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457c8996 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
3fcfab16 AM |
2 | |
3 | #include <linux/wait.h> | |
4 | #include <linux/backing-dev.h> | |
03ba3782 JA |
5 | #include <linux/kthread.h> |
6 | #include <linux/freezer.h> | |
3fcfab16 | 7 | #include <linux/fs.h> |
26160158 | 8 | #include <linux/pagemap.h> |
03ba3782 | 9 | #include <linux/mm.h> |
3fcfab16 AM |
10 | #include <linux/sched.h> |
11 | #include <linux/module.h> | |
cf0ca9fe PZ |
12 | #include <linux/writeback.h> |
13 | #include <linux/device.h> | |
455b2864 | 14 | #include <trace/events/writeback.h> |
cf0ca9fe | 15 | |
5129a469 JE |
16 | struct backing_dev_info noop_backing_dev_info = { |
17 | .name = "noop", | |
976e48f8 | 18 | .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK, |
5129a469 | 19 | }; |
a212b105 | 20 | EXPORT_SYMBOL_GPL(noop_backing_dev_info); |
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; | |
0d960a38 | 51 | unsigned long wb_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); |
c7f54084 | 57 | list_for_each_entry(inode, &wb->b_dirty, i_io_list) |
c1955ce3 | 58 | nr_dirty++; |
c7f54084 | 59 | list_for_each_entry(inode, &wb->b_io, i_io_list) |
c1955ce3 | 60 | nr_io++; |
c7f54084 | 61 | list_for_each_entry(inode, &wb->b_more_io, i_io_list) |
c1955ce3 | 62 | nr_more_io++; |
c7f54084 | 63 | list_for_each_entry(inode, &wb->b_dirty_time, i_io_list) |
0ae45f63 TT |
64 | if (inode->i_state & I_DIRTY_TIME) |
65 | nr_dirty_time++; | |
f758eeab | 66 | spin_unlock(&wb->list_lock); |
76f1418b | 67 | |
16c4042f | 68 | global_dirty_limits(&background_thresh, &dirty_thresh); |
0d960a38 | 69 | wb_thresh = wb_calc_thresh(wb, 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", | |
93f78d88 TH |
87 | (unsigned long) K(wb_stat(wb, WB_WRITEBACK)), |
88 | (unsigned long) K(wb_stat(wb, WB_RECLAIMABLE)), | |
0d960a38 | 89 | K(wb_thresh), |
f7d2b1ec JK |
90 | K(dirty_thresh), |
91 | K(background_thresh), | |
93f78d88 TH |
92 | (unsigned long) K(wb_stat(wb, WB_DIRTIED)), |
93 | (unsigned long) K(wb_stat(wb, WB_WRITTEN)), | |
a88a341a | 94 | (unsigned long) K(wb->write_bandwidth), |
f7d2b1ec JK |
95 | nr_dirty, |
96 | nr_io, | |
97 | nr_more_io, | |
0ae45f63 | 98 | nr_dirty_time, |
4452226e | 99 | !list_empty(&bdi->bdi_list), bdi->wb.state); |
76f1418b MS |
100 | #undef K |
101 | ||
102 | return 0; | |
103 | } | |
5ad35093 | 104 | DEFINE_SHOW_ATTRIBUTE(bdi_debug_stats); |
76f1418b | 105 | |
2d146b92 | 106 | static void bdi_debug_register(struct backing_dev_info *bdi, const char *name) |
76f1418b MS |
107 | { |
108 | bdi->debug_dir = debugfs_create_dir(name, bdi_debug_root); | |
97f07697 | 109 | |
2d146b92 GKH |
110 | debugfs_create_file("stats", 0444, bdi->debug_dir, bdi, |
111 | &bdi_debug_stats_fops); | |
76f1418b MS |
112 | } |
113 | ||
114 | static void bdi_debug_unregister(struct backing_dev_info *bdi) | |
115 | { | |
2d146b92 | 116 | debugfs_remove_recursive(bdi->debug_dir); |
76f1418b MS |
117 | } |
118 | #else | |
119 | static inline void bdi_debug_init(void) | |
120 | { | |
121 | } | |
2d146b92 | 122 | static inline void bdi_debug_register(struct backing_dev_info *bdi, |
76f1418b MS |
123 | const char *name) |
124 | { | |
125 | } | |
126 | static inline void bdi_debug_unregister(struct backing_dev_info *bdi) | |
127 | { | |
128 | } | |
129 | #endif | |
130 | ||
cf0ca9fe PZ |
131 | static ssize_t read_ahead_kb_store(struct device *dev, |
132 | struct device_attribute *attr, | |
133 | const char *buf, size_t count) | |
134 | { | |
135 | struct backing_dev_info *bdi = dev_get_drvdata(dev); | |
cf0ca9fe | 136 | unsigned long read_ahead_kb; |
7034ed13 | 137 | ssize_t ret; |
cf0ca9fe | 138 | |
7034ed13 NJ |
139 | ret = kstrtoul(buf, 10, &read_ahead_kb); |
140 | if (ret < 0) | |
141 | return ret; | |
142 | ||
143 | bdi->ra_pages = read_ahead_kb >> (PAGE_SHIFT - 10); | |
144 | ||
145 | return count; | |
cf0ca9fe PZ |
146 | } |
147 | ||
148 | #define K(pages) ((pages) << (PAGE_SHIFT - 10)) | |
149 | ||
150 | #define BDI_SHOW(name, expr) \ | |
151 | static ssize_t name##_show(struct device *dev, \ | |
152 | struct device_attribute *attr, char *page) \ | |
153 | { \ | |
154 | struct backing_dev_info *bdi = dev_get_drvdata(dev); \ | |
155 | \ | |
156 | return snprintf(page, PAGE_SIZE-1, "%lld\n", (long long)expr); \ | |
d9e1241e GKH |
157 | } \ |
158 | static DEVICE_ATTR_RW(name); | |
cf0ca9fe PZ |
159 | |
160 | BDI_SHOW(read_ahead_kb, K(bdi->ra_pages)) | |
161 | ||
189d3c4a PZ |
162 | static ssize_t min_ratio_store(struct device *dev, |
163 | struct device_attribute *attr, const char *buf, size_t count) | |
164 | { | |
165 | struct backing_dev_info *bdi = dev_get_drvdata(dev); | |
189d3c4a | 166 | unsigned int ratio; |
7034ed13 NJ |
167 | ssize_t ret; |
168 | ||
169 | ret = kstrtouint(buf, 10, &ratio); | |
170 | if (ret < 0) | |
171 | return ret; | |
172 | ||
173 | ret = bdi_set_min_ratio(bdi, ratio); | |
174 | if (!ret) | |
175 | ret = count; | |
189d3c4a | 176 | |
189d3c4a PZ |
177 | return ret; |
178 | } | |
179 | BDI_SHOW(min_ratio, bdi->min_ratio) | |
180 | ||
a42dde04 PZ |
181 | static ssize_t max_ratio_store(struct device *dev, |
182 | struct device_attribute *attr, const char *buf, size_t count) | |
183 | { | |
184 | struct backing_dev_info *bdi = dev_get_drvdata(dev); | |
a42dde04 | 185 | unsigned int ratio; |
7034ed13 NJ |
186 | ssize_t ret; |
187 | ||
188 | ret = kstrtouint(buf, 10, &ratio); | |
189 | if (ret < 0) | |
190 | return ret; | |
191 | ||
192 | ret = bdi_set_max_ratio(bdi, ratio); | |
193 | if (!ret) | |
194 | ret = count; | |
a42dde04 | 195 | |
a42dde04 PZ |
196 | return ret; |
197 | } | |
198 | BDI_SHOW(max_ratio, bdi->max_ratio) | |
199 | ||
7d311cda DW |
200 | static ssize_t stable_pages_required_show(struct device *dev, |
201 | struct device_attribute *attr, | |
202 | char *page) | |
203 | { | |
204 | struct backing_dev_info *bdi = dev_get_drvdata(dev); | |
205 | ||
206 | return snprintf(page, PAGE_SIZE-1, "%d\n", | |
207 | bdi_cap_stable_pages_required(bdi) ? 1 : 0); | |
208 | } | |
d9e1241e GKH |
209 | static DEVICE_ATTR_RO(stable_pages_required); |
210 | ||
211 | static struct attribute *bdi_dev_attrs[] = { | |
212 | &dev_attr_read_ahead_kb.attr, | |
213 | &dev_attr_min_ratio.attr, | |
214 | &dev_attr_max_ratio.attr, | |
215 | &dev_attr_stable_pages_required.attr, | |
216 | NULL, | |
cf0ca9fe | 217 | }; |
d9e1241e | 218 | ATTRIBUTE_GROUPS(bdi_dev); |
cf0ca9fe PZ |
219 | |
220 | static __init int bdi_class_init(void) | |
221 | { | |
222 | bdi_class = class_create(THIS_MODULE, "bdi"); | |
14421453 AB |
223 | if (IS_ERR(bdi_class)) |
224 | return PTR_ERR(bdi_class); | |
225 | ||
d9e1241e | 226 | bdi_class->dev_groups = bdi_dev_groups; |
76f1418b | 227 | bdi_debug_init(); |
d03f6cdc | 228 | |
cf0ca9fe PZ |
229 | return 0; |
230 | } | |
76f1418b | 231 | postcore_initcall(bdi_class_init); |
cf0ca9fe | 232 | |
2e82b84c JK |
233 | static int bdi_init(struct backing_dev_info *bdi); |
234 | ||
26160158 JA |
235 | static int __init default_bdi_init(void) |
236 | { | |
237 | int err; | |
238 | ||
839a8e86 | 239 | bdi_wq = alloc_workqueue("writeback", WQ_MEM_RECLAIM | WQ_FREEZABLE | |
b5c872dd | 240 | WQ_UNBOUND | WQ_SYSFS, 0); |
839a8e86 TH |
241 | if (!bdi_wq) |
242 | return -ENOMEM; | |
243 | ||
976e48f8 | 244 | err = bdi_init(&noop_backing_dev_info); |
26160158 JA |
245 | |
246 | return err; | |
247 | } | |
248 | subsys_initcall(default_bdi_init); | |
249 | ||
6467716a | 250 | /* |
f0054bb1 | 251 | * This function is used when the first inode for this wb is marked dirty. It |
6467716a AB |
252 | * wakes-up the corresponding bdi thread which should then take care of the |
253 | * periodic background write-out of dirty inodes. Since the write-out would | |
254 | * starts only 'dirty_writeback_interval' centisecs from now anyway, we just | |
255 | * set up a timer which wakes the bdi thread up later. | |
256 | * | |
257 | * Note, we wouldn't bother setting up the timer, but this function is on the | |
258 | * fast-path (used by '__mark_inode_dirty()'), so we save few context switches | |
259 | * by delaying the wake-up. | |
6ca738d6 DB |
260 | * |
261 | * We have to be careful not to postpone flush work if it is scheduled for | |
262 | * earlier. Thus we use queue_delayed_work(). | |
6467716a | 263 | */ |
f0054bb1 | 264 | void wb_wakeup_delayed(struct bdi_writeback *wb) |
6467716a AB |
265 | { |
266 | unsigned long timeout; | |
267 | ||
268 | timeout = msecs_to_jiffies(dirty_writeback_interval * 10); | |
f0054bb1 TH |
269 | spin_lock_bh(&wb->work_lock); |
270 | if (test_bit(WB_registered, &wb->state)) | |
271 | queue_delayed_work(bdi_wq, &wb->dwork, timeout); | |
272 | spin_unlock_bh(&wb->work_lock); | |
03ba3782 JA |
273 | } |
274 | ||
cfc4ba53 | 275 | /* |
a88a341a | 276 | * Initial write bandwidth: 100 MB/s |
cfc4ba53 | 277 | */ |
a88a341a | 278 | #define INIT_BW (100 << (20 - PAGE_SHIFT)) |
cfc4ba53 | 279 | |
8395cd9f | 280 | static int wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi, |
a13f35e8 | 281 | int blkcg_id, gfp_t gfp) |
cf0ca9fe | 282 | { |
93f78d88 | 283 | int i, err; |
cf0ca9fe | 284 | |
6467716a | 285 | memset(wb, 0, sizeof(*wb)); |
f1d0b063 | 286 | |
810df54a JK |
287 | if (wb != &bdi->wb) |
288 | bdi_get(bdi); | |
6467716a AB |
289 | wb->bdi = bdi; |
290 | wb->last_old_flush = jiffies; | |
291 | INIT_LIST_HEAD(&wb->b_dirty); | |
292 | INIT_LIST_HEAD(&wb->b_io); | |
293 | INIT_LIST_HEAD(&wb->b_more_io); | |
0ae45f63 | 294 | INIT_LIST_HEAD(&wb->b_dirty_time); |
f758eeab | 295 | spin_lock_init(&wb->list_lock); |
66f3b8e2 | 296 | |
a88a341a TH |
297 | wb->bw_time_stamp = jiffies; |
298 | wb->balanced_dirty_ratelimit = INIT_BW; | |
299 | wb->dirty_ratelimit = INIT_BW; | |
300 | wb->write_bandwidth = INIT_BW; | |
301 | wb->avg_write_bandwidth = INIT_BW; | |
cf0ca9fe | 302 | |
f0054bb1 TH |
303 | spin_lock_init(&wb->work_lock); |
304 | INIT_LIST_HEAD(&wb->work_list); | |
305 | INIT_DELAYED_WORK(&wb->dwork, wb_workfn); | |
b57d74af | 306 | wb->dirty_sleep = jiffies; |
c284de61 | 307 | |
a13f35e8 | 308 | wb->congested = wb_congested_get_create(bdi, blkcg_id, gfp); |
810df54a JK |
309 | if (!wb->congested) { |
310 | err = -ENOMEM; | |
311 | goto out_put_bdi; | |
312 | } | |
a13f35e8 | 313 | |
8395cd9f | 314 | err = fprop_local_init_percpu(&wb->completions, gfp); |
a88a341a | 315 | if (err) |
a13f35e8 | 316 | goto out_put_cong; |
c284de61 | 317 | |
93f78d88 | 318 | for (i = 0; i < NR_WB_STAT_ITEMS; i++) { |
8395cd9f | 319 | err = percpu_counter_init(&wb->stat[i], 0, gfp); |
a13f35e8 TH |
320 | if (err) |
321 | goto out_destroy_stat; | |
93f78d88 | 322 | } |
cf0ca9fe | 323 | |
93f78d88 | 324 | return 0; |
a13f35e8 TH |
325 | |
326 | out_destroy_stat: | |
078c6c3a | 327 | while (i--) |
a13f35e8 TH |
328 | percpu_counter_destroy(&wb->stat[i]); |
329 | fprop_local_destroy_percpu(&wb->completions); | |
330 | out_put_cong: | |
331 | wb_congested_put(wb->congested); | |
810df54a JK |
332 | out_put_bdi: |
333 | if (wb != &bdi->wb) | |
334 | bdi_put(bdi); | |
a13f35e8 | 335 | return err; |
cf0ca9fe | 336 | } |
cf0ca9fe | 337 | |
e8cb72b3 JK |
338 | static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb); |
339 | ||
03ba3782 JA |
340 | /* |
341 | * Remove bdi from the global list and shutdown any threads we have running | |
342 | */ | |
46100071 | 343 | static void wb_shutdown(struct bdi_writeback *wb) |
66f3b8e2 | 344 | { |
c4db59d3 | 345 | /* Make sure nobody queues further work */ |
46100071 TH |
346 | spin_lock_bh(&wb->work_lock); |
347 | if (!test_and_clear_bit(WB_registered, &wb->state)) { | |
348 | spin_unlock_bh(&wb->work_lock); | |
03ba3782 | 349 | return; |
c4db59d3 | 350 | } |
46100071 | 351 | spin_unlock_bh(&wb->work_lock); |
03ba3782 | 352 | |
e8cb72b3 | 353 | cgwb_remove_from_bdi_list(wb); |
03ba3782 | 354 | /* |
46100071 TH |
355 | * Drain work list and shutdown the delayed_work. !WB_registered |
356 | * tells wb_workfn() that @wb is dying and its work_list needs to | |
357 | * be drained no matter what. | |
03ba3782 | 358 | */ |
46100071 TH |
359 | mod_delayed_work(bdi_wq, &wb->dwork, 0); |
360 | flush_delayed_work(&wb->dwork); | |
361 | WARN_ON(!list_empty(&wb->work_list)); | |
362 | } | |
363 | ||
f0054bb1 | 364 | static void wb_exit(struct bdi_writeback *wb) |
93f78d88 TH |
365 | { |
366 | int i; | |
367 | ||
368 | WARN_ON(delayed_work_pending(&wb->dwork)); | |
369 | ||
370 | for (i = 0; i < NR_WB_STAT_ITEMS; i++) | |
371 | percpu_counter_destroy(&wb->stat[i]); | |
6467716a | 372 | |
a88a341a | 373 | fprop_local_destroy_percpu(&wb->completions); |
a13f35e8 | 374 | wb_congested_put(wb->congested); |
810df54a JK |
375 | if (wb != &wb->bdi->wb) |
376 | bdi_put(wb->bdi); | |
a88a341a | 377 | } |
e98be2d5 | 378 | |
52ebea74 TH |
379 | #ifdef CONFIG_CGROUP_WRITEBACK |
380 | ||
381 | #include <linux/memcontrol.h> | |
382 | ||
383 | /* | |
384 | * cgwb_lock protects bdi->cgwb_tree, bdi->cgwb_congested_tree, | |
385 | * blkcg->cgwb_list, and memcg->cgwb_list. bdi->cgwb_tree is also RCU | |
4514451e | 386 | * protected. |
52ebea74 TH |
387 | */ |
388 | static DEFINE_SPINLOCK(cgwb_lock); | |
f1834646 | 389 | static struct workqueue_struct *cgwb_release_wq; |
52ebea74 TH |
390 | |
391 | /** | |
392 | * wb_congested_get_create - get or create a wb_congested | |
393 | * @bdi: associated bdi | |
394 | * @blkcg_id: ID of the associated blkcg | |
395 | * @gfp: allocation mask | |
396 | * | |
397 | * Look up the wb_congested for @blkcg_id on @bdi. If missing, create one. | |
398 | * The returned wb_congested has its reference count incremented. Returns | |
399 | * NULL on failure. | |
400 | */ | |
401 | struct bdi_writeback_congested * | |
402 | wb_congested_get_create(struct backing_dev_info *bdi, int blkcg_id, gfp_t gfp) | |
403 | { | |
404 | struct bdi_writeback_congested *new_congested = NULL, *congested; | |
405 | struct rb_node **node, *parent; | |
406 | unsigned long flags; | |
52ebea74 TH |
407 | retry: |
408 | spin_lock_irqsave(&cgwb_lock, flags); | |
409 | ||
410 | node = &bdi->cgwb_congested_tree.rb_node; | |
411 | parent = NULL; | |
412 | ||
413 | while (*node != NULL) { | |
414 | parent = *node; | |
bc71226b GT |
415 | congested = rb_entry(parent, struct bdi_writeback_congested, |
416 | rb_node); | |
52ebea74 TH |
417 | if (congested->blkcg_id < blkcg_id) |
418 | node = &parent->rb_left; | |
419 | else if (congested->blkcg_id > blkcg_id) | |
420 | node = &parent->rb_right; | |
421 | else | |
422 | goto found; | |
423 | } | |
424 | ||
425 | if (new_congested) { | |
426 | /* !found and storage for new one already allocated, insert */ | |
427 | congested = new_congested; | |
52ebea74 TH |
428 | rb_link_node(&congested->rb_node, parent, node); |
429 | rb_insert_color(&congested->rb_node, &bdi->cgwb_congested_tree); | |
e58dd0de SAS |
430 | spin_unlock_irqrestore(&cgwb_lock, flags); |
431 | return congested; | |
52ebea74 TH |
432 | } |
433 | ||
434 | spin_unlock_irqrestore(&cgwb_lock, flags); | |
435 | ||
436 | /* allocate storage for new one and retry */ | |
437 | new_congested = kzalloc(sizeof(*new_congested), gfp); | |
438 | if (!new_congested) | |
439 | return NULL; | |
440 | ||
e58dd0de | 441 | refcount_set(&new_congested->refcnt, 1); |
b7d680d7 | 442 | new_congested->__bdi = bdi; |
52ebea74 TH |
443 | new_congested->blkcg_id = blkcg_id; |
444 | goto retry; | |
445 | ||
446 | found: | |
e58dd0de | 447 | refcount_inc(&congested->refcnt); |
52ebea74 TH |
448 | spin_unlock_irqrestore(&cgwb_lock, flags); |
449 | kfree(new_congested); | |
450 | return congested; | |
451 | } | |
452 | ||
453 | /** | |
454 | * wb_congested_put - put a wb_congested | |
455 | * @congested: wb_congested to put | |
456 | * | |
457 | * Put @congested and destroy it if the refcnt reaches zero. | |
458 | */ | |
459 | void wb_congested_put(struct bdi_writeback_congested *congested) | |
460 | { | |
52ebea74 TH |
461 | unsigned long flags; |
462 | ||
060288a7 | 463 | if (!refcount_dec_and_lock_irqsave(&congested->refcnt, &cgwb_lock, &flags)) |
52ebea74 | 464 | return; |
52ebea74 | 465 | |
a20135ff | 466 | /* bdi might already have been destroyed leaving @congested unlinked */ |
b7d680d7 | 467 | if (congested->__bdi) { |
a20135ff | 468 | rb_erase(&congested->rb_node, |
b7d680d7 JK |
469 | &congested->__bdi->cgwb_congested_tree); |
470 | congested->__bdi = NULL; | |
a20135ff TH |
471 | } |
472 | ||
52ebea74 TH |
473 | spin_unlock_irqrestore(&cgwb_lock, flags); |
474 | kfree(congested); | |
52ebea74 TH |
475 | } |
476 | ||
477 | static void cgwb_release_workfn(struct work_struct *work) | |
478 | { | |
479 | struct bdi_writeback *wb = container_of(work, struct bdi_writeback, | |
480 | release_work); | |
59b57717 | 481 | struct blkcg *blkcg = css_to_blkcg(wb->blkcg_css); |
52ebea74 | 482 | |
3ee7e869 | 483 | mutex_lock(&wb->bdi->cgwb_release_mutex); |
52ebea74 TH |
484 | wb_shutdown(wb); |
485 | ||
486 | css_put(wb->memcg_css); | |
487 | css_put(wb->blkcg_css); | |
3ee7e869 | 488 | mutex_unlock(&wb->bdi->cgwb_release_mutex); |
52ebea74 | 489 | |
59b57717 DZF |
490 | /* triggers blkg destruction if cgwb_refcnt becomes zero */ |
491 | blkcg_cgwb_put(blkcg); | |
492 | ||
841710aa | 493 | fprop_local_destroy_percpu(&wb->memcg_completions); |
52ebea74 TH |
494 | percpu_ref_exit(&wb->refcnt); |
495 | wb_exit(wb); | |
496 | kfree_rcu(wb, rcu); | |
52ebea74 TH |
497 | } |
498 | ||
499 | static void cgwb_release(struct percpu_ref *refcnt) | |
500 | { | |
501 | struct bdi_writeback *wb = container_of(refcnt, struct bdi_writeback, | |
502 | refcnt); | |
f1834646 | 503 | queue_work(cgwb_release_wq, &wb->release_work); |
52ebea74 TH |
504 | } |
505 | ||
506 | static void cgwb_kill(struct bdi_writeback *wb) | |
507 | { | |
508 | lockdep_assert_held(&cgwb_lock); | |
509 | ||
510 | WARN_ON(!radix_tree_delete(&wb->bdi->cgwb_tree, wb->memcg_css->id)); | |
511 | list_del(&wb->memcg_node); | |
512 | list_del(&wb->blkcg_node); | |
513 | percpu_ref_kill(&wb->refcnt); | |
514 | } | |
515 | ||
e8cb72b3 JK |
516 | static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb) |
517 | { | |
518 | spin_lock_irq(&cgwb_lock); | |
519 | list_del_rcu(&wb->bdi_node); | |
520 | spin_unlock_irq(&cgwb_lock); | |
521 | } | |
522 | ||
52ebea74 TH |
523 | static int cgwb_create(struct backing_dev_info *bdi, |
524 | struct cgroup_subsys_state *memcg_css, gfp_t gfp) | |
525 | { | |
526 | struct mem_cgroup *memcg; | |
527 | struct cgroup_subsys_state *blkcg_css; | |
528 | struct blkcg *blkcg; | |
529 | struct list_head *memcg_cgwb_list, *blkcg_cgwb_list; | |
530 | struct bdi_writeback *wb; | |
531 | unsigned long flags; | |
532 | int ret = 0; | |
533 | ||
534 | memcg = mem_cgroup_from_css(memcg_css); | |
c165b3e3 | 535 | blkcg_css = cgroup_get_e_css(memcg_css->cgroup, &io_cgrp_subsys); |
52ebea74 | 536 | blkcg = css_to_blkcg(blkcg_css); |
9ccc3617 | 537 | memcg_cgwb_list = &memcg->cgwb_list; |
52ebea74 TH |
538 | blkcg_cgwb_list = &blkcg->cgwb_list; |
539 | ||
540 | /* look up again under lock and discard on blkcg mismatch */ | |
541 | spin_lock_irqsave(&cgwb_lock, flags); | |
542 | wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id); | |
543 | if (wb && wb->blkcg_css != blkcg_css) { | |
544 | cgwb_kill(wb); | |
545 | wb = NULL; | |
546 | } | |
547 | spin_unlock_irqrestore(&cgwb_lock, flags); | |
548 | if (wb) | |
549 | goto out_put; | |
550 | ||
551 | /* need to create a new one */ | |
552 | wb = kmalloc(sizeof(*wb), gfp); | |
0b045bd1 CJ |
553 | if (!wb) { |
554 | ret = -ENOMEM; | |
555 | goto out_put; | |
556 | } | |
52ebea74 | 557 | |
a13f35e8 | 558 | ret = wb_init(wb, bdi, blkcg_css->id, gfp); |
52ebea74 TH |
559 | if (ret) |
560 | goto err_free; | |
561 | ||
562 | ret = percpu_ref_init(&wb->refcnt, cgwb_release, 0, gfp); | |
563 | if (ret) | |
564 | goto err_wb_exit; | |
565 | ||
841710aa TH |
566 | ret = fprop_local_init_percpu(&wb->memcg_completions, gfp); |
567 | if (ret) | |
568 | goto err_ref_exit; | |
569 | ||
52ebea74 TH |
570 | wb->memcg_css = memcg_css; |
571 | wb->blkcg_css = blkcg_css; | |
572 | INIT_WORK(&wb->release_work, cgwb_release_workfn); | |
573 | set_bit(WB_registered, &wb->state); | |
03ba3782 JA |
574 | |
575 | /* | |
52ebea74 TH |
576 | * The root wb determines the registered state of the whole bdi and |
577 | * memcg_cgwb_list and blkcg_cgwb_list's next pointers indicate | |
578 | * whether they're still online. Don't link @wb if any is dead. | |
579 | * See wb_memcg_offline() and wb_blkcg_offline(). | |
03ba3782 | 580 | */ |
52ebea74 TH |
581 | ret = -ENODEV; |
582 | spin_lock_irqsave(&cgwb_lock, flags); | |
583 | if (test_bit(WB_registered, &bdi->wb.state) && | |
584 | blkcg_cgwb_list->next && memcg_cgwb_list->next) { | |
585 | /* we might have raced another instance of this function */ | |
586 | ret = radix_tree_insert(&bdi->cgwb_tree, memcg_css->id, wb); | |
587 | if (!ret) { | |
b817525a | 588 | list_add_tail_rcu(&wb->bdi_node, &bdi->wb_list); |
52ebea74 TH |
589 | list_add(&wb->memcg_node, memcg_cgwb_list); |
590 | list_add(&wb->blkcg_node, blkcg_cgwb_list); | |
59b57717 | 591 | blkcg_cgwb_get(blkcg); |
52ebea74 TH |
592 | css_get(memcg_css); |
593 | css_get(blkcg_css); | |
594 | } | |
595 | } | |
596 | spin_unlock_irqrestore(&cgwb_lock, flags); | |
597 | if (ret) { | |
598 | if (ret == -EEXIST) | |
599 | ret = 0; | |
a13f35e8 | 600 | goto err_fprop_exit; |
52ebea74 TH |
601 | } |
602 | goto out_put; | |
603 | ||
841710aa TH |
604 | err_fprop_exit: |
605 | fprop_local_destroy_percpu(&wb->memcg_completions); | |
52ebea74 TH |
606 | err_ref_exit: |
607 | percpu_ref_exit(&wb->refcnt); | |
608 | err_wb_exit: | |
609 | wb_exit(wb); | |
610 | err_free: | |
611 | kfree(wb); | |
612 | out_put: | |
613 | css_put(blkcg_css); | |
614 | return ret; | |
66f3b8e2 JA |
615 | } |
616 | ||
52ebea74 TH |
617 | /** |
618 | * wb_get_create - get wb for a given memcg, create if necessary | |
619 | * @bdi: target bdi | |
620 | * @memcg_css: cgroup_subsys_state of the target memcg (must have positive ref) | |
621 | * @gfp: allocation mask to use | |
622 | * | |
623 | * Try to get the wb for @memcg_css on @bdi. If it doesn't exist, try to | |
624 | * create one. The returned wb has its refcount incremented. | |
625 | * | |
626 | * This function uses css_get() on @memcg_css and thus expects its refcnt | |
627 | * to be positive on invocation. IOW, rcu_read_lock() protection on | |
628 | * @memcg_css isn't enough. try_get it before calling this function. | |
629 | * | |
630 | * A wb is keyed by its associated memcg. As blkcg implicitly enables | |
631 | * memcg on the default hierarchy, memcg association is guaranteed to be | |
632 | * more specific (equal or descendant to the associated blkcg) and thus can | |
633 | * identify both the memcg and blkcg associations. | |
634 | * | |
635 | * Because the blkcg associated with a memcg may change as blkcg is enabled | |
636 | * and disabled closer to root in the hierarchy, each wb keeps track of | |
637 | * both the memcg and blkcg associated with it and verifies the blkcg on | |
638 | * each lookup. On mismatch, the existing wb is discarded and a new one is | |
639 | * created. | |
640 | */ | |
641 | struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi, | |
642 | struct cgroup_subsys_state *memcg_css, | |
643 | gfp_t gfp) | |
6467716a | 644 | { |
52ebea74 TH |
645 | struct bdi_writeback *wb; |
646 | ||
d0164adc | 647 | might_sleep_if(gfpflags_allow_blocking(gfp)); |
52ebea74 TH |
648 | |
649 | if (!memcg_css->parent) | |
650 | return &bdi->wb; | |
651 | ||
652 | do { | |
653 | rcu_read_lock(); | |
654 | wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id); | |
655 | if (wb) { | |
656 | struct cgroup_subsys_state *blkcg_css; | |
657 | ||
658 | /* see whether the blkcg association has changed */ | |
659 | blkcg_css = cgroup_get_e_css(memcg_css->cgroup, | |
c165b3e3 | 660 | &io_cgrp_subsys); |
52ebea74 TH |
661 | if (unlikely(wb->blkcg_css != blkcg_css || |
662 | !wb_tryget(wb))) | |
663 | wb = NULL; | |
664 | css_put(blkcg_css); | |
665 | } | |
666 | rcu_read_unlock(); | |
667 | } while (!wb && !cgwb_create(bdi, memcg_css, gfp)); | |
668 | ||
669 | return wb; | |
670 | } | |
6467716a | 671 | |
a13f35e8 | 672 | static int cgwb_bdi_init(struct backing_dev_info *bdi) |
52ebea74 | 673 | { |
a13f35e8 TH |
674 | int ret; |
675 | ||
52ebea74 TH |
676 | INIT_RADIX_TREE(&bdi->cgwb_tree, GFP_ATOMIC); |
677 | bdi->cgwb_congested_tree = RB_ROOT; | |
3ee7e869 | 678 | mutex_init(&bdi->cgwb_release_mutex); |
7fc5854f | 679 | init_rwsem(&bdi->wb_switch_rwsem); |
a13f35e8 TH |
680 | |
681 | ret = wb_init(&bdi->wb, bdi, 1, GFP_KERNEL); | |
682 | if (!ret) { | |
7d828602 | 683 | bdi->wb.memcg_css = &root_mem_cgroup->css; |
a13f35e8 TH |
684 | bdi->wb.blkcg_css = blkcg_root_css; |
685 | } | |
686 | return ret; | |
6467716a AB |
687 | } |
688 | ||
b1c51afc | 689 | static void cgwb_bdi_unregister(struct backing_dev_info *bdi) |
52ebea74 TH |
690 | { |
691 | struct radix_tree_iter iter; | |
692 | void **slot; | |
5318ce7d | 693 | struct bdi_writeback *wb; |
52ebea74 TH |
694 | |
695 | WARN_ON(test_bit(WB_registered, &bdi->wb.state)); | |
696 | ||
697 | spin_lock_irq(&cgwb_lock); | |
698 | radix_tree_for_each_slot(slot, &bdi->cgwb_tree, &iter, 0) | |
699 | cgwb_kill(*slot); | |
3ee7e869 | 700 | spin_unlock_irq(&cgwb_lock); |
5318ce7d | 701 | |
3ee7e869 JK |
702 | mutex_lock(&bdi->cgwb_release_mutex); |
703 | spin_lock_irq(&cgwb_lock); | |
5318ce7d JK |
704 | while (!list_empty(&bdi->wb_list)) { |
705 | wb = list_first_entry(&bdi->wb_list, struct bdi_writeback, | |
706 | bdi_node); | |
707 | spin_unlock_irq(&cgwb_lock); | |
708 | wb_shutdown(wb); | |
709 | spin_lock_irq(&cgwb_lock); | |
710 | } | |
52ebea74 | 711 | spin_unlock_irq(&cgwb_lock); |
3ee7e869 | 712 | mutex_unlock(&bdi->cgwb_release_mutex); |
52ebea74 TH |
713 | } |
714 | ||
715 | /** | |
716 | * wb_memcg_offline - kill all wb's associated with a memcg being offlined | |
717 | * @memcg: memcg being offlined | |
718 | * | |
719 | * Also prevents creation of any new wb's associated with @memcg. | |
e98be2d5 | 720 | */ |
52ebea74 TH |
721 | void wb_memcg_offline(struct mem_cgroup *memcg) |
722 | { | |
9ccc3617 | 723 | struct list_head *memcg_cgwb_list = &memcg->cgwb_list; |
52ebea74 TH |
724 | struct bdi_writeback *wb, *next; |
725 | ||
726 | spin_lock_irq(&cgwb_lock); | |
727 | list_for_each_entry_safe(wb, next, memcg_cgwb_list, memcg_node) | |
728 | cgwb_kill(wb); | |
729 | memcg_cgwb_list->next = NULL; /* prevent new wb's */ | |
730 | spin_unlock_irq(&cgwb_lock); | |
731 | } | |
732 | ||
733 | /** | |
734 | * wb_blkcg_offline - kill all wb's associated with a blkcg being offlined | |
735 | * @blkcg: blkcg being offlined | |
736 | * | |
737 | * Also prevents creation of any new wb's associated with @blkcg. | |
738 | */ | |
739 | void wb_blkcg_offline(struct blkcg *blkcg) | |
740 | { | |
52ebea74 TH |
741 | struct bdi_writeback *wb, *next; |
742 | ||
743 | spin_lock_irq(&cgwb_lock); | |
744 | list_for_each_entry_safe(wb, next, &blkcg->cgwb_list, blkcg_node) | |
745 | cgwb_kill(wb); | |
746 | blkcg->cgwb_list.next = NULL; /* prevent new wb's */ | |
747 | spin_unlock_irq(&cgwb_lock); | |
748 | } | |
749 | ||
df23de55 JK |
750 | static void cgwb_bdi_exit(struct backing_dev_info *bdi) |
751 | { | |
752 | struct rb_node *rbn; | |
753 | ||
754 | spin_lock_irq(&cgwb_lock); | |
755 | while ((rbn = rb_first(&bdi->cgwb_congested_tree))) { | |
756 | struct bdi_writeback_congested *congested = | |
757 | rb_entry(rbn, struct bdi_writeback_congested, rb_node); | |
758 | ||
759 | rb_erase(rbn, &bdi->cgwb_congested_tree); | |
b7d680d7 | 760 | congested->__bdi = NULL; /* mark @congested unlinked */ |
df23de55 JK |
761 | } |
762 | spin_unlock_irq(&cgwb_lock); | |
763 | } | |
764 | ||
e8cb72b3 JK |
765 | static void cgwb_bdi_register(struct backing_dev_info *bdi) |
766 | { | |
767 | spin_lock_irq(&cgwb_lock); | |
768 | list_add_tail_rcu(&bdi->wb.bdi_node, &bdi->wb_list); | |
769 | spin_unlock_irq(&cgwb_lock); | |
770 | } | |
771 | ||
f1834646 TH |
772 | static int __init cgwb_init(void) |
773 | { | |
774 | /* | |
775 | * There can be many concurrent release work items overwhelming | |
776 | * system_wq. Put them in a separate wq and limit concurrency. | |
777 | * There's no point in executing many of these in parallel. | |
778 | */ | |
779 | cgwb_release_wq = alloc_workqueue("cgwb_release", 0, 1); | |
780 | if (!cgwb_release_wq) | |
781 | return -ENOMEM; | |
782 | ||
783 | return 0; | |
784 | } | |
785 | subsys_initcall(cgwb_init); | |
786 | ||
52ebea74 TH |
787 | #else /* CONFIG_CGROUP_WRITEBACK */ |
788 | ||
a13f35e8 TH |
789 | static int cgwb_bdi_init(struct backing_dev_info *bdi) |
790 | { | |
791 | int err; | |
792 | ||
793 | bdi->wb_congested = kzalloc(sizeof(*bdi->wb_congested), GFP_KERNEL); | |
794 | if (!bdi->wb_congested) | |
795 | return -ENOMEM; | |
796 | ||
e58dd0de | 797 | refcount_set(&bdi->wb_congested->refcnt, 1); |
5f478e4e | 798 | |
a13f35e8 TH |
799 | err = wb_init(&bdi->wb, bdi, 1, GFP_KERNEL); |
800 | if (err) { | |
5f478e4e | 801 | wb_congested_put(bdi->wb_congested); |
a13f35e8 TH |
802 | return err; |
803 | } | |
804 | return 0; | |
805 | } | |
806 | ||
b1c51afc | 807 | static void cgwb_bdi_unregister(struct backing_dev_info *bdi) { } |
df23de55 JK |
808 | |
809 | static void cgwb_bdi_exit(struct backing_dev_info *bdi) | |
5f478e4e TH |
810 | { |
811 | wb_congested_put(bdi->wb_congested); | |
812 | } | |
52ebea74 | 813 | |
e8cb72b3 JK |
814 | static void cgwb_bdi_register(struct backing_dev_info *bdi) |
815 | { | |
816 | list_add_tail_rcu(&bdi->wb.bdi_node, &bdi->wb_list); | |
817 | } | |
818 | ||
819 | static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb) | |
820 | { | |
821 | list_del_rcu(&wb->bdi_node); | |
822 | } | |
823 | ||
52ebea74 | 824 | #endif /* CONFIG_CGROUP_WRITEBACK */ |
e98be2d5 | 825 | |
2e82b84c | 826 | static int bdi_init(struct backing_dev_info *bdi) |
b2e8fb6e | 827 | { |
b817525a TH |
828 | int ret; |
829 | ||
cf0ca9fe PZ |
830 | bdi->dev = NULL; |
831 | ||
d03f6cdc | 832 | kref_init(&bdi->refcnt); |
189d3c4a | 833 | bdi->min_ratio = 0; |
a42dde04 | 834 | bdi->max_ratio = 100; |
eb608e3a | 835 | bdi->max_prop_frac = FPROP_FRAC_BASE; |
66f3b8e2 | 836 | INIT_LIST_HEAD(&bdi->bdi_list); |
b817525a | 837 | INIT_LIST_HEAD(&bdi->wb_list); |
cc395d7f | 838 | init_waitqueue_head(&bdi->wb_waitq); |
03ba3782 | 839 | |
b817525a TH |
840 | ret = cgwb_bdi_init(bdi); |
841 | ||
b817525a | 842 | return ret; |
b2e8fb6e | 843 | } |
e98be2d5 | 844 | |
d03f6cdc JK |
845 | struct backing_dev_info *bdi_alloc_node(gfp_t gfp_mask, int node_id) |
846 | { | |
847 | struct backing_dev_info *bdi; | |
848 | ||
849 | bdi = kmalloc_node(sizeof(struct backing_dev_info), | |
850 | gfp_mask | __GFP_ZERO, node_id); | |
851 | if (!bdi) | |
852 | return NULL; | |
853 | ||
854 | if (bdi_init(bdi)) { | |
855 | kfree(bdi); | |
856 | return NULL; | |
857 | } | |
858 | return bdi; | |
859 | } | |
62bf42ad | 860 | EXPORT_SYMBOL(bdi_alloc_node); |
d03f6cdc | 861 | |
7c4cc300 | 862 | int bdi_register_va(struct backing_dev_info *bdi, const char *fmt, va_list args) |
46100071 | 863 | { |
46100071 | 864 | struct device *dev; |
e98be2d5 | 865 | |
46100071 TH |
866 | if (bdi->dev) /* The driver needs to use separate queues per device */ |
867 | return 0; | |
e98be2d5 | 868 | |
7c4cc300 | 869 | dev = device_create_vargs(bdi_class, NULL, MKDEV(0, 0), bdi, fmt, args); |
46100071 TH |
870 | if (IS_ERR(dev)) |
871 | return PTR_ERR(dev); | |
04fbfdc1 | 872 | |
e8cb72b3 | 873 | cgwb_bdi_register(bdi); |
46100071 | 874 | bdi->dev = dev; |
b2e8fb6e | 875 | |
6d0e4827 | 876 | bdi_debug_register(bdi, dev_name(dev)); |
46100071 TH |
877 | set_bit(WB_registered, &bdi->wb.state); |
878 | ||
879 | spin_lock_bh(&bdi_lock); | |
880 | list_add_tail_rcu(&bdi->bdi_list, &bdi_list); | |
881 | spin_unlock_bh(&bdi_lock); | |
882 | ||
883 | trace_writeback_bdi_register(bdi); | |
884 | return 0; | |
b2e8fb6e | 885 | } |
baf7a616 JK |
886 | EXPORT_SYMBOL(bdi_register_va); |
887 | ||
7c4cc300 | 888 | int bdi_register(struct backing_dev_info *bdi, const char *fmt, ...) |
baf7a616 JK |
889 | { |
890 | va_list args; | |
891 | int ret; | |
892 | ||
893 | va_start(args, fmt); | |
7c4cc300 | 894 | ret = bdi_register_va(bdi, fmt, args); |
baf7a616 JK |
895 | va_end(args); |
896 | return ret; | |
897 | } | |
46100071 | 898 | EXPORT_SYMBOL(bdi_register); |
b2e8fb6e | 899 | |
df08c32c DW |
900 | int bdi_register_owner(struct backing_dev_info *bdi, struct device *owner) |
901 | { | |
902 | int rc; | |
903 | ||
7c4cc300 | 904 | rc = bdi_register(bdi, "%u:%u", MAJOR(owner->devt), MINOR(owner->devt)); |
df08c32c DW |
905 | if (rc) |
906 | return rc; | |
b6f8fec4 JK |
907 | /* Leaking owner reference... */ |
908 | WARN_ON(bdi->owner); | |
df08c32c DW |
909 | bdi->owner = owner; |
910 | get_device(owner); | |
911 | return 0; | |
912 | } | |
913 | EXPORT_SYMBOL(bdi_register_owner); | |
914 | ||
46100071 TH |
915 | /* |
916 | * Remove bdi from bdi_list, and ensure that it is no longer visible | |
917 | */ | |
918 | static void bdi_remove_from_list(struct backing_dev_info *bdi) | |
919 | { | |
920 | spin_lock_bh(&bdi_lock); | |
921 | list_del_rcu(&bdi->bdi_list); | |
922 | spin_unlock_bh(&bdi_lock); | |
b2e8fb6e | 923 | |
46100071 TH |
924 | synchronize_rcu_expedited(); |
925 | } | |
cf0ca9fe | 926 | |
b02176f3 | 927 | void bdi_unregister(struct backing_dev_info *bdi) |
b2e8fb6e | 928 | { |
f0054bb1 TH |
929 | /* make sure nobody finds us on the bdi_list anymore */ |
930 | bdi_remove_from_list(bdi); | |
931 | wb_shutdown(&bdi->wb); | |
b1c51afc | 932 | cgwb_bdi_unregister(bdi); |
7a401a97 | 933 | |
c4db59d3 CH |
934 | if (bdi->dev) { |
935 | bdi_debug_unregister(bdi); | |
936 | device_unregister(bdi->dev); | |
937 | bdi->dev = NULL; | |
938 | } | |
df08c32c DW |
939 | |
940 | if (bdi->owner) { | |
941 | put_device(bdi->owner); | |
942 | bdi->owner = NULL; | |
943 | } | |
b02176f3 | 944 | } |
c4db59d3 | 945 | |
d03f6cdc JK |
946 | static void release_bdi(struct kref *ref) |
947 | { | |
948 | struct backing_dev_info *bdi = | |
949 | container_of(ref, struct backing_dev_info, refcnt); | |
950 | ||
5af110b2 JK |
951 | if (test_bit(WB_registered, &bdi->wb.state)) |
952 | bdi_unregister(bdi); | |
2e82b84c JK |
953 | WARN_ON_ONCE(bdi->dev); |
954 | wb_exit(&bdi->wb); | |
955 | cgwb_bdi_exit(bdi); | |
d03f6cdc JK |
956 | kfree(bdi); |
957 | } | |
958 | ||
959 | void bdi_put(struct backing_dev_info *bdi) | |
960 | { | |
961 | kref_put(&bdi->refcnt, release_bdi); | |
962 | } | |
62bf42ad | 963 | EXPORT_SYMBOL(bdi_put); |
d03f6cdc | 964 | |
3fcfab16 AM |
965 | static wait_queue_head_t congestion_wqh[2] = { |
966 | __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]), | |
967 | __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1]) | |
968 | }; | |
ec8a6f26 | 969 | static atomic_t nr_wb_congested[2]; |
3fcfab16 | 970 | |
ec8a6f26 | 971 | void clear_wb_congested(struct bdi_writeback_congested *congested, int sync) |
3fcfab16 | 972 | { |
1faa16d2 | 973 | wait_queue_head_t *wqh = &congestion_wqh[sync]; |
c877ef8a | 974 | enum wb_congested_state bit; |
3fcfab16 | 975 | |
4452226e | 976 | bit = sync ? WB_sync_congested : WB_async_congested; |
ec8a6f26 TH |
977 | if (test_and_clear_bit(bit, &congested->state)) |
978 | atomic_dec(&nr_wb_congested[sync]); | |
4e857c58 | 979 | smp_mb__after_atomic(); |
3fcfab16 AM |
980 | if (waitqueue_active(wqh)) |
981 | wake_up(wqh); | |
982 | } | |
ec8a6f26 | 983 | EXPORT_SYMBOL(clear_wb_congested); |
3fcfab16 | 984 | |
ec8a6f26 | 985 | void set_wb_congested(struct bdi_writeback_congested *congested, int sync) |
3fcfab16 | 986 | { |
c877ef8a | 987 | enum wb_congested_state bit; |
3fcfab16 | 988 | |
4452226e | 989 | bit = sync ? WB_sync_congested : WB_async_congested; |
ec8a6f26 TH |
990 | if (!test_and_set_bit(bit, &congested->state)) |
991 | atomic_inc(&nr_wb_congested[sync]); | |
3fcfab16 | 992 | } |
ec8a6f26 | 993 | EXPORT_SYMBOL(set_wb_congested); |
3fcfab16 AM |
994 | |
995 | /** | |
996 | * congestion_wait - wait for a backing_dev to become uncongested | |
8aa7e847 | 997 | * @sync: SYNC or ASYNC IO |
3fcfab16 AM |
998 | * @timeout: timeout in jiffies |
999 | * | |
1000 | * Waits for up to @timeout jiffies for a backing_dev (any backing_dev) to exit | |
1001 | * write congestion. If no backing_devs are congested then just wait for the | |
1002 | * next write to be completed. | |
1003 | */ | |
8aa7e847 | 1004 | long congestion_wait(int sync, long timeout) |
3fcfab16 AM |
1005 | { |
1006 | long ret; | |
52bb9198 | 1007 | unsigned long start = jiffies; |
3fcfab16 | 1008 | DEFINE_WAIT(wait); |
8aa7e847 | 1009 | wait_queue_head_t *wqh = &congestion_wqh[sync]; |
3fcfab16 AM |
1010 | |
1011 | prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); | |
1012 | ret = io_schedule_timeout(timeout); | |
1013 | finish_wait(wqh, &wait); | |
52bb9198 MG |
1014 | |
1015 | trace_writeback_congestion_wait(jiffies_to_usecs(timeout), | |
1016 | jiffies_to_usecs(jiffies - start)); | |
1017 | ||
3fcfab16 AM |
1018 | return ret; |
1019 | } | |
1020 | EXPORT_SYMBOL(congestion_wait); | |
04fbfdc1 | 1021 | |
0e093d99 | 1022 | /** |
599d0c95 | 1023 | * wait_iff_congested - Conditionally wait for a backing_dev to become uncongested or a pgdat to complete writes |
0e093d99 MG |
1024 | * @sync: SYNC or ASYNC IO |
1025 | * @timeout: timeout in jiffies | |
1026 | * | |
e3c1ac58 AR |
1027 | * In the event of a congested backing_dev (any backing_dev) this waits |
1028 | * for up to @timeout jiffies for either a BDI to exit congestion of the | |
1029 | * given @sync queue or a write to complete. | |
0e093d99 MG |
1030 | * |
1031 | * The return value is 0 if the sleep is for the full timeout. Otherwise, | |
1032 | * it is the number of jiffies that were still remaining when the function | |
1033 | * returned. return_value == timeout implies the function did not sleep. | |
1034 | */ | |
e3c1ac58 | 1035 | long wait_iff_congested(int sync, long timeout) |
0e093d99 MG |
1036 | { |
1037 | long ret; | |
1038 | unsigned long start = jiffies; | |
1039 | DEFINE_WAIT(wait); | |
1040 | wait_queue_head_t *wqh = &congestion_wqh[sync]; | |
1041 | ||
1042 | /* | |
e3c1ac58 | 1043 | * If there is no congestion, yield if necessary instead |
0e093d99 MG |
1044 | * of sleeping on the congestion queue |
1045 | */ | |
e3c1ac58 | 1046 | if (atomic_read(&nr_wb_congested[sync]) == 0) { |
ede37713 | 1047 | cond_resched(); |
599d0c95 | 1048 | |
0e093d99 MG |
1049 | /* In case we scheduled, work out time remaining */ |
1050 | ret = timeout - (jiffies - start); | |
1051 | if (ret < 0) | |
1052 | ret = 0; | |
1053 | ||
1054 | goto out; | |
1055 | } | |
1056 | ||
1057 | /* Sleep until uncongested or a write happens */ | |
1058 | prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); | |
1059 | ret = io_schedule_timeout(timeout); | |
1060 | finish_wait(wqh, &wait); | |
1061 | ||
1062 | out: | |
1063 | trace_writeback_wait_iff_congested(jiffies_to_usecs(timeout), | |
1064 | jiffies_to_usecs(jiffies - start)); | |
1065 | ||
1066 | return ret; | |
1067 | } | |
1068 | EXPORT_SYMBOL(wait_iff_congested); |