projects/linux·blob v4.13 · refs

1092 lines · 27.5 KiB

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}
103
104static int bdi_debug_stats_open(struct inode *inode, struct file *file)
105{
106 return single_open(file, bdi_debug_stats_show, inode->i_private);
107}
108
109static const struct file_operations bdi_debug_stats_fops = {
110 .open = bdi_debug_stats_open,
111 .read = seq_read,
112 .llseek = seq_lseek,
113 .release = single_release,
114};
115
116static void bdi_debug_register(struct backing_dev_info *bdi, const char *name)
117{
118 bdi->debug_dir = debugfs_create_dir(name, bdi_debug_root);
119 bdi->debug_stats = debugfs_create_file("stats", 0444, bdi->debug_dir,
120 bdi, &bdi_debug_stats_fops);
121}
122
123static void bdi_debug_unregister(struct backing_dev_info *bdi)
124{
125 debugfs_remove(bdi->debug_stats);
126 debugfs_remove(bdi->debug_dir);
127}
128#else
129static inline void bdi_debug_init(void)
130{
131}
132static inline void bdi_debug_register(struct backing_dev_info *bdi,
133 const char *name)
134{
135}
136static inline void bdi_debug_unregister(struct backing_dev_info *bdi)
137{
138}
139#endif
140
141static ssize_t read_ahead_kb_store(struct device *dev,
142 struct device_attribute *attr,
143 const char *buf, size_t count)
144{
145 struct backing_dev_info *bdi = dev_get_drvdata(dev);
146 unsigned long read_ahead_kb;
147 ssize_t ret;
148
149 ret = kstrtoul(buf, 10, &read_ahead_kb);
150 if (ret < 0)
151 return ret;
152
153 bdi->ra_pages = read_ahead_kb >> (PAGE_SHIFT - 10);
154
155 return count;
156}
157
158#define K(pages) ((pages) << (PAGE_SHIFT - 10))
159
160#define BDI_SHOW(name, expr) \
161static ssize_t name##_show(struct device *dev, \
162 struct device_attribute *attr, char *page) \
163{ \
164 struct backing_dev_info *bdi = dev_get_drvdata(dev); \
165 \
166 return snprintf(page, PAGE_SIZE-1, "%lld\n", (long long)expr); \
167} \
168static DEVICE_ATTR_RW(name);
169
170BDI_SHOW(read_ahead_kb, K(bdi->ra_pages))
171
172static ssize_t min_ratio_store(struct device *dev,
173 struct device_attribute *attr, const char *buf, size_t count)
174{
175 struct backing_dev_info *bdi = dev_get_drvdata(dev);
176 unsigned int ratio;
177 ssize_t ret;
178
179 ret = kstrtouint(buf, 10, &ratio);
180 if (ret < 0)
181 return ret;
182
183 ret = bdi_set_min_ratio(bdi, ratio);
184 if (!ret)
185 ret = count;
186
187 return ret;
188}
189BDI_SHOW(min_ratio, bdi->min_ratio)
190
191static ssize_t max_ratio_store(struct device *dev,
192 struct device_attribute *attr, const char *buf, size_t count)
193{
194 struct backing_dev_info *bdi = dev_get_drvdata(dev);
195 unsigned int ratio;
196 ssize_t ret;
197
198 ret = kstrtouint(buf, 10, &ratio);
199 if (ret < 0)
200 return ret;
201
202 ret = bdi_set_max_ratio(bdi, ratio);
203 if (!ret)
204 ret = count;
205
206 return ret;
207}
208BDI_SHOW(max_ratio, bdi->max_ratio)
209
210static ssize_t stable_pages_required_show(struct device *dev,
211 struct device_attribute *attr,
212 char *page)
213{
214 struct backing_dev_info *bdi = dev_get_drvdata(dev);
215
216 return snprintf(page, PAGE_SIZE-1, "%d\n",
217 bdi_cap_stable_pages_required(bdi) ? 1 : 0);
218}
219static DEVICE_ATTR_RO(stable_pages_required);
220
221static struct attribute *bdi_dev_attrs[] = {
222 &dev_attr_read_ahead_kb.attr,
223 &dev_attr_min_ratio.attr,
224 &dev_attr_max_ratio.attr,
225 &dev_attr_stable_pages_required.attr,
226 NULL,
227};
228ATTRIBUTE_GROUPS(bdi_dev);
229
230static __init int bdi_class_init(void)
231{
232 bdi_class = class_create(THIS_MODULE, "bdi");
233 if (IS_ERR(bdi_class))
234 return PTR_ERR(bdi_class);
235
236 bdi_class->dev_groups = bdi_dev_groups;
237 bdi_debug_init();
238
239 return 0;
240}
241postcore_initcall(bdi_class_init);
242
243static int bdi_init(struct backing_dev_info *bdi);
244
245static int __init default_bdi_init(void)
246{
247 int err;
248
249 bdi_wq = alloc_workqueue("writeback", WQ_MEM_RECLAIM | WQ_FREEZABLE |
250 WQ_UNBOUND | WQ_SYSFS, 0);
251 if (!bdi_wq)
252 return -ENOMEM;
253
254 err = bdi_init(&noop_backing_dev_info);
255
256 return err;
257}
258subsys_initcall(default_bdi_init);
259
260/*
261 * This function is used when the first inode for this wb is marked dirty. It
262 * wakes-up the corresponding bdi thread which should then take care of the
263 * periodic background write-out of dirty inodes. Since the write-out would
264 * starts only 'dirty_writeback_interval' centisecs from now anyway, we just
265 * set up a timer which wakes the bdi thread up later.
266 *
267 * Note, we wouldn't bother setting up the timer, but this function is on the
268 * fast-path (used by '__mark_inode_dirty()'), so we save few context switches
269 * by delaying the wake-up.
270 *
271 * We have to be careful not to postpone flush work if it is scheduled for
272 * earlier. Thus we use queue_delayed_work().
273 */
274void wb_wakeup_delayed(struct bdi_writeback *wb)
275{
276 unsigned long timeout;
277
278 timeout = msecs_to_jiffies(dirty_writeback_interval * 10);
279 spin_lock_bh(&wb->work_lock);
280 if (test_bit(WB_registered, &wb->state))
281 queue_delayed_work(bdi_wq, &wb->dwork, timeout);
282 spin_unlock_bh(&wb->work_lock);
283}
284
285/*
286 * Initial write bandwidth: 100 MB/s
287 */
288#define INIT_BW (100 << (20 - PAGE_SHIFT))
289
290static int wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi,
291 int blkcg_id, gfp_t gfp)
292{
293 int i, err;
294
295 memset(wb, 0, sizeof(*wb));
296
297 if (wb != &bdi->wb)
298 bdi_get(bdi);
299 wb->bdi = bdi;
300 wb->last_old_flush = jiffies;
301 INIT_LIST_HEAD(&wb->b_dirty);
302 INIT_LIST_HEAD(&wb->b_io);
303 INIT_LIST_HEAD(&wb->b_more_io);
304 INIT_LIST_HEAD(&wb->b_dirty_time);
305 spin_lock_init(&wb->list_lock);
306
307 wb->bw_time_stamp = jiffies;
308 wb->balanced_dirty_ratelimit = INIT_BW;
309 wb->dirty_ratelimit = INIT_BW;
310 wb->write_bandwidth = INIT_BW;
311 wb->avg_write_bandwidth = INIT_BW;
312
313 spin_lock_init(&wb->work_lock);
314 INIT_LIST_HEAD(&wb->work_list);
315 INIT_DELAYED_WORK(&wb->dwork, wb_workfn);
316 wb->dirty_sleep = jiffies;
317
318 wb->congested = wb_congested_get_create(bdi, blkcg_id, gfp);
319 if (!wb->congested) {
320 err = -ENOMEM;
321 goto out_put_bdi;
322 }
323
324 err = fprop_local_init_percpu(&wb->completions, gfp);
325 if (err)
326 goto out_put_cong;
327
328 for (i = 0; i < NR_WB_STAT_ITEMS; i++) {
329 err = percpu_counter_init(&wb->stat[i], 0, gfp);
330 if (err)
331 goto out_destroy_stat;
332 }
333
334 return 0;
335
336out_destroy_stat:
337 while (i--)
338 percpu_counter_destroy(&wb->stat[i]);
339 fprop_local_destroy_percpu(&wb->completions);
340out_put_cong:
341 wb_congested_put(wb->congested);
342out_put_bdi:
343 if (wb != &bdi->wb)
344 bdi_put(bdi);
345 return err;
346}
347
348static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb);
349
350/*
351 * Remove bdi from the global list and shutdown any threads we have running
352 */
353static void wb_shutdown(struct bdi_writeback *wb)
354{
355 /* Make sure nobody queues further work */
356 spin_lock_bh(&wb->work_lock);
357 if (!test_and_clear_bit(WB_registered, &wb->state)) {
358 spin_unlock_bh(&wb->work_lock);
359 /*
360 * Wait for wb shutdown to finish if someone else is just
361 * running wb_shutdown(). Otherwise we could proceed to wb /
362 * bdi destruction before wb_shutdown() is finished.
363 */
364 wait_on_bit(&wb->state, WB_shutting_down, TASK_UNINTERRUPTIBLE);
365 return;
366 }
367 set_bit(WB_shutting_down, &wb->state);
368 spin_unlock_bh(&wb->work_lock);
369
370 cgwb_remove_from_bdi_list(wb);
371 /*
372 * Drain work list and shutdown the delayed_work. !WB_registered
373 * tells wb_workfn() that @wb is dying and its work_list needs to
374 * be drained no matter what.
375 */
376 mod_delayed_work(bdi_wq, &wb->dwork, 0);
377 flush_delayed_work(&wb->dwork);
378 WARN_ON(!list_empty(&wb->work_list));
379 /*
380 * Make sure bit gets cleared after shutdown is finished. Matches with
381 * the barrier provided by test_and_clear_bit() above.
382 */
383 smp_wmb();
384 clear_bit(WB_shutting_down, &wb->state);
385}
386
387static void wb_exit(struct bdi_writeback *wb)
388{
389 int i;
390
391 WARN_ON(delayed_work_pending(&wb->dwork));
392
393 for (i = 0; i < NR_WB_STAT_ITEMS; i++)
394 percpu_counter_destroy(&wb->stat[i]);
395
396 fprop_local_destroy_percpu(&wb->completions);
397 wb_congested_put(wb->congested);
398 if (wb != &wb->bdi->wb)
399 bdi_put(wb->bdi);
400}
401
402#ifdef CONFIG_CGROUP_WRITEBACK
403
404#include <linux/memcontrol.h>
405
406/*
407 * cgwb_lock protects bdi->cgwb_tree, bdi->cgwb_congested_tree,
408 * blkcg->cgwb_list, and memcg->cgwb_list. bdi->cgwb_tree is also RCU
409 * protected.
410 */
411static DEFINE_SPINLOCK(cgwb_lock);
412
413/**
414 * wb_congested_get_create - get or create a wb_congested
415 * @bdi: associated bdi
416 * @blkcg_id: ID of the associated blkcg
417 * @gfp: allocation mask
418 *
419 * Look up the wb_congested for @blkcg_id on @bdi. If missing, create one.
420 * The returned wb_congested has its reference count incremented. Returns
421 * NULL on failure.
422 */
423struct bdi_writeback_congested *
424wb_congested_get_create(struct backing_dev_info *bdi, int blkcg_id, gfp_t gfp)
425{
426 struct bdi_writeback_congested *new_congested = NULL, *congested;
427 struct rb_node **node, *parent;
428 unsigned long flags;
429retry:
430 spin_lock_irqsave(&cgwb_lock, flags);
431
432 node = &bdi->cgwb_congested_tree.rb_node;
433 parent = NULL;
434
435 while (*node != NULL) {
436 parent = *node;
437 congested = rb_entry(parent, struct bdi_writeback_congested,
438 rb_node);
439 if (congested->blkcg_id < blkcg_id)
440 node = &parent->rb_left;
441 else if (congested->blkcg_id > blkcg_id)
442 node = &parent->rb_right;
443 else
444 goto found;
445 }
446
447 if (new_congested) {
448 /* !found and storage for new one already allocated, insert */
449 congested = new_congested;
450 new_congested = NULL;
451 rb_link_node(&congested->rb_node, parent, node);
452 rb_insert_color(&congested->rb_node, &bdi->cgwb_congested_tree);
453 goto found;
454 }
455
456 spin_unlock_irqrestore(&cgwb_lock, flags);
457
458 /* allocate storage for new one and retry */
459 new_congested = kzalloc(sizeof(*new_congested), gfp);
460 if (!new_congested)
461 return NULL;
462
463 atomic_set(&new_congested->refcnt, 0);
464 new_congested->__bdi = bdi;
465 new_congested->blkcg_id = blkcg_id;
466 goto retry;
467
468found:
469 atomic_inc(&congested->refcnt);
470 spin_unlock_irqrestore(&cgwb_lock, flags);
471 kfree(new_congested);
472 return congested;
473}
474
475/**
476 * wb_congested_put - put a wb_congested
477 * @congested: wb_congested to put
478 *
479 * Put @congested and destroy it if the refcnt reaches zero.
480 */
481void wb_congested_put(struct bdi_writeback_congested *congested)
482{
483 unsigned long flags;
484
485 local_irq_save(flags);
486 if (!atomic_dec_and_lock(&congested->refcnt, &cgwb_lock)) {
487 local_irq_restore(flags);
488 return;
489 }
490
491 /* bdi might already have been destroyed leaving @congested unlinked */
492 if (congested->__bdi) {
493 rb_erase(&congested->rb_node,
494 &congested->__bdi->cgwb_congested_tree);
495 congested->__bdi = NULL;
496 }
497
498 spin_unlock_irqrestore(&cgwb_lock, flags);
499 kfree(congested);
500}
501
502static void cgwb_release_workfn(struct work_struct *work)
503{
504 struct bdi_writeback *wb = container_of(work, struct bdi_writeback,
505 release_work);
506
507 wb_shutdown(wb);
508
509 css_put(wb->memcg_css);
510 css_put(wb->blkcg_css);
511
512 fprop_local_destroy_percpu(&wb->memcg_completions);
513 percpu_ref_exit(&wb->refcnt);
514 wb_exit(wb);
515 kfree_rcu(wb, rcu);
516}
517
518static void cgwb_release(struct percpu_ref *refcnt)
519{
520 struct bdi_writeback *wb = container_of(refcnt, struct bdi_writeback,
521 refcnt);
522 schedule_work(&wb->release_work);
523}
524
525static void cgwb_kill(struct bdi_writeback *wb)
526{
527 lockdep_assert_held(&cgwb_lock);
528
529 WARN_ON(!radix_tree_delete(&wb->bdi->cgwb_tree, wb->memcg_css->id));
530 list_del(&wb->memcg_node);
531 list_del(&wb->blkcg_node);
532 percpu_ref_kill(&wb->refcnt);
533}
534
535static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb)
536{
537 spin_lock_irq(&cgwb_lock);
538 list_del_rcu(&wb->bdi_node);
539 spin_unlock_irq(&cgwb_lock);
540}
541
542static int cgwb_create(struct backing_dev_info *bdi,
543 struct cgroup_subsys_state *memcg_css, gfp_t gfp)
544{
545 struct mem_cgroup *memcg;
546 struct cgroup_subsys_state *blkcg_css;
547 struct blkcg *blkcg;
548 struct list_head *memcg_cgwb_list, *blkcg_cgwb_list;
549 struct bdi_writeback *wb;
550 unsigned long flags;
551 int ret = 0;
552
553 memcg = mem_cgroup_from_css(memcg_css);
554 blkcg_css = cgroup_get_e_css(memcg_css->cgroup, &io_cgrp_subsys);
555 blkcg = css_to_blkcg(blkcg_css);
556 memcg_cgwb_list = mem_cgroup_cgwb_list(memcg);
557 blkcg_cgwb_list = &blkcg->cgwb_list;
558
559 /* look up again under lock and discard on blkcg mismatch */
560 spin_lock_irqsave(&cgwb_lock, flags);
561 wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id);
562 if (wb && wb->blkcg_css != blkcg_css) {
563 cgwb_kill(wb);
564 wb = NULL;
565 }
566 spin_unlock_irqrestore(&cgwb_lock, flags);
567 if (wb)
568 goto out_put;
569
570 /* need to create a new one */
571 wb = kmalloc(sizeof(*wb), gfp);
572 if (!wb)
573 return -ENOMEM;
574
575 ret = wb_init(wb, bdi, blkcg_css->id, gfp);
576 if (ret)
577 goto err_free;
578
579 ret = percpu_ref_init(&wb->refcnt, cgwb_release, 0, gfp);
580 if (ret)
581 goto err_wb_exit;
582
583 ret = fprop_local_init_percpu(&wb->memcg_completions, gfp);
584 if (ret)
585 goto err_ref_exit;
586
587 wb->memcg_css = memcg_css;
588 wb->blkcg_css = blkcg_css;
589 INIT_WORK(&wb->release_work, cgwb_release_workfn);
590 set_bit(WB_registered, &wb->state);
591
592 /*
593 * The root wb determines the registered state of the whole bdi and
594 * memcg_cgwb_list and blkcg_cgwb_list's next pointers indicate
595 * whether they're still online. Don't link @wb if any is dead.
596 * See wb_memcg_offline() and wb_blkcg_offline().
597 */
598 ret = -ENODEV;
599 spin_lock_irqsave(&cgwb_lock, flags);
600 if (test_bit(WB_registered, &bdi->wb.state) &&
601 blkcg_cgwb_list->next && memcg_cgwb_list->next) {
602 /* we might have raced another instance of this function */
603 ret = radix_tree_insert(&bdi->cgwb_tree, memcg_css->id, wb);
604 if (!ret) {
605 list_add_tail_rcu(&wb->bdi_node, &bdi->wb_list);
606 list_add(&wb->memcg_node, memcg_cgwb_list);
607 list_add(&wb->blkcg_node, blkcg_cgwb_list);
608 css_get(memcg_css);
609 css_get(blkcg_css);
610 }
611 }
612 spin_unlock_irqrestore(&cgwb_lock, flags);
613 if (ret) {
614 if (ret == -EEXIST)
615 ret = 0;
616 goto err_fprop_exit;
617 }
618 goto out_put;
619
620err_fprop_exit:
621 fprop_local_destroy_percpu(&wb->memcg_completions);
622err_ref_exit:
623 percpu_ref_exit(&wb->refcnt);
624err_wb_exit:
625 wb_exit(wb);
626err_free:
627 kfree(wb);
628out_put:
629 css_put(blkcg_css);
630 return ret;
631}
632
633/**
634 * wb_get_create - get wb for a given memcg, create if necessary
635 * @bdi: target bdi
636 * @memcg_css: cgroup_subsys_state of the target memcg (must have positive ref)
637 * @gfp: allocation mask to use
638 *
639 * Try to get the wb for @memcg_css on @bdi. If it doesn't exist, try to
640 * create one. The returned wb has its refcount incremented.
641 *
642 * This function uses css_get() on @memcg_css and thus expects its refcnt
643 * to be positive on invocation. IOW, rcu_read_lock() protection on
644 * @memcg_css isn't enough. try_get it before calling this function.
645 *
646 * A wb is keyed by its associated memcg. As blkcg implicitly enables
647 * memcg on the default hierarchy, memcg association is guaranteed to be
648 * more specific (equal or descendant to the associated blkcg) and thus can
649 * identify both the memcg and blkcg associations.
650 *
651 * Because the blkcg associated with a memcg may change as blkcg is enabled
652 * and disabled closer to root in the hierarchy, each wb keeps track of
653 * both the memcg and blkcg associated with it and verifies the blkcg on
654 * each lookup. On mismatch, the existing wb is discarded and a new one is
655 * created.
656 */
657struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi,
658 struct cgroup_subsys_state *memcg_css,
659 gfp_t gfp)
660{
661 struct bdi_writeback *wb;
662
663 might_sleep_if(gfpflags_allow_blocking(gfp));
664
665 if (!memcg_css->parent)
666 return &bdi->wb;
667
668 do {
669 rcu_read_lock();
670 wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id);
671 if (wb) {
672 struct cgroup_subsys_state *blkcg_css;
673
674 /* see whether the blkcg association has changed */
675 blkcg_css = cgroup_get_e_css(memcg_css->cgroup,
676 &io_cgrp_subsys);
677 if (unlikely(wb->blkcg_css != blkcg_css ||
678 !wb_tryget(wb)))
679 wb = NULL;
680 css_put(blkcg_css);
681 }
682 rcu_read_unlock();
683 } while (!wb && !cgwb_create(bdi, memcg_css, gfp));
684
685 return wb;
686}
687
688static int cgwb_bdi_init(struct backing_dev_info *bdi)
689{
690 int ret;
691
692 INIT_RADIX_TREE(&bdi->cgwb_tree, GFP_ATOMIC);
693 bdi->cgwb_congested_tree = RB_ROOT;
694
695 ret = wb_init(&bdi->wb, bdi, 1, GFP_KERNEL);
696 if (!ret) {
697 bdi->wb.memcg_css = &root_mem_cgroup->css;
698 bdi->wb.blkcg_css = blkcg_root_css;
699 }
700 return ret;
701}
702
703static void cgwb_bdi_unregister(struct backing_dev_info *bdi)
704{
705 struct radix_tree_iter iter;
706 void **slot;
707 struct bdi_writeback *wb;
708
709 WARN_ON(test_bit(WB_registered, &bdi->wb.state));
710
711 spin_lock_irq(&cgwb_lock);
712 radix_tree_for_each_slot(slot, &bdi->cgwb_tree, &iter, 0)
713 cgwb_kill(*slot);
714
715 while (!list_empty(&bdi->wb_list)) {
716 wb = list_first_entry(&bdi->wb_list, struct bdi_writeback,
717 bdi_node);
718 spin_unlock_irq(&cgwb_lock);
719 wb_shutdown(wb);
720 spin_lock_irq(&cgwb_lock);
721 }
722 spin_unlock_irq(&cgwb_lock);
723}
724
725/**
726 * wb_memcg_offline - kill all wb's associated with a memcg being offlined
727 * @memcg: memcg being offlined
728 *
729 * Also prevents creation of any new wb's associated with @memcg.
730 */
731void wb_memcg_offline(struct mem_cgroup *memcg)
732{
733 LIST_HEAD(to_destroy);
734 struct list_head *memcg_cgwb_list = mem_cgroup_cgwb_list(memcg);
735 struct bdi_writeback *wb, *next;
736
737 spin_lock_irq(&cgwb_lock);
738 list_for_each_entry_safe(wb, next, memcg_cgwb_list, memcg_node)
739 cgwb_kill(wb);
740 memcg_cgwb_list->next = NULL; /* prevent new wb's */
741 spin_unlock_irq(&cgwb_lock);
742}
743
744/**
745 * wb_blkcg_offline - kill all wb's associated with a blkcg being offlined
746 * @blkcg: blkcg being offlined
747 *
748 * Also prevents creation of any new wb's associated with @blkcg.
749 */
750void wb_blkcg_offline(struct blkcg *blkcg)
751{
752 LIST_HEAD(to_destroy);
753 struct bdi_writeback *wb, *next;
754
755 spin_lock_irq(&cgwb_lock);
756 list_for_each_entry_safe(wb, next, &blkcg->cgwb_list, blkcg_node)
757 cgwb_kill(wb);
758 blkcg->cgwb_list.next = NULL; /* prevent new wb's */
759 spin_unlock_irq(&cgwb_lock);
760}
761
762static void cgwb_bdi_exit(struct backing_dev_info *bdi)
763{
764 struct rb_node *rbn;
765
766 spin_lock_irq(&cgwb_lock);
767 while ((rbn = rb_first(&bdi->cgwb_congested_tree))) {
768 struct bdi_writeback_congested *congested =
769 rb_entry(rbn, struct bdi_writeback_congested, rb_node);
770
771 rb_erase(rbn, &bdi->cgwb_congested_tree);
772 congested->__bdi = NULL; /* mark @congested unlinked */
773 }
774 spin_unlock_irq(&cgwb_lock);
775}
776
777static void cgwb_bdi_register(struct backing_dev_info *bdi)
778{
779 spin_lock_irq(&cgwb_lock);
780 list_add_tail_rcu(&bdi->wb.bdi_node, &bdi->wb_list);
781 spin_unlock_irq(&cgwb_lock);
782}
783
784#else /* CONFIG_CGROUP_WRITEBACK */
785
786static int cgwb_bdi_init(struct backing_dev_info *bdi)
787{
788 int err;
789
790 bdi->wb_congested = kzalloc(sizeof(*bdi->wb_congested), GFP_KERNEL);
791 if (!bdi->wb_congested)
792 return -ENOMEM;
793
794 atomic_set(&bdi->wb_congested->refcnt, 1);
795
796 err = wb_init(&bdi->wb, bdi, 1, GFP_KERNEL);
797 if (err) {
798 wb_congested_put(bdi->wb_congested);
799 return err;
800 }
801 return 0;
802}
803
804static void cgwb_bdi_unregister(struct backing_dev_info *bdi) { }
805
806static void cgwb_bdi_exit(struct backing_dev_info *bdi)
807{
808 wb_congested_put(bdi->wb_congested);
809}
810
811static void cgwb_bdi_register(struct backing_dev_info *bdi)
812{
813 list_add_tail_rcu(&bdi->wb.bdi_node, &bdi->wb_list);
814}
815
816static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb)
817{
818 list_del_rcu(&wb->bdi_node);
819}
820
821#endif /* CONFIG_CGROUP_WRITEBACK */
822
823static int bdi_init(struct backing_dev_info *bdi)
824{
825 int ret;
826
827 bdi->dev = NULL;
828
829 kref_init(&bdi->refcnt);
830 bdi->min_ratio = 0;
831 bdi->max_ratio = 100;
832 bdi->max_prop_frac = FPROP_FRAC_BASE;
833 INIT_LIST_HEAD(&bdi->bdi_list);
834 INIT_LIST_HEAD(&bdi->wb_list);
835 init_waitqueue_head(&bdi->wb_waitq);
836
837 ret = cgwb_bdi_init(bdi);
838
839 return ret;
840}
841
842struct backing_dev_info *bdi_alloc_node(gfp_t gfp_mask, int node_id)
843{
844 struct backing_dev_info *bdi;
845
846 bdi = kmalloc_node(sizeof(struct backing_dev_info),
847 gfp_mask | __GFP_ZERO, node_id);
848 if (!bdi)
849 return NULL;
850
851 if (bdi_init(bdi)) {
852 kfree(bdi);
853 return NULL;
854 }
855 return bdi;
856}
857EXPORT_SYMBOL(bdi_alloc_node);
858
859int bdi_register_va(struct backing_dev_info *bdi, const char *fmt, va_list args)
860{
861 struct device *dev;
862
863 if (bdi->dev) /* The driver needs to use separate queues per device */
864 return 0;
865
866 dev = device_create_vargs(bdi_class, NULL, MKDEV(0, 0), bdi, fmt, args);
867 if (IS_ERR(dev))
868 return PTR_ERR(dev);
869
870 cgwb_bdi_register(bdi);
871 bdi->dev = dev;
872
873 bdi_debug_register(bdi, dev_name(dev));
874 set_bit(WB_registered, &bdi->wb.state);
875
876 spin_lock_bh(&bdi_lock);
877 list_add_tail_rcu(&bdi->bdi_list, &bdi_list);
878 spin_unlock_bh(&bdi_lock);
879
880 trace_writeback_bdi_register(bdi);
881 return 0;
882}
883EXPORT_SYMBOL(bdi_register_va);
884
885int bdi_register(struct backing_dev_info *bdi, const char *fmt, ...)
886{
887 va_list args;
888 int ret;
889
890 va_start(args, fmt);
891 ret = bdi_register_va(bdi, fmt, args);
892 va_end(args);
893 return ret;
894}
895EXPORT_SYMBOL(bdi_register);
896
897int bdi_register_owner(struct backing_dev_info *bdi, struct device *owner)
898{
899 int rc;
900
901 rc = bdi_register(bdi, "%u:%u", MAJOR(owner->devt), MINOR(owner->devt));
902 if (rc)
903 return rc;
904 /* Leaking owner reference... */
905 WARN_ON(bdi->owner);
906 bdi->owner = owner;
907 get_device(owner);
908 return 0;
909}
910EXPORT_SYMBOL(bdi_register_owner);
911
912/*
913 * Remove bdi from bdi_list, and ensure that it is no longer visible
914 */
915static void bdi_remove_from_list(struct backing_dev_info *bdi)
916{
917 spin_lock_bh(&bdi_lock);
918 list_del_rcu(&bdi->bdi_list);
919 spin_unlock_bh(&bdi_lock);
920
921 synchronize_rcu_expedited();
922}
923
924void bdi_unregister(struct backing_dev_info *bdi)
925{
926 /* make sure nobody finds us on the bdi_list anymore */
927 bdi_remove_from_list(bdi);
928 wb_shutdown(&bdi->wb);
929 cgwb_bdi_unregister(bdi);
930
931 if (bdi->dev) {
932 bdi_debug_unregister(bdi);
933 device_unregister(bdi->dev);
934 bdi->dev = NULL;
935 }
936
937 if (bdi->owner) {
938 put_device(bdi->owner);
939 bdi->owner = NULL;
940 }
941}
942
943static void release_bdi(struct kref *ref)
944{
945 struct backing_dev_info *bdi =
946 container_of(ref, struct backing_dev_info, refcnt);
947
948 if (test_bit(WB_registered, &bdi->wb.state))
949 bdi_unregister(bdi);
950 WARN_ON_ONCE(bdi->dev);
951 wb_exit(&bdi->wb);
952 cgwb_bdi_exit(bdi);
953 kfree(bdi);
954}
955
956void bdi_put(struct backing_dev_info *bdi)
957{
958 kref_put(&bdi->refcnt, release_bdi);
959}
960EXPORT_SYMBOL(bdi_put);
961
962static wait_queue_head_t congestion_wqh[2] = {
963 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]),
964 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1])
965 };
966static atomic_t nr_wb_congested[2];
967
968void clear_wb_congested(struct bdi_writeback_congested *congested, int sync)
969{
970 wait_queue_head_t *wqh = &congestion_wqh[sync];
971 enum wb_congested_state bit;
972
973 bit = sync ? WB_sync_congested : WB_async_congested;
974 if (test_and_clear_bit(bit, &congested->state))
975 atomic_dec(&nr_wb_congested[sync]);
976 smp_mb__after_atomic();
977 if (waitqueue_active(wqh))
978 wake_up(wqh);
979}
980EXPORT_SYMBOL(clear_wb_congested);
981
982void set_wb_congested(struct bdi_writeback_congested *congested, int sync)
983{
984 enum wb_congested_state bit;
985
986 bit = sync ? WB_sync_congested : WB_async_congested;
987 if (!test_and_set_bit(bit, &congested->state))
988 atomic_inc(&nr_wb_congested[sync]);
989}
990EXPORT_SYMBOL(set_wb_congested);
991
992/**
993 * congestion_wait - wait for a backing_dev to become uncongested
994 * @sync: SYNC or ASYNC IO
995 * @timeout: timeout in jiffies
996 *
997 * Waits for up to @timeout jiffies for a backing_dev (any backing_dev) to exit
998 * write congestion. If no backing_devs are congested then just wait for the
999 * next write to be completed.
1000 */
1001long congestion_wait(int sync, long timeout)
1002{
1003 long ret;
1004 unsigned long start = jiffies;
1005 DEFINE_WAIT(wait);
1006 wait_queue_head_t *wqh = &congestion_wqh[sync];
1007
1008 prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
1009 ret = io_schedule_timeout(timeout);
1010 finish_wait(wqh, &wait);
1011
1012 trace_writeback_congestion_wait(jiffies_to_usecs(timeout),
1013 jiffies_to_usecs(jiffies - start));
1014
1015 return ret;
1016}
1017EXPORT_SYMBOL(congestion_wait);
1018
1019/**
1020 * wait_iff_congested - Conditionally wait for a backing_dev to become uncongested or a pgdat to complete writes
1021 * @pgdat: A pgdat to check if it is heavily congested
1022 * @sync: SYNC or ASYNC IO
1023 * @timeout: timeout in jiffies
1024 *
1025 * In the event of a congested backing_dev (any backing_dev) and the given
1026 * @pgdat has experienced recent congestion, this waits for up to @timeout
1027 * jiffies for either a BDI to exit congestion of the given @sync queue
1028 * or a write to complete.
1029 *
1030 * In the absence of pgdat congestion, cond_resched() is called to yield
1031 * the processor if necessary but otherwise does not sleep.
1032 *
1033 * The return value is 0 if the sleep is for the full timeout. Otherwise,
1034 * it is the number of jiffies that were still remaining when the function
1035 * returned. return_value == timeout implies the function did not sleep.
1036 */
1037long wait_iff_congested(struct pglist_data *pgdat, int sync, long timeout)
1038{
1039 long ret;
1040 unsigned long start = jiffies;
1041 DEFINE_WAIT(wait);
1042 wait_queue_head_t *wqh = &congestion_wqh[sync];
1043
1044 /*
1045 * If there is no congestion, or heavy congestion is not being
1046 * encountered in the current pgdat, yield if necessary instead
1047 * of sleeping on the congestion queue
1048 */
1049 if (atomic_read(&nr_wb_congested[sync]) == 0 ||
1050 !test_bit(PGDAT_CONGESTED, &pgdat->flags)) {
1051 cond_resched();
1052
1053 /* In case we scheduled, work out time remaining */
1054 ret = timeout - (jiffies - start);
1055 if (ret < 0)
1056 ret = 0;
1057
1058 goto out;
1059 }
1060
1061 /* Sleep until uncongested or a write happens */
1062 prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
1063 ret = io_schedule_timeout(timeout);
1064 finish_wait(wqh, &wait);
1065
1066out:
1067 trace_writeback_wait_iff_congested(jiffies_to_usecs(timeout),
1068 jiffies_to_usecs(jiffies - start));
1069
1070 return ret;
1071}
1072EXPORT_SYMBOL(wait_iff_congested);
1073
1074int pdflush_proc_obsolete(struct ctl_table *table, int write,
1075 void __user *buffer, size_t *lenp, loff_t *ppos)
1076{
1077 char kbuf[] = "0\n";
1078
1079 if (*ppos || *lenp < sizeof(kbuf)) {
1080 *lenp = 0;
1081 return 0;
1082 }
1083
1084 if (copy_to_user(buffer, kbuf, sizeof(kbuf)))
1085 return -EFAULT;
1086 pr_warn_once("%s exported in /proc is scheduled for removal\n",
1087 table->procname);
1088
1089 *lenp = 2;
1090 *ppos += *lenp;
1091 return 2;
1092}