatch depth gradually for async IO,
2340 * based on the last sync IO we serviced
2341 */
2342 if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) {
2343 unsigned long last_sync = jiffies - cfqd->last_delayed_sync;
2344 unsigned int depth;
2345
2346 depth = last_sync / cfqd->cfq_slice[1];
2347 if (!depth && !cfqq->dispatched)
2348 depth = 1;
2349 if (depth < max_dispatch)
2350 max_dispatch = depth;
2351 }
2352
2353 /*
2354 * If we're below the current max, allow a dispatch
2355 */
2356 return cfqq->dispatched < max_dispatch;
2357 }
2358
2359 /*
2360 * Dispatch a request from cfqq, moving them to the request queue
2361 * dispatch list.
2362 */
2363 static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2364 {
2365 struct request *rq;
2366
2367 BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list));
2368
2369 if (!cfq_may_dispatch(cfqd, cfqq))
2370 return false;
2371
2372 /*
2373 * follow expired path, else get first next available
2374 */
2375 rq = cfq_check_fifo(cfqq);
2376 if (!rq)
2377 rq = cfqq->next_rq;
2378
2379 /*
2380 * insert request into driver dispatch list
2381 */
2382 cfq_dispatch_insert(cfqd->queue, rq);
2383
2384 if (!cfqd->active_cic) {
2385 struct cfq_io_context *cic = RQ_CIC(rq);
2386
2387 atomic_long_inc(&cic->ioc->refcount);
2388 cfqd->active_cic = cic;
2389 }
2390
2391 return true;
2392 }
2393
2394 /*
2395 * Find the cfqq that we need to service and move a request from that to the
2396 * dispatch list
2397 */
2398 static int cfq_dispatch_requests(struct request_queue *q, int force)
2399 {
2400 struct cfq_data *cfqd = q->elevator->elevator_data;
2401 struct cfq_queue *cfqq;
2402
2403 if (!cfqd->busy_queues)
2404 return 0;
2405
2406 if (unlikely(force))
2407 return cfq_forced_dispatch(cfqd);
2408
2409 cfqq = cfq_select_queue(cfqd);
2410 if (!cfqq)
2411 return 0;
2412
2413 /*
2414 * Dispatch a request from this cfqq, if it is allowed
2415 */
2416 if (!cfq_dispatch_request(cfqd, cfqq))
2417 return 0;
2418
2419 cfqq->slice_dispatch++;
2420 cfq_clear_cfqq_must_dispatch(cfqq);
2421
2422 /*
2423 * expire an async queue immediately if it has used up its slice. idle
2424 * queue always expire after 1 dispatch round.
2425 */
2426 if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
2427 cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
2428 cfq_class_idle(cfqq))) {
2429 cfqq->slice_end = jiffies + 1;
2430 cfq_slice_expired(cfqd, 0);
2431 }
2432
2433 cfq_log_cfqq(cfqd, cfqq, "dispatched a request");
2434 return 1;
2435 }
2436
2437 /*
2438 * task holds one reference to the queue, dropped when task exits. each rq
2439 * in-flight on this queue also holds a reference, dropped when rq is freed.
2440 *
2441 * Each cfq queue took a reference on the parent group. Drop it now.
2442 * queue lock must be held here.
2443 */
2444 static void cfq_put_queue(struct cfq_queue *cfqq)
2445 {
2446 struct cfq_data *cfqd = cfqq->cfqd;
2447 struct cfq_group *cfqg, *orig_cfqg;
2448
2449 BUG_ON(atomic_read(&cfqq->ref) <= 0);
2450
2451 if (!atomic_dec_and_test(&cfqq->ref))
2452 return;
2453
2454 cfq_log_cfqq(cfqd, cfqq, "put_queue");
2455 BUG_ON(rb_first(&cfqq->sort_list));
2456 BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
2457 cfqg = cfqq->cfqg;
2458 orig_cfqg = cfqq->orig_cfqg;
2459
2460 if (unlikely(cfqd->active_queue == cfqq)) {
2461 __cfq_slice_expired(cfqd, cfqq, 0);
2462 cfq_schedule_dispatch(cfqd);
2463 }
2464
2465 BUG_ON(cfq_cfqq_on_rr(cfqq));
2466 kmem_cache_free(cfq_pool, cfqq);
2467 cfq_put_cfqg(cfqg);
2468 if (orig_cfqg)
2469 cfq_put_cfqg(orig_cfqg);
2470 }
2471
2472 /*
2473 * Must always be called with the rcu_read_lock() held
2474 */
2475 static void
2476 __call_for_each_cic(struct io_context *ioc,
2477 void (*func)(struct io_context *, struct cfq_io_context *))
2478 {
2479 struct cfq_io_context *cic;
2480 struct hlist_node *n;
2481
2482 hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list)
2483 func(ioc, cic);
2484 }
2485
2486 /*
2487 * Call func for each cic attached to this ioc.
2488 */
2489 static void
2490 call_for_each_cic(struct io_context *ioc,
2491 void (*func)(struct io_context *, struct cfq_io_context *))
2492 {
2493 rcu_read_lock();
2494 __call_for_each_cic(ioc, func);
2495 rcu_read_unlock();
2496 }
2497
2498 static void cfq_cic_free_rcu(struct rcu_head *head)
2499 {
2500 struct cfq_io_context *cic;
2501
2502 cic = container_of(head, struct cfq_io_context, rcu_head);
2503
2504 kmem_cache_free(cfq_ioc_pool, cic);
2505 elv_ioc_count_dec(cfq_ioc_count);
2506
2507 if (ioc_gone) {
2508 /*
2509 * CFQ scheduler is exiting, grab exit lock and check
2510 * the pending io context count. If it hits zero,
2511 * complete ioc_gone and set it back to NULL
2512 */
2513 spin_lock(&ioc_gone_lock);
2514 if (ioc_gone && !elv_ioc_count_read(cfq_ioc_count)) {
2515 complete(ioc_gone);
2516 ioc_gone = NULL;
2517 }
2518 spin_unlock(&ioc_gone_lock);
2519 }
2520 }
2521
2522 static void cfq_cic_free(struct cfq_io_context *cic)
2523 {
2524 call_rcu(&cic->rcu_head, cfq_cic_free_rcu);
2525 }
2526
2527 static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic)
2528 {
2529 unsigned long flags;
2530 unsigned long dead_key = (unsigned long) cic->key;
2531
2532 BUG_ON(!(dead_key & CIC_DEAD_KEY));
2533
2534 spin_lock_irqsave(&ioc->lock, flags);
2535 radix_tree_delete(&ioc->radix_root, dead_key & ~CIC_DEAD_KEY);
2536 hlist_del_rcu(&cic->cic_list);
2537 spin_unlock_irqrestore(&ioc->lock, flags);
2538
2539 cfq_cic_free(cic);
2540 }
2541
2542 /*
2543 * Must be called with rcu_read_lock() held or preemption otherwise disabled.
2544 * Only two callers of this - ->dtor() which is called with the rcu_read_lock(),
2545 * and ->trim() which is called with the task lock held
2546 */
2547 static void cfq_free_io_context(struct io_context *ioc)
2548 {
2549 /*
2550 * ioc->refcount is zero here, or we are called from elv_unregister(),
2551 * so no more cic's are allowed to be linked into this ioc. So it
2552 * should be ok to iterate over the known list, we will see all cic's
2553 * since no new ones are added.
2554 */
2555 __call_for_each_cic(ioc, cic_free_func);
2556 }
2557
2558 static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2559 {
2560 struct cfq_queue *__cfqq, *next;
2561
2562 if (unlikely(cfqq == cfqd->active_queue)) {
2563 __cfq_slice_expired(cfqd, cfqq, 0);
2564 cfq_schedule_dispatch(cfqd);
2565 }
2566
2567 /*
2568 * If this queue was scheduled to merge with another queue, be
2569 * sure to drop the reference taken on that queue (and others in
2570 * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs.
2571 */
2572 __cfqq = cfqq->new_cfqq;
2573 while (__cfqq) {
2574 if (__cfqq == cfqq) {
2575 WARN(1, "cfqq->new_cfqq loop detected\n");
2576 break;
2577 }
2578 next = __cfqq->new_cfqq;
2579 cfq_put_queue(__cfqq);
2580 __cfqq = next;
2581 }
2582
2583 cfq_put_queue(cfqq);
2584 }
2585
2586 static void __cfq_exit_single_io_context(struct cfq_data *cfqd,
2587 struct cfq_io_context *cic)
2588 {
2589 struct io_context *ioc = cic->ioc;
2590
2591 list_del_init(&cic->queue_list);
2592
2593 /*
2594 * Make sure dead mark is seen for dead queues
2595 */
2596 smp_wmb();
2597 cic->key = cfqd_dead_key(cfqd);
2598
2599 if (ioc->ioc_data == cic)
2600 rcu_assign_pointer(ioc->ioc_data, NULL);
2601
2602 if (cic->cfqq[BLK_RW_ASYNC]) {
2603 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]);
2604 cic->cfqq[BLK_RW_ASYNC] = NULL;
2605 }
2606
2607 if (cic->cfqq[BLK_RW_SYNC]) {
2608 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]);
2609 cic->cfqq[BLK_RW_SYNC] = NULL;
2610 }
2611 }
2612
2613 static void cfq_exit_single_io_context(struct io_context *ioc,
2614 struct cfq_io_context *cic)
2615 {
2616 struct cfq_data *cfqd = cic_to_cfqd(cic);
2617
2618 if (cfqd) {
2619 struct request_queue *q = cfqd->queue;
2620 unsigned long flags;
2621
2622 spin_lock_irqsave(q->queue_lock, flags);
2623
2624 /*
2625 * Ensure we get a fresh copy of the ->key to prevent
2626 * race between exiting task and queue
2627 */
2628 smp_read_barrier_depends();
2629 if (cic->key == cfqd)
2630 __cfq_exit_single_io_context(cfqd, cic);
2631
2632 spin_unlock_irqrestore(q->queue_lock, flags);
2633 }
2634 }
2635
2636 /*
2637 * The process that ioc belongs to has exited, we need to clean up
2638 * and put the internal structures we have that belongs to that process.
2639 */
2640 static void cfq_exit_io_context(struct io_context *ioc)
2641 {
2642 call_for_each_cic(ioc, cfq_exit_single_io_context);
2643 }
2644
2645 static struct cfq_io_context *
2646 cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
2647 {
2648 struct cfq_io_context *cic;
2649
2650 cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask | __GFP_ZERO,
2651 cfqd->queue->node);
2652 if (cic) {
2653 cic->last_end_request = jiffies;
2654 INIT_LIST_HEAD(&cic->queue_list);
2655 INIT_HLIST_NODE(&cic->cic_list);
2656 cic->dtor = cfq_free_io_context;
2657 cic->exit = cfq_exit_io_context;
2658 elv_ioc_count_inc(cfq_ioc_count);
2659 }
2660
2661 return cic;
2662 }
2663
2664 static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc)
2665 {
2666 struct task_struct *tsk = current;
2667 int ioprio_class;
2668
2669 if (!cfq_cfqq_prio_changed(cfqq))
2670 return;
2671
2672 ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio);
2673 switch (ioprio_class) {
2674 default:
2675 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
2676 case IOPRIO_CLASS_NONE:
2677 /*
2678 * no prio set, inherit CPU scheduling settings
2679 */
2680 cfqq->ioprio = task_nice_ioprio(tsk);
2681 cfqq->ioprio_class = task_nice_ioclass(tsk);
2682 break;
2683 case IOPRIO_CLASS_RT:
2684 cfqq->ioprio = task_ioprio(ioc);
2685 cfqq->ioprio_class = IOPRIO_CLASS_RT;
2686 break;
2687 case IOPRIO_CLASS_BE:
2688 cfqq->ioprio = task_ioprio(ioc);
2689 cfqq->ioprio_class = IOPRIO_CLASS_BE;
2690 break;
2691 case IOPRIO_CLASS_IDLE:
2692 cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
2693 cfqq->ioprio = 7;
2694 cfq_clear_cfqq_idle_window(cfqq);
2695 break;
2696 }
2697
2698 /*
2699 * keep track of original prio settings in case we have to temporarily
2700 * elevate the priority of this queue
2701 */
2702 cfqq->org_ioprio = cfqq->ioprio;
2703 cfqq->org_ioprio_class = cfqq->ioprio_class;
2704 cfq_clear_cfqq_prio_changed(cfqq);
2705 }
2706
2707 static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic)
2708 {
2709 struct cfq_data *cfqd = cic_to_cfqd(cic);
2710 struct cfq_queue *cfqq;
2711 unsigned long flags;
2712
2713 if (unlikely(!cfqd))
2714 return;
2715
2716 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
2717
2718 cfqq = cic->cfqq[BLK_RW_ASYNC];
2719 if (cfqq) {
2720 struct cfq_queue *new_cfqq;
2721 new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->ioc,
2722 GFP_ATOMIC);
2723 if (new_cfqq) {
2724 cic->cfqq[BLK_RW_ASYNC] = new_cfqq;
2725 cfq_put_queue(cfqq);
2726 }
2727 }
2728
2729 cfqq = cic->cfqq[BLK_RW_SYNC];
2730 if (cfqq)
2731 cfq_mark_cfqq_prio_changed(cfqq);
2732
2733 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
2734 }
2735
2736 static void cfq_ioc_set_ioprio(struct io_context *ioc)
2737 {
2738 call_for_each_cic(ioc, changed_ioprio);
2739 ioc->ioprio_changed = 0;
2740 }
2741
2742 static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2743 pid_t pid, bool is_sync)
2744 {
2745 RB_CLEAR_NODE(&cfqq->rb_node);
2746 RB_CLEAR_NODE(&cfqq->p_node);
2747 INIT_LIST_HEAD(&cfqq->fifo);
2748
2749 atomic_set(&cfqq->ref, 0);
2750 cfqq->cfqd = cfqd;
2751
2752 cfq_mark_cfqq_prio_changed(cfqq);
2753
2754 if (is_sync) {
2755 if (!cfq_class_idle(cfqq))
2756 cfq_mark_cfqq_idle_window(cfqq);
2757 cfq_mark_cfqq_sync(cfqq);
2758 }
2759 cfqq->pid = pid;
2760 }
2761
2762 #ifdef CONFIG_CFQ_GROUP_IOSCHED
2763 static void changed_cgroup(struct io_context *ioc, struct cfq_io_context *cic)
2764 {
2765 struct cfq_queue *sync_cfqq = cic_to_cfqq(cic, 1);
2766 struct cfq_data *cfqd = cic_to_cfqd(cic);
2767 unsigned long flags;
2768 struct request_queue *q;
2769
2770 if (unlikely(!cfqd))
2771 return;
2772
2773 q = cfqd->queue;
2774
2775 spin_lock_irqsave(q->queue_lock, flags);
2776
2777 if (sync_cfqq) {
2778 /*
2779 * Drop reference to sync queue. A new sync queue will be
2780 * assigned in new group upon arrival of a fresh request.
2781 */
2782 cfq_log_cfqq(cfqd, sync_cfqq, "changed cgroup");
2783 cic_set_cfqq(cic, NULL, 1);
2784 cfq_put_queue(sync_cfqq);
2785 }
2786
2787 spin_unlock_irqrestore(q->queue_lock, flags);
2788 }
2789
2790 static void cfq_ioc_set_cgroup(struct io_context *ioc)
2791 {
2792 call_for_each_cic(ioc, changed_cgroup);
2793 ioc->cgroup_changed = 0;
2794 }
2795 #endif /* CONFIG_CFQ_GROUP_IOSCHED */
2796
2797 static struct cfq_queue *
2798 cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync,
2799 struct io_context *ioc, gfp_t gfp_mask)
2800 {
2801 struct cfq_queue *cfqq, *new_cfqq = NULL;
2802 struct cfq_io_context *cic;
2803 struct cfq_group *cfqg;
2804
2805 retry:
2806 cfqg = cfq_get_cfqg(cfqd, 1);
2807 cic = cfq_cic_lookup(cfqd, ioc);
2808 /* cic always exists here */
2809 cfqq = cic_to_cfqq(cic, is_sync);
2810
2811 /*
2812 * Always try a new alloc if we fell back to the OOM cfqq
2813 * originally, since it should just be a temporary situation.
2814 */
2815 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
2816 cfqq = NULL;
2817 if (new_cfqq) {
2818 cfqq = new_cfqq;
2819 new_cfqq = NULL;
2820 } else if (gfp_mask & __GFP_WAIT) {
2821 spin_unlock_irq(cfqd->queue->queue_lock);
2822 new_cfqq = kmem_cache_alloc_node(cfq_pool,
2823 gfp_mask | __GFP_ZERO,
2824 cfqd->queue->node);
2825 spin_lock_irq(cfqd->queue->queue_lock);
2826 if (new_cfqq)
2827 goto retry;
2828 } else {
2829 cfqq = kmem_cache_alloc_node(cfq_pool,
2830 gfp_mask | __GFP_ZERO,
2831 cfqd->queue->node);
2832 }
2833
2834 if (cfqq) {
2835 cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
2836 cfq_init_prio_data(cfqq, ioc);
2837 cfq_link_cfqq_cfqg(cfqq, cfqg);
2838 cfq_log_cfqq(cfqd, cfqq, "alloced");
2839 } else
2840 cfqq = &cfqd->oom_cfqq;
2841 }
2842
2843 if (new_cfqq)
2844 kmem_cache_free(cfq_pool, new_cfqq);
2845
2846 return cfqq;
2847 }
2848
2849 static struct cfq_queue **
2850 cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio)
2851 {
2852 switch (ioprio_class) {
2853 case IOPRIO_CLASS_RT:
2854 return &cfqd->async_cfqq[0][ioprio];
2855 case IOPRIO_CLASS_BE:
2856 return &cfqd->async_cfqq[1][ioprio];
2857 case IOPRIO_CLASS_IDLE:
2858 return &cfqd->async_idle_cfqq;
2859 default:
2860 BUG();
2861 }
2862 }
2863
2864 static struct cfq_queue *
2865 cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct io_context *ioc,
2866 gfp_t gfp_mask)
2867 {
2868 const int ioprio = task_ioprio(ioc);
2869 const int ioprio_class = task_ioprio_class(ioc);
2870 struct cfq_queue **async_cfqq = NULL;
2871 struct cfq_queue *cfqq = NULL;
2872
2873 if (!is_sync) {
2874 async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio);
2875 cfqq = *async_cfqq;
2876 }
2877
2878 if (!cfqq)
2879 cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask);
2880
2881 /*
2882 * pin the queue now that it's allocated, scheduler exit will prune it
2883 */
2884 if (!is_sync && !(*async_cfqq)) {
2885 atomic_inc(&cfqq->ref);
2886 *async_cfqq = cfqq;
2887 }
2888
2889 atomic_inc(&cfqq->ref);
2890 return cfqq;
2891 }
2892
2893 /*
2894 * We drop cfq io contexts lazily, so we may find a dead one.
2895 */
2896 static void
2897 cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc,
2898 struct cfq_io_context *cic)
2899 {
2900 unsigned long flags;
2901
2902 WARN_ON(!list_empty(&cic->queue_list));
2903 BUG_ON(cic->key != cfqd_dead_key(cfqd));
2904
2905 spin_lock_irqsave(&ioc->lock, flags);
2906
2907 BUG_ON(ioc->ioc_data == cic);
2908
2909 radix_tree_delete(&ioc->radix_root, (unsigned long) cfqd);
2910 hlist_del_rcu(&cic->cic_list);
2911 spin_unlock_irqrestore(&ioc->lock, flags);
2912
2913 cfq_cic_free(cic);
2914 }
2915
2916 static struct cfq_io_context *
2917 cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc)
2918 {
2919 struct cfq_io_context *cic;
2920 unsigned long flags;
2921
2922 if (unlikely(!ioc))
2923 return NULL;
2924
2925 rcu_read_lock();
2926
2927 /*
2928 * we maintain a last-hit cache, to avoid browsing over the tree
2929 */
2930 cic = rcu_dereference(ioc->ioc_data);
2931 if (cic && cic->key == cfqd) {
2932 rcu_read_unlock();
2933 return cic;
2934 }
2935
2936 do {
2937 cic = radix_tree_lookup(&ioc->radix_root, (unsigned long) cfqd);
2938 rcu_read_unlock();
2939 if (!cic)
2940 break;
2941 if (unlikely(cic->key != cfqd)) {
2942 cfq_drop_dead_cic(cfqd, ioc, cic);
2943 rcu_read_lock();
2944 continue;
2945 }
2946
2947 spin_lock_irqsave(&ioc->lock, flags);
2948 rcu_assign_pointer(ioc->ioc_data, cic);
2949 spin_unlock_irqrestore(&ioc->lock, flags);
2950 break;
2951 } while (1);
2952
2953 return cic;
2954 }
2955
2956 /*
2957 * Add cic into ioc, using cfqd as the search key. This enables us to lookup
2958 * the process specific cfq io context when entered from the block layer.
2959 * Also adds the cic to a per-cfqd list, used when this queue is removed.
2960 */
2961 static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc,
2962 struct cfq_io_context *cic, gfp_t gfp_mask)
2963 {
2964 unsigned long flags;
2965 int ret;
2966
2967 ret = radix_tree_preload(gfp_mask);
2968 if (!ret) {
2969 cic->ioc = ioc;
2970 cic->key = cfqd;
2971
2972 spin_lock_irqsave(&ioc->lock, flags);
2973 ret = radix_tree_insert(&ioc->radix_root,
2974 (unsigned long) cfqd, cic);
2975 if (!ret)
2976 hlist_add_head_rcu(&cic->cic_list, &ioc->cic_list);
2977 spin_unlock_irqrestore(&ioc->lock, flags);
2978
2979 radix_tree_preload_end();
2980
2981 if (!ret) {
2982 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
2983 list_add(&cic->queue_list, &cfqd->cic_list);
2984 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
2985 }
2986 }
2987
2988 if (ret)
2989 printk(KERN_ERR "cfq: cic link failed!\n");
2990
2991 return ret;
2992 }
2993
2994 /*
2995 * Setup general io context and cfq io context. There can be several cfq
2996 * io contexts per general io context, if this process is doing io to more
2997 * than one device managed by cfq.
2998 */
2999 static struct cfq_io_context *
3000 cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
3001 {
3002 struct io_context *ioc = NULL;
3003 struct cfq_io_context *cic;
3004
3005 might_sleep_if(gfp_mask & __GFP_WAIT);
3006
3007 ioc = get_io_context(gfp_mask, cfqd->queue->node);
3008 if (!ioc)
3009 return NULL;
3010
3011 cic = cfq_cic_lookup(cfqd, ioc);
3012 if (cic)
3013 goto out;
3014
3015 cic = cfq_alloc_io_context(cfqd, gfp_mask);
3016 if (cic == NULL)
3017 goto err;
3018
3019 if (cfq_cic_link(cfqd, ioc, cic, gfp_mask))
3020 goto err_free;
3021
3022 out:
3023 smp_read_barrier_depends();
3024 if (unlikely(ioc->ioprio_changed))
3025 cfq_ioc_set_ioprio(ioc);
3026
3027 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3028 if (unlikely(ioc->cgroup_changed))
3029 cfq_ioc_set_cgroup(ioc);
3030 #endif
3031 return cic;
3032 err_free:
3033 cfq_cic_free(cic);
3034 err:
3035 put_io_context(ioc);
3036 return NULL;
3037 }
3038
3039 static void
3040 cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic)
3041 {
3042 unsigned long elapsed = jiffies - cic->last_end_request;
3043 unsigned long ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle);
3044
3045 cic->ttime_samples = (7*cic->ttime_samples + 256) / 8;
3046 cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8;
3047 cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples;
3048 }
3049
3050 static void
3051 cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3052 struct request *rq)
3053 {
3054 sector_t sdist = 0;
3055 sector_t n_sec = blk_rq_sectors(rq);
3056 if (cfqq->last_request_pos) {
3057 if (cfqq->last_request_pos < blk_rq_pos(rq))
3058 sdist = blk_rq_pos(rq) - cfqq->last_request_pos;
3059 else
3060 sdist = cfqq->last_request_pos - blk_rq_pos(rq);
3061 }
3062
3063 cfqq->seek_history <<= 1;
3064 if (blk_queue_nonrot(cfqd->queue))
3065 cfqq->seek_history |= (n_sec < CFQQ_SECT_THR_NONROT);
3066 else
3067 cfqq->seek_history |= (sdist > CFQQ_SEEK_THR);
3068 }
3069
3070 /*
3071 * Disable idle window if the process thinks too long or seeks so much that
3072 * it doesn't matter
3073 */
3074 static void
3075 cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3076 struct cfq_io_context *cic)
3077 {
3078 int old_idle, enable_idle;
3079
3080 /*
3081 * Don't idle for async or idle io prio class
3082 */
3083 if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq))
3084 return;
3085
3086 enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
3087
3088 if (cfqq->queued[0] + cfqq->queued[1] >= 4)
3089 cfq_mark_cfqq_deep(cfqq);
3090
3091 if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle ||
3092 (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq)))
3093 enable_idle = 0;
3094 else if (sample_valid(cic->ttime_samples)) {
3095 if (cic->ttime_mean > cfqd->cfq_slice_idle)
3096 enable_idle = 0;
3097 else
3098 enable_idle = 1;
3099 }
3100
3101 if (old_idle != enable_idle) {
3102 cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle);
3103 if (enable_idle)
3104 cfq_mark_cfqq_idle_window(cfqq);
3105 else
3106 cfq_clear_cfqq_idle_window(cfqq);
3107 }
3108 }
3109
3110 /*
3111 * Check if new_cfqq should preempt the currently active queue. Return 0 for
3112 * no or if we aren't sure, a 1 will cause a preempt.
3113 */
3114 static bool
3115 cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
3116 struct request *rq)
3117 {
3118 struct cfq_queue *cfqq;
3119
3120 cfqq = cfqd->active_queue;
3121 if (!cfqq)
3122 return false;
3123
3124 if (cfq_class_idle(new_cfqq))
3125 return false;
3126
3127 if (cfq_class_idle(cfqq))
3128 return true;
3129
3130 /*
3131 * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice.
3132 */
3133 if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq))
3134 return false;
3135
3136 /*
3137 * if the new request is sync, but the currently running queue is
3138 * not, let the sync request have priority.
3139 */
3140 if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq))
3141 return true;
3142
3143 if (new_cfqq->cfqg != cfqq->cfqg)
3144 return false;
3145
3146 if (cfq_slice_used(cfqq))
3147 return true;
3148
3149 /* Allow preemption only if we are idling on sync-noidle tree */
3150 if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD &&
3151 cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD &&
3152 new_cfqq->service_tree->count == 2 &&
3153 RB_EMPTY_ROOT(&cfqq->sort_list))
3154 return true;
3155
3156 /*
3157 * So both queues are sync. Let the new request get disk time if
3158 * it's a metadata request and the current queue is doing regular IO.
3159 */
3160 if (rq_is_meta(rq) && !cfqq->meta_pending)
3161 return true;
3162
3163 /*
3164 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
3165 */
3166 if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
3167 return true;
3168
3169 if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq))
3170 return false;
3171
3172 /*
3173 * if this request is as-good as one we would expect from the
3174 * current cfqq, let it preempt
3175 */
3176 if (cfq_rq_close(cfqd, cfqq, rq))
3177 return true;
3178
3179 return false;
3180 }
3181
3182 /*
3183 * cfqq preempts the active queue. if we allowed preempt with no slice left,
3184 * let it have half of its nominal slice.
3185 */
3186 static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3187 {
3188 cfq_log_cfqq(cfqd, cfqq, "preempt");
3189 cfq_slice_expired(cfqd, 1);
3190
3191 /*
3192 * Put the new queue at the front of the of the current list,
3193 * so we know that it will be selected next.
3194 */
3195 BUG_ON(!cfq_cfqq_on_rr(cfqq));
3196
3197 cfq_service_tree_add(cfqd, cfqq, 1);
3198
3199 cfqq->slice_end = 0;
3200 cfq_mark_cfqq_slice_new(cfqq);
3201 }
3202
3203 /*
3204 * Called when a new fs request (rq) is added (to cfqq). Check if there's
3205 * something we should do about it
3206 */
3207 static void
3208 cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
3209 struct request *rq)
3210 {
3211 struct cfq_io_context *cic = RQ_CIC(rq);
3212
3213 cfqd->rq_queued++;
3214 if (rq_is_meta(rq))
3215 cfqq->meta_pending++;
3216
3217 cfq_update_io_thinktime(cfqd, cic);
3218 cfq_update_io_seektime(cfqd, cfqq, rq);
3219 cfq_update_idle_window(cfqd, cfqq, cic);
3220
3221 cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
3222
3223 if (cfqq == cfqd->active_queue) {
3224 /*
3225 * Remember that we saw a request from this process, but
3226 * don't start queuing just yet. Otherwise we risk seeing lots
3227 * of tiny requests, because we disrupt the normal plugging
3228 * and merging. If the request is already larger than a single
3229 * page, let it rip immediately. For that case we assume that
3230 * merging is already done. Ditto for a busy system that
3231 * has other work pending, don't risk delaying until the
3232 * idle timer unplug to continue working.
3233 */
3234 if (cfq_cfqq_wait_request(cfqq)) {
3235 if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE ||
3236 cfqd->busy_queues > 1) {
3237 cfq_del_timer(cfqd, cfqq);
3238 cfq_clear_cfqq_wait_request(cfqq);
3239 __blk_run_queue(cfqd->queue);
3240 } else {
3241 blkiocg_update_idle_time_stats(
3242 &cfqq->cfqg->blkg);
3243 cfq_mark_cfqq_must_dispatch(cfqq);
3244 }
3245 }
3246 } else if (cfq_should_preempt(cfqd, cfqq, rq)) {
3247 /*
3248 * not the active queue - expire current slice if it is
3249 * idle and has expired it's mean thinktime or this new queue
3250 * has some old slice time left and is of higher priority or
3251 * this new queue is RT and the current one is BE
3252 */
3253 cfq_preempt_queue(cfqd, cfqq);
3254 __blk_run_queue(cfqd->queue);
3255 }
3256 }
3257
3258 static void cfq_insert_request(struct request_queue *q, struct request *rq)
3259 {
3260 struct cfq_data *cfqd = q->elevator->elevator_data;
3261 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3262
3263 cfq_log_cfqq(cfqd, cfqq, "insert_request");
3264 cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc);
3265
3266 rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]);
3267 list_add_tail(&rq->queuelist, &cfqq->fifo);
3268 cfq_add_rq_rb(rq);
3269 blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg,
3270 &cfqd->serving_group->blkg, rq_data_dir(rq),
3271 rq_is_sync(rq));
3272 cfq_rq_enqueued(cfqd, cfqq, rq);
3273 }
3274
3275 /*
3276 * Update hw_tag based on peak queue depth over 50 samples under
3277 * sufficient load.
3278 */
3279 static void cfq_update_hw_tag(struct cfq_data *cfqd)
3280 {
3281 struct cfq_queue *cfqq = cfqd->active_queue;
3282
3283 if (cfqd->rq_in_driver > cfqd->hw_tag_est_depth)
3284 cfqd->hw_tag_est_depth = cfqd->rq_in_driver;
3285
3286 if (cfqd->hw_tag == 1)
3287 return;
3288
3289 if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
3290 cfqd->rq_in_driver <= CFQ_HW_QUEUE_MIN)
3291 return;
3292
3293 /*
3294 * If active queue hasn't enough requests and can idle, cfq might not
3295 * dispatch sufficient requests to hardware. Don't zero hw_tag in this
3296 * case
3297 */
3298 if (cfqq && cfq_cfqq_idle_window(cfqq) &&
3299 cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] <
3300 CFQ_HW_QUEUE_MIN && cfqd->rq_in_driver < CFQ_HW_QUEUE_MIN)
3301 return;
3302
3303 if (cfqd->hw_tag_samples++ < 50)
3304 return;
3305
3306 if (cfqd->hw_tag_est_depth >= CFQ_HW_QUEUE_MIN)
3307 cfqd->hw_tag = 1;
3308 else
3309 cfqd->hw_tag = 0;
3310 }
3311
3312 static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq)
3313 {
3314 struct cfq_io_context *cic = cfqd->active_cic;
3315
3316 /* If there are other queues in the group, don't wait */
3317 if (cfqq->cfqg->nr_cfqq > 1)
3318 return false;
3319
3320 if (cfq_slice_used(cfqq))
3321 return true;
3322
3323 /* if slice left is less than think time, wait busy */
3324 if (cic && sample_valid(cic->ttime_samples)
3325 && (cfqq->slice_end - jiffies < cic->ttime_mean))
3326 return true;
3327
3328 /*
3329 * If think times is less than a jiffy than ttime_mean=0 and above
3330 * will not be true. It might happen that slice has not expired yet
3331 * but will expire soon (4-5 ns) during select_queue(). To cover the
3332 * case where think time is less than a jiffy, mark the queue wait
3333 * busy if only 1 jiffy is left in the slice.
3334 */
3335 if (cfqq->slice_end - jiffies == 1)
3336 return true;
3337
3338 return false;
3339 }
3340
3341 static void cfq_completed_request(struct request_queue *q, struct request *rq)
3342 {
3343 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3344 struct cfq_data *cfqd = cfqq->cfqd;
3345 const int sync = rq_is_sync(rq);
3346 unsigned long now;
3347
3348 now = jiffies;
3349 cfq_log_cfqq(cfqd, cfqq, "complete rqnoidle %d", !!rq_noidle(rq));
3350
3351 cfq_update_hw_tag(cfqd);
3352
3353 WARN_ON(!cfqd->rq_in_driver);
3354 WARN_ON(!cfqq->dispatched);
3355 cfqd->rq_in_driver--;
3356 cfqq->dispatched--;
3357 blkiocg_update_completion_stats(&cfqq->cfqg->blkg, rq_start_time_ns(rq),
3358 rq_io_start_time_ns(rq), rq_data_dir(rq),
3359 rq_is_sync(rq));
3360
3361 cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--;
3362
3363 if (sync) {
3364 RQ_CIC(rq)->last_end_request = now;
3365 if (!time_after(rq->start_time + cfqd->cfq_fifo_expire[1], now))
3366 cfqd->last_delayed_sync = now;
3367 }
3368
3369 /*
3370 * If this is the active queue, check if it needs to be expired,
3371 * or if we want to idle in case it has no pending requests.
3372 */
3373 if (cfqd->active_queue == cfqq) {
3374 const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list);
3375
3376 if (cfq_cfqq_slice_new(cfqq)) {
3377 cfq_set_prio_slice(cfqd, cfqq);
3378 cfq_clear_cfqq_slice_new(cfqq);
3379 }
3380
3381 /*
3382 * Should we wait for next request to come in before we expire
3383 * the queue.
3384 */
3385 if (cfq_should_wait_busy(cfqd, cfqq)) {
3386 cfqq->slice_end = jiffies + cfqd->cfq_slice_idle;
3387 cfq_mark_cfqq_wait_busy(cfqq);
3388 cfq_log_cfqq(cfqd, cfqq, "will busy wait");
3389 }
3390
3391 /*
3392 * Idling is not enabled on:
3393 * - expired queues
3394 * - idle-priority queues
3395 * - async queues
3396 * - queues with still some requests queued
3397 * - when there is a close cooperator
3398 */
3399 if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq))
3400 cfq_slice_expired(cfqd, 1);
3401 else if (sync && cfqq_empty &&
3402 !cfq_close_cooperator(cfqd, cfqq)) {
3403 cfqd->noidle_tree_requires_idle |= !rq_noidle(rq);
3404 /*
3405 * Idling is enabled for SYNC_WORKLOAD.
3406 * SYNC_NOIDLE_WORKLOAD idles at the end of the tree
3407 * only if we processed at least one !rq_noidle request
3408 */
3409 if (cfqd->serving_type == SYNC_WORKLOAD
3410 || cfqd->noidle_tree_requires_idle
3411 || cfqq->cfqg->nr_cfqq == 1)
3412 cfq_arm_slice_timer(cfqd);
3413 }
3414 }
3415
3416 if (!cfqd->rq_in_driver)
3417 cfq_schedule_dispatch(cfqd);
3418 }
3419
3420 /*
3421 * we temporarily boost lower priority queues if they are holding fs exclusive
3422 * resources. they are boosted to normal prio (CLASS_BE/4)
3423 */
3424 static void cfq_prio_boost(struct cfq_queue *cfqq)
3425 {
3426 if (has_fs_excl()) {
3427 /*
3428 * boost idle prio on transactions that would lock out other
3429 * users of the filesystem
3430 */
3431 if (cfq_class_idle(cfqq))
3432 cfqq->ioprio_class = IOPRIO_CLASS_BE;
3433 if (cfqq->ioprio > IOPRIO_NORM)
3434 cfqq->ioprio = IOPRIO_NORM;
3435 } else {
3436 /*
3437 * unboost the queue (if needed)
3438 */
3439 cfqq->ioprio_class = cfqq->org_ioprio_class;
3440 cfqq->ioprio = cfqq->org_ioprio;
3441 }
3442 }
3443
3444 static inline int __cfq_may_queue(struct cfq_queue *cfqq)
3445 {
3446 if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) {
3447 cfq_mark_cfqq_must_alloc_slice(cfqq);
3448 return ELV_MQUEUE_MUST;
3449 }
3450
3451 return ELV_MQUEUE_MAY;
3452 }
3453
3454 static int cfq_may_queue(struct request_queue *q, int rw)
3455 {
3456 struct cfq_data *cfqd = q->elevator->elevator_data;
3457 struct task_struct *tsk = current;
3458 struct cfq_io_context *cic;
3459 struct cfq_queue *cfqq;
3460
3461 /*
3462 * don't force setup of a queue from here, as a call to may_queue
3463 * does not necessarily imply that a request actually will be queued.
3464 * so just lookup a possibly existing queue, or return 'may queue'
3465 * if that fails
3466 */
3467 cic = cfq_cic_lookup(cfqd, tsk->io_context);
3468 if (!cic)
3469 return ELV_MQUEUE_MAY;
3470
3471 cfqq = cic_to_cfqq(cic, rw_is_sync(rw));
3472 if (cfqq) {
3473 cfq_init_prio_data(cfqq, cic->ioc);
3474 cfq_prio_boost(cfqq);
3475
3476 return __cfq_may_queue(cfqq);
3477 }
3478
3479 return ELV_MQUEUE_MAY;
3480 }
3481
3482 /*
3483 * queue lock held here
3484 */
3485 static void cfq_put_request(struct request *rq)
3486 {
3487 struct cfq_queue *cfqq = RQ_CFQQ(rq);
3488
3489 if (cfqq) {
3490 const int rw = rq_data_dir(rq);
3491
3492 BUG_ON(!cfqq->allocated[rw]);
3493 cfqq->allocated[rw]--;
3494
3495 put_io_context(RQ_CIC(rq)->ioc);
3496
3497 rq->elevator_private = NULL;
3498 rq->elevator_private2 = NULL;
3499
3500 /* Put down rq reference on cfqg */
3501 cfq_put_cfqg(RQ_CFQG(rq));
3502 rq->elevator_private3 = NULL;
3503
3504 cfq_put_queue(cfqq);
3505 }
3506 }
3507
3508 static struct cfq_queue *
3509 cfq_merge_cfqqs(struct cfq_data *cfqd, struct cfq_io_context *cic,
3510 struct cfq_queue *cfqq)
3511 {
3512 cfq_log_cfqq(cfqd, cfqq, "merging with queue %p", cfqq->new_cfqq);
3513 cic_set_cfqq(cic, cfqq->new_cfqq, 1);
3514 cfq_mark_cfqq_coop(cfqq->new_cfqq);
3515 cfq_put_queue(cfqq);
3516 return cic_to_cfqq(cic, 1);
3517 }
3518
3519 /*
3520 * Returns NULL if a new cfqq should be allocated, or the old cfqq if this
3521 * was the last process referring to said cfqq.
3522 */
3523 static struct cfq_queue *
3524 split_cfqq(struct cfq_io_context *cic, struct cfq_queue *cfqq)
3525 {
3526 if (cfqq_process_refs(cfqq) == 1) {
3527 cfqq->pid = current->pid;
3528 cfq_clear_cfqq_coop(cfqq);
3529 cfq_clear_cfqq_split_coop(cfqq);
3530 return cfqq;
3531 }
3532
3533 cic_set_cfqq(cic, NULL, 1);
3534 cfq_put_queue(cfqq);
3535 return NULL;
3536 }
3537 /*
3538 * Allocate cfq data structures associated with this request.
3539 */
3540 static int
3541 cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask)
3542 {
3543 struct cfq_data *cfqd = q->elevator->elevator_data;
3544 struct cfq_io_context *cic;
3545 const int rw = rq_data_dir(rq);
3546 const bool is_sync = rq_is_sync(rq);
3547 struct cfq_queue *cfqq;
3548 unsigned long flags;
3549
3550 might_sleep_if(gfp_mask & __GFP_WAIT);
3551
3552 cic = cfq_get_io_context(cfqd, gfp_mask);
3553
3554 spin_lock_irqsave(q->queue_lock, flags);
3555
3556 if (!cic)
3557 goto queue_fail;
3558
3559 new_queue:
3560 cfqq = cic_to_cfqq(cic, is_sync);
3561 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
3562 cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask);
3563 cic_set_cfqq(cic, cfqq, is_sync);
3564 } else {
3565 /*
3566 * If the queue was seeky for too long, break it apart.
3567 */
3568 if (cfq_cfqq_coop(cfqq) && cfq_cfqq_split_coop(cfqq)) {
3569 cfq_log_cfqq(cfqd, cfqq, "breaking apart cfqq");
3570 cfqq = split_cfqq(cic, cfqq);
3571 if (!cfqq)
3572 goto new_queue;
3573 }
3574
3575 /*
3576 * Check to see if this queue is scheduled to merge with
3577 * another, closely cooperating queue. The merging of
3578 * queues happens here as it must be done in process context.
3579 * The reference on new_cfqq was taken in merge_cfqqs.
3580 */
3581 if (cfqq->new_cfqq)
3582 cfqq = cfq_merge_cfqqs(cfqd, cic, cfqq);
3583 }
3584
3585 cfqq->allocated[rw]++;
3586 atomic_inc(&cfqq->ref);
3587
3588 spin_unlock_irqrestore(q->queue_lock, flags);
3589
3590 rq->elevator_private = cic;
3591 rq->elevator_private2 = cfqq;
3592 rq->elevator_private3 = cfq_ref_get_cfqg(cfqq->cfqg);
3593 return 0;
3594
3595 queue_fail:
3596 if (cic)
3597 put_io_context(cic->ioc);
3598
3599 cfq_schedule_dispatch(cfqd);
3600 spin_unlock_irqrestore(q->queue_lock, flags);
3601 cfq_log(cfqd, "set_request fail");
3602 return 1;
3603 }
3604
3605 static void cfq_kick_queue(struct work_struct *work)
3606 {
3607 struct cfq_data *cfqd =
3608 container_of(work, struct cfq_data, unplug_work);
3609 struct request_queue *q = cfqd->queue;
3610
3611 spin_lock_irq(q->queue_lock);
3612 __blk_run_queue(cfqd->queue);
3613 spin_unlock_irq(q->queue_lock);
3614 }
3615
3616 /*
3617 * Timer running if the active_queue is currently idling inside its time slice
3618 */
3619 static void cfq_idle_slice_timer(unsigned long data)
3620 {
3621 struct cfq_data *cfqd = (struct cfq_data *) data;
3622 struct cfq_queue *cfqq;
3623 unsigned long flags;
3624 int timed_out = 1;
3625
3626 cfq_log(cfqd, "idle timer fired");
3627
3628 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
3629
3630 cfqq = cfqd->active_queue;
3631 if (cfqq) {
3632 timed_out = 0;
3633
3634 /*
3635 * We saw a request before the queue expired, let it through
3636 */
3637 if (cfq_cfqq_must_dispatch(cfqq))
3638 goto out_kick;
3639
3640 /*
3641 * expired
3642 */
3643 if (cfq_slice_used(cfqq))
3644 goto expire;
3645
3646 /*
3647 * only expire and reinvoke request handler, if there are
3648 * other queues with pending requests
3649 */
3650 if (!cfqd->busy_queues)
3651 goto out_cont;
3652
3653 /*
3654 * not expired and it has a request pending, let it dispatch
3655 */
3656 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
3657 goto out_kick;
3658
3659 /*
3660 * Queue depth flag is reset only when the idle didn't succeed
3661 */
3662 cfq_clear_cfqq_deep(cfqq);
3663 }
3664 expire:
3665 cfq_slice_expired(cfqd, timed_out);
3666 out_kick:
3667 cfq_schedule_dispatch(cfqd);
3668 out_cont:
3669 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
3670 }
3671
3672 static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
3673 {
3674 del_timer_sync(&cfqd->idle_slice_timer);
3675 cancel_work_sync(&cfqd->unplug_work);
3676 }
3677
3678 static void cfq_put_async_queues(struct cfq_data *cfqd)
3679 {
3680 int i;
3681
3682 for (i = 0; i < IOPRIO_BE_NR; i++) {
3683 if (cfqd->async_cfqq[0][i])
3684 cfq_put_queue(cfqd->async_cfqq[0][i]);
3685 if (cfqd->async_cfqq[1][i])
3686 cfq_put_queue(cfqd->async_cfqq[1][i]);
3687 }
3688
3689 if (cfqd->async_idle_cfqq)
3690 cfq_put_queue(cfqd->async_idle_cfqq);
3691 }
3692
3693 static void cfq_cfqd_free(struct rcu_head *head)
3694 {
3695 kfree(container_of(head, struct cfq_data, rcu));
3696 }
3697
3698 static void cfq_exit_queue(struct elevator_queue *e)
3699 {
3700 struct cfq_data *cfqd = e->elevator_data;
3701 struct request_queue *q = cfqd->queue;
3702
3703 cfq_shutdown_timer_wq(cfqd);
3704
3705 spin_lock_irq(q->queue_lock);
3706
3707 if (cfqd->active_queue)
3708 __cfq_slice_expired(cfqd, cfqd->active_queue, 0);
3709
3710 while (!list_empty(&cfqd->cic_list)) {
3711 struct cfq_io_context *cic = list_entry(cfqd->cic_list.next,
3712 struct cfq_io_context,
3713 queue_list);
3714
3715 __cfq_exit_single_io_context(cfqd, cic);
3716 }
3717
3718 cfq_put_async_queues(cfqd);
3719 cfq_release_cfq_groups(cfqd);
3720 blkiocg_del_blkio_group(&cfqd->root_group.blkg);
3721
3722 spin_unlock_irq(q->queue_lock);
3723
3724 cfq_shutdown_timer_wq(cfqd);
3725
3726 /* Wait for cfqg->blkg->key accessors to exit their grace periods. */
3727 call_rcu(&cfqd->rcu, cfq_cfqd_free);
3728 }
3729
3730 static void *cfq_init_queue(struct request_queue *q)
3731 {
3732 struct cfq_data *cfqd;
3733 int i, j;
3734 struct cfq_group *cfqg;
3735 struct cfq_rb_root *st;
3736
3737 cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node);
3738 if (!cfqd)
3739 return NULL;
3740
3741 /* Init root service tree */
3742 cfqd->grp_service_tree = CFQ_RB_ROOT;
3743
3744 /* Init root group */
3745 cfqg = &cfqd->root_group;
3746 for_each_cfqg_st(cfqg, i, j, st)
3747 *st = CFQ_RB_ROOT;
3748 RB_CLEAR_NODE(&cfqg->rb_node);
3749
3750 /* Give preference to root group over other groups */
3751 cfqg->weight = 2*BLKIO_WEIGHT_DEFAULT;
3752
3753 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3754 /*
3755 * Take a reference to root group which we never drop. This is just
3756 * to make sure that cfq_put_cfqg() does not try to kfree root group
3757 */
3758 atomic_set(&cfqg->ref, 1);
3759 rcu_read_lock();
3760 blkiocg_add_blkio_group(&blkio_root_cgroup, &cfqg->blkg, (void *)cfqd,
3761 0);
3762 rcu_read_unlock();
3763 #endif
3764 /*
3765 * Not strictly needed (since RB_ROOT just clears the node and we
3766 * zeroed cfqd on alloc), but better be safe in case someone decides
3767 * to add magic to the rb code
3768 */
3769 for (i = 0; i < CFQ_PRIO_LISTS; i++)
3770 cfqd->prio_trees[i] = RB_ROOT;
3771
3772 /*
3773 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
3774 * Grab a permanent reference to it, so that the normal code flow
3775 * will not attempt to free it.
3776 */
3777 cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0);
3778 atomic_inc(&cfqd->oom_cfqq.ref);
3779 cfq_link_cfqq_cfqg(&cfqd->oom_cfqq, &cfqd->root_group);
3780
3781 INIT_LIST_HEAD(&cfqd->cic_list);
3782
3783 cfqd->queue = q;
3784
3785 init_timer(&cfqd->idle_slice_timer);
3786 cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
3787 cfqd->idle_slice_timer.data = (unsigned long) cfqd;
3788
3789 INIT_WORK(&cfqd->unplug_work, cfq_kick_queue);
3790
3791 cfqd->cfq_quantum = cfq_quantum;
3792 cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
3793 cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
3794 cfqd->cfq_back_max = cfq_back_max;
3795 cfqd->cfq_back_penalty = cfq_back_penalty;
3796 cfqd->cfq_slice[0] = cfq_slice_async;
3797 cfqd->cfq_slice[1] = cfq_slice_sync;
3798 cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
3799 cfqd->cfq_slice_idle = cfq_slice_idle;
3800 cfqd->cfq_latency = 1;
3801 cfqd->cfq_group_isolation = 0;
3802 cfqd->hw_tag = -1;
3803 /*
3804 * we optimistically start assuming sync ops weren't delayed in last
3805 * second, in order to have larger depth for async operations.
3806 */
3807 cfqd->last_delayed_sync = jiffies - HZ;
3808 return cfqd;
3809 }
3810
3811 static void cfq_slab_kill(void)
3812 {
3813 /*
3814 * Caller already ensured that pending RCU callbacks are completed,
3815 * so we should have no busy allocations at this point.
3816 */
3817 if (cfq_pool)
3818 kmem_cache_destroy(cfq_pool);
3819 if (cfq_ioc_pool)
3820 kmem_cache_destroy(cfq_ioc_pool);
3821 }
3822
3823 static int __init cfq_slab_setup(void)
3824 {
3825 cfq_pool = KMEM_CACHE(cfq_queue, 0);
3826 if (!cfq_pool)
3827 goto fail;
3828
3829 cfq_ioc_pool = KMEM_CACHE(cfq_io_context, 0);
3830 if (!cfq_ioc_pool)
3831 goto fail;
3832
3833 return 0;
3834 fail:
3835 cfq_slab_kill();
3836 return -ENOMEM;
3837 }
3838
3839 /*
3840 * sysfs parts below -->
3841 */
3842 static ssize_t
3843 cfq_var_show(unsigned int var, char *page)
3844 {
3845 return sprintf(page, "%d\n", var);
3846 }
3847
3848 static ssize_t
3849 cfq_var_store(unsigned int *var, const char *page, size_t count)
3850 {
3851 char *p = (char *) page;
3852
3853 *var = simple_strtoul(p, &p, 10);
3854 return count;
3855 }
3856
3857 #define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
3858 static ssize_t __FUNC(struct elevator_queue *e, char *page) \
3859 { \
3860 struct cfq_data *cfqd = e->elevator_data; \
3861 unsigned int __data = __VAR; \
3862 if (__CONV) \
3863 __data = jiffies_to_msecs(__data); \
3864 return cfq_var_show(__data, (page)); \
3865 }
3866 SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
3867 SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
3868 SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
3869 SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0);
3870 SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0);
3871 SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
3872 SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
3873 SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
3874 SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
3875 SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0);
3876 SHOW_FUNCTION(cfq_group_isolation_show, cfqd->cfq_group_isolation, 0);
3877 #undef SHOW_FUNCTION
3878
3879 #define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
3880 static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
3881 { \
3882 struct cfq_data *cfqd = e->elevator_data; \
3883 unsigned int __data; \
3884 int ret = cfq_var_store(&__data, (page), count); \
3885 if (__data < (MIN)) \
3886 __data = (MIN); \
3887 else if (__data > (MAX)) \
3888 __data = (MAX); \
3889 if (__CONV) \
3890 *(__PTR) = msecs_to_jiffies(__data); \
3891 else \
3892 *(__PTR) = __data; \
3893 return ret; \
3894 }
3895 STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
3896 STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1,
3897 UINT_MAX, 1);
3898 STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1,
3899 UINT_MAX, 1);
3900 STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
3901 STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1,
3902 UINT_MAX, 0);
3903 STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
3904 STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
3905 STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
3906 STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
3907 UINT_MAX, 0);
3908 STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0);
3909 STORE_FUNCTION(cfq_group_isolation_store, &cfqd->cfq_group_isolation, 0, 1, 0);
3910 #undef STORE_FUNCTION
3911
3912 #define CFQ_ATTR(name) \
3913 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
3914
3915 static struct elv_fs_entry cfq_attrs[] = {
3916 CFQ_ATTR(quantum),
3917 CFQ_ATTR(fifo_expire_sync),
3918 CFQ_ATTR(fifo_expire_async),
3919 CFQ_ATTR(back_seek_max),
3920 CFQ_ATTR(back_seek_penalty),
3921 CFQ_ATTR(slice_sync),
3922 CFQ_ATTR(slice_async),
3923 CFQ_ATTR(slice_async_rq),
3924 CFQ_ATTR(slice_idle),
3925 CFQ_ATTR(low_latency),
3926 CFQ_ATTR(group_isolation),
3927 __ATTR_NULL
3928 };
3929
3930 static struct elevator_type iosched_cfq = {
3931 .ops = {
3932 .elevator_merge_fn = cfq_merge,
3933 .elevator_merged_fn = cfq_merged_request,
3934 .elevator_merge_req_fn = cfq_merged_requests,
3935 .elevator_allow_merge_fn = cfq_allow_merge,
3936 .elevator_bio_merged_fn = cfq_bio_merged,
3937 .elevator_dispatch_fn = cfq_dispatch_requests,
3938 .elevator_add_req_fn = cfq_insert_request,
3939 .elevator_activate_req_fn = cfq_activate_request,
3940 .elevator_deactivate_req_fn = cfq_deactivate_request,
3941 .elevator_queue_empty_fn = cfq_queue_empty,
3942 .elevator_completed_req_fn = cfq_completed_request,
3943 .elevator_former_req_fn = elv_rb_former_request,
3944 .elevator_latter_req_fn = elv_rb_latter_request,
3945 .elevator_set_req_fn = cfq_set_request,
3946 .elevator_put_req_fn = cfq_put_request,
3947 .elevator_may_queue_fn = cfq_may_queue,
3948 .elevator_init_fn = cfq_init_queue,
3949 .elevator_exit_fn = cfq_exit_queue,
3950 .trim = cfq_free_io_context,
3951 },
3952 .elevator_attrs = cfq_attrs,
3953 .elevator_name = "cfq",
3954 .elevator_owner = THIS_MODULE,
3955 };
3956
3957 #ifdef CONFIG_CFQ_GROUP_IOSCHED
3958 static struct blkio_policy_type blkio_policy_cfq = {
3959 .ops = {
3960 .blkio_unlink_group_fn = cfq_unlink_blkio_group,
3961 .blkio_update_group_weight_fn = cfq_update_blkio_group_weight,
3962 },
3963 };
3964 #else
3965 static struct blkio_policy_type blkio_policy_cfq;
3966 #endif
3967
3968 static int __init cfq_init(void)
3969 {
3970 /*
3971 * could be 0 on HZ < 1000 setups
3972 */
3973 if (!cfq_slice_async)
3974 cfq_slice_async = 1;
3975 if (!cfq_slice_idle)
3976 cfq_slice_idle = 1;
3977
3978 if (cfq_slab_setup())
3979 return -ENOMEM;
3980
3981 elv_register(&iosched_cfq);
3982 blkio_policy_register(&blkio_policy_cfq);
3983
3984 return 0;
3985 }
3986
3987 static void __exit cfq_exit(void)
3988 {
3989 DECLARE_COMPLETION_ONSTACK(all_gone);
3990 blkio_policy_unregister(&blkio_policy_cfq);
3991 elv_unregister(&iosched_cfq);
3992 ioc_gone = &all_gone;
3993 /* ioc_gone's update must be visible before reading ioc_count */
3994 smp_wmb();
3995
3996 /*
3997 * this also protects us from entering cfq_slab_kill() with
3998 * pending RCU callbacks
3999 */
4000 if (elv_ioc_count_read(cfq_ioc_count))
4001 wait_for_completion(&all_gone);
4002 cfq_slab_kill();
4003 }
4004
4005 module_init(cfq_init);
4006 module_exit(cfq_exit);
4007
4008 MODULE_AUTHOR("Jens Axboe");
4009 MODULE_LICENSE("GPL");
4010 MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");