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3fcfab1 [PATCH] separate bdi congestion functions from queue congestion funct…
Andrew Morton authored
1
2 #include <linux/wait.h>
3 #include <linux/backing-dev.h>
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Jens Axboe authored
4 #include <linux/kthread.h>
5 #include <linux/freezer.h>
3fcfab1 [PATCH] separate bdi congestion functions from queue congestion funct…
Andrew Morton authored
6 #include <linux/fs.h>
2616015 Move the default_backing_dev_info out of readahead.c and into backing…
Jens Axboe authored
7 #include <linux/pagemap.h>
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8 #include <linux/mm.h>
3fcfab1 [PATCH] separate bdi congestion functions from queue congestion funct…
Andrew Morton authored
9 #include <linux/sched.h>
10 #include <linux/module.h>
cf0ca9f mm: bdi: export BDI attributes in sysfs
Peter Zijlstra authored
11 #include <linux/writeback.h>
12 #include <linux/device.h>
13
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Jens Axboe authored
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 = {
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20 .name = "default",
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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);
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27
28 static struct class *bdi_class;
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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 */
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35 DEFINE_SPINLOCK(bdi_lock);
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36 LIST_HEAD(bdi_list);
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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);
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47
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Miklos Szeredi authored
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;
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62 struct bdi_writeback *wb;
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David Rientjes authored
63 unsigned long background_thresh;
64 unsigned long dirty_thresh;
65 unsigned long bdi_thresh;
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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);
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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"
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94 "BackgroundThresh: %8lu kB\n"
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fengguang authored
95 "WritebackThreads: %8lu\n"
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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",
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104 (unsigned long) K(bdi_stat(bdi, BDI_WRITEBACK)),
105 (unsigned long) K(bdi_stat(bdi, BDI_RECLAIMABLE)),
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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);
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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
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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
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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
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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
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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),
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222 __ATTR_RW(min_ratio),
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223 __ATTR_RW(max_ratio),
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224 __ATTR_NULL,
225 };
226
227 static __init int bdi_class_init(void)
228 {
229 bdi_class = class_create(THIS_MODULE, "bdi");
230 bdi_class->dev_attrs = bdi_dev_attrs;
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231 bdi_debug_init();
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232 return 0;
233 }
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234 postcore_initcall(bdi_class_init);
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235
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Jens Axboe authored
236 static int __init default_bdi_init(void)
237 {
238 int err;
239
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240 sync_supers_tsk = kthread_run(bdi_sync_supers, NULL, "sync_supers");
241 BUG_ON(IS_ERR(sync_supers_tsk));
242
243 init_timer(&sync_supers_timer);
244 setup_timer(&sync_supers_timer, sync_supers_timer_fn, 0);
245 arm_supers_timer();
246
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247 err = bdi_init(&default_backing_dev_info);
248 if (!err)
249 bdi_register(&default_backing_dev_info, NULL, "default");
250
251 return err;
252 }
253 subsys_initcall(default_bdi_init);
254
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255 static void bdi_wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi)
256 {
257 memset(wb, 0, sizeof(*wb));
258
259 wb->bdi = bdi;
260 wb->last_old_flush = jiffies;
261 INIT_LIST_HEAD(&wb->b_dirty);
262 INIT_LIST_HEAD(&wb->b_io);
263 INIT_LIST_HEAD(&wb->b_more_io);
264 }
265
266 static void bdi_task_init(struct backing_dev_info *bdi,
267 struct bdi_writeback *wb)
268 {
269 struct task_struct *tsk = current;
270
271 spin_lock(&bdi->wb_lock);
272 list_add_tail_rcu(&wb->list, &bdi->wb_list);
273 spin_unlock(&bdi->wb_lock);
274
275 tsk->flags |= PF_FLUSHER | PF_SWAPWRITE;
276 set_freezable();
277
278 /*
279 * Our parent may run at a different priority, just set us to normal
280 */
281 set_user_nice(tsk, 0);
282 }
283
284 static int bdi_start_fn(void *ptr)
285 {
286 struct bdi_writeback *wb = ptr;
287 struct backing_dev_info *bdi = wb->bdi;
288 int ret;
289
290 /*
291 * Add us to the active bdi_list
292 */
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293 spin_lock_bh(&bdi_lock);
294 list_add_rcu(&bdi->bdi_list, &bdi_list);
295 spin_unlock_bh(&bdi_lock);
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296
297 bdi_task_init(bdi, wb);
298
299 /*
300 * Clear pending bit and wakeup anybody waiting to tear us down
301 */
302 clear_bit(BDI_pending, &bdi->state);
303 smp_mb__after_clear_bit();
304 wake_up_bit(&bdi->state, BDI_pending);
305
306 ret = bdi_writeback_task(wb);
307
308 /*
309 * Remove us from the list
310 */
311 spin_lock(&bdi->wb_lock);
312 list_del_rcu(&wb->list);
313 spin_unlock(&bdi->wb_lock);
314
315 /*
316 * Flush any work that raced with us exiting. No new work
317 * will be added, since this bdi isn't discoverable anymore.
318 */
319 if (!list_empty(&bdi->work_list))
320 wb_do_writeback(wb, 1);
321
322 wb->task = NULL;
323 return ret;
324 }
325
326 int bdi_has_dirty_io(struct backing_dev_info *bdi)
327 {
328 return wb_has_dirty_io(&bdi->wb);
329 }
330
331 static void bdi_flush_io(struct backing_dev_info *bdi)
332 {
333 struct writeback_control wbc = {
334 .bdi = bdi,
335 .sync_mode = WB_SYNC_NONE,
336 .older_than_this = NULL,
337 .range_cyclic = 1,
338 .nr_to_write = 1024,
339 };
340
341 writeback_inodes_wbc(&wbc);
342 }
343
344 /*
345 * kupdated() used to do this. We cannot do it from the bdi_forker_task()
346 * or we risk deadlocking on ->s_umount. The longer term solution would be
347 * to implement sync_supers_bdi() or similar and simply do it from the
348 * bdi writeback tasks individually.
349 */
350 static int bdi_sync_supers(void *unused)
351 {
352 set_user_nice(current, 0);
353
354 while (!kthread_should_stop()) {
355 set_current_state(TASK_INTERRUPTIBLE);
356 schedule();
357
358 /*
359 * Do this periodically, like kupdated() did before.
360 */
361 sync_supers();
362 }
363
364 return 0;
365 }
366
367 static void arm_supers_timer(void)
368 {
369 unsigned long next;
370
371 next = msecs_to_jiffies(dirty_writeback_interval * 10) + jiffies;
372 mod_timer(&sync_supers_timer, round_jiffies_up(next));
373 }
374
375 static void sync_supers_timer_fn(unsigned long unused)
376 {
377 wake_up_process(sync_supers_tsk);
378 arm_supers_timer();
379 }
380
381 static int bdi_forker_task(void *ptr)
382 {
383 struct bdi_writeback *me = ptr;
384
385 bdi_task_init(me->bdi, me);
386
387 for (;;) {
388 struct backing_dev_info *bdi, *tmp;
389 struct bdi_writeback *wb;
390
391 /*
392 * Temporary measure, we want to make sure we don't see
393 * dirty data on the default backing_dev_info
394 */
395 if (wb_has_dirty_io(me) || !list_empty(&me->bdi->work_list))
396 wb_do_writeback(me, 0);
397
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398 spin_lock_bh(&bdi_lock);
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399
400 /*
401 * Check if any existing bdi's have dirty data without
402 * a thread registered. If so, set that up.
403 */
404 list_for_each_entry_safe(bdi, tmp, &bdi_list, bdi_list) {
405 if (bdi->wb.task)
406 continue;
407 if (list_empty(&bdi->work_list) &&
408 !bdi_has_dirty_io(bdi))
409 continue;
410
411 bdi_add_default_flusher_task(bdi);
412 }
413
414 set_current_state(TASK_INTERRUPTIBLE);
415
416 if (list_empty(&bdi_pending_list)) {
417 unsigned long wait;
418
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419 spin_unlock_bh(&bdi_lock);
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420 wait = msecs_to_jiffies(dirty_writeback_interval * 10);
421 schedule_timeout(wait);
422 try_to_freeze();
423 continue;
424 }
425
426 __set_current_state(TASK_RUNNING);
427
428 /*
429 * This is our real job - check for pending entries in
430 * bdi_pending_list, and create the tasks that got added
431 */
432 bdi = list_entry(bdi_pending_list.next, struct backing_dev_info,
433 bdi_list);
434 list_del_init(&bdi->bdi_list);
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435 spin_unlock_bh(&bdi_lock);
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436
437 wb = &bdi->wb;
438 wb->task = kthread_run(bdi_start_fn, wb, "flush-%s",
439 dev_name(bdi->dev));
440 /*
441 * If task creation fails, then readd the bdi to
442 * the pending list and force writeout of the bdi
443 * from this forker thread. That will free some memory
444 * and we can try again.
445 */
446 if (IS_ERR(wb->task)) {
447 wb->task = NULL;
448
449 /*
450 * Add this 'bdi' to the back, so we get
451 * a chance to flush other bdi's to free
452 * memory.
453 */
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454 spin_lock_bh(&bdi_lock);
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455 list_add_tail(&bdi->bdi_list, &bdi_pending_list);
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456 spin_unlock_bh(&bdi_lock);
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457
458 bdi_flush_io(bdi);
459 }
460 }
461
462 return 0;
463 }
464
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465 static void bdi_add_to_pending(struct rcu_head *head)
466 {
467 struct backing_dev_info *bdi;
468
469 bdi = container_of(head, struct backing_dev_info, rcu_head);
470 INIT_LIST_HEAD(&bdi->bdi_list);
471
472 spin_lock(&bdi_lock);
473 list_add_tail(&bdi->bdi_list, &bdi_pending_list);
474 spin_unlock(&bdi_lock);
475
476 /*
477 * We are now on the pending list, wake up bdi_forker_task()
478 * to finish the job and add us back to the active bdi_list
479 */
480 wake_up_process(default_backing_dev_info.wb.task);
481 }
482
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483 /*
484 * Add the default flusher task that gets created for any bdi
485 * that has dirty data pending writeout
486 */
487 void static bdi_add_default_flusher_task(struct backing_dev_info *bdi)
488 {
489 if (!bdi_cap_writeback_dirty(bdi))
490 return;
491
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492 if (WARN_ON(!test_bit(BDI_registered, &bdi->state))) {
493 printk(KERN_ERR "bdi %p/%s is not registered!\n",
494 bdi, bdi->name);
495 return;
496 }
497
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498 /*
499 * Check with the helper whether to proceed adding a task. Will only
500 * abort if we two or more simultanous calls to
501 * bdi_add_default_flusher_task() occured, further additions will block
502 * waiting for previous additions to finish.
503 */
504 if (!test_and_set_bit(BDI_pending, &bdi->state)) {
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505 list_del_rcu(&bdi->bdi_list);
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506
507 /*
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508 * We must wait for the current RCU period to end before
509 * moving to the pending list. So schedule that operation
510 * from an RCU callback.
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511 */
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512 call_rcu(&bdi->rcu_head, bdi_add_to_pending);
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513 }
514 }
515
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516 /*
517 * Remove bdi from bdi_list, and ensure that it is no longer visible
518 */
519 static void bdi_remove_from_list(struct backing_dev_info *bdi)
520 {
521 spin_lock_bh(&bdi_lock);
522 list_del_rcu(&bdi->bdi_list);
523 spin_unlock_bh(&bdi_lock);
524
525 synchronize_rcu();
526 }
527
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528 int bdi_register(struct backing_dev_info *bdi, struct device *parent,
529 const char *fmt, ...)
530 {
531 va_list args;
532 int ret = 0;
533 struct device *dev;
534
69fc208 mm/backing-dev.c: remove recently-added WARN_ON()
Andrew Morton authored
535 if (bdi->dev) /* The driver needs to use separate queues per device */
f1d0b06 @kaysievers bdi: register sysfs bdi device only once per queue
kaysievers authored
536 goto exit;
537
cf0ca9f mm: bdi: export BDI attributes in sysfs
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538 va_start(args, fmt);
19051c5 @gregkh mm: bdi: fix race in bdi_class device creation
gregkh authored
539 dev = device_create_vargs(bdi_class, parent, MKDEV(0, 0), bdi, fmt, args);
cf0ca9f mm: bdi: export BDI attributes in sysfs
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540 va_end(args);
541 if (IS_ERR(dev)) {
542 ret = PTR_ERR(dev);
543 goto exit;
544 }
545
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546 spin_lock_bh(&bdi_lock);
547 list_add_tail_rcu(&bdi->bdi_list, &bdi_list);
548 spin_unlock_bh(&bdi_lock);
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549
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550 bdi->dev = dev;
551
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552 /*
553 * Just start the forker thread for our default backing_dev_info,
554 * and add other bdi's to the list. They will get a thread created
555 * on-demand when they need it.
556 */
557 if (bdi_cap_flush_forker(bdi)) {
558 struct bdi_writeback *wb = &bdi->wb;
559
560 wb->task = kthread_run(bdi_forker_task, wb, "bdi-%s",
561 dev_name(dev));
562 if (IS_ERR(wb->task)) {
563 wb->task = NULL;
564 ret = -ENOMEM;
565
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566 bdi_remove_from_list(bdi);
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567 goto exit;
568 }
569 }
570
571 bdi_debug_register(bdi, dev_name(dev));
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572 set_bit(BDI_registered, &bdi->state);
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573 exit:
574 return ret;
575 }
576 EXPORT_SYMBOL(bdi_register);
577
578 int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev)
579 {
580 return bdi_register(bdi, NULL, "%u:%u", MAJOR(dev), MINOR(dev));
581 }
582 EXPORT_SYMBOL(bdi_register_dev);
583
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584 /*
585 * Remove bdi from the global list and shutdown any threads we have running
586 */
587 static void bdi_wb_shutdown(struct backing_dev_info *bdi)
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588 {
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589 struct bdi_writeback *wb;
590
591 if (!bdi_cap_writeback_dirty(bdi))
592 return;
593
594 /*
595 * If setup is pending, wait for that to complete first
596 */
597 wait_on_bit(&bdi->state, BDI_pending, bdi_sched_wait,
598 TASK_UNINTERRUPTIBLE);
599
600 /*
601 * Make sure nobody finds us on the bdi_list anymore
602 */
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603 bdi_remove_from_list(bdi);
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604
605 /*
606 * Finally, kill the kernel threads. We don't need to be RCU
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607 * safe anymore, since the bdi is gone from visibility. Force
608 * unfreeze of the thread before calling kthread_stop(), otherwise
609 * it would never exet if it is currently stuck in the refrigerator.
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610 */
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611 list_for_each_entry(wb, &bdi->wb_list, list) {
612 wb->task->flags &= ~PF_FROZEN;
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613 kthread_stop(wb->task);
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614 }
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615 }
616
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617 /*
618 * This bdi is going away now, make sure that no super_blocks point to it
619 */
620 static void bdi_prune_sb(struct backing_dev_info *bdi)
621 {
622 struct super_block *sb;
623
624 spin_lock(&sb_lock);
625 list_for_each_entry(sb, &super_blocks, s_list) {
626 if (sb->s_bdi == bdi)
627 sb->s_bdi = NULL;
628 }
629 spin_unlock(&sb_lock);
630 }
631
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632 void bdi_unregister(struct backing_dev_info *bdi)
633 {
634 if (bdi->dev) {
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635 bdi_prune_sb(bdi);
636
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637 if (!bdi_cap_flush_forker(bdi))
638 bdi_wb_shutdown(bdi);
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639 bdi_debug_unregister(bdi);
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640 device_unregister(bdi->dev);
641 bdi->dev = NULL;
642 }
643 }
644 EXPORT_SYMBOL(bdi_unregister);
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645
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646 int bdi_init(struct backing_dev_info *bdi)
647 {
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648 int i, err;
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649
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650 bdi->dev = NULL;
651
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652 bdi->min_ratio = 0;
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653 bdi->max_ratio = 100;
654 bdi->max_prop_frac = PROP_FRAC_BASE;
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655 spin_lock_init(&bdi->wb_lock);
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656 INIT_RCU_HEAD(&bdi->rcu_head);
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657 INIT_LIST_HEAD(&bdi->bdi_list);
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658 INIT_LIST_HEAD(&bdi->wb_list);
659 INIT_LIST_HEAD(&bdi->work_list);
660
661 bdi_wb_init(&bdi->wb, bdi);
662
663 /*
664 * Just one thread support for now, hard code mask and count
665 */
666 bdi->wb_mask = 1;
667 bdi->wb_cnt = 1;
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668
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669 for (i = 0; i < NR_BDI_STAT_ITEMS; i++) {
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670 err = percpu_counter_init(&bdi->bdi_stat[i], 0);
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671 if (err)
672 goto err;
673 }
674
675 bdi->dirty_exceeded = 0;
676 err = prop_local_init_percpu(&bdi->completions);
677
678 if (err) {
679 err:
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680 while (i--)
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681 percpu_counter_destroy(&bdi->bdi_stat[i]);
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682 }
683
684 return err;
685 }
686 EXPORT_SYMBOL(bdi_init);
687
688 void bdi_destroy(struct backing_dev_info *bdi)
689 {
690 int i;
691
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692 /*
693 * Splice our entries to the default_backing_dev_info, if this
694 * bdi disappears
695 */
696 if (bdi_has_dirty_io(bdi)) {
697 struct bdi_writeback *dst = &default_backing_dev_info.wb;
698
699 spin_lock(&inode_lock);
700 list_splice(&bdi->wb.b_dirty, &dst->b_dirty);
701 list_splice(&bdi->wb.b_io, &dst->b_io);
702 list_splice(&bdi->wb.b_more_io, &dst->b_more_io);
703 spin_unlock(&inode_lock);
704 }
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705
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706 bdi_unregister(bdi);
707
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708 for (i = 0; i < NR_BDI_STAT_ITEMS; i++)
709 percpu_counter_destroy(&bdi->bdi_stat[i]);
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710
711 prop_local_destroy_percpu(&bdi->completions);
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712 }
713 EXPORT_SYMBOL(bdi_destroy);
714
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715 static wait_queue_head_t congestion_wqh[2] = {
716 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]),
717 __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1])
718 };
719
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720 void clear_bdi_congested(struct backing_dev_info *bdi, int sync)
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721 {
722 enum bdi_state bit;
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723 wait_queue_head_t *wqh = &congestion_wqh[sync];
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724
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725 bit = sync ? BDI_sync_congested : BDI_async_congested;
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726 clear_bit(bit, &bdi->state);
727 smp_mb__after_clear_bit();
728 if (waitqueue_active(wqh))
729 wake_up(wqh);
730 }
731 EXPORT_SYMBOL(clear_bdi_congested);
732
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733 void set_bdi_congested(struct backing_dev_info *bdi, int sync)
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734 {
735 enum bdi_state bit;
736
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737 bit = sync ? BDI_sync_congested : BDI_async_congested;
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738 set_bit(bit, &bdi->state);
739 }
740 EXPORT_SYMBOL(set_bdi_congested);
741
742 /**
743 * congestion_wait - wait for a backing_dev to become uncongested
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744 * @sync: SYNC or ASYNC IO
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745 * @timeout: timeout in jiffies
746 *
747 * Waits for up to @timeout jiffies for a backing_dev (any backing_dev) to exit
748 * write congestion. If no backing_devs are congested then just wait for the
749 * next write to be completed.
750 */
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751 long congestion_wait(int sync, long timeout)
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752 {
753 long ret;
754 DEFINE_WAIT(wait);
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755 wait_queue_head_t *wqh = &congestion_wqh[sync];
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756
757 prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE);
758 ret = io_schedule_timeout(timeout);
759 finish_wait(wqh, &wait);
760 return ret;
761 }
762 EXPORT_SYMBOL(congestion_wait);
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763
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