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
15struct backing_dev_info noop_backing_dev_info = {
16 .name = "noop",
17 .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK,
18};
19EXPORT_SYMBOL_GPL(noop_backing_dev_info);
20
21static struct class *bdi_class;
22
23
24
25
26
27DEFINE_SPINLOCK(bdi_lock);
28LIST_HEAD(bdi_list);
29
30
31struct workqueue_struct *bdi_wq;
32
33#ifdef CONFIG_DEBUG_FS
34#include <linux/debugfs.h>
35#include <linux/seq_file.h>
36
37static struct dentry *bdi_debug_root;
38
39static void bdi_debug_init(void)
40{
41 bdi_debug_root = debugfs_create_dir("bdi", NULL);
42}
43
44static int bdi_debug_stats_show(struct seq_file *m, void *v)
45{
46 struct backing_dev_info *bdi = m->private;
47 struct bdi_writeback *wb = &bdi->wb;
48 unsigned long background_thresh;
49 unsigned long dirty_thresh;
50 unsigned long wb_thresh;
51 unsigned long nr_dirty, nr_io, nr_more_io, nr_dirty_time;
52 struct inode *inode;
53
54 nr_dirty = nr_io = nr_more_io = nr_dirty_time = 0;
55 spin_lock(&wb->list_lock);
56 list_for_each_entry(inode, &wb->b_dirty, i_io_list)
57 nr_dirty++;
58 list_for_each_entry(inode, &wb->b_io, i_io_list)
59 nr_io++;
60 list_for_each_entry(inode, &wb->b_more_io, i_io_list)
61 nr_more_io++;
62 list_for_each_entry(inode, &wb->b_dirty_time, i_io_list)
63 if (inode->i_state & I_DIRTY_TIME)
64 nr_dirty_time++;
65 spin_unlock(&wb->list_lock);
66
67 global_dirty_limits(&background_thresh, &dirty_thresh);
68 wb_thresh = wb_calc_thresh(wb, dirty_thresh);
69
70#define K(x) ((x) << (PAGE_SHIFT - 10))
71 seq_printf(m,
72 "BdiWriteback: %10lu kB\n"
73 "BdiReclaimable: %10lu kB\n"
74 "BdiDirtyThresh: %10lu kB\n"
75 "DirtyThresh: %10lu kB\n"
76 "BackgroundThresh: %10lu kB\n"
77 "BdiDirtied: %10lu kB\n"
78 "BdiWritten: %10lu kB\n"
79 "BdiWriteBandwidth: %10lu kBps\n"
80 "b_dirty: %10lu\n"
81 "b_io: %10lu\n"
82 "b_more_io: %10lu\n"
83 "b_dirty_time: %10lu\n"
84 "bdi_list: %10u\n"
85 "state: %10lx\n",
86 (unsigned long) K(wb_stat(wb, WB_WRITEBACK)),
87 (unsigned long) K(wb_stat(wb, WB_RECLAIMABLE)),
88 K(wb_thresh),
89 K(dirty_thresh),
90 K(background_thresh),
91 (unsigned long) K(wb_stat(wb, WB_DIRTIED)),
92 (unsigned long) K(wb_stat(wb, WB_WRITTEN)),
93 (unsigned long) K(wb->write_bandwidth),
94 nr_dirty,
95 nr_io,
96 nr_more_io,
97 nr_dirty_time,
98 !list_empty(&bdi->bdi_list), bdi->wb.state);
99#undef K
100
101 return 0;
102}
103DEFINE_SHOW_ATTRIBUTE(bdi_debug_stats);
104
105static int bdi_debug_register(struct backing_dev_info *bdi, const char *name)
106{
107 if (!bdi_debug_root)
108 return -ENOMEM;
109
110 bdi->debug_dir = debugfs_create_dir(name, bdi_debug_root);
111 if (!bdi->debug_dir)
112 return -ENOMEM;
113
114 bdi->debug_stats = debugfs_create_file("stats", 0444, bdi->debug_dir,
115 bdi, &bdi_debug_stats_fops);
116 if (!bdi->debug_stats) {
117 debugfs_remove(bdi->debug_dir);
118 bdi->debug_dir = NULL;
119 return -ENOMEM;
120 }
121
122 return 0;
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 int bdi_debug_register(struct backing_dev_info *bdi,
135 const char *name)
136{
137 return 0;
138}
139static inline void bdi_debug_unregister(struct backing_dev_info *bdi)
140{
141}
142#endif
143
144static ssize_t read_ahead_kb_store(struct device *dev,
145 struct device_attribute *attr,
146 const char *buf, size_t count)
147{
148 struct backing_dev_info *bdi = dev_get_drvdata(dev);
149 unsigned long read_ahead_kb;
150 ssize_t ret;
151
152 ret = kstrtoul(buf, 10, &read_ahead_kb);
153 if (ret < 0)
154 return ret;
155
156 bdi->ra_pages = read_ahead_kb >> (PAGE_SHIFT - 10);
157
158 return count;
159}
160
161#define K(pages) ((pages) << (PAGE_SHIFT - 10))
162
163#define BDI_SHOW(name, expr) \
164static ssize_t name##_show(struct device *dev, \
165 struct device_attribute *attr, char *page) \
166{ \
167 struct backing_dev_info *bdi = dev_get_drvdata(dev); \
168 \
169 return snprintf(page, PAGE_SIZE-1, "%lld\n", (long long)expr); \
170} \
171static DEVICE_ATTR_RW(name);
172
173BDI_SHOW(read_ahead_kb, K(bdi->ra_pages))
174
175static ssize_t min_ratio_store(struct device *dev,
176 struct device_attribute *attr, const char *buf, size_t count)
177{
178 struct backing_dev_info *bdi = dev_get_drvdata(dev);
179 unsigned int ratio;
180 ssize_t ret;
181
182 ret = kstrtouint(buf, 10, &ratio);
183 if (ret < 0)
184 return ret;
185
186 ret = bdi_set_min_ratio(bdi, ratio);
187 if (!ret)
188 ret = count;
189
190 return ret;
191}
192BDI_SHOW(min_ratio, bdi->min_ratio)
193
194static ssize_t max_ratio_store(struct device *dev,
195 struct device_attribute *attr, const char *buf, size_t count)
196{
197 struct backing_dev_info *bdi = dev_get_drvdata(dev);
198 unsigned int ratio;
199 ssize_t ret;
200
201 ret = kstrtouint(buf, 10, &ratio);
202 if (ret < 0)
203 return ret;
204
205 ret = bdi_set_max_ratio(bdi, ratio);
206 if (!ret)
207 ret = count;
208
209 return ret;
210}
211BDI_SHOW(max_ratio, bdi->max_ratio)
212
213static ssize_t stable_pages_required_show(struct device *dev,
214 struct device_attribute *attr,
215 char *page)
216{
217 struct backing_dev_info *bdi = dev_get_drvdata(dev);
218
219 return snprintf(page, PAGE_SIZE-1, "%d\n",
220 bdi_cap_stable_pages_required(bdi) ? 1 : 0);
221}
222static DEVICE_ATTR_RO(stable_pages_required);
223
224static struct attribute *bdi_dev_attrs[] = {
225 &dev_attr_read_ahead_kb.attr,
226 &dev_attr_min_ratio.attr,
227 &dev_attr_max_ratio.attr,
228 &dev_attr_stable_pages_required.attr,
229 NULL,
230};
231ATTRIBUTE_GROUPS(bdi_dev);
232
233static __init int bdi_class_init(void)
234{
235 bdi_class = class_create(THIS_MODULE, "bdi");
236 if (IS_ERR(bdi_class))
237 return PTR_ERR(bdi_class);
238
239 bdi_class->dev_groups = bdi_dev_groups;
240 bdi_debug_init();
241
242 return 0;
243}
244postcore_initcall(bdi_class_init);
245
246static int bdi_init(struct backing_dev_info *bdi);
247
248static int __init default_bdi_init(void)
249{
250 int err;
251
252 bdi_wq = alloc_workqueue("writeback", WQ_MEM_RECLAIM | WQ_FREEZABLE |
253 WQ_UNBOUND | WQ_SYSFS, 0);
254 if (!bdi_wq)
255 return -ENOMEM;
256
257 err = bdi_init(&noop_backing_dev_info);
258
259 return err;
260}
261subsys_initcall(default_bdi_init);
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277void wb_wakeup_delayed(struct bdi_writeback *wb)
278{
279 unsigned long timeout;
280
281 timeout = msecs_to_jiffies(dirty_writeback_interval * 10);
282 spin_lock_bh(&wb->work_lock);
283 if (test_bit(WB_registered, &wb->state))
284 queue_delayed_work(bdi_wq, &wb->dwork, timeout);
285 spin_unlock_bh(&wb->work_lock);
286}
287
288
289
290
291#define INIT_BW (100 << (20 - PAGE_SHIFT))
292
293static int wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi,
294 int blkcg_id, gfp_t gfp)
295{
296 int i, err;
297
298 memset(wb, 0, sizeof(*wb));
299
300 if (wb != &bdi->wb)
301 bdi_get(bdi);
302 wb->bdi = bdi;
303 wb->last_old_flush = jiffies;
304 INIT_LIST_HEAD(&wb->b_dirty);
305 INIT_LIST_HEAD(&wb->b_io);
306 INIT_LIST_HEAD(&wb->b_more_io);
307 INIT_LIST_HEAD(&wb->b_dirty_time);
308 spin_lock_init(&wb->list_lock);
309
310 wb->bw_time_stamp = jiffies;
311 wb->balanced_dirty_ratelimit = INIT_BW;
312 wb->dirty_ratelimit = INIT_BW;
313 wb->write_bandwidth = INIT_BW;
314 wb->avg_write_bandwidth = INIT_BW;
315
316 spin_lock_init(&wb->work_lock);
317 INIT_LIST_HEAD(&wb->work_list);
318 INIT_DELAYED_WORK(&wb->dwork, wb_workfn);
319 wb->dirty_sleep = jiffies;
320
321 wb->congested = wb_congested_get_create(bdi, blkcg_id, gfp);
322 if (!wb->congested) {
323 err = -ENOMEM;
324 goto out_put_bdi;
325 }
326
327 err = fprop_local_init_percpu(&wb->completions, gfp);
328 if (err)
329 goto out_put_cong;
330
331 for (i = 0; i < NR_WB_STAT_ITEMS; i++) {
332 err = percpu_counter_init(&wb->stat[i], 0, gfp);
333 if (err)
334 goto out_destroy_stat;
335 }
336
337 return 0;
338
339out_destroy_stat:
340 while (i--)
341 percpu_counter_destroy(&wb->stat[i]);
342 fprop_local_destroy_percpu(&wb->completions);
343out_put_cong:
344 wb_congested_put(wb->congested);
345out_put_bdi:
346 if (wb != &bdi->wb)
347 bdi_put(bdi);
348 return err;
349}
350
351static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb);
352
353
354
355
356static void wb_shutdown(struct bdi_writeback *wb)
357{
358
359 spin_lock_bh(&wb->work_lock);
360 if (!test_and_clear_bit(WB_registered, &wb->state)) {
361 spin_unlock_bh(&wb->work_lock);
362
363
364
365
366
367 wait_on_bit(&wb->state, WB_shutting_down, TASK_UNINTERRUPTIBLE);
368 return;
369 }
370 set_bit(WB_shutting_down, &wb->state);
371 spin_unlock_bh(&wb->work_lock);
372
373 cgwb_remove_from_bdi_list(wb);
374
375
376
377
378
379 mod_delayed_work(bdi_wq, &wb->dwork, 0);
380 flush_delayed_work(&wb->dwork);
381 WARN_ON(!list_empty(&wb->work_list));
382
383
384
385
386 smp_wmb();
387 clear_and_wake_up_bit(WB_shutting_down, &wb->state);
388}
389
390static void wb_exit(struct bdi_writeback *wb)
391{
392 int i;
393
394 WARN_ON(delayed_work_pending(&wb->dwork));
395
396 for (i = 0; i < NR_WB_STAT_ITEMS; i++)
397 percpu_counter_destroy(&wb->stat[i]);
398
399 fprop_local_destroy_percpu(&wb->completions);
400 wb_congested_put(wb->congested);
401 if (wb != &wb->bdi->wb)
402 bdi_put(wb->bdi);
403}
404
405#ifdef CONFIG_CGROUP_WRITEBACK
406
407#include <linux/memcontrol.h>
408
409
410
411
412
413
414static DEFINE_SPINLOCK(cgwb_lock);
415
416
417
418
419
420
421
422
423
424
425
426struct bdi_writeback_congested *
427wb_congested_get_create(struct backing_dev_info *bdi, int blkcg_id, gfp_t gfp)
428{
429 struct bdi_writeback_congested *new_congested = NULL, *congested;
430 struct rb_node **node, *parent;
431 unsigned long flags;
432retry:
433 spin_lock_irqsave(&cgwb_lock, flags);
434
435 node = &bdi->cgwb_congested_tree.rb_node;
436 parent = NULL;
437
438 while (*node != NULL) {
439 parent = *node;
440 congested = rb_entry(parent, struct bdi_writeback_congested,
441 rb_node);
442 if (congested->blkcg_id < blkcg_id)
443 node = &parent->rb_left;
444 else if (congested->blkcg_id > blkcg_id)
445 node = &parent->rb_right;
446 else
447 goto found;
448 }
449
450 if (new_congested) {
451
452 congested = new_congested;
453 new_congested = NULL;
454 rb_link_node(&congested->rb_node, parent, node);
455 rb_insert_color(&congested->rb_node, &bdi->cgwb_congested_tree);
456 goto found;
457 }
458
459 spin_unlock_irqrestore(&cgwb_lock, flags);
460
461
462 new_congested = kzalloc(sizeof(*new_congested), gfp);
463 if (!new_congested)
464 return NULL;
465
466 atomic_set(&new_congested->refcnt, 0);
467 new_congested->__bdi = bdi;
468 new_congested->blkcg_id = blkcg_id;
469 goto retry;
470
471found:
472 atomic_inc(&congested->refcnt);
473 spin_unlock_irqrestore(&cgwb_lock, flags);
474 kfree(new_congested);
475 return congested;
476}
477
478
479
480
481
482
483
484void wb_congested_put(struct bdi_writeback_congested *congested)
485{
486 unsigned long flags;
487
488 local_irq_save(flags);
489 if (!atomic_dec_and_lock(&congested->refcnt, &cgwb_lock)) {
490 local_irq_restore(flags);
491 return;
492 }
493
494
495 if (congested->__bdi) {
496 rb_erase(&congested->rb_node,
497 &congested->__bdi->cgwb_congested_tree);
498 congested->__bdi = NULL;
499 }
500
501 spin_unlock_irqrestore(&cgwb_lock, flags);
502 kfree(congested);
503}
504
505static void cgwb_release_workfn(struct work_struct *work)
506{
507 struct bdi_writeback *wb = container_of(work, struct bdi_writeback,
508 release_work);
509
510 wb_shutdown(wb);
511
512 css_put(wb->memcg_css);
513 css_put(wb->blkcg_css);
514
515 fprop_local_destroy_percpu(&wb->memcg_completions);
516 percpu_ref_exit(&wb->refcnt);
517 wb_exit(wb);
518 kfree_rcu(wb, rcu);
519}
520
521static void cgwb_release(struct percpu_ref *refcnt)
522{
523 struct bdi_writeback *wb = container_of(refcnt, struct bdi_writeback,
524 refcnt);
525 schedule_work(&wb->release_work);
526}
527
528static void cgwb_kill(struct bdi_writeback *wb)
529{
530 lockdep_assert_held(&cgwb_lock);
531
532 WARN_ON(!radix_tree_delete(&wb->bdi->cgwb_tree, wb->memcg_css->id));
533 list_del(&wb->memcg_node);
534 list_del(&wb->blkcg_node);
535 percpu_ref_kill(&wb->refcnt);
536}
537
538static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb)
539{
540 spin_lock_irq(&cgwb_lock);
541 list_del_rcu(&wb->bdi_node);
542 spin_unlock_irq(&cgwb_lock);
543}
544
545static int cgwb_create(struct backing_dev_info *bdi,
546 struct cgroup_subsys_state *memcg_css, gfp_t gfp)
547{
548 struct mem_cgroup *memcg;
549 struct cgroup_subsys_state *blkcg_css;
550 struct blkcg *blkcg;
551 struct list_head *memcg_cgwb_list, *blkcg_cgwb_list;
552 struct bdi_writeback *wb;
553 unsigned long flags;
554 int ret = 0;
555
556 memcg = mem_cgroup_from_css(memcg_css);
557 blkcg_css = cgroup_get_e_css(memcg_css->cgroup, &io_cgrp_subsys);
558 blkcg = css_to_blkcg(blkcg_css);
559 memcg_cgwb_list = mem_cgroup_cgwb_list(memcg);
560 blkcg_cgwb_list = &blkcg->cgwb_list;
561
562
563 spin_lock_irqsave(&cgwb_lock, flags);
564 wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id);
565 if (wb && wb->blkcg_css != blkcg_css) {
566 cgwb_kill(wb);
567 wb = NULL;
568 }
569 spin_unlock_irqrestore(&cgwb_lock, flags);
570 if (wb)
571 goto out_put;
572
573
574 wb = kmalloc(sizeof(*wb), gfp);
575 if (!wb) {
576 ret = -ENOMEM;
577 goto out_put;
578 }
579
580 ret = wb_init(wb, bdi, blkcg_css->id, gfp);
581 if (ret)
582 goto err_free;
583
584 ret = percpu_ref_init(&wb->refcnt, cgwb_release, 0, gfp);
585 if (ret)
586 goto err_wb_exit;
587
588 ret = fprop_local_init_percpu(&wb->memcg_completions, gfp);
589 if (ret)
590 goto err_ref_exit;
591
592 wb->memcg_css = memcg_css;
593 wb->blkcg_css = blkcg_css;
594 INIT_WORK(&wb->release_work, cgwb_release_workfn);
595 set_bit(WB_registered, &wb->state);
596
597
598
599
600
601
602
603 ret = -ENODEV;
604 spin_lock_irqsave(&cgwb_lock, flags);
605 if (test_bit(WB_registered, &bdi->wb.state) &&
606 blkcg_cgwb_list->next && memcg_cgwb_list->next) {
607
608 ret = radix_tree_insert(&bdi->cgwb_tree, memcg_css->id, wb);
609 if (!ret) {
610 list_add_tail_rcu(&wb->bdi_node, &bdi->wb_list);
611 list_add(&wb->memcg_node, memcg_cgwb_list);
612 list_add(&wb->blkcg_node, blkcg_cgwb_list);
613 css_get(memcg_css);
614 css_get(blkcg_css);
615 }
616 }
617 spin_unlock_irqrestore(&cgwb_lock, flags);
618 if (ret) {
619 if (ret == -EEXIST)
620 ret = 0;
621 goto err_fprop_exit;
622 }
623 goto out_put;
624
625err_fprop_exit:
626 fprop_local_destroy_percpu(&wb->memcg_completions);
627err_ref_exit:
628 percpu_ref_exit(&wb->refcnt);
629err_wb_exit:
630 wb_exit(wb);
631err_free:
632 kfree(wb);
633out_put:
634 css_put(blkcg_css);
635 return ret;
636}
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi,
663 struct cgroup_subsys_state *memcg_css,
664 gfp_t gfp)
665{
666 struct bdi_writeback *wb;
667
668 might_sleep_if(gfpflags_allow_blocking(gfp));
669
670 if (!memcg_css->parent)
671 return &bdi->wb;
672
673 do {
674 rcu_read_lock();
675 wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id);
676 if (wb) {
677 struct cgroup_subsys_state *blkcg_css;
678
679
680 blkcg_css = cgroup_get_e_css(memcg_css->cgroup,
681 &io_cgrp_subsys);
682 if (unlikely(wb->blkcg_css != blkcg_css ||
683 !wb_tryget(wb)))
684 wb = NULL;
685 css_put(blkcg_css);
686 }
687 rcu_read_unlock();
688 } while (!wb && !cgwb_create(bdi, memcg_css, gfp));
689
690 return wb;
691}
692
693static int cgwb_bdi_init(struct backing_dev_info *bdi)
694{
695 int ret;
696
697 INIT_RADIX_TREE(&bdi->cgwb_tree, GFP_ATOMIC);
698 bdi->cgwb_congested_tree = RB_ROOT;
699
700 ret = wb_init(&bdi->wb, bdi, 1, GFP_KERNEL);
701 if (!ret) {
702 bdi->wb.memcg_css = &root_mem_cgroup->css;
703 bdi->wb.blkcg_css = blkcg_root_css;
704 }
705 return ret;
706}
707
708static void cgwb_bdi_unregister(struct backing_dev_info *bdi)
709{
710 struct radix_tree_iter iter;
711 void **slot;
712 struct bdi_writeback *wb;
713
714 WARN_ON(test_bit(WB_registered, &bdi->wb.state));
715
716 spin_lock_irq(&cgwb_lock);
717 radix_tree_for_each_slot(slot, &bdi->cgwb_tree, &iter, 0)
718 cgwb_kill(*slot);
719
720 while (!list_empty(&bdi->wb_list)) {
721 wb = list_first_entry(&bdi->wb_list, struct bdi_writeback,
722 bdi_node);
723 spin_unlock_irq(&cgwb_lock);
724 wb_shutdown(wb);
725 spin_lock_irq(&cgwb_lock);
726 }
727 spin_unlock_irq(&cgwb_lock);
728}
729
730
731
732
733
734
735
736void wb_memcg_offline(struct mem_cgroup *memcg)
737{
738 struct list_head *memcg_cgwb_list = mem_cgroup_cgwb_list(memcg);
739 struct bdi_writeback *wb, *next;
740
741 spin_lock_irq(&cgwb_lock);
742 list_for_each_entry_safe(wb, next, memcg_cgwb_list, memcg_node)
743 cgwb_kill(wb);
744 memcg_cgwb_list->next = NULL;
745 spin_unlock_irq(&cgwb_lock);
746}
747
748
749
750
751
752
753
754void wb_blkcg_offline(struct blkcg *blkcg)
755{
756 struct bdi_writeback *wb, *next;
757
758 spin_lock_irq(&cgwb_lock);
759 list_for_each_entry_safe(wb, next, &blkcg->cgwb_list, blkcg_node)
760 cgwb_kill(wb);
761 blkcg->cgwb_list.next = NULL;
762 spin_unlock_irq(&cgwb_lock);
763}
764
765static void cgwb_bdi_exit(struct backing_dev_info *bdi)
766{
767 struct rb_node *rbn;
768
769 spin_lock_irq(&cgwb_lock);
770 while ((rbn = rb_first(&bdi->cgwb_congested_tree))) {
771 struct bdi_writeback_congested *congested =
772 rb_entry(rbn, struct bdi_writeback_congested, rb_node);
773
774 rb_erase(rbn, &bdi->cgwb_congested_tree);
775 congested->__bdi = NULL;
776 }
777 spin_unlock_irq(&cgwb_lock);
778}
779
780static void cgwb_bdi_register(struct backing_dev_info *bdi)
781{
782 spin_lock_irq(&cgwb_lock);
783 list_add_tail_rcu(&bdi->wb.bdi_node, &bdi->wb_list);
784 spin_unlock_irq(&cgwb_lock);
785}
786
787#else
788
789static int cgwb_bdi_init(struct backing_dev_info *bdi)
790{
791 int err;
792
793 bdi->wb_congested = kzalloc(sizeof(*bdi->wb_congested), GFP_KERNEL);
794 if (!bdi->wb_congested)
795 return -ENOMEM;
796
797 atomic_set(&bdi->wb_congested->refcnt, 1);
798
799 err = wb_init(&bdi->wb, bdi, 1, GFP_KERNEL);
800 if (err) {
801 wb_congested_put(bdi->wb_congested);
802 return err;
803 }
804 return 0;
805}
806
807static void cgwb_bdi_unregister(struct backing_dev_info *bdi) { }
808
809static void cgwb_bdi_exit(struct backing_dev_info *bdi)
810{
811 wb_congested_put(bdi->wb_congested);
812}
813
814static void cgwb_bdi_register(struct backing_dev_info *bdi)
815{
816 list_add_tail_rcu(&bdi->wb.bdi_node, &bdi->wb_list);
817}
818
819static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb)
820{
821 list_del_rcu(&wb->bdi_node);
822}
823
824#endif
825
826static int bdi_init(struct backing_dev_info *bdi)
827{
828 int ret;
829
830 bdi->dev = NULL;
831
832 kref_init(&bdi->refcnt);
833 bdi->min_ratio = 0;
834 bdi->max_ratio = 100;
835 bdi->max_prop_frac = FPROP_FRAC_BASE;
836 INIT_LIST_HEAD(&bdi->bdi_list);
837 INIT_LIST_HEAD(&bdi->wb_list);
838 init_waitqueue_head(&bdi->wb_waitq);
839
840 ret = cgwb_bdi_init(bdi);
841
842 return ret;
843}
844
845struct backing_dev_info *bdi_alloc_node(gfp_t gfp_mask, int node_id)
846{
847 struct backing_dev_info *bdi;
848
849 bdi = kmalloc_node(sizeof(struct backing_dev_info),
850 gfp_mask | __GFP_ZERO, node_id);
851 if (!bdi)
852 return NULL;
853
854 if (bdi_init(bdi)) {
855 kfree(bdi);
856 return NULL;
857 }
858 return bdi;
859}
860EXPORT_SYMBOL(bdi_alloc_node);
861
862int bdi_register_va(struct backing_dev_info *bdi, const char *fmt, va_list args)
863{
864 struct device *dev;
865
866 if (bdi->dev)
867 return 0;
868
869 dev = device_create_vargs(bdi_class, NULL, MKDEV(0, 0), bdi, fmt, args);
870 if (IS_ERR(dev))
871 return PTR_ERR(dev);
872
873 cgwb_bdi_register(bdi);
874 bdi->dev = dev;
875
876 bdi_debug_register(bdi, dev_name(dev));
877 set_bit(WB_registered, &bdi->wb.state);
878
879 spin_lock_bh(&bdi_lock);
880 list_add_tail_rcu(&bdi->bdi_list, &bdi_list);
881 spin_unlock_bh(&bdi_lock);
882
883 trace_writeback_bdi_register(bdi);
884 return 0;
885}
886EXPORT_SYMBOL(bdi_register_va);
887
888int bdi_register(struct backing_dev_info *bdi, const char *fmt, ...)
889{
890 va_list args;
891 int ret;
892
893 va_start(args, fmt);
894 ret = bdi_register_va(bdi, fmt, args);
895 va_end(args);
896 return ret;
897}
898EXPORT_SYMBOL(bdi_register);
899
900int bdi_register_owner(struct backing_dev_info *bdi, struct device *owner)
901{
902 int rc;
903
904 rc = bdi_register(bdi, "%u:%u", MAJOR(owner->devt), MINOR(owner->devt));
905 if (rc)
906 return rc;
907
908 WARN_ON(bdi->owner);
909 bdi->owner = owner;
910 get_device(owner);
911 return 0;
912}
913EXPORT_SYMBOL(bdi_register_owner);
914
915
916
917
918static void bdi_remove_from_list(struct backing_dev_info *bdi)
919{
920 spin_lock_bh(&bdi_lock);
921 list_del_rcu(&bdi->bdi_list);
922 spin_unlock_bh(&bdi_lock);
923
924 synchronize_rcu_expedited();
925}
926
927void bdi_unregister(struct backing_dev_info *bdi)
928{
929
930 bdi_remove_from_list(bdi);
931 wb_shutdown(&bdi->wb);
932 cgwb_bdi_unregister(bdi);
933
934 if (bdi->dev) {
935 bdi_debug_unregister(bdi);
936 device_unregister(bdi->dev);
937 bdi->dev = NULL;
938 }
939
940 if (bdi->owner) {
941 put_device(bdi->owner);
942 bdi->owner = NULL;
943 }
944}
945
946static void release_bdi(struct kref *ref)
947{
948 struct backing_dev_info *bdi =
949 container_of(ref, struct backing_dev_info, refcnt);
950
951 if (test_bit(WB_registered, &bdi->wb.state))
952 bdi_unregister(bdi);
953 WARN_ON_ONCE(bdi->dev);
954 wb_exit(&bdi->wb);
955 cgwb_bdi_exit(bdi);
956 kfree(bdi);
957}
958
959void bdi_put(struct backing_dev_info *bdi)
960{
961 kref_put(&bdi->refcnt, release_bdi);
962}
963EXPORT_SYMBOL(bdi_put);
964
965static wait_queue_head_t congestion_wqh[2] = {
966 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]),
967 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1])
968 };
969static atomic_t nr_wb_congested[2];
970
971void clear_wb_congested(struct bdi_writeback_congested *congested, int sync)
972{
973 wait_queue_head_t *wqh = &congestion_wqh[sync];
974 enum wb_congested_state bit;
975
976 bit = sync ? WB_sync_congested : WB_async_congested;
977 if (test_and_clear_bit(bit, &congested->state))
978 atomic_dec(&nr_wb_congested[sync]);
979 smp_mb__after_atomic();
980 if (waitqueue_active(wqh))
981 wake_up(wqh);
982}
983EXPORT_SYMBOL(clear_wb_congested);
984
985void set_wb_congested(struct bdi_writeback_congested *congested, int sync)
986{
987 enum wb_congested_state bit;
988
989 bit = sync ? WB_sync_congested : WB_async_congested;
990 if (!test_and_set_bit(bit, &congested->state))
991 atomic_inc(&nr_wb_congested[sync]);
992}
993EXPORT_SYMBOL(set_wb_congested);
994
995
996
997
998
999
1000
1001
1002
1003
1004long congestion_wait(int sync, long timeout)
1005{
1006 long ret;
1007 unsigned long start = jiffies;
1008 DEFINE_WAIT(wait);
1009 wait_queue_head_t *wqh = &congestion_wqh[sync];
1010
1011 prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
1012 ret = io_schedule_timeout(timeout);
1013 finish_wait(wqh, &wait);
1014
1015 trace_writeback_congestion_wait(jiffies_to_usecs(timeout),
1016 jiffies_to_usecs(jiffies - start));
1017
1018 return ret;
1019}
1020EXPORT_SYMBOL(congestion_wait);
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035long wait_iff_congested(int sync, long timeout)
1036{
1037 long ret;
1038 unsigned long start = jiffies;
1039 DEFINE_WAIT(wait);
1040 wait_queue_head_t *wqh = &congestion_wqh[sync];
1041
1042
1043
1044
1045
1046 if (atomic_read(&nr_wb_congested[sync]) == 0) {
1047 cond_resched();
1048
1049
1050 ret = timeout - (jiffies - start);
1051 if (ret < 0)
1052 ret = 0;
1053
1054 goto out;
1055 }
1056
1057
1058 prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
1059 ret = io_schedule_timeout(timeout);
1060 finish_wait(wqh, &wait);
1061
1062out:
1063 trace_writeback_wait_iff_congested(jiffies_to_usecs(timeout),
1064 jiffies_to_usecs(jiffies - start));
1065
1066 return ret;
1067}
1068EXPORT_SYMBOL(wait_iff_congested);
1069