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1// SPDX-License-Identifier: GPL-2.0-only
2
3#include <linux/wait.h>
4#include <linux/rbtree.h>
5#include <linux/backing-dev.h>
6#include <linux/kthread.h>
7#include <linux/freezer.h>
8#include <linux/fs.h>
9#include <linux/pagemap.h>
10#include <linux/mm.h>
11#include <linux/sched.h>
12#include <linux/module.h>
13#include <linux/writeback.h>
14#include <linux/device.h>
15#include <trace/events/writeback.h>
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 bdi_tree and updates to bdi_list. bdi_list has RCU
27 * reader side locking.
28 */
29DEFINE_SPINLOCK(bdi_lock);
30static u64 bdi_id_cursor;
31static struct rb_root bdi_tree = RB_ROOT;
32LIST_HEAD(bdi_list);
33
34/* bdi_wq serves all asynchronous writeback tasks */
35struct workqueue_struct *bdi_wq;
36
37#ifdef CONFIG_DEBUG_FS
38#include <linux/debugfs.h>
39#include <linux/seq_file.h>
40
41static struct dentry *bdi_debug_root;
42
43static void bdi_debug_init(void)
44{
45 bdi_debug_root = debugfs_create_dir("bdi", NULL);
46}
47
48static int bdi_debug_stats_show(struct seq_file *m, void *v)
49{
50 struct backing_dev_info *bdi = m->private;
51 struct bdi_writeback *wb = &bdi->wb;
52 unsigned long background_thresh;
53 unsigned long dirty_thresh;
54 unsigned long wb_thresh;
55 unsigned long nr_dirty, nr_io, nr_more_io, nr_dirty_time;
56 struct inode *inode;
57
58 nr_dirty = nr_io = nr_more_io = nr_dirty_time = 0;
59 spin_lock(&wb->list_lock);
60 list_for_each_entry(inode, &wb->b_dirty, i_io_list)
61 nr_dirty++;
62 list_for_each_entry(inode, &wb->b_io, i_io_list)
63 nr_io++;
64 list_for_each_entry(inode, &wb->b_more_io, i_io_list)
65 nr_more_io++;
66 list_for_each_entry(inode, &wb->b_dirty_time, i_io_list)
67 if (inode->i_state & I_DIRTY_TIME)
68 nr_dirty_time++;
69 spin_unlock(&wb->list_lock);
70
71 global_dirty_limits(&background_thresh, &dirty_thresh);
72 wb_thresh = wb_calc_thresh(wb, dirty_thresh);
73
74#define K(x) ((x) << (PAGE_SHIFT - 10))
75 seq_printf(m,
76 "BdiWriteback: %10lu kB\n"
77 "BdiReclaimable: %10lu kB\n"
78 "BdiDirtyThresh: %10lu kB\n"
79 "DirtyThresh: %10lu kB\n"
80 "BackgroundThresh: %10lu kB\n"
81 "BdiDirtied: %10lu kB\n"
82 "BdiWritten: %10lu kB\n"
83 "BdiWriteBandwidth: %10lu kBps\n"
84 "b_dirty: %10lu\n"
85 "b_io: %10lu\n"
86 "b_more_io: %10lu\n"
87 "b_dirty_time: %10lu\n"
88 "bdi_list: %10u\n"
89 "state: %10lx\n",
90 (unsigned long) K(wb_stat(wb, WB_WRITEBACK)),
91 (unsigned long) K(wb_stat(wb, WB_RECLAIMABLE)),
92 K(wb_thresh),
93 K(dirty_thresh),
94 K(background_thresh),
95 (unsigned long) K(wb_stat(wb, WB_DIRTIED)),
96 (unsigned long) K(wb_stat(wb, WB_WRITTEN)),
97 (unsigned long) K(wb->write_bandwidth),
98 nr_dirty,
99 nr_io,
100 nr_more_io,
101 nr_dirty_time,
102 !list_empty(&bdi->bdi_list), bdi->wb.state);
103#undef K
104
105 return 0;
106}
107DEFINE_SHOW_ATTRIBUTE(bdi_debug_stats);
108
109static void bdi_debug_register(struct backing_dev_info *bdi, const char *name)
110{
111 bdi->debug_dir = debugfs_create_dir(name, bdi_debug_root);
112
113 debugfs_create_file("stats", 0444, bdi->debug_dir, bdi,
114 &bdi_debug_stats_fops);
115}
116
117static void bdi_debug_unregister(struct backing_dev_info *bdi)
118{
119 debugfs_remove_recursive(bdi->debug_dir);
120}
121#else
122static inline void bdi_debug_init(void)
123{
124}
125static inline void bdi_debug_register(struct backing_dev_info *bdi,
126 const char *name)
127{
128}
129static inline void bdi_debug_unregister(struct backing_dev_info *bdi)
130{
131}
132#endif
133
134static ssize_t read_ahead_kb_store(struct device *dev,
135 struct device_attribute *attr,
136 const char *buf, size_t count)
137{
138 struct backing_dev_info *bdi = dev_get_drvdata(dev);
139 unsigned long read_ahead_kb;
140 ssize_t ret;
141
142 ret = kstrtoul(buf, 10, &read_ahead_kb);
143 if (ret < 0)
144 return ret;
145
146 bdi->ra_pages = read_ahead_kb >> (PAGE_SHIFT - 10);
147
148 return count;
149}
150
151#define K(pages) ((pages) << (PAGE_SHIFT - 10))
152
153#define BDI_SHOW(name, expr) \
154static ssize_t name##_show(struct device *dev, \
155 struct device_attribute *attr, char *page) \
156{ \
157 struct backing_dev_info *bdi = dev_get_drvdata(dev); \
158 \
159 return snprintf(page, PAGE_SIZE-1, "%lld\n", (long long)expr); \
160} \
161static DEVICE_ATTR_RW(name);
162
163BDI_SHOW(read_ahead_kb, K(bdi->ra_pages))
164
165static ssize_t min_ratio_store(struct device *dev,
166 struct device_attribute *attr, const char *buf, size_t count)
167{
168 struct backing_dev_info *bdi = dev_get_drvdata(dev);
169 unsigned int ratio;
170 ssize_t ret;
171
172 ret = kstrtouint(buf, 10, &ratio);
173 if (ret < 0)
174 return ret;
175
176 ret = bdi_set_min_ratio(bdi, ratio);
177 if (!ret)
178 ret = count;
179
180 return ret;
181}
182BDI_SHOW(min_ratio, bdi->min_ratio)
183
184static ssize_t max_ratio_store(struct device *dev,
185 struct device_attribute *attr, const char *buf, size_t count)
186{
187 struct backing_dev_info *bdi = dev_get_drvdata(dev);
188 unsigned int ratio;
189 ssize_t ret;
190
191 ret = kstrtouint(buf, 10, &ratio);
192 if (ret < 0)
193 return ret;
194
195 ret = bdi_set_max_ratio(bdi, ratio);
196 if (!ret)
197 ret = count;
198
199 return ret;
200}
201BDI_SHOW(max_ratio, bdi->max_ratio)
202
203static ssize_t stable_pages_required_show(struct device *dev,
204 struct device_attribute *attr,
205 char *page)
206{
207 struct backing_dev_info *bdi = dev_get_drvdata(dev);
208
209 return snprintf(page, PAGE_SIZE-1, "%d\n",
210 bdi_cap_stable_pages_required(bdi) ? 1 : 0);
211}
212static DEVICE_ATTR_RO(stable_pages_required);
213
214static struct attribute *bdi_dev_attrs[] = {
215 &dev_attr_read_ahead_kb.attr,
216 &dev_attr_min_ratio.attr,
217 &dev_attr_max_ratio.attr,
218 &dev_attr_stable_pages_required.attr,
219 NULL,
220};
221ATTRIBUTE_GROUPS(bdi_dev);
222
223static __init int bdi_class_init(void)
224{
225 bdi_class = class_create(THIS_MODULE, "bdi");
226 if (IS_ERR(bdi_class))
227 return PTR_ERR(bdi_class);
228
229 bdi_class->dev_groups = bdi_dev_groups;
230 bdi_debug_init();
231
232 return 0;
233}
234postcore_initcall(bdi_class_init);
235
236static int bdi_init(struct backing_dev_info *bdi);
237
238static int __init default_bdi_init(void)
239{
240 int err;
241
242 bdi_wq = alloc_workqueue("writeback", WQ_MEM_RECLAIM | WQ_UNBOUND |
243 WQ_SYSFS, 0);
244 if (!bdi_wq)
245 return -ENOMEM;
246
247 err = bdi_init(&noop_backing_dev_info);
248
249 return err;
250}
251subsys_initcall(default_bdi_init);
252
253/*
254 * This function is used when the first inode for this wb is marked dirty. It
255 * wakes-up the corresponding bdi thread which should then take care of the
256 * periodic background write-out of dirty inodes. Since the write-out would
257 * starts only 'dirty_writeback_interval' centisecs from now anyway, we just
258 * set up a timer which wakes the bdi thread up later.
259 *
260 * Note, we wouldn't bother setting up the timer, but this function is on the
261 * fast-path (used by '__mark_inode_dirty()'), so we save few context switches
262 * by delaying the wake-up.
263 *
264 * We have to be careful not to postpone flush work if it is scheduled for
265 * earlier. Thus we use queue_delayed_work().
266 */
267void wb_wakeup_delayed(struct bdi_writeback *wb)
268{
269 unsigned long timeout;
270
271 timeout = msecs_to_jiffies(dirty_writeback_interval * 10);
272 spin_lock_bh(&wb->work_lock);
273 if (test_bit(WB_registered, &wb->state))
274 queue_delayed_work(bdi_wq, &wb->dwork, timeout);
275 spin_unlock_bh(&wb->work_lock);
276}
277
278/*
279 * Initial write bandwidth: 100 MB/s
280 */
281#define INIT_BW (100 << (20 - PAGE_SHIFT))
282
283static int wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi,
284 int blkcg_id, gfp_t gfp)
285{
286 int i, err;
287
288 memset(wb, 0, sizeof(*wb));
289
290 if (wb != &bdi->wb)
291 bdi_get(bdi);
292 wb->bdi = bdi;
293 wb->last_old_flush = jiffies;
294 INIT_LIST_HEAD(&wb->b_dirty);
295 INIT_LIST_HEAD(&wb->b_io);
296 INIT_LIST_HEAD(&wb->b_more_io);
297 INIT_LIST_HEAD(&wb->b_dirty_time);
298 spin_lock_init(&wb->list_lock);
299
300 wb->bw_time_stamp = jiffies;
301 wb->balanced_dirty_ratelimit = INIT_BW;
302 wb->dirty_ratelimit = INIT_BW;
303 wb->write_bandwidth = INIT_BW;
304 wb->avg_write_bandwidth = INIT_BW;
305
306 spin_lock_init(&wb->work_lock);
307 INIT_LIST_HEAD(&wb->work_list);
308 INIT_DELAYED_WORK(&wb->dwork, wb_workfn);
309 wb->dirty_sleep = jiffies;
310
311 wb->congested = wb_congested_get_create(bdi, blkcg_id, gfp);
312 if (!wb->congested) {
313 err = -ENOMEM;
314 goto out_put_bdi;
315 }
316
317 err = fprop_local_init_percpu(&wb->completions, gfp);
318 if (err)
319 goto out_put_cong;
320
321 for (i = 0; i < NR_WB_STAT_ITEMS; i++) {
322 err = percpu_counter_init(&wb->stat[i], 0, gfp);
323 if (err)
324 goto out_destroy_stat;
325 }
326
327 return 0;
328
329out_destroy_stat:
330 while (i--)
331 percpu_counter_destroy(&wb->stat[i]);
332 fprop_local_destroy_percpu(&wb->completions);
333out_put_cong:
334 wb_congested_put(wb->congested);
335out_put_bdi:
336 if (wb != &bdi->wb)
337 bdi_put(bdi);
338 return err;
339}
340
341static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb);
342
343/*
344 * Remove bdi from the global list and shutdown any threads we have running
345 */
346static void wb_shutdown(struct bdi_writeback *wb)
347{
348 /* Make sure nobody queues further work */
349 spin_lock_bh(&wb->work_lock);
350 if (!test_and_clear_bit(WB_registered, &wb->state)) {
351 spin_unlock_bh(&wb->work_lock);
352 return;
353 }
354 spin_unlock_bh(&wb->work_lock);
355
356 cgwb_remove_from_bdi_list(wb);
357 /*
358 * Drain work list and shutdown the delayed_work. !WB_registered
359 * tells wb_workfn() that @wb is dying and its work_list needs to
360 * be drained no matter what.
361 */
362 mod_delayed_work(bdi_wq, &wb->dwork, 0);
363 flush_delayed_work(&wb->dwork);
364 WARN_ON(!list_empty(&wb->work_list));
365}
366
367static void wb_exit(struct bdi_writeback *wb)
368{
369 int i;
370
371 WARN_ON(delayed_work_pending(&wb->dwork));
372
373 for (i = 0; i < NR_WB_STAT_ITEMS; i++)
374 percpu_counter_destroy(&wb->stat[i]);
375
376 fprop_local_destroy_percpu(&wb->completions);
377 wb_congested_put(wb->congested);
378 if (wb != &wb->bdi->wb)
379 bdi_put(wb->bdi);
380}
381
382#ifdef CONFIG_CGROUP_WRITEBACK
383
384#include <linux/memcontrol.h>
385
386/*
387 * cgwb_lock protects bdi->cgwb_tree, bdi->cgwb_congested_tree,
388 * blkcg->cgwb_list, and memcg->cgwb_list. bdi->cgwb_tree is also RCU
389 * protected.
390 */
391static DEFINE_SPINLOCK(cgwb_lock);
392static struct workqueue_struct *cgwb_release_wq;
393
394/**
395 * wb_congested_get_create - get or create a wb_congested
396 * @bdi: associated bdi
397 * @blkcg_id: ID of the associated blkcg
398 * @gfp: allocation mask
399 *
400 * Look up the wb_congested for @blkcg_id on @bdi. If missing, create one.
401 * The returned wb_congested has its reference count incremented. Returns
402 * NULL on failure.
403 */
404struct bdi_writeback_congested *
405wb_congested_get_create(struct backing_dev_info *bdi, int blkcg_id, gfp_t gfp)
406{
407 struct bdi_writeback_congested *new_congested = NULL, *congested;
408 struct rb_node **node, *parent;
409 unsigned long flags;
410retry:
411 spin_lock_irqsave(&cgwb_lock, flags);
412
413 node = &bdi->cgwb_congested_tree.rb_node;
414 parent = NULL;
415
416 while (*node != NULL) {
417 parent = *node;
418 congested = rb_entry(parent, struct bdi_writeback_congested,
419 rb_node);
420 if (congested->blkcg_id < blkcg_id)
421 node = &parent->rb_left;
422 else if (congested->blkcg_id > blkcg_id)
423 node = &parent->rb_right;
424 else
425 goto found;
426 }
427
428 if (new_congested) {
429 /* !found and storage for new one already allocated, insert */
430 congested = new_congested;
431 rb_link_node(&congested->rb_node, parent, node);
432 rb_insert_color(&congested->rb_node, &bdi->cgwb_congested_tree);
433 spin_unlock_irqrestore(&cgwb_lock, flags);
434 return congested;
435 }
436
437 spin_unlock_irqrestore(&cgwb_lock, flags);
438
439 /* allocate storage for new one and retry */
440 new_congested = kzalloc(sizeof(*new_congested), gfp);
441 if (!new_congested)
442 return NULL;
443
444 refcount_set(&new_congested->refcnt, 1);
445 new_congested->__bdi = bdi;
446 new_congested->blkcg_id = blkcg_id;
447 goto retry;
448
449found:
450 refcount_inc(&congested->refcnt);
451 spin_unlock_irqrestore(&cgwb_lock, flags);
452 kfree(new_congested);
453 return congested;
454}
455
456/**
457 * wb_congested_put - put a wb_congested
458 * @congested: wb_congested to put
459 *
460 * Put @congested and destroy it if the refcnt reaches zero.
461 */
462void wb_congested_put(struct bdi_writeback_congested *congested)
463{
464 unsigned long flags;
465
466 if (!refcount_dec_and_lock_irqsave(&congested->refcnt, &cgwb_lock, &flags))
467 return;
468
469 /* bdi might already have been destroyed leaving @congested unlinked */
470 if (congested->__bdi) {
471 rb_erase(&congested->rb_node,
472 &congested->__bdi->cgwb_congested_tree);
473 congested->__bdi = NULL;
474 }
475
476 spin_unlock_irqrestore(&cgwb_lock, flags);
477 kfree(congested);
478}
479
480static void cgwb_release_workfn(struct work_struct *work)
481{
482 struct bdi_writeback *wb = container_of(work, struct bdi_writeback,
483 release_work);
484 struct blkcg *blkcg = css_to_blkcg(wb->blkcg_css);
485
486 mutex_lock(&wb->bdi->cgwb_release_mutex);
487 wb_shutdown(wb);
488
489 css_put(wb->memcg_css);
490 css_put(wb->blkcg_css);
491 mutex_unlock(&wb->bdi->cgwb_release_mutex);
492
493 /* triggers blkg destruction if cgwb_refcnt becomes zero */
494 blkcg_cgwb_put(blkcg);
495
496 fprop_local_destroy_percpu(&wb->memcg_completions);
497 percpu_ref_exit(&wb->refcnt);
498 wb_exit(wb);
499 kfree_rcu(wb, rcu);
500}
501
502static void cgwb_release(struct percpu_ref *refcnt)
503{
504 struct bdi_writeback *wb = container_of(refcnt, struct bdi_writeback,
505 refcnt);
506 queue_work(cgwb_release_wq, &wb->release_work);
507}
508
509static void cgwb_kill(struct bdi_writeback *wb)
510{
511 lockdep_assert_held(&cgwb_lock);
512
513 WARN_ON(!radix_tree_delete(&wb->bdi->cgwb_tree, wb->memcg_css->id));
514 list_del(&wb->memcg_node);
515 list_del(&wb->blkcg_node);
516 percpu_ref_kill(&wb->refcnt);
517}
518
519static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb)
520{
521 spin_lock_irq(&cgwb_lock);
522 list_del_rcu(&wb->bdi_node);
523 spin_unlock_irq(&cgwb_lock);
524}
525
526static int cgwb_create(struct backing_dev_info *bdi,
527 struct cgroup_subsys_state *memcg_css, gfp_t gfp)
528{
529 struct mem_cgroup *memcg;
530 struct cgroup_subsys_state *blkcg_css;
531 struct blkcg *blkcg;
532 struct list_head *memcg_cgwb_list, *blkcg_cgwb_list;
533 struct bdi_writeback *wb;
534 unsigned long flags;
535 int ret = 0;
536
537 memcg = mem_cgroup_from_css(memcg_css);
538 blkcg_css = cgroup_get_e_css(memcg_css->cgroup, &io_cgrp_subsys);
539 blkcg = css_to_blkcg(blkcg_css);
540 memcg_cgwb_list = &memcg->cgwb_list;
541 blkcg_cgwb_list = &blkcg->cgwb_list;
542
543 /* look up again under lock and discard on blkcg mismatch */
544 spin_lock_irqsave(&cgwb_lock, flags);
545 wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id);
546 if (wb && wb->blkcg_css != blkcg_css) {
547 cgwb_kill(wb);
548 wb = NULL;
549 }
550 spin_unlock_irqrestore(&cgwb_lock, flags);
551 if (wb)
552 goto out_put;
553
554 /* need to create a new one */
555 wb = kmalloc(sizeof(*wb), gfp);
556 if (!wb) {
557 ret = -ENOMEM;
558 goto out_put;
559 }
560
561 ret = wb_init(wb, bdi, blkcg_css->id, gfp);
562 if (ret)
563 goto err_free;
564
565 ret = percpu_ref_init(&wb->refcnt, cgwb_release, 0, gfp);
566 if (ret)
567 goto err_wb_exit;
568
569 ret = fprop_local_init_percpu(&wb->memcg_completions, gfp);
570 if (ret)
571 goto err_ref_exit;
572
573 wb->memcg_css = memcg_css;
574 wb->blkcg_css = blkcg_css;
575 INIT_WORK(&wb->release_work, cgwb_release_workfn);
576 set_bit(WB_registered, &wb->state);
577
578 /*
579 * The root wb determines the registered state of the whole bdi and
580 * memcg_cgwb_list and blkcg_cgwb_list's next pointers indicate
581 * whether they're still online. Don't link @wb if any is dead.
582 * See wb_memcg_offline() and wb_blkcg_offline().
583 */
584 ret = -ENODEV;
585 spin_lock_irqsave(&cgwb_lock, flags);
586 if (test_bit(WB_registered, &bdi->wb.state) &&
587 blkcg_cgwb_list->next && memcg_cgwb_list->next) {
588 /* we might have raced another instance of this function */
589 ret = radix_tree_insert(&bdi->cgwb_tree, memcg_css->id, wb);
590 if (!ret) {
591 list_add_tail_rcu(&wb->bdi_node, &bdi->wb_list);
592 list_add(&wb->memcg_node, memcg_cgwb_list);
593 list_add(&wb->blkcg_node, blkcg_cgwb_list);
594 blkcg_cgwb_get(blkcg);
595 css_get(memcg_css);
596 css_get(blkcg_css);
597 }
598 }
599 spin_unlock_irqrestore(&cgwb_lock, flags);
600 if (ret) {
601 if (ret == -EEXIST)
602 ret = 0;
603 goto err_fprop_exit;
604 }
605 goto out_put;
606
607err_fprop_exit:
608 fprop_local_destroy_percpu(&wb->memcg_completions);
609err_ref_exit:
610 percpu_ref_exit(&wb->refcnt);
611err_wb_exit:
612 wb_exit(wb);
613err_free:
614 kfree(wb);
615out_put:
616 css_put(blkcg_css);
617 return ret;
618}
619
620/**
621 * wb_get_lookup - get wb for a given memcg
622 * @bdi: target bdi
623 * @memcg_css: cgroup_subsys_state of the target memcg (must have positive ref)
624 *
625 * Try to get the wb for @memcg_css on @bdi. The returned wb has its
626 * refcount incremented.
627 *
628 * This function uses css_get() on @memcg_css and thus expects its refcnt
629 * to be positive on invocation. IOW, rcu_read_lock() protection on
630 * @memcg_css isn't enough. try_get it before calling this function.
631 *
632 * A wb is keyed by its associated memcg. As blkcg implicitly enables
633 * memcg on the default hierarchy, memcg association is guaranteed to be
634 * more specific (equal or descendant to the associated blkcg) and thus can
635 * identify both the memcg and blkcg associations.
636 *
637 * Because the blkcg associated with a memcg may change as blkcg is enabled
638 * and disabled closer to root in the hierarchy, each wb keeps track of
639 * both the memcg and blkcg associated with it and verifies the blkcg on
640 * each lookup. On mismatch, the existing wb is discarded and a new one is
641 * created.
642 */
643struct bdi_writeback *wb_get_lookup(struct backing_dev_info *bdi,
644 struct cgroup_subsys_state *memcg_css)
645{
646 struct bdi_writeback *wb;
647
648 if (!memcg_css->parent)
649 return &bdi->wb;
650
651 rcu_read_lock();
652 wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id);
653 if (wb) {
654 struct cgroup_subsys_state *blkcg_css;
655
656 /* see whether the blkcg association has changed */
657 blkcg_css = cgroup_get_e_css(memcg_css->cgroup, &io_cgrp_subsys);
658 if (unlikely(wb->blkcg_css != blkcg_css || !wb_tryget(wb)))
659 wb = NULL;
660 css_put(blkcg_css);
661 }
662 rcu_read_unlock();
663
664 return wb;
665}
666
667/**
668 * wb_get_create - get wb for a given memcg, create if necessary
669 * @bdi: target bdi
670 * @memcg_css: cgroup_subsys_state of the target memcg (must have positive ref)
671 * @gfp: allocation mask to use
672 *
673 * Try to get the wb for @memcg_css on @bdi. If it doesn't exist, try to
674 * create one. See wb_get_lookup() for more details.
675 */
676struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi,
677 struct cgroup_subsys_state *memcg_css,
678 gfp_t gfp)
679{
680 struct bdi_writeback *wb;
681
682 might_sleep_if(gfpflags_allow_blocking(gfp));
683
684 if (!memcg_css->parent)
685 return &bdi->wb;
686
687 do {
688 wb = wb_get_lookup(bdi, memcg_css);
689 } while (!wb && !cgwb_create(bdi, memcg_css, gfp));
690
691 return wb;
692}
693
694static int cgwb_bdi_init(struct backing_dev_info *bdi)
695{
696 int ret;
697
698 INIT_RADIX_TREE(&bdi->cgwb_tree, GFP_ATOMIC);
699 bdi->cgwb_congested_tree = RB_ROOT;
700 mutex_init(&bdi->cgwb_release_mutex);
701 init_rwsem(&bdi->wb_switch_rwsem);
702
703 ret = wb_init(&bdi->wb, bdi, 1, GFP_KERNEL);
704 if (!ret) {
705 bdi->wb.memcg_css = &root_mem_cgroup->css;
706 bdi->wb.blkcg_css = blkcg_root_css;
707 }
708 return ret;
709}
710
711static void cgwb_bdi_unregister(struct backing_dev_info *bdi)
712{
713 struct radix_tree_iter iter;
714 void **slot;
715 struct bdi_writeback *wb;
716
717 WARN_ON(test_bit(WB_registered, &bdi->wb.state));
718
719 spin_lock_irq(&cgwb_lock);
720 radix_tree_for_each_slot(slot, &bdi->cgwb_tree, &iter, 0)
721 cgwb_kill(*slot);
722 spin_unlock_irq(&cgwb_lock);
723
724 mutex_lock(&bdi->cgwb_release_mutex);
725 spin_lock_irq(&cgwb_lock);
726 while (!list_empty(&bdi->wb_list)) {
727 wb = list_first_entry(&bdi->wb_list, struct bdi_writeback,
728 bdi_node);
729 spin_unlock_irq(&cgwb_lock);
730 wb_shutdown(wb);
731 spin_lock_irq(&cgwb_lock);
732 }
733 spin_unlock_irq(&cgwb_lock);
734 mutex_unlock(&bdi->cgwb_release_mutex);
735}
736
737/**
738 * wb_memcg_offline - kill all wb's associated with a memcg being offlined
739 * @memcg: memcg being offlined
740 *
741 * Also prevents creation of any new wb's associated with @memcg.
742 */
743void wb_memcg_offline(struct mem_cgroup *memcg)
744{
745 struct list_head *memcg_cgwb_list = &memcg->cgwb_list;
746 struct bdi_writeback *wb, *next;
747
748 spin_lock_irq(&cgwb_lock);
749 list_for_each_entry_safe(wb, next, memcg_cgwb_list, memcg_node)
750 cgwb_kill(wb);
751 memcg_cgwb_list->next = NULL; /* prevent new wb's */
752 spin_unlock_irq(&cgwb_lock);
753}
754
755/**
756 * wb_blkcg_offline - kill all wb's associated with a blkcg being offlined
757 * @blkcg: blkcg being offlined
758 *
759 * Also prevents creation of any new wb's associated with @blkcg.
760 */
761void wb_blkcg_offline(struct blkcg *blkcg)
762{
763 struct bdi_writeback *wb, *next;
764
765 spin_lock_irq(&cgwb_lock);
766 list_for_each_entry_safe(wb, next, &blkcg->cgwb_list, blkcg_node)
767 cgwb_kill(wb);
768 blkcg->cgwb_list.next = NULL; /* prevent new wb's */
769 spin_unlock_irq(&cgwb_lock);
770}
771
772static void cgwb_bdi_exit(struct backing_dev_info *bdi)
773{
774 struct rb_node *rbn;
775
776 spin_lock_irq(&cgwb_lock);
777 while ((rbn = rb_first(&bdi->cgwb_congested_tree))) {
778 struct bdi_writeback_congested *congested =
779 rb_entry(rbn, struct bdi_writeback_congested, rb_node);
780
781 rb_erase(rbn, &bdi->cgwb_congested_tree);
782 congested->__bdi = NULL; /* mark @congested unlinked */
783 }
784 spin_unlock_irq(&cgwb_lock);
785}
786
787static void cgwb_bdi_register(struct backing_dev_info *bdi)
788{
789 spin_lock_irq(&cgwb_lock);
790 list_add_tail_rcu(&bdi->wb.bdi_node, &bdi->wb_list);
791 spin_unlock_irq(&cgwb_lock);
792}
793
794static int __init cgwb_init(void)
795{
796 /*
797 * There can be many concurrent release work items overwhelming
798 * system_wq. Put them in a separate wq and limit concurrency.
799 * There's no point in executing many of these in parallel.
800 */
801 cgwb_release_wq = alloc_workqueue("cgwb_release", 0, 1);
802 if (!cgwb_release_wq)
803 return -ENOMEM;
804
805 return 0;
806}
807subsys_initcall(cgwb_init);
808
809#else /* CONFIG_CGROUP_WRITEBACK */
810
811static int cgwb_bdi_init(struct backing_dev_info *bdi)
812{
813 int err;
814
815 bdi->wb_congested = kzalloc(sizeof(*bdi->wb_congested), GFP_KERNEL);
816 if (!bdi->wb_congested)
817 return -ENOMEM;
818
819 refcount_set(&bdi->wb_congested->refcnt, 1);
820
821 err = wb_init(&bdi->wb, bdi, 1, GFP_KERNEL);
822 if (err) {
823 wb_congested_put(bdi->wb_congested);
824 return err;
825 }
826 return 0;
827}
828
829static void cgwb_bdi_unregister(struct backing_dev_info *bdi) { }
830
831static void cgwb_bdi_exit(struct backing_dev_info *bdi)
832{
833 wb_congested_put(bdi->wb_congested);
834}
835
836static void cgwb_bdi_register(struct backing_dev_info *bdi)
837{
838 list_add_tail_rcu(&bdi->wb.bdi_node, &bdi->wb_list);
839}
840
841static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb)
842{
843 list_del_rcu(&wb->bdi_node);
844}
845
846#endif /* CONFIG_CGROUP_WRITEBACK */
847
848static int bdi_init(struct backing_dev_info *bdi)
849{
850 int ret;
851
852 bdi->dev = NULL;
853
854 kref_init(&bdi->refcnt);
855 bdi->min_ratio = 0;
856 bdi->max_ratio = 100;
857 bdi->max_prop_frac = FPROP_FRAC_BASE;
858 INIT_LIST_HEAD(&bdi->bdi_list);
859 INIT_LIST_HEAD(&bdi->wb_list);
860 init_waitqueue_head(&bdi->wb_waitq);
861
862 ret = cgwb_bdi_init(bdi);
863
864 return ret;
865}
866
867struct backing_dev_info *bdi_alloc_node(gfp_t gfp_mask, int node_id)
868{
869 struct backing_dev_info *bdi;
870
871 bdi = kmalloc_node(sizeof(struct backing_dev_info),
872 gfp_mask | __GFP_ZERO, node_id);
873 if (!bdi)
874 return NULL;
875
876 if (bdi_init(bdi)) {
877 kfree(bdi);
878 return NULL;
879 }
880 return bdi;
881}
882EXPORT_SYMBOL(bdi_alloc_node);
883
884static struct rb_node **bdi_lookup_rb_node(u64 id, struct rb_node **parentp)
885{
886 struct rb_node **p = &bdi_tree.rb_node;
887 struct rb_node *parent = NULL;
888 struct backing_dev_info *bdi;
889
890 lockdep_assert_held(&bdi_lock);
891
892 while (*p) {
893 parent = *p;
894 bdi = rb_entry(parent, struct backing_dev_info, rb_node);
895
896 if (bdi->id > id)
897 p = &(*p)->rb_left;
898 else if (bdi->id < id)
899 p = &(*p)->rb_right;
900 else
901 break;
902 }
903
904 if (parentp)
905 *parentp = parent;
906 return p;
907}
908
909/**
910 * bdi_get_by_id - lookup and get bdi from its id
911 * @id: bdi id to lookup
912 *
913 * Find bdi matching @id and get it. Returns NULL if the matching bdi
914 * doesn't exist or is already unregistered.
915 */
916struct backing_dev_info *bdi_get_by_id(u64 id)
917{
918 struct backing_dev_info *bdi = NULL;
919 struct rb_node **p;
920
921 spin_lock_bh(&bdi_lock);
922 p = bdi_lookup_rb_node(id, NULL);
923 if (*p) {
924 bdi = rb_entry(*p, struct backing_dev_info, rb_node);
925 bdi_get(bdi);
926 }
927 spin_unlock_bh(&bdi_lock);
928
929 return bdi;
930}
931
932int bdi_register_va(struct backing_dev_info *bdi, const char *fmt, va_list args)
933{
934 struct device *dev;
935 struct rb_node *parent, **p;
936
937 if (bdi->dev) /* The driver needs to use separate queues per device */
938 return 0;
939
940 dev = device_create_vargs(bdi_class, NULL, MKDEV(0, 0), bdi, fmt, args);
941 if (IS_ERR(dev))
942 return PTR_ERR(dev);
943
944 cgwb_bdi_register(bdi);
945 bdi->dev = dev;
946
947 bdi_debug_register(bdi, dev_name(dev));
948 set_bit(WB_registered, &bdi->wb.state);
949
950 spin_lock_bh(&bdi_lock);
951
952 bdi->id = ++bdi_id_cursor;
953
954 p = bdi_lookup_rb_node(bdi->id, &parent);
955 rb_link_node(&bdi->rb_node, parent, p);
956 rb_insert_color(&bdi->rb_node, &bdi_tree);
957
958 list_add_tail_rcu(&bdi->bdi_list, &bdi_list);
959
960 spin_unlock_bh(&bdi_lock);
961
962 trace_writeback_bdi_register(bdi);
963 return 0;
964}
965EXPORT_SYMBOL(bdi_register_va);
966
967int bdi_register(struct backing_dev_info *bdi, const char *fmt, ...)
968{
969 va_list args;
970 int ret;
971
972 va_start(args, fmt);
973 ret = bdi_register_va(bdi, fmt, args);
974 va_end(args);
975 return ret;
976}
977EXPORT_SYMBOL(bdi_register);
978
979int bdi_register_owner(struct backing_dev_info *bdi, struct device *owner)
980{
981 int rc;
982
983 rc = bdi_register(bdi, "%u:%u", MAJOR(owner->devt), MINOR(owner->devt));
984 if (rc)
985 return rc;
986 /* Leaking owner reference... */
987 WARN_ON(bdi->owner);
988 bdi->owner = owner;
989 get_device(owner);
990 return 0;
991}
992EXPORT_SYMBOL(bdi_register_owner);
993
994/*
995 * Remove bdi from bdi_list, and ensure that it is no longer visible
996 */
997static void bdi_remove_from_list(struct backing_dev_info *bdi)
998{
999 spin_lock_bh(&bdi_lock);
1000 rb_erase(&bdi->rb_node, &bdi_tree);
1001 list_del_rcu(&bdi->bdi_list);
1002 spin_unlock_bh(&bdi_lock);
1003
1004 synchronize_rcu_expedited();
1005}
1006
1007void bdi_unregister(struct backing_dev_info *bdi)
1008{
1009 /* make sure nobody finds us on the bdi_list anymore */
1010 bdi_remove_from_list(bdi);
1011 wb_shutdown(&bdi->wb);
1012 cgwb_bdi_unregister(bdi);
1013
1014 if (bdi->dev) {
1015 bdi_debug_unregister(bdi);
1016 device_unregister(bdi->dev);
1017 bdi->dev = NULL;
1018 }
1019
1020 if (bdi->owner) {
1021 put_device(bdi->owner);
1022 bdi->owner = NULL;
1023 }
1024}
1025
1026static void release_bdi(struct kref *ref)
1027{
1028 struct backing_dev_info *bdi =
1029 container_of(ref, struct backing_dev_info, refcnt);
1030
1031 if (test_bit(WB_registered, &bdi->wb.state))
1032 bdi_unregister(bdi);
1033 WARN_ON_ONCE(bdi->dev);
1034 wb_exit(&bdi->wb);
1035 cgwb_bdi_exit(bdi);
1036 kfree(bdi);
1037}
1038
1039void bdi_put(struct backing_dev_info *bdi)
1040{
1041 kref_put(&bdi->refcnt, release_bdi);
1042}
1043EXPORT_SYMBOL(bdi_put);
1044
1045static wait_queue_head_t congestion_wqh[2] = {
1046 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]),
1047 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1])
1048 };
1049static atomic_t nr_wb_congested[2];
1050
1051void clear_wb_congested(struct bdi_writeback_congested *congested, int sync)
1052{
1053 wait_queue_head_t *wqh = &congestion_wqh[sync];
1054 enum wb_congested_state bit;
1055
1056 bit = sync ? WB_sync_congested : WB_async_congested;
1057 if (test_and_clear_bit(bit, &congested->state))
1058 atomic_dec(&nr_wb_congested[sync]);
1059 smp_mb__after_atomic();
1060 if (waitqueue_active(wqh))
1061 wake_up(wqh);
1062}
1063EXPORT_SYMBOL(clear_wb_congested);
1064
1065void set_wb_congested(struct bdi_writeback_congested *congested, int sync)
1066{
1067 enum wb_congested_state bit;
1068
1069 bit = sync ? WB_sync_congested : WB_async_congested;
1070 if (!test_and_set_bit(bit, &congested->state))
1071 atomic_inc(&nr_wb_congested[sync]);
1072}
1073EXPORT_SYMBOL(set_wb_congested);
1074
1075/**
1076 * congestion_wait - wait for a backing_dev to become uncongested
1077 * @sync: SYNC or ASYNC IO
1078 * @timeout: timeout in jiffies
1079 *
1080 * Waits for up to @timeout jiffies for a backing_dev (any backing_dev) to exit
1081 * write congestion. If no backing_devs are congested then just wait for the
1082 * next write to be completed.
1083 */
1084long congestion_wait(int sync, long timeout)
1085{
1086 long ret;
1087 unsigned long start = jiffies;
1088 DEFINE_WAIT(wait);
1089 wait_queue_head_t *wqh = &congestion_wqh[sync];
1090
1091 prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
1092 ret = io_schedule_timeout(timeout);
1093 finish_wait(wqh, &wait);
1094
1095 trace_writeback_congestion_wait(jiffies_to_usecs(timeout),
1096 jiffies_to_usecs(jiffies - start));
1097
1098 return ret;
1099}
1100EXPORT_SYMBOL(congestion_wait);
1101
1102/**
1103 * wait_iff_congested - Conditionally wait for a backing_dev to become uncongested or a pgdat to complete writes
1104 * @sync: SYNC or ASYNC IO
1105 * @timeout: timeout in jiffies
1106 *
1107 * In the event of a congested backing_dev (any backing_dev) this waits
1108 * for up to @timeout jiffies for either a BDI to exit congestion of the
1109 * given @sync queue or a write to complete.
1110 *
1111 * The return value is 0 if the sleep is for the full timeout. Otherwise,
1112 * it is the number of jiffies that were still remaining when the function
1113 * returned. return_value == timeout implies the function did not sleep.
1114 */
1115long wait_iff_congested(int sync, long timeout)
1116{
1117 long ret;
1118 unsigned long start = jiffies;
1119 DEFINE_WAIT(wait);
1120 wait_queue_head_t *wqh = &congestion_wqh[sync];
1121
1122 /*
1123 * If there is no congestion, yield if necessary instead
1124 * of sleeping on the congestion queue
1125 */
1126 if (atomic_read(&nr_wb_congested[sync]) == 0) {
1127 cond_resched();
1128
1129 /* In case we scheduled, work out time remaining */
1130 ret = timeout - (jiffies - start);
1131 if (ret < 0)
1132 ret = 0;
1133
1134 goto out;
1135 }
1136
1137 /* Sleep until uncongested or a write happens */
1138 prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
1139 ret = io_schedule_timeout(timeout);
1140 finish_wait(wqh, &wait);
1141
1142out:
1143 trace_writeback_wait_iff_congested(jiffies_to_usecs(timeout),
1144 jiffies_to_usecs(jiffies - start));
1145
1146 return ret;
1147}
1148EXPORT_SYMBOL(wait_iff_congested);
1// SPDX-License-Identifier: GPL-2.0-only
2
3#include <linux/blkdev.h>
4#include <linux/wait.h>
5#include <linux/rbtree.h>
6#include <linux/kthread.h>
7#include <linux/backing-dev.h>
8#include <linux/blk-cgroup.h>
9#include <linux/freezer.h>
10#include <linux/fs.h>
11#include <linux/pagemap.h>
12#include <linux/mm.h>
13#include <linux/sched/mm.h>
14#include <linux/sched.h>
15#include <linux/module.h>
16#include <linux/writeback.h>
17#include <linux/device.h>
18#include <trace/events/writeback.h>
19#include "internal.h"
20
21struct backing_dev_info noop_backing_dev_info;
22EXPORT_SYMBOL_GPL(noop_backing_dev_info);
23
24static const char *bdi_unknown_name = "(unknown)";
25
26/*
27 * bdi_lock protects bdi_tree and updates to bdi_list. bdi_list has RCU
28 * reader side locking.
29 */
30DEFINE_SPINLOCK(bdi_lock);
31static u64 bdi_id_cursor;
32static struct rb_root bdi_tree = RB_ROOT;
33LIST_HEAD(bdi_list);
34
35/* bdi_wq serves all asynchronous writeback tasks */
36struct workqueue_struct *bdi_wq;
37
38#ifdef CONFIG_DEBUG_FS
39#include <linux/debugfs.h>
40#include <linux/seq_file.h>
41
42struct wb_stats {
43 unsigned long nr_dirty;
44 unsigned long nr_io;
45 unsigned long nr_more_io;
46 unsigned long nr_dirty_time;
47 unsigned long nr_writeback;
48 unsigned long nr_reclaimable;
49 unsigned long nr_dirtied;
50 unsigned long nr_written;
51 unsigned long dirty_thresh;
52 unsigned long wb_thresh;
53};
54
55static struct dentry *bdi_debug_root;
56
57static void bdi_debug_init(void)
58{
59 bdi_debug_root = debugfs_create_dir("bdi", NULL);
60}
61
62static void collect_wb_stats(struct wb_stats *stats,
63 struct bdi_writeback *wb)
64{
65 struct inode *inode;
66
67 spin_lock(&wb->list_lock);
68 list_for_each_entry(inode, &wb->b_dirty, i_io_list)
69 stats->nr_dirty++;
70 list_for_each_entry(inode, &wb->b_io, i_io_list)
71 stats->nr_io++;
72 list_for_each_entry(inode, &wb->b_more_io, i_io_list)
73 stats->nr_more_io++;
74 list_for_each_entry(inode, &wb->b_dirty_time, i_io_list)
75 if (inode->i_state & I_DIRTY_TIME)
76 stats->nr_dirty_time++;
77 spin_unlock(&wb->list_lock);
78
79 stats->nr_writeback += wb_stat(wb, WB_WRITEBACK);
80 stats->nr_reclaimable += wb_stat(wb, WB_RECLAIMABLE);
81 stats->nr_dirtied += wb_stat(wb, WB_DIRTIED);
82 stats->nr_written += wb_stat(wb, WB_WRITTEN);
83 stats->wb_thresh += wb_calc_thresh(wb, stats->dirty_thresh);
84}
85
86#ifdef CONFIG_CGROUP_WRITEBACK
87static void bdi_collect_stats(struct backing_dev_info *bdi,
88 struct wb_stats *stats)
89{
90 struct bdi_writeback *wb;
91
92 rcu_read_lock();
93 list_for_each_entry_rcu(wb, &bdi->wb_list, bdi_node) {
94 if (!wb_tryget(wb))
95 continue;
96
97 collect_wb_stats(stats, wb);
98 wb_put(wb);
99 }
100 rcu_read_unlock();
101}
102#else
103static void bdi_collect_stats(struct backing_dev_info *bdi,
104 struct wb_stats *stats)
105{
106 collect_wb_stats(stats, &bdi->wb);
107}
108#endif
109
110static int bdi_debug_stats_show(struct seq_file *m, void *v)
111{
112 struct backing_dev_info *bdi = m->private;
113 unsigned long background_thresh;
114 unsigned long dirty_thresh;
115 struct wb_stats stats;
116 unsigned long tot_bw;
117
118 global_dirty_limits(&background_thresh, &dirty_thresh);
119
120 memset(&stats, 0, sizeof(stats));
121 stats.dirty_thresh = dirty_thresh;
122 bdi_collect_stats(bdi, &stats);
123 tot_bw = atomic_long_read(&bdi->tot_write_bandwidth);
124
125 seq_printf(m,
126 "BdiWriteback: %10lu kB\n"
127 "BdiReclaimable: %10lu kB\n"
128 "BdiDirtyThresh: %10lu kB\n"
129 "DirtyThresh: %10lu kB\n"
130 "BackgroundThresh: %10lu kB\n"
131 "BdiDirtied: %10lu kB\n"
132 "BdiWritten: %10lu kB\n"
133 "BdiWriteBandwidth: %10lu kBps\n"
134 "b_dirty: %10lu\n"
135 "b_io: %10lu\n"
136 "b_more_io: %10lu\n"
137 "b_dirty_time: %10lu\n"
138 "bdi_list: %10u\n"
139 "state: %10lx\n",
140 K(stats.nr_writeback),
141 K(stats.nr_reclaimable),
142 K(stats.wb_thresh),
143 K(dirty_thresh),
144 K(background_thresh),
145 K(stats.nr_dirtied),
146 K(stats.nr_written),
147 K(tot_bw),
148 stats.nr_dirty,
149 stats.nr_io,
150 stats.nr_more_io,
151 stats.nr_dirty_time,
152 !list_empty(&bdi->bdi_list), bdi->wb.state);
153
154 return 0;
155}
156DEFINE_SHOW_ATTRIBUTE(bdi_debug_stats);
157
158static void wb_stats_show(struct seq_file *m, struct bdi_writeback *wb,
159 struct wb_stats *stats)
160{
161
162 seq_printf(m,
163 "WbCgIno: %10lu\n"
164 "WbWriteback: %10lu kB\n"
165 "WbReclaimable: %10lu kB\n"
166 "WbDirtyThresh: %10lu kB\n"
167 "WbDirtied: %10lu kB\n"
168 "WbWritten: %10lu kB\n"
169 "WbWriteBandwidth: %10lu kBps\n"
170 "b_dirty: %10lu\n"
171 "b_io: %10lu\n"
172 "b_more_io: %10lu\n"
173 "b_dirty_time: %10lu\n"
174 "state: %10lx\n\n",
175#ifdef CONFIG_CGROUP_WRITEBACK
176 cgroup_ino(wb->memcg_css->cgroup),
177#else
178 1ul,
179#endif
180 K(stats->nr_writeback),
181 K(stats->nr_reclaimable),
182 K(stats->wb_thresh),
183 K(stats->nr_dirtied),
184 K(stats->nr_written),
185 K(wb->avg_write_bandwidth),
186 stats->nr_dirty,
187 stats->nr_io,
188 stats->nr_more_io,
189 stats->nr_dirty_time,
190 wb->state);
191}
192
193static int cgwb_debug_stats_show(struct seq_file *m, void *v)
194{
195 struct backing_dev_info *bdi = m->private;
196 unsigned long background_thresh;
197 unsigned long dirty_thresh;
198 struct bdi_writeback *wb;
199
200 global_dirty_limits(&background_thresh, &dirty_thresh);
201
202 rcu_read_lock();
203 list_for_each_entry_rcu(wb, &bdi->wb_list, bdi_node) {
204 struct wb_stats stats = { .dirty_thresh = dirty_thresh };
205
206 if (!wb_tryget(wb))
207 continue;
208
209 collect_wb_stats(&stats, wb);
210
211 /*
212 * Calculate thresh of wb in writeback cgroup which is min of
213 * thresh in global domain and thresh in cgroup domain. Drop
214 * rcu lock because cgwb_calc_thresh may sleep in
215 * cgroup_rstat_flush. We can do so here because we have a ref.
216 */
217 if (mem_cgroup_wb_domain(wb)) {
218 rcu_read_unlock();
219 stats.wb_thresh = min(stats.wb_thresh, cgwb_calc_thresh(wb));
220 rcu_read_lock();
221 }
222
223 wb_stats_show(m, wb, &stats);
224
225 wb_put(wb);
226 }
227 rcu_read_unlock();
228
229 return 0;
230}
231DEFINE_SHOW_ATTRIBUTE(cgwb_debug_stats);
232
233static void bdi_debug_register(struct backing_dev_info *bdi, const char *name)
234{
235 bdi->debug_dir = debugfs_create_dir(name, bdi_debug_root);
236
237 debugfs_create_file("stats", 0444, bdi->debug_dir, bdi,
238 &bdi_debug_stats_fops);
239 debugfs_create_file("wb_stats", 0444, bdi->debug_dir, bdi,
240 &cgwb_debug_stats_fops);
241}
242
243static void bdi_debug_unregister(struct backing_dev_info *bdi)
244{
245 debugfs_remove_recursive(bdi->debug_dir);
246}
247#else /* CONFIG_DEBUG_FS */
248static inline void bdi_debug_init(void)
249{
250}
251static inline void bdi_debug_register(struct backing_dev_info *bdi,
252 const char *name)
253{
254}
255static inline void bdi_debug_unregister(struct backing_dev_info *bdi)
256{
257}
258#endif /* CONFIG_DEBUG_FS */
259
260static ssize_t read_ahead_kb_store(struct device *dev,
261 struct device_attribute *attr,
262 const char *buf, size_t count)
263{
264 struct backing_dev_info *bdi = dev_get_drvdata(dev);
265 unsigned long read_ahead_kb;
266 ssize_t ret;
267
268 ret = kstrtoul(buf, 10, &read_ahead_kb);
269 if (ret < 0)
270 return ret;
271
272 bdi->ra_pages = read_ahead_kb >> (PAGE_SHIFT - 10);
273
274 return count;
275}
276
277#define BDI_SHOW(name, expr) \
278static ssize_t name##_show(struct device *dev, \
279 struct device_attribute *attr, char *buf) \
280{ \
281 struct backing_dev_info *bdi = dev_get_drvdata(dev); \
282 \
283 return sysfs_emit(buf, "%lld\n", (long long)expr); \
284} \
285static DEVICE_ATTR_RW(name);
286
287BDI_SHOW(read_ahead_kb, K(bdi->ra_pages))
288
289static ssize_t min_ratio_store(struct device *dev,
290 struct device_attribute *attr, const char *buf, size_t count)
291{
292 struct backing_dev_info *bdi = dev_get_drvdata(dev);
293 unsigned int ratio;
294 ssize_t ret;
295
296 ret = kstrtouint(buf, 10, &ratio);
297 if (ret < 0)
298 return ret;
299
300 ret = bdi_set_min_ratio(bdi, ratio);
301 if (!ret)
302 ret = count;
303
304 return ret;
305}
306BDI_SHOW(min_ratio, bdi->min_ratio / BDI_RATIO_SCALE)
307
308static ssize_t min_ratio_fine_store(struct device *dev,
309 struct device_attribute *attr, const char *buf, size_t count)
310{
311 struct backing_dev_info *bdi = dev_get_drvdata(dev);
312 unsigned int ratio;
313 ssize_t ret;
314
315 ret = kstrtouint(buf, 10, &ratio);
316 if (ret < 0)
317 return ret;
318
319 ret = bdi_set_min_ratio_no_scale(bdi, ratio);
320 if (!ret)
321 ret = count;
322
323 return ret;
324}
325BDI_SHOW(min_ratio_fine, bdi->min_ratio)
326
327static ssize_t max_ratio_store(struct device *dev,
328 struct device_attribute *attr, const char *buf, size_t count)
329{
330 struct backing_dev_info *bdi = dev_get_drvdata(dev);
331 unsigned int ratio;
332 ssize_t ret;
333
334 ret = kstrtouint(buf, 10, &ratio);
335 if (ret < 0)
336 return ret;
337
338 ret = bdi_set_max_ratio(bdi, ratio);
339 if (!ret)
340 ret = count;
341
342 return ret;
343}
344BDI_SHOW(max_ratio, bdi->max_ratio / BDI_RATIO_SCALE)
345
346static ssize_t max_ratio_fine_store(struct device *dev,
347 struct device_attribute *attr, const char *buf, size_t count)
348{
349 struct backing_dev_info *bdi = dev_get_drvdata(dev);
350 unsigned int ratio;
351 ssize_t ret;
352
353 ret = kstrtouint(buf, 10, &ratio);
354 if (ret < 0)
355 return ret;
356
357 ret = bdi_set_max_ratio_no_scale(bdi, ratio);
358 if (!ret)
359 ret = count;
360
361 return ret;
362}
363BDI_SHOW(max_ratio_fine, bdi->max_ratio)
364
365static ssize_t min_bytes_show(struct device *dev,
366 struct device_attribute *attr,
367 char *buf)
368{
369 struct backing_dev_info *bdi = dev_get_drvdata(dev);
370
371 return sysfs_emit(buf, "%llu\n", bdi_get_min_bytes(bdi));
372}
373
374static ssize_t min_bytes_store(struct device *dev,
375 struct device_attribute *attr, const char *buf, size_t count)
376{
377 struct backing_dev_info *bdi = dev_get_drvdata(dev);
378 u64 bytes;
379 ssize_t ret;
380
381 ret = kstrtoull(buf, 10, &bytes);
382 if (ret < 0)
383 return ret;
384
385 ret = bdi_set_min_bytes(bdi, bytes);
386 if (!ret)
387 ret = count;
388
389 return ret;
390}
391static DEVICE_ATTR_RW(min_bytes);
392
393static ssize_t max_bytes_show(struct device *dev,
394 struct device_attribute *attr,
395 char *buf)
396{
397 struct backing_dev_info *bdi = dev_get_drvdata(dev);
398
399 return sysfs_emit(buf, "%llu\n", bdi_get_max_bytes(bdi));
400}
401
402static ssize_t max_bytes_store(struct device *dev,
403 struct device_attribute *attr, const char *buf, size_t count)
404{
405 struct backing_dev_info *bdi = dev_get_drvdata(dev);
406 u64 bytes;
407 ssize_t ret;
408
409 ret = kstrtoull(buf, 10, &bytes);
410 if (ret < 0)
411 return ret;
412
413 ret = bdi_set_max_bytes(bdi, bytes);
414 if (!ret)
415 ret = count;
416
417 return ret;
418}
419static DEVICE_ATTR_RW(max_bytes);
420
421static ssize_t stable_pages_required_show(struct device *dev,
422 struct device_attribute *attr,
423 char *buf)
424{
425 dev_warn_once(dev,
426 "the stable_pages_required attribute has been removed. Use the stable_writes queue attribute instead.\n");
427 return sysfs_emit(buf, "%d\n", 0);
428}
429static DEVICE_ATTR_RO(stable_pages_required);
430
431static ssize_t strict_limit_store(struct device *dev,
432 struct device_attribute *attr, const char *buf, size_t count)
433{
434 struct backing_dev_info *bdi = dev_get_drvdata(dev);
435 unsigned int strict_limit;
436 ssize_t ret;
437
438 ret = kstrtouint(buf, 10, &strict_limit);
439 if (ret < 0)
440 return ret;
441
442 ret = bdi_set_strict_limit(bdi, strict_limit);
443 if (!ret)
444 ret = count;
445
446 return ret;
447}
448
449static ssize_t strict_limit_show(struct device *dev,
450 struct device_attribute *attr, char *buf)
451{
452 struct backing_dev_info *bdi = dev_get_drvdata(dev);
453
454 return sysfs_emit(buf, "%d\n",
455 !!(bdi->capabilities & BDI_CAP_STRICTLIMIT));
456}
457static DEVICE_ATTR_RW(strict_limit);
458
459static struct attribute *bdi_dev_attrs[] = {
460 &dev_attr_read_ahead_kb.attr,
461 &dev_attr_min_ratio.attr,
462 &dev_attr_min_ratio_fine.attr,
463 &dev_attr_max_ratio.attr,
464 &dev_attr_max_ratio_fine.attr,
465 &dev_attr_min_bytes.attr,
466 &dev_attr_max_bytes.attr,
467 &dev_attr_stable_pages_required.attr,
468 &dev_attr_strict_limit.attr,
469 NULL,
470};
471ATTRIBUTE_GROUPS(bdi_dev);
472
473static const struct class bdi_class = {
474 .name = "bdi",
475 .dev_groups = bdi_dev_groups,
476};
477
478static __init int bdi_class_init(void)
479{
480 int ret;
481
482 ret = class_register(&bdi_class);
483 if (ret)
484 return ret;
485
486 bdi_debug_init();
487
488 return 0;
489}
490postcore_initcall(bdi_class_init);
491
492static int __init default_bdi_init(void)
493{
494 bdi_wq = alloc_workqueue("writeback", WQ_MEM_RECLAIM | WQ_UNBOUND |
495 WQ_SYSFS, 0);
496 if (!bdi_wq)
497 return -ENOMEM;
498 return 0;
499}
500subsys_initcall(default_bdi_init);
501
502static void wb_update_bandwidth_workfn(struct work_struct *work)
503{
504 struct bdi_writeback *wb = container_of(to_delayed_work(work),
505 struct bdi_writeback, bw_dwork);
506
507 wb_update_bandwidth(wb);
508}
509
510/*
511 * Initial write bandwidth: 100 MB/s
512 */
513#define INIT_BW (100 << (20 - PAGE_SHIFT))
514
515static int wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi,
516 gfp_t gfp)
517{
518 int err;
519
520 memset(wb, 0, sizeof(*wb));
521
522 wb->bdi = bdi;
523 wb->last_old_flush = jiffies;
524 INIT_LIST_HEAD(&wb->b_dirty);
525 INIT_LIST_HEAD(&wb->b_io);
526 INIT_LIST_HEAD(&wb->b_more_io);
527 INIT_LIST_HEAD(&wb->b_dirty_time);
528 spin_lock_init(&wb->list_lock);
529
530 atomic_set(&wb->writeback_inodes, 0);
531 wb->bw_time_stamp = jiffies;
532 wb->balanced_dirty_ratelimit = INIT_BW;
533 wb->dirty_ratelimit = INIT_BW;
534 wb->write_bandwidth = INIT_BW;
535 wb->avg_write_bandwidth = INIT_BW;
536
537 spin_lock_init(&wb->work_lock);
538 INIT_LIST_HEAD(&wb->work_list);
539 INIT_DELAYED_WORK(&wb->dwork, wb_workfn);
540 INIT_DELAYED_WORK(&wb->bw_dwork, wb_update_bandwidth_workfn);
541
542 err = fprop_local_init_percpu(&wb->completions, gfp);
543 if (err)
544 return err;
545
546 err = percpu_counter_init_many(wb->stat, 0, gfp, NR_WB_STAT_ITEMS);
547 if (err)
548 fprop_local_destroy_percpu(&wb->completions);
549
550 return err;
551}
552
553static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb);
554
555/*
556 * Remove bdi from the global list and shutdown any threads we have running
557 */
558static void wb_shutdown(struct bdi_writeback *wb)
559{
560 /* Make sure nobody queues further work */
561 spin_lock_irq(&wb->work_lock);
562 if (!test_and_clear_bit(WB_registered, &wb->state)) {
563 spin_unlock_irq(&wb->work_lock);
564 return;
565 }
566 spin_unlock_irq(&wb->work_lock);
567
568 cgwb_remove_from_bdi_list(wb);
569 /*
570 * Drain work list and shutdown the delayed_work. !WB_registered
571 * tells wb_workfn() that @wb is dying and its work_list needs to
572 * be drained no matter what.
573 */
574 mod_delayed_work(bdi_wq, &wb->dwork, 0);
575 flush_delayed_work(&wb->dwork);
576 WARN_ON(!list_empty(&wb->work_list));
577 flush_delayed_work(&wb->bw_dwork);
578}
579
580static void wb_exit(struct bdi_writeback *wb)
581{
582 WARN_ON(delayed_work_pending(&wb->dwork));
583 percpu_counter_destroy_many(wb->stat, NR_WB_STAT_ITEMS);
584 fprop_local_destroy_percpu(&wb->completions);
585}
586
587#ifdef CONFIG_CGROUP_WRITEBACK
588
589#include <linux/memcontrol.h>
590
591/*
592 * cgwb_lock protects bdi->cgwb_tree, blkcg->cgwb_list, offline_cgwbs and
593 * memcg->cgwb_list. bdi->cgwb_tree is also RCU protected.
594 */
595static DEFINE_SPINLOCK(cgwb_lock);
596static struct workqueue_struct *cgwb_release_wq;
597
598static LIST_HEAD(offline_cgwbs);
599static void cleanup_offline_cgwbs_workfn(struct work_struct *work);
600static DECLARE_WORK(cleanup_offline_cgwbs_work, cleanup_offline_cgwbs_workfn);
601
602static void cgwb_free_rcu(struct rcu_head *rcu_head)
603{
604 struct bdi_writeback *wb = container_of(rcu_head,
605 struct bdi_writeback, rcu);
606
607 percpu_ref_exit(&wb->refcnt);
608 kfree(wb);
609}
610
611static void cgwb_release_workfn(struct work_struct *work)
612{
613 struct bdi_writeback *wb = container_of(work, struct bdi_writeback,
614 release_work);
615 struct backing_dev_info *bdi = wb->bdi;
616
617 mutex_lock(&wb->bdi->cgwb_release_mutex);
618 wb_shutdown(wb);
619
620 css_put(wb->memcg_css);
621 css_put(wb->blkcg_css);
622 mutex_unlock(&wb->bdi->cgwb_release_mutex);
623
624 /* triggers blkg destruction if no online users left */
625 blkcg_unpin_online(wb->blkcg_css);
626
627 fprop_local_destroy_percpu(&wb->memcg_completions);
628
629 spin_lock_irq(&cgwb_lock);
630 list_del(&wb->offline_node);
631 spin_unlock_irq(&cgwb_lock);
632
633 wb_exit(wb);
634 bdi_put(bdi);
635 WARN_ON_ONCE(!list_empty(&wb->b_attached));
636 call_rcu(&wb->rcu, cgwb_free_rcu);
637}
638
639static void cgwb_release(struct percpu_ref *refcnt)
640{
641 struct bdi_writeback *wb = container_of(refcnt, struct bdi_writeback,
642 refcnt);
643 queue_work(cgwb_release_wq, &wb->release_work);
644}
645
646static void cgwb_kill(struct bdi_writeback *wb)
647{
648 lockdep_assert_held(&cgwb_lock);
649
650 WARN_ON(!radix_tree_delete(&wb->bdi->cgwb_tree, wb->memcg_css->id));
651 list_del(&wb->memcg_node);
652 list_del(&wb->blkcg_node);
653 list_add(&wb->offline_node, &offline_cgwbs);
654 percpu_ref_kill(&wb->refcnt);
655}
656
657static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb)
658{
659 spin_lock_irq(&cgwb_lock);
660 list_del_rcu(&wb->bdi_node);
661 spin_unlock_irq(&cgwb_lock);
662}
663
664static int cgwb_create(struct backing_dev_info *bdi,
665 struct cgroup_subsys_state *memcg_css, gfp_t gfp)
666{
667 struct mem_cgroup *memcg;
668 struct cgroup_subsys_state *blkcg_css;
669 struct list_head *memcg_cgwb_list, *blkcg_cgwb_list;
670 struct bdi_writeback *wb;
671 unsigned long flags;
672 int ret = 0;
673
674 memcg = mem_cgroup_from_css(memcg_css);
675 blkcg_css = cgroup_get_e_css(memcg_css->cgroup, &io_cgrp_subsys);
676 memcg_cgwb_list = &memcg->cgwb_list;
677 blkcg_cgwb_list = blkcg_get_cgwb_list(blkcg_css);
678
679 /* look up again under lock and discard on blkcg mismatch */
680 spin_lock_irqsave(&cgwb_lock, flags);
681 wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id);
682 if (wb && wb->blkcg_css != blkcg_css) {
683 cgwb_kill(wb);
684 wb = NULL;
685 }
686 spin_unlock_irqrestore(&cgwb_lock, flags);
687 if (wb)
688 goto out_put;
689
690 /* need to create a new one */
691 wb = kmalloc(sizeof(*wb), gfp);
692 if (!wb) {
693 ret = -ENOMEM;
694 goto out_put;
695 }
696
697 ret = wb_init(wb, bdi, gfp);
698 if (ret)
699 goto err_free;
700
701 ret = percpu_ref_init(&wb->refcnt, cgwb_release, 0, gfp);
702 if (ret)
703 goto err_wb_exit;
704
705 ret = fprop_local_init_percpu(&wb->memcg_completions, gfp);
706 if (ret)
707 goto err_ref_exit;
708
709 wb->memcg_css = memcg_css;
710 wb->blkcg_css = blkcg_css;
711 INIT_LIST_HEAD(&wb->b_attached);
712 INIT_WORK(&wb->release_work, cgwb_release_workfn);
713 set_bit(WB_registered, &wb->state);
714 bdi_get(bdi);
715
716 /*
717 * The root wb determines the registered state of the whole bdi and
718 * memcg_cgwb_list and blkcg_cgwb_list's next pointers indicate
719 * whether they're still online. Don't link @wb if any is dead.
720 * See wb_memcg_offline() and wb_blkcg_offline().
721 */
722 ret = -ENODEV;
723 spin_lock_irqsave(&cgwb_lock, flags);
724 if (test_bit(WB_registered, &bdi->wb.state) &&
725 blkcg_cgwb_list->next && memcg_cgwb_list->next) {
726 /* we might have raced another instance of this function */
727 ret = radix_tree_insert(&bdi->cgwb_tree, memcg_css->id, wb);
728 if (!ret) {
729 list_add_tail_rcu(&wb->bdi_node, &bdi->wb_list);
730 list_add(&wb->memcg_node, memcg_cgwb_list);
731 list_add(&wb->blkcg_node, blkcg_cgwb_list);
732 blkcg_pin_online(blkcg_css);
733 css_get(memcg_css);
734 css_get(blkcg_css);
735 }
736 }
737 spin_unlock_irqrestore(&cgwb_lock, flags);
738 if (ret) {
739 if (ret == -EEXIST)
740 ret = 0;
741 goto err_fprop_exit;
742 }
743 goto out_put;
744
745err_fprop_exit:
746 bdi_put(bdi);
747 fprop_local_destroy_percpu(&wb->memcg_completions);
748err_ref_exit:
749 percpu_ref_exit(&wb->refcnt);
750err_wb_exit:
751 wb_exit(wb);
752err_free:
753 kfree(wb);
754out_put:
755 css_put(blkcg_css);
756 return ret;
757}
758
759/**
760 * wb_get_lookup - get wb for a given memcg
761 * @bdi: target bdi
762 * @memcg_css: cgroup_subsys_state of the target memcg (must have positive ref)
763 *
764 * Try to get the wb for @memcg_css on @bdi. The returned wb has its
765 * refcount incremented.
766 *
767 * This function uses css_get() on @memcg_css and thus expects its refcnt
768 * to be positive on invocation. IOW, rcu_read_lock() protection on
769 * @memcg_css isn't enough. try_get it before calling this function.
770 *
771 * A wb is keyed by its associated memcg. As blkcg implicitly enables
772 * memcg on the default hierarchy, memcg association is guaranteed to be
773 * more specific (equal or descendant to the associated blkcg) and thus can
774 * identify both the memcg and blkcg associations.
775 *
776 * Because the blkcg associated with a memcg may change as blkcg is enabled
777 * and disabled closer to root in the hierarchy, each wb keeps track of
778 * both the memcg and blkcg associated with it and verifies the blkcg on
779 * each lookup. On mismatch, the existing wb is discarded and a new one is
780 * created.
781 */
782struct bdi_writeback *wb_get_lookup(struct backing_dev_info *bdi,
783 struct cgroup_subsys_state *memcg_css)
784{
785 struct bdi_writeback *wb;
786
787 if (!memcg_css->parent)
788 return &bdi->wb;
789
790 rcu_read_lock();
791 wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id);
792 if (wb) {
793 struct cgroup_subsys_state *blkcg_css;
794
795 /* see whether the blkcg association has changed */
796 blkcg_css = cgroup_get_e_css(memcg_css->cgroup, &io_cgrp_subsys);
797 if (unlikely(wb->blkcg_css != blkcg_css || !wb_tryget(wb)))
798 wb = NULL;
799 css_put(blkcg_css);
800 }
801 rcu_read_unlock();
802
803 return wb;
804}
805
806/**
807 * wb_get_create - get wb for a given memcg, create if necessary
808 * @bdi: target bdi
809 * @memcg_css: cgroup_subsys_state of the target memcg (must have positive ref)
810 * @gfp: allocation mask to use
811 *
812 * Try to get the wb for @memcg_css on @bdi. If it doesn't exist, try to
813 * create one. See wb_get_lookup() for more details.
814 */
815struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi,
816 struct cgroup_subsys_state *memcg_css,
817 gfp_t gfp)
818{
819 struct bdi_writeback *wb;
820
821 might_alloc(gfp);
822
823 do {
824 wb = wb_get_lookup(bdi, memcg_css);
825 } while (!wb && !cgwb_create(bdi, memcg_css, gfp));
826
827 return wb;
828}
829
830static int cgwb_bdi_init(struct backing_dev_info *bdi)
831{
832 int ret;
833
834 INIT_RADIX_TREE(&bdi->cgwb_tree, GFP_ATOMIC);
835 mutex_init(&bdi->cgwb_release_mutex);
836 init_rwsem(&bdi->wb_switch_rwsem);
837
838 ret = wb_init(&bdi->wb, bdi, GFP_KERNEL);
839 if (!ret) {
840 bdi->wb.memcg_css = &root_mem_cgroup->css;
841 bdi->wb.blkcg_css = blkcg_root_css;
842 }
843 return ret;
844}
845
846static void cgwb_bdi_unregister(struct backing_dev_info *bdi)
847{
848 struct radix_tree_iter iter;
849 void **slot;
850 struct bdi_writeback *wb;
851
852 WARN_ON(test_bit(WB_registered, &bdi->wb.state));
853
854 spin_lock_irq(&cgwb_lock);
855 radix_tree_for_each_slot(slot, &bdi->cgwb_tree, &iter, 0)
856 cgwb_kill(*slot);
857 spin_unlock_irq(&cgwb_lock);
858
859 mutex_lock(&bdi->cgwb_release_mutex);
860 spin_lock_irq(&cgwb_lock);
861 while (!list_empty(&bdi->wb_list)) {
862 wb = list_first_entry(&bdi->wb_list, struct bdi_writeback,
863 bdi_node);
864 spin_unlock_irq(&cgwb_lock);
865 wb_shutdown(wb);
866 spin_lock_irq(&cgwb_lock);
867 }
868 spin_unlock_irq(&cgwb_lock);
869 mutex_unlock(&bdi->cgwb_release_mutex);
870}
871
872/*
873 * cleanup_offline_cgwbs_workfn - try to release dying cgwbs
874 *
875 * Try to release dying cgwbs by switching attached inodes to the nearest
876 * living ancestor's writeback. Processed wbs are placed at the end
877 * of the list to guarantee the forward progress.
878 */
879static void cleanup_offline_cgwbs_workfn(struct work_struct *work)
880{
881 struct bdi_writeback *wb;
882 LIST_HEAD(processed);
883
884 spin_lock_irq(&cgwb_lock);
885
886 while (!list_empty(&offline_cgwbs)) {
887 wb = list_first_entry(&offline_cgwbs, struct bdi_writeback,
888 offline_node);
889 list_move(&wb->offline_node, &processed);
890
891 /*
892 * If wb is dirty, cleaning up the writeback by switching
893 * attached inodes will result in an effective removal of any
894 * bandwidth restrictions, which isn't the goal. Instead,
895 * it can be postponed until the next time, when all io
896 * will be likely completed. If in the meantime some inodes
897 * will get re-dirtied, they should be eventually switched to
898 * a new cgwb.
899 */
900 if (wb_has_dirty_io(wb))
901 continue;
902
903 if (!wb_tryget(wb))
904 continue;
905
906 spin_unlock_irq(&cgwb_lock);
907 while (cleanup_offline_cgwb(wb))
908 cond_resched();
909 spin_lock_irq(&cgwb_lock);
910
911 wb_put(wb);
912 }
913
914 if (!list_empty(&processed))
915 list_splice_tail(&processed, &offline_cgwbs);
916
917 spin_unlock_irq(&cgwb_lock);
918}
919
920/**
921 * wb_memcg_offline - kill all wb's associated with a memcg being offlined
922 * @memcg: memcg being offlined
923 *
924 * Also prevents creation of any new wb's associated with @memcg.
925 */
926void wb_memcg_offline(struct mem_cgroup *memcg)
927{
928 struct list_head *memcg_cgwb_list = &memcg->cgwb_list;
929 struct bdi_writeback *wb, *next;
930
931 spin_lock_irq(&cgwb_lock);
932 list_for_each_entry_safe(wb, next, memcg_cgwb_list, memcg_node)
933 cgwb_kill(wb);
934 memcg_cgwb_list->next = NULL; /* prevent new wb's */
935 spin_unlock_irq(&cgwb_lock);
936
937 queue_work(system_unbound_wq, &cleanup_offline_cgwbs_work);
938}
939
940/**
941 * wb_blkcg_offline - kill all wb's associated with a blkcg being offlined
942 * @css: blkcg being offlined
943 *
944 * Also prevents creation of any new wb's associated with @blkcg.
945 */
946void wb_blkcg_offline(struct cgroup_subsys_state *css)
947{
948 struct bdi_writeback *wb, *next;
949 struct list_head *list = blkcg_get_cgwb_list(css);
950
951 spin_lock_irq(&cgwb_lock);
952 list_for_each_entry_safe(wb, next, list, blkcg_node)
953 cgwb_kill(wb);
954 list->next = NULL; /* prevent new wb's */
955 spin_unlock_irq(&cgwb_lock);
956}
957
958static void cgwb_bdi_register(struct backing_dev_info *bdi)
959{
960 spin_lock_irq(&cgwb_lock);
961 list_add_tail_rcu(&bdi->wb.bdi_node, &bdi->wb_list);
962 spin_unlock_irq(&cgwb_lock);
963}
964
965static int __init cgwb_init(void)
966{
967 /*
968 * There can be many concurrent release work items overwhelming
969 * system_wq. Put them in a separate wq and limit concurrency.
970 * There's no point in executing many of these in parallel.
971 */
972 cgwb_release_wq = alloc_workqueue("cgwb_release", 0, 1);
973 if (!cgwb_release_wq)
974 return -ENOMEM;
975
976 return 0;
977}
978subsys_initcall(cgwb_init);
979
980#else /* CONFIG_CGROUP_WRITEBACK */
981
982static int cgwb_bdi_init(struct backing_dev_info *bdi)
983{
984 return wb_init(&bdi->wb, bdi, GFP_KERNEL);
985}
986
987static void cgwb_bdi_unregister(struct backing_dev_info *bdi) { }
988
989static void cgwb_bdi_register(struct backing_dev_info *bdi)
990{
991 list_add_tail_rcu(&bdi->wb.bdi_node, &bdi->wb_list);
992}
993
994static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb)
995{
996 list_del_rcu(&wb->bdi_node);
997}
998
999#endif /* CONFIG_CGROUP_WRITEBACK */
1000
1001int bdi_init(struct backing_dev_info *bdi)
1002{
1003 bdi->dev = NULL;
1004
1005 kref_init(&bdi->refcnt);
1006 bdi->min_ratio = 0;
1007 bdi->max_ratio = 100 * BDI_RATIO_SCALE;
1008 bdi->max_prop_frac = FPROP_FRAC_BASE;
1009 INIT_LIST_HEAD(&bdi->bdi_list);
1010 INIT_LIST_HEAD(&bdi->wb_list);
1011 init_waitqueue_head(&bdi->wb_waitq);
1012 bdi->last_bdp_sleep = jiffies;
1013
1014 return cgwb_bdi_init(bdi);
1015}
1016
1017struct backing_dev_info *bdi_alloc(int node_id)
1018{
1019 struct backing_dev_info *bdi;
1020
1021 bdi = kzalloc_node(sizeof(*bdi), GFP_KERNEL, node_id);
1022 if (!bdi)
1023 return NULL;
1024
1025 if (bdi_init(bdi)) {
1026 kfree(bdi);
1027 return NULL;
1028 }
1029 bdi->capabilities = BDI_CAP_WRITEBACK | BDI_CAP_WRITEBACK_ACCT;
1030 bdi->ra_pages = VM_READAHEAD_PAGES;
1031 bdi->io_pages = VM_READAHEAD_PAGES;
1032 timer_setup(&bdi->laptop_mode_wb_timer, laptop_mode_timer_fn, 0);
1033 return bdi;
1034}
1035EXPORT_SYMBOL(bdi_alloc);
1036
1037static struct rb_node **bdi_lookup_rb_node(u64 id, struct rb_node **parentp)
1038{
1039 struct rb_node **p = &bdi_tree.rb_node;
1040 struct rb_node *parent = NULL;
1041 struct backing_dev_info *bdi;
1042
1043 lockdep_assert_held(&bdi_lock);
1044
1045 while (*p) {
1046 parent = *p;
1047 bdi = rb_entry(parent, struct backing_dev_info, rb_node);
1048
1049 if (bdi->id > id)
1050 p = &(*p)->rb_left;
1051 else if (bdi->id < id)
1052 p = &(*p)->rb_right;
1053 else
1054 break;
1055 }
1056
1057 if (parentp)
1058 *parentp = parent;
1059 return p;
1060}
1061
1062/**
1063 * bdi_get_by_id - lookup and get bdi from its id
1064 * @id: bdi id to lookup
1065 *
1066 * Find bdi matching @id and get it. Returns NULL if the matching bdi
1067 * doesn't exist or is already unregistered.
1068 */
1069struct backing_dev_info *bdi_get_by_id(u64 id)
1070{
1071 struct backing_dev_info *bdi = NULL;
1072 struct rb_node **p;
1073
1074 spin_lock_bh(&bdi_lock);
1075 p = bdi_lookup_rb_node(id, NULL);
1076 if (*p) {
1077 bdi = rb_entry(*p, struct backing_dev_info, rb_node);
1078 bdi_get(bdi);
1079 }
1080 spin_unlock_bh(&bdi_lock);
1081
1082 return bdi;
1083}
1084
1085int bdi_register_va(struct backing_dev_info *bdi, const char *fmt, va_list args)
1086{
1087 struct device *dev;
1088 struct rb_node *parent, **p;
1089
1090 if (bdi->dev) /* The driver needs to use separate queues per device */
1091 return 0;
1092
1093 vsnprintf(bdi->dev_name, sizeof(bdi->dev_name), fmt, args);
1094 dev = device_create(&bdi_class, NULL, MKDEV(0, 0), bdi, bdi->dev_name);
1095 if (IS_ERR(dev))
1096 return PTR_ERR(dev);
1097
1098 cgwb_bdi_register(bdi);
1099 bdi->dev = dev;
1100
1101 bdi_debug_register(bdi, dev_name(dev));
1102 set_bit(WB_registered, &bdi->wb.state);
1103
1104 spin_lock_bh(&bdi_lock);
1105
1106 bdi->id = ++bdi_id_cursor;
1107
1108 p = bdi_lookup_rb_node(bdi->id, &parent);
1109 rb_link_node(&bdi->rb_node, parent, p);
1110 rb_insert_color(&bdi->rb_node, &bdi_tree);
1111
1112 list_add_tail_rcu(&bdi->bdi_list, &bdi_list);
1113
1114 spin_unlock_bh(&bdi_lock);
1115
1116 trace_writeback_bdi_register(bdi);
1117 return 0;
1118}
1119
1120int bdi_register(struct backing_dev_info *bdi, const char *fmt, ...)
1121{
1122 va_list args;
1123 int ret;
1124
1125 va_start(args, fmt);
1126 ret = bdi_register_va(bdi, fmt, args);
1127 va_end(args);
1128 return ret;
1129}
1130EXPORT_SYMBOL(bdi_register);
1131
1132void bdi_set_owner(struct backing_dev_info *bdi, struct device *owner)
1133{
1134 WARN_ON_ONCE(bdi->owner);
1135 bdi->owner = owner;
1136 get_device(owner);
1137}
1138
1139/*
1140 * Remove bdi from bdi_list, and ensure that it is no longer visible
1141 */
1142static void bdi_remove_from_list(struct backing_dev_info *bdi)
1143{
1144 spin_lock_bh(&bdi_lock);
1145 rb_erase(&bdi->rb_node, &bdi_tree);
1146 list_del_rcu(&bdi->bdi_list);
1147 spin_unlock_bh(&bdi_lock);
1148
1149 synchronize_rcu_expedited();
1150}
1151
1152void bdi_unregister(struct backing_dev_info *bdi)
1153{
1154 del_timer_sync(&bdi->laptop_mode_wb_timer);
1155
1156 /* make sure nobody finds us on the bdi_list anymore */
1157 bdi_remove_from_list(bdi);
1158 wb_shutdown(&bdi->wb);
1159 cgwb_bdi_unregister(bdi);
1160
1161 /*
1162 * If this BDI's min ratio has been set, use bdi_set_min_ratio() to
1163 * update the global bdi_min_ratio.
1164 */
1165 if (bdi->min_ratio)
1166 bdi_set_min_ratio(bdi, 0);
1167
1168 if (bdi->dev) {
1169 bdi_debug_unregister(bdi);
1170 device_unregister(bdi->dev);
1171 bdi->dev = NULL;
1172 }
1173
1174 if (bdi->owner) {
1175 put_device(bdi->owner);
1176 bdi->owner = NULL;
1177 }
1178}
1179EXPORT_SYMBOL(bdi_unregister);
1180
1181static void release_bdi(struct kref *ref)
1182{
1183 struct backing_dev_info *bdi =
1184 container_of(ref, struct backing_dev_info, refcnt);
1185
1186 WARN_ON_ONCE(test_bit(WB_registered, &bdi->wb.state));
1187 WARN_ON_ONCE(bdi->dev);
1188 wb_exit(&bdi->wb);
1189 kfree(bdi);
1190}
1191
1192void bdi_put(struct backing_dev_info *bdi)
1193{
1194 kref_put(&bdi->refcnt, release_bdi);
1195}
1196EXPORT_SYMBOL(bdi_put);
1197
1198struct backing_dev_info *inode_to_bdi(struct inode *inode)
1199{
1200 struct super_block *sb;
1201
1202 if (!inode)
1203 return &noop_backing_dev_info;
1204
1205 sb = inode->i_sb;
1206#ifdef CONFIG_BLOCK
1207 if (sb_is_blkdev_sb(sb))
1208 return I_BDEV(inode)->bd_disk->bdi;
1209#endif
1210 return sb->s_bdi;
1211}
1212EXPORT_SYMBOL(inode_to_bdi);
1213
1214const char *bdi_dev_name(struct backing_dev_info *bdi)
1215{
1216 if (!bdi || !bdi->dev)
1217 return bdi_unknown_name;
1218 return bdi->dev_name;
1219}
1220EXPORT_SYMBOL_GPL(bdi_dev_name);