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be2net: Patch to flash redboot section while firmware update.
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CommitLineData
1da177e4 1/*
1da177e4
LT
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 *
0fe23479 7 * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk>
1da177e4 8 */
1da177e4 9#include <linux/module.h>
1cc9be68
AV
10#include <linux/blkdev.h>
11#include <linux/elevator.h>
1da177e4 12#include <linux/rbtree.h>
22e2c507 13#include <linux/ioprio.h>
7b679138 14#include <linux/blktrace_api.h>
1da177e4
LT
15
16/*
17 * tunables
18 */
fe094d98
JA
19/* max queue in one round of service */
20static const int cfq_quantum = 4;
64100099 21static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 };
fe094d98
JA
22/* maximum backwards seek, in KiB */
23static const int cfq_back_max = 16 * 1024;
24/* penalty of a backwards seek */
25static const int cfq_back_penalty = 2;
64100099 26static const int cfq_slice_sync = HZ / 10;
3b18152c 27static int cfq_slice_async = HZ / 25;
64100099 28static const int cfq_slice_async_rq = 2;
caaa5f9f 29static int cfq_slice_idle = HZ / 125;
22e2c507 30
d9e7620e 31/*
0871714e 32 * offset from end of service tree
d9e7620e 33 */
0871714e 34#define CFQ_IDLE_DELAY (HZ / 5)
d9e7620e
JA
35
36/*
37 * below this threshold, we consider thinktime immediate
38 */
39#define CFQ_MIN_TT (2)
40
22e2c507 41#define CFQ_SLICE_SCALE (5)
45333d5a 42#define CFQ_HW_QUEUE_MIN (5)
22e2c507 43
fe094d98
JA
44#define RQ_CIC(rq) \
45 ((struct cfq_io_context *) (rq)->elevator_private)
7b679138 46#define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elevator_private2)
1da177e4 47
e18b890b
CL
48static struct kmem_cache *cfq_pool;
49static struct kmem_cache *cfq_ioc_pool;
1da177e4 50
245b2e70 51static DEFINE_PER_CPU(unsigned long, cfq_ioc_count);
334e94de 52static struct completion *ioc_gone;
9a11b4ed 53static DEFINE_SPINLOCK(ioc_gone_lock);
334e94de 54
22e2c507
JA
55#define CFQ_PRIO_LISTS IOPRIO_BE_NR
56#define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE)
22e2c507
JA
57#define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT)
58
206dc69b
JA
59#define sample_valid(samples) ((samples) > 80)
60
cc09e299
JA
61/*
62 * Most of our rbtree usage is for sorting with min extraction, so
63 * if we cache the leftmost node we don't have to walk down the tree
64 * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should
65 * move this into the elevator for the rq sorting as well.
66 */
67struct cfq_rb_root {
68 struct rb_root rb;
69 struct rb_node *left;
70};
71#define CFQ_RB_ROOT (struct cfq_rb_root) { RB_ROOT, NULL, }
72
6118b70b
JA
73/*
74 * Per process-grouping structure
75 */
76struct cfq_queue {
77 /* reference count */
78 atomic_t ref;
79 /* various state flags, see below */
80 unsigned int flags;
81 /* parent cfq_data */
82 struct cfq_data *cfqd;
83 /* service_tree member */
84 struct rb_node rb_node;
85 /* service_tree key */
86 unsigned long rb_key;
87 /* prio tree member */
88 struct rb_node p_node;
89 /* prio tree root we belong to, if any */
90 struct rb_root *p_root;
91 /* sorted list of pending requests */
92 struct rb_root sort_list;
93 /* if fifo isn't expired, next request to serve */
94 struct request *next_rq;
95 /* requests queued in sort_list */
96 int queued[2];
97 /* currently allocated requests */
98 int allocated[2];
99 /* fifo list of requests in sort_list */
100 struct list_head fifo;
101
102 unsigned long slice_end;
103 long slice_resid;
104 unsigned int slice_dispatch;
105
106 /* pending metadata requests */
107 int meta_pending;
108 /* number of requests that are on the dispatch list or inside driver */
109 int dispatched;
110
111 /* io prio of this group */
112 unsigned short ioprio, org_ioprio;
113 unsigned short ioprio_class, org_ioprio_class;
114
115 pid_t pid;
116};
117
22e2c507
JA
118/*
119 * Per block device queue structure
120 */
1da177e4 121struct cfq_data {
165125e1 122 struct request_queue *queue;
22e2c507
JA
123
124 /*
125 * rr list of queues with requests and the count of them
126 */
cc09e299 127 struct cfq_rb_root service_tree;
a36e71f9
JA
128
129 /*
130 * Each priority tree is sorted by next_request position. These
131 * trees are used when determining if two or more queues are
132 * interleaving requests (see cfq_close_cooperator).
133 */
134 struct rb_root prio_trees[CFQ_PRIO_LISTS];
135
22e2c507
JA
136 unsigned int busy_queues;
137
5ad531db 138 int rq_in_driver[2];
3ed9a296 139 int sync_flight;
45333d5a
AC
140
141 /*
142 * queue-depth detection
143 */
144 int rq_queued;
25776e35 145 int hw_tag;
45333d5a
AC
146 int hw_tag_samples;
147 int rq_in_driver_peak;
1da177e4 148
22e2c507
JA
149 /*
150 * idle window management
151 */
152 struct timer_list idle_slice_timer;
23e018a1 153 struct work_struct unplug_work;
1da177e4 154
22e2c507
JA
155 struct cfq_queue *active_queue;
156 struct cfq_io_context *active_cic;
22e2c507 157
c2dea2d1
VT
158 /*
159 * async queue for each priority case
160 */
161 struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR];
162 struct cfq_queue *async_idle_cfqq;
15c31be4 163
6d048f53 164 sector_t last_position;
1da177e4 165
1da177e4
LT
166 /*
167 * tunables, see top of file
168 */
169 unsigned int cfq_quantum;
22e2c507 170 unsigned int cfq_fifo_expire[2];
1da177e4
LT
171 unsigned int cfq_back_penalty;
172 unsigned int cfq_back_max;
22e2c507
JA
173 unsigned int cfq_slice[2];
174 unsigned int cfq_slice_async_rq;
175 unsigned int cfq_slice_idle;
963b72fc 176 unsigned int cfq_latency;
d9ff4187
AV
177
178 struct list_head cic_list;
1da177e4 179
6118b70b
JA
180 /*
181 * Fallback dummy cfqq for extreme OOM conditions
182 */
183 struct cfq_queue oom_cfqq;
365722bb
VG
184
185 unsigned long last_end_sync_rq;
1da177e4
LT
186};
187
3b18152c 188enum cfqq_state_flags {
b0b8d749
JA
189 CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */
190 CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */
b029195d 191 CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */
b0b8d749 192 CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */
b0b8d749
JA
193 CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */
194 CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */
195 CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */
44f7c160 196 CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */
91fac317 197 CFQ_CFQQ_FLAG_sync, /* synchronous queue */
a36e71f9 198 CFQ_CFQQ_FLAG_coop, /* has done a coop jump of the queue */
4b27e1bb 199 CFQ_CFQQ_FLAG_coop_preempt, /* coop preempt */
3b18152c
JA
200};
201
202#define CFQ_CFQQ_FNS(name) \
203static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \
204{ \
fe094d98 205 (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \
3b18152c
JA
206} \
207static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \
208{ \
fe094d98 209 (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \
3b18152c
JA
210} \
211static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \
212{ \
fe094d98 213 return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \
3b18152c
JA
214}
215
216CFQ_CFQQ_FNS(on_rr);
217CFQ_CFQQ_FNS(wait_request);
b029195d 218CFQ_CFQQ_FNS(must_dispatch);
3b18152c 219CFQ_CFQQ_FNS(must_alloc_slice);
3b18152c
JA
220CFQ_CFQQ_FNS(fifo_expire);
221CFQ_CFQQ_FNS(idle_window);
222CFQ_CFQQ_FNS(prio_changed);
44f7c160 223CFQ_CFQQ_FNS(slice_new);
91fac317 224CFQ_CFQQ_FNS(sync);
a36e71f9 225CFQ_CFQQ_FNS(coop);
4b27e1bb 226CFQ_CFQQ_FNS(coop_preempt);
3b18152c
JA
227#undef CFQ_CFQQ_FNS
228
7b679138
JA
229#define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \
230 blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args)
231#define cfq_log(cfqd, fmt, args...) \
232 blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args)
233
165125e1 234static void cfq_dispatch_insert(struct request_queue *, struct request *);
a6151c3a 235static struct cfq_queue *cfq_get_queue(struct cfq_data *, bool,
fd0928df 236 struct io_context *, gfp_t);
4ac845a2 237static struct cfq_io_context *cfq_cic_lookup(struct cfq_data *,
91fac317
VT
238 struct io_context *);
239
5ad531db
JA
240static inline int rq_in_driver(struct cfq_data *cfqd)
241{
242 return cfqd->rq_in_driver[0] + cfqd->rq_in_driver[1];
243}
244
91fac317 245static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic,
a6151c3a 246 bool is_sync)
91fac317 247{
a6151c3a 248 return cic->cfqq[is_sync];
91fac317
VT
249}
250
251static inline void cic_set_cfqq(struct cfq_io_context *cic,
a6151c3a 252 struct cfq_queue *cfqq, bool is_sync)
91fac317 253{
a6151c3a 254 cic->cfqq[is_sync] = cfqq;
91fac317
VT
255}
256
257/*
258 * We regard a request as SYNC, if it's either a read or has the SYNC bit
259 * set (in which case it could also be direct WRITE).
260 */
a6151c3a 261static inline bool cfq_bio_sync(struct bio *bio)
91fac317 262{
a6151c3a 263 return bio_data_dir(bio) == READ || bio_rw_flagged(bio, BIO_RW_SYNCIO);
91fac317 264}
1da177e4 265
99f95e52
AM
266/*
267 * scheduler run of queue, if there are requests pending and no one in the
268 * driver that will restart queueing
269 */
23e018a1 270static inline void cfq_schedule_dispatch(struct cfq_data *cfqd)
99f95e52 271{
7b679138
JA
272 if (cfqd->busy_queues) {
273 cfq_log(cfqd, "schedule dispatch");
23e018a1 274 kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work);
7b679138 275 }
99f95e52
AM
276}
277
165125e1 278static int cfq_queue_empty(struct request_queue *q)
99f95e52
AM
279{
280 struct cfq_data *cfqd = q->elevator->elevator_data;
281
b4878f24 282 return !cfqd->busy_queues;
99f95e52
AM
283}
284
44f7c160
JA
285/*
286 * Scale schedule slice based on io priority. Use the sync time slice only
287 * if a queue is marked sync and has sync io queued. A sync queue with async
288 * io only, should not get full sync slice length.
289 */
a6151c3a 290static inline int cfq_prio_slice(struct cfq_data *cfqd, bool sync,
d9e7620e 291 unsigned short prio)
44f7c160 292{
d9e7620e 293 const int base_slice = cfqd->cfq_slice[sync];
44f7c160 294
d9e7620e
JA
295 WARN_ON(prio >= IOPRIO_BE_NR);
296
297 return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio));
298}
44f7c160 299
d9e7620e
JA
300static inline int
301cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
302{
303 return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio);
44f7c160
JA
304}
305
306static inline void
307cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
308{
309 cfqq->slice_end = cfq_prio_to_slice(cfqd, cfqq) + jiffies;
7b679138 310 cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies);
44f7c160
JA
311}
312
313/*
314 * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end
315 * isn't valid until the first request from the dispatch is activated
316 * and the slice time set.
317 */
a6151c3a 318static inline bool cfq_slice_used(struct cfq_queue *cfqq)
44f7c160
JA
319{
320 if (cfq_cfqq_slice_new(cfqq))
321 return 0;
322 if (time_before(jiffies, cfqq->slice_end))
323 return 0;
324
325 return 1;
326}
327
1da177e4 328/*
5e705374 329 * Lifted from AS - choose which of rq1 and rq2 that is best served now.
1da177e4 330 * We choose the request that is closest to the head right now. Distance
e8a99053 331 * behind the head is penalized and only allowed to a certain extent.
1da177e4 332 */
5e705374
JA
333static struct request *
334cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2)
1da177e4
LT
335{
336 sector_t last, s1, s2, d1 = 0, d2 = 0;
1da177e4 337 unsigned long back_max;
e8a99053
AM
338#define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */
339#define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */
340 unsigned wrap = 0; /* bit mask: requests behind the disk head? */
1da177e4 341
5e705374
JA
342 if (rq1 == NULL || rq1 == rq2)
343 return rq2;
344 if (rq2 == NULL)
345 return rq1;
9c2c38a1 346
5e705374
JA
347 if (rq_is_sync(rq1) && !rq_is_sync(rq2))
348 return rq1;
349 else if (rq_is_sync(rq2) && !rq_is_sync(rq1))
350 return rq2;
374f84ac
JA
351 if (rq_is_meta(rq1) && !rq_is_meta(rq2))
352 return rq1;
353 else if (rq_is_meta(rq2) && !rq_is_meta(rq1))
354 return rq2;
1da177e4 355
83096ebf
TH
356 s1 = blk_rq_pos(rq1);
357 s2 = blk_rq_pos(rq2);
1da177e4 358
6d048f53 359 last = cfqd->last_position;
1da177e4 360
1da177e4
LT
361 /*
362 * by definition, 1KiB is 2 sectors
363 */
364 back_max = cfqd->cfq_back_max * 2;
365
366 /*
367 * Strict one way elevator _except_ in the case where we allow
368 * short backward seeks which are biased as twice the cost of a
369 * similar forward seek.
370 */
371 if (s1 >= last)
372 d1 = s1 - last;
373 else if (s1 + back_max >= last)
374 d1 = (last - s1) * cfqd->cfq_back_penalty;
375 else
e8a99053 376 wrap |= CFQ_RQ1_WRAP;
1da177e4
LT
377
378 if (s2 >= last)
379 d2 = s2 - last;
380 else if (s2 + back_max >= last)
381 d2 = (last - s2) * cfqd->cfq_back_penalty;
382 else
e8a99053 383 wrap |= CFQ_RQ2_WRAP;
1da177e4
LT
384
385 /* Found required data */
e8a99053
AM
386
387 /*
388 * By doing switch() on the bit mask "wrap" we avoid having to
389 * check two variables for all permutations: --> faster!
390 */
391 switch (wrap) {
5e705374 392 case 0: /* common case for CFQ: rq1 and rq2 not wrapped */
e8a99053 393 if (d1 < d2)
5e705374 394 return rq1;
e8a99053 395 else if (d2 < d1)
5e705374 396 return rq2;
e8a99053
AM
397 else {
398 if (s1 >= s2)
5e705374 399 return rq1;
e8a99053 400 else
5e705374 401 return rq2;
e8a99053 402 }
1da177e4 403
e8a99053 404 case CFQ_RQ2_WRAP:
5e705374 405 return rq1;
e8a99053 406 case CFQ_RQ1_WRAP:
5e705374
JA
407 return rq2;
408 case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */
e8a99053
AM
409 default:
410 /*
411 * Since both rqs are wrapped,
412 * start with the one that's further behind head
413 * (--> only *one* back seek required),
414 * since back seek takes more time than forward.
415 */
416 if (s1 <= s2)
5e705374 417 return rq1;
1da177e4 418 else
5e705374 419 return rq2;
1da177e4
LT
420 }
421}
422
498d3aa2
JA
423/*
424 * The below is leftmost cache rbtree addon
425 */
0871714e 426static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root)
cc09e299
JA
427{
428 if (!root->left)
429 root->left = rb_first(&root->rb);
430
0871714e
JA
431 if (root->left)
432 return rb_entry(root->left, struct cfq_queue, rb_node);
433
434 return NULL;
cc09e299
JA
435}
436
a36e71f9
JA
437static void rb_erase_init(struct rb_node *n, struct rb_root *root)
438{
439 rb_erase(n, root);
440 RB_CLEAR_NODE(n);
441}
442
cc09e299
JA
443static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root)
444{
445 if (root->left == n)
446 root->left = NULL;
a36e71f9 447 rb_erase_init(n, &root->rb);
cc09e299
JA
448}
449
1da177e4
LT
450/*
451 * would be nice to take fifo expire time into account as well
452 */
5e705374
JA
453static struct request *
454cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
455 struct request *last)
1da177e4 456{
21183b07
JA
457 struct rb_node *rbnext = rb_next(&last->rb_node);
458 struct rb_node *rbprev = rb_prev(&last->rb_node);
5e705374 459 struct request *next = NULL, *prev = NULL;
1da177e4 460
21183b07 461 BUG_ON(RB_EMPTY_NODE(&last->rb_node));
1da177e4
LT
462
463 if (rbprev)
5e705374 464 prev = rb_entry_rq(rbprev);
1da177e4 465
21183b07 466 if (rbnext)
5e705374 467 next = rb_entry_rq(rbnext);
21183b07
JA
468 else {
469 rbnext = rb_first(&cfqq->sort_list);
470 if (rbnext && rbnext != &last->rb_node)
5e705374 471 next = rb_entry_rq(rbnext);
21183b07 472 }
1da177e4 473
21183b07 474 return cfq_choose_req(cfqd, next, prev);
1da177e4
LT
475}
476
d9e7620e
JA
477static unsigned long cfq_slice_offset(struct cfq_data *cfqd,
478 struct cfq_queue *cfqq)
1da177e4 479{
d9e7620e
JA
480 /*
481 * just an approximation, should be ok.
482 */
67e6b49e
JA
483 return (cfqd->busy_queues - 1) * (cfq_prio_slice(cfqd, 1, 0) -
484 cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio));
d9e7620e
JA
485}
486
498d3aa2
JA
487/*
488 * The cfqd->service_tree holds all pending cfq_queue's that have
489 * requests waiting to be processed. It is sorted in the order that
490 * we will service the queues.
491 */
a36e71f9 492static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
a6151c3a 493 bool add_front)
d9e7620e 494{
0871714e
JA
495 struct rb_node **p, *parent;
496 struct cfq_queue *__cfqq;
d9e7620e 497 unsigned long rb_key;
498d3aa2 498 int left;
d9e7620e 499
0871714e
JA
500 if (cfq_class_idle(cfqq)) {
501 rb_key = CFQ_IDLE_DELAY;
502 parent = rb_last(&cfqd->service_tree.rb);
503 if (parent && parent != &cfqq->rb_node) {
504 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
505 rb_key += __cfqq->rb_key;
506 } else
507 rb_key += jiffies;
508 } else if (!add_front) {
b9c8946b
JA
509 /*
510 * Get our rb key offset. Subtract any residual slice
511 * value carried from last service. A negative resid
512 * count indicates slice overrun, and this should position
513 * the next service time further away in the tree.
514 */
edd75ffd 515 rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies;
b9c8946b 516 rb_key -= cfqq->slice_resid;
edd75ffd 517 cfqq->slice_resid = 0;
48e025e6
CZ
518 } else {
519 rb_key = -HZ;
520 __cfqq = cfq_rb_first(&cfqd->service_tree);
521 rb_key += __cfqq ? __cfqq->rb_key : jiffies;
522 }
1da177e4 523
d9e7620e 524 if (!RB_EMPTY_NODE(&cfqq->rb_node)) {
99f9628a 525 /*
d9e7620e 526 * same position, nothing more to do
99f9628a 527 */
d9e7620e
JA
528 if (rb_key == cfqq->rb_key)
529 return;
1da177e4 530
cc09e299 531 cfq_rb_erase(&cfqq->rb_node, &cfqd->service_tree);
1da177e4 532 }
d9e7620e 533
498d3aa2 534 left = 1;
0871714e
JA
535 parent = NULL;
536 p = &cfqd->service_tree.rb.rb_node;
d9e7620e 537 while (*p) {
67060e37 538 struct rb_node **n;
cc09e299 539
d9e7620e
JA
540 parent = *p;
541 __cfqq = rb_entry(parent, struct cfq_queue, rb_node);
542
0c534e0a
JA
543 /*
544 * sort RT queues first, we always want to give
67060e37
JA
545 * preference to them. IDLE queues goes to the back.
546 * after that, sort on the next service time.
0c534e0a
JA
547 */
548 if (cfq_class_rt(cfqq) > cfq_class_rt(__cfqq))
67060e37 549 n = &(*p)->rb_left;
0c534e0a 550 else if (cfq_class_rt(cfqq) < cfq_class_rt(__cfqq))
67060e37
JA
551 n = &(*p)->rb_right;
552 else if (cfq_class_idle(cfqq) < cfq_class_idle(__cfqq))
553 n = &(*p)->rb_left;
554 else if (cfq_class_idle(cfqq) > cfq_class_idle(__cfqq))
555 n = &(*p)->rb_right;
48e025e6 556 else if (time_before(rb_key, __cfqq->rb_key))
67060e37
JA
557 n = &(*p)->rb_left;
558 else
559 n = &(*p)->rb_right;
560
561 if (n == &(*p)->rb_right)
cc09e299 562 left = 0;
67060e37
JA
563
564 p = n;
d9e7620e
JA
565 }
566
cc09e299
JA
567 if (left)
568 cfqd->service_tree.left = &cfqq->rb_node;
569
d9e7620e
JA
570 cfqq->rb_key = rb_key;
571 rb_link_node(&cfqq->rb_node, parent, p);
cc09e299 572 rb_insert_color(&cfqq->rb_node, &cfqd->service_tree.rb);
1da177e4
LT
573}
574
a36e71f9 575static struct cfq_queue *
f2d1f0ae
JA
576cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root,
577 sector_t sector, struct rb_node **ret_parent,
578 struct rb_node ***rb_link)
a36e71f9 579{
a36e71f9
JA
580 struct rb_node **p, *parent;
581 struct cfq_queue *cfqq = NULL;
582
583 parent = NULL;
584 p = &root->rb_node;
585 while (*p) {
586 struct rb_node **n;
587
588 parent = *p;
589 cfqq = rb_entry(parent, struct cfq_queue, p_node);
590
591 /*
592 * Sort strictly based on sector. Smallest to the left,
593 * largest to the right.
594 */
2e46e8b2 595 if (sector > blk_rq_pos(cfqq->next_rq))
a36e71f9 596 n = &(*p)->rb_right;
2e46e8b2 597 else if (sector < blk_rq_pos(cfqq->next_rq))
a36e71f9
JA
598 n = &(*p)->rb_left;
599 else
600 break;
601 p = n;
3ac6c9f8 602 cfqq = NULL;
a36e71f9
JA
603 }
604
605 *ret_parent = parent;
606 if (rb_link)
607 *rb_link = p;
3ac6c9f8 608 return cfqq;
a36e71f9
JA
609}
610
611static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
612{
a36e71f9
JA
613 struct rb_node **p, *parent;
614 struct cfq_queue *__cfqq;
615
f2d1f0ae
JA
616 if (cfqq->p_root) {
617 rb_erase(&cfqq->p_node, cfqq->p_root);
618 cfqq->p_root = NULL;
619 }
a36e71f9
JA
620
621 if (cfq_class_idle(cfqq))
622 return;
623 if (!cfqq->next_rq)
624 return;
625
f2d1f0ae 626 cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
2e46e8b2
TH
627 __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root,
628 blk_rq_pos(cfqq->next_rq), &parent, &p);
3ac6c9f8
JA
629 if (!__cfqq) {
630 rb_link_node(&cfqq->p_node, parent, p);
f2d1f0ae
JA
631 rb_insert_color(&cfqq->p_node, cfqq->p_root);
632 } else
633 cfqq->p_root = NULL;
a36e71f9
JA
634}
635
498d3aa2
JA
636/*
637 * Update cfqq's position in the service tree.
638 */
edd75ffd 639static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq)
6d048f53 640{
6d048f53
JA
641 /*
642 * Resorting requires the cfqq to be on the RR list already.
643 */
a36e71f9 644 if (cfq_cfqq_on_rr(cfqq)) {
edd75ffd 645 cfq_service_tree_add(cfqd, cfqq, 0);
a36e71f9
JA
646 cfq_prio_tree_add(cfqd, cfqq);
647 }
6d048f53
JA
648}
649
1da177e4
LT
650/*
651 * add to busy list of queues for service, trying to be fair in ordering
22e2c507 652 * the pending list according to last request service
1da177e4 653 */
febffd61 654static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1da177e4 655{
7b679138 656 cfq_log_cfqq(cfqd, cfqq, "add_to_rr");
3b18152c
JA
657 BUG_ON(cfq_cfqq_on_rr(cfqq));
658 cfq_mark_cfqq_on_rr(cfqq);
1da177e4
LT
659 cfqd->busy_queues++;
660
edd75ffd 661 cfq_resort_rr_list(cfqd, cfqq);
1da177e4
LT
662}
663
498d3aa2
JA
664/*
665 * Called when the cfqq no longer has requests pending, remove it from
666 * the service tree.
667 */
febffd61 668static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1da177e4 669{
7b679138 670 cfq_log_cfqq(cfqd, cfqq, "del_from_rr");
3b18152c
JA
671 BUG_ON(!cfq_cfqq_on_rr(cfqq));
672 cfq_clear_cfqq_on_rr(cfqq);
1da177e4 673
cc09e299
JA
674 if (!RB_EMPTY_NODE(&cfqq->rb_node))
675 cfq_rb_erase(&cfqq->rb_node, &cfqd->service_tree);
f2d1f0ae
JA
676 if (cfqq->p_root) {
677 rb_erase(&cfqq->p_node, cfqq->p_root);
678 cfqq->p_root = NULL;
679 }
d9e7620e 680
1da177e4
LT
681 BUG_ON(!cfqd->busy_queues);
682 cfqd->busy_queues--;
683}
684
685/*
686 * rb tree support functions
687 */
febffd61 688static void cfq_del_rq_rb(struct request *rq)
1da177e4 689{
5e705374 690 struct cfq_queue *cfqq = RQ_CFQQ(rq);
b4878f24 691 struct cfq_data *cfqd = cfqq->cfqd;
5e705374 692 const int sync = rq_is_sync(rq);
1da177e4 693
b4878f24
JA
694 BUG_ON(!cfqq->queued[sync]);
695 cfqq->queued[sync]--;
1da177e4 696
5e705374 697 elv_rb_del(&cfqq->sort_list, rq);
1da177e4 698
dd67d051 699 if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list))
b4878f24 700 cfq_del_cfqq_rr(cfqd, cfqq);
1da177e4
LT
701}
702
5e705374 703static void cfq_add_rq_rb(struct request *rq)
1da177e4 704{
5e705374 705 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1da177e4 706 struct cfq_data *cfqd = cfqq->cfqd;
a36e71f9 707 struct request *__alias, *prev;
1da177e4 708
5380a101 709 cfqq->queued[rq_is_sync(rq)]++;
1da177e4
LT
710
711 /*
712 * looks a little odd, but the first insert might return an alias.
713 * if that happens, put the alias on the dispatch list
714 */
21183b07 715 while ((__alias = elv_rb_add(&cfqq->sort_list, rq)) != NULL)
5e705374 716 cfq_dispatch_insert(cfqd->queue, __alias);
5fccbf61
JA
717
718 if (!cfq_cfqq_on_rr(cfqq))
719 cfq_add_cfqq_rr(cfqd, cfqq);
5044eed4
JA
720
721 /*
722 * check if this request is a better next-serve candidate
723 */
a36e71f9 724 prev = cfqq->next_rq;
5044eed4 725 cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq);
a36e71f9
JA
726
727 /*
728 * adjust priority tree position, if ->next_rq changes
729 */
730 if (prev != cfqq->next_rq)
731 cfq_prio_tree_add(cfqd, cfqq);
732
5044eed4 733 BUG_ON(!cfqq->next_rq);
1da177e4
LT
734}
735
febffd61 736static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq)
1da177e4 737{
5380a101
JA
738 elv_rb_del(&cfqq->sort_list, rq);
739 cfqq->queued[rq_is_sync(rq)]--;
5e705374 740 cfq_add_rq_rb(rq);
1da177e4
LT
741}
742
206dc69b
JA
743static struct request *
744cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
1da177e4 745{
206dc69b 746 struct task_struct *tsk = current;
91fac317 747 struct cfq_io_context *cic;
206dc69b 748 struct cfq_queue *cfqq;
1da177e4 749
4ac845a2 750 cic = cfq_cic_lookup(cfqd, tsk->io_context);
91fac317
VT
751 if (!cic)
752 return NULL;
753
754 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
89850f7e
JA
755 if (cfqq) {
756 sector_t sector = bio->bi_sector + bio_sectors(bio);
757
21183b07 758 return elv_rb_find(&cfqq->sort_list, sector);
89850f7e 759 }
1da177e4 760
1da177e4
LT
761 return NULL;
762}
763
165125e1 764static void cfq_activate_request(struct request_queue *q, struct request *rq)
1da177e4 765{
22e2c507 766 struct cfq_data *cfqd = q->elevator->elevator_data;
3b18152c 767
5ad531db 768 cfqd->rq_in_driver[rq_is_sync(rq)]++;
7b679138 769 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
5ad531db 770 rq_in_driver(cfqd));
25776e35 771
5b93629b 772 cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq);
1da177e4
LT
773}
774
165125e1 775static void cfq_deactivate_request(struct request_queue *q, struct request *rq)
1da177e4 776{
b4878f24 777 struct cfq_data *cfqd = q->elevator->elevator_data;
5ad531db 778 const int sync = rq_is_sync(rq);
b4878f24 779
5ad531db
JA
780 WARN_ON(!cfqd->rq_in_driver[sync]);
781 cfqd->rq_in_driver[sync]--;
7b679138 782 cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
5ad531db 783 rq_in_driver(cfqd));
1da177e4
LT
784}
785
b4878f24 786static void cfq_remove_request(struct request *rq)
1da177e4 787{
5e705374 788 struct cfq_queue *cfqq = RQ_CFQQ(rq);
21183b07 789
5e705374
JA
790 if (cfqq->next_rq == rq)
791 cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq);
1da177e4 792
b4878f24 793 list_del_init(&rq->queuelist);
5e705374 794 cfq_del_rq_rb(rq);
374f84ac 795
45333d5a 796 cfqq->cfqd->rq_queued--;
374f84ac
JA
797 if (rq_is_meta(rq)) {
798 WARN_ON(!cfqq->meta_pending);
799 cfqq->meta_pending--;
800 }
1da177e4
LT
801}
802
165125e1
JA
803static int cfq_merge(struct request_queue *q, struct request **req,
804 struct bio *bio)
1da177e4
LT
805{
806 struct cfq_data *cfqd = q->elevator->elevator_data;
807 struct request *__rq;
1da177e4 808
206dc69b 809 __rq = cfq_find_rq_fmerge(cfqd, bio);
22e2c507 810 if (__rq && elv_rq_merge_ok(__rq, bio)) {
9817064b
JA
811 *req = __rq;
812 return ELEVATOR_FRONT_MERGE;
1da177e4
LT
813 }
814
815 return ELEVATOR_NO_MERGE;
1da177e4
LT
816}
817
165125e1 818static void cfq_merged_request(struct request_queue *q, struct request *req,
21183b07 819 int type)
1da177e4 820{
21183b07 821 if (type == ELEVATOR_FRONT_MERGE) {
5e705374 822 struct cfq_queue *cfqq = RQ_CFQQ(req);
1da177e4 823
5e705374 824 cfq_reposition_rq_rb(cfqq, req);
1da177e4 825 }
1da177e4
LT
826}
827
828static void
165125e1 829cfq_merged_requests(struct request_queue *q, struct request *rq,
1da177e4
LT
830 struct request *next)
831{
22e2c507
JA
832 /*
833 * reposition in fifo if next is older than rq
834 */
835 if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) &&
30996f40 836 time_before(rq_fifo_time(next), rq_fifo_time(rq))) {
22e2c507 837 list_move(&rq->queuelist, &next->queuelist);
30996f40
JA
838 rq_set_fifo_time(rq, rq_fifo_time(next));
839 }
22e2c507 840
b4878f24 841 cfq_remove_request(next);
22e2c507
JA
842}
843
165125e1 844static int cfq_allow_merge(struct request_queue *q, struct request *rq,
da775265
JA
845 struct bio *bio)
846{
847 struct cfq_data *cfqd = q->elevator->elevator_data;
91fac317 848 struct cfq_io_context *cic;
da775265 849 struct cfq_queue *cfqq;
da775265
JA
850
851 /*
ec8acb69 852 * Disallow merge of a sync bio into an async request.
da775265 853 */
91fac317 854 if (cfq_bio_sync(bio) && !rq_is_sync(rq))
a6151c3a 855 return false;
da775265
JA
856
857 /*
719d3402
JA
858 * Lookup the cfqq that this bio will be queued with. Allow
859 * merge only if rq is queued there.
da775265 860 */
4ac845a2 861 cic = cfq_cic_lookup(cfqd, current->io_context);
91fac317 862 if (!cic)
a6151c3a 863 return false;
719d3402 864
91fac317 865 cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio));
a6151c3a 866 return cfqq == RQ_CFQQ(rq);
da775265
JA
867}
868
febffd61
JA
869static void __cfq_set_active_queue(struct cfq_data *cfqd,
870 struct cfq_queue *cfqq)
22e2c507
JA
871{
872 if (cfqq) {
7b679138 873 cfq_log_cfqq(cfqd, cfqq, "set_active");
22e2c507 874 cfqq->slice_end = 0;
2f5cb738
JA
875 cfqq->slice_dispatch = 0;
876
2f5cb738 877 cfq_clear_cfqq_wait_request(cfqq);
b029195d 878 cfq_clear_cfqq_must_dispatch(cfqq);
3b18152c
JA
879 cfq_clear_cfqq_must_alloc_slice(cfqq);
880 cfq_clear_cfqq_fifo_expire(cfqq);
44f7c160 881 cfq_mark_cfqq_slice_new(cfqq);
2f5cb738
JA
882
883 del_timer(&cfqd->idle_slice_timer);
22e2c507
JA
884 }
885
886 cfqd->active_queue = cfqq;
887}
888
7b14e3b5
JA
889/*
890 * current cfqq expired its slice (or was too idle), select new one
891 */
892static void
893__cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
a6151c3a 894 bool timed_out)
7b14e3b5 895{
7b679138
JA
896 cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out);
897
7b14e3b5
JA
898 if (cfq_cfqq_wait_request(cfqq))
899 del_timer(&cfqd->idle_slice_timer);
900
7b14e3b5
JA
901 cfq_clear_cfqq_wait_request(cfqq);
902
903 /*
6084cdda 904 * store what was left of this slice, if the queue idled/timed out
7b14e3b5 905 */
7b679138 906 if (timed_out && !cfq_cfqq_slice_new(cfqq)) {
c5b680f3 907 cfqq->slice_resid = cfqq->slice_end - jiffies;
7b679138
JA
908 cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
909 }
7b14e3b5 910
edd75ffd 911 cfq_resort_rr_list(cfqd, cfqq);
7b14e3b5
JA
912
913 if (cfqq == cfqd->active_queue)
914 cfqd->active_queue = NULL;
915
916 if (cfqd->active_cic) {
917 put_io_context(cfqd->active_cic->ioc);
918 cfqd->active_cic = NULL;
919 }
7b14e3b5
JA
920}
921
a6151c3a 922static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out)
7b14e3b5
JA
923{
924 struct cfq_queue *cfqq = cfqd->active_queue;
925
926 if (cfqq)
6084cdda 927 __cfq_slice_expired(cfqd, cfqq, timed_out);
7b14e3b5
JA
928}
929
498d3aa2
JA
930/*
931 * Get next queue for service. Unless we have a queue preemption,
932 * we'll simply select the first cfqq in the service tree.
933 */
6d048f53 934static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd)
22e2c507 935{
edd75ffd
JA
936 if (RB_EMPTY_ROOT(&cfqd->service_tree.rb))
937 return NULL;
d9e7620e 938
0871714e 939 return cfq_rb_first(&cfqd->service_tree);
6d048f53
JA
940}
941
498d3aa2
JA
942/*
943 * Get and set a new active queue for service.
944 */
a36e71f9
JA
945static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
946 struct cfq_queue *cfqq)
6d048f53 947{
a36e71f9
JA
948 if (!cfqq) {
949 cfqq = cfq_get_next_queue(cfqd);
4b27e1bb 950 if (cfqq && !cfq_cfqq_coop_preempt(cfqq))
a36e71f9
JA
951 cfq_clear_cfqq_coop(cfqq);
952 }
6d048f53 953
4b27e1bb
SL
954 if (cfqq)
955 cfq_clear_cfqq_coop_preempt(cfqq);
956
22e2c507 957 __cfq_set_active_queue(cfqd, cfqq);
3b18152c 958 return cfqq;
22e2c507
JA
959}
960
d9e7620e
JA
961static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
962 struct request *rq)
963{
83096ebf
TH
964 if (blk_rq_pos(rq) >= cfqd->last_position)
965 return blk_rq_pos(rq) - cfqd->last_position;
d9e7620e 966 else
83096ebf 967 return cfqd->last_position - blk_rq_pos(rq);
d9e7620e
JA
968}
969
04dc6e71
JM
970#define CIC_SEEK_THR 8 * 1024
971#define CIC_SEEKY(cic) ((cic)->seek_mean > CIC_SEEK_THR)
972
6d048f53
JA
973static inline int cfq_rq_close(struct cfq_data *cfqd, struct request *rq)
974{
975 struct cfq_io_context *cic = cfqd->active_cic;
04dc6e71 976 sector_t sdist = cic->seek_mean;
6d048f53
JA
977
978 if (!sample_valid(cic->seek_samples))
04dc6e71 979 sdist = CIC_SEEK_THR;
6d048f53 980
04dc6e71 981 return cfq_dist_from_last(cfqd, rq) <= sdist;
6d048f53
JA
982}
983
a36e71f9
JA
984static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
985 struct cfq_queue *cur_cfqq)
986{
f2d1f0ae 987 struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
a36e71f9
JA
988 struct rb_node *parent, *node;
989 struct cfq_queue *__cfqq;
990 sector_t sector = cfqd->last_position;
991
992 if (RB_EMPTY_ROOT(root))
993 return NULL;
994
995 /*
996 * First, if we find a request starting at the end of the last
997 * request, choose it.
998 */
f2d1f0ae 999 __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
a36e71f9
JA
1000 if (__cfqq)
1001 return __cfqq;
1002
1003 /*
1004 * If the exact sector wasn't found, the parent of the NULL leaf
1005 * will contain the closest sector.
1006 */
1007 __cfqq = rb_entry(parent, struct cfq_queue, p_node);
1008 if (cfq_rq_close(cfqd, __cfqq->next_rq))
1009 return __cfqq;
1010
2e46e8b2 1011 if (blk_rq_pos(__cfqq->next_rq) < sector)
a36e71f9
JA
1012 node = rb_next(&__cfqq->p_node);
1013 else
1014 node = rb_prev(&__cfqq->p_node);
1015 if (!node)
1016 return NULL;
1017
1018 __cfqq = rb_entry(node, struct cfq_queue, p_node);
1019 if (cfq_rq_close(cfqd, __cfqq->next_rq))
1020 return __cfqq;
1021
1022 return NULL;
1023}
1024
1025/*
1026 * cfqd - obvious
1027 * cur_cfqq - passed in so that we don't decide that the current queue is
1028 * closely cooperating with itself.
1029 *
1030 * So, basically we're assuming that that cur_cfqq has dispatched at least
1031 * one request, and that cfqd->last_position reflects a position on the disk
1032 * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid
1033 * assumption.
1034 */
1035static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
1036 struct cfq_queue *cur_cfqq,
a6151c3a 1037 bool probe)
6d048f53 1038{
a36e71f9
JA
1039 struct cfq_queue *cfqq;
1040
1041 /*
1042 * A valid cfq_io_context is necessary to compare requests against
1043 * the seek_mean of the current cfqq.
1044 */
1045 if (!cfqd->active_cic)
1046 return NULL;
1047
6d048f53 1048 /*
d9e7620e
JA
1049 * We should notice if some of the queues are cooperating, eg
1050 * working closely on the same area of the disk. In that case,
1051 * we can group them together and don't waste time idling.
6d048f53 1052 */
a36e71f9
JA
1053 cfqq = cfqq_close(cfqd, cur_cfqq);
1054 if (!cfqq)
1055 return NULL;
1056
1057 if (cfq_cfqq_coop(cfqq))
1058 return NULL;
1059
1060 if (!probe)
1061 cfq_mark_cfqq_coop(cfqq);
1062 return cfqq;
6d048f53
JA
1063}
1064
6d048f53 1065static void cfq_arm_slice_timer(struct cfq_data *cfqd)
22e2c507 1066{
1792669c 1067 struct cfq_queue *cfqq = cfqd->active_queue;
206dc69b 1068 struct cfq_io_context *cic;
7b14e3b5
JA
1069 unsigned long sl;
1070
a68bbddb 1071 /*
f7d7b7a7
JA
1072 * SSD device without seek penalty, disable idling. But only do so
1073 * for devices that support queuing, otherwise we still have a problem
1074 * with sync vs async workloads.
a68bbddb 1075 */
f7d7b7a7 1076 if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)
a68bbddb
JA
1077 return;
1078
dd67d051 1079 WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
6d048f53 1080 WARN_ON(cfq_cfqq_slice_new(cfqq));
22e2c507
JA
1081
1082 /*
1083 * idle is disabled, either manually or by past process history
1084 */
6d048f53
JA
1085 if (!cfqd->cfq_slice_idle || !cfq_cfqq_idle_window(cfqq))
1086 return;
1087
7b679138
JA
1088 /*
1089 * still requests with the driver, don't idle
1090 */
5ad531db 1091 if (rq_in_driver(cfqd))
7b679138
JA
1092 return;
1093
22e2c507
JA
1094 /*
1095 * task has exited, don't wait
1096 */
206dc69b 1097 cic = cfqd->active_cic;
66dac98e 1098 if (!cic || !atomic_read(&cic->ioc->nr_tasks))
6d048f53
JA
1099 return;
1100
355b659c
CZ
1101 /*
1102 * If our average think time is larger than the remaining time
1103 * slice, then don't idle. This avoids overrunning the allotted
1104 * time slice.
1105 */
1106 if (sample_valid(cic->ttime_samples) &&
1107 (cfqq->slice_end - jiffies < cic->ttime_mean))
1108 return;
1109
3b18152c 1110 cfq_mark_cfqq_wait_request(cfqq);
22e2c507 1111
206dc69b
JA
1112 /*
1113 * we don't want to idle for seeks, but we do want to allow
1114 * fair distribution of slice time for a process doing back-to-back
1115 * seeks. so allow a little bit of time for him to submit a new rq
1116 */
6d048f53 1117 sl = cfqd->cfq_slice_idle;
caaa5f9f 1118 if (sample_valid(cic->seek_samples) && CIC_SEEKY(cic))
d9e7620e 1119 sl = min(sl, msecs_to_jiffies(CFQ_MIN_TT));
206dc69b 1120
7b14e3b5 1121 mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
9481ffdc 1122 cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu", sl);
1da177e4
LT
1123}
1124
498d3aa2
JA
1125/*
1126 * Move request from internal lists to the request queue dispatch list.
1127 */
165125e1 1128static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
1da177e4 1129{
3ed9a296 1130 struct cfq_data *cfqd = q->elevator->elevator_data;
5e705374 1131 struct cfq_queue *cfqq = RQ_CFQQ(rq);
22e2c507 1132
7b679138
JA
1133 cfq_log_cfqq(cfqd, cfqq, "dispatch_insert");
1134
06d21886 1135 cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq);
5380a101 1136 cfq_remove_request(rq);
6d048f53 1137 cfqq->dispatched++;
5380a101 1138 elv_dispatch_sort(q, rq);
3ed9a296
JA
1139
1140 if (cfq_cfqq_sync(cfqq))
1141 cfqd->sync_flight++;
1da177e4
LT
1142}
1143
1144/*
1145 * return expired entry, or NULL to just start from scratch in rbtree
1146 */
febffd61 1147static struct request *cfq_check_fifo(struct cfq_queue *cfqq)
1da177e4 1148{
30996f40 1149 struct request *rq = NULL;
1da177e4 1150
3b18152c 1151 if (cfq_cfqq_fifo_expire(cfqq))
1da177e4 1152 return NULL;
cb887411
JA
1153
1154 cfq_mark_cfqq_fifo_expire(cfqq);
1155
89850f7e
JA
1156 if (list_empty(&cfqq->fifo))
1157 return NULL;
1da177e4 1158
89850f7e 1159 rq = rq_entry_fifo(cfqq->fifo.next);
30996f40 1160 if (time_before(jiffies, rq_fifo_time(rq)))
7b679138 1161 rq = NULL;
1da177e4 1162
30996f40 1163 cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq);
6d048f53 1164 return rq;
1da177e4
LT
1165}
1166
22e2c507
JA
1167static inline int
1168cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1169{
1170 const int base_rq = cfqd->cfq_slice_async_rq;
1da177e4 1171
22e2c507 1172 WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR);
1da177e4 1173
22e2c507 1174 return 2 * (base_rq + base_rq * (CFQ_PRIO_LISTS - 1 - cfqq->ioprio));
1da177e4
LT
1175}
1176
22e2c507 1177/*
498d3aa2
JA
1178 * Select a queue for service. If we have a current active queue,
1179 * check whether to continue servicing it, or retrieve and set a new one.
22e2c507 1180 */
1b5ed5e1 1181static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
1da177e4 1182{
a36e71f9 1183 struct cfq_queue *cfqq, *new_cfqq = NULL;
1da177e4 1184
22e2c507
JA
1185 cfqq = cfqd->active_queue;
1186 if (!cfqq)
1187 goto new_queue;
1da177e4 1188
22e2c507 1189 /*
6d048f53 1190 * The active queue has run out of time, expire it and select new.
22e2c507 1191 */
b029195d 1192 if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq))
3b18152c 1193 goto expire;
1da177e4 1194
22e2c507 1195 /*
6d048f53
JA
1196 * The active queue has requests and isn't expired, allow it to
1197 * dispatch.
22e2c507 1198 */
dd67d051 1199 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
22e2c507 1200 goto keep_queue;
6d048f53 1201
a36e71f9
JA
1202 /*
1203 * If another queue has a request waiting within our mean seek
1204 * distance, let it run. The expire code will check for close
1205 * cooperators and put the close queue at the front of the service
1206 * tree.
1207 */
1208 new_cfqq = cfq_close_cooperator(cfqd, cfqq, 0);
1209 if (new_cfqq)
1210 goto expire;
1211
6d048f53
JA
1212 /*
1213 * No requests pending. If the active queue still has requests in
1214 * flight or is idling for a new request, allow either of these
1215 * conditions to happen (or time out) before selecting a new queue.
1216 */
cc197479
JA
1217 if (timer_pending(&cfqd->idle_slice_timer) ||
1218 (cfqq->dispatched && cfq_cfqq_idle_window(cfqq))) {
caaa5f9f
JA
1219 cfqq = NULL;
1220 goto keep_queue;
22e2c507
JA
1221 }
1222
3b18152c 1223expire:
6084cdda 1224 cfq_slice_expired(cfqd, 0);
3b18152c 1225new_queue:
a36e71f9 1226 cfqq = cfq_set_active_queue(cfqd, new_cfqq);
22e2c507 1227keep_queue:
3b18152c 1228 return cfqq;
22e2c507
JA
1229}
1230
febffd61 1231static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq)
d9e7620e
JA
1232{
1233 int dispatched = 0;
1234
1235 while (cfqq->next_rq) {
1236 cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq);
1237 dispatched++;
1238 }
1239
1240 BUG_ON(!list_empty(&cfqq->fifo));
1241 return dispatched;
1242}
1243
498d3aa2
JA
1244/*
1245 * Drain our current requests. Used for barriers and when switching
1246 * io schedulers on-the-fly.
1247 */
d9e7620e 1248static int cfq_forced_dispatch(struct cfq_data *cfqd)
1b5ed5e1 1249{
0871714e 1250 struct cfq_queue *cfqq;
d9e7620e 1251 int dispatched = 0;
1b5ed5e1 1252
0871714e 1253 while ((cfqq = cfq_rb_first(&cfqd->service_tree)) != NULL)
d9e7620e 1254 dispatched += __cfq_forced_dispatch_cfqq(cfqq);
1b5ed5e1 1255
6084cdda 1256 cfq_slice_expired(cfqd, 0);
1b5ed5e1
TH
1257
1258 BUG_ON(cfqd->busy_queues);
1259
6923715a 1260 cfq_log(cfqd, "forced_dispatch=%d", dispatched);
1b5ed5e1
TH
1261 return dispatched;
1262}
1263
0b182d61 1264static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2f5cb738 1265{
2f5cb738 1266 unsigned int max_dispatch;
22e2c507 1267
5ad531db
JA
1268 /*
1269 * Drain async requests before we start sync IO
1270 */
1271 if (cfq_cfqq_idle_window(cfqq) && cfqd->rq_in_driver[BLK_RW_ASYNC])
0b182d61 1272 return false;
5ad531db 1273
2f5cb738
JA
1274 /*
1275 * If this is an async queue and we have sync IO in flight, let it wait
1276 */
1277 if (cfqd->sync_flight && !cfq_cfqq_sync(cfqq))
0b182d61 1278 return false;
2f5cb738
JA
1279
1280 max_dispatch = cfqd->cfq_quantum;
1281 if (cfq_class_idle(cfqq))
1282 max_dispatch = 1;
b4878f24 1283
2f5cb738
JA
1284 /*
1285 * Does this cfqq already have too much IO in flight?
1286 */
1287 if (cfqq->dispatched >= max_dispatch) {
1288 /*
1289 * idle queue must always only have a single IO in flight
1290 */
3ed9a296 1291 if (cfq_class_idle(cfqq))
0b182d61 1292 return false;
3ed9a296 1293
2f5cb738
JA
1294 /*
1295 * We have other queues, don't allow more IO from this one
1296 */
1297 if (cfqd->busy_queues > 1)
0b182d61 1298 return false;
9ede209e 1299
365722bb 1300 /*
8e296755 1301 * Sole queue user, allow bigger slice
365722bb 1302 */
8e296755
JA
1303 max_dispatch *= 4;
1304 }
1305
1306 /*
1307 * Async queues must wait a bit before being allowed dispatch.
1308 * We also ramp up the dispatch depth gradually for async IO,
1309 * based on the last sync IO we serviced
1310 */
963b72fc 1311 if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) {
8e296755
JA
1312 unsigned long last_sync = jiffies - cfqd->last_end_sync_rq;
1313 unsigned int depth;
365722bb 1314
61f0c1dc 1315 depth = last_sync / cfqd->cfq_slice[1];
e00c54c3
JA
1316 if (!depth && !cfqq->dispatched)
1317 depth = 1;
8e296755
JA
1318 if (depth < max_dispatch)
1319 max_dispatch = depth;
2f5cb738 1320 }
3ed9a296 1321
0b182d61
JA
1322 /*
1323 * If we're below the current max, allow a dispatch
1324 */
1325 return cfqq->dispatched < max_dispatch;
1326}
1327
1328/*
1329 * Dispatch a request from cfqq, moving them to the request queue
1330 * dispatch list.
1331 */
1332static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1333{
1334 struct request *rq;
1335
1336 BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list));
1337
1338 if (!cfq_may_dispatch(cfqd, cfqq))
1339 return false;
1340
1341 /*
1342 * follow expired path, else get first next available
1343 */
1344 rq = cfq_check_fifo(cfqq);
1345 if (!rq)
1346 rq = cfqq->next_rq;
1347
1348 /*
1349 * insert request into driver dispatch list
1350 */
1351 cfq_dispatch_insert(cfqd->queue, rq);
1352
1353 if (!cfqd->active_cic) {
1354 struct cfq_io_context *cic = RQ_CIC(rq);
1355
1356 atomic_long_inc(&cic->ioc->refcount);
1357 cfqd->active_cic = cic;
1358 }
1359
1360 return true;
1361}
1362
1363/*
1364 * Find the cfqq that we need to service and move a request from that to the
1365 * dispatch list
1366 */
1367static int cfq_dispatch_requests(struct request_queue *q, int force)
1368{
1369 struct cfq_data *cfqd = q->elevator->elevator_data;
1370 struct cfq_queue *cfqq;
1371
1372 if (!cfqd->busy_queues)
1373 return 0;
1374
1375 if (unlikely(force))
1376 return cfq_forced_dispatch(cfqd);
1377
1378 cfqq = cfq_select_queue(cfqd);
1379 if (!cfqq)
8e296755
JA
1380 return 0;
1381
2f5cb738 1382 /*
0b182d61 1383 * Dispatch a request from this cfqq, if it is allowed
2f5cb738 1384 */
0b182d61
JA
1385 if (!cfq_dispatch_request(cfqd, cfqq))
1386 return 0;
1387
2f5cb738 1388 cfqq->slice_dispatch++;
b029195d 1389 cfq_clear_cfqq_must_dispatch(cfqq);
22e2c507 1390
2f5cb738
JA
1391 /*
1392 * expire an async queue immediately if it has used up its slice. idle
1393 * queue always expire after 1 dispatch round.
1394 */
1395 if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) &&
1396 cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) ||
1397 cfq_class_idle(cfqq))) {
1398 cfqq->slice_end = jiffies + 1;
1399 cfq_slice_expired(cfqd, 0);
1da177e4
LT
1400 }
1401
b217a903 1402 cfq_log_cfqq(cfqd, cfqq, "dispatched a request");
2f5cb738 1403 return 1;
1da177e4
LT
1404}
1405
1da177e4 1406/*
5e705374
JA
1407 * task holds one reference to the queue, dropped when task exits. each rq
1408 * in-flight on this queue also holds a reference, dropped when rq is freed.
1da177e4
LT
1409 *
1410 * queue lock must be held here.
1411 */
1412static void cfq_put_queue(struct cfq_queue *cfqq)
1413{
22e2c507
JA
1414 struct cfq_data *cfqd = cfqq->cfqd;
1415
1416 BUG_ON(atomic_read(&cfqq->ref) <= 0);
1da177e4
LT
1417
1418 if (!atomic_dec_and_test(&cfqq->ref))
1419 return;
1420
7b679138 1421 cfq_log_cfqq(cfqd, cfqq, "put_queue");
1da177e4 1422 BUG_ON(rb_first(&cfqq->sort_list));
22e2c507 1423 BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]);
3b18152c 1424 BUG_ON(cfq_cfqq_on_rr(cfqq));
1da177e4 1425
28f95cbc 1426 if (unlikely(cfqd->active_queue == cfqq)) {
6084cdda 1427 __cfq_slice_expired(cfqd, cfqq, 0);
23e018a1 1428 cfq_schedule_dispatch(cfqd);
28f95cbc 1429 }
22e2c507 1430
1da177e4
LT
1431 kmem_cache_free(cfq_pool, cfqq);
1432}
1433
d6de8be7
JA
1434/*
1435 * Must always be called with the rcu_read_lock() held
1436 */
07416d29
JA
1437static void
1438__call_for_each_cic(struct io_context *ioc,
1439 void (*func)(struct io_context *, struct cfq_io_context *))
1440{
1441 struct cfq_io_context *cic;
1442 struct hlist_node *n;
1443
1444 hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list)
1445 func(ioc, cic);
1446}
1447
4ac845a2 1448/*
34e6bbf2 1449 * Call func for each cic attached to this ioc.
4ac845a2 1450 */
34e6bbf2 1451static void
4ac845a2
JA
1452call_for_each_cic(struct io_context *ioc,
1453 void (*func)(struct io_context *, struct cfq_io_context *))
1da177e4 1454{
4ac845a2 1455 rcu_read_lock();
07416d29 1456 __call_for_each_cic(ioc, func);
4ac845a2 1457 rcu_read_unlock();
34e6bbf2
FC
1458}
1459
1460static void cfq_cic_free_rcu(struct rcu_head *head)
1461{
1462 struct cfq_io_context *cic;
1463
1464 cic = container_of(head, struct cfq_io_context, rcu_head);
1465
1466 kmem_cache_free(cfq_ioc_pool, cic);
245b2e70 1467 elv_ioc_count_dec(cfq_ioc_count);
34e6bbf2 1468
9a11b4ed
JA
1469 if (ioc_gone) {
1470 /*
1471 * CFQ scheduler is exiting, grab exit lock and check
1472 * the pending io context count. If it hits zero,
1473 * complete ioc_gone and set it back to NULL
1474 */
1475 spin_lock(&ioc_gone_lock);
245b2e70 1476 if (ioc_gone && !elv_ioc_count_read(cfq_ioc_count)) {
9a11b4ed
JA
1477 complete(ioc_gone);
1478 ioc_gone = NULL;
1479 }
1480 spin_unlock(&ioc_gone_lock);
1481 }
34e6bbf2 1482}
4ac845a2 1483
34e6bbf2
FC
1484static void cfq_cic_free(struct cfq_io_context *cic)
1485{
1486 call_rcu(&cic->rcu_head, cfq_cic_free_rcu);
4ac845a2
JA
1487}
1488
1489static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic)
1490{
1491 unsigned long flags;
1492
1493 BUG_ON(!cic->dead_key);
1494
1495 spin_lock_irqsave(&ioc->lock, flags);
1496 radix_tree_delete(&ioc->radix_root, cic->dead_key);
ffc4e759 1497 hlist_del_rcu(&cic->cic_list);
4ac845a2
JA
1498 spin_unlock_irqrestore(&ioc->lock, flags);
1499
34e6bbf2 1500 cfq_cic_free(cic);
4ac845a2
JA
1501}
1502
d6de8be7
JA
1503/*
1504 * Must be called with rcu_read_lock() held or preemption otherwise disabled.
1505 * Only two callers of this - ->dtor() which is called with the rcu_read_lock(),
1506 * and ->trim() which is called with the task lock held
1507 */
4ac845a2
JA
1508static void cfq_free_io_context(struct io_context *ioc)
1509{
4ac845a2 1510 /*
34e6bbf2
FC
1511 * ioc->refcount is zero here, or we are called from elv_unregister(),
1512 * so no more cic's are allowed to be linked into this ioc. So it
1513 * should be ok to iterate over the known list, we will see all cic's
1514 * since no new ones are added.
4ac845a2 1515 */
07416d29 1516 __call_for_each_cic(ioc, cic_free_func);
1da177e4
LT
1517}
1518
89850f7e 1519static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq)
1da177e4 1520{
28f95cbc 1521 if (unlikely(cfqq == cfqd->active_queue)) {
6084cdda 1522 __cfq_slice_expired(cfqd, cfqq, 0);
23e018a1 1523 cfq_schedule_dispatch(cfqd);
28f95cbc 1524 }
22e2c507 1525
89850f7e
JA
1526 cfq_put_queue(cfqq);
1527}
22e2c507 1528
89850f7e
JA
1529static void __cfq_exit_single_io_context(struct cfq_data *cfqd,
1530 struct cfq_io_context *cic)
1531{
4faa3c81
FC
1532 struct io_context *ioc = cic->ioc;
1533
fc46379d 1534 list_del_init(&cic->queue_list);
4ac845a2
JA
1535
1536 /*
1537 * Make sure key == NULL is seen for dead queues
1538 */
fc46379d 1539 smp_wmb();
4ac845a2 1540 cic->dead_key = (unsigned long) cic->key;
fc46379d
JA
1541 cic->key = NULL;
1542
4faa3c81
FC
1543 if (ioc->ioc_data == cic)
1544 rcu_assign_pointer(ioc->ioc_data, NULL);
1545
ff6657c6
JA
1546 if (cic->cfqq[BLK_RW_ASYNC]) {
1547 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]);
1548 cic->cfqq[BLK_RW_ASYNC] = NULL;
12a05732
AV
1549 }
1550
ff6657c6
JA
1551 if (cic->cfqq[BLK_RW_SYNC]) {
1552 cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]);
1553 cic->cfqq[BLK_RW_SYNC] = NULL;
12a05732 1554 }
89850f7e
JA
1555}
1556
4ac845a2
JA
1557static void cfq_exit_single_io_context(struct io_context *ioc,
1558 struct cfq_io_context *cic)
89850f7e
JA
1559{
1560 struct cfq_data *cfqd = cic->key;
1561
89850f7e 1562 if (cfqd) {
165125e1 1563 struct request_queue *q = cfqd->queue;
4ac845a2 1564 unsigned long flags;
89850f7e 1565
4ac845a2 1566 spin_lock_irqsave(q->queue_lock, flags);
62c1fe9d
JA
1567
1568 /*
1569 * Ensure we get a fresh copy of the ->key to prevent
1570 * race between exiting task and queue
1571 */
1572 smp_read_barrier_depends();
1573 if (cic->key)
1574 __cfq_exit_single_io_context(cfqd, cic);
1575
4ac845a2 1576 spin_unlock_irqrestore(q->queue_lock, flags);
89850f7e 1577 }
1da177e4
LT
1578}
1579
498d3aa2
JA
1580/*
1581 * The process that ioc belongs to has exited, we need to clean up
1582 * and put the internal structures we have that belongs to that process.
1583 */
e2d74ac0 1584static void cfq_exit_io_context(struct io_context *ioc)
1da177e4 1585{
4ac845a2 1586 call_for_each_cic(ioc, cfq_exit_single_io_context);
1da177e4
LT
1587}
1588
22e2c507 1589static struct cfq_io_context *
8267e268 1590cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
1da177e4 1591{
b5deef90 1592 struct cfq_io_context *cic;
1da177e4 1593
94f6030c
CL
1594 cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask | __GFP_ZERO,
1595 cfqd->queue->node);
1da177e4 1596 if (cic) {
22e2c507 1597 cic->last_end_request = jiffies;
553698f9 1598 INIT_LIST_HEAD(&cic->queue_list);
ffc4e759 1599 INIT_HLIST_NODE(&cic->cic_list);
22e2c507
JA
1600 cic->dtor = cfq_free_io_context;
1601 cic->exit = cfq_exit_io_context;
245b2e70 1602 elv_ioc_count_inc(cfq_ioc_count);
1da177e4
LT
1603 }
1604
1605 return cic;
1606}
1607
fd0928df 1608static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc)
22e2c507
JA
1609{
1610 struct task_struct *tsk = current;
1611 int ioprio_class;
1612
3b18152c 1613 if (!cfq_cfqq_prio_changed(cfqq))
22e2c507
JA
1614 return;
1615
fd0928df 1616 ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio);
22e2c507 1617 switch (ioprio_class) {
fe094d98
JA
1618 default:
1619 printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class);
1620 case IOPRIO_CLASS_NONE:
1621 /*
6d63c275 1622 * no prio set, inherit CPU scheduling settings
fe094d98
JA
1623 */
1624 cfqq->ioprio = task_nice_ioprio(tsk);
6d63c275 1625 cfqq->ioprio_class = task_nice_ioclass(tsk);
fe094d98
JA
1626 break;
1627 case IOPRIO_CLASS_RT:
1628 cfqq->ioprio = task_ioprio(ioc);
1629 cfqq->ioprio_class = IOPRIO_CLASS_RT;
1630 break;
1631 case IOPRIO_CLASS_BE:
1632 cfqq->ioprio = task_ioprio(ioc);
1633 cfqq->ioprio_class = IOPRIO_CLASS_BE;
1634 break;
1635 case IOPRIO_CLASS_IDLE:
1636 cfqq->ioprio_class = IOPRIO_CLASS_IDLE;
1637 cfqq->ioprio = 7;
1638 cfq_clear_cfqq_idle_window(cfqq);
1639 break;
22e2c507
JA
1640 }
1641
1642 /*
1643 * keep track of original prio settings in case we have to temporarily
1644 * elevate the priority of this queue
1645 */
1646 cfqq->org_ioprio = cfqq->ioprio;
1647 cfqq->org_ioprio_class = cfqq->ioprio_class;
3b18152c 1648 cfq_clear_cfqq_prio_changed(cfqq);
22e2c507
JA
1649}
1650
febffd61 1651static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic)
22e2c507 1652{
478a82b0
AV
1653 struct cfq_data *cfqd = cic->key;
1654 struct cfq_queue *cfqq;
c1b707d2 1655 unsigned long flags;
35e6077c 1656
caaa5f9f
JA
1657 if (unlikely(!cfqd))
1658 return;
1659
c1b707d2 1660 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
caaa5f9f 1661
ff6657c6 1662 cfqq = cic->cfqq[BLK_RW_ASYNC];
caaa5f9f
JA
1663 if (cfqq) {
1664 struct cfq_queue *new_cfqq;
ff6657c6
JA
1665 new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->ioc,
1666 GFP_ATOMIC);
caaa5f9f 1667 if (new_cfqq) {
ff6657c6 1668 cic->cfqq[BLK_RW_ASYNC] = new_cfqq;
caaa5f9f
JA
1669 cfq_put_queue(cfqq);
1670 }
22e2c507 1671 }
caaa5f9f 1672
ff6657c6 1673 cfqq = cic->cfqq[BLK_RW_SYNC];
caaa5f9f
JA
1674 if (cfqq)
1675 cfq_mark_cfqq_prio_changed(cfqq);
1676
c1b707d2 1677 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
22e2c507
JA
1678}
1679
fc46379d 1680static void cfq_ioc_set_ioprio(struct io_context *ioc)
22e2c507 1681{
4ac845a2 1682 call_for_each_cic(ioc, changed_ioprio);
fc46379d 1683 ioc->ioprio_changed = 0;
22e2c507
JA
1684}
1685
d5036d77 1686static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq,
a6151c3a 1687 pid_t pid, bool is_sync)
d5036d77
JA
1688{
1689 RB_CLEAR_NODE(&cfqq->rb_node);
1690 RB_CLEAR_NODE(&cfqq->p_node);
1691 INIT_LIST_HEAD(&cfqq->fifo);
1692
1693 atomic_set(&cfqq->ref, 0);
1694 cfqq->cfqd = cfqd;
1695
1696 cfq_mark_cfqq_prio_changed(cfqq);
1697
1698 if (is_sync) {
1699 if (!cfq_class_idle(cfqq))
1700 cfq_mark_cfqq_idle_window(cfqq);
1701 cfq_mark_cfqq_sync(cfqq);
1702 }
1703 cfqq->pid = pid;
1704}
1705
22e2c507 1706static struct cfq_queue *
a6151c3a 1707cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync,
fd0928df 1708 struct io_context *ioc, gfp_t gfp_mask)
22e2c507 1709{
22e2c507 1710 struct cfq_queue *cfqq, *new_cfqq = NULL;
91fac317 1711 struct cfq_io_context *cic;
22e2c507
JA
1712
1713retry:
4ac845a2 1714 cic = cfq_cic_lookup(cfqd, ioc);
91fac317
VT
1715 /* cic always exists here */
1716 cfqq = cic_to_cfqq(cic, is_sync);
22e2c507 1717
6118b70b
JA
1718 /*
1719 * Always try a new alloc if we fell back to the OOM cfqq
1720 * originally, since it should just be a temporary situation.
1721 */
1722 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
1723 cfqq = NULL;
22e2c507
JA
1724 if (new_cfqq) {
1725 cfqq = new_cfqq;
1726 new_cfqq = NULL;
1727 } else if (gfp_mask & __GFP_WAIT) {
1728 spin_unlock_irq(cfqd->queue->queue_lock);
94f6030c 1729 new_cfqq = kmem_cache_alloc_node(cfq_pool,
6118b70b 1730 gfp_mask | __GFP_ZERO,
94f6030c 1731 cfqd->queue->node);
22e2c507 1732 spin_lock_irq(cfqd->queue->queue_lock);
6118b70b
JA
1733 if (new_cfqq)
1734 goto retry;
22e2c507 1735 } else {
94f6030c
CL
1736 cfqq = kmem_cache_alloc_node(cfq_pool,
1737 gfp_mask | __GFP_ZERO,
1738 cfqd->queue->node);
22e2c507
JA
1739 }
1740
6118b70b
JA
1741 if (cfqq) {
1742 cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync);
1743 cfq_init_prio_data(cfqq, ioc);
1744 cfq_log_cfqq(cfqd, cfqq, "alloced");
1745 } else
1746 cfqq = &cfqd->oom_cfqq;
22e2c507
JA
1747 }
1748
1749 if (new_cfqq)
1750 kmem_cache_free(cfq_pool, new_cfqq);
1751
22e2c507
JA
1752 return cfqq;
1753}
1754
c2dea2d1
VT
1755static struct cfq_queue **
1756cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio)
1757{
fe094d98 1758 switch (ioprio_class) {
c2dea2d1
VT
1759 case IOPRIO_CLASS_RT:
1760 return &cfqd->async_cfqq[0][ioprio];
1761 case IOPRIO_CLASS_BE:
1762 return &cfqd->async_cfqq[1][ioprio];
1763 case IOPRIO_CLASS_IDLE:
1764 return &cfqd->async_idle_cfqq;
1765 default:
1766 BUG();
1767 }
1768}
1769
15c31be4 1770static struct cfq_queue *
a6151c3a 1771cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct io_context *ioc,
15c31be4
JA
1772 gfp_t gfp_mask)
1773{
fd0928df
JA
1774 const int ioprio = task_ioprio(ioc);
1775 const int ioprio_class = task_ioprio_class(ioc);
c2dea2d1 1776 struct cfq_queue **async_cfqq = NULL;
15c31be4
JA
1777 struct cfq_queue *cfqq = NULL;
1778
c2dea2d1
VT
1779 if (!is_sync) {
1780 async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio);
1781 cfqq = *async_cfqq;
1782 }
1783
6118b70b 1784 if (!cfqq)
fd0928df 1785 cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask);
15c31be4
JA
1786
1787 /*
1788 * pin the queue now that it's allocated, scheduler exit will prune it
1789 */
c2dea2d1 1790 if (!is_sync && !(*async_cfqq)) {
15c31be4 1791 atomic_inc(&cfqq->ref);
c2dea2d1 1792 *async_cfqq = cfqq;
15c31be4
JA
1793 }
1794
1795 atomic_inc(&cfqq->ref);
1796 return cfqq;
1797}
1798
498d3aa2
JA
1799/*
1800 * We drop cfq io contexts lazily, so we may find a dead one.
1801 */
dbecf3ab 1802static void
4ac845a2
JA
1803cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc,
1804 struct cfq_io_context *cic)
dbecf3ab 1805{
4ac845a2
JA
1806 unsigned long flags;
1807
fc46379d 1808 WARN_ON(!list_empty(&cic->queue_list));
597bc485 1809
4ac845a2
JA
1810 spin_lock_irqsave(&ioc->lock, flags);
1811
4faa3c81 1812 BUG_ON(ioc->ioc_data == cic);
597bc485 1813
4ac845a2 1814 radix_tree_delete(&ioc->radix_root, (unsigned long) cfqd);
ffc4e759 1815 hlist_del_rcu(&cic->cic_list);
4ac845a2
JA
1816 spin_unlock_irqrestore(&ioc->lock, flags);
1817
1818 cfq_cic_free(cic);
dbecf3ab
OH
1819}
1820
e2d74ac0 1821static struct cfq_io_context *
4ac845a2 1822cfq_cic_lookup(struct cfq_data *cfqd, struct io_context *ioc)
e2d74ac0 1823{
e2d74ac0 1824 struct cfq_io_context *cic;
d6de8be7 1825 unsigned long flags;
4ac845a2 1826 void *k;
e2d74ac0 1827
91fac317
VT
1828 if (unlikely(!ioc))
1829 return NULL;
1830
d6de8be7
JA
1831 rcu_read_lock();
1832
597bc485
JA
1833 /*
1834 * we maintain a last-hit cache, to avoid browsing over the tree
1835 */
4ac845a2 1836 cic = rcu_dereference(ioc->ioc_data);
d6de8be7
JA
1837 if (cic && cic->key == cfqd) {
1838 rcu_read_unlock();
597bc485 1839 return cic;
d6de8be7 1840 }
597bc485 1841
4ac845a2 1842 do {
4ac845a2
JA
1843 cic = radix_tree_lookup(&ioc->radix_root, (unsigned long) cfqd);
1844 rcu_read_unlock();
1845 if (!cic)
1846 break;
be3b0753
OH
1847 /* ->key must be copied to avoid race with cfq_exit_queue() */
1848 k = cic->key;
1849 if (unlikely(!k)) {
4ac845a2 1850 cfq_drop_dead_cic(cfqd, ioc, cic);
d6de8be7 1851 rcu_read_lock();
4ac845a2 1852 continue;
dbecf3ab 1853 }
e2d74ac0 1854
d6de8be7 1855 spin_lock_irqsave(&ioc->lock, flags);
4ac845a2 1856 rcu_assign_pointer(ioc->ioc_data, cic);
d6de8be7 1857 spin_unlock_irqrestore(&ioc->lock, flags);
4ac845a2
JA
1858 break;
1859 } while (1);
e2d74ac0 1860
4ac845a2 1861 return cic;
e2d74ac0
JA
1862}
1863
4ac845a2
JA
1864/*
1865 * Add cic into ioc, using cfqd as the search key. This enables us to lookup
1866 * the process specific cfq io context when entered from the block layer.
1867 * Also adds the cic to a per-cfqd list, used when this queue is removed.
1868 */
febffd61
JA
1869static int cfq_cic_link(struct cfq_data *cfqd, struct io_context *ioc,
1870 struct cfq_io_context *cic, gfp_t gfp_mask)
e2d74ac0 1871{
0261d688 1872 unsigned long flags;
4ac845a2 1873 int ret;
e2d74ac0 1874
4ac845a2
JA
1875 ret = radix_tree_preload(gfp_mask);
1876 if (!ret) {
1877 cic->ioc = ioc;
1878 cic->key = cfqd;
e2d74ac0 1879
4ac845a2
JA
1880 spin_lock_irqsave(&ioc->lock, flags);
1881 ret = radix_tree_insert(&ioc->radix_root,
1882 (unsigned long) cfqd, cic);
ffc4e759
JA
1883 if (!ret)
1884 hlist_add_head_rcu(&cic->cic_list, &ioc->cic_list);
4ac845a2 1885 spin_unlock_irqrestore(&ioc->lock, flags);
e2d74ac0 1886
4ac845a2
JA
1887 radix_tree_preload_end();
1888
1889 if (!ret) {
1890 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
1891 list_add(&cic->queue_list, &cfqd->cic_list);
1892 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
1893 }
e2d74ac0
JA
1894 }
1895
4ac845a2
JA
1896 if (ret)
1897 printk(KERN_ERR "cfq: cic link failed!\n");
fc46379d 1898
4ac845a2 1899 return ret;
e2d74ac0
JA
1900}
1901
1da177e4
LT
1902/*
1903 * Setup general io context and cfq io context. There can be several cfq
1904 * io contexts per general io context, if this process is doing io to more
e2d74ac0 1905 * than one device managed by cfq.
1da177e4
LT
1906 */
1907static struct cfq_io_context *
e2d74ac0 1908cfq_get_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
1da177e4 1909{
22e2c507 1910 struct io_context *ioc = NULL;
1da177e4 1911 struct cfq_io_context *cic;
1da177e4 1912
22e2c507 1913 might_sleep_if(gfp_mask & __GFP_WAIT);
1da177e4 1914
b5deef90 1915 ioc = get_io_context(gfp_mask, cfqd->queue->node);
1da177e4
LT
1916 if (!ioc)
1917 return NULL;
1918
4ac845a2 1919 cic = cfq_cic_lookup(cfqd, ioc);
e2d74ac0
JA
1920 if (cic)
1921 goto out;
1da177e4 1922
e2d74ac0
JA
1923 cic = cfq_alloc_io_context(cfqd, gfp_mask);
1924 if (cic == NULL)
1925 goto err;
1da177e4 1926
4ac845a2
JA
1927 if (cfq_cic_link(cfqd, ioc, cic, gfp_mask))
1928 goto err_free;
1929
1da177e4 1930out:
fc46379d
JA
1931 smp_read_barrier_depends();
1932 if (unlikely(ioc->ioprio_changed))
1933 cfq_ioc_set_ioprio(ioc);
1934
1da177e4 1935 return cic;
4ac845a2
JA
1936err_free:
1937 cfq_cic_free(cic);
1da177e4
LT
1938err:
1939 put_io_context(ioc);
1940 return NULL;
1941}
1942
22e2c507
JA
1943static void
1944cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_io_context *cic)
1da177e4 1945{
aaf1228d
JA
1946 unsigned long elapsed = jiffies - cic->last_end_request;
1947 unsigned long ttime = min(elapsed, 2UL * cfqd->cfq_slice_idle);
db3b5848 1948
22e2c507
JA
1949 cic->ttime_samples = (7*cic->ttime_samples + 256) / 8;
1950 cic->ttime_total = (7*cic->ttime_total + 256*ttime) / 8;
1951 cic->ttime_mean = (cic->ttime_total + 128) / cic->ttime_samples;
1952}
1da177e4 1953
206dc69b 1954static void
6d048f53
JA
1955cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_io_context *cic,
1956 struct request *rq)
206dc69b
JA
1957{
1958 sector_t sdist;
1959 u64 total;
1960
4d00aa47
JM
1961 if (!cic->last_request_pos)
1962 sdist = 0;
83096ebf
TH
1963 else if (cic->last_request_pos < blk_rq_pos(rq))
1964 sdist = blk_rq_pos(rq) - cic->last_request_pos;
206dc69b 1965 else
83096ebf 1966 sdist = cic->last_request_pos - blk_rq_pos(rq);
206dc69b
JA
1967
1968 /*
1969 * Don't allow the seek distance to get too large from the
1970 * odd fragment, pagein, etc
1971 */
1972 if (cic->seek_samples <= 60) /* second&third seek */
1973 sdist = min(sdist, (cic->seek_mean * 4) + 2*1024*1024);
1974 else
1975 sdist = min(sdist, (cic->seek_mean * 4) + 2*1024*64);
1976
1977 cic->seek_samples = (7*cic->seek_samples + 256) / 8;
1978 cic->seek_total = (7*cic->seek_total + (u64)256*sdist) / 8;
1979 total = cic->seek_total + (cic->seek_samples/2);
1980 do_div(total, cic->seek_samples);
1981 cic->seek_mean = (sector_t)total;
1982}
1da177e4 1983
22e2c507
JA
1984/*
1985 * Disable idle window if the process thinks too long or seeks so much that
1986 * it doesn't matter
1987 */
1988static void
1989cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
1990 struct cfq_io_context *cic)
1991{
7b679138 1992 int old_idle, enable_idle;
1be92f2f 1993
0871714e
JA
1994 /*
1995 * Don't idle for async or idle io prio class
1996 */
1997 if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq))
1be92f2f
JA
1998 return;
1999
c265a7f4 2000 enable_idle = old_idle = cfq_cfqq_idle_window(cfqq);
1da177e4 2001
66dac98e 2002 if (!atomic_read(&cic->ioc->nr_tasks) || !cfqd->cfq_slice_idle ||
963b72fc 2003 (!cfqd->cfq_latency && cfqd->hw_tag && CIC_SEEKY(cic)))
22e2c507
JA
2004 enable_idle = 0;
2005 else if (sample_valid(cic->ttime_samples)) {
ec60e4f6
CZ
2006 unsigned int slice_idle = cfqd->cfq_slice_idle;
2007 if (sample_valid(cic->seek_samples) && CIC_SEEKY(cic))
2008 slice_idle = msecs_to_jiffies(CFQ_MIN_TT);
2009 if (cic->ttime_mean > slice_idle)
22e2c507
JA
2010 enable_idle = 0;
2011 else
2012 enable_idle = 1;
1da177e4
LT
2013 }
2014
7b679138
JA
2015 if (old_idle != enable_idle) {
2016 cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle);
2017 if (enable_idle)
2018 cfq_mark_cfqq_idle_window(cfqq);
2019 else
2020 cfq_clear_cfqq_idle_window(cfqq);
2021 }
22e2c507 2022}
1da177e4 2023
22e2c507
JA
2024/*
2025 * Check if new_cfqq should preempt the currently active queue. Return 0 for
2026 * no or if we aren't sure, a 1 will cause a preempt.
2027 */
a6151c3a 2028static bool
22e2c507 2029cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
5e705374 2030 struct request *rq)
22e2c507 2031{
6d048f53 2032 struct cfq_queue *cfqq;
22e2c507 2033
6d048f53
JA
2034 cfqq = cfqd->active_queue;
2035 if (!cfqq)
a6151c3a 2036 return false;
22e2c507 2037
6d048f53 2038 if (cfq_slice_used(cfqq))
a6151c3a 2039 return true;
6d048f53
JA
2040
2041 if (cfq_class_idle(new_cfqq))
a6151c3a 2042 return false;
22e2c507
JA
2043
2044 if (cfq_class_idle(cfqq))
a6151c3a 2045 return true;
1e3335de 2046
374f84ac
JA
2047 /*
2048 * if the new request is sync, but the currently running queue is
2049 * not, let the sync request have priority.
2050 */
5e705374 2051 if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq))
a6151c3a 2052 return true;
1e3335de 2053
374f84ac
JA
2054 /*
2055 * So both queues are sync. Let the new request get disk time if
2056 * it's a metadata request and the current queue is doing regular IO.
2057 */
2058 if (rq_is_meta(rq) && !cfqq->meta_pending)
e6ec4fe2 2059 return true;
22e2c507 2060
3a9a3f6c
DS
2061 /*
2062 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
2063 */
2064 if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq))
a6151c3a 2065 return true;
3a9a3f6c 2066
1e3335de 2067 if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq))
a6151c3a 2068 return false;
1e3335de
JA
2069
2070 /*
2071 * if this request is as-good as one we would expect from the
2072 * current cfqq, let it preempt
2073 */
4b27e1bb
SL
2074 if (cfq_rq_close(cfqd, rq) && (!cfq_cfqq_coop(new_cfqq) ||
2075 cfqd->busy_queues == 1)) {
2076 /*
2077 * Mark new queue coop_preempt, so its coop flag will not be
2078 * cleared when new queue gets scheduled at the very first time
2079 */
2080 cfq_mark_cfqq_coop_preempt(new_cfqq);
2081 cfq_mark_cfqq_coop(new_cfqq);
a6151c3a 2082 return true;
4b27e1bb 2083 }
1e3335de 2084
a6151c3a 2085 return false;
22e2c507
JA
2086}
2087
2088/*
2089 * cfqq preempts the active queue. if we allowed preempt with no slice left,
2090 * let it have half of its nominal slice.
2091 */
2092static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
2093{
7b679138 2094 cfq_log_cfqq(cfqd, cfqq, "preempt");
6084cdda 2095 cfq_slice_expired(cfqd, 1);
22e2c507 2096
bf572256
JA
2097 /*
2098 * Put the new queue at the front of the of the current list,
2099 * so we know that it will be selected next.
2100 */
2101 BUG_ON(!cfq_cfqq_on_rr(cfqq));
edd75ffd
JA
2102
2103 cfq_service_tree_add(cfqd, cfqq, 1);
bf572256 2104
44f7c160
JA
2105 cfqq->slice_end = 0;
2106 cfq_mark_cfqq_slice_new(cfqq);
22e2c507
JA
2107}
2108
22e2c507 2109/*
5e705374 2110 * Called when a new fs request (rq) is added (to cfqq). Check if there's
22e2c507
JA
2111 * something we should do about it
2112 */
2113static void
5e705374
JA
2114cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
2115 struct request *rq)
22e2c507 2116{
5e705374 2117 struct cfq_io_context *cic = RQ_CIC(rq);
12e9fddd 2118
45333d5a 2119 cfqd->rq_queued++;
374f84ac
JA
2120 if (rq_is_meta(rq))
2121 cfqq->meta_pending++;
2122
9c2c38a1 2123 cfq_update_io_thinktime(cfqd, cic);
6d048f53 2124 cfq_update_io_seektime(cfqd, cic, rq);
9c2c38a1
JA
2125 cfq_update_idle_window(cfqd, cfqq, cic);
2126
83096ebf 2127 cic->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq);
22e2c507
JA
2128
2129 if (cfqq == cfqd->active_queue) {
2130 /*
b029195d
JA
2131 * Remember that we saw a request from this process, but
2132 * don't start queuing just yet. Otherwise we risk seeing lots
2133 * of tiny requests, because we disrupt the normal plugging
d6ceb25e
JA
2134 * and merging. If the request is already larger than a single
2135 * page, let it rip immediately. For that case we assume that
2d870722
JA
2136 * merging is already done. Ditto for a busy system that
2137 * has other work pending, don't risk delaying until the
2138 * idle timer unplug to continue working.
22e2c507 2139 */
d6ceb25e 2140 if (cfq_cfqq_wait_request(cfqq)) {
2d870722
JA
2141 if (blk_rq_bytes(rq) > PAGE_CACHE_SIZE ||
2142 cfqd->busy_queues > 1) {
d6ceb25e 2143 del_timer(&cfqd->idle_slice_timer);
a7f55792 2144 __blk_run_queue(cfqd->queue);
d6ceb25e 2145 }
b029195d 2146 cfq_mark_cfqq_must_dispatch(cfqq);
d6ceb25e 2147 }
5e705374 2148 } else if (cfq_should_preempt(cfqd, cfqq, rq)) {
22e2c507
JA
2149 /*
2150 * not the active queue - expire current slice if it is
2151 * idle and has expired it's mean thinktime or this new queue
3a9a3f6c
DS
2152 * has some old slice time left and is of higher priority or
2153 * this new queue is RT and the current one is BE
22e2c507
JA
2154 */
2155 cfq_preempt_queue(cfqd, cfqq);
a7f55792 2156 __blk_run_queue(cfqd->queue);
22e2c507 2157 }
1da177e4
LT
2158}
2159
165125e1 2160static void cfq_insert_request(struct request_queue *q, struct request *rq)
1da177e4 2161{
b4878f24 2162 struct cfq_data *cfqd = q->elevator->elevator_data;
5e705374 2163 struct cfq_queue *cfqq = RQ_CFQQ(rq);
22e2c507 2164
7b679138 2165 cfq_log_cfqq(cfqd, cfqq, "insert_request");
fd0928df 2166 cfq_init_prio_data(cfqq, RQ_CIC(rq)->ioc);
1da177e4 2167
5e705374 2168 cfq_add_rq_rb(rq);
1da177e4 2169
30996f40 2170 rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]);
22e2c507
JA
2171 list_add_tail(&rq->queuelist, &cfqq->fifo);
2172
5e705374 2173 cfq_rq_enqueued(cfqd, cfqq, rq);
1da177e4
LT
2174}
2175
45333d5a
AC
2176/*
2177 * Update hw_tag based on peak queue depth over 50 samples under
2178 * sufficient load.
2179 */
2180static void cfq_update_hw_tag(struct cfq_data *cfqd)
2181{
5ad531db
JA
2182 if (rq_in_driver(cfqd) > cfqd->rq_in_driver_peak)
2183 cfqd->rq_in_driver_peak = rq_in_driver(cfqd);
45333d5a
AC
2184
2185 if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
5ad531db 2186 rq_in_driver(cfqd) <= CFQ_HW_QUEUE_MIN)
45333d5a
AC
2187 return;
2188
2189 if (cfqd->hw_tag_samples++ < 50)
2190 return;
2191
2192 if (cfqd->rq_in_driver_peak >= CFQ_HW_QUEUE_MIN)
2193 cfqd->hw_tag = 1;
2194 else
2195 cfqd->hw_tag = 0;
2196
2197 cfqd->hw_tag_samples = 0;
2198 cfqd->rq_in_driver_peak = 0;
2199}
2200
165125e1 2201static void cfq_completed_request(struct request_queue *q, struct request *rq)
1da177e4 2202{
5e705374 2203 struct cfq_queue *cfqq = RQ_CFQQ(rq);
b4878f24 2204 struct cfq_data *cfqd = cfqq->cfqd;
5380a101 2205 const int sync = rq_is_sync(rq);
b4878f24 2206 unsigned long now;
1da177e4 2207
b4878f24 2208 now = jiffies;
7b679138 2209 cfq_log_cfqq(cfqd, cfqq, "complete");
1da177e4 2210
45333d5a
AC
2211 cfq_update_hw_tag(cfqd);
2212
5ad531db 2213 WARN_ON(!cfqd->rq_in_driver[sync]);
6d048f53 2214 WARN_ON(!cfqq->dispatched);
5ad531db 2215 cfqd->rq_in_driver[sync]--;
6d048f53 2216 cfqq->dispatched--;
1da177e4 2217
3ed9a296
JA
2218 if (cfq_cfqq_sync(cfqq))
2219 cfqd->sync_flight--;
2220
365722bb 2221 if (sync) {
5e705374 2222 RQ_CIC(rq)->last_end_request = now;
365722bb
VG
2223 cfqd->last_end_sync_rq = now;
2224 }
caaa5f9f
JA
2225
2226 /*
2227 * If this is the active queue, check if it needs to be expired,
2228 * or if we want to idle in case it has no pending requests.
2229 */
2230 if (cfqd->active_queue == cfqq) {
a36e71f9
JA
2231 const bool cfqq_empty = RB_EMPTY_ROOT(&cfqq->sort_list);
2232
44f7c160
JA
2233 if (cfq_cfqq_slice_new(cfqq)) {
2234 cfq_set_prio_slice(cfqd, cfqq);
2235 cfq_clear_cfqq_slice_new(cfqq);
2236 }
a36e71f9
JA
2237 /*
2238 * If there are no requests waiting in this queue, and
2239 * there are other queues ready to issue requests, AND
2240 * those other queues are issuing requests within our
2241 * mean seek distance, give them a chance to run instead
2242 * of idling.
2243 */
0871714e 2244 if (cfq_slice_used(cfqq) || cfq_class_idle(cfqq))
6084cdda 2245 cfq_slice_expired(cfqd, 1);
a36e71f9
JA
2246 else if (cfqq_empty && !cfq_close_cooperator(cfqd, cfqq, 1) &&
2247 sync && !rq_noidle(rq))
6d048f53 2248 cfq_arm_slice_timer(cfqd);
caaa5f9f 2249 }
6d048f53 2250
5ad531db 2251 if (!rq_in_driver(cfqd))
23e018a1 2252 cfq_schedule_dispatch(cfqd);
1da177e4
LT
2253}
2254
22e2c507
JA
2255/*
2256 * we temporarily boost lower priority queues if they are holding fs exclusive
2257 * resources. they are boosted to normal prio (CLASS_BE/4)
2258 */
2259static void cfq_prio_boost(struct cfq_queue *cfqq)
1da177e4 2260{
22e2c507
JA
2261 if (has_fs_excl()) {
2262 /*
2263 * boost idle prio on transactions that would lock out other
2264 * users of the filesystem
2265 */
2266 if (cfq_class_idle(cfqq))
2267 cfqq->ioprio_class = IOPRIO_CLASS_BE;
2268 if (cfqq->ioprio > IOPRIO_NORM)
2269 cfqq->ioprio = IOPRIO_NORM;
2270 } else {
2271 /*
2272 * check if we need to unboost the queue
2273 */
2274 if (cfqq->ioprio_class != cfqq->org_ioprio_class)
2275 cfqq->ioprio_class = cfqq->org_ioprio_class;
2276 if (cfqq->ioprio != cfqq->org_ioprio)
2277 cfqq->ioprio = cfqq->org_ioprio;
2278 }
22e2c507 2279}
1da177e4 2280
89850f7e 2281static inline int __cfq_may_queue(struct cfq_queue *cfqq)
22e2c507 2282{
1b379d8d 2283 if (cfq_cfqq_wait_request(cfqq) && !cfq_cfqq_must_alloc_slice(cfqq)) {
3b18152c 2284 cfq_mark_cfqq_must_alloc_slice(cfqq);
22e2c507 2285 return ELV_MQUEUE_MUST;
3b18152c 2286 }
1da177e4 2287
22e2c507 2288 return ELV_MQUEUE_MAY;
22e2c507
JA
2289}
2290
165125e1 2291static int cfq_may_queue(struct request_queue *q, int rw)
22e2c507
JA
2292{
2293 struct cfq_data *cfqd = q->elevator->elevator_data;
2294 struct task_struct *tsk = current;
91fac317 2295 struct cfq_io_context *cic;
22e2c507
JA
2296 struct cfq_queue *cfqq;
2297
2298 /*
2299 * don't force setup of a queue from here, as a call to may_queue
2300 * does not necessarily imply that a request actually will be queued.
2301 * so just lookup a possibly existing queue, or return 'may queue'
2302 * if that fails
2303 */
4ac845a2 2304 cic = cfq_cic_lookup(cfqd, tsk->io_context);
91fac317
VT
2305 if (!cic)
2306 return ELV_MQUEUE_MAY;
2307
b0b78f81 2308 cfqq = cic_to_cfqq(cic, rw_is_sync(rw));
22e2c507 2309 if (cfqq) {
fd0928df 2310 cfq_init_prio_data(cfqq, cic->ioc);
22e2c507
JA
2311 cfq_prio_boost(cfqq);
2312
89850f7e 2313 return __cfq_may_queue(cfqq);
22e2c507
JA
2314 }
2315
2316 return ELV_MQUEUE_MAY;
1da177e4
LT
2317}
2318
1da177e4
LT
2319/*
2320 * queue lock held here
2321 */
bb37b94c 2322static void cfq_put_request(struct request *rq)
1da177e4 2323{
5e705374 2324 struct cfq_queue *cfqq = RQ_CFQQ(rq);
1da177e4 2325
5e705374 2326 if (cfqq) {
22e2c507 2327 const int rw = rq_data_dir(rq);
1da177e4 2328
22e2c507
JA
2329 BUG_ON(!cfqq->allocated[rw]);
2330 cfqq->allocated[rw]--;
1da177e4 2331
5e705374 2332 put_io_context(RQ_CIC(rq)->ioc);
1da177e4 2333
1da177e4 2334 rq->elevator_private = NULL;
5e705374 2335 rq->elevator_private2 = NULL;
1da177e4 2336
1da177e4
LT
2337 cfq_put_queue(cfqq);
2338 }
2339}
2340
2341/*
22e2c507 2342 * Allocate cfq data structures associated with this request.
1da177e4 2343 */
22e2c507 2344static int
165125e1 2345cfq_set_request(struct request_queue *q, struct request *rq, gfp_t gfp_mask)
1da177e4
LT
2346{
2347 struct cfq_data *cfqd = q->elevator->elevator_data;
2348 struct cfq_io_context *cic;
2349 const int rw = rq_data_dir(rq);
a6151c3a 2350 const bool is_sync = rq_is_sync(rq);
22e2c507 2351 struct cfq_queue *cfqq;
1da177e4
LT
2352 unsigned long flags;
2353
2354 might_sleep_if(gfp_mask & __GFP_WAIT);
2355
e2d74ac0 2356 cic = cfq_get_io_context(cfqd, gfp_mask);
22e2c507 2357
1da177e4
LT
2358 spin_lock_irqsave(q->queue_lock, flags);
2359
22e2c507
JA
2360 if (!cic)
2361 goto queue_fail;
2362
91fac317 2363 cfqq = cic_to_cfqq(cic, is_sync);
32f2e807 2364 if (!cfqq || cfqq == &cfqd->oom_cfqq) {
fd0928df 2365 cfqq = cfq_get_queue(cfqd, is_sync, cic->ioc, gfp_mask);
91fac317
VT
2366 cic_set_cfqq(cic, cfqq, is_sync);
2367 }
1da177e4
LT
2368
2369 cfqq->allocated[rw]++;
22e2c507 2370 atomic_inc(&cfqq->ref);
1da177e4 2371
5e705374 2372 spin_unlock_irqrestore(q->queue_lock, flags);
3b18152c 2373
5e705374
JA
2374 rq->elevator_private = cic;
2375 rq->elevator_private2 = cfqq;
2376 return 0;
1da177e4 2377
22e2c507
JA
2378queue_fail:
2379 if (cic)
2380 put_io_context(cic->ioc);
89850f7e 2381
23e018a1 2382 cfq_schedule_dispatch(cfqd);
1da177e4 2383 spin_unlock_irqrestore(q->queue_lock, flags);
7b679138 2384 cfq_log(cfqd, "set_request fail");
1da177e4
LT
2385 return 1;
2386}
2387
65f27f38 2388static void cfq_kick_queue(struct work_struct *work)
22e2c507 2389{
65f27f38 2390 struct cfq_data *cfqd =
23e018a1 2391 container_of(work, struct cfq_data, unplug_work);
165125e1 2392 struct request_queue *q = cfqd->queue;
22e2c507 2393
40bb54d1 2394 spin_lock_irq(q->queue_lock);
a7f55792 2395 __blk_run_queue(cfqd->queue);
40bb54d1 2396 spin_unlock_irq(q->queue_lock);
22e2c507
JA
2397}
2398
2399/*
2400 * Timer running if the active_queue is currently idling inside its time slice
2401 */
2402static void cfq_idle_slice_timer(unsigned long data)
2403{
2404 struct cfq_data *cfqd = (struct cfq_data *) data;
2405 struct cfq_queue *cfqq;
2406 unsigned long flags;
3c6bd2f8 2407 int timed_out = 1;
22e2c507 2408
7b679138
JA
2409 cfq_log(cfqd, "idle timer fired");
2410
22e2c507
JA
2411 spin_lock_irqsave(cfqd->queue->queue_lock, flags);
2412
fe094d98
JA
2413 cfqq = cfqd->active_queue;
2414 if (cfqq) {
3c6bd2f8
JA
2415 timed_out = 0;
2416
b029195d
JA
2417 /*
2418 * We saw a request before the queue expired, let it through
2419 */
2420 if (cfq_cfqq_must_dispatch(cfqq))
2421 goto out_kick;
2422
22e2c507
JA
2423 /*
2424 * expired
2425 */
44f7c160 2426 if (cfq_slice_used(cfqq))
22e2c507
JA
2427 goto expire;
2428
2429 /*
2430 * only expire and reinvoke request handler, if there are
2431 * other queues with pending requests
2432 */
caaa5f9f 2433 if (!cfqd->busy_queues)
22e2c507 2434 goto out_cont;
22e2c507
JA
2435
2436 /*
2437 * not expired and it has a request pending, let it dispatch
2438 */
75e50984 2439 if (!RB_EMPTY_ROOT(&cfqq->sort_list))
22e2c507 2440 goto out_kick;
22e2c507
JA
2441 }
2442expire:
6084cdda 2443 cfq_slice_expired(cfqd, timed_out);
22e2c507 2444out_kick:
23e018a1 2445 cfq_schedule_dispatch(cfqd);
22e2c507
JA
2446out_cont:
2447 spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
2448}
2449
3b18152c
JA
2450static void cfq_shutdown_timer_wq(struct cfq_data *cfqd)
2451{
2452 del_timer_sync(&cfqd->idle_slice_timer);
23e018a1 2453 cancel_work_sync(&cfqd->unplug_work);
3b18152c 2454}
22e2c507 2455
c2dea2d1
VT
2456static void cfq_put_async_queues(struct cfq_data *cfqd)
2457{
2458 int i;
2459
2460 for (i = 0; i < IOPRIO_BE_NR; i++) {
2461 if (cfqd->async_cfqq[0][i])
2462 cfq_put_queue(cfqd->async_cfqq[0][i]);
2463 if (cfqd->async_cfqq[1][i])
2464 cfq_put_queue(cfqd->async_cfqq[1][i]);
c2dea2d1 2465 }
2389d1ef
ON
2466
2467 if (cfqd->async_idle_cfqq)
2468 cfq_put_queue(cfqd->async_idle_cfqq);
c2dea2d1
VT
2469}
2470
b374d18a 2471static void cfq_exit_queue(struct elevator_queue *e)
1da177e4 2472{
22e2c507 2473 struct cfq_data *cfqd = e->elevator_data;
165125e1 2474 struct request_queue *q = cfqd->queue;
22e2c507 2475
3b18152c 2476 cfq_shutdown_timer_wq(cfqd);
e2d74ac0 2477
d9ff4187 2478 spin_lock_irq(q->queue_lock);
e2d74ac0 2479
d9ff4187 2480 if (cfqd->active_queue)
6084cdda 2481 __cfq_slice_expired(cfqd, cfqd->active_queue, 0);
e2d74ac0
JA
2482
2483 while (!list_empty(&cfqd->cic_list)) {
d9ff4187
AV
2484 struct cfq_io_context *cic = list_entry(cfqd->cic_list.next,
2485 struct cfq_io_context,
2486 queue_list);
89850f7e
JA
2487
2488 __cfq_exit_single_io_context(cfqd, cic);
d9ff4187 2489 }
e2d74ac0 2490
c2dea2d1 2491 cfq_put_async_queues(cfqd);
15c31be4 2492
d9ff4187 2493 spin_unlock_irq(q->queue_lock);
a90d742e
AV
2494
2495 cfq_shutdown_timer_wq(cfqd);
2496
a90d742e 2497 kfree(cfqd);
1da177e4
LT
2498}
2499
165125e1 2500static void *cfq_init_queue(struct request_queue *q)
1da177e4
LT
2501{
2502 struct cfq_data *cfqd;
26a2ac00 2503 int i;
1da177e4 2504
94f6030c 2505 cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node);
1da177e4 2506 if (!cfqd)
bc1c1169 2507 return NULL;
1da177e4 2508
cc09e299 2509 cfqd->service_tree = CFQ_RB_ROOT;
26a2ac00
JA
2510
2511 /*
2512 * Not strictly needed (since RB_ROOT just clears the node and we
2513 * zeroed cfqd on alloc), but better be safe in case someone decides
2514 * to add magic to the rb code
2515 */
2516 for (i = 0; i < CFQ_PRIO_LISTS; i++)
2517 cfqd->prio_trees[i] = RB_ROOT;
2518
6118b70b
JA
2519 /*
2520 * Our fallback cfqq if cfq_find_alloc_queue() runs into OOM issues.
2521 * Grab a permanent reference to it, so that the normal code flow
2522 * will not attempt to free it.
2523 */
2524 cfq_init_cfqq(cfqd, &cfqd->oom_cfqq, 1, 0);
2525 atomic_inc(&cfqd->oom_cfqq.ref);
2526
d9ff4187 2527 INIT_LIST_HEAD(&cfqd->cic_list);
1da177e4 2528
1da177e4 2529 cfqd->queue = q;
1da177e4 2530
22e2c507
JA
2531 init_timer(&cfqd->idle_slice_timer);
2532 cfqd->idle_slice_timer.function = cfq_idle_slice_timer;
2533 cfqd->idle_slice_timer.data = (unsigned long) cfqd;
2534
23e018a1 2535 INIT_WORK(&cfqd->unplug_work, cfq_kick_queue);
22e2c507 2536
1da177e4 2537 cfqd->cfq_quantum = cfq_quantum;
22e2c507
JA
2538 cfqd->cfq_fifo_expire[0] = cfq_fifo_expire[0];
2539 cfqd->cfq_fifo_expire[1] = cfq_fifo_expire[1];
1da177e4
LT
2540 cfqd->cfq_back_max = cfq_back_max;
2541 cfqd->cfq_back_penalty = cfq_back_penalty;
22e2c507
JA
2542 cfqd->cfq_slice[0] = cfq_slice_async;
2543 cfqd->cfq_slice[1] = cfq_slice_sync;
2544 cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
2545 cfqd->cfq_slice_idle = cfq_slice_idle;
963b72fc 2546 cfqd->cfq_latency = 1;
45333d5a 2547 cfqd->hw_tag = 1;
365722bb 2548 cfqd->last_end_sync_rq = jiffies;
bc1c1169 2549 return cfqd;
1da177e4
LT
2550}
2551
2552static void cfq_slab_kill(void)
2553{
d6de8be7
JA
2554 /*
2555 * Caller already ensured that pending RCU callbacks are completed,
2556 * so we should have no busy allocations at this point.
2557 */
1da177e4
LT
2558 if (cfq_pool)
2559 kmem_cache_destroy(cfq_pool);
2560 if (cfq_ioc_pool)
2561 kmem_cache_destroy(cfq_ioc_pool);
2562}
2563
2564static int __init cfq_slab_setup(void)
2565{
0a31bd5f 2566 cfq_pool = KMEM_CACHE(cfq_queue, 0);
1da177e4
LT
2567 if (!cfq_pool)
2568 goto fail;
2569
34e6bbf2 2570 cfq_ioc_pool = KMEM_CACHE(cfq_io_context, 0);
1da177e4
LT
2571 if (!cfq_ioc_pool)
2572 goto fail;
2573
2574 return 0;
2575fail:
2576 cfq_slab_kill();
2577 return -ENOMEM;
2578}
2579
1da177e4
LT
2580/*
2581 * sysfs parts below -->
2582 */
1da177e4
LT
2583static ssize_t
2584cfq_var_show(unsigned int var, char *page)
2585{
2586 return sprintf(page, "%d\n", var);
2587}
2588
2589static ssize_t
2590cfq_var_store(unsigned int *var, const char *page, size_t count)
2591{
2592 char *p = (char *) page;
2593
2594 *var = simple_strtoul(p, &p, 10);
2595 return count;
2596}
2597
1da177e4 2598#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
b374d18a 2599static ssize_t __FUNC(struct elevator_queue *e, char *page) \
1da177e4 2600{ \
3d1ab40f 2601 struct cfq_data *cfqd = e->elevator_data; \
1da177e4
LT
2602 unsigned int __data = __VAR; \
2603 if (__CONV) \
2604 __data = jiffies_to_msecs(__data); \
2605 return cfq_var_show(__data, (page)); \
2606}
2607SHOW_FUNCTION(cfq_quantum_show, cfqd->cfq_quantum, 0);
22e2c507
JA
2608SHOW_FUNCTION(cfq_fifo_expire_sync_show, cfqd->cfq_fifo_expire[1], 1);
2609SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
e572ec7e
AV
2610SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0);
2611SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0);
22e2c507
JA
2612SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
2613SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
2614SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
2615SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
963b72fc 2616SHOW_FUNCTION(cfq_low_latency_show, cfqd->cfq_latency, 0);
1da177e4
LT
2617#undef SHOW_FUNCTION
2618
2619#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
b374d18a 2620static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
1da177e4 2621{ \
3d1ab40f 2622 struct cfq_data *cfqd = e->elevator_data; \
1da177e4
LT
2623 unsigned int __data; \
2624 int ret = cfq_var_store(&__data, (page), count); \
2625 if (__data < (MIN)) \
2626 __data = (MIN); \
2627 else if (__data > (MAX)) \
2628 __data = (MAX); \
2629 if (__CONV) \
2630 *(__PTR) = msecs_to_jiffies(__data); \
2631 else \
2632 *(__PTR) = __data; \
2633 return ret; \
2634}
2635STORE_FUNCTION(cfq_quantum_store, &cfqd->cfq_quantum, 1, UINT_MAX, 0);
fe094d98
JA
2636STORE_FUNCTION(cfq_fifo_expire_sync_store, &cfqd->cfq_fifo_expire[1], 1,
2637 UINT_MAX, 1);
2638STORE_FUNCTION(cfq_fifo_expire_async_store, &cfqd->cfq_fifo_expire[0], 1,
2639 UINT_MAX, 1);
e572ec7e 2640STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
fe094d98
JA
2641STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1,
2642 UINT_MAX, 0);
22e2c507
JA
2643STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
2644STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
2645STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
fe094d98
JA
2646STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
2647 UINT_MAX, 0);
963b72fc 2648STORE_FUNCTION(cfq_low_latency_store, &cfqd->cfq_latency, 0, 1, 0);
1da177e4
LT
2649#undef STORE_FUNCTION
2650
e572ec7e
AV
2651#define CFQ_ATTR(name) \
2652 __ATTR(name, S_IRUGO|S_IWUSR, cfq_##name##_show, cfq_##name##_store)
2653
2654static struct elv_fs_entry cfq_attrs[] = {
2655 CFQ_ATTR(quantum),
e572ec7e
AV
2656 CFQ_ATTR(fifo_expire_sync),
2657 CFQ_ATTR(fifo_expire_async),
2658 CFQ_ATTR(back_seek_max),
2659 CFQ_ATTR(back_seek_penalty),
2660 CFQ_ATTR(slice_sync),
2661 CFQ_ATTR(slice_async),
2662 CFQ_ATTR(slice_async_rq),
2663 CFQ_ATTR(slice_idle),
963b72fc 2664 CFQ_ATTR(low_latency),
e572ec7e 2665 __ATTR_NULL
1da177e4
LT
2666};
2667
1da177e4
LT
2668static struct elevator_type iosched_cfq = {
2669 .ops = {
2670 .elevator_merge_fn = cfq_merge,
2671 .elevator_merged_fn = cfq_merged_request,
2672 .elevator_merge_req_fn = cfq_merged_requests,
da775265 2673 .elevator_allow_merge_fn = cfq_allow_merge,
b4878f24 2674 .elevator_dispatch_fn = cfq_dispatch_requests,
1da177e4 2675 .elevator_add_req_fn = cfq_insert_request,
b4878f24 2676 .elevator_activate_req_fn = cfq_activate_request,
1da177e4
LT
2677 .elevator_deactivate_req_fn = cfq_deactivate_request,
2678 .elevator_queue_empty_fn = cfq_queue_empty,
2679 .elevator_completed_req_fn = cfq_completed_request,
21183b07
JA
2680 .elevator_former_req_fn = elv_rb_former_request,
2681 .elevator_latter_req_fn = elv_rb_latter_request,
1da177e4
LT
2682 .elevator_set_req_fn = cfq_set_request,
2683 .elevator_put_req_fn = cfq_put_request,
2684 .elevator_may_queue_fn = cfq_may_queue,
2685 .elevator_init_fn = cfq_init_queue,
2686 .elevator_exit_fn = cfq_exit_queue,
fc46379d 2687 .trim = cfq_free_io_context,
1da177e4 2688 },
3d1ab40f 2689 .elevator_attrs = cfq_attrs,
1da177e4
LT
2690 .elevator_name = "cfq",
2691 .elevator_owner = THIS_MODULE,
2692};
2693
2694static int __init cfq_init(void)
2695{
22e2c507
JA
2696 /*
2697 * could be 0 on HZ < 1000 setups
2698 */
2699 if (!cfq_slice_async)
2700 cfq_slice_async = 1;
2701 if (!cfq_slice_idle)
2702 cfq_slice_idle = 1;
2703
1da177e4
LT
2704 if (cfq_slab_setup())
2705 return -ENOMEM;
2706
2fdd82bd 2707 elv_register(&iosched_cfq);
1da177e4 2708
2fdd82bd 2709 return 0;
1da177e4
LT
2710}
2711
2712static void __exit cfq_exit(void)
2713{
6e9a4738 2714 DECLARE_COMPLETION_ONSTACK(all_gone);
1da177e4 2715 elv_unregister(&iosched_cfq);
334e94de 2716 ioc_gone = &all_gone;
fba82272
OH
2717 /* ioc_gone's update must be visible before reading ioc_count */
2718 smp_wmb();
d6de8be7
JA
2719
2720 /*
2721 * this also protects us from entering cfq_slab_kill() with
2722 * pending RCU callbacks
2723 */
245b2e70 2724 if (elv_ioc_count_read(cfq_ioc_count))
9a11b4ed 2725 wait_for_completion(&all_gone);
83521d3e 2726 cfq_slab_kill();
1da177e4
LT
2727}
2728
2729module_init(cfq_init);
2730module_exit(cfq_exit);
2731
2732MODULE_AUTHOR("Jens Axboe");
2733MODULE_LICENSE("GPL");
2734MODULE_DESCRIPTION("Completely Fair Queueing IO scheduler");