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); | |
cf0ca9fe | 161 | unsigned long read_ahead_kb; |
7034ed13 | 162 | ssize_t ret; |
cf0ca9fe | 163 | |
7034ed13 NJ |
164 | ret = kstrtoul(buf, 10, &read_ahead_kb); |
165 | if (ret < 0) | |
166 | return ret; | |
167 | ||
168 | bdi->ra_pages = read_ahead_kb >> (PAGE_SHIFT - 10); | |
169 | ||
170 | return count; | |
cf0ca9fe PZ |
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); | |
189d3c4a | 190 | unsigned int ratio; |
7034ed13 NJ |
191 | ssize_t ret; |
192 | ||
193 | ret = kstrtouint(buf, 10, &ratio); | |
194 | if (ret < 0) | |
195 | return ret; | |
196 | ||
197 | ret = bdi_set_min_ratio(bdi, ratio); | |
198 | if (!ret) | |
199 | ret = count; | |
189d3c4a | 200 | |
189d3c4a PZ |
201 | return ret; |
202 | } | |
203 | BDI_SHOW(min_ratio, bdi->min_ratio) | |
204 | ||
a42dde04 PZ |
205 | static ssize_t max_ratio_store(struct device *dev, |
206 | struct device_attribute *attr, const char *buf, size_t count) | |
207 | { | |
208 | struct backing_dev_info *bdi = dev_get_drvdata(dev); | |
a42dde04 | 209 | unsigned int ratio; |
7034ed13 NJ |
210 | ssize_t ret; |
211 | ||
212 | ret = kstrtouint(buf, 10, &ratio); | |
213 | if (ret < 0) | |
214 | return ret; | |
215 | ||
216 | ret = bdi_set_max_ratio(bdi, ratio); | |
217 | if (!ret) | |
218 | ret = count; | |
a42dde04 | 219 | |
a42dde04 PZ |
220 | return ret; |
221 | } | |
222 | BDI_SHOW(max_ratio, bdi->max_ratio) | |
223 | ||
7d311cda DW |
224 | static ssize_t stable_pages_required_show(struct device *dev, |
225 | struct device_attribute *attr, | |
226 | char *page) | |
227 | { | |
228 | struct backing_dev_info *bdi = dev_get_drvdata(dev); | |
229 | ||
230 | return snprintf(page, PAGE_SIZE-1, "%d\n", | |
231 | bdi_cap_stable_pages_required(bdi) ? 1 : 0); | |
232 | } | |
233 | ||
cf0ca9fe PZ |
234 | #define __ATTR_RW(attr) __ATTR(attr, 0644, attr##_show, attr##_store) |
235 | ||
236 | static struct device_attribute bdi_dev_attrs[] = { | |
237 | __ATTR_RW(read_ahead_kb), | |
189d3c4a | 238 | __ATTR_RW(min_ratio), |
a42dde04 | 239 | __ATTR_RW(max_ratio), |
7d311cda | 240 | __ATTR_RO(stable_pages_required), |
cf0ca9fe PZ |
241 | __ATTR_NULL, |
242 | }; | |
243 | ||
244 | static __init int bdi_class_init(void) | |
245 | { | |
246 | bdi_class = class_create(THIS_MODULE, "bdi"); | |
14421453 AB |
247 | if (IS_ERR(bdi_class)) |
248 | return PTR_ERR(bdi_class); | |
249 | ||
cf0ca9fe | 250 | bdi_class->dev_attrs = bdi_dev_attrs; |
76f1418b | 251 | bdi_debug_init(); |
cf0ca9fe PZ |
252 | return 0; |
253 | } | |
76f1418b | 254 | postcore_initcall(bdi_class_init); |
cf0ca9fe | 255 | |
26160158 JA |
256 | static int __init default_bdi_init(void) |
257 | { | |
258 | int err; | |
259 | ||
260 | err = bdi_init(&default_backing_dev_info); | |
261 | if (!err) | |
262 | bdi_register(&default_backing_dev_info, NULL, "default"); | |
976e48f8 | 263 | err = bdi_init(&noop_backing_dev_info); |
26160158 JA |
264 | |
265 | return err; | |
266 | } | |
267 | subsys_initcall(default_bdi_init); | |
268 | ||
03ba3782 JA |
269 | int bdi_has_dirty_io(struct backing_dev_info *bdi) |
270 | { | |
271 | return wb_has_dirty_io(&bdi->wb); | |
272 | } | |
273 | ||
6467716a AB |
274 | static void wakeup_timer_fn(unsigned long data) |
275 | { | |
276 | struct backing_dev_info *bdi = (struct backing_dev_info *)data; | |
277 | ||
278 | spin_lock_bh(&bdi->wb_lock); | |
279 | if (bdi->wb.task) { | |
60332023 | 280 | trace_writeback_wake_thread(bdi); |
6467716a | 281 | wake_up_process(bdi->wb.task); |
2673b4cf | 282 | } else if (bdi->dev) { |
6467716a AB |
283 | /* |
284 | * When bdi tasks are inactive for long time, they are killed. | |
285 | * In this case we have to wake-up the forker thread which | |
286 | * should create and run the bdi thread. | |
287 | */ | |
60332023 | 288 | trace_writeback_wake_forker_thread(bdi); |
6467716a AB |
289 | wake_up_process(default_backing_dev_info.wb.task); |
290 | } | |
291 | spin_unlock_bh(&bdi->wb_lock); | |
292 | } | |
293 | ||
294 | /* | |
295 | * This function is used when the first inode for this bdi is marked dirty. It | |
296 | * wakes-up the corresponding bdi thread which should then take care of the | |
297 | * periodic background write-out of dirty inodes. Since the write-out would | |
298 | * starts only 'dirty_writeback_interval' centisecs from now anyway, we just | |
299 | * set up a timer which wakes the bdi thread up later. | |
300 | * | |
301 | * Note, we wouldn't bother setting up the timer, but this function is on the | |
302 | * fast-path (used by '__mark_inode_dirty()'), so we save few context switches | |
303 | * by delaying the wake-up. | |
304 | */ | |
305 | void bdi_wakeup_thread_delayed(struct backing_dev_info *bdi) | |
306 | { | |
307 | unsigned long timeout; | |
308 | ||
309 | timeout = msecs_to_jiffies(dirty_writeback_interval * 10); | |
310 | mod_timer(&bdi->wb.wakeup_timer, jiffies + timeout); | |
311 | } | |
312 | ||
fff5b85a AB |
313 | /* |
314 | * Calculate the longest interval (jiffies) bdi threads are allowed to be | |
315 | * inactive. | |
316 | */ | |
317 | static unsigned long bdi_longest_inactive(void) | |
318 | { | |
319 | unsigned long interval; | |
320 | ||
321 | interval = msecs_to_jiffies(dirty_writeback_interval * 10); | |
322 | return max(5UL * 60 * HZ, interval); | |
323 | } | |
324 | ||
5a042aa4 JK |
325 | /* |
326 | * Clear pending bit and wakeup anybody waiting for flusher thread creation or | |
327 | * shutdown | |
328 | */ | |
329 | static void bdi_clear_pending(struct backing_dev_info *bdi) | |
330 | { | |
331 | clear_bit(BDI_pending, &bdi->state); | |
332 | smp_mb__after_clear_bit(); | |
333 | wake_up_bit(&bdi->state, BDI_pending); | |
334 | } | |
335 | ||
6f904ff0 | 336 | static int bdi_forker_thread(void *ptr) |
03ba3782 JA |
337 | { |
338 | struct bdi_writeback *me = ptr; | |
339 | ||
766f9164 | 340 | current->flags |= PF_SWAPWRITE; |
c1955ce3 CH |
341 | set_freezable(); |
342 | ||
343 | /* | |
344 | * Our parent may run at a different priority, just set us to normal | |
345 | */ | |
346 | set_user_nice(current, 0); | |
03ba3782 JA |
347 | |
348 | for (;;) { | |
fff5b85a | 349 | struct task_struct *task = NULL; |
78c40cb6 | 350 | struct backing_dev_info *bdi; |
adf39240 AB |
351 | enum { |
352 | NO_ACTION, /* Nothing to do */ | |
353 | FORK_THREAD, /* Fork bdi thread */ | |
fff5b85a | 354 | KILL_THREAD, /* Kill inactive bdi thread */ |
adf39240 | 355 | } action = NO_ACTION; |
03ba3782 JA |
356 | |
357 | /* | |
358 | * Temporary measure, we want to make sure we don't see | |
359 | * dirty data on the default backing_dev_info | |
360 | */ | |
6467716a AB |
361 | if (wb_has_dirty_io(me) || !list_empty(&me->bdi->work_list)) { |
362 | del_timer(&me->wakeup_timer); | |
03ba3782 | 363 | wb_do_writeback(me, 0); |
6467716a | 364 | } |
03ba3782 | 365 | |
cfc4ba53 | 366 | spin_lock_bh(&bdi_lock); |
09f40f98 JK |
367 | /* |
368 | * In the following loop we are going to check whether we have | |
369 | * some work to do without any synchronization with tasks | |
20c8c628 AM |
370 | * waking us up to do work for them. Set the task state here |
371 | * so that we don't miss wakeups after verifying conditions. | |
09f40f98 | 372 | */ |
c5f7ad23 | 373 | set_current_state(TASK_INTERRUPTIBLE); |
03ba3782 | 374 | |
78c40cb6 | 375 | list_for_each_entry(bdi, &bdi_list, bdi_list) { |
adf39240 AB |
376 | bool have_dirty_io; |
377 | ||
378 | if (!bdi_cap_writeback_dirty(bdi) || | |
379 | bdi_cap_flush_forker(bdi)) | |
03ba3782 JA |
380 | continue; |
381 | ||
080dcec4 AB |
382 | WARN(!test_bit(BDI_registered, &bdi->state), |
383 | "bdi %p/%s is not registered!\n", bdi, bdi->name); | |
384 | ||
adf39240 AB |
385 | have_dirty_io = !list_empty(&bdi->work_list) || |
386 | wb_has_dirty_io(&bdi->wb); | |
78c40cb6 AB |
387 | |
388 | /* | |
adf39240 AB |
389 | * If the bdi has work to do, but the thread does not |
390 | * exist - create it. | |
78c40cb6 | 391 | */ |
adf39240 AB |
392 | if (!bdi->wb.task && have_dirty_io) { |
393 | /* | |
394 | * Set the pending bit - if someone will try to | |
395 | * unregister this bdi - it'll wait on this bit. | |
396 | */ | |
397 | set_bit(BDI_pending, &bdi->state); | |
398 | action = FORK_THREAD; | |
399 | break; | |
400 | } | |
fff5b85a | 401 | |
6bf05d03 JA |
402 | spin_lock(&bdi->wb_lock); |
403 | ||
fff5b85a AB |
404 | /* |
405 | * If there is no work to do and the bdi thread was | |
406 | * inactive long enough - kill it. The wb_lock is taken | |
407 | * to make sure no-one adds more work to this bdi and | |
408 | * wakes the bdi thread up. | |
409 | */ | |
410 | if (bdi->wb.task && !have_dirty_io && | |
411 | time_after(jiffies, bdi->wb.last_active + | |
412 | bdi_longest_inactive())) { | |
413 | task = bdi->wb.task; | |
414 | bdi->wb.task = NULL; | |
415 | spin_unlock(&bdi->wb_lock); | |
416 | set_bit(BDI_pending, &bdi->state); | |
417 | action = KILL_THREAD; | |
418 | break; | |
419 | } | |
6bf05d03 | 420 | spin_unlock(&bdi->wb_lock); |
03ba3782 | 421 | } |
080dcec4 | 422 | spin_unlock_bh(&bdi_lock); |
03ba3782 | 423 | |
c4ec7908 AB |
424 | /* Keep working if default bdi still has things to do */ |
425 | if (!list_empty(&me->bdi->work_list)) | |
426 | __set_current_state(TASK_RUNNING); | |
427 | ||
adf39240 AB |
428 | switch (action) { |
429 | case FORK_THREAD: | |
430 | __set_current_state(TASK_RUNNING); | |
6628bc74 AB |
431 | task = kthread_create(bdi_writeback_thread, &bdi->wb, |
432 | "flush-%s", dev_name(bdi->dev)); | |
adf39240 AB |
433 | if (IS_ERR(task)) { |
434 | /* | |
435 | * If thread creation fails, force writeout of | |
d46db3d5 WF |
436 | * the bdi from the thread. Hopefully 1024 is |
437 | * large enough for efficient IO. | |
adf39240 | 438 | */ |
0e175a18 CW |
439 | writeback_inodes_wb(&bdi->wb, 1024, |
440 | WB_REASON_FORKER_THREAD); | |
fff5b85a AB |
441 | } else { |
442 | /* | |
443 | * The spinlock makes sure we do not lose | |
444 | * wake-ups when racing with 'bdi_queue_work()'. | |
6628bc74 AB |
445 | * And as soon as the bdi thread is visible, we |
446 | * can start it. | |
fff5b85a | 447 | */ |
6467716a | 448 | spin_lock_bh(&bdi->wb_lock); |
adf39240 | 449 | bdi->wb.task = task; |
6467716a | 450 | spin_unlock_bh(&bdi->wb_lock); |
6628bc74 | 451 | wake_up_process(task); |
fff5b85a | 452 | } |
5a042aa4 | 453 | bdi_clear_pending(bdi); |
fff5b85a AB |
454 | break; |
455 | ||
456 | case KILL_THREAD: | |
457 | __set_current_state(TASK_RUNNING); | |
458 | kthread_stop(task); | |
5a042aa4 | 459 | bdi_clear_pending(bdi); |
adf39240 | 460 | break; |
03ba3782 | 461 | |
adf39240 | 462 | case NO_ACTION: |
253c34e9 AB |
463 | if (!wb_has_dirty_io(me) || !dirty_writeback_interval) |
464 | /* | |
465 | * There are no dirty data. The only thing we | |
466 | * should now care about is checking for | |
467 | * inactive bdi threads and killing them. Thus, | |
468 | * let's sleep for longer time, save energy and | |
469 | * be friendly for battery-driven devices. | |
470 | */ | |
471 | schedule_timeout(bdi_longest_inactive()); | |
6423104b | 472 | else |
253c34e9 | 473 | schedule_timeout(msecs_to_jiffies(dirty_writeback_interval * 10)); |
03ba3782 | 474 | try_to_freeze(); |
5a042aa4 | 475 | break; |
03ba3782 | 476 | } |
03ba3782 JA |
477 | } |
478 | ||
479 | return 0; | |
480 | } | |
481 | ||
cfc4ba53 JA |
482 | /* |
483 | * Remove bdi from bdi_list, and ensure that it is no longer visible | |
484 | */ | |
485 | static void bdi_remove_from_list(struct backing_dev_info *bdi) | |
486 | { | |
487 | spin_lock_bh(&bdi_lock); | |
488 | list_del_rcu(&bdi->bdi_list); | |
489 | spin_unlock_bh(&bdi_lock); | |
490 | ||
ef323088 | 491 | synchronize_rcu_expedited(); |
cfc4ba53 JA |
492 | } |
493 | ||
cf0ca9fe PZ |
494 | int bdi_register(struct backing_dev_info *bdi, struct device *parent, |
495 | const char *fmt, ...) | |
496 | { | |
cf0ca9fe | 497 | va_list args; |
cf0ca9fe PZ |
498 | struct device *dev; |
499 | ||
69fc208b | 500 | if (bdi->dev) /* The driver needs to use separate queues per device */ |
c284de61 | 501 | return 0; |
f1d0b063 | 502 | |
cf0ca9fe | 503 | va_start(args, fmt); |
19051c50 | 504 | dev = device_create_vargs(bdi_class, parent, MKDEV(0, 0), bdi, fmt, args); |
cf0ca9fe | 505 | va_end(args); |
c284de61 AB |
506 | if (IS_ERR(dev)) |
507 | return PTR_ERR(dev); | |
66f3b8e2 | 508 | |
cf0ca9fe | 509 | bdi->dev = dev; |
cf0ca9fe | 510 | |
03ba3782 JA |
511 | /* |
512 | * Just start the forker thread for our default backing_dev_info, | |
513 | * and add other bdi's to the list. They will get a thread created | |
514 | * on-demand when they need it. | |
515 | */ | |
516 | if (bdi_cap_flush_forker(bdi)) { | |
517 | struct bdi_writeback *wb = &bdi->wb; | |
518 | ||
6f904ff0 | 519 | wb->task = kthread_run(bdi_forker_thread, wb, "bdi-%s", |
03ba3782 | 520 | dev_name(dev)); |
c284de61 AB |
521 | if (IS_ERR(wb->task)) |
522 | return PTR_ERR(wb->task); | |
03ba3782 JA |
523 | } |
524 | ||
525 | bdi_debug_register(bdi, dev_name(dev)); | |
500b067c | 526 | set_bit(BDI_registered, &bdi->state); |
c284de61 AB |
527 | |
528 | spin_lock_bh(&bdi_lock); | |
529 | list_add_tail_rcu(&bdi->bdi_list, &bdi_list); | |
530 | spin_unlock_bh(&bdi_lock); | |
531 | ||
455b2864 | 532 | trace_writeback_bdi_register(bdi); |
c284de61 | 533 | return 0; |
cf0ca9fe PZ |
534 | } |
535 | EXPORT_SYMBOL(bdi_register); | |
536 | ||
537 | int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev) | |
538 | { | |
539 | return bdi_register(bdi, NULL, "%u:%u", MAJOR(dev), MINOR(dev)); | |
540 | } | |
541 | EXPORT_SYMBOL(bdi_register_dev); | |
542 | ||
03ba3782 JA |
543 | /* |
544 | * Remove bdi from the global list and shutdown any threads we have running | |
545 | */ | |
546 | static void bdi_wb_shutdown(struct backing_dev_info *bdi) | |
66f3b8e2 | 547 | { |
2673b4cf RV |
548 | struct task_struct *task; |
549 | ||
03ba3782 JA |
550 | if (!bdi_cap_writeback_dirty(bdi)) |
551 | return; | |
552 | ||
553 | /* | |
fff5b85a | 554 | * Make sure nobody finds us on the bdi_list anymore |
03ba3782 | 555 | */ |
fff5b85a | 556 | bdi_remove_from_list(bdi); |
03ba3782 JA |
557 | |
558 | /* | |
fff5b85a | 559 | * If setup is pending, wait for that to complete first |
03ba3782 | 560 | */ |
fff5b85a AB |
561 | wait_on_bit(&bdi->state, BDI_pending, bdi_sched_wait, |
562 | TASK_UNINTERRUPTIBLE); | |
03ba3782 JA |
563 | |
564 | /* | |
c1955ce3 | 565 | * Finally, kill the kernel thread. We don't need to be RCU |
8a32c441 | 566 | * safe anymore, since the bdi is gone from visibility. |
03ba3782 | 567 | */ |
2673b4cf RV |
568 | spin_lock_bh(&bdi->wb_lock); |
569 | task = bdi->wb.task; | |
570 | bdi->wb.task = NULL; | |
571 | spin_unlock_bh(&bdi->wb_lock); | |
572 | ||
573 | if (task) | |
574 | kthread_stop(task); | |
66f3b8e2 JA |
575 | } |
576 | ||
592b09a4 JA |
577 | /* |
578 | * This bdi is going away now, make sure that no super_blocks point to it | |
579 | */ | |
580 | static void bdi_prune_sb(struct backing_dev_info *bdi) | |
581 | { | |
582 | struct super_block *sb; | |
583 | ||
584 | spin_lock(&sb_lock); | |
585 | list_for_each_entry(sb, &super_blocks, s_list) { | |
586 | if (sb->s_bdi == bdi) | |
95f28604 | 587 | sb->s_bdi = &default_backing_dev_info; |
592b09a4 JA |
588 | } |
589 | spin_unlock(&sb_lock); | |
590 | } | |
591 | ||
cf0ca9fe PZ |
592 | void bdi_unregister(struct backing_dev_info *bdi) |
593 | { | |
2673b4cf RV |
594 | struct device *dev = bdi->dev; |
595 | ||
596 | if (dev) { | |
ccb6108f | 597 | bdi_set_min_ratio(bdi, 0); |
455b2864 | 598 | trace_writeback_bdi_unregister(bdi); |
8c4db335 | 599 | bdi_prune_sb(bdi); |
6467716a | 600 | del_timer_sync(&bdi->wb.wakeup_timer); |
8c4db335 | 601 | |
03ba3782 JA |
602 | if (!bdi_cap_flush_forker(bdi)) |
603 | bdi_wb_shutdown(bdi); | |
76f1418b | 604 | bdi_debug_unregister(bdi); |
2673b4cf RV |
605 | |
606 | spin_lock_bh(&bdi->wb_lock); | |
cf0ca9fe | 607 | bdi->dev = NULL; |
2673b4cf RV |
608 | spin_unlock_bh(&bdi->wb_lock); |
609 | ||
610 | device_unregister(dev); | |
cf0ca9fe PZ |
611 | } |
612 | } | |
613 | EXPORT_SYMBOL(bdi_unregister); | |
3fcfab16 | 614 | |
6467716a AB |
615 | static void bdi_wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi) |
616 | { | |
617 | memset(wb, 0, sizeof(*wb)); | |
618 | ||
619 | wb->bdi = bdi; | |
620 | wb->last_old_flush = jiffies; | |
621 | INIT_LIST_HEAD(&wb->b_dirty); | |
622 | INIT_LIST_HEAD(&wb->b_io); | |
623 | INIT_LIST_HEAD(&wb->b_more_io); | |
f758eeab | 624 | spin_lock_init(&wb->list_lock); |
6467716a AB |
625 | setup_timer(&wb->wakeup_timer, wakeup_timer_fn, (unsigned long)bdi); |
626 | } | |
627 | ||
e98be2d5 WF |
628 | /* |
629 | * Initial write bandwidth: 100 MB/s | |
630 | */ | |
631 | #define INIT_BW (100 << (20 - PAGE_SHIFT)) | |
632 | ||
b2e8fb6e PZ |
633 | int bdi_init(struct backing_dev_info *bdi) |
634 | { | |
03ba3782 | 635 | int i, err; |
b2e8fb6e | 636 | |
cf0ca9fe PZ |
637 | bdi->dev = NULL; |
638 | ||
189d3c4a | 639 | bdi->min_ratio = 0; |
a42dde04 | 640 | bdi->max_ratio = 100; |
eb608e3a | 641 | bdi->max_prop_frac = FPROP_FRAC_BASE; |
03ba3782 | 642 | spin_lock_init(&bdi->wb_lock); |
66f3b8e2 | 643 | INIT_LIST_HEAD(&bdi->bdi_list); |
03ba3782 JA |
644 | INIT_LIST_HEAD(&bdi->work_list); |
645 | ||
646 | bdi_wb_init(&bdi->wb, bdi); | |
647 | ||
b2e8fb6e | 648 | for (i = 0; i < NR_BDI_STAT_ITEMS; i++) { |
ea319518 | 649 | err = percpu_counter_init(&bdi->bdi_stat[i], 0); |
04fbfdc1 PZ |
650 | if (err) |
651 | goto err; | |
652 | } | |
653 | ||
654 | bdi->dirty_exceeded = 0; | |
e98be2d5 WF |
655 | |
656 | bdi->bw_time_stamp = jiffies; | |
657 | bdi->written_stamp = 0; | |
658 | ||
7381131c | 659 | bdi->balanced_dirty_ratelimit = INIT_BW; |
be3ffa27 | 660 | bdi->dirty_ratelimit = INIT_BW; |
e98be2d5 WF |
661 | bdi->write_bandwidth = INIT_BW; |
662 | bdi->avg_write_bandwidth = INIT_BW; | |
663 | ||
eb608e3a | 664 | err = fprop_local_init_percpu(&bdi->completions); |
04fbfdc1 PZ |
665 | |
666 | if (err) { | |
667 | err: | |
4b01a0b1 | 668 | while (i--) |
04fbfdc1 | 669 | percpu_counter_destroy(&bdi->bdi_stat[i]); |
b2e8fb6e PZ |
670 | } |
671 | ||
672 | return err; | |
673 | } | |
674 | EXPORT_SYMBOL(bdi_init); | |
675 | ||
676 | void bdi_destroy(struct backing_dev_info *bdi) | |
677 | { | |
678 | int i; | |
679 | ||
ce5f8e77 JA |
680 | /* |
681 | * Splice our entries to the default_backing_dev_info, if this | |
682 | * bdi disappears | |
683 | */ | |
684 | if (bdi_has_dirty_io(bdi)) { | |
685 | struct bdi_writeback *dst = &default_backing_dev_info.wb; | |
686 | ||
f758eeab | 687 | bdi_lock_two(&bdi->wb, dst); |
ce5f8e77 JA |
688 | list_splice(&bdi->wb.b_dirty, &dst->b_dirty); |
689 | list_splice(&bdi->wb.b_io, &dst->b_io); | |
690 | list_splice(&bdi->wb.b_more_io, &dst->b_more_io); | |
f758eeab CH |
691 | spin_unlock(&bdi->wb.list_lock); |
692 | spin_unlock(&dst->list_lock); | |
ce5f8e77 | 693 | } |
66f3b8e2 | 694 | |
cf0ca9fe PZ |
695 | bdi_unregister(bdi); |
696 | ||
7a401a97 RV |
697 | /* |
698 | * If bdi_unregister() had already been called earlier, the | |
699 | * wakeup_timer could still be armed because bdi_prune_sb() | |
700 | * can race with the bdi_wakeup_thread_delayed() calls from | |
701 | * __mark_inode_dirty(). | |
702 | */ | |
703 | del_timer_sync(&bdi->wb.wakeup_timer); | |
704 | ||
b2e8fb6e PZ |
705 | for (i = 0; i < NR_BDI_STAT_ITEMS; i++) |
706 | percpu_counter_destroy(&bdi->bdi_stat[i]); | |
04fbfdc1 | 707 | |
eb608e3a | 708 | fprop_local_destroy_percpu(&bdi->completions); |
b2e8fb6e PZ |
709 | } |
710 | EXPORT_SYMBOL(bdi_destroy); | |
711 | ||
c3c53206 JA |
712 | /* |
713 | * For use from filesystems to quickly init and register a bdi associated | |
714 | * with dirty writeback | |
715 | */ | |
716 | int bdi_setup_and_register(struct backing_dev_info *bdi, char *name, | |
717 | unsigned int cap) | |
718 | { | |
719 | char tmp[32]; | |
720 | int err; | |
721 | ||
722 | bdi->name = name; | |
723 | bdi->capabilities = cap; | |
724 | err = bdi_init(bdi); | |
725 | if (err) | |
726 | return err; | |
727 | ||
728 | sprintf(tmp, "%.28s%s", name, "-%d"); | |
729 | err = bdi_register(bdi, NULL, tmp, atomic_long_inc_return(&bdi_seq)); | |
730 | if (err) { | |
731 | bdi_destroy(bdi); | |
732 | return err; | |
733 | } | |
734 | ||
735 | return 0; | |
736 | } | |
737 | EXPORT_SYMBOL(bdi_setup_and_register); | |
738 | ||
3fcfab16 AM |
739 | static wait_queue_head_t congestion_wqh[2] = { |
740 | __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]), | |
741 | __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1]) | |
742 | }; | |
0e093d99 | 743 | static atomic_t nr_bdi_congested[2]; |
3fcfab16 | 744 | |
1faa16d2 | 745 | void clear_bdi_congested(struct backing_dev_info *bdi, int sync) |
3fcfab16 AM |
746 | { |
747 | enum bdi_state bit; | |
1faa16d2 | 748 | wait_queue_head_t *wqh = &congestion_wqh[sync]; |
3fcfab16 | 749 | |
1faa16d2 | 750 | bit = sync ? BDI_sync_congested : BDI_async_congested; |
0e093d99 MG |
751 | if (test_and_clear_bit(bit, &bdi->state)) |
752 | atomic_dec(&nr_bdi_congested[sync]); | |
3fcfab16 AM |
753 | smp_mb__after_clear_bit(); |
754 | if (waitqueue_active(wqh)) | |
755 | wake_up(wqh); | |
756 | } | |
757 | EXPORT_SYMBOL(clear_bdi_congested); | |
758 | ||
1faa16d2 | 759 | void set_bdi_congested(struct backing_dev_info *bdi, int sync) |
3fcfab16 AM |
760 | { |
761 | enum bdi_state bit; | |
762 | ||
1faa16d2 | 763 | bit = sync ? BDI_sync_congested : BDI_async_congested; |
0e093d99 MG |
764 | if (!test_and_set_bit(bit, &bdi->state)) |
765 | atomic_inc(&nr_bdi_congested[sync]); | |
3fcfab16 AM |
766 | } |
767 | EXPORT_SYMBOL(set_bdi_congested); | |
768 | ||
769 | /** | |
770 | * congestion_wait - wait for a backing_dev to become uncongested | |
8aa7e847 | 771 | * @sync: SYNC or ASYNC IO |
3fcfab16 AM |
772 | * @timeout: timeout in jiffies |
773 | * | |
774 | * Waits for up to @timeout jiffies for a backing_dev (any backing_dev) to exit | |
775 | * write congestion. If no backing_devs are congested then just wait for the | |
776 | * next write to be completed. | |
777 | */ | |
8aa7e847 | 778 | long congestion_wait(int sync, long timeout) |
3fcfab16 AM |
779 | { |
780 | long ret; | |
52bb9198 | 781 | unsigned long start = jiffies; |
3fcfab16 | 782 | DEFINE_WAIT(wait); |
8aa7e847 | 783 | wait_queue_head_t *wqh = &congestion_wqh[sync]; |
3fcfab16 AM |
784 | |
785 | prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); | |
786 | ret = io_schedule_timeout(timeout); | |
787 | finish_wait(wqh, &wait); | |
52bb9198 MG |
788 | |
789 | trace_writeback_congestion_wait(jiffies_to_usecs(timeout), | |
790 | jiffies_to_usecs(jiffies - start)); | |
791 | ||
3fcfab16 AM |
792 | return ret; |
793 | } | |
794 | EXPORT_SYMBOL(congestion_wait); | |
04fbfdc1 | 795 | |
0e093d99 MG |
796 | /** |
797 | * wait_iff_congested - Conditionally wait for a backing_dev to become uncongested or a zone to complete writes | |
798 | * @zone: A zone to check if it is heavily congested | |
799 | * @sync: SYNC or ASYNC IO | |
800 | * @timeout: timeout in jiffies | |
801 | * | |
802 | * In the event of a congested backing_dev (any backing_dev) and the given | |
803 | * @zone has experienced recent congestion, this waits for up to @timeout | |
804 | * jiffies for either a BDI to exit congestion of the given @sync queue | |
805 | * or a write to complete. | |
806 | * | |
25985edc | 807 | * In the absence of zone congestion, cond_resched() is called to yield |
0e093d99 MG |
808 | * the processor if necessary but otherwise does not sleep. |
809 | * | |
810 | * The return value is 0 if the sleep is for the full timeout. Otherwise, | |
811 | * it is the number of jiffies that were still remaining when the function | |
812 | * returned. return_value == timeout implies the function did not sleep. | |
813 | */ | |
814 | long wait_iff_congested(struct zone *zone, int sync, long timeout) | |
815 | { | |
816 | long ret; | |
817 | unsigned long start = jiffies; | |
818 | DEFINE_WAIT(wait); | |
819 | wait_queue_head_t *wqh = &congestion_wqh[sync]; | |
820 | ||
821 | /* | |
822 | * If there is no congestion, or heavy congestion is not being | |
823 | * encountered in the current zone, yield if necessary instead | |
824 | * of sleeping on the congestion queue | |
825 | */ | |
826 | if (atomic_read(&nr_bdi_congested[sync]) == 0 || | |
827 | !zone_is_reclaim_congested(zone)) { | |
828 | cond_resched(); | |
829 | ||
830 | /* In case we scheduled, work out time remaining */ | |
831 | ret = timeout - (jiffies - start); | |
832 | if (ret < 0) | |
833 | ret = 0; | |
834 | ||
835 | goto out; | |
836 | } | |
837 | ||
838 | /* Sleep until uncongested or a write happens */ | |
839 | prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); | |
840 | ret = io_schedule_timeout(timeout); | |
841 | finish_wait(wqh, &wait); | |
842 | ||
843 | out: | |
844 | trace_writeback_wait_iff_congested(jiffies_to_usecs(timeout), | |
845 | jiffies_to_usecs(jiffies - start)); | |
846 | ||
847 | return ret; | |
848 | } | |
849 | EXPORT_SYMBOL(wait_iff_congested); | |
3965c9ae WL |
850 | |
851 | int pdflush_proc_obsolete(struct ctl_table *table, int write, | |
852 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
853 | { | |
854 | char kbuf[] = "0\n"; | |
855 | ||
856 | if (*ppos) { | |
857 | *lenp = 0; | |
858 | return 0; | |
859 | } | |
860 | ||
861 | if (copy_to_user(buffer, kbuf, sizeof(kbuf))) | |
862 | return -EFAULT; | |
863 | printk_once(KERN_WARNING "%s exported in /proc is scheduled for removal\n", | |
864 | table->procname); | |
865 | ||
866 | *lenp = 2; | |
867 | *ppos += *lenp; | |
868 | return 2; | |
869 | } |