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Commit | Line | Data |
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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 | ||
5129a469 JE |
17 | struct backing_dev_info noop_backing_dev_info = { |
18 | .name = "noop", | |
976e48f8 | 19 | .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK, |
5129a469 | 20 | }; |
5129a469 | 21 | |
cf0ca9fe | 22 | static struct class *bdi_class; |
cfc4ba53 JA |
23 | |
24 | /* | |
181387da | 25 | * bdi_lock protects updates to bdi_list. bdi_list has RCU reader side |
cfc4ba53 JA |
26 | * locking. |
27 | */ | |
03ba3782 | 28 | DEFINE_SPINLOCK(bdi_lock); |
66f3b8e2 | 29 | LIST_HEAD(bdi_list); |
03ba3782 | 30 | |
839a8e86 TH |
31 | /* bdi_wq serves all asynchronous writeback tasks */ |
32 | struct workqueue_struct *bdi_wq; | |
33 | ||
76f1418b MS |
34 | #ifdef CONFIG_DEBUG_FS |
35 | #include <linux/debugfs.h> | |
36 | #include <linux/seq_file.h> | |
37 | ||
38 | static struct dentry *bdi_debug_root; | |
39 | ||
40 | static void bdi_debug_init(void) | |
41 | { | |
42 | bdi_debug_root = debugfs_create_dir("bdi", NULL); | |
43 | } | |
44 | ||
45 | static int bdi_debug_stats_show(struct seq_file *m, void *v) | |
46 | { | |
47 | struct backing_dev_info *bdi = m->private; | |
c1955ce3 | 48 | struct bdi_writeback *wb = &bdi->wb; |
364aeb28 DR |
49 | unsigned long background_thresh; |
50 | unsigned long dirty_thresh; | |
51 | unsigned long bdi_thresh; | |
345227d7 | 52 | unsigned long nr_dirty, nr_io, nr_more_io; |
f09b00d3 JA |
53 | struct inode *inode; |
54 | ||
345227d7 | 55 | nr_dirty = nr_io = nr_more_io = 0; |
f758eeab | 56 | spin_lock(&wb->list_lock); |
7ccf19a8 | 57 | list_for_each_entry(inode, &wb->b_dirty, i_wb_list) |
c1955ce3 | 58 | nr_dirty++; |
7ccf19a8 | 59 | list_for_each_entry(inode, &wb->b_io, i_wb_list) |
c1955ce3 | 60 | nr_io++; |
7ccf19a8 | 61 | list_for_each_entry(inode, &wb->b_more_io, i_wb_list) |
c1955ce3 | 62 | nr_more_io++; |
f758eeab | 63 | spin_unlock(&wb->list_lock); |
76f1418b | 64 | |
16c4042f WF |
65 | global_dirty_limits(&background_thresh, &dirty_thresh); |
66 | bdi_thresh = bdi_dirty_limit(bdi, dirty_thresh); | |
76f1418b MS |
67 | |
68 | #define K(x) ((x) << (PAGE_SHIFT - 10)) | |
69 | seq_printf(m, | |
00821b00 WF |
70 | "BdiWriteback: %10lu kB\n" |
71 | "BdiReclaimable: %10lu kB\n" | |
72 | "BdiDirtyThresh: %10lu kB\n" | |
73 | "DirtyThresh: %10lu kB\n" | |
74 | "BackgroundThresh: %10lu kB\n" | |
c8e28ce0 | 75 | "BdiDirtied: %10lu kB\n" |
00821b00 WF |
76 | "BdiWritten: %10lu kB\n" |
77 | "BdiWriteBandwidth: %10lu kBps\n" | |
78 | "b_dirty: %10lu\n" | |
79 | "b_io: %10lu\n" | |
80 | "b_more_io: %10lu\n" | |
81 | "bdi_list: %10u\n" | |
82 | "state: %10lx\n", | |
76f1418b MS |
83 | (unsigned long) K(bdi_stat(bdi, BDI_WRITEBACK)), |
84 | (unsigned long) K(bdi_stat(bdi, BDI_RECLAIMABLE)), | |
f7d2b1ec JK |
85 | K(bdi_thresh), |
86 | K(dirty_thresh), | |
87 | K(background_thresh), | |
c8e28ce0 | 88 | (unsigned long) K(bdi_stat(bdi, BDI_DIRTIED)), |
f7d2b1ec | 89 | (unsigned long) K(bdi_stat(bdi, BDI_WRITTEN)), |
00821b00 | 90 | (unsigned long) K(bdi->write_bandwidth), |
f7d2b1ec JK |
91 | nr_dirty, |
92 | nr_io, | |
93 | nr_more_io, | |
c1955ce3 | 94 | !list_empty(&bdi->bdi_list), bdi->state); |
76f1418b MS |
95 | #undef K |
96 | ||
97 | return 0; | |
98 | } | |
99 | ||
100 | static int bdi_debug_stats_open(struct inode *inode, struct file *file) | |
101 | { | |
102 | return single_open(file, bdi_debug_stats_show, inode->i_private); | |
103 | } | |
104 | ||
105 | static const struct file_operations bdi_debug_stats_fops = { | |
106 | .open = bdi_debug_stats_open, | |
107 | .read = seq_read, | |
108 | .llseek = seq_lseek, | |
109 | .release = single_release, | |
110 | }; | |
111 | ||
112 | static void bdi_debug_register(struct backing_dev_info *bdi, const char *name) | |
113 | { | |
114 | bdi->debug_dir = debugfs_create_dir(name, bdi_debug_root); | |
115 | bdi->debug_stats = debugfs_create_file("stats", 0444, bdi->debug_dir, | |
116 | bdi, &bdi_debug_stats_fops); | |
117 | } | |
118 | ||
119 | static void bdi_debug_unregister(struct backing_dev_info *bdi) | |
120 | { | |
121 | debugfs_remove(bdi->debug_stats); | |
122 | debugfs_remove(bdi->debug_dir); | |
123 | } | |
124 | #else | |
125 | static inline void bdi_debug_init(void) | |
126 | { | |
127 | } | |
128 | static inline void bdi_debug_register(struct backing_dev_info *bdi, | |
129 | const char *name) | |
130 | { | |
131 | } | |
132 | static inline void bdi_debug_unregister(struct backing_dev_info *bdi) | |
133 | { | |
134 | } | |
135 | #endif | |
136 | ||
cf0ca9fe PZ |
137 | static ssize_t read_ahead_kb_store(struct device *dev, |
138 | struct device_attribute *attr, | |
139 | const char *buf, size_t count) | |
140 | { | |
141 | struct backing_dev_info *bdi = dev_get_drvdata(dev); | |
cf0ca9fe | 142 | unsigned long read_ahead_kb; |
7034ed13 | 143 | ssize_t ret; |
cf0ca9fe | 144 | |
7034ed13 NJ |
145 | ret = kstrtoul(buf, 10, &read_ahead_kb); |
146 | if (ret < 0) | |
147 | return ret; | |
148 | ||
149 | bdi->ra_pages = read_ahead_kb >> (PAGE_SHIFT - 10); | |
150 | ||
151 | return count; | |
cf0ca9fe PZ |
152 | } |
153 | ||
154 | #define K(pages) ((pages) << (PAGE_SHIFT - 10)) | |
155 | ||
156 | #define BDI_SHOW(name, expr) \ | |
157 | static ssize_t name##_show(struct device *dev, \ | |
158 | struct device_attribute *attr, char *page) \ | |
159 | { \ | |
160 | struct backing_dev_info *bdi = dev_get_drvdata(dev); \ | |
161 | \ | |
162 | return snprintf(page, PAGE_SIZE-1, "%lld\n", (long long)expr); \ | |
d9e1241e GKH |
163 | } \ |
164 | static DEVICE_ATTR_RW(name); | |
cf0ca9fe PZ |
165 | |
166 | BDI_SHOW(read_ahead_kb, K(bdi->ra_pages)) | |
167 | ||
189d3c4a PZ |
168 | static ssize_t min_ratio_store(struct device *dev, |
169 | struct device_attribute *attr, const char *buf, size_t count) | |
170 | { | |
171 | struct backing_dev_info *bdi = dev_get_drvdata(dev); | |
189d3c4a | 172 | unsigned int ratio; |
7034ed13 NJ |
173 | ssize_t ret; |
174 | ||
175 | ret = kstrtouint(buf, 10, &ratio); | |
176 | if (ret < 0) | |
177 | return ret; | |
178 | ||
179 | ret = bdi_set_min_ratio(bdi, ratio); | |
180 | if (!ret) | |
181 | ret = count; | |
189d3c4a | 182 | |
189d3c4a PZ |
183 | return ret; |
184 | } | |
185 | BDI_SHOW(min_ratio, bdi->min_ratio) | |
186 | ||
a42dde04 PZ |
187 | static ssize_t max_ratio_store(struct device *dev, |
188 | struct device_attribute *attr, const char *buf, size_t count) | |
189 | { | |
190 | struct backing_dev_info *bdi = dev_get_drvdata(dev); | |
a42dde04 | 191 | unsigned int ratio; |
7034ed13 NJ |
192 | ssize_t ret; |
193 | ||
194 | ret = kstrtouint(buf, 10, &ratio); | |
195 | if (ret < 0) | |
196 | return ret; | |
197 | ||
198 | ret = bdi_set_max_ratio(bdi, ratio); | |
199 | if (!ret) | |
200 | ret = count; | |
a42dde04 | 201 | |
a42dde04 PZ |
202 | return ret; |
203 | } | |
204 | BDI_SHOW(max_ratio, bdi->max_ratio) | |
205 | ||
7d311cda DW |
206 | static ssize_t stable_pages_required_show(struct device *dev, |
207 | struct device_attribute *attr, | |
208 | char *page) | |
209 | { | |
210 | struct backing_dev_info *bdi = dev_get_drvdata(dev); | |
211 | ||
212 | return snprintf(page, PAGE_SIZE-1, "%d\n", | |
213 | bdi_cap_stable_pages_required(bdi) ? 1 : 0); | |
214 | } | |
d9e1241e GKH |
215 | static DEVICE_ATTR_RO(stable_pages_required); |
216 | ||
217 | static struct attribute *bdi_dev_attrs[] = { | |
218 | &dev_attr_read_ahead_kb.attr, | |
219 | &dev_attr_min_ratio.attr, | |
220 | &dev_attr_max_ratio.attr, | |
221 | &dev_attr_stable_pages_required.attr, | |
222 | NULL, | |
cf0ca9fe | 223 | }; |
d9e1241e | 224 | ATTRIBUTE_GROUPS(bdi_dev); |
cf0ca9fe PZ |
225 | |
226 | static __init int bdi_class_init(void) | |
227 | { | |
228 | bdi_class = class_create(THIS_MODULE, "bdi"); | |
14421453 AB |
229 | if (IS_ERR(bdi_class)) |
230 | return PTR_ERR(bdi_class); | |
231 | ||
d9e1241e | 232 | bdi_class->dev_groups = bdi_dev_groups; |
76f1418b | 233 | bdi_debug_init(); |
cf0ca9fe PZ |
234 | return 0; |
235 | } | |
76f1418b | 236 | postcore_initcall(bdi_class_init); |
cf0ca9fe | 237 | |
26160158 JA |
238 | static int __init default_bdi_init(void) |
239 | { | |
240 | int err; | |
241 | ||
839a8e86 | 242 | bdi_wq = alloc_workqueue("writeback", WQ_MEM_RECLAIM | WQ_FREEZABLE | |
b5c872dd | 243 | WQ_UNBOUND | WQ_SYSFS, 0); |
839a8e86 TH |
244 | if (!bdi_wq) |
245 | return -ENOMEM; | |
246 | ||
976e48f8 | 247 | err = bdi_init(&noop_backing_dev_info); |
26160158 JA |
248 | |
249 | return err; | |
250 | } | |
251 | subsys_initcall(default_bdi_init); | |
252 | ||
03ba3782 JA |
253 | int bdi_has_dirty_io(struct backing_dev_info *bdi) |
254 | { | |
255 | return wb_has_dirty_io(&bdi->wb); | |
256 | } | |
257 | ||
6467716a AB |
258 | /* |
259 | * This function is used when the first inode for this bdi is marked dirty. It | |
260 | * wakes-up the corresponding bdi thread which should then take care of the | |
261 | * periodic background write-out of dirty inodes. Since the write-out would | |
262 | * starts only 'dirty_writeback_interval' centisecs from now anyway, we just | |
263 | * set up a timer which wakes the bdi thread up later. | |
264 | * | |
265 | * Note, we wouldn't bother setting up the timer, but this function is on the | |
266 | * fast-path (used by '__mark_inode_dirty()'), so we save few context switches | |
267 | * by delaying the wake-up. | |
6ca738d6 DB |
268 | * |
269 | * We have to be careful not to postpone flush work if it is scheduled for | |
270 | * earlier. Thus we use queue_delayed_work(). | |
6467716a AB |
271 | */ |
272 | void bdi_wakeup_thread_delayed(struct backing_dev_info *bdi) | |
273 | { | |
274 | unsigned long timeout; | |
275 | ||
276 | timeout = msecs_to_jiffies(dirty_writeback_interval * 10); | |
5acda9d1 JK |
277 | spin_lock_bh(&bdi->wb_lock); |
278 | if (test_bit(BDI_registered, &bdi->state)) | |
279 | queue_delayed_work(bdi_wq, &bdi->wb.dwork, timeout); | |
280 | spin_unlock_bh(&bdi->wb_lock); | |
03ba3782 JA |
281 | } |
282 | ||
cfc4ba53 JA |
283 | /* |
284 | * Remove bdi from bdi_list, and ensure that it is no longer visible | |
285 | */ | |
286 | static void bdi_remove_from_list(struct backing_dev_info *bdi) | |
287 | { | |
288 | spin_lock_bh(&bdi_lock); | |
289 | list_del_rcu(&bdi->bdi_list); | |
290 | spin_unlock_bh(&bdi_lock); | |
291 | ||
ef323088 | 292 | synchronize_rcu_expedited(); |
cfc4ba53 JA |
293 | } |
294 | ||
cf0ca9fe PZ |
295 | int bdi_register(struct backing_dev_info *bdi, struct device *parent, |
296 | const char *fmt, ...) | |
297 | { | |
cf0ca9fe | 298 | va_list args; |
cf0ca9fe PZ |
299 | struct device *dev; |
300 | ||
69fc208b | 301 | if (bdi->dev) /* The driver needs to use separate queues per device */ |
c284de61 | 302 | return 0; |
f1d0b063 | 303 | |
cf0ca9fe | 304 | va_start(args, fmt); |
19051c50 | 305 | dev = device_create_vargs(bdi_class, parent, MKDEV(0, 0), bdi, fmt, args); |
cf0ca9fe | 306 | va_end(args); |
c284de61 AB |
307 | if (IS_ERR(dev)) |
308 | return PTR_ERR(dev); | |
66f3b8e2 | 309 | |
cf0ca9fe | 310 | bdi->dev = dev; |
cf0ca9fe | 311 | |
03ba3782 | 312 | bdi_debug_register(bdi, dev_name(dev)); |
500b067c | 313 | set_bit(BDI_registered, &bdi->state); |
c284de61 AB |
314 | |
315 | spin_lock_bh(&bdi_lock); | |
316 | list_add_tail_rcu(&bdi->bdi_list, &bdi_list); | |
317 | spin_unlock_bh(&bdi_lock); | |
318 | ||
455b2864 | 319 | trace_writeback_bdi_register(bdi); |
c284de61 | 320 | return 0; |
cf0ca9fe PZ |
321 | } |
322 | EXPORT_SYMBOL(bdi_register); | |
323 | ||
324 | int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev) | |
325 | { | |
326 | return bdi_register(bdi, NULL, "%u:%u", MAJOR(dev), MINOR(dev)); | |
327 | } | |
328 | EXPORT_SYMBOL(bdi_register_dev); | |
329 | ||
03ba3782 JA |
330 | /* |
331 | * Remove bdi from the global list and shutdown any threads we have running | |
332 | */ | |
333 | static void bdi_wb_shutdown(struct backing_dev_info *bdi) | |
66f3b8e2 | 334 | { |
c4db59d3 CH |
335 | /* Make sure nobody queues further work */ |
336 | spin_lock_bh(&bdi->wb_lock); | |
337 | if (!test_and_clear_bit(BDI_registered, &bdi->state)) { | |
338 | spin_unlock_bh(&bdi->wb_lock); | |
03ba3782 | 339 | return; |
c4db59d3 CH |
340 | } |
341 | spin_unlock_bh(&bdi->wb_lock); | |
03ba3782 JA |
342 | |
343 | /* | |
fff5b85a | 344 | * Make sure nobody finds us on the bdi_list anymore |
03ba3782 | 345 | */ |
fff5b85a | 346 | bdi_remove_from_list(bdi); |
03ba3782 JA |
347 | |
348 | /* | |
839a8e86 TH |
349 | * Drain work list and shutdown the delayed_work. At this point, |
350 | * @bdi->bdi_list is empty telling bdi_Writeback_workfn() that @bdi | |
351 | * is dying and its work_list needs to be drained no matter what. | |
03ba3782 | 352 | */ |
839a8e86 TH |
353 | mod_delayed_work(bdi_wq, &bdi->wb.dwork, 0); |
354 | flush_delayed_work(&bdi->wb.dwork); | |
66f3b8e2 JA |
355 | } |
356 | ||
592b09a4 | 357 | /* |
c4db59d3 CH |
358 | * Called when the device behind @bdi has been removed or ejected. |
359 | * | |
360 | * We can't really do much here except for reducing the dirty ratio at | |
361 | * the moment. In the future we should be able to set a flag so that | |
362 | * the filesystem can handle errors at mark_inode_dirty time instead | |
363 | * of only at writeback time. | |
592b09a4 | 364 | */ |
cf0ca9fe PZ |
365 | void bdi_unregister(struct backing_dev_info *bdi) |
366 | { | |
c4db59d3 CH |
367 | if (WARN_ON_ONCE(!bdi->dev)) |
368 | return; | |
8c4db335 | 369 | |
c4db59d3 | 370 | bdi_set_min_ratio(bdi, 0); |
cf0ca9fe PZ |
371 | } |
372 | EXPORT_SYMBOL(bdi_unregister); | |
3fcfab16 | 373 | |
6467716a AB |
374 | static void bdi_wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi) |
375 | { | |
376 | memset(wb, 0, sizeof(*wb)); | |
377 | ||
378 | wb->bdi = bdi; | |
379 | wb->last_old_flush = jiffies; | |
380 | INIT_LIST_HEAD(&wb->b_dirty); | |
381 | INIT_LIST_HEAD(&wb->b_io); | |
382 | INIT_LIST_HEAD(&wb->b_more_io); | |
f758eeab | 383 | spin_lock_init(&wb->list_lock); |
839a8e86 | 384 | INIT_DELAYED_WORK(&wb->dwork, bdi_writeback_workfn); |
6467716a AB |
385 | } |
386 | ||
e98be2d5 WF |
387 | /* |
388 | * Initial write bandwidth: 100 MB/s | |
389 | */ | |
390 | #define INIT_BW (100 << (20 - PAGE_SHIFT)) | |
391 | ||
b2e8fb6e PZ |
392 | int bdi_init(struct backing_dev_info *bdi) |
393 | { | |
03ba3782 | 394 | int i, err; |
b2e8fb6e | 395 | |
cf0ca9fe PZ |
396 | bdi->dev = NULL; |
397 | ||
189d3c4a | 398 | bdi->min_ratio = 0; |
a42dde04 | 399 | bdi->max_ratio = 100; |
eb608e3a | 400 | bdi->max_prop_frac = FPROP_FRAC_BASE; |
03ba3782 | 401 | spin_lock_init(&bdi->wb_lock); |
66f3b8e2 | 402 | INIT_LIST_HEAD(&bdi->bdi_list); |
03ba3782 JA |
403 | INIT_LIST_HEAD(&bdi->work_list); |
404 | ||
405 | bdi_wb_init(&bdi->wb, bdi); | |
406 | ||
b2e8fb6e | 407 | for (i = 0; i < NR_BDI_STAT_ITEMS; i++) { |
908c7f19 | 408 | err = percpu_counter_init(&bdi->bdi_stat[i], 0, GFP_KERNEL); |
04fbfdc1 PZ |
409 | if (err) |
410 | goto err; | |
411 | } | |
412 | ||
413 | bdi->dirty_exceeded = 0; | |
e98be2d5 WF |
414 | |
415 | bdi->bw_time_stamp = jiffies; | |
416 | bdi->written_stamp = 0; | |
417 | ||
7381131c | 418 | bdi->balanced_dirty_ratelimit = INIT_BW; |
be3ffa27 | 419 | bdi->dirty_ratelimit = INIT_BW; |
e98be2d5 WF |
420 | bdi->write_bandwidth = INIT_BW; |
421 | bdi->avg_write_bandwidth = INIT_BW; | |
422 | ||
20ae0079 | 423 | err = fprop_local_init_percpu(&bdi->completions, GFP_KERNEL); |
04fbfdc1 PZ |
424 | |
425 | if (err) { | |
426 | err: | |
4b01a0b1 | 427 | while (i--) |
04fbfdc1 | 428 | percpu_counter_destroy(&bdi->bdi_stat[i]); |
b2e8fb6e PZ |
429 | } |
430 | ||
431 | return err; | |
432 | } | |
433 | EXPORT_SYMBOL(bdi_init); | |
434 | ||
435 | void bdi_destroy(struct backing_dev_info *bdi) | |
436 | { | |
437 | int i; | |
438 | ||
c4db59d3 | 439 | bdi_wb_shutdown(bdi); |
cf0ca9fe | 440 | |
c4db59d3 | 441 | WARN_ON(!list_empty(&bdi->work_list)); |
c0ea1c22 | 442 | WARN_ON(delayed_work_pending(&bdi->wb.dwork)); |
7a401a97 | 443 | |
c4db59d3 CH |
444 | if (bdi->dev) { |
445 | bdi_debug_unregister(bdi); | |
446 | device_unregister(bdi->dev); | |
447 | bdi->dev = NULL; | |
448 | } | |
449 | ||
b2e8fb6e PZ |
450 | for (i = 0; i < NR_BDI_STAT_ITEMS; i++) |
451 | percpu_counter_destroy(&bdi->bdi_stat[i]); | |
eb608e3a | 452 | fprop_local_destroy_percpu(&bdi->completions); |
b2e8fb6e PZ |
453 | } |
454 | EXPORT_SYMBOL(bdi_destroy); | |
455 | ||
c3c53206 JA |
456 | /* |
457 | * For use from filesystems to quickly init and register a bdi associated | |
458 | * with dirty writeback | |
459 | */ | |
b4caecd4 | 460 | int bdi_setup_and_register(struct backing_dev_info *bdi, char *name) |
c3c53206 | 461 | { |
c3c53206 JA |
462 | int err; |
463 | ||
464 | bdi->name = name; | |
b4caecd4 | 465 | bdi->capabilities = 0; |
c3c53206 JA |
466 | err = bdi_init(bdi); |
467 | if (err) | |
468 | return err; | |
469 | ||
02aa2a37 KC |
470 | err = bdi_register(bdi, NULL, "%.28s-%ld", name, |
471 | atomic_long_inc_return(&bdi_seq)); | |
c3c53206 JA |
472 | if (err) { |
473 | bdi_destroy(bdi); | |
474 | return err; | |
475 | } | |
476 | ||
477 | return 0; | |
478 | } | |
479 | EXPORT_SYMBOL(bdi_setup_and_register); | |
480 | ||
3fcfab16 AM |
481 | static wait_queue_head_t congestion_wqh[2] = { |
482 | __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]), | |
483 | __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1]) | |
484 | }; | |
0e093d99 | 485 | static atomic_t nr_bdi_congested[2]; |
3fcfab16 | 486 | |
1faa16d2 | 487 | void clear_bdi_congested(struct backing_dev_info *bdi, int sync) |
3fcfab16 AM |
488 | { |
489 | enum bdi_state bit; | |
1faa16d2 | 490 | wait_queue_head_t *wqh = &congestion_wqh[sync]; |
3fcfab16 | 491 | |
1faa16d2 | 492 | bit = sync ? BDI_sync_congested : BDI_async_congested; |
0e093d99 MG |
493 | if (test_and_clear_bit(bit, &bdi->state)) |
494 | atomic_dec(&nr_bdi_congested[sync]); | |
4e857c58 | 495 | smp_mb__after_atomic(); |
3fcfab16 AM |
496 | if (waitqueue_active(wqh)) |
497 | wake_up(wqh); | |
498 | } | |
499 | EXPORT_SYMBOL(clear_bdi_congested); | |
500 | ||
1faa16d2 | 501 | void set_bdi_congested(struct backing_dev_info *bdi, int sync) |
3fcfab16 AM |
502 | { |
503 | enum bdi_state bit; | |
504 | ||
1faa16d2 | 505 | bit = sync ? BDI_sync_congested : BDI_async_congested; |
0e093d99 MG |
506 | if (!test_and_set_bit(bit, &bdi->state)) |
507 | atomic_inc(&nr_bdi_congested[sync]); | |
3fcfab16 AM |
508 | } |
509 | EXPORT_SYMBOL(set_bdi_congested); | |
510 | ||
511 | /** | |
512 | * congestion_wait - wait for a backing_dev to become uncongested | |
8aa7e847 | 513 | * @sync: SYNC or ASYNC IO |
3fcfab16 AM |
514 | * @timeout: timeout in jiffies |
515 | * | |
516 | * Waits for up to @timeout jiffies for a backing_dev (any backing_dev) to exit | |
517 | * write congestion. If no backing_devs are congested then just wait for the | |
518 | * next write to be completed. | |
519 | */ | |
8aa7e847 | 520 | long congestion_wait(int sync, long timeout) |
3fcfab16 AM |
521 | { |
522 | long ret; | |
52bb9198 | 523 | unsigned long start = jiffies; |
3fcfab16 | 524 | DEFINE_WAIT(wait); |
8aa7e847 | 525 | wait_queue_head_t *wqh = &congestion_wqh[sync]; |
3fcfab16 AM |
526 | |
527 | prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); | |
528 | ret = io_schedule_timeout(timeout); | |
529 | finish_wait(wqh, &wait); | |
52bb9198 MG |
530 | |
531 | trace_writeback_congestion_wait(jiffies_to_usecs(timeout), | |
532 | jiffies_to_usecs(jiffies - start)); | |
533 | ||
3fcfab16 AM |
534 | return ret; |
535 | } | |
536 | EXPORT_SYMBOL(congestion_wait); | |
04fbfdc1 | 537 | |
0e093d99 MG |
538 | /** |
539 | * wait_iff_congested - Conditionally wait for a backing_dev to become uncongested or a zone to complete writes | |
540 | * @zone: A zone to check if it is heavily congested | |
541 | * @sync: SYNC or ASYNC IO | |
542 | * @timeout: timeout in jiffies | |
543 | * | |
544 | * In the event of a congested backing_dev (any backing_dev) and the given | |
545 | * @zone has experienced recent congestion, this waits for up to @timeout | |
546 | * jiffies for either a BDI to exit congestion of the given @sync queue | |
547 | * or a write to complete. | |
548 | * | |
25985edc | 549 | * In the absence of zone congestion, cond_resched() is called to yield |
0e093d99 MG |
550 | * the processor if necessary but otherwise does not sleep. |
551 | * | |
552 | * The return value is 0 if the sleep is for the full timeout. Otherwise, | |
553 | * it is the number of jiffies that were still remaining when the function | |
554 | * returned. return_value == timeout implies the function did not sleep. | |
555 | */ | |
556 | long wait_iff_congested(struct zone *zone, int sync, long timeout) | |
557 | { | |
558 | long ret; | |
559 | unsigned long start = jiffies; | |
560 | DEFINE_WAIT(wait); | |
561 | wait_queue_head_t *wqh = &congestion_wqh[sync]; | |
562 | ||
563 | /* | |
564 | * If there is no congestion, or heavy congestion is not being | |
565 | * encountered in the current zone, yield if necessary instead | |
566 | * of sleeping on the congestion queue | |
567 | */ | |
568 | if (atomic_read(&nr_bdi_congested[sync]) == 0 || | |
57054651 | 569 | !test_bit(ZONE_CONGESTED, &zone->flags)) { |
0e093d99 MG |
570 | cond_resched(); |
571 | ||
572 | /* In case we scheduled, work out time remaining */ | |
573 | ret = timeout - (jiffies - start); | |
574 | if (ret < 0) | |
575 | ret = 0; | |
576 | ||
577 | goto out; | |
578 | } | |
579 | ||
580 | /* Sleep until uncongested or a write happens */ | |
581 | prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); | |
582 | ret = io_schedule_timeout(timeout); | |
583 | finish_wait(wqh, &wait); | |
584 | ||
585 | out: | |
586 | trace_writeback_wait_iff_congested(jiffies_to_usecs(timeout), | |
587 | jiffies_to_usecs(jiffies - start)); | |
588 | ||
589 | return ret; | |
590 | } | |
591 | EXPORT_SYMBOL(wait_iff_congested); | |
3965c9ae WL |
592 | |
593 | int pdflush_proc_obsolete(struct ctl_table *table, int write, | |
594 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
595 | { | |
596 | char kbuf[] = "0\n"; | |
597 | ||
4c3bffc2 | 598 | if (*ppos || *lenp < sizeof(kbuf)) { |
3965c9ae WL |
599 | *lenp = 0; |
600 | return 0; | |
601 | } | |
602 | ||
603 | if (copy_to_user(buffer, kbuf, sizeof(kbuf))) | |
604 | return -EFAULT; | |
605 | printk_once(KERN_WARNING "%s exported in /proc is scheduled for removal\n", | |
606 | table->procname); | |
607 | ||
608 | *lenp = 2; | |
609 | *ppos += *lenp; | |
610 | return 2; | |
611 | } |