Commit | Line | Data |
---|---|---|
3fcfab16 AM |
1 | |
2 | #include <linux/wait.h> | |
3 | #include <linux/backing-dev.h> | |
03ba3782 JA |
4 | #include <linux/kthread.h> |
5 | #include <linux/freezer.h> | |
3fcfab16 | 6 | #include <linux/fs.h> |
26160158 | 7 | #include <linux/pagemap.h> |
03ba3782 | 8 | #include <linux/mm.h> |
3fcfab16 AM |
9 | #include <linux/sched.h> |
10 | #include <linux/module.h> | |
cf0ca9fe PZ |
11 | #include <linux/writeback.h> |
12 | #include <linux/device.h> | |
455b2864 | 13 | #include <trace/events/writeback.h> |
cf0ca9fe | 14 | |
c3c53206 JA |
15 | static atomic_long_t bdi_seq = ATOMIC_LONG_INIT(0); |
16 | ||
26160158 JA |
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 = { | |
d993831f | 23 | .name = "default", |
26160158 JA |
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); | |
cf0ca9fe | 30 | |
5129a469 JE |
31 | struct backing_dev_info noop_backing_dev_info = { |
32 | .name = "noop", | |
33 | }; | |
34 | EXPORT_SYMBOL_GPL(noop_backing_dev_info); | |
35 | ||
cf0ca9fe | 36 | static struct class *bdi_class; |
cfc4ba53 JA |
37 | |
38 | /* | |
39 | * bdi_lock protects updates to bdi_list and bdi_pending_list, as well as | |
40 | * reader side protection for bdi_pending_list. bdi_list has RCU reader side | |
41 | * locking. | |
42 | */ | |
03ba3782 | 43 | DEFINE_SPINLOCK(bdi_lock); |
66f3b8e2 | 44 | LIST_HEAD(bdi_list); |
03ba3782 JA |
45 | LIST_HEAD(bdi_pending_list); |
46 | ||
47 | static struct task_struct *sync_supers_tsk; | |
48 | static struct timer_list sync_supers_timer; | |
49 | ||
50 | static int bdi_sync_supers(void *); | |
51 | static void sync_supers_timer_fn(unsigned long); | |
03ba3782 | 52 | |
76f1418b MS |
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; | |
c1955ce3 | 67 | struct bdi_writeback *wb = &bdi->wb; |
364aeb28 DR |
68 | unsigned long background_thresh; |
69 | unsigned long dirty_thresh; | |
70 | unsigned long bdi_thresh; | |
f09b00d3 JA |
71 | unsigned long nr_dirty, nr_io, nr_more_io, nr_wb; |
72 | struct inode *inode; | |
73 | ||
f09b00d3 JA |
74 | nr_wb = nr_dirty = nr_io = nr_more_io = 0; |
75 | spin_lock(&inode_lock); | |
c1955ce3 CH |
76 | list_for_each_entry(inode, &wb->b_dirty, i_list) |
77 | nr_dirty++; | |
78 | list_for_each_entry(inode, &wb->b_io, i_list) | |
79 | nr_io++; | |
80 | list_for_each_entry(inode, &wb->b_more_io, i_list) | |
81 | nr_more_io++; | |
f09b00d3 | 82 | spin_unlock(&inode_lock); |
76f1418b MS |
83 | |
84 | get_dirty_limits(&background_thresh, &dirty_thresh, &bdi_thresh, bdi); | |
85 | ||
86 | #define K(x) ((x) << (PAGE_SHIFT - 10)) | |
87 | seq_printf(m, | |
88 | "BdiWriteback: %8lu kB\n" | |
89 | "BdiReclaimable: %8lu kB\n" | |
90 | "BdiDirtyThresh: %8lu kB\n" | |
91 | "DirtyThresh: %8lu kB\n" | |
f09b00d3 | 92 | "BackgroundThresh: %8lu kB\n" |
f09b00d3 JA |
93 | "b_dirty: %8lu\n" |
94 | "b_io: %8lu\n" | |
95 | "b_more_io: %8lu\n" | |
96 | "bdi_list: %8u\n" | |
c1955ce3 | 97 | "state: %8lx\n", |
76f1418b MS |
98 | (unsigned long) K(bdi_stat(bdi, BDI_WRITEBACK)), |
99 | (unsigned long) K(bdi_stat(bdi, BDI_RECLAIMABLE)), | |
f09b00d3 | 100 | K(bdi_thresh), K(dirty_thresh), |
c1955ce3 CH |
101 | K(background_thresh), nr_dirty, nr_io, nr_more_io, |
102 | !list_empty(&bdi->bdi_list), bdi->state); | |
76f1418b MS |
103 | #undef K |
104 | ||
105 | return 0; | |
106 | } | |
107 | ||
108 | static int bdi_debug_stats_open(struct inode *inode, struct file *file) | |
109 | { | |
110 | return single_open(file, bdi_debug_stats_show, inode->i_private); | |
111 | } | |
112 | ||
113 | static const struct file_operations bdi_debug_stats_fops = { | |
114 | .open = bdi_debug_stats_open, | |
115 | .read = seq_read, | |
116 | .llseek = seq_lseek, | |
117 | .release = single_release, | |
118 | }; | |
119 | ||
120 | static void bdi_debug_register(struct backing_dev_info *bdi, const char *name) | |
121 | { | |
122 | bdi->debug_dir = debugfs_create_dir(name, bdi_debug_root); | |
123 | bdi->debug_stats = debugfs_create_file("stats", 0444, bdi->debug_dir, | |
124 | bdi, &bdi_debug_stats_fops); | |
125 | } | |
126 | ||
127 | static void bdi_debug_unregister(struct backing_dev_info *bdi) | |
128 | { | |
129 | debugfs_remove(bdi->debug_stats); | |
130 | debugfs_remove(bdi->debug_dir); | |
131 | } | |
132 | #else | |
133 | static inline void bdi_debug_init(void) | |
134 | { | |
135 | } | |
136 | static inline void bdi_debug_register(struct backing_dev_info *bdi, | |
137 | const char *name) | |
138 | { | |
139 | } | |
140 | static inline void bdi_debug_unregister(struct backing_dev_info *bdi) | |
141 | { | |
142 | } | |
143 | #endif | |
144 | ||
cf0ca9fe PZ |
145 | static ssize_t read_ahead_kb_store(struct device *dev, |
146 | struct device_attribute *attr, | |
147 | const char *buf, size_t count) | |
148 | { | |
149 | struct backing_dev_info *bdi = dev_get_drvdata(dev); | |
150 | char *end; | |
151 | unsigned long read_ahead_kb; | |
152 | ssize_t ret = -EINVAL; | |
153 | ||
154 | read_ahead_kb = simple_strtoul(buf, &end, 10); | |
155 | if (*buf && (end[0] == '\0' || (end[0] == '\n' && end[1] == '\0'))) { | |
156 | bdi->ra_pages = read_ahead_kb >> (PAGE_SHIFT - 10); | |
157 | ret = count; | |
158 | } | |
159 | return ret; | |
160 | } | |
161 | ||
162 | #define K(pages) ((pages) << (PAGE_SHIFT - 10)) | |
163 | ||
164 | #define BDI_SHOW(name, expr) \ | |
165 | static ssize_t name##_show(struct device *dev, \ | |
166 | struct device_attribute *attr, char *page) \ | |
167 | { \ | |
168 | struct backing_dev_info *bdi = dev_get_drvdata(dev); \ | |
169 | \ | |
170 | return snprintf(page, PAGE_SIZE-1, "%lld\n", (long long)expr); \ | |
171 | } | |
172 | ||
173 | BDI_SHOW(read_ahead_kb, K(bdi->ra_pages)) | |
174 | ||
189d3c4a PZ |
175 | static ssize_t min_ratio_store(struct device *dev, |
176 | struct device_attribute *attr, const char *buf, size_t count) | |
177 | { | |
178 | struct backing_dev_info *bdi = dev_get_drvdata(dev); | |
179 | char *end; | |
180 | unsigned int ratio; | |
181 | ssize_t ret = -EINVAL; | |
182 | ||
183 | ratio = simple_strtoul(buf, &end, 10); | |
184 | if (*buf && (end[0] == '\0' || (end[0] == '\n' && end[1] == '\0'))) { | |
185 | ret = bdi_set_min_ratio(bdi, ratio); | |
186 | if (!ret) | |
187 | ret = count; | |
188 | } | |
189 | return ret; | |
190 | } | |
191 | BDI_SHOW(min_ratio, bdi->min_ratio) | |
192 | ||
a42dde04 PZ |
193 | static ssize_t max_ratio_store(struct device *dev, |
194 | struct device_attribute *attr, const char *buf, size_t count) | |
195 | { | |
196 | struct backing_dev_info *bdi = dev_get_drvdata(dev); | |
197 | char *end; | |
198 | unsigned int ratio; | |
199 | ssize_t ret = -EINVAL; | |
200 | ||
201 | ratio = simple_strtoul(buf, &end, 10); | |
202 | if (*buf && (end[0] == '\0' || (end[0] == '\n' && end[1] == '\0'))) { | |
203 | ret = bdi_set_max_ratio(bdi, ratio); | |
204 | if (!ret) | |
205 | ret = count; | |
206 | } | |
207 | return ret; | |
208 | } | |
209 | BDI_SHOW(max_ratio, bdi->max_ratio) | |
210 | ||
cf0ca9fe PZ |
211 | #define __ATTR_RW(attr) __ATTR(attr, 0644, attr##_show, attr##_store) |
212 | ||
213 | static struct device_attribute bdi_dev_attrs[] = { | |
214 | __ATTR_RW(read_ahead_kb), | |
189d3c4a | 215 | __ATTR_RW(min_ratio), |
a42dde04 | 216 | __ATTR_RW(max_ratio), |
cf0ca9fe PZ |
217 | __ATTR_NULL, |
218 | }; | |
219 | ||
220 | static __init int bdi_class_init(void) | |
221 | { | |
222 | bdi_class = class_create(THIS_MODULE, "bdi"); | |
14421453 AB |
223 | if (IS_ERR(bdi_class)) |
224 | return PTR_ERR(bdi_class); | |
225 | ||
cf0ca9fe | 226 | bdi_class->dev_attrs = bdi_dev_attrs; |
76f1418b | 227 | bdi_debug_init(); |
cf0ca9fe PZ |
228 | return 0; |
229 | } | |
76f1418b | 230 | postcore_initcall(bdi_class_init); |
cf0ca9fe | 231 | |
26160158 JA |
232 | static int __init default_bdi_init(void) |
233 | { | |
234 | int err; | |
235 | ||
03ba3782 JA |
236 | sync_supers_tsk = kthread_run(bdi_sync_supers, NULL, "sync_supers"); |
237 | BUG_ON(IS_ERR(sync_supers_tsk)); | |
238 | ||
03ba3782 | 239 | setup_timer(&sync_supers_timer, sync_supers_timer_fn, 0); |
6423104b | 240 | bdi_arm_supers_timer(); |
03ba3782 | 241 | |
26160158 JA |
242 | err = bdi_init(&default_backing_dev_info); |
243 | if (!err) | |
244 | bdi_register(&default_backing_dev_info, NULL, "default"); | |
245 | ||
246 | return err; | |
247 | } | |
248 | subsys_initcall(default_bdi_init); | |
249 | ||
03ba3782 JA |
250 | int bdi_has_dirty_io(struct backing_dev_info *bdi) |
251 | { | |
252 | return wb_has_dirty_io(&bdi->wb); | |
253 | } | |
254 | ||
255 | static void bdi_flush_io(struct backing_dev_info *bdi) | |
256 | { | |
257 | struct writeback_control wbc = { | |
03ba3782 JA |
258 | .sync_mode = WB_SYNC_NONE, |
259 | .older_than_this = NULL, | |
260 | .range_cyclic = 1, | |
261 | .nr_to_write = 1024, | |
262 | }; | |
263 | ||
9c3a8ee8 | 264 | writeback_inodes_wb(&bdi->wb, &wbc); |
03ba3782 JA |
265 | } |
266 | ||
267 | /* | |
6f904ff0 | 268 | * kupdated() used to do this. We cannot do it from the bdi_forker_thread() |
03ba3782 JA |
269 | * or we risk deadlocking on ->s_umount. The longer term solution would be |
270 | * to implement sync_supers_bdi() or similar and simply do it from the | |
6f904ff0 | 271 | * bdi writeback thread individually. |
03ba3782 JA |
272 | */ |
273 | static int bdi_sync_supers(void *unused) | |
274 | { | |
275 | set_user_nice(current, 0); | |
276 | ||
277 | while (!kthread_should_stop()) { | |
278 | set_current_state(TASK_INTERRUPTIBLE); | |
279 | schedule(); | |
280 | ||
281 | /* | |
282 | * Do this periodically, like kupdated() did before. | |
283 | */ | |
284 | sync_supers(); | |
285 | } | |
286 | ||
287 | return 0; | |
288 | } | |
289 | ||
6423104b | 290 | void bdi_arm_supers_timer(void) |
03ba3782 JA |
291 | { |
292 | unsigned long next; | |
293 | ||
6423104b JA |
294 | if (!dirty_writeback_interval) |
295 | return; | |
296 | ||
03ba3782 JA |
297 | next = msecs_to_jiffies(dirty_writeback_interval * 10) + jiffies; |
298 | mod_timer(&sync_supers_timer, round_jiffies_up(next)); | |
299 | } | |
300 | ||
301 | static void sync_supers_timer_fn(unsigned long unused) | |
302 | { | |
303 | wake_up_process(sync_supers_tsk); | |
6423104b | 304 | bdi_arm_supers_timer(); |
03ba3782 JA |
305 | } |
306 | ||
6467716a AB |
307 | static void wakeup_timer_fn(unsigned long data) |
308 | { | |
309 | struct backing_dev_info *bdi = (struct backing_dev_info *)data; | |
310 | ||
311 | spin_lock_bh(&bdi->wb_lock); | |
312 | if (bdi->wb.task) { | |
313 | wake_up_process(bdi->wb.task); | |
314 | } else { | |
315 | /* | |
316 | * When bdi tasks are inactive for long time, they are killed. | |
317 | * In this case we have to wake-up the forker thread which | |
318 | * should create and run the bdi thread. | |
319 | */ | |
320 | wake_up_process(default_backing_dev_info.wb.task); | |
321 | } | |
322 | spin_unlock_bh(&bdi->wb_lock); | |
323 | } | |
324 | ||
325 | /* | |
326 | * This function is used when the first inode for this bdi is marked dirty. It | |
327 | * wakes-up the corresponding bdi thread which should then take care of the | |
328 | * periodic background write-out of dirty inodes. Since the write-out would | |
329 | * starts only 'dirty_writeback_interval' centisecs from now anyway, we just | |
330 | * set up a timer which wakes the bdi thread up later. | |
331 | * | |
332 | * Note, we wouldn't bother setting up the timer, but this function is on the | |
333 | * fast-path (used by '__mark_inode_dirty()'), so we save few context switches | |
334 | * by delaying the wake-up. | |
335 | */ | |
336 | void bdi_wakeup_thread_delayed(struct backing_dev_info *bdi) | |
337 | { | |
338 | unsigned long timeout; | |
339 | ||
340 | timeout = msecs_to_jiffies(dirty_writeback_interval * 10); | |
341 | mod_timer(&bdi->wb.wakeup_timer, jiffies + timeout); | |
342 | } | |
343 | ||
fff5b85a AB |
344 | /* |
345 | * Calculate the longest interval (jiffies) bdi threads are allowed to be | |
346 | * inactive. | |
347 | */ | |
348 | static unsigned long bdi_longest_inactive(void) | |
349 | { | |
350 | unsigned long interval; | |
351 | ||
352 | interval = msecs_to_jiffies(dirty_writeback_interval * 10); | |
353 | return max(5UL * 60 * HZ, interval); | |
354 | } | |
355 | ||
6f904ff0 | 356 | static int bdi_forker_thread(void *ptr) |
03ba3782 JA |
357 | { |
358 | struct bdi_writeback *me = ptr; | |
359 | ||
c1955ce3 CH |
360 | current->flags |= PF_FLUSHER | PF_SWAPWRITE; |
361 | set_freezable(); | |
362 | ||
363 | /* | |
364 | * Our parent may run at a different priority, just set us to normal | |
365 | */ | |
366 | set_user_nice(current, 0); | |
03ba3782 JA |
367 | |
368 | for (;;) { | |
fff5b85a | 369 | struct task_struct *task = NULL; |
78c40cb6 | 370 | struct backing_dev_info *bdi; |
adf39240 AB |
371 | enum { |
372 | NO_ACTION, /* Nothing to do */ | |
373 | FORK_THREAD, /* Fork bdi thread */ | |
fff5b85a | 374 | KILL_THREAD, /* Kill inactive bdi thread */ |
adf39240 | 375 | } action = NO_ACTION; |
03ba3782 JA |
376 | |
377 | /* | |
378 | * Temporary measure, we want to make sure we don't see | |
379 | * dirty data on the default backing_dev_info | |
380 | */ | |
6467716a AB |
381 | if (wb_has_dirty_io(me) || !list_empty(&me->bdi->work_list)) { |
382 | del_timer(&me->wakeup_timer); | |
03ba3782 | 383 | wb_do_writeback(me, 0); |
6467716a | 384 | } |
03ba3782 | 385 | |
cfc4ba53 | 386 | spin_lock_bh(&bdi_lock); |
c5f7ad23 | 387 | set_current_state(TASK_INTERRUPTIBLE); |
03ba3782 | 388 | |
78c40cb6 | 389 | list_for_each_entry(bdi, &bdi_list, bdi_list) { |
adf39240 AB |
390 | bool have_dirty_io; |
391 | ||
392 | if (!bdi_cap_writeback_dirty(bdi) || | |
393 | bdi_cap_flush_forker(bdi)) | |
03ba3782 JA |
394 | continue; |
395 | ||
080dcec4 AB |
396 | WARN(!test_bit(BDI_registered, &bdi->state), |
397 | "bdi %p/%s is not registered!\n", bdi, bdi->name); | |
398 | ||
adf39240 AB |
399 | have_dirty_io = !list_empty(&bdi->work_list) || |
400 | wb_has_dirty_io(&bdi->wb); | |
78c40cb6 AB |
401 | |
402 | /* | |
adf39240 AB |
403 | * If the bdi has work to do, but the thread does not |
404 | * exist - create it. | |
78c40cb6 | 405 | */ |
adf39240 AB |
406 | if (!bdi->wb.task && have_dirty_io) { |
407 | /* | |
408 | * Set the pending bit - if someone will try to | |
409 | * unregister this bdi - it'll wait on this bit. | |
410 | */ | |
411 | set_bit(BDI_pending, &bdi->state); | |
412 | action = FORK_THREAD; | |
413 | break; | |
414 | } | |
fff5b85a | 415 | |
6467716a | 416 | spin_lock_bh(&bdi->wb_lock); |
fff5b85a AB |
417 | /* |
418 | * If there is no work to do and the bdi thread was | |
419 | * inactive long enough - kill it. The wb_lock is taken | |
420 | * to make sure no-one adds more work to this bdi and | |
421 | * wakes the bdi thread up. | |
422 | */ | |
423 | if (bdi->wb.task && !have_dirty_io && | |
424 | time_after(jiffies, bdi->wb.last_active + | |
425 | bdi_longest_inactive())) { | |
426 | task = bdi->wb.task; | |
427 | bdi->wb.task = NULL; | |
428 | spin_unlock(&bdi->wb_lock); | |
429 | set_bit(BDI_pending, &bdi->state); | |
430 | action = KILL_THREAD; | |
431 | break; | |
432 | } | |
6467716a | 433 | spin_unlock_bh(&bdi->wb_lock); |
03ba3782 | 434 | } |
080dcec4 | 435 | spin_unlock_bh(&bdi_lock); |
03ba3782 | 436 | |
c4ec7908 AB |
437 | /* Keep working if default bdi still has things to do */ |
438 | if (!list_empty(&me->bdi->work_list)) | |
439 | __set_current_state(TASK_RUNNING); | |
440 | ||
adf39240 AB |
441 | switch (action) { |
442 | case FORK_THREAD: | |
443 | __set_current_state(TASK_RUNNING); | |
444 | task = kthread_run(bdi_writeback_thread, &bdi->wb, "flush-%s", | |
445 | dev_name(bdi->dev)); | |
446 | if (IS_ERR(task)) { | |
447 | /* | |
448 | * If thread creation fails, force writeout of | |
449 | * the bdi from the thread. | |
450 | */ | |
451 | bdi_flush_io(bdi); | |
fff5b85a AB |
452 | } else { |
453 | /* | |
454 | * The spinlock makes sure we do not lose | |
455 | * wake-ups when racing with 'bdi_queue_work()'. | |
456 | */ | |
6467716a | 457 | spin_lock_bh(&bdi->wb_lock); |
adf39240 | 458 | bdi->wb.task = task; |
6467716a | 459 | spin_unlock_bh(&bdi->wb_lock); |
fff5b85a AB |
460 | } |
461 | break; | |
462 | ||
463 | case KILL_THREAD: | |
464 | __set_current_state(TASK_RUNNING); | |
465 | kthread_stop(task); | |
adf39240 | 466 | break; |
03ba3782 | 467 | |
adf39240 | 468 | case NO_ACTION: |
253c34e9 AB |
469 | if (!wb_has_dirty_io(me) || !dirty_writeback_interval) |
470 | /* | |
471 | * There are no dirty data. The only thing we | |
472 | * should now care about is checking for | |
473 | * inactive bdi threads and killing them. Thus, | |
474 | * let's sleep for longer time, save energy and | |
475 | * be friendly for battery-driven devices. | |
476 | */ | |
477 | schedule_timeout(bdi_longest_inactive()); | |
6423104b | 478 | else |
253c34e9 | 479 | schedule_timeout(msecs_to_jiffies(dirty_writeback_interval * 10)); |
03ba3782 | 480 | try_to_freeze(); |
adf39240 | 481 | /* Back to the main loop */ |
03ba3782 JA |
482 | continue; |
483 | } | |
fff5b85a AB |
484 | |
485 | /* | |
486 | * Clear pending bit and wakeup anybody waiting to tear us down. | |
487 | */ | |
488 | clear_bit(BDI_pending, &bdi->state); | |
489 | smp_mb__after_clear_bit(); | |
490 | wake_up_bit(&bdi->state, BDI_pending); | |
03ba3782 JA |
491 | } |
492 | ||
493 | return 0; | |
494 | } | |
495 | ||
cfc4ba53 JA |
496 | /* |
497 | * Remove bdi from bdi_list, and ensure that it is no longer visible | |
498 | */ | |
499 | static void bdi_remove_from_list(struct backing_dev_info *bdi) | |
500 | { | |
501 | spin_lock_bh(&bdi_lock); | |
502 | list_del_rcu(&bdi->bdi_list); | |
503 | spin_unlock_bh(&bdi_lock); | |
504 | ||
505 | synchronize_rcu(); | |
506 | } | |
507 | ||
cf0ca9fe PZ |
508 | int bdi_register(struct backing_dev_info *bdi, struct device *parent, |
509 | const char *fmt, ...) | |
510 | { | |
cf0ca9fe PZ |
511 | va_list args; |
512 | int ret = 0; | |
513 | struct device *dev; | |
514 | ||
69fc208b | 515 | if (bdi->dev) /* The driver needs to use separate queues per device */ |
f1d0b063 KS |
516 | goto exit; |
517 | ||
cf0ca9fe | 518 | va_start(args, fmt); |
19051c50 | 519 | dev = device_create_vargs(bdi_class, parent, MKDEV(0, 0), bdi, fmt, args); |
cf0ca9fe | 520 | va_end(args); |
cf0ca9fe PZ |
521 | if (IS_ERR(dev)) { |
522 | ret = PTR_ERR(dev); | |
523 | goto exit; | |
524 | } | |
525 | ||
cfc4ba53 JA |
526 | spin_lock_bh(&bdi_lock); |
527 | list_add_tail_rcu(&bdi->bdi_list, &bdi_list); | |
528 | spin_unlock_bh(&bdi_lock); | |
66f3b8e2 | 529 | |
cf0ca9fe | 530 | bdi->dev = dev; |
cf0ca9fe | 531 | |
03ba3782 JA |
532 | /* |
533 | * Just start the forker thread for our default backing_dev_info, | |
534 | * and add other bdi's to the list. They will get a thread created | |
535 | * on-demand when they need it. | |
536 | */ | |
537 | if (bdi_cap_flush_forker(bdi)) { | |
538 | struct bdi_writeback *wb = &bdi->wb; | |
539 | ||
6f904ff0 | 540 | wb->task = kthread_run(bdi_forker_thread, wb, "bdi-%s", |
03ba3782 JA |
541 | dev_name(dev)); |
542 | if (IS_ERR(wb->task)) { | |
543 | wb->task = NULL; | |
544 | ret = -ENOMEM; | |
545 | ||
cfc4ba53 | 546 | bdi_remove_from_list(bdi); |
03ba3782 JA |
547 | goto exit; |
548 | } | |
549 | } | |
550 | ||
551 | bdi_debug_register(bdi, dev_name(dev)); | |
500b067c | 552 | set_bit(BDI_registered, &bdi->state); |
455b2864 | 553 | trace_writeback_bdi_register(bdi); |
cf0ca9fe | 554 | exit: |
cf0ca9fe PZ |
555 | return ret; |
556 | } | |
557 | EXPORT_SYMBOL(bdi_register); | |
558 | ||
559 | int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev) | |
560 | { | |
561 | return bdi_register(bdi, NULL, "%u:%u", MAJOR(dev), MINOR(dev)); | |
562 | } | |
563 | EXPORT_SYMBOL(bdi_register_dev); | |
564 | ||
03ba3782 JA |
565 | /* |
566 | * Remove bdi from the global list and shutdown any threads we have running | |
567 | */ | |
568 | static void bdi_wb_shutdown(struct backing_dev_info *bdi) | |
66f3b8e2 | 569 | { |
03ba3782 JA |
570 | if (!bdi_cap_writeback_dirty(bdi)) |
571 | return; | |
572 | ||
573 | /* | |
fff5b85a | 574 | * Make sure nobody finds us on the bdi_list anymore |
03ba3782 | 575 | */ |
fff5b85a | 576 | bdi_remove_from_list(bdi); |
03ba3782 JA |
577 | |
578 | /* | |
fff5b85a | 579 | * If setup is pending, wait for that to complete first |
03ba3782 | 580 | */ |
fff5b85a AB |
581 | wait_on_bit(&bdi->state, BDI_pending, bdi_sched_wait, |
582 | TASK_UNINTERRUPTIBLE); | |
03ba3782 JA |
583 | |
584 | /* | |
c1955ce3 | 585 | * Finally, kill the kernel thread. We don't need to be RCU |
c62b17a5 RD |
586 | * safe anymore, since the bdi is gone from visibility. Force |
587 | * unfreeze of the thread before calling kthread_stop(), otherwise | |
588 | * it would never exet if it is currently stuck in the refrigerator. | |
03ba3782 | 589 | */ |
c1955ce3 CH |
590 | if (bdi->wb.task) { |
591 | thaw_process(bdi->wb.task); | |
592 | kthread_stop(bdi->wb.task); | |
c62b17a5 | 593 | } |
66f3b8e2 JA |
594 | } |
595 | ||
592b09a4 JA |
596 | /* |
597 | * This bdi is going away now, make sure that no super_blocks point to it | |
598 | */ | |
599 | static void bdi_prune_sb(struct backing_dev_info *bdi) | |
600 | { | |
601 | struct super_block *sb; | |
602 | ||
603 | spin_lock(&sb_lock); | |
604 | list_for_each_entry(sb, &super_blocks, s_list) { | |
605 | if (sb->s_bdi == bdi) | |
606 | sb->s_bdi = NULL; | |
607 | } | |
608 | spin_unlock(&sb_lock); | |
609 | } | |
610 | ||
cf0ca9fe PZ |
611 | void bdi_unregister(struct backing_dev_info *bdi) |
612 | { | |
613 | if (bdi->dev) { | |
455b2864 | 614 | trace_writeback_bdi_unregister(bdi); |
8c4db335 | 615 | bdi_prune_sb(bdi); |
6467716a | 616 | del_timer_sync(&bdi->wb.wakeup_timer); |
8c4db335 | 617 | |
03ba3782 JA |
618 | if (!bdi_cap_flush_forker(bdi)) |
619 | bdi_wb_shutdown(bdi); | |
76f1418b | 620 | bdi_debug_unregister(bdi); |
cf0ca9fe PZ |
621 | device_unregister(bdi->dev); |
622 | bdi->dev = NULL; | |
623 | } | |
624 | } | |
625 | EXPORT_SYMBOL(bdi_unregister); | |
3fcfab16 | 626 | |
6467716a AB |
627 | static void bdi_wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi) |
628 | { | |
629 | memset(wb, 0, sizeof(*wb)); | |
630 | ||
631 | wb->bdi = bdi; | |
632 | wb->last_old_flush = jiffies; | |
633 | INIT_LIST_HEAD(&wb->b_dirty); | |
634 | INIT_LIST_HEAD(&wb->b_io); | |
635 | INIT_LIST_HEAD(&wb->b_more_io); | |
636 | setup_timer(&wb->wakeup_timer, wakeup_timer_fn, (unsigned long)bdi); | |
637 | } | |
638 | ||
b2e8fb6e PZ |
639 | int bdi_init(struct backing_dev_info *bdi) |
640 | { | |
03ba3782 | 641 | int i, err; |
b2e8fb6e | 642 | |
cf0ca9fe PZ |
643 | bdi->dev = NULL; |
644 | ||
189d3c4a | 645 | bdi->min_ratio = 0; |
a42dde04 PZ |
646 | bdi->max_ratio = 100; |
647 | bdi->max_prop_frac = PROP_FRAC_BASE; | |
03ba3782 | 648 | spin_lock_init(&bdi->wb_lock); |
66f3b8e2 | 649 | INIT_LIST_HEAD(&bdi->bdi_list); |
03ba3782 JA |
650 | INIT_LIST_HEAD(&bdi->work_list); |
651 | ||
652 | bdi_wb_init(&bdi->wb, bdi); | |
653 | ||
b2e8fb6e | 654 | for (i = 0; i < NR_BDI_STAT_ITEMS; i++) { |
ea319518 | 655 | err = percpu_counter_init(&bdi->bdi_stat[i], 0); |
04fbfdc1 PZ |
656 | if (err) |
657 | goto err; | |
658 | } | |
659 | ||
660 | bdi->dirty_exceeded = 0; | |
661 | err = prop_local_init_percpu(&bdi->completions); | |
662 | ||
663 | if (err) { | |
664 | err: | |
4b01a0b1 | 665 | while (i--) |
04fbfdc1 | 666 | percpu_counter_destroy(&bdi->bdi_stat[i]); |
b2e8fb6e PZ |
667 | } |
668 | ||
669 | return err; | |
670 | } | |
671 | EXPORT_SYMBOL(bdi_init); | |
672 | ||
673 | void bdi_destroy(struct backing_dev_info *bdi) | |
674 | { | |
675 | int i; | |
676 | ||
ce5f8e77 JA |
677 | /* |
678 | * Splice our entries to the default_backing_dev_info, if this | |
679 | * bdi disappears | |
680 | */ | |
681 | if (bdi_has_dirty_io(bdi)) { | |
682 | struct bdi_writeback *dst = &default_backing_dev_info.wb; | |
683 | ||
684 | spin_lock(&inode_lock); | |
685 | list_splice(&bdi->wb.b_dirty, &dst->b_dirty); | |
686 | list_splice(&bdi->wb.b_io, &dst->b_io); | |
687 | list_splice(&bdi->wb.b_more_io, &dst->b_more_io); | |
688 | spin_unlock(&inode_lock); | |
689 | } | |
66f3b8e2 | 690 | |
cf0ca9fe PZ |
691 | bdi_unregister(bdi); |
692 | ||
b2e8fb6e PZ |
693 | for (i = 0; i < NR_BDI_STAT_ITEMS; i++) |
694 | percpu_counter_destroy(&bdi->bdi_stat[i]); | |
04fbfdc1 PZ |
695 | |
696 | prop_local_destroy_percpu(&bdi->completions); | |
b2e8fb6e PZ |
697 | } |
698 | EXPORT_SYMBOL(bdi_destroy); | |
699 | ||
c3c53206 JA |
700 | /* |
701 | * For use from filesystems to quickly init and register a bdi associated | |
702 | * with dirty writeback | |
703 | */ | |
704 | int bdi_setup_and_register(struct backing_dev_info *bdi, char *name, | |
705 | unsigned int cap) | |
706 | { | |
707 | char tmp[32]; | |
708 | int err; | |
709 | ||
710 | bdi->name = name; | |
711 | bdi->capabilities = cap; | |
712 | err = bdi_init(bdi); | |
713 | if (err) | |
714 | return err; | |
715 | ||
716 | sprintf(tmp, "%.28s%s", name, "-%d"); | |
717 | err = bdi_register(bdi, NULL, tmp, atomic_long_inc_return(&bdi_seq)); | |
718 | if (err) { | |
719 | bdi_destroy(bdi); | |
720 | return err; | |
721 | } | |
722 | ||
723 | return 0; | |
724 | } | |
725 | EXPORT_SYMBOL(bdi_setup_and_register); | |
726 | ||
3fcfab16 AM |
727 | static wait_queue_head_t congestion_wqh[2] = { |
728 | __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]), | |
729 | __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1]) | |
730 | }; | |
731 | ||
1faa16d2 | 732 | void clear_bdi_congested(struct backing_dev_info *bdi, int sync) |
3fcfab16 AM |
733 | { |
734 | enum bdi_state bit; | |
1faa16d2 | 735 | wait_queue_head_t *wqh = &congestion_wqh[sync]; |
3fcfab16 | 736 | |
1faa16d2 | 737 | bit = sync ? BDI_sync_congested : BDI_async_congested; |
3fcfab16 AM |
738 | clear_bit(bit, &bdi->state); |
739 | smp_mb__after_clear_bit(); | |
740 | if (waitqueue_active(wqh)) | |
741 | wake_up(wqh); | |
742 | } | |
743 | EXPORT_SYMBOL(clear_bdi_congested); | |
744 | ||
1faa16d2 | 745 | void set_bdi_congested(struct backing_dev_info *bdi, int sync) |
3fcfab16 AM |
746 | { |
747 | enum bdi_state bit; | |
748 | ||
1faa16d2 | 749 | bit = sync ? BDI_sync_congested : BDI_async_congested; |
3fcfab16 AM |
750 | set_bit(bit, &bdi->state); |
751 | } | |
752 | EXPORT_SYMBOL(set_bdi_congested); | |
753 | ||
754 | /** | |
755 | * congestion_wait - wait for a backing_dev to become uncongested | |
8aa7e847 | 756 | * @sync: SYNC or ASYNC IO |
3fcfab16 AM |
757 | * @timeout: timeout in jiffies |
758 | * | |
759 | * Waits for up to @timeout jiffies for a backing_dev (any backing_dev) to exit | |
760 | * write congestion. If no backing_devs are congested then just wait for the | |
761 | * next write to be completed. | |
762 | */ | |
8aa7e847 | 763 | long congestion_wait(int sync, long timeout) |
3fcfab16 AM |
764 | { |
765 | long ret; | |
766 | DEFINE_WAIT(wait); | |
8aa7e847 | 767 | wait_queue_head_t *wqh = &congestion_wqh[sync]; |
3fcfab16 AM |
768 | |
769 | prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); | |
770 | ret = io_schedule_timeout(timeout); | |
771 | finish_wait(wqh, &wait); | |
772 | return ret; | |
773 | } | |
774 | EXPORT_SYMBOL(congestion_wait); | |
04fbfdc1 | 775 |