sh: fix format string bug in stack tracer
[linux-2.6-block.git] / mm / backing-dev.c
CommitLineData
3fcfab16
AM
1
2#include <linux/wait.h>
3#include <linux/backing-dev.h>
03ba3782
JA
4#include <linux/kthread.h>
5#include <linux/freezer.h>
3fcfab16 6#include <linux/fs.h>
26160158 7#include <linux/pagemap.h>
03ba3782 8#include <linux/mm.h>
3fcfab16
AM
9#include <linux/sched.h>
10#include <linux/module.h>
cf0ca9fe
PZ
11#include <linux/writeback.h>
12#include <linux/device.h>
455b2864 13#include <trace/events/writeback.h>
cf0ca9fe 14
c3c53206
JA
15static atomic_long_t bdi_seq = ATOMIC_LONG_INIT(0);
16
26160158 17struct backing_dev_info default_backing_dev_info = {
d993831f 18 .name = "default",
26160158
JA
19 .ra_pages = VM_MAX_READAHEAD * 1024 / PAGE_CACHE_SIZE,
20 .state = 0,
21 .capabilities = BDI_CAP_MAP_COPY,
26160158
JA
22};
23EXPORT_SYMBOL_GPL(default_backing_dev_info);
cf0ca9fe 24
5129a469
JE
25struct backing_dev_info noop_backing_dev_info = {
26 .name = "noop",
976e48f8 27 .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK,
5129a469
JE
28};
29EXPORT_SYMBOL_GPL(noop_backing_dev_info);
30
cf0ca9fe 31static struct class *bdi_class;
cfc4ba53
JA
32
33/*
181387da 34 * bdi_lock protects updates to bdi_list. bdi_list has RCU reader side
cfc4ba53
JA
35 * locking.
36 */
03ba3782 37DEFINE_SPINLOCK(bdi_lock);
66f3b8e2 38LIST_HEAD(bdi_list);
03ba3782 39
839a8e86
TH
40/* bdi_wq serves all asynchronous writeback tasks */
41struct workqueue_struct *bdi_wq;
42
f758eeab
CH
43void bdi_lock_two(struct bdi_writeback *wb1, struct bdi_writeback *wb2)
44{
45 if (wb1 < wb2) {
46 spin_lock(&wb1->list_lock);
47 spin_lock_nested(&wb2->list_lock, 1);
48 } else {
49 spin_lock(&wb2->list_lock);
50 spin_lock_nested(&wb1->list_lock, 1);
51 }
52}
53
76f1418b
MS
54#ifdef CONFIG_DEBUG_FS
55#include <linux/debugfs.h>
56#include <linux/seq_file.h>
57
58static struct dentry *bdi_debug_root;
59
60static void bdi_debug_init(void)
61{
62 bdi_debug_root = debugfs_create_dir("bdi", NULL);
63}
64
65static int bdi_debug_stats_show(struct seq_file *m, void *v)
66{
67 struct backing_dev_info *bdi = m->private;
c1955ce3 68 struct bdi_writeback *wb = &bdi->wb;
364aeb28
DR
69 unsigned long background_thresh;
70 unsigned long dirty_thresh;
71 unsigned long bdi_thresh;
345227d7 72 unsigned long nr_dirty, nr_io, nr_more_io;
f09b00d3
JA
73 struct inode *inode;
74
345227d7 75 nr_dirty = nr_io = nr_more_io = 0;
f758eeab 76 spin_lock(&wb->list_lock);
7ccf19a8 77 list_for_each_entry(inode, &wb->b_dirty, i_wb_list)
c1955ce3 78 nr_dirty++;
7ccf19a8 79 list_for_each_entry(inode, &wb->b_io, i_wb_list)
c1955ce3 80 nr_io++;
7ccf19a8 81 list_for_each_entry(inode, &wb->b_more_io, i_wb_list)
c1955ce3 82 nr_more_io++;
f758eeab 83 spin_unlock(&wb->list_lock);
76f1418b 84
16c4042f
WF
85 global_dirty_limits(&background_thresh, &dirty_thresh);
86 bdi_thresh = bdi_dirty_limit(bdi, dirty_thresh);
76f1418b
MS
87
88#define K(x) ((x) << (PAGE_SHIFT - 10))
89 seq_printf(m,
00821b00
WF
90 "BdiWriteback: %10lu kB\n"
91 "BdiReclaimable: %10lu kB\n"
92 "BdiDirtyThresh: %10lu kB\n"
93 "DirtyThresh: %10lu kB\n"
94 "BackgroundThresh: %10lu kB\n"
c8e28ce0 95 "BdiDirtied: %10lu kB\n"
00821b00
WF
96 "BdiWritten: %10lu kB\n"
97 "BdiWriteBandwidth: %10lu kBps\n"
98 "b_dirty: %10lu\n"
99 "b_io: %10lu\n"
100 "b_more_io: %10lu\n"
101 "bdi_list: %10u\n"
102 "state: %10lx\n",
76f1418b
MS
103 (unsigned long) K(bdi_stat(bdi, BDI_WRITEBACK)),
104 (unsigned long) K(bdi_stat(bdi, BDI_RECLAIMABLE)),
f7d2b1ec
JK
105 K(bdi_thresh),
106 K(dirty_thresh),
107 K(background_thresh),
c8e28ce0 108 (unsigned long) K(bdi_stat(bdi, BDI_DIRTIED)),
f7d2b1ec 109 (unsigned long) K(bdi_stat(bdi, BDI_WRITTEN)),
00821b00 110 (unsigned long) K(bdi->write_bandwidth),
f7d2b1ec
JK
111 nr_dirty,
112 nr_io,
113 nr_more_io,
c1955ce3 114 !list_empty(&bdi->bdi_list), bdi->state);
76f1418b
MS
115#undef K
116
117 return 0;
118}
119
120static int bdi_debug_stats_open(struct inode *inode, struct file *file)
121{
122 return single_open(file, bdi_debug_stats_show, inode->i_private);
123}
124
125static const struct file_operations bdi_debug_stats_fops = {
126 .open = bdi_debug_stats_open,
127 .read = seq_read,
128 .llseek = seq_lseek,
129 .release = single_release,
130};
131
132static void bdi_debug_register(struct backing_dev_info *bdi, const char *name)
133{
134 bdi->debug_dir = debugfs_create_dir(name, bdi_debug_root);
135 bdi->debug_stats = debugfs_create_file("stats", 0444, bdi->debug_dir,
136 bdi, &bdi_debug_stats_fops);
137}
138
139static void bdi_debug_unregister(struct backing_dev_info *bdi)
140{
141 debugfs_remove(bdi->debug_stats);
142 debugfs_remove(bdi->debug_dir);
143}
144#else
145static inline void bdi_debug_init(void)
146{
147}
148static inline void bdi_debug_register(struct backing_dev_info *bdi,
149 const char *name)
150{
151}
152static inline void bdi_debug_unregister(struct backing_dev_info *bdi)
153{
154}
155#endif
156
cf0ca9fe
PZ
157static ssize_t read_ahead_kb_store(struct device *dev,
158 struct device_attribute *attr,
159 const char *buf, size_t count)
160{
161 struct backing_dev_info *bdi = dev_get_drvdata(dev);
cf0ca9fe 162 unsigned long read_ahead_kb;
7034ed13 163 ssize_t ret;
cf0ca9fe 164
7034ed13
NJ
165 ret = kstrtoul(buf, 10, &read_ahead_kb);
166 if (ret < 0)
167 return ret;
168
169 bdi->ra_pages = read_ahead_kb >> (PAGE_SHIFT - 10);
170
171 return count;
cf0ca9fe
PZ
172}
173
174#define K(pages) ((pages) << (PAGE_SHIFT - 10))
175
176#define BDI_SHOW(name, expr) \
177static ssize_t name##_show(struct device *dev, \
178 struct device_attribute *attr, char *page) \
179{ \
180 struct backing_dev_info *bdi = dev_get_drvdata(dev); \
181 \
182 return snprintf(page, PAGE_SIZE-1, "%lld\n", (long long)expr); \
d9e1241e
GKH
183} \
184static DEVICE_ATTR_RW(name);
cf0ca9fe
PZ
185
186BDI_SHOW(read_ahead_kb, K(bdi->ra_pages))
187
189d3c4a
PZ
188static ssize_t min_ratio_store(struct device *dev,
189 struct device_attribute *attr, const char *buf, size_t count)
190{
191 struct backing_dev_info *bdi = dev_get_drvdata(dev);
189d3c4a 192 unsigned int ratio;
7034ed13
NJ
193 ssize_t ret;
194
195 ret = kstrtouint(buf, 10, &ratio);
196 if (ret < 0)
197 return ret;
198
199 ret = bdi_set_min_ratio(bdi, ratio);
200 if (!ret)
201 ret = count;
189d3c4a 202
189d3c4a
PZ
203 return ret;
204}
205BDI_SHOW(min_ratio, bdi->min_ratio)
206
a42dde04
PZ
207static ssize_t max_ratio_store(struct device *dev,
208 struct device_attribute *attr, const char *buf, size_t count)
209{
210 struct backing_dev_info *bdi = dev_get_drvdata(dev);
a42dde04 211 unsigned int ratio;
7034ed13
NJ
212 ssize_t ret;
213
214 ret = kstrtouint(buf, 10, &ratio);
215 if (ret < 0)
216 return ret;
217
218 ret = bdi_set_max_ratio(bdi, ratio);
219 if (!ret)
220 ret = count;
a42dde04 221
a42dde04
PZ
222 return ret;
223}
224BDI_SHOW(max_ratio, bdi->max_ratio)
225
7d311cda
DW
226static ssize_t stable_pages_required_show(struct device *dev,
227 struct device_attribute *attr,
228 char *page)
229{
230 struct backing_dev_info *bdi = dev_get_drvdata(dev);
231
232 return snprintf(page, PAGE_SIZE-1, "%d\n",
233 bdi_cap_stable_pages_required(bdi) ? 1 : 0);
234}
d9e1241e
GKH
235static DEVICE_ATTR_RO(stable_pages_required);
236
237static struct attribute *bdi_dev_attrs[] = {
238 &dev_attr_read_ahead_kb.attr,
239 &dev_attr_min_ratio.attr,
240 &dev_attr_max_ratio.attr,
241 &dev_attr_stable_pages_required.attr,
242 NULL,
cf0ca9fe 243};
d9e1241e 244ATTRIBUTE_GROUPS(bdi_dev);
cf0ca9fe
PZ
245
246static __init int bdi_class_init(void)
247{
248 bdi_class = class_create(THIS_MODULE, "bdi");
14421453
AB
249 if (IS_ERR(bdi_class))
250 return PTR_ERR(bdi_class);
251
d9e1241e 252 bdi_class->dev_groups = bdi_dev_groups;
76f1418b 253 bdi_debug_init();
cf0ca9fe
PZ
254 return 0;
255}
76f1418b 256postcore_initcall(bdi_class_init);
cf0ca9fe 257
26160158
JA
258static int __init default_bdi_init(void)
259{
260 int err;
261
839a8e86 262 bdi_wq = alloc_workqueue("writeback", WQ_MEM_RECLAIM | WQ_FREEZABLE |
b5c872dd 263 WQ_UNBOUND | WQ_SYSFS, 0);
839a8e86
TH
264 if (!bdi_wq)
265 return -ENOMEM;
266
26160158
JA
267 err = bdi_init(&default_backing_dev_info);
268 if (!err)
269 bdi_register(&default_backing_dev_info, NULL, "default");
976e48f8 270 err = bdi_init(&noop_backing_dev_info);
26160158
JA
271
272 return err;
273}
274subsys_initcall(default_bdi_init);
275
03ba3782
JA
276int bdi_has_dirty_io(struct backing_dev_info *bdi)
277{
278 return wb_has_dirty_io(&bdi->wb);
279}
280
6467716a
AB
281/*
282 * This function is used when the first inode for this bdi is marked dirty. It
283 * wakes-up the corresponding bdi thread which should then take care of the
284 * periodic background write-out of dirty inodes. Since the write-out would
285 * starts only 'dirty_writeback_interval' centisecs from now anyway, we just
286 * set up a timer which wakes the bdi thread up later.
287 *
288 * Note, we wouldn't bother setting up the timer, but this function is on the
289 * fast-path (used by '__mark_inode_dirty()'), so we save few context switches
290 * by delaying the wake-up.
291 */
292void bdi_wakeup_thread_delayed(struct backing_dev_info *bdi)
293{
294 unsigned long timeout;
295
296 timeout = msecs_to_jiffies(dirty_writeback_interval * 10);
839a8e86 297 mod_delayed_work(bdi_wq, &bdi->wb.dwork, timeout);
03ba3782
JA
298}
299
cfc4ba53
JA
300/*
301 * Remove bdi from bdi_list, and ensure that it is no longer visible
302 */
303static void bdi_remove_from_list(struct backing_dev_info *bdi)
304{
305 spin_lock_bh(&bdi_lock);
306 list_del_rcu(&bdi->bdi_list);
307 spin_unlock_bh(&bdi_lock);
308
ef323088 309 synchronize_rcu_expedited();
839a8e86
TH
310
311 /* bdi_list is now unused, clear it to mark @bdi dying */
312 INIT_LIST_HEAD(&bdi->bdi_list);
cfc4ba53
JA
313}
314
cf0ca9fe
PZ
315int bdi_register(struct backing_dev_info *bdi, struct device *parent,
316 const char *fmt, ...)
317{
cf0ca9fe 318 va_list args;
cf0ca9fe
PZ
319 struct device *dev;
320
69fc208b 321 if (bdi->dev) /* The driver needs to use separate queues per device */
c284de61 322 return 0;
f1d0b063 323
cf0ca9fe 324 va_start(args, fmt);
19051c50 325 dev = device_create_vargs(bdi_class, parent, MKDEV(0, 0), bdi, fmt, args);
cf0ca9fe 326 va_end(args);
c284de61
AB
327 if (IS_ERR(dev))
328 return PTR_ERR(dev);
66f3b8e2 329
cf0ca9fe 330 bdi->dev = dev;
cf0ca9fe 331
03ba3782 332 bdi_debug_register(bdi, dev_name(dev));
500b067c 333 set_bit(BDI_registered, &bdi->state);
c284de61
AB
334
335 spin_lock_bh(&bdi_lock);
336 list_add_tail_rcu(&bdi->bdi_list, &bdi_list);
337 spin_unlock_bh(&bdi_lock);
338
455b2864 339 trace_writeback_bdi_register(bdi);
c284de61 340 return 0;
cf0ca9fe
PZ
341}
342EXPORT_SYMBOL(bdi_register);
343
344int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev)
345{
346 return bdi_register(bdi, NULL, "%u:%u", MAJOR(dev), MINOR(dev));
347}
348EXPORT_SYMBOL(bdi_register_dev);
349
03ba3782
JA
350/*
351 * Remove bdi from the global list and shutdown any threads we have running
352 */
353static void bdi_wb_shutdown(struct backing_dev_info *bdi)
66f3b8e2 354{
03ba3782
JA
355 if (!bdi_cap_writeback_dirty(bdi))
356 return;
357
358 /*
fff5b85a 359 * Make sure nobody finds us on the bdi_list anymore
03ba3782 360 */
fff5b85a 361 bdi_remove_from_list(bdi);
03ba3782
JA
362
363 /*
839a8e86
TH
364 * Drain work list and shutdown the delayed_work. At this point,
365 * @bdi->bdi_list is empty telling bdi_Writeback_workfn() that @bdi
366 * is dying and its work_list needs to be drained no matter what.
03ba3782 367 */
839a8e86
TH
368 mod_delayed_work(bdi_wq, &bdi->wb.dwork, 0);
369 flush_delayed_work(&bdi->wb.dwork);
370 WARN_ON(!list_empty(&bdi->work_list));
03ba3782
JA
371
372 /*
839a8e86
TH
373 * This shouldn't be necessary unless @bdi for some reason has
374 * unflushed dirty IO after work_list is drained. Do it anyway
375 * just in case.
03ba3782 376 */
839a8e86 377 cancel_delayed_work_sync(&bdi->wb.dwork);
66f3b8e2
JA
378}
379
592b09a4
JA
380/*
381 * This bdi is going away now, make sure that no super_blocks point to it
382 */
383static void bdi_prune_sb(struct backing_dev_info *bdi)
384{
385 struct super_block *sb;
386
387 spin_lock(&sb_lock);
388 list_for_each_entry(sb, &super_blocks, s_list) {
389 if (sb->s_bdi == bdi)
95f28604 390 sb->s_bdi = &default_backing_dev_info;
592b09a4
JA
391 }
392 spin_unlock(&sb_lock);
393}
394
cf0ca9fe
PZ
395void bdi_unregister(struct backing_dev_info *bdi)
396{
2673b4cf
RV
397 struct device *dev = bdi->dev;
398
399 if (dev) {
ccb6108f 400 bdi_set_min_ratio(bdi, 0);
455b2864 401 trace_writeback_bdi_unregister(bdi);
8c4db335
JA
402 bdi_prune_sb(bdi);
403
839a8e86 404 bdi_wb_shutdown(bdi);
76f1418b 405 bdi_debug_unregister(bdi);
2673b4cf
RV
406
407 spin_lock_bh(&bdi->wb_lock);
cf0ca9fe 408 bdi->dev = NULL;
2673b4cf
RV
409 spin_unlock_bh(&bdi->wb_lock);
410
411 device_unregister(dev);
cf0ca9fe
PZ
412 }
413}
414EXPORT_SYMBOL(bdi_unregister);
3fcfab16 415
6467716a
AB
416static void bdi_wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi)
417{
418 memset(wb, 0, sizeof(*wb));
419
420 wb->bdi = bdi;
421 wb->last_old_flush = jiffies;
422 INIT_LIST_HEAD(&wb->b_dirty);
423 INIT_LIST_HEAD(&wb->b_io);
424 INIT_LIST_HEAD(&wb->b_more_io);
f758eeab 425 spin_lock_init(&wb->list_lock);
839a8e86 426 INIT_DELAYED_WORK(&wb->dwork, bdi_writeback_workfn);
6467716a
AB
427}
428
e98be2d5
WF
429/*
430 * Initial write bandwidth: 100 MB/s
431 */
432#define INIT_BW (100 << (20 - PAGE_SHIFT))
433
b2e8fb6e
PZ
434int bdi_init(struct backing_dev_info *bdi)
435{
03ba3782 436 int i, err;
b2e8fb6e 437
cf0ca9fe
PZ
438 bdi->dev = NULL;
439
189d3c4a 440 bdi->min_ratio = 0;
a42dde04 441 bdi->max_ratio = 100;
eb608e3a 442 bdi->max_prop_frac = FPROP_FRAC_BASE;
03ba3782 443 spin_lock_init(&bdi->wb_lock);
66f3b8e2 444 INIT_LIST_HEAD(&bdi->bdi_list);
03ba3782
JA
445 INIT_LIST_HEAD(&bdi->work_list);
446
447 bdi_wb_init(&bdi->wb, bdi);
448
b2e8fb6e 449 for (i = 0; i < NR_BDI_STAT_ITEMS; i++) {
ea319518 450 err = percpu_counter_init(&bdi->bdi_stat[i], 0);
04fbfdc1
PZ
451 if (err)
452 goto err;
453 }
454
455 bdi->dirty_exceeded = 0;
e98be2d5
WF
456
457 bdi->bw_time_stamp = jiffies;
458 bdi->written_stamp = 0;
459
7381131c 460 bdi->balanced_dirty_ratelimit = INIT_BW;
be3ffa27 461 bdi->dirty_ratelimit = INIT_BW;
e98be2d5
WF
462 bdi->write_bandwidth = INIT_BW;
463 bdi->avg_write_bandwidth = INIT_BW;
464
eb608e3a 465 err = fprop_local_init_percpu(&bdi->completions);
04fbfdc1
PZ
466
467 if (err) {
468err:
4b01a0b1 469 while (i--)
04fbfdc1 470 percpu_counter_destroy(&bdi->bdi_stat[i]);
b2e8fb6e
PZ
471 }
472
473 return err;
474}
475EXPORT_SYMBOL(bdi_init);
476
477void bdi_destroy(struct backing_dev_info *bdi)
478{
479 int i;
480
ce5f8e77
JA
481 /*
482 * Splice our entries to the default_backing_dev_info, if this
483 * bdi disappears
484 */
485 if (bdi_has_dirty_io(bdi)) {
486 struct bdi_writeback *dst = &default_backing_dev_info.wb;
487
f758eeab 488 bdi_lock_two(&bdi->wb, dst);
ce5f8e77
JA
489 list_splice(&bdi->wb.b_dirty, &dst->b_dirty);
490 list_splice(&bdi->wb.b_io, &dst->b_io);
491 list_splice(&bdi->wb.b_more_io, &dst->b_more_io);
f758eeab
CH
492 spin_unlock(&bdi->wb.list_lock);
493 spin_unlock(&dst->list_lock);
ce5f8e77 494 }
66f3b8e2 495
cf0ca9fe
PZ
496 bdi_unregister(bdi);
497
7a401a97 498 /*
839a8e86
TH
499 * If bdi_unregister() had already been called earlier, the dwork
500 * could still be pending because bdi_prune_sb() can race with the
501 * bdi_wakeup_thread_delayed() calls from __mark_inode_dirty().
7a401a97 502 */
839a8e86 503 cancel_delayed_work_sync(&bdi->wb.dwork);
7a401a97 504
b2e8fb6e
PZ
505 for (i = 0; i < NR_BDI_STAT_ITEMS; i++)
506 percpu_counter_destroy(&bdi->bdi_stat[i]);
04fbfdc1 507
eb608e3a 508 fprop_local_destroy_percpu(&bdi->completions);
b2e8fb6e
PZ
509}
510EXPORT_SYMBOL(bdi_destroy);
511
c3c53206
JA
512/*
513 * For use from filesystems to quickly init and register a bdi associated
514 * with dirty writeback
515 */
516int bdi_setup_and_register(struct backing_dev_info *bdi, char *name,
517 unsigned int cap)
518{
c3c53206
JA
519 int err;
520
521 bdi->name = name;
522 bdi->capabilities = cap;
523 err = bdi_init(bdi);
524 if (err)
525 return err;
526
02aa2a37
KC
527 err = bdi_register(bdi, NULL, "%.28s-%ld", name,
528 atomic_long_inc_return(&bdi_seq));
c3c53206
JA
529 if (err) {
530 bdi_destroy(bdi);
531 return err;
532 }
533
534 return 0;
535}
536EXPORT_SYMBOL(bdi_setup_and_register);
537
3fcfab16
AM
538static wait_queue_head_t congestion_wqh[2] = {
539 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]),
540 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1])
541 };
0e093d99 542static atomic_t nr_bdi_congested[2];
3fcfab16 543
1faa16d2 544void clear_bdi_congested(struct backing_dev_info *bdi, int sync)
3fcfab16
AM
545{
546 enum bdi_state bit;
1faa16d2 547 wait_queue_head_t *wqh = &congestion_wqh[sync];
3fcfab16 548
1faa16d2 549 bit = sync ? BDI_sync_congested : BDI_async_congested;
0e093d99
MG
550 if (test_and_clear_bit(bit, &bdi->state))
551 atomic_dec(&nr_bdi_congested[sync]);
3fcfab16
AM
552 smp_mb__after_clear_bit();
553 if (waitqueue_active(wqh))
554 wake_up(wqh);
555}
556EXPORT_SYMBOL(clear_bdi_congested);
557
1faa16d2 558void set_bdi_congested(struct backing_dev_info *bdi, int sync)
3fcfab16
AM
559{
560 enum bdi_state bit;
561
1faa16d2 562 bit = sync ? BDI_sync_congested : BDI_async_congested;
0e093d99
MG
563 if (!test_and_set_bit(bit, &bdi->state))
564 atomic_inc(&nr_bdi_congested[sync]);
3fcfab16
AM
565}
566EXPORT_SYMBOL(set_bdi_congested);
567
568/**
569 * congestion_wait - wait for a backing_dev to become uncongested
8aa7e847 570 * @sync: SYNC or ASYNC IO
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571 * @timeout: timeout in jiffies
572 *
573 * Waits for up to @timeout jiffies for a backing_dev (any backing_dev) to exit
574 * write congestion. If no backing_devs are congested then just wait for the
575 * next write to be completed.
576 */
8aa7e847 577long congestion_wait(int sync, long timeout)
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578{
579 long ret;
52bb9198 580 unsigned long start = jiffies;
3fcfab16 581 DEFINE_WAIT(wait);
8aa7e847 582 wait_queue_head_t *wqh = &congestion_wqh[sync];
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583
584 prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
585 ret = io_schedule_timeout(timeout);
586 finish_wait(wqh, &wait);
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587
588 trace_writeback_congestion_wait(jiffies_to_usecs(timeout),
589 jiffies_to_usecs(jiffies - start));
590
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591 return ret;
592}
593EXPORT_SYMBOL(congestion_wait);
04fbfdc1 594
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595/**
596 * wait_iff_congested - Conditionally wait for a backing_dev to become uncongested or a zone to complete writes
597 * @zone: A zone to check if it is heavily congested
598 * @sync: SYNC or ASYNC IO
599 * @timeout: timeout in jiffies
600 *
601 * In the event of a congested backing_dev (any backing_dev) and the given
602 * @zone has experienced recent congestion, this waits for up to @timeout
603 * jiffies for either a BDI to exit congestion of the given @sync queue
604 * or a write to complete.
605 *
25985edc 606 * In the absence of zone congestion, cond_resched() is called to yield
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607 * the processor if necessary but otherwise does not sleep.
608 *
609 * The return value is 0 if the sleep is for the full timeout. Otherwise,
610 * it is the number of jiffies that were still remaining when the function
611 * returned. return_value == timeout implies the function did not sleep.
612 */
613long wait_iff_congested(struct zone *zone, int sync, long timeout)
614{
615 long ret;
616 unsigned long start = jiffies;
617 DEFINE_WAIT(wait);
618 wait_queue_head_t *wqh = &congestion_wqh[sync];
619
620 /*
621 * If there is no congestion, or heavy congestion is not being
622 * encountered in the current zone, yield if necessary instead
623 * of sleeping on the congestion queue
624 */
625 if (atomic_read(&nr_bdi_congested[sync]) == 0 ||
626 !zone_is_reclaim_congested(zone)) {
627 cond_resched();
628
629 /* In case we scheduled, work out time remaining */
630 ret = timeout - (jiffies - start);
631 if (ret < 0)
632 ret = 0;
633
634 goto out;
635 }
636
637 /* Sleep until uncongested or a write happens */
638 prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
639 ret = io_schedule_timeout(timeout);
640 finish_wait(wqh, &wait);
641
642out:
643 trace_writeback_wait_iff_congested(jiffies_to_usecs(timeout),
644 jiffies_to_usecs(jiffies - start));
645
646 return ret;
647}
648EXPORT_SYMBOL(wait_iff_congested);
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649
650int pdflush_proc_obsolete(struct ctl_table *table, int write,
651 void __user *buffer, size_t *lenp, loff_t *ppos)
652{
653 char kbuf[] = "0\n";
654
4c3bffc2 655 if (*ppos || *lenp < sizeof(kbuf)) {
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656 *lenp = 0;
657 return 0;
658 }
659
660 if (copy_to_user(buffer, kbuf, sizeof(kbuf)))
661 return -EFAULT;
662 printk_once(KERN_WARNING "%s exported in /proc is scheduled for removal\n",
663 table->procname);
664
665 *lenp = 2;
666 *ppos += *lenp;
667 return 2;
668}