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 | 17 | struct backing_dev_info default_backing_dev_info = { |
d993831f | 18 | .name = "default", |
26160158 JA |
19 | .ra_pages = VM_MAX_READAHEAD * 1024 / PAGE_CACHE_SIZE, |
20 | .state = 0, | |
21 | .capabilities = BDI_CAP_MAP_COPY, | |
26160158 JA |
22 | }; |
23 | EXPORT_SYMBOL_GPL(default_backing_dev_info); | |
cf0ca9fe | 24 | |
5129a469 JE |
25 | struct backing_dev_info noop_backing_dev_info = { |
26 | .name = "noop", | |
976e48f8 | 27 | .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK, |
5129a469 JE |
28 | }; |
29 | EXPORT_SYMBOL_GPL(noop_backing_dev_info); | |
30 | ||
cf0ca9fe | 31 | static struct class *bdi_class; |
cfc4ba53 JA |
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 | */ | |
03ba3782 | 38 | DEFINE_SPINLOCK(bdi_lock); |
66f3b8e2 | 39 | LIST_HEAD(bdi_list); |
03ba3782 JA |
40 | LIST_HEAD(bdi_pending_list); |
41 | ||
f758eeab CH |
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 | ||
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; | |
345227d7 | 71 | unsigned long nr_dirty, nr_io, nr_more_io; |
f09b00d3 JA |
72 | struct inode *inode; |
73 | ||
345227d7 | 74 | nr_dirty = nr_io = nr_more_io = 0; |
f758eeab | 75 | spin_lock(&wb->list_lock); |
7ccf19a8 | 76 | list_for_each_entry(inode, &wb->b_dirty, i_wb_list) |
c1955ce3 | 77 | nr_dirty++; |
7ccf19a8 | 78 | list_for_each_entry(inode, &wb->b_io, i_wb_list) |
c1955ce3 | 79 | nr_io++; |
7ccf19a8 | 80 | list_for_each_entry(inode, &wb->b_more_io, i_wb_list) |
c1955ce3 | 81 | nr_more_io++; |
f758eeab | 82 | spin_unlock(&wb->list_lock); |
76f1418b | 83 | |
16c4042f WF |
84 | global_dirty_limits(&background_thresh, &dirty_thresh); |
85 | bdi_thresh = bdi_dirty_limit(bdi, dirty_thresh); | |
76f1418b MS |
86 | |
87 | #define K(x) ((x) << (PAGE_SHIFT - 10)) | |
88 | seq_printf(m, | |
00821b00 WF |
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" | |
c8e28ce0 | 94 | "BdiDirtied: %10lu kB\n" |
00821b00 WF |
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", | |
76f1418b MS |
102 | (unsigned long) K(bdi_stat(bdi, BDI_WRITEBACK)), |
103 | (unsigned long) K(bdi_stat(bdi, BDI_RECLAIMABLE)), | |
f7d2b1ec JK |
104 | K(bdi_thresh), |
105 | K(dirty_thresh), | |
106 | K(background_thresh), | |
c8e28ce0 | 107 | (unsigned long) K(bdi_stat(bdi, BDI_DIRTIED)), |
f7d2b1ec | 108 | (unsigned long) K(bdi_stat(bdi, BDI_WRITTEN)), |
00821b00 | 109 | (unsigned long) K(bdi->write_bandwidth), |
f7d2b1ec JK |
110 | nr_dirty, |
111 | nr_io, | |
112 | nr_more_io, | |
c1955ce3 | 113 | !list_empty(&bdi->bdi_list), bdi->state); |
76f1418b MS |
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 | ||
cf0ca9fe PZ |
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 | ||
189d3c4a PZ |
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 | ||
a42dde04 PZ |
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 | ||
cf0ca9fe PZ |
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), | |
189d3c4a | 226 | __ATTR_RW(min_ratio), |
a42dde04 | 227 | __ATTR_RW(max_ratio), |
cf0ca9fe PZ |
228 | __ATTR_NULL, |
229 | }; | |
230 | ||
231 | static __init int bdi_class_init(void) | |
232 | { | |
233 | bdi_class = class_create(THIS_MODULE, "bdi"); | |
14421453 AB |
234 | if (IS_ERR(bdi_class)) |
235 | return PTR_ERR(bdi_class); | |
236 | ||
cf0ca9fe | 237 | bdi_class->dev_attrs = bdi_dev_attrs; |
76f1418b | 238 | bdi_debug_init(); |
cf0ca9fe PZ |
239 | return 0; |
240 | } | |
76f1418b | 241 | postcore_initcall(bdi_class_init); |
cf0ca9fe | 242 | |
26160158 JA |
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"); | |
976e48f8 | 250 | err = bdi_init(&noop_backing_dev_info); |
26160158 JA |
251 | |
252 | return err; | |
253 | } | |
254 | subsys_initcall(default_bdi_init); | |
255 | ||
03ba3782 JA |
256 | int bdi_has_dirty_io(struct backing_dev_info *bdi) |
257 | { | |
258 | return wb_has_dirty_io(&bdi->wb); | |
259 | } | |
260 | ||
6467716a AB |
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) { | |
60332023 | 267 | trace_writeback_wake_thread(bdi); |
6467716a | 268 | wake_up_process(bdi->wb.task); |
2673b4cf | 269 | } else if (bdi->dev) { |
6467716a AB |
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 | */ | |
60332023 | 275 | trace_writeback_wake_forker_thread(bdi); |
6467716a AB |
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 | ||
fff5b85a AB |
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 | ||
5a042aa4 JK |
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 | ||
6f904ff0 | 323 | static int bdi_forker_thread(void *ptr) |
03ba3782 JA |
324 | { |
325 | struct bdi_writeback *me = ptr; | |
326 | ||
766f9164 | 327 | current->flags |= PF_SWAPWRITE; |
c1955ce3 CH |
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); | |
03ba3782 JA |
334 | |
335 | for (;;) { | |
fff5b85a | 336 | struct task_struct *task = NULL; |
78c40cb6 | 337 | struct backing_dev_info *bdi; |
adf39240 AB |
338 | enum { |
339 | NO_ACTION, /* Nothing to do */ | |
340 | FORK_THREAD, /* Fork bdi thread */ | |
fff5b85a | 341 | KILL_THREAD, /* Kill inactive bdi thread */ |
adf39240 | 342 | } action = NO_ACTION; |
03ba3782 JA |
343 | |
344 | /* | |
345 | * Temporary measure, we want to make sure we don't see | |
346 | * dirty data on the default backing_dev_info | |
347 | */ | |
6467716a AB |
348 | if (wb_has_dirty_io(me) || !list_empty(&me->bdi->work_list)) { |
349 | del_timer(&me->wakeup_timer); | |
03ba3782 | 350 | wb_do_writeback(me, 0); |
6467716a | 351 | } |
03ba3782 | 352 | |
cfc4ba53 | 353 | spin_lock_bh(&bdi_lock); |
09f40f98 JK |
354 | /* |
355 | * In the following loop we are going to check whether we have | |
356 | * some work to do without any synchronization with tasks | |
20c8c628 AM |
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. | |
09f40f98 | 359 | */ |
c5f7ad23 | 360 | set_current_state(TASK_INTERRUPTIBLE); |
03ba3782 | 361 | |
78c40cb6 | 362 | list_for_each_entry(bdi, &bdi_list, bdi_list) { |
adf39240 AB |
363 | bool have_dirty_io; |
364 | ||
365 | if (!bdi_cap_writeback_dirty(bdi) || | |
366 | bdi_cap_flush_forker(bdi)) | |
03ba3782 JA |
367 | continue; |
368 | ||
080dcec4 AB |
369 | WARN(!test_bit(BDI_registered, &bdi->state), |
370 | "bdi %p/%s is not registered!\n", bdi, bdi->name); | |
371 | ||
adf39240 AB |
372 | have_dirty_io = !list_empty(&bdi->work_list) || |
373 | wb_has_dirty_io(&bdi->wb); | |
78c40cb6 AB |
374 | |
375 | /* | |
adf39240 AB |
376 | * If the bdi has work to do, but the thread does not |
377 | * exist - create it. | |
78c40cb6 | 378 | */ |
adf39240 AB |
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 | } | |
fff5b85a | 388 | |
6bf05d03 JA |
389 | spin_lock(&bdi->wb_lock); |
390 | ||
fff5b85a AB |
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 | } | |
6bf05d03 | 407 | spin_unlock(&bdi->wb_lock); |
03ba3782 | 408 | } |
080dcec4 | 409 | spin_unlock_bh(&bdi_lock); |
03ba3782 | 410 | |
c4ec7908 AB |
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 | ||
adf39240 AB |
415 | switch (action) { |
416 | case FORK_THREAD: | |
417 | __set_current_state(TASK_RUNNING); | |
6628bc74 AB |
418 | task = kthread_create(bdi_writeback_thread, &bdi->wb, |
419 | "flush-%s", dev_name(bdi->dev)); | |
adf39240 AB |
420 | if (IS_ERR(task)) { |
421 | /* | |
422 | * If thread creation fails, force writeout of | |
d46db3d5 WF |
423 | * the bdi from the thread. Hopefully 1024 is |
424 | * large enough for efficient IO. | |
adf39240 | 425 | */ |
0e175a18 CW |
426 | writeback_inodes_wb(&bdi->wb, 1024, |
427 | WB_REASON_FORKER_THREAD); | |
fff5b85a AB |
428 | } else { |
429 | /* | |
430 | * The spinlock makes sure we do not lose | |
431 | * wake-ups when racing with 'bdi_queue_work()'. | |
6628bc74 AB |
432 | * And as soon as the bdi thread is visible, we |
433 | * can start it. | |
fff5b85a | 434 | */ |
6467716a | 435 | spin_lock_bh(&bdi->wb_lock); |
adf39240 | 436 | bdi->wb.task = task; |
6467716a | 437 | spin_unlock_bh(&bdi->wb_lock); |
6628bc74 | 438 | wake_up_process(task); |
fff5b85a | 439 | } |
5a042aa4 | 440 | bdi_clear_pending(bdi); |
fff5b85a AB |
441 | break; |
442 | ||
443 | case KILL_THREAD: | |
444 | __set_current_state(TASK_RUNNING); | |
445 | kthread_stop(task); | |
5a042aa4 | 446 | bdi_clear_pending(bdi); |
adf39240 | 447 | break; |
03ba3782 | 448 | |
adf39240 | 449 | case NO_ACTION: |
253c34e9 AB |
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()); | |
6423104b | 459 | else |
253c34e9 | 460 | schedule_timeout(msecs_to_jiffies(dirty_writeback_interval * 10)); |
03ba3782 | 461 | try_to_freeze(); |
5a042aa4 | 462 | break; |
03ba3782 | 463 | } |
03ba3782 JA |
464 | } |
465 | ||
466 | return 0; | |
467 | } | |
468 | ||
cfc4ba53 JA |
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 | ||
ef323088 | 478 | synchronize_rcu_expedited(); |
cfc4ba53 JA |
479 | } |
480 | ||
cf0ca9fe PZ |
481 | int bdi_register(struct backing_dev_info *bdi, struct device *parent, |
482 | const char *fmt, ...) | |
483 | { | |
cf0ca9fe | 484 | va_list args; |
cf0ca9fe PZ |
485 | struct device *dev; |
486 | ||
69fc208b | 487 | if (bdi->dev) /* The driver needs to use separate queues per device */ |
c284de61 | 488 | return 0; |
f1d0b063 | 489 | |
cf0ca9fe | 490 | va_start(args, fmt); |
19051c50 | 491 | dev = device_create_vargs(bdi_class, parent, MKDEV(0, 0), bdi, fmt, args); |
cf0ca9fe | 492 | va_end(args); |
c284de61 AB |
493 | if (IS_ERR(dev)) |
494 | return PTR_ERR(dev); | |
66f3b8e2 | 495 | |
cf0ca9fe | 496 | bdi->dev = dev; |
cf0ca9fe | 497 | |
03ba3782 JA |
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 | ||
6f904ff0 | 506 | wb->task = kthread_run(bdi_forker_thread, wb, "bdi-%s", |
03ba3782 | 507 | dev_name(dev)); |
c284de61 AB |
508 | if (IS_ERR(wb->task)) |
509 | return PTR_ERR(wb->task); | |
03ba3782 JA |
510 | } |
511 | ||
512 | bdi_debug_register(bdi, dev_name(dev)); | |
500b067c | 513 | set_bit(BDI_registered, &bdi->state); |
c284de61 AB |
514 | |
515 | spin_lock_bh(&bdi_lock); | |
516 | list_add_tail_rcu(&bdi->bdi_list, &bdi_list); | |
517 | spin_unlock_bh(&bdi_lock); | |
518 | ||
455b2864 | 519 | trace_writeback_bdi_register(bdi); |
c284de61 | 520 | return 0; |
cf0ca9fe PZ |
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 | ||
03ba3782 JA |
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) | |
66f3b8e2 | 534 | { |
2673b4cf RV |
535 | struct task_struct *task; |
536 | ||
03ba3782 JA |
537 | if (!bdi_cap_writeback_dirty(bdi)) |
538 | return; | |
539 | ||
540 | /* | |
fff5b85a | 541 | * Make sure nobody finds us on the bdi_list anymore |
03ba3782 | 542 | */ |
fff5b85a | 543 | bdi_remove_from_list(bdi); |
03ba3782 JA |
544 | |
545 | /* | |
fff5b85a | 546 | * If setup is pending, wait for that to complete first |
03ba3782 | 547 | */ |
fff5b85a AB |
548 | wait_on_bit(&bdi->state, BDI_pending, bdi_sched_wait, |
549 | TASK_UNINTERRUPTIBLE); | |
03ba3782 JA |
550 | |
551 | /* | |
c1955ce3 | 552 | * Finally, kill the kernel thread. We don't need to be RCU |
8a32c441 | 553 | * safe anymore, since the bdi is gone from visibility. |
03ba3782 | 554 | */ |
2673b4cf RV |
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); | |
66f3b8e2 JA |
562 | } |
563 | ||
592b09a4 JA |
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) | |
95f28604 | 574 | sb->s_bdi = &default_backing_dev_info; |
592b09a4 JA |
575 | } |
576 | spin_unlock(&sb_lock); | |
577 | } | |
578 | ||
cf0ca9fe PZ |
579 | void bdi_unregister(struct backing_dev_info *bdi) |
580 | { | |
2673b4cf RV |
581 | struct device *dev = bdi->dev; |
582 | ||
583 | if (dev) { | |
ccb6108f | 584 | bdi_set_min_ratio(bdi, 0); |
455b2864 | 585 | trace_writeback_bdi_unregister(bdi); |
8c4db335 | 586 | bdi_prune_sb(bdi); |
6467716a | 587 | del_timer_sync(&bdi->wb.wakeup_timer); |
8c4db335 | 588 | |
03ba3782 JA |
589 | if (!bdi_cap_flush_forker(bdi)) |
590 | bdi_wb_shutdown(bdi); | |
76f1418b | 591 | bdi_debug_unregister(bdi); |
2673b4cf RV |
592 | |
593 | spin_lock_bh(&bdi->wb_lock); | |
cf0ca9fe | 594 | bdi->dev = NULL; |
2673b4cf RV |
595 | spin_unlock_bh(&bdi->wb_lock); |
596 | ||
597 | device_unregister(dev); | |
cf0ca9fe PZ |
598 | } |
599 | } | |
600 | EXPORT_SYMBOL(bdi_unregister); | |
3fcfab16 | 601 | |
6467716a AB |
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); | |
f758eeab | 611 | spin_lock_init(&wb->list_lock); |
6467716a AB |
612 | setup_timer(&wb->wakeup_timer, wakeup_timer_fn, (unsigned long)bdi); |
613 | } | |
614 | ||
e98be2d5 WF |
615 | /* |
616 | * Initial write bandwidth: 100 MB/s | |
617 | */ | |
618 | #define INIT_BW (100 << (20 - PAGE_SHIFT)) | |
619 | ||
b2e8fb6e PZ |
620 | int bdi_init(struct backing_dev_info *bdi) |
621 | { | |
03ba3782 | 622 | int i, err; |
b2e8fb6e | 623 | |
cf0ca9fe PZ |
624 | bdi->dev = NULL; |
625 | ||
189d3c4a | 626 | bdi->min_ratio = 0; |
a42dde04 | 627 | bdi->max_ratio = 100; |
eb608e3a | 628 | bdi->max_prop_frac = FPROP_FRAC_BASE; |
03ba3782 | 629 | spin_lock_init(&bdi->wb_lock); |
66f3b8e2 | 630 | INIT_LIST_HEAD(&bdi->bdi_list); |
03ba3782 JA |
631 | INIT_LIST_HEAD(&bdi->work_list); |
632 | ||
633 | bdi_wb_init(&bdi->wb, bdi); | |
634 | ||
b2e8fb6e | 635 | for (i = 0; i < NR_BDI_STAT_ITEMS; i++) { |
ea319518 | 636 | err = percpu_counter_init(&bdi->bdi_stat[i], 0); |
04fbfdc1 PZ |
637 | if (err) |
638 | goto err; | |
639 | } | |
640 | ||
641 | bdi->dirty_exceeded = 0; | |
e98be2d5 WF |
642 | |
643 | bdi->bw_time_stamp = jiffies; | |
644 | bdi->written_stamp = 0; | |
645 | ||
7381131c | 646 | bdi->balanced_dirty_ratelimit = INIT_BW; |
be3ffa27 | 647 | bdi->dirty_ratelimit = INIT_BW; |
e98be2d5 WF |
648 | bdi->write_bandwidth = INIT_BW; |
649 | bdi->avg_write_bandwidth = INIT_BW; | |
650 | ||
eb608e3a | 651 | err = fprop_local_init_percpu(&bdi->completions); |
04fbfdc1 PZ |
652 | |
653 | if (err) { | |
654 | err: | |
4b01a0b1 | 655 | while (i--) |
04fbfdc1 | 656 | percpu_counter_destroy(&bdi->bdi_stat[i]); |
b2e8fb6e PZ |
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 | ||
ce5f8e77 JA |
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 | ||
f758eeab | 674 | bdi_lock_two(&bdi->wb, dst); |
ce5f8e77 JA |
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); | |
f758eeab CH |
678 | spin_unlock(&bdi->wb.list_lock); |
679 | spin_unlock(&dst->list_lock); | |
ce5f8e77 | 680 | } |
66f3b8e2 | 681 | |
cf0ca9fe PZ |
682 | bdi_unregister(bdi); |
683 | ||
7a401a97 RV |
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 | ||
b2e8fb6e PZ |
692 | for (i = 0; i < NR_BDI_STAT_ITEMS; i++) |
693 | percpu_counter_destroy(&bdi->bdi_stat[i]); | |
04fbfdc1 | 694 | |
eb608e3a | 695 | fprop_local_destroy_percpu(&bdi->completions); |
b2e8fb6e PZ |
696 | } |
697 | EXPORT_SYMBOL(bdi_destroy); | |
698 | ||
c3c53206 JA |
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 | ||
3fcfab16 AM |
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 | }; | |
0e093d99 | 730 | static atomic_t nr_bdi_congested[2]; |
3fcfab16 | 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; |
0e093d99 MG |
738 | if (test_and_clear_bit(bit, &bdi->state)) |
739 | atomic_dec(&nr_bdi_congested[sync]); | |
3fcfab16 AM |
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; |
0e093d99 MG |
751 | if (!test_and_set_bit(bit, &bdi->state)) |
752 | atomic_inc(&nr_bdi_congested[sync]); | |
3fcfab16 AM |
753 | } |
754 | EXPORT_SYMBOL(set_bdi_congested); | |
755 | ||
756 | /** | |
757 | * congestion_wait - wait for a backing_dev to become uncongested | |
8aa7e847 | 758 | * @sync: SYNC or ASYNC IO |
3fcfab16 AM |
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 | */ | |
8aa7e847 | 765 | long congestion_wait(int sync, long timeout) |
3fcfab16 AM |
766 | { |
767 | long ret; | |
52bb9198 | 768 | unsigned long start = jiffies; |
3fcfab16 | 769 | DEFINE_WAIT(wait); |
8aa7e847 | 770 | wait_queue_head_t *wqh = &congestion_wqh[sync]; |
3fcfab16 AM |
771 | |
772 | prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); | |
773 | ret = io_schedule_timeout(timeout); | |
774 | finish_wait(wqh, &wait); | |
52bb9198 MG |
775 | |
776 | trace_writeback_congestion_wait(jiffies_to_usecs(timeout), | |
777 | jiffies_to_usecs(jiffies - start)); | |
778 | ||
3fcfab16 AM |
779 | return ret; |
780 | } | |
781 | EXPORT_SYMBOL(congestion_wait); | |
04fbfdc1 | 782 | |
0e093d99 MG |
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 | * | |
25985edc | 794 | * In the absence of zone congestion, cond_resched() is called to yield |
0e093d99 MG |
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); | |
3965c9ae WL |
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 | } |