projects/linux·blob assoc-array-fixes · refs

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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_state_read_once(inode) & 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 MB_TO_PAGES(100)
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
622 /* triggers blkg destruction if no online users left */
623 blkcg_unpin_online(wb->blkcg_css);
624
625 css_put(wb->blkcg_css);
626 mutex_unlock(&wb->bdi->cgwb_release_mutex);
627
628 fprop_local_destroy_percpu(&wb->memcg_completions);
629
630 spin_lock_irq(&cgwb_lock);
631 list_del(&wb->offline_node);
632 spin_unlock_irq(&cgwb_lock);
633
634 wb_exit(wb);
635 bdi_put(bdi);
636 WARN_ON_ONCE(!list_empty(&wb->b_attached));
637 WARN_ON_ONCE(work_pending(&wb->switch_work));
638 call_rcu(&wb->rcu, cgwb_free_rcu);
639}
640
641static void cgwb_release(struct percpu_ref *refcnt)
642{
643 struct bdi_writeback *wb = container_of(refcnt, struct bdi_writeback,
644 refcnt);
645 queue_work(cgwb_release_wq, &wb->release_work);
646}
647
648static void cgwb_kill(struct bdi_writeback *wb)
649{
650 lockdep_assert_held(&cgwb_lock);
651
652 WARN_ON(!radix_tree_delete(&wb->bdi->cgwb_tree, wb->memcg_css->id));
653 list_del(&wb->memcg_node);
654 list_del(&wb->blkcg_node);
655 list_add(&wb->offline_node, &offline_cgwbs);
656 percpu_ref_kill(&wb->refcnt);
657}
658
659static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb)
660{
661 spin_lock_irq(&cgwb_lock);
662 list_del_rcu(&wb->bdi_node);
663 spin_unlock_irq(&cgwb_lock);
664}
665
666static int cgwb_create(struct backing_dev_info *bdi,
667 struct cgroup_subsys_state *memcg_css, gfp_t gfp)
668{
669 struct mem_cgroup *memcg;
670 struct cgroup_subsys_state *blkcg_css;
671 struct list_head *memcg_cgwb_list, *blkcg_cgwb_list;
672 struct bdi_writeback *wb;
673 unsigned long flags;
674 int ret = 0;
675
676 memcg = mem_cgroup_from_css(memcg_css);
677 blkcg_css = cgroup_get_e_css(memcg_css->cgroup, &io_cgrp_subsys);
678 memcg_cgwb_list = &memcg->cgwb_list;
679 blkcg_cgwb_list = blkcg_get_cgwb_list(blkcg_css);
680
681 /* look up again under lock and discard on blkcg mismatch */
682 spin_lock_irqsave(&cgwb_lock, flags);
683 wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id);
684 if (wb && wb->blkcg_css != blkcg_css) {
685 cgwb_kill(wb);
686 wb = NULL;
687 }
688 spin_unlock_irqrestore(&cgwb_lock, flags);
689 if (wb)
690 goto out_put;
691
692 /* need to create a new one */
693 wb = kmalloc_obj(*wb, gfp);
694 if (!wb) {
695 ret = -ENOMEM;
696 goto out_put;
697 }
698
699 ret = wb_init(wb, bdi, gfp);
700 if (ret)
701 goto err_free;
702
703 ret = percpu_ref_init(&wb->refcnt, cgwb_release, 0, gfp);
704 if (ret)
705 goto err_wb_exit;
706
707 ret = fprop_local_init_percpu(&wb->memcg_completions, gfp);
708 if (ret)
709 goto err_ref_exit;
710
711 wb->memcg_css = memcg_css;
712 wb->blkcg_css = blkcg_css;
713 INIT_LIST_HEAD(&wb->b_attached);
714 INIT_WORK(&wb->switch_work, inode_switch_wbs_work_fn);
715 init_llist_head(&wb->switch_wbs_ctxs);
716 INIT_WORK(&wb->release_work, cgwb_release_workfn);
717 set_bit(WB_registered, &wb->state);
718 bdi_get(bdi);
719
720 /*
721 * The root wb determines the registered state of the whole bdi and
722 * memcg_cgwb_list and blkcg_cgwb_list's next pointers indicate
723 * whether they're still online. Don't link @wb if any is dead.
724 * See wb_memcg_offline() and wb_blkcg_offline().
725 */
726 ret = -ENODEV;
727 spin_lock_irqsave(&cgwb_lock, flags);
728 if (test_bit(WB_registered, &bdi->wb.state) &&
729 blkcg_cgwb_list->next && memcg_cgwb_list->next) {
730 /* we might have raced another instance of this function */
731 ret = radix_tree_insert(&bdi->cgwb_tree, memcg_css->id, wb);
732 if (!ret) {
733 list_add_tail_rcu(&wb->bdi_node, &bdi->wb_list);
734 list_add(&wb->memcg_node, memcg_cgwb_list);
735 list_add(&wb->blkcg_node, blkcg_cgwb_list);
736 blkcg_pin_online(blkcg_css);
737 css_get(memcg_css);
738 css_get(blkcg_css);
739 }
740 }
741 spin_unlock_irqrestore(&cgwb_lock, flags);
742 if (ret) {
743 if (ret == -EEXIST)
744 ret = 0;
745 goto err_fprop_exit;
746 }
747 goto out_put;
748
749err_fprop_exit:
750 bdi_put(bdi);
751 fprop_local_destroy_percpu(&wb->memcg_completions);
752err_ref_exit:
753 percpu_ref_exit(&wb->refcnt);
754err_wb_exit:
755 wb_exit(wb);
756err_free:
757 kfree(wb);
758out_put:
759 css_put(blkcg_css);
760 return ret;
761}
762
763/**
764 * wb_get_lookup - get wb for a given memcg
765 * @bdi: target bdi
766 * @memcg_css: cgroup_subsys_state of the target memcg (must have positive ref)
767 *
768 * Try to get the wb for @memcg_css on @bdi. The returned wb has its
769 * refcount incremented.
770 *
771 * This function uses css_get() on @memcg_css and thus expects its refcnt
772 * to be positive on invocation. IOW, rcu_read_lock() protection on
773 * @memcg_css isn't enough. try_get it before calling this function.
774 *
775 * A wb is keyed by its associated memcg. As blkcg implicitly enables
776 * memcg on the default hierarchy, memcg association is guaranteed to be
777 * more specific (equal or descendant to the associated blkcg) and thus can
778 * identify both the memcg and blkcg associations.
779 *
780 * Because the blkcg associated with a memcg may change as blkcg is enabled
781 * and disabled closer to root in the hierarchy, each wb keeps track of
782 * both the memcg and blkcg associated with it and verifies the blkcg on
783 * each lookup. On mismatch, the existing wb is discarded and a new one is
784 * created.
785 */
786struct bdi_writeback *wb_get_lookup(struct backing_dev_info *bdi,
787 struct cgroup_subsys_state *memcg_css)
788{
789 struct bdi_writeback *wb;
790
791 if (!memcg_css->parent)
792 return &bdi->wb;
793
794 rcu_read_lock();
795 wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id);
796 if (wb) {
797 struct cgroup_subsys_state *blkcg_css;
798
799 /* see whether the blkcg association has changed */
800 blkcg_css = cgroup_get_e_css(memcg_css->cgroup, &io_cgrp_subsys);
801 if (unlikely(wb->blkcg_css != blkcg_css || !wb_tryget(wb)))
802 wb = NULL;
803 css_put(blkcg_css);
804 }
805 rcu_read_unlock();
806
807 return wb;
808}
809
810/**
811 * wb_get_create - get wb for a given memcg, create if necessary
812 * @bdi: target bdi
813 * @memcg_css: cgroup_subsys_state of the target memcg (must have positive ref)
814 * @gfp: allocation mask to use
815 *
816 * Try to get the wb for @memcg_css on @bdi. If it doesn't exist, try to
817 * create one. See wb_get_lookup() for more details.
818 */
819struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi,
820 struct cgroup_subsys_state *memcg_css,
821 gfp_t gfp)
822{
823 struct bdi_writeback *wb;
824
825 might_alloc(gfp);
826
827 do {
828 wb = wb_get_lookup(bdi, memcg_css);
829 } while (!wb && !cgwb_create(bdi, memcg_css, gfp));
830
831 return wb;
832}
833
834static int cgwb_bdi_init(struct backing_dev_info *bdi)
835{
836 int ret;
837
838 INIT_RADIX_TREE(&bdi->cgwb_tree, GFP_ATOMIC);
839 mutex_init(&bdi->cgwb_release_mutex);
840 init_rwsem(&bdi->wb_switch_rwsem);
841
842 ret = wb_init(&bdi->wb, bdi, GFP_KERNEL);
843 if (!ret) {
844 bdi->wb.memcg_css = &root_mem_cgroup->css;
845 bdi->wb.blkcg_css = blkcg_root_css;
846 INIT_WORK(&bdi->wb.switch_work, inode_switch_wbs_work_fn);
847 init_llist_head(&bdi->wb.switch_wbs_ctxs);
848 }
849 return ret;
850}
851
852static void cgwb_bdi_unregister(struct backing_dev_info *bdi)
853{
854 struct radix_tree_iter iter;
855 void **slot;
856 struct bdi_writeback *wb;
857
858 WARN_ON(test_bit(WB_registered, &bdi->wb.state));
859
860 spin_lock_irq(&cgwb_lock);
861 radix_tree_for_each_slot(slot, &bdi->cgwb_tree, &iter, 0)
862 cgwb_kill(*slot);
863 spin_unlock_irq(&cgwb_lock);
864
865 mutex_lock(&bdi->cgwb_release_mutex);
866 spin_lock_irq(&cgwb_lock);
867 while (!list_empty(&bdi->wb_list)) {
868 wb = list_first_entry(&bdi->wb_list, struct bdi_writeback,
869 bdi_node);
870 spin_unlock_irq(&cgwb_lock);
871 wb_shutdown(wb);
872 spin_lock_irq(&cgwb_lock);
873 }
874 spin_unlock_irq(&cgwb_lock);
875 mutex_unlock(&bdi->cgwb_release_mutex);
876}
877
878/*
879 * cleanup_offline_cgwbs_workfn - try to release dying cgwbs
880 *
881 * Try to release dying cgwbs by switching attached inodes to the nearest
882 * living ancestor's writeback. Processed wbs are placed at the end
883 * of the list to guarantee the forward progress.
884 */
885static void cleanup_offline_cgwbs_workfn(struct work_struct *work)
886{
887 struct bdi_writeback *wb;
888 LIST_HEAD(processed);
889
890 spin_lock_irq(&cgwb_lock);
891
892 while (!list_empty(&offline_cgwbs)) {
893 wb = list_first_entry(&offline_cgwbs, struct bdi_writeback,
894 offline_node);
895 list_move(&wb->offline_node, &processed);
896
897 /*
898 * If wb is dirty, cleaning up the writeback by switching
899 * attached inodes will result in an effective removal of any
900 * bandwidth restrictions, which isn't the goal. Instead,
901 * it can be postponed until the next time, when all io
902 * will be likely completed. If in the meantime some inodes
903 * will get re-dirtied, they should be eventually switched to
904 * a new cgwb.
905 */
906 if (wb_has_dirty_io(wb))
907 continue;
908
909 if (!wb_tryget(wb))
910 continue;
911
912 spin_unlock_irq(&cgwb_lock);
913 do {
914 cond_resched_tasks_rcu_qs();
915 } while (cleanup_offline_cgwb(wb));
916 spin_lock_irq(&cgwb_lock);
917
918 wb_put(wb);
919 }
920
921 if (!list_empty(&processed))
922 list_splice_tail(&processed, &offline_cgwbs);
923
924 spin_unlock_irq(&cgwb_lock);
925}
926
927/**
928 * wb_memcg_offline - kill all wb's associated with a memcg being offlined
929 * @memcg: memcg being offlined
930 *
931 * Also prevents creation of any new wb's associated with @memcg.
932 */
933void wb_memcg_offline(struct mem_cgroup *memcg)
934{
935 struct list_head *memcg_cgwb_list = &memcg->cgwb_list;
936 struct bdi_writeback *wb, *next;
937
938 spin_lock_irq(&cgwb_lock);
939 list_for_each_entry_safe(wb, next, memcg_cgwb_list, memcg_node)
940 cgwb_kill(wb);
941 memcg_cgwb_list->next = NULL; /* prevent new wb's */
942 spin_unlock_irq(&cgwb_lock);
943
944 queue_work(system_dfl_wq, &cleanup_offline_cgwbs_work);
945}
946
947/**
948 * wb_blkcg_offline - kill all wb's associated with a blkcg being offlined
949 * @css: blkcg being offlined
950 *
951 * Also prevents creation of any new wb's associated with @blkcg.
952 */
953void wb_blkcg_offline(struct cgroup_subsys_state *css)
954{
955 struct bdi_writeback *wb, *next;
956 struct list_head *list = blkcg_get_cgwb_list(css);
957
958 spin_lock_irq(&cgwb_lock);
959 list_for_each_entry_safe(wb, next, list, blkcg_node)
960 cgwb_kill(wb);
961 list->next = NULL; /* prevent new wb's */
962 spin_unlock_irq(&cgwb_lock);
963}
964
965static void cgwb_bdi_register(struct backing_dev_info *bdi)
966{
967 spin_lock_irq(&cgwb_lock);
968 list_add_tail_rcu(&bdi->wb.bdi_node, &bdi->wb_list);
969 spin_unlock_irq(&cgwb_lock);
970}
971
972static int __init cgwb_init(void)
973{
974 /*
975 * There can be many concurrent release work items overwhelming
976 * system_percpu_wq. Put them in a separate wq and limit concurrency.
977 * There's no point in executing many of these in parallel.
978 */
979 cgwb_release_wq = alloc_workqueue("cgwb_release", WQ_PERCPU, 1);
980 if (!cgwb_release_wq)
981 return -ENOMEM;
982
983 return 0;
984}
985subsys_initcall(cgwb_init);
986
987#else /* CONFIG_CGROUP_WRITEBACK */
988
989static int cgwb_bdi_init(struct backing_dev_info *bdi)
990{
991 return wb_init(&bdi->wb, bdi, GFP_KERNEL);
992}
993
994static void cgwb_bdi_unregister(struct backing_dev_info *bdi) { }
995
996static void cgwb_bdi_register(struct backing_dev_info *bdi)
997{
998 list_add_tail_rcu(&bdi->wb.bdi_node, &bdi->wb_list);
999}
1000
1001static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb)
1002{
1003 list_del_rcu(&wb->bdi_node);
1004}
1005
1006#endif /* CONFIG_CGROUP_WRITEBACK */
1007
1008int bdi_init(struct backing_dev_info *bdi)
1009{
1010 bdi->dev = NULL;
1011
1012 kref_init(&bdi->refcnt);
1013 bdi->min_ratio = 0;
1014 bdi->max_ratio = 100 * BDI_RATIO_SCALE;
1015 bdi->max_prop_frac = FPROP_FRAC_BASE;
1016 INIT_LIST_HEAD(&bdi->bdi_list);
1017 INIT_LIST_HEAD(&bdi->wb_list);
1018 init_waitqueue_head(&bdi->wb_waitq);
1019 bdi->last_bdp_sleep = jiffies;
1020
1021 return cgwb_bdi_init(bdi);
1022}
1023
1024struct backing_dev_info *bdi_alloc(int node_id)
1025{
1026 struct backing_dev_info *bdi;
1027
1028 bdi = kzalloc_node(sizeof(*bdi), GFP_KERNEL, node_id);
1029 if (!bdi)
1030 return NULL;
1031
1032 if (bdi_init(bdi)) {
1033 kfree(bdi);
1034 return NULL;
1035 }
1036 bdi->capabilities = BDI_CAP_WRITEBACK;
1037 bdi->ra_pages = VM_READAHEAD_PAGES;
1038 bdi->io_pages = VM_READAHEAD_PAGES;
1039 return bdi;
1040}
1041EXPORT_SYMBOL(bdi_alloc);
1042
1043static struct rb_node **bdi_lookup_rb_node(u64 id, struct rb_node **parentp)
1044{
1045 struct rb_node **p = &bdi_tree.rb_node;
1046 struct rb_node *parent = NULL;
1047 struct backing_dev_info *bdi;
1048
1049 lockdep_assert_held(&bdi_lock);
1050
1051 while (*p) {
1052 parent = *p;
1053 bdi = rb_entry(parent, struct backing_dev_info, rb_node);
1054
1055 if (bdi->id > id)
1056 p = &(*p)->rb_left;
1057 else if (bdi->id < id)
1058 p = &(*p)->rb_right;
1059 else
1060 break;
1061 }
1062
1063 if (parentp)
1064 *parentp = parent;
1065 return p;
1066}
1067
1068/**
1069 * bdi_get_by_id - lookup and get bdi from its id
1070 * @id: bdi id to lookup
1071 *
1072 * Find bdi matching @id and get it. Returns NULL if the matching bdi
1073 * doesn't exist or is already unregistered.
1074 */
1075struct backing_dev_info *bdi_get_by_id(u64 id)
1076{
1077 struct backing_dev_info *bdi = NULL;
1078 struct rb_node **p;
1079
1080 spin_lock_bh(&bdi_lock);
1081 p = bdi_lookup_rb_node(id, NULL);
1082 if (*p) {
1083 bdi = rb_entry(*p, struct backing_dev_info, rb_node);
1084 bdi_get(bdi);
1085 }
1086 spin_unlock_bh(&bdi_lock);
1087
1088 return bdi;
1089}
1090
1091int bdi_register_va(struct backing_dev_info *bdi, const char *fmt, va_list args)
1092{
1093 struct device *dev;
1094 struct rb_node *parent, **p;
1095
1096 if (bdi->dev) /* The driver needs to use separate queues per device */
1097 return 0;
1098
1099 vsnprintf(bdi->dev_name, sizeof(bdi->dev_name), fmt, args);
1100 dev = device_create(&bdi_class, NULL, MKDEV(0, 0), bdi, bdi->dev_name);
1101 if (IS_ERR(dev))
1102 return PTR_ERR(dev);
1103
1104 cgwb_bdi_register(bdi);
1105 bdi->dev = dev;
1106
1107 bdi_debug_register(bdi, dev_name(dev));
1108 set_bit(WB_registered, &bdi->wb.state);
1109
1110 spin_lock_bh(&bdi_lock);
1111
1112 bdi->id = ++bdi_id_cursor;
1113
1114 p = bdi_lookup_rb_node(bdi->id, &parent);
1115 rb_link_node(&bdi->rb_node, parent, p);
1116 rb_insert_color(&bdi->rb_node, &bdi_tree);
1117
1118 list_add_tail_rcu(&bdi->bdi_list, &bdi_list);
1119
1120 spin_unlock_bh(&bdi_lock);
1121
1122 trace_writeback_bdi_register(bdi);
1123 return 0;
1124}
1125
1126int bdi_register(struct backing_dev_info *bdi, const char *fmt, ...)
1127{
1128 va_list args;
1129 int ret;
1130
1131 va_start(args, fmt);
1132 ret = bdi_register_va(bdi, fmt, args);
1133 va_end(args);
1134 return ret;
1135}
1136EXPORT_SYMBOL(bdi_register);
1137
1138void bdi_set_owner(struct backing_dev_info *bdi, struct device *owner)
1139{
1140 WARN_ON_ONCE(bdi->owner);
1141 bdi->owner = owner;
1142 get_device(owner);
1143}
1144
1145/*
1146 * Remove bdi from bdi_list, and ensure that it is no longer visible
1147 */
1148static void bdi_remove_from_list(struct backing_dev_info *bdi)
1149{
1150 spin_lock_bh(&bdi_lock);
1151 rb_erase(&bdi->rb_node, &bdi_tree);
1152 list_del_rcu(&bdi->bdi_list);
1153 spin_unlock_bh(&bdi_lock);
1154
1155 synchronize_rcu_expedited();
1156}
1157
1158void bdi_unregister(struct backing_dev_info *bdi)
1159{
1160 /* make sure nobody finds us on the bdi_list anymore */
1161 bdi_remove_from_list(bdi);
1162 wb_shutdown(&bdi->wb);
1163 cgwb_bdi_unregister(bdi);
1164
1165 /*
1166 * If this BDI's min ratio has been set, use bdi_set_min_ratio() to
1167 * update the global bdi_min_ratio.
1168 */
1169 if (bdi->min_ratio)
1170 bdi_set_min_ratio(bdi, 0);
1171
1172 if (bdi->dev) {
1173 bdi_debug_unregister(bdi);
1174 device_unregister(bdi->dev);
1175 bdi->dev = NULL;
1176 }
1177
1178 if (bdi->owner) {
1179 put_device(bdi->owner);
1180 bdi->owner = NULL;
1181 }
1182}
1183EXPORT_SYMBOL(bdi_unregister);
1184
1185static void release_bdi(struct kref *ref)
1186{
1187 struct backing_dev_info *bdi =
1188 container_of(ref, struct backing_dev_info, refcnt);
1189
1190 WARN_ON_ONCE(test_bit(WB_registered, &bdi->wb.state));
1191 WARN_ON_ONCE(bdi->dev);
1192 wb_exit(&bdi->wb);
1193 kfree(bdi);
1194}
1195
1196void bdi_put(struct backing_dev_info *bdi)
1197{
1198 kref_put(&bdi->refcnt, release_bdi);
1199}
1200EXPORT_SYMBOL(bdi_put);
1201
1202struct backing_dev_info *inode_to_bdi(struct inode *inode)
1203{
1204 struct super_block *sb;
1205
1206 if (!inode)
1207 return &noop_backing_dev_info;
1208
1209 sb = inode->i_sb;
1210#ifdef CONFIG_BLOCK
1211 if (sb_is_blkdev_sb(sb))
1212 return I_BDEV(inode)->bd_disk->bdi;
1213#endif
1214 return sb->s_bdi;
1215}
1216EXPORT_SYMBOL(inode_to_bdi);
1217
1218const char *bdi_dev_name(struct backing_dev_info *bdi)
1219{
1220 if (!bdi || !bdi->dev)
1221 return bdi_unknown_name;
1222 return bdi->dev_name;
1223}
1224EXPORT_SYMBOL_GPL(bdi_dev_name);