Line data Source code
1 : // SPDX-License-Identifier: GPL-2.0-only
2 :
3 : #include <linux/wait.h>
4 : #include <linux/rbtree.h>
5 : #include <linux/kthread.h>
6 : #include <linux/backing-dev.h>
7 : #include <linux/blk-cgroup.h>
8 : #include <linux/freezer.h>
9 : #include <linux/fs.h>
10 : #include <linux/pagemap.h>
11 : #include <linux/mm.h>
12 : #include <linux/sched/mm.h>
13 : #include <linux/sched.h>
14 : #include <linux/module.h>
15 : #include <linux/writeback.h>
16 : #include <linux/device.h>
17 : #include <trace/events/writeback.h>
18 :
19 : struct backing_dev_info noop_backing_dev_info;
20 : EXPORT_SYMBOL_GPL(noop_backing_dev_info);
21 :
22 : static struct class *bdi_class;
23 : static const char *bdi_unknown_name = "(unknown)";
24 :
25 : /*
26 : * bdi_lock protects bdi_tree and updates to bdi_list. bdi_list has RCU
27 : * reader side locking.
28 : */
29 : DEFINE_SPINLOCK(bdi_lock);
30 : static u64 bdi_id_cursor;
31 : static struct rb_root bdi_tree = RB_ROOT;
32 : LIST_HEAD(bdi_list);
33 :
34 : /* bdi_wq serves all asynchronous writeback tasks */
35 : struct workqueue_struct *bdi_wq;
36 :
37 : #define K(x) ((x) << (PAGE_SHIFT - 10))
38 :
39 : #ifdef CONFIG_DEBUG_FS
40 : #include <linux/debugfs.h>
41 : #include <linux/seq_file.h>
42 :
43 : static struct dentry *bdi_debug_root;
44 :
45 : static void bdi_debug_init(void)
46 : {
47 : bdi_debug_root = debugfs_create_dir("bdi", NULL);
48 : }
49 :
50 : static int bdi_debug_stats_show(struct seq_file *m, void *v)
51 : {
52 : struct backing_dev_info *bdi = m->private;
53 : struct bdi_writeback *wb = &bdi->wb;
54 : unsigned long background_thresh;
55 : unsigned long dirty_thresh;
56 : unsigned long wb_thresh;
57 : unsigned long nr_dirty, nr_io, nr_more_io, nr_dirty_time;
58 : struct inode *inode;
59 :
60 : nr_dirty = nr_io = nr_more_io = nr_dirty_time = 0;
61 : spin_lock(&wb->list_lock);
62 : list_for_each_entry(inode, &wb->b_dirty, i_io_list)
63 : nr_dirty++;
64 : list_for_each_entry(inode, &wb->b_io, i_io_list)
65 : nr_io++;
66 : list_for_each_entry(inode, &wb->b_more_io, i_io_list)
67 : nr_more_io++;
68 : list_for_each_entry(inode, &wb->b_dirty_time, i_io_list)
69 : if (inode->i_state & I_DIRTY_TIME)
70 : nr_dirty_time++;
71 : spin_unlock(&wb->list_lock);
72 :
73 : global_dirty_limits(&background_thresh, &dirty_thresh);
74 : wb_thresh = wb_calc_thresh(wb, dirty_thresh);
75 :
76 : seq_printf(m,
77 : "BdiWriteback: %10lu kB\n"
78 : "BdiReclaimable: %10lu kB\n"
79 : "BdiDirtyThresh: %10lu kB\n"
80 : "DirtyThresh: %10lu kB\n"
81 : "BackgroundThresh: %10lu kB\n"
82 : "BdiDirtied: %10lu kB\n"
83 : "BdiWritten: %10lu kB\n"
84 : "BdiWriteBandwidth: %10lu kBps\n"
85 : "b_dirty: %10lu\n"
86 : "b_io: %10lu\n"
87 : "b_more_io: %10lu\n"
88 : "b_dirty_time: %10lu\n"
89 : "bdi_list: %10u\n"
90 : "state: %10lx\n",
91 : (unsigned long) K(wb_stat(wb, WB_WRITEBACK)),
92 : (unsigned long) K(wb_stat(wb, WB_RECLAIMABLE)),
93 : K(wb_thresh),
94 : K(dirty_thresh),
95 : K(background_thresh),
96 : (unsigned long) K(wb_stat(wb, WB_DIRTIED)),
97 : (unsigned long) K(wb_stat(wb, WB_WRITTEN)),
98 : (unsigned long) K(wb->write_bandwidth),
99 : nr_dirty,
100 : nr_io,
101 : nr_more_io,
102 : nr_dirty_time,
103 : !list_empty(&bdi->bdi_list), bdi->wb.state);
104 :
105 : return 0;
106 : }
107 : DEFINE_SHOW_ATTRIBUTE(bdi_debug_stats);
108 :
109 : static void bdi_debug_register(struct backing_dev_info *bdi, const char *name)
110 : {
111 : bdi->debug_dir = debugfs_create_dir(name, bdi_debug_root);
112 :
113 : debugfs_create_file("stats", 0444, bdi->debug_dir, bdi,
114 : &bdi_debug_stats_fops);
115 : }
116 :
117 : static void bdi_debug_unregister(struct backing_dev_info *bdi)
118 : {
119 : debugfs_remove_recursive(bdi->debug_dir);
120 : }
121 : #else
122 : static inline void bdi_debug_init(void)
123 : {
124 : }
125 : static inline void bdi_debug_register(struct backing_dev_info *bdi,
126 : const char *name)
127 : {
128 : }
129 : static inline void bdi_debug_unregister(struct backing_dev_info *bdi)
130 : {
131 : }
132 : #endif
133 :
134 0 : static ssize_t read_ahead_kb_store(struct device *dev,
135 : struct device_attribute *attr,
136 : const char *buf, size_t count)
137 : {
138 0 : struct backing_dev_info *bdi = dev_get_drvdata(dev);
139 : unsigned long read_ahead_kb;
140 : ssize_t ret;
141 :
142 0 : ret = kstrtoul(buf, 10, &read_ahead_kb);
143 0 : if (ret < 0)
144 : return ret;
145 :
146 0 : bdi->ra_pages = read_ahead_kb >> (PAGE_SHIFT - 10);
147 :
148 0 : return count;
149 : }
150 :
151 : #define BDI_SHOW(name, expr) \
152 : static ssize_t name##_show(struct device *dev, \
153 : struct device_attribute *attr, char *buf) \
154 : { \
155 : struct backing_dev_info *bdi = dev_get_drvdata(dev); \
156 : \
157 : return sysfs_emit(buf, "%lld\n", (long long)expr); \
158 : } \
159 : static DEVICE_ATTR_RW(name);
160 :
161 0 : BDI_SHOW(read_ahead_kb, K(bdi->ra_pages))
162 :
163 0 : static ssize_t min_ratio_store(struct device *dev,
164 : struct device_attribute *attr, const char *buf, size_t count)
165 : {
166 0 : struct backing_dev_info *bdi = dev_get_drvdata(dev);
167 : unsigned int ratio;
168 : ssize_t ret;
169 :
170 0 : ret = kstrtouint(buf, 10, &ratio);
171 0 : if (ret < 0)
172 : return ret;
173 :
174 0 : ret = bdi_set_min_ratio(bdi, ratio);
175 0 : if (!ret)
176 0 : ret = count;
177 :
178 : return ret;
179 : }
180 0 : BDI_SHOW(min_ratio, bdi->min_ratio)
181 :
182 0 : static ssize_t max_ratio_store(struct device *dev,
183 : struct device_attribute *attr, const char *buf, size_t count)
184 : {
185 0 : struct backing_dev_info *bdi = dev_get_drvdata(dev);
186 : unsigned int ratio;
187 : ssize_t ret;
188 :
189 0 : ret = kstrtouint(buf, 10, &ratio);
190 0 : if (ret < 0)
191 : return ret;
192 :
193 0 : ret = bdi_set_max_ratio(bdi, ratio);
194 0 : if (!ret)
195 0 : ret = count;
196 :
197 : return ret;
198 : }
199 0 : BDI_SHOW(max_ratio, bdi->max_ratio)
200 :
201 0 : static ssize_t stable_pages_required_show(struct device *dev,
202 : struct device_attribute *attr,
203 : char *buf)
204 : {
205 0 : dev_warn_once(dev,
206 : "the stable_pages_required attribute has been removed. Use the stable_writes queue attribute instead.\n");
207 0 : return sysfs_emit(buf, "%d\n", 0);
208 : }
209 : static DEVICE_ATTR_RO(stable_pages_required);
210 :
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,
216 : NULL,
217 : };
218 : ATTRIBUTE_GROUPS(bdi_dev);
219 :
220 1 : static __init int bdi_class_init(void)
221 : {
222 1 : bdi_class = class_create(THIS_MODULE, "bdi");
223 2 : if (IS_ERR(bdi_class))
224 0 : return PTR_ERR(bdi_class);
225 :
226 1 : bdi_class->dev_groups = bdi_dev_groups;
227 : bdi_debug_init();
228 :
229 1 : return 0;
230 : }
231 : postcore_initcall(bdi_class_init);
232 :
233 : static int bdi_init(struct backing_dev_info *bdi);
234 :
235 1 : static int __init default_bdi_init(void)
236 : {
237 : int err;
238 :
239 1 : bdi_wq = alloc_workqueue("writeback", WQ_MEM_RECLAIM | WQ_UNBOUND |
240 : WQ_SYSFS, 0);
241 1 : if (!bdi_wq)
242 : return -ENOMEM;
243 :
244 1 : err = bdi_init(&noop_backing_dev_info);
245 :
246 1 : return err;
247 : }
248 : subsys_initcall(default_bdi_init);
249 :
250 : /*
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.
256 : *
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.
260 : *
261 : * We have to be careful not to postpone flush work if it is scheduled for
262 : * earlier. Thus we use queue_delayed_work().
263 : */
264 0 : void wb_wakeup_delayed(struct bdi_writeback *wb)
265 : {
266 : unsigned long timeout;
267 :
268 0 : timeout = msecs_to_jiffies(dirty_writeback_interval * 10);
269 0 : spin_lock_bh(&wb->work_lock);
270 0 : if (test_bit(WB_registered, &wb->state))
271 0 : queue_delayed_work(bdi_wq, &wb->dwork, timeout);
272 0 : spin_unlock_bh(&wb->work_lock);
273 0 : }
274 :
275 0 : static void wb_update_bandwidth_workfn(struct work_struct *work)
276 : {
277 0 : struct bdi_writeback *wb = container_of(to_delayed_work(work),
278 : struct bdi_writeback, bw_dwork);
279 :
280 0 : wb_update_bandwidth(wb);
281 0 : }
282 :
283 : /*
284 : * Initial write bandwidth: 100 MB/s
285 : */
286 : #define INIT_BW (100 << (20 - PAGE_SHIFT))
287 :
288 1 : static int wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi,
289 : gfp_t gfp)
290 : {
291 : int i, err;
292 :
293 1 : memset(wb, 0, sizeof(*wb));
294 :
295 1 : wb->bdi = bdi;
296 1 : wb->last_old_flush = jiffies;
297 2 : INIT_LIST_HEAD(&wb->b_dirty);
298 2 : INIT_LIST_HEAD(&wb->b_io);
299 2 : INIT_LIST_HEAD(&wb->b_more_io);
300 2 : INIT_LIST_HEAD(&wb->b_dirty_time);
301 1 : spin_lock_init(&wb->list_lock);
302 :
303 2 : atomic_set(&wb->writeback_inodes, 0);
304 1 : wb->bw_time_stamp = jiffies;
305 1 : wb->balanced_dirty_ratelimit = INIT_BW;
306 1 : wb->dirty_ratelimit = INIT_BW;
307 1 : wb->write_bandwidth = INIT_BW;
308 1 : wb->avg_write_bandwidth = INIT_BW;
309 :
310 1 : spin_lock_init(&wb->work_lock);
311 2 : INIT_LIST_HEAD(&wb->work_list);
312 2 : INIT_DELAYED_WORK(&wb->dwork, wb_workfn);
313 2 : INIT_DELAYED_WORK(&wb->bw_dwork, wb_update_bandwidth_workfn);
314 1 : wb->dirty_sleep = jiffies;
315 :
316 1 : err = fprop_local_init_percpu(&wb->completions, gfp);
317 1 : if (err)
318 : return err;
319 :
320 4 : for (i = 0; i < NR_WB_STAT_ITEMS; i++) {
321 8 : err = percpu_counter_init(&wb->stat[i], 0, gfp);
322 : if (err)
323 : goto out_destroy_stat;
324 : }
325 :
326 : return 0;
327 :
328 : out_destroy_stat:
329 : while (i--)
330 : percpu_counter_destroy(&wb->stat[i]);
331 : fprop_local_destroy_percpu(&wb->completions);
332 : return err;
333 : }
334 :
335 : static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb);
336 :
337 : /*
338 : * Remove bdi from the global list and shutdown any threads we have running
339 : */
340 0 : static void wb_shutdown(struct bdi_writeback *wb)
341 : {
342 : /* Make sure nobody queues further work */
343 0 : spin_lock_bh(&wb->work_lock);
344 0 : if (!test_and_clear_bit(WB_registered, &wb->state)) {
345 0 : spin_unlock_bh(&wb->work_lock);
346 : return;
347 : }
348 0 : spin_unlock_bh(&wb->work_lock);
349 :
350 0 : cgwb_remove_from_bdi_list(wb);
351 : /*
352 : * Drain work list and shutdown the delayed_work. !WB_registered
353 : * tells wb_workfn() that @wb is dying and its work_list needs to
354 : * be drained no matter what.
355 : */
356 0 : mod_delayed_work(bdi_wq, &wb->dwork, 0);
357 0 : flush_delayed_work(&wb->dwork);
358 0 : WARN_ON(!list_empty(&wb->work_list));
359 0 : flush_delayed_work(&wb->bw_dwork);
360 : }
361 :
362 0 : static void wb_exit(struct bdi_writeback *wb)
363 : {
364 : int i;
365 :
366 0 : WARN_ON(delayed_work_pending(&wb->dwork));
367 :
368 : for (i = 0; i < NR_WB_STAT_ITEMS; i++)
369 : percpu_counter_destroy(&wb->stat[i]);
370 :
371 0 : fprop_local_destroy_percpu(&wb->completions);
372 0 : }
373 :
374 : #ifdef CONFIG_CGROUP_WRITEBACK
375 :
376 : #include <linux/memcontrol.h>
377 :
378 : /*
379 : * cgwb_lock protects bdi->cgwb_tree, blkcg->cgwb_list, offline_cgwbs and
380 : * memcg->cgwb_list. bdi->cgwb_tree is also RCU protected.
381 : */
382 : static DEFINE_SPINLOCK(cgwb_lock);
383 : static struct workqueue_struct *cgwb_release_wq;
384 :
385 : static LIST_HEAD(offline_cgwbs);
386 : static void cleanup_offline_cgwbs_workfn(struct work_struct *work);
387 : static DECLARE_WORK(cleanup_offline_cgwbs_work, cleanup_offline_cgwbs_workfn);
388 :
389 : static void cgwb_release_workfn(struct work_struct *work)
390 : {
391 : struct bdi_writeback *wb = container_of(work, struct bdi_writeback,
392 : release_work);
393 : struct blkcg *blkcg = css_to_blkcg(wb->blkcg_css);
394 : struct backing_dev_info *bdi = wb->bdi;
395 :
396 : mutex_lock(&wb->bdi->cgwb_release_mutex);
397 : wb_shutdown(wb);
398 :
399 : css_put(wb->memcg_css);
400 : css_put(wb->blkcg_css);
401 : mutex_unlock(&wb->bdi->cgwb_release_mutex);
402 :
403 : /* triggers blkg destruction if no online users left */
404 : blkcg_unpin_online(blkcg);
405 :
406 : fprop_local_destroy_percpu(&wb->memcg_completions);
407 :
408 : spin_lock_irq(&cgwb_lock);
409 : list_del(&wb->offline_node);
410 : spin_unlock_irq(&cgwb_lock);
411 :
412 : percpu_ref_exit(&wb->refcnt);
413 : wb_exit(wb);
414 : bdi_put(bdi);
415 : WARN_ON_ONCE(!list_empty(&wb->b_attached));
416 : kfree_rcu(wb, rcu);
417 : }
418 :
419 : static void cgwb_release(struct percpu_ref *refcnt)
420 : {
421 : struct bdi_writeback *wb = container_of(refcnt, struct bdi_writeback,
422 : refcnt);
423 : queue_work(cgwb_release_wq, &wb->release_work);
424 : }
425 :
426 : static void cgwb_kill(struct bdi_writeback *wb)
427 : {
428 : lockdep_assert_held(&cgwb_lock);
429 :
430 : WARN_ON(!radix_tree_delete(&wb->bdi->cgwb_tree, wb->memcg_css->id));
431 : list_del(&wb->memcg_node);
432 : list_del(&wb->blkcg_node);
433 : list_add(&wb->offline_node, &offline_cgwbs);
434 : percpu_ref_kill(&wb->refcnt);
435 : }
436 :
437 : static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb)
438 : {
439 : spin_lock_irq(&cgwb_lock);
440 : list_del_rcu(&wb->bdi_node);
441 : spin_unlock_irq(&cgwb_lock);
442 : }
443 :
444 : static int cgwb_create(struct backing_dev_info *bdi,
445 : struct cgroup_subsys_state *memcg_css, gfp_t gfp)
446 : {
447 : struct mem_cgroup *memcg;
448 : struct cgroup_subsys_state *blkcg_css;
449 : struct blkcg *blkcg;
450 : struct list_head *memcg_cgwb_list, *blkcg_cgwb_list;
451 : struct bdi_writeback *wb;
452 : unsigned long flags;
453 : int ret = 0;
454 :
455 : memcg = mem_cgroup_from_css(memcg_css);
456 : blkcg_css = cgroup_get_e_css(memcg_css->cgroup, &io_cgrp_subsys);
457 : blkcg = css_to_blkcg(blkcg_css);
458 : memcg_cgwb_list = &memcg->cgwb_list;
459 : blkcg_cgwb_list = &blkcg->cgwb_list;
460 :
461 : /* look up again under lock and discard on blkcg mismatch */
462 : spin_lock_irqsave(&cgwb_lock, flags);
463 : wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id);
464 : if (wb && wb->blkcg_css != blkcg_css) {
465 : cgwb_kill(wb);
466 : wb = NULL;
467 : }
468 : spin_unlock_irqrestore(&cgwb_lock, flags);
469 : if (wb)
470 : goto out_put;
471 :
472 : /* need to create a new one */
473 : wb = kmalloc(sizeof(*wb), gfp);
474 : if (!wb) {
475 : ret = -ENOMEM;
476 : goto out_put;
477 : }
478 :
479 : ret = wb_init(wb, bdi, gfp);
480 : if (ret)
481 : goto err_free;
482 :
483 : ret = percpu_ref_init(&wb->refcnt, cgwb_release, 0, gfp);
484 : if (ret)
485 : goto err_wb_exit;
486 :
487 : ret = fprop_local_init_percpu(&wb->memcg_completions, gfp);
488 : if (ret)
489 : goto err_ref_exit;
490 :
491 : wb->memcg_css = memcg_css;
492 : wb->blkcg_css = blkcg_css;
493 : INIT_LIST_HEAD(&wb->b_attached);
494 : INIT_WORK(&wb->release_work, cgwb_release_workfn);
495 : set_bit(WB_registered, &wb->state);
496 : bdi_get(bdi);
497 :
498 : /*
499 : * The root wb determines the registered state of the whole bdi and
500 : * memcg_cgwb_list and blkcg_cgwb_list's next pointers indicate
501 : * whether they're still online. Don't link @wb if any is dead.
502 : * See wb_memcg_offline() and wb_blkcg_offline().
503 : */
504 : ret = -ENODEV;
505 : spin_lock_irqsave(&cgwb_lock, flags);
506 : if (test_bit(WB_registered, &bdi->wb.state) &&
507 : blkcg_cgwb_list->next && memcg_cgwb_list->next) {
508 : /* we might have raced another instance of this function */
509 : ret = radix_tree_insert(&bdi->cgwb_tree, memcg_css->id, wb);
510 : if (!ret) {
511 : list_add_tail_rcu(&wb->bdi_node, &bdi->wb_list);
512 : list_add(&wb->memcg_node, memcg_cgwb_list);
513 : list_add(&wb->blkcg_node, blkcg_cgwb_list);
514 : blkcg_pin_online(blkcg);
515 : css_get(memcg_css);
516 : css_get(blkcg_css);
517 : }
518 : }
519 : spin_unlock_irqrestore(&cgwb_lock, flags);
520 : if (ret) {
521 : if (ret == -EEXIST)
522 : ret = 0;
523 : goto err_fprop_exit;
524 : }
525 : goto out_put;
526 :
527 : err_fprop_exit:
528 : bdi_put(bdi);
529 : fprop_local_destroy_percpu(&wb->memcg_completions);
530 : err_ref_exit:
531 : percpu_ref_exit(&wb->refcnt);
532 : err_wb_exit:
533 : wb_exit(wb);
534 : err_free:
535 : kfree(wb);
536 : out_put:
537 : css_put(blkcg_css);
538 : return ret;
539 : }
540 :
541 : /**
542 : * wb_get_lookup - get wb for a given memcg
543 : * @bdi: target bdi
544 : * @memcg_css: cgroup_subsys_state of the target memcg (must have positive ref)
545 : *
546 : * Try to get the wb for @memcg_css on @bdi. The returned wb has its
547 : * refcount incremented.
548 : *
549 : * This function uses css_get() on @memcg_css and thus expects its refcnt
550 : * to be positive on invocation. IOW, rcu_read_lock() protection on
551 : * @memcg_css isn't enough. try_get it before calling this function.
552 : *
553 : * A wb is keyed by its associated memcg. As blkcg implicitly enables
554 : * memcg on the default hierarchy, memcg association is guaranteed to be
555 : * more specific (equal or descendant to the associated blkcg) and thus can
556 : * identify both the memcg and blkcg associations.
557 : *
558 : * Because the blkcg associated with a memcg may change as blkcg is enabled
559 : * and disabled closer to root in the hierarchy, each wb keeps track of
560 : * both the memcg and blkcg associated with it and verifies the blkcg on
561 : * each lookup. On mismatch, the existing wb is discarded and a new one is
562 : * created.
563 : */
564 : struct bdi_writeback *wb_get_lookup(struct backing_dev_info *bdi,
565 : struct cgroup_subsys_state *memcg_css)
566 : {
567 : struct bdi_writeback *wb;
568 :
569 : if (!memcg_css->parent)
570 : return &bdi->wb;
571 :
572 : rcu_read_lock();
573 : wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id);
574 : if (wb) {
575 : struct cgroup_subsys_state *blkcg_css;
576 :
577 : /* see whether the blkcg association has changed */
578 : blkcg_css = cgroup_get_e_css(memcg_css->cgroup, &io_cgrp_subsys);
579 : if (unlikely(wb->blkcg_css != blkcg_css || !wb_tryget(wb)))
580 : wb = NULL;
581 : css_put(blkcg_css);
582 : }
583 : rcu_read_unlock();
584 :
585 : return wb;
586 : }
587 :
588 : /**
589 : * wb_get_create - get wb for a given memcg, create if necessary
590 : * @bdi: target bdi
591 : * @memcg_css: cgroup_subsys_state of the target memcg (must have positive ref)
592 : * @gfp: allocation mask to use
593 : *
594 : * Try to get the wb for @memcg_css on @bdi. If it doesn't exist, try to
595 : * create one. See wb_get_lookup() for more details.
596 : */
597 : struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi,
598 : struct cgroup_subsys_state *memcg_css,
599 : gfp_t gfp)
600 : {
601 : struct bdi_writeback *wb;
602 :
603 : might_alloc(gfp);
604 :
605 : if (!memcg_css->parent)
606 : return &bdi->wb;
607 :
608 : do {
609 : wb = wb_get_lookup(bdi, memcg_css);
610 : } while (!wb && !cgwb_create(bdi, memcg_css, gfp));
611 :
612 : return wb;
613 : }
614 :
615 : static int cgwb_bdi_init(struct backing_dev_info *bdi)
616 : {
617 : int ret;
618 :
619 : INIT_RADIX_TREE(&bdi->cgwb_tree, GFP_ATOMIC);
620 : mutex_init(&bdi->cgwb_release_mutex);
621 : init_rwsem(&bdi->wb_switch_rwsem);
622 :
623 : ret = wb_init(&bdi->wb, bdi, GFP_KERNEL);
624 : if (!ret) {
625 : bdi->wb.memcg_css = &root_mem_cgroup->css;
626 : bdi->wb.blkcg_css = blkcg_root_css;
627 : }
628 : return ret;
629 : }
630 :
631 : static void cgwb_bdi_unregister(struct backing_dev_info *bdi)
632 : {
633 : struct radix_tree_iter iter;
634 : void **slot;
635 : struct bdi_writeback *wb;
636 :
637 : WARN_ON(test_bit(WB_registered, &bdi->wb.state));
638 :
639 : spin_lock_irq(&cgwb_lock);
640 : radix_tree_for_each_slot(slot, &bdi->cgwb_tree, &iter, 0)
641 : cgwb_kill(*slot);
642 : spin_unlock_irq(&cgwb_lock);
643 :
644 : mutex_lock(&bdi->cgwb_release_mutex);
645 : spin_lock_irq(&cgwb_lock);
646 : while (!list_empty(&bdi->wb_list)) {
647 : wb = list_first_entry(&bdi->wb_list, struct bdi_writeback,
648 : bdi_node);
649 : spin_unlock_irq(&cgwb_lock);
650 : wb_shutdown(wb);
651 : spin_lock_irq(&cgwb_lock);
652 : }
653 : spin_unlock_irq(&cgwb_lock);
654 : mutex_unlock(&bdi->cgwb_release_mutex);
655 : }
656 :
657 : /*
658 : * cleanup_offline_cgwbs_workfn - try to release dying cgwbs
659 : *
660 : * Try to release dying cgwbs by switching attached inodes to the nearest
661 : * living ancestor's writeback. Processed wbs are placed at the end
662 : * of the list to guarantee the forward progress.
663 : */
664 : static void cleanup_offline_cgwbs_workfn(struct work_struct *work)
665 : {
666 : struct bdi_writeback *wb;
667 : LIST_HEAD(processed);
668 :
669 : spin_lock_irq(&cgwb_lock);
670 :
671 : while (!list_empty(&offline_cgwbs)) {
672 : wb = list_first_entry(&offline_cgwbs, struct bdi_writeback,
673 : offline_node);
674 : list_move(&wb->offline_node, &processed);
675 :
676 : /*
677 : * If wb is dirty, cleaning up the writeback by switching
678 : * attached inodes will result in an effective removal of any
679 : * bandwidth restrictions, which isn't the goal. Instead,
680 : * it can be postponed until the next time, when all io
681 : * will be likely completed. If in the meantime some inodes
682 : * will get re-dirtied, they should be eventually switched to
683 : * a new cgwb.
684 : */
685 : if (wb_has_dirty_io(wb))
686 : continue;
687 :
688 : if (!wb_tryget(wb))
689 : continue;
690 :
691 : spin_unlock_irq(&cgwb_lock);
692 : while (cleanup_offline_cgwb(wb))
693 : cond_resched();
694 : spin_lock_irq(&cgwb_lock);
695 :
696 : wb_put(wb);
697 : }
698 :
699 : if (!list_empty(&processed))
700 : list_splice_tail(&processed, &offline_cgwbs);
701 :
702 : spin_unlock_irq(&cgwb_lock);
703 : }
704 :
705 : /**
706 : * wb_memcg_offline - kill all wb's associated with a memcg being offlined
707 : * @memcg: memcg being offlined
708 : *
709 : * Also prevents creation of any new wb's associated with @memcg.
710 : */
711 : void wb_memcg_offline(struct mem_cgroup *memcg)
712 : {
713 : struct list_head *memcg_cgwb_list = &memcg->cgwb_list;
714 : struct bdi_writeback *wb, *next;
715 :
716 : spin_lock_irq(&cgwb_lock);
717 : list_for_each_entry_safe(wb, next, memcg_cgwb_list, memcg_node)
718 : cgwb_kill(wb);
719 : memcg_cgwb_list->next = NULL; /* prevent new wb's */
720 : spin_unlock_irq(&cgwb_lock);
721 :
722 : queue_work(system_unbound_wq, &cleanup_offline_cgwbs_work);
723 : }
724 :
725 : /**
726 : * wb_blkcg_offline - kill all wb's associated with a blkcg being offlined
727 : * @blkcg: blkcg being offlined
728 : *
729 : * Also prevents creation of any new wb's associated with @blkcg.
730 : */
731 : void wb_blkcg_offline(struct blkcg *blkcg)
732 : {
733 : struct bdi_writeback *wb, *next;
734 :
735 : spin_lock_irq(&cgwb_lock);
736 : list_for_each_entry_safe(wb, next, &blkcg->cgwb_list, blkcg_node)
737 : cgwb_kill(wb);
738 : blkcg->cgwb_list.next = NULL; /* prevent new wb's */
739 : spin_unlock_irq(&cgwb_lock);
740 : }
741 :
742 : static void cgwb_bdi_register(struct backing_dev_info *bdi)
743 : {
744 : spin_lock_irq(&cgwb_lock);
745 : list_add_tail_rcu(&bdi->wb.bdi_node, &bdi->wb_list);
746 : spin_unlock_irq(&cgwb_lock);
747 : }
748 :
749 : static int __init cgwb_init(void)
750 : {
751 : /*
752 : * There can be many concurrent release work items overwhelming
753 : * system_wq. Put them in a separate wq and limit concurrency.
754 : * There's no point in executing many of these in parallel.
755 : */
756 : cgwb_release_wq = alloc_workqueue("cgwb_release", 0, 1);
757 : if (!cgwb_release_wq)
758 : return -ENOMEM;
759 :
760 : return 0;
761 : }
762 : subsys_initcall(cgwb_init);
763 :
764 : #else /* CONFIG_CGROUP_WRITEBACK */
765 :
766 : static int cgwb_bdi_init(struct backing_dev_info *bdi)
767 : {
768 1 : return wb_init(&bdi->wb, bdi, GFP_KERNEL);
769 : }
770 :
771 : static void cgwb_bdi_unregister(struct backing_dev_info *bdi) { }
772 :
773 : static void cgwb_bdi_register(struct backing_dev_info *bdi)
774 : {
775 0 : list_add_tail_rcu(&bdi->wb.bdi_node, &bdi->wb_list);
776 : }
777 :
778 : static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb)
779 : {
780 0 : list_del_rcu(&wb->bdi_node);
781 : }
782 :
783 : #endif /* CONFIG_CGROUP_WRITEBACK */
784 :
785 1 : static int bdi_init(struct backing_dev_info *bdi)
786 : {
787 : int ret;
788 :
789 1 : bdi->dev = NULL;
790 :
791 2 : kref_init(&bdi->refcnt);
792 1 : bdi->min_ratio = 0;
793 1 : bdi->max_ratio = 100;
794 1 : bdi->max_prop_frac = FPROP_FRAC_BASE;
795 2 : INIT_LIST_HEAD(&bdi->bdi_list);
796 2 : INIT_LIST_HEAD(&bdi->wb_list);
797 1 : init_waitqueue_head(&bdi->wb_waitq);
798 :
799 1 : ret = cgwb_bdi_init(bdi);
800 :
801 1 : return ret;
802 : }
803 :
804 0 : struct backing_dev_info *bdi_alloc(int node_id)
805 : {
806 : struct backing_dev_info *bdi;
807 :
808 0 : bdi = kzalloc_node(sizeof(*bdi), GFP_KERNEL, node_id);
809 0 : if (!bdi)
810 : return NULL;
811 :
812 0 : if (bdi_init(bdi)) {
813 0 : kfree(bdi);
814 0 : return NULL;
815 : }
816 0 : bdi->capabilities = BDI_CAP_WRITEBACK | BDI_CAP_WRITEBACK_ACCT;
817 0 : bdi->ra_pages = VM_READAHEAD_PAGES;
818 0 : bdi->io_pages = VM_READAHEAD_PAGES;
819 0 : timer_setup(&bdi->laptop_mode_wb_timer, laptop_mode_timer_fn, 0);
820 0 : return bdi;
821 : }
822 : EXPORT_SYMBOL(bdi_alloc);
823 :
824 : static struct rb_node **bdi_lookup_rb_node(u64 id, struct rb_node **parentp)
825 : {
826 : struct rb_node **p = &bdi_tree.rb_node;
827 : struct rb_node *parent = NULL;
828 : struct backing_dev_info *bdi;
829 :
830 : lockdep_assert_held(&bdi_lock);
831 :
832 0 : while (*p) {
833 0 : parent = *p;
834 0 : bdi = rb_entry(parent, struct backing_dev_info, rb_node);
835 :
836 0 : if (bdi->id > id)
837 0 : p = &(*p)->rb_left;
838 0 : else if (bdi->id < id)
839 0 : p = &(*p)->rb_right;
840 : else
841 : break;
842 : }
843 :
844 : if (parentp)
845 0 : *parentp = parent;
846 : return p;
847 : }
848 :
849 : /**
850 : * bdi_get_by_id - lookup and get bdi from its id
851 : * @id: bdi id to lookup
852 : *
853 : * Find bdi matching @id and get it. Returns NULL if the matching bdi
854 : * doesn't exist or is already unregistered.
855 : */
856 0 : struct backing_dev_info *bdi_get_by_id(u64 id)
857 : {
858 0 : struct backing_dev_info *bdi = NULL;
859 : struct rb_node **p;
860 :
861 : spin_lock_bh(&bdi_lock);
862 0 : p = bdi_lookup_rb_node(id, NULL);
863 0 : if (*p) {
864 0 : bdi = rb_entry(*p, struct backing_dev_info, rb_node);
865 : bdi_get(bdi);
866 : }
867 0 : spin_unlock_bh(&bdi_lock);
868 :
869 0 : return bdi;
870 : }
871 :
872 0 : int bdi_register_va(struct backing_dev_info *bdi, const char *fmt, va_list args)
873 : {
874 : struct device *dev;
875 : struct rb_node *parent, **p;
876 :
877 0 : if (bdi->dev) /* The driver needs to use separate queues per device */
878 : return 0;
879 :
880 0 : vsnprintf(bdi->dev_name, sizeof(bdi->dev_name), fmt, args);
881 0 : dev = device_create(bdi_class, NULL, MKDEV(0, 0), bdi, bdi->dev_name);
882 0 : if (IS_ERR(dev))
883 0 : return PTR_ERR(dev);
884 :
885 0 : cgwb_bdi_register(bdi);
886 0 : bdi->dev = dev;
887 :
888 0 : bdi_debug_register(bdi, dev_name(dev));
889 0 : set_bit(WB_registered, &bdi->wb.state);
890 :
891 0 : spin_lock_bh(&bdi_lock);
892 :
893 0 : bdi->id = ++bdi_id_cursor;
894 :
895 0 : p = bdi_lookup_rb_node(bdi->id, &parent);
896 0 : rb_link_node(&bdi->rb_node, parent, p);
897 0 : rb_insert_color(&bdi->rb_node, &bdi_tree);
898 :
899 0 : list_add_tail_rcu(&bdi->bdi_list, &bdi_list);
900 :
901 0 : spin_unlock_bh(&bdi_lock);
902 :
903 0 : trace_writeback_bdi_register(bdi);
904 0 : return 0;
905 : }
906 :
907 0 : int bdi_register(struct backing_dev_info *bdi, const char *fmt, ...)
908 : {
909 : va_list args;
910 : int ret;
911 :
912 0 : va_start(args, fmt);
913 0 : ret = bdi_register_va(bdi, fmt, args);
914 0 : va_end(args);
915 0 : return ret;
916 : }
917 : EXPORT_SYMBOL(bdi_register);
918 :
919 0 : void bdi_set_owner(struct backing_dev_info *bdi, struct device *owner)
920 : {
921 0 : WARN_ON_ONCE(bdi->owner);
922 0 : bdi->owner = owner;
923 0 : get_device(owner);
924 0 : }
925 :
926 : /*
927 : * Remove bdi from bdi_list, and ensure that it is no longer visible
928 : */
929 0 : static void bdi_remove_from_list(struct backing_dev_info *bdi)
930 : {
931 0 : spin_lock_bh(&bdi_lock);
932 0 : rb_erase(&bdi->rb_node, &bdi_tree);
933 0 : list_del_rcu(&bdi->bdi_list);
934 0 : spin_unlock_bh(&bdi_lock);
935 :
936 : synchronize_rcu_expedited();
937 0 : }
938 :
939 0 : void bdi_unregister(struct backing_dev_info *bdi)
940 : {
941 0 : del_timer_sync(&bdi->laptop_mode_wb_timer);
942 :
943 : /* make sure nobody finds us on the bdi_list anymore */
944 0 : bdi_remove_from_list(bdi);
945 0 : wb_shutdown(&bdi->wb);
946 0 : cgwb_bdi_unregister(bdi);
947 :
948 : /*
949 : * If this BDI's min ratio has been set, use bdi_set_min_ratio() to
950 : * update the global bdi_min_ratio.
951 : */
952 0 : if (bdi->min_ratio)
953 0 : bdi_set_min_ratio(bdi, 0);
954 :
955 0 : if (bdi->dev) {
956 0 : bdi_debug_unregister(bdi);
957 0 : device_unregister(bdi->dev);
958 0 : bdi->dev = NULL;
959 : }
960 :
961 0 : if (bdi->owner) {
962 0 : put_device(bdi->owner);
963 0 : bdi->owner = NULL;
964 : }
965 0 : }
966 : EXPORT_SYMBOL(bdi_unregister);
967 :
968 0 : static void release_bdi(struct kref *ref)
969 : {
970 0 : struct backing_dev_info *bdi =
971 0 : container_of(ref, struct backing_dev_info, refcnt);
972 :
973 0 : WARN_ON_ONCE(test_bit(WB_registered, &bdi->wb.state));
974 0 : WARN_ON_ONCE(bdi->dev);
975 0 : wb_exit(&bdi->wb);
976 0 : kfree(bdi);
977 0 : }
978 :
979 0 : void bdi_put(struct backing_dev_info *bdi)
980 : {
981 0 : kref_put(&bdi->refcnt, release_bdi);
982 0 : }
983 : EXPORT_SYMBOL(bdi_put);
984 :
985 0 : struct backing_dev_info *inode_to_bdi(struct inode *inode)
986 : {
987 : struct super_block *sb;
988 :
989 0 : if (!inode)
990 : return &noop_backing_dev_info;
991 :
992 0 : sb = inode->i_sb;
993 : #ifdef CONFIG_BLOCK
994 0 : if (sb_is_blkdev_sb(sb))
995 0 : return I_BDEV(inode)->bd_disk->bdi;
996 : #endif
997 0 : return sb->s_bdi;
998 : }
999 : EXPORT_SYMBOL(inode_to_bdi);
1000 :
1001 0 : const char *bdi_dev_name(struct backing_dev_info *bdi)
1002 : {
1003 0 : if (!bdi || !bdi->dev)
1004 0 : return bdi_unknown_name;
1005 0 : return bdi->dev_name;
1006 : }
1007 : EXPORT_SYMBOL_GPL(bdi_dev_name);
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