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Source at commit 6c17a31f1fc515425221067cb3ece599c09dbc5d created 12 years 8 months ago. By Werner Almesberger, atusb, atben: moved from spi/ to ieee802154/; renamed atusb to spi_atusb | |
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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 | void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page) |
18 | { |
19 | } |
20 | EXPORT_SYMBOL(default_unplug_io_fn); |
21 | |
22 | struct backing_dev_info default_backing_dev_info = { |
23 | .name = "default", |
24 | .ra_pages = VM_MAX_READAHEAD * 1024 / PAGE_CACHE_SIZE, |
25 | .state = 0, |
26 | .capabilities = BDI_CAP_MAP_COPY, |
27 | .unplug_io_fn = default_unplug_io_fn, |
28 | }; |
29 | EXPORT_SYMBOL_GPL(default_backing_dev_info); |
30 | |
31 | struct backing_dev_info noop_backing_dev_info = { |
32 | .name = "noop", |
33 | .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK, |
34 | }; |
35 | EXPORT_SYMBOL_GPL(noop_backing_dev_info); |
36 | |
37 | static struct class *bdi_class; |
38 | |
39 | /* |
40 | * bdi_lock protects updates to bdi_list and bdi_pending_list, as well as |
41 | * reader side protection for bdi_pending_list. bdi_list has RCU reader side |
42 | * locking. |
43 | */ |
44 | DEFINE_SPINLOCK(bdi_lock); |
45 | LIST_HEAD(bdi_list); |
46 | LIST_HEAD(bdi_pending_list); |
47 | |
48 | static struct task_struct *sync_supers_tsk; |
49 | static struct timer_list sync_supers_timer; |
50 | |
51 | static int bdi_sync_supers(void *); |
52 | static void sync_supers_timer_fn(unsigned long); |
53 | |
54 | #ifdef CONFIG_DEBUG_FS |
55 | #include <linux/debugfs.h> |
56 | #include <linux/seq_file.h> |
57 | |
58 | static struct dentry *bdi_debug_root; |
59 | |
60 | static void bdi_debug_init(void) |
61 | { |
62 | bdi_debug_root = debugfs_create_dir("bdi", NULL); |
63 | } |
64 | |
65 | static int bdi_debug_stats_show(struct seq_file *m, void *v) |
66 | { |
67 | struct backing_dev_info *bdi = m->private; |
68 | struct bdi_writeback *wb = &bdi->wb; |
69 | unsigned long background_thresh; |
70 | unsigned long dirty_thresh; |
71 | unsigned long bdi_thresh; |
72 | unsigned long nr_dirty, nr_io, nr_more_io, nr_wb; |
73 | struct inode *inode; |
74 | |
75 | nr_wb = nr_dirty = nr_io = nr_more_io = 0; |
76 | spin_lock(&inode_lock); |
77 | list_for_each_entry(inode, &wb->b_dirty, i_wb_list) |
78 | nr_dirty++; |
79 | list_for_each_entry(inode, &wb->b_io, i_wb_list) |
80 | nr_io++; |
81 | list_for_each_entry(inode, &wb->b_more_io, i_wb_list) |
82 | nr_more_io++; |
83 | spin_unlock(&inode_lock); |
84 | |
85 | global_dirty_limits(&background_thresh, &dirty_thresh); |
86 | bdi_thresh = bdi_dirty_limit(bdi, dirty_thresh); |
87 | |
88 | #define K(x) ((x) << (PAGE_SHIFT - 10)) |
89 | seq_printf(m, |
90 | "BdiWriteback: %8lu kB\n" |
91 | "BdiReclaimable: %8lu kB\n" |
92 | "BdiDirtyThresh: %8lu kB\n" |
93 | "DirtyThresh: %8lu kB\n" |
94 | "BackgroundThresh: %8lu kB\n" |
95 | "b_dirty: %8lu\n" |
96 | "b_io: %8lu\n" |
97 | "b_more_io: %8lu\n" |
98 | "bdi_list: %8u\n" |
99 | "state: %8lx\n", |
100 | (unsigned long) K(bdi_stat(bdi, BDI_WRITEBACK)), |
101 | (unsigned long) K(bdi_stat(bdi, BDI_RECLAIMABLE)), |
102 | K(bdi_thresh), K(dirty_thresh), |
103 | K(background_thresh), nr_dirty, nr_io, nr_more_io, |
104 | !list_empty(&bdi->bdi_list), bdi->state); |
105 | #undef K |
106 | |
107 | return 0; |
108 | } |
109 | |
110 | static int bdi_debug_stats_open(struct inode *inode, struct file *file) |
111 | { |
112 | return single_open(file, bdi_debug_stats_show, inode->i_private); |
113 | } |
114 | |
115 | static const struct file_operations bdi_debug_stats_fops = { |
116 | .open = bdi_debug_stats_open, |
117 | .read = seq_read, |
118 | .llseek = seq_lseek, |
119 | .release = single_release, |
120 | }; |
121 | |
122 | static void bdi_debug_register(struct backing_dev_info *bdi, const char *name) |
123 | { |
124 | bdi->debug_dir = debugfs_create_dir(name, bdi_debug_root); |
125 | bdi->debug_stats = debugfs_create_file("stats", 0444, bdi->debug_dir, |
126 | bdi, &bdi_debug_stats_fops); |
127 | } |
128 | |
129 | static void bdi_debug_unregister(struct backing_dev_info *bdi) |
130 | { |
131 | debugfs_remove(bdi->debug_stats); |
132 | debugfs_remove(bdi->debug_dir); |
133 | } |
134 | #else |
135 | static inline void bdi_debug_init(void) |
136 | { |
137 | } |
138 | static inline void bdi_debug_register(struct backing_dev_info *bdi, |
139 | const char *name) |
140 | { |
141 | } |
142 | static inline void bdi_debug_unregister(struct backing_dev_info *bdi) |
143 | { |
144 | } |
145 | #endif |
146 | |
147 | static ssize_t read_ahead_kb_store(struct device *dev, |
148 | struct device_attribute *attr, |
149 | const char *buf, size_t count) |
150 | { |
151 | struct backing_dev_info *bdi = dev_get_drvdata(dev); |
152 | char *end; |
153 | unsigned long read_ahead_kb; |
154 | ssize_t ret = -EINVAL; |
155 | |
156 | read_ahead_kb = simple_strtoul(buf, &end, 10); |
157 | if (*buf && (end[0] == '\0' || (end[0] == '\n' && end[1] == '\0'))) { |
158 | bdi->ra_pages = read_ahead_kb >> (PAGE_SHIFT - 10); |
159 | ret = count; |
160 | } |
161 | return ret; |
162 | } |
163 | |
164 | #define K(pages) ((pages) << (PAGE_SHIFT - 10)) |
165 | |
166 | #define BDI_SHOW(name, expr) \ |
167 | static ssize_t name##_show(struct device *dev, \ |
168 | struct device_attribute *attr, char *page) \ |
169 | { \ |
170 | struct backing_dev_info *bdi = dev_get_drvdata(dev); \ |
171 | \ |
172 | return snprintf(page, PAGE_SIZE-1, "%lld\n", (long long)expr); \ |
173 | } |
174 | |
175 | BDI_SHOW(read_ahead_kb, K(bdi->ra_pages)) |
176 | |
177 | static ssize_t min_ratio_store(struct device *dev, |
178 | struct device_attribute *attr, const char *buf, size_t count) |
179 | { |
180 | struct backing_dev_info *bdi = dev_get_drvdata(dev); |
181 | char *end; |
182 | unsigned int ratio; |
183 | ssize_t ret = -EINVAL; |
184 | |
185 | ratio = simple_strtoul(buf, &end, 10); |
186 | if (*buf && (end[0] == '\0' || (end[0] == '\n' && end[1] == '\0'))) { |
187 | ret = bdi_set_min_ratio(bdi, ratio); |
188 | if (!ret) |
189 | ret = count; |
190 | } |
191 | return ret; |
192 | } |
193 | BDI_SHOW(min_ratio, bdi->min_ratio) |
194 | |
195 | static ssize_t max_ratio_store(struct device *dev, |
196 | struct device_attribute *attr, const char *buf, size_t count) |
197 | { |
198 | struct backing_dev_info *bdi = dev_get_drvdata(dev); |
199 | char *end; |
200 | unsigned int ratio; |
201 | ssize_t ret = -EINVAL; |
202 | |
203 | ratio = simple_strtoul(buf, &end, 10); |
204 | if (*buf && (end[0] == '\0' || (end[0] == '\n' && end[1] == '\0'))) { |
205 | ret = bdi_set_max_ratio(bdi, ratio); |
206 | if (!ret) |
207 | ret = count; |
208 | } |
209 | return ret; |
210 | } |
211 | BDI_SHOW(max_ratio, bdi->max_ratio) |
212 | |
213 | #define __ATTR_RW(attr) __ATTR(attr, 0644, attr##_show, attr##_store) |
214 | |
215 | static struct device_attribute bdi_dev_attrs[] = { |
216 | __ATTR_RW(read_ahead_kb), |
217 | __ATTR_RW(min_ratio), |
218 | __ATTR_RW(max_ratio), |
219 | __ATTR_NULL, |
220 | }; |
221 | |
222 | static __init int bdi_class_init(void) |
223 | { |
224 | bdi_class = class_create(THIS_MODULE, "bdi"); |
225 | if (IS_ERR(bdi_class)) |
226 | return PTR_ERR(bdi_class); |
227 | |
228 | bdi_class->dev_attrs = bdi_dev_attrs; |
229 | bdi_debug_init(); |
230 | return 0; |
231 | } |
232 | postcore_initcall(bdi_class_init); |
233 | |
234 | static int __init default_bdi_init(void) |
235 | { |
236 | int err; |
237 | |
238 | sync_supers_tsk = kthread_run(bdi_sync_supers, NULL, "sync_supers"); |
239 | BUG_ON(IS_ERR(sync_supers_tsk)); |
240 | |
241 | setup_timer(&sync_supers_timer, sync_supers_timer_fn, 0); |
242 | bdi_arm_supers_timer(); |
243 | |
244 | err = bdi_init(&default_backing_dev_info); |
245 | if (!err) |
246 | bdi_register(&default_backing_dev_info, NULL, "default"); |
247 | err = bdi_init(&noop_backing_dev_info); |
248 | |
249 | return err; |
250 | } |
251 | subsys_initcall(default_bdi_init); |
252 | |
253 | int bdi_has_dirty_io(struct backing_dev_info *bdi) |
254 | { |
255 | return wb_has_dirty_io(&bdi->wb); |
256 | } |
257 | |
258 | static void bdi_flush_io(struct backing_dev_info *bdi) |
259 | { |
260 | struct writeback_control wbc = { |
261 | .sync_mode = WB_SYNC_NONE, |
262 | .older_than_this = NULL, |
263 | .range_cyclic = 1, |
264 | .nr_to_write = 1024, |
265 | }; |
266 | |
267 | writeback_inodes_wb(&bdi->wb, &wbc); |
268 | } |
269 | |
270 | /* |
271 | * kupdated() used to do this. We cannot do it from the bdi_forker_thread() |
272 | * or we risk deadlocking on ->s_umount. The longer term solution would be |
273 | * to implement sync_supers_bdi() or similar and simply do it from the |
274 | * bdi writeback thread individually. |
275 | */ |
276 | static int bdi_sync_supers(void *unused) |
277 | { |
278 | set_user_nice(current, 0); |
279 | |
280 | while (!kthread_should_stop()) { |
281 | set_current_state(TASK_INTERRUPTIBLE); |
282 | schedule(); |
283 | |
284 | /* |
285 | * Do this periodically, like kupdated() did before. |
286 | */ |
287 | sync_supers(); |
288 | } |
289 | |
290 | return 0; |
291 | } |
292 | |
293 | void bdi_arm_supers_timer(void) |
294 | { |
295 | unsigned long next; |
296 | |
297 | if (!dirty_writeback_interval) |
298 | return; |
299 | |
300 | next = msecs_to_jiffies(dirty_writeback_interval * 10) + jiffies; |
301 | mod_timer(&sync_supers_timer, round_jiffies_up(next)); |
302 | } |
303 | |
304 | static void sync_supers_timer_fn(unsigned long unused) |
305 | { |
306 | wake_up_process(sync_supers_tsk); |
307 | bdi_arm_supers_timer(); |
308 | } |
309 | |
310 | static void wakeup_timer_fn(unsigned long data) |
311 | { |
312 | struct backing_dev_info *bdi = (struct backing_dev_info *)data; |
313 | |
314 | spin_lock_bh(&bdi->wb_lock); |
315 | if (bdi->wb.task) { |
316 | trace_writeback_wake_thread(bdi); |
317 | wake_up_process(bdi->wb.task); |
318 | } else { |
319 | /* |
320 | * When bdi tasks are inactive for long time, they are killed. |
321 | * In this case we have to wake-up the forker thread which |
322 | * should create and run the bdi thread. |
323 | */ |
324 | trace_writeback_wake_forker_thread(bdi); |
325 | wake_up_process(default_backing_dev_info.wb.task); |
326 | } |
327 | spin_unlock_bh(&bdi->wb_lock); |
328 | } |
329 | |
330 | /* |
331 | * This function is used when the first inode for this bdi is marked dirty. It |
332 | * wakes-up the corresponding bdi thread which should then take care of the |
333 | * periodic background write-out of dirty inodes. Since the write-out would |
334 | * starts only 'dirty_writeback_interval' centisecs from now anyway, we just |
335 | * set up a timer which wakes the bdi thread up later. |
336 | * |
337 | * Note, we wouldn't bother setting up the timer, but this function is on the |
338 | * fast-path (used by '__mark_inode_dirty()'), so we save few context switches |
339 | * by delaying the wake-up. |
340 | */ |
341 | void bdi_wakeup_thread_delayed(struct backing_dev_info *bdi) |
342 | { |
343 | unsigned long timeout; |
344 | |
345 | timeout = msecs_to_jiffies(dirty_writeback_interval * 10); |
346 | mod_timer(&bdi->wb.wakeup_timer, jiffies + timeout); |
347 | } |
348 | |
349 | /* |
350 | * Calculate the longest interval (jiffies) bdi threads are allowed to be |
351 | * inactive. |
352 | */ |
353 | static unsigned long bdi_longest_inactive(void) |
354 | { |
355 | unsigned long interval; |
356 | |
357 | interval = msecs_to_jiffies(dirty_writeback_interval * 10); |
358 | return max(5UL * 60 * HZ, interval); |
359 | } |
360 | |
361 | static int bdi_forker_thread(void *ptr) |
362 | { |
363 | struct bdi_writeback *me = ptr; |
364 | |
365 | current->flags |= PF_SWAPWRITE; |
366 | set_freezable(); |
367 | |
368 | /* |
369 | * Our parent may run at a different priority, just set us to normal |
370 | */ |
371 | set_user_nice(current, 0); |
372 | |
373 | for (;;) { |
374 | struct task_struct *task = NULL; |
375 | struct backing_dev_info *bdi; |
376 | enum { |
377 | NO_ACTION, /* Nothing to do */ |
378 | FORK_THREAD, /* Fork bdi thread */ |
379 | KILL_THREAD, /* Kill inactive bdi thread */ |
380 | } action = NO_ACTION; |
381 | |
382 | /* |
383 | * Temporary measure, we want to make sure we don't see |
384 | * dirty data on the default backing_dev_info |
385 | */ |
386 | if (wb_has_dirty_io(me) || !list_empty(&me->bdi->work_list)) { |
387 | del_timer(&me->wakeup_timer); |
388 | wb_do_writeback(me, 0); |
389 | } |
390 | |
391 | spin_lock_bh(&bdi_lock); |
392 | set_current_state(TASK_INTERRUPTIBLE); |
393 | |
394 | list_for_each_entry(bdi, &bdi_list, bdi_list) { |
395 | bool have_dirty_io; |
396 | |
397 | if (!bdi_cap_writeback_dirty(bdi) || |
398 | bdi_cap_flush_forker(bdi)) |
399 | continue; |
400 | |
401 | WARN(!test_bit(BDI_registered, &bdi->state), |
402 | "bdi %p/%s is not registered!\n", bdi, bdi->name); |
403 | |
404 | have_dirty_io = !list_empty(&bdi->work_list) || |
405 | wb_has_dirty_io(&bdi->wb); |
406 | |
407 | /* |
408 | * If the bdi has work to do, but the thread does not |
409 | * exist - create it. |
410 | */ |
411 | if (!bdi->wb.task && have_dirty_io) { |
412 | /* |
413 | * Set the pending bit - if someone will try to |
414 | * unregister this bdi - it'll wait on this bit. |
415 | */ |
416 | set_bit(BDI_pending, &bdi->state); |
417 | action = FORK_THREAD; |
418 | break; |
419 | } |
420 | |
421 | spin_lock(&bdi->wb_lock); |
422 | |
423 | /* |
424 | * If there is no work to do and the bdi thread was |
425 | * inactive long enough - kill it. The wb_lock is taken |
426 | * to make sure no-one adds more work to this bdi and |
427 | * wakes the bdi thread up. |
428 | */ |
429 | if (bdi->wb.task && !have_dirty_io && |
430 | time_after(jiffies, bdi->wb.last_active + |
431 | bdi_longest_inactive())) { |
432 | task = bdi->wb.task; |
433 | bdi->wb.task = NULL; |
434 | spin_unlock(&bdi->wb_lock); |
435 | set_bit(BDI_pending, &bdi->state); |
436 | action = KILL_THREAD; |
437 | break; |
438 | } |
439 | spin_unlock(&bdi->wb_lock); |
440 | } |
441 | spin_unlock_bh(&bdi_lock); |
442 | |
443 | /* Keep working if default bdi still has things to do */ |
444 | if (!list_empty(&me->bdi->work_list)) |
445 | __set_current_state(TASK_RUNNING); |
446 | |
447 | switch (action) { |
448 | case FORK_THREAD: |
449 | __set_current_state(TASK_RUNNING); |
450 | task = kthread_create(bdi_writeback_thread, &bdi->wb, |
451 | "flush-%s", dev_name(bdi->dev)); |
452 | if (IS_ERR(task)) { |
453 | /* |
454 | * If thread creation fails, force writeout of |
455 | * the bdi from the thread. |
456 | */ |
457 | bdi_flush_io(bdi); |
458 | } else { |
459 | /* |
460 | * The spinlock makes sure we do not lose |
461 | * wake-ups when racing with 'bdi_queue_work()'. |
462 | * And as soon as the bdi thread is visible, we |
463 | * can start it. |
464 | */ |
465 | spin_lock_bh(&bdi->wb_lock); |
466 | bdi->wb.task = task; |
467 | spin_unlock_bh(&bdi->wb_lock); |
468 | wake_up_process(task); |
469 | } |
470 | break; |
471 | |
472 | case KILL_THREAD: |
473 | __set_current_state(TASK_RUNNING); |
474 | kthread_stop(task); |
475 | break; |
476 | |
477 | case NO_ACTION: |
478 | if (!wb_has_dirty_io(me) || !dirty_writeback_interval) |
479 | /* |
480 | * There are no dirty data. The only thing we |
481 | * should now care about is checking for |
482 | * inactive bdi threads and killing them. Thus, |
483 | * let's sleep for longer time, save energy and |
484 | * be friendly for battery-driven devices. |
485 | */ |
486 | schedule_timeout(bdi_longest_inactive()); |
487 | else |
488 | schedule_timeout(msecs_to_jiffies(dirty_writeback_interval * 10)); |
489 | try_to_freeze(); |
490 | /* Back to the main loop */ |
491 | continue; |
492 | } |
493 | |
494 | /* |
495 | * Clear pending bit and wakeup anybody waiting to tear us down. |
496 | */ |
497 | clear_bit(BDI_pending, &bdi->state); |
498 | smp_mb__after_clear_bit(); |
499 | wake_up_bit(&bdi->state, BDI_pending); |
500 | } |
501 | |
502 | return 0; |
503 | } |
504 | |
505 | /* |
506 | * Remove bdi from bdi_list, and ensure that it is no longer visible |
507 | */ |
508 | static void bdi_remove_from_list(struct backing_dev_info *bdi) |
509 | { |
510 | spin_lock_bh(&bdi_lock); |
511 | list_del_rcu(&bdi->bdi_list); |
512 | spin_unlock_bh(&bdi_lock); |
513 | |
514 | synchronize_rcu(); |
515 | } |
516 | |
517 | int bdi_register(struct backing_dev_info *bdi, struct device *parent, |
518 | const char *fmt, ...) |
519 | { |
520 | va_list args; |
521 | struct device *dev; |
522 | |
523 | if (bdi->dev) /* The driver needs to use separate queues per device */ |
524 | return 0; |
525 | |
526 | va_start(args, fmt); |
527 | dev = device_create_vargs(bdi_class, parent, MKDEV(0, 0), bdi, fmt, args); |
528 | va_end(args); |
529 | if (IS_ERR(dev)) |
530 | return PTR_ERR(dev); |
531 | |
532 | bdi->dev = dev; |
533 | |
534 | /* |
535 | * Just start the forker thread for our default backing_dev_info, |
536 | * and add other bdi's to the list. They will get a thread created |
537 | * on-demand when they need it. |
538 | */ |
539 | if (bdi_cap_flush_forker(bdi)) { |
540 | struct bdi_writeback *wb = &bdi->wb; |
541 | |
542 | wb->task = kthread_run(bdi_forker_thread, wb, "bdi-%s", |
543 | dev_name(dev)); |
544 | if (IS_ERR(wb->task)) |
545 | return PTR_ERR(wb->task); |
546 | } |
547 | |
548 | bdi_debug_register(bdi, dev_name(dev)); |
549 | set_bit(BDI_registered, &bdi->state); |
550 | |
551 | spin_lock_bh(&bdi_lock); |
552 | list_add_tail_rcu(&bdi->bdi_list, &bdi_list); |
553 | spin_unlock_bh(&bdi_lock); |
554 | |
555 | trace_writeback_bdi_register(bdi); |
556 | return 0; |
557 | } |
558 | EXPORT_SYMBOL(bdi_register); |
559 | |
560 | int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev) |
561 | { |
562 | return bdi_register(bdi, NULL, "%u:%u", MAJOR(dev), MINOR(dev)); |
563 | } |
564 | EXPORT_SYMBOL(bdi_register_dev); |
565 | |
566 | /* |
567 | * Remove bdi from the global list and shutdown any threads we have running |
568 | */ |
569 | static void bdi_wb_shutdown(struct backing_dev_info *bdi) |
570 | { |
571 | if (!bdi_cap_writeback_dirty(bdi)) |
572 | return; |
573 | |
574 | /* |
575 | * Make sure nobody finds us on the bdi_list anymore |
576 | */ |
577 | bdi_remove_from_list(bdi); |
578 | |
579 | /* |
580 | * If setup is pending, wait for that to complete first |
581 | */ |
582 | wait_on_bit(&bdi->state, BDI_pending, bdi_sched_wait, |
583 | TASK_UNINTERRUPTIBLE); |
584 | |
585 | /* |
586 | * Finally, kill the kernel thread. We don't need to be RCU |
587 | * safe anymore, since the bdi is gone from visibility. Force |
588 | * unfreeze of the thread before calling kthread_stop(), otherwise |
589 | * it would never exet if it is currently stuck in the refrigerator. |
590 | */ |
591 | if (bdi->wb.task) { |
592 | thaw_process(bdi->wb.task); |
593 | kthread_stop(bdi->wb.task); |
594 | } |
595 | } |
596 | |
597 | /* |
598 | * This bdi is going away now, make sure that no super_blocks point to it |
599 | */ |
600 | static void bdi_prune_sb(struct backing_dev_info *bdi) |
601 | { |
602 | struct super_block *sb; |
603 | |
604 | spin_lock(&sb_lock); |
605 | list_for_each_entry(sb, &super_blocks, s_list) { |
606 | if (sb->s_bdi == bdi) |
607 | sb->s_bdi = NULL; |
608 | } |
609 | spin_unlock(&sb_lock); |
610 | } |
611 | |
612 | void bdi_unregister(struct backing_dev_info *bdi) |
613 | { |
614 | if (bdi->dev) { |
615 | trace_writeback_bdi_unregister(bdi); |
616 | bdi_prune_sb(bdi); |
617 | del_timer_sync(&bdi->wb.wakeup_timer); |
618 | |
619 | if (!bdi_cap_flush_forker(bdi)) |
620 | bdi_wb_shutdown(bdi); |
621 | bdi_debug_unregister(bdi); |
622 | device_unregister(bdi->dev); |
623 | bdi->dev = NULL; |
624 | } |
625 | } |
626 | EXPORT_SYMBOL(bdi_unregister); |
627 | |
628 | static void bdi_wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi) |
629 | { |
630 | memset(wb, 0, sizeof(*wb)); |
631 | |
632 | wb->bdi = bdi; |
633 | wb->last_old_flush = jiffies; |
634 | INIT_LIST_HEAD(&wb->b_dirty); |
635 | INIT_LIST_HEAD(&wb->b_io); |
636 | INIT_LIST_HEAD(&wb->b_more_io); |
637 | setup_timer(&wb->wakeup_timer, wakeup_timer_fn, (unsigned long)bdi); |
638 | } |
639 | |
640 | int bdi_init(struct backing_dev_info *bdi) |
641 | { |
642 | int i, err; |
643 | |
644 | bdi->dev = NULL; |
645 | |
646 | bdi->min_ratio = 0; |
647 | bdi->max_ratio = 100; |
648 | bdi->max_prop_frac = PROP_FRAC_BASE; |
649 | spin_lock_init(&bdi->wb_lock); |
650 | INIT_LIST_HEAD(&bdi->bdi_list); |
651 | INIT_LIST_HEAD(&bdi->work_list); |
652 | |
653 | bdi_wb_init(&bdi->wb, bdi); |
654 | |
655 | for (i = 0; i < NR_BDI_STAT_ITEMS; i++) { |
656 | err = percpu_counter_init(&bdi->bdi_stat[i], 0); |
657 | if (err) |
658 | goto err; |
659 | } |
660 | |
661 | bdi->dirty_exceeded = 0; |
662 | err = prop_local_init_percpu(&bdi->completions); |
663 | |
664 | if (err) { |
665 | err: |
666 | while (i--) |
667 | percpu_counter_destroy(&bdi->bdi_stat[i]); |
668 | } |
669 | |
670 | return err; |
671 | } |
672 | EXPORT_SYMBOL(bdi_init); |
673 | |
674 | void bdi_destroy(struct backing_dev_info *bdi) |
675 | { |
676 | int i; |
677 | |
678 | /* |
679 | * Splice our entries to the default_backing_dev_info, if this |
680 | * bdi disappears |
681 | */ |
682 | if (bdi_has_dirty_io(bdi)) { |
683 | struct bdi_writeback *dst = &default_backing_dev_info.wb; |
684 | |
685 | spin_lock(&inode_lock); |
686 | list_splice(&bdi->wb.b_dirty, &dst->b_dirty); |
687 | list_splice(&bdi->wb.b_io, &dst->b_io); |
688 | list_splice(&bdi->wb.b_more_io, &dst->b_more_io); |
689 | spin_unlock(&inode_lock); |
690 | } |
691 | |
692 | bdi_unregister(bdi); |
693 | |
694 | for (i = 0; i < NR_BDI_STAT_ITEMS; i++) |
695 | percpu_counter_destroy(&bdi->bdi_stat[i]); |
696 | |
697 | prop_local_destroy_percpu(&bdi->completions); |
698 | } |
699 | EXPORT_SYMBOL(bdi_destroy); |
700 | |
701 | /* |
702 | * For use from filesystems to quickly init and register a bdi associated |
703 | * with dirty writeback |
704 | */ |
705 | int bdi_setup_and_register(struct backing_dev_info *bdi, char *name, |
706 | unsigned int cap) |
707 | { |
708 | char tmp[32]; |
709 | int err; |
710 | |
711 | bdi->name = name; |
712 | bdi->capabilities = cap; |
713 | err = bdi_init(bdi); |
714 | if (err) |
715 | return err; |
716 | |
717 | sprintf(tmp, "%.28s%s", name, "-%d"); |
718 | err = bdi_register(bdi, NULL, tmp, atomic_long_inc_return(&bdi_seq)); |
719 | if (err) { |
720 | bdi_destroy(bdi); |
721 | return err; |
722 | } |
723 | |
724 | return 0; |
725 | } |
726 | EXPORT_SYMBOL(bdi_setup_and_register); |
727 | |
728 | static wait_queue_head_t congestion_wqh[2] = { |
729 | __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]), |
730 | __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1]) |
731 | }; |
732 | static atomic_t nr_bdi_congested[2]; |
733 | |
734 | void clear_bdi_congested(struct backing_dev_info *bdi, int sync) |
735 | { |
736 | enum bdi_state bit; |
737 | wait_queue_head_t *wqh = &congestion_wqh[sync]; |
738 | |
739 | bit = sync ? BDI_sync_congested : BDI_async_congested; |
740 | if (test_and_clear_bit(bit, &bdi->state)) |
741 | atomic_dec(&nr_bdi_congested[sync]); |
742 | smp_mb__after_clear_bit(); |
743 | if (waitqueue_active(wqh)) |
744 | wake_up(wqh); |
745 | } |
746 | EXPORT_SYMBOL(clear_bdi_congested); |
747 | |
748 | void set_bdi_congested(struct backing_dev_info *bdi, int sync) |
749 | { |
750 | enum bdi_state bit; |
751 | |
752 | bit = sync ? BDI_sync_congested : BDI_async_congested; |
753 | if (!test_and_set_bit(bit, &bdi->state)) |
754 | atomic_inc(&nr_bdi_congested[sync]); |
755 | } |
756 | EXPORT_SYMBOL(set_bdi_congested); |
757 | |
758 | /** |
759 | * congestion_wait - wait for a backing_dev to become uncongested |
760 | * @sync: SYNC or ASYNC IO |
761 | * @timeout: timeout in jiffies |
762 | * |
763 | * Waits for up to @timeout jiffies for a backing_dev (any backing_dev) to exit |
764 | * write congestion. If no backing_devs are congested then just wait for the |
765 | * next write to be completed. |
766 | */ |
767 | long congestion_wait(int sync, long timeout) |
768 | { |
769 | long ret; |
770 | unsigned long start = jiffies; |
771 | DEFINE_WAIT(wait); |
772 | wait_queue_head_t *wqh = &congestion_wqh[sync]; |
773 | |
774 | prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); |
775 | ret = io_schedule_timeout(timeout); |
776 | finish_wait(wqh, &wait); |
777 | |
778 | trace_writeback_congestion_wait(jiffies_to_usecs(timeout), |
779 | jiffies_to_usecs(jiffies - start)); |
780 | |
781 | return ret; |
782 | } |
783 | EXPORT_SYMBOL(congestion_wait); |
784 | |
785 | /** |
786 | * wait_iff_congested - Conditionally wait for a backing_dev to become uncongested or a zone to complete writes |
787 | * @zone: A zone to check if it is heavily congested |
788 | * @sync: SYNC or ASYNC IO |
789 | * @timeout: timeout in jiffies |
790 | * |
791 | * In the event of a congested backing_dev (any backing_dev) and the given |
792 | * @zone has experienced recent congestion, this waits for up to @timeout |
793 | * jiffies for either a BDI to exit congestion of the given @sync queue |
794 | * or a write to complete. |
795 | * |
796 | * In the absense of zone congestion, cond_resched() is called to yield |
797 | * the processor if necessary but otherwise does not sleep. |
798 | * |
799 | * The return value is 0 if the sleep is for the full timeout. Otherwise, |
800 | * it is the number of jiffies that were still remaining when the function |
801 | * returned. return_value == timeout implies the function did not sleep. |
802 | */ |
803 | long wait_iff_congested(struct zone *zone, int sync, long timeout) |
804 | { |
805 | long ret; |
806 | unsigned long start = jiffies; |
807 | DEFINE_WAIT(wait); |
808 | wait_queue_head_t *wqh = &congestion_wqh[sync]; |
809 | |
810 | /* |
811 | * If there is no congestion, or heavy congestion is not being |
812 | * encountered in the current zone, yield if necessary instead |
813 | * of sleeping on the congestion queue |
814 | */ |
815 | if (atomic_read(&nr_bdi_congested[sync]) == 0 || |
816 | !zone_is_reclaim_congested(zone)) { |
817 | cond_resched(); |
818 | |
819 | /* In case we scheduled, work out time remaining */ |
820 | ret = timeout - (jiffies - start); |
821 | if (ret < 0) |
822 | ret = 0; |
823 | |
824 | goto out; |
825 | } |
826 | |
827 | /* Sleep until uncongested or a write happens */ |
828 | prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); |
829 | ret = io_schedule_timeout(timeout); |
830 | finish_wait(wqh, &wait); |
831 | |
832 | out: |
833 | trace_writeback_wait_iff_congested(jiffies_to_usecs(timeout), |
834 | jiffies_to_usecs(jiffies - start)); |
835 | |
836 | return ret; |
837 | } |
838 | EXPORT_SYMBOL(wait_iff_congested); |
839 |
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