1 // SPDX-License-Identifier: GPL-2.0-only
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>
11 #include <linux/pagemap.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>
20 struct backing_dev_info noop_backing_dev_info;
21 EXPORT_SYMBOL_GPL(noop_backing_dev_info);
23 static struct class *bdi_class;
24 static const char *bdi_unknown_name = "(unknown)";
27 * bdi_lock protects bdi_tree and updates to bdi_list. bdi_list has RCU
28 * reader side locking.
30 DEFINE_SPINLOCK(bdi_lock);
31 static u64 bdi_id_cursor;
32 static struct rb_root bdi_tree = RB_ROOT;
35 /* bdi_wq serves all asynchronous writeback tasks */
36 struct workqueue_struct *bdi_wq;
38 #define K(x) ((x) << (PAGE_SHIFT - 10))
40 #ifdef CONFIG_DEBUG_FS
41 #include <linux/debugfs.h>
42 #include <linux/seq_file.h>
44 static struct dentry *bdi_debug_root;
46 static void bdi_debug_init(void)
48 bdi_debug_root = debugfs_create_dir("bdi", NULL);
51 static int bdi_debug_stats_show(struct seq_file *m, void *v)
53 struct backing_dev_info *bdi = m->private;
54 struct bdi_writeback *wb = &bdi->wb;
55 unsigned long background_thresh;
56 unsigned long dirty_thresh;
57 unsigned long wb_thresh;
58 unsigned long nr_dirty, nr_io, nr_more_io, nr_dirty_time;
61 nr_dirty = nr_io = nr_more_io = nr_dirty_time = 0;
62 spin_lock(&wb->list_lock);
63 list_for_each_entry(inode, &wb->b_dirty, i_io_list)
65 list_for_each_entry(inode, &wb->b_io, i_io_list)
67 list_for_each_entry(inode, &wb->b_more_io, i_io_list)
69 list_for_each_entry(inode, &wb->b_dirty_time, i_io_list)
70 if (inode->i_state & I_DIRTY_TIME)
72 spin_unlock(&wb->list_lock);
74 global_dirty_limits(&background_thresh, &dirty_thresh);
75 wb_thresh = wb_calc_thresh(wb, dirty_thresh);
78 "BdiWriteback: %10lu kB\n"
79 "BdiReclaimable: %10lu kB\n"
80 "BdiDirtyThresh: %10lu kB\n"
81 "DirtyThresh: %10lu kB\n"
82 "BackgroundThresh: %10lu kB\n"
83 "BdiDirtied: %10lu kB\n"
84 "BdiWritten: %10lu kB\n"
85 "BdiWriteBandwidth: %10lu kBps\n"
89 "b_dirty_time: %10lu\n"
92 (unsigned long) K(wb_stat(wb, WB_WRITEBACK)),
93 (unsigned long) K(wb_stat(wb, WB_RECLAIMABLE)),
97 (unsigned long) K(wb_stat(wb, WB_DIRTIED)),
98 (unsigned long) K(wb_stat(wb, WB_WRITTEN)),
99 (unsigned long) K(wb->write_bandwidth),
104 !list_empty(&bdi->bdi_list), bdi->wb.state);
108 DEFINE_SHOW_ATTRIBUTE(bdi_debug_stats);
110 static void bdi_debug_register(struct backing_dev_info *bdi, const char *name)
112 bdi->debug_dir = debugfs_create_dir(name, bdi_debug_root);
114 debugfs_create_file("stats", 0444, bdi->debug_dir, bdi,
115 &bdi_debug_stats_fops);
118 static void bdi_debug_unregister(struct backing_dev_info *bdi)
120 debugfs_remove_recursive(bdi->debug_dir);
123 static inline void bdi_debug_init(void)
126 static inline void bdi_debug_register(struct backing_dev_info *bdi,
130 static inline void bdi_debug_unregister(struct backing_dev_info *bdi)
135 static ssize_t read_ahead_kb_store(struct device *dev,
136 struct device_attribute *attr,
137 const char *buf, size_t count)
139 struct backing_dev_info *bdi = dev_get_drvdata(dev);
140 unsigned long read_ahead_kb;
143 ret = kstrtoul(buf, 10, &read_ahead_kb);
147 bdi->ra_pages = read_ahead_kb >> (PAGE_SHIFT - 10);
152 #define BDI_SHOW(name, expr) \
153 static ssize_t name##_show(struct device *dev, \
154 struct device_attribute *attr, char *buf) \
156 struct backing_dev_info *bdi = dev_get_drvdata(dev); \
158 return sysfs_emit(buf, "%lld\n", (long long)expr); \
160 static DEVICE_ATTR_RW(name);
162 BDI_SHOW(read_ahead_kb, K(bdi->ra_pages))
164 static ssize_t min_ratio_store(struct device *dev,
165 struct device_attribute *attr, const char *buf, size_t count)
167 struct backing_dev_info *bdi = dev_get_drvdata(dev);
171 ret = kstrtouint(buf, 10, &ratio);
175 ret = bdi_set_min_ratio(bdi, ratio);
181 BDI_SHOW(min_ratio, bdi->min_ratio)
183 static ssize_t max_ratio_store(struct device *dev,
184 struct device_attribute *attr, const char *buf, size_t count)
186 struct backing_dev_info *bdi = dev_get_drvdata(dev);
190 ret = kstrtouint(buf, 10, &ratio);
194 ret = bdi_set_max_ratio(bdi, ratio);
200 BDI_SHOW(max_ratio, bdi->max_ratio)
202 static ssize_t stable_pages_required_show(struct device *dev,
203 struct device_attribute *attr,
207 "the stable_pages_required attribute has been removed. Use the stable_writes queue attribute instead.\n");
208 return sysfs_emit(buf, "%d\n", 0);
210 static DEVICE_ATTR_RO(stable_pages_required);
212 static struct attribute *bdi_dev_attrs[] = {
213 &dev_attr_read_ahead_kb.attr,
214 &dev_attr_min_ratio.attr,
215 &dev_attr_max_ratio.attr,
216 &dev_attr_stable_pages_required.attr,
219 ATTRIBUTE_GROUPS(bdi_dev);
221 static __init int bdi_class_init(void)
223 bdi_class = class_create(THIS_MODULE, "bdi");
224 if (IS_ERR(bdi_class))
225 return PTR_ERR(bdi_class);
227 bdi_class->dev_groups = bdi_dev_groups;
232 postcore_initcall(bdi_class_init);
234 static int __init default_bdi_init(void)
236 bdi_wq = alloc_workqueue("writeback", WQ_MEM_RECLAIM | WQ_UNBOUND |
242 subsys_initcall(default_bdi_init);
245 * This function is used when the first inode for this wb is marked dirty. It
246 * wakes-up the corresponding bdi thread which should then take care of the
247 * periodic background write-out of dirty inodes. Since the write-out would
248 * starts only 'dirty_writeback_interval' centisecs from now anyway, we just
249 * set up a timer which wakes the bdi thread up later.
251 * Note, we wouldn't bother setting up the timer, but this function is on the
252 * fast-path (used by '__mark_inode_dirty()'), so we save few context switches
253 * by delaying the wake-up.
255 * We have to be careful not to postpone flush work if it is scheduled for
256 * earlier. Thus we use queue_delayed_work().
258 void wb_wakeup_delayed(struct bdi_writeback *wb)
260 unsigned long timeout;
262 timeout = msecs_to_jiffies(dirty_writeback_interval * 10);
263 spin_lock_bh(&wb->work_lock);
264 if (test_bit(WB_registered, &wb->state))
265 queue_delayed_work(bdi_wq, &wb->dwork, timeout);
266 spin_unlock_bh(&wb->work_lock);
269 static void wb_update_bandwidth_workfn(struct work_struct *work)
271 struct bdi_writeback *wb = container_of(to_delayed_work(work),
272 struct bdi_writeback, bw_dwork);
274 wb_update_bandwidth(wb);
278 * Initial write bandwidth: 100 MB/s
280 #define INIT_BW (100 << (20 - PAGE_SHIFT))
282 static int wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi,
287 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 atomic_set(&wb->writeback_inodes, 0);
298 wb->bw_time_stamp = jiffies;
299 wb->balanced_dirty_ratelimit = INIT_BW;
300 wb->dirty_ratelimit = INIT_BW;
301 wb->write_bandwidth = INIT_BW;
302 wb->avg_write_bandwidth = INIT_BW;
304 spin_lock_init(&wb->work_lock);
305 INIT_LIST_HEAD(&wb->work_list);
306 INIT_DELAYED_WORK(&wb->dwork, wb_workfn);
307 INIT_DELAYED_WORK(&wb->bw_dwork, wb_update_bandwidth_workfn);
308 wb->dirty_sleep = jiffies;
310 err = fprop_local_init_percpu(&wb->completions, gfp);
314 for (i = 0; i < NR_WB_STAT_ITEMS; i++) {
315 err = percpu_counter_init(&wb->stat[i], 0, gfp);
317 goto out_destroy_stat;
324 percpu_counter_destroy(&wb->stat[i]);
325 fprop_local_destroy_percpu(&wb->completions);
329 static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb);
332 * Remove bdi from the global list and shutdown any threads we have running
334 static void wb_shutdown(struct bdi_writeback *wb)
336 /* Make sure nobody queues further work */
337 spin_lock_bh(&wb->work_lock);
338 if (!test_and_clear_bit(WB_registered, &wb->state)) {
339 spin_unlock_bh(&wb->work_lock);
342 spin_unlock_bh(&wb->work_lock);
344 cgwb_remove_from_bdi_list(wb);
346 * Drain work list and shutdown the delayed_work. !WB_registered
347 * tells wb_workfn() that @wb is dying and its work_list needs to
348 * be drained no matter what.
350 mod_delayed_work(bdi_wq, &wb->dwork, 0);
351 flush_delayed_work(&wb->dwork);
352 WARN_ON(!list_empty(&wb->work_list));
353 flush_delayed_work(&wb->bw_dwork);
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);
368 #ifdef CONFIG_CGROUP_WRITEBACK
370 #include <linux/memcontrol.h>
373 * cgwb_lock protects bdi->cgwb_tree, blkcg->cgwb_list, offline_cgwbs and
374 * memcg->cgwb_list. bdi->cgwb_tree is also RCU protected.
376 static DEFINE_SPINLOCK(cgwb_lock);
377 static struct workqueue_struct *cgwb_release_wq;
379 static LIST_HEAD(offline_cgwbs);
380 static void cleanup_offline_cgwbs_workfn(struct work_struct *work);
381 static DECLARE_WORK(cleanup_offline_cgwbs_work, cleanup_offline_cgwbs_workfn);
383 static void cgwb_release_workfn(struct work_struct *work)
385 struct bdi_writeback *wb = container_of(work, struct bdi_writeback,
387 struct backing_dev_info *bdi = wb->bdi;
389 mutex_lock(&wb->bdi->cgwb_release_mutex);
392 css_put(wb->memcg_css);
393 css_put(wb->blkcg_css);
394 mutex_unlock(&wb->bdi->cgwb_release_mutex);
396 /* triggers blkg destruction if no online users left */
397 blkcg_unpin_online(wb->blkcg_css);
399 fprop_local_destroy_percpu(&wb->memcg_completions);
401 spin_lock_irq(&cgwb_lock);
402 list_del(&wb->offline_node);
403 spin_unlock_irq(&cgwb_lock);
405 percpu_ref_exit(&wb->refcnt);
408 WARN_ON_ONCE(!list_empty(&wb->b_attached));
412 static void cgwb_release(struct percpu_ref *refcnt)
414 struct bdi_writeback *wb = container_of(refcnt, struct bdi_writeback,
416 queue_work(cgwb_release_wq, &wb->release_work);
419 static void cgwb_kill(struct bdi_writeback *wb)
421 lockdep_assert_held(&cgwb_lock);
423 WARN_ON(!radix_tree_delete(&wb->bdi->cgwb_tree, wb->memcg_css->id));
424 list_del(&wb->memcg_node);
425 list_del(&wb->blkcg_node);
426 list_add(&wb->offline_node, &offline_cgwbs);
427 percpu_ref_kill(&wb->refcnt);
430 static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb)
432 spin_lock_irq(&cgwb_lock);
433 list_del_rcu(&wb->bdi_node);
434 spin_unlock_irq(&cgwb_lock);
437 static int cgwb_create(struct backing_dev_info *bdi,
438 struct cgroup_subsys_state *memcg_css, gfp_t gfp)
440 struct mem_cgroup *memcg;
441 struct cgroup_subsys_state *blkcg_css;
442 struct list_head *memcg_cgwb_list, *blkcg_cgwb_list;
443 struct bdi_writeback *wb;
447 memcg = mem_cgroup_from_css(memcg_css);
448 blkcg_css = cgroup_get_e_css(memcg_css->cgroup, &io_cgrp_subsys);
449 memcg_cgwb_list = &memcg->cgwb_list;
450 blkcg_cgwb_list = blkcg_get_cgwb_list(blkcg_css);
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_LIST_HEAD(&wb->b_attached);
485 INIT_WORK(&wb->release_work, cgwb_release_workfn);
486 set_bit(WB_registered, &wb->state);
490 * The root wb determines the registered state of the whole bdi and
491 * memcg_cgwb_list and blkcg_cgwb_list's next pointers indicate
492 * whether they're still online. Don't link @wb if any is dead.
493 * See wb_memcg_offline() and wb_blkcg_offline().
496 spin_lock_irqsave(&cgwb_lock, flags);
497 if (test_bit(WB_registered, &bdi->wb.state) &&
498 blkcg_cgwb_list->next && memcg_cgwb_list->next) {
499 /* we might have raced another instance of this function */
500 ret = radix_tree_insert(&bdi->cgwb_tree, memcg_css->id, wb);
502 list_add_tail_rcu(&wb->bdi_node, &bdi->wb_list);
503 list_add(&wb->memcg_node, memcg_cgwb_list);
504 list_add(&wb->blkcg_node, blkcg_cgwb_list);
505 blkcg_pin_online(blkcg_css);
510 spin_unlock_irqrestore(&cgwb_lock, flags);
520 fprop_local_destroy_percpu(&wb->memcg_completions);
522 percpu_ref_exit(&wb->refcnt);
533 * wb_get_lookup - get wb for a given memcg
535 * @memcg_css: cgroup_subsys_state of the target memcg (must have positive ref)
537 * Try to get the wb for @memcg_css on @bdi. The returned wb has its
538 * refcount incremented.
540 * This function uses css_get() on @memcg_css and thus expects its refcnt
541 * to be positive on invocation. IOW, rcu_read_lock() protection on
542 * @memcg_css isn't enough. try_get it before calling this function.
544 * A wb is keyed by its associated memcg. As blkcg implicitly enables
545 * memcg on the default hierarchy, memcg association is guaranteed to be
546 * more specific (equal or descendant to the associated blkcg) and thus can
547 * identify both the memcg and blkcg associations.
549 * Because the blkcg associated with a memcg may change as blkcg is enabled
550 * and disabled closer to root in the hierarchy, each wb keeps track of
551 * both the memcg and blkcg associated with it and verifies the blkcg on
552 * each lookup. On mismatch, the existing wb is discarded and a new one is
555 struct bdi_writeback *wb_get_lookup(struct backing_dev_info *bdi,
556 struct cgroup_subsys_state *memcg_css)
558 struct bdi_writeback *wb;
560 if (!memcg_css->parent)
564 wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id);
566 struct cgroup_subsys_state *blkcg_css;
568 /* see whether the blkcg association has changed */
569 blkcg_css = cgroup_get_e_css(memcg_css->cgroup, &io_cgrp_subsys);
570 if (unlikely(wb->blkcg_css != blkcg_css || !wb_tryget(wb)))
580 * wb_get_create - get wb for a given memcg, create if necessary
582 * @memcg_css: cgroup_subsys_state of the target memcg (must have positive ref)
583 * @gfp: allocation mask to use
585 * Try to get the wb for @memcg_css on @bdi. If it doesn't exist, try to
586 * create one. See wb_get_lookup() for more details.
588 struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi,
589 struct cgroup_subsys_state *memcg_css,
592 struct bdi_writeback *wb;
596 if (!memcg_css->parent)
600 wb = wb_get_lookup(bdi, memcg_css);
601 } while (!wb && !cgwb_create(bdi, memcg_css, gfp));
606 static int cgwb_bdi_init(struct backing_dev_info *bdi)
610 INIT_RADIX_TREE(&bdi->cgwb_tree, GFP_ATOMIC);
611 mutex_init(&bdi->cgwb_release_mutex);
612 init_rwsem(&bdi->wb_switch_rwsem);
614 ret = wb_init(&bdi->wb, bdi, GFP_KERNEL);
616 bdi->wb.memcg_css = &root_mem_cgroup->css;
617 bdi->wb.blkcg_css = blkcg_root_css;
622 static void cgwb_bdi_unregister(struct backing_dev_info *bdi)
624 struct radix_tree_iter iter;
626 struct bdi_writeback *wb;
628 WARN_ON(test_bit(WB_registered, &bdi->wb.state));
630 spin_lock_irq(&cgwb_lock);
631 radix_tree_for_each_slot(slot, &bdi->cgwb_tree, &iter, 0)
633 spin_unlock_irq(&cgwb_lock);
635 mutex_lock(&bdi->cgwb_release_mutex);
636 spin_lock_irq(&cgwb_lock);
637 while (!list_empty(&bdi->wb_list)) {
638 wb = list_first_entry(&bdi->wb_list, struct bdi_writeback,
640 spin_unlock_irq(&cgwb_lock);
642 spin_lock_irq(&cgwb_lock);
644 spin_unlock_irq(&cgwb_lock);
645 mutex_unlock(&bdi->cgwb_release_mutex);
649 * cleanup_offline_cgwbs_workfn - try to release dying cgwbs
651 * Try to release dying cgwbs by switching attached inodes to the nearest
652 * living ancestor's writeback. Processed wbs are placed at the end
653 * of the list to guarantee the forward progress.
655 static void cleanup_offline_cgwbs_workfn(struct work_struct *work)
657 struct bdi_writeback *wb;
658 LIST_HEAD(processed);
660 spin_lock_irq(&cgwb_lock);
662 while (!list_empty(&offline_cgwbs)) {
663 wb = list_first_entry(&offline_cgwbs, struct bdi_writeback,
665 list_move(&wb->offline_node, &processed);
668 * If wb is dirty, cleaning up the writeback by switching
669 * attached inodes will result in an effective removal of any
670 * bandwidth restrictions, which isn't the goal. Instead,
671 * it can be postponed until the next time, when all io
672 * will be likely completed. If in the meantime some inodes
673 * will get re-dirtied, they should be eventually switched to
676 if (wb_has_dirty_io(wb))
682 spin_unlock_irq(&cgwb_lock);
683 while (cleanup_offline_cgwb(wb))
685 spin_lock_irq(&cgwb_lock);
690 if (!list_empty(&processed))
691 list_splice_tail(&processed, &offline_cgwbs);
693 spin_unlock_irq(&cgwb_lock);
697 * wb_memcg_offline - kill all wb's associated with a memcg being offlined
698 * @memcg: memcg being offlined
700 * Also prevents creation of any new wb's associated with @memcg.
702 void wb_memcg_offline(struct mem_cgroup *memcg)
704 struct list_head *memcg_cgwb_list = &memcg->cgwb_list;
705 struct bdi_writeback *wb, *next;
707 spin_lock_irq(&cgwb_lock);
708 list_for_each_entry_safe(wb, next, memcg_cgwb_list, memcg_node)
710 memcg_cgwb_list->next = NULL; /* prevent new wb's */
711 spin_unlock_irq(&cgwb_lock);
713 queue_work(system_unbound_wq, &cleanup_offline_cgwbs_work);
717 * wb_blkcg_offline - kill all wb's associated with a blkcg being offlined
718 * @css: blkcg being offlined
720 * Also prevents creation of any new wb's associated with @blkcg.
722 void wb_blkcg_offline(struct cgroup_subsys_state *css)
724 struct bdi_writeback *wb, *next;
725 struct list_head *list = blkcg_get_cgwb_list(css);
727 spin_lock_irq(&cgwb_lock);
728 list_for_each_entry_safe(wb, next, list, blkcg_node)
730 list->next = NULL; /* prevent new wb's */
731 spin_unlock_irq(&cgwb_lock);
734 static void cgwb_bdi_register(struct backing_dev_info *bdi)
736 spin_lock_irq(&cgwb_lock);
737 list_add_tail_rcu(&bdi->wb.bdi_node, &bdi->wb_list);
738 spin_unlock_irq(&cgwb_lock);
741 static int __init cgwb_init(void)
744 * There can be many concurrent release work items overwhelming
745 * system_wq. Put them in a separate wq and limit concurrency.
746 * There's no point in executing many of these in parallel.
748 cgwb_release_wq = alloc_workqueue("cgwb_release", 0, 1);
749 if (!cgwb_release_wq)
754 subsys_initcall(cgwb_init);
756 #else /* CONFIG_CGROUP_WRITEBACK */
758 static int cgwb_bdi_init(struct backing_dev_info *bdi)
760 return wb_init(&bdi->wb, bdi, GFP_KERNEL);
763 static void cgwb_bdi_unregister(struct backing_dev_info *bdi) { }
765 static void cgwb_bdi_register(struct backing_dev_info *bdi)
767 list_add_tail_rcu(&bdi->wb.bdi_node, &bdi->wb_list);
770 static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb)
772 list_del_rcu(&wb->bdi_node);
775 #endif /* CONFIG_CGROUP_WRITEBACK */
777 int bdi_init(struct backing_dev_info *bdi)
783 kref_init(&bdi->refcnt);
785 bdi->max_ratio = 100;
786 bdi->max_prop_frac = FPROP_FRAC_BASE;
787 INIT_LIST_HEAD(&bdi->bdi_list);
788 INIT_LIST_HEAD(&bdi->wb_list);
789 init_waitqueue_head(&bdi->wb_waitq);
791 ret = cgwb_bdi_init(bdi);
796 struct backing_dev_info *bdi_alloc(int node_id)
798 struct backing_dev_info *bdi;
800 bdi = kzalloc_node(sizeof(*bdi), GFP_KERNEL, node_id);
808 bdi->capabilities = BDI_CAP_WRITEBACK | BDI_CAP_WRITEBACK_ACCT;
809 bdi->ra_pages = VM_READAHEAD_PAGES;
810 bdi->io_pages = VM_READAHEAD_PAGES;
811 timer_setup(&bdi->laptop_mode_wb_timer, laptop_mode_timer_fn, 0);
814 EXPORT_SYMBOL(bdi_alloc);
816 static struct rb_node **bdi_lookup_rb_node(u64 id, struct rb_node **parentp)
818 struct rb_node **p = &bdi_tree.rb_node;
819 struct rb_node *parent = NULL;
820 struct backing_dev_info *bdi;
822 lockdep_assert_held(&bdi_lock);
826 bdi = rb_entry(parent, struct backing_dev_info, rb_node);
830 else if (bdi->id < id)
842 * bdi_get_by_id - lookup and get bdi from its id
843 * @id: bdi id to lookup
845 * Find bdi matching @id and get it. Returns NULL if the matching bdi
846 * doesn't exist or is already unregistered.
848 struct backing_dev_info *bdi_get_by_id(u64 id)
850 struct backing_dev_info *bdi = NULL;
853 spin_lock_bh(&bdi_lock);
854 p = bdi_lookup_rb_node(id, NULL);
856 bdi = rb_entry(*p, struct backing_dev_info, rb_node);
859 spin_unlock_bh(&bdi_lock);
864 int bdi_register_va(struct backing_dev_info *bdi, const char *fmt, va_list args)
867 struct rb_node *parent, **p;
869 if (bdi->dev) /* The driver needs to use separate queues per device */
872 vsnprintf(bdi->dev_name, sizeof(bdi->dev_name), fmt, args);
873 dev = device_create(bdi_class, NULL, MKDEV(0, 0), bdi, bdi->dev_name);
877 cgwb_bdi_register(bdi);
880 bdi_debug_register(bdi, dev_name(dev));
881 set_bit(WB_registered, &bdi->wb.state);
883 spin_lock_bh(&bdi_lock);
885 bdi->id = ++bdi_id_cursor;
887 p = bdi_lookup_rb_node(bdi->id, &parent);
888 rb_link_node(&bdi->rb_node, parent, p);
889 rb_insert_color(&bdi->rb_node, &bdi_tree);
891 list_add_tail_rcu(&bdi->bdi_list, &bdi_list);
893 spin_unlock_bh(&bdi_lock);
895 trace_writeback_bdi_register(bdi);
899 int bdi_register(struct backing_dev_info *bdi, const char *fmt, ...)
905 ret = bdi_register_va(bdi, fmt, args);
909 EXPORT_SYMBOL(bdi_register);
911 void bdi_set_owner(struct backing_dev_info *bdi, struct device *owner)
913 WARN_ON_ONCE(bdi->owner);
919 * Remove bdi from bdi_list, and ensure that it is no longer visible
921 static void bdi_remove_from_list(struct backing_dev_info *bdi)
923 spin_lock_bh(&bdi_lock);
924 rb_erase(&bdi->rb_node, &bdi_tree);
925 list_del_rcu(&bdi->bdi_list);
926 spin_unlock_bh(&bdi_lock);
928 synchronize_rcu_expedited();
931 void bdi_unregister(struct backing_dev_info *bdi)
933 del_timer_sync(&bdi->laptop_mode_wb_timer);
935 /* make sure nobody finds us on the bdi_list anymore */
936 bdi_remove_from_list(bdi);
937 wb_shutdown(&bdi->wb);
938 cgwb_bdi_unregister(bdi);
941 * If this BDI's min ratio has been set, use bdi_set_min_ratio() to
942 * update the global bdi_min_ratio.
945 bdi_set_min_ratio(bdi, 0);
948 bdi_debug_unregister(bdi);
949 device_unregister(bdi->dev);
954 put_device(bdi->owner);
958 EXPORT_SYMBOL(bdi_unregister);
960 static void release_bdi(struct kref *ref)
962 struct backing_dev_info *bdi =
963 container_of(ref, struct backing_dev_info, refcnt);
965 WARN_ON_ONCE(test_bit(WB_registered, &bdi->wb.state));
966 WARN_ON_ONCE(bdi->dev);
971 void bdi_put(struct backing_dev_info *bdi)
973 kref_put(&bdi->refcnt, release_bdi);
975 EXPORT_SYMBOL(bdi_put);
977 struct backing_dev_info *inode_to_bdi(struct inode *inode)
979 struct super_block *sb;
982 return &noop_backing_dev_info;
986 if (sb_is_blkdev_sb(sb))
987 return I_BDEV(inode)->bd_disk->bdi;
991 EXPORT_SYMBOL(inode_to_bdi);
993 const char *bdi_dev_name(struct backing_dev_info *bdi)
995 if (!bdi || !bdi->dev)
996 return bdi_unknown_name;
997 return bdi->dev_name;
999 EXPORT_SYMBOL_GPL(bdi_dev_name);