writeback: remove unused bdi_pending_list
[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>
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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
f758eeab
CH
40void bdi_lock_two(struct bdi_writeback *wb1, struct bdi_writeback *wb2)
41{
42 if (wb1 < wb2) {
43 spin_lock(&wb1->list_lock);
44 spin_lock_nested(&wb2->list_lock, 1);
45 } else {
46 spin_lock(&wb2->list_lock);
47 spin_lock_nested(&wb1->list_lock, 1);
48 }
49}
50
76f1418b
MS
51#ifdef CONFIG_DEBUG_FS
52#include <linux/debugfs.h>
53#include <linux/seq_file.h>
54
55static struct dentry *bdi_debug_root;
56
57static void bdi_debug_init(void)
58{
59 bdi_debug_root = debugfs_create_dir("bdi", NULL);
60}
61
62static int bdi_debug_stats_show(struct seq_file *m, void *v)
63{
64 struct backing_dev_info *bdi = m->private;
c1955ce3 65 struct bdi_writeback *wb = &bdi->wb;
364aeb28
DR
66 unsigned long background_thresh;
67 unsigned long dirty_thresh;
68 unsigned long bdi_thresh;
345227d7 69 unsigned long nr_dirty, nr_io, nr_more_io;
f09b00d3
JA
70 struct inode *inode;
71
345227d7 72 nr_dirty = nr_io = nr_more_io = 0;
f758eeab 73 spin_lock(&wb->list_lock);
7ccf19a8 74 list_for_each_entry(inode, &wb->b_dirty, i_wb_list)
c1955ce3 75 nr_dirty++;
7ccf19a8 76 list_for_each_entry(inode, &wb->b_io, i_wb_list)
c1955ce3 77 nr_io++;
7ccf19a8 78 list_for_each_entry(inode, &wb->b_more_io, i_wb_list)
c1955ce3 79 nr_more_io++;
f758eeab 80 spin_unlock(&wb->list_lock);
76f1418b 81
16c4042f
WF
82 global_dirty_limits(&background_thresh, &dirty_thresh);
83 bdi_thresh = bdi_dirty_limit(bdi, dirty_thresh);
76f1418b
MS
84
85#define K(x) ((x) << (PAGE_SHIFT - 10))
86 seq_printf(m,
00821b00
WF
87 "BdiWriteback: %10lu kB\n"
88 "BdiReclaimable: %10lu kB\n"
89 "BdiDirtyThresh: %10lu kB\n"
90 "DirtyThresh: %10lu kB\n"
91 "BackgroundThresh: %10lu kB\n"
c8e28ce0 92 "BdiDirtied: %10lu kB\n"
00821b00
WF
93 "BdiWritten: %10lu kB\n"
94 "BdiWriteBandwidth: %10lu kBps\n"
95 "b_dirty: %10lu\n"
96 "b_io: %10lu\n"
97 "b_more_io: %10lu\n"
98 "bdi_list: %10u\n"
99 "state: %10lx\n",
76f1418b
MS
100 (unsigned long) K(bdi_stat(bdi, BDI_WRITEBACK)),
101 (unsigned long) K(bdi_stat(bdi, BDI_RECLAIMABLE)),
f7d2b1ec
JK
102 K(bdi_thresh),
103 K(dirty_thresh),
104 K(background_thresh),
c8e28ce0 105 (unsigned long) K(bdi_stat(bdi, BDI_DIRTIED)),
f7d2b1ec 106 (unsigned long) K(bdi_stat(bdi, BDI_WRITTEN)),
00821b00 107 (unsigned long) K(bdi->write_bandwidth),
f7d2b1ec
JK
108 nr_dirty,
109 nr_io,
110 nr_more_io,
c1955ce3 111 !list_empty(&bdi->bdi_list), bdi->state);
76f1418b
MS
112#undef K
113
114 return 0;
115}
116
117static int bdi_debug_stats_open(struct inode *inode, struct file *file)
118{
119 return single_open(file, bdi_debug_stats_show, inode->i_private);
120}
121
122static const struct file_operations bdi_debug_stats_fops = {
123 .open = bdi_debug_stats_open,
124 .read = seq_read,
125 .llseek = seq_lseek,
126 .release = single_release,
127};
128
129static void bdi_debug_register(struct backing_dev_info *bdi, const char *name)
130{
131 bdi->debug_dir = debugfs_create_dir(name, bdi_debug_root);
132 bdi->debug_stats = debugfs_create_file("stats", 0444, bdi->debug_dir,
133 bdi, &bdi_debug_stats_fops);
134}
135
136static void bdi_debug_unregister(struct backing_dev_info *bdi)
137{
138 debugfs_remove(bdi->debug_stats);
139 debugfs_remove(bdi->debug_dir);
140}
141#else
142static inline void bdi_debug_init(void)
143{
144}
145static inline void bdi_debug_register(struct backing_dev_info *bdi,
146 const char *name)
147{
148}
149static inline void bdi_debug_unregister(struct backing_dev_info *bdi)
150{
151}
152#endif
153
cf0ca9fe
PZ
154static ssize_t read_ahead_kb_store(struct device *dev,
155 struct device_attribute *attr,
156 const char *buf, size_t count)
157{
158 struct backing_dev_info *bdi = dev_get_drvdata(dev);
cf0ca9fe 159 unsigned long read_ahead_kb;
7034ed13 160 ssize_t ret;
cf0ca9fe 161
7034ed13
NJ
162 ret = kstrtoul(buf, 10, &read_ahead_kb);
163 if (ret < 0)
164 return ret;
165
166 bdi->ra_pages = read_ahead_kb >> (PAGE_SHIFT - 10);
167
168 return count;
cf0ca9fe
PZ
169}
170
171#define K(pages) ((pages) << (PAGE_SHIFT - 10))
172
173#define BDI_SHOW(name, expr) \
174static ssize_t name##_show(struct device *dev, \
175 struct device_attribute *attr, char *page) \
176{ \
177 struct backing_dev_info *bdi = dev_get_drvdata(dev); \
178 \
179 return snprintf(page, PAGE_SIZE-1, "%lld\n", (long long)expr); \
180}
181
182BDI_SHOW(read_ahead_kb, K(bdi->ra_pages))
183
189d3c4a
PZ
184static ssize_t min_ratio_store(struct device *dev,
185 struct device_attribute *attr, const char *buf, size_t count)
186{
187 struct backing_dev_info *bdi = dev_get_drvdata(dev);
189d3c4a 188 unsigned int ratio;
7034ed13
NJ
189 ssize_t ret;
190
191 ret = kstrtouint(buf, 10, &ratio);
192 if (ret < 0)
193 return ret;
194
195 ret = bdi_set_min_ratio(bdi, ratio);
196 if (!ret)
197 ret = count;
189d3c4a 198
189d3c4a
PZ
199 return ret;
200}
201BDI_SHOW(min_ratio, bdi->min_ratio)
202
a42dde04
PZ
203static ssize_t max_ratio_store(struct device *dev,
204 struct device_attribute *attr, const char *buf, size_t count)
205{
206 struct backing_dev_info *bdi = dev_get_drvdata(dev);
a42dde04 207 unsigned int ratio;
7034ed13
NJ
208 ssize_t ret;
209
210 ret = kstrtouint(buf, 10, &ratio);
211 if (ret < 0)
212 return ret;
213
214 ret = bdi_set_max_ratio(bdi, ratio);
215 if (!ret)
216 ret = count;
a42dde04 217
a42dde04
PZ
218 return ret;
219}
220BDI_SHOW(max_ratio, bdi->max_ratio)
221
7d311cda
DW
222static ssize_t stable_pages_required_show(struct device *dev,
223 struct device_attribute *attr,
224 char *page)
225{
226 struct backing_dev_info *bdi = dev_get_drvdata(dev);
227
228 return snprintf(page, PAGE_SIZE-1, "%d\n",
229 bdi_cap_stable_pages_required(bdi) ? 1 : 0);
230}
231
cf0ca9fe
PZ
232#define __ATTR_RW(attr) __ATTR(attr, 0644, attr##_show, attr##_store)
233
234static struct device_attribute bdi_dev_attrs[] = {
235 __ATTR_RW(read_ahead_kb),
189d3c4a 236 __ATTR_RW(min_ratio),
a42dde04 237 __ATTR_RW(max_ratio),
7d311cda 238 __ATTR_RO(stable_pages_required),
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PZ
239 __ATTR_NULL,
240};
241
242static __init int bdi_class_init(void)
243{
244 bdi_class = class_create(THIS_MODULE, "bdi");
14421453
AB
245 if (IS_ERR(bdi_class))
246 return PTR_ERR(bdi_class);
247
cf0ca9fe 248 bdi_class->dev_attrs = bdi_dev_attrs;
76f1418b 249 bdi_debug_init();
cf0ca9fe
PZ
250 return 0;
251}
76f1418b 252postcore_initcall(bdi_class_init);
cf0ca9fe 253
26160158
JA
254static int __init default_bdi_init(void)
255{
256 int err;
257
258 err = bdi_init(&default_backing_dev_info);
259 if (!err)
260 bdi_register(&default_backing_dev_info, NULL, "default");
976e48f8 261 err = bdi_init(&noop_backing_dev_info);
26160158
JA
262
263 return err;
264}
265subsys_initcall(default_bdi_init);
266
03ba3782
JA
267int bdi_has_dirty_io(struct backing_dev_info *bdi)
268{
269 return wb_has_dirty_io(&bdi->wb);
270}
271
6467716a
AB
272static void wakeup_timer_fn(unsigned long data)
273{
274 struct backing_dev_info *bdi = (struct backing_dev_info *)data;
275
276 spin_lock_bh(&bdi->wb_lock);
277 if (bdi->wb.task) {
60332023 278 trace_writeback_wake_thread(bdi);
6467716a 279 wake_up_process(bdi->wb.task);
2673b4cf 280 } else if (bdi->dev) {
6467716a
AB
281 /*
282 * When bdi tasks are inactive for long time, they are killed.
283 * In this case we have to wake-up the forker thread which
284 * should create and run the bdi thread.
285 */
60332023 286 trace_writeback_wake_forker_thread(bdi);
6467716a
AB
287 wake_up_process(default_backing_dev_info.wb.task);
288 }
289 spin_unlock_bh(&bdi->wb_lock);
290}
291
292/*
293 * This function is used when the first inode for this bdi is marked dirty. It
294 * wakes-up the corresponding bdi thread which should then take care of the
295 * periodic background write-out of dirty inodes. Since the write-out would
296 * starts only 'dirty_writeback_interval' centisecs from now anyway, we just
297 * set up a timer which wakes the bdi thread up later.
298 *
299 * Note, we wouldn't bother setting up the timer, but this function is on the
300 * fast-path (used by '__mark_inode_dirty()'), so we save few context switches
301 * by delaying the wake-up.
302 */
303void bdi_wakeup_thread_delayed(struct backing_dev_info *bdi)
304{
305 unsigned long timeout;
306
307 timeout = msecs_to_jiffies(dirty_writeback_interval * 10);
308 mod_timer(&bdi->wb.wakeup_timer, jiffies + timeout);
309}
310
fff5b85a
AB
311/*
312 * Calculate the longest interval (jiffies) bdi threads are allowed to be
313 * inactive.
314 */
315static unsigned long bdi_longest_inactive(void)
316{
317 unsigned long interval;
318
319 interval = msecs_to_jiffies(dirty_writeback_interval * 10);
320 return max(5UL * 60 * HZ, interval);
321}
322
5a042aa4
JK
323/*
324 * Clear pending bit and wakeup anybody waiting for flusher thread creation or
325 * shutdown
326 */
327static void bdi_clear_pending(struct backing_dev_info *bdi)
328{
329 clear_bit(BDI_pending, &bdi->state);
330 smp_mb__after_clear_bit();
331 wake_up_bit(&bdi->state, BDI_pending);
332}
333
6f904ff0 334static int bdi_forker_thread(void *ptr)
03ba3782
JA
335{
336 struct bdi_writeback *me = ptr;
337
766f9164 338 current->flags |= PF_SWAPWRITE;
c1955ce3
CH
339 set_freezable();
340
341 /*
342 * Our parent may run at a different priority, just set us to normal
343 */
344 set_user_nice(current, 0);
03ba3782
JA
345
346 for (;;) {
fff5b85a 347 struct task_struct *task = NULL;
78c40cb6 348 struct backing_dev_info *bdi;
adf39240
AB
349 enum {
350 NO_ACTION, /* Nothing to do */
351 FORK_THREAD, /* Fork bdi thread */
fff5b85a 352 KILL_THREAD, /* Kill inactive bdi thread */
adf39240 353 } action = NO_ACTION;
03ba3782
JA
354
355 /*
356 * Temporary measure, we want to make sure we don't see
357 * dirty data on the default backing_dev_info
358 */
6467716a
AB
359 if (wb_has_dirty_io(me) || !list_empty(&me->bdi->work_list)) {
360 del_timer(&me->wakeup_timer);
03ba3782 361 wb_do_writeback(me, 0);
6467716a 362 }
03ba3782 363
cfc4ba53 364 spin_lock_bh(&bdi_lock);
09f40f98
JK
365 /*
366 * In the following loop we are going to check whether we have
367 * some work to do without any synchronization with tasks
20c8c628
AM
368 * waking us up to do work for them. Set the task state here
369 * so that we don't miss wakeups after verifying conditions.
09f40f98 370 */
c5f7ad23 371 set_current_state(TASK_INTERRUPTIBLE);
03ba3782 372
78c40cb6 373 list_for_each_entry(bdi, &bdi_list, bdi_list) {
adf39240
AB
374 bool have_dirty_io;
375
376 if (!bdi_cap_writeback_dirty(bdi) ||
377 bdi_cap_flush_forker(bdi))
03ba3782
JA
378 continue;
379
080dcec4
AB
380 WARN(!test_bit(BDI_registered, &bdi->state),
381 "bdi %p/%s is not registered!\n", bdi, bdi->name);
382
adf39240
AB
383 have_dirty_io = !list_empty(&bdi->work_list) ||
384 wb_has_dirty_io(&bdi->wb);
78c40cb6
AB
385
386 /*
adf39240
AB
387 * If the bdi has work to do, but the thread does not
388 * exist - create it.
78c40cb6 389 */
adf39240
AB
390 if (!bdi->wb.task && have_dirty_io) {
391 /*
392 * Set the pending bit - if someone will try to
393 * unregister this bdi - it'll wait on this bit.
394 */
395 set_bit(BDI_pending, &bdi->state);
396 action = FORK_THREAD;
397 break;
398 }
fff5b85a 399
6bf05d03
JA
400 spin_lock(&bdi->wb_lock);
401
fff5b85a
AB
402 /*
403 * If there is no work to do and the bdi thread was
404 * inactive long enough - kill it. The wb_lock is taken
405 * to make sure no-one adds more work to this bdi and
406 * wakes the bdi thread up.
407 */
408 if (bdi->wb.task && !have_dirty_io &&
409 time_after(jiffies, bdi->wb.last_active +
410 bdi_longest_inactive())) {
411 task = bdi->wb.task;
412 bdi->wb.task = NULL;
413 spin_unlock(&bdi->wb_lock);
414 set_bit(BDI_pending, &bdi->state);
415 action = KILL_THREAD;
416 break;
417 }
6bf05d03 418 spin_unlock(&bdi->wb_lock);
03ba3782 419 }
080dcec4 420 spin_unlock_bh(&bdi_lock);
03ba3782 421
c4ec7908
AB
422 /* Keep working if default bdi still has things to do */
423 if (!list_empty(&me->bdi->work_list))
424 __set_current_state(TASK_RUNNING);
425
adf39240
AB
426 switch (action) {
427 case FORK_THREAD:
428 __set_current_state(TASK_RUNNING);
6628bc74
AB
429 task = kthread_create(bdi_writeback_thread, &bdi->wb,
430 "flush-%s", dev_name(bdi->dev));
adf39240
AB
431 if (IS_ERR(task)) {
432 /*
433 * If thread creation fails, force writeout of
d46db3d5
WF
434 * the bdi from the thread. Hopefully 1024 is
435 * large enough for efficient IO.
adf39240 436 */
0e175a18
CW
437 writeback_inodes_wb(&bdi->wb, 1024,
438 WB_REASON_FORKER_THREAD);
fff5b85a
AB
439 } else {
440 /*
441 * The spinlock makes sure we do not lose
442 * wake-ups when racing with 'bdi_queue_work()'.
6628bc74
AB
443 * And as soon as the bdi thread is visible, we
444 * can start it.
fff5b85a 445 */
6467716a 446 spin_lock_bh(&bdi->wb_lock);
adf39240 447 bdi->wb.task = task;
6467716a 448 spin_unlock_bh(&bdi->wb_lock);
6628bc74 449 wake_up_process(task);
fff5b85a 450 }
5a042aa4 451 bdi_clear_pending(bdi);
fff5b85a
AB
452 break;
453
454 case KILL_THREAD:
455 __set_current_state(TASK_RUNNING);
456 kthread_stop(task);
5a042aa4 457 bdi_clear_pending(bdi);
adf39240 458 break;
03ba3782 459
adf39240 460 case NO_ACTION:
253c34e9
AB
461 if (!wb_has_dirty_io(me) || !dirty_writeback_interval)
462 /*
463 * There are no dirty data. The only thing we
464 * should now care about is checking for
465 * inactive bdi threads and killing them. Thus,
466 * let's sleep for longer time, save energy and
467 * be friendly for battery-driven devices.
468 */
469 schedule_timeout(bdi_longest_inactive());
6423104b 470 else
253c34e9 471 schedule_timeout(msecs_to_jiffies(dirty_writeback_interval * 10));
03ba3782 472 try_to_freeze();
5a042aa4 473 break;
03ba3782 474 }
03ba3782
JA
475 }
476
477 return 0;
478}
479
cfc4ba53
JA
480/*
481 * Remove bdi from bdi_list, and ensure that it is no longer visible
482 */
483static void bdi_remove_from_list(struct backing_dev_info *bdi)
484{
485 spin_lock_bh(&bdi_lock);
486 list_del_rcu(&bdi->bdi_list);
487 spin_unlock_bh(&bdi_lock);
488
ef323088 489 synchronize_rcu_expedited();
cfc4ba53
JA
490}
491
cf0ca9fe
PZ
492int bdi_register(struct backing_dev_info *bdi, struct device *parent,
493 const char *fmt, ...)
494{
cf0ca9fe 495 va_list args;
cf0ca9fe
PZ
496 struct device *dev;
497
69fc208b 498 if (bdi->dev) /* The driver needs to use separate queues per device */
c284de61 499 return 0;
f1d0b063 500
cf0ca9fe 501 va_start(args, fmt);
19051c50 502 dev = device_create_vargs(bdi_class, parent, MKDEV(0, 0), bdi, fmt, args);
cf0ca9fe 503 va_end(args);
c284de61
AB
504 if (IS_ERR(dev))
505 return PTR_ERR(dev);
66f3b8e2 506
cf0ca9fe 507 bdi->dev = dev;
cf0ca9fe 508
03ba3782
JA
509 /*
510 * Just start the forker thread for our default backing_dev_info,
511 * and add other bdi's to the list. They will get a thread created
512 * on-demand when they need it.
513 */
514 if (bdi_cap_flush_forker(bdi)) {
515 struct bdi_writeback *wb = &bdi->wb;
516
6f904ff0 517 wb->task = kthread_run(bdi_forker_thread, wb, "bdi-%s",
03ba3782 518 dev_name(dev));
c284de61
AB
519 if (IS_ERR(wb->task))
520 return PTR_ERR(wb->task);
03ba3782
JA
521 }
522
523 bdi_debug_register(bdi, dev_name(dev));
500b067c 524 set_bit(BDI_registered, &bdi->state);
c284de61
AB
525
526 spin_lock_bh(&bdi_lock);
527 list_add_tail_rcu(&bdi->bdi_list, &bdi_list);
528 spin_unlock_bh(&bdi_lock);
529
455b2864 530 trace_writeback_bdi_register(bdi);
c284de61 531 return 0;
cf0ca9fe
PZ
532}
533EXPORT_SYMBOL(bdi_register);
534
535int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev)
536{
537 return bdi_register(bdi, NULL, "%u:%u", MAJOR(dev), MINOR(dev));
538}
539EXPORT_SYMBOL(bdi_register_dev);
540
03ba3782
JA
541/*
542 * Remove bdi from the global list and shutdown any threads we have running
543 */
544static void bdi_wb_shutdown(struct backing_dev_info *bdi)
66f3b8e2 545{
2673b4cf
RV
546 struct task_struct *task;
547
03ba3782
JA
548 if (!bdi_cap_writeback_dirty(bdi))
549 return;
550
551 /*
fff5b85a 552 * Make sure nobody finds us on the bdi_list anymore
03ba3782 553 */
fff5b85a 554 bdi_remove_from_list(bdi);
03ba3782
JA
555
556 /*
fff5b85a 557 * If setup is pending, wait for that to complete first
03ba3782 558 */
fff5b85a
AB
559 wait_on_bit(&bdi->state, BDI_pending, bdi_sched_wait,
560 TASK_UNINTERRUPTIBLE);
03ba3782
JA
561
562 /*
c1955ce3 563 * Finally, kill the kernel thread. We don't need to be RCU
8a32c441 564 * safe anymore, since the bdi is gone from visibility.
03ba3782 565 */
2673b4cf
RV
566 spin_lock_bh(&bdi->wb_lock);
567 task = bdi->wb.task;
568 bdi->wb.task = NULL;
569 spin_unlock_bh(&bdi->wb_lock);
570
571 if (task)
572 kthread_stop(task);
66f3b8e2
JA
573}
574
592b09a4
JA
575/*
576 * This bdi is going away now, make sure that no super_blocks point to it
577 */
578static void bdi_prune_sb(struct backing_dev_info *bdi)
579{
580 struct super_block *sb;
581
582 spin_lock(&sb_lock);
583 list_for_each_entry(sb, &super_blocks, s_list) {
584 if (sb->s_bdi == bdi)
95f28604 585 sb->s_bdi = &default_backing_dev_info;
592b09a4
JA
586 }
587 spin_unlock(&sb_lock);
588}
589
cf0ca9fe
PZ
590void bdi_unregister(struct backing_dev_info *bdi)
591{
2673b4cf
RV
592 struct device *dev = bdi->dev;
593
594 if (dev) {
ccb6108f 595 bdi_set_min_ratio(bdi, 0);
455b2864 596 trace_writeback_bdi_unregister(bdi);
8c4db335 597 bdi_prune_sb(bdi);
6467716a 598 del_timer_sync(&bdi->wb.wakeup_timer);
8c4db335 599
03ba3782
JA
600 if (!bdi_cap_flush_forker(bdi))
601 bdi_wb_shutdown(bdi);
76f1418b 602 bdi_debug_unregister(bdi);
2673b4cf
RV
603
604 spin_lock_bh(&bdi->wb_lock);
cf0ca9fe 605 bdi->dev = NULL;
2673b4cf
RV
606 spin_unlock_bh(&bdi->wb_lock);
607
608 device_unregister(dev);
cf0ca9fe
PZ
609 }
610}
611EXPORT_SYMBOL(bdi_unregister);
3fcfab16 612
6467716a
AB
613static void bdi_wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi)
614{
615 memset(wb, 0, sizeof(*wb));
616
617 wb->bdi = bdi;
618 wb->last_old_flush = jiffies;
619 INIT_LIST_HEAD(&wb->b_dirty);
620 INIT_LIST_HEAD(&wb->b_io);
621 INIT_LIST_HEAD(&wb->b_more_io);
f758eeab 622 spin_lock_init(&wb->list_lock);
6467716a
AB
623 setup_timer(&wb->wakeup_timer, wakeup_timer_fn, (unsigned long)bdi);
624}
625
e98be2d5
WF
626/*
627 * Initial write bandwidth: 100 MB/s
628 */
629#define INIT_BW (100 << (20 - PAGE_SHIFT))
630
b2e8fb6e
PZ
631int bdi_init(struct backing_dev_info *bdi)
632{
03ba3782 633 int i, err;
b2e8fb6e 634
cf0ca9fe
PZ
635 bdi->dev = NULL;
636
189d3c4a 637 bdi->min_ratio = 0;
a42dde04 638 bdi->max_ratio = 100;
eb608e3a 639 bdi->max_prop_frac = FPROP_FRAC_BASE;
03ba3782 640 spin_lock_init(&bdi->wb_lock);
66f3b8e2 641 INIT_LIST_HEAD(&bdi->bdi_list);
03ba3782
JA
642 INIT_LIST_HEAD(&bdi->work_list);
643
644 bdi_wb_init(&bdi->wb, bdi);
645
b2e8fb6e 646 for (i = 0; i < NR_BDI_STAT_ITEMS; i++) {
ea319518 647 err = percpu_counter_init(&bdi->bdi_stat[i], 0);
04fbfdc1
PZ
648 if (err)
649 goto err;
650 }
651
652 bdi->dirty_exceeded = 0;
e98be2d5
WF
653
654 bdi->bw_time_stamp = jiffies;
655 bdi->written_stamp = 0;
656
7381131c 657 bdi->balanced_dirty_ratelimit = INIT_BW;
be3ffa27 658 bdi->dirty_ratelimit = INIT_BW;
e98be2d5
WF
659 bdi->write_bandwidth = INIT_BW;
660 bdi->avg_write_bandwidth = INIT_BW;
661
eb608e3a 662 err = fprop_local_init_percpu(&bdi->completions);
04fbfdc1
PZ
663
664 if (err) {
665err:
4b01a0b1 666 while (i--)
04fbfdc1 667 percpu_counter_destroy(&bdi->bdi_stat[i]);
b2e8fb6e
PZ
668 }
669
670 return err;
671}
672EXPORT_SYMBOL(bdi_init);
673
674void bdi_destroy(struct backing_dev_info *bdi)
675{
676 int i;
677
ce5f8e77
JA
678 /*
679 * Splice our entries to the default_backing_dev_info, if this
680 * bdi disappears
681 */
682 if (bdi_has_dirty_io(bdi)) {
683 struct bdi_writeback *dst = &default_backing_dev_info.wb;
684
f758eeab 685 bdi_lock_two(&bdi->wb, dst);
ce5f8e77
JA
686 list_splice(&bdi->wb.b_dirty, &dst->b_dirty);
687 list_splice(&bdi->wb.b_io, &dst->b_io);
688 list_splice(&bdi->wb.b_more_io, &dst->b_more_io);
f758eeab
CH
689 spin_unlock(&bdi->wb.list_lock);
690 spin_unlock(&dst->list_lock);
ce5f8e77 691 }
66f3b8e2 692
cf0ca9fe
PZ
693 bdi_unregister(bdi);
694
7a401a97
RV
695 /*
696 * If bdi_unregister() had already been called earlier, the
697 * wakeup_timer could still be armed because bdi_prune_sb()
698 * can race with the bdi_wakeup_thread_delayed() calls from
699 * __mark_inode_dirty().
700 */
701 del_timer_sync(&bdi->wb.wakeup_timer);
702
b2e8fb6e
PZ
703 for (i = 0; i < NR_BDI_STAT_ITEMS; i++)
704 percpu_counter_destroy(&bdi->bdi_stat[i]);
04fbfdc1 705
eb608e3a 706 fprop_local_destroy_percpu(&bdi->completions);
b2e8fb6e
PZ
707}
708EXPORT_SYMBOL(bdi_destroy);
709
c3c53206
JA
710/*
711 * For use from filesystems to quickly init and register a bdi associated
712 * with dirty writeback
713 */
714int bdi_setup_and_register(struct backing_dev_info *bdi, char *name,
715 unsigned int cap)
716{
717 char tmp[32];
718 int err;
719
720 bdi->name = name;
721 bdi->capabilities = cap;
722 err = bdi_init(bdi);
723 if (err)
724 return err;
725
726 sprintf(tmp, "%.28s%s", name, "-%d");
727 err = bdi_register(bdi, NULL, tmp, atomic_long_inc_return(&bdi_seq));
728 if (err) {
729 bdi_destroy(bdi);
730 return err;
731 }
732
733 return 0;
734}
735EXPORT_SYMBOL(bdi_setup_and_register);
736
3fcfab16
AM
737static wait_queue_head_t congestion_wqh[2] = {
738 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]),
739 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1])
740 };
0e093d99 741static atomic_t nr_bdi_congested[2];
3fcfab16 742
1faa16d2 743void clear_bdi_congested(struct backing_dev_info *bdi, int sync)
3fcfab16
AM
744{
745 enum bdi_state bit;
1faa16d2 746 wait_queue_head_t *wqh = &congestion_wqh[sync];
3fcfab16 747
1faa16d2 748 bit = sync ? BDI_sync_congested : BDI_async_congested;
0e093d99
MG
749 if (test_and_clear_bit(bit, &bdi->state))
750 atomic_dec(&nr_bdi_congested[sync]);
3fcfab16
AM
751 smp_mb__after_clear_bit();
752 if (waitqueue_active(wqh))
753 wake_up(wqh);
754}
755EXPORT_SYMBOL(clear_bdi_congested);
756
1faa16d2 757void set_bdi_congested(struct backing_dev_info *bdi, int sync)
3fcfab16
AM
758{
759 enum bdi_state bit;
760
1faa16d2 761 bit = sync ? BDI_sync_congested : BDI_async_congested;
0e093d99
MG
762 if (!test_and_set_bit(bit, &bdi->state))
763 atomic_inc(&nr_bdi_congested[sync]);
3fcfab16
AM
764}
765EXPORT_SYMBOL(set_bdi_congested);
766
767/**
768 * congestion_wait - wait for a backing_dev to become uncongested
8aa7e847 769 * @sync: SYNC or ASYNC IO
3fcfab16
AM
770 * @timeout: timeout in jiffies
771 *
772 * Waits for up to @timeout jiffies for a backing_dev (any backing_dev) to exit
773 * write congestion. If no backing_devs are congested then just wait for the
774 * next write to be completed.
775 */
8aa7e847 776long congestion_wait(int sync, long timeout)
3fcfab16
AM
777{
778 long ret;
52bb9198 779 unsigned long start = jiffies;
3fcfab16 780 DEFINE_WAIT(wait);
8aa7e847 781 wait_queue_head_t *wqh = &congestion_wqh[sync];
3fcfab16
AM
782
783 prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
784 ret = io_schedule_timeout(timeout);
785 finish_wait(wqh, &wait);
52bb9198
MG
786
787 trace_writeback_congestion_wait(jiffies_to_usecs(timeout),
788 jiffies_to_usecs(jiffies - start));
789
3fcfab16
AM
790 return ret;
791}
792EXPORT_SYMBOL(congestion_wait);
04fbfdc1 793
0e093d99
MG
794/**
795 * wait_iff_congested - Conditionally wait for a backing_dev to become uncongested or a zone to complete writes
796 * @zone: A zone to check if it is heavily congested
797 * @sync: SYNC or ASYNC IO
798 * @timeout: timeout in jiffies
799 *
800 * In the event of a congested backing_dev (any backing_dev) and the given
801 * @zone has experienced recent congestion, this waits for up to @timeout
802 * jiffies for either a BDI to exit congestion of the given @sync queue
803 * or a write to complete.
804 *
25985edc 805 * In the absence of zone congestion, cond_resched() is called to yield
0e093d99
MG
806 * the processor if necessary but otherwise does not sleep.
807 *
808 * The return value is 0 if the sleep is for the full timeout. Otherwise,
809 * it is the number of jiffies that were still remaining when the function
810 * returned. return_value == timeout implies the function did not sleep.
811 */
812long wait_iff_congested(struct zone *zone, int sync, long timeout)
813{
814 long ret;
815 unsigned long start = jiffies;
816 DEFINE_WAIT(wait);
817 wait_queue_head_t *wqh = &congestion_wqh[sync];
818
819 /*
820 * If there is no congestion, or heavy congestion is not being
821 * encountered in the current zone, yield if necessary instead
822 * of sleeping on the congestion queue
823 */
824 if (atomic_read(&nr_bdi_congested[sync]) == 0 ||
825 !zone_is_reclaim_congested(zone)) {
826 cond_resched();
827
828 /* In case we scheduled, work out time remaining */
829 ret = timeout - (jiffies - start);
830 if (ret < 0)
831 ret = 0;
832
833 goto out;
834 }
835
836 /* Sleep until uncongested or a write happens */
837 prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
838 ret = io_schedule_timeout(timeout);
839 finish_wait(wqh, &wait);
840
841out:
842 trace_writeback_wait_iff_congested(jiffies_to_usecs(timeout),
843 jiffies_to_usecs(jiffies - start));
844
845 return ret;
846}
847EXPORT_SYMBOL(wait_iff_congested);
3965c9ae
WL
848
849int pdflush_proc_obsolete(struct ctl_table *table, int write,
850 void __user *buffer, size_t *lenp, loff_t *ppos)
851{
852 char kbuf[] = "0\n";
853
854 if (*ppos) {
855 *lenp = 0;
856 return 0;
857 }
858
859 if (copy_to_user(buffer, kbuf, sizeof(kbuf)))
860 return -EFAULT;
861 printk_once(KERN_WARNING "%s exported in /proc is scheduled for removal\n",
862 table->procname);
863
864 *lenp = 2;
865 *ppos += *lenp;
866 return 2;
867}