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 | ||
239 | init_timer(&sync_supers_timer); | |
240 | setup_timer(&sync_supers_timer, sync_supers_timer_fn, 0); | |
6423104b | 241 | bdi_arm_supers_timer(); |
03ba3782 | 242 | |
26160158 JA |
243 | err = bdi_init(&default_backing_dev_info); |
244 | if (!err) | |
245 | bdi_register(&default_backing_dev_info, NULL, "default"); | |
246 | ||
247 | return err; | |
248 | } | |
249 | subsys_initcall(default_bdi_init); | |
250 | ||
03ba3782 JA |
251 | int bdi_has_dirty_io(struct backing_dev_info *bdi) |
252 | { | |
253 | return wb_has_dirty_io(&bdi->wb); | |
254 | } | |
255 | ||
256 | static void bdi_flush_io(struct backing_dev_info *bdi) | |
257 | { | |
258 | struct writeback_control wbc = { | |
03ba3782 JA |
259 | .sync_mode = WB_SYNC_NONE, |
260 | .older_than_this = NULL, | |
261 | .range_cyclic = 1, | |
262 | .nr_to_write = 1024, | |
263 | }; | |
264 | ||
9c3a8ee8 | 265 | writeback_inodes_wb(&bdi->wb, &wbc); |
03ba3782 JA |
266 | } |
267 | ||
268 | /* | |
6f904ff0 | 269 | * kupdated() used to do this. We cannot do it from the bdi_forker_thread() |
03ba3782 JA |
270 | * or we risk deadlocking on ->s_umount. The longer term solution would be |
271 | * to implement sync_supers_bdi() or similar and simply do it from the | |
6f904ff0 | 272 | * bdi writeback thread individually. |
03ba3782 JA |
273 | */ |
274 | static int bdi_sync_supers(void *unused) | |
275 | { | |
276 | set_user_nice(current, 0); | |
277 | ||
278 | while (!kthread_should_stop()) { | |
279 | set_current_state(TASK_INTERRUPTIBLE); | |
280 | schedule(); | |
281 | ||
282 | /* | |
283 | * Do this periodically, like kupdated() did before. | |
284 | */ | |
285 | sync_supers(); | |
286 | } | |
287 | ||
288 | return 0; | |
289 | } | |
290 | ||
6423104b | 291 | void bdi_arm_supers_timer(void) |
03ba3782 JA |
292 | { |
293 | unsigned long next; | |
294 | ||
6423104b JA |
295 | if (!dirty_writeback_interval) |
296 | return; | |
297 | ||
03ba3782 JA |
298 | next = msecs_to_jiffies(dirty_writeback_interval * 10) + jiffies; |
299 | mod_timer(&sync_supers_timer, round_jiffies_up(next)); | |
300 | } | |
301 | ||
302 | static void sync_supers_timer_fn(unsigned long unused) | |
303 | { | |
304 | wake_up_process(sync_supers_tsk); | |
6423104b | 305 | bdi_arm_supers_timer(); |
03ba3782 JA |
306 | } |
307 | ||
6467716a AB |
308 | static void wakeup_timer_fn(unsigned long data) |
309 | { | |
310 | struct backing_dev_info *bdi = (struct backing_dev_info *)data; | |
311 | ||
312 | spin_lock_bh(&bdi->wb_lock); | |
313 | if (bdi->wb.task) { | |
314 | wake_up_process(bdi->wb.task); | |
315 | } else { | |
316 | /* | |
317 | * When bdi tasks are inactive for long time, they are killed. | |
318 | * In this case we have to wake-up the forker thread which | |
319 | * should create and run the bdi thread. | |
320 | */ | |
321 | wake_up_process(default_backing_dev_info.wb.task); | |
322 | } | |
323 | spin_unlock_bh(&bdi->wb_lock); | |
324 | } | |
325 | ||
326 | /* | |
327 | * This function is used when the first inode for this bdi is marked dirty. It | |
328 | * wakes-up the corresponding bdi thread which should then take care of the | |
329 | * periodic background write-out of dirty inodes. Since the write-out would | |
330 | * starts only 'dirty_writeback_interval' centisecs from now anyway, we just | |
331 | * set up a timer which wakes the bdi thread up later. | |
332 | * | |
333 | * Note, we wouldn't bother setting up the timer, but this function is on the | |
334 | * fast-path (used by '__mark_inode_dirty()'), so we save few context switches | |
335 | * by delaying the wake-up. | |
336 | */ | |
337 | void bdi_wakeup_thread_delayed(struct backing_dev_info *bdi) | |
338 | { | |
339 | unsigned long timeout; | |
340 | ||
341 | timeout = msecs_to_jiffies(dirty_writeback_interval * 10); | |
342 | mod_timer(&bdi->wb.wakeup_timer, jiffies + timeout); | |
343 | } | |
344 | ||
fff5b85a AB |
345 | /* |
346 | * Calculate the longest interval (jiffies) bdi threads are allowed to be | |
347 | * inactive. | |
348 | */ | |
349 | static unsigned long bdi_longest_inactive(void) | |
350 | { | |
351 | unsigned long interval; | |
352 | ||
353 | interval = msecs_to_jiffies(dirty_writeback_interval * 10); | |
354 | return max(5UL * 60 * HZ, interval); | |
355 | } | |
356 | ||
6f904ff0 | 357 | static int bdi_forker_thread(void *ptr) |
03ba3782 JA |
358 | { |
359 | struct bdi_writeback *me = ptr; | |
360 | ||
c1955ce3 CH |
361 | current->flags |= PF_FLUSHER | PF_SWAPWRITE; |
362 | set_freezable(); | |
363 | ||
364 | /* | |
365 | * Our parent may run at a different priority, just set us to normal | |
366 | */ | |
367 | set_user_nice(current, 0); | |
03ba3782 JA |
368 | |
369 | for (;;) { | |
fff5b85a | 370 | struct task_struct *task = NULL; |
78c40cb6 | 371 | struct backing_dev_info *bdi; |
adf39240 AB |
372 | enum { |
373 | NO_ACTION, /* Nothing to do */ | |
374 | FORK_THREAD, /* Fork bdi thread */ | |
fff5b85a | 375 | KILL_THREAD, /* Kill inactive bdi thread */ |
adf39240 | 376 | } action = NO_ACTION; |
03ba3782 JA |
377 | |
378 | /* | |
379 | * Temporary measure, we want to make sure we don't see | |
380 | * dirty data on the default backing_dev_info | |
381 | */ | |
6467716a AB |
382 | if (wb_has_dirty_io(me) || !list_empty(&me->bdi->work_list)) { |
383 | del_timer(&me->wakeup_timer); | |
03ba3782 | 384 | wb_do_writeback(me, 0); |
6467716a | 385 | } |
03ba3782 | 386 | |
cfc4ba53 | 387 | spin_lock_bh(&bdi_lock); |
c5f7ad23 | 388 | set_current_state(TASK_INTERRUPTIBLE); |
03ba3782 | 389 | |
78c40cb6 | 390 | list_for_each_entry(bdi, &bdi_list, bdi_list) { |
adf39240 AB |
391 | bool have_dirty_io; |
392 | ||
393 | if (!bdi_cap_writeback_dirty(bdi) || | |
394 | bdi_cap_flush_forker(bdi)) | |
03ba3782 JA |
395 | continue; |
396 | ||
080dcec4 AB |
397 | WARN(!test_bit(BDI_registered, &bdi->state), |
398 | "bdi %p/%s is not registered!\n", bdi, bdi->name); | |
399 | ||
adf39240 AB |
400 | have_dirty_io = !list_empty(&bdi->work_list) || |
401 | wb_has_dirty_io(&bdi->wb); | |
78c40cb6 AB |
402 | |
403 | /* | |
adf39240 AB |
404 | * If the bdi has work to do, but the thread does not |
405 | * exist - create it. | |
78c40cb6 | 406 | */ |
adf39240 AB |
407 | if (!bdi->wb.task && have_dirty_io) { |
408 | /* | |
409 | * Set the pending bit - if someone will try to | |
410 | * unregister this bdi - it'll wait on this bit. | |
411 | */ | |
412 | set_bit(BDI_pending, &bdi->state); | |
413 | action = FORK_THREAD; | |
414 | break; | |
415 | } | |
fff5b85a | 416 | |
6467716a | 417 | spin_lock_bh(&bdi->wb_lock); |
fff5b85a AB |
418 | /* |
419 | * If there is no work to do and the bdi thread was | |
420 | * inactive long enough - kill it. The wb_lock is taken | |
421 | * to make sure no-one adds more work to this bdi and | |
422 | * wakes the bdi thread up. | |
423 | */ | |
424 | if (bdi->wb.task && !have_dirty_io && | |
425 | time_after(jiffies, bdi->wb.last_active + | |
426 | bdi_longest_inactive())) { | |
427 | task = bdi->wb.task; | |
428 | bdi->wb.task = NULL; | |
429 | spin_unlock(&bdi->wb_lock); | |
430 | set_bit(BDI_pending, &bdi->state); | |
431 | action = KILL_THREAD; | |
432 | break; | |
433 | } | |
6467716a | 434 | spin_unlock_bh(&bdi->wb_lock); |
03ba3782 | 435 | } |
080dcec4 | 436 | spin_unlock_bh(&bdi_lock); |
03ba3782 | 437 | |
c4ec7908 AB |
438 | /* Keep working if default bdi still has things to do */ |
439 | if (!list_empty(&me->bdi->work_list)) | |
440 | __set_current_state(TASK_RUNNING); | |
441 | ||
adf39240 AB |
442 | switch (action) { |
443 | case FORK_THREAD: | |
444 | __set_current_state(TASK_RUNNING); | |
445 | task = kthread_run(bdi_writeback_thread, &bdi->wb, "flush-%s", | |
446 | dev_name(bdi->dev)); | |
447 | if (IS_ERR(task)) { | |
448 | /* | |
449 | * If thread creation fails, force writeout of | |
450 | * the bdi from the thread. | |
451 | */ | |
452 | bdi_flush_io(bdi); | |
fff5b85a AB |
453 | } else { |
454 | /* | |
455 | * The spinlock makes sure we do not lose | |
456 | * wake-ups when racing with 'bdi_queue_work()'. | |
457 | */ | |
6467716a | 458 | spin_lock_bh(&bdi->wb_lock); |
adf39240 | 459 | bdi->wb.task = task; |
6467716a | 460 | spin_unlock_bh(&bdi->wb_lock); |
fff5b85a AB |
461 | } |
462 | break; | |
463 | ||
464 | case KILL_THREAD: | |
465 | __set_current_state(TASK_RUNNING); | |
466 | kthread_stop(task); | |
adf39240 | 467 | break; |
03ba3782 | 468 | |
adf39240 | 469 | case NO_ACTION: |
253c34e9 AB |
470 | if (!wb_has_dirty_io(me) || !dirty_writeback_interval) |
471 | /* | |
472 | * There are no dirty data. The only thing we | |
473 | * should now care about is checking for | |
474 | * inactive bdi threads and killing them. Thus, | |
475 | * let's sleep for longer time, save energy and | |
476 | * be friendly for battery-driven devices. | |
477 | */ | |
478 | schedule_timeout(bdi_longest_inactive()); | |
6423104b | 479 | else |
253c34e9 | 480 | schedule_timeout(msecs_to_jiffies(dirty_writeback_interval * 10)); |
03ba3782 | 481 | try_to_freeze(); |
adf39240 | 482 | /* Back to the main loop */ |
03ba3782 JA |
483 | continue; |
484 | } | |
fff5b85a AB |
485 | |
486 | /* | |
487 | * Clear pending bit and wakeup anybody waiting to tear us down. | |
488 | */ | |
489 | clear_bit(BDI_pending, &bdi->state); | |
490 | smp_mb__after_clear_bit(); | |
491 | wake_up_bit(&bdi->state, BDI_pending); | |
03ba3782 JA |
492 | } |
493 | ||
494 | return 0; | |
495 | } | |
496 | ||
cfc4ba53 JA |
497 | /* |
498 | * Remove bdi from bdi_list, and ensure that it is no longer visible | |
499 | */ | |
500 | static void bdi_remove_from_list(struct backing_dev_info *bdi) | |
501 | { | |
502 | spin_lock_bh(&bdi_lock); | |
503 | list_del_rcu(&bdi->bdi_list); | |
504 | spin_unlock_bh(&bdi_lock); | |
505 | ||
506 | synchronize_rcu(); | |
507 | } | |
508 | ||
cf0ca9fe PZ |
509 | int bdi_register(struct backing_dev_info *bdi, struct device *parent, |
510 | const char *fmt, ...) | |
511 | { | |
cf0ca9fe PZ |
512 | va_list args; |
513 | int ret = 0; | |
514 | struct device *dev; | |
515 | ||
69fc208b | 516 | if (bdi->dev) /* The driver needs to use separate queues per device */ |
f1d0b063 KS |
517 | goto exit; |
518 | ||
cf0ca9fe | 519 | va_start(args, fmt); |
19051c50 | 520 | dev = device_create_vargs(bdi_class, parent, MKDEV(0, 0), bdi, fmt, args); |
cf0ca9fe | 521 | va_end(args); |
cf0ca9fe PZ |
522 | if (IS_ERR(dev)) { |
523 | ret = PTR_ERR(dev); | |
524 | goto exit; | |
525 | } | |
526 | ||
cfc4ba53 JA |
527 | spin_lock_bh(&bdi_lock); |
528 | list_add_tail_rcu(&bdi->bdi_list, &bdi_list); | |
529 | spin_unlock_bh(&bdi_lock); | |
66f3b8e2 | 530 | |
cf0ca9fe | 531 | bdi->dev = dev; |
cf0ca9fe | 532 | |
03ba3782 JA |
533 | /* |
534 | * Just start the forker thread for our default backing_dev_info, | |
535 | * and add other bdi's to the list. They will get a thread created | |
536 | * on-demand when they need it. | |
537 | */ | |
538 | if (bdi_cap_flush_forker(bdi)) { | |
539 | struct bdi_writeback *wb = &bdi->wb; | |
540 | ||
6f904ff0 | 541 | wb->task = kthread_run(bdi_forker_thread, wb, "bdi-%s", |
03ba3782 JA |
542 | dev_name(dev)); |
543 | if (IS_ERR(wb->task)) { | |
544 | wb->task = NULL; | |
545 | ret = -ENOMEM; | |
546 | ||
cfc4ba53 | 547 | bdi_remove_from_list(bdi); |
03ba3782 JA |
548 | goto exit; |
549 | } | |
550 | } | |
551 | ||
552 | bdi_debug_register(bdi, dev_name(dev)); | |
500b067c | 553 | set_bit(BDI_registered, &bdi->state); |
455b2864 | 554 | trace_writeback_bdi_register(bdi); |
cf0ca9fe | 555 | exit: |
cf0ca9fe PZ |
556 | return ret; |
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 | ||
03ba3782 JA |
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) | |
66f3b8e2 | 570 | { |
03ba3782 JA |
571 | if (!bdi_cap_writeback_dirty(bdi)) |
572 | return; | |
573 | ||
574 | /* | |
fff5b85a | 575 | * Make sure nobody finds us on the bdi_list anymore |
03ba3782 | 576 | */ |
fff5b85a | 577 | bdi_remove_from_list(bdi); |
03ba3782 JA |
578 | |
579 | /* | |
fff5b85a | 580 | * If setup is pending, wait for that to complete first |
03ba3782 | 581 | */ |
fff5b85a AB |
582 | wait_on_bit(&bdi->state, BDI_pending, bdi_sched_wait, |
583 | TASK_UNINTERRUPTIBLE); | |
03ba3782 JA |
584 | |
585 | /* | |
c1955ce3 | 586 | * Finally, kill the kernel thread. We don't need to be RCU |
c62b17a5 RD |
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. | |
03ba3782 | 590 | */ |
c1955ce3 CH |
591 | if (bdi->wb.task) { |
592 | thaw_process(bdi->wb.task); | |
593 | kthread_stop(bdi->wb.task); | |
c62b17a5 | 594 | } |
66f3b8e2 JA |
595 | } |
596 | ||
592b09a4 JA |
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 | ||
cf0ca9fe PZ |
612 | void bdi_unregister(struct backing_dev_info *bdi) |
613 | { | |
614 | if (bdi->dev) { | |
455b2864 | 615 | trace_writeback_bdi_unregister(bdi); |
8c4db335 | 616 | bdi_prune_sb(bdi); |
6467716a | 617 | del_timer_sync(&bdi->wb.wakeup_timer); |
8c4db335 | 618 | |
03ba3782 JA |
619 | if (!bdi_cap_flush_forker(bdi)) |
620 | bdi_wb_shutdown(bdi); | |
76f1418b | 621 | bdi_debug_unregister(bdi); |
cf0ca9fe PZ |
622 | device_unregister(bdi->dev); |
623 | bdi->dev = NULL; | |
624 | } | |
625 | } | |
626 | EXPORT_SYMBOL(bdi_unregister); | |
3fcfab16 | 627 | |
6467716a AB |
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 | ||
b2e8fb6e PZ |
640 | int bdi_init(struct backing_dev_info *bdi) |
641 | { | |
03ba3782 | 642 | int i, err; |
b2e8fb6e | 643 | |
cf0ca9fe PZ |
644 | bdi->dev = NULL; |
645 | ||
189d3c4a | 646 | bdi->min_ratio = 0; |
a42dde04 PZ |
647 | bdi->max_ratio = 100; |
648 | bdi->max_prop_frac = PROP_FRAC_BASE; | |
03ba3782 | 649 | spin_lock_init(&bdi->wb_lock); |
66f3b8e2 | 650 | INIT_LIST_HEAD(&bdi->bdi_list); |
03ba3782 JA |
651 | INIT_LIST_HEAD(&bdi->work_list); |
652 | ||
653 | bdi_wb_init(&bdi->wb, bdi); | |
654 | ||
b2e8fb6e | 655 | for (i = 0; i < NR_BDI_STAT_ITEMS; i++) { |
ea319518 | 656 | err = percpu_counter_init(&bdi->bdi_stat[i], 0); |
04fbfdc1 PZ |
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: | |
4b01a0b1 | 666 | while (i--) |
04fbfdc1 | 667 | percpu_counter_destroy(&bdi->bdi_stat[i]); |
b2e8fb6e PZ |
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 | ||
ce5f8e77 JA |
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 | } | |
66f3b8e2 | 691 | |
cf0ca9fe PZ |
692 | bdi_unregister(bdi); |
693 | ||
b2e8fb6e PZ |
694 | for (i = 0; i < NR_BDI_STAT_ITEMS; i++) |
695 | percpu_counter_destroy(&bdi->bdi_stat[i]); | |
04fbfdc1 PZ |
696 | |
697 | prop_local_destroy_percpu(&bdi->completions); | |
b2e8fb6e PZ |
698 | } |
699 | EXPORT_SYMBOL(bdi_destroy); | |
700 | ||
c3c53206 JA |
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 | ||
3fcfab16 AM |
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 | ||
1faa16d2 | 733 | void clear_bdi_congested(struct backing_dev_info *bdi, int sync) |
3fcfab16 AM |
734 | { |
735 | enum bdi_state bit; | |
1faa16d2 | 736 | wait_queue_head_t *wqh = &congestion_wqh[sync]; |
3fcfab16 | 737 | |
1faa16d2 | 738 | bit = sync ? BDI_sync_congested : BDI_async_congested; |
3fcfab16 AM |
739 | clear_bit(bit, &bdi->state); |
740 | smp_mb__after_clear_bit(); | |
741 | if (waitqueue_active(wqh)) | |
742 | wake_up(wqh); | |
743 | } | |
744 | EXPORT_SYMBOL(clear_bdi_congested); | |
745 | ||
1faa16d2 | 746 | void set_bdi_congested(struct backing_dev_info *bdi, int sync) |
3fcfab16 AM |
747 | { |
748 | enum bdi_state bit; | |
749 | ||
1faa16d2 | 750 | bit = sync ? BDI_sync_congested : BDI_async_congested; |
3fcfab16 AM |
751 | set_bit(bit, &bdi->state); |
752 | } | |
753 | EXPORT_SYMBOL(set_bdi_congested); | |
754 | ||
755 | /** | |
756 | * congestion_wait - wait for a backing_dev to become uncongested | |
8aa7e847 | 757 | * @sync: SYNC or ASYNC IO |
3fcfab16 AM |
758 | * @timeout: timeout in jiffies |
759 | * | |
760 | * Waits for up to @timeout jiffies for a backing_dev (any backing_dev) to exit | |
761 | * write congestion. If no backing_devs are congested then just wait for the | |
762 | * next write to be completed. | |
763 | */ | |
8aa7e847 | 764 | long congestion_wait(int sync, long timeout) |
3fcfab16 AM |
765 | { |
766 | long ret; | |
767 | DEFINE_WAIT(wait); | |
8aa7e847 | 768 | wait_queue_head_t *wqh = &congestion_wqh[sync]; |
3fcfab16 AM |
769 | |
770 | prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); | |
771 | ret = io_schedule_timeout(timeout); | |
772 | finish_wait(wqh, &wait); | |
773 | return ret; | |
774 | } | |
775 | EXPORT_SYMBOL(congestion_wait); | |
04fbfdc1 | 776 |