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Commit | Line | Data |
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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 | |
f56753ac | 17 | struct backing_dev_info noop_backing_dev_info; |
a212b105 | 18 | EXPORT_SYMBOL_GPL(noop_backing_dev_info); |
5129a469 | 19 | |
cf0ca9fe | 20 | static struct class *bdi_class; |
eb7ae5e0 | 21 | static const char *bdi_unknown_name = "(unknown)"; |
cfc4ba53 JA |
22 | |
23 | /* | |
34f8fe50 TH |
24 | * bdi_lock protects bdi_tree and updates to bdi_list. bdi_list has RCU |
25 | * reader side locking. | |
cfc4ba53 | 26 | */ |
03ba3782 | 27 | DEFINE_SPINLOCK(bdi_lock); |
34f8fe50 TH |
28 | static u64 bdi_id_cursor; |
29 | static struct rb_root bdi_tree = RB_ROOT; | |
66f3b8e2 | 30 | LIST_HEAD(bdi_list); |
03ba3782 | 31 | |
839a8e86 TH |
32 | /* bdi_wq serves all asynchronous writeback tasks */ |
33 | struct workqueue_struct *bdi_wq; | |
34 | ||
6986c3e2 BW |
35 | #define K(x) ((x) << (PAGE_SHIFT - 10)) |
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 | 73 | |
76f1418b | 74 | seq_printf(m, |
00821b00 WF |
75 | "BdiWriteback: %10lu kB\n" |
76 | "BdiReclaimable: %10lu kB\n" | |
77 | "BdiDirtyThresh: %10lu kB\n" | |
78 | "DirtyThresh: %10lu kB\n" | |
79 | "BackgroundThresh: %10lu kB\n" | |
c8e28ce0 | 80 | "BdiDirtied: %10lu kB\n" |
00821b00 WF |
81 | "BdiWritten: %10lu kB\n" |
82 | "BdiWriteBandwidth: %10lu kBps\n" | |
83 | "b_dirty: %10lu\n" | |
84 | "b_io: %10lu\n" | |
85 | "b_more_io: %10lu\n" | |
0ae45f63 | 86 | "b_dirty_time: %10lu\n" |
00821b00 WF |
87 | "bdi_list: %10u\n" |
88 | "state: %10lx\n", | |
93f78d88 TH |
89 | (unsigned long) K(wb_stat(wb, WB_WRITEBACK)), |
90 | (unsigned long) K(wb_stat(wb, WB_RECLAIMABLE)), | |
0d960a38 | 91 | K(wb_thresh), |
f7d2b1ec JK |
92 | K(dirty_thresh), |
93 | K(background_thresh), | |
93f78d88 TH |
94 | (unsigned long) K(wb_stat(wb, WB_DIRTIED)), |
95 | (unsigned long) K(wb_stat(wb, WB_WRITTEN)), | |
a88a341a | 96 | (unsigned long) K(wb->write_bandwidth), |
f7d2b1ec JK |
97 | nr_dirty, |
98 | nr_io, | |
99 | nr_more_io, | |
0ae45f63 | 100 | nr_dirty_time, |
4452226e | 101 | !list_empty(&bdi->bdi_list), bdi->wb.state); |
76f1418b MS |
102 | |
103 | return 0; | |
104 | } | |
5ad35093 | 105 | DEFINE_SHOW_ATTRIBUTE(bdi_debug_stats); |
76f1418b | 106 | |
2d146b92 | 107 | static void bdi_debug_register(struct backing_dev_info *bdi, const char *name) |
76f1418b MS |
108 | { |
109 | bdi->debug_dir = debugfs_create_dir(name, bdi_debug_root); | |
97f07697 | 110 | |
2d146b92 GKH |
111 | debugfs_create_file("stats", 0444, bdi->debug_dir, bdi, |
112 | &bdi_debug_stats_fops); | |
76f1418b MS |
113 | } |
114 | ||
115 | static void bdi_debug_unregister(struct backing_dev_info *bdi) | |
116 | { | |
2d146b92 | 117 | debugfs_remove_recursive(bdi->debug_dir); |
76f1418b MS |
118 | } |
119 | #else | |
120 | static inline void bdi_debug_init(void) | |
121 | { | |
122 | } | |
2d146b92 | 123 | static inline void bdi_debug_register(struct backing_dev_info *bdi, |
76f1418b MS |
124 | const char *name) |
125 | { | |
126 | } | |
127 | static inline void bdi_debug_unregister(struct backing_dev_info *bdi) | |
128 | { | |
129 | } | |
130 | #endif | |
131 | ||
cf0ca9fe PZ |
132 | static ssize_t read_ahead_kb_store(struct device *dev, |
133 | struct device_attribute *attr, | |
134 | const char *buf, size_t count) | |
135 | { | |
136 | struct backing_dev_info *bdi = dev_get_drvdata(dev); | |
cf0ca9fe | 137 | unsigned long read_ahead_kb; |
7034ed13 | 138 | ssize_t ret; |
cf0ca9fe | 139 | |
7034ed13 NJ |
140 | ret = kstrtoul(buf, 10, &read_ahead_kb); |
141 | if (ret < 0) | |
142 | return ret; | |
143 | ||
144 | bdi->ra_pages = read_ahead_kb >> (PAGE_SHIFT - 10); | |
145 | ||
146 | return count; | |
cf0ca9fe PZ |
147 | } |
148 | ||
cf0ca9fe PZ |
149 | #define BDI_SHOW(name, expr) \ |
150 | static ssize_t name##_show(struct device *dev, \ | |
5e4c0d86 | 151 | struct device_attribute *attr, char *buf) \ |
cf0ca9fe PZ |
152 | { \ |
153 | struct backing_dev_info *bdi = dev_get_drvdata(dev); \ | |
154 | \ | |
5e4c0d86 | 155 | return sysfs_emit(buf, "%lld\n", (long long)expr); \ |
d9e1241e GKH |
156 | } \ |
157 | static DEVICE_ATTR_RW(name); | |
cf0ca9fe PZ |
158 | |
159 | BDI_SHOW(read_ahead_kb, K(bdi->ra_pages)) | |
160 | ||
189d3c4a PZ |
161 | static ssize_t min_ratio_store(struct device *dev, |
162 | struct device_attribute *attr, const char *buf, size_t count) | |
163 | { | |
164 | struct backing_dev_info *bdi = dev_get_drvdata(dev); | |
189d3c4a | 165 | unsigned int ratio; |
7034ed13 NJ |
166 | ssize_t ret; |
167 | ||
168 | ret = kstrtouint(buf, 10, &ratio); | |
169 | if (ret < 0) | |
170 | return ret; | |
171 | ||
172 | ret = bdi_set_min_ratio(bdi, ratio); | |
173 | if (!ret) | |
174 | ret = count; | |
189d3c4a | 175 | |
189d3c4a PZ |
176 | return ret; |
177 | } | |
178 | BDI_SHOW(min_ratio, bdi->min_ratio) | |
179 | ||
a42dde04 PZ |
180 | static ssize_t max_ratio_store(struct device *dev, |
181 | struct device_attribute *attr, const char *buf, size_t count) | |
182 | { | |
183 | struct backing_dev_info *bdi = dev_get_drvdata(dev); | |
a42dde04 | 184 | unsigned int ratio; |
7034ed13 NJ |
185 | ssize_t ret; |
186 | ||
187 | ret = kstrtouint(buf, 10, &ratio); | |
188 | if (ret < 0) | |
189 | return ret; | |
190 | ||
191 | ret = bdi_set_max_ratio(bdi, ratio); | |
192 | if (!ret) | |
193 | ret = count; | |
a42dde04 | 194 | |
a42dde04 PZ |
195 | return ret; |
196 | } | |
197 | BDI_SHOW(max_ratio, bdi->max_ratio) | |
198 | ||
7d311cda DW |
199 | static ssize_t stable_pages_required_show(struct device *dev, |
200 | struct device_attribute *attr, | |
5e4c0d86 | 201 | char *buf) |
7d311cda | 202 | { |
1cb039f3 CH |
203 | dev_warn_once(dev, |
204 | "the stable_pages_required attribute has been removed. Use the stable_writes queue attribute instead.\n"); | |
5e4c0d86 | 205 | return sysfs_emit(buf, "%d\n", 0); |
7d311cda | 206 | } |
d9e1241e GKH |
207 | static DEVICE_ATTR_RO(stable_pages_required); |
208 | ||
209 | static struct attribute *bdi_dev_attrs[] = { | |
210 | &dev_attr_read_ahead_kb.attr, | |
211 | &dev_attr_min_ratio.attr, | |
212 | &dev_attr_max_ratio.attr, | |
213 | &dev_attr_stable_pages_required.attr, | |
214 | NULL, | |
cf0ca9fe | 215 | }; |
d9e1241e | 216 | ATTRIBUTE_GROUPS(bdi_dev); |
cf0ca9fe PZ |
217 | |
218 | static __init int bdi_class_init(void) | |
219 | { | |
220 | bdi_class = class_create(THIS_MODULE, "bdi"); | |
14421453 AB |
221 | if (IS_ERR(bdi_class)) |
222 | return PTR_ERR(bdi_class); | |
223 | ||
d9e1241e | 224 | bdi_class->dev_groups = bdi_dev_groups; |
76f1418b | 225 | bdi_debug_init(); |
d03f6cdc | 226 | |
cf0ca9fe PZ |
227 | return 0; |
228 | } | |
76f1418b | 229 | postcore_initcall(bdi_class_init); |
cf0ca9fe | 230 | |
2e82b84c JK |
231 | static int bdi_init(struct backing_dev_info *bdi); |
232 | ||
26160158 JA |
233 | static int __init default_bdi_init(void) |
234 | { | |
235 | int err; | |
236 | ||
a2b90f11 MW |
237 | bdi_wq = alloc_workqueue("writeback", WQ_MEM_RECLAIM | WQ_UNBOUND | |
238 | WQ_SYSFS, 0); | |
839a8e86 TH |
239 | if (!bdi_wq) |
240 | return -ENOMEM; | |
241 | ||
976e48f8 | 242 | err = bdi_init(&noop_backing_dev_info); |
26160158 JA |
243 | |
244 | return err; | |
245 | } | |
246 | subsys_initcall(default_bdi_init); | |
247 | ||
6467716a | 248 | /* |
f0054bb1 | 249 | * This function is used when the first inode for this wb is marked dirty. It |
6467716a AB |
250 | * wakes-up the corresponding bdi thread which should then take care of the |
251 | * periodic background write-out of dirty inodes. Since the write-out would | |
252 | * starts only 'dirty_writeback_interval' centisecs from now anyway, we just | |
253 | * set up a timer which wakes the bdi thread up later. | |
254 | * | |
255 | * Note, we wouldn't bother setting up the timer, but this function is on the | |
256 | * fast-path (used by '__mark_inode_dirty()'), so we save few context switches | |
257 | * by delaying the wake-up. | |
6ca738d6 DB |
258 | * |
259 | * We have to be careful not to postpone flush work if it is scheduled for | |
260 | * earlier. Thus we use queue_delayed_work(). | |
6467716a | 261 | */ |
f0054bb1 | 262 | void wb_wakeup_delayed(struct bdi_writeback *wb) |
6467716a AB |
263 | { |
264 | unsigned long timeout; | |
265 | ||
266 | timeout = msecs_to_jiffies(dirty_writeback_interval * 10); | |
f0054bb1 TH |
267 | spin_lock_bh(&wb->work_lock); |
268 | if (test_bit(WB_registered, &wb->state)) | |
269 | queue_delayed_work(bdi_wq, &wb->dwork, timeout); | |
270 | spin_unlock_bh(&wb->work_lock); | |
03ba3782 JA |
271 | } |
272 | ||
cfc4ba53 | 273 | /* |
a88a341a | 274 | * Initial write bandwidth: 100 MB/s |
cfc4ba53 | 275 | */ |
a88a341a | 276 | #define INIT_BW (100 << (20 - PAGE_SHIFT)) |
cfc4ba53 | 277 | |
8395cd9f | 278 | static int wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi, |
8c911f3d | 279 | gfp_t gfp) |
cf0ca9fe | 280 | { |
93f78d88 | 281 | int i, err; |
cf0ca9fe | 282 | |
6467716a | 283 | memset(wb, 0, sizeof(*wb)); |
f1d0b063 | 284 | |
810df54a JK |
285 | if (wb != &bdi->wb) |
286 | bdi_get(bdi); | |
6467716a AB |
287 | wb->bdi = bdi; |
288 | wb->last_old_flush = jiffies; | |
289 | INIT_LIST_HEAD(&wb->b_dirty); | |
290 | INIT_LIST_HEAD(&wb->b_io); | |
291 | INIT_LIST_HEAD(&wb->b_more_io); | |
0ae45f63 | 292 | INIT_LIST_HEAD(&wb->b_dirty_time); |
f758eeab | 293 | spin_lock_init(&wb->list_lock); |
66f3b8e2 | 294 | |
a88a341a TH |
295 | wb->bw_time_stamp = jiffies; |
296 | wb->balanced_dirty_ratelimit = INIT_BW; | |
297 | wb->dirty_ratelimit = INIT_BW; | |
298 | wb->write_bandwidth = INIT_BW; | |
299 | wb->avg_write_bandwidth = INIT_BW; | |
cf0ca9fe | 300 | |
f0054bb1 TH |
301 | spin_lock_init(&wb->work_lock); |
302 | INIT_LIST_HEAD(&wb->work_list); | |
303 | INIT_DELAYED_WORK(&wb->dwork, wb_workfn); | |
b57d74af | 304 | wb->dirty_sleep = jiffies; |
c284de61 | 305 | |
8395cd9f | 306 | err = fprop_local_init_percpu(&wb->completions, gfp); |
a88a341a | 307 | if (err) |
8c911f3d | 308 | goto out_put_bdi; |
c284de61 | 309 | |
93f78d88 | 310 | for (i = 0; i < NR_WB_STAT_ITEMS; i++) { |
8395cd9f | 311 | err = percpu_counter_init(&wb->stat[i], 0, gfp); |
a13f35e8 TH |
312 | if (err) |
313 | goto out_destroy_stat; | |
93f78d88 | 314 | } |
cf0ca9fe | 315 | |
93f78d88 | 316 | return 0; |
a13f35e8 TH |
317 | |
318 | out_destroy_stat: | |
078c6c3a | 319 | while (i--) |
a13f35e8 TH |
320 | percpu_counter_destroy(&wb->stat[i]); |
321 | fprop_local_destroy_percpu(&wb->completions); | |
810df54a JK |
322 | out_put_bdi: |
323 | if (wb != &bdi->wb) | |
324 | bdi_put(bdi); | |
a13f35e8 | 325 | return err; |
cf0ca9fe | 326 | } |
cf0ca9fe | 327 | |
e8cb72b3 JK |
328 | static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb); |
329 | ||
03ba3782 JA |
330 | /* |
331 | * Remove bdi from the global list and shutdown any threads we have running | |
332 | */ | |
46100071 | 333 | static void wb_shutdown(struct bdi_writeback *wb) |
66f3b8e2 | 334 | { |
c4db59d3 | 335 | /* Make sure nobody queues further work */ |
46100071 TH |
336 | spin_lock_bh(&wb->work_lock); |
337 | if (!test_and_clear_bit(WB_registered, &wb->state)) { | |
338 | spin_unlock_bh(&wb->work_lock); | |
03ba3782 | 339 | return; |
c4db59d3 | 340 | } |
46100071 | 341 | spin_unlock_bh(&wb->work_lock); |
03ba3782 | 342 | |
e8cb72b3 | 343 | cgwb_remove_from_bdi_list(wb); |
03ba3782 | 344 | /* |
46100071 TH |
345 | * Drain work list and shutdown the delayed_work. !WB_registered |
346 | * tells wb_workfn() that @wb is dying and its work_list needs to | |
347 | * be drained no matter what. | |
03ba3782 | 348 | */ |
46100071 TH |
349 | mod_delayed_work(bdi_wq, &wb->dwork, 0); |
350 | flush_delayed_work(&wb->dwork); | |
351 | WARN_ON(!list_empty(&wb->work_list)); | |
352 | } | |
353 | ||
f0054bb1 | 354 | static void wb_exit(struct bdi_writeback *wb) |
93f78d88 TH |
355 | { |
356 | int i; | |
357 | ||
358 | WARN_ON(delayed_work_pending(&wb->dwork)); | |
359 | ||
360 | for (i = 0; i < NR_WB_STAT_ITEMS; i++) | |
361 | percpu_counter_destroy(&wb->stat[i]); | |
6467716a | 362 | |
a88a341a | 363 | fprop_local_destroy_percpu(&wb->completions); |
810df54a JK |
364 | if (wb != &wb->bdi->wb) |
365 | bdi_put(wb->bdi); | |
a88a341a | 366 | } |
e98be2d5 | 367 | |
52ebea74 TH |
368 | #ifdef CONFIG_CGROUP_WRITEBACK |
369 | ||
370 | #include <linux/memcontrol.h> | |
371 | ||
372 | /* | |
8c911f3d CH |
373 | * cgwb_lock protects bdi->cgwb_tree, blkcg->cgwb_list, and memcg->cgwb_list. |
374 | * bdi->cgwb_tree is also RCU protected. | |
52ebea74 TH |
375 | */ |
376 | static DEFINE_SPINLOCK(cgwb_lock); | |
f1834646 | 377 | static struct workqueue_struct *cgwb_release_wq; |
52ebea74 | 378 | |
52ebea74 TH |
379 | static void cgwb_release_workfn(struct work_struct *work) |
380 | { | |
381 | struct bdi_writeback *wb = container_of(work, struct bdi_writeback, | |
382 | release_work); | |
59b57717 | 383 | struct blkcg *blkcg = css_to_blkcg(wb->blkcg_css); |
52ebea74 | 384 | |
3ee7e869 | 385 | mutex_lock(&wb->bdi->cgwb_release_mutex); |
52ebea74 TH |
386 | wb_shutdown(wb); |
387 | ||
388 | css_put(wb->memcg_css); | |
389 | css_put(wb->blkcg_css); | |
3ee7e869 | 390 | mutex_unlock(&wb->bdi->cgwb_release_mutex); |
52ebea74 | 391 | |
d866dbf6 TH |
392 | /* triggers blkg destruction if no online users left */ |
393 | blkcg_unpin_online(blkcg); | |
59b57717 | 394 | |
841710aa | 395 | fprop_local_destroy_percpu(&wb->memcg_completions); |
52ebea74 TH |
396 | percpu_ref_exit(&wb->refcnt); |
397 | wb_exit(wb); | |
398 | kfree_rcu(wb, rcu); | |
52ebea74 TH |
399 | } |
400 | ||
401 | static void cgwb_release(struct percpu_ref *refcnt) | |
402 | { | |
403 | struct bdi_writeback *wb = container_of(refcnt, struct bdi_writeback, | |
404 | refcnt); | |
f1834646 | 405 | queue_work(cgwb_release_wq, &wb->release_work); |
52ebea74 TH |
406 | } |
407 | ||
408 | static void cgwb_kill(struct bdi_writeback *wb) | |
409 | { | |
410 | lockdep_assert_held(&cgwb_lock); | |
411 | ||
412 | WARN_ON(!radix_tree_delete(&wb->bdi->cgwb_tree, wb->memcg_css->id)); | |
413 | list_del(&wb->memcg_node); | |
414 | list_del(&wb->blkcg_node); | |
415 | percpu_ref_kill(&wb->refcnt); | |
416 | } | |
417 | ||
e8cb72b3 JK |
418 | static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb) |
419 | { | |
420 | spin_lock_irq(&cgwb_lock); | |
421 | list_del_rcu(&wb->bdi_node); | |
422 | spin_unlock_irq(&cgwb_lock); | |
423 | } | |
424 | ||
52ebea74 TH |
425 | static int cgwb_create(struct backing_dev_info *bdi, |
426 | struct cgroup_subsys_state *memcg_css, gfp_t gfp) | |
427 | { | |
428 | struct mem_cgroup *memcg; | |
429 | struct cgroup_subsys_state *blkcg_css; | |
430 | struct blkcg *blkcg; | |
431 | struct list_head *memcg_cgwb_list, *blkcg_cgwb_list; | |
432 | struct bdi_writeback *wb; | |
433 | unsigned long flags; | |
434 | int ret = 0; | |
435 | ||
436 | memcg = mem_cgroup_from_css(memcg_css); | |
c165b3e3 | 437 | blkcg_css = cgroup_get_e_css(memcg_css->cgroup, &io_cgrp_subsys); |
52ebea74 | 438 | blkcg = css_to_blkcg(blkcg_css); |
9ccc3617 | 439 | memcg_cgwb_list = &memcg->cgwb_list; |
52ebea74 TH |
440 | blkcg_cgwb_list = &blkcg->cgwb_list; |
441 | ||
442 | /* look up again under lock and discard on blkcg mismatch */ | |
443 | spin_lock_irqsave(&cgwb_lock, flags); | |
444 | wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id); | |
445 | if (wb && wb->blkcg_css != blkcg_css) { | |
446 | cgwb_kill(wb); | |
447 | wb = NULL; | |
448 | } | |
449 | spin_unlock_irqrestore(&cgwb_lock, flags); | |
450 | if (wb) | |
451 | goto out_put; | |
452 | ||
453 | /* need to create a new one */ | |
454 | wb = kmalloc(sizeof(*wb), gfp); | |
0b045bd1 CJ |
455 | if (!wb) { |
456 | ret = -ENOMEM; | |
457 | goto out_put; | |
458 | } | |
52ebea74 | 459 | |
8c911f3d | 460 | ret = wb_init(wb, bdi, gfp); |
52ebea74 TH |
461 | if (ret) |
462 | goto err_free; | |
463 | ||
464 | ret = percpu_ref_init(&wb->refcnt, cgwb_release, 0, gfp); | |
465 | if (ret) | |
466 | goto err_wb_exit; | |
467 | ||
841710aa TH |
468 | ret = fprop_local_init_percpu(&wb->memcg_completions, gfp); |
469 | if (ret) | |
470 | goto err_ref_exit; | |
471 | ||
52ebea74 TH |
472 | wb->memcg_css = memcg_css; |
473 | wb->blkcg_css = blkcg_css; | |
474 | INIT_WORK(&wb->release_work, cgwb_release_workfn); | |
475 | set_bit(WB_registered, &wb->state); | |
03ba3782 JA |
476 | |
477 | /* | |
52ebea74 TH |
478 | * The root wb determines the registered state of the whole bdi and |
479 | * memcg_cgwb_list and blkcg_cgwb_list's next pointers indicate | |
480 | * whether they're still online. Don't link @wb if any is dead. | |
481 | * See wb_memcg_offline() and wb_blkcg_offline(). | |
03ba3782 | 482 | */ |
52ebea74 TH |
483 | ret = -ENODEV; |
484 | spin_lock_irqsave(&cgwb_lock, flags); | |
485 | if (test_bit(WB_registered, &bdi->wb.state) && | |
486 | blkcg_cgwb_list->next && memcg_cgwb_list->next) { | |
487 | /* we might have raced another instance of this function */ | |
488 | ret = radix_tree_insert(&bdi->cgwb_tree, memcg_css->id, wb); | |
489 | if (!ret) { | |
b817525a | 490 | list_add_tail_rcu(&wb->bdi_node, &bdi->wb_list); |
52ebea74 TH |
491 | list_add(&wb->memcg_node, memcg_cgwb_list); |
492 | list_add(&wb->blkcg_node, blkcg_cgwb_list); | |
d866dbf6 | 493 | blkcg_pin_online(blkcg); |
52ebea74 TH |
494 | css_get(memcg_css); |
495 | css_get(blkcg_css); | |
496 | } | |
497 | } | |
498 | spin_unlock_irqrestore(&cgwb_lock, flags); | |
499 | if (ret) { | |
500 | if (ret == -EEXIST) | |
501 | ret = 0; | |
a13f35e8 | 502 | goto err_fprop_exit; |
52ebea74 TH |
503 | } |
504 | goto out_put; | |
505 | ||
841710aa TH |
506 | err_fprop_exit: |
507 | fprop_local_destroy_percpu(&wb->memcg_completions); | |
52ebea74 TH |
508 | err_ref_exit: |
509 | percpu_ref_exit(&wb->refcnt); | |
510 | err_wb_exit: | |
511 | wb_exit(wb); | |
512 | err_free: | |
513 | kfree(wb); | |
514 | out_put: | |
515 | css_put(blkcg_css); | |
516 | return ret; | |
66f3b8e2 JA |
517 | } |
518 | ||
52ebea74 | 519 | /** |
ed288dc0 | 520 | * wb_get_lookup - get wb for a given memcg |
52ebea74 TH |
521 | * @bdi: target bdi |
522 | * @memcg_css: cgroup_subsys_state of the target memcg (must have positive ref) | |
52ebea74 | 523 | * |
ed288dc0 TH |
524 | * Try to get the wb for @memcg_css on @bdi. The returned wb has its |
525 | * refcount incremented. | |
52ebea74 TH |
526 | * |
527 | * This function uses css_get() on @memcg_css and thus expects its refcnt | |
528 | * to be positive on invocation. IOW, rcu_read_lock() protection on | |
529 | * @memcg_css isn't enough. try_get it before calling this function. | |
530 | * | |
531 | * A wb is keyed by its associated memcg. As blkcg implicitly enables | |
532 | * memcg on the default hierarchy, memcg association is guaranteed to be | |
533 | * more specific (equal or descendant to the associated blkcg) and thus can | |
534 | * identify both the memcg and blkcg associations. | |
535 | * | |
536 | * Because the blkcg associated with a memcg may change as blkcg is enabled | |
537 | * and disabled closer to root in the hierarchy, each wb keeps track of | |
538 | * both the memcg and blkcg associated with it and verifies the blkcg on | |
539 | * each lookup. On mismatch, the existing wb is discarded and a new one is | |
540 | * created. | |
541 | */ | |
ed288dc0 TH |
542 | struct bdi_writeback *wb_get_lookup(struct backing_dev_info *bdi, |
543 | struct cgroup_subsys_state *memcg_css) | |
544 | { | |
545 | struct bdi_writeback *wb; | |
546 | ||
547 | if (!memcg_css->parent) | |
548 | return &bdi->wb; | |
549 | ||
550 | rcu_read_lock(); | |
551 | wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id); | |
552 | if (wb) { | |
553 | struct cgroup_subsys_state *blkcg_css; | |
554 | ||
555 | /* see whether the blkcg association has changed */ | |
556 | blkcg_css = cgroup_get_e_css(memcg_css->cgroup, &io_cgrp_subsys); | |
557 | if (unlikely(wb->blkcg_css != blkcg_css || !wb_tryget(wb))) | |
558 | wb = NULL; | |
559 | css_put(blkcg_css); | |
560 | } | |
561 | rcu_read_unlock(); | |
562 | ||
563 | return wb; | |
564 | } | |
565 | ||
566 | /** | |
567 | * wb_get_create - get wb for a given memcg, create if necessary | |
568 | * @bdi: target bdi | |
569 | * @memcg_css: cgroup_subsys_state of the target memcg (must have positive ref) | |
570 | * @gfp: allocation mask to use | |
571 | * | |
572 | * Try to get the wb for @memcg_css on @bdi. If it doesn't exist, try to | |
573 | * create one. See wb_get_lookup() for more details. | |
574 | */ | |
52ebea74 TH |
575 | struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi, |
576 | struct cgroup_subsys_state *memcg_css, | |
577 | gfp_t gfp) | |
6467716a | 578 | { |
52ebea74 TH |
579 | struct bdi_writeback *wb; |
580 | ||
d0164adc | 581 | might_sleep_if(gfpflags_allow_blocking(gfp)); |
52ebea74 TH |
582 | |
583 | if (!memcg_css->parent) | |
584 | return &bdi->wb; | |
585 | ||
586 | do { | |
ed288dc0 | 587 | wb = wb_get_lookup(bdi, memcg_css); |
52ebea74 TH |
588 | } while (!wb && !cgwb_create(bdi, memcg_css, gfp)); |
589 | ||
590 | return wb; | |
591 | } | |
6467716a | 592 | |
a13f35e8 | 593 | static int cgwb_bdi_init(struct backing_dev_info *bdi) |
52ebea74 | 594 | { |
a13f35e8 TH |
595 | int ret; |
596 | ||
52ebea74 | 597 | INIT_RADIX_TREE(&bdi->cgwb_tree, GFP_ATOMIC); |
3ee7e869 | 598 | mutex_init(&bdi->cgwb_release_mutex); |
7fc5854f | 599 | init_rwsem(&bdi->wb_switch_rwsem); |
a13f35e8 | 600 | |
8c911f3d | 601 | ret = wb_init(&bdi->wb, bdi, GFP_KERNEL); |
a13f35e8 | 602 | if (!ret) { |
7d828602 | 603 | bdi->wb.memcg_css = &root_mem_cgroup->css; |
a13f35e8 TH |
604 | bdi->wb.blkcg_css = blkcg_root_css; |
605 | } | |
606 | return ret; | |
6467716a AB |
607 | } |
608 | ||
b1c51afc | 609 | static void cgwb_bdi_unregister(struct backing_dev_info *bdi) |
52ebea74 TH |
610 | { |
611 | struct radix_tree_iter iter; | |
612 | void **slot; | |
5318ce7d | 613 | struct bdi_writeback *wb; |
52ebea74 TH |
614 | |
615 | WARN_ON(test_bit(WB_registered, &bdi->wb.state)); | |
616 | ||
617 | spin_lock_irq(&cgwb_lock); | |
618 | radix_tree_for_each_slot(slot, &bdi->cgwb_tree, &iter, 0) | |
619 | cgwb_kill(*slot); | |
3ee7e869 | 620 | spin_unlock_irq(&cgwb_lock); |
5318ce7d | 621 | |
3ee7e869 JK |
622 | mutex_lock(&bdi->cgwb_release_mutex); |
623 | spin_lock_irq(&cgwb_lock); | |
5318ce7d JK |
624 | while (!list_empty(&bdi->wb_list)) { |
625 | wb = list_first_entry(&bdi->wb_list, struct bdi_writeback, | |
626 | bdi_node); | |
627 | spin_unlock_irq(&cgwb_lock); | |
628 | wb_shutdown(wb); | |
629 | spin_lock_irq(&cgwb_lock); | |
630 | } | |
52ebea74 | 631 | spin_unlock_irq(&cgwb_lock); |
3ee7e869 | 632 | mutex_unlock(&bdi->cgwb_release_mutex); |
52ebea74 TH |
633 | } |
634 | ||
635 | /** | |
636 | * wb_memcg_offline - kill all wb's associated with a memcg being offlined | |
637 | * @memcg: memcg being offlined | |
638 | * | |
639 | * Also prevents creation of any new wb's associated with @memcg. | |
e98be2d5 | 640 | */ |
52ebea74 TH |
641 | void wb_memcg_offline(struct mem_cgroup *memcg) |
642 | { | |
9ccc3617 | 643 | struct list_head *memcg_cgwb_list = &memcg->cgwb_list; |
52ebea74 TH |
644 | struct bdi_writeback *wb, *next; |
645 | ||
646 | spin_lock_irq(&cgwb_lock); | |
647 | list_for_each_entry_safe(wb, next, memcg_cgwb_list, memcg_node) | |
648 | cgwb_kill(wb); | |
649 | memcg_cgwb_list->next = NULL; /* prevent new wb's */ | |
650 | spin_unlock_irq(&cgwb_lock); | |
651 | } | |
652 | ||
653 | /** | |
654 | * wb_blkcg_offline - kill all wb's associated with a blkcg being offlined | |
655 | * @blkcg: blkcg being offlined | |
656 | * | |
657 | * Also prevents creation of any new wb's associated with @blkcg. | |
658 | */ | |
659 | void wb_blkcg_offline(struct blkcg *blkcg) | |
660 | { | |
52ebea74 TH |
661 | struct bdi_writeback *wb, *next; |
662 | ||
663 | spin_lock_irq(&cgwb_lock); | |
664 | list_for_each_entry_safe(wb, next, &blkcg->cgwb_list, blkcg_node) | |
665 | cgwb_kill(wb); | |
666 | blkcg->cgwb_list.next = NULL; /* prevent new wb's */ | |
667 | spin_unlock_irq(&cgwb_lock); | |
668 | } | |
669 | ||
e8cb72b3 JK |
670 | static void cgwb_bdi_register(struct backing_dev_info *bdi) |
671 | { | |
672 | spin_lock_irq(&cgwb_lock); | |
673 | list_add_tail_rcu(&bdi->wb.bdi_node, &bdi->wb_list); | |
674 | spin_unlock_irq(&cgwb_lock); | |
675 | } | |
676 | ||
f1834646 TH |
677 | static int __init cgwb_init(void) |
678 | { | |
679 | /* | |
680 | * There can be many concurrent release work items overwhelming | |
681 | * system_wq. Put them in a separate wq and limit concurrency. | |
682 | * There's no point in executing many of these in parallel. | |
683 | */ | |
684 | cgwb_release_wq = alloc_workqueue("cgwb_release", 0, 1); | |
685 | if (!cgwb_release_wq) | |
686 | return -ENOMEM; | |
687 | ||
688 | return 0; | |
689 | } | |
690 | subsys_initcall(cgwb_init); | |
691 | ||
52ebea74 TH |
692 | #else /* CONFIG_CGROUP_WRITEBACK */ |
693 | ||
a13f35e8 TH |
694 | static int cgwb_bdi_init(struct backing_dev_info *bdi) |
695 | { | |
8c911f3d | 696 | return wb_init(&bdi->wb, bdi, GFP_KERNEL); |
a13f35e8 TH |
697 | } |
698 | ||
b1c51afc | 699 | static void cgwb_bdi_unregister(struct backing_dev_info *bdi) { } |
df23de55 | 700 | |
e8cb72b3 JK |
701 | static void cgwb_bdi_register(struct backing_dev_info *bdi) |
702 | { | |
703 | list_add_tail_rcu(&bdi->wb.bdi_node, &bdi->wb_list); | |
704 | } | |
705 | ||
706 | static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb) | |
707 | { | |
708 | list_del_rcu(&wb->bdi_node); | |
709 | } | |
710 | ||
52ebea74 | 711 | #endif /* CONFIG_CGROUP_WRITEBACK */ |
e98be2d5 | 712 | |
2e82b84c | 713 | static int bdi_init(struct backing_dev_info *bdi) |
b2e8fb6e | 714 | { |
b817525a TH |
715 | int ret; |
716 | ||
cf0ca9fe PZ |
717 | bdi->dev = NULL; |
718 | ||
d03f6cdc | 719 | kref_init(&bdi->refcnt); |
189d3c4a | 720 | bdi->min_ratio = 0; |
a42dde04 | 721 | bdi->max_ratio = 100; |
eb608e3a | 722 | bdi->max_prop_frac = FPROP_FRAC_BASE; |
66f3b8e2 | 723 | INIT_LIST_HEAD(&bdi->bdi_list); |
b817525a | 724 | INIT_LIST_HEAD(&bdi->wb_list); |
cc395d7f | 725 | init_waitqueue_head(&bdi->wb_waitq); |
03ba3782 | 726 | |
b817525a TH |
727 | ret = cgwb_bdi_init(bdi); |
728 | ||
b817525a | 729 | return ret; |
b2e8fb6e | 730 | } |
e98be2d5 | 731 | |
aef33c2f | 732 | struct backing_dev_info *bdi_alloc(int node_id) |
d03f6cdc JK |
733 | { |
734 | struct backing_dev_info *bdi; | |
735 | ||
aef33c2f | 736 | bdi = kzalloc_node(sizeof(*bdi), GFP_KERNEL, node_id); |
d03f6cdc JK |
737 | if (!bdi) |
738 | return NULL; | |
739 | ||
740 | if (bdi_init(bdi)) { | |
741 | kfree(bdi); | |
742 | return NULL; | |
743 | } | |
f56753ac | 744 | bdi->capabilities = BDI_CAP_WRITEBACK | BDI_CAP_WRITEBACK_ACCT; |
55b2598e CH |
745 | bdi->ra_pages = VM_READAHEAD_PAGES; |
746 | bdi->io_pages = VM_READAHEAD_PAGES; | |
d03f6cdc JK |
747 | return bdi; |
748 | } | |
aef33c2f | 749 | EXPORT_SYMBOL(bdi_alloc); |
d03f6cdc | 750 | |
34f8fe50 TH |
751 | static struct rb_node **bdi_lookup_rb_node(u64 id, struct rb_node **parentp) |
752 | { | |
753 | struct rb_node **p = &bdi_tree.rb_node; | |
754 | struct rb_node *parent = NULL; | |
755 | struct backing_dev_info *bdi; | |
756 | ||
757 | lockdep_assert_held(&bdi_lock); | |
758 | ||
759 | while (*p) { | |
760 | parent = *p; | |
761 | bdi = rb_entry(parent, struct backing_dev_info, rb_node); | |
762 | ||
763 | if (bdi->id > id) | |
764 | p = &(*p)->rb_left; | |
765 | else if (bdi->id < id) | |
766 | p = &(*p)->rb_right; | |
767 | else | |
768 | break; | |
769 | } | |
770 | ||
771 | if (parentp) | |
772 | *parentp = parent; | |
773 | return p; | |
774 | } | |
775 | ||
776 | /** | |
777 | * bdi_get_by_id - lookup and get bdi from its id | |
778 | * @id: bdi id to lookup | |
779 | * | |
780 | * Find bdi matching @id and get it. Returns NULL if the matching bdi | |
781 | * doesn't exist or is already unregistered. | |
782 | */ | |
783 | struct backing_dev_info *bdi_get_by_id(u64 id) | |
784 | { | |
785 | struct backing_dev_info *bdi = NULL; | |
786 | struct rb_node **p; | |
787 | ||
788 | spin_lock_bh(&bdi_lock); | |
789 | p = bdi_lookup_rb_node(id, NULL); | |
790 | if (*p) { | |
791 | bdi = rb_entry(*p, struct backing_dev_info, rb_node); | |
792 | bdi_get(bdi); | |
793 | } | |
794 | spin_unlock_bh(&bdi_lock); | |
795 | ||
796 | return bdi; | |
797 | } | |
798 | ||
7c4cc300 | 799 | int bdi_register_va(struct backing_dev_info *bdi, const char *fmt, va_list args) |
46100071 | 800 | { |
46100071 | 801 | struct device *dev; |
34f8fe50 | 802 | struct rb_node *parent, **p; |
e98be2d5 | 803 | |
46100071 TH |
804 | if (bdi->dev) /* The driver needs to use separate queues per device */ |
805 | return 0; | |
e98be2d5 | 806 | |
6bd87eec CH |
807 | vsnprintf(bdi->dev_name, sizeof(bdi->dev_name), fmt, args); |
808 | dev = device_create(bdi_class, NULL, MKDEV(0, 0), bdi, bdi->dev_name); | |
46100071 TH |
809 | if (IS_ERR(dev)) |
810 | return PTR_ERR(dev); | |
04fbfdc1 | 811 | |
e8cb72b3 | 812 | cgwb_bdi_register(bdi); |
46100071 | 813 | bdi->dev = dev; |
b2e8fb6e | 814 | |
6d0e4827 | 815 | bdi_debug_register(bdi, dev_name(dev)); |
46100071 TH |
816 | set_bit(WB_registered, &bdi->wb.state); |
817 | ||
818 | spin_lock_bh(&bdi_lock); | |
34f8fe50 TH |
819 | |
820 | bdi->id = ++bdi_id_cursor; | |
821 | ||
822 | p = bdi_lookup_rb_node(bdi->id, &parent); | |
823 | rb_link_node(&bdi->rb_node, parent, p); | |
824 | rb_insert_color(&bdi->rb_node, &bdi_tree); | |
825 | ||
46100071 | 826 | list_add_tail_rcu(&bdi->bdi_list, &bdi_list); |
34f8fe50 | 827 | |
46100071 TH |
828 | spin_unlock_bh(&bdi_lock); |
829 | ||
830 | trace_writeback_bdi_register(bdi); | |
831 | return 0; | |
b2e8fb6e | 832 | } |
baf7a616 | 833 | |
7c4cc300 | 834 | int bdi_register(struct backing_dev_info *bdi, const char *fmt, ...) |
baf7a616 JK |
835 | { |
836 | va_list args; | |
837 | int ret; | |
838 | ||
839 | va_start(args, fmt); | |
7c4cc300 | 840 | ret = bdi_register_va(bdi, fmt, args); |
baf7a616 JK |
841 | va_end(args); |
842 | return ret; | |
843 | } | |
46100071 | 844 | EXPORT_SYMBOL(bdi_register); |
b2e8fb6e | 845 | |
3c5d202b | 846 | void bdi_set_owner(struct backing_dev_info *bdi, struct device *owner) |
df08c32c | 847 | { |
3c5d202b | 848 | WARN_ON_ONCE(bdi->owner); |
df08c32c DW |
849 | bdi->owner = owner; |
850 | get_device(owner); | |
df08c32c | 851 | } |
df08c32c | 852 | |
46100071 TH |
853 | /* |
854 | * Remove bdi from bdi_list, and ensure that it is no longer visible | |
855 | */ | |
856 | static void bdi_remove_from_list(struct backing_dev_info *bdi) | |
857 | { | |
858 | spin_lock_bh(&bdi_lock); | |
34f8fe50 | 859 | rb_erase(&bdi->rb_node, &bdi_tree); |
46100071 TH |
860 | list_del_rcu(&bdi->bdi_list); |
861 | spin_unlock_bh(&bdi_lock); | |
b2e8fb6e | 862 | |
46100071 TH |
863 | synchronize_rcu_expedited(); |
864 | } | |
cf0ca9fe | 865 | |
b02176f3 | 866 | void bdi_unregister(struct backing_dev_info *bdi) |
b2e8fb6e | 867 | { |
f0054bb1 TH |
868 | /* make sure nobody finds us on the bdi_list anymore */ |
869 | bdi_remove_from_list(bdi); | |
870 | wb_shutdown(&bdi->wb); | |
b1c51afc | 871 | cgwb_bdi_unregister(bdi); |
7a401a97 | 872 | |
c4db59d3 CH |
873 | if (bdi->dev) { |
874 | bdi_debug_unregister(bdi); | |
875 | device_unregister(bdi->dev); | |
876 | bdi->dev = NULL; | |
877 | } | |
df08c32c DW |
878 | |
879 | if (bdi->owner) { | |
880 | put_device(bdi->owner); | |
881 | bdi->owner = NULL; | |
882 | } | |
b02176f3 | 883 | } |
c4db59d3 | 884 | |
d03f6cdc JK |
885 | static void release_bdi(struct kref *ref) |
886 | { | |
887 | struct backing_dev_info *bdi = | |
888 | container_of(ref, struct backing_dev_info, refcnt); | |
889 | ||
5af110b2 JK |
890 | if (test_bit(WB_registered, &bdi->wb.state)) |
891 | bdi_unregister(bdi); | |
2e82b84c JK |
892 | WARN_ON_ONCE(bdi->dev); |
893 | wb_exit(&bdi->wb); | |
d03f6cdc JK |
894 | kfree(bdi); |
895 | } | |
896 | ||
897 | void bdi_put(struct backing_dev_info *bdi) | |
898 | { | |
899 | kref_put(&bdi->refcnt, release_bdi); | |
900 | } | |
62bf42ad | 901 | EXPORT_SYMBOL(bdi_put); |
d03f6cdc | 902 | |
eb7ae5e0 CH |
903 | const char *bdi_dev_name(struct backing_dev_info *bdi) |
904 | { | |
905 | if (!bdi || !bdi->dev) | |
906 | return bdi_unknown_name; | |
6bd87eec | 907 | return bdi->dev_name; |
eb7ae5e0 CH |
908 | } |
909 | EXPORT_SYMBOL_GPL(bdi_dev_name); | |
910 | ||
3fcfab16 AM |
911 | static wait_queue_head_t congestion_wqh[2] = { |
912 | __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[0]), | |
913 | __WAIT_QUEUE_HEAD_INITIALIZER(congestion_wqh[1]) | |
914 | }; | |
ec8a6f26 | 915 | static atomic_t nr_wb_congested[2]; |
3fcfab16 | 916 | |
492d76b2 | 917 | void clear_bdi_congested(struct backing_dev_info *bdi, int sync) |
3fcfab16 | 918 | { |
1faa16d2 | 919 | wait_queue_head_t *wqh = &congestion_wqh[sync]; |
c877ef8a | 920 | enum wb_congested_state bit; |
3fcfab16 | 921 | |
4452226e | 922 | bit = sync ? WB_sync_congested : WB_async_congested; |
8c911f3d | 923 | if (test_and_clear_bit(bit, &bdi->wb.congested)) |
ec8a6f26 | 924 | atomic_dec(&nr_wb_congested[sync]); |
4e857c58 | 925 | smp_mb__after_atomic(); |
3fcfab16 AM |
926 | if (waitqueue_active(wqh)) |
927 | wake_up(wqh); | |
928 | } | |
492d76b2 | 929 | EXPORT_SYMBOL(clear_bdi_congested); |
3fcfab16 | 930 | |
492d76b2 | 931 | void set_bdi_congested(struct backing_dev_info *bdi, int sync) |
3fcfab16 | 932 | { |
c877ef8a | 933 | enum wb_congested_state bit; |
3fcfab16 | 934 | |
4452226e | 935 | bit = sync ? WB_sync_congested : WB_async_congested; |
8c911f3d | 936 | if (!test_and_set_bit(bit, &bdi->wb.congested)) |
ec8a6f26 | 937 | atomic_inc(&nr_wb_congested[sync]); |
3fcfab16 | 938 | } |
492d76b2 | 939 | EXPORT_SYMBOL(set_bdi_congested); |
3fcfab16 AM |
940 | |
941 | /** | |
942 | * congestion_wait - wait for a backing_dev to become uncongested | |
8aa7e847 | 943 | * @sync: SYNC or ASYNC IO |
3fcfab16 AM |
944 | * @timeout: timeout in jiffies |
945 | * | |
946 | * Waits for up to @timeout jiffies for a backing_dev (any backing_dev) to exit | |
947 | * write congestion. If no backing_devs are congested then just wait for the | |
948 | * next write to be completed. | |
949 | */ | |
8aa7e847 | 950 | long congestion_wait(int sync, long timeout) |
3fcfab16 AM |
951 | { |
952 | long ret; | |
52bb9198 | 953 | unsigned long start = jiffies; |
3fcfab16 | 954 | DEFINE_WAIT(wait); |
8aa7e847 | 955 | wait_queue_head_t *wqh = &congestion_wqh[sync]; |
3fcfab16 AM |
956 | |
957 | prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); | |
958 | ret = io_schedule_timeout(timeout); | |
959 | finish_wait(wqh, &wait); | |
52bb9198 MG |
960 | |
961 | trace_writeback_congestion_wait(jiffies_to_usecs(timeout), | |
962 | jiffies_to_usecs(jiffies - start)); | |
963 | ||
3fcfab16 AM |
964 | return ret; |
965 | } | |
966 | EXPORT_SYMBOL(congestion_wait); | |
04fbfdc1 | 967 | |
0e093d99 | 968 | /** |
599d0c95 | 969 | * wait_iff_congested - Conditionally wait for a backing_dev to become uncongested or a pgdat to complete writes |
0e093d99 MG |
970 | * @sync: SYNC or ASYNC IO |
971 | * @timeout: timeout in jiffies | |
972 | * | |
e3c1ac58 AR |
973 | * In the event of a congested backing_dev (any backing_dev) this waits |
974 | * for up to @timeout jiffies for either a BDI to exit congestion of the | |
975 | * given @sync queue or a write to complete. | |
0e093d99 MG |
976 | * |
977 | * The return value is 0 if the sleep is for the full timeout. Otherwise, | |
978 | * it is the number of jiffies that were still remaining when the function | |
979 | * returned. return_value == timeout implies the function did not sleep. | |
980 | */ | |
e3c1ac58 | 981 | long wait_iff_congested(int sync, long timeout) |
0e093d99 MG |
982 | { |
983 | long ret; | |
984 | unsigned long start = jiffies; | |
985 | DEFINE_WAIT(wait); | |
986 | wait_queue_head_t *wqh = &congestion_wqh[sync]; | |
987 | ||
988 | /* | |
e3c1ac58 | 989 | * If there is no congestion, yield if necessary instead |
0e093d99 MG |
990 | * of sleeping on the congestion queue |
991 | */ | |
e3c1ac58 | 992 | if (atomic_read(&nr_wb_congested[sync]) == 0) { |
ede37713 | 993 | cond_resched(); |
599d0c95 | 994 | |
0e093d99 MG |
995 | /* In case we scheduled, work out time remaining */ |
996 | ret = timeout - (jiffies - start); | |
997 | if (ret < 0) | |
998 | ret = 0; | |
999 | ||
1000 | goto out; | |
1001 | } | |
1002 | ||
1003 | /* Sleep until uncongested or a write happens */ | |
1004 | prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); | |
1005 | ret = io_schedule_timeout(timeout); | |
1006 | finish_wait(wqh, &wait); | |
1007 | ||
1008 | out: | |
1009 | trace_writeback_wait_iff_congested(jiffies_to_usecs(timeout), | |
1010 | jiffies_to_usecs(jiffies - start)); | |
1011 | ||
1012 | return ret; | |
1013 | } | |
1014 | EXPORT_SYMBOL(wait_iff_congested); |