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 | |
5129a469 JE |
15 | struct backing_dev_info noop_backing_dev_info = { |
16 | .name = "noop", | |
976e48f8 | 17 | .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK, |
5129a469 | 18 | }; |
a212b105 | 19 | EXPORT_SYMBOL_GPL(noop_backing_dev_info); |
5129a469 | 20 | |
cf0ca9fe | 21 | static struct class *bdi_class; |
cfc4ba53 JA |
22 | |
23 | /* | |
181387da | 24 | * bdi_lock protects updates to bdi_list. bdi_list has RCU reader side |
cfc4ba53 JA |
25 | * locking. |
26 | */ | |
03ba3782 | 27 | DEFINE_SPINLOCK(bdi_lock); |
66f3b8e2 | 28 | LIST_HEAD(bdi_list); |
03ba3782 | 29 | |
839a8e86 TH |
30 | /* bdi_wq serves all asynchronous writeback tasks */ |
31 | struct workqueue_struct *bdi_wq; | |
32 | ||
76f1418b MS |
33 | #ifdef CONFIG_DEBUG_FS |
34 | #include <linux/debugfs.h> | |
35 | #include <linux/seq_file.h> | |
36 | ||
37 | static struct dentry *bdi_debug_root; | |
38 | ||
39 | static void bdi_debug_init(void) | |
40 | { | |
41 | bdi_debug_root = debugfs_create_dir("bdi", NULL); | |
42 | } | |
43 | ||
44 | static int bdi_debug_stats_show(struct seq_file *m, void *v) | |
45 | { | |
46 | struct backing_dev_info *bdi = m->private; | |
c1955ce3 | 47 | struct bdi_writeback *wb = &bdi->wb; |
364aeb28 DR |
48 | unsigned long background_thresh; |
49 | unsigned long dirty_thresh; | |
0d960a38 | 50 | unsigned long wb_thresh; |
0ae45f63 | 51 | unsigned long nr_dirty, nr_io, nr_more_io, nr_dirty_time; |
f09b00d3 JA |
52 | struct inode *inode; |
53 | ||
0ae45f63 | 54 | nr_dirty = nr_io = nr_more_io = nr_dirty_time = 0; |
f758eeab | 55 | spin_lock(&wb->list_lock); |
c7f54084 | 56 | list_for_each_entry(inode, &wb->b_dirty, i_io_list) |
c1955ce3 | 57 | nr_dirty++; |
c7f54084 | 58 | list_for_each_entry(inode, &wb->b_io, i_io_list) |
c1955ce3 | 59 | nr_io++; |
c7f54084 | 60 | list_for_each_entry(inode, &wb->b_more_io, i_io_list) |
c1955ce3 | 61 | nr_more_io++; |
c7f54084 | 62 | list_for_each_entry(inode, &wb->b_dirty_time, i_io_list) |
0ae45f63 TT |
63 | if (inode->i_state & I_DIRTY_TIME) |
64 | nr_dirty_time++; | |
f758eeab | 65 | spin_unlock(&wb->list_lock); |
76f1418b | 66 | |
16c4042f | 67 | global_dirty_limits(&background_thresh, &dirty_thresh); |
0d960a38 | 68 | wb_thresh = wb_calc_thresh(wb, dirty_thresh); |
76f1418b MS |
69 | |
70 | #define K(x) ((x) << (PAGE_SHIFT - 10)) | |
71 | seq_printf(m, | |
00821b00 WF |
72 | "BdiWriteback: %10lu kB\n" |
73 | "BdiReclaimable: %10lu kB\n" | |
74 | "BdiDirtyThresh: %10lu kB\n" | |
75 | "DirtyThresh: %10lu kB\n" | |
76 | "BackgroundThresh: %10lu kB\n" | |
c8e28ce0 | 77 | "BdiDirtied: %10lu kB\n" |
00821b00 WF |
78 | "BdiWritten: %10lu kB\n" |
79 | "BdiWriteBandwidth: %10lu kBps\n" | |
80 | "b_dirty: %10lu\n" | |
81 | "b_io: %10lu\n" | |
82 | "b_more_io: %10lu\n" | |
0ae45f63 | 83 | "b_dirty_time: %10lu\n" |
00821b00 WF |
84 | "bdi_list: %10u\n" |
85 | "state: %10lx\n", | |
93f78d88 TH |
86 | (unsigned long) K(wb_stat(wb, WB_WRITEBACK)), |
87 | (unsigned long) K(wb_stat(wb, WB_RECLAIMABLE)), | |
0d960a38 | 88 | K(wb_thresh), |
f7d2b1ec JK |
89 | K(dirty_thresh), |
90 | K(background_thresh), | |
93f78d88 TH |
91 | (unsigned long) K(wb_stat(wb, WB_DIRTIED)), |
92 | (unsigned long) K(wb_stat(wb, WB_WRITTEN)), | |
a88a341a | 93 | (unsigned long) K(wb->write_bandwidth), |
f7d2b1ec JK |
94 | nr_dirty, |
95 | nr_io, | |
96 | nr_more_io, | |
0ae45f63 | 97 | nr_dirty_time, |
4452226e | 98 | !list_empty(&bdi->bdi_list), bdi->wb.state); |
76f1418b MS |
99 | #undef K |
100 | ||
101 | return 0; | |
102 | } | |
5ad35093 | 103 | DEFINE_SHOW_ATTRIBUTE(bdi_debug_stats); |
76f1418b | 104 | |
97f07697 | 105 | static int bdi_debug_register(struct backing_dev_info *bdi, const char *name) |
76f1418b | 106 | { |
97f07697 | 107 | if (!bdi_debug_root) |
108 | return -ENOMEM; | |
109 | ||
76f1418b | 110 | bdi->debug_dir = debugfs_create_dir(name, bdi_debug_root); |
97f07697 | 111 | if (!bdi->debug_dir) |
112 | return -ENOMEM; | |
113 | ||
76f1418b MS |
114 | bdi->debug_stats = debugfs_create_file("stats", 0444, bdi->debug_dir, |
115 | bdi, &bdi_debug_stats_fops); | |
97f07697 | 116 | if (!bdi->debug_stats) { |
117 | debugfs_remove(bdi->debug_dir); | |
f53823c1 | 118 | bdi->debug_dir = NULL; |
97f07697 | 119 | return -ENOMEM; |
120 | } | |
121 | ||
122 | return 0; | |
76f1418b MS |
123 | } |
124 | ||
125 | static void bdi_debug_unregister(struct backing_dev_info *bdi) | |
126 | { | |
127 | debugfs_remove(bdi->debug_stats); | |
128 | debugfs_remove(bdi->debug_dir); | |
129 | } | |
130 | #else | |
131 | static inline void bdi_debug_init(void) | |
132 | { | |
133 | } | |
97f07697 | 134 | static inline int bdi_debug_register(struct backing_dev_info *bdi, |
76f1418b MS |
135 | const char *name) |
136 | { | |
97f07697 | 137 | return 0; |
76f1418b MS |
138 | } |
139 | static inline void bdi_debug_unregister(struct backing_dev_info *bdi) | |
140 | { | |
141 | } | |
142 | #endif | |
143 | ||
cf0ca9fe PZ |
144 | static ssize_t read_ahead_kb_store(struct device *dev, |
145 | struct device_attribute *attr, | |
146 | const char *buf, size_t count) | |
147 | { | |
148 | struct backing_dev_info *bdi = dev_get_drvdata(dev); | |
cf0ca9fe | 149 | unsigned long read_ahead_kb; |
7034ed13 | 150 | ssize_t ret; |
cf0ca9fe | 151 | |
7034ed13 NJ |
152 | ret = kstrtoul(buf, 10, &read_ahead_kb); |
153 | if (ret < 0) | |
154 | return ret; | |
155 | ||
156 | bdi->ra_pages = read_ahead_kb >> (PAGE_SHIFT - 10); | |
157 | ||
158 | return count; | |
cf0ca9fe PZ |
159 | } |
160 | ||
161 | #define K(pages) ((pages) << (PAGE_SHIFT - 10)) | |
162 | ||
163 | #define BDI_SHOW(name, expr) \ | |
164 | static ssize_t name##_show(struct device *dev, \ | |
165 | struct device_attribute *attr, char *page) \ | |
166 | { \ | |
167 | struct backing_dev_info *bdi = dev_get_drvdata(dev); \ | |
168 | \ | |
169 | return snprintf(page, PAGE_SIZE-1, "%lld\n", (long long)expr); \ | |
d9e1241e GKH |
170 | } \ |
171 | static DEVICE_ATTR_RW(name); | |
cf0ca9fe PZ |
172 | |
173 | BDI_SHOW(read_ahead_kb, K(bdi->ra_pages)) | |
174 | ||
189d3c4a PZ |
175 | static ssize_t min_ratio_store(struct device *dev, |
176 | struct device_attribute *attr, const char *buf, size_t count) | |
177 | { | |
178 | struct backing_dev_info *bdi = dev_get_drvdata(dev); | |
189d3c4a | 179 | unsigned int ratio; |
7034ed13 NJ |
180 | ssize_t ret; |
181 | ||
182 | ret = kstrtouint(buf, 10, &ratio); | |
183 | if (ret < 0) | |
184 | return ret; | |
185 | ||
186 | ret = bdi_set_min_ratio(bdi, ratio); | |
187 | if (!ret) | |
188 | ret = count; | |
189d3c4a | 189 | |
189d3c4a PZ |
190 | return ret; |
191 | } | |
192 | BDI_SHOW(min_ratio, bdi->min_ratio) | |
193 | ||
a42dde04 PZ |
194 | static ssize_t max_ratio_store(struct device *dev, |
195 | struct device_attribute *attr, const char *buf, size_t count) | |
196 | { | |
197 | struct backing_dev_info *bdi = dev_get_drvdata(dev); | |
a42dde04 | 198 | unsigned int ratio; |
7034ed13 NJ |
199 | ssize_t ret; |
200 | ||
201 | ret = kstrtouint(buf, 10, &ratio); | |
202 | if (ret < 0) | |
203 | return ret; | |
204 | ||
205 | ret = bdi_set_max_ratio(bdi, ratio); | |
206 | if (!ret) | |
207 | ret = count; | |
a42dde04 | 208 | |
a42dde04 PZ |
209 | return ret; |
210 | } | |
211 | BDI_SHOW(max_ratio, bdi->max_ratio) | |
212 | ||
7d311cda DW |
213 | static ssize_t stable_pages_required_show(struct device *dev, |
214 | struct device_attribute *attr, | |
215 | char *page) | |
216 | { | |
217 | struct backing_dev_info *bdi = dev_get_drvdata(dev); | |
218 | ||
219 | return snprintf(page, PAGE_SIZE-1, "%d\n", | |
220 | bdi_cap_stable_pages_required(bdi) ? 1 : 0); | |
221 | } | |
d9e1241e GKH |
222 | static DEVICE_ATTR_RO(stable_pages_required); |
223 | ||
224 | static struct attribute *bdi_dev_attrs[] = { | |
225 | &dev_attr_read_ahead_kb.attr, | |
226 | &dev_attr_min_ratio.attr, | |
227 | &dev_attr_max_ratio.attr, | |
228 | &dev_attr_stable_pages_required.attr, | |
229 | NULL, | |
cf0ca9fe | 230 | }; |
d9e1241e | 231 | ATTRIBUTE_GROUPS(bdi_dev); |
cf0ca9fe PZ |
232 | |
233 | static __init int bdi_class_init(void) | |
234 | { | |
235 | bdi_class = class_create(THIS_MODULE, "bdi"); | |
14421453 AB |
236 | if (IS_ERR(bdi_class)) |
237 | return PTR_ERR(bdi_class); | |
238 | ||
d9e1241e | 239 | bdi_class->dev_groups = bdi_dev_groups; |
76f1418b | 240 | bdi_debug_init(); |
d03f6cdc | 241 | |
cf0ca9fe PZ |
242 | return 0; |
243 | } | |
76f1418b | 244 | postcore_initcall(bdi_class_init); |
cf0ca9fe | 245 | |
2e82b84c JK |
246 | static int bdi_init(struct backing_dev_info *bdi); |
247 | ||
26160158 JA |
248 | static int __init default_bdi_init(void) |
249 | { | |
250 | int err; | |
251 | ||
839a8e86 | 252 | bdi_wq = alloc_workqueue("writeback", WQ_MEM_RECLAIM | WQ_FREEZABLE | |
b5c872dd | 253 | WQ_UNBOUND | WQ_SYSFS, 0); |
839a8e86 TH |
254 | if (!bdi_wq) |
255 | return -ENOMEM; | |
256 | ||
976e48f8 | 257 | err = bdi_init(&noop_backing_dev_info); |
26160158 JA |
258 | |
259 | return err; | |
260 | } | |
261 | subsys_initcall(default_bdi_init); | |
262 | ||
6467716a | 263 | /* |
f0054bb1 | 264 | * This function is used when the first inode for this wb is marked dirty. It |
6467716a AB |
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 | 276 | */ |
f0054bb1 | 277 | void wb_wakeup_delayed(struct bdi_writeback *wb) |
6467716a AB |
278 | { |
279 | unsigned long timeout; | |
280 | ||
281 | timeout = msecs_to_jiffies(dirty_writeback_interval * 10); | |
f0054bb1 TH |
282 | spin_lock_bh(&wb->work_lock); |
283 | if (test_bit(WB_registered, &wb->state)) | |
284 | queue_delayed_work(bdi_wq, &wb->dwork, timeout); | |
285 | spin_unlock_bh(&wb->work_lock); | |
03ba3782 JA |
286 | } |
287 | ||
cfc4ba53 | 288 | /* |
a88a341a | 289 | * Initial write bandwidth: 100 MB/s |
cfc4ba53 | 290 | */ |
a88a341a | 291 | #define INIT_BW (100 << (20 - PAGE_SHIFT)) |
cfc4ba53 | 292 | |
8395cd9f | 293 | static int wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi, |
a13f35e8 | 294 | int blkcg_id, gfp_t gfp) |
cf0ca9fe | 295 | { |
93f78d88 | 296 | int i, err; |
cf0ca9fe | 297 | |
6467716a | 298 | memset(wb, 0, sizeof(*wb)); |
f1d0b063 | 299 | |
810df54a JK |
300 | if (wb != &bdi->wb) |
301 | bdi_get(bdi); | |
6467716a AB |
302 | wb->bdi = bdi; |
303 | wb->last_old_flush = jiffies; | |
304 | INIT_LIST_HEAD(&wb->b_dirty); | |
305 | INIT_LIST_HEAD(&wb->b_io); | |
306 | INIT_LIST_HEAD(&wb->b_more_io); | |
0ae45f63 | 307 | INIT_LIST_HEAD(&wb->b_dirty_time); |
f758eeab | 308 | spin_lock_init(&wb->list_lock); |
66f3b8e2 | 309 | |
a88a341a TH |
310 | wb->bw_time_stamp = jiffies; |
311 | wb->balanced_dirty_ratelimit = INIT_BW; | |
312 | wb->dirty_ratelimit = INIT_BW; | |
313 | wb->write_bandwidth = INIT_BW; | |
314 | wb->avg_write_bandwidth = INIT_BW; | |
cf0ca9fe | 315 | |
f0054bb1 TH |
316 | spin_lock_init(&wb->work_lock); |
317 | INIT_LIST_HEAD(&wb->work_list); | |
318 | INIT_DELAYED_WORK(&wb->dwork, wb_workfn); | |
b57d74af | 319 | wb->dirty_sleep = jiffies; |
c284de61 | 320 | |
a13f35e8 | 321 | wb->congested = wb_congested_get_create(bdi, blkcg_id, gfp); |
810df54a JK |
322 | if (!wb->congested) { |
323 | err = -ENOMEM; | |
324 | goto out_put_bdi; | |
325 | } | |
a13f35e8 | 326 | |
8395cd9f | 327 | err = fprop_local_init_percpu(&wb->completions, gfp); |
a88a341a | 328 | if (err) |
a13f35e8 | 329 | goto out_put_cong; |
c284de61 | 330 | |
93f78d88 | 331 | for (i = 0; i < NR_WB_STAT_ITEMS; i++) { |
8395cd9f | 332 | err = percpu_counter_init(&wb->stat[i], 0, gfp); |
a13f35e8 TH |
333 | if (err) |
334 | goto out_destroy_stat; | |
93f78d88 | 335 | } |
cf0ca9fe | 336 | |
93f78d88 | 337 | return 0; |
a13f35e8 TH |
338 | |
339 | out_destroy_stat: | |
078c6c3a | 340 | while (i--) |
a13f35e8 TH |
341 | percpu_counter_destroy(&wb->stat[i]); |
342 | fprop_local_destroy_percpu(&wb->completions); | |
343 | out_put_cong: | |
344 | wb_congested_put(wb->congested); | |
810df54a JK |
345 | out_put_bdi: |
346 | if (wb != &bdi->wb) | |
347 | bdi_put(bdi); | |
a13f35e8 | 348 | return err; |
cf0ca9fe | 349 | } |
cf0ca9fe | 350 | |
e8cb72b3 JK |
351 | static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb); |
352 | ||
03ba3782 JA |
353 | /* |
354 | * Remove bdi from the global list and shutdown any threads we have running | |
355 | */ | |
46100071 | 356 | static void wb_shutdown(struct bdi_writeback *wb) |
66f3b8e2 | 357 | { |
c4db59d3 | 358 | /* Make sure nobody queues further work */ |
46100071 TH |
359 | spin_lock_bh(&wb->work_lock); |
360 | if (!test_and_clear_bit(WB_registered, &wb->state)) { | |
361 | spin_unlock_bh(&wb->work_lock); | |
03ba3782 | 362 | return; |
c4db59d3 | 363 | } |
46100071 | 364 | spin_unlock_bh(&wb->work_lock); |
03ba3782 | 365 | |
e8cb72b3 | 366 | cgwb_remove_from_bdi_list(wb); |
03ba3782 | 367 | /* |
46100071 TH |
368 | * Drain work list and shutdown the delayed_work. !WB_registered |
369 | * tells wb_workfn() that @wb is dying and its work_list needs to | |
370 | * be drained no matter what. | |
03ba3782 | 371 | */ |
46100071 TH |
372 | mod_delayed_work(bdi_wq, &wb->dwork, 0); |
373 | flush_delayed_work(&wb->dwork); | |
374 | WARN_ON(!list_empty(&wb->work_list)); | |
375 | } | |
376 | ||
f0054bb1 | 377 | static void wb_exit(struct bdi_writeback *wb) |
93f78d88 TH |
378 | { |
379 | int i; | |
380 | ||
381 | WARN_ON(delayed_work_pending(&wb->dwork)); | |
382 | ||
383 | for (i = 0; i < NR_WB_STAT_ITEMS; i++) | |
384 | percpu_counter_destroy(&wb->stat[i]); | |
6467716a | 385 | |
a88a341a | 386 | fprop_local_destroy_percpu(&wb->completions); |
a13f35e8 | 387 | wb_congested_put(wb->congested); |
810df54a JK |
388 | if (wb != &wb->bdi->wb) |
389 | bdi_put(wb->bdi); | |
a88a341a | 390 | } |
e98be2d5 | 391 | |
52ebea74 TH |
392 | #ifdef CONFIG_CGROUP_WRITEBACK |
393 | ||
394 | #include <linux/memcontrol.h> | |
395 | ||
396 | /* | |
397 | * cgwb_lock protects bdi->cgwb_tree, bdi->cgwb_congested_tree, | |
398 | * blkcg->cgwb_list, and memcg->cgwb_list. bdi->cgwb_tree is also RCU | |
4514451e | 399 | * protected. |
52ebea74 TH |
400 | */ |
401 | static DEFINE_SPINLOCK(cgwb_lock); | |
f1834646 | 402 | static struct workqueue_struct *cgwb_release_wq; |
52ebea74 TH |
403 | |
404 | /** | |
405 | * wb_congested_get_create - get or create a wb_congested | |
406 | * @bdi: associated bdi | |
407 | * @blkcg_id: ID of the associated blkcg | |
408 | * @gfp: allocation mask | |
409 | * | |
410 | * Look up the wb_congested for @blkcg_id on @bdi. If missing, create one. | |
411 | * The returned wb_congested has its reference count incremented. Returns | |
412 | * NULL on failure. | |
413 | */ | |
414 | struct bdi_writeback_congested * | |
415 | wb_congested_get_create(struct backing_dev_info *bdi, int blkcg_id, gfp_t gfp) | |
416 | { | |
417 | struct bdi_writeback_congested *new_congested = NULL, *congested; | |
418 | struct rb_node **node, *parent; | |
419 | unsigned long flags; | |
52ebea74 TH |
420 | retry: |
421 | spin_lock_irqsave(&cgwb_lock, flags); | |
422 | ||
423 | node = &bdi->cgwb_congested_tree.rb_node; | |
424 | parent = NULL; | |
425 | ||
426 | while (*node != NULL) { | |
427 | parent = *node; | |
bc71226b GT |
428 | congested = rb_entry(parent, struct bdi_writeback_congested, |
429 | rb_node); | |
52ebea74 TH |
430 | if (congested->blkcg_id < blkcg_id) |
431 | node = &parent->rb_left; | |
432 | else if (congested->blkcg_id > blkcg_id) | |
433 | node = &parent->rb_right; | |
434 | else | |
435 | goto found; | |
436 | } | |
437 | ||
438 | if (new_congested) { | |
439 | /* !found and storage for new one already allocated, insert */ | |
440 | congested = new_congested; | |
441 | new_congested = NULL; | |
442 | rb_link_node(&congested->rb_node, parent, node); | |
443 | rb_insert_color(&congested->rb_node, &bdi->cgwb_congested_tree); | |
52ebea74 TH |
444 | goto found; |
445 | } | |
446 | ||
447 | spin_unlock_irqrestore(&cgwb_lock, flags); | |
448 | ||
449 | /* allocate storage for new one and retry */ | |
450 | new_congested = kzalloc(sizeof(*new_congested), gfp); | |
451 | if (!new_congested) | |
452 | return NULL; | |
453 | ||
454 | atomic_set(&new_congested->refcnt, 0); | |
b7d680d7 | 455 | new_congested->__bdi = bdi; |
52ebea74 TH |
456 | new_congested->blkcg_id = blkcg_id; |
457 | goto retry; | |
458 | ||
459 | found: | |
460 | atomic_inc(&congested->refcnt); | |
461 | spin_unlock_irqrestore(&cgwb_lock, flags); | |
462 | kfree(new_congested); | |
463 | return congested; | |
464 | } | |
465 | ||
466 | /** | |
467 | * wb_congested_put - put a wb_congested | |
468 | * @congested: wb_congested to put | |
469 | * | |
470 | * Put @congested and destroy it if the refcnt reaches zero. | |
471 | */ | |
472 | void wb_congested_put(struct bdi_writeback_congested *congested) | |
473 | { | |
52ebea74 TH |
474 | unsigned long flags; |
475 | ||
52ebea74 TH |
476 | local_irq_save(flags); |
477 | if (!atomic_dec_and_lock(&congested->refcnt, &cgwb_lock)) { | |
478 | local_irq_restore(flags); | |
479 | return; | |
480 | } | |
481 | ||
a20135ff | 482 | /* bdi might already have been destroyed leaving @congested unlinked */ |
b7d680d7 | 483 | if (congested->__bdi) { |
a20135ff | 484 | rb_erase(&congested->rb_node, |
b7d680d7 JK |
485 | &congested->__bdi->cgwb_congested_tree); |
486 | congested->__bdi = NULL; | |
a20135ff TH |
487 | } |
488 | ||
52ebea74 TH |
489 | spin_unlock_irqrestore(&cgwb_lock, flags); |
490 | kfree(congested); | |
52ebea74 TH |
491 | } |
492 | ||
493 | static void cgwb_release_workfn(struct work_struct *work) | |
494 | { | |
495 | struct bdi_writeback *wb = container_of(work, struct bdi_writeback, | |
496 | release_work); | |
52ebea74 | 497 | |
3ee7e869 | 498 | mutex_lock(&wb->bdi->cgwb_release_mutex); |
52ebea74 TH |
499 | wb_shutdown(wb); |
500 | ||
501 | css_put(wb->memcg_css); | |
502 | css_put(wb->blkcg_css); | |
3ee7e869 | 503 | mutex_unlock(&wb->bdi->cgwb_release_mutex); |
52ebea74 | 504 | |
841710aa | 505 | fprop_local_destroy_percpu(&wb->memcg_completions); |
52ebea74 TH |
506 | percpu_ref_exit(&wb->refcnt); |
507 | wb_exit(wb); | |
508 | kfree_rcu(wb, rcu); | |
52ebea74 TH |
509 | } |
510 | ||
511 | static void cgwb_release(struct percpu_ref *refcnt) | |
512 | { | |
513 | struct bdi_writeback *wb = container_of(refcnt, struct bdi_writeback, | |
514 | refcnt); | |
f1834646 | 515 | queue_work(cgwb_release_wq, &wb->release_work); |
52ebea74 TH |
516 | } |
517 | ||
518 | static void cgwb_kill(struct bdi_writeback *wb) | |
519 | { | |
520 | lockdep_assert_held(&cgwb_lock); | |
521 | ||
522 | WARN_ON(!radix_tree_delete(&wb->bdi->cgwb_tree, wb->memcg_css->id)); | |
523 | list_del(&wb->memcg_node); | |
524 | list_del(&wb->blkcg_node); | |
525 | percpu_ref_kill(&wb->refcnt); | |
526 | } | |
527 | ||
e8cb72b3 JK |
528 | static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb) |
529 | { | |
530 | spin_lock_irq(&cgwb_lock); | |
531 | list_del_rcu(&wb->bdi_node); | |
532 | spin_unlock_irq(&cgwb_lock); | |
533 | } | |
534 | ||
52ebea74 TH |
535 | static int cgwb_create(struct backing_dev_info *bdi, |
536 | struct cgroup_subsys_state *memcg_css, gfp_t gfp) | |
537 | { | |
538 | struct mem_cgroup *memcg; | |
539 | struct cgroup_subsys_state *blkcg_css; | |
540 | struct blkcg *blkcg; | |
541 | struct list_head *memcg_cgwb_list, *blkcg_cgwb_list; | |
542 | struct bdi_writeback *wb; | |
543 | unsigned long flags; | |
544 | int ret = 0; | |
545 | ||
546 | memcg = mem_cgroup_from_css(memcg_css); | |
c165b3e3 | 547 | blkcg_css = cgroup_get_e_css(memcg_css->cgroup, &io_cgrp_subsys); |
52ebea74 | 548 | blkcg = css_to_blkcg(blkcg_css); |
9ccc3617 | 549 | memcg_cgwb_list = &memcg->cgwb_list; |
52ebea74 TH |
550 | blkcg_cgwb_list = &blkcg->cgwb_list; |
551 | ||
552 | /* look up again under lock and discard on blkcg mismatch */ | |
553 | spin_lock_irqsave(&cgwb_lock, flags); | |
554 | wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id); | |
555 | if (wb && wb->blkcg_css != blkcg_css) { | |
556 | cgwb_kill(wb); | |
557 | wb = NULL; | |
558 | } | |
559 | spin_unlock_irqrestore(&cgwb_lock, flags); | |
560 | if (wb) | |
561 | goto out_put; | |
562 | ||
563 | /* need to create a new one */ | |
564 | wb = kmalloc(sizeof(*wb), gfp); | |
0b045bd1 CJ |
565 | if (!wb) { |
566 | ret = -ENOMEM; | |
567 | goto out_put; | |
568 | } | |
52ebea74 | 569 | |
a13f35e8 | 570 | ret = wb_init(wb, bdi, blkcg_css->id, gfp); |
52ebea74 TH |
571 | if (ret) |
572 | goto err_free; | |
573 | ||
574 | ret = percpu_ref_init(&wb->refcnt, cgwb_release, 0, gfp); | |
575 | if (ret) | |
576 | goto err_wb_exit; | |
577 | ||
841710aa TH |
578 | ret = fprop_local_init_percpu(&wb->memcg_completions, gfp); |
579 | if (ret) | |
580 | goto err_ref_exit; | |
581 | ||
52ebea74 TH |
582 | wb->memcg_css = memcg_css; |
583 | wb->blkcg_css = blkcg_css; | |
584 | INIT_WORK(&wb->release_work, cgwb_release_workfn); | |
585 | set_bit(WB_registered, &wb->state); | |
03ba3782 JA |
586 | |
587 | /* | |
52ebea74 TH |
588 | * The root wb determines the registered state of the whole bdi and |
589 | * memcg_cgwb_list and blkcg_cgwb_list's next pointers indicate | |
590 | * whether they're still online. Don't link @wb if any is dead. | |
591 | * See wb_memcg_offline() and wb_blkcg_offline(). | |
03ba3782 | 592 | */ |
52ebea74 TH |
593 | ret = -ENODEV; |
594 | spin_lock_irqsave(&cgwb_lock, flags); | |
595 | if (test_bit(WB_registered, &bdi->wb.state) && | |
596 | blkcg_cgwb_list->next && memcg_cgwb_list->next) { | |
597 | /* we might have raced another instance of this function */ | |
598 | ret = radix_tree_insert(&bdi->cgwb_tree, memcg_css->id, wb); | |
599 | if (!ret) { | |
b817525a | 600 | list_add_tail_rcu(&wb->bdi_node, &bdi->wb_list); |
52ebea74 TH |
601 | list_add(&wb->memcg_node, memcg_cgwb_list); |
602 | list_add(&wb->blkcg_node, blkcg_cgwb_list); | |
603 | css_get(memcg_css); | |
604 | css_get(blkcg_css); | |
605 | } | |
606 | } | |
607 | spin_unlock_irqrestore(&cgwb_lock, flags); | |
608 | if (ret) { | |
609 | if (ret == -EEXIST) | |
610 | ret = 0; | |
a13f35e8 | 611 | goto err_fprop_exit; |
52ebea74 TH |
612 | } |
613 | goto out_put; | |
614 | ||
841710aa TH |
615 | err_fprop_exit: |
616 | fprop_local_destroy_percpu(&wb->memcg_completions); | |
52ebea74 TH |
617 | err_ref_exit: |
618 | percpu_ref_exit(&wb->refcnt); | |
619 | err_wb_exit: | |
620 | wb_exit(wb); | |
621 | err_free: | |
622 | kfree(wb); | |
623 | out_put: | |
624 | css_put(blkcg_css); | |
625 | return ret; | |
66f3b8e2 JA |
626 | } |
627 | ||
52ebea74 TH |
628 | /** |
629 | * wb_get_create - get wb for a given memcg, create if necessary | |
630 | * @bdi: target bdi | |
631 | * @memcg_css: cgroup_subsys_state of the target memcg (must have positive ref) | |
632 | * @gfp: allocation mask to use | |
633 | * | |
634 | * Try to get the wb for @memcg_css on @bdi. If it doesn't exist, try to | |
635 | * create one. The returned wb has its refcount incremented. | |
636 | * | |
637 | * This function uses css_get() on @memcg_css and thus expects its refcnt | |
638 | * to be positive on invocation. IOW, rcu_read_lock() protection on | |
639 | * @memcg_css isn't enough. try_get it before calling this function. | |
640 | * | |
641 | * A wb is keyed by its associated memcg. As blkcg implicitly enables | |
642 | * memcg on the default hierarchy, memcg association is guaranteed to be | |
643 | * more specific (equal or descendant to the associated blkcg) and thus can | |
644 | * identify both the memcg and blkcg associations. | |
645 | * | |
646 | * Because the blkcg associated with a memcg may change as blkcg is enabled | |
647 | * and disabled closer to root in the hierarchy, each wb keeps track of | |
648 | * both the memcg and blkcg associated with it and verifies the blkcg on | |
649 | * each lookup. On mismatch, the existing wb is discarded and a new one is | |
650 | * created. | |
651 | */ | |
652 | struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi, | |
653 | struct cgroup_subsys_state *memcg_css, | |
654 | gfp_t gfp) | |
6467716a | 655 | { |
52ebea74 TH |
656 | struct bdi_writeback *wb; |
657 | ||
d0164adc | 658 | might_sleep_if(gfpflags_allow_blocking(gfp)); |
52ebea74 TH |
659 | |
660 | if (!memcg_css->parent) | |
661 | return &bdi->wb; | |
662 | ||
663 | do { | |
664 | rcu_read_lock(); | |
665 | wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id); | |
666 | if (wb) { | |
667 | struct cgroup_subsys_state *blkcg_css; | |
668 | ||
669 | /* see whether the blkcg association has changed */ | |
670 | blkcg_css = cgroup_get_e_css(memcg_css->cgroup, | |
c165b3e3 | 671 | &io_cgrp_subsys); |
52ebea74 TH |
672 | if (unlikely(wb->blkcg_css != blkcg_css || |
673 | !wb_tryget(wb))) | |
674 | wb = NULL; | |
675 | css_put(blkcg_css); | |
676 | } | |
677 | rcu_read_unlock(); | |
678 | } while (!wb && !cgwb_create(bdi, memcg_css, gfp)); | |
679 | ||
680 | return wb; | |
681 | } | |
6467716a | 682 | |
a13f35e8 | 683 | static int cgwb_bdi_init(struct backing_dev_info *bdi) |
52ebea74 | 684 | { |
a13f35e8 TH |
685 | int ret; |
686 | ||
52ebea74 TH |
687 | INIT_RADIX_TREE(&bdi->cgwb_tree, GFP_ATOMIC); |
688 | bdi->cgwb_congested_tree = RB_ROOT; | |
3ee7e869 | 689 | mutex_init(&bdi->cgwb_release_mutex); |
a13f35e8 TH |
690 | |
691 | ret = wb_init(&bdi->wb, bdi, 1, GFP_KERNEL); | |
692 | if (!ret) { | |
7d828602 | 693 | bdi->wb.memcg_css = &root_mem_cgroup->css; |
a13f35e8 TH |
694 | bdi->wb.blkcg_css = blkcg_root_css; |
695 | } | |
696 | return ret; | |
6467716a AB |
697 | } |
698 | ||
b1c51afc | 699 | static void cgwb_bdi_unregister(struct backing_dev_info *bdi) |
52ebea74 TH |
700 | { |
701 | struct radix_tree_iter iter; | |
702 | void **slot; | |
5318ce7d | 703 | struct bdi_writeback *wb; |
52ebea74 TH |
704 | |
705 | WARN_ON(test_bit(WB_registered, &bdi->wb.state)); | |
706 | ||
707 | spin_lock_irq(&cgwb_lock); | |
708 | radix_tree_for_each_slot(slot, &bdi->cgwb_tree, &iter, 0) | |
709 | cgwb_kill(*slot); | |
3ee7e869 | 710 | spin_unlock_irq(&cgwb_lock); |
5318ce7d | 711 | |
3ee7e869 JK |
712 | mutex_lock(&bdi->cgwb_release_mutex); |
713 | spin_lock_irq(&cgwb_lock); | |
5318ce7d JK |
714 | while (!list_empty(&bdi->wb_list)) { |
715 | wb = list_first_entry(&bdi->wb_list, struct bdi_writeback, | |
716 | bdi_node); | |
717 | spin_unlock_irq(&cgwb_lock); | |
718 | wb_shutdown(wb); | |
719 | spin_lock_irq(&cgwb_lock); | |
720 | } | |
52ebea74 | 721 | spin_unlock_irq(&cgwb_lock); |
3ee7e869 | 722 | mutex_unlock(&bdi->cgwb_release_mutex); |
52ebea74 TH |
723 | } |
724 | ||
725 | /** | |
726 | * wb_memcg_offline - kill all wb's associated with a memcg being offlined | |
727 | * @memcg: memcg being offlined | |
728 | * | |
729 | * Also prevents creation of any new wb's associated with @memcg. | |
e98be2d5 | 730 | */ |
52ebea74 TH |
731 | void wb_memcg_offline(struct mem_cgroup *memcg) |
732 | { | |
9ccc3617 | 733 | struct list_head *memcg_cgwb_list = &memcg->cgwb_list; |
52ebea74 TH |
734 | struct bdi_writeback *wb, *next; |
735 | ||
736 | spin_lock_irq(&cgwb_lock); | |
737 | list_for_each_entry_safe(wb, next, memcg_cgwb_list, memcg_node) | |
738 | cgwb_kill(wb); | |
739 | memcg_cgwb_list->next = NULL; /* prevent new wb's */ | |
740 | spin_unlock_irq(&cgwb_lock); | |
741 | } | |
742 | ||
743 | /** | |
744 | * wb_blkcg_offline - kill all wb's associated with a blkcg being offlined | |
745 | * @blkcg: blkcg being offlined | |
746 | * | |
747 | * Also prevents creation of any new wb's associated with @blkcg. | |
748 | */ | |
749 | void wb_blkcg_offline(struct blkcg *blkcg) | |
750 | { | |
52ebea74 TH |
751 | struct bdi_writeback *wb, *next; |
752 | ||
753 | spin_lock_irq(&cgwb_lock); | |
754 | list_for_each_entry_safe(wb, next, &blkcg->cgwb_list, blkcg_node) | |
755 | cgwb_kill(wb); | |
756 | blkcg->cgwb_list.next = NULL; /* prevent new wb's */ | |
757 | spin_unlock_irq(&cgwb_lock); | |
758 | } | |
759 | ||
df23de55 JK |
760 | static void cgwb_bdi_exit(struct backing_dev_info *bdi) |
761 | { | |
762 | struct rb_node *rbn; | |
763 | ||
764 | spin_lock_irq(&cgwb_lock); | |
765 | while ((rbn = rb_first(&bdi->cgwb_congested_tree))) { | |
766 | struct bdi_writeback_congested *congested = | |
767 | rb_entry(rbn, struct bdi_writeback_congested, rb_node); | |
768 | ||
769 | rb_erase(rbn, &bdi->cgwb_congested_tree); | |
b7d680d7 | 770 | congested->__bdi = NULL; /* mark @congested unlinked */ |
df23de55 JK |
771 | } |
772 | spin_unlock_irq(&cgwb_lock); | |
773 | } | |
774 | ||
e8cb72b3 JK |
775 | static void cgwb_bdi_register(struct backing_dev_info *bdi) |
776 | { | |
777 | spin_lock_irq(&cgwb_lock); | |
778 | list_add_tail_rcu(&bdi->wb.bdi_node, &bdi->wb_list); | |
779 | spin_unlock_irq(&cgwb_lock); | |
780 | } | |
781 | ||
f1834646 TH |
782 | static int __init cgwb_init(void) |
783 | { | |
784 | /* | |
785 | * There can be many concurrent release work items overwhelming | |
786 | * system_wq. Put them in a separate wq and limit concurrency. | |
787 | * There's no point in executing many of these in parallel. | |
788 | */ | |
789 | cgwb_release_wq = alloc_workqueue("cgwb_release", 0, 1); | |
790 | if (!cgwb_release_wq) | |
791 | return -ENOMEM; | |
792 | ||
793 | return 0; | |
794 | } | |
795 | subsys_initcall(cgwb_init); | |
796 | ||
52ebea74 TH |
797 | #else /* CONFIG_CGROUP_WRITEBACK */ |
798 | ||
a13f35e8 TH |
799 | static int cgwb_bdi_init(struct backing_dev_info *bdi) |
800 | { | |
801 | int err; | |
802 | ||
803 | bdi->wb_congested = kzalloc(sizeof(*bdi->wb_congested), GFP_KERNEL); | |
804 | if (!bdi->wb_congested) | |
805 | return -ENOMEM; | |
806 | ||
5f478e4e TH |
807 | atomic_set(&bdi->wb_congested->refcnt, 1); |
808 | ||
a13f35e8 TH |
809 | err = wb_init(&bdi->wb, bdi, 1, GFP_KERNEL); |
810 | if (err) { | |
5f478e4e | 811 | wb_congested_put(bdi->wb_congested); |
a13f35e8 TH |
812 | return err; |
813 | } | |
814 | return 0; | |
815 | } | |
816 | ||
b1c51afc | 817 | static void cgwb_bdi_unregister(struct backing_dev_info *bdi) { } |
df23de55 JK |
818 | |
819 | static void cgwb_bdi_exit(struct backing_dev_info *bdi) | |
5f478e4e TH |
820 | { |
821 | wb_congested_put(bdi->wb_congested); | |
822 | } | |
52ebea74 | 823 | |
e8cb72b3 JK |
824 | static void cgwb_bdi_register(struct backing_dev_info *bdi) |
825 | { | |
826 | list_add_tail_rcu(&bdi->wb.bdi_node, &bdi->wb_list); | |
827 | } | |
828 | ||
829 | static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb) | |
830 | { | |
831 | list_del_rcu(&wb->bdi_node); | |
832 | } | |
833 | ||
52ebea74 | 834 | #endif /* CONFIG_CGROUP_WRITEBACK */ |
e98be2d5 | 835 | |
2e82b84c | 836 | static int bdi_init(struct backing_dev_info *bdi) |
b2e8fb6e | 837 | { |
b817525a TH |
838 | int ret; |
839 | ||
cf0ca9fe PZ |
840 | bdi->dev = NULL; |
841 | ||
d03f6cdc | 842 | kref_init(&bdi->refcnt); |
189d3c4a | 843 | bdi->min_ratio = 0; |
a42dde04 | 844 | bdi->max_ratio = 100; |
eb608e3a | 845 | bdi->max_prop_frac = FPROP_FRAC_BASE; |
66f3b8e2 | 846 | INIT_LIST_HEAD(&bdi->bdi_list); |
b817525a | 847 | INIT_LIST_HEAD(&bdi->wb_list); |
cc395d7f | 848 | init_waitqueue_head(&bdi->wb_waitq); |
03ba3782 | 849 | |
b817525a TH |
850 | ret = cgwb_bdi_init(bdi); |
851 | ||
b817525a | 852 | return ret; |
b2e8fb6e | 853 | } |
e98be2d5 | 854 | |
d03f6cdc JK |
855 | struct backing_dev_info *bdi_alloc_node(gfp_t gfp_mask, int node_id) |
856 | { | |
857 | struct backing_dev_info *bdi; | |
858 | ||
859 | bdi = kmalloc_node(sizeof(struct backing_dev_info), | |
860 | gfp_mask | __GFP_ZERO, node_id); | |
861 | if (!bdi) | |
862 | return NULL; | |
863 | ||
864 | if (bdi_init(bdi)) { | |
865 | kfree(bdi); | |
866 | return NULL; | |
867 | } | |
868 | return bdi; | |
869 | } | |
62bf42ad | 870 | EXPORT_SYMBOL(bdi_alloc_node); |
d03f6cdc | 871 | |
7c4cc300 | 872 | int bdi_register_va(struct backing_dev_info *bdi, const char *fmt, va_list args) |
46100071 | 873 | { |
46100071 | 874 | struct device *dev; |
e98be2d5 | 875 | |
46100071 TH |
876 | if (bdi->dev) /* The driver needs to use separate queues per device */ |
877 | return 0; | |
e98be2d5 | 878 | |
7c4cc300 | 879 | dev = device_create_vargs(bdi_class, NULL, MKDEV(0, 0), bdi, fmt, args); |
46100071 TH |
880 | if (IS_ERR(dev)) |
881 | return PTR_ERR(dev); | |
04fbfdc1 | 882 | |
e8cb72b3 | 883 | cgwb_bdi_register(bdi); |
46100071 | 884 | bdi->dev = dev; |
b2e8fb6e | 885 | |
6d0e4827 | 886 | bdi_debug_register(bdi, dev_name(dev)); |
46100071 TH |
887 | set_bit(WB_registered, &bdi->wb.state); |
888 | ||
889 | spin_lock_bh(&bdi_lock); | |
890 | list_add_tail_rcu(&bdi->bdi_list, &bdi_list); | |
891 | spin_unlock_bh(&bdi_lock); | |
892 | ||
893 | trace_writeback_bdi_register(bdi); | |
894 | return 0; | |
b2e8fb6e | 895 | } |
baf7a616 JK |
896 | EXPORT_SYMBOL(bdi_register_va); |
897 | ||
7c4cc300 | 898 | int bdi_register(struct backing_dev_info *bdi, const char *fmt, ...) |
baf7a616 JK |
899 | { |
900 | va_list args; | |
901 | int ret; | |
902 | ||
903 | va_start(args, fmt); | |
7c4cc300 | 904 | ret = bdi_register_va(bdi, fmt, args); |
baf7a616 JK |
905 | va_end(args); |
906 | return ret; | |
907 | } | |
46100071 | 908 | EXPORT_SYMBOL(bdi_register); |
b2e8fb6e | 909 | |
df08c32c DW |
910 | int bdi_register_owner(struct backing_dev_info *bdi, struct device *owner) |
911 | { | |
912 | int rc; | |
913 | ||
7c4cc300 | 914 | rc = bdi_register(bdi, "%u:%u", MAJOR(owner->devt), MINOR(owner->devt)); |
df08c32c DW |
915 | if (rc) |
916 | return rc; | |
b6f8fec4 JK |
917 | /* Leaking owner reference... */ |
918 | WARN_ON(bdi->owner); | |
df08c32c DW |
919 | bdi->owner = owner; |
920 | get_device(owner); | |
921 | return 0; | |
922 | } | |
923 | EXPORT_SYMBOL(bdi_register_owner); | |
924 | ||
46100071 TH |
925 | /* |
926 | * Remove bdi from bdi_list, and ensure that it is no longer visible | |
927 | */ | |
928 | static void bdi_remove_from_list(struct backing_dev_info *bdi) | |
929 | { | |
930 | spin_lock_bh(&bdi_lock); | |
931 | list_del_rcu(&bdi->bdi_list); | |
932 | spin_unlock_bh(&bdi_lock); | |
b2e8fb6e | 933 | |
46100071 TH |
934 | synchronize_rcu_expedited(); |
935 | } | |
cf0ca9fe | 936 | |
b02176f3 | 937 | void bdi_unregister(struct backing_dev_info *bdi) |
b2e8fb6e | 938 | { |
f0054bb1 TH |
939 | /* make sure nobody finds us on the bdi_list anymore */ |
940 | bdi_remove_from_list(bdi); | |
941 | wb_shutdown(&bdi->wb); | |
b1c51afc | 942 | cgwb_bdi_unregister(bdi); |
7a401a97 | 943 | |
c4db59d3 CH |
944 | if (bdi->dev) { |
945 | bdi_debug_unregister(bdi); | |
946 | device_unregister(bdi->dev); | |
947 | bdi->dev = NULL; | |
948 | } | |
df08c32c DW |
949 | |
950 | if (bdi->owner) { | |
951 | put_device(bdi->owner); | |
952 | bdi->owner = NULL; | |
953 | } | |
b02176f3 | 954 | } |
c4db59d3 | 955 | |
d03f6cdc JK |
956 | static void release_bdi(struct kref *ref) |
957 | { | |
958 | struct backing_dev_info *bdi = | |
959 | container_of(ref, struct backing_dev_info, refcnt); | |
960 | ||
5af110b2 JK |
961 | if (test_bit(WB_registered, &bdi->wb.state)) |
962 | bdi_unregister(bdi); | |
2e82b84c JK |
963 | WARN_ON_ONCE(bdi->dev); |
964 | wb_exit(&bdi->wb); | |
965 | cgwb_bdi_exit(bdi); | |
d03f6cdc JK |
966 | kfree(bdi); |
967 | } | |
968 | ||
969 | void bdi_put(struct backing_dev_info *bdi) | |
970 | { | |
971 | kref_put(&bdi->refcnt, release_bdi); | |
972 | } | |
62bf42ad | 973 | EXPORT_SYMBOL(bdi_put); |
d03f6cdc | 974 | |
3fcfab16 AM |
975 | static wait_queue_head_t congestion_wqh[2] = { |
976 | __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]), | |
977 | __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1]) | |
978 | }; | |
ec8a6f26 | 979 | static atomic_t nr_wb_congested[2]; |
3fcfab16 | 980 | |
ec8a6f26 | 981 | void clear_wb_congested(struct bdi_writeback_congested *congested, int sync) |
3fcfab16 | 982 | { |
1faa16d2 | 983 | wait_queue_head_t *wqh = &congestion_wqh[sync]; |
c877ef8a | 984 | enum wb_congested_state bit; |
3fcfab16 | 985 | |
4452226e | 986 | bit = sync ? WB_sync_congested : WB_async_congested; |
ec8a6f26 TH |
987 | if (test_and_clear_bit(bit, &congested->state)) |
988 | atomic_dec(&nr_wb_congested[sync]); | |
4e857c58 | 989 | smp_mb__after_atomic(); |
3fcfab16 AM |
990 | if (waitqueue_active(wqh)) |
991 | wake_up(wqh); | |
992 | } | |
ec8a6f26 | 993 | EXPORT_SYMBOL(clear_wb_congested); |
3fcfab16 | 994 | |
ec8a6f26 | 995 | void set_wb_congested(struct bdi_writeback_congested *congested, int sync) |
3fcfab16 | 996 | { |
c877ef8a | 997 | enum wb_congested_state bit; |
3fcfab16 | 998 | |
4452226e | 999 | bit = sync ? WB_sync_congested : WB_async_congested; |
ec8a6f26 TH |
1000 | if (!test_and_set_bit(bit, &congested->state)) |
1001 | atomic_inc(&nr_wb_congested[sync]); | |
3fcfab16 | 1002 | } |
ec8a6f26 | 1003 | EXPORT_SYMBOL(set_wb_congested); |
3fcfab16 AM |
1004 | |
1005 | /** | |
1006 | * congestion_wait - wait for a backing_dev to become uncongested | |
8aa7e847 | 1007 | * @sync: SYNC or ASYNC IO |
3fcfab16 AM |
1008 | * @timeout: timeout in jiffies |
1009 | * | |
1010 | * Waits for up to @timeout jiffies for a backing_dev (any backing_dev) to exit | |
1011 | * write congestion. If no backing_devs are congested then just wait for the | |
1012 | * next write to be completed. | |
1013 | */ | |
8aa7e847 | 1014 | long congestion_wait(int sync, long timeout) |
3fcfab16 AM |
1015 | { |
1016 | long ret; | |
52bb9198 | 1017 | unsigned long start = jiffies; |
3fcfab16 | 1018 | DEFINE_WAIT(wait); |
8aa7e847 | 1019 | wait_queue_head_t *wqh = &congestion_wqh[sync]; |
3fcfab16 AM |
1020 | |
1021 | prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); | |
1022 | ret = io_schedule_timeout(timeout); | |
1023 | finish_wait(wqh, &wait); | |
52bb9198 MG |
1024 | |
1025 | trace_writeback_congestion_wait(jiffies_to_usecs(timeout), | |
1026 | jiffies_to_usecs(jiffies - start)); | |
1027 | ||
3fcfab16 AM |
1028 | return ret; |
1029 | } | |
1030 | EXPORT_SYMBOL(congestion_wait); | |
04fbfdc1 | 1031 | |
0e093d99 | 1032 | /** |
599d0c95 | 1033 | * wait_iff_congested - Conditionally wait for a backing_dev to become uncongested or a pgdat to complete writes |
0e093d99 MG |
1034 | * @sync: SYNC or ASYNC IO |
1035 | * @timeout: timeout in jiffies | |
1036 | * | |
e3c1ac58 AR |
1037 | * In the event of a congested backing_dev (any backing_dev) this waits |
1038 | * for up to @timeout jiffies for either a BDI to exit congestion of the | |
1039 | * given @sync queue or a write to complete. | |
0e093d99 MG |
1040 | * |
1041 | * The return value is 0 if the sleep is for the full timeout. Otherwise, | |
1042 | * it is the number of jiffies that were still remaining when the function | |
1043 | * returned. return_value == timeout implies the function did not sleep. | |
1044 | */ | |
e3c1ac58 | 1045 | long wait_iff_congested(int sync, long timeout) |
0e093d99 MG |
1046 | { |
1047 | long ret; | |
1048 | unsigned long start = jiffies; | |
1049 | DEFINE_WAIT(wait); | |
1050 | wait_queue_head_t *wqh = &congestion_wqh[sync]; | |
1051 | ||
1052 | /* | |
e3c1ac58 | 1053 | * If there is no congestion, yield if necessary instead |
0e093d99 MG |
1054 | * of sleeping on the congestion queue |
1055 | */ | |
e3c1ac58 | 1056 | if (atomic_read(&nr_wb_congested[sync]) == 0) { |
ede37713 | 1057 | cond_resched(); |
599d0c95 | 1058 | |
0e093d99 MG |
1059 | /* In case we scheduled, work out time remaining */ |
1060 | ret = timeout - (jiffies - start); | |
1061 | if (ret < 0) | |
1062 | ret = 0; | |
1063 | ||
1064 | goto out; | |
1065 | } | |
1066 | ||
1067 | /* Sleep until uncongested or a write happens */ | |
1068 | prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); | |
1069 | ret = io_schedule_timeout(timeout); | |
1070 | finish_wait(wqh, &wait); | |
1071 | ||
1072 | out: | |
1073 | trace_writeback_wait_iff_congested(jiffies_to_usecs(timeout), | |
1074 | jiffies_to_usecs(jiffies - start)); | |
1075 | ||
1076 | return ret; | |
1077 | } | |
1078 | EXPORT_SYMBOL(wait_iff_congested); |