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1 | |
2 | #include <linux/wait.h> |
3 | #include <linux/backing-dev.h> |
4 | #include <linux/kthread.h> |
5 | #include <linux/freezer.h> |
6 | #include <linux/fs.h> |
7 | #include <linux/pagemap.h> |
8 | #include <linux/mm.h> |
9 | #include <linux/sched.h> |
10 | #include <linux/module.h> |
11 | #include <linux/writeback.h> |
12 | #include <linux/device.h> |
13 | #include <trace/events/writeback.h> |
14 | |
15 | static atomic_long_t bdi_seq = ATOMIC_LONG_INIT(0); |
16 | |
17 | struct backing_dev_info default_backing_dev_info = { |
18 | .name = "default", |
19 | .ra_pages = VM_MAX_READAHEAD * 1024 / PAGE_CACHE_SIZE, |
20 | .state = 0, |
21 | .capabilities = BDI_CAP_MAP_COPY, |
22 | }; |
23 | EXPORT_SYMBOL_GPL(default_backing_dev_info); |
24 | |
25 | struct backing_dev_info noop_backing_dev_info = { |
26 | .name = "noop", |
27 | .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK, |
28 | }; |
29 | EXPORT_SYMBOL_GPL(noop_backing_dev_info); |
30 | |
31 | static struct class *bdi_class; |
32 | |
33 | /* |
34 | * bdi_lock protects updates to bdi_list and bdi_pending_list, as well as |
35 | * reader side protection for bdi_pending_list. bdi_list has RCU reader side |
36 | * locking. |
37 | */ |
38 | DEFINE_SPINLOCK(bdi_lock); |
39 | LIST_HEAD(bdi_list); |
40 | LIST_HEAD(bdi_pending_list); |
41 | |
42 | void bdi_lock_two(struct bdi_writeback *wb1, struct bdi_writeback *wb2) |
43 | { |
44 | if (wb1 < wb2) { |
45 | spin_lock(&wb1->list_lock); |
46 | spin_lock_nested(&wb2->list_lock, 1); |
47 | } else { |
48 | spin_lock(&wb2->list_lock); |
49 | spin_lock_nested(&wb1->list_lock, 1); |
50 | } |
51 | } |
52 | |
53 | #ifdef CONFIG_DEBUG_FS |
54 | #include <linux/debugfs.h> |
55 | #include <linux/seq_file.h> |
56 | |
57 | static struct dentry *bdi_debug_root; |
58 | |
59 | static void bdi_debug_init(void) |
60 | { |
61 | bdi_debug_root = debugfs_create_dir("bdi", NULL); |
62 | } |
63 | |
64 | static int bdi_debug_stats_show(struct seq_file *m, void *v) |
65 | { |
66 | struct backing_dev_info *bdi = m->private; |
67 | struct bdi_writeback *wb = &bdi->wb; |
68 | unsigned long background_thresh; |
69 | unsigned long dirty_thresh; |
70 | unsigned long bdi_thresh; |
71 | unsigned long nr_dirty, nr_io, nr_more_io; |
72 | struct inode *inode; |
73 | |
74 | nr_dirty = nr_io = nr_more_io = 0; |
75 | spin_lock(&wb->list_lock); |
76 | list_for_each_entry(inode, &wb->b_dirty, i_wb_list) |
77 | nr_dirty++; |
78 | list_for_each_entry(inode, &wb->b_io, i_wb_list) |
79 | nr_io++; |
80 | list_for_each_entry(inode, &wb->b_more_io, i_wb_list) |
81 | nr_more_io++; |
82 | spin_unlock(&wb->list_lock); |
83 | |
84 | global_dirty_limits(&background_thresh, &dirty_thresh); |
85 | bdi_thresh = bdi_dirty_limit(bdi, dirty_thresh); |
86 | |
87 | #define K(x) ((x) << (PAGE_SHIFT - 10)) |
88 | seq_printf(m, |
89 | "BdiWriteback: %10lu kB\n" |
90 | "BdiReclaimable: %10lu kB\n" |
91 | "BdiDirtyThresh: %10lu kB\n" |
92 | "DirtyThresh: %10lu kB\n" |
93 | "BackgroundThresh: %10lu kB\n" |
94 | "BdiDirtied: %10lu kB\n" |
95 | "BdiWritten: %10lu kB\n" |
96 | "BdiWriteBandwidth: %10lu kBps\n" |
97 | "b_dirty: %10lu\n" |
98 | "b_io: %10lu\n" |
99 | "b_more_io: %10lu\n" |
100 | "bdi_list: %10u\n" |
101 | "state: %10lx\n", |
102 | (unsigned long) K(bdi_stat(bdi, BDI_WRITEBACK)), |
103 | (unsigned long) K(bdi_stat(bdi, BDI_RECLAIMABLE)), |
104 | K(bdi_thresh), |
105 | K(dirty_thresh), |
106 | K(background_thresh), |
107 | (unsigned long) K(bdi_stat(bdi, BDI_DIRTIED)), |
108 | (unsigned long) K(bdi_stat(bdi, BDI_WRITTEN)), |
109 | (unsigned long) K(bdi->write_bandwidth), |
110 | nr_dirty, |
111 | nr_io, |
112 | nr_more_io, |
113 | !list_empty(&bdi->bdi_list), bdi->state); |
114 | #undef K |
115 | |
116 | return 0; |
117 | } |
118 | |
119 | static int bdi_debug_stats_open(struct inode *inode, struct file *file) |
120 | { |
121 | return single_open(file, bdi_debug_stats_show, inode->i_private); |
122 | } |
123 | |
124 | static const struct file_operations bdi_debug_stats_fops = { |
125 | .open = bdi_debug_stats_open, |
126 | .read = seq_read, |
127 | .llseek = seq_lseek, |
128 | .release = single_release, |
129 | }; |
130 | |
131 | static void bdi_debug_register(struct backing_dev_info *bdi, const char *name) |
132 | { |
133 | bdi->debug_dir = debugfs_create_dir(name, bdi_debug_root); |
134 | bdi->debug_stats = debugfs_create_file("stats", 0444, bdi->debug_dir, |
135 | bdi, &bdi_debug_stats_fops); |
136 | } |
137 | |
138 | static void bdi_debug_unregister(struct backing_dev_info *bdi) |
139 | { |
140 | debugfs_remove(bdi->debug_stats); |
141 | debugfs_remove(bdi->debug_dir); |
142 | } |
143 | #else |
144 | static inline void bdi_debug_init(void) |
145 | { |
146 | } |
147 | static inline void bdi_debug_register(struct backing_dev_info *bdi, |
148 | const char *name) |
149 | { |
150 | } |
151 | static inline void bdi_debug_unregister(struct backing_dev_info *bdi) |
152 | { |
153 | } |
154 | #endif |
155 | |
156 | static ssize_t read_ahead_kb_store(struct device *dev, |
157 | struct device_attribute *attr, |
158 | const char *buf, size_t count) |
159 | { |
160 | struct backing_dev_info *bdi = dev_get_drvdata(dev); |
161 | unsigned long read_ahead_kb; |
162 | ssize_t ret; |
163 | |
164 | ret = kstrtoul(buf, 10, &read_ahead_kb); |
165 | if (ret < 0) |
166 | return ret; |
167 | |
168 | bdi->ra_pages = read_ahead_kb >> (PAGE_SHIFT - 10); |
169 | |
170 | return count; |
171 | } |
172 | |
173 | #define K(pages) ((pages) << (PAGE_SHIFT - 10)) |
174 | |
175 | #define BDI_SHOW(name, expr) \ |
176 | static ssize_t name##_show(struct device *dev, \ |
177 | struct device_attribute *attr, char *page) \ |
178 | { \ |
179 | struct backing_dev_info *bdi = dev_get_drvdata(dev); \ |
180 | \ |
181 | return snprintf(page, PAGE_SIZE-1, "%lld\n", (long long)expr); \ |
182 | } |
183 | |
184 | BDI_SHOW(read_ahead_kb, K(bdi->ra_pages)) |
185 | |
186 | static ssize_t min_ratio_store(struct device *dev, |
187 | struct device_attribute *attr, const char *buf, size_t count) |
188 | { |
189 | struct backing_dev_info *bdi = dev_get_drvdata(dev); |
190 | unsigned int ratio; |
191 | ssize_t ret; |
192 | |
193 | ret = kstrtouint(buf, 10, &ratio); |
194 | if (ret < 0) |
195 | return ret; |
196 | |
197 | ret = bdi_set_min_ratio(bdi, ratio); |
198 | if (!ret) |
199 | ret = count; |
200 | |
201 | return ret; |
202 | } |
203 | BDI_SHOW(min_ratio, bdi->min_ratio) |
204 | |
205 | static ssize_t max_ratio_store(struct device *dev, |
206 | struct device_attribute *attr, const char *buf, size_t count) |
207 | { |
208 | struct backing_dev_info *bdi = dev_get_drvdata(dev); |
209 | unsigned int ratio; |
210 | ssize_t ret; |
211 | |
212 | ret = kstrtouint(buf, 10, &ratio); |
213 | if (ret < 0) |
214 | return ret; |
215 | |
216 | ret = bdi_set_max_ratio(bdi, ratio); |
217 | if (!ret) |
218 | ret = count; |
219 | |
220 | return ret; |
221 | } |
222 | BDI_SHOW(max_ratio, bdi->max_ratio) |
223 | |
224 | static ssize_t stable_pages_required_show(struct device *dev, |
225 | struct device_attribute *attr, |
226 | char *page) |
227 | { |
228 | struct backing_dev_info *bdi = dev_get_drvdata(dev); |
229 | |
230 | return snprintf(page, PAGE_SIZE-1, "%d\n", |
231 | bdi_cap_stable_pages_required(bdi) ? 1 : 0); |
232 | } |
233 | |
234 | #define __ATTR_RW(attr) __ATTR(attr, 0644, attr##_show, attr##_store) |
235 | |
236 | static struct device_attribute bdi_dev_attrs[] = { |
237 | __ATTR_RW(read_ahead_kb), |
238 | __ATTR_RW(min_ratio), |
239 | __ATTR_RW(max_ratio), |
240 | __ATTR_RO(stable_pages_required), |
241 | __ATTR_NULL, |
242 | }; |
243 | |
244 | static __init int bdi_class_init(void) |
245 | { |
246 | bdi_class = class_create(THIS_MODULE, "bdi"); |
247 | if (IS_ERR(bdi_class)) |
248 | return PTR_ERR(bdi_class); |
249 | |
250 | bdi_class->dev_attrs = bdi_dev_attrs; |
251 | bdi_debug_init(); |
252 | return 0; |
253 | } |
254 | postcore_initcall(bdi_class_init); |
255 | |
256 | static int __init default_bdi_init(void) |
257 | { |
258 | int err; |
259 | |
260 | err = bdi_init(&default_backing_dev_info); |
261 | if (!err) |
262 | bdi_register(&default_backing_dev_info, NULL, "default"); |
263 | err = bdi_init(&noop_backing_dev_info); |
264 | |
265 | return err; |
266 | } |
267 | subsys_initcall(default_bdi_init); |
268 | |
269 | int bdi_has_dirty_io(struct backing_dev_info *bdi) |
270 | { |
271 | return wb_has_dirty_io(&bdi->wb); |
272 | } |
273 | |
274 | static void wakeup_timer_fn(unsigned long data) |
275 | { |
276 | struct backing_dev_info *bdi = (struct backing_dev_info *)data; |
277 | |
278 | spin_lock_bh(&bdi->wb_lock); |
279 | if (bdi->wb.task) { |
280 | trace_writeback_wake_thread(bdi); |
281 | wake_up_process(bdi->wb.task); |
282 | } else if (bdi->dev) { |
283 | /* |
284 | * When bdi tasks are inactive for long time, they are killed. |
285 | * In this case we have to wake-up the forker thread which |
286 | * should create and run the bdi thread. |
287 | */ |
288 | trace_writeback_wake_forker_thread(bdi); |
289 | wake_up_process(default_backing_dev_info.wb.task); |
290 | } |
291 | spin_unlock_bh(&bdi->wb_lock); |
292 | } |
293 | |
294 | /* |
295 | * This function is used when the first inode for this bdi is marked dirty. It |
296 | * wakes-up the corresponding bdi thread which should then take care of the |
297 | * periodic background write-out of dirty inodes. Since the write-out would |
298 | * starts only 'dirty_writeback_interval' centisecs from now anyway, we just |
299 | * set up a timer which wakes the bdi thread up later. |
300 | * |
301 | * Note, we wouldn't bother setting up the timer, but this function is on the |
302 | * fast-path (used by '__mark_inode_dirty()'), so we save few context switches |
303 | * by delaying the wake-up. |
304 | */ |
305 | void bdi_wakeup_thread_delayed(struct backing_dev_info *bdi) |
306 | { |
307 | unsigned long timeout; |
308 | |
309 | timeout = msecs_to_jiffies(dirty_writeback_interval * 10); |
310 | mod_timer(&bdi->wb.wakeup_timer, jiffies + timeout); |
311 | } |
312 | |
313 | /* |
314 | * Calculate the longest interval (jiffies) bdi threads are allowed to be |
315 | * inactive. |
316 | */ |
317 | static unsigned long bdi_longest_inactive(void) |
318 | { |
319 | unsigned long interval; |
320 | |
321 | interval = msecs_to_jiffies(dirty_writeback_interval * 10); |
322 | return max(5UL * 60 * HZ, interval); |
323 | } |
324 | |
325 | /* |
326 | * Clear pending bit and wakeup anybody waiting for flusher thread creation or |
327 | * shutdown |
328 | */ |
329 | static void bdi_clear_pending(struct backing_dev_info *bdi) |
330 | { |
331 | clear_bit(BDI_pending, &bdi->state); |
332 | smp_mb__after_clear_bit(); |
333 | wake_up_bit(&bdi->state, BDI_pending); |
334 | } |
335 | |
336 | static int bdi_forker_thread(void *ptr) |
337 | { |
338 | struct bdi_writeback *me = ptr; |
339 | |
340 | current->flags |= PF_SWAPWRITE; |
341 | set_freezable(); |
342 | |
343 | /* |
344 | * Our parent may run at a different priority, just set us to normal |
345 | */ |
346 | set_user_nice(current, 0); |
347 | |
348 | for (;;) { |
349 | struct task_struct *task = NULL; |
350 | struct backing_dev_info *bdi; |
351 | enum { |
352 | NO_ACTION, /* Nothing to do */ |
353 | FORK_THREAD, /* Fork bdi thread */ |
354 | KILL_THREAD, /* Kill inactive bdi thread */ |
355 | } action = NO_ACTION; |
356 | |
357 | /* |
358 | * Temporary measure, we want to make sure we don't see |
359 | * dirty data on the default backing_dev_info |
360 | */ |
361 | if (wb_has_dirty_io(me) || !list_empty(&me->bdi->work_list)) { |
362 | del_timer(&me->wakeup_timer); |
363 | wb_do_writeback(me, 0); |
364 | } |
365 | |
366 | spin_lock_bh(&bdi_lock); |
367 | /* |
368 | * In the following loop we are going to check whether we have |
369 | * some work to do without any synchronization with tasks |
370 | * waking us up to do work for them. Set the task state here |
371 | * so that we don't miss wakeups after verifying conditions. |
372 | */ |
373 | set_current_state(TASK_INTERRUPTIBLE); |
374 | |
375 | list_for_each_entry(bdi, &bdi_list, bdi_list) { |
376 | bool have_dirty_io; |
377 | |
378 | if (!bdi_cap_writeback_dirty(bdi) || |
379 | bdi_cap_flush_forker(bdi)) |
380 | continue; |
381 | |
382 | WARN(!test_bit(BDI_registered, &bdi->state), |
383 | "bdi %p/%s is not registered!\n", bdi, bdi->name); |
384 | |
385 | have_dirty_io = !list_empty(&bdi->work_list) || |
386 | wb_has_dirty_io(&bdi->wb); |
387 | |
388 | /* |
389 | * If the bdi has work to do, but the thread does not |
390 | * exist - create it. |
391 | */ |
392 | if (!bdi->wb.task && have_dirty_io) { |
393 | /* |
394 | * Set the pending bit - if someone will try to |
395 | * unregister this bdi - it'll wait on this bit. |
396 | */ |
397 | set_bit(BDI_pending, &bdi->state); |
398 | action = FORK_THREAD; |
399 | break; |
400 | } |
401 | |
402 | spin_lock(&bdi->wb_lock); |
403 | |
404 | /* |
405 | * If there is no work to do and the bdi thread was |
406 | * inactive long enough - kill it. The wb_lock is taken |
407 | * to make sure no-one adds more work to this bdi and |
408 | * wakes the bdi thread up. |
409 | */ |
410 | if (bdi->wb.task && !have_dirty_io && |
411 | time_after(jiffies, bdi->wb.last_active + |
412 | bdi_longest_inactive())) { |
413 | task = bdi->wb.task; |
414 | bdi->wb.task = NULL; |
415 | spin_unlock(&bdi->wb_lock); |
416 | set_bit(BDI_pending, &bdi->state); |
417 | action = KILL_THREAD; |
418 | break; |
419 | } |
420 | spin_unlock(&bdi->wb_lock); |
421 | } |
422 | spin_unlock_bh(&bdi_lock); |
423 | |
424 | /* Keep working if default bdi still has things to do */ |
425 | if (!list_empty(&me->bdi->work_list)) |
426 | __set_current_state(TASK_RUNNING); |
427 | |
428 | switch (action) { |
429 | case FORK_THREAD: |
430 | __set_current_state(TASK_RUNNING); |
431 | task = kthread_create(bdi_writeback_thread, &bdi->wb, |
432 | "flush-%s", dev_name(bdi->dev)); |
433 | if (IS_ERR(task)) { |
434 | /* |
435 | * If thread creation fails, force writeout of |
436 | * the bdi from the thread. Hopefully 1024 is |
437 | * large enough for efficient IO. |
438 | */ |
439 | writeback_inodes_wb(&bdi->wb, 1024, |
440 | WB_REASON_FORKER_THREAD); |
441 | } else { |
442 | /* |
443 | * The spinlock makes sure we do not lose |
444 | * wake-ups when racing with 'bdi_queue_work()'. |
445 | * And as soon as the bdi thread is visible, we |
446 | * can start it. |
447 | */ |
448 | spin_lock_bh(&bdi->wb_lock); |
449 | bdi->wb.task = task; |
450 | spin_unlock_bh(&bdi->wb_lock); |
451 | wake_up_process(task); |
452 | } |
453 | bdi_clear_pending(bdi); |
454 | break; |
455 | |
456 | case KILL_THREAD: |
457 | __set_current_state(TASK_RUNNING); |
458 | kthread_stop(task); |
459 | bdi_clear_pending(bdi); |
460 | break; |
461 | |
462 | case NO_ACTION: |
463 | if (!wb_has_dirty_io(me) || !dirty_writeback_interval) |
464 | /* |
465 | * There are no dirty data. The only thing we |
466 | * should now care about is checking for |
467 | * inactive bdi threads and killing them. Thus, |
468 | * let's sleep for longer time, save energy and |
469 | * be friendly for battery-driven devices. |
470 | */ |
471 | schedule_timeout(bdi_longest_inactive()); |
472 | else |
473 | schedule_timeout(msecs_to_jiffies(dirty_writeback_interval * 10)); |
474 | try_to_freeze(); |
475 | break; |
476 | } |
477 | } |
478 | |
479 | return 0; |
480 | } |
481 | |
482 | /* |
483 | * Remove bdi from bdi_list, and ensure that it is no longer visible |
484 | */ |
485 | static void bdi_remove_from_list(struct backing_dev_info *bdi) |
486 | { |
487 | spin_lock_bh(&bdi_lock); |
488 | list_del_rcu(&bdi->bdi_list); |
489 | spin_unlock_bh(&bdi_lock); |
490 | |
491 | synchronize_rcu_expedited(); |
492 | } |
493 | |
494 | int bdi_register(struct backing_dev_info *bdi, struct device *parent, |
495 | const char *fmt, ...) |
496 | { |
497 | va_list args; |
498 | struct device *dev; |
499 | |
500 | if (bdi->dev) /* The driver needs to use separate queues per device */ |
501 | return 0; |
502 | |
503 | va_start(args, fmt); |
504 | dev = device_create_vargs(bdi_class, parent, MKDEV(0, 0), bdi, fmt, args); |
505 | va_end(args); |
506 | if (IS_ERR(dev)) |
507 | return PTR_ERR(dev); |
508 | |
509 | bdi->dev = dev; |
510 | |
511 | /* |
512 | * Just start the forker thread for our default backing_dev_info, |
513 | * and add other bdi's to the list. They will get a thread created |
514 | * on-demand when they need it. |
515 | */ |
516 | if (bdi_cap_flush_forker(bdi)) { |
517 | struct bdi_writeback *wb = &bdi->wb; |
518 | |
519 | wb->task = kthread_run(bdi_forker_thread, wb, "bdi-%s", |
520 | dev_name(dev)); |
521 | if (IS_ERR(wb->task)) |
522 | return PTR_ERR(wb->task); |
523 | } |
524 | |
525 | bdi_debug_register(bdi, dev_name(dev)); |
526 | set_bit(BDI_registered, &bdi->state); |
527 | |
528 | spin_lock_bh(&bdi_lock); |
529 | list_add_tail_rcu(&bdi->bdi_list, &bdi_list); |
530 | spin_unlock_bh(&bdi_lock); |
531 | |
532 | trace_writeback_bdi_register(bdi); |
533 | return 0; |
534 | } |
535 | EXPORT_SYMBOL(bdi_register); |
536 | |
537 | int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev) |
538 | { |
539 | return bdi_register(bdi, NULL, "%u:%u", MAJOR(dev), MINOR(dev)); |
540 | } |
541 | EXPORT_SYMBOL(bdi_register_dev); |
542 | |
543 | /* |
544 | * Remove bdi from the global list and shutdown any threads we have running |
545 | */ |
546 | static void bdi_wb_shutdown(struct backing_dev_info *bdi) |
547 | { |
548 | struct task_struct *task; |
549 | |
550 | if (!bdi_cap_writeback_dirty(bdi)) |
551 | return; |
552 | |
553 | /* |
554 | * Make sure nobody finds us on the bdi_list anymore |
555 | */ |
556 | bdi_remove_from_list(bdi); |
557 | |
558 | /* |
559 | * If setup is pending, wait for that to complete first |
560 | */ |
561 | wait_on_bit(&bdi->state, BDI_pending, bdi_sched_wait, |
562 | TASK_UNINTERRUPTIBLE); |
563 | |
564 | /* |
565 | * Finally, kill the kernel thread. We don't need to be RCU |
566 | * safe anymore, since the bdi is gone from visibility. |
567 | */ |
568 | spin_lock_bh(&bdi->wb_lock); |
569 | task = bdi->wb.task; |
570 | bdi->wb.task = NULL; |
571 | spin_unlock_bh(&bdi->wb_lock); |
572 | |
573 | if (task) |
574 | kthread_stop(task); |
575 | } |
576 | |
577 | /* |
578 | * This bdi is going away now, make sure that no super_blocks point to it |
579 | */ |
580 | static void bdi_prune_sb(struct backing_dev_info *bdi) |
581 | { |
582 | struct super_block *sb; |
583 | |
584 | spin_lock(&sb_lock); |
585 | list_for_each_entry(sb, &super_blocks, s_list) { |
586 | if (sb->s_bdi == bdi) |
587 | sb->s_bdi = &default_backing_dev_info; |
588 | } |
589 | spin_unlock(&sb_lock); |
590 | } |
591 | |
592 | void bdi_unregister(struct backing_dev_info *bdi) |
593 | { |
594 | struct device *dev = bdi->dev; |
595 | |
596 | if (dev) { |
597 | bdi_set_min_ratio(bdi, 0); |
598 | trace_writeback_bdi_unregister(bdi); |
599 | bdi_prune_sb(bdi); |
600 | del_timer_sync(&bdi->wb.wakeup_timer); |
601 | |
602 | if (!bdi_cap_flush_forker(bdi)) |
603 | bdi_wb_shutdown(bdi); |
604 | bdi_debug_unregister(bdi); |
605 | |
606 | spin_lock_bh(&bdi->wb_lock); |
607 | bdi->dev = NULL; |
608 | spin_unlock_bh(&bdi->wb_lock); |
609 | |
610 | device_unregister(dev); |
611 | } |
612 | } |
613 | EXPORT_SYMBOL(bdi_unregister); |
614 | |
615 | static void bdi_wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi) |
616 | { |
617 | memset(wb, 0, sizeof(*wb)); |
618 | |
619 | wb->bdi = bdi; |
620 | wb->last_old_flush = jiffies; |
621 | INIT_LIST_HEAD(&wb->b_dirty); |
622 | INIT_LIST_HEAD(&wb->b_io); |
623 | INIT_LIST_HEAD(&wb->b_more_io); |
624 | spin_lock_init(&wb->list_lock); |
625 | setup_timer(&wb->wakeup_timer, wakeup_timer_fn, (unsigned long)bdi); |
626 | } |
627 | |
628 | /* |
629 | * Initial write bandwidth: 100 MB/s |
630 | */ |
631 | #define INIT_BW (100 << (20 - PAGE_SHIFT)) |
632 | |
633 | int bdi_init(struct backing_dev_info *bdi) |
634 | { |
635 | int i, err; |
636 | |
637 | bdi->dev = NULL; |
638 | |
639 | bdi->min_ratio = 0; |
640 | bdi->max_ratio = 100; |
641 | bdi->max_prop_frac = FPROP_FRAC_BASE; |
642 | spin_lock_init(&bdi->wb_lock); |
643 | INIT_LIST_HEAD(&bdi->bdi_list); |
644 | INIT_LIST_HEAD(&bdi->work_list); |
645 | |
646 | bdi_wb_init(&bdi->wb, bdi); |
647 | |
648 | for (i = 0; i < NR_BDI_STAT_ITEMS; i++) { |
649 | err = percpu_counter_init(&bdi->bdi_stat[i], 0); |
650 | if (err) |
651 | goto err; |
652 | } |
653 | |
654 | bdi->dirty_exceeded = 0; |
655 | |
656 | bdi->bw_time_stamp = jiffies; |
657 | bdi->written_stamp = 0; |
658 | |
659 | bdi->balanced_dirty_ratelimit = INIT_BW; |
660 | bdi->dirty_ratelimit = INIT_BW; |
661 | bdi->write_bandwidth = INIT_BW; |
662 | bdi->avg_write_bandwidth = INIT_BW; |
663 | |
664 | err = fprop_local_init_percpu(&bdi->completions); |
665 | |
666 | if (err) { |
667 | err: |
668 | while (i--) |
669 | percpu_counter_destroy(&bdi->bdi_stat[i]); |
670 | } |
671 | |
672 | return err; |
673 | } |
674 | EXPORT_SYMBOL(bdi_init); |
675 | |
676 | void bdi_destroy(struct backing_dev_info *bdi) |
677 | { |
678 | int i; |
679 | |
680 | /* |
681 | * Splice our entries to the default_backing_dev_info, if this |
682 | * bdi disappears |
683 | */ |
684 | if (bdi_has_dirty_io(bdi)) { |
685 | struct bdi_writeback *dst = &default_backing_dev_info.wb; |
686 | |
687 | bdi_lock_two(&bdi->wb, dst); |
688 | list_splice(&bdi->wb.b_dirty, &dst->b_dirty); |
689 | list_splice(&bdi->wb.b_io, &dst->b_io); |
690 | list_splice(&bdi->wb.b_more_io, &dst->b_more_io); |
691 | spin_unlock(&bdi->wb.list_lock); |
692 | spin_unlock(&dst->list_lock); |
693 | } |
694 | |
695 | bdi_unregister(bdi); |
696 | |
697 | /* |
698 | * If bdi_unregister() had already been called earlier, the |
699 | * wakeup_timer could still be armed because bdi_prune_sb() |
700 | * can race with the bdi_wakeup_thread_delayed() calls from |
701 | * __mark_inode_dirty(). |
702 | */ |
703 | del_timer_sync(&bdi->wb.wakeup_timer); |
704 | |
705 | for (i = 0; i < NR_BDI_STAT_ITEMS; i++) |
706 | percpu_counter_destroy(&bdi->bdi_stat[i]); |
707 | |
708 | fprop_local_destroy_percpu(&bdi->completions); |
709 | } |
710 | EXPORT_SYMBOL(bdi_destroy); |
711 | |
712 | /* |
713 | * For use from filesystems to quickly init and register a bdi associated |
714 | * with dirty writeback |
715 | */ |
716 | int bdi_setup_and_register(struct backing_dev_info *bdi, char *name, |
717 | unsigned int cap) |
718 | { |
719 | char tmp[32]; |
720 | int err; |
721 | |
722 | bdi->name = name; |
723 | bdi->capabilities = cap; |
724 | err = bdi_init(bdi); |
725 | if (err) |
726 | return err; |
727 | |
728 | sprintf(tmp, "%.28s%s", name, "-%d"); |
729 | err = bdi_register(bdi, NULL, tmp, atomic_long_inc_return(&bdi_seq)); |
730 | if (err) { |
731 | bdi_destroy(bdi); |
732 | return err; |
733 | } |
734 | |
735 | return 0; |
736 | } |
737 | EXPORT_SYMBOL(bdi_setup_and_register); |
738 | |
739 | static wait_queue_head_t congestion_wqh[2] = { |
740 | __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]), |
741 | __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1]) |
742 | }; |
743 | static atomic_t nr_bdi_congested[2]; |
744 | |
745 | void clear_bdi_congested(struct backing_dev_info *bdi, int sync) |
746 | { |
747 | enum bdi_state bit; |
748 | wait_queue_head_t *wqh = &congestion_wqh[sync]; |
749 | |
750 | bit = sync ? BDI_sync_congested : BDI_async_congested; |
751 | if (test_and_clear_bit(bit, &bdi->state)) |
752 | atomic_dec(&nr_bdi_congested[sync]); |
753 | smp_mb__after_clear_bit(); |
754 | if (waitqueue_active(wqh)) |
755 | wake_up(wqh); |
756 | } |
757 | EXPORT_SYMBOL(clear_bdi_congested); |
758 | |
759 | void set_bdi_congested(struct backing_dev_info *bdi, int sync) |
760 | { |
761 | enum bdi_state bit; |
762 | |
763 | bit = sync ? BDI_sync_congested : BDI_async_congested; |
764 | if (!test_and_set_bit(bit, &bdi->state)) |
765 | atomic_inc(&nr_bdi_congested[sync]); |
766 | } |
767 | EXPORT_SYMBOL(set_bdi_congested); |
768 | |
769 | /** |
770 | * congestion_wait - wait for a backing_dev to become uncongested |
771 | * @sync: SYNC or ASYNC IO |
772 | * @timeout: timeout in jiffies |
773 | * |
774 | * Waits for up to @timeout jiffies for a backing_dev (any backing_dev) to exit |
775 | * write congestion. If no backing_devs are congested then just wait for the |
776 | * next write to be completed. |
777 | */ |
778 | long congestion_wait(int sync, long timeout) |
779 | { |
780 | long ret; |
781 | unsigned long start = jiffies; |
782 | DEFINE_WAIT(wait); |
783 | wait_queue_head_t *wqh = &congestion_wqh[sync]; |
784 | |
785 | prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); |
786 | ret = io_schedule_timeout(timeout); |
787 | finish_wait(wqh, &wait); |
788 | |
789 | trace_writeback_congestion_wait(jiffies_to_usecs(timeout), |
790 | jiffies_to_usecs(jiffies - start)); |
791 | |
792 | return ret; |
793 | } |
794 | EXPORT_SYMBOL(congestion_wait); |
795 | |
796 | /** |
797 | * wait_iff_congested - Conditionally wait for a backing_dev to become uncongested or a zone to complete writes |
798 | * @zone: A zone to check if it is heavily congested |
799 | * @sync: SYNC or ASYNC IO |
800 | * @timeout: timeout in jiffies |
801 | * |
802 | * In the event of a congested backing_dev (any backing_dev) and the given |
803 | * @zone has experienced recent congestion, this waits for up to @timeout |
804 | * jiffies for either a BDI to exit congestion of the given @sync queue |
805 | * or a write to complete. |
806 | * |
807 | * In the absence of zone congestion, cond_resched() is called to yield |
808 | * the processor if necessary but otherwise does not sleep. |
809 | * |
810 | * The return value is 0 if the sleep is for the full timeout. Otherwise, |
811 | * it is the number of jiffies that were still remaining when the function |
812 | * returned. return_value == timeout implies the function did not sleep. |
813 | */ |
814 | long wait_iff_congested(struct zone *zone, int sync, long timeout) |
815 | { |
816 | long ret; |
817 | unsigned long start = jiffies; |
818 | DEFINE_WAIT(wait); |
819 | wait_queue_head_t *wqh = &congestion_wqh[sync]; |
820 | |
821 | /* |
822 | * If there is no congestion, or heavy congestion is not being |
823 | * encountered in the current zone, yield if necessary instead |
824 | * of sleeping on the congestion queue |
825 | */ |
826 | if (atomic_read(&nr_bdi_congested[sync]) == 0 || |
827 | !zone_is_reclaim_congested(zone)) { |
828 | cond_resched(); |
829 | |
830 | /* In case we scheduled, work out time remaining */ |
831 | ret = timeout - (jiffies - start); |
832 | if (ret < 0) |
833 | ret = 0; |
834 | |
835 | goto out; |
836 | } |
837 | |
838 | /* Sleep until uncongested or a write happens */ |
839 | prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); |
840 | ret = io_schedule_timeout(timeout); |
841 | finish_wait(wqh, &wait); |
842 | |
843 | out: |
844 | trace_writeback_wait_iff_congested(jiffies_to_usecs(timeout), |
845 | jiffies_to_usecs(jiffies - start)); |
846 | |
847 | return ret; |
848 | } |
849 | EXPORT_SYMBOL(wait_iff_congested); |
850 | |
851 | int pdflush_proc_obsolete(struct ctl_table *table, int write, |
852 | void __user *buffer, size_t *lenp, loff_t *ppos) |
853 | { |
854 | char kbuf[] = "0\n"; |
855 | |
856 | if (*ppos) { |
857 | *lenp = 0; |
858 | return 0; |
859 | } |
860 | |
861 | if (copy_to_user(buffer, kbuf, sizeof(kbuf))) |
862 | return -EFAULT; |
863 | printk_once(KERN_WARNING "%s exported in /proc is scheduled for removal\n", |
864 | table->procname); |
865 | |
866 | *lenp = 2; |
867 | *ppos += *lenp; |
868 | return 2; |
869 | } |
870 |
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