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