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 | ||
42 | static struct task_struct *sync_supers_tsk; | |
43 | static struct timer_list sync_supers_timer; | |
44 | ||
45 | static int bdi_sync_supers(void *); | |
46 | static void sync_supers_timer_fn(unsigned long); | |
03ba3782 | 47 | |
76f1418b MS |
48 | #ifdef CONFIG_DEBUG_FS |
49 | #include <linux/debugfs.h> | |
50 | #include <linux/seq_file.h> | |
51 | ||
52 | static struct dentry *bdi_debug_root; | |
53 | ||
54 | static void bdi_debug_init(void) | |
55 | { | |
56 | bdi_debug_root = debugfs_create_dir("bdi", NULL); | |
57 | } | |
58 | ||
59 | static int bdi_debug_stats_show(struct seq_file *m, void *v) | |
60 | { | |
61 | struct backing_dev_info *bdi = m->private; | |
c1955ce3 | 62 | struct bdi_writeback *wb = &bdi->wb; |
364aeb28 DR |
63 | unsigned long background_thresh; |
64 | unsigned long dirty_thresh; | |
65 | unsigned long bdi_thresh; | |
345227d7 | 66 | unsigned long nr_dirty, nr_io, nr_more_io; |
f09b00d3 JA |
67 | struct inode *inode; |
68 | ||
345227d7 | 69 | nr_dirty = nr_io = nr_more_io = 0; |
a66979ab | 70 | spin_lock(&inode_wb_list_lock); |
7ccf19a8 | 71 | list_for_each_entry(inode, &wb->b_dirty, i_wb_list) |
c1955ce3 | 72 | nr_dirty++; |
7ccf19a8 | 73 | list_for_each_entry(inode, &wb->b_io, i_wb_list) |
c1955ce3 | 74 | nr_io++; |
7ccf19a8 | 75 | list_for_each_entry(inode, &wb->b_more_io, i_wb_list) |
c1955ce3 | 76 | nr_more_io++; |
a66979ab | 77 | spin_unlock(&inode_wb_list_lock); |
76f1418b | 78 | |
16c4042f WF |
79 | global_dirty_limits(&background_thresh, &dirty_thresh); |
80 | bdi_thresh = bdi_dirty_limit(bdi, dirty_thresh); | |
76f1418b MS |
81 | |
82 | #define K(x) ((x) << (PAGE_SHIFT - 10)) | |
83 | seq_printf(m, | |
84 | "BdiWriteback: %8lu kB\n" | |
85 | "BdiReclaimable: %8lu kB\n" | |
86 | "BdiDirtyThresh: %8lu kB\n" | |
87 | "DirtyThresh: %8lu kB\n" | |
f09b00d3 | 88 | "BackgroundThresh: %8lu kB\n" |
f09b00d3 JA |
89 | "b_dirty: %8lu\n" |
90 | "b_io: %8lu\n" | |
91 | "b_more_io: %8lu\n" | |
92 | "bdi_list: %8u\n" | |
c1955ce3 | 93 | "state: %8lx\n", |
76f1418b MS |
94 | (unsigned long) K(bdi_stat(bdi, BDI_WRITEBACK)), |
95 | (unsigned long) K(bdi_stat(bdi, BDI_RECLAIMABLE)), | |
f09b00d3 | 96 | K(bdi_thresh), K(dirty_thresh), |
c1955ce3 CH |
97 | K(background_thresh), nr_dirty, nr_io, nr_more_io, |
98 | !list_empty(&bdi->bdi_list), bdi->state); | |
76f1418b MS |
99 | #undef K |
100 | ||
101 | return 0; | |
102 | } | |
103 | ||
104 | static int bdi_debug_stats_open(struct inode *inode, struct file *file) | |
105 | { | |
106 | return single_open(file, bdi_debug_stats_show, inode->i_private); | |
107 | } | |
108 | ||
109 | static const struct file_operations bdi_debug_stats_fops = { | |
110 | .open = bdi_debug_stats_open, | |
111 | .read = seq_read, | |
112 | .llseek = seq_lseek, | |
113 | .release = single_release, | |
114 | }; | |
115 | ||
116 | static void bdi_debug_register(struct backing_dev_info *bdi, const char *name) | |
117 | { | |
118 | bdi->debug_dir = debugfs_create_dir(name, bdi_debug_root); | |
119 | bdi->debug_stats = debugfs_create_file("stats", 0444, bdi->debug_dir, | |
120 | bdi, &bdi_debug_stats_fops); | |
121 | } | |
122 | ||
123 | static void bdi_debug_unregister(struct backing_dev_info *bdi) | |
124 | { | |
125 | debugfs_remove(bdi->debug_stats); | |
126 | debugfs_remove(bdi->debug_dir); | |
127 | } | |
128 | #else | |
129 | static inline void bdi_debug_init(void) | |
130 | { | |
131 | } | |
132 | static inline void bdi_debug_register(struct backing_dev_info *bdi, | |
133 | const char *name) | |
134 | { | |
135 | } | |
136 | static inline void bdi_debug_unregister(struct backing_dev_info *bdi) | |
137 | { | |
138 | } | |
139 | #endif | |
140 | ||
cf0ca9fe PZ |
141 | static ssize_t read_ahead_kb_store(struct device *dev, |
142 | struct device_attribute *attr, | |
143 | const char *buf, size_t count) | |
144 | { | |
145 | struct backing_dev_info *bdi = dev_get_drvdata(dev); | |
146 | char *end; | |
147 | unsigned long read_ahead_kb; | |
148 | ssize_t ret = -EINVAL; | |
149 | ||
150 | read_ahead_kb = simple_strtoul(buf, &end, 10); | |
151 | if (*buf && (end[0] == '\0' || (end[0] == '\n' && end[1] == '\0'))) { | |
152 | bdi->ra_pages = read_ahead_kb >> (PAGE_SHIFT - 10); | |
153 | ret = count; | |
154 | } | |
155 | return ret; | |
156 | } | |
157 | ||
158 | #define K(pages) ((pages) << (PAGE_SHIFT - 10)) | |
159 | ||
160 | #define BDI_SHOW(name, expr) \ | |
161 | static ssize_t name##_show(struct device *dev, \ | |
162 | struct device_attribute *attr, char *page) \ | |
163 | { \ | |
164 | struct backing_dev_info *bdi = dev_get_drvdata(dev); \ | |
165 | \ | |
166 | return snprintf(page, PAGE_SIZE-1, "%lld\n", (long long)expr); \ | |
167 | } | |
168 | ||
169 | BDI_SHOW(read_ahead_kb, K(bdi->ra_pages)) | |
170 | ||
189d3c4a PZ |
171 | static ssize_t min_ratio_store(struct device *dev, |
172 | struct device_attribute *attr, const char *buf, size_t count) | |
173 | { | |
174 | struct backing_dev_info *bdi = dev_get_drvdata(dev); | |
175 | char *end; | |
176 | unsigned int ratio; | |
177 | ssize_t ret = -EINVAL; | |
178 | ||
179 | ratio = simple_strtoul(buf, &end, 10); | |
180 | if (*buf && (end[0] == '\0' || (end[0] == '\n' && end[1] == '\0'))) { | |
181 | ret = bdi_set_min_ratio(bdi, ratio); | |
182 | if (!ret) | |
183 | ret = count; | |
184 | } | |
185 | return ret; | |
186 | } | |
187 | BDI_SHOW(min_ratio, bdi->min_ratio) | |
188 | ||
a42dde04 PZ |
189 | static ssize_t max_ratio_store(struct device *dev, |
190 | struct device_attribute *attr, const char *buf, size_t count) | |
191 | { | |
192 | struct backing_dev_info *bdi = dev_get_drvdata(dev); | |
193 | char *end; | |
194 | unsigned int ratio; | |
195 | ssize_t ret = -EINVAL; | |
196 | ||
197 | ratio = simple_strtoul(buf, &end, 10); | |
198 | if (*buf && (end[0] == '\0' || (end[0] == '\n' && end[1] == '\0'))) { | |
199 | ret = bdi_set_max_ratio(bdi, ratio); | |
200 | if (!ret) | |
201 | ret = count; | |
202 | } | |
203 | return ret; | |
204 | } | |
205 | BDI_SHOW(max_ratio, bdi->max_ratio) | |
206 | ||
cf0ca9fe PZ |
207 | #define __ATTR_RW(attr) __ATTR(attr, 0644, attr##_show, attr##_store) |
208 | ||
209 | static struct device_attribute bdi_dev_attrs[] = { | |
210 | __ATTR_RW(read_ahead_kb), | |
189d3c4a | 211 | __ATTR_RW(min_ratio), |
a42dde04 | 212 | __ATTR_RW(max_ratio), |
cf0ca9fe PZ |
213 | __ATTR_NULL, |
214 | }; | |
215 | ||
216 | static __init int bdi_class_init(void) | |
217 | { | |
218 | bdi_class = class_create(THIS_MODULE, "bdi"); | |
14421453 AB |
219 | if (IS_ERR(bdi_class)) |
220 | return PTR_ERR(bdi_class); | |
221 | ||
cf0ca9fe | 222 | bdi_class->dev_attrs = bdi_dev_attrs; |
76f1418b | 223 | bdi_debug_init(); |
cf0ca9fe PZ |
224 | return 0; |
225 | } | |
76f1418b | 226 | postcore_initcall(bdi_class_init); |
cf0ca9fe | 227 | |
26160158 JA |
228 | static int __init default_bdi_init(void) |
229 | { | |
230 | int err; | |
231 | ||
03ba3782 JA |
232 | sync_supers_tsk = kthread_run(bdi_sync_supers, NULL, "sync_supers"); |
233 | BUG_ON(IS_ERR(sync_supers_tsk)); | |
234 | ||
03ba3782 | 235 | setup_timer(&sync_supers_timer, sync_supers_timer_fn, 0); |
6423104b | 236 | bdi_arm_supers_timer(); |
03ba3782 | 237 | |
26160158 JA |
238 | err = bdi_init(&default_backing_dev_info); |
239 | if (!err) | |
240 | bdi_register(&default_backing_dev_info, NULL, "default"); | |
976e48f8 | 241 | err = bdi_init(&noop_backing_dev_info); |
26160158 JA |
242 | |
243 | return err; | |
244 | } | |
245 | subsys_initcall(default_bdi_init); | |
246 | ||
03ba3782 JA |
247 | int bdi_has_dirty_io(struct backing_dev_info *bdi) |
248 | { | |
249 | return wb_has_dirty_io(&bdi->wb); | |
250 | } | |
251 | ||
252 | static void bdi_flush_io(struct backing_dev_info *bdi) | |
253 | { | |
254 | struct writeback_control wbc = { | |
03ba3782 JA |
255 | .sync_mode = WB_SYNC_NONE, |
256 | .older_than_this = NULL, | |
257 | .range_cyclic = 1, | |
258 | .nr_to_write = 1024, | |
259 | }; | |
260 | ||
9c3a8ee8 | 261 | writeback_inodes_wb(&bdi->wb, &wbc); |
03ba3782 JA |
262 | } |
263 | ||
264 | /* | |
6f904ff0 | 265 | * kupdated() used to do this. We cannot do it from the bdi_forker_thread() |
03ba3782 JA |
266 | * or we risk deadlocking on ->s_umount. The longer term solution would be |
267 | * to implement sync_supers_bdi() or similar and simply do it from the | |
6f904ff0 | 268 | * bdi writeback thread individually. |
03ba3782 JA |
269 | */ |
270 | static int bdi_sync_supers(void *unused) | |
271 | { | |
272 | set_user_nice(current, 0); | |
273 | ||
274 | while (!kthread_should_stop()) { | |
275 | set_current_state(TASK_INTERRUPTIBLE); | |
276 | schedule(); | |
277 | ||
278 | /* | |
279 | * Do this periodically, like kupdated() did before. | |
280 | */ | |
281 | sync_supers(); | |
282 | } | |
283 | ||
284 | return 0; | |
285 | } | |
286 | ||
6423104b | 287 | void bdi_arm_supers_timer(void) |
03ba3782 JA |
288 | { |
289 | unsigned long next; | |
290 | ||
6423104b JA |
291 | if (!dirty_writeback_interval) |
292 | return; | |
293 | ||
03ba3782 JA |
294 | next = msecs_to_jiffies(dirty_writeback_interval * 10) + jiffies; |
295 | mod_timer(&sync_supers_timer, round_jiffies_up(next)); | |
296 | } | |
297 | ||
298 | static void sync_supers_timer_fn(unsigned long unused) | |
299 | { | |
300 | wake_up_process(sync_supers_tsk); | |
6423104b | 301 | bdi_arm_supers_timer(); |
03ba3782 JA |
302 | } |
303 | ||
6467716a AB |
304 | static void wakeup_timer_fn(unsigned long data) |
305 | { | |
306 | struct backing_dev_info *bdi = (struct backing_dev_info *)data; | |
307 | ||
308 | spin_lock_bh(&bdi->wb_lock); | |
309 | if (bdi->wb.task) { | |
60332023 | 310 | trace_writeback_wake_thread(bdi); |
6467716a AB |
311 | wake_up_process(bdi->wb.task); |
312 | } else { | |
313 | /* | |
314 | * When bdi tasks are inactive for long time, they are killed. | |
315 | * In this case we have to wake-up the forker thread which | |
316 | * should create and run the bdi thread. | |
317 | */ | |
60332023 | 318 | trace_writeback_wake_forker_thread(bdi); |
6467716a AB |
319 | wake_up_process(default_backing_dev_info.wb.task); |
320 | } | |
321 | spin_unlock_bh(&bdi->wb_lock); | |
322 | } | |
323 | ||
324 | /* | |
325 | * This function is used when the first inode for this bdi is marked dirty. It | |
326 | * wakes-up the corresponding bdi thread which should then take care of the | |
327 | * periodic background write-out of dirty inodes. Since the write-out would | |
328 | * starts only 'dirty_writeback_interval' centisecs from now anyway, we just | |
329 | * set up a timer which wakes the bdi thread up later. | |
330 | * | |
331 | * Note, we wouldn't bother setting up the timer, but this function is on the | |
332 | * fast-path (used by '__mark_inode_dirty()'), so we save few context switches | |
333 | * by delaying the wake-up. | |
334 | */ | |
335 | void bdi_wakeup_thread_delayed(struct backing_dev_info *bdi) | |
336 | { | |
337 | unsigned long timeout; | |
338 | ||
339 | timeout = msecs_to_jiffies(dirty_writeback_interval * 10); | |
340 | mod_timer(&bdi->wb.wakeup_timer, jiffies + timeout); | |
341 | } | |
342 | ||
fff5b85a AB |
343 | /* |
344 | * Calculate the longest interval (jiffies) bdi threads are allowed to be | |
345 | * inactive. | |
346 | */ | |
347 | static unsigned long bdi_longest_inactive(void) | |
348 | { | |
349 | unsigned long interval; | |
350 | ||
351 | interval = msecs_to_jiffies(dirty_writeback_interval * 10); | |
352 | return max(5UL * 60 * HZ, interval); | |
353 | } | |
354 | ||
6f904ff0 | 355 | static int bdi_forker_thread(void *ptr) |
03ba3782 JA |
356 | { |
357 | struct bdi_writeback *me = ptr; | |
358 | ||
766f9164 | 359 | current->flags |= PF_SWAPWRITE; |
c1955ce3 CH |
360 | set_freezable(); |
361 | ||
362 | /* | |
363 | * Our parent may run at a different priority, just set us to normal | |
364 | */ | |
365 | set_user_nice(current, 0); | |
03ba3782 JA |
366 | |
367 | for (;;) { | |
fff5b85a | 368 | struct task_struct *task = NULL; |
78c40cb6 | 369 | struct backing_dev_info *bdi; |
adf39240 AB |
370 | enum { |
371 | NO_ACTION, /* Nothing to do */ | |
372 | FORK_THREAD, /* Fork bdi thread */ | |
fff5b85a | 373 | KILL_THREAD, /* Kill inactive bdi thread */ |
adf39240 | 374 | } action = NO_ACTION; |
03ba3782 JA |
375 | |
376 | /* | |
377 | * Temporary measure, we want to make sure we don't see | |
378 | * dirty data on the default backing_dev_info | |
379 | */ | |
6467716a AB |
380 | if (wb_has_dirty_io(me) || !list_empty(&me->bdi->work_list)) { |
381 | del_timer(&me->wakeup_timer); | |
03ba3782 | 382 | wb_do_writeback(me, 0); |
6467716a | 383 | } |
03ba3782 | 384 | |
cfc4ba53 | 385 | spin_lock_bh(&bdi_lock); |
c5f7ad23 | 386 | set_current_state(TASK_INTERRUPTIBLE); |
03ba3782 | 387 | |
78c40cb6 | 388 | list_for_each_entry(bdi, &bdi_list, bdi_list) { |
adf39240 AB |
389 | bool have_dirty_io; |
390 | ||
391 | if (!bdi_cap_writeback_dirty(bdi) || | |
392 | bdi_cap_flush_forker(bdi)) | |
03ba3782 JA |
393 | continue; |
394 | ||
080dcec4 AB |
395 | WARN(!test_bit(BDI_registered, &bdi->state), |
396 | "bdi %p/%s is not registered!\n", bdi, bdi->name); | |
397 | ||
adf39240 AB |
398 | have_dirty_io = !list_empty(&bdi->work_list) || |
399 | wb_has_dirty_io(&bdi->wb); | |
78c40cb6 AB |
400 | |
401 | /* | |
adf39240 AB |
402 | * If the bdi has work to do, but the thread does not |
403 | * exist - create it. | |
78c40cb6 | 404 | */ |
adf39240 AB |
405 | if (!bdi->wb.task && have_dirty_io) { |
406 | /* | |
407 | * Set the pending bit - if someone will try to | |
408 | * unregister this bdi - it'll wait on this bit. | |
409 | */ | |
410 | set_bit(BDI_pending, &bdi->state); | |
411 | action = FORK_THREAD; | |
412 | break; | |
413 | } | |
fff5b85a | 414 | |
6bf05d03 JA |
415 | spin_lock(&bdi->wb_lock); |
416 | ||
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 | } | |
6bf05d03 | 433 | spin_unlock(&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); | |
6628bc74 AB |
444 | task = kthread_create(bdi_writeback_thread, &bdi->wb, |
445 | "flush-%s", dev_name(bdi->dev)); | |
adf39240 AB |
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()'. | |
6628bc74 AB |
456 | * And as soon as the bdi thread is visible, we |
457 | * can start it. | |
fff5b85a | 458 | */ |
6467716a | 459 | spin_lock_bh(&bdi->wb_lock); |
adf39240 | 460 | bdi->wb.task = task; |
6467716a | 461 | spin_unlock_bh(&bdi->wb_lock); |
6628bc74 | 462 | wake_up_process(task); |
fff5b85a AB |
463 | } |
464 | break; | |
465 | ||
466 | case KILL_THREAD: | |
467 | __set_current_state(TASK_RUNNING); | |
468 | kthread_stop(task); | |
adf39240 | 469 | break; |
03ba3782 | 470 | |
adf39240 | 471 | case NO_ACTION: |
253c34e9 AB |
472 | if (!wb_has_dirty_io(me) || !dirty_writeback_interval) |
473 | /* | |
474 | * There are no dirty data. The only thing we | |
475 | * should now care about is checking for | |
476 | * inactive bdi threads and killing them. Thus, | |
477 | * let's sleep for longer time, save energy and | |
478 | * be friendly for battery-driven devices. | |
479 | */ | |
480 | schedule_timeout(bdi_longest_inactive()); | |
6423104b | 481 | else |
253c34e9 | 482 | schedule_timeout(msecs_to_jiffies(dirty_writeback_interval * 10)); |
03ba3782 | 483 | try_to_freeze(); |
adf39240 | 484 | /* Back to the main loop */ |
03ba3782 JA |
485 | continue; |
486 | } | |
fff5b85a AB |
487 | |
488 | /* | |
489 | * Clear pending bit and wakeup anybody waiting to tear us down. | |
490 | */ | |
491 | clear_bit(BDI_pending, &bdi->state); | |
492 | smp_mb__after_clear_bit(); | |
493 | wake_up_bit(&bdi->state, BDI_pending); | |
03ba3782 JA |
494 | } |
495 | ||
496 | return 0; | |
497 | } | |
498 | ||
cfc4ba53 JA |
499 | /* |
500 | * Remove bdi from bdi_list, and ensure that it is no longer visible | |
501 | */ | |
502 | static void bdi_remove_from_list(struct backing_dev_info *bdi) | |
503 | { | |
504 | spin_lock_bh(&bdi_lock); | |
505 | list_del_rcu(&bdi->bdi_list); | |
506 | spin_unlock_bh(&bdi_lock); | |
507 | ||
508 | synchronize_rcu(); | |
509 | } | |
510 | ||
cf0ca9fe PZ |
511 | int bdi_register(struct backing_dev_info *bdi, struct device *parent, |
512 | const char *fmt, ...) | |
513 | { | |
cf0ca9fe | 514 | va_list args; |
cf0ca9fe PZ |
515 | struct device *dev; |
516 | ||
69fc208b | 517 | if (bdi->dev) /* The driver needs to use separate queues per device */ |
c284de61 | 518 | return 0; |
f1d0b063 | 519 | |
cf0ca9fe | 520 | va_start(args, fmt); |
19051c50 | 521 | dev = device_create_vargs(bdi_class, parent, MKDEV(0, 0), bdi, fmt, args); |
cf0ca9fe | 522 | va_end(args); |
c284de61 AB |
523 | if (IS_ERR(dev)) |
524 | return PTR_ERR(dev); | |
66f3b8e2 | 525 | |
cf0ca9fe | 526 | bdi->dev = dev; |
cf0ca9fe | 527 | |
03ba3782 JA |
528 | /* |
529 | * Just start the forker thread for our default backing_dev_info, | |
530 | * and add other bdi's to the list. They will get a thread created | |
531 | * on-demand when they need it. | |
532 | */ | |
533 | if (bdi_cap_flush_forker(bdi)) { | |
534 | struct bdi_writeback *wb = &bdi->wb; | |
535 | ||
6f904ff0 | 536 | wb->task = kthread_run(bdi_forker_thread, wb, "bdi-%s", |
03ba3782 | 537 | dev_name(dev)); |
c284de61 AB |
538 | if (IS_ERR(wb->task)) |
539 | return PTR_ERR(wb->task); | |
03ba3782 JA |
540 | } |
541 | ||
542 | bdi_debug_register(bdi, dev_name(dev)); | |
500b067c | 543 | set_bit(BDI_registered, &bdi->state); |
c284de61 AB |
544 | |
545 | spin_lock_bh(&bdi_lock); | |
546 | list_add_tail_rcu(&bdi->bdi_list, &bdi_list); | |
547 | spin_unlock_bh(&bdi_lock); | |
548 | ||
455b2864 | 549 | trace_writeback_bdi_register(bdi); |
c284de61 | 550 | return 0; |
cf0ca9fe PZ |
551 | } |
552 | EXPORT_SYMBOL(bdi_register); | |
553 | ||
554 | int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev) | |
555 | { | |
556 | return bdi_register(bdi, NULL, "%u:%u", MAJOR(dev), MINOR(dev)); | |
557 | } | |
558 | EXPORT_SYMBOL(bdi_register_dev); | |
559 | ||
03ba3782 JA |
560 | /* |
561 | * Remove bdi from the global list and shutdown any threads we have running | |
562 | */ | |
563 | static void bdi_wb_shutdown(struct backing_dev_info *bdi) | |
66f3b8e2 | 564 | { |
03ba3782 JA |
565 | if (!bdi_cap_writeback_dirty(bdi)) |
566 | return; | |
567 | ||
568 | /* | |
fff5b85a | 569 | * Make sure nobody finds us on the bdi_list anymore |
03ba3782 | 570 | */ |
fff5b85a | 571 | bdi_remove_from_list(bdi); |
03ba3782 JA |
572 | |
573 | /* | |
fff5b85a | 574 | * If setup is pending, wait for that to complete first |
03ba3782 | 575 | */ |
fff5b85a AB |
576 | wait_on_bit(&bdi->state, BDI_pending, bdi_sched_wait, |
577 | TASK_UNINTERRUPTIBLE); | |
03ba3782 JA |
578 | |
579 | /* | |
c1955ce3 | 580 | * Finally, kill the kernel thread. We don't need to be RCU |
c62b17a5 RD |
581 | * safe anymore, since the bdi is gone from visibility. Force |
582 | * unfreeze of the thread before calling kthread_stop(), otherwise | |
583 | * it would never exet if it is currently stuck in the refrigerator. | |
03ba3782 | 584 | */ |
c1955ce3 CH |
585 | if (bdi->wb.task) { |
586 | thaw_process(bdi->wb.task); | |
587 | kthread_stop(bdi->wb.task); | |
c62b17a5 | 588 | } |
66f3b8e2 JA |
589 | } |
590 | ||
592b09a4 JA |
591 | /* |
592 | * This bdi is going away now, make sure that no super_blocks point to it | |
593 | */ | |
594 | static void bdi_prune_sb(struct backing_dev_info *bdi) | |
595 | { | |
596 | struct super_block *sb; | |
597 | ||
598 | spin_lock(&sb_lock); | |
599 | list_for_each_entry(sb, &super_blocks, s_list) { | |
600 | if (sb->s_bdi == bdi) | |
95f28604 | 601 | sb->s_bdi = &default_backing_dev_info; |
592b09a4 JA |
602 | } |
603 | spin_unlock(&sb_lock); | |
604 | } | |
605 | ||
cf0ca9fe PZ |
606 | void bdi_unregister(struct backing_dev_info *bdi) |
607 | { | |
608 | if (bdi->dev) { | |
455b2864 | 609 | trace_writeback_bdi_unregister(bdi); |
8c4db335 | 610 | bdi_prune_sb(bdi); |
6467716a | 611 | del_timer_sync(&bdi->wb.wakeup_timer); |
8c4db335 | 612 | |
03ba3782 JA |
613 | if (!bdi_cap_flush_forker(bdi)) |
614 | bdi_wb_shutdown(bdi); | |
76f1418b | 615 | bdi_debug_unregister(bdi); |
cf0ca9fe PZ |
616 | device_unregister(bdi->dev); |
617 | bdi->dev = NULL; | |
618 | } | |
619 | } | |
620 | EXPORT_SYMBOL(bdi_unregister); | |
3fcfab16 | 621 | |
6467716a AB |
622 | static void bdi_wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi) |
623 | { | |
624 | memset(wb, 0, sizeof(*wb)); | |
625 | ||
626 | wb->bdi = bdi; | |
627 | wb->last_old_flush = jiffies; | |
628 | INIT_LIST_HEAD(&wb->b_dirty); | |
629 | INIT_LIST_HEAD(&wb->b_io); | |
630 | INIT_LIST_HEAD(&wb->b_more_io); | |
631 | setup_timer(&wb->wakeup_timer, wakeup_timer_fn, (unsigned long)bdi); | |
632 | } | |
633 | ||
b2e8fb6e PZ |
634 | int bdi_init(struct backing_dev_info *bdi) |
635 | { | |
03ba3782 | 636 | int i, err; |
b2e8fb6e | 637 | |
cf0ca9fe PZ |
638 | bdi->dev = NULL; |
639 | ||
189d3c4a | 640 | bdi->min_ratio = 0; |
a42dde04 PZ |
641 | bdi->max_ratio = 100; |
642 | bdi->max_prop_frac = PROP_FRAC_BASE; | |
03ba3782 | 643 | spin_lock_init(&bdi->wb_lock); |
66f3b8e2 | 644 | INIT_LIST_HEAD(&bdi->bdi_list); |
03ba3782 JA |
645 | INIT_LIST_HEAD(&bdi->work_list); |
646 | ||
647 | bdi_wb_init(&bdi->wb, bdi); | |
648 | ||
b2e8fb6e | 649 | for (i = 0; i < NR_BDI_STAT_ITEMS; i++) { |
ea319518 | 650 | err = percpu_counter_init(&bdi->bdi_stat[i], 0); |
04fbfdc1 PZ |
651 | if (err) |
652 | goto err; | |
653 | } | |
654 | ||
655 | bdi->dirty_exceeded = 0; | |
656 | err = prop_local_init_percpu(&bdi->completions); | |
657 | ||
658 | if (err) { | |
659 | err: | |
4b01a0b1 | 660 | while (i--) |
04fbfdc1 | 661 | percpu_counter_destroy(&bdi->bdi_stat[i]); |
b2e8fb6e PZ |
662 | } |
663 | ||
664 | return err; | |
665 | } | |
666 | EXPORT_SYMBOL(bdi_init); | |
667 | ||
668 | void bdi_destroy(struct backing_dev_info *bdi) | |
669 | { | |
670 | int i; | |
671 | ||
ce5f8e77 JA |
672 | /* |
673 | * Splice our entries to the default_backing_dev_info, if this | |
674 | * bdi disappears | |
675 | */ | |
676 | if (bdi_has_dirty_io(bdi)) { | |
677 | struct bdi_writeback *dst = &default_backing_dev_info.wb; | |
678 | ||
a66979ab | 679 | spin_lock(&inode_wb_list_lock); |
ce5f8e77 JA |
680 | list_splice(&bdi->wb.b_dirty, &dst->b_dirty); |
681 | list_splice(&bdi->wb.b_io, &dst->b_io); | |
682 | list_splice(&bdi->wb.b_more_io, &dst->b_more_io); | |
a66979ab | 683 | spin_unlock(&inode_wb_list_lock); |
ce5f8e77 | 684 | } |
66f3b8e2 | 685 | |
cf0ca9fe PZ |
686 | bdi_unregister(bdi); |
687 | ||
b2e8fb6e PZ |
688 | for (i = 0; i < NR_BDI_STAT_ITEMS; i++) |
689 | percpu_counter_destroy(&bdi->bdi_stat[i]); | |
04fbfdc1 PZ |
690 | |
691 | prop_local_destroy_percpu(&bdi->completions); | |
b2e8fb6e PZ |
692 | } |
693 | EXPORT_SYMBOL(bdi_destroy); | |
694 | ||
c3c53206 JA |
695 | /* |
696 | * For use from filesystems to quickly init and register a bdi associated | |
697 | * with dirty writeback | |
698 | */ | |
699 | int bdi_setup_and_register(struct backing_dev_info *bdi, char *name, | |
700 | unsigned int cap) | |
701 | { | |
702 | char tmp[32]; | |
703 | int err; | |
704 | ||
705 | bdi->name = name; | |
706 | bdi->capabilities = cap; | |
707 | err = bdi_init(bdi); | |
708 | if (err) | |
709 | return err; | |
710 | ||
711 | sprintf(tmp, "%.28s%s", name, "-%d"); | |
712 | err = bdi_register(bdi, NULL, tmp, atomic_long_inc_return(&bdi_seq)); | |
713 | if (err) { | |
714 | bdi_destroy(bdi); | |
715 | return err; | |
716 | } | |
717 | ||
718 | return 0; | |
719 | } | |
720 | EXPORT_SYMBOL(bdi_setup_and_register); | |
721 | ||
3fcfab16 AM |
722 | static wait_queue_head_t congestion_wqh[2] = { |
723 | __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]), | |
724 | __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1]) | |
725 | }; | |
0e093d99 | 726 | static atomic_t nr_bdi_congested[2]; |
3fcfab16 | 727 | |
1faa16d2 | 728 | void clear_bdi_congested(struct backing_dev_info *bdi, int sync) |
3fcfab16 AM |
729 | { |
730 | enum bdi_state bit; | |
1faa16d2 | 731 | wait_queue_head_t *wqh = &congestion_wqh[sync]; |
3fcfab16 | 732 | |
1faa16d2 | 733 | bit = sync ? BDI_sync_congested : BDI_async_congested; |
0e093d99 MG |
734 | if (test_and_clear_bit(bit, &bdi->state)) |
735 | atomic_dec(&nr_bdi_congested[sync]); | |
3fcfab16 AM |
736 | smp_mb__after_clear_bit(); |
737 | if (waitqueue_active(wqh)) | |
738 | wake_up(wqh); | |
739 | } | |
740 | EXPORT_SYMBOL(clear_bdi_congested); | |
741 | ||
1faa16d2 | 742 | void set_bdi_congested(struct backing_dev_info *bdi, int sync) |
3fcfab16 AM |
743 | { |
744 | enum bdi_state bit; | |
745 | ||
1faa16d2 | 746 | bit = sync ? BDI_sync_congested : BDI_async_congested; |
0e093d99 MG |
747 | if (!test_and_set_bit(bit, &bdi->state)) |
748 | atomic_inc(&nr_bdi_congested[sync]); | |
3fcfab16 AM |
749 | } |
750 | EXPORT_SYMBOL(set_bdi_congested); | |
751 | ||
752 | /** | |
753 | * congestion_wait - wait for a backing_dev to become uncongested | |
8aa7e847 | 754 | * @sync: SYNC or ASYNC IO |
3fcfab16 AM |
755 | * @timeout: timeout in jiffies |
756 | * | |
757 | * Waits for up to @timeout jiffies for a backing_dev (any backing_dev) to exit | |
758 | * write congestion. If no backing_devs are congested then just wait for the | |
759 | * next write to be completed. | |
760 | */ | |
8aa7e847 | 761 | long congestion_wait(int sync, long timeout) |
3fcfab16 AM |
762 | { |
763 | long ret; | |
52bb9198 | 764 | unsigned long start = jiffies; |
3fcfab16 | 765 | DEFINE_WAIT(wait); |
8aa7e847 | 766 | wait_queue_head_t *wqh = &congestion_wqh[sync]; |
3fcfab16 AM |
767 | |
768 | prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); | |
769 | ret = io_schedule_timeout(timeout); | |
770 | finish_wait(wqh, &wait); | |
52bb9198 MG |
771 | |
772 | trace_writeback_congestion_wait(jiffies_to_usecs(timeout), | |
773 | jiffies_to_usecs(jiffies - start)); | |
774 | ||
3fcfab16 AM |
775 | return ret; |
776 | } | |
777 | EXPORT_SYMBOL(congestion_wait); | |
04fbfdc1 | 778 | |
0e093d99 MG |
779 | /** |
780 | * wait_iff_congested - Conditionally wait for a backing_dev to become uncongested or a zone to complete writes | |
781 | * @zone: A zone to check if it is heavily congested | |
782 | * @sync: SYNC or ASYNC IO | |
783 | * @timeout: timeout in jiffies | |
784 | * | |
785 | * In the event of a congested backing_dev (any backing_dev) and the given | |
786 | * @zone has experienced recent congestion, this waits for up to @timeout | |
787 | * jiffies for either a BDI to exit congestion of the given @sync queue | |
788 | * or a write to complete. | |
789 | * | |
25985edc | 790 | * In the absence of zone congestion, cond_resched() is called to yield |
0e093d99 MG |
791 | * the processor if necessary but otherwise does not sleep. |
792 | * | |
793 | * The return value is 0 if the sleep is for the full timeout. Otherwise, | |
794 | * it is the number of jiffies that were still remaining when the function | |
795 | * returned. return_value == timeout implies the function did not sleep. | |
796 | */ | |
797 | long wait_iff_congested(struct zone *zone, int sync, long timeout) | |
798 | { | |
799 | long ret; | |
800 | unsigned long start = jiffies; | |
801 | DEFINE_WAIT(wait); | |
802 | wait_queue_head_t *wqh = &congestion_wqh[sync]; | |
803 | ||
804 | /* | |
805 | * If there is no congestion, or heavy congestion is not being | |
806 | * encountered in the current zone, yield if necessary instead | |
807 | * of sleeping on the congestion queue | |
808 | */ | |
809 | if (atomic_read(&nr_bdi_congested[sync]) == 0 || | |
810 | !zone_is_reclaim_congested(zone)) { | |
811 | cond_resched(); | |
812 | ||
813 | /* In case we scheduled, work out time remaining */ | |
814 | ret = timeout - (jiffies - start); | |
815 | if (ret < 0) | |
816 | ret = 0; | |
817 | ||
818 | goto out; | |
819 | } | |
820 | ||
821 | /* Sleep until uncongested or a write happens */ | |
822 | prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); | |
823 | ret = io_schedule_timeout(timeout); | |
824 | finish_wait(wqh, &wait); | |
825 | ||
826 | out: | |
827 | trace_writeback_wait_iff_congested(jiffies_to_usecs(timeout), | |
828 | jiffies_to_usecs(jiffies - start)); | |
829 | ||
830 | return ret; | |
831 | } | |
832 | EXPORT_SYMBOL(wait_iff_congested); |