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> | |
13 | ||
26160158 JA |
14 | void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page) |
15 | { | |
16 | } | |
17 | EXPORT_SYMBOL(default_unplug_io_fn); | |
18 | ||
19 | struct backing_dev_info default_backing_dev_info = { | |
d993831f | 20 | .name = "default", |
26160158 JA |
21 | .ra_pages = VM_MAX_READAHEAD * 1024 / PAGE_CACHE_SIZE, |
22 | .state = 0, | |
23 | .capabilities = BDI_CAP_MAP_COPY, | |
24 | .unplug_io_fn = default_unplug_io_fn, | |
25 | }; | |
26 | EXPORT_SYMBOL_GPL(default_backing_dev_info); | |
cf0ca9fe PZ |
27 | |
28 | static struct class *bdi_class; | |
cfc4ba53 JA |
29 | |
30 | /* | |
31 | * bdi_lock protects updates to bdi_list and bdi_pending_list, as well as | |
32 | * reader side protection for bdi_pending_list. bdi_list has RCU reader side | |
33 | * locking. | |
34 | */ | |
03ba3782 | 35 | DEFINE_SPINLOCK(bdi_lock); |
66f3b8e2 | 36 | LIST_HEAD(bdi_list); |
03ba3782 JA |
37 | LIST_HEAD(bdi_pending_list); |
38 | ||
39 | static struct task_struct *sync_supers_tsk; | |
40 | static struct timer_list sync_supers_timer; | |
41 | ||
42 | static int bdi_sync_supers(void *); | |
43 | static void sync_supers_timer_fn(unsigned long); | |
44 | static void arm_supers_timer(void); | |
45 | ||
46 | static void bdi_add_default_flusher_task(struct backing_dev_info *bdi); | |
cf0ca9fe | 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; | |
f09b00d3 | 62 | struct bdi_writeback *wb; |
364aeb28 DR |
63 | unsigned long background_thresh; |
64 | unsigned long dirty_thresh; | |
65 | unsigned long bdi_thresh; | |
f09b00d3 JA |
66 | unsigned long nr_dirty, nr_io, nr_more_io, nr_wb; |
67 | struct inode *inode; | |
68 | ||
69 | /* | |
70 | * inode lock is enough here, the bdi->wb_list is protected by | |
71 | * RCU on the reader side | |
72 | */ | |
73 | nr_wb = nr_dirty = nr_io = nr_more_io = 0; | |
74 | spin_lock(&inode_lock); | |
75 | list_for_each_entry(wb, &bdi->wb_list, list) { | |
76 | nr_wb++; | |
77 | list_for_each_entry(inode, &wb->b_dirty, i_list) | |
78 | nr_dirty++; | |
79 | list_for_each_entry(inode, &wb->b_io, i_list) | |
80 | nr_io++; | |
81 | list_for_each_entry(inode, &wb->b_more_io, i_list) | |
82 | nr_more_io++; | |
83 | } | |
84 | spin_unlock(&inode_lock); | |
76f1418b MS |
85 | |
86 | get_dirty_limits(&background_thresh, &dirty_thresh, &bdi_thresh, bdi); | |
87 | ||
88 | #define K(x) ((x) << (PAGE_SHIFT - 10)) | |
89 | seq_printf(m, | |
90 | "BdiWriteback: %8lu kB\n" | |
91 | "BdiReclaimable: %8lu kB\n" | |
92 | "BdiDirtyThresh: %8lu kB\n" | |
93 | "DirtyThresh: %8lu kB\n" | |
f09b00d3 | 94 | "BackgroundThresh: %8lu kB\n" |
961515f6 | 95 | "WritebackThreads: %8lu\n" |
f09b00d3 JA |
96 | "b_dirty: %8lu\n" |
97 | "b_io: %8lu\n" | |
98 | "b_more_io: %8lu\n" | |
99 | "bdi_list: %8u\n" | |
100 | "state: %8lx\n" | |
101 | "wb_mask: %8lx\n" | |
102 | "wb_list: %8u\n" | |
103 | "wb_cnt: %8u\n", | |
76f1418b MS |
104 | (unsigned long) K(bdi_stat(bdi, BDI_WRITEBACK)), |
105 | (unsigned long) K(bdi_stat(bdi, BDI_RECLAIMABLE)), | |
f09b00d3 JA |
106 | K(bdi_thresh), K(dirty_thresh), |
107 | K(background_thresh), nr_wb, nr_dirty, nr_io, nr_more_io, | |
108 | !list_empty(&bdi->bdi_list), bdi->state, bdi->wb_mask, | |
109 | !list_empty(&bdi->wb_list), bdi->wb_cnt); | |
76f1418b MS |
110 | #undef K |
111 | ||
112 | return 0; | |
113 | } | |
114 | ||
115 | static int bdi_debug_stats_open(struct inode *inode, struct file *file) | |
116 | { | |
117 | return single_open(file, bdi_debug_stats_show, inode->i_private); | |
118 | } | |
119 | ||
120 | static const struct file_operations bdi_debug_stats_fops = { | |
121 | .open = bdi_debug_stats_open, | |
122 | .read = seq_read, | |
123 | .llseek = seq_lseek, | |
124 | .release = single_release, | |
125 | }; | |
126 | ||
127 | static void bdi_debug_register(struct backing_dev_info *bdi, const char *name) | |
128 | { | |
129 | bdi->debug_dir = debugfs_create_dir(name, bdi_debug_root); | |
130 | bdi->debug_stats = debugfs_create_file("stats", 0444, bdi->debug_dir, | |
131 | bdi, &bdi_debug_stats_fops); | |
132 | } | |
133 | ||
134 | static void bdi_debug_unregister(struct backing_dev_info *bdi) | |
135 | { | |
136 | debugfs_remove(bdi->debug_stats); | |
137 | debugfs_remove(bdi->debug_dir); | |
138 | } | |
139 | #else | |
140 | static inline void bdi_debug_init(void) | |
141 | { | |
142 | } | |
143 | static inline void bdi_debug_register(struct backing_dev_info *bdi, | |
144 | const char *name) | |
145 | { | |
146 | } | |
147 | static inline void bdi_debug_unregister(struct backing_dev_info *bdi) | |
148 | { | |
149 | } | |
150 | #endif | |
151 | ||
cf0ca9fe PZ |
152 | static ssize_t read_ahead_kb_store(struct device *dev, |
153 | struct device_attribute *attr, | |
154 | const char *buf, size_t count) | |
155 | { | |
156 | struct backing_dev_info *bdi = dev_get_drvdata(dev); | |
157 | char *end; | |
158 | unsigned long read_ahead_kb; | |
159 | ssize_t ret = -EINVAL; | |
160 | ||
161 | read_ahead_kb = simple_strtoul(buf, &end, 10); | |
162 | if (*buf && (end[0] == '\0' || (end[0] == '\n' && end[1] == '\0'))) { | |
163 | bdi->ra_pages = read_ahead_kb >> (PAGE_SHIFT - 10); | |
164 | ret = count; | |
165 | } | |
166 | return ret; | |
167 | } | |
168 | ||
169 | #define K(pages) ((pages) << (PAGE_SHIFT - 10)) | |
170 | ||
171 | #define BDI_SHOW(name, expr) \ | |
172 | static ssize_t name##_show(struct device *dev, \ | |
173 | struct device_attribute *attr, char *page) \ | |
174 | { \ | |
175 | struct backing_dev_info *bdi = dev_get_drvdata(dev); \ | |
176 | \ | |
177 | return snprintf(page, PAGE_SIZE-1, "%lld\n", (long long)expr); \ | |
178 | } | |
179 | ||
180 | BDI_SHOW(read_ahead_kb, K(bdi->ra_pages)) | |
181 | ||
189d3c4a PZ |
182 | static ssize_t min_ratio_store(struct device *dev, |
183 | struct device_attribute *attr, const char *buf, size_t count) | |
184 | { | |
185 | struct backing_dev_info *bdi = dev_get_drvdata(dev); | |
186 | char *end; | |
187 | unsigned int ratio; | |
188 | ssize_t ret = -EINVAL; | |
189 | ||
190 | ratio = simple_strtoul(buf, &end, 10); | |
191 | if (*buf && (end[0] == '\0' || (end[0] == '\n' && end[1] == '\0'))) { | |
192 | ret = bdi_set_min_ratio(bdi, ratio); | |
193 | if (!ret) | |
194 | ret = count; | |
195 | } | |
196 | return ret; | |
197 | } | |
198 | BDI_SHOW(min_ratio, bdi->min_ratio) | |
199 | ||
a42dde04 PZ |
200 | static ssize_t max_ratio_store(struct device *dev, |
201 | struct device_attribute *attr, const char *buf, size_t count) | |
202 | { | |
203 | struct backing_dev_info *bdi = dev_get_drvdata(dev); | |
204 | char *end; | |
205 | unsigned int ratio; | |
206 | ssize_t ret = -EINVAL; | |
207 | ||
208 | ratio = simple_strtoul(buf, &end, 10); | |
209 | if (*buf && (end[0] == '\0' || (end[0] == '\n' && end[1] == '\0'))) { | |
210 | ret = bdi_set_max_ratio(bdi, ratio); | |
211 | if (!ret) | |
212 | ret = count; | |
213 | } | |
214 | return ret; | |
215 | } | |
216 | BDI_SHOW(max_ratio, bdi->max_ratio) | |
217 | ||
cf0ca9fe PZ |
218 | #define __ATTR_RW(attr) __ATTR(attr, 0644, attr##_show, attr##_store) |
219 | ||
220 | static struct device_attribute bdi_dev_attrs[] = { | |
221 | __ATTR_RW(read_ahead_kb), | |
189d3c4a | 222 | __ATTR_RW(min_ratio), |
a42dde04 | 223 | __ATTR_RW(max_ratio), |
cf0ca9fe PZ |
224 | __ATTR_NULL, |
225 | }; | |
226 | ||
227 | static __init int bdi_class_init(void) | |
228 | { | |
229 | bdi_class = class_create(THIS_MODULE, "bdi"); | |
14421453 AB |
230 | if (IS_ERR(bdi_class)) |
231 | return PTR_ERR(bdi_class); | |
232 | ||
cf0ca9fe | 233 | bdi_class->dev_attrs = bdi_dev_attrs; |
76f1418b | 234 | bdi_debug_init(); |
cf0ca9fe PZ |
235 | return 0; |
236 | } | |
76f1418b | 237 | postcore_initcall(bdi_class_init); |
cf0ca9fe | 238 | |
26160158 JA |
239 | static int __init default_bdi_init(void) |
240 | { | |
241 | int err; | |
242 | ||
03ba3782 JA |
243 | sync_supers_tsk = kthread_run(bdi_sync_supers, NULL, "sync_supers"); |
244 | BUG_ON(IS_ERR(sync_supers_tsk)); | |
245 | ||
246 | init_timer(&sync_supers_timer); | |
247 | setup_timer(&sync_supers_timer, sync_supers_timer_fn, 0); | |
248 | arm_supers_timer(); | |
249 | ||
26160158 JA |
250 | err = bdi_init(&default_backing_dev_info); |
251 | if (!err) | |
252 | bdi_register(&default_backing_dev_info, NULL, "default"); | |
253 | ||
254 | return err; | |
255 | } | |
256 | subsys_initcall(default_bdi_init); | |
257 | ||
03ba3782 JA |
258 | static void bdi_wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi) |
259 | { | |
260 | memset(wb, 0, sizeof(*wb)); | |
261 | ||
262 | wb->bdi = bdi; | |
263 | wb->last_old_flush = jiffies; | |
264 | INIT_LIST_HEAD(&wb->b_dirty); | |
265 | INIT_LIST_HEAD(&wb->b_io); | |
266 | INIT_LIST_HEAD(&wb->b_more_io); | |
267 | } | |
268 | ||
269 | static void bdi_task_init(struct backing_dev_info *bdi, | |
270 | struct bdi_writeback *wb) | |
271 | { | |
272 | struct task_struct *tsk = current; | |
273 | ||
274 | spin_lock(&bdi->wb_lock); | |
275 | list_add_tail_rcu(&wb->list, &bdi->wb_list); | |
276 | spin_unlock(&bdi->wb_lock); | |
277 | ||
278 | tsk->flags |= PF_FLUSHER | PF_SWAPWRITE; | |
279 | set_freezable(); | |
280 | ||
281 | /* | |
282 | * Our parent may run at a different priority, just set us to normal | |
283 | */ | |
284 | set_user_nice(tsk, 0); | |
285 | } | |
286 | ||
287 | static int bdi_start_fn(void *ptr) | |
288 | { | |
289 | struct bdi_writeback *wb = ptr; | |
290 | struct backing_dev_info *bdi = wb->bdi; | |
291 | int ret; | |
292 | ||
293 | /* | |
294 | * Add us to the active bdi_list | |
295 | */ | |
cfc4ba53 JA |
296 | spin_lock_bh(&bdi_lock); |
297 | list_add_rcu(&bdi->bdi_list, &bdi_list); | |
298 | spin_unlock_bh(&bdi_lock); | |
03ba3782 JA |
299 | |
300 | bdi_task_init(bdi, wb); | |
301 | ||
302 | /* | |
303 | * Clear pending bit and wakeup anybody waiting to tear us down | |
304 | */ | |
305 | clear_bit(BDI_pending, &bdi->state); | |
306 | smp_mb__after_clear_bit(); | |
307 | wake_up_bit(&bdi->state, BDI_pending); | |
308 | ||
309 | ret = bdi_writeback_task(wb); | |
310 | ||
311 | /* | |
312 | * Remove us from the list | |
313 | */ | |
314 | spin_lock(&bdi->wb_lock); | |
315 | list_del_rcu(&wb->list); | |
316 | spin_unlock(&bdi->wb_lock); | |
317 | ||
318 | /* | |
319 | * Flush any work that raced with us exiting. No new work | |
320 | * will be added, since this bdi isn't discoverable anymore. | |
321 | */ | |
322 | if (!list_empty(&bdi->work_list)) | |
323 | wb_do_writeback(wb, 1); | |
324 | ||
325 | wb->task = NULL; | |
326 | return ret; | |
327 | } | |
328 | ||
329 | int bdi_has_dirty_io(struct backing_dev_info *bdi) | |
330 | { | |
331 | return wb_has_dirty_io(&bdi->wb); | |
332 | } | |
333 | ||
334 | static void bdi_flush_io(struct backing_dev_info *bdi) | |
335 | { | |
336 | struct writeback_control wbc = { | |
337 | .bdi = bdi, | |
338 | .sync_mode = WB_SYNC_NONE, | |
339 | .older_than_this = NULL, | |
340 | .range_cyclic = 1, | |
341 | .nr_to_write = 1024, | |
342 | }; | |
343 | ||
344 | writeback_inodes_wbc(&wbc); | |
345 | } | |
346 | ||
347 | /* | |
348 | * kupdated() used to do this. We cannot do it from the bdi_forker_task() | |
349 | * or we risk deadlocking on ->s_umount. The longer term solution would be | |
350 | * to implement sync_supers_bdi() or similar and simply do it from the | |
351 | * bdi writeback tasks individually. | |
352 | */ | |
353 | static int bdi_sync_supers(void *unused) | |
354 | { | |
355 | set_user_nice(current, 0); | |
356 | ||
357 | while (!kthread_should_stop()) { | |
358 | set_current_state(TASK_INTERRUPTIBLE); | |
359 | schedule(); | |
360 | ||
361 | /* | |
362 | * Do this periodically, like kupdated() did before. | |
363 | */ | |
364 | sync_supers(); | |
365 | } | |
366 | ||
367 | return 0; | |
368 | } | |
369 | ||
370 | static void arm_supers_timer(void) | |
371 | { | |
372 | unsigned long next; | |
373 | ||
374 | next = msecs_to_jiffies(dirty_writeback_interval * 10) + jiffies; | |
375 | mod_timer(&sync_supers_timer, round_jiffies_up(next)); | |
376 | } | |
377 | ||
378 | static void sync_supers_timer_fn(unsigned long unused) | |
379 | { | |
380 | wake_up_process(sync_supers_tsk); | |
381 | arm_supers_timer(); | |
382 | } | |
383 | ||
384 | static int bdi_forker_task(void *ptr) | |
385 | { | |
386 | struct bdi_writeback *me = ptr; | |
387 | ||
388 | bdi_task_init(me->bdi, me); | |
389 | ||
390 | for (;;) { | |
391 | struct backing_dev_info *bdi, *tmp; | |
392 | struct bdi_writeback *wb; | |
393 | ||
394 | /* | |
395 | * Temporary measure, we want to make sure we don't see | |
396 | * dirty data on the default backing_dev_info | |
397 | */ | |
398 | if (wb_has_dirty_io(me) || !list_empty(&me->bdi->work_list)) | |
399 | wb_do_writeback(me, 0); | |
400 | ||
cfc4ba53 | 401 | spin_lock_bh(&bdi_lock); |
03ba3782 JA |
402 | |
403 | /* | |
404 | * Check if any existing bdi's have dirty data without | |
405 | * a thread registered. If so, set that up. | |
406 | */ | |
407 | list_for_each_entry_safe(bdi, tmp, &bdi_list, bdi_list) { | |
408 | if (bdi->wb.task) | |
409 | continue; | |
410 | if (list_empty(&bdi->work_list) && | |
411 | !bdi_has_dirty_io(bdi)) | |
412 | continue; | |
413 | ||
414 | bdi_add_default_flusher_task(bdi); | |
415 | } | |
416 | ||
417 | set_current_state(TASK_INTERRUPTIBLE); | |
418 | ||
419 | if (list_empty(&bdi_pending_list)) { | |
420 | unsigned long wait; | |
421 | ||
cfc4ba53 | 422 | spin_unlock_bh(&bdi_lock); |
03ba3782 JA |
423 | wait = msecs_to_jiffies(dirty_writeback_interval * 10); |
424 | schedule_timeout(wait); | |
425 | try_to_freeze(); | |
426 | continue; | |
427 | } | |
428 | ||
429 | __set_current_state(TASK_RUNNING); | |
430 | ||
431 | /* | |
432 | * This is our real job - check for pending entries in | |
433 | * bdi_pending_list, and create the tasks that got added | |
434 | */ | |
435 | bdi = list_entry(bdi_pending_list.next, struct backing_dev_info, | |
436 | bdi_list); | |
437 | list_del_init(&bdi->bdi_list); | |
cfc4ba53 | 438 | spin_unlock_bh(&bdi_lock); |
03ba3782 JA |
439 | |
440 | wb = &bdi->wb; | |
441 | wb->task = kthread_run(bdi_start_fn, wb, "flush-%s", | |
442 | dev_name(bdi->dev)); | |
443 | /* | |
444 | * If task creation fails, then readd the bdi to | |
445 | * the pending list and force writeout of the bdi | |
446 | * from this forker thread. That will free some memory | |
447 | * and we can try again. | |
448 | */ | |
449 | if (IS_ERR(wb->task)) { | |
450 | wb->task = NULL; | |
451 | ||
452 | /* | |
453 | * Add this 'bdi' to the back, so we get | |
454 | * a chance to flush other bdi's to free | |
455 | * memory. | |
456 | */ | |
cfc4ba53 | 457 | spin_lock_bh(&bdi_lock); |
03ba3782 | 458 | list_add_tail(&bdi->bdi_list, &bdi_pending_list); |
cfc4ba53 | 459 | spin_unlock_bh(&bdi_lock); |
03ba3782 JA |
460 | |
461 | bdi_flush_io(bdi); | |
462 | } | |
463 | } | |
464 | ||
465 | return 0; | |
466 | } | |
467 | ||
cfc4ba53 JA |
468 | static void bdi_add_to_pending(struct rcu_head *head) |
469 | { | |
470 | struct backing_dev_info *bdi; | |
471 | ||
472 | bdi = container_of(head, struct backing_dev_info, rcu_head); | |
473 | INIT_LIST_HEAD(&bdi->bdi_list); | |
474 | ||
475 | spin_lock(&bdi_lock); | |
476 | list_add_tail(&bdi->bdi_list, &bdi_pending_list); | |
477 | spin_unlock(&bdi_lock); | |
478 | ||
479 | /* | |
480 | * We are now on the pending list, wake up bdi_forker_task() | |
481 | * to finish the job and add us back to the active bdi_list | |
482 | */ | |
483 | wake_up_process(default_backing_dev_info.wb.task); | |
484 | } | |
485 | ||
03ba3782 JA |
486 | /* |
487 | * Add the default flusher task that gets created for any bdi | |
488 | * that has dirty data pending writeout | |
489 | */ | |
490 | void static bdi_add_default_flusher_task(struct backing_dev_info *bdi) | |
491 | { | |
492 | if (!bdi_cap_writeback_dirty(bdi)) | |
493 | return; | |
494 | ||
500b067c JA |
495 | if (WARN_ON(!test_bit(BDI_registered, &bdi->state))) { |
496 | printk(KERN_ERR "bdi %p/%s is not registered!\n", | |
497 | bdi, bdi->name); | |
498 | return; | |
499 | } | |
500 | ||
03ba3782 JA |
501 | /* |
502 | * Check with the helper whether to proceed adding a task. Will only | |
503 | * abort if we two or more simultanous calls to | |
504 | * bdi_add_default_flusher_task() occured, further additions will block | |
505 | * waiting for previous additions to finish. | |
506 | */ | |
507 | if (!test_and_set_bit(BDI_pending, &bdi->state)) { | |
cfc4ba53 | 508 | list_del_rcu(&bdi->bdi_list); |
03ba3782 JA |
509 | |
510 | /* | |
cfc4ba53 JA |
511 | * We must wait for the current RCU period to end before |
512 | * moving to the pending list. So schedule that operation | |
513 | * from an RCU callback. | |
03ba3782 | 514 | */ |
cfc4ba53 | 515 | call_rcu(&bdi->rcu_head, bdi_add_to_pending); |
03ba3782 JA |
516 | } |
517 | } | |
518 | ||
cfc4ba53 JA |
519 | /* |
520 | * Remove bdi from bdi_list, and ensure that it is no longer visible | |
521 | */ | |
522 | static void bdi_remove_from_list(struct backing_dev_info *bdi) | |
523 | { | |
524 | spin_lock_bh(&bdi_lock); | |
525 | list_del_rcu(&bdi->bdi_list); | |
526 | spin_unlock_bh(&bdi_lock); | |
527 | ||
528 | synchronize_rcu(); | |
529 | } | |
530 | ||
cf0ca9fe PZ |
531 | int bdi_register(struct backing_dev_info *bdi, struct device *parent, |
532 | const char *fmt, ...) | |
533 | { | |
cf0ca9fe PZ |
534 | va_list args; |
535 | int ret = 0; | |
536 | struct device *dev; | |
537 | ||
69fc208b | 538 | if (bdi->dev) /* The driver needs to use separate queues per device */ |
f1d0b063 KS |
539 | goto exit; |
540 | ||
cf0ca9fe | 541 | va_start(args, fmt); |
19051c50 | 542 | dev = device_create_vargs(bdi_class, parent, MKDEV(0, 0), bdi, fmt, args); |
cf0ca9fe | 543 | va_end(args); |
cf0ca9fe PZ |
544 | if (IS_ERR(dev)) { |
545 | ret = PTR_ERR(dev); | |
546 | goto exit; | |
547 | } | |
548 | ||
cfc4ba53 JA |
549 | spin_lock_bh(&bdi_lock); |
550 | list_add_tail_rcu(&bdi->bdi_list, &bdi_list); | |
551 | spin_unlock_bh(&bdi_lock); | |
66f3b8e2 | 552 | |
cf0ca9fe | 553 | bdi->dev = dev; |
cf0ca9fe | 554 | |
03ba3782 JA |
555 | /* |
556 | * Just start the forker thread for our default backing_dev_info, | |
557 | * and add other bdi's to the list. They will get a thread created | |
558 | * on-demand when they need it. | |
559 | */ | |
560 | if (bdi_cap_flush_forker(bdi)) { | |
561 | struct bdi_writeback *wb = &bdi->wb; | |
562 | ||
563 | wb->task = kthread_run(bdi_forker_task, wb, "bdi-%s", | |
564 | dev_name(dev)); | |
565 | if (IS_ERR(wb->task)) { | |
566 | wb->task = NULL; | |
567 | ret = -ENOMEM; | |
568 | ||
cfc4ba53 | 569 | bdi_remove_from_list(bdi); |
03ba3782 JA |
570 | goto exit; |
571 | } | |
572 | } | |
573 | ||
574 | bdi_debug_register(bdi, dev_name(dev)); | |
500b067c | 575 | set_bit(BDI_registered, &bdi->state); |
cf0ca9fe | 576 | exit: |
cf0ca9fe PZ |
577 | return ret; |
578 | } | |
579 | EXPORT_SYMBOL(bdi_register); | |
580 | ||
581 | int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev) | |
582 | { | |
583 | return bdi_register(bdi, NULL, "%u:%u", MAJOR(dev), MINOR(dev)); | |
584 | } | |
585 | EXPORT_SYMBOL(bdi_register_dev); | |
586 | ||
03ba3782 JA |
587 | /* |
588 | * Remove bdi from the global list and shutdown any threads we have running | |
589 | */ | |
590 | static void bdi_wb_shutdown(struct backing_dev_info *bdi) | |
66f3b8e2 | 591 | { |
03ba3782 JA |
592 | struct bdi_writeback *wb; |
593 | ||
594 | if (!bdi_cap_writeback_dirty(bdi)) | |
595 | return; | |
596 | ||
597 | /* | |
598 | * If setup is pending, wait for that to complete first | |
599 | */ | |
600 | wait_on_bit(&bdi->state, BDI_pending, bdi_sched_wait, | |
601 | TASK_UNINTERRUPTIBLE); | |
602 | ||
603 | /* | |
604 | * Make sure nobody finds us on the bdi_list anymore | |
605 | */ | |
cfc4ba53 | 606 | bdi_remove_from_list(bdi); |
03ba3782 JA |
607 | |
608 | /* | |
609 | * Finally, kill the kernel threads. We don't need to be RCU | |
c62b17a5 RD |
610 | * safe anymore, since the bdi is gone from visibility. Force |
611 | * unfreeze of the thread before calling kthread_stop(), otherwise | |
612 | * it would never exet if it is currently stuck in the refrigerator. | |
03ba3782 | 613 | */ |
c62b17a5 | 614 | list_for_each_entry(wb, &bdi->wb_list, list) { |
bf7ec5bb | 615 | thaw_process(wb->task); |
03ba3782 | 616 | kthread_stop(wb->task); |
c62b17a5 | 617 | } |
66f3b8e2 JA |
618 | } |
619 | ||
592b09a4 JA |
620 | /* |
621 | * This bdi is going away now, make sure that no super_blocks point to it | |
622 | */ | |
623 | static void bdi_prune_sb(struct backing_dev_info *bdi) | |
624 | { | |
625 | struct super_block *sb; | |
626 | ||
627 | spin_lock(&sb_lock); | |
628 | list_for_each_entry(sb, &super_blocks, s_list) { | |
629 | if (sb->s_bdi == bdi) | |
630 | sb->s_bdi = NULL; | |
631 | } | |
632 | spin_unlock(&sb_lock); | |
633 | } | |
634 | ||
cf0ca9fe PZ |
635 | void bdi_unregister(struct backing_dev_info *bdi) |
636 | { | |
637 | if (bdi->dev) { | |
8c4db335 JA |
638 | bdi_prune_sb(bdi); |
639 | ||
03ba3782 JA |
640 | if (!bdi_cap_flush_forker(bdi)) |
641 | bdi_wb_shutdown(bdi); | |
76f1418b | 642 | bdi_debug_unregister(bdi); |
cf0ca9fe PZ |
643 | device_unregister(bdi->dev); |
644 | bdi->dev = NULL; | |
645 | } | |
646 | } | |
647 | EXPORT_SYMBOL(bdi_unregister); | |
3fcfab16 | 648 | |
b2e8fb6e PZ |
649 | int bdi_init(struct backing_dev_info *bdi) |
650 | { | |
03ba3782 | 651 | int i, err; |
b2e8fb6e | 652 | |
cf0ca9fe PZ |
653 | bdi->dev = NULL; |
654 | ||
189d3c4a | 655 | bdi->min_ratio = 0; |
a42dde04 PZ |
656 | bdi->max_ratio = 100; |
657 | bdi->max_prop_frac = PROP_FRAC_BASE; | |
03ba3782 | 658 | spin_lock_init(&bdi->wb_lock); |
cfc4ba53 | 659 | INIT_RCU_HEAD(&bdi->rcu_head); |
66f3b8e2 | 660 | INIT_LIST_HEAD(&bdi->bdi_list); |
03ba3782 JA |
661 | INIT_LIST_HEAD(&bdi->wb_list); |
662 | INIT_LIST_HEAD(&bdi->work_list); | |
663 | ||
664 | bdi_wb_init(&bdi->wb, bdi); | |
665 | ||
666 | /* | |
667 | * Just one thread support for now, hard code mask and count | |
668 | */ | |
669 | bdi->wb_mask = 1; | |
670 | bdi->wb_cnt = 1; | |
189d3c4a | 671 | |
b2e8fb6e | 672 | for (i = 0; i < NR_BDI_STAT_ITEMS; i++) { |
ea319518 | 673 | err = percpu_counter_init(&bdi->bdi_stat[i], 0); |
04fbfdc1 PZ |
674 | if (err) |
675 | goto err; | |
676 | } | |
677 | ||
678 | bdi->dirty_exceeded = 0; | |
679 | err = prop_local_init_percpu(&bdi->completions); | |
680 | ||
681 | if (err) { | |
682 | err: | |
4b01a0b1 | 683 | while (i--) |
04fbfdc1 | 684 | percpu_counter_destroy(&bdi->bdi_stat[i]); |
b2e8fb6e PZ |
685 | } |
686 | ||
687 | return err; | |
688 | } | |
689 | EXPORT_SYMBOL(bdi_init); | |
690 | ||
691 | void bdi_destroy(struct backing_dev_info *bdi) | |
692 | { | |
693 | int i; | |
694 | ||
ce5f8e77 JA |
695 | /* |
696 | * Splice our entries to the default_backing_dev_info, if this | |
697 | * bdi disappears | |
698 | */ | |
699 | if (bdi_has_dirty_io(bdi)) { | |
700 | struct bdi_writeback *dst = &default_backing_dev_info.wb; | |
701 | ||
702 | spin_lock(&inode_lock); | |
703 | list_splice(&bdi->wb.b_dirty, &dst->b_dirty); | |
704 | list_splice(&bdi->wb.b_io, &dst->b_io); | |
705 | list_splice(&bdi->wb.b_more_io, &dst->b_more_io); | |
706 | spin_unlock(&inode_lock); | |
707 | } | |
66f3b8e2 | 708 | |
cf0ca9fe PZ |
709 | bdi_unregister(bdi); |
710 | ||
b2e8fb6e PZ |
711 | for (i = 0; i < NR_BDI_STAT_ITEMS; i++) |
712 | percpu_counter_destroy(&bdi->bdi_stat[i]); | |
04fbfdc1 PZ |
713 | |
714 | prop_local_destroy_percpu(&bdi->completions); | |
b2e8fb6e PZ |
715 | } |
716 | EXPORT_SYMBOL(bdi_destroy); | |
717 | ||
3fcfab16 AM |
718 | static wait_queue_head_t congestion_wqh[2] = { |
719 | __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]), | |
720 | __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1]) | |
721 | }; | |
722 | ||
1faa16d2 | 723 | void clear_bdi_congested(struct backing_dev_info *bdi, int sync) |
3fcfab16 AM |
724 | { |
725 | enum bdi_state bit; | |
1faa16d2 | 726 | wait_queue_head_t *wqh = &congestion_wqh[sync]; |
3fcfab16 | 727 | |
1faa16d2 | 728 | bit = sync ? BDI_sync_congested : BDI_async_congested; |
3fcfab16 AM |
729 | clear_bit(bit, &bdi->state); |
730 | smp_mb__after_clear_bit(); | |
731 | if (waitqueue_active(wqh)) | |
732 | wake_up(wqh); | |
733 | } | |
734 | EXPORT_SYMBOL(clear_bdi_congested); | |
735 | ||
1faa16d2 | 736 | void set_bdi_congested(struct backing_dev_info *bdi, int sync) |
3fcfab16 AM |
737 | { |
738 | enum bdi_state bit; | |
739 | ||
1faa16d2 | 740 | bit = sync ? BDI_sync_congested : BDI_async_congested; |
3fcfab16 AM |
741 | set_bit(bit, &bdi->state); |
742 | } | |
743 | EXPORT_SYMBOL(set_bdi_congested); | |
744 | ||
745 | /** | |
746 | * congestion_wait - wait for a backing_dev to become uncongested | |
8aa7e847 | 747 | * @sync: SYNC or ASYNC IO |
3fcfab16 AM |
748 | * @timeout: timeout in jiffies |
749 | * | |
750 | * Waits for up to @timeout jiffies for a backing_dev (any backing_dev) to exit | |
751 | * write congestion. If no backing_devs are congested then just wait for the | |
752 | * next write to be completed. | |
753 | */ | |
8aa7e847 | 754 | long congestion_wait(int sync, long timeout) |
3fcfab16 AM |
755 | { |
756 | long ret; | |
757 | DEFINE_WAIT(wait); | |
8aa7e847 | 758 | wait_queue_head_t *wqh = &congestion_wqh[sync]; |
3fcfab16 AM |
759 | |
760 | prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); | |
761 | ret = io_schedule_timeout(timeout); | |
762 | finish_wait(wqh, &wait); | |
763 | return ret; | |
764 | } | |
765 | EXPORT_SYMBOL(congestion_wait); | |
04fbfdc1 | 766 |