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/backing-dev.h>
6 : #include <linux/kthread.h>
7 : #include <linux/freezer.h>
8 : #include <linux/fs.h>
9 : #include <linux/pagemap.h>
10 : #include <linux/mm.h>
11 : #include <linux/sched/mm.h>
12 : #include <linux/sched.h>
13 : #include <linux/module.h>
14 : #include <linux/writeback.h>
15 : #include <linux/device.h>
16 : #include <trace/events/writeback.h>
17 :
18 : struct backing_dev_info noop_backing_dev_info;
19 : EXPORT_SYMBOL_GPL(noop_backing_dev_info);
20 :
21 : static struct class *bdi_class;
22 : static const char *bdi_unknown_name = "(unknown)";
23 :
24 : /*
25 : * bdi_lock protects bdi_tree and updates to bdi_list. bdi_list has RCU
26 : * reader side locking.
27 : */
28 : DEFINE_SPINLOCK(bdi_lock);
29 : static u64 bdi_id_cursor;
30 : static struct rb_root bdi_tree = RB_ROOT;
31 : LIST_HEAD(bdi_list);
32 :
33 : /* bdi_wq serves all asynchronous writeback tasks */
34 : struct workqueue_struct *bdi_wq;
35 :
36 : #define K(x) ((x) << (PAGE_SHIFT - 10))
37 :
38 : #ifdef CONFIG_DEBUG_FS
39 : #include <linux/debugfs.h>
40 : #include <linux/seq_file.h>
41 :
42 : static struct dentry *bdi_debug_root;
43 :
44 1 : static void bdi_debug_init(void)
45 : {
46 1 : bdi_debug_root = debugfs_create_dir("bdi", NULL);
47 1 : }
48 :
49 0 : static int bdi_debug_stats_show(struct seq_file *m, void *v)
50 : {
51 0 : struct backing_dev_info *bdi = m->private;
52 0 : struct bdi_writeback *wb = &bdi->wb;
53 0 : unsigned long background_thresh;
54 0 : unsigned long dirty_thresh;
55 0 : unsigned long wb_thresh;
56 0 : unsigned long nr_dirty, nr_io, nr_more_io, nr_dirty_time;
57 0 : struct inode *inode;
58 :
59 0 : nr_dirty = nr_io = nr_more_io = nr_dirty_time = 0;
60 0 : spin_lock(&wb->list_lock);
61 0 : list_for_each_entry(inode, &wb->b_dirty, i_io_list)
62 0 : nr_dirty++;
63 0 : list_for_each_entry(inode, &wb->b_io, i_io_list)
64 0 : nr_io++;
65 0 : list_for_each_entry(inode, &wb->b_more_io, i_io_list)
66 0 : nr_more_io++;
67 0 : list_for_each_entry(inode, &wb->b_dirty_time, i_io_list)
68 0 : if (inode->i_state & I_DIRTY_TIME)
69 0 : nr_dirty_time++;
70 0 : spin_unlock(&wb->list_lock);
71 :
72 0 : global_dirty_limits(&background_thresh, &dirty_thresh);
73 0 : wb_thresh = wb_calc_thresh(wb, dirty_thresh);
74 :
75 0 : seq_printf(m,
76 : "BdiWriteback: %10lu kB\n"
77 : "BdiReclaimable: %10lu kB\n"
78 : "BdiDirtyThresh: %10lu kB\n"
79 : "DirtyThresh: %10lu kB\n"
80 : "BackgroundThresh: %10lu kB\n"
81 : "BdiDirtied: %10lu kB\n"
82 : "BdiWritten: %10lu kB\n"
83 : "BdiWriteBandwidth: %10lu kBps\n"
84 : "b_dirty: %10lu\n"
85 : "b_io: %10lu\n"
86 : "b_more_io: %10lu\n"
87 : "b_dirty_time: %10lu\n"
88 : "bdi_list: %10u\n"
89 : "state: %10lx\n",
90 0 : (unsigned long) K(wb_stat(wb, WB_WRITEBACK)),
91 0 : (unsigned long) K(wb_stat(wb, WB_RECLAIMABLE)),
92 : K(wb_thresh),
93 : K(dirty_thresh),
94 : K(background_thresh),
95 0 : (unsigned long) K(wb_stat(wb, WB_DIRTIED)),
96 0 : (unsigned long) K(wb_stat(wb, WB_WRITTEN)),
97 0 : (unsigned long) K(wb->write_bandwidth),
98 : nr_dirty,
99 : nr_io,
100 : nr_more_io,
101 : nr_dirty_time,
102 0 : !list_empty(&bdi->bdi_list), bdi->wb.state);
103 :
104 0 : return 0;
105 : }
106 0 : DEFINE_SHOW_ATTRIBUTE(bdi_debug_stats);
107 :
108 9 : static void bdi_debug_register(struct backing_dev_info *bdi, const char *name)
109 : {
110 9 : bdi->debug_dir = debugfs_create_dir(name, bdi_debug_root);
111 :
112 9 : debugfs_create_file("stats", 0444, bdi->debug_dir, bdi,
113 : &bdi_debug_stats_fops);
114 9 : }
115 :
116 0 : static void bdi_debug_unregister(struct backing_dev_info *bdi)
117 : {
118 0 : debugfs_remove_recursive(bdi->debug_dir);
119 : }
120 : #else
121 : static inline void bdi_debug_init(void)
122 : {
123 : }
124 : static inline void bdi_debug_register(struct backing_dev_info *bdi,
125 : const char *name)
126 : {
127 : }
128 : static inline void bdi_debug_unregister(struct backing_dev_info *bdi)
129 : {
130 : }
131 : #endif
132 :
133 0 : static ssize_t read_ahead_kb_store(struct device *dev,
134 : struct device_attribute *attr,
135 : const char *buf, size_t count)
136 : {
137 0 : struct backing_dev_info *bdi = dev_get_drvdata(dev);
138 0 : unsigned long read_ahead_kb;
139 0 : ssize_t ret;
140 :
141 0 : ret = kstrtoul(buf, 10, &read_ahead_kb);
142 0 : if (ret < 0)
143 : return ret;
144 :
145 0 : bdi->ra_pages = read_ahead_kb >> (PAGE_SHIFT - 10);
146 :
147 0 : return count;
148 : }
149 :
150 : #define BDI_SHOW(name, expr) \
151 : static ssize_t name##_show(struct device *dev, \
152 : struct device_attribute *attr, char *buf) \
153 : { \
154 : struct backing_dev_info *bdi = dev_get_drvdata(dev); \
155 : \
156 : return sysfs_emit(buf, "%lld\n", (long long)expr); \
157 : } \
158 : static DEVICE_ATTR_RW(name);
159 :
160 0 : BDI_SHOW(read_ahead_kb, K(bdi->ra_pages))
161 :
162 0 : static ssize_t min_ratio_store(struct device *dev,
163 : struct device_attribute *attr, const char *buf, size_t count)
164 : {
165 0 : struct backing_dev_info *bdi = dev_get_drvdata(dev);
166 0 : unsigned int ratio;
167 0 : ssize_t ret;
168 :
169 0 : ret = kstrtouint(buf, 10, &ratio);
170 0 : if (ret < 0)
171 : return ret;
172 :
173 0 : ret = bdi_set_min_ratio(bdi, ratio);
174 0 : if (!ret)
175 0 : ret = count;
176 :
177 : return ret;
178 : }
179 0 : BDI_SHOW(min_ratio, bdi->min_ratio)
180 :
181 0 : static ssize_t max_ratio_store(struct device *dev,
182 : struct device_attribute *attr, const char *buf, size_t count)
183 : {
184 0 : struct backing_dev_info *bdi = dev_get_drvdata(dev);
185 0 : unsigned int ratio;
186 0 : ssize_t ret;
187 :
188 0 : ret = kstrtouint(buf, 10, &ratio);
189 0 : if (ret < 0)
190 : return ret;
191 :
192 0 : ret = bdi_set_max_ratio(bdi, ratio);
193 0 : if (!ret)
194 0 : ret = count;
195 :
196 : return ret;
197 : }
198 0 : BDI_SHOW(max_ratio, bdi->max_ratio)
199 :
200 0 : static ssize_t stable_pages_required_show(struct device *dev,
201 : struct device_attribute *attr,
202 : char *buf)
203 : {
204 0 : dev_warn_once(dev,
205 : "the stable_pages_required attribute has been removed. Use the stable_writes queue attribute instead.\n");
206 0 : return sysfs_emit(buf, "%d\n", 0);
207 : }
208 : static DEVICE_ATTR_RO(stable_pages_required);
209 :
210 : static struct attribute *bdi_dev_attrs[] = {
211 : &dev_attr_read_ahead_kb.attr,
212 : &dev_attr_min_ratio.attr,
213 : &dev_attr_max_ratio.attr,
214 : &dev_attr_stable_pages_required.attr,
215 : NULL,
216 : };
217 : ATTRIBUTE_GROUPS(bdi_dev);
218 :
219 1 : static __init int bdi_class_init(void)
220 : {
221 1 : bdi_class = class_create(THIS_MODULE, "bdi");
222 1 : if (IS_ERR(bdi_class))
223 0 : return PTR_ERR(bdi_class);
224 :
225 1 : bdi_class->dev_groups = bdi_dev_groups;
226 1 : bdi_debug_init();
227 :
228 1 : return 0;
229 : }
230 : postcore_initcall(bdi_class_init);
231 :
232 : static int bdi_init(struct backing_dev_info *bdi);
233 :
234 1 : static int __init default_bdi_init(void)
235 : {
236 1 : int err;
237 :
238 1 : bdi_wq = alloc_workqueue("writeback", WQ_MEM_RECLAIM | WQ_UNBOUND |
239 : WQ_SYSFS, 0);
240 1 : if (!bdi_wq)
241 : return -ENOMEM;
242 :
243 1 : err = bdi_init(&noop_backing_dev_info);
244 :
245 1 : return err;
246 : }
247 : subsys_initcall(default_bdi_init);
248 :
249 : /*
250 : * This function is used when the first inode for this wb is marked dirty. It
251 : * wakes-up the corresponding bdi thread which should then take care of the
252 : * periodic background write-out of dirty inodes. Since the write-out would
253 : * starts only 'dirty_writeback_interval' centisecs from now anyway, we just
254 : * set up a timer which wakes the bdi thread up later.
255 : *
256 : * Note, we wouldn't bother setting up the timer, but this function is on the
257 : * fast-path (used by '__mark_inode_dirty()'), so we save few context switches
258 : * by delaying the wake-up.
259 : *
260 : * We have to be careful not to postpone flush work if it is scheduled for
261 : * earlier. Thus we use queue_delayed_work().
262 : */
263 8 : void wb_wakeup_delayed(struct bdi_writeback *wb)
264 : {
265 8 : unsigned long timeout;
266 :
267 8 : timeout = msecs_to_jiffies(dirty_writeback_interval * 10);
268 8 : spin_lock_bh(&wb->work_lock);
269 8 : if (test_bit(WB_registered, &wb->state))
270 8 : queue_delayed_work(bdi_wq, &wb->dwork, timeout);
271 8 : spin_unlock_bh(&wb->work_lock);
272 8 : }
273 :
274 : /*
275 : * Initial write bandwidth: 100 MB/s
276 : */
277 : #define INIT_BW (100 << (20 - PAGE_SHIFT))
278 :
279 10 : static int wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi,
280 : gfp_t gfp)
281 : {
282 10 : int i, err;
283 :
284 10 : memset(wb, 0, sizeof(*wb));
285 :
286 10 : if (wb != &bdi->wb)
287 0 : bdi_get(bdi);
288 10 : wb->bdi = bdi;
289 10 : wb->last_old_flush = jiffies;
290 10 : INIT_LIST_HEAD(&wb->b_dirty);
291 10 : INIT_LIST_HEAD(&wb->b_io);
292 10 : INIT_LIST_HEAD(&wb->b_more_io);
293 10 : INIT_LIST_HEAD(&wb->b_dirty_time);
294 10 : spin_lock_init(&wb->list_lock);
295 :
296 10 : wb->bw_time_stamp = jiffies;
297 10 : wb->balanced_dirty_ratelimit = INIT_BW;
298 10 : wb->dirty_ratelimit = INIT_BW;
299 10 : wb->write_bandwidth = INIT_BW;
300 10 : wb->avg_write_bandwidth = INIT_BW;
301 :
302 10 : spin_lock_init(&wb->work_lock);
303 10 : INIT_LIST_HEAD(&wb->work_list);
304 10 : INIT_DELAYED_WORK(&wb->dwork, wb_workfn);
305 10 : wb->dirty_sleep = jiffies;
306 :
307 10 : err = fprop_local_init_percpu(&wb->completions, gfp);
308 10 : if (err)
309 0 : goto out_put_bdi;
310 :
311 50 : for (i = 0; i < NR_WB_STAT_ITEMS; i++) {
312 40 : err = percpu_counter_init(&wb->stat[i], 0, gfp);
313 40 : if (err)
314 0 : goto out_destroy_stat;
315 : }
316 :
317 : return 0;
318 :
319 0 : out_destroy_stat:
320 0 : while (i--)
321 0 : percpu_counter_destroy(&wb->stat[i]);
322 0 : fprop_local_destroy_percpu(&wb->completions);
323 0 : out_put_bdi:
324 0 : if (wb != &bdi->wb)
325 10 : bdi_put(bdi);
326 : return err;
327 : }
328 :
329 : static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb);
330 :
331 : /*
332 : * Remove bdi from the global list and shutdown any threads we have running
333 : */
334 0 : static void wb_shutdown(struct bdi_writeback *wb)
335 : {
336 : /* Make sure nobody queues further work */
337 0 : spin_lock_bh(&wb->work_lock);
338 0 : if (!test_and_clear_bit(WB_registered, &wb->state)) {
339 0 : spin_unlock_bh(&wb->work_lock);
340 0 : return;
341 : }
342 0 : spin_unlock_bh(&wb->work_lock);
343 :
344 0 : cgwb_remove_from_bdi_list(wb);
345 : /*
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.
349 : */
350 0 : mod_delayed_work(bdi_wq, &wb->dwork, 0);
351 0 : flush_delayed_work(&wb->dwork);
352 0 : WARN_ON(!list_empty(&wb->work_list));
353 : }
354 :
355 0 : static void wb_exit(struct bdi_writeback *wb)
356 : {
357 0 : int i;
358 :
359 0 : WARN_ON(delayed_work_pending(&wb->dwork));
360 :
361 0 : for (i = 0; i < NR_WB_STAT_ITEMS; i++)
362 0 : percpu_counter_destroy(&wb->stat[i]);
363 :
364 0 : fprop_local_destroy_percpu(&wb->completions);
365 0 : if (wb != &wb->bdi->wb)
366 0 : bdi_put(wb->bdi);
367 0 : }
368 :
369 : #ifdef CONFIG_CGROUP_WRITEBACK
370 :
371 : #include <linux/memcontrol.h>
372 :
373 : /*
374 : * cgwb_lock protects bdi->cgwb_tree, blkcg->cgwb_list, and memcg->cgwb_list.
375 : * bdi->cgwb_tree is also RCU protected.
376 : */
377 : static DEFINE_SPINLOCK(cgwb_lock);
378 : static struct workqueue_struct *cgwb_release_wq;
379 :
380 : static void cgwb_release_workfn(struct work_struct *work)
381 : {
382 : struct bdi_writeback *wb = container_of(work, struct bdi_writeback,
383 : release_work);
384 : struct blkcg *blkcg = css_to_blkcg(wb->blkcg_css);
385 :
386 : mutex_lock(&wb->bdi->cgwb_release_mutex);
387 : wb_shutdown(wb);
388 :
389 : css_put(wb->memcg_css);
390 : css_put(wb->blkcg_css);
391 : mutex_unlock(&wb->bdi->cgwb_release_mutex);
392 :
393 : /* triggers blkg destruction if no online users left */
394 : blkcg_unpin_online(blkcg);
395 :
396 : fprop_local_destroy_percpu(&wb->memcg_completions);
397 : percpu_ref_exit(&wb->refcnt);
398 : wb_exit(wb);
399 : kfree_rcu(wb, rcu);
400 : }
401 :
402 : static void cgwb_release(struct percpu_ref *refcnt)
403 : {
404 : struct bdi_writeback *wb = container_of(refcnt, struct bdi_writeback,
405 : refcnt);
406 : queue_work(cgwb_release_wq, &wb->release_work);
407 : }
408 :
409 : static void cgwb_kill(struct bdi_writeback *wb)
410 : {
411 : lockdep_assert_held(&cgwb_lock);
412 :
413 : WARN_ON(!radix_tree_delete(&wb->bdi->cgwb_tree, wb->memcg_css->id));
414 : list_del(&wb->memcg_node);
415 : list_del(&wb->blkcg_node);
416 : percpu_ref_kill(&wb->refcnt);
417 : }
418 :
419 : static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb)
420 : {
421 : spin_lock_irq(&cgwb_lock);
422 : list_del_rcu(&wb->bdi_node);
423 : spin_unlock_irq(&cgwb_lock);
424 : }
425 :
426 : static int cgwb_create(struct backing_dev_info *bdi,
427 : struct cgroup_subsys_state *memcg_css, gfp_t gfp)
428 : {
429 : struct mem_cgroup *memcg;
430 : struct cgroup_subsys_state *blkcg_css;
431 : struct blkcg *blkcg;
432 : struct list_head *memcg_cgwb_list, *blkcg_cgwb_list;
433 : struct bdi_writeback *wb;
434 : unsigned long flags;
435 : int ret = 0;
436 :
437 : memcg = mem_cgroup_from_css(memcg_css);
438 : blkcg_css = cgroup_get_e_css(memcg_css->cgroup, &io_cgrp_subsys);
439 : blkcg = css_to_blkcg(blkcg_css);
440 : memcg_cgwb_list = &memcg->cgwb_list;
441 : blkcg_cgwb_list = &blkcg->cgwb_list;
442 :
443 : /* look up again under lock and discard on blkcg mismatch */
444 : spin_lock_irqsave(&cgwb_lock, flags);
445 : wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id);
446 : if (wb && wb->blkcg_css != blkcg_css) {
447 : cgwb_kill(wb);
448 : wb = NULL;
449 : }
450 : spin_unlock_irqrestore(&cgwb_lock, flags);
451 : if (wb)
452 : goto out_put;
453 :
454 : /* need to create a new one */
455 : wb = kmalloc(sizeof(*wb), gfp);
456 : if (!wb) {
457 : ret = -ENOMEM;
458 : goto out_put;
459 : }
460 :
461 : ret = wb_init(wb, bdi, gfp);
462 : if (ret)
463 : goto err_free;
464 :
465 : ret = percpu_ref_init(&wb->refcnt, cgwb_release, 0, gfp);
466 : if (ret)
467 : goto err_wb_exit;
468 :
469 : ret = fprop_local_init_percpu(&wb->memcg_completions, gfp);
470 : if (ret)
471 : goto err_ref_exit;
472 :
473 : wb->memcg_css = memcg_css;
474 : wb->blkcg_css = blkcg_css;
475 : INIT_WORK(&wb->release_work, cgwb_release_workfn);
476 : set_bit(WB_registered, &wb->state);
477 :
478 : /*
479 : * The root wb determines the registered state of the whole bdi and
480 : * memcg_cgwb_list and blkcg_cgwb_list's next pointers indicate
481 : * whether they're still online. Don't link @wb if any is dead.
482 : * See wb_memcg_offline() and wb_blkcg_offline().
483 : */
484 : ret = -ENODEV;
485 : spin_lock_irqsave(&cgwb_lock, flags);
486 : if (test_bit(WB_registered, &bdi->wb.state) &&
487 : blkcg_cgwb_list->next && memcg_cgwb_list->next) {
488 : /* we might have raced another instance of this function */
489 : ret = radix_tree_insert(&bdi->cgwb_tree, memcg_css->id, wb);
490 : if (!ret) {
491 : list_add_tail_rcu(&wb->bdi_node, &bdi->wb_list);
492 : list_add(&wb->memcg_node, memcg_cgwb_list);
493 : list_add(&wb->blkcg_node, blkcg_cgwb_list);
494 : blkcg_pin_online(blkcg);
495 : css_get(memcg_css);
496 : css_get(blkcg_css);
497 : }
498 : }
499 : spin_unlock_irqrestore(&cgwb_lock, flags);
500 : if (ret) {
501 : if (ret == -EEXIST)
502 : ret = 0;
503 : goto err_fprop_exit;
504 : }
505 : goto out_put;
506 :
507 : err_fprop_exit:
508 : fprop_local_destroy_percpu(&wb->memcg_completions);
509 : err_ref_exit:
510 : percpu_ref_exit(&wb->refcnt);
511 : err_wb_exit:
512 : wb_exit(wb);
513 : err_free:
514 : kfree(wb);
515 : out_put:
516 : css_put(blkcg_css);
517 : return ret;
518 : }
519 :
520 : /**
521 : * wb_get_lookup - get wb for a given memcg
522 : * @bdi: target bdi
523 : * @memcg_css: cgroup_subsys_state of the target memcg (must have positive ref)
524 : *
525 : * Try to get the wb for @memcg_css on @bdi. The returned wb has its
526 : * refcount incremented.
527 : *
528 : * This function uses css_get() on @memcg_css and thus expects its refcnt
529 : * to be positive on invocation. IOW, rcu_read_lock() protection on
530 : * @memcg_css isn't enough. try_get it before calling this function.
531 : *
532 : * A wb is keyed by its associated memcg. As blkcg implicitly enables
533 : * memcg on the default hierarchy, memcg association is guaranteed to be
534 : * more specific (equal or descendant to the associated blkcg) and thus can
535 : * identify both the memcg and blkcg associations.
536 : *
537 : * Because the blkcg associated with a memcg may change as blkcg is enabled
538 : * and disabled closer to root in the hierarchy, each wb keeps track of
539 : * both the memcg and blkcg associated with it and verifies the blkcg on
540 : * each lookup. On mismatch, the existing wb is discarded and a new one is
541 : * created.
542 : */
543 : struct bdi_writeback *wb_get_lookup(struct backing_dev_info *bdi,
544 : struct cgroup_subsys_state *memcg_css)
545 : {
546 : struct bdi_writeback *wb;
547 :
548 : if (!memcg_css->parent)
549 : return &bdi->wb;
550 :
551 : rcu_read_lock();
552 : wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id);
553 : if (wb) {
554 : struct cgroup_subsys_state *blkcg_css;
555 :
556 : /* see whether the blkcg association has changed */
557 : blkcg_css = cgroup_get_e_css(memcg_css->cgroup, &io_cgrp_subsys);
558 : if (unlikely(wb->blkcg_css != blkcg_css || !wb_tryget(wb)))
559 : wb = NULL;
560 : css_put(blkcg_css);
561 : }
562 : rcu_read_unlock();
563 :
564 : return wb;
565 : }
566 :
567 : /**
568 : * wb_get_create - get wb for a given memcg, create if necessary
569 : * @bdi: target bdi
570 : * @memcg_css: cgroup_subsys_state of the target memcg (must have positive ref)
571 : * @gfp: allocation mask to use
572 : *
573 : * Try to get the wb for @memcg_css on @bdi. If it doesn't exist, try to
574 : * create one. See wb_get_lookup() for more details.
575 : */
576 : struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi,
577 : struct cgroup_subsys_state *memcg_css,
578 : gfp_t gfp)
579 : {
580 : struct bdi_writeback *wb;
581 :
582 : might_alloc(gfp);
583 :
584 : if (!memcg_css->parent)
585 : return &bdi->wb;
586 :
587 : do {
588 : wb = wb_get_lookup(bdi, memcg_css);
589 : } while (!wb && !cgwb_create(bdi, memcg_css, gfp));
590 :
591 : return wb;
592 : }
593 :
594 : static int cgwb_bdi_init(struct backing_dev_info *bdi)
595 : {
596 : int ret;
597 :
598 : INIT_RADIX_TREE(&bdi->cgwb_tree, GFP_ATOMIC);
599 : mutex_init(&bdi->cgwb_release_mutex);
600 : init_rwsem(&bdi->wb_switch_rwsem);
601 :
602 : ret = wb_init(&bdi->wb, bdi, GFP_KERNEL);
603 : if (!ret) {
604 : bdi->wb.memcg_css = &root_mem_cgroup->css;
605 : bdi->wb.blkcg_css = blkcg_root_css;
606 : }
607 : return ret;
608 : }
609 :
610 : static void cgwb_bdi_unregister(struct backing_dev_info *bdi)
611 : {
612 : struct radix_tree_iter iter;
613 : void **slot;
614 : struct bdi_writeback *wb;
615 :
616 : WARN_ON(test_bit(WB_registered, &bdi->wb.state));
617 :
618 : spin_lock_irq(&cgwb_lock);
619 : radix_tree_for_each_slot(slot, &bdi->cgwb_tree, &iter, 0)
620 : cgwb_kill(*slot);
621 : spin_unlock_irq(&cgwb_lock);
622 :
623 : mutex_lock(&bdi->cgwb_release_mutex);
624 : spin_lock_irq(&cgwb_lock);
625 : while (!list_empty(&bdi->wb_list)) {
626 : wb = list_first_entry(&bdi->wb_list, struct bdi_writeback,
627 : bdi_node);
628 : spin_unlock_irq(&cgwb_lock);
629 : wb_shutdown(wb);
630 : spin_lock_irq(&cgwb_lock);
631 : }
632 : spin_unlock_irq(&cgwb_lock);
633 : mutex_unlock(&bdi->cgwb_release_mutex);
634 : }
635 :
636 : /**
637 : * wb_memcg_offline - kill all wb's associated with a memcg being offlined
638 : * @memcg: memcg being offlined
639 : *
640 : * Also prevents creation of any new wb's associated with @memcg.
641 : */
642 : void wb_memcg_offline(struct mem_cgroup *memcg)
643 : {
644 : struct list_head *memcg_cgwb_list = &memcg->cgwb_list;
645 : struct bdi_writeback *wb, *next;
646 :
647 : spin_lock_irq(&cgwb_lock);
648 : list_for_each_entry_safe(wb, next, memcg_cgwb_list, memcg_node)
649 : cgwb_kill(wb);
650 : memcg_cgwb_list->next = NULL; /* prevent new wb's */
651 : spin_unlock_irq(&cgwb_lock);
652 : }
653 :
654 : /**
655 : * wb_blkcg_offline - kill all wb's associated with a blkcg being offlined
656 : * @blkcg: blkcg being offlined
657 : *
658 : * Also prevents creation of any new wb's associated with @blkcg.
659 : */
660 : void wb_blkcg_offline(struct blkcg *blkcg)
661 : {
662 : struct bdi_writeback *wb, *next;
663 :
664 : spin_lock_irq(&cgwb_lock);
665 : list_for_each_entry_safe(wb, next, &blkcg->cgwb_list, blkcg_node)
666 : cgwb_kill(wb);
667 : blkcg->cgwb_list.next = NULL; /* prevent new wb's */
668 : spin_unlock_irq(&cgwb_lock);
669 : }
670 :
671 : static void cgwb_bdi_register(struct backing_dev_info *bdi)
672 : {
673 : spin_lock_irq(&cgwb_lock);
674 : list_add_tail_rcu(&bdi->wb.bdi_node, &bdi->wb_list);
675 : spin_unlock_irq(&cgwb_lock);
676 : }
677 :
678 : static int __init cgwb_init(void)
679 : {
680 : /*
681 : * There can be many concurrent release work items overwhelming
682 : * system_wq. Put them in a separate wq and limit concurrency.
683 : * There's no point in executing many of these in parallel.
684 : */
685 : cgwb_release_wq = alloc_workqueue("cgwb_release", 0, 1);
686 : if (!cgwb_release_wq)
687 : return -ENOMEM;
688 :
689 : return 0;
690 : }
691 : subsys_initcall(cgwb_init);
692 :
693 : #else /* CONFIG_CGROUP_WRITEBACK */
694 :
695 10 : static int cgwb_bdi_init(struct backing_dev_info *bdi)
696 : {
697 10 : return wb_init(&bdi->wb, bdi, GFP_KERNEL);
698 : }
699 :
700 0 : static void cgwb_bdi_unregister(struct backing_dev_info *bdi) { }
701 :
702 9 : static void cgwb_bdi_register(struct backing_dev_info *bdi)
703 : {
704 18 : list_add_tail_rcu(&bdi->wb.bdi_node, &bdi->wb_list);
705 : }
706 :
707 0 : static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb)
708 : {
709 0 : list_del_rcu(&wb->bdi_node);
710 : }
711 :
712 : #endif /* CONFIG_CGROUP_WRITEBACK */
713 :
714 10 : static int bdi_init(struct backing_dev_info *bdi)
715 : {
716 10 : int ret;
717 :
718 10 : bdi->dev = NULL;
719 :
720 10 : kref_init(&bdi->refcnt);
721 10 : bdi->min_ratio = 0;
722 10 : bdi->max_ratio = 100;
723 10 : bdi->max_prop_frac = FPROP_FRAC_BASE;
724 10 : INIT_LIST_HEAD(&bdi->bdi_list);
725 10 : INIT_LIST_HEAD(&bdi->wb_list);
726 10 : init_waitqueue_head(&bdi->wb_waitq);
727 :
728 10 : ret = cgwb_bdi_init(bdi);
729 :
730 10 : return ret;
731 : }
732 :
733 9 : struct backing_dev_info *bdi_alloc(int node_id)
734 : {
735 9 : struct backing_dev_info *bdi;
736 :
737 9 : bdi = kzalloc_node(sizeof(*bdi), GFP_KERNEL, node_id);
738 9 : if (!bdi)
739 : return NULL;
740 :
741 9 : if (bdi_init(bdi)) {
742 0 : kfree(bdi);
743 0 : return NULL;
744 : }
745 9 : bdi->capabilities = BDI_CAP_WRITEBACK | BDI_CAP_WRITEBACK_ACCT;
746 9 : bdi->ra_pages = VM_READAHEAD_PAGES;
747 9 : bdi->io_pages = VM_READAHEAD_PAGES;
748 9 : return bdi;
749 : }
750 : EXPORT_SYMBOL(bdi_alloc);
751 :
752 9 : static struct rb_node **bdi_lookup_rb_node(u64 id, struct rb_node **parentp)
753 : {
754 9 : struct rb_node **p = &bdi_tree.rb_node;
755 9 : struct rb_node *parent = NULL;
756 9 : struct backing_dev_info *bdi;
757 :
758 27 : lockdep_assert_held(&bdi_lock);
759 :
760 32 : while (*p) {
761 23 : parent = *p;
762 23 : bdi = rb_entry(parent, struct backing_dev_info, rb_node);
763 :
764 23 : if (bdi->id > id)
765 0 : p = &(*p)->rb_left;
766 23 : else if (bdi->id < id)
767 23 : p = &(*p)->rb_right;
768 : else
769 : break;
770 : }
771 :
772 9 : if (parentp)
773 9 : *parentp = parent;
774 9 : return p;
775 : }
776 :
777 : /**
778 : * bdi_get_by_id - lookup and get bdi from its id
779 : * @id: bdi id to lookup
780 : *
781 : * Find bdi matching @id and get it. Returns NULL if the matching bdi
782 : * doesn't exist or is already unregistered.
783 : */
784 0 : struct backing_dev_info *bdi_get_by_id(u64 id)
785 : {
786 0 : struct backing_dev_info *bdi = NULL;
787 0 : struct rb_node **p;
788 :
789 0 : spin_lock_bh(&bdi_lock);
790 0 : p = bdi_lookup_rb_node(id, NULL);
791 0 : if (*p) {
792 0 : bdi = rb_entry(*p, struct backing_dev_info, rb_node);
793 0 : bdi_get(bdi);
794 : }
795 0 : spin_unlock_bh(&bdi_lock);
796 :
797 0 : return bdi;
798 : }
799 :
800 9 : int bdi_register_va(struct backing_dev_info *bdi, const char *fmt, va_list args)
801 : {
802 9 : struct device *dev;
803 9 : struct rb_node *parent, **p;
804 :
805 9 : if (bdi->dev) /* The driver needs to use separate queues per device */
806 : return 0;
807 :
808 9 : vsnprintf(bdi->dev_name, sizeof(bdi->dev_name), fmt, args);
809 9 : dev = device_create(bdi_class, NULL, MKDEV(0, 0), bdi, bdi->dev_name);
810 9 : if (IS_ERR(dev))
811 0 : return PTR_ERR(dev);
812 :
813 9 : cgwb_bdi_register(bdi);
814 9 : bdi->dev = dev;
815 :
816 18 : bdi_debug_register(bdi, dev_name(dev));
817 9 : set_bit(WB_registered, &bdi->wb.state);
818 :
819 9 : spin_lock_bh(&bdi_lock);
820 :
821 9 : bdi->id = ++bdi_id_cursor;
822 :
823 9 : p = bdi_lookup_rb_node(bdi->id, &parent);
824 9 : rb_link_node(&bdi->rb_node, parent, p);
825 9 : rb_insert_color(&bdi->rb_node, &bdi_tree);
826 :
827 9 : list_add_tail_rcu(&bdi->bdi_list, &bdi_list);
828 :
829 9 : spin_unlock_bh(&bdi_lock);
830 :
831 9 : trace_writeback_bdi_register(bdi);
832 9 : return 0;
833 : }
834 :
835 9 : int bdi_register(struct backing_dev_info *bdi, const char *fmt, ...)
836 : {
837 9 : va_list args;
838 9 : int ret;
839 :
840 9 : va_start(args, fmt);
841 9 : ret = bdi_register_va(bdi, fmt, args);
842 9 : va_end(args);
843 9 : return ret;
844 : }
845 : EXPORT_SYMBOL(bdi_register);
846 :
847 9 : void bdi_set_owner(struct backing_dev_info *bdi, struct device *owner)
848 : {
849 9 : WARN_ON_ONCE(bdi->owner);
850 9 : bdi->owner = owner;
851 9 : get_device(owner);
852 9 : }
853 :
854 : /*
855 : * Remove bdi from bdi_list, and ensure that it is no longer visible
856 : */
857 0 : static void bdi_remove_from_list(struct backing_dev_info *bdi)
858 : {
859 0 : spin_lock_bh(&bdi_lock);
860 0 : rb_erase(&bdi->rb_node, &bdi_tree);
861 0 : list_del_rcu(&bdi->bdi_list);
862 0 : spin_unlock_bh(&bdi_lock);
863 :
864 0 : synchronize_rcu_expedited();
865 0 : }
866 :
867 0 : void bdi_unregister(struct backing_dev_info *bdi)
868 : {
869 : /* make sure nobody finds us on the bdi_list anymore */
870 0 : bdi_remove_from_list(bdi);
871 0 : wb_shutdown(&bdi->wb);
872 0 : cgwb_bdi_unregister(bdi);
873 :
874 0 : if (bdi->dev) {
875 0 : bdi_debug_unregister(bdi);
876 0 : device_unregister(bdi->dev);
877 0 : bdi->dev = NULL;
878 : }
879 :
880 0 : if (bdi->owner) {
881 0 : put_device(bdi->owner);
882 0 : bdi->owner = NULL;
883 : }
884 0 : }
885 :
886 0 : static void release_bdi(struct kref *ref)
887 : {
888 0 : struct backing_dev_info *bdi =
889 0 : container_of(ref, struct backing_dev_info, refcnt);
890 :
891 0 : if (test_bit(WB_registered, &bdi->wb.state))
892 0 : bdi_unregister(bdi);
893 0 : WARN_ON_ONCE(bdi->dev);
894 0 : wb_exit(&bdi->wb);
895 0 : kfree(bdi);
896 0 : }
897 :
898 1 : void bdi_put(struct backing_dev_info *bdi)
899 : {
900 1 : kref_put(&bdi->refcnt, release_bdi);
901 0 : }
902 : EXPORT_SYMBOL(bdi_put);
903 :
904 7 : const char *bdi_dev_name(struct backing_dev_info *bdi)
905 : {
906 7 : if (!bdi || !bdi->dev)
907 0 : return bdi_unknown_name;
908 7 : return bdi->dev_name;
909 : }
910 : EXPORT_SYMBOL_GPL(bdi_dev_name);
911 :
912 : static wait_queue_head_t congestion_wqh[2] = {
913 : __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]),
914 : __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1])
915 : };
916 : static atomic_t nr_wb_congested[2];
917 :
918 0 : void clear_bdi_congested(struct backing_dev_info *bdi, int sync)
919 : {
920 0 : wait_queue_head_t *wqh = &congestion_wqh[sync];
921 0 : enum wb_congested_state bit;
922 :
923 0 : bit = sync ? WB_sync_congested : WB_async_congested;
924 0 : if (test_and_clear_bit(bit, &bdi->wb.congested))
925 0 : atomic_dec(&nr_wb_congested[sync]);
926 0 : smp_mb__after_atomic();
927 0 : if (waitqueue_active(wqh))
928 0 : wake_up(wqh);
929 0 : }
930 : EXPORT_SYMBOL(clear_bdi_congested);
931 :
932 0 : void set_bdi_congested(struct backing_dev_info *bdi, int sync)
933 : {
934 0 : enum wb_congested_state bit;
935 :
936 0 : bit = sync ? WB_sync_congested : WB_async_congested;
937 0 : if (!test_and_set_bit(bit, &bdi->wb.congested))
938 0 : atomic_inc(&nr_wb_congested[sync]);
939 0 : }
940 : EXPORT_SYMBOL(set_bdi_congested);
941 :
942 : /**
943 : * congestion_wait - wait for a backing_dev to become uncongested
944 : * @sync: SYNC or ASYNC IO
945 : * @timeout: timeout in jiffies
946 : *
947 : * Waits for up to @timeout jiffies for a backing_dev (any backing_dev) to exit
948 : * write congestion. If no backing_devs are congested then just wait for the
949 : * next write to be completed.
950 : */
951 0 : long congestion_wait(int sync, long timeout)
952 : {
953 0 : long ret;
954 0 : unsigned long start = jiffies;
955 0 : DEFINE_WAIT(wait);
956 0 : wait_queue_head_t *wqh = &congestion_wqh[sync];
957 :
958 0 : prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
959 0 : ret = io_schedule_timeout(timeout);
960 0 : finish_wait(wqh, &wait);
961 :
962 0 : trace_writeback_congestion_wait(jiffies_to_usecs(timeout),
963 : jiffies_to_usecs(jiffies - start));
964 :
965 0 : return ret;
966 : }
967 : EXPORT_SYMBOL(congestion_wait);
968 :
969 : /**
970 : * wait_iff_congested - Conditionally wait for a backing_dev to become uncongested or a pgdat to complete writes
971 : * @sync: SYNC or ASYNC IO
972 : * @timeout: timeout in jiffies
973 : *
974 : * In the event of a congested backing_dev (any backing_dev) this waits
975 : * for up to @timeout jiffies for either a BDI to exit congestion of the
976 : * given @sync queue or a write to complete.
977 : *
978 : * The return value is 0 if the sleep is for the full timeout. Otherwise,
979 : * it is the number of jiffies that were still remaining when the function
980 : * returned. return_value == timeout implies the function did not sleep.
981 : */
982 0 : long wait_iff_congested(int sync, long timeout)
983 : {
984 0 : long ret;
985 0 : unsigned long start = jiffies;
986 0 : DEFINE_WAIT(wait);
987 0 : wait_queue_head_t *wqh = &congestion_wqh[sync];
988 :
989 : /*
990 : * If there is no congestion, yield if necessary instead
991 : * of sleeping on the congestion queue
992 : */
993 0 : if (atomic_read(&nr_wb_congested[sync]) == 0) {
994 0 : cond_resched();
995 :
996 : /* In case we scheduled, work out time remaining */
997 0 : ret = timeout - (jiffies - start);
998 0 : if (ret < 0)
999 : ret = 0;
1000 :
1001 0 : goto out;
1002 : }
1003 :
1004 : /* Sleep until uncongested or a write happens */
1005 0 : prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
1006 0 : ret = io_schedule_timeout(timeout);
1007 0 : finish_wait(wqh, &wait);
1008 :
1009 0 : out:
1010 0 : trace_writeback_wait_iff_congested(jiffies_to_usecs(timeout),
1011 : jiffies_to_usecs(jiffies - start));
1012 :
1013 0 : return ret;
1014 : }
1015 : EXPORT_SYMBOL(wait_iff_congested);
|
