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