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1
2#include <linux/wait.h>
3#include <linux/backing-dev.h>
4#include <linux/kthread.h>
5#include <linux/freezer.h>
6#include <linux/fs.h>
7#include <linux/pagemap.h>
8#include <linux/mm.h>
9#include <linux/sched.h>
10#include <linux/module.h>
11#include <linux/writeback.h>
12#include <linux/device.h>
13#include <trace/events/writeback.h>
14
15static atomic_long_t bdi_seq = ATOMIC_LONG_INIT(0);
16
17struct backing_dev_info default_backing_dev_info = {
18 .name = "default",
19 .ra_pages = VM_MAX_READAHEAD * 1024 / PAGE_CACHE_SIZE,
20 .state = 0,
21 .capabilities = BDI_CAP_MAP_COPY,
22};
23EXPORT_SYMBOL_GPL(default_backing_dev_info);
24
25struct backing_dev_info noop_backing_dev_info = {
26 .name = "noop",
27 .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK,
28};
29EXPORT_SYMBOL_GPL(noop_backing_dev_info);
30
31static struct class *bdi_class;
32
33/*
34 * bdi_lock protects updates to bdi_list. bdi_list has RCU reader side
35 * locking.
36 */
37DEFINE_SPINLOCK(bdi_lock);
38LIST_HEAD(bdi_list);
39
40/* bdi_wq serves all asynchronous writeback tasks */
41struct workqueue_struct *bdi_wq;
42
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
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;
68 struct bdi_writeback *wb = &bdi->wb;
69 unsigned long background_thresh;
70 unsigned long dirty_thresh;
71 unsigned long bdi_thresh;
72 unsigned long nr_dirty, nr_io, nr_more_io;
73 struct inode *inode;
74
75 nr_dirty = nr_io = nr_more_io = 0;
76 spin_lock(&wb->list_lock);
77 list_for_each_entry(inode, &wb->b_dirty, i_wb_list)
78 nr_dirty++;
79 list_for_each_entry(inode, &wb->b_io, i_wb_list)
80 nr_io++;
81 list_for_each_entry(inode, &wb->b_more_io, i_wb_list)
82 nr_more_io++;
83 spin_unlock(&wb->list_lock);
84
85 global_dirty_limits(&background_thresh, &dirty_thresh);
86 bdi_thresh = bdi_dirty_limit(bdi, dirty_thresh);
87
88#define K(x) ((x) << (PAGE_SHIFT - 10))
89 seq_printf(m,
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"
95 "BdiDirtied: %10lu kB\n"
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",
103 (unsigned long) K(bdi_stat(bdi, BDI_WRITEBACK)),
104 (unsigned long) K(bdi_stat(bdi, BDI_RECLAIMABLE)),
105 K(bdi_thresh),
106 K(dirty_thresh),
107 K(background_thresh),
108 (unsigned long) K(bdi_stat(bdi, BDI_DIRTIED)),
109 (unsigned long) K(bdi_stat(bdi, BDI_WRITTEN)),
110 (unsigned long) K(bdi->write_bandwidth),
111 nr_dirty,
112 nr_io,
113 nr_more_io,
114 !list_empty(&bdi->bdi_list), bdi->state);
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
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);
162 unsigned long read_ahead_kb;
163 ssize_t ret;
164
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;
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); \
183} \
184static DEVICE_ATTR_RW(name);
185
186BDI_SHOW(read_ahead_kb, K(bdi->ra_pages))
187
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);
192 unsigned int ratio;
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;
202
203 return ret;
204}
205BDI_SHOW(min_ratio, bdi->min_ratio)
206
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);
211 unsigned int ratio;
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;
221
222 return ret;
223}
224BDI_SHOW(max_ratio, bdi->max_ratio)
225
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}
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,
243};
244ATTRIBUTE_GROUPS(bdi_dev);
245
246static __init int bdi_class_init(void)
247{
248 bdi_class = class_create(THIS_MODULE, "bdi");
249 if (IS_ERR(bdi_class))
250 return PTR_ERR(bdi_class);
251
252 bdi_class->dev_groups = bdi_dev_groups;
253 bdi_debug_init();
254 return 0;
255}
256postcore_initcall(bdi_class_init);
257
258static int __init default_bdi_init(void)
259{
260 int err;
261
262 bdi_wq = alloc_workqueue("writeback", WQ_MEM_RECLAIM | WQ_FREEZABLE |
263 WQ_UNBOUND | WQ_SYSFS, 0);
264 if (!bdi_wq)
265 return -ENOMEM;
266
267 err = bdi_init(&default_backing_dev_info);
268 if (!err)
269 bdi_register(&default_backing_dev_info, NULL, "default");
270 err = bdi_init(&noop_backing_dev_info);
271
272 return err;
273}
274subsys_initcall(default_bdi_init);
275
276int bdi_has_dirty_io(struct backing_dev_info *bdi)
277{
278 return wb_has_dirty_io(&bdi->wb);
279}
280
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 *
292 * We have to be careful not to postpone flush work if it is scheduled for
293 * earlier. Thus we use queue_delayed_work().
294 */
295void bdi_wakeup_thread_delayed(struct backing_dev_info *bdi)
296{
297 unsigned long timeout;
298
299 timeout = msecs_to_jiffies(dirty_writeback_interval * 10);
300 spin_lock_bh(&bdi->wb_lock);
301 if (test_bit(BDI_registered, &bdi->state))
302 queue_delayed_work(bdi_wq, &bdi->wb.dwork, timeout);
303 spin_unlock_bh(&bdi->wb_lock);
304}
305
306/*
307 * Remove bdi from bdi_list, and ensure that it is no longer visible
308 */
309static void bdi_remove_from_list(struct backing_dev_info *bdi)
310{
311 spin_lock_bh(&bdi_lock);
312 list_del_rcu(&bdi->bdi_list);
313 spin_unlock_bh(&bdi_lock);
314
315 synchronize_rcu_expedited();
316}
317
318int bdi_register(struct backing_dev_info *bdi, struct device *parent,
319 const char *fmt, ...)
320{
321 va_list args;
322 struct device *dev;
323
324 if (bdi->dev) /* The driver needs to use separate queues per device */
325 return 0;
326
327 va_start(args, fmt);
328 dev = device_create_vargs(bdi_class, parent, MKDEV(0, 0), bdi, fmt, args);
329 va_end(args);
330 if (IS_ERR(dev))
331 return PTR_ERR(dev);
332
333 bdi->dev = dev;
334
335 bdi_debug_register(bdi, dev_name(dev));
336 set_bit(BDI_registered, &bdi->state);
337
338 spin_lock_bh(&bdi_lock);
339 list_add_tail_rcu(&bdi->bdi_list, &bdi_list);
340 spin_unlock_bh(&bdi_lock);
341
342 trace_writeback_bdi_register(bdi);
343 return 0;
344}
345EXPORT_SYMBOL(bdi_register);
346
347int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev)
348{
349 return bdi_register(bdi, NULL, "%u:%u", MAJOR(dev), MINOR(dev));
350}
351EXPORT_SYMBOL(bdi_register_dev);
352
353/*
354 * Remove bdi from the global list and shutdown any threads we have running
355 */
356static void bdi_wb_shutdown(struct backing_dev_info *bdi)
357{
358 if (!bdi_cap_writeback_dirty(bdi))
359 return;
360
361 /*
362 * Make sure nobody finds us on the bdi_list anymore
363 */
364 bdi_remove_from_list(bdi);
365
366 /* Make sure nobody queues further work */
367 spin_lock_bh(&bdi->wb_lock);
368 clear_bit(BDI_registered, &bdi->state);
369 spin_unlock_bh(&bdi->wb_lock);
370
371 /*
372 * Drain work list and shutdown the delayed_work. At this point,
373 * @bdi->bdi_list is empty telling bdi_Writeback_workfn() that @bdi
374 * is dying and its work_list needs to be drained no matter what.
375 */
376 mod_delayed_work(bdi_wq, &bdi->wb.dwork, 0);
377 flush_delayed_work(&bdi->wb.dwork);
378 WARN_ON(!list_empty(&bdi->work_list));
379
380 /*
381 * This shouldn't be necessary unless @bdi for some reason has
382 * unflushed dirty IO after work_list is drained. Do it anyway
383 * just in case.
384 */
385 cancel_delayed_work_sync(&bdi->wb.dwork);
386}
387
388/*
389 * This bdi is going away now, make sure that no super_blocks point to it
390 */
391static void bdi_prune_sb(struct backing_dev_info *bdi)
392{
393 struct super_block *sb;
394
395 spin_lock(&sb_lock);
396 list_for_each_entry(sb, &super_blocks, s_list) {
397 if (sb->s_bdi == bdi)
398 sb->s_bdi = &default_backing_dev_info;
399 }
400 spin_unlock(&sb_lock);
401}
402
403void bdi_unregister(struct backing_dev_info *bdi)
404{
405 struct device *dev = bdi->dev;
406
407 if (dev) {
408 bdi_set_min_ratio(bdi, 0);
409 trace_writeback_bdi_unregister(bdi);
410 bdi_prune_sb(bdi);
411
412 bdi_wb_shutdown(bdi);
413 bdi_debug_unregister(bdi);
414
415 spin_lock_bh(&bdi->wb_lock);
416 bdi->dev = NULL;
417 spin_unlock_bh(&bdi->wb_lock);
418
419 device_unregister(dev);
420 }
421}
422EXPORT_SYMBOL(bdi_unregister);
423
424static void bdi_wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi)
425{
426 memset(wb, 0, sizeof(*wb));
427
428 wb->bdi = bdi;
429 wb->last_old_flush = jiffies;
430 INIT_LIST_HEAD(&wb->b_dirty);
431 INIT_LIST_HEAD(&wb->b_io);
432 INIT_LIST_HEAD(&wb->b_more_io);
433 spin_lock_init(&wb->list_lock);
434 INIT_DELAYED_WORK(&wb->dwork, bdi_writeback_workfn);
435}
436
437/*
438 * Initial write bandwidth: 100 MB/s
439 */
440#define INIT_BW (100 << (20 - PAGE_SHIFT))
441
442int bdi_init(struct backing_dev_info *bdi)
443{
444 int i, err;
445
446 bdi->dev = NULL;
447
448 bdi->min_ratio = 0;
449 bdi->max_ratio = 100;
450 bdi->max_prop_frac = FPROP_FRAC_BASE;
451 spin_lock_init(&bdi->wb_lock);
452 INIT_LIST_HEAD(&bdi->bdi_list);
453 INIT_LIST_HEAD(&bdi->work_list);
454
455 bdi_wb_init(&bdi->wb, bdi);
456
457 for (i = 0; i < NR_BDI_STAT_ITEMS; i++) {
458 err = percpu_counter_init(&bdi->bdi_stat[i], 0);
459 if (err)
460 goto err;
461 }
462
463 bdi->dirty_exceeded = 0;
464
465 bdi->bw_time_stamp = jiffies;
466 bdi->written_stamp = 0;
467
468 bdi->balanced_dirty_ratelimit = INIT_BW;
469 bdi->dirty_ratelimit = INIT_BW;
470 bdi->write_bandwidth = INIT_BW;
471 bdi->avg_write_bandwidth = INIT_BW;
472
473 err = fprop_local_init_percpu(&bdi->completions);
474
475 if (err) {
476err:
477 while (i--)
478 percpu_counter_destroy(&bdi->bdi_stat[i]);
479 }
480
481 return err;
482}
483EXPORT_SYMBOL(bdi_init);
484
485void bdi_destroy(struct backing_dev_info *bdi)
486{
487 int i;
488
489 /*
490 * Splice our entries to the default_backing_dev_info, if this
491 * bdi disappears
492 */
493 if (bdi_has_dirty_io(bdi)) {
494 struct bdi_writeback *dst = &default_backing_dev_info.wb;
495
496 bdi_lock_two(&bdi->wb, dst);
497 list_splice(&bdi->wb.b_dirty, &dst->b_dirty);
498 list_splice(&bdi->wb.b_io, &dst->b_io);
499 list_splice(&bdi->wb.b_more_io, &dst->b_more_io);
500 spin_unlock(&bdi->wb.list_lock);
501 spin_unlock(&dst->list_lock);
502 }
503
504 bdi_unregister(bdi);
505
506 /*
507 * If bdi_unregister() had already been called earlier, the dwork
508 * could still be pending because bdi_prune_sb() can race with the
509 * bdi_wakeup_thread_delayed() calls from __mark_inode_dirty().
510 */
511 cancel_delayed_work_sync(&bdi->wb.dwork);
512
513 for (i = 0; i < NR_BDI_STAT_ITEMS; i++)
514 percpu_counter_destroy(&bdi->bdi_stat[i]);
515
516 fprop_local_destroy_percpu(&bdi->completions);
517}
518EXPORT_SYMBOL(bdi_destroy);
519
520/*
521 * For use from filesystems to quickly init and register a bdi associated
522 * with dirty writeback
523 */
524int bdi_setup_and_register(struct backing_dev_info *bdi, char *name,
525 unsigned int cap)
526{
527 int err;
528
529 bdi->name = name;
530 bdi->capabilities = cap;
531 err = bdi_init(bdi);
532 if (err)
533 return err;
534
535 err = bdi_register(bdi, NULL, "%.28s-%ld", name,
536 atomic_long_inc_return(&bdi_seq));
537 if (err) {
538 bdi_destroy(bdi);
539 return err;
540 }
541
542 return 0;
543}
544EXPORT_SYMBOL(bdi_setup_and_register);
545
546static wait_queue_head_t congestion_wqh[2] = {
547 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]),
548 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1])
549 };
550static atomic_t nr_bdi_congested[2];
551
552void clear_bdi_congested(struct backing_dev_info *bdi, int sync)
553{
554 enum bdi_state bit;
555 wait_queue_head_t *wqh = &congestion_wqh[sync];
556
557 bit = sync ? BDI_sync_congested : BDI_async_congested;
558 if (test_and_clear_bit(bit, &bdi->state))
559 atomic_dec(&nr_bdi_congested[sync]);
560 smp_mb__after_clear_bit();
561 if (waitqueue_active(wqh))
562 wake_up(wqh);
563}
564EXPORT_SYMBOL(clear_bdi_congested);
565
566void set_bdi_congested(struct backing_dev_info *bdi, int sync)
567{
568 enum bdi_state bit;
569
570 bit = sync ? BDI_sync_congested : BDI_async_congested;
571 if (!test_and_set_bit(bit, &bdi->state))
572 atomic_inc(&nr_bdi_congested[sync]);
573}
574EXPORT_SYMBOL(set_bdi_congested);
575
576/**
577 * congestion_wait - wait for a backing_dev to become uncongested
578 * @sync: SYNC or ASYNC IO
579 * @timeout: timeout in jiffies
580 *
581 * Waits for up to @timeout jiffies for a backing_dev (any backing_dev) to exit
582 * write congestion. If no backing_devs are congested then just wait for the
583 * next write to be completed.
584 */
585long congestion_wait(int sync, long timeout)
586{
587 long ret;
588 unsigned long start = jiffies;
589 DEFINE_WAIT(wait);
590 wait_queue_head_t *wqh = &congestion_wqh[sync];
591
592 prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
593 ret = io_schedule_timeout(timeout);
594 finish_wait(wqh, &wait);
595
596 trace_writeback_congestion_wait(jiffies_to_usecs(timeout),
597 jiffies_to_usecs(jiffies - start));
598
599 return ret;
600}
601EXPORT_SYMBOL(congestion_wait);
602
603/**
604 * wait_iff_congested - Conditionally wait for a backing_dev to become uncongested or a zone to complete writes
605 * @zone: A zone to check if it is heavily congested
606 * @sync: SYNC or ASYNC IO
607 * @timeout: timeout in jiffies
608 *
609 * In the event of a congested backing_dev (any backing_dev) and the given
610 * @zone has experienced recent congestion, this waits for up to @timeout
611 * jiffies for either a BDI to exit congestion of the given @sync queue
612 * or a write to complete.
613 *
614 * In the absence of zone congestion, cond_resched() is called to yield
615 * the processor if necessary but otherwise does not sleep.
616 *
617 * The return value is 0 if the sleep is for the full timeout. Otherwise,
618 * it is the number of jiffies that were still remaining when the function
619 * returned. return_value == timeout implies the function did not sleep.
620 */
621long wait_iff_congested(struct zone *zone, int sync, long timeout)
622{
623 long ret;
624 unsigned long start = jiffies;
625 DEFINE_WAIT(wait);
626 wait_queue_head_t *wqh = &congestion_wqh[sync];
627
628 /*
629 * If there is no congestion, or heavy congestion is not being
630 * encountered in the current zone, yield if necessary instead
631 * of sleeping on the congestion queue
632 */
633 if (atomic_read(&nr_bdi_congested[sync]) == 0 ||
634 !zone_is_reclaim_congested(zone)) {
635 cond_resched();
636
637 /* In case we scheduled, work out time remaining */
638 ret = timeout - (jiffies - start);
639 if (ret < 0)
640 ret = 0;
641
642 goto out;
643 }
644
645 /* Sleep until uncongested or a write happens */
646 prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
647 ret = io_schedule_timeout(timeout);
648 finish_wait(wqh, &wait);
649
650out:
651 trace_writeback_wait_iff_congested(jiffies_to_usecs(timeout),
652 jiffies_to_usecs(jiffies - start));
653
654 return ret;
655}
656EXPORT_SYMBOL(wait_iff_congested);
657
658int pdflush_proc_obsolete(struct ctl_table *table, int write,
659 void __user *buffer, size_t *lenp, loff_t *ppos)
660{
661 char kbuf[] = "0\n";
662
663 if (*ppos || *lenp < sizeof(kbuf)) {
664 *lenp = 0;
665 return 0;
666 }
667
668 if (copy_to_user(buffer, kbuf, sizeof(kbuf)))
669 return -EFAULT;
670 printk_once(KERN_WARNING "%s exported in /proc is scheduled for removal\n",
671 table->procname);
672
673 *lenp = 2;
674 *ppos += *lenp;
675 return 2;
676}
1
2#include <linux/wait.h>
3#include <linux/backing-dev.h>
4#include <linux/kthread.h>
5#include <linux/freezer.h>
6#include <linux/fs.h>
7#include <linux/pagemap.h>
8#include <linux/mm.h>
9#include <linux/sched.h>
10#include <linux/module.h>
11#include <linux/writeback.h>
12#include <linux/device.h>
13#include <trace/events/writeback.h>
14
15static atomic_long_t bdi_seq = ATOMIC_LONG_INIT(0);
16
17struct backing_dev_info noop_backing_dev_info = {
18 .name = "noop",
19 .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK,
20};
21EXPORT_SYMBOL_GPL(noop_backing_dev_info);
22
23static struct class *bdi_class;
24
25/*
26 * bdi_lock protects updates to bdi_list. bdi_list has RCU reader side
27 * locking.
28 */
29DEFINE_SPINLOCK(bdi_lock);
30LIST_HEAD(bdi_list);
31
32/* bdi_wq serves all asynchronous writeback tasks */
33struct workqueue_struct *bdi_wq;
34
35#ifdef CONFIG_DEBUG_FS
36#include <linux/debugfs.h>
37#include <linux/seq_file.h>
38
39static struct dentry *bdi_debug_root;
40
41static void bdi_debug_init(void)
42{
43 bdi_debug_root = debugfs_create_dir("bdi", NULL);
44}
45
46static int bdi_debug_stats_show(struct seq_file *m, void *v)
47{
48 struct backing_dev_info *bdi = m->private;
49 struct bdi_writeback *wb = &bdi->wb;
50 unsigned long background_thresh;
51 unsigned long dirty_thresh;
52 unsigned long wb_thresh;
53 unsigned long nr_dirty, nr_io, nr_more_io, nr_dirty_time;
54 struct inode *inode;
55
56 nr_dirty = nr_io = nr_more_io = nr_dirty_time = 0;
57 spin_lock(&wb->list_lock);
58 list_for_each_entry(inode, &wb->b_dirty, i_io_list)
59 nr_dirty++;
60 list_for_each_entry(inode, &wb->b_io, i_io_list)
61 nr_io++;
62 list_for_each_entry(inode, &wb->b_more_io, i_io_list)
63 nr_more_io++;
64 list_for_each_entry(inode, &wb->b_dirty_time, i_io_list)
65 if (inode->i_state & I_DIRTY_TIME)
66 nr_dirty_time++;
67 spin_unlock(&wb->list_lock);
68
69 global_dirty_limits(&background_thresh, &dirty_thresh);
70 wb_thresh = wb_calc_thresh(wb, dirty_thresh);
71
72#define K(x) ((x) << (PAGE_SHIFT - 10))
73 seq_printf(m,
74 "BdiWriteback: %10lu kB\n"
75 "BdiReclaimable: %10lu kB\n"
76 "BdiDirtyThresh: %10lu kB\n"
77 "DirtyThresh: %10lu kB\n"
78 "BackgroundThresh: %10lu kB\n"
79 "BdiDirtied: %10lu kB\n"
80 "BdiWritten: %10lu kB\n"
81 "BdiWriteBandwidth: %10lu kBps\n"
82 "b_dirty: %10lu\n"
83 "b_io: %10lu\n"
84 "b_more_io: %10lu\n"
85 "b_dirty_time: %10lu\n"
86 "bdi_list: %10u\n"
87 "state: %10lx\n",
88 (unsigned long) K(wb_stat(wb, WB_WRITEBACK)),
89 (unsigned long) K(wb_stat(wb, WB_RECLAIMABLE)),
90 K(wb_thresh),
91 K(dirty_thresh),
92 K(background_thresh),
93 (unsigned long) K(wb_stat(wb, WB_DIRTIED)),
94 (unsigned long) K(wb_stat(wb, WB_WRITTEN)),
95 (unsigned long) K(wb->write_bandwidth),
96 nr_dirty,
97 nr_io,
98 nr_more_io,
99 nr_dirty_time,
100 !list_empty(&bdi->bdi_list), bdi->wb.state);
101#undef K
102
103 return 0;
104}
105
106static int bdi_debug_stats_open(struct inode *inode, struct file *file)
107{
108 return single_open(file, bdi_debug_stats_show, inode->i_private);
109}
110
111static const struct file_operations bdi_debug_stats_fops = {
112 .open = bdi_debug_stats_open,
113 .read = seq_read,
114 .llseek = seq_lseek,
115 .release = single_release,
116};
117
118static void bdi_debug_register(struct backing_dev_info *bdi, const char *name)
119{
120 bdi->debug_dir = debugfs_create_dir(name, bdi_debug_root);
121 bdi->debug_stats = debugfs_create_file("stats", 0444, bdi->debug_dir,
122 bdi, &bdi_debug_stats_fops);
123}
124
125static void bdi_debug_unregister(struct backing_dev_info *bdi)
126{
127 debugfs_remove(bdi->debug_stats);
128 debugfs_remove(bdi->debug_dir);
129}
130#else
131static inline void bdi_debug_init(void)
132{
133}
134static inline void bdi_debug_register(struct backing_dev_info *bdi,
135 const char *name)
136{
137}
138static inline void bdi_debug_unregister(struct backing_dev_info *bdi)
139{
140}
141#endif
142
143static ssize_t read_ahead_kb_store(struct device *dev,
144 struct device_attribute *attr,
145 const char *buf, size_t count)
146{
147 struct backing_dev_info *bdi = dev_get_drvdata(dev);
148 unsigned long read_ahead_kb;
149 ssize_t ret;
150
151 ret = kstrtoul(buf, 10, &read_ahead_kb);
152 if (ret < 0)
153 return ret;
154
155 bdi->ra_pages = read_ahead_kb >> (PAGE_SHIFT - 10);
156
157 return count;
158}
159
160#define K(pages) ((pages) << (PAGE_SHIFT - 10))
161
162#define BDI_SHOW(name, expr) \
163static ssize_t name##_show(struct device *dev, \
164 struct device_attribute *attr, char *page) \
165{ \
166 struct backing_dev_info *bdi = dev_get_drvdata(dev); \
167 \
168 return snprintf(page, PAGE_SIZE-1, "%lld\n", (long long)expr); \
169} \
170static DEVICE_ATTR_RW(name);
171
172BDI_SHOW(read_ahead_kb, K(bdi->ra_pages))
173
174static ssize_t min_ratio_store(struct device *dev,
175 struct device_attribute *attr, const char *buf, size_t count)
176{
177 struct backing_dev_info *bdi = dev_get_drvdata(dev);
178 unsigned int ratio;
179 ssize_t ret;
180
181 ret = kstrtouint(buf, 10, &ratio);
182 if (ret < 0)
183 return ret;
184
185 ret = bdi_set_min_ratio(bdi, ratio);
186 if (!ret)
187 ret = count;
188
189 return ret;
190}
191BDI_SHOW(min_ratio, bdi->min_ratio)
192
193static ssize_t max_ratio_store(struct device *dev,
194 struct device_attribute *attr, const char *buf, size_t count)
195{
196 struct backing_dev_info *bdi = dev_get_drvdata(dev);
197 unsigned int ratio;
198 ssize_t ret;
199
200 ret = kstrtouint(buf, 10, &ratio);
201 if (ret < 0)
202 return ret;
203
204 ret = bdi_set_max_ratio(bdi, ratio);
205 if (!ret)
206 ret = count;
207
208 return ret;
209}
210BDI_SHOW(max_ratio, bdi->max_ratio)
211
212static ssize_t stable_pages_required_show(struct device *dev,
213 struct device_attribute *attr,
214 char *page)
215{
216 struct backing_dev_info *bdi = dev_get_drvdata(dev);
217
218 return snprintf(page, PAGE_SIZE-1, "%d\n",
219 bdi_cap_stable_pages_required(bdi) ? 1 : 0);
220}
221static DEVICE_ATTR_RO(stable_pages_required);
222
223static struct attribute *bdi_dev_attrs[] = {
224 &dev_attr_read_ahead_kb.attr,
225 &dev_attr_min_ratio.attr,
226 &dev_attr_max_ratio.attr,
227 &dev_attr_stable_pages_required.attr,
228 NULL,
229};
230ATTRIBUTE_GROUPS(bdi_dev);
231
232static __init int bdi_class_init(void)
233{
234 bdi_class = class_create(THIS_MODULE, "bdi");
235 if (IS_ERR(bdi_class))
236 return PTR_ERR(bdi_class);
237
238 bdi_class->dev_groups = bdi_dev_groups;
239 bdi_debug_init();
240 return 0;
241}
242postcore_initcall(bdi_class_init);
243
244static int __init default_bdi_init(void)
245{
246 int err;
247
248 bdi_wq = alloc_workqueue("writeback", WQ_MEM_RECLAIM | WQ_FREEZABLE |
249 WQ_UNBOUND | WQ_SYSFS, 0);
250 if (!bdi_wq)
251 return -ENOMEM;
252
253 err = bdi_init(&noop_backing_dev_info);
254
255 return err;
256}
257subsys_initcall(default_bdi_init);
258
259/*
260 * This function is used when the first inode for this wb is marked dirty. It
261 * wakes-up the corresponding bdi thread which should then take care of the
262 * periodic background write-out of dirty inodes. Since the write-out would
263 * starts only 'dirty_writeback_interval' centisecs from now anyway, we just
264 * set up a timer which wakes the bdi thread up later.
265 *
266 * Note, we wouldn't bother setting up the timer, but this function is on the
267 * fast-path (used by '__mark_inode_dirty()'), so we save few context switches
268 * by delaying the wake-up.
269 *
270 * We have to be careful not to postpone flush work if it is scheduled for
271 * earlier. Thus we use queue_delayed_work().
272 */
273void wb_wakeup_delayed(struct bdi_writeback *wb)
274{
275 unsigned long timeout;
276
277 timeout = msecs_to_jiffies(dirty_writeback_interval * 10);
278 spin_lock_bh(&wb->work_lock);
279 if (test_bit(WB_registered, &wb->state))
280 queue_delayed_work(bdi_wq, &wb->dwork, timeout);
281 spin_unlock_bh(&wb->work_lock);
282}
283
284/*
285 * Initial write bandwidth: 100 MB/s
286 */
287#define INIT_BW (100 << (20 - PAGE_SHIFT))
288
289static int wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi,
290 int blkcg_id, gfp_t gfp)
291{
292 int i, err;
293
294 memset(wb, 0, sizeof(*wb));
295
296 wb->bdi = bdi;
297 wb->last_old_flush = jiffies;
298 INIT_LIST_HEAD(&wb->b_dirty);
299 INIT_LIST_HEAD(&wb->b_io);
300 INIT_LIST_HEAD(&wb->b_more_io);
301 INIT_LIST_HEAD(&wb->b_dirty_time);
302 spin_lock_init(&wb->list_lock);
303
304 wb->bw_time_stamp = jiffies;
305 wb->balanced_dirty_ratelimit = INIT_BW;
306 wb->dirty_ratelimit = INIT_BW;
307 wb->write_bandwidth = INIT_BW;
308 wb->avg_write_bandwidth = INIT_BW;
309
310 spin_lock_init(&wb->work_lock);
311 INIT_LIST_HEAD(&wb->work_list);
312 INIT_DELAYED_WORK(&wb->dwork, wb_workfn);
313
314 wb->congested = wb_congested_get_create(bdi, blkcg_id, gfp);
315 if (!wb->congested)
316 return -ENOMEM;
317
318 err = fprop_local_init_percpu(&wb->completions, gfp);
319 if (err)
320 goto out_put_cong;
321
322 for (i = 0; i < NR_WB_STAT_ITEMS; i++) {
323 err = percpu_counter_init(&wb->stat[i], 0, gfp);
324 if (err)
325 goto out_destroy_stat;
326 }
327
328 return 0;
329
330out_destroy_stat:
331 while (i--)
332 percpu_counter_destroy(&wb->stat[i]);
333 fprop_local_destroy_percpu(&wb->completions);
334out_put_cong:
335 wb_congested_put(wb->congested);
336 return err;
337}
338
339/*
340 * Remove bdi from the global list and shutdown any threads we have running
341 */
342static void wb_shutdown(struct bdi_writeback *wb)
343{
344 /* Make sure nobody queues further work */
345 spin_lock_bh(&wb->work_lock);
346 if (!test_and_clear_bit(WB_registered, &wb->state)) {
347 spin_unlock_bh(&wb->work_lock);
348 return;
349 }
350 spin_unlock_bh(&wb->work_lock);
351
352 /*
353 * Drain work list and shutdown the delayed_work. !WB_registered
354 * tells wb_workfn() that @wb is dying and its work_list needs to
355 * be drained no matter what.
356 */
357 mod_delayed_work(bdi_wq, &wb->dwork, 0);
358 flush_delayed_work(&wb->dwork);
359 WARN_ON(!list_empty(&wb->work_list));
360}
361
362static void wb_exit(struct bdi_writeback *wb)
363{
364 int i;
365
366 WARN_ON(delayed_work_pending(&wb->dwork));
367
368 for (i = 0; i < NR_WB_STAT_ITEMS; i++)
369 percpu_counter_destroy(&wb->stat[i]);
370
371 fprop_local_destroy_percpu(&wb->completions);
372 wb_congested_put(wb->congested);
373}
374
375#ifdef CONFIG_CGROUP_WRITEBACK
376
377#include <linux/memcontrol.h>
378
379/*
380 * cgwb_lock protects bdi->cgwb_tree, bdi->cgwb_congested_tree,
381 * blkcg->cgwb_list, and memcg->cgwb_list. bdi->cgwb_tree is also RCU
382 * protected. cgwb_release_wait is used to wait for the completion of cgwb
383 * releases from bdi destruction path.
384 */
385static DEFINE_SPINLOCK(cgwb_lock);
386static DECLARE_WAIT_QUEUE_HEAD(cgwb_release_wait);
387
388/**
389 * wb_congested_get_create - get or create a wb_congested
390 * @bdi: associated bdi
391 * @blkcg_id: ID of the associated blkcg
392 * @gfp: allocation mask
393 *
394 * Look up the wb_congested for @blkcg_id on @bdi. If missing, create one.
395 * The returned wb_congested has its reference count incremented. Returns
396 * NULL on failure.
397 */
398struct bdi_writeback_congested *
399wb_congested_get_create(struct backing_dev_info *bdi, int blkcg_id, gfp_t gfp)
400{
401 struct bdi_writeback_congested *new_congested = NULL, *congested;
402 struct rb_node **node, *parent;
403 unsigned long flags;
404retry:
405 spin_lock_irqsave(&cgwb_lock, flags);
406
407 node = &bdi->cgwb_congested_tree.rb_node;
408 parent = NULL;
409
410 while (*node != NULL) {
411 parent = *node;
412 congested = container_of(parent, struct bdi_writeback_congested,
413 rb_node);
414 if (congested->blkcg_id < blkcg_id)
415 node = &parent->rb_left;
416 else if (congested->blkcg_id > blkcg_id)
417 node = &parent->rb_right;
418 else
419 goto found;
420 }
421
422 if (new_congested) {
423 /* !found and storage for new one already allocated, insert */
424 congested = new_congested;
425 new_congested = NULL;
426 rb_link_node(&congested->rb_node, parent, node);
427 rb_insert_color(&congested->rb_node, &bdi->cgwb_congested_tree);
428 goto found;
429 }
430
431 spin_unlock_irqrestore(&cgwb_lock, flags);
432
433 /* allocate storage for new one and retry */
434 new_congested = kzalloc(sizeof(*new_congested), gfp);
435 if (!new_congested)
436 return NULL;
437
438 atomic_set(&new_congested->refcnt, 0);
439 new_congested->bdi = bdi;
440 new_congested->blkcg_id = blkcg_id;
441 goto retry;
442
443found:
444 atomic_inc(&congested->refcnt);
445 spin_unlock_irqrestore(&cgwb_lock, flags);
446 kfree(new_congested);
447 return congested;
448}
449
450/**
451 * wb_congested_put - put a wb_congested
452 * @congested: wb_congested to put
453 *
454 * Put @congested and destroy it if the refcnt reaches zero.
455 */
456void wb_congested_put(struct bdi_writeback_congested *congested)
457{
458 unsigned long flags;
459
460 local_irq_save(flags);
461 if (!atomic_dec_and_lock(&congested->refcnt, &cgwb_lock)) {
462 local_irq_restore(flags);
463 return;
464 }
465
466 /* bdi might already have been destroyed leaving @congested unlinked */
467 if (congested->bdi) {
468 rb_erase(&congested->rb_node,
469 &congested->bdi->cgwb_congested_tree);
470 congested->bdi = NULL;
471 }
472
473 spin_unlock_irqrestore(&cgwb_lock, flags);
474 kfree(congested);
475}
476
477static void cgwb_release_workfn(struct work_struct *work)
478{
479 struct bdi_writeback *wb = container_of(work, struct bdi_writeback,
480 release_work);
481 struct backing_dev_info *bdi = wb->bdi;
482
483 spin_lock_irq(&cgwb_lock);
484 list_del_rcu(&wb->bdi_node);
485 spin_unlock_irq(&cgwb_lock);
486
487 wb_shutdown(wb);
488
489 css_put(wb->memcg_css);
490 css_put(wb->blkcg_css);
491
492 fprop_local_destroy_percpu(&wb->memcg_completions);
493 percpu_ref_exit(&wb->refcnt);
494 wb_exit(wb);
495 kfree_rcu(wb, rcu);
496
497 if (atomic_dec_and_test(&bdi->usage_cnt))
498 wake_up_all(&cgwb_release_wait);
499}
500
501static void cgwb_release(struct percpu_ref *refcnt)
502{
503 struct bdi_writeback *wb = container_of(refcnt, struct bdi_writeback,
504 refcnt);
505 schedule_work(&wb->release_work);
506}
507
508static void cgwb_kill(struct bdi_writeback *wb)
509{
510 lockdep_assert_held(&cgwb_lock);
511
512 WARN_ON(!radix_tree_delete(&wb->bdi->cgwb_tree, wb->memcg_css->id));
513 list_del(&wb->memcg_node);
514 list_del(&wb->blkcg_node);
515 percpu_ref_kill(&wb->refcnt);
516}
517
518static int cgwb_create(struct backing_dev_info *bdi,
519 struct cgroup_subsys_state *memcg_css, gfp_t gfp)
520{
521 struct mem_cgroup *memcg;
522 struct cgroup_subsys_state *blkcg_css;
523 struct blkcg *blkcg;
524 struct list_head *memcg_cgwb_list, *blkcg_cgwb_list;
525 struct bdi_writeback *wb;
526 unsigned long flags;
527 int ret = 0;
528
529 memcg = mem_cgroup_from_css(memcg_css);
530 blkcg_css = cgroup_get_e_css(memcg_css->cgroup, &io_cgrp_subsys);
531 blkcg = css_to_blkcg(blkcg_css);
532 memcg_cgwb_list = mem_cgroup_cgwb_list(memcg);
533 blkcg_cgwb_list = &blkcg->cgwb_list;
534
535 /* look up again under lock and discard on blkcg mismatch */
536 spin_lock_irqsave(&cgwb_lock, flags);
537 wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id);
538 if (wb && wb->blkcg_css != blkcg_css) {
539 cgwb_kill(wb);
540 wb = NULL;
541 }
542 spin_unlock_irqrestore(&cgwb_lock, flags);
543 if (wb)
544 goto out_put;
545
546 /* need to create a new one */
547 wb = kmalloc(sizeof(*wb), gfp);
548 if (!wb)
549 return -ENOMEM;
550
551 ret = wb_init(wb, bdi, blkcg_css->id, gfp);
552 if (ret)
553 goto err_free;
554
555 ret = percpu_ref_init(&wb->refcnt, cgwb_release, 0, gfp);
556 if (ret)
557 goto err_wb_exit;
558
559 ret = fprop_local_init_percpu(&wb->memcg_completions, gfp);
560 if (ret)
561 goto err_ref_exit;
562
563 wb->memcg_css = memcg_css;
564 wb->blkcg_css = blkcg_css;
565 INIT_WORK(&wb->release_work, cgwb_release_workfn);
566 set_bit(WB_registered, &wb->state);
567
568 /*
569 * The root wb determines the registered state of the whole bdi and
570 * memcg_cgwb_list and blkcg_cgwb_list's next pointers indicate
571 * whether they're still online. Don't link @wb if any is dead.
572 * See wb_memcg_offline() and wb_blkcg_offline().
573 */
574 ret = -ENODEV;
575 spin_lock_irqsave(&cgwb_lock, flags);
576 if (test_bit(WB_registered, &bdi->wb.state) &&
577 blkcg_cgwb_list->next && memcg_cgwb_list->next) {
578 /* we might have raced another instance of this function */
579 ret = radix_tree_insert(&bdi->cgwb_tree, memcg_css->id, wb);
580 if (!ret) {
581 atomic_inc(&bdi->usage_cnt);
582 list_add_tail_rcu(&wb->bdi_node, &bdi->wb_list);
583 list_add(&wb->memcg_node, memcg_cgwb_list);
584 list_add(&wb->blkcg_node, blkcg_cgwb_list);
585 css_get(memcg_css);
586 css_get(blkcg_css);
587 }
588 }
589 spin_unlock_irqrestore(&cgwb_lock, flags);
590 if (ret) {
591 if (ret == -EEXIST)
592 ret = 0;
593 goto err_fprop_exit;
594 }
595 goto out_put;
596
597err_fprop_exit:
598 fprop_local_destroy_percpu(&wb->memcg_completions);
599err_ref_exit:
600 percpu_ref_exit(&wb->refcnt);
601err_wb_exit:
602 wb_exit(wb);
603err_free:
604 kfree(wb);
605out_put:
606 css_put(blkcg_css);
607 return ret;
608}
609
610/**
611 * wb_get_create - get wb for a given memcg, create if necessary
612 * @bdi: target bdi
613 * @memcg_css: cgroup_subsys_state of the target memcg (must have positive ref)
614 * @gfp: allocation mask to use
615 *
616 * Try to get the wb for @memcg_css on @bdi. If it doesn't exist, try to
617 * create one. The returned wb has its refcount incremented.
618 *
619 * This function uses css_get() on @memcg_css and thus expects its refcnt
620 * to be positive on invocation. IOW, rcu_read_lock() protection on
621 * @memcg_css isn't enough. try_get it before calling this function.
622 *
623 * A wb is keyed by its associated memcg. As blkcg implicitly enables
624 * memcg on the default hierarchy, memcg association is guaranteed to be
625 * more specific (equal or descendant to the associated blkcg) and thus can
626 * identify both the memcg and blkcg associations.
627 *
628 * Because the blkcg associated with a memcg may change as blkcg is enabled
629 * and disabled closer to root in the hierarchy, each wb keeps track of
630 * both the memcg and blkcg associated with it and verifies the blkcg on
631 * each lookup. On mismatch, the existing wb is discarded and a new one is
632 * created.
633 */
634struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi,
635 struct cgroup_subsys_state *memcg_css,
636 gfp_t gfp)
637{
638 struct bdi_writeback *wb;
639
640 might_sleep_if(gfpflags_allow_blocking(gfp));
641
642 if (!memcg_css->parent)
643 return &bdi->wb;
644
645 do {
646 rcu_read_lock();
647 wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id);
648 if (wb) {
649 struct cgroup_subsys_state *blkcg_css;
650
651 /* see whether the blkcg association has changed */
652 blkcg_css = cgroup_get_e_css(memcg_css->cgroup,
653 &io_cgrp_subsys);
654 if (unlikely(wb->blkcg_css != blkcg_css ||
655 !wb_tryget(wb)))
656 wb = NULL;
657 css_put(blkcg_css);
658 }
659 rcu_read_unlock();
660 } while (!wb && !cgwb_create(bdi, memcg_css, gfp));
661
662 return wb;
663}
664
665static int cgwb_bdi_init(struct backing_dev_info *bdi)
666{
667 int ret;
668
669 INIT_RADIX_TREE(&bdi->cgwb_tree, GFP_ATOMIC);
670 bdi->cgwb_congested_tree = RB_ROOT;
671 atomic_set(&bdi->usage_cnt, 1);
672
673 ret = wb_init(&bdi->wb, bdi, 1, GFP_KERNEL);
674 if (!ret) {
675 bdi->wb.memcg_css = &root_mem_cgroup->css;
676 bdi->wb.blkcg_css = blkcg_root_css;
677 }
678 return ret;
679}
680
681static void cgwb_bdi_destroy(struct backing_dev_info *bdi)
682{
683 struct radix_tree_iter iter;
684 struct rb_node *rbn;
685 void **slot;
686
687 WARN_ON(test_bit(WB_registered, &bdi->wb.state));
688
689 spin_lock_irq(&cgwb_lock);
690
691 radix_tree_for_each_slot(slot, &bdi->cgwb_tree, &iter, 0)
692 cgwb_kill(*slot);
693
694 while ((rbn = rb_first(&bdi->cgwb_congested_tree))) {
695 struct bdi_writeback_congested *congested =
696 rb_entry(rbn, struct bdi_writeback_congested, rb_node);
697
698 rb_erase(rbn, &bdi->cgwb_congested_tree);
699 congested->bdi = NULL; /* mark @congested unlinked */
700 }
701
702 spin_unlock_irq(&cgwb_lock);
703
704 /*
705 * All cgwb's and their congested states must be shutdown and
706 * released before returning. Drain the usage counter to wait for
707 * all cgwb's and cgwb_congested's ever created on @bdi.
708 */
709 atomic_dec(&bdi->usage_cnt);
710 wait_event(cgwb_release_wait, !atomic_read(&bdi->usage_cnt));
711}
712
713/**
714 * wb_memcg_offline - kill all wb's associated with a memcg being offlined
715 * @memcg: memcg being offlined
716 *
717 * Also prevents creation of any new wb's associated with @memcg.
718 */
719void wb_memcg_offline(struct mem_cgroup *memcg)
720{
721 LIST_HEAD(to_destroy);
722 struct list_head *memcg_cgwb_list = mem_cgroup_cgwb_list(memcg);
723 struct bdi_writeback *wb, *next;
724
725 spin_lock_irq(&cgwb_lock);
726 list_for_each_entry_safe(wb, next, memcg_cgwb_list, memcg_node)
727 cgwb_kill(wb);
728 memcg_cgwb_list->next = NULL; /* prevent new wb's */
729 spin_unlock_irq(&cgwb_lock);
730}
731
732/**
733 * wb_blkcg_offline - kill all wb's associated with a blkcg being offlined
734 * @blkcg: blkcg being offlined
735 *
736 * Also prevents creation of any new wb's associated with @blkcg.
737 */
738void wb_blkcg_offline(struct blkcg *blkcg)
739{
740 LIST_HEAD(to_destroy);
741 struct bdi_writeback *wb, *next;
742
743 spin_lock_irq(&cgwb_lock);
744 list_for_each_entry_safe(wb, next, &blkcg->cgwb_list, blkcg_node)
745 cgwb_kill(wb);
746 blkcg->cgwb_list.next = NULL; /* prevent new wb's */
747 spin_unlock_irq(&cgwb_lock);
748}
749
750#else /* CONFIG_CGROUP_WRITEBACK */
751
752static int cgwb_bdi_init(struct backing_dev_info *bdi)
753{
754 int err;
755
756 bdi->wb_congested = kzalloc(sizeof(*bdi->wb_congested), GFP_KERNEL);
757 if (!bdi->wb_congested)
758 return -ENOMEM;
759
760 err = wb_init(&bdi->wb, bdi, 1, GFP_KERNEL);
761 if (err) {
762 kfree(bdi->wb_congested);
763 return err;
764 }
765 return 0;
766}
767
768static void cgwb_bdi_destroy(struct backing_dev_info *bdi) { }
769
770#endif /* CONFIG_CGROUP_WRITEBACK */
771
772int bdi_init(struct backing_dev_info *bdi)
773{
774 int ret;
775
776 bdi->dev = NULL;
777
778 bdi->min_ratio = 0;
779 bdi->max_ratio = 100;
780 bdi->max_prop_frac = FPROP_FRAC_BASE;
781 INIT_LIST_HEAD(&bdi->bdi_list);
782 INIT_LIST_HEAD(&bdi->wb_list);
783 init_waitqueue_head(&bdi->wb_waitq);
784
785 ret = cgwb_bdi_init(bdi);
786
787 list_add_tail_rcu(&bdi->wb.bdi_node, &bdi->wb_list);
788
789 return ret;
790}
791EXPORT_SYMBOL(bdi_init);
792
793int bdi_register(struct backing_dev_info *bdi, struct device *parent,
794 const char *fmt, ...)
795{
796 va_list args;
797 struct device *dev;
798
799 if (bdi->dev) /* The driver needs to use separate queues per device */
800 return 0;
801
802 va_start(args, fmt);
803 dev = device_create_vargs(bdi_class, parent, MKDEV(0, 0), bdi, fmt, args);
804 va_end(args);
805 if (IS_ERR(dev))
806 return PTR_ERR(dev);
807
808 bdi->dev = dev;
809
810 bdi_debug_register(bdi, dev_name(dev));
811 set_bit(WB_registered, &bdi->wb.state);
812
813 spin_lock_bh(&bdi_lock);
814 list_add_tail_rcu(&bdi->bdi_list, &bdi_list);
815 spin_unlock_bh(&bdi_lock);
816
817 trace_writeback_bdi_register(bdi);
818 return 0;
819}
820EXPORT_SYMBOL(bdi_register);
821
822int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev)
823{
824 return bdi_register(bdi, NULL, "%u:%u", MAJOR(dev), MINOR(dev));
825}
826EXPORT_SYMBOL(bdi_register_dev);
827
828/*
829 * Remove bdi from bdi_list, and ensure that it is no longer visible
830 */
831static void bdi_remove_from_list(struct backing_dev_info *bdi)
832{
833 spin_lock_bh(&bdi_lock);
834 list_del_rcu(&bdi->bdi_list);
835 spin_unlock_bh(&bdi_lock);
836
837 synchronize_rcu_expedited();
838}
839
840void bdi_unregister(struct backing_dev_info *bdi)
841{
842 /* make sure nobody finds us on the bdi_list anymore */
843 bdi_remove_from_list(bdi);
844 wb_shutdown(&bdi->wb);
845 cgwb_bdi_destroy(bdi);
846
847 if (bdi->dev) {
848 bdi_debug_unregister(bdi);
849 device_unregister(bdi->dev);
850 bdi->dev = NULL;
851 }
852}
853
854void bdi_exit(struct backing_dev_info *bdi)
855{
856 WARN_ON_ONCE(bdi->dev);
857 wb_exit(&bdi->wb);
858}
859
860void bdi_destroy(struct backing_dev_info *bdi)
861{
862 bdi_unregister(bdi);
863 bdi_exit(bdi);
864}
865EXPORT_SYMBOL(bdi_destroy);
866
867/*
868 * For use from filesystems to quickly init and register a bdi associated
869 * with dirty writeback
870 */
871int bdi_setup_and_register(struct backing_dev_info *bdi, char *name)
872{
873 int err;
874
875 bdi->name = name;
876 bdi->capabilities = 0;
877 err = bdi_init(bdi);
878 if (err)
879 return err;
880
881 err = bdi_register(bdi, NULL, "%.28s-%ld", name,
882 atomic_long_inc_return(&bdi_seq));
883 if (err) {
884 bdi_destroy(bdi);
885 return err;
886 }
887
888 return 0;
889}
890EXPORT_SYMBOL(bdi_setup_and_register);
891
892static wait_queue_head_t congestion_wqh[2] = {
893 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]),
894 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1])
895 };
896static atomic_t nr_wb_congested[2];
897
898void clear_wb_congested(struct bdi_writeback_congested *congested, int sync)
899{
900 wait_queue_head_t *wqh = &congestion_wqh[sync];
901 enum wb_congested_state bit;
902
903 bit = sync ? WB_sync_congested : WB_async_congested;
904 if (test_and_clear_bit(bit, &congested->state))
905 atomic_dec(&nr_wb_congested[sync]);
906 smp_mb__after_atomic();
907 if (waitqueue_active(wqh))
908 wake_up(wqh);
909}
910EXPORT_SYMBOL(clear_wb_congested);
911
912void set_wb_congested(struct bdi_writeback_congested *congested, int sync)
913{
914 enum wb_congested_state bit;
915
916 bit = sync ? WB_sync_congested : WB_async_congested;
917 if (!test_and_set_bit(bit, &congested->state))
918 atomic_inc(&nr_wb_congested[sync]);
919}
920EXPORT_SYMBOL(set_wb_congested);
921
922/**
923 * congestion_wait - wait for a backing_dev to become uncongested
924 * @sync: SYNC or ASYNC IO
925 * @timeout: timeout in jiffies
926 *
927 * Waits for up to @timeout jiffies for a backing_dev (any backing_dev) to exit
928 * write congestion. If no backing_devs are congested then just wait for the
929 * next write to be completed.
930 */
931long congestion_wait(int sync, long timeout)
932{
933 long ret;
934 unsigned long start = jiffies;
935 DEFINE_WAIT(wait);
936 wait_queue_head_t *wqh = &congestion_wqh[sync];
937
938 prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
939 ret = io_schedule_timeout(timeout);
940 finish_wait(wqh, &wait);
941
942 trace_writeback_congestion_wait(jiffies_to_usecs(timeout),
943 jiffies_to_usecs(jiffies - start));
944
945 return ret;
946}
947EXPORT_SYMBOL(congestion_wait);
948
949/**
950 * wait_iff_congested - Conditionally wait for a backing_dev to become uncongested or a zone to complete writes
951 * @zone: A zone to check if it is heavily congested
952 * @sync: SYNC or ASYNC IO
953 * @timeout: timeout in jiffies
954 *
955 * In the event of a congested backing_dev (any backing_dev) and the given
956 * @zone has experienced recent congestion, this waits for up to @timeout
957 * jiffies for either a BDI to exit congestion of the given @sync queue
958 * or a write to complete.
959 *
960 * In the absence of zone congestion, a short sleep or a cond_resched is
961 * performed to yield the processor and to allow other subsystems to make
962 * a forward progress.
963 *
964 * The return value is 0 if the sleep is for the full timeout. Otherwise,
965 * it is the number of jiffies that were still remaining when the function
966 * returned. return_value == timeout implies the function did not sleep.
967 */
968long wait_iff_congested(struct zone *zone, int sync, long timeout)
969{
970 long ret;
971 unsigned long start = jiffies;
972 DEFINE_WAIT(wait);
973 wait_queue_head_t *wqh = &congestion_wqh[sync];
974
975 /*
976 * If there is no congestion, or heavy congestion is not being
977 * encountered in the current zone, yield if necessary instead
978 * of sleeping on the congestion queue
979 */
980 if (atomic_read(&nr_wb_congested[sync]) == 0 ||
981 !test_bit(ZONE_CONGESTED, &zone->flags)) {
982
983 /*
984 * Memory allocation/reclaim might be called from a WQ
985 * context and the current implementation of the WQ
986 * concurrency control doesn't recognize that a particular
987 * WQ is congested if the worker thread is looping without
988 * ever sleeping. Therefore we have to do a short sleep
989 * here rather than calling cond_resched().
990 */
991 if (current->flags & PF_WQ_WORKER)
992 schedule_timeout_uninterruptible(1);
993 else
994 cond_resched();
995
996 /* In case we scheduled, work out time remaining */
997 ret = timeout - (jiffies - start);
998 if (ret < 0)
999 ret = 0;
1000
1001 goto out;
1002 }
1003
1004 /* Sleep until uncongested or a write happens */
1005 prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
1006 ret = io_schedule_timeout(timeout);
1007 finish_wait(wqh, &wait);
1008
1009out:
1010 trace_writeback_wait_iff_congested(jiffies_to_usecs(timeout),
1011 jiffies_to_usecs(jiffies - start));
1012
1013 return ret;
1014}
1015EXPORT_SYMBOL(wait_iff_congested);
1016
1017int pdflush_proc_obsolete(struct ctl_table *table, int write,
1018 void __user *buffer, size_t *lenp, loff_t *ppos)
1019{
1020 char kbuf[] = "0\n";
1021
1022 if (*ppos || *lenp < sizeof(kbuf)) {
1023 *lenp = 0;
1024 return 0;
1025 }
1026
1027 if (copy_to_user(buffer, kbuf, sizeof(kbuf)))
1028 return -EFAULT;
1029 pr_warn_once("%s exported in /proc is scheduled for removal\n",
1030 table->procname);
1031
1032 *lenp = 2;
1033 *ppos += *lenp;
1034 return 2;
1035}