Commit | Line | Data |
---|---|---|
457c8996 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
3fcfab16 AM |
2 | |
3 | #include <linux/wait.h> | |
34f8fe50 | 4 | #include <linux/rbtree.h> |
3fcfab16 | 5 | #include <linux/backing-dev.h> |
03ba3782 JA |
6 | #include <linux/kthread.h> |
7 | #include <linux/freezer.h> | |
3fcfab16 | 8 | #include <linux/fs.h> |
26160158 | 9 | #include <linux/pagemap.h> |
03ba3782 | 10 | #include <linux/mm.h> |
3fcfab16 AM |
11 | #include <linux/sched.h> |
12 | #include <linux/module.h> | |
cf0ca9fe PZ |
13 | #include <linux/writeback.h> |
14 | #include <linux/device.h> | |
455b2864 | 15 | #include <trace/events/writeback.h> |
cf0ca9fe | 16 | |
5129a469 | 17 | struct backing_dev_info noop_backing_dev_info = { |
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; |
eb7ae5e0 | 23 | static const char *bdi_unknown_name = "(unknown)"; |
cfc4ba53 JA |
24 | |
25 | /* | |
34f8fe50 TH |
26 | * bdi_lock protects bdi_tree and updates to bdi_list. bdi_list has RCU |
27 | * reader side locking. | |
cfc4ba53 | 28 | */ |
03ba3782 | 29 | DEFINE_SPINLOCK(bdi_lock); |
34f8fe50 TH |
30 | static u64 bdi_id_cursor; |
31 | static struct rb_root bdi_tree = RB_ROOT; | |
66f3b8e2 | 32 | LIST_HEAD(bdi_list); |
03ba3782 | 33 | |
839a8e86 TH |
34 | /* bdi_wq serves all asynchronous writeback tasks */ |
35 | struct workqueue_struct *bdi_wq; | |
36 | ||
76f1418b MS |
37 | #ifdef CONFIG_DEBUG_FS |
38 | #include <linux/debugfs.h> | |
39 | #include <linux/seq_file.h> | |
40 | ||
41 | static struct dentry *bdi_debug_root; | |
42 | ||
43 | static void bdi_debug_init(void) | |
44 | { | |
45 | bdi_debug_root = debugfs_create_dir("bdi", NULL); | |
46 | } | |
47 | ||
48 | static int bdi_debug_stats_show(struct seq_file *m, void *v) | |
49 | { | |
50 | struct backing_dev_info *bdi = m->private; | |
c1955ce3 | 51 | struct bdi_writeback *wb = &bdi->wb; |
364aeb28 DR |
52 | unsigned long background_thresh; |
53 | unsigned long dirty_thresh; | |
0d960a38 | 54 | unsigned long wb_thresh; |
0ae45f63 | 55 | unsigned long nr_dirty, nr_io, nr_more_io, nr_dirty_time; |
f09b00d3 JA |
56 | struct inode *inode; |
57 | ||
0ae45f63 | 58 | nr_dirty = nr_io = nr_more_io = nr_dirty_time = 0; |
f758eeab | 59 | spin_lock(&wb->list_lock); |
c7f54084 | 60 | list_for_each_entry(inode, &wb->b_dirty, i_io_list) |
c1955ce3 | 61 | nr_dirty++; |
c7f54084 | 62 | list_for_each_entry(inode, &wb->b_io, i_io_list) |
c1955ce3 | 63 | nr_io++; |
c7f54084 | 64 | list_for_each_entry(inode, &wb->b_more_io, i_io_list) |
c1955ce3 | 65 | nr_more_io++; |
c7f54084 | 66 | list_for_each_entry(inode, &wb->b_dirty_time, i_io_list) |
0ae45f63 TT |
67 | if (inode->i_state & I_DIRTY_TIME) |
68 | nr_dirty_time++; | |
f758eeab | 69 | spin_unlock(&wb->list_lock); |
76f1418b | 70 | |
16c4042f | 71 | global_dirty_limits(&background_thresh, &dirty_thresh); |
0d960a38 | 72 | wb_thresh = wb_calc_thresh(wb, dirty_thresh); |
76f1418b MS |
73 | |
74 | #define K(x) ((x) << (PAGE_SHIFT - 10)) | |
75 | seq_printf(m, | |
00821b00 WF |
76 | "BdiWriteback: %10lu kB\n" |
77 | "BdiReclaimable: %10lu kB\n" | |
78 | "BdiDirtyThresh: %10lu kB\n" | |
79 | "DirtyThresh: %10lu kB\n" | |
80 | "BackgroundThresh: %10lu kB\n" | |
c8e28ce0 | 81 | "BdiDirtied: %10lu kB\n" |
00821b00 WF |
82 | "BdiWritten: %10lu kB\n" |
83 | "BdiWriteBandwidth: %10lu kBps\n" | |
84 | "b_dirty: %10lu\n" | |
85 | "b_io: %10lu\n" | |
86 | "b_more_io: %10lu\n" | |
0ae45f63 | 87 | "b_dirty_time: %10lu\n" |
00821b00 WF |
88 | "bdi_list: %10u\n" |
89 | "state: %10lx\n", | |
93f78d88 TH |
90 | (unsigned long) K(wb_stat(wb, WB_WRITEBACK)), |
91 | (unsigned long) K(wb_stat(wb, WB_RECLAIMABLE)), | |
0d960a38 | 92 | K(wb_thresh), |
f7d2b1ec JK |
93 | K(dirty_thresh), |
94 | K(background_thresh), | |
93f78d88 TH |
95 | (unsigned long) K(wb_stat(wb, WB_DIRTIED)), |
96 | (unsigned long) K(wb_stat(wb, WB_WRITTEN)), | |
a88a341a | 97 | (unsigned long) K(wb->write_bandwidth), |
f7d2b1ec JK |
98 | nr_dirty, |
99 | nr_io, | |
100 | nr_more_io, | |
0ae45f63 | 101 | nr_dirty_time, |
4452226e | 102 | !list_empty(&bdi->bdi_list), bdi->wb.state); |
76f1418b MS |
103 | #undef K |
104 | ||
105 | return 0; | |
106 | } | |
5ad35093 | 107 | DEFINE_SHOW_ATTRIBUTE(bdi_debug_stats); |
76f1418b | 108 | |
2d146b92 | 109 | static void bdi_debug_register(struct backing_dev_info *bdi, const char *name) |
76f1418b MS |
110 | { |
111 | bdi->debug_dir = debugfs_create_dir(name, bdi_debug_root); | |
97f07697 | 112 | |
2d146b92 GKH |
113 | debugfs_create_file("stats", 0444, bdi->debug_dir, bdi, |
114 | &bdi_debug_stats_fops); | |
76f1418b MS |
115 | } |
116 | ||
117 | static void bdi_debug_unregister(struct backing_dev_info *bdi) | |
118 | { | |
2d146b92 | 119 | debugfs_remove_recursive(bdi->debug_dir); |
76f1418b MS |
120 | } |
121 | #else | |
122 | static inline void bdi_debug_init(void) | |
123 | { | |
124 | } | |
2d146b92 | 125 | static inline void bdi_debug_register(struct backing_dev_info *bdi, |
76f1418b MS |
126 | const char *name) |
127 | { | |
128 | } | |
129 | static inline void bdi_debug_unregister(struct backing_dev_info *bdi) | |
130 | { | |
131 | } | |
132 | #endif | |
133 | ||
cf0ca9fe PZ |
134 | static ssize_t read_ahead_kb_store(struct device *dev, |
135 | struct device_attribute *attr, | |
136 | const char *buf, size_t count) | |
137 | { | |
138 | struct backing_dev_info *bdi = dev_get_drvdata(dev); | |
cf0ca9fe | 139 | unsigned long read_ahead_kb; |
7034ed13 | 140 | ssize_t ret; |
cf0ca9fe | 141 | |
7034ed13 NJ |
142 | ret = kstrtoul(buf, 10, &read_ahead_kb); |
143 | if (ret < 0) | |
144 | return ret; | |
145 | ||
146 | bdi->ra_pages = read_ahead_kb >> (PAGE_SHIFT - 10); | |
147 | ||
148 | return count; | |
cf0ca9fe PZ |
149 | } |
150 | ||
151 | #define K(pages) ((pages) << (PAGE_SHIFT - 10)) | |
152 | ||
153 | #define BDI_SHOW(name, expr) \ | |
154 | static ssize_t name##_show(struct device *dev, \ | |
155 | struct device_attribute *attr, char *page) \ | |
156 | { \ | |
157 | struct backing_dev_info *bdi = dev_get_drvdata(dev); \ | |
158 | \ | |
159 | return snprintf(page, PAGE_SIZE-1, "%lld\n", (long long)expr); \ | |
d9e1241e GKH |
160 | } \ |
161 | static DEVICE_ATTR_RW(name); | |
cf0ca9fe PZ |
162 | |
163 | BDI_SHOW(read_ahead_kb, K(bdi->ra_pages)) | |
164 | ||
189d3c4a PZ |
165 | static ssize_t min_ratio_store(struct device *dev, |
166 | struct device_attribute *attr, const char *buf, size_t count) | |
167 | { | |
168 | struct backing_dev_info *bdi = dev_get_drvdata(dev); | |
189d3c4a | 169 | unsigned int ratio; |
7034ed13 NJ |
170 | ssize_t ret; |
171 | ||
172 | ret = kstrtouint(buf, 10, &ratio); | |
173 | if (ret < 0) | |
174 | return ret; | |
175 | ||
176 | ret = bdi_set_min_ratio(bdi, ratio); | |
177 | if (!ret) | |
178 | ret = count; | |
189d3c4a | 179 | |
189d3c4a PZ |
180 | return ret; |
181 | } | |
182 | BDI_SHOW(min_ratio, bdi->min_ratio) | |
183 | ||
a42dde04 PZ |
184 | static ssize_t max_ratio_store(struct device *dev, |
185 | struct device_attribute *attr, const char *buf, size_t count) | |
186 | { | |
187 | struct backing_dev_info *bdi = dev_get_drvdata(dev); | |
a42dde04 | 188 | unsigned int ratio; |
7034ed13 NJ |
189 | ssize_t ret; |
190 | ||
191 | ret = kstrtouint(buf, 10, &ratio); | |
192 | if (ret < 0) | |
193 | return ret; | |
194 | ||
195 | ret = bdi_set_max_ratio(bdi, ratio); | |
196 | if (!ret) | |
197 | ret = count; | |
a42dde04 | 198 | |
a42dde04 PZ |
199 | return ret; |
200 | } | |
201 | BDI_SHOW(max_ratio, bdi->max_ratio) | |
202 | ||
7d311cda DW |
203 | static ssize_t stable_pages_required_show(struct device *dev, |
204 | struct device_attribute *attr, | |
205 | char *page) | |
206 | { | |
207 | struct backing_dev_info *bdi = dev_get_drvdata(dev); | |
208 | ||
209 | return snprintf(page, PAGE_SIZE-1, "%d\n", | |
210 | bdi_cap_stable_pages_required(bdi) ? 1 : 0); | |
211 | } | |
d9e1241e GKH |
212 | static DEVICE_ATTR_RO(stable_pages_required); |
213 | ||
214 | static struct attribute *bdi_dev_attrs[] = { | |
215 | &dev_attr_read_ahead_kb.attr, | |
216 | &dev_attr_min_ratio.attr, | |
217 | &dev_attr_max_ratio.attr, | |
218 | &dev_attr_stable_pages_required.attr, | |
219 | NULL, | |
cf0ca9fe | 220 | }; |
d9e1241e | 221 | ATTRIBUTE_GROUPS(bdi_dev); |
cf0ca9fe PZ |
222 | |
223 | static __init int bdi_class_init(void) | |
224 | { | |
225 | bdi_class = class_create(THIS_MODULE, "bdi"); | |
14421453 AB |
226 | if (IS_ERR(bdi_class)) |
227 | return PTR_ERR(bdi_class); | |
228 | ||
d9e1241e | 229 | bdi_class->dev_groups = bdi_dev_groups; |
76f1418b | 230 | bdi_debug_init(); |
d03f6cdc | 231 | |
cf0ca9fe PZ |
232 | return 0; |
233 | } | |
76f1418b | 234 | postcore_initcall(bdi_class_init); |
cf0ca9fe | 235 | |
2e82b84c JK |
236 | static int bdi_init(struct backing_dev_info *bdi); |
237 | ||
26160158 JA |
238 | static int __init default_bdi_init(void) |
239 | { | |
240 | int err; | |
241 | ||
a2b90f11 MW |
242 | bdi_wq = alloc_workqueue("writeback", WQ_MEM_RECLAIM | WQ_UNBOUND | |
243 | WQ_SYSFS, 0); | |
839a8e86 TH |
244 | if (!bdi_wq) |
245 | return -ENOMEM; | |
246 | ||
976e48f8 | 247 | err = bdi_init(&noop_backing_dev_info); |
26160158 JA |
248 | |
249 | return err; | |
250 | } | |
251 | subsys_initcall(default_bdi_init); | |
252 | ||
6467716a | 253 | /* |
f0054bb1 | 254 | * This function is used when the first inode for this wb is marked dirty. It |
6467716a AB |
255 | * wakes-up the corresponding bdi thread which should then take care of the |
256 | * periodic background write-out of dirty inodes. Since the write-out would | |
257 | * starts only 'dirty_writeback_interval' centisecs from now anyway, we just | |
258 | * set up a timer which wakes the bdi thread up later. | |
259 | * | |
260 | * Note, we wouldn't bother setting up the timer, but this function is on the | |
261 | * fast-path (used by '__mark_inode_dirty()'), so we save few context switches | |
262 | * by delaying the wake-up. | |
6ca738d6 DB |
263 | * |
264 | * We have to be careful not to postpone flush work if it is scheduled for | |
265 | * earlier. Thus we use queue_delayed_work(). | |
6467716a | 266 | */ |
f0054bb1 | 267 | void wb_wakeup_delayed(struct bdi_writeback *wb) |
6467716a AB |
268 | { |
269 | unsigned long timeout; | |
270 | ||
271 | timeout = msecs_to_jiffies(dirty_writeback_interval * 10); | |
f0054bb1 TH |
272 | spin_lock_bh(&wb->work_lock); |
273 | if (test_bit(WB_registered, &wb->state)) | |
274 | queue_delayed_work(bdi_wq, &wb->dwork, timeout); | |
275 | spin_unlock_bh(&wb->work_lock); | |
03ba3782 JA |
276 | } |
277 | ||
cfc4ba53 | 278 | /* |
a88a341a | 279 | * Initial write bandwidth: 100 MB/s |
cfc4ba53 | 280 | */ |
a88a341a | 281 | #define INIT_BW (100 << (20 - PAGE_SHIFT)) |
cfc4ba53 | 282 | |
8395cd9f | 283 | static int wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi, |
8c911f3d | 284 | gfp_t gfp) |
cf0ca9fe | 285 | { |
93f78d88 | 286 | int i, err; |
cf0ca9fe | 287 | |
6467716a | 288 | memset(wb, 0, sizeof(*wb)); |
f1d0b063 | 289 | |
810df54a JK |
290 | if (wb != &bdi->wb) |
291 | bdi_get(bdi); | |
6467716a AB |
292 | wb->bdi = bdi; |
293 | wb->last_old_flush = jiffies; | |
294 | INIT_LIST_HEAD(&wb->b_dirty); | |
295 | INIT_LIST_HEAD(&wb->b_io); | |
296 | INIT_LIST_HEAD(&wb->b_more_io); | |
0ae45f63 | 297 | INIT_LIST_HEAD(&wb->b_dirty_time); |
f758eeab | 298 | spin_lock_init(&wb->list_lock); |
66f3b8e2 | 299 | |
a88a341a TH |
300 | wb->bw_time_stamp = jiffies; |
301 | wb->balanced_dirty_ratelimit = INIT_BW; | |
302 | wb->dirty_ratelimit = INIT_BW; | |
303 | wb->write_bandwidth = INIT_BW; | |
304 | wb->avg_write_bandwidth = INIT_BW; | |
cf0ca9fe | 305 | |
f0054bb1 TH |
306 | spin_lock_init(&wb->work_lock); |
307 | INIT_LIST_HEAD(&wb->work_list); | |
308 | INIT_DELAYED_WORK(&wb->dwork, wb_workfn); | |
b57d74af | 309 | wb->dirty_sleep = jiffies; |
c284de61 | 310 | |
8395cd9f | 311 | err = fprop_local_init_percpu(&wb->completions, gfp); |
a88a341a | 312 | if (err) |
8c911f3d | 313 | goto out_put_bdi; |
c284de61 | 314 | |
93f78d88 | 315 | for (i = 0; i < NR_WB_STAT_ITEMS; i++) { |
8395cd9f | 316 | err = percpu_counter_init(&wb->stat[i], 0, gfp); |
a13f35e8 TH |
317 | if (err) |
318 | goto out_destroy_stat; | |
93f78d88 | 319 | } |
cf0ca9fe | 320 | |
93f78d88 | 321 | return 0; |
a13f35e8 TH |
322 | |
323 | out_destroy_stat: | |
078c6c3a | 324 | while (i--) |
a13f35e8 TH |
325 | percpu_counter_destroy(&wb->stat[i]); |
326 | fprop_local_destroy_percpu(&wb->completions); | |
810df54a JK |
327 | out_put_bdi: |
328 | if (wb != &bdi->wb) | |
329 | bdi_put(bdi); | |
a13f35e8 | 330 | return err; |
cf0ca9fe | 331 | } |
cf0ca9fe | 332 | |
e8cb72b3 JK |
333 | static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb); |
334 | ||
03ba3782 JA |
335 | /* |
336 | * Remove bdi from the global list and shutdown any threads we have running | |
337 | */ | |
46100071 | 338 | static void wb_shutdown(struct bdi_writeback *wb) |
66f3b8e2 | 339 | { |
c4db59d3 | 340 | /* Make sure nobody queues further work */ |
46100071 TH |
341 | spin_lock_bh(&wb->work_lock); |
342 | if (!test_and_clear_bit(WB_registered, &wb->state)) { | |
343 | spin_unlock_bh(&wb->work_lock); | |
03ba3782 | 344 | return; |
c4db59d3 | 345 | } |
46100071 | 346 | spin_unlock_bh(&wb->work_lock); |
03ba3782 | 347 | |
e8cb72b3 | 348 | cgwb_remove_from_bdi_list(wb); |
03ba3782 | 349 | /* |
46100071 TH |
350 | * Drain work list and shutdown the delayed_work. !WB_registered |
351 | * tells wb_workfn() that @wb is dying and its work_list needs to | |
352 | * be drained no matter what. | |
03ba3782 | 353 | */ |
46100071 TH |
354 | mod_delayed_work(bdi_wq, &wb->dwork, 0); |
355 | flush_delayed_work(&wb->dwork); | |
356 | WARN_ON(!list_empty(&wb->work_list)); | |
357 | } | |
358 | ||
f0054bb1 | 359 | static void wb_exit(struct bdi_writeback *wb) |
93f78d88 TH |
360 | { |
361 | int i; | |
362 | ||
363 | WARN_ON(delayed_work_pending(&wb->dwork)); | |
364 | ||
365 | for (i = 0; i < NR_WB_STAT_ITEMS; i++) | |
366 | percpu_counter_destroy(&wb->stat[i]); | |
6467716a | 367 | |
a88a341a | 368 | fprop_local_destroy_percpu(&wb->completions); |
810df54a JK |
369 | if (wb != &wb->bdi->wb) |
370 | bdi_put(wb->bdi); | |
a88a341a | 371 | } |
e98be2d5 | 372 | |
52ebea74 TH |
373 | #ifdef CONFIG_CGROUP_WRITEBACK |
374 | ||
375 | #include <linux/memcontrol.h> | |
376 | ||
377 | /* | |
8c911f3d CH |
378 | * cgwb_lock protects bdi->cgwb_tree, blkcg->cgwb_list, and memcg->cgwb_list. |
379 | * bdi->cgwb_tree is also RCU protected. | |
52ebea74 TH |
380 | */ |
381 | static DEFINE_SPINLOCK(cgwb_lock); | |
f1834646 | 382 | static struct workqueue_struct *cgwb_release_wq; |
52ebea74 | 383 | |
52ebea74 TH |
384 | static void cgwb_release_workfn(struct work_struct *work) |
385 | { | |
386 | struct bdi_writeback *wb = container_of(work, struct bdi_writeback, | |
387 | release_work); | |
59b57717 | 388 | struct blkcg *blkcg = css_to_blkcg(wb->blkcg_css); |
52ebea74 | 389 | |
3ee7e869 | 390 | mutex_lock(&wb->bdi->cgwb_release_mutex); |
52ebea74 TH |
391 | wb_shutdown(wb); |
392 | ||
393 | css_put(wb->memcg_css); | |
394 | css_put(wb->blkcg_css); | |
3ee7e869 | 395 | mutex_unlock(&wb->bdi->cgwb_release_mutex); |
52ebea74 | 396 | |
d866dbf6 TH |
397 | /* triggers blkg destruction if no online users left */ |
398 | blkcg_unpin_online(blkcg); | |
59b57717 | 399 | |
841710aa | 400 | fprop_local_destroy_percpu(&wb->memcg_completions); |
52ebea74 TH |
401 | percpu_ref_exit(&wb->refcnt); |
402 | wb_exit(wb); | |
403 | kfree_rcu(wb, rcu); | |
52ebea74 TH |
404 | } |
405 | ||
406 | static void cgwb_release(struct percpu_ref *refcnt) | |
407 | { | |
408 | struct bdi_writeback *wb = container_of(refcnt, struct bdi_writeback, | |
409 | refcnt); | |
f1834646 | 410 | queue_work(cgwb_release_wq, &wb->release_work); |
52ebea74 TH |
411 | } |
412 | ||
413 | static void cgwb_kill(struct bdi_writeback *wb) | |
414 | { | |
415 | lockdep_assert_held(&cgwb_lock); | |
416 | ||
417 | WARN_ON(!radix_tree_delete(&wb->bdi->cgwb_tree, wb->memcg_css->id)); | |
418 | list_del(&wb->memcg_node); | |
419 | list_del(&wb->blkcg_node); | |
420 | percpu_ref_kill(&wb->refcnt); | |
421 | } | |
422 | ||
e8cb72b3 JK |
423 | static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb) |
424 | { | |
425 | spin_lock_irq(&cgwb_lock); | |
426 | list_del_rcu(&wb->bdi_node); | |
427 | spin_unlock_irq(&cgwb_lock); | |
428 | } | |
429 | ||
52ebea74 TH |
430 | static int cgwb_create(struct backing_dev_info *bdi, |
431 | struct cgroup_subsys_state *memcg_css, gfp_t gfp) | |
432 | { | |
433 | struct mem_cgroup *memcg; | |
434 | struct cgroup_subsys_state *blkcg_css; | |
435 | struct blkcg *blkcg; | |
436 | struct list_head *memcg_cgwb_list, *blkcg_cgwb_list; | |
437 | struct bdi_writeback *wb; | |
438 | unsigned long flags; | |
439 | int ret = 0; | |
440 | ||
441 | memcg = mem_cgroup_from_css(memcg_css); | |
c165b3e3 | 442 | blkcg_css = cgroup_get_e_css(memcg_css->cgroup, &io_cgrp_subsys); |
52ebea74 | 443 | blkcg = css_to_blkcg(blkcg_css); |
9ccc3617 | 444 | memcg_cgwb_list = &memcg->cgwb_list; |
52ebea74 TH |
445 | blkcg_cgwb_list = &blkcg->cgwb_list; |
446 | ||
447 | /* look up again under lock and discard on blkcg mismatch */ | |
448 | spin_lock_irqsave(&cgwb_lock, flags); | |
449 | wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id); | |
450 | if (wb && wb->blkcg_css != blkcg_css) { | |
451 | cgwb_kill(wb); | |
452 | wb = NULL; | |
453 | } | |
454 | spin_unlock_irqrestore(&cgwb_lock, flags); | |
455 | if (wb) | |
456 | goto out_put; | |
457 | ||
458 | /* need to create a new one */ | |
459 | wb = kmalloc(sizeof(*wb), gfp); | |
0b045bd1 CJ |
460 | if (!wb) { |
461 | ret = -ENOMEM; | |
462 | goto out_put; | |
463 | } | |
52ebea74 | 464 | |
8c911f3d | 465 | ret = wb_init(wb, bdi, gfp); |
52ebea74 TH |
466 | if (ret) |
467 | goto err_free; | |
468 | ||
469 | ret = percpu_ref_init(&wb->refcnt, cgwb_release, 0, gfp); | |
470 | if (ret) | |
471 | goto err_wb_exit; | |
472 | ||
841710aa TH |
473 | ret = fprop_local_init_percpu(&wb->memcg_completions, gfp); |
474 | if (ret) | |
475 | goto err_ref_exit; | |
476 | ||
52ebea74 TH |
477 | wb->memcg_css = memcg_css; |
478 | wb->blkcg_css = blkcg_css; | |
479 | INIT_WORK(&wb->release_work, cgwb_release_workfn); | |
480 | set_bit(WB_registered, &wb->state); | |
03ba3782 JA |
481 | |
482 | /* | |
52ebea74 TH |
483 | * The root wb determines the registered state of the whole bdi and |
484 | * memcg_cgwb_list and blkcg_cgwb_list's next pointers indicate | |
485 | * whether they're still online. Don't link @wb if any is dead. | |
486 | * See wb_memcg_offline() and wb_blkcg_offline(). | |
03ba3782 | 487 | */ |
52ebea74 TH |
488 | ret = -ENODEV; |
489 | spin_lock_irqsave(&cgwb_lock, flags); | |
490 | if (test_bit(WB_registered, &bdi->wb.state) && | |
491 | blkcg_cgwb_list->next && memcg_cgwb_list->next) { | |
492 | /* we might have raced another instance of this function */ | |
493 | ret = radix_tree_insert(&bdi->cgwb_tree, memcg_css->id, wb); | |
494 | if (!ret) { | |
b817525a | 495 | list_add_tail_rcu(&wb->bdi_node, &bdi->wb_list); |
52ebea74 TH |
496 | list_add(&wb->memcg_node, memcg_cgwb_list); |
497 | list_add(&wb->blkcg_node, blkcg_cgwb_list); | |
d866dbf6 | 498 | blkcg_pin_online(blkcg); |
52ebea74 TH |
499 | css_get(memcg_css); |
500 | css_get(blkcg_css); | |
501 | } | |
502 | } | |
503 | spin_unlock_irqrestore(&cgwb_lock, flags); | |
504 | if (ret) { | |
505 | if (ret == -EEXIST) | |
506 | ret = 0; | |
a13f35e8 | 507 | goto err_fprop_exit; |
52ebea74 TH |
508 | } |
509 | goto out_put; | |
510 | ||
841710aa TH |
511 | err_fprop_exit: |
512 | fprop_local_destroy_percpu(&wb->memcg_completions); | |
52ebea74 TH |
513 | err_ref_exit: |
514 | percpu_ref_exit(&wb->refcnt); | |
515 | err_wb_exit: | |
516 | wb_exit(wb); | |
517 | err_free: | |
518 | kfree(wb); | |
519 | out_put: | |
520 | css_put(blkcg_css); | |
521 | return ret; | |
66f3b8e2 JA |
522 | } |
523 | ||
52ebea74 | 524 | /** |
ed288dc0 | 525 | * wb_get_lookup - get wb for a given memcg |
52ebea74 TH |
526 | * @bdi: target bdi |
527 | * @memcg_css: cgroup_subsys_state of the target memcg (must have positive ref) | |
52ebea74 | 528 | * |
ed288dc0 TH |
529 | * Try to get the wb for @memcg_css on @bdi. The returned wb has its |
530 | * refcount incremented. | |
52ebea74 TH |
531 | * |
532 | * This function uses css_get() on @memcg_css and thus expects its refcnt | |
533 | * to be positive on invocation. IOW, rcu_read_lock() protection on | |
534 | * @memcg_css isn't enough. try_get it before calling this function. | |
535 | * | |
536 | * A wb is keyed by its associated memcg. As blkcg implicitly enables | |
537 | * memcg on the default hierarchy, memcg association is guaranteed to be | |
538 | * more specific (equal or descendant to the associated blkcg) and thus can | |
539 | * identify both the memcg and blkcg associations. | |
540 | * | |
541 | * Because the blkcg associated with a memcg may change as blkcg is enabled | |
542 | * and disabled closer to root in the hierarchy, each wb keeps track of | |
543 | * both the memcg and blkcg associated with it and verifies the blkcg on | |
544 | * each lookup. On mismatch, the existing wb is discarded and a new one is | |
545 | * created. | |
546 | */ | |
ed288dc0 TH |
547 | struct bdi_writeback *wb_get_lookup(struct backing_dev_info *bdi, |
548 | struct cgroup_subsys_state *memcg_css) | |
549 | { | |
550 | struct bdi_writeback *wb; | |
551 | ||
552 | if (!memcg_css->parent) | |
553 | return &bdi->wb; | |
554 | ||
555 | rcu_read_lock(); | |
556 | wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id); | |
557 | if (wb) { | |
558 | struct cgroup_subsys_state *blkcg_css; | |
559 | ||
560 | /* see whether the blkcg association has changed */ | |
561 | blkcg_css = cgroup_get_e_css(memcg_css->cgroup, &io_cgrp_subsys); | |
562 | if (unlikely(wb->blkcg_css != blkcg_css || !wb_tryget(wb))) | |
563 | wb = NULL; | |
564 | css_put(blkcg_css); | |
565 | } | |
566 | rcu_read_unlock(); | |
567 | ||
568 | return wb; | |
569 | } | |
570 | ||
571 | /** | |
572 | * wb_get_create - get wb for a given memcg, create if necessary | |
573 | * @bdi: target bdi | |
574 | * @memcg_css: cgroup_subsys_state of the target memcg (must have positive ref) | |
575 | * @gfp: allocation mask to use | |
576 | * | |
577 | * Try to get the wb for @memcg_css on @bdi. If it doesn't exist, try to | |
578 | * create one. See wb_get_lookup() for more details. | |
579 | */ | |
52ebea74 TH |
580 | struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi, |
581 | struct cgroup_subsys_state *memcg_css, | |
582 | gfp_t gfp) | |
6467716a | 583 | { |
52ebea74 TH |
584 | struct bdi_writeback *wb; |
585 | ||
d0164adc | 586 | might_sleep_if(gfpflags_allow_blocking(gfp)); |
52ebea74 TH |
587 | |
588 | if (!memcg_css->parent) | |
589 | return &bdi->wb; | |
590 | ||
591 | do { | |
ed288dc0 | 592 | wb = wb_get_lookup(bdi, memcg_css); |
52ebea74 TH |
593 | } while (!wb && !cgwb_create(bdi, memcg_css, gfp)); |
594 | ||
595 | return wb; | |
596 | } | |
6467716a | 597 | |
a13f35e8 | 598 | static int cgwb_bdi_init(struct backing_dev_info *bdi) |
52ebea74 | 599 | { |
a13f35e8 TH |
600 | int ret; |
601 | ||
52ebea74 | 602 | INIT_RADIX_TREE(&bdi->cgwb_tree, GFP_ATOMIC); |
3ee7e869 | 603 | mutex_init(&bdi->cgwb_release_mutex); |
7fc5854f | 604 | init_rwsem(&bdi->wb_switch_rwsem); |
a13f35e8 | 605 | |
8c911f3d | 606 | ret = wb_init(&bdi->wb, bdi, GFP_KERNEL); |
a13f35e8 | 607 | if (!ret) { |
7d828602 | 608 | bdi->wb.memcg_css = &root_mem_cgroup->css; |
a13f35e8 TH |
609 | bdi->wb.blkcg_css = blkcg_root_css; |
610 | } | |
611 | return ret; | |
6467716a AB |
612 | } |
613 | ||
b1c51afc | 614 | static void cgwb_bdi_unregister(struct backing_dev_info *bdi) |
52ebea74 TH |
615 | { |
616 | struct radix_tree_iter iter; | |
617 | void **slot; | |
5318ce7d | 618 | struct bdi_writeback *wb; |
52ebea74 TH |
619 | |
620 | WARN_ON(test_bit(WB_registered, &bdi->wb.state)); | |
621 | ||
622 | spin_lock_irq(&cgwb_lock); | |
623 | radix_tree_for_each_slot(slot, &bdi->cgwb_tree, &iter, 0) | |
624 | cgwb_kill(*slot); | |
3ee7e869 | 625 | spin_unlock_irq(&cgwb_lock); |
5318ce7d | 626 | |
3ee7e869 JK |
627 | mutex_lock(&bdi->cgwb_release_mutex); |
628 | spin_lock_irq(&cgwb_lock); | |
5318ce7d JK |
629 | while (!list_empty(&bdi->wb_list)) { |
630 | wb = list_first_entry(&bdi->wb_list, struct bdi_writeback, | |
631 | bdi_node); | |
632 | spin_unlock_irq(&cgwb_lock); | |
633 | wb_shutdown(wb); | |
634 | spin_lock_irq(&cgwb_lock); | |
635 | } | |
52ebea74 | 636 | spin_unlock_irq(&cgwb_lock); |
3ee7e869 | 637 | mutex_unlock(&bdi->cgwb_release_mutex); |
52ebea74 TH |
638 | } |
639 | ||
640 | /** | |
641 | * wb_memcg_offline - kill all wb's associated with a memcg being offlined | |
642 | * @memcg: memcg being offlined | |
643 | * | |
644 | * Also prevents creation of any new wb's associated with @memcg. | |
e98be2d5 | 645 | */ |
52ebea74 TH |
646 | void wb_memcg_offline(struct mem_cgroup *memcg) |
647 | { | |
9ccc3617 | 648 | struct list_head *memcg_cgwb_list = &memcg->cgwb_list; |
52ebea74 TH |
649 | struct bdi_writeback *wb, *next; |
650 | ||
651 | spin_lock_irq(&cgwb_lock); | |
652 | list_for_each_entry_safe(wb, next, memcg_cgwb_list, memcg_node) | |
653 | cgwb_kill(wb); | |
654 | memcg_cgwb_list->next = NULL; /* prevent new wb's */ | |
655 | spin_unlock_irq(&cgwb_lock); | |
656 | } | |
657 | ||
658 | /** | |
659 | * wb_blkcg_offline - kill all wb's associated with a blkcg being offlined | |
660 | * @blkcg: blkcg being offlined | |
661 | * | |
662 | * Also prevents creation of any new wb's associated with @blkcg. | |
663 | */ | |
664 | void wb_blkcg_offline(struct blkcg *blkcg) | |
665 | { | |
52ebea74 TH |
666 | struct bdi_writeback *wb, *next; |
667 | ||
668 | spin_lock_irq(&cgwb_lock); | |
669 | list_for_each_entry_safe(wb, next, &blkcg->cgwb_list, blkcg_node) | |
670 | cgwb_kill(wb); | |
671 | blkcg->cgwb_list.next = NULL; /* prevent new wb's */ | |
672 | spin_unlock_irq(&cgwb_lock); | |
673 | } | |
674 | ||
e8cb72b3 JK |
675 | static void cgwb_bdi_register(struct backing_dev_info *bdi) |
676 | { | |
677 | spin_lock_irq(&cgwb_lock); | |
678 | list_add_tail_rcu(&bdi->wb.bdi_node, &bdi->wb_list); | |
679 | spin_unlock_irq(&cgwb_lock); | |
680 | } | |
681 | ||
f1834646 TH |
682 | static int __init cgwb_init(void) |
683 | { | |
684 | /* | |
685 | * There can be many concurrent release work items overwhelming | |
686 | * system_wq. Put them in a separate wq and limit concurrency. | |
687 | * There's no point in executing many of these in parallel. | |
688 | */ | |
689 | cgwb_release_wq = alloc_workqueue("cgwb_release", 0, 1); | |
690 | if (!cgwb_release_wq) | |
691 | return -ENOMEM; | |
692 | ||
693 | return 0; | |
694 | } | |
695 | subsys_initcall(cgwb_init); | |
696 | ||
52ebea74 TH |
697 | #else /* CONFIG_CGROUP_WRITEBACK */ |
698 | ||
a13f35e8 TH |
699 | static int cgwb_bdi_init(struct backing_dev_info *bdi) |
700 | { | |
8c911f3d | 701 | return wb_init(&bdi->wb, bdi, GFP_KERNEL); |
a13f35e8 TH |
702 | } |
703 | ||
b1c51afc | 704 | static void cgwb_bdi_unregister(struct backing_dev_info *bdi) { } |
df23de55 | 705 | |
e8cb72b3 JK |
706 | static void cgwb_bdi_register(struct backing_dev_info *bdi) |
707 | { | |
708 | list_add_tail_rcu(&bdi->wb.bdi_node, &bdi->wb_list); | |
709 | } | |
710 | ||
711 | static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb) | |
712 | { | |
713 | list_del_rcu(&wb->bdi_node); | |
714 | } | |
715 | ||
52ebea74 | 716 | #endif /* CONFIG_CGROUP_WRITEBACK */ |
e98be2d5 | 717 | |
2e82b84c | 718 | static int bdi_init(struct backing_dev_info *bdi) |
b2e8fb6e | 719 | { |
b817525a TH |
720 | int ret; |
721 | ||
cf0ca9fe PZ |
722 | bdi->dev = NULL; |
723 | ||
d03f6cdc | 724 | kref_init(&bdi->refcnt); |
189d3c4a | 725 | bdi->min_ratio = 0; |
a42dde04 | 726 | bdi->max_ratio = 100; |
eb608e3a | 727 | bdi->max_prop_frac = FPROP_FRAC_BASE; |
66f3b8e2 | 728 | INIT_LIST_HEAD(&bdi->bdi_list); |
b817525a | 729 | INIT_LIST_HEAD(&bdi->wb_list); |
cc395d7f | 730 | init_waitqueue_head(&bdi->wb_waitq); |
03ba3782 | 731 | |
b817525a TH |
732 | ret = cgwb_bdi_init(bdi); |
733 | ||
b817525a | 734 | return ret; |
b2e8fb6e | 735 | } |
e98be2d5 | 736 | |
aef33c2f | 737 | struct backing_dev_info *bdi_alloc(int node_id) |
d03f6cdc JK |
738 | { |
739 | struct backing_dev_info *bdi; | |
740 | ||
aef33c2f | 741 | bdi = kzalloc_node(sizeof(*bdi), GFP_KERNEL, node_id); |
d03f6cdc JK |
742 | if (!bdi) |
743 | return NULL; | |
744 | ||
745 | if (bdi_init(bdi)) { | |
746 | kfree(bdi); | |
747 | return NULL; | |
748 | } | |
749 | return bdi; | |
750 | } | |
aef33c2f | 751 | EXPORT_SYMBOL(bdi_alloc); |
d03f6cdc | 752 | |
34f8fe50 TH |
753 | static struct rb_node **bdi_lookup_rb_node(u64 id, struct rb_node **parentp) |
754 | { | |
755 | struct rb_node **p = &bdi_tree.rb_node; | |
756 | struct rb_node *parent = NULL; | |
757 | struct backing_dev_info *bdi; | |
758 | ||
759 | lockdep_assert_held(&bdi_lock); | |
760 | ||
761 | while (*p) { | |
762 | parent = *p; | |
763 | bdi = rb_entry(parent, struct backing_dev_info, rb_node); | |
764 | ||
765 | if (bdi->id > id) | |
766 | p = &(*p)->rb_left; | |
767 | else if (bdi->id < id) | |
768 | p = &(*p)->rb_right; | |
769 | else | |
770 | break; | |
771 | } | |
772 | ||
773 | if (parentp) | |
774 | *parentp = parent; | |
775 | return p; | |
776 | } | |
777 | ||
778 | /** | |
779 | * bdi_get_by_id - lookup and get bdi from its id | |
780 | * @id: bdi id to lookup | |
781 | * | |
782 | * Find bdi matching @id and get it. Returns NULL if the matching bdi | |
783 | * doesn't exist or is already unregistered. | |
784 | */ | |
785 | struct backing_dev_info *bdi_get_by_id(u64 id) | |
786 | { | |
787 | struct backing_dev_info *bdi = NULL; | |
788 | struct rb_node **p; | |
789 | ||
790 | spin_lock_bh(&bdi_lock); | |
791 | p = bdi_lookup_rb_node(id, NULL); | |
792 | if (*p) { | |
793 | bdi = rb_entry(*p, struct backing_dev_info, rb_node); | |
794 | bdi_get(bdi); | |
795 | } | |
796 | spin_unlock_bh(&bdi_lock); | |
797 | ||
798 | return bdi; | |
799 | } | |
800 | ||
7c4cc300 | 801 | int bdi_register_va(struct backing_dev_info *bdi, const char *fmt, va_list args) |
46100071 | 802 | { |
46100071 | 803 | struct device *dev; |
34f8fe50 | 804 | struct rb_node *parent, **p; |
e98be2d5 | 805 | |
46100071 TH |
806 | if (bdi->dev) /* The driver needs to use separate queues per device */ |
807 | return 0; | |
e98be2d5 | 808 | |
6bd87eec CH |
809 | vsnprintf(bdi->dev_name, sizeof(bdi->dev_name), fmt, args); |
810 | dev = device_create(bdi_class, NULL, MKDEV(0, 0), bdi, bdi->dev_name); | |
46100071 TH |
811 | if (IS_ERR(dev)) |
812 | return PTR_ERR(dev); | |
04fbfdc1 | 813 | |
e8cb72b3 | 814 | cgwb_bdi_register(bdi); |
46100071 | 815 | bdi->dev = dev; |
b2e8fb6e | 816 | |
6d0e4827 | 817 | bdi_debug_register(bdi, dev_name(dev)); |
46100071 TH |
818 | set_bit(WB_registered, &bdi->wb.state); |
819 | ||
820 | spin_lock_bh(&bdi_lock); | |
34f8fe50 TH |
821 | |
822 | bdi->id = ++bdi_id_cursor; | |
823 | ||
824 | p = bdi_lookup_rb_node(bdi->id, &parent); | |
825 | rb_link_node(&bdi->rb_node, parent, p); | |
826 | rb_insert_color(&bdi->rb_node, &bdi_tree); | |
827 | ||
46100071 | 828 | list_add_tail_rcu(&bdi->bdi_list, &bdi_list); |
34f8fe50 | 829 | |
46100071 TH |
830 | spin_unlock_bh(&bdi_lock); |
831 | ||
832 | trace_writeback_bdi_register(bdi); | |
833 | return 0; | |
b2e8fb6e | 834 | } |
baf7a616 | 835 | |
7c4cc300 | 836 | int bdi_register(struct backing_dev_info *bdi, const char *fmt, ...) |
baf7a616 JK |
837 | { |
838 | va_list args; | |
839 | int ret; | |
840 | ||
841 | va_start(args, fmt); | |
7c4cc300 | 842 | ret = bdi_register_va(bdi, fmt, args); |
baf7a616 JK |
843 | va_end(args); |
844 | return ret; | |
845 | } | |
46100071 | 846 | EXPORT_SYMBOL(bdi_register); |
b2e8fb6e | 847 | |
3c5d202b | 848 | void bdi_set_owner(struct backing_dev_info *bdi, struct device *owner) |
df08c32c | 849 | { |
3c5d202b | 850 | WARN_ON_ONCE(bdi->owner); |
df08c32c DW |
851 | bdi->owner = owner; |
852 | get_device(owner); | |
df08c32c | 853 | } |
df08c32c | 854 | |
46100071 TH |
855 | /* |
856 | * Remove bdi from bdi_list, and ensure that it is no longer visible | |
857 | */ | |
858 | static void bdi_remove_from_list(struct backing_dev_info *bdi) | |
859 | { | |
860 | spin_lock_bh(&bdi_lock); | |
34f8fe50 | 861 | rb_erase(&bdi->rb_node, &bdi_tree); |
46100071 TH |
862 | list_del_rcu(&bdi->bdi_list); |
863 | spin_unlock_bh(&bdi_lock); | |
b2e8fb6e | 864 | |
46100071 TH |
865 | synchronize_rcu_expedited(); |
866 | } | |
cf0ca9fe | 867 | |
b02176f3 | 868 | void bdi_unregister(struct backing_dev_info *bdi) |
b2e8fb6e | 869 | { |
f0054bb1 TH |
870 | /* make sure nobody finds us on the bdi_list anymore */ |
871 | bdi_remove_from_list(bdi); | |
872 | wb_shutdown(&bdi->wb); | |
b1c51afc | 873 | cgwb_bdi_unregister(bdi); |
7a401a97 | 874 | |
c4db59d3 CH |
875 | if (bdi->dev) { |
876 | bdi_debug_unregister(bdi); | |
877 | device_unregister(bdi->dev); | |
878 | bdi->dev = NULL; | |
879 | } | |
df08c32c DW |
880 | |
881 | if (bdi->owner) { | |
882 | put_device(bdi->owner); | |
883 | bdi->owner = NULL; | |
884 | } | |
b02176f3 | 885 | } |
c4db59d3 | 886 | |
d03f6cdc JK |
887 | static void release_bdi(struct kref *ref) |
888 | { | |
889 | struct backing_dev_info *bdi = | |
890 | container_of(ref, struct backing_dev_info, refcnt); | |
891 | ||
5af110b2 JK |
892 | if (test_bit(WB_registered, &bdi->wb.state)) |
893 | bdi_unregister(bdi); | |
2e82b84c JK |
894 | WARN_ON_ONCE(bdi->dev); |
895 | wb_exit(&bdi->wb); | |
d03f6cdc JK |
896 | kfree(bdi); |
897 | } | |
898 | ||
899 | void bdi_put(struct backing_dev_info *bdi) | |
900 | { | |
901 | kref_put(&bdi->refcnt, release_bdi); | |
902 | } | |
62bf42ad | 903 | EXPORT_SYMBOL(bdi_put); |
d03f6cdc | 904 | |
eb7ae5e0 CH |
905 | const char *bdi_dev_name(struct backing_dev_info *bdi) |
906 | { | |
907 | if (!bdi || !bdi->dev) | |
908 | return bdi_unknown_name; | |
6bd87eec | 909 | return bdi->dev_name; |
eb7ae5e0 CH |
910 | } |
911 | EXPORT_SYMBOL_GPL(bdi_dev_name); | |
912 | ||
3fcfab16 AM |
913 | static wait_queue_head_t congestion_wqh[2] = { |
914 | __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]), | |
915 | __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1]) | |
916 | }; | |
ec8a6f26 | 917 | static atomic_t nr_wb_congested[2]; |
3fcfab16 | 918 | |
492d76b2 | 919 | void clear_bdi_congested(struct backing_dev_info *bdi, int sync) |
3fcfab16 | 920 | { |
1faa16d2 | 921 | wait_queue_head_t *wqh = &congestion_wqh[sync]; |
c877ef8a | 922 | enum wb_congested_state bit; |
3fcfab16 | 923 | |
4452226e | 924 | bit = sync ? WB_sync_congested : WB_async_congested; |
8c911f3d | 925 | if (test_and_clear_bit(bit, &bdi->wb.congested)) |
ec8a6f26 | 926 | atomic_dec(&nr_wb_congested[sync]); |
4e857c58 | 927 | smp_mb__after_atomic(); |
3fcfab16 AM |
928 | if (waitqueue_active(wqh)) |
929 | wake_up(wqh); | |
930 | } | |
492d76b2 | 931 | EXPORT_SYMBOL(clear_bdi_congested); |
3fcfab16 | 932 | |
492d76b2 | 933 | void set_bdi_congested(struct backing_dev_info *bdi, int sync) |
3fcfab16 | 934 | { |
c877ef8a | 935 | enum wb_congested_state bit; |
3fcfab16 | 936 | |
4452226e | 937 | bit = sync ? WB_sync_congested : WB_async_congested; |
8c911f3d | 938 | if (!test_and_set_bit(bit, &bdi->wb.congested)) |
ec8a6f26 | 939 | atomic_inc(&nr_wb_congested[sync]); |
3fcfab16 | 940 | } |
492d76b2 | 941 | EXPORT_SYMBOL(set_bdi_congested); |
3fcfab16 AM |
942 | |
943 | /** | |
944 | * congestion_wait - wait for a backing_dev to become uncongested | |
8aa7e847 | 945 | * @sync: SYNC or ASYNC IO |
3fcfab16 AM |
946 | * @timeout: timeout in jiffies |
947 | * | |
948 | * Waits for up to @timeout jiffies for a backing_dev (any backing_dev) to exit | |
949 | * write congestion. If no backing_devs are congested then just wait for the | |
950 | * next write to be completed. | |
951 | */ | |
8aa7e847 | 952 | long congestion_wait(int sync, long timeout) |
3fcfab16 AM |
953 | { |
954 | long ret; | |
52bb9198 | 955 | unsigned long start = jiffies; |
3fcfab16 | 956 | DEFINE_WAIT(wait); |
8aa7e847 | 957 | wait_queue_head_t *wqh = &congestion_wqh[sync]; |
3fcfab16 AM |
958 | |
959 | prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); | |
960 | ret = io_schedule_timeout(timeout); | |
961 | finish_wait(wqh, &wait); | |
52bb9198 MG |
962 | |
963 | trace_writeback_congestion_wait(jiffies_to_usecs(timeout), | |
964 | jiffies_to_usecs(jiffies - start)); | |
965 | ||
3fcfab16 AM |
966 | return ret; |
967 | } | |
968 | EXPORT_SYMBOL(congestion_wait); | |
04fbfdc1 | 969 | |
0e093d99 | 970 | /** |
599d0c95 | 971 | * wait_iff_congested - Conditionally wait for a backing_dev to become uncongested or a pgdat to complete writes |
0e093d99 MG |
972 | * @sync: SYNC or ASYNC IO |
973 | * @timeout: timeout in jiffies | |
974 | * | |
e3c1ac58 AR |
975 | * In the event of a congested backing_dev (any backing_dev) this waits |
976 | * for up to @timeout jiffies for either a BDI to exit congestion of the | |
977 | * given @sync queue or a write to complete. | |
0e093d99 MG |
978 | * |
979 | * The return value is 0 if the sleep is for the full timeout. Otherwise, | |
980 | * it is the number of jiffies that were still remaining when the function | |
981 | * returned. return_value == timeout implies the function did not sleep. | |
982 | */ | |
e3c1ac58 | 983 | long wait_iff_congested(int sync, long timeout) |
0e093d99 MG |
984 | { |
985 | long ret; | |
986 | unsigned long start = jiffies; | |
987 | DEFINE_WAIT(wait); | |
988 | wait_queue_head_t *wqh = &congestion_wqh[sync]; | |
989 | ||
990 | /* | |
e3c1ac58 | 991 | * If there is no congestion, yield if necessary instead |
0e093d99 MG |
992 | * of sleeping on the congestion queue |
993 | */ | |
e3c1ac58 | 994 | if (atomic_read(&nr_wb_congested[sync]) == 0) { |
ede37713 | 995 | cond_resched(); |
599d0c95 | 996 | |
0e093d99 MG |
997 | /* In case we scheduled, work out time remaining */ |
998 | ret = timeout - (jiffies - start); | |
999 | if (ret < 0) | |
1000 | ret = 0; | |
1001 | ||
1002 | goto out; | |
1003 | } | |
1004 | ||
1005 | /* Sleep until uncongested or a write happens */ | |
1006 | prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); | |
1007 | ret = io_schedule_timeout(timeout); | |
1008 | finish_wait(wqh, &wait); | |
1009 | ||
1010 | out: | |
1011 | trace_writeback_wait_iff_congested(jiffies_to_usecs(timeout), | |
1012 | jiffies_to_usecs(jiffies - start)); | |
1013 | ||
1014 | return ret; | |
1015 | } | |
1016 | EXPORT_SYMBOL(wait_iff_congested); |