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 * bdi_lock protects updates to bdi_list. bdi_list has RCU reader side
25 * locking.
26 */
27DEFINE_SPINLOCK(bdi_lock);
28LIST_HEAD(bdi_list);
29
30/* bdi_wq serves all asynchronous writeback tasks */
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 * This function is used when the first inode for this wb is marked dirty. It
265 * wakes-up the corresponding bdi thread which should then take care of the
266 * periodic background write-out of dirty inodes. Since the write-out would
267 * starts only 'dirty_writeback_interval' centisecs from now anyway, we just
268 * set up a timer which wakes the bdi thread up later.
269 *
270 * Note, we wouldn't bother setting up the timer, but this function is on the
271 * fast-path (used by '__mark_inode_dirty()'), so we save few context switches
272 * by delaying the wake-up.
273 *
274 * We have to be careful not to postpone flush work if it is scheduled for
275 * earlier. Thus we use queue_delayed_work().
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 * Initial write bandwidth: 100 MB/s
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 * Remove bdi from the global list and shutdown any threads we have running
355 */
356static void wb_shutdown(struct bdi_writeback *wb)
357{
358 /* Make sure nobody queues further work */
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 return;
363 }
364 spin_unlock_bh(&wb->work_lock);
365
366 cgwb_remove_from_bdi_list(wb);
367 /*
368 * Drain work list and shutdown the delayed_work. !WB_registered
369 * tells wb_workfn() that @wb is dying and its work_list needs to
370 * be drained no matter what.
371 */
372 mod_delayed_work(bdi_wq, &wb->dwork, 0);
373 flush_delayed_work(&wb->dwork);
374 WARN_ON(!list_empty(&wb->work_list));
375}
376
377static void wb_exit(struct bdi_writeback *wb)
378{
379 int i;
380
381 WARN_ON(delayed_work_pending(&wb->dwork));
382
383 for (i = 0; i < NR_WB_STAT_ITEMS; i++)
384 percpu_counter_destroy(&wb->stat[i]);
385
386 fprop_local_destroy_percpu(&wb->completions);
387 wb_congested_put(wb->congested);
388 if (wb != &wb->bdi->wb)
389 bdi_put(wb->bdi);
390}
391
392#ifdef CONFIG_CGROUP_WRITEBACK
393
394#include <linux/memcontrol.h>
395
396/*
397 * cgwb_lock protects bdi->cgwb_tree, bdi->cgwb_congested_tree,
398 * blkcg->cgwb_list, and memcg->cgwb_list. bdi->cgwb_tree is also RCU
399 * protected.
400 */
401static DEFINE_SPINLOCK(cgwb_lock);
402static struct workqueue_struct *cgwb_release_wq;
403
404/**
405 * wb_congested_get_create - get or create a wb_congested
406 * @bdi: associated bdi
407 * @blkcg_id: ID of the associated blkcg
408 * @gfp: allocation mask
409 *
410 * Look up the wb_congested for @blkcg_id on @bdi. If missing, create one.
411 * The returned wb_congested has its reference count incremented. Returns
412 * NULL on failure.
413 */
414struct bdi_writeback_congested *
415wb_congested_get_create(struct backing_dev_info *bdi, int blkcg_id, gfp_t gfp)
416{
417 struct bdi_writeback_congested *new_congested = NULL, *congested;
418 struct rb_node **node, *parent;
419 unsigned long flags;
420retry:
421 spin_lock_irqsave(&cgwb_lock, flags);
422
423 node = &bdi->cgwb_congested_tree.rb_node;
424 parent = NULL;
425
426 while (*node != NULL) {
427 parent = *node;
428 congested = rb_entry(parent, struct bdi_writeback_congested,
429 rb_node);
430 if (congested->blkcg_id < blkcg_id)
431 node = &parent->rb_left;
432 else if (congested->blkcg_id > blkcg_id)
433 node = &parent->rb_right;
434 else
435 goto found;
436 }
437
438 if (new_congested) {
439 /* !found and storage for new one already allocated, insert */
440 congested = new_congested;
441 rb_link_node(&congested->rb_node, parent, node);
442 rb_insert_color(&congested->rb_node, &bdi->cgwb_congested_tree);
443 spin_unlock_irqrestore(&cgwb_lock, flags);
444 return congested;
445 }
446
447 spin_unlock_irqrestore(&cgwb_lock, flags);
448
449 /* allocate storage for new one and retry */
450 new_congested = kzalloc(sizeof(*new_congested), gfp);
451 if (!new_congested)
452 return NULL;
453
454 refcount_set(&new_congested->refcnt, 1);
455 new_congested->__bdi = bdi;
456 new_congested->blkcg_id = blkcg_id;
457 goto retry;
458
459found:
460 refcount_inc(&congested->refcnt);
461 spin_unlock_irqrestore(&cgwb_lock, flags);
462 kfree(new_congested);
463 return congested;
464}
465
466/**
467 * wb_congested_put - put a wb_congested
468 * @congested: wb_congested to put
469 *
470 * Put @congested and destroy it if the refcnt reaches zero.
471 */
472void wb_congested_put(struct bdi_writeback_congested *congested)
473{
474 unsigned long flags;
475
476 if (!refcount_dec_and_lock_irqsave(&congested->refcnt, &cgwb_lock, &flags))
477 return;
478
479 /* bdi might already have been destroyed leaving @congested unlinked */
480 if (congested->__bdi) {
481 rb_erase(&congested->rb_node,
482 &congested->__bdi->cgwb_congested_tree);
483 congested->__bdi = NULL;
484 }
485
486 spin_unlock_irqrestore(&cgwb_lock, flags);
487 kfree(congested);
488}
489
490static void cgwb_release_workfn(struct work_struct *work)
491{
492 struct bdi_writeback *wb = container_of(work, struct bdi_writeback,
493 release_work);
494 struct blkcg *blkcg = css_to_blkcg(wb->blkcg_css);
495
496 mutex_lock(&wb->bdi->cgwb_release_mutex);
497 wb_shutdown(wb);
498
499 css_put(wb->memcg_css);
500 css_put(wb->blkcg_css);
501 mutex_unlock(&wb->bdi->cgwb_release_mutex);
502
503 /* triggers blkg destruction if cgwb_refcnt becomes zero */
504 blkcg_cgwb_put(blkcg);
505
506 fprop_local_destroy_percpu(&wb->memcg_completions);
507 percpu_ref_exit(&wb->refcnt);
508 wb_exit(wb);
509 kfree_rcu(wb, rcu);
510}
511
512static void cgwb_release(struct percpu_ref *refcnt)
513{
514 struct bdi_writeback *wb = container_of(refcnt, struct bdi_writeback,
515 refcnt);
516 queue_work(cgwb_release_wq, &wb->release_work);
517}
518
519static void cgwb_kill(struct bdi_writeback *wb)
520{
521 lockdep_assert_held(&cgwb_lock);
522
523 WARN_ON(!radix_tree_delete(&wb->bdi->cgwb_tree, wb->memcg_css->id));
524 list_del(&wb->memcg_node);
525 list_del(&wb->blkcg_node);
526 percpu_ref_kill(&wb->refcnt);
527}
528
529static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb)
530{
531 spin_lock_irq(&cgwb_lock);
532 list_del_rcu(&wb->bdi_node);
533 spin_unlock_irq(&cgwb_lock);
534}
535
536static int cgwb_create(struct backing_dev_info *bdi,
537 struct cgroup_subsys_state *memcg_css, gfp_t gfp)
538{
539 struct mem_cgroup *memcg;
540 struct cgroup_subsys_state *blkcg_css;
541 struct blkcg *blkcg;
542 struct list_head *memcg_cgwb_list, *blkcg_cgwb_list;
543 struct bdi_writeback *wb;
544 unsigned long flags;
545 int ret = 0;
546
547 memcg = mem_cgroup_from_css(memcg_css);
548 blkcg_css = cgroup_get_e_css(memcg_css->cgroup, &io_cgrp_subsys);
549 blkcg = css_to_blkcg(blkcg_css);
550 memcg_cgwb_list = &memcg->cgwb_list;
551 blkcg_cgwb_list = &blkcg->cgwb_list;
552
553 /* look up again under lock and discard on blkcg mismatch */
554 spin_lock_irqsave(&cgwb_lock, flags);
555 wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id);
556 if (wb && wb->blkcg_css != blkcg_css) {
557 cgwb_kill(wb);
558 wb = NULL;
559 }
560 spin_unlock_irqrestore(&cgwb_lock, flags);
561 if (wb)
562 goto out_put;
563
564 /* need to create a new one */
565 wb = kmalloc(sizeof(*wb), gfp);
566 if (!wb) {
567 ret = -ENOMEM;
568 goto out_put;
569 }
570
571 ret = wb_init(wb, bdi, blkcg_css->id, gfp);
572 if (ret)
573 goto err_free;
574
575 ret = percpu_ref_init(&wb->refcnt, cgwb_release, 0, gfp);
576 if (ret)
577 goto err_wb_exit;
578
579 ret = fprop_local_init_percpu(&wb->memcg_completions, gfp);
580 if (ret)
581 goto err_ref_exit;
582
583 wb->memcg_css = memcg_css;
584 wb->blkcg_css = blkcg_css;
585 INIT_WORK(&wb->release_work, cgwb_release_workfn);
586 set_bit(WB_registered, &wb->state);
587
588 /*
589 * The root wb determines the registered state of the whole bdi and
590 * memcg_cgwb_list and blkcg_cgwb_list's next pointers indicate
591 * whether they're still online. Don't link @wb if any is dead.
592 * See wb_memcg_offline() and wb_blkcg_offline().
593 */
594 ret = -ENODEV;
595 spin_lock_irqsave(&cgwb_lock, flags);
596 if (test_bit(WB_registered, &bdi->wb.state) &&
597 blkcg_cgwb_list->next && memcg_cgwb_list->next) {
598 /* we might have raced another instance of this function */
599 ret = radix_tree_insert(&bdi->cgwb_tree, memcg_css->id, wb);
600 if (!ret) {
601 list_add_tail_rcu(&wb->bdi_node, &bdi->wb_list);
602 list_add(&wb->memcg_node, memcg_cgwb_list);
603 list_add(&wb->blkcg_node, blkcg_cgwb_list);
604 blkcg_cgwb_get(blkcg);
605 css_get(memcg_css);
606 css_get(blkcg_css);
607 }
608 }
609 spin_unlock_irqrestore(&cgwb_lock, flags);
610 if (ret) {
611 if (ret == -EEXIST)
612 ret = 0;
613 goto err_fprop_exit;
614 }
615 goto out_put;
616
617err_fprop_exit:
618 fprop_local_destroy_percpu(&wb->memcg_completions);
619err_ref_exit:
620 percpu_ref_exit(&wb->refcnt);
621err_wb_exit:
622 wb_exit(wb);
623err_free:
624 kfree(wb);
625out_put:
626 css_put(blkcg_css);
627 return ret;
628}
629
630/**
631 * wb_get_create - get wb for a given memcg, create if necessary
632 * @bdi: target bdi
633 * @memcg_css: cgroup_subsys_state of the target memcg (must have positive ref)
634 * @gfp: allocation mask to use
635 *
636 * Try to get the wb for @memcg_css on @bdi. If it doesn't exist, try to
637 * create one. The returned wb has its refcount incremented.
638 *
639 * This function uses css_get() on @memcg_css and thus expects its refcnt
640 * to be positive on invocation. IOW, rcu_read_lock() protection on
641 * @memcg_css isn't enough. try_get it before calling this function.
642 *
643 * A wb is keyed by its associated memcg. As blkcg implicitly enables
644 * memcg on the default hierarchy, memcg association is guaranteed to be
645 * more specific (equal or descendant to the associated blkcg) and thus can
646 * identify both the memcg and blkcg associations.
647 *
648 * Because the blkcg associated with a memcg may change as blkcg is enabled
649 * and disabled closer to root in the hierarchy, each wb keeps track of
650 * both the memcg and blkcg associated with it and verifies the blkcg on
651 * each lookup. On mismatch, the existing wb is discarded and a new one is
652 * created.
653 */
654struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi,
655 struct cgroup_subsys_state *memcg_css,
656 gfp_t gfp)
657{
658 struct bdi_writeback *wb;
659
660 might_sleep_if(gfpflags_allow_blocking(gfp));
661
662 if (!memcg_css->parent)
663 return &bdi->wb;
664
665 do {
666 rcu_read_lock();
667 wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id);
668 if (wb) {
669 struct cgroup_subsys_state *blkcg_css;
670
671 /* see whether the blkcg association has changed */
672 blkcg_css = cgroup_get_e_css(memcg_css->cgroup,
673 &io_cgrp_subsys);
674 if (unlikely(wb->blkcg_css != blkcg_css ||
675 !wb_tryget(wb)))
676 wb = NULL;
677 css_put(blkcg_css);
678 }
679 rcu_read_unlock();
680 } while (!wb && !cgwb_create(bdi, memcg_css, gfp));
681
682 return wb;
683}
684
685static int cgwb_bdi_init(struct backing_dev_info *bdi)
686{
687 int ret;
688
689 INIT_RADIX_TREE(&bdi->cgwb_tree, GFP_ATOMIC);
690 bdi->cgwb_congested_tree = RB_ROOT;
691 mutex_init(&bdi->cgwb_release_mutex);
692 init_rwsem(&bdi->wb_switch_rwsem);
693
694 ret = wb_init(&bdi->wb, bdi, 1, GFP_KERNEL);
695 if (!ret) {
696 bdi->wb.memcg_css = &root_mem_cgroup->css;
697 bdi->wb.blkcg_css = blkcg_root_css;
698 }
699 return ret;
700}
701
702static void cgwb_bdi_unregister(struct backing_dev_info *bdi)
703{
704 struct radix_tree_iter iter;
705 void **slot;
706 struct bdi_writeback *wb;
707
708 WARN_ON(test_bit(WB_registered, &bdi->wb.state));
709
710 spin_lock_irq(&cgwb_lock);
711 radix_tree_for_each_slot(slot, &bdi->cgwb_tree, &iter, 0)
712 cgwb_kill(*slot);
713 spin_unlock_irq(&cgwb_lock);
714
715 mutex_lock(&bdi->cgwb_release_mutex);
716 spin_lock_irq(&cgwb_lock);
717 while (!list_empty(&bdi->wb_list)) {
718 wb = list_first_entry(&bdi->wb_list, struct bdi_writeback,
719 bdi_node);
720 spin_unlock_irq(&cgwb_lock);
721 wb_shutdown(wb);
722 spin_lock_irq(&cgwb_lock);
723 }
724 spin_unlock_irq(&cgwb_lock);
725 mutex_unlock(&bdi->cgwb_release_mutex);
726}
727
728/**
729 * wb_memcg_offline - kill all wb's associated with a memcg being offlined
730 * @memcg: memcg being offlined
731 *
732 * Also prevents creation of any new wb's associated with @memcg.
733 */
734void wb_memcg_offline(struct mem_cgroup *memcg)
735{
736 struct list_head *memcg_cgwb_list = &memcg->cgwb_list;
737 struct bdi_writeback *wb, *next;
738
739 spin_lock_irq(&cgwb_lock);
740 list_for_each_entry_safe(wb, next, memcg_cgwb_list, memcg_node)
741 cgwb_kill(wb);
742 memcg_cgwb_list->next = NULL; /* prevent new wb's */
743 spin_unlock_irq(&cgwb_lock);
744}
745
746/**
747 * wb_blkcg_offline - kill all wb's associated with a blkcg being offlined
748 * @blkcg: blkcg being offlined
749 *
750 * Also prevents creation of any new wb's associated with @blkcg.
751 */
752void wb_blkcg_offline(struct blkcg *blkcg)
753{
754 struct bdi_writeback *wb, *next;
755
756 spin_lock_irq(&cgwb_lock);
757 list_for_each_entry_safe(wb, next, &blkcg->cgwb_list, blkcg_node)
758 cgwb_kill(wb);
759 blkcg->cgwb_list.next = NULL; /* prevent new wb's */
760 spin_unlock_irq(&cgwb_lock);
761}
762
763static void cgwb_bdi_exit(struct backing_dev_info *bdi)
764{
765 struct rb_node *rbn;
766
767 spin_lock_irq(&cgwb_lock);
768 while ((rbn = rb_first(&bdi->cgwb_congested_tree))) {
769 struct bdi_writeback_congested *congested =
770 rb_entry(rbn, struct bdi_writeback_congested, rb_node);
771
772 rb_erase(rbn, &bdi->cgwb_congested_tree);
773 congested->__bdi = NULL; /* mark @congested unlinked */
774 }
775 spin_unlock_irq(&cgwb_lock);
776}
777
778static void cgwb_bdi_register(struct backing_dev_info *bdi)
779{
780 spin_lock_irq(&cgwb_lock);
781 list_add_tail_rcu(&bdi->wb.bdi_node, &bdi->wb_list);
782 spin_unlock_irq(&cgwb_lock);
783}
784
785static int __init cgwb_init(void)
786{
787 /*
788 * There can be many concurrent release work items overwhelming
789 * system_wq. Put them in a separate wq and limit concurrency.
790 * There's no point in executing many of these in parallel.
791 */
792 cgwb_release_wq = alloc_workqueue("cgwb_release", 0, 1);
793 if (!cgwb_release_wq)
794 return -ENOMEM;
795
796 return 0;
797}
798subsys_initcall(cgwb_init);
799
800#else /* CONFIG_CGROUP_WRITEBACK */
801
802static int cgwb_bdi_init(struct backing_dev_info *bdi)
803{
804 int err;
805
806 bdi->wb_congested = kzalloc(sizeof(*bdi->wb_congested), GFP_KERNEL);
807 if (!bdi->wb_congested)
808 return -ENOMEM;
809
810 refcount_set(&bdi->wb_congested->refcnt, 1);
811
812 err = wb_init(&bdi->wb, bdi, 1, GFP_KERNEL);
813 if (err) {
814 wb_congested_put(bdi->wb_congested);
815 return err;
816 }
817 return 0;
818}
819
820static void cgwb_bdi_unregister(struct backing_dev_info *bdi) { }
821
822static void cgwb_bdi_exit(struct backing_dev_info *bdi)
823{
824 wb_congested_put(bdi->wb_congested);
825}
826
827static void cgwb_bdi_register(struct backing_dev_info *bdi)
828{
829 list_add_tail_rcu(&bdi->wb.bdi_node, &bdi->wb_list);
830}
831
832static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb)
833{
834 list_del_rcu(&wb->bdi_node);
835}
836
837#endif /* CONFIG_CGROUP_WRITEBACK */
838
839static int bdi_init(struct backing_dev_info *bdi)
840{
841 int ret;
842
843 bdi->dev = NULL;
844
845 kref_init(&bdi->refcnt);
846 bdi->min_ratio = 0;
847 bdi->max_ratio = 100;
848 bdi->max_prop_frac = FPROP_FRAC_BASE;
849 INIT_LIST_HEAD(&bdi->bdi_list);
850 INIT_LIST_HEAD(&bdi->wb_list);
851 init_waitqueue_head(&bdi->wb_waitq);
852
853 ret = cgwb_bdi_init(bdi);
854
855 return ret;
856}
857
858struct backing_dev_info *bdi_alloc_node(gfp_t gfp_mask, int node_id)
859{
860 struct backing_dev_info *bdi;
861
862 bdi = kmalloc_node(sizeof(struct backing_dev_info),
863 gfp_mask | __GFP_ZERO, node_id);
864 if (!bdi)
865 return NULL;
866
867 if (bdi_init(bdi)) {
868 kfree(bdi);
869 return NULL;
870 }
871 return bdi;
872}
873EXPORT_SYMBOL(bdi_alloc_node);
874
875int bdi_register_va(struct backing_dev_info *bdi, const char *fmt, va_list args)
876{
877 struct device *dev;
878
879 if (bdi->dev) /* The driver needs to use separate queues per device */
880 return 0;
881
882 dev = device_create_vargs(bdi_class, NULL, MKDEV(0, 0), bdi, fmt, args);
883 if (IS_ERR(dev))
884 return PTR_ERR(dev);
885
886 cgwb_bdi_register(bdi);
887 bdi->dev = dev;
888
889 bdi_debug_register(bdi, dev_name(dev));
890 set_bit(WB_registered, &bdi->wb.state);
891
892 spin_lock_bh(&bdi_lock);
893 list_add_tail_rcu(&bdi->bdi_list, &bdi_list);
894 spin_unlock_bh(&bdi_lock);
895
896 trace_writeback_bdi_register(bdi);
897 return 0;
898}
899EXPORT_SYMBOL(bdi_register_va);
900
901int bdi_register(struct backing_dev_info *bdi, const char *fmt, ...)
902{
903 va_list args;
904 int ret;
905
906 va_start(args, fmt);
907 ret = bdi_register_va(bdi, fmt, args);
908 va_end(args);
909 return ret;
910}
911EXPORT_SYMBOL(bdi_register);
912
913int bdi_register_owner(struct backing_dev_info *bdi, struct device *owner)
914{
915 int rc;
916
917 rc = bdi_register(bdi, "%u:%u", MAJOR(owner->devt), MINOR(owner->devt));
918 if (rc)
919 return rc;
920 /* Leaking owner reference... */
921 WARN_ON(bdi->owner);
922 bdi->owner = owner;
923 get_device(owner);
924 return 0;
925}
926EXPORT_SYMBOL(bdi_register_owner);
927
928/*
929 * Remove bdi from bdi_list, and ensure that it is no longer visible
930 */
931static void bdi_remove_from_list(struct backing_dev_info *bdi)
932{
933 spin_lock_bh(&bdi_lock);
934 list_del_rcu(&bdi->bdi_list);
935 spin_unlock_bh(&bdi_lock);
936
937 synchronize_rcu_expedited();
938}
939
940void bdi_unregister(struct backing_dev_info *bdi)
941{
942 /* make sure nobody finds us on the bdi_list anymore */
943 bdi_remove_from_list(bdi);
944 wb_shutdown(&bdi->wb);
945 cgwb_bdi_unregister(bdi);
946
947 if (bdi->dev) {
948 bdi_debug_unregister(bdi);
949 device_unregister(bdi->dev);
950 bdi->dev = NULL;
951 }
952
953 if (bdi->owner) {
954 put_device(bdi->owner);
955 bdi->owner = NULL;
956 }
957}
958
959static void release_bdi(struct kref *ref)
960{
961 struct backing_dev_info *bdi =
962 container_of(ref, struct backing_dev_info, refcnt);
963
964 if (test_bit(WB_registered, &bdi->wb.state))
965 bdi_unregister(bdi);
966 WARN_ON_ONCE(bdi->dev);
967 wb_exit(&bdi->wb);
968 cgwb_bdi_exit(bdi);
969 kfree(bdi);
970}
971
972void bdi_put(struct backing_dev_info *bdi)
973{
974 kref_put(&bdi->refcnt, release_bdi);
975}
976EXPORT_SYMBOL(bdi_put);
977
978static wait_queue_head_t congestion_wqh[2] = {
979 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]),
980 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1])
981 };
982static atomic_t nr_wb_congested[2];
983
984void clear_wb_congested(struct bdi_writeback_congested *congested, int sync)
985{
986 wait_queue_head_t *wqh = &congestion_wqh[sync];
987 enum wb_congested_state bit;
988
989 bit = sync ? WB_sync_congested : WB_async_congested;
990 if (test_and_clear_bit(bit, &congested->state))
991 atomic_dec(&nr_wb_congested[sync]);
992 smp_mb__after_atomic();
993 if (waitqueue_active(wqh))
994 wake_up(wqh);
995}
996EXPORT_SYMBOL(clear_wb_congested);
997
998void set_wb_congested(struct bdi_writeback_congested *congested, int sync)
999{
1000 enum wb_congested_state bit;
1001
1002 bit = sync ? WB_sync_congested : WB_async_congested;
1003 if (!test_and_set_bit(bit, &congested->state))
1004 atomic_inc(&nr_wb_congested[sync]);
1005}
1006EXPORT_SYMBOL(set_wb_congested);
1007
1008/**
1009 * congestion_wait - wait for a backing_dev to become uncongested
1010 * @sync: SYNC or ASYNC IO
1011 * @timeout: timeout in jiffies
1012 *
1013 * Waits for up to @timeout jiffies for a backing_dev (any backing_dev) to exit
1014 * write congestion. If no backing_devs are congested then just wait for the
1015 * next write to be completed.
1016 */
1017long congestion_wait(int sync, long timeout)
1018{
1019 long ret;
1020 unsigned long start = jiffies;
1021 DEFINE_WAIT(wait);
1022 wait_queue_head_t *wqh = &congestion_wqh[sync];
1023
1024 prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
1025 ret = io_schedule_timeout(timeout);
1026 finish_wait(wqh, &wait);
1027
1028 trace_writeback_congestion_wait(jiffies_to_usecs(timeout),
1029 jiffies_to_usecs(jiffies - start));
1030
1031 return ret;
1032}
1033EXPORT_SYMBOL(congestion_wait);
1034
1035/**
1036 * wait_iff_congested - Conditionally wait for a backing_dev to become uncongested or a pgdat to complete writes
1037 * @sync: SYNC or ASYNC IO
1038 * @timeout: timeout in jiffies
1039 *
1040 * In the event of a congested backing_dev (any backing_dev) this waits
1041 * for up to @timeout jiffies for either a BDI to exit congestion of the
1042 * given @sync queue or a write to complete.
1043 *
1044 * The return value is 0 if the sleep is for the full timeout. Otherwise,
1045 * it is the number of jiffies that were still remaining when the function
1046 * returned. return_value == timeout implies the function did not sleep.
1047 */
1048long wait_iff_congested(int sync, long timeout)
1049{
1050 long ret;
1051 unsigned long start = jiffies;
1052 DEFINE_WAIT(wait);
1053 wait_queue_head_t *wqh = &congestion_wqh[sync];
1054
1055 /*
1056 * If there is no congestion, yield if necessary instead
1057 * of sleeping on the congestion queue
1058 */
1059 if (atomic_read(&nr_wb_congested[sync]) == 0) {
1060 cond_resched();
1061
1062 /* In case we scheduled, work out time remaining */
1063 ret = timeout - (jiffies - start);
1064 if (ret < 0)
1065 ret = 0;
1066
1067 goto out;
1068 }
1069
1070 /* Sleep until uncongested or a write happens */
1071 prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
1072 ret = io_schedule_timeout(timeout);
1073 finish_wait(wqh, &wait);
1074
1075out:
1076 trace_writeback_wait_iff_congested(jiffies_to_usecs(timeout),
1077 jiffies_to_usecs(jiffies - start));
1078
1079 return ret;
1080}
1081EXPORT_SYMBOL(wait_iff_congested);
1082