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 | ||
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; | |
0ae45f63 | 52 | unsigned long nr_dirty, nr_io, nr_more_io, nr_dirty_time; |
f09b00d3 JA |
53 | struct inode *inode; |
54 | ||
0ae45f63 | 55 | nr_dirty = nr_io = nr_more_io = nr_dirty_time = 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++; |
0ae45f63 TT |
63 | list_for_each_entry(inode, &wb->b_dirty_time, i_wb_list) |
64 | if (inode->i_state & I_DIRTY_TIME) | |
65 | nr_dirty_time++; | |
f758eeab | 66 | spin_unlock(&wb->list_lock); |
76f1418b | 67 | |
16c4042f WF |
68 | global_dirty_limits(&background_thresh, &dirty_thresh); |
69 | bdi_thresh = bdi_dirty_limit(bdi, dirty_thresh); | |
76f1418b MS |
70 | |
71 | #define K(x) ((x) << (PAGE_SHIFT - 10)) | |
72 | seq_printf(m, | |
00821b00 WF |
73 | "BdiWriteback: %10lu kB\n" |
74 | "BdiReclaimable: %10lu kB\n" | |
75 | "BdiDirtyThresh: %10lu kB\n" | |
76 | "DirtyThresh: %10lu kB\n" | |
77 | "BackgroundThresh: %10lu kB\n" | |
c8e28ce0 | 78 | "BdiDirtied: %10lu kB\n" |
00821b00 WF |
79 | "BdiWritten: %10lu kB\n" |
80 | "BdiWriteBandwidth: %10lu kBps\n" | |
81 | "b_dirty: %10lu\n" | |
82 | "b_io: %10lu\n" | |
83 | "b_more_io: %10lu\n" | |
0ae45f63 | 84 | "b_dirty_time: %10lu\n" |
00821b00 WF |
85 | "bdi_list: %10u\n" |
86 | "state: %10lx\n", | |
76f1418b MS |
87 | (unsigned long) K(bdi_stat(bdi, BDI_WRITEBACK)), |
88 | (unsigned long) K(bdi_stat(bdi, BDI_RECLAIMABLE)), | |
f7d2b1ec JK |
89 | K(bdi_thresh), |
90 | K(dirty_thresh), | |
91 | K(background_thresh), | |
c8e28ce0 | 92 | (unsigned long) K(bdi_stat(bdi, BDI_DIRTIED)), |
f7d2b1ec | 93 | (unsigned long) K(bdi_stat(bdi, BDI_WRITTEN)), |
00821b00 | 94 | (unsigned long) K(bdi->write_bandwidth), |
f7d2b1ec JK |
95 | nr_dirty, |
96 | nr_io, | |
97 | nr_more_io, | |
0ae45f63 | 98 | nr_dirty_time, |
c1955ce3 | 99 | !list_empty(&bdi->bdi_list), bdi->state); |
76f1418b MS |
100 | #undef K |
101 | ||
102 | return 0; | |
103 | } | |
104 | ||
105 | static int bdi_debug_stats_open(struct inode *inode, struct file *file) | |
106 | { | |
107 | return single_open(file, bdi_debug_stats_show, inode->i_private); | |
108 | } | |
109 | ||
110 | static const struct file_operations bdi_debug_stats_fops = { | |
111 | .open = bdi_debug_stats_open, | |
112 | .read = seq_read, | |
113 | .llseek = seq_lseek, | |
114 | .release = single_release, | |
115 | }; | |
116 | ||
117 | static void bdi_debug_register(struct backing_dev_info *bdi, const char *name) | |
118 | { | |
119 | bdi->debug_dir = debugfs_create_dir(name, bdi_debug_root); | |
120 | bdi->debug_stats = debugfs_create_file("stats", 0444, bdi->debug_dir, | |
121 | bdi, &bdi_debug_stats_fops); | |
122 | } | |
123 | ||
124 | static void bdi_debug_unregister(struct backing_dev_info *bdi) | |
125 | { | |
126 | debugfs_remove(bdi->debug_stats); | |
127 | debugfs_remove(bdi->debug_dir); | |
128 | } | |
129 | #else | |
130 | static inline void bdi_debug_init(void) | |
131 | { | |
132 | } | |
133 | static inline void bdi_debug_register(struct backing_dev_info *bdi, | |
134 | const char *name) | |
135 | { | |
136 | } | |
137 | static inline void bdi_debug_unregister(struct backing_dev_info *bdi) | |
138 | { | |
139 | } | |
140 | #endif | |
141 | ||
cf0ca9fe PZ |
142 | static ssize_t read_ahead_kb_store(struct device *dev, |
143 | struct device_attribute *attr, | |
144 | const char *buf, size_t count) | |
145 | { | |
146 | struct backing_dev_info *bdi = dev_get_drvdata(dev); | |
cf0ca9fe | 147 | unsigned long read_ahead_kb; |
7034ed13 | 148 | ssize_t ret; |
cf0ca9fe | 149 | |
7034ed13 NJ |
150 | ret = kstrtoul(buf, 10, &read_ahead_kb); |
151 | if (ret < 0) | |
152 | return ret; | |
153 | ||
154 | bdi->ra_pages = read_ahead_kb >> (PAGE_SHIFT - 10); | |
155 | ||
156 | return count; | |
cf0ca9fe PZ |
157 | } |
158 | ||
159 | #define K(pages) ((pages) << (PAGE_SHIFT - 10)) | |
160 | ||
161 | #define BDI_SHOW(name, expr) \ | |
162 | static ssize_t name##_show(struct device *dev, \ | |
163 | struct device_attribute *attr, char *page) \ | |
164 | { \ | |
165 | struct backing_dev_info *bdi = dev_get_drvdata(dev); \ | |
166 | \ | |
167 | return snprintf(page, PAGE_SIZE-1, "%lld\n", (long long)expr); \ | |
d9e1241e GKH |
168 | } \ |
169 | static DEVICE_ATTR_RW(name); | |
cf0ca9fe PZ |
170 | |
171 | BDI_SHOW(read_ahead_kb, K(bdi->ra_pages)) | |
172 | ||
189d3c4a PZ |
173 | static ssize_t min_ratio_store(struct device *dev, |
174 | struct device_attribute *attr, const char *buf, size_t count) | |
175 | { | |
176 | struct backing_dev_info *bdi = dev_get_drvdata(dev); | |
189d3c4a | 177 | unsigned int ratio; |
7034ed13 NJ |
178 | ssize_t ret; |
179 | ||
180 | ret = kstrtouint(buf, 10, &ratio); | |
181 | if (ret < 0) | |
182 | return ret; | |
183 | ||
184 | ret = bdi_set_min_ratio(bdi, ratio); | |
185 | if (!ret) | |
186 | ret = count; | |
189d3c4a | 187 | |
189d3c4a PZ |
188 | return ret; |
189 | } | |
190 | BDI_SHOW(min_ratio, bdi->min_ratio) | |
191 | ||
a42dde04 PZ |
192 | static ssize_t max_ratio_store(struct device *dev, |
193 | struct device_attribute *attr, const char *buf, size_t count) | |
194 | { | |
195 | struct backing_dev_info *bdi = dev_get_drvdata(dev); | |
a42dde04 | 196 | unsigned int ratio; |
7034ed13 NJ |
197 | ssize_t ret; |
198 | ||
199 | ret = kstrtouint(buf, 10, &ratio); | |
200 | if (ret < 0) | |
201 | return ret; | |
202 | ||
203 | ret = bdi_set_max_ratio(bdi, ratio); | |
204 | if (!ret) | |
205 | ret = count; | |
a42dde04 | 206 | |
a42dde04 PZ |
207 | return ret; |
208 | } | |
209 | BDI_SHOW(max_ratio, bdi->max_ratio) | |
210 | ||
7d311cda DW |
211 | static ssize_t stable_pages_required_show(struct device *dev, |
212 | struct device_attribute *attr, | |
213 | char *page) | |
214 | { | |
215 | struct backing_dev_info *bdi = dev_get_drvdata(dev); | |
216 | ||
217 | return snprintf(page, PAGE_SIZE-1, "%d\n", | |
218 | bdi_cap_stable_pages_required(bdi) ? 1 : 0); | |
219 | } | |
d9e1241e GKH |
220 | static DEVICE_ATTR_RO(stable_pages_required); |
221 | ||
222 | static struct attribute *bdi_dev_attrs[] = { | |
223 | &dev_attr_read_ahead_kb.attr, | |
224 | &dev_attr_min_ratio.attr, | |
225 | &dev_attr_max_ratio.attr, | |
226 | &dev_attr_stable_pages_required.attr, | |
227 | NULL, | |
cf0ca9fe | 228 | }; |
d9e1241e | 229 | ATTRIBUTE_GROUPS(bdi_dev); |
cf0ca9fe PZ |
230 | |
231 | static __init int bdi_class_init(void) | |
232 | { | |
233 | bdi_class = class_create(THIS_MODULE, "bdi"); | |
14421453 AB |
234 | if (IS_ERR(bdi_class)) |
235 | return PTR_ERR(bdi_class); | |
236 | ||
d9e1241e | 237 | bdi_class->dev_groups = bdi_dev_groups; |
76f1418b | 238 | bdi_debug_init(); |
cf0ca9fe PZ |
239 | return 0; |
240 | } | |
76f1418b | 241 | postcore_initcall(bdi_class_init); |
cf0ca9fe | 242 | |
26160158 JA |
243 | static int __init default_bdi_init(void) |
244 | { | |
245 | int err; | |
246 | ||
839a8e86 | 247 | bdi_wq = alloc_workqueue("writeback", WQ_MEM_RECLAIM | WQ_FREEZABLE | |
b5c872dd | 248 | WQ_UNBOUND | WQ_SYSFS, 0); |
839a8e86 TH |
249 | if (!bdi_wq) |
250 | return -ENOMEM; | |
251 | ||
976e48f8 | 252 | err = bdi_init(&noop_backing_dev_info); |
26160158 JA |
253 | |
254 | return err; | |
255 | } | |
256 | subsys_initcall(default_bdi_init); | |
257 | ||
03ba3782 JA |
258 | int bdi_has_dirty_io(struct backing_dev_info *bdi) |
259 | { | |
260 | return wb_has_dirty_io(&bdi->wb); | |
261 | } | |
262 | ||
6467716a AB |
263 | /* |
264 | * This function is used when the first inode for this bdi is marked dirty. It | |
265 | * wakes-up the corresponding bdi thread which should then take care of the | |
266 | * periodic background write-out of dirty inodes. Since the write-out would | |
267 | * starts only 'dirty_writeback_interval' centisecs from now anyway, we just | |
268 | * set up a timer which wakes the bdi thread up later. | |
269 | * | |
270 | * Note, we wouldn't bother setting up the timer, but this function is on the | |
271 | * fast-path (used by '__mark_inode_dirty()'), so we save few context switches | |
272 | * by delaying the wake-up. | |
6ca738d6 DB |
273 | * |
274 | * We have to be careful not to postpone flush work if it is scheduled for | |
275 | * earlier. Thus we use queue_delayed_work(). | |
6467716a AB |
276 | */ |
277 | void bdi_wakeup_thread_delayed(struct backing_dev_info *bdi) | |
278 | { | |
279 | unsigned long timeout; | |
280 | ||
281 | timeout = msecs_to_jiffies(dirty_writeback_interval * 10); | |
5acda9d1 JK |
282 | spin_lock_bh(&bdi->wb_lock); |
283 | if (test_bit(BDI_registered, &bdi->state)) | |
284 | queue_delayed_work(bdi_wq, &bdi->wb.dwork, timeout); | |
285 | spin_unlock_bh(&bdi->wb_lock); | |
03ba3782 JA |
286 | } |
287 | ||
cfc4ba53 JA |
288 | /* |
289 | * Remove bdi from bdi_list, and ensure that it is no longer visible | |
290 | */ | |
291 | static void bdi_remove_from_list(struct backing_dev_info *bdi) | |
292 | { | |
293 | spin_lock_bh(&bdi_lock); | |
294 | list_del_rcu(&bdi->bdi_list); | |
295 | spin_unlock_bh(&bdi_lock); | |
296 | ||
ef323088 | 297 | synchronize_rcu_expedited(); |
cfc4ba53 JA |
298 | } |
299 | ||
cf0ca9fe PZ |
300 | int bdi_register(struct backing_dev_info *bdi, struct device *parent, |
301 | const char *fmt, ...) | |
302 | { | |
cf0ca9fe | 303 | va_list args; |
cf0ca9fe PZ |
304 | struct device *dev; |
305 | ||
69fc208b | 306 | if (bdi->dev) /* The driver needs to use separate queues per device */ |
c284de61 | 307 | return 0; |
f1d0b063 | 308 | |
cf0ca9fe | 309 | va_start(args, fmt); |
19051c50 | 310 | dev = device_create_vargs(bdi_class, parent, MKDEV(0, 0), bdi, fmt, args); |
cf0ca9fe | 311 | va_end(args); |
c284de61 AB |
312 | if (IS_ERR(dev)) |
313 | return PTR_ERR(dev); | |
66f3b8e2 | 314 | |
cf0ca9fe | 315 | bdi->dev = dev; |
cf0ca9fe | 316 | |
03ba3782 | 317 | bdi_debug_register(bdi, dev_name(dev)); |
500b067c | 318 | set_bit(BDI_registered, &bdi->state); |
c284de61 AB |
319 | |
320 | spin_lock_bh(&bdi_lock); | |
321 | list_add_tail_rcu(&bdi->bdi_list, &bdi_list); | |
322 | spin_unlock_bh(&bdi_lock); | |
323 | ||
455b2864 | 324 | trace_writeback_bdi_register(bdi); |
c284de61 | 325 | return 0; |
cf0ca9fe PZ |
326 | } |
327 | EXPORT_SYMBOL(bdi_register); | |
328 | ||
329 | int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev) | |
330 | { | |
331 | return bdi_register(bdi, NULL, "%u:%u", MAJOR(dev), MINOR(dev)); | |
332 | } | |
333 | EXPORT_SYMBOL(bdi_register_dev); | |
334 | ||
03ba3782 JA |
335 | /* |
336 | * Remove bdi from the global list and shutdown any threads we have running | |
337 | */ | |
338 | static void bdi_wb_shutdown(struct backing_dev_info *bdi) | |
66f3b8e2 | 339 | { |
c4db59d3 CH |
340 | /* Make sure nobody queues further work */ |
341 | spin_lock_bh(&bdi->wb_lock); | |
342 | if (!test_and_clear_bit(BDI_registered, &bdi->state)) { | |
343 | spin_unlock_bh(&bdi->wb_lock); | |
03ba3782 | 344 | return; |
c4db59d3 CH |
345 | } |
346 | spin_unlock_bh(&bdi->wb_lock); | |
03ba3782 JA |
347 | |
348 | /* | |
fff5b85a | 349 | * Make sure nobody finds us on the bdi_list anymore |
03ba3782 | 350 | */ |
fff5b85a | 351 | bdi_remove_from_list(bdi); |
03ba3782 JA |
352 | |
353 | /* | |
839a8e86 TH |
354 | * Drain work list and shutdown the delayed_work. At this point, |
355 | * @bdi->bdi_list is empty telling bdi_Writeback_workfn() that @bdi | |
356 | * is dying and its work_list needs to be drained no matter what. | |
03ba3782 | 357 | */ |
839a8e86 TH |
358 | mod_delayed_work(bdi_wq, &bdi->wb.dwork, 0); |
359 | flush_delayed_work(&bdi->wb.dwork); | |
66f3b8e2 JA |
360 | } |
361 | ||
592b09a4 | 362 | /* |
c4db59d3 CH |
363 | * Called when the device behind @bdi has been removed or ejected. |
364 | * | |
365 | * We can't really do much here except for reducing the dirty ratio at | |
366 | * the moment. In the future we should be able to set a flag so that | |
367 | * the filesystem can handle errors at mark_inode_dirty time instead | |
368 | * of only at writeback time. | |
592b09a4 | 369 | */ |
cf0ca9fe PZ |
370 | void bdi_unregister(struct backing_dev_info *bdi) |
371 | { | |
c4db59d3 CH |
372 | if (WARN_ON_ONCE(!bdi->dev)) |
373 | return; | |
8c4db335 | 374 | |
c4db59d3 | 375 | bdi_set_min_ratio(bdi, 0); |
cf0ca9fe PZ |
376 | } |
377 | EXPORT_SYMBOL(bdi_unregister); | |
3fcfab16 | 378 | |
6467716a AB |
379 | static void bdi_wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi) |
380 | { | |
381 | memset(wb, 0, sizeof(*wb)); | |
382 | ||
383 | wb->bdi = bdi; | |
384 | wb->last_old_flush = jiffies; | |
385 | INIT_LIST_HEAD(&wb->b_dirty); | |
386 | INIT_LIST_HEAD(&wb->b_io); | |
387 | INIT_LIST_HEAD(&wb->b_more_io); | |
0ae45f63 | 388 | INIT_LIST_HEAD(&wb->b_dirty_time); |
f758eeab | 389 | spin_lock_init(&wb->list_lock); |
839a8e86 | 390 | INIT_DELAYED_WORK(&wb->dwork, bdi_writeback_workfn); |
6467716a AB |
391 | } |
392 | ||
e98be2d5 WF |
393 | /* |
394 | * Initial write bandwidth: 100 MB/s | |
395 | */ | |
396 | #define INIT_BW (100 << (20 - PAGE_SHIFT)) | |
397 | ||
b2e8fb6e PZ |
398 | int bdi_init(struct backing_dev_info *bdi) |
399 | { | |
03ba3782 | 400 | int i, err; |
b2e8fb6e | 401 | |
cf0ca9fe PZ |
402 | bdi->dev = NULL; |
403 | ||
189d3c4a | 404 | bdi->min_ratio = 0; |
a42dde04 | 405 | bdi->max_ratio = 100; |
eb608e3a | 406 | bdi->max_prop_frac = FPROP_FRAC_BASE; |
03ba3782 | 407 | spin_lock_init(&bdi->wb_lock); |
66f3b8e2 | 408 | INIT_LIST_HEAD(&bdi->bdi_list); |
03ba3782 JA |
409 | INIT_LIST_HEAD(&bdi->work_list); |
410 | ||
411 | bdi_wb_init(&bdi->wb, bdi); | |
412 | ||
b2e8fb6e | 413 | for (i = 0; i < NR_BDI_STAT_ITEMS; i++) { |
908c7f19 | 414 | err = percpu_counter_init(&bdi->bdi_stat[i], 0, GFP_KERNEL); |
04fbfdc1 PZ |
415 | if (err) |
416 | goto err; | |
417 | } | |
418 | ||
419 | bdi->dirty_exceeded = 0; | |
e98be2d5 WF |
420 | |
421 | bdi->bw_time_stamp = jiffies; | |
422 | bdi->written_stamp = 0; | |
423 | ||
7381131c | 424 | bdi->balanced_dirty_ratelimit = INIT_BW; |
be3ffa27 | 425 | bdi->dirty_ratelimit = INIT_BW; |
e98be2d5 WF |
426 | bdi->write_bandwidth = INIT_BW; |
427 | bdi->avg_write_bandwidth = INIT_BW; | |
428 | ||
20ae0079 | 429 | err = fprop_local_init_percpu(&bdi->completions, GFP_KERNEL); |
04fbfdc1 PZ |
430 | |
431 | if (err) { | |
432 | err: | |
4b01a0b1 | 433 | while (i--) |
04fbfdc1 | 434 | percpu_counter_destroy(&bdi->bdi_stat[i]); |
b2e8fb6e PZ |
435 | } |
436 | ||
437 | return err; | |
438 | } | |
439 | EXPORT_SYMBOL(bdi_init); | |
440 | ||
441 | void bdi_destroy(struct backing_dev_info *bdi) | |
442 | { | |
443 | int i; | |
444 | ||
c4db59d3 | 445 | bdi_wb_shutdown(bdi); |
cf0ca9fe | 446 | |
c4db59d3 | 447 | WARN_ON(!list_empty(&bdi->work_list)); |
c0ea1c22 | 448 | WARN_ON(delayed_work_pending(&bdi->wb.dwork)); |
7a401a97 | 449 | |
c4db59d3 CH |
450 | if (bdi->dev) { |
451 | bdi_debug_unregister(bdi); | |
452 | device_unregister(bdi->dev); | |
453 | bdi->dev = NULL; | |
454 | } | |
455 | ||
b2e8fb6e PZ |
456 | for (i = 0; i < NR_BDI_STAT_ITEMS; i++) |
457 | percpu_counter_destroy(&bdi->bdi_stat[i]); | |
eb608e3a | 458 | fprop_local_destroy_percpu(&bdi->completions); |
b2e8fb6e PZ |
459 | } |
460 | EXPORT_SYMBOL(bdi_destroy); | |
461 | ||
c3c53206 JA |
462 | /* |
463 | * For use from filesystems to quickly init and register a bdi associated | |
464 | * with dirty writeback | |
465 | */ | |
b4caecd4 | 466 | int bdi_setup_and_register(struct backing_dev_info *bdi, char *name) |
c3c53206 | 467 | { |
c3c53206 JA |
468 | int err; |
469 | ||
470 | bdi->name = name; | |
b4caecd4 | 471 | bdi->capabilities = 0; |
c3c53206 JA |
472 | err = bdi_init(bdi); |
473 | if (err) | |
474 | return err; | |
475 | ||
02aa2a37 KC |
476 | err = bdi_register(bdi, NULL, "%.28s-%ld", name, |
477 | atomic_long_inc_return(&bdi_seq)); | |
c3c53206 JA |
478 | if (err) { |
479 | bdi_destroy(bdi); | |
480 | return err; | |
481 | } | |
482 | ||
483 | return 0; | |
484 | } | |
485 | EXPORT_SYMBOL(bdi_setup_and_register); | |
486 | ||
3fcfab16 AM |
487 | static wait_queue_head_t congestion_wqh[2] = { |
488 | __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]), | |
489 | __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1]) | |
490 | }; | |
0e093d99 | 491 | static atomic_t nr_bdi_congested[2]; |
3fcfab16 | 492 | |
1faa16d2 | 493 | void clear_bdi_congested(struct backing_dev_info *bdi, int sync) |
3fcfab16 AM |
494 | { |
495 | enum bdi_state bit; | |
1faa16d2 | 496 | wait_queue_head_t *wqh = &congestion_wqh[sync]; |
3fcfab16 | 497 | |
1faa16d2 | 498 | bit = sync ? BDI_sync_congested : BDI_async_congested; |
0e093d99 MG |
499 | if (test_and_clear_bit(bit, &bdi->state)) |
500 | atomic_dec(&nr_bdi_congested[sync]); | |
4e857c58 | 501 | smp_mb__after_atomic(); |
3fcfab16 AM |
502 | if (waitqueue_active(wqh)) |
503 | wake_up(wqh); | |
504 | } | |
505 | EXPORT_SYMBOL(clear_bdi_congested); | |
506 | ||
1faa16d2 | 507 | void set_bdi_congested(struct backing_dev_info *bdi, int sync) |
3fcfab16 AM |
508 | { |
509 | enum bdi_state bit; | |
510 | ||
1faa16d2 | 511 | bit = sync ? BDI_sync_congested : BDI_async_congested; |
0e093d99 MG |
512 | if (!test_and_set_bit(bit, &bdi->state)) |
513 | atomic_inc(&nr_bdi_congested[sync]); | |
3fcfab16 AM |
514 | } |
515 | EXPORT_SYMBOL(set_bdi_congested); | |
516 | ||
517 | /** | |
518 | * congestion_wait - wait for a backing_dev to become uncongested | |
8aa7e847 | 519 | * @sync: SYNC or ASYNC IO |
3fcfab16 AM |
520 | * @timeout: timeout in jiffies |
521 | * | |
522 | * Waits for up to @timeout jiffies for a backing_dev (any backing_dev) to exit | |
523 | * write congestion. If no backing_devs are congested then just wait for the | |
524 | * next write to be completed. | |
525 | */ | |
8aa7e847 | 526 | long congestion_wait(int sync, long timeout) |
3fcfab16 AM |
527 | { |
528 | long ret; | |
52bb9198 | 529 | unsigned long start = jiffies; |
3fcfab16 | 530 | DEFINE_WAIT(wait); |
8aa7e847 | 531 | wait_queue_head_t *wqh = &congestion_wqh[sync]; |
3fcfab16 AM |
532 | |
533 | prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); | |
534 | ret = io_schedule_timeout(timeout); | |
535 | finish_wait(wqh, &wait); | |
52bb9198 MG |
536 | |
537 | trace_writeback_congestion_wait(jiffies_to_usecs(timeout), | |
538 | jiffies_to_usecs(jiffies - start)); | |
539 | ||
3fcfab16 AM |
540 | return ret; |
541 | } | |
542 | EXPORT_SYMBOL(congestion_wait); | |
04fbfdc1 | 543 | |
0e093d99 MG |
544 | /** |
545 | * wait_iff_congested - Conditionally wait for a backing_dev to become uncongested or a zone to complete writes | |
546 | * @zone: A zone to check if it is heavily congested | |
547 | * @sync: SYNC or ASYNC IO | |
548 | * @timeout: timeout in jiffies | |
549 | * | |
550 | * In the event of a congested backing_dev (any backing_dev) and the given | |
551 | * @zone has experienced recent congestion, this waits for up to @timeout | |
552 | * jiffies for either a BDI to exit congestion of the given @sync queue | |
553 | * or a write to complete. | |
554 | * | |
25985edc | 555 | * In the absence of zone congestion, cond_resched() is called to yield |
0e093d99 MG |
556 | * the processor if necessary but otherwise does not sleep. |
557 | * | |
558 | * The return value is 0 if the sleep is for the full timeout. Otherwise, | |
559 | * it is the number of jiffies that were still remaining when the function | |
560 | * returned. return_value == timeout implies the function did not sleep. | |
561 | */ | |
562 | long wait_iff_congested(struct zone *zone, int sync, long timeout) | |
563 | { | |
564 | long ret; | |
565 | unsigned long start = jiffies; | |
566 | DEFINE_WAIT(wait); | |
567 | wait_queue_head_t *wqh = &congestion_wqh[sync]; | |
568 | ||
569 | /* | |
570 | * If there is no congestion, or heavy congestion is not being | |
571 | * encountered in the current zone, yield if necessary instead | |
572 | * of sleeping on the congestion queue | |
573 | */ | |
574 | if (atomic_read(&nr_bdi_congested[sync]) == 0 || | |
57054651 | 575 | !test_bit(ZONE_CONGESTED, &zone->flags)) { |
0e093d99 MG |
576 | cond_resched(); |
577 | ||
578 | /* In case we scheduled, work out time remaining */ | |
579 | ret = timeout - (jiffies - start); | |
580 | if (ret < 0) | |
581 | ret = 0; | |
582 | ||
583 | goto out; | |
584 | } | |
585 | ||
586 | /* Sleep until uncongested or a write happens */ | |
587 | prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); | |
588 | ret = io_schedule_timeout(timeout); | |
589 | finish_wait(wqh, &wait); | |
590 | ||
591 | out: | |
592 | trace_writeback_wait_iff_congested(jiffies_to_usecs(timeout), | |
593 | jiffies_to_usecs(jiffies - start)); | |
594 | ||
595 | return ret; | |
596 | } | |
597 | EXPORT_SYMBOL(wait_iff_congested); | |
3965c9ae WL |
598 | |
599 | int pdflush_proc_obsolete(struct ctl_table *table, int write, | |
600 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
601 | { | |
602 | char kbuf[] = "0\n"; | |
603 | ||
4c3bffc2 | 604 | if (*ppos || *lenp < sizeof(kbuf)) { |
3965c9ae WL |
605 | *lenp = 0; |
606 | return 0; | |
607 | } | |
608 | ||
609 | if (copy_to_user(buffer, kbuf, sizeof(kbuf))) | |
610 | return -EFAULT; | |
611 | printk_once(KERN_WARNING "%s exported in /proc is scheduled for removal\n", | |
612 | table->procname); | |
613 | ||
614 | *lenp = 2; | |
615 | *ppos += *lenp; | |
616 | return 2; | |
617 | } |