1 // SPDX-License-Identifier: GPL-2.0-only
3 #include <linux/wait.h>
4 #include <linux/rbtree.h>
5 #include <linux/backing-dev.h>
6 #include <linux/kthread.h>
7 #include <linux/freezer.h>
9 #include <linux/pagemap.h>
11 #include <linux/sched.h>
12 #include <linux/module.h>
13 #include <linux/writeback.h>
14 #include <linux/device.h>
15 #include <trace/events/writeback.h>
17 struct backing_dev_info noop_backing_dev_info;
18 EXPORT_SYMBOL_GPL(noop_backing_dev_info);
20 static struct class *bdi_class;
21 static const char *bdi_unknown_name = "(unknown)";
24 * bdi_lock protects bdi_tree and updates to bdi_list. bdi_list has RCU
25 * reader side locking.
27 DEFINE_SPINLOCK(bdi_lock);
28 static u64 bdi_id_cursor;
29 static struct rb_root bdi_tree = RB_ROOT;
32 /* bdi_wq serves all asynchronous writeback tasks */
33 struct workqueue_struct *bdi_wq;
35 #ifdef CONFIG_DEBUG_FS
36 #include <linux/debugfs.h>
37 #include <linux/seq_file.h>
39 static struct dentry *bdi_debug_root;
41 static void bdi_debug_init(void)
43 bdi_debug_root = debugfs_create_dir("bdi", NULL);
46 static int bdi_debug_stats_show(struct seq_file *m, void *v)
48 struct backing_dev_info *bdi = m->private;
49 struct bdi_writeback *wb = &bdi->wb;
50 unsigned long background_thresh;
51 unsigned long dirty_thresh;
52 unsigned long wb_thresh;
53 unsigned long nr_dirty, nr_io, nr_more_io, nr_dirty_time;
56 nr_dirty = nr_io = nr_more_io = nr_dirty_time = 0;
57 spin_lock(&wb->list_lock);
58 list_for_each_entry(inode, &wb->b_dirty, i_io_list)
60 list_for_each_entry(inode, &wb->b_io, i_io_list)
62 list_for_each_entry(inode, &wb->b_more_io, i_io_list)
64 list_for_each_entry(inode, &wb->b_dirty_time, i_io_list)
65 if (inode->i_state & I_DIRTY_TIME)
67 spin_unlock(&wb->list_lock);
69 global_dirty_limits(&background_thresh, &dirty_thresh);
70 wb_thresh = wb_calc_thresh(wb, dirty_thresh);
72 #define K(x) ((x) << (PAGE_SHIFT - 10))
74 "BdiWriteback: %10lu kB\n"
75 "BdiReclaimable: %10lu kB\n"
76 "BdiDirtyThresh: %10lu kB\n"
77 "DirtyThresh: %10lu kB\n"
78 "BackgroundThresh: %10lu kB\n"
79 "BdiDirtied: %10lu kB\n"
80 "BdiWritten: %10lu kB\n"
81 "BdiWriteBandwidth: %10lu kBps\n"
85 "b_dirty_time: %10lu\n"
88 (unsigned long) K(wb_stat(wb, WB_WRITEBACK)),
89 (unsigned long) K(wb_stat(wb, WB_RECLAIMABLE)),
93 (unsigned long) K(wb_stat(wb, WB_DIRTIED)),
94 (unsigned long) K(wb_stat(wb, WB_WRITTEN)),
95 (unsigned long) K(wb->write_bandwidth),
100 !list_empty(&bdi->bdi_list), bdi->wb.state);
105 DEFINE_SHOW_ATTRIBUTE(bdi_debug_stats);
107 static void bdi_debug_register(struct backing_dev_info *bdi, const char *name)
109 bdi->debug_dir = debugfs_create_dir(name, bdi_debug_root);
111 debugfs_create_file("stats", 0444, bdi->debug_dir, bdi,
112 &bdi_debug_stats_fops);
115 static void bdi_debug_unregister(struct backing_dev_info *bdi)
117 debugfs_remove_recursive(bdi->debug_dir);
120 static inline void bdi_debug_init(void)
123 static inline void bdi_debug_register(struct backing_dev_info *bdi,
127 static inline void bdi_debug_unregister(struct backing_dev_info *bdi)
132 static ssize_t read_ahead_kb_store(struct device *dev,
133 struct device_attribute *attr,
134 const char *buf, size_t count)
136 struct backing_dev_info *bdi = dev_get_drvdata(dev);
137 unsigned long read_ahead_kb;
140 ret = kstrtoul(buf, 10, &read_ahead_kb);
144 bdi->ra_pages = read_ahead_kb >> (PAGE_SHIFT - 10);
149 #define K(pages) ((pages) << (PAGE_SHIFT - 10))
151 #define BDI_SHOW(name, expr) \
152 static ssize_t name##_show(struct device *dev, \
153 struct device_attribute *attr, char *page) \
155 struct backing_dev_info *bdi = dev_get_drvdata(dev); \
157 return snprintf(page, PAGE_SIZE-1, "%lld\n", (long long)expr); \
159 static DEVICE_ATTR_RW(name);
161 BDI_SHOW(read_ahead_kb, K(bdi->ra_pages))
163 static ssize_t min_ratio_store(struct device *dev,
164 struct device_attribute *attr, const char *buf, size_t count)
166 struct backing_dev_info *bdi = dev_get_drvdata(dev);
170 ret = kstrtouint(buf, 10, &ratio);
174 ret = bdi_set_min_ratio(bdi, ratio);
180 BDI_SHOW(min_ratio, bdi->min_ratio)
182 static ssize_t max_ratio_store(struct device *dev,
183 struct device_attribute *attr, const char *buf, size_t count)
185 struct backing_dev_info *bdi = dev_get_drvdata(dev);
189 ret = kstrtouint(buf, 10, &ratio);
193 ret = bdi_set_max_ratio(bdi, ratio);
199 BDI_SHOW(max_ratio, bdi->max_ratio)
201 static ssize_t stable_pages_required_show(struct device *dev,
202 struct device_attribute *attr,
206 "the stable_pages_required attribute has been removed. Use the stable_writes queue attribute instead.\n");
207 return snprintf(page, PAGE_SIZE-1, "%d\n", 0);
209 static DEVICE_ATTR_RO(stable_pages_required);
211 static struct attribute *bdi_dev_attrs[] = {
212 &dev_attr_read_ahead_kb.attr,
213 &dev_attr_min_ratio.attr,
214 &dev_attr_max_ratio.attr,
215 &dev_attr_stable_pages_required.attr,
218 ATTRIBUTE_GROUPS(bdi_dev);
220 static __init int bdi_class_init(void)
222 bdi_class = class_create(THIS_MODULE, "bdi");
223 if (IS_ERR(bdi_class))
224 return PTR_ERR(bdi_class);
226 bdi_class->dev_groups = bdi_dev_groups;
231 postcore_initcall(bdi_class_init);
233 static int bdi_init(struct backing_dev_info *bdi);
235 static int __init default_bdi_init(void)
239 bdi_wq = alloc_workqueue("writeback", WQ_MEM_RECLAIM | WQ_UNBOUND |
244 err = bdi_init(&noop_backing_dev_info);
248 subsys_initcall(default_bdi_init);
251 * This function is used when the first inode for this wb is marked dirty. It
252 * wakes-up the corresponding bdi thread which should then take care of the
253 * periodic background write-out of dirty inodes. Since the write-out would
254 * starts only 'dirty_writeback_interval' centisecs from now anyway, we just
255 * set up a timer which wakes the bdi thread up later.
257 * Note, we wouldn't bother setting up the timer, but this function is on the
258 * fast-path (used by '__mark_inode_dirty()'), so we save few context switches
259 * by delaying the wake-up.
261 * We have to be careful not to postpone flush work if it is scheduled for
262 * earlier. Thus we use queue_delayed_work().
264 void wb_wakeup_delayed(struct bdi_writeback *wb)
266 unsigned long timeout;
268 timeout = msecs_to_jiffies(dirty_writeback_interval * 10);
269 spin_lock_bh(&wb->work_lock);
270 if (test_bit(WB_registered, &wb->state))
271 queue_delayed_work(bdi_wq, &wb->dwork, timeout);
272 spin_unlock_bh(&wb->work_lock);
276 * Initial write bandwidth: 100 MB/s
278 #define INIT_BW (100 << (20 - PAGE_SHIFT))
280 static int wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi,
285 memset(wb, 0, sizeof(*wb));
290 wb->last_old_flush = jiffies;
291 INIT_LIST_HEAD(&wb->b_dirty);
292 INIT_LIST_HEAD(&wb->b_io);
293 INIT_LIST_HEAD(&wb->b_more_io);
294 INIT_LIST_HEAD(&wb->b_dirty_time);
295 spin_lock_init(&wb->list_lock);
297 wb->bw_time_stamp = jiffies;
298 wb->balanced_dirty_ratelimit = INIT_BW;
299 wb->dirty_ratelimit = INIT_BW;
300 wb->write_bandwidth = INIT_BW;
301 wb->avg_write_bandwidth = INIT_BW;
303 spin_lock_init(&wb->work_lock);
304 INIT_LIST_HEAD(&wb->work_list);
305 INIT_DELAYED_WORK(&wb->dwork, wb_workfn);
306 wb->dirty_sleep = jiffies;
308 err = fprop_local_init_percpu(&wb->completions, gfp);
312 for (i = 0; i < NR_WB_STAT_ITEMS; i++) {
313 err = percpu_counter_init(&wb->stat[i], 0, gfp);
315 goto out_destroy_stat;
322 percpu_counter_destroy(&wb->stat[i]);
323 fprop_local_destroy_percpu(&wb->completions);
330 static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb);
333 * Remove bdi from the global list and shutdown any threads we have running
335 static void wb_shutdown(struct bdi_writeback *wb)
337 /* Make sure nobody queues further work */
338 spin_lock_bh(&wb->work_lock);
339 if (!test_and_clear_bit(WB_registered, &wb->state)) {
340 spin_unlock_bh(&wb->work_lock);
343 spin_unlock_bh(&wb->work_lock);
345 cgwb_remove_from_bdi_list(wb);
347 * Drain work list and shutdown the delayed_work. !WB_registered
348 * tells wb_workfn() that @wb is dying and its work_list needs to
349 * be drained no matter what.
351 mod_delayed_work(bdi_wq, &wb->dwork, 0);
352 flush_delayed_work(&wb->dwork);
353 WARN_ON(!list_empty(&wb->work_list));
356 static void wb_exit(struct bdi_writeback *wb)
360 WARN_ON(delayed_work_pending(&wb->dwork));
362 for (i = 0; i < NR_WB_STAT_ITEMS; i++)
363 percpu_counter_destroy(&wb->stat[i]);
365 fprop_local_destroy_percpu(&wb->completions);
366 if (wb != &wb->bdi->wb)
370 #ifdef CONFIG_CGROUP_WRITEBACK
372 #include <linux/memcontrol.h>
375 * cgwb_lock protects bdi->cgwb_tree, blkcg->cgwb_list, and memcg->cgwb_list.
376 * bdi->cgwb_tree is also RCU protected.
378 static DEFINE_SPINLOCK(cgwb_lock);
379 static struct workqueue_struct *cgwb_release_wq;
381 static void cgwb_free_rcu(struct rcu_head *rcu_head)
383 struct bdi_writeback *wb = container_of(rcu_head,
384 struct bdi_writeback, rcu);
386 percpu_ref_exit(&wb->refcnt);
390 static void cgwb_release_workfn(struct work_struct *work)
392 struct bdi_writeback *wb = container_of(work, struct bdi_writeback,
394 struct blkcg *blkcg = css_to_blkcg(wb->blkcg_css);
396 mutex_lock(&wb->bdi->cgwb_release_mutex);
399 css_put(wb->memcg_css);
400 css_put(wb->blkcg_css);
401 mutex_unlock(&wb->bdi->cgwb_release_mutex);
403 /* triggers blkg destruction if no online users left */
404 blkcg_unpin_online(blkcg);
406 fprop_local_destroy_percpu(&wb->memcg_completions);
408 call_rcu(&wb->rcu, cgwb_free_rcu);
411 static void cgwb_release(struct percpu_ref *refcnt)
413 struct bdi_writeback *wb = container_of(refcnt, struct bdi_writeback,
415 queue_work(cgwb_release_wq, &wb->release_work);
418 static void cgwb_kill(struct bdi_writeback *wb)
420 lockdep_assert_held(&cgwb_lock);
422 WARN_ON(!radix_tree_delete(&wb->bdi->cgwb_tree, wb->memcg_css->id));
423 list_del(&wb->memcg_node);
424 list_del(&wb->blkcg_node);
425 percpu_ref_kill(&wb->refcnt);
428 static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb)
430 spin_lock_irq(&cgwb_lock);
431 list_del_rcu(&wb->bdi_node);
432 spin_unlock_irq(&cgwb_lock);
435 static int cgwb_create(struct backing_dev_info *bdi,
436 struct cgroup_subsys_state *memcg_css, gfp_t gfp)
438 struct mem_cgroup *memcg;
439 struct cgroup_subsys_state *blkcg_css;
441 struct list_head *memcg_cgwb_list, *blkcg_cgwb_list;
442 struct bdi_writeback *wb;
446 memcg = mem_cgroup_from_css(memcg_css);
447 blkcg_css = cgroup_get_e_css(memcg_css->cgroup, &io_cgrp_subsys);
448 blkcg = css_to_blkcg(blkcg_css);
449 memcg_cgwb_list = &memcg->cgwb_list;
450 blkcg_cgwb_list = &blkcg->cgwb_list;
452 /* look up again under lock and discard on blkcg mismatch */
453 spin_lock_irqsave(&cgwb_lock, flags);
454 wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id);
455 if (wb && wb->blkcg_css != blkcg_css) {
459 spin_unlock_irqrestore(&cgwb_lock, flags);
463 /* need to create a new one */
464 wb = kmalloc(sizeof(*wb), gfp);
470 ret = wb_init(wb, bdi, gfp);
474 ret = percpu_ref_init(&wb->refcnt, cgwb_release, 0, gfp);
478 ret = fprop_local_init_percpu(&wb->memcg_completions, gfp);
482 wb->memcg_css = memcg_css;
483 wb->blkcg_css = blkcg_css;
484 INIT_WORK(&wb->release_work, cgwb_release_workfn);
485 set_bit(WB_registered, &wb->state);
488 * The root wb determines the registered state of the whole bdi and
489 * memcg_cgwb_list and blkcg_cgwb_list's next pointers indicate
490 * whether they're still online. Don't link @wb if any is dead.
491 * See wb_memcg_offline() and wb_blkcg_offline().
494 spin_lock_irqsave(&cgwb_lock, flags);
495 if (test_bit(WB_registered, &bdi->wb.state) &&
496 blkcg_cgwb_list->next && memcg_cgwb_list->next) {
497 /* we might have raced another instance of this function */
498 ret = radix_tree_insert(&bdi->cgwb_tree, memcg_css->id, wb);
500 list_add_tail_rcu(&wb->bdi_node, &bdi->wb_list);
501 list_add(&wb->memcg_node, memcg_cgwb_list);
502 list_add(&wb->blkcg_node, blkcg_cgwb_list);
503 blkcg_pin_online(blkcg);
508 spin_unlock_irqrestore(&cgwb_lock, flags);
517 fprop_local_destroy_percpu(&wb->memcg_completions);
519 percpu_ref_exit(&wb->refcnt);
530 * wb_get_lookup - get wb for a given memcg
532 * @memcg_css: cgroup_subsys_state of the target memcg (must have positive ref)
534 * Try to get the wb for @memcg_css on @bdi. The returned wb has its
535 * refcount incremented.
537 * This function uses css_get() on @memcg_css and thus expects its refcnt
538 * to be positive on invocation. IOW, rcu_read_lock() protection on
539 * @memcg_css isn't enough. try_get it before calling this function.
541 * A wb is keyed by its associated memcg. As blkcg implicitly enables
542 * memcg on the default hierarchy, memcg association is guaranteed to be
543 * more specific (equal or descendant to the associated blkcg) and thus can
544 * identify both the memcg and blkcg associations.
546 * Because the blkcg associated with a memcg may change as blkcg is enabled
547 * and disabled closer to root in the hierarchy, each wb keeps track of
548 * both the memcg and blkcg associated with it and verifies the blkcg on
549 * each lookup. On mismatch, the existing wb is discarded and a new one is
552 struct bdi_writeback *wb_get_lookup(struct backing_dev_info *bdi,
553 struct cgroup_subsys_state *memcg_css)
555 struct bdi_writeback *wb;
557 if (!memcg_css->parent)
561 wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id);
563 struct cgroup_subsys_state *blkcg_css;
565 /* see whether the blkcg association has changed */
566 blkcg_css = cgroup_get_e_css(memcg_css->cgroup, &io_cgrp_subsys);
567 if (unlikely(wb->blkcg_css != blkcg_css || !wb_tryget(wb)))
577 * wb_get_create - get wb for a given memcg, create if necessary
579 * @memcg_css: cgroup_subsys_state of the target memcg (must have positive ref)
580 * @gfp: allocation mask to use
582 * Try to get the wb for @memcg_css on @bdi. If it doesn't exist, try to
583 * create one. See wb_get_lookup() for more details.
585 struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi,
586 struct cgroup_subsys_state *memcg_css,
589 struct bdi_writeback *wb;
591 might_sleep_if(gfpflags_allow_blocking(gfp));
593 if (!memcg_css->parent)
597 wb = wb_get_lookup(bdi, memcg_css);
598 } while (!wb && !cgwb_create(bdi, memcg_css, gfp));
603 static int cgwb_bdi_init(struct backing_dev_info *bdi)
607 INIT_RADIX_TREE(&bdi->cgwb_tree, GFP_ATOMIC);
608 mutex_init(&bdi->cgwb_release_mutex);
609 init_rwsem(&bdi->wb_switch_rwsem);
611 ret = wb_init(&bdi->wb, bdi, GFP_KERNEL);
613 bdi->wb.memcg_css = &root_mem_cgroup->css;
614 bdi->wb.blkcg_css = blkcg_root_css;
619 static void cgwb_bdi_unregister(struct backing_dev_info *bdi)
621 struct radix_tree_iter iter;
623 struct bdi_writeback *wb;
625 WARN_ON(test_bit(WB_registered, &bdi->wb.state));
627 spin_lock_irq(&cgwb_lock);
628 radix_tree_for_each_slot(slot, &bdi->cgwb_tree, &iter, 0)
630 spin_unlock_irq(&cgwb_lock);
632 mutex_lock(&bdi->cgwb_release_mutex);
633 spin_lock_irq(&cgwb_lock);
634 while (!list_empty(&bdi->wb_list)) {
635 wb = list_first_entry(&bdi->wb_list, struct bdi_writeback,
637 spin_unlock_irq(&cgwb_lock);
639 spin_lock_irq(&cgwb_lock);
641 spin_unlock_irq(&cgwb_lock);
642 mutex_unlock(&bdi->cgwb_release_mutex);
646 * wb_memcg_offline - kill all wb's associated with a memcg being offlined
647 * @memcg: memcg being offlined
649 * Also prevents creation of any new wb's associated with @memcg.
651 void wb_memcg_offline(struct mem_cgroup *memcg)
653 struct list_head *memcg_cgwb_list = &memcg->cgwb_list;
654 struct bdi_writeback *wb, *next;
656 spin_lock_irq(&cgwb_lock);
657 list_for_each_entry_safe(wb, next, memcg_cgwb_list, memcg_node)
659 memcg_cgwb_list->next = NULL; /* prevent new wb's */
660 spin_unlock_irq(&cgwb_lock);
664 * wb_blkcg_offline - kill all wb's associated with a blkcg being offlined
665 * @blkcg: blkcg being offlined
667 * Also prevents creation of any new wb's associated with @blkcg.
669 void wb_blkcg_offline(struct blkcg *blkcg)
671 struct bdi_writeback *wb, *next;
673 spin_lock_irq(&cgwb_lock);
674 list_for_each_entry_safe(wb, next, &blkcg->cgwb_list, blkcg_node)
676 blkcg->cgwb_list.next = NULL; /* prevent new wb's */
677 spin_unlock_irq(&cgwb_lock);
680 static void cgwb_bdi_register(struct backing_dev_info *bdi)
682 spin_lock_irq(&cgwb_lock);
683 list_add_tail_rcu(&bdi->wb.bdi_node, &bdi->wb_list);
684 spin_unlock_irq(&cgwb_lock);
687 static int __init cgwb_init(void)
690 * There can be many concurrent release work items overwhelming
691 * system_wq. Put them in a separate wq and limit concurrency.
692 * There's no point in executing many of these in parallel.
694 cgwb_release_wq = alloc_workqueue("cgwb_release", 0, 1);
695 if (!cgwb_release_wq)
700 subsys_initcall(cgwb_init);
702 #else /* CONFIG_CGROUP_WRITEBACK */
704 static int cgwb_bdi_init(struct backing_dev_info *bdi)
706 return wb_init(&bdi->wb, bdi, GFP_KERNEL);
709 static void cgwb_bdi_unregister(struct backing_dev_info *bdi) { }
711 static void cgwb_bdi_register(struct backing_dev_info *bdi)
713 list_add_tail_rcu(&bdi->wb.bdi_node, &bdi->wb_list);
716 static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb)
718 list_del_rcu(&wb->bdi_node);
721 #endif /* CONFIG_CGROUP_WRITEBACK */
723 static int bdi_init(struct backing_dev_info *bdi)
729 kref_init(&bdi->refcnt);
731 bdi->max_ratio = 100;
732 bdi->max_prop_frac = FPROP_FRAC_BASE;
733 INIT_LIST_HEAD(&bdi->bdi_list);
734 INIT_LIST_HEAD(&bdi->wb_list);
735 init_waitqueue_head(&bdi->wb_waitq);
737 ret = cgwb_bdi_init(bdi);
742 struct backing_dev_info *bdi_alloc(int node_id)
744 struct backing_dev_info *bdi;
746 bdi = kzalloc_node(sizeof(*bdi), GFP_KERNEL, node_id);
754 bdi->capabilities = BDI_CAP_WRITEBACK | BDI_CAP_WRITEBACK_ACCT;
755 bdi->ra_pages = VM_READAHEAD_PAGES;
756 bdi->io_pages = VM_READAHEAD_PAGES;
759 EXPORT_SYMBOL(bdi_alloc);
761 static struct rb_node **bdi_lookup_rb_node(u64 id, struct rb_node **parentp)
763 struct rb_node **p = &bdi_tree.rb_node;
764 struct rb_node *parent = NULL;
765 struct backing_dev_info *bdi;
767 lockdep_assert_held(&bdi_lock);
771 bdi = rb_entry(parent, struct backing_dev_info, rb_node);
775 else if (bdi->id < id)
787 * bdi_get_by_id - lookup and get bdi from its id
788 * @id: bdi id to lookup
790 * Find bdi matching @id and get it. Returns NULL if the matching bdi
791 * doesn't exist or is already unregistered.
793 struct backing_dev_info *bdi_get_by_id(u64 id)
795 struct backing_dev_info *bdi = NULL;
798 spin_lock_bh(&bdi_lock);
799 p = bdi_lookup_rb_node(id, NULL);
801 bdi = rb_entry(*p, struct backing_dev_info, rb_node);
804 spin_unlock_bh(&bdi_lock);
809 int bdi_register_va(struct backing_dev_info *bdi, const char *fmt, va_list args)
812 struct rb_node *parent, **p;
814 if (bdi->dev) /* The driver needs to use separate queues per device */
817 vsnprintf(bdi->dev_name, sizeof(bdi->dev_name), fmt, args);
818 dev = device_create(bdi_class, NULL, MKDEV(0, 0), bdi, bdi->dev_name);
822 cgwb_bdi_register(bdi);
825 bdi_debug_register(bdi, dev_name(dev));
826 set_bit(WB_registered, &bdi->wb.state);
828 spin_lock_bh(&bdi_lock);
830 bdi->id = ++bdi_id_cursor;
832 p = bdi_lookup_rb_node(bdi->id, &parent);
833 rb_link_node(&bdi->rb_node, parent, p);
834 rb_insert_color(&bdi->rb_node, &bdi_tree);
836 list_add_tail_rcu(&bdi->bdi_list, &bdi_list);
838 spin_unlock_bh(&bdi_lock);
840 trace_writeback_bdi_register(bdi);
844 int bdi_register(struct backing_dev_info *bdi, const char *fmt, ...)
850 ret = bdi_register_va(bdi, fmt, args);
854 EXPORT_SYMBOL(bdi_register);
856 void bdi_set_owner(struct backing_dev_info *bdi, struct device *owner)
858 WARN_ON_ONCE(bdi->owner);
864 * Remove bdi from bdi_list, and ensure that it is no longer visible
866 static void bdi_remove_from_list(struct backing_dev_info *bdi)
868 spin_lock_bh(&bdi_lock);
869 rb_erase(&bdi->rb_node, &bdi_tree);
870 list_del_rcu(&bdi->bdi_list);
871 spin_unlock_bh(&bdi_lock);
873 synchronize_rcu_expedited();
876 void bdi_unregister(struct backing_dev_info *bdi)
878 /* make sure nobody finds us on the bdi_list anymore */
879 bdi_remove_from_list(bdi);
880 wb_shutdown(&bdi->wb);
881 cgwb_bdi_unregister(bdi);
884 * If this BDI's min ratio has been set, use bdi_set_min_ratio() to
885 * update the global bdi_min_ratio.
888 bdi_set_min_ratio(bdi, 0);
891 bdi_debug_unregister(bdi);
892 device_unregister(bdi->dev);
897 put_device(bdi->owner);
902 static void release_bdi(struct kref *ref)
904 struct backing_dev_info *bdi =
905 container_of(ref, struct backing_dev_info, refcnt);
907 if (test_bit(WB_registered, &bdi->wb.state))
909 WARN_ON_ONCE(bdi->dev);
914 void bdi_put(struct backing_dev_info *bdi)
916 kref_put(&bdi->refcnt, release_bdi);
918 EXPORT_SYMBOL(bdi_put);
920 const char *bdi_dev_name(struct backing_dev_info *bdi)
922 if (!bdi || !bdi->dev)
923 return bdi_unknown_name;
924 return bdi->dev_name;
926 EXPORT_SYMBOL_GPL(bdi_dev_name);
928 static wait_queue_head_t congestion_wqh[2] = {
929 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]),
930 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1])
932 static atomic_t nr_wb_congested[2];
934 void clear_bdi_congested(struct backing_dev_info *bdi, int sync)
936 wait_queue_head_t *wqh = &congestion_wqh[sync];
937 enum wb_congested_state bit;
939 bit = sync ? WB_sync_congested : WB_async_congested;
940 if (test_and_clear_bit(bit, &bdi->wb.congested))
941 atomic_dec(&nr_wb_congested[sync]);
942 smp_mb__after_atomic();
943 if (waitqueue_active(wqh))
946 EXPORT_SYMBOL(clear_bdi_congested);
948 void set_bdi_congested(struct backing_dev_info *bdi, int sync)
950 enum wb_congested_state bit;
952 bit = sync ? WB_sync_congested : WB_async_congested;
953 if (!test_and_set_bit(bit, &bdi->wb.congested))
954 atomic_inc(&nr_wb_congested[sync]);
956 EXPORT_SYMBOL(set_bdi_congested);
959 * congestion_wait - wait for a backing_dev to become uncongested
960 * @sync: SYNC or ASYNC IO
961 * @timeout: timeout in jiffies
963 * Waits for up to @timeout jiffies for a backing_dev (any backing_dev) to exit
964 * write congestion. If no backing_devs are congested then just wait for the
965 * next write to be completed.
967 long congestion_wait(int sync, long timeout)
970 unsigned long start = jiffies;
972 wait_queue_head_t *wqh = &congestion_wqh[sync];
974 prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
975 ret = io_schedule_timeout(timeout);
976 finish_wait(wqh, &wait);
978 trace_writeback_congestion_wait(jiffies_to_usecs(timeout),
979 jiffies_to_usecs(jiffies - start));
983 EXPORT_SYMBOL(congestion_wait);
986 * wait_iff_congested - Conditionally wait for a backing_dev to become uncongested or a pgdat to complete writes
987 * @sync: SYNC or ASYNC IO
988 * @timeout: timeout in jiffies
990 * In the event of a congested backing_dev (any backing_dev) this waits
991 * for up to @timeout jiffies for either a BDI to exit congestion of the
992 * given @sync queue or a write to complete.
994 * The return value is 0 if the sleep is for the full timeout. Otherwise,
995 * it is the number of jiffies that were still remaining when the function
996 * returned. return_value == timeout implies the function did not sleep.
998 long wait_iff_congested(int sync, long timeout)
1001 unsigned long start = jiffies;
1003 wait_queue_head_t *wqh = &congestion_wqh[sync];
1006 * If there is no congestion, yield if necessary instead
1007 * of sleeping on the congestion queue
1009 if (atomic_read(&nr_wb_congested[sync]) == 0) {
1012 /* In case we scheduled, work out time remaining */
1013 ret = timeout - (jiffies - start);
1020 /* Sleep until uncongested or a write happens */
1021 prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
1022 ret = io_schedule_timeout(timeout);
1023 finish_wait(wqh, &wait);
1026 trace_writeback_wait_iff_congested(jiffies_to_usecs(timeout),
1027 jiffies_to_usecs(jiffies - start));
1031 EXPORT_SYMBOL(wait_iff_congested);