Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * fs/fs-writeback.c | |
3 | * | |
4 | * Copyright (C) 2002, Linus Torvalds. | |
5 | * | |
6 | * Contains all the functions related to writing back and waiting | |
7 | * upon dirty inodes against superblocks, and writing back dirty | |
8 | * pages against inodes. ie: data writeback. Writeout of the | |
9 | * inode itself is not handled here. | |
10 | * | |
e1f8e874 | 11 | * 10Apr2002 Andrew Morton |
1da177e4 LT |
12 | * Split out of fs/inode.c |
13 | * Additions for address_space-based writeback | |
14 | */ | |
15 | ||
16 | #include <linux/kernel.h> | |
630d9c47 | 17 | #include <linux/export.h> |
1da177e4 | 18 | #include <linux/spinlock.h> |
5a0e3ad6 | 19 | #include <linux/slab.h> |
1da177e4 LT |
20 | #include <linux/sched.h> |
21 | #include <linux/fs.h> | |
22 | #include <linux/mm.h> | |
bc31b86a | 23 | #include <linux/pagemap.h> |
03ba3782 | 24 | #include <linux/kthread.h> |
1da177e4 LT |
25 | #include <linux/writeback.h> |
26 | #include <linux/blkdev.h> | |
27 | #include <linux/backing-dev.h> | |
455b2864 | 28 | #include <linux/tracepoint.h> |
719ea2fb | 29 | #include <linux/device.h> |
21c6321f | 30 | #include <linux/memcontrol.h> |
07f3f05c | 31 | #include "internal.h" |
1da177e4 | 32 | |
bc31b86a WF |
33 | /* |
34 | * 4MB minimal write chunk size | |
35 | */ | |
36 | #define MIN_WRITEBACK_PAGES (4096UL >> (PAGE_CACHE_SHIFT - 10)) | |
37 | ||
cc395d7f TH |
38 | struct wb_completion { |
39 | atomic_t cnt; | |
40 | }; | |
41 | ||
c4a77a6c JA |
42 | /* |
43 | * Passed into wb_writeback(), essentially a subset of writeback_control | |
44 | */ | |
83ba7b07 | 45 | struct wb_writeback_work { |
c4a77a6c JA |
46 | long nr_pages; |
47 | struct super_block *sb; | |
0dc83bd3 | 48 | unsigned long *older_than_this; |
c4a77a6c | 49 | enum writeback_sync_modes sync_mode; |
6e6938b6 | 50 | unsigned int tagged_writepages:1; |
52957fe1 HS |
51 | unsigned int for_kupdate:1; |
52 | unsigned int range_cyclic:1; | |
53 | unsigned int for_background:1; | |
7747bd4b | 54 | unsigned int for_sync:1; /* sync(2) WB_SYNC_ALL writeback */ |
ac7b19a3 | 55 | unsigned int auto_free:1; /* free on completion */ |
98754bf7 TH |
56 | unsigned int single_wait:1; |
57 | unsigned int single_done:1; | |
0e175a18 | 58 | enum wb_reason reason; /* why was writeback initiated? */ |
c4a77a6c | 59 | |
8010c3b6 | 60 | struct list_head list; /* pending work list */ |
cc395d7f | 61 | struct wb_completion *done; /* set if the caller waits */ |
03ba3782 JA |
62 | }; |
63 | ||
cc395d7f TH |
64 | /* |
65 | * If one wants to wait for one or more wb_writeback_works, each work's | |
66 | * ->done should be set to a wb_completion defined using the following | |
67 | * macro. Once all work items are issued with wb_queue_work(), the caller | |
68 | * can wait for the completion of all using wb_wait_for_completion(). Work | |
69 | * items which are waited upon aren't freed automatically on completion. | |
70 | */ | |
71 | #define DEFINE_WB_COMPLETION_ONSTACK(cmpl) \ | |
72 | struct wb_completion cmpl = { \ | |
73 | .cnt = ATOMIC_INIT(1), \ | |
74 | } | |
75 | ||
76 | ||
a2f48706 TT |
77 | /* |
78 | * If an inode is constantly having its pages dirtied, but then the | |
79 | * updates stop dirtytime_expire_interval seconds in the past, it's | |
80 | * possible for the worst case time between when an inode has its | |
81 | * timestamps updated and when they finally get written out to be two | |
82 | * dirtytime_expire_intervals. We set the default to 12 hours (in | |
83 | * seconds), which means most of the time inodes will have their | |
84 | * timestamps written to disk after 12 hours, but in the worst case a | |
85 | * few inodes might not their timestamps updated for 24 hours. | |
86 | */ | |
87 | unsigned int dirtytime_expire_interval = 12 * 60 * 60; | |
88 | ||
7ccf19a8 NP |
89 | static inline struct inode *wb_inode(struct list_head *head) |
90 | { | |
91 | return list_entry(head, struct inode, i_wb_list); | |
92 | } | |
93 | ||
15eb77a0 WF |
94 | /* |
95 | * Include the creation of the trace points after defining the | |
96 | * wb_writeback_work structure and inline functions so that the definition | |
97 | * remains local to this file. | |
98 | */ | |
99 | #define CREATE_TRACE_POINTS | |
100 | #include <trace/events/writeback.h> | |
101 | ||
774016b2 SW |
102 | EXPORT_TRACEPOINT_SYMBOL_GPL(wbc_writepage); |
103 | ||
d6c10f1f TH |
104 | static bool wb_io_lists_populated(struct bdi_writeback *wb) |
105 | { | |
106 | if (wb_has_dirty_io(wb)) { | |
107 | return false; | |
108 | } else { | |
109 | set_bit(WB_has_dirty_io, &wb->state); | |
95a46c65 | 110 | WARN_ON_ONCE(!wb->avg_write_bandwidth); |
766a9d6e TH |
111 | atomic_long_add(wb->avg_write_bandwidth, |
112 | &wb->bdi->tot_write_bandwidth); | |
d6c10f1f TH |
113 | return true; |
114 | } | |
115 | } | |
116 | ||
117 | static void wb_io_lists_depopulated(struct bdi_writeback *wb) | |
118 | { | |
119 | if (wb_has_dirty_io(wb) && list_empty(&wb->b_dirty) && | |
766a9d6e | 120 | list_empty(&wb->b_io) && list_empty(&wb->b_more_io)) { |
d6c10f1f | 121 | clear_bit(WB_has_dirty_io, &wb->state); |
95a46c65 TH |
122 | WARN_ON_ONCE(atomic_long_sub_return(wb->avg_write_bandwidth, |
123 | &wb->bdi->tot_write_bandwidth) < 0); | |
766a9d6e | 124 | } |
d6c10f1f TH |
125 | } |
126 | ||
127 | /** | |
128 | * inode_wb_list_move_locked - move an inode onto a bdi_writeback IO list | |
129 | * @inode: inode to be moved | |
130 | * @wb: target bdi_writeback | |
131 | * @head: one of @wb->b_{dirty|io|more_io} | |
132 | * | |
133 | * Move @inode->i_wb_list to @list of @wb and set %WB_has_dirty_io. | |
134 | * Returns %true if @inode is the first occupant of the !dirty_time IO | |
135 | * lists; otherwise, %false. | |
136 | */ | |
137 | static bool inode_wb_list_move_locked(struct inode *inode, | |
138 | struct bdi_writeback *wb, | |
139 | struct list_head *head) | |
140 | { | |
141 | assert_spin_locked(&wb->list_lock); | |
142 | ||
143 | list_move(&inode->i_wb_list, head); | |
144 | ||
145 | /* dirty_time doesn't count as dirty_io until expiration */ | |
146 | if (head != &wb->b_dirty_time) | |
147 | return wb_io_lists_populated(wb); | |
148 | ||
149 | wb_io_lists_depopulated(wb); | |
150 | return false; | |
151 | } | |
152 | ||
153 | /** | |
154 | * inode_wb_list_del_locked - remove an inode from its bdi_writeback IO list | |
155 | * @inode: inode to be removed | |
156 | * @wb: bdi_writeback @inode is being removed from | |
157 | * | |
158 | * Remove @inode which may be on one of @wb->b_{dirty|io|more_io} lists and | |
159 | * clear %WB_has_dirty_io if all are empty afterwards. | |
160 | */ | |
161 | static void inode_wb_list_del_locked(struct inode *inode, | |
162 | struct bdi_writeback *wb) | |
163 | { | |
164 | assert_spin_locked(&wb->list_lock); | |
165 | ||
166 | list_del_init(&inode->i_wb_list); | |
167 | wb_io_lists_depopulated(wb); | |
168 | } | |
169 | ||
f0054bb1 | 170 | static void wb_wakeup(struct bdi_writeback *wb) |
5acda9d1 | 171 | { |
f0054bb1 TH |
172 | spin_lock_bh(&wb->work_lock); |
173 | if (test_bit(WB_registered, &wb->state)) | |
174 | mod_delayed_work(bdi_wq, &wb->dwork, 0); | |
175 | spin_unlock_bh(&wb->work_lock); | |
5acda9d1 JK |
176 | } |
177 | ||
f0054bb1 TH |
178 | static void wb_queue_work(struct bdi_writeback *wb, |
179 | struct wb_writeback_work *work) | |
6585027a | 180 | { |
f0054bb1 | 181 | trace_writeback_queue(wb->bdi, work); |
6585027a | 182 | |
f0054bb1 | 183 | spin_lock_bh(&wb->work_lock); |
98754bf7 TH |
184 | if (!test_bit(WB_registered, &wb->state)) { |
185 | if (work->single_wait) | |
186 | work->single_done = 1; | |
5acda9d1 | 187 | goto out_unlock; |
98754bf7 | 188 | } |
cc395d7f TH |
189 | if (work->done) |
190 | atomic_inc(&work->done->cnt); | |
f0054bb1 TH |
191 | list_add_tail(&work->list, &wb->work_list); |
192 | mod_delayed_work(bdi_wq, &wb->dwork, 0); | |
5acda9d1 | 193 | out_unlock: |
f0054bb1 | 194 | spin_unlock_bh(&wb->work_lock); |
1da177e4 LT |
195 | } |
196 | ||
cc395d7f TH |
197 | /** |
198 | * wb_wait_for_completion - wait for completion of bdi_writeback_works | |
199 | * @bdi: bdi work items were issued to | |
200 | * @done: target wb_completion | |
201 | * | |
202 | * Wait for one or more work items issued to @bdi with their ->done field | |
203 | * set to @done, which should have been defined with | |
204 | * DEFINE_WB_COMPLETION_ONSTACK(). This function returns after all such | |
205 | * work items are completed. Work items which are waited upon aren't freed | |
206 | * automatically on completion. | |
207 | */ | |
208 | static void wb_wait_for_completion(struct backing_dev_info *bdi, | |
209 | struct wb_completion *done) | |
210 | { | |
211 | atomic_dec(&done->cnt); /* put down the initial count */ | |
212 | wait_event(bdi->wb_waitq, !atomic_read(&done->cnt)); | |
213 | } | |
214 | ||
703c2708 TH |
215 | #ifdef CONFIG_CGROUP_WRITEBACK |
216 | ||
2a814908 TH |
217 | /* parameters for foreign inode detection, see wb_detach_inode() */ |
218 | #define WB_FRN_TIME_SHIFT 13 /* 1s = 2^13, upto 8 secs w/ 16bit */ | |
219 | #define WB_FRN_TIME_AVG_SHIFT 3 /* avg = avg * 7/8 + new * 1/8 */ | |
220 | #define WB_FRN_TIME_CUT_DIV 2 /* ignore rounds < avg / 2 */ | |
221 | #define WB_FRN_TIME_PERIOD (2 * (1 << WB_FRN_TIME_SHIFT)) /* 2s */ | |
222 | ||
223 | #define WB_FRN_HIST_SLOTS 16 /* inode->i_wb_frn_history is 16bit */ | |
224 | #define WB_FRN_HIST_UNIT (WB_FRN_TIME_PERIOD / WB_FRN_HIST_SLOTS) | |
225 | /* each slot's duration is 2s / 16 */ | |
226 | #define WB_FRN_HIST_THR_SLOTS (WB_FRN_HIST_SLOTS / 2) | |
227 | /* if foreign slots >= 8, switch */ | |
228 | #define WB_FRN_HIST_MAX_SLOTS (WB_FRN_HIST_THR_SLOTS / 2 + 1) | |
229 | /* one round can affect upto 5 slots */ | |
230 | ||
21c6321f TH |
231 | void __inode_attach_wb(struct inode *inode, struct page *page) |
232 | { | |
233 | struct backing_dev_info *bdi = inode_to_bdi(inode); | |
234 | struct bdi_writeback *wb = NULL; | |
235 | ||
236 | if (inode_cgwb_enabled(inode)) { | |
237 | struct cgroup_subsys_state *memcg_css; | |
238 | ||
239 | if (page) { | |
240 | memcg_css = mem_cgroup_css_from_page(page); | |
241 | wb = wb_get_create(bdi, memcg_css, GFP_ATOMIC); | |
242 | } else { | |
243 | /* must pin memcg_css, see wb_get_create() */ | |
244 | memcg_css = task_get_css(current, memory_cgrp_id); | |
245 | wb = wb_get_create(bdi, memcg_css, GFP_ATOMIC); | |
246 | css_put(memcg_css); | |
247 | } | |
248 | } | |
249 | ||
250 | if (!wb) | |
251 | wb = &bdi->wb; | |
252 | ||
253 | /* | |
254 | * There may be multiple instances of this function racing to | |
255 | * update the same inode. Use cmpxchg() to tell the winner. | |
256 | */ | |
257 | if (unlikely(cmpxchg(&inode->i_wb, NULL, wb))) | |
258 | wb_put(wb); | |
259 | } | |
260 | ||
87e1d789 TH |
261 | /** |
262 | * locked_inode_to_wb_and_lock_list - determine a locked inode's wb and lock it | |
263 | * @inode: inode of interest with i_lock held | |
264 | * | |
265 | * Returns @inode's wb with its list_lock held. @inode->i_lock must be | |
266 | * held on entry and is released on return. The returned wb is guaranteed | |
267 | * to stay @inode's associated wb until its list_lock is released. | |
268 | */ | |
269 | static struct bdi_writeback * | |
270 | locked_inode_to_wb_and_lock_list(struct inode *inode) | |
271 | __releases(&inode->i_lock) | |
272 | __acquires(&wb->list_lock) | |
273 | { | |
274 | while (true) { | |
275 | struct bdi_writeback *wb = inode_to_wb(inode); | |
276 | ||
277 | /* | |
278 | * inode_to_wb() association is protected by both | |
279 | * @inode->i_lock and @wb->list_lock but list_lock nests | |
280 | * outside i_lock. Drop i_lock and verify that the | |
281 | * association hasn't changed after acquiring list_lock. | |
282 | */ | |
283 | wb_get(wb); | |
284 | spin_unlock(&inode->i_lock); | |
285 | spin_lock(&wb->list_lock); | |
286 | wb_put(wb); /* not gonna deref it anymore */ | |
287 | ||
aaa2cacf TH |
288 | /* i_wb may have changed inbetween, can't use inode_to_wb() */ |
289 | if (likely(wb == inode->i_wb)) | |
87e1d789 TH |
290 | return wb; /* @inode already has ref */ |
291 | ||
292 | spin_unlock(&wb->list_lock); | |
293 | cpu_relax(); | |
294 | spin_lock(&inode->i_lock); | |
295 | } | |
296 | } | |
297 | ||
298 | /** | |
299 | * inode_to_wb_and_lock_list - determine an inode's wb and lock it | |
300 | * @inode: inode of interest | |
301 | * | |
302 | * Same as locked_inode_to_wb_and_lock_list() but @inode->i_lock isn't held | |
303 | * on entry. | |
304 | */ | |
305 | static struct bdi_writeback *inode_to_wb_and_lock_list(struct inode *inode) | |
306 | __acquires(&wb->list_lock) | |
307 | { | |
308 | spin_lock(&inode->i_lock); | |
309 | return locked_inode_to_wb_and_lock_list(inode); | |
310 | } | |
311 | ||
682aa8e1 TH |
312 | struct inode_switch_wbs_context { |
313 | struct inode *inode; | |
314 | struct bdi_writeback *new_wb; | |
315 | ||
316 | struct rcu_head rcu_head; | |
317 | struct work_struct work; | |
318 | }; | |
319 | ||
320 | static void inode_switch_wbs_work_fn(struct work_struct *work) | |
321 | { | |
322 | struct inode_switch_wbs_context *isw = | |
323 | container_of(work, struct inode_switch_wbs_context, work); | |
324 | struct inode *inode = isw->inode; | |
d10c8095 TH |
325 | struct address_space *mapping = inode->i_mapping; |
326 | struct bdi_writeback *old_wb = inode->i_wb; | |
682aa8e1 | 327 | struct bdi_writeback *new_wb = isw->new_wb; |
d10c8095 TH |
328 | struct radix_tree_iter iter; |
329 | bool switched = false; | |
330 | void **slot; | |
682aa8e1 TH |
331 | |
332 | /* | |
333 | * By the time control reaches here, RCU grace period has passed | |
334 | * since I_WB_SWITCH assertion and all wb stat update transactions | |
335 | * between unlocked_inode_to_wb_begin/end() are guaranteed to be | |
336 | * synchronizing against mapping->tree_lock. | |
d10c8095 TH |
337 | * |
338 | * Grabbing old_wb->list_lock, inode->i_lock and mapping->tree_lock | |
339 | * gives us exclusion against all wb related operations on @inode | |
340 | * including IO list manipulations and stat updates. | |
682aa8e1 | 341 | */ |
d10c8095 TH |
342 | if (old_wb < new_wb) { |
343 | spin_lock(&old_wb->list_lock); | |
344 | spin_lock_nested(&new_wb->list_lock, SINGLE_DEPTH_NESTING); | |
345 | } else { | |
346 | spin_lock(&new_wb->list_lock); | |
347 | spin_lock_nested(&old_wb->list_lock, SINGLE_DEPTH_NESTING); | |
348 | } | |
682aa8e1 | 349 | spin_lock(&inode->i_lock); |
d10c8095 TH |
350 | spin_lock_irq(&mapping->tree_lock); |
351 | ||
352 | /* | |
353 | * Once I_FREEING is visible under i_lock, the eviction path owns | |
354 | * the inode and we shouldn't modify ->i_wb_list. | |
355 | */ | |
356 | if (unlikely(inode->i_state & I_FREEING)) | |
357 | goto skip_switch; | |
358 | ||
359 | /* | |
360 | * Count and transfer stats. Note that PAGECACHE_TAG_DIRTY points | |
361 | * to possibly dirty pages while PAGECACHE_TAG_WRITEBACK points to | |
362 | * pages actually under underwriteback. | |
363 | */ | |
364 | radix_tree_for_each_tagged(slot, &mapping->page_tree, &iter, 0, | |
365 | PAGECACHE_TAG_DIRTY) { | |
366 | struct page *page = radix_tree_deref_slot_protected(slot, | |
367 | &mapping->tree_lock); | |
368 | if (likely(page) && PageDirty(page)) { | |
369 | __dec_wb_stat(old_wb, WB_RECLAIMABLE); | |
370 | __inc_wb_stat(new_wb, WB_RECLAIMABLE); | |
371 | } | |
372 | } | |
373 | ||
374 | radix_tree_for_each_tagged(slot, &mapping->page_tree, &iter, 0, | |
375 | PAGECACHE_TAG_WRITEBACK) { | |
376 | struct page *page = radix_tree_deref_slot_protected(slot, | |
377 | &mapping->tree_lock); | |
378 | if (likely(page)) { | |
379 | WARN_ON_ONCE(!PageWriteback(page)); | |
380 | __dec_wb_stat(old_wb, WB_WRITEBACK); | |
381 | __inc_wb_stat(new_wb, WB_WRITEBACK); | |
382 | } | |
383 | } | |
384 | ||
385 | wb_get(new_wb); | |
386 | ||
387 | /* | |
388 | * Transfer to @new_wb's IO list if necessary. The specific list | |
389 | * @inode was on is ignored and the inode is put on ->b_dirty which | |
390 | * is always correct including from ->b_dirty_time. The transfer | |
391 | * preserves @inode->dirtied_when ordering. | |
392 | */ | |
393 | if (!list_empty(&inode->i_wb_list)) { | |
394 | struct inode *pos; | |
395 | ||
396 | inode_wb_list_del_locked(inode, old_wb); | |
397 | inode->i_wb = new_wb; | |
398 | list_for_each_entry(pos, &new_wb->b_dirty, i_wb_list) | |
399 | if (time_after_eq(inode->dirtied_when, | |
400 | pos->dirtied_when)) | |
401 | break; | |
402 | inode_wb_list_move_locked(inode, new_wb, pos->i_wb_list.prev); | |
403 | } else { | |
404 | inode->i_wb = new_wb; | |
405 | } | |
682aa8e1 | 406 | |
d10c8095 | 407 | /* ->i_wb_frn updates may race wbc_detach_inode() but doesn't matter */ |
682aa8e1 TH |
408 | inode->i_wb_frn_winner = 0; |
409 | inode->i_wb_frn_avg_time = 0; | |
410 | inode->i_wb_frn_history = 0; | |
d10c8095 TH |
411 | switched = true; |
412 | skip_switch: | |
682aa8e1 TH |
413 | /* |
414 | * Paired with load_acquire in unlocked_inode_to_wb_begin() and | |
415 | * ensures that the new wb is visible if they see !I_WB_SWITCH. | |
416 | */ | |
417 | smp_store_release(&inode->i_state, inode->i_state & ~I_WB_SWITCH); | |
418 | ||
d10c8095 | 419 | spin_unlock_irq(&mapping->tree_lock); |
682aa8e1 | 420 | spin_unlock(&inode->i_lock); |
d10c8095 TH |
421 | spin_unlock(&new_wb->list_lock); |
422 | spin_unlock(&old_wb->list_lock); | |
682aa8e1 | 423 | |
d10c8095 TH |
424 | if (switched) { |
425 | wb_wakeup(new_wb); | |
426 | wb_put(old_wb); | |
427 | } | |
682aa8e1 | 428 | wb_put(new_wb); |
d10c8095 TH |
429 | |
430 | iput(inode); | |
682aa8e1 TH |
431 | kfree(isw); |
432 | } | |
433 | ||
434 | static void inode_switch_wbs_rcu_fn(struct rcu_head *rcu_head) | |
435 | { | |
436 | struct inode_switch_wbs_context *isw = container_of(rcu_head, | |
437 | struct inode_switch_wbs_context, rcu_head); | |
438 | ||
439 | /* needs to grab bh-unsafe locks, bounce to work item */ | |
440 | INIT_WORK(&isw->work, inode_switch_wbs_work_fn); | |
441 | schedule_work(&isw->work); | |
442 | } | |
443 | ||
444 | /** | |
445 | * inode_switch_wbs - change the wb association of an inode | |
446 | * @inode: target inode | |
447 | * @new_wb_id: ID of the new wb | |
448 | * | |
449 | * Switch @inode's wb association to the wb identified by @new_wb_id. The | |
450 | * switching is performed asynchronously and may fail silently. | |
451 | */ | |
452 | static void inode_switch_wbs(struct inode *inode, int new_wb_id) | |
453 | { | |
454 | struct backing_dev_info *bdi = inode_to_bdi(inode); | |
455 | struct cgroup_subsys_state *memcg_css; | |
456 | struct inode_switch_wbs_context *isw; | |
457 | ||
458 | /* noop if seems to be already in progress */ | |
459 | if (inode->i_state & I_WB_SWITCH) | |
460 | return; | |
461 | ||
462 | isw = kzalloc(sizeof(*isw), GFP_ATOMIC); | |
463 | if (!isw) | |
464 | return; | |
465 | ||
466 | /* find and pin the new wb */ | |
467 | rcu_read_lock(); | |
468 | memcg_css = css_from_id(new_wb_id, &memory_cgrp_subsys); | |
469 | if (memcg_css) | |
470 | isw->new_wb = wb_get_create(bdi, memcg_css, GFP_ATOMIC); | |
471 | rcu_read_unlock(); | |
472 | if (!isw->new_wb) | |
473 | goto out_free; | |
474 | ||
475 | /* while holding I_WB_SWITCH, no one else can update the association */ | |
476 | spin_lock(&inode->i_lock); | |
477 | if (inode->i_state & (I_WB_SWITCH | I_FREEING) || | |
478 | inode_to_wb(inode) == isw->new_wb) { | |
479 | spin_unlock(&inode->i_lock); | |
480 | goto out_free; | |
481 | } | |
482 | inode->i_state |= I_WB_SWITCH; | |
483 | spin_unlock(&inode->i_lock); | |
484 | ||
485 | ihold(inode); | |
486 | isw->inode = inode; | |
487 | ||
488 | /* | |
489 | * In addition to synchronizing among switchers, I_WB_SWITCH tells | |
490 | * the RCU protected stat update paths to grab the mapping's | |
491 | * tree_lock so that stat transfer can synchronize against them. | |
492 | * Let's continue after I_WB_SWITCH is guaranteed to be visible. | |
493 | */ | |
494 | call_rcu(&isw->rcu_head, inode_switch_wbs_rcu_fn); | |
495 | return; | |
496 | ||
497 | out_free: | |
498 | if (isw->new_wb) | |
499 | wb_put(isw->new_wb); | |
500 | kfree(isw); | |
501 | } | |
502 | ||
b16b1deb TH |
503 | /** |
504 | * wbc_attach_and_unlock_inode - associate wbc with target inode and unlock it | |
505 | * @wbc: writeback_control of interest | |
506 | * @inode: target inode | |
507 | * | |
508 | * @inode is locked and about to be written back under the control of @wbc. | |
509 | * Record @inode's writeback context into @wbc and unlock the i_lock. On | |
510 | * writeback completion, wbc_detach_inode() should be called. This is used | |
511 | * to track the cgroup writeback context. | |
512 | */ | |
513 | void wbc_attach_and_unlock_inode(struct writeback_control *wbc, | |
514 | struct inode *inode) | |
515 | { | |
dd73e4b7 TH |
516 | if (!inode_cgwb_enabled(inode)) { |
517 | spin_unlock(&inode->i_lock); | |
518 | return; | |
519 | } | |
520 | ||
b16b1deb | 521 | wbc->wb = inode_to_wb(inode); |
2a814908 TH |
522 | wbc->inode = inode; |
523 | ||
524 | wbc->wb_id = wbc->wb->memcg_css->id; | |
525 | wbc->wb_lcand_id = inode->i_wb_frn_winner; | |
526 | wbc->wb_tcand_id = 0; | |
527 | wbc->wb_bytes = 0; | |
528 | wbc->wb_lcand_bytes = 0; | |
529 | wbc->wb_tcand_bytes = 0; | |
530 | ||
b16b1deb TH |
531 | wb_get(wbc->wb); |
532 | spin_unlock(&inode->i_lock); | |
e8a7abf5 TH |
533 | |
534 | /* | |
535 | * A dying wb indicates that the memcg-blkcg mapping has changed | |
536 | * and a new wb is already serving the memcg. Switch immediately. | |
537 | */ | |
538 | if (unlikely(wb_dying(wbc->wb))) | |
539 | inode_switch_wbs(inode, wbc->wb_id); | |
b16b1deb TH |
540 | } |
541 | ||
542 | /** | |
2a814908 TH |
543 | * wbc_detach_inode - disassociate wbc from inode and perform foreign detection |
544 | * @wbc: writeback_control of the just finished writeback | |
b16b1deb TH |
545 | * |
546 | * To be called after a writeback attempt of an inode finishes and undoes | |
547 | * wbc_attach_and_unlock_inode(). Can be called under any context. | |
2a814908 TH |
548 | * |
549 | * As concurrent write sharing of an inode is expected to be very rare and | |
550 | * memcg only tracks page ownership on first-use basis severely confining | |
551 | * the usefulness of such sharing, cgroup writeback tracks ownership | |
552 | * per-inode. While the support for concurrent write sharing of an inode | |
553 | * is deemed unnecessary, an inode being written to by different cgroups at | |
554 | * different points in time is a lot more common, and, more importantly, | |
555 | * charging only by first-use can too readily lead to grossly incorrect | |
556 | * behaviors (single foreign page can lead to gigabytes of writeback to be | |
557 | * incorrectly attributed). | |
558 | * | |
559 | * To resolve this issue, cgroup writeback detects the majority dirtier of | |
560 | * an inode and transfers the ownership to it. To avoid unnnecessary | |
561 | * oscillation, the detection mechanism keeps track of history and gives | |
562 | * out the switch verdict only if the foreign usage pattern is stable over | |
563 | * a certain amount of time and/or writeback attempts. | |
564 | * | |
565 | * On each writeback attempt, @wbc tries to detect the majority writer | |
566 | * using Boyer-Moore majority vote algorithm. In addition to the byte | |
567 | * count from the majority voting, it also counts the bytes written for the | |
568 | * current wb and the last round's winner wb (max of last round's current | |
569 | * wb, the winner from two rounds ago, and the last round's majority | |
570 | * candidate). Keeping track of the historical winner helps the algorithm | |
571 | * to semi-reliably detect the most active writer even when it's not the | |
572 | * absolute majority. | |
573 | * | |
574 | * Once the winner of the round is determined, whether the winner is | |
575 | * foreign or not and how much IO time the round consumed is recorded in | |
576 | * inode->i_wb_frn_history. If the amount of recorded foreign IO time is | |
577 | * over a certain threshold, the switch verdict is given. | |
b16b1deb TH |
578 | */ |
579 | void wbc_detach_inode(struct writeback_control *wbc) | |
580 | { | |
2a814908 TH |
581 | struct bdi_writeback *wb = wbc->wb; |
582 | struct inode *inode = wbc->inode; | |
dd73e4b7 TH |
583 | unsigned long avg_time, max_bytes, max_time; |
584 | u16 history; | |
2a814908 TH |
585 | int max_id; |
586 | ||
dd73e4b7 TH |
587 | if (!wb) |
588 | return; | |
589 | ||
590 | history = inode->i_wb_frn_history; | |
591 | avg_time = inode->i_wb_frn_avg_time; | |
592 | ||
2a814908 TH |
593 | /* pick the winner of this round */ |
594 | if (wbc->wb_bytes >= wbc->wb_lcand_bytes && | |
595 | wbc->wb_bytes >= wbc->wb_tcand_bytes) { | |
596 | max_id = wbc->wb_id; | |
597 | max_bytes = wbc->wb_bytes; | |
598 | } else if (wbc->wb_lcand_bytes >= wbc->wb_tcand_bytes) { | |
599 | max_id = wbc->wb_lcand_id; | |
600 | max_bytes = wbc->wb_lcand_bytes; | |
601 | } else { | |
602 | max_id = wbc->wb_tcand_id; | |
603 | max_bytes = wbc->wb_tcand_bytes; | |
604 | } | |
605 | ||
606 | /* | |
607 | * Calculate the amount of IO time the winner consumed and fold it | |
608 | * into the running average kept per inode. If the consumed IO | |
609 | * time is lower than avag / WB_FRN_TIME_CUT_DIV, ignore it for | |
610 | * deciding whether to switch or not. This is to prevent one-off | |
611 | * small dirtiers from skewing the verdict. | |
612 | */ | |
613 | max_time = DIV_ROUND_UP((max_bytes >> PAGE_SHIFT) << WB_FRN_TIME_SHIFT, | |
614 | wb->avg_write_bandwidth); | |
615 | if (avg_time) | |
616 | avg_time += (max_time >> WB_FRN_TIME_AVG_SHIFT) - | |
617 | (avg_time >> WB_FRN_TIME_AVG_SHIFT); | |
618 | else | |
619 | avg_time = max_time; /* immediate catch up on first run */ | |
620 | ||
621 | if (max_time >= avg_time / WB_FRN_TIME_CUT_DIV) { | |
622 | int slots; | |
623 | ||
624 | /* | |
625 | * The switch verdict is reached if foreign wb's consume | |
626 | * more than a certain proportion of IO time in a | |
627 | * WB_FRN_TIME_PERIOD. This is loosely tracked by 16 slot | |
628 | * history mask where each bit represents one sixteenth of | |
629 | * the period. Determine the number of slots to shift into | |
630 | * history from @max_time. | |
631 | */ | |
632 | slots = min(DIV_ROUND_UP(max_time, WB_FRN_HIST_UNIT), | |
633 | (unsigned long)WB_FRN_HIST_MAX_SLOTS); | |
634 | history <<= slots; | |
635 | if (wbc->wb_id != max_id) | |
636 | history |= (1U << slots) - 1; | |
637 | ||
638 | /* | |
639 | * Switch if the current wb isn't the consistent winner. | |
640 | * If there are multiple closely competing dirtiers, the | |
641 | * inode may switch across them repeatedly over time, which | |
642 | * is okay. The main goal is avoiding keeping an inode on | |
643 | * the wrong wb for an extended period of time. | |
644 | */ | |
682aa8e1 TH |
645 | if (hweight32(history) > WB_FRN_HIST_THR_SLOTS) |
646 | inode_switch_wbs(inode, max_id); | |
2a814908 TH |
647 | } |
648 | ||
649 | /* | |
650 | * Multiple instances of this function may race to update the | |
651 | * following fields but we don't mind occassional inaccuracies. | |
652 | */ | |
653 | inode->i_wb_frn_winner = max_id; | |
654 | inode->i_wb_frn_avg_time = min(avg_time, (unsigned long)U16_MAX); | |
655 | inode->i_wb_frn_history = history; | |
656 | ||
b16b1deb TH |
657 | wb_put(wbc->wb); |
658 | wbc->wb = NULL; | |
659 | } | |
660 | ||
2a814908 TH |
661 | /** |
662 | * wbc_account_io - account IO issued during writeback | |
663 | * @wbc: writeback_control of the writeback in progress | |
664 | * @page: page being written out | |
665 | * @bytes: number of bytes being written out | |
666 | * | |
667 | * @bytes from @page are about to written out during the writeback | |
668 | * controlled by @wbc. Keep the book for foreign inode detection. See | |
669 | * wbc_detach_inode(). | |
670 | */ | |
671 | void wbc_account_io(struct writeback_control *wbc, struct page *page, | |
672 | size_t bytes) | |
673 | { | |
674 | int id; | |
675 | ||
676 | /* | |
677 | * pageout() path doesn't attach @wbc to the inode being written | |
678 | * out. This is intentional as we don't want the function to block | |
679 | * behind a slow cgroup. Ultimately, we want pageout() to kick off | |
680 | * regular writeback instead of writing things out itself. | |
681 | */ | |
682 | if (!wbc->wb) | |
683 | return; | |
684 | ||
685 | rcu_read_lock(); | |
686 | id = mem_cgroup_css_from_page(page)->id; | |
687 | rcu_read_unlock(); | |
688 | ||
689 | if (id == wbc->wb_id) { | |
690 | wbc->wb_bytes += bytes; | |
691 | return; | |
692 | } | |
693 | ||
694 | if (id == wbc->wb_lcand_id) | |
695 | wbc->wb_lcand_bytes += bytes; | |
696 | ||
697 | /* Boyer-Moore majority vote algorithm */ | |
698 | if (!wbc->wb_tcand_bytes) | |
699 | wbc->wb_tcand_id = id; | |
700 | if (id == wbc->wb_tcand_id) | |
701 | wbc->wb_tcand_bytes += bytes; | |
702 | else | |
703 | wbc->wb_tcand_bytes -= min(bytes, wbc->wb_tcand_bytes); | |
704 | } | |
705 | ||
703c2708 TH |
706 | /** |
707 | * inode_congested - test whether an inode is congested | |
708 | * @inode: inode to test for congestion | |
709 | * @cong_bits: mask of WB_[a]sync_congested bits to test | |
710 | * | |
711 | * Tests whether @inode is congested. @cong_bits is the mask of congestion | |
712 | * bits to test and the return value is the mask of set bits. | |
713 | * | |
714 | * If cgroup writeback is enabled for @inode, the congestion state is | |
715 | * determined by whether the cgwb (cgroup bdi_writeback) for the blkcg | |
716 | * associated with @inode is congested; otherwise, the root wb's congestion | |
717 | * state is used. | |
718 | */ | |
719 | int inode_congested(struct inode *inode, int cong_bits) | |
720 | { | |
5cb8b824 TH |
721 | /* |
722 | * Once set, ->i_wb never becomes NULL while the inode is alive. | |
723 | * Start transaction iff ->i_wb is visible. | |
724 | */ | |
aaa2cacf | 725 | if (inode && inode_to_wb_is_valid(inode)) { |
5cb8b824 TH |
726 | struct bdi_writeback *wb; |
727 | bool locked, congested; | |
728 | ||
729 | wb = unlocked_inode_to_wb_begin(inode, &locked); | |
730 | congested = wb_congested(wb, cong_bits); | |
731 | unlocked_inode_to_wb_end(inode, locked); | |
732 | return congested; | |
703c2708 TH |
733 | } |
734 | ||
735 | return wb_congested(&inode_to_bdi(inode)->wb, cong_bits); | |
736 | } | |
737 | EXPORT_SYMBOL_GPL(inode_congested); | |
738 | ||
98754bf7 TH |
739 | /** |
740 | * wb_wait_for_single_work - wait for completion of a single bdi_writeback_work | |
741 | * @bdi: bdi the work item was issued to | |
742 | * @work: work item to wait for | |
743 | * | |
744 | * Wait for the completion of @work which was issued to one of @bdi's | |
745 | * bdi_writeback's. The caller must have set @work->single_wait before | |
746 | * issuing it. This wait operates independently fo | |
747 | * wb_wait_for_completion() and also disables automatic freeing of @work. | |
748 | */ | |
749 | static void wb_wait_for_single_work(struct backing_dev_info *bdi, | |
750 | struct wb_writeback_work *work) | |
751 | { | |
752 | if (WARN_ON_ONCE(!work->single_wait)) | |
753 | return; | |
754 | ||
755 | wait_event(bdi->wb_waitq, work->single_done); | |
756 | ||
757 | /* | |
758 | * Paired with smp_wmb() in wb_do_writeback() and ensures that all | |
759 | * modifications to @work prior to assertion of ->single_done is | |
760 | * visible to the caller once this function returns. | |
761 | */ | |
762 | smp_rmb(); | |
763 | } | |
764 | ||
f2b65121 TH |
765 | /** |
766 | * wb_split_bdi_pages - split nr_pages to write according to bandwidth | |
767 | * @wb: target bdi_writeback to split @nr_pages to | |
768 | * @nr_pages: number of pages to write for the whole bdi | |
769 | * | |
770 | * Split @wb's portion of @nr_pages according to @wb's write bandwidth in | |
771 | * relation to the total write bandwidth of all wb's w/ dirty inodes on | |
772 | * @wb->bdi. | |
773 | */ | |
774 | static long wb_split_bdi_pages(struct bdi_writeback *wb, long nr_pages) | |
775 | { | |
776 | unsigned long this_bw = wb->avg_write_bandwidth; | |
777 | unsigned long tot_bw = atomic_long_read(&wb->bdi->tot_write_bandwidth); | |
778 | ||
779 | if (nr_pages == LONG_MAX) | |
780 | return LONG_MAX; | |
781 | ||
782 | /* | |
783 | * This may be called on clean wb's and proportional distribution | |
784 | * may not make sense, just use the original @nr_pages in those | |
785 | * cases. In general, we wanna err on the side of writing more. | |
786 | */ | |
787 | if (!tot_bw || this_bw >= tot_bw) | |
788 | return nr_pages; | |
789 | else | |
790 | return DIV_ROUND_UP_ULL((u64)nr_pages * this_bw, tot_bw); | |
791 | } | |
792 | ||
db125360 TH |
793 | /** |
794 | * wb_clone_and_queue_work - clone a wb_writeback_work and issue it to a wb | |
795 | * @wb: target bdi_writeback | |
796 | * @base_work: source wb_writeback_work | |
797 | * | |
798 | * Try to make a clone of @base_work and issue it to @wb. If cloning | |
799 | * succeeds, %true is returned; otherwise, @base_work is issued directly | |
800 | * and %false is returned. In the latter case, the caller is required to | |
801 | * wait for @base_work's completion using wb_wait_for_single_work(). | |
802 | * | |
803 | * A clone is auto-freed on completion. @base_work never is. | |
804 | */ | |
805 | static bool wb_clone_and_queue_work(struct bdi_writeback *wb, | |
806 | struct wb_writeback_work *base_work) | |
807 | { | |
808 | struct wb_writeback_work *work; | |
809 | ||
810 | work = kmalloc(sizeof(*work), GFP_ATOMIC); | |
811 | if (work) { | |
812 | *work = *base_work; | |
813 | work->auto_free = 1; | |
814 | work->single_wait = 0; | |
815 | } else { | |
816 | work = base_work; | |
817 | work->auto_free = 0; | |
818 | work->single_wait = 1; | |
819 | } | |
820 | work->single_done = 0; | |
821 | wb_queue_work(wb, work); | |
822 | return work != base_work; | |
823 | } | |
824 | ||
825 | /** | |
826 | * bdi_split_work_to_wbs - split a wb_writeback_work to all wb's of a bdi | |
827 | * @bdi: target backing_dev_info | |
828 | * @base_work: wb_writeback_work to issue | |
829 | * @skip_if_busy: skip wb's which already have writeback in progress | |
830 | * | |
831 | * Split and issue @base_work to all wb's (bdi_writeback's) of @bdi which | |
832 | * have dirty inodes. If @base_work->nr_page isn't %LONG_MAX, it's | |
833 | * distributed to the busy wbs according to each wb's proportion in the | |
834 | * total active write bandwidth of @bdi. | |
835 | */ | |
836 | static void bdi_split_work_to_wbs(struct backing_dev_info *bdi, | |
837 | struct wb_writeback_work *base_work, | |
838 | bool skip_if_busy) | |
839 | { | |
840 | long nr_pages = base_work->nr_pages; | |
841 | int next_blkcg_id = 0; | |
842 | struct bdi_writeback *wb; | |
843 | struct wb_iter iter; | |
844 | ||
845 | might_sleep(); | |
846 | ||
847 | if (!bdi_has_dirty_io(bdi)) | |
848 | return; | |
849 | restart: | |
850 | rcu_read_lock(); | |
851 | bdi_for_each_wb(wb, bdi, &iter, next_blkcg_id) { | |
852 | if (!wb_has_dirty_io(wb) || | |
853 | (skip_if_busy && writeback_in_progress(wb))) | |
854 | continue; | |
855 | ||
856 | base_work->nr_pages = wb_split_bdi_pages(wb, nr_pages); | |
857 | if (!wb_clone_and_queue_work(wb, base_work)) { | |
858 | next_blkcg_id = wb->blkcg_css->id + 1; | |
859 | rcu_read_unlock(); | |
860 | wb_wait_for_single_work(bdi, base_work); | |
861 | goto restart; | |
862 | } | |
863 | } | |
864 | rcu_read_unlock(); | |
865 | } | |
866 | ||
f2b65121 TH |
867 | #else /* CONFIG_CGROUP_WRITEBACK */ |
868 | ||
87e1d789 TH |
869 | static struct bdi_writeback * |
870 | locked_inode_to_wb_and_lock_list(struct inode *inode) | |
871 | __releases(&inode->i_lock) | |
872 | __acquires(&wb->list_lock) | |
873 | { | |
874 | struct bdi_writeback *wb = inode_to_wb(inode); | |
875 | ||
876 | spin_unlock(&inode->i_lock); | |
877 | spin_lock(&wb->list_lock); | |
878 | return wb; | |
879 | } | |
880 | ||
881 | static struct bdi_writeback *inode_to_wb_and_lock_list(struct inode *inode) | |
882 | __acquires(&wb->list_lock) | |
883 | { | |
884 | struct bdi_writeback *wb = inode_to_wb(inode); | |
885 | ||
886 | spin_lock(&wb->list_lock); | |
887 | return wb; | |
888 | } | |
889 | ||
f2b65121 TH |
890 | static long wb_split_bdi_pages(struct bdi_writeback *wb, long nr_pages) |
891 | { | |
892 | return nr_pages; | |
893 | } | |
894 | ||
db125360 TH |
895 | static void bdi_split_work_to_wbs(struct backing_dev_info *bdi, |
896 | struct wb_writeback_work *base_work, | |
897 | bool skip_if_busy) | |
898 | { | |
899 | might_sleep(); | |
900 | ||
901 | if (bdi_has_dirty_io(bdi) && | |
902 | (!skip_if_busy || !writeback_in_progress(&bdi->wb))) { | |
903 | base_work->auto_free = 0; | |
904 | base_work->single_wait = 0; | |
905 | base_work->single_done = 0; | |
906 | wb_queue_work(&bdi->wb, base_work); | |
907 | } | |
908 | } | |
909 | ||
703c2708 TH |
910 | #endif /* CONFIG_CGROUP_WRITEBACK */ |
911 | ||
c00ddad3 TH |
912 | void wb_start_writeback(struct bdi_writeback *wb, long nr_pages, |
913 | bool range_cyclic, enum wb_reason reason) | |
b6e51316 | 914 | { |
c00ddad3 TH |
915 | struct wb_writeback_work *work; |
916 | ||
917 | if (!wb_has_dirty_io(wb)) | |
918 | return; | |
919 | ||
920 | /* | |
921 | * This is WB_SYNC_NONE writeback, so if allocation fails just | |
922 | * wakeup the thread for old dirty data writeback | |
923 | */ | |
924 | work = kzalloc(sizeof(*work), GFP_ATOMIC); | |
925 | if (!work) { | |
926 | trace_writeback_nowork(wb->bdi); | |
927 | wb_wakeup(wb); | |
928 | return; | |
929 | } | |
930 | ||
931 | work->sync_mode = WB_SYNC_NONE; | |
932 | work->nr_pages = nr_pages; | |
933 | work->range_cyclic = range_cyclic; | |
934 | work->reason = reason; | |
ac7b19a3 | 935 | work->auto_free = 1; |
c00ddad3 TH |
936 | |
937 | wb_queue_work(wb, work); | |
c5444198 | 938 | } |
d3ddec76 | 939 | |
c5444198 | 940 | /** |
9ecf4866 TH |
941 | * wb_start_background_writeback - start background writeback |
942 | * @wb: bdi_writback to write from | |
c5444198 CH |
943 | * |
944 | * Description: | |
6585027a | 945 | * This makes sure WB_SYNC_NONE background writeback happens. When |
9ecf4866 | 946 | * this function returns, it is only guaranteed that for given wb |
6585027a JK |
947 | * some IO is happening if we are over background dirty threshold. |
948 | * Caller need not hold sb s_umount semaphore. | |
c5444198 | 949 | */ |
9ecf4866 | 950 | void wb_start_background_writeback(struct bdi_writeback *wb) |
c5444198 | 951 | { |
6585027a JK |
952 | /* |
953 | * We just wake up the flusher thread. It will perform background | |
954 | * writeback as soon as there is no other work to do. | |
955 | */ | |
9ecf4866 TH |
956 | trace_writeback_wake_background(wb->bdi); |
957 | wb_wakeup(wb); | |
1da177e4 LT |
958 | } |
959 | ||
a66979ab DC |
960 | /* |
961 | * Remove the inode from the writeback list it is on. | |
962 | */ | |
963 | void inode_wb_list_del(struct inode *inode) | |
964 | { | |
87e1d789 | 965 | struct bdi_writeback *wb; |
f758eeab | 966 | |
87e1d789 | 967 | wb = inode_to_wb_and_lock_list(inode); |
d6c10f1f | 968 | inode_wb_list_del_locked(inode, wb); |
52ebea74 | 969 | spin_unlock(&wb->list_lock); |
a66979ab DC |
970 | } |
971 | ||
6610a0bc AM |
972 | /* |
973 | * Redirty an inode: set its when-it-was dirtied timestamp and move it to the | |
974 | * furthest end of its superblock's dirty-inode list. | |
975 | * | |
976 | * Before stamping the inode's ->dirtied_when, we check to see whether it is | |
66f3b8e2 | 977 | * already the most-recently-dirtied inode on the b_dirty list. If that is |
6610a0bc AM |
978 | * the case then the inode must have been redirtied while it was being written |
979 | * out and we don't reset its dirtied_when. | |
980 | */ | |
f758eeab | 981 | static void redirty_tail(struct inode *inode, struct bdi_writeback *wb) |
6610a0bc | 982 | { |
03ba3782 | 983 | if (!list_empty(&wb->b_dirty)) { |
66f3b8e2 | 984 | struct inode *tail; |
6610a0bc | 985 | |
7ccf19a8 | 986 | tail = wb_inode(wb->b_dirty.next); |
66f3b8e2 | 987 | if (time_before(inode->dirtied_when, tail->dirtied_when)) |
6610a0bc AM |
988 | inode->dirtied_when = jiffies; |
989 | } | |
d6c10f1f | 990 | inode_wb_list_move_locked(inode, wb, &wb->b_dirty); |
6610a0bc AM |
991 | } |
992 | ||
c986d1e2 | 993 | /* |
66f3b8e2 | 994 | * requeue inode for re-scanning after bdi->b_io list is exhausted. |
c986d1e2 | 995 | */ |
f758eeab | 996 | static void requeue_io(struct inode *inode, struct bdi_writeback *wb) |
c986d1e2 | 997 | { |
d6c10f1f | 998 | inode_wb_list_move_locked(inode, wb, &wb->b_more_io); |
c986d1e2 AM |
999 | } |
1000 | ||
1c0eeaf5 JE |
1001 | static void inode_sync_complete(struct inode *inode) |
1002 | { | |
365b94ae | 1003 | inode->i_state &= ~I_SYNC; |
4eff96dd JK |
1004 | /* If inode is clean an unused, put it into LRU now... */ |
1005 | inode_add_lru(inode); | |
365b94ae | 1006 | /* Waiters must see I_SYNC cleared before being woken up */ |
1c0eeaf5 JE |
1007 | smp_mb(); |
1008 | wake_up_bit(&inode->i_state, __I_SYNC); | |
1009 | } | |
1010 | ||
d2caa3c5 JL |
1011 | static bool inode_dirtied_after(struct inode *inode, unsigned long t) |
1012 | { | |
1013 | bool ret = time_after(inode->dirtied_when, t); | |
1014 | #ifndef CONFIG_64BIT | |
1015 | /* | |
1016 | * For inodes being constantly redirtied, dirtied_when can get stuck. | |
1017 | * It _appears_ to be in the future, but is actually in distant past. | |
1018 | * This test is necessary to prevent such wrapped-around relative times | |
5b0830cb | 1019 | * from permanently stopping the whole bdi writeback. |
d2caa3c5 JL |
1020 | */ |
1021 | ret = ret && time_before_eq(inode->dirtied_when, jiffies); | |
1022 | #endif | |
1023 | return ret; | |
1024 | } | |
1025 | ||
0ae45f63 TT |
1026 | #define EXPIRE_DIRTY_ATIME 0x0001 |
1027 | ||
2c136579 | 1028 | /* |
0e2f2b23 | 1029 | * Move expired (dirtied before work->older_than_this) dirty inodes from |
697e6fed | 1030 | * @delaying_queue to @dispatch_queue. |
2c136579 | 1031 | */ |
e84d0a4f | 1032 | static int move_expired_inodes(struct list_head *delaying_queue, |
2c136579 | 1033 | struct list_head *dispatch_queue, |
0ae45f63 | 1034 | int flags, |
ad4e38dd | 1035 | struct wb_writeback_work *work) |
2c136579 | 1036 | { |
0ae45f63 TT |
1037 | unsigned long *older_than_this = NULL; |
1038 | unsigned long expire_time; | |
5c03449d SL |
1039 | LIST_HEAD(tmp); |
1040 | struct list_head *pos, *node; | |
cf137307 | 1041 | struct super_block *sb = NULL; |
5c03449d | 1042 | struct inode *inode; |
cf137307 | 1043 | int do_sb_sort = 0; |
e84d0a4f | 1044 | int moved = 0; |
5c03449d | 1045 | |
0ae45f63 TT |
1046 | if ((flags & EXPIRE_DIRTY_ATIME) == 0) |
1047 | older_than_this = work->older_than_this; | |
a2f48706 TT |
1048 | else if (!work->for_sync) { |
1049 | expire_time = jiffies - (dirtytime_expire_interval * HZ); | |
0ae45f63 TT |
1050 | older_than_this = &expire_time; |
1051 | } | |
2c136579 | 1052 | while (!list_empty(delaying_queue)) { |
7ccf19a8 | 1053 | inode = wb_inode(delaying_queue->prev); |
0ae45f63 TT |
1054 | if (older_than_this && |
1055 | inode_dirtied_after(inode, *older_than_this)) | |
2c136579 | 1056 | break; |
a8855990 JK |
1057 | list_move(&inode->i_wb_list, &tmp); |
1058 | moved++; | |
0ae45f63 TT |
1059 | if (flags & EXPIRE_DIRTY_ATIME) |
1060 | set_bit(__I_DIRTY_TIME_EXPIRED, &inode->i_state); | |
a8855990 JK |
1061 | if (sb_is_blkdev_sb(inode->i_sb)) |
1062 | continue; | |
cf137307 JA |
1063 | if (sb && sb != inode->i_sb) |
1064 | do_sb_sort = 1; | |
1065 | sb = inode->i_sb; | |
5c03449d SL |
1066 | } |
1067 | ||
cf137307 JA |
1068 | /* just one sb in list, splice to dispatch_queue and we're done */ |
1069 | if (!do_sb_sort) { | |
1070 | list_splice(&tmp, dispatch_queue); | |
e84d0a4f | 1071 | goto out; |
cf137307 JA |
1072 | } |
1073 | ||
5c03449d SL |
1074 | /* Move inodes from one superblock together */ |
1075 | while (!list_empty(&tmp)) { | |
7ccf19a8 | 1076 | sb = wb_inode(tmp.prev)->i_sb; |
5c03449d | 1077 | list_for_each_prev_safe(pos, node, &tmp) { |
7ccf19a8 | 1078 | inode = wb_inode(pos); |
5c03449d | 1079 | if (inode->i_sb == sb) |
7ccf19a8 | 1080 | list_move(&inode->i_wb_list, dispatch_queue); |
5c03449d | 1081 | } |
2c136579 | 1082 | } |
e84d0a4f WF |
1083 | out: |
1084 | return moved; | |
2c136579 FW |
1085 | } |
1086 | ||
1087 | /* | |
1088 | * Queue all expired dirty inodes for io, eldest first. | |
4ea879b9 WF |
1089 | * Before |
1090 | * newly dirtied b_dirty b_io b_more_io | |
1091 | * =============> gf edc BA | |
1092 | * After | |
1093 | * newly dirtied b_dirty b_io b_more_io | |
1094 | * =============> g fBAedc | |
1095 | * | | |
1096 | * +--> dequeue for IO | |
2c136579 | 1097 | */ |
ad4e38dd | 1098 | static void queue_io(struct bdi_writeback *wb, struct wb_writeback_work *work) |
66f3b8e2 | 1099 | { |
e84d0a4f | 1100 | int moved; |
0ae45f63 | 1101 | |
f758eeab | 1102 | assert_spin_locked(&wb->list_lock); |
4ea879b9 | 1103 | list_splice_init(&wb->b_more_io, &wb->b_io); |
0ae45f63 TT |
1104 | moved = move_expired_inodes(&wb->b_dirty, &wb->b_io, 0, work); |
1105 | moved += move_expired_inodes(&wb->b_dirty_time, &wb->b_io, | |
1106 | EXPIRE_DIRTY_ATIME, work); | |
d6c10f1f TH |
1107 | if (moved) |
1108 | wb_io_lists_populated(wb); | |
ad4e38dd | 1109 | trace_writeback_queue_io(wb, work, moved); |
66f3b8e2 JA |
1110 | } |
1111 | ||
a9185b41 | 1112 | static int write_inode(struct inode *inode, struct writeback_control *wbc) |
08d8e974 | 1113 | { |
9fb0a7da TH |
1114 | int ret; |
1115 | ||
1116 | if (inode->i_sb->s_op->write_inode && !is_bad_inode(inode)) { | |
1117 | trace_writeback_write_inode_start(inode, wbc); | |
1118 | ret = inode->i_sb->s_op->write_inode(inode, wbc); | |
1119 | trace_writeback_write_inode(inode, wbc); | |
1120 | return ret; | |
1121 | } | |
03ba3782 | 1122 | return 0; |
08d8e974 | 1123 | } |
08d8e974 | 1124 | |
1da177e4 | 1125 | /* |
169ebd90 JK |
1126 | * Wait for writeback on an inode to complete. Called with i_lock held. |
1127 | * Caller must make sure inode cannot go away when we drop i_lock. | |
01c03194 | 1128 | */ |
169ebd90 JK |
1129 | static void __inode_wait_for_writeback(struct inode *inode) |
1130 | __releases(inode->i_lock) | |
1131 | __acquires(inode->i_lock) | |
01c03194 CH |
1132 | { |
1133 | DEFINE_WAIT_BIT(wq, &inode->i_state, __I_SYNC); | |
1134 | wait_queue_head_t *wqh; | |
1135 | ||
1136 | wqh = bit_waitqueue(&inode->i_state, __I_SYNC); | |
250df6ed DC |
1137 | while (inode->i_state & I_SYNC) { |
1138 | spin_unlock(&inode->i_lock); | |
74316201 N |
1139 | __wait_on_bit(wqh, &wq, bit_wait, |
1140 | TASK_UNINTERRUPTIBLE); | |
250df6ed | 1141 | spin_lock(&inode->i_lock); |
58a9d3d8 | 1142 | } |
01c03194 CH |
1143 | } |
1144 | ||
169ebd90 JK |
1145 | /* |
1146 | * Wait for writeback on an inode to complete. Caller must have inode pinned. | |
1147 | */ | |
1148 | void inode_wait_for_writeback(struct inode *inode) | |
1149 | { | |
1150 | spin_lock(&inode->i_lock); | |
1151 | __inode_wait_for_writeback(inode); | |
1152 | spin_unlock(&inode->i_lock); | |
1153 | } | |
1154 | ||
1155 | /* | |
1156 | * Sleep until I_SYNC is cleared. This function must be called with i_lock | |
1157 | * held and drops it. It is aimed for callers not holding any inode reference | |
1158 | * so once i_lock is dropped, inode can go away. | |
1159 | */ | |
1160 | static void inode_sleep_on_writeback(struct inode *inode) | |
1161 | __releases(inode->i_lock) | |
1162 | { | |
1163 | DEFINE_WAIT(wait); | |
1164 | wait_queue_head_t *wqh = bit_waitqueue(&inode->i_state, __I_SYNC); | |
1165 | int sleep; | |
1166 | ||
1167 | prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); | |
1168 | sleep = inode->i_state & I_SYNC; | |
1169 | spin_unlock(&inode->i_lock); | |
1170 | if (sleep) | |
1171 | schedule(); | |
1172 | finish_wait(wqh, &wait); | |
1173 | } | |
1174 | ||
ccb26b5a JK |
1175 | /* |
1176 | * Find proper writeback list for the inode depending on its current state and | |
1177 | * possibly also change of its state while we were doing writeback. Here we | |
1178 | * handle things such as livelock prevention or fairness of writeback among | |
1179 | * inodes. This function can be called only by flusher thread - noone else | |
1180 | * processes all inodes in writeback lists and requeueing inodes behind flusher | |
1181 | * thread's back can have unexpected consequences. | |
1182 | */ | |
1183 | static void requeue_inode(struct inode *inode, struct bdi_writeback *wb, | |
1184 | struct writeback_control *wbc) | |
1185 | { | |
1186 | if (inode->i_state & I_FREEING) | |
1187 | return; | |
1188 | ||
1189 | /* | |
1190 | * Sync livelock prevention. Each inode is tagged and synced in one | |
1191 | * shot. If still dirty, it will be redirty_tail()'ed below. Update | |
1192 | * the dirty time to prevent enqueue and sync it again. | |
1193 | */ | |
1194 | if ((inode->i_state & I_DIRTY) && | |
1195 | (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)) | |
1196 | inode->dirtied_when = jiffies; | |
1197 | ||
4f8ad655 JK |
1198 | if (wbc->pages_skipped) { |
1199 | /* | |
1200 | * writeback is not making progress due to locked | |
1201 | * buffers. Skip this inode for now. | |
1202 | */ | |
1203 | redirty_tail(inode, wb); | |
1204 | return; | |
1205 | } | |
1206 | ||
ccb26b5a JK |
1207 | if (mapping_tagged(inode->i_mapping, PAGECACHE_TAG_DIRTY)) { |
1208 | /* | |
1209 | * We didn't write back all the pages. nfs_writepages() | |
1210 | * sometimes bales out without doing anything. | |
1211 | */ | |
1212 | if (wbc->nr_to_write <= 0) { | |
1213 | /* Slice used up. Queue for next turn. */ | |
1214 | requeue_io(inode, wb); | |
1215 | } else { | |
1216 | /* | |
1217 | * Writeback blocked by something other than | |
1218 | * congestion. Delay the inode for some time to | |
1219 | * avoid spinning on the CPU (100% iowait) | |
1220 | * retrying writeback of the dirty page/inode | |
1221 | * that cannot be performed immediately. | |
1222 | */ | |
1223 | redirty_tail(inode, wb); | |
1224 | } | |
1225 | } else if (inode->i_state & I_DIRTY) { | |
1226 | /* | |
1227 | * Filesystems can dirty the inode during writeback operations, | |
1228 | * such as delayed allocation during submission or metadata | |
1229 | * updates after data IO completion. | |
1230 | */ | |
1231 | redirty_tail(inode, wb); | |
0ae45f63 | 1232 | } else if (inode->i_state & I_DIRTY_TIME) { |
a2f48706 | 1233 | inode->dirtied_when = jiffies; |
d6c10f1f | 1234 | inode_wb_list_move_locked(inode, wb, &wb->b_dirty_time); |
ccb26b5a JK |
1235 | } else { |
1236 | /* The inode is clean. Remove from writeback lists. */ | |
d6c10f1f | 1237 | inode_wb_list_del_locked(inode, wb); |
ccb26b5a JK |
1238 | } |
1239 | } | |
1240 | ||
01c03194 | 1241 | /* |
4f8ad655 JK |
1242 | * Write out an inode and its dirty pages. Do not update the writeback list |
1243 | * linkage. That is left to the caller. The caller is also responsible for | |
1244 | * setting I_SYNC flag and calling inode_sync_complete() to clear it. | |
1da177e4 LT |
1245 | */ |
1246 | static int | |
cd8ed2a4 | 1247 | __writeback_single_inode(struct inode *inode, struct writeback_control *wbc) |
1da177e4 | 1248 | { |
1da177e4 | 1249 | struct address_space *mapping = inode->i_mapping; |
251d6a47 | 1250 | long nr_to_write = wbc->nr_to_write; |
01c03194 | 1251 | unsigned dirty; |
1da177e4 LT |
1252 | int ret; |
1253 | ||
4f8ad655 | 1254 | WARN_ON(!(inode->i_state & I_SYNC)); |
1da177e4 | 1255 | |
9fb0a7da TH |
1256 | trace_writeback_single_inode_start(inode, wbc, nr_to_write); |
1257 | ||
1da177e4 LT |
1258 | ret = do_writepages(mapping, wbc); |
1259 | ||
26821ed4 CH |
1260 | /* |
1261 | * Make sure to wait on the data before writing out the metadata. | |
1262 | * This is important for filesystems that modify metadata on data | |
7747bd4b DC |
1263 | * I/O completion. We don't do it for sync(2) writeback because it has a |
1264 | * separate, external IO completion path and ->sync_fs for guaranteeing | |
1265 | * inode metadata is written back correctly. | |
26821ed4 | 1266 | */ |
7747bd4b | 1267 | if (wbc->sync_mode == WB_SYNC_ALL && !wbc->for_sync) { |
26821ed4 | 1268 | int err = filemap_fdatawait(mapping); |
1da177e4 LT |
1269 | if (ret == 0) |
1270 | ret = err; | |
1271 | } | |
1272 | ||
5547e8aa DM |
1273 | /* |
1274 | * Some filesystems may redirty the inode during the writeback | |
1275 | * due to delalloc, clear dirty metadata flags right before | |
1276 | * write_inode() | |
1277 | */ | |
250df6ed | 1278 | spin_lock(&inode->i_lock); |
9c6ac78e | 1279 | |
5547e8aa | 1280 | dirty = inode->i_state & I_DIRTY; |
a2f48706 TT |
1281 | if (inode->i_state & I_DIRTY_TIME) { |
1282 | if ((dirty & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) || | |
1283 | unlikely(inode->i_state & I_DIRTY_TIME_EXPIRED) || | |
1284 | unlikely(time_after(jiffies, | |
1285 | (inode->dirtied_time_when + | |
1286 | dirtytime_expire_interval * HZ)))) { | |
1287 | dirty |= I_DIRTY_TIME | I_DIRTY_TIME_EXPIRED; | |
1288 | trace_writeback_lazytime(inode); | |
1289 | } | |
1290 | } else | |
1291 | inode->i_state &= ~I_DIRTY_TIME_EXPIRED; | |
0ae45f63 | 1292 | inode->i_state &= ~dirty; |
9c6ac78e TH |
1293 | |
1294 | /* | |
1295 | * Paired with smp_mb() in __mark_inode_dirty(). This allows | |
1296 | * __mark_inode_dirty() to test i_state without grabbing i_lock - | |
1297 | * either they see the I_DIRTY bits cleared or we see the dirtied | |
1298 | * inode. | |
1299 | * | |
1300 | * I_DIRTY_PAGES is always cleared together above even if @mapping | |
1301 | * still has dirty pages. The flag is reinstated after smp_mb() if | |
1302 | * necessary. This guarantees that either __mark_inode_dirty() | |
1303 | * sees clear I_DIRTY_PAGES or we see PAGECACHE_TAG_DIRTY. | |
1304 | */ | |
1305 | smp_mb(); | |
1306 | ||
1307 | if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) | |
1308 | inode->i_state |= I_DIRTY_PAGES; | |
1309 | ||
250df6ed | 1310 | spin_unlock(&inode->i_lock); |
9c6ac78e | 1311 | |
0ae45f63 TT |
1312 | if (dirty & I_DIRTY_TIME) |
1313 | mark_inode_dirty_sync(inode); | |
26821ed4 | 1314 | /* Don't write the inode if only I_DIRTY_PAGES was set */ |
0ae45f63 | 1315 | if (dirty & ~I_DIRTY_PAGES) { |
a9185b41 | 1316 | int err = write_inode(inode, wbc); |
1da177e4 LT |
1317 | if (ret == 0) |
1318 | ret = err; | |
1319 | } | |
4f8ad655 JK |
1320 | trace_writeback_single_inode(inode, wbc, nr_to_write); |
1321 | return ret; | |
1322 | } | |
1323 | ||
1324 | /* | |
1325 | * Write out an inode's dirty pages. Either the caller has an active reference | |
1326 | * on the inode or the inode has I_WILL_FREE set. | |
1327 | * | |
1328 | * This function is designed to be called for writing back one inode which | |
1329 | * we go e.g. from filesystem. Flusher thread uses __writeback_single_inode() | |
1330 | * and does more profound writeback list handling in writeback_sb_inodes(). | |
1331 | */ | |
1332 | static int | |
1333 | writeback_single_inode(struct inode *inode, struct bdi_writeback *wb, | |
1334 | struct writeback_control *wbc) | |
1335 | { | |
1336 | int ret = 0; | |
1337 | ||
1338 | spin_lock(&inode->i_lock); | |
1339 | if (!atomic_read(&inode->i_count)) | |
1340 | WARN_ON(!(inode->i_state & (I_WILL_FREE|I_FREEING))); | |
1341 | else | |
1342 | WARN_ON(inode->i_state & I_WILL_FREE); | |
1343 | ||
1344 | if (inode->i_state & I_SYNC) { | |
1345 | if (wbc->sync_mode != WB_SYNC_ALL) | |
1346 | goto out; | |
1347 | /* | |
169ebd90 JK |
1348 | * It's a data-integrity sync. We must wait. Since callers hold |
1349 | * inode reference or inode has I_WILL_FREE set, it cannot go | |
1350 | * away under us. | |
4f8ad655 | 1351 | */ |
169ebd90 | 1352 | __inode_wait_for_writeback(inode); |
4f8ad655 JK |
1353 | } |
1354 | WARN_ON(inode->i_state & I_SYNC); | |
1355 | /* | |
f9b0e058 JK |
1356 | * Skip inode if it is clean and we have no outstanding writeback in |
1357 | * WB_SYNC_ALL mode. We don't want to mess with writeback lists in this | |
1358 | * function since flusher thread may be doing for example sync in | |
1359 | * parallel and if we move the inode, it could get skipped. So here we | |
1360 | * make sure inode is on some writeback list and leave it there unless | |
1361 | * we have completely cleaned the inode. | |
4f8ad655 | 1362 | */ |
0ae45f63 | 1363 | if (!(inode->i_state & I_DIRTY_ALL) && |
f9b0e058 JK |
1364 | (wbc->sync_mode != WB_SYNC_ALL || |
1365 | !mapping_tagged(inode->i_mapping, PAGECACHE_TAG_WRITEBACK))) | |
4f8ad655 JK |
1366 | goto out; |
1367 | inode->i_state |= I_SYNC; | |
b16b1deb | 1368 | wbc_attach_and_unlock_inode(wbc, inode); |
4f8ad655 | 1369 | |
cd8ed2a4 | 1370 | ret = __writeback_single_inode(inode, wbc); |
1da177e4 | 1371 | |
b16b1deb | 1372 | wbc_detach_inode(wbc); |
f758eeab | 1373 | spin_lock(&wb->list_lock); |
250df6ed | 1374 | spin_lock(&inode->i_lock); |
4f8ad655 JK |
1375 | /* |
1376 | * If inode is clean, remove it from writeback lists. Otherwise don't | |
1377 | * touch it. See comment above for explanation. | |
1378 | */ | |
0ae45f63 | 1379 | if (!(inode->i_state & I_DIRTY_ALL)) |
d6c10f1f | 1380 | inode_wb_list_del_locked(inode, wb); |
4f8ad655 | 1381 | spin_unlock(&wb->list_lock); |
1c0eeaf5 | 1382 | inode_sync_complete(inode); |
4f8ad655 JK |
1383 | out: |
1384 | spin_unlock(&inode->i_lock); | |
1da177e4 LT |
1385 | return ret; |
1386 | } | |
1387 | ||
a88a341a | 1388 | static long writeback_chunk_size(struct bdi_writeback *wb, |
1a12d8bd | 1389 | struct wb_writeback_work *work) |
d46db3d5 WF |
1390 | { |
1391 | long pages; | |
1392 | ||
1393 | /* | |
1394 | * WB_SYNC_ALL mode does livelock avoidance by syncing dirty | |
1395 | * inodes/pages in one big loop. Setting wbc.nr_to_write=LONG_MAX | |
1396 | * here avoids calling into writeback_inodes_wb() more than once. | |
1397 | * | |
1398 | * The intended call sequence for WB_SYNC_ALL writeback is: | |
1399 | * | |
1400 | * wb_writeback() | |
1401 | * writeback_sb_inodes() <== called only once | |
1402 | * write_cache_pages() <== called once for each inode | |
1403 | * (quickly) tag currently dirty pages | |
1404 | * (maybe slowly) sync all tagged pages | |
1405 | */ | |
1406 | if (work->sync_mode == WB_SYNC_ALL || work->tagged_writepages) | |
1407 | pages = LONG_MAX; | |
1a12d8bd | 1408 | else { |
a88a341a | 1409 | pages = min(wb->avg_write_bandwidth / 2, |
dcc25ae7 | 1410 | global_wb_domain.dirty_limit / DIRTY_SCOPE); |
1a12d8bd WF |
1411 | pages = min(pages, work->nr_pages); |
1412 | pages = round_down(pages + MIN_WRITEBACK_PAGES, | |
1413 | MIN_WRITEBACK_PAGES); | |
1414 | } | |
d46db3d5 WF |
1415 | |
1416 | return pages; | |
1417 | } | |
1418 | ||
f11c9c5c ES |
1419 | /* |
1420 | * Write a portion of b_io inodes which belong to @sb. | |
edadfb10 | 1421 | * |
d46db3d5 | 1422 | * Return the number of pages and/or inodes written. |
f11c9c5c | 1423 | */ |
d46db3d5 WF |
1424 | static long writeback_sb_inodes(struct super_block *sb, |
1425 | struct bdi_writeback *wb, | |
1426 | struct wb_writeback_work *work) | |
1da177e4 | 1427 | { |
d46db3d5 WF |
1428 | struct writeback_control wbc = { |
1429 | .sync_mode = work->sync_mode, | |
1430 | .tagged_writepages = work->tagged_writepages, | |
1431 | .for_kupdate = work->for_kupdate, | |
1432 | .for_background = work->for_background, | |
7747bd4b | 1433 | .for_sync = work->for_sync, |
d46db3d5 WF |
1434 | .range_cyclic = work->range_cyclic, |
1435 | .range_start = 0, | |
1436 | .range_end = LLONG_MAX, | |
1437 | }; | |
1438 | unsigned long start_time = jiffies; | |
1439 | long write_chunk; | |
1440 | long wrote = 0; /* count both pages and inodes */ | |
1441 | ||
03ba3782 | 1442 | while (!list_empty(&wb->b_io)) { |
7ccf19a8 | 1443 | struct inode *inode = wb_inode(wb->b_io.prev); |
edadfb10 CH |
1444 | |
1445 | if (inode->i_sb != sb) { | |
d46db3d5 | 1446 | if (work->sb) { |
edadfb10 CH |
1447 | /* |
1448 | * We only want to write back data for this | |
1449 | * superblock, move all inodes not belonging | |
1450 | * to it back onto the dirty list. | |
1451 | */ | |
f758eeab | 1452 | redirty_tail(inode, wb); |
edadfb10 CH |
1453 | continue; |
1454 | } | |
1455 | ||
1456 | /* | |
1457 | * The inode belongs to a different superblock. | |
1458 | * Bounce back to the caller to unpin this and | |
1459 | * pin the next superblock. | |
1460 | */ | |
d46db3d5 | 1461 | break; |
edadfb10 CH |
1462 | } |
1463 | ||
9843b76a | 1464 | /* |
331cbdee WL |
1465 | * Don't bother with new inodes or inodes being freed, first |
1466 | * kind does not need periodic writeout yet, and for the latter | |
9843b76a CH |
1467 | * kind writeout is handled by the freer. |
1468 | */ | |
250df6ed | 1469 | spin_lock(&inode->i_lock); |
9843b76a | 1470 | if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) { |
250df6ed | 1471 | spin_unlock(&inode->i_lock); |
fcc5c222 | 1472 | redirty_tail(inode, wb); |
7ef0d737 NP |
1473 | continue; |
1474 | } | |
cc1676d9 JK |
1475 | if ((inode->i_state & I_SYNC) && wbc.sync_mode != WB_SYNC_ALL) { |
1476 | /* | |
1477 | * If this inode is locked for writeback and we are not | |
1478 | * doing writeback-for-data-integrity, move it to | |
1479 | * b_more_io so that writeback can proceed with the | |
1480 | * other inodes on s_io. | |
1481 | * | |
1482 | * We'll have another go at writing back this inode | |
1483 | * when we completed a full scan of b_io. | |
1484 | */ | |
1485 | spin_unlock(&inode->i_lock); | |
1486 | requeue_io(inode, wb); | |
1487 | trace_writeback_sb_inodes_requeue(inode); | |
1488 | continue; | |
1489 | } | |
f0d07b7f JK |
1490 | spin_unlock(&wb->list_lock); |
1491 | ||
4f8ad655 JK |
1492 | /* |
1493 | * We already requeued the inode if it had I_SYNC set and we | |
1494 | * are doing WB_SYNC_NONE writeback. So this catches only the | |
1495 | * WB_SYNC_ALL case. | |
1496 | */ | |
169ebd90 JK |
1497 | if (inode->i_state & I_SYNC) { |
1498 | /* Wait for I_SYNC. This function drops i_lock... */ | |
1499 | inode_sleep_on_writeback(inode); | |
1500 | /* Inode may be gone, start again */ | |
ead188f9 | 1501 | spin_lock(&wb->list_lock); |
169ebd90 JK |
1502 | continue; |
1503 | } | |
4f8ad655 | 1504 | inode->i_state |= I_SYNC; |
b16b1deb | 1505 | wbc_attach_and_unlock_inode(&wbc, inode); |
169ebd90 | 1506 | |
a88a341a | 1507 | write_chunk = writeback_chunk_size(wb, work); |
d46db3d5 WF |
1508 | wbc.nr_to_write = write_chunk; |
1509 | wbc.pages_skipped = 0; | |
250df6ed | 1510 | |
169ebd90 JK |
1511 | /* |
1512 | * We use I_SYNC to pin the inode in memory. While it is set | |
1513 | * evict_inode() will wait so the inode cannot be freed. | |
1514 | */ | |
cd8ed2a4 | 1515 | __writeback_single_inode(inode, &wbc); |
250df6ed | 1516 | |
b16b1deb | 1517 | wbc_detach_inode(&wbc); |
d46db3d5 WF |
1518 | work->nr_pages -= write_chunk - wbc.nr_to_write; |
1519 | wrote += write_chunk - wbc.nr_to_write; | |
4f8ad655 JK |
1520 | spin_lock(&wb->list_lock); |
1521 | spin_lock(&inode->i_lock); | |
0ae45f63 | 1522 | if (!(inode->i_state & I_DIRTY_ALL)) |
d46db3d5 | 1523 | wrote++; |
4f8ad655 JK |
1524 | requeue_inode(inode, wb, &wbc); |
1525 | inode_sync_complete(inode); | |
0f1b1fd8 | 1526 | spin_unlock(&inode->i_lock); |
169ebd90 | 1527 | cond_resched_lock(&wb->list_lock); |
d46db3d5 WF |
1528 | /* |
1529 | * bail out to wb_writeback() often enough to check | |
1530 | * background threshold and other termination conditions. | |
1531 | */ | |
1532 | if (wrote) { | |
1533 | if (time_is_before_jiffies(start_time + HZ / 10UL)) | |
1534 | break; | |
1535 | if (work->nr_pages <= 0) | |
1536 | break; | |
8bc3be27 | 1537 | } |
1da177e4 | 1538 | } |
d46db3d5 | 1539 | return wrote; |
f11c9c5c ES |
1540 | } |
1541 | ||
d46db3d5 WF |
1542 | static long __writeback_inodes_wb(struct bdi_writeback *wb, |
1543 | struct wb_writeback_work *work) | |
f11c9c5c | 1544 | { |
d46db3d5 WF |
1545 | unsigned long start_time = jiffies; |
1546 | long wrote = 0; | |
38f21977 | 1547 | |
f11c9c5c | 1548 | while (!list_empty(&wb->b_io)) { |
7ccf19a8 | 1549 | struct inode *inode = wb_inode(wb->b_io.prev); |
f11c9c5c | 1550 | struct super_block *sb = inode->i_sb; |
9ecc2738 | 1551 | |
eb6ef3df | 1552 | if (!trylock_super(sb)) { |
0e995816 | 1553 | /* |
eb6ef3df | 1554 | * trylock_super() may fail consistently due to |
0e995816 WF |
1555 | * s_umount being grabbed by someone else. Don't use |
1556 | * requeue_io() to avoid busy retrying the inode/sb. | |
1557 | */ | |
1558 | redirty_tail(inode, wb); | |
edadfb10 | 1559 | continue; |
f11c9c5c | 1560 | } |
d46db3d5 | 1561 | wrote += writeback_sb_inodes(sb, wb, work); |
eb6ef3df | 1562 | up_read(&sb->s_umount); |
f11c9c5c | 1563 | |
d46db3d5 WF |
1564 | /* refer to the same tests at the end of writeback_sb_inodes */ |
1565 | if (wrote) { | |
1566 | if (time_is_before_jiffies(start_time + HZ / 10UL)) | |
1567 | break; | |
1568 | if (work->nr_pages <= 0) | |
1569 | break; | |
1570 | } | |
f11c9c5c | 1571 | } |
66f3b8e2 | 1572 | /* Leave any unwritten inodes on b_io */ |
d46db3d5 | 1573 | return wrote; |
66f3b8e2 JA |
1574 | } |
1575 | ||
7d9f073b | 1576 | static long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages, |
0e175a18 | 1577 | enum wb_reason reason) |
edadfb10 | 1578 | { |
d46db3d5 WF |
1579 | struct wb_writeback_work work = { |
1580 | .nr_pages = nr_pages, | |
1581 | .sync_mode = WB_SYNC_NONE, | |
1582 | .range_cyclic = 1, | |
0e175a18 | 1583 | .reason = reason, |
d46db3d5 | 1584 | }; |
edadfb10 | 1585 | |
f758eeab | 1586 | spin_lock(&wb->list_lock); |
424b351f | 1587 | if (list_empty(&wb->b_io)) |
ad4e38dd | 1588 | queue_io(wb, &work); |
d46db3d5 | 1589 | __writeback_inodes_wb(wb, &work); |
f758eeab | 1590 | spin_unlock(&wb->list_lock); |
edadfb10 | 1591 | |
d46db3d5 WF |
1592 | return nr_pages - work.nr_pages; |
1593 | } | |
03ba3782 | 1594 | |
03ba3782 JA |
1595 | /* |
1596 | * Explicit flushing or periodic writeback of "old" data. | |
66f3b8e2 | 1597 | * |
03ba3782 JA |
1598 | * Define "old": the first time one of an inode's pages is dirtied, we mark the |
1599 | * dirtying-time in the inode's address_space. So this periodic writeback code | |
1600 | * just walks the superblock inode list, writing back any inodes which are | |
1601 | * older than a specific point in time. | |
66f3b8e2 | 1602 | * |
03ba3782 JA |
1603 | * Try to run once per dirty_writeback_interval. But if a writeback event |
1604 | * takes longer than a dirty_writeback_interval interval, then leave a | |
1605 | * one-second gap. | |
66f3b8e2 | 1606 | * |
03ba3782 JA |
1607 | * older_than_this takes precedence over nr_to_write. So we'll only write back |
1608 | * all dirty pages if they are all attached to "old" mappings. | |
66f3b8e2 | 1609 | */ |
c4a77a6c | 1610 | static long wb_writeback(struct bdi_writeback *wb, |
83ba7b07 | 1611 | struct wb_writeback_work *work) |
66f3b8e2 | 1612 | { |
e98be2d5 | 1613 | unsigned long wb_start = jiffies; |
d46db3d5 | 1614 | long nr_pages = work->nr_pages; |
0dc83bd3 | 1615 | unsigned long oldest_jif; |
a5989bdc | 1616 | struct inode *inode; |
d46db3d5 | 1617 | long progress; |
66f3b8e2 | 1618 | |
0dc83bd3 JK |
1619 | oldest_jif = jiffies; |
1620 | work->older_than_this = &oldest_jif; | |
38f21977 | 1621 | |
e8dfc305 | 1622 | spin_lock(&wb->list_lock); |
03ba3782 JA |
1623 | for (;;) { |
1624 | /* | |
d3ddec76 | 1625 | * Stop writeback when nr_pages has been consumed |
03ba3782 | 1626 | */ |
83ba7b07 | 1627 | if (work->nr_pages <= 0) |
03ba3782 | 1628 | break; |
66f3b8e2 | 1629 | |
aa373cf5 JK |
1630 | /* |
1631 | * Background writeout and kupdate-style writeback may | |
1632 | * run forever. Stop them if there is other work to do | |
1633 | * so that e.g. sync can proceed. They'll be restarted | |
1634 | * after the other works are all done. | |
1635 | */ | |
1636 | if ((work->for_background || work->for_kupdate) && | |
f0054bb1 | 1637 | !list_empty(&wb->work_list)) |
aa373cf5 JK |
1638 | break; |
1639 | ||
38f21977 | 1640 | /* |
d3ddec76 WF |
1641 | * For background writeout, stop when we are below the |
1642 | * background dirty threshold | |
38f21977 | 1643 | */ |
aa661bbe | 1644 | if (work->for_background && !wb_over_bg_thresh(wb)) |
03ba3782 | 1645 | break; |
38f21977 | 1646 | |
1bc36b64 JK |
1647 | /* |
1648 | * Kupdate and background works are special and we want to | |
1649 | * include all inodes that need writing. Livelock avoidance is | |
1650 | * handled by these works yielding to any other work so we are | |
1651 | * safe. | |
1652 | */ | |
ba9aa839 | 1653 | if (work->for_kupdate) { |
0dc83bd3 | 1654 | oldest_jif = jiffies - |
ba9aa839 | 1655 | msecs_to_jiffies(dirty_expire_interval * 10); |
1bc36b64 | 1656 | } else if (work->for_background) |
0dc83bd3 | 1657 | oldest_jif = jiffies; |
028c2dd1 | 1658 | |
d46db3d5 | 1659 | trace_writeback_start(wb->bdi, work); |
e8dfc305 | 1660 | if (list_empty(&wb->b_io)) |
ad4e38dd | 1661 | queue_io(wb, work); |
83ba7b07 | 1662 | if (work->sb) |
d46db3d5 | 1663 | progress = writeback_sb_inodes(work->sb, wb, work); |
edadfb10 | 1664 | else |
d46db3d5 WF |
1665 | progress = __writeback_inodes_wb(wb, work); |
1666 | trace_writeback_written(wb->bdi, work); | |
028c2dd1 | 1667 | |
e98be2d5 | 1668 | wb_update_bandwidth(wb, wb_start); |
03ba3782 JA |
1669 | |
1670 | /* | |
e6fb6da2 WF |
1671 | * Did we write something? Try for more |
1672 | * | |
1673 | * Dirty inodes are moved to b_io for writeback in batches. | |
1674 | * The completion of the current batch does not necessarily | |
1675 | * mean the overall work is done. So we keep looping as long | |
1676 | * as made some progress on cleaning pages or inodes. | |
03ba3782 | 1677 | */ |
d46db3d5 | 1678 | if (progress) |
71fd05a8 JA |
1679 | continue; |
1680 | /* | |
e6fb6da2 | 1681 | * No more inodes for IO, bail |
71fd05a8 | 1682 | */ |
b7a2441f | 1683 | if (list_empty(&wb->b_more_io)) |
03ba3782 | 1684 | break; |
71fd05a8 JA |
1685 | /* |
1686 | * Nothing written. Wait for some inode to | |
1687 | * become available for writeback. Otherwise | |
1688 | * we'll just busyloop. | |
1689 | */ | |
71fd05a8 | 1690 | if (!list_empty(&wb->b_more_io)) { |
d46db3d5 | 1691 | trace_writeback_wait(wb->bdi, work); |
7ccf19a8 | 1692 | inode = wb_inode(wb->b_more_io.prev); |
250df6ed | 1693 | spin_lock(&inode->i_lock); |
f0d07b7f | 1694 | spin_unlock(&wb->list_lock); |
169ebd90 JK |
1695 | /* This function drops i_lock... */ |
1696 | inode_sleep_on_writeback(inode); | |
f0d07b7f | 1697 | spin_lock(&wb->list_lock); |
03ba3782 JA |
1698 | } |
1699 | } | |
e8dfc305 | 1700 | spin_unlock(&wb->list_lock); |
03ba3782 | 1701 | |
d46db3d5 | 1702 | return nr_pages - work->nr_pages; |
03ba3782 JA |
1703 | } |
1704 | ||
1705 | /* | |
83ba7b07 | 1706 | * Return the next wb_writeback_work struct that hasn't been processed yet. |
03ba3782 | 1707 | */ |
f0054bb1 | 1708 | static struct wb_writeback_work *get_next_work_item(struct bdi_writeback *wb) |
03ba3782 | 1709 | { |
83ba7b07 | 1710 | struct wb_writeback_work *work = NULL; |
03ba3782 | 1711 | |
f0054bb1 TH |
1712 | spin_lock_bh(&wb->work_lock); |
1713 | if (!list_empty(&wb->work_list)) { | |
1714 | work = list_entry(wb->work_list.next, | |
83ba7b07 CH |
1715 | struct wb_writeback_work, list); |
1716 | list_del_init(&work->list); | |
03ba3782 | 1717 | } |
f0054bb1 | 1718 | spin_unlock_bh(&wb->work_lock); |
83ba7b07 | 1719 | return work; |
03ba3782 JA |
1720 | } |
1721 | ||
cdf01dd5 LT |
1722 | /* |
1723 | * Add in the number of potentially dirty inodes, because each inode | |
1724 | * write can dirty pagecache in the underlying blockdev. | |
1725 | */ | |
1726 | static unsigned long get_nr_dirty_pages(void) | |
1727 | { | |
1728 | return global_page_state(NR_FILE_DIRTY) + | |
1729 | global_page_state(NR_UNSTABLE_NFS) + | |
1730 | get_nr_dirty_inodes(); | |
1731 | } | |
1732 | ||
6585027a JK |
1733 | static long wb_check_background_flush(struct bdi_writeback *wb) |
1734 | { | |
aa661bbe | 1735 | if (wb_over_bg_thresh(wb)) { |
6585027a JK |
1736 | |
1737 | struct wb_writeback_work work = { | |
1738 | .nr_pages = LONG_MAX, | |
1739 | .sync_mode = WB_SYNC_NONE, | |
1740 | .for_background = 1, | |
1741 | .range_cyclic = 1, | |
0e175a18 | 1742 | .reason = WB_REASON_BACKGROUND, |
6585027a JK |
1743 | }; |
1744 | ||
1745 | return wb_writeback(wb, &work); | |
1746 | } | |
1747 | ||
1748 | return 0; | |
1749 | } | |
1750 | ||
03ba3782 JA |
1751 | static long wb_check_old_data_flush(struct bdi_writeback *wb) |
1752 | { | |
1753 | unsigned long expired; | |
1754 | long nr_pages; | |
1755 | ||
69b62d01 JA |
1756 | /* |
1757 | * When set to zero, disable periodic writeback | |
1758 | */ | |
1759 | if (!dirty_writeback_interval) | |
1760 | return 0; | |
1761 | ||
03ba3782 JA |
1762 | expired = wb->last_old_flush + |
1763 | msecs_to_jiffies(dirty_writeback_interval * 10); | |
1764 | if (time_before(jiffies, expired)) | |
1765 | return 0; | |
1766 | ||
1767 | wb->last_old_flush = jiffies; | |
cdf01dd5 | 1768 | nr_pages = get_nr_dirty_pages(); |
03ba3782 | 1769 | |
c4a77a6c | 1770 | if (nr_pages) { |
83ba7b07 | 1771 | struct wb_writeback_work work = { |
c4a77a6c JA |
1772 | .nr_pages = nr_pages, |
1773 | .sync_mode = WB_SYNC_NONE, | |
1774 | .for_kupdate = 1, | |
1775 | .range_cyclic = 1, | |
0e175a18 | 1776 | .reason = WB_REASON_PERIODIC, |
c4a77a6c JA |
1777 | }; |
1778 | ||
83ba7b07 | 1779 | return wb_writeback(wb, &work); |
c4a77a6c | 1780 | } |
03ba3782 JA |
1781 | |
1782 | return 0; | |
1783 | } | |
1784 | ||
1785 | /* | |
1786 | * Retrieve work items and do the writeback they describe | |
1787 | */ | |
25d130ba | 1788 | static long wb_do_writeback(struct bdi_writeback *wb) |
03ba3782 | 1789 | { |
83ba7b07 | 1790 | struct wb_writeback_work *work; |
c4a77a6c | 1791 | long wrote = 0; |
03ba3782 | 1792 | |
4452226e | 1793 | set_bit(WB_writeback_running, &wb->state); |
f0054bb1 | 1794 | while ((work = get_next_work_item(wb)) != NULL) { |
cc395d7f | 1795 | struct wb_completion *done = work->done; |
98754bf7 | 1796 | bool need_wake_up = false; |
03ba3782 | 1797 | |
f0054bb1 | 1798 | trace_writeback_exec(wb->bdi, work); |
455b2864 | 1799 | |
83ba7b07 | 1800 | wrote += wb_writeback(wb, work); |
03ba3782 | 1801 | |
98754bf7 TH |
1802 | if (work->single_wait) { |
1803 | WARN_ON_ONCE(work->auto_free); | |
1804 | /* paired w/ rmb in wb_wait_for_single_work() */ | |
1805 | smp_wmb(); | |
1806 | work->single_done = 1; | |
1807 | need_wake_up = true; | |
1808 | } else if (work->auto_free) { | |
83ba7b07 | 1809 | kfree(work); |
98754bf7 TH |
1810 | } |
1811 | ||
cc395d7f | 1812 | if (done && atomic_dec_and_test(&done->cnt)) |
98754bf7 TH |
1813 | need_wake_up = true; |
1814 | ||
1815 | if (need_wake_up) | |
cc395d7f | 1816 | wake_up_all(&wb->bdi->wb_waitq); |
03ba3782 JA |
1817 | } |
1818 | ||
1819 | /* | |
1820 | * Check for periodic writeback, kupdated() style | |
1821 | */ | |
1822 | wrote += wb_check_old_data_flush(wb); | |
6585027a | 1823 | wrote += wb_check_background_flush(wb); |
4452226e | 1824 | clear_bit(WB_writeback_running, &wb->state); |
03ba3782 JA |
1825 | |
1826 | return wrote; | |
1827 | } | |
1828 | ||
1829 | /* | |
1830 | * Handle writeback of dirty data for the device backed by this bdi. Also | |
839a8e86 | 1831 | * reschedules periodically and does kupdated style flushing. |
03ba3782 | 1832 | */ |
f0054bb1 | 1833 | void wb_workfn(struct work_struct *work) |
03ba3782 | 1834 | { |
839a8e86 TH |
1835 | struct bdi_writeback *wb = container_of(to_delayed_work(work), |
1836 | struct bdi_writeback, dwork); | |
03ba3782 JA |
1837 | long pages_written; |
1838 | ||
f0054bb1 | 1839 | set_worker_desc("flush-%s", dev_name(wb->bdi->dev)); |
766f9164 | 1840 | current->flags |= PF_SWAPWRITE; |
455b2864 | 1841 | |
839a8e86 | 1842 | if (likely(!current_is_workqueue_rescuer() || |
4452226e | 1843 | !test_bit(WB_registered, &wb->state))) { |
6467716a | 1844 | /* |
f0054bb1 | 1845 | * The normal path. Keep writing back @wb until its |
839a8e86 | 1846 | * work_list is empty. Note that this path is also taken |
f0054bb1 | 1847 | * if @wb is shutting down even when we're running off the |
839a8e86 | 1848 | * rescuer as work_list needs to be drained. |
6467716a | 1849 | */ |
839a8e86 | 1850 | do { |
25d130ba | 1851 | pages_written = wb_do_writeback(wb); |
839a8e86 | 1852 | trace_writeback_pages_written(pages_written); |
f0054bb1 | 1853 | } while (!list_empty(&wb->work_list)); |
839a8e86 TH |
1854 | } else { |
1855 | /* | |
1856 | * bdi_wq can't get enough workers and we're running off | |
1857 | * the emergency worker. Don't hog it. Hopefully, 1024 is | |
1858 | * enough for efficient IO. | |
1859 | */ | |
f0054bb1 | 1860 | pages_written = writeback_inodes_wb(wb, 1024, |
839a8e86 | 1861 | WB_REASON_FORKER_THREAD); |
455b2864 | 1862 | trace_writeback_pages_written(pages_written); |
03ba3782 JA |
1863 | } |
1864 | ||
f0054bb1 | 1865 | if (!list_empty(&wb->work_list)) |
6ca738d6 DB |
1866 | mod_delayed_work(bdi_wq, &wb->dwork, 0); |
1867 | else if (wb_has_dirty_io(wb) && dirty_writeback_interval) | |
f0054bb1 | 1868 | wb_wakeup_delayed(wb); |
455b2864 | 1869 | |
839a8e86 | 1870 | current->flags &= ~PF_SWAPWRITE; |
03ba3782 JA |
1871 | } |
1872 | ||
1873 | /* | |
b8c2f347 CH |
1874 | * Start writeback of `nr_pages' pages. If `nr_pages' is zero, write back |
1875 | * the whole world. | |
03ba3782 | 1876 | */ |
0e175a18 | 1877 | void wakeup_flusher_threads(long nr_pages, enum wb_reason reason) |
03ba3782 | 1878 | { |
b8c2f347 | 1879 | struct backing_dev_info *bdi; |
03ba3782 | 1880 | |
47df3dde JK |
1881 | if (!nr_pages) |
1882 | nr_pages = get_nr_dirty_pages(); | |
03ba3782 | 1883 | |
b8c2f347 | 1884 | rcu_read_lock(); |
f2b65121 TH |
1885 | list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) { |
1886 | struct bdi_writeback *wb; | |
1887 | struct wb_iter iter; | |
1888 | ||
1889 | if (!bdi_has_dirty_io(bdi)) | |
1890 | continue; | |
1891 | ||
1892 | bdi_for_each_wb(wb, bdi, &iter, 0) | |
1893 | wb_start_writeback(wb, wb_split_bdi_pages(wb, nr_pages), | |
1894 | false, reason); | |
1895 | } | |
cfc4ba53 | 1896 | rcu_read_unlock(); |
1da177e4 LT |
1897 | } |
1898 | ||
a2f48706 TT |
1899 | /* |
1900 | * Wake up bdi's periodically to make sure dirtytime inodes gets | |
1901 | * written back periodically. We deliberately do *not* check the | |
1902 | * b_dirtytime list in wb_has_dirty_io(), since this would cause the | |
1903 | * kernel to be constantly waking up once there are any dirtytime | |
1904 | * inodes on the system. So instead we define a separate delayed work | |
1905 | * function which gets called much more rarely. (By default, only | |
1906 | * once every 12 hours.) | |
1907 | * | |
1908 | * If there is any other write activity going on in the file system, | |
1909 | * this function won't be necessary. But if the only thing that has | |
1910 | * happened on the file system is a dirtytime inode caused by an atime | |
1911 | * update, we need this infrastructure below to make sure that inode | |
1912 | * eventually gets pushed out to disk. | |
1913 | */ | |
1914 | static void wakeup_dirtytime_writeback(struct work_struct *w); | |
1915 | static DECLARE_DELAYED_WORK(dirtytime_work, wakeup_dirtytime_writeback); | |
1916 | ||
1917 | static void wakeup_dirtytime_writeback(struct work_struct *w) | |
1918 | { | |
1919 | struct backing_dev_info *bdi; | |
1920 | ||
1921 | rcu_read_lock(); | |
1922 | list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) { | |
001fe6f6 TH |
1923 | struct bdi_writeback *wb; |
1924 | struct wb_iter iter; | |
1925 | ||
1926 | bdi_for_each_wb(wb, bdi, &iter, 0) | |
1927 | if (!list_empty(&bdi->wb.b_dirty_time)) | |
1928 | wb_wakeup(&bdi->wb); | |
a2f48706 TT |
1929 | } |
1930 | rcu_read_unlock(); | |
1931 | schedule_delayed_work(&dirtytime_work, dirtytime_expire_interval * HZ); | |
1932 | } | |
1933 | ||
1934 | static int __init start_dirtytime_writeback(void) | |
1935 | { | |
1936 | schedule_delayed_work(&dirtytime_work, dirtytime_expire_interval * HZ); | |
1937 | return 0; | |
1938 | } | |
1939 | __initcall(start_dirtytime_writeback); | |
1940 | ||
1efff914 TT |
1941 | int dirtytime_interval_handler(struct ctl_table *table, int write, |
1942 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
1943 | { | |
1944 | int ret; | |
1945 | ||
1946 | ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); | |
1947 | if (ret == 0 && write) | |
1948 | mod_delayed_work(system_wq, &dirtytime_work, 0); | |
1949 | return ret; | |
1950 | } | |
1951 | ||
03ba3782 JA |
1952 | static noinline void block_dump___mark_inode_dirty(struct inode *inode) |
1953 | { | |
1954 | if (inode->i_ino || strcmp(inode->i_sb->s_id, "bdev")) { | |
1955 | struct dentry *dentry; | |
1956 | const char *name = "?"; | |
1957 | ||
1958 | dentry = d_find_alias(inode); | |
1959 | if (dentry) { | |
1960 | spin_lock(&dentry->d_lock); | |
1961 | name = (const char *) dentry->d_name.name; | |
1962 | } | |
1963 | printk(KERN_DEBUG | |
1964 | "%s(%d): dirtied inode %lu (%s) on %s\n", | |
1965 | current->comm, task_pid_nr(current), inode->i_ino, | |
1966 | name, inode->i_sb->s_id); | |
1967 | if (dentry) { | |
1968 | spin_unlock(&dentry->d_lock); | |
1969 | dput(dentry); | |
1970 | } | |
1971 | } | |
1972 | } | |
1973 | ||
1974 | /** | |
1975 | * __mark_inode_dirty - internal function | |
1976 | * @inode: inode to mark | |
1977 | * @flags: what kind of dirty (i.e. I_DIRTY_SYNC) | |
1978 | * Mark an inode as dirty. Callers should use mark_inode_dirty or | |
1979 | * mark_inode_dirty_sync. | |
1da177e4 | 1980 | * |
03ba3782 JA |
1981 | * Put the inode on the super block's dirty list. |
1982 | * | |
1983 | * CAREFUL! We mark it dirty unconditionally, but move it onto the | |
1984 | * dirty list only if it is hashed or if it refers to a blockdev. | |
1985 | * If it was not hashed, it will never be added to the dirty list | |
1986 | * even if it is later hashed, as it will have been marked dirty already. | |
1987 | * | |
1988 | * In short, make sure you hash any inodes _before_ you start marking | |
1989 | * them dirty. | |
1da177e4 | 1990 | * |
03ba3782 JA |
1991 | * Note that for blockdevs, inode->dirtied_when represents the dirtying time of |
1992 | * the block-special inode (/dev/hda1) itself. And the ->dirtied_when field of | |
1993 | * the kernel-internal blockdev inode represents the dirtying time of the | |
1994 | * blockdev's pages. This is why for I_DIRTY_PAGES we always use | |
1995 | * page->mapping->host, so the page-dirtying time is recorded in the internal | |
1996 | * blockdev inode. | |
1da177e4 | 1997 | */ |
0ae45f63 | 1998 | #define I_DIRTY_INODE (I_DIRTY_SYNC | I_DIRTY_DATASYNC) |
03ba3782 | 1999 | void __mark_inode_dirty(struct inode *inode, int flags) |
1da177e4 | 2000 | { |
03ba3782 | 2001 | struct super_block *sb = inode->i_sb; |
0ae45f63 TT |
2002 | int dirtytime; |
2003 | ||
2004 | trace_writeback_mark_inode_dirty(inode, flags); | |
1da177e4 | 2005 | |
03ba3782 JA |
2006 | /* |
2007 | * Don't do this for I_DIRTY_PAGES - that doesn't actually | |
2008 | * dirty the inode itself | |
2009 | */ | |
0ae45f63 | 2010 | if (flags & (I_DIRTY_SYNC | I_DIRTY_DATASYNC | I_DIRTY_TIME)) { |
9fb0a7da TH |
2011 | trace_writeback_dirty_inode_start(inode, flags); |
2012 | ||
03ba3782 | 2013 | if (sb->s_op->dirty_inode) |
aa385729 | 2014 | sb->s_op->dirty_inode(inode, flags); |
9fb0a7da TH |
2015 | |
2016 | trace_writeback_dirty_inode(inode, flags); | |
03ba3782 | 2017 | } |
0ae45f63 TT |
2018 | if (flags & I_DIRTY_INODE) |
2019 | flags &= ~I_DIRTY_TIME; | |
2020 | dirtytime = flags & I_DIRTY_TIME; | |
03ba3782 JA |
2021 | |
2022 | /* | |
9c6ac78e TH |
2023 | * Paired with smp_mb() in __writeback_single_inode() for the |
2024 | * following lockless i_state test. See there for details. | |
03ba3782 JA |
2025 | */ |
2026 | smp_mb(); | |
2027 | ||
0ae45f63 TT |
2028 | if (((inode->i_state & flags) == flags) || |
2029 | (dirtytime && (inode->i_state & I_DIRTY_INODE))) | |
03ba3782 JA |
2030 | return; |
2031 | ||
2032 | if (unlikely(block_dump)) | |
2033 | block_dump___mark_inode_dirty(inode); | |
2034 | ||
250df6ed | 2035 | spin_lock(&inode->i_lock); |
0ae45f63 TT |
2036 | if (dirtytime && (inode->i_state & I_DIRTY_INODE)) |
2037 | goto out_unlock_inode; | |
03ba3782 JA |
2038 | if ((inode->i_state & flags) != flags) { |
2039 | const int was_dirty = inode->i_state & I_DIRTY; | |
2040 | ||
52ebea74 TH |
2041 | inode_attach_wb(inode, NULL); |
2042 | ||
0ae45f63 TT |
2043 | if (flags & I_DIRTY_INODE) |
2044 | inode->i_state &= ~I_DIRTY_TIME; | |
03ba3782 JA |
2045 | inode->i_state |= flags; |
2046 | ||
2047 | /* | |
2048 | * If the inode is being synced, just update its dirty state. | |
2049 | * The unlocker will place the inode on the appropriate | |
2050 | * superblock list, based upon its state. | |
2051 | */ | |
2052 | if (inode->i_state & I_SYNC) | |
250df6ed | 2053 | goto out_unlock_inode; |
03ba3782 JA |
2054 | |
2055 | /* | |
2056 | * Only add valid (hashed) inodes to the superblock's | |
2057 | * dirty list. Add blockdev inodes as well. | |
2058 | */ | |
2059 | if (!S_ISBLK(inode->i_mode)) { | |
1d3382cb | 2060 | if (inode_unhashed(inode)) |
250df6ed | 2061 | goto out_unlock_inode; |
03ba3782 | 2062 | } |
a4ffdde6 | 2063 | if (inode->i_state & I_FREEING) |
250df6ed | 2064 | goto out_unlock_inode; |
03ba3782 JA |
2065 | |
2066 | /* | |
2067 | * If the inode was already on b_dirty/b_io/b_more_io, don't | |
2068 | * reposition it (that would break b_dirty time-ordering). | |
2069 | */ | |
2070 | if (!was_dirty) { | |
87e1d789 | 2071 | struct bdi_writeback *wb; |
d6c10f1f | 2072 | struct list_head *dirty_list; |
a66979ab | 2073 | bool wakeup_bdi = false; |
253c34e9 | 2074 | |
87e1d789 | 2075 | wb = locked_inode_to_wb_and_lock_list(inode); |
253c34e9 | 2076 | |
0747259d TH |
2077 | WARN(bdi_cap_writeback_dirty(wb->bdi) && |
2078 | !test_bit(WB_registered, &wb->state), | |
2079 | "bdi-%s not registered\n", wb->bdi->name); | |
03ba3782 JA |
2080 | |
2081 | inode->dirtied_when = jiffies; | |
a2f48706 TT |
2082 | if (dirtytime) |
2083 | inode->dirtied_time_when = jiffies; | |
d6c10f1f | 2084 | |
a2f48706 | 2085 | if (inode->i_state & (I_DIRTY_INODE | I_DIRTY_PAGES)) |
0747259d | 2086 | dirty_list = &wb->b_dirty; |
a2f48706 | 2087 | else |
0747259d | 2088 | dirty_list = &wb->b_dirty_time; |
d6c10f1f | 2089 | |
0747259d | 2090 | wakeup_bdi = inode_wb_list_move_locked(inode, wb, |
d6c10f1f TH |
2091 | dirty_list); |
2092 | ||
0747259d | 2093 | spin_unlock(&wb->list_lock); |
0ae45f63 | 2094 | trace_writeback_dirty_inode_enqueue(inode); |
a66979ab | 2095 | |
d6c10f1f TH |
2096 | /* |
2097 | * If this is the first dirty inode for this bdi, | |
2098 | * we have to wake-up the corresponding bdi thread | |
2099 | * to make sure background write-back happens | |
2100 | * later. | |
2101 | */ | |
0747259d TH |
2102 | if (bdi_cap_writeback_dirty(wb->bdi) && wakeup_bdi) |
2103 | wb_wakeup_delayed(wb); | |
a66979ab | 2104 | return; |
1da177e4 | 2105 | } |
1da177e4 | 2106 | } |
250df6ed DC |
2107 | out_unlock_inode: |
2108 | spin_unlock(&inode->i_lock); | |
253c34e9 | 2109 | |
03ba3782 JA |
2110 | } |
2111 | EXPORT_SYMBOL(__mark_inode_dirty); | |
2112 | ||
b6e51316 | 2113 | static void wait_sb_inodes(struct super_block *sb) |
03ba3782 JA |
2114 | { |
2115 | struct inode *inode, *old_inode = NULL; | |
2116 | ||
2117 | /* | |
2118 | * We need to be protected against the filesystem going from | |
2119 | * r/o to r/w or vice versa. | |
2120 | */ | |
b6e51316 | 2121 | WARN_ON(!rwsem_is_locked(&sb->s_umount)); |
03ba3782 | 2122 | |
55fa6091 | 2123 | spin_lock(&inode_sb_list_lock); |
03ba3782 JA |
2124 | |
2125 | /* | |
2126 | * Data integrity sync. Must wait for all pages under writeback, | |
2127 | * because there may have been pages dirtied before our sync | |
2128 | * call, but which had writeout started before we write it out. | |
2129 | * In which case, the inode may not be on the dirty list, but | |
2130 | * we still have to wait for that writeout. | |
2131 | */ | |
b6e51316 | 2132 | list_for_each_entry(inode, &sb->s_inodes, i_sb_list) { |
250df6ed | 2133 | struct address_space *mapping = inode->i_mapping; |
03ba3782 | 2134 | |
250df6ed DC |
2135 | spin_lock(&inode->i_lock); |
2136 | if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) || | |
2137 | (mapping->nrpages == 0)) { | |
2138 | spin_unlock(&inode->i_lock); | |
03ba3782 | 2139 | continue; |
250df6ed | 2140 | } |
03ba3782 | 2141 | __iget(inode); |
250df6ed | 2142 | spin_unlock(&inode->i_lock); |
55fa6091 DC |
2143 | spin_unlock(&inode_sb_list_lock); |
2144 | ||
03ba3782 | 2145 | /* |
55fa6091 DC |
2146 | * We hold a reference to 'inode' so it couldn't have been |
2147 | * removed from s_inodes list while we dropped the | |
2148 | * inode_sb_list_lock. We cannot iput the inode now as we can | |
2149 | * be holding the last reference and we cannot iput it under | |
2150 | * inode_sb_list_lock. So we keep the reference and iput it | |
2151 | * later. | |
03ba3782 JA |
2152 | */ |
2153 | iput(old_inode); | |
2154 | old_inode = inode; | |
2155 | ||
2156 | filemap_fdatawait(mapping); | |
2157 | ||
2158 | cond_resched(); | |
2159 | ||
55fa6091 | 2160 | spin_lock(&inode_sb_list_lock); |
03ba3782 | 2161 | } |
55fa6091 | 2162 | spin_unlock(&inode_sb_list_lock); |
03ba3782 | 2163 | iput(old_inode); |
1da177e4 LT |
2164 | } |
2165 | ||
f30a7d0c TH |
2166 | static void __writeback_inodes_sb_nr(struct super_block *sb, unsigned long nr, |
2167 | enum wb_reason reason, bool skip_if_busy) | |
1da177e4 | 2168 | { |
cc395d7f | 2169 | DEFINE_WB_COMPLETION_ONSTACK(done); |
83ba7b07 | 2170 | struct wb_writeback_work work = { |
6e6938b6 WF |
2171 | .sb = sb, |
2172 | .sync_mode = WB_SYNC_NONE, | |
2173 | .tagged_writepages = 1, | |
2174 | .done = &done, | |
2175 | .nr_pages = nr, | |
0e175a18 | 2176 | .reason = reason, |
3c4d7165 | 2177 | }; |
e7972912 | 2178 | struct backing_dev_info *bdi = sb->s_bdi; |
d8a8559c | 2179 | |
e7972912 | 2180 | if (!bdi_has_dirty_io(bdi) || bdi == &noop_backing_dev_info) |
6eedc701 | 2181 | return; |
cf37e972 | 2182 | WARN_ON(!rwsem_is_locked(&sb->s_umount)); |
f30a7d0c | 2183 | |
db125360 | 2184 | bdi_split_work_to_wbs(sb->s_bdi, &work, skip_if_busy); |
cc395d7f | 2185 | wb_wait_for_completion(bdi, &done); |
e913fc82 | 2186 | } |
f30a7d0c TH |
2187 | |
2188 | /** | |
2189 | * writeback_inodes_sb_nr - writeback dirty inodes from given super_block | |
2190 | * @sb: the superblock | |
2191 | * @nr: the number of pages to write | |
2192 | * @reason: reason why some writeback work initiated | |
2193 | * | |
2194 | * Start writeback on some inodes on this super_block. No guarantees are made | |
2195 | * on how many (if any) will be written, and this function does not wait | |
2196 | * for IO completion of submitted IO. | |
2197 | */ | |
2198 | void writeback_inodes_sb_nr(struct super_block *sb, | |
2199 | unsigned long nr, | |
2200 | enum wb_reason reason) | |
2201 | { | |
2202 | __writeback_inodes_sb_nr(sb, nr, reason, false); | |
2203 | } | |
3259f8be CM |
2204 | EXPORT_SYMBOL(writeback_inodes_sb_nr); |
2205 | ||
2206 | /** | |
2207 | * writeback_inodes_sb - writeback dirty inodes from given super_block | |
2208 | * @sb: the superblock | |
786228ab | 2209 | * @reason: reason why some writeback work was initiated |
3259f8be CM |
2210 | * |
2211 | * Start writeback on some inodes on this super_block. No guarantees are made | |
2212 | * on how many (if any) will be written, and this function does not wait | |
2213 | * for IO completion of submitted IO. | |
2214 | */ | |
0e175a18 | 2215 | void writeback_inodes_sb(struct super_block *sb, enum wb_reason reason) |
3259f8be | 2216 | { |
0e175a18 | 2217 | return writeback_inodes_sb_nr(sb, get_nr_dirty_pages(), reason); |
3259f8be | 2218 | } |
0e3c9a22 | 2219 | EXPORT_SYMBOL(writeback_inodes_sb); |
e913fc82 | 2220 | |
17bd55d0 | 2221 | /** |
10ee27a0 | 2222 | * try_to_writeback_inodes_sb_nr - try to start writeback if none underway |
17bd55d0 | 2223 | * @sb: the superblock |
10ee27a0 MX |
2224 | * @nr: the number of pages to write |
2225 | * @reason: the reason of writeback | |
17bd55d0 | 2226 | * |
10ee27a0 | 2227 | * Invoke writeback_inodes_sb_nr if no writeback is currently underway. |
17bd55d0 ES |
2228 | * Returns 1 if writeback was started, 0 if not. |
2229 | */ | |
f30a7d0c TH |
2230 | bool try_to_writeback_inodes_sb_nr(struct super_block *sb, unsigned long nr, |
2231 | enum wb_reason reason) | |
17bd55d0 | 2232 | { |
10ee27a0 | 2233 | if (!down_read_trylock(&sb->s_umount)) |
f30a7d0c | 2234 | return false; |
10ee27a0 | 2235 | |
f30a7d0c | 2236 | __writeback_inodes_sb_nr(sb, nr, reason, true); |
10ee27a0 | 2237 | up_read(&sb->s_umount); |
f30a7d0c | 2238 | return true; |
17bd55d0 | 2239 | } |
10ee27a0 | 2240 | EXPORT_SYMBOL(try_to_writeback_inodes_sb_nr); |
17bd55d0 | 2241 | |
3259f8be | 2242 | /** |
10ee27a0 | 2243 | * try_to_writeback_inodes_sb - try to start writeback if none underway |
3259f8be | 2244 | * @sb: the superblock |
786228ab | 2245 | * @reason: reason why some writeback work was initiated |
3259f8be | 2246 | * |
10ee27a0 | 2247 | * Implement by try_to_writeback_inodes_sb_nr() |
3259f8be CM |
2248 | * Returns 1 if writeback was started, 0 if not. |
2249 | */ | |
f30a7d0c | 2250 | bool try_to_writeback_inodes_sb(struct super_block *sb, enum wb_reason reason) |
3259f8be | 2251 | { |
10ee27a0 | 2252 | return try_to_writeback_inodes_sb_nr(sb, get_nr_dirty_pages(), reason); |
3259f8be | 2253 | } |
10ee27a0 | 2254 | EXPORT_SYMBOL(try_to_writeback_inodes_sb); |
3259f8be | 2255 | |
d8a8559c JA |
2256 | /** |
2257 | * sync_inodes_sb - sync sb inode pages | |
0dc83bd3 | 2258 | * @sb: the superblock |
d8a8559c JA |
2259 | * |
2260 | * This function writes and waits on any dirty inode belonging to this | |
0dc83bd3 | 2261 | * super_block. |
d8a8559c | 2262 | */ |
0dc83bd3 | 2263 | void sync_inodes_sb(struct super_block *sb) |
d8a8559c | 2264 | { |
cc395d7f | 2265 | DEFINE_WB_COMPLETION_ONSTACK(done); |
83ba7b07 | 2266 | struct wb_writeback_work work = { |
3c4d7165 CH |
2267 | .sb = sb, |
2268 | .sync_mode = WB_SYNC_ALL, | |
2269 | .nr_pages = LONG_MAX, | |
2270 | .range_cyclic = 0, | |
83ba7b07 | 2271 | .done = &done, |
0e175a18 | 2272 | .reason = WB_REASON_SYNC, |
7747bd4b | 2273 | .for_sync = 1, |
3c4d7165 | 2274 | }; |
e7972912 | 2275 | struct backing_dev_info *bdi = sb->s_bdi; |
3c4d7165 | 2276 | |
6eedc701 | 2277 | /* Nothing to do? */ |
e7972912 | 2278 | if (!bdi_has_dirty_io(bdi) || bdi == &noop_backing_dev_info) |
6eedc701 | 2279 | return; |
cf37e972 CH |
2280 | WARN_ON(!rwsem_is_locked(&sb->s_umount)); |
2281 | ||
db125360 | 2282 | bdi_split_work_to_wbs(bdi, &work, false); |
cc395d7f | 2283 | wb_wait_for_completion(bdi, &done); |
83ba7b07 | 2284 | |
b6e51316 | 2285 | wait_sb_inodes(sb); |
1da177e4 | 2286 | } |
d8a8559c | 2287 | EXPORT_SYMBOL(sync_inodes_sb); |
1da177e4 | 2288 | |
1da177e4 | 2289 | /** |
7f04c26d AA |
2290 | * write_inode_now - write an inode to disk |
2291 | * @inode: inode to write to disk | |
2292 | * @sync: whether the write should be synchronous or not | |
2293 | * | |
2294 | * This function commits an inode to disk immediately if it is dirty. This is | |
2295 | * primarily needed by knfsd. | |
1da177e4 | 2296 | * |
7f04c26d | 2297 | * The caller must either have a ref on the inode or must have set I_WILL_FREE. |
1da177e4 | 2298 | */ |
1da177e4 LT |
2299 | int write_inode_now(struct inode *inode, int sync) |
2300 | { | |
f758eeab | 2301 | struct bdi_writeback *wb = &inode_to_bdi(inode)->wb; |
1da177e4 LT |
2302 | struct writeback_control wbc = { |
2303 | .nr_to_write = LONG_MAX, | |
18914b18 | 2304 | .sync_mode = sync ? WB_SYNC_ALL : WB_SYNC_NONE, |
111ebb6e OH |
2305 | .range_start = 0, |
2306 | .range_end = LLONG_MAX, | |
1da177e4 LT |
2307 | }; |
2308 | ||
2309 | if (!mapping_cap_writeback_dirty(inode->i_mapping)) | |
49364ce2 | 2310 | wbc.nr_to_write = 0; |
1da177e4 LT |
2311 | |
2312 | might_sleep(); | |
4f8ad655 | 2313 | return writeback_single_inode(inode, wb, &wbc); |
1da177e4 LT |
2314 | } |
2315 | EXPORT_SYMBOL(write_inode_now); | |
2316 | ||
2317 | /** | |
2318 | * sync_inode - write an inode and its pages to disk. | |
2319 | * @inode: the inode to sync | |
2320 | * @wbc: controls the writeback mode | |
2321 | * | |
2322 | * sync_inode() will write an inode and its pages to disk. It will also | |
2323 | * correctly update the inode on its superblock's dirty inode lists and will | |
2324 | * update inode->i_state. | |
2325 | * | |
2326 | * The caller must have a ref on the inode. | |
2327 | */ | |
2328 | int sync_inode(struct inode *inode, struct writeback_control *wbc) | |
2329 | { | |
4f8ad655 | 2330 | return writeback_single_inode(inode, &inode_to_bdi(inode)->wb, wbc); |
1da177e4 LT |
2331 | } |
2332 | EXPORT_SYMBOL(sync_inode); | |
c3765016 CH |
2333 | |
2334 | /** | |
c691b9d9 | 2335 | * sync_inode_metadata - write an inode to disk |
c3765016 CH |
2336 | * @inode: the inode to sync |
2337 | * @wait: wait for I/O to complete. | |
2338 | * | |
c691b9d9 | 2339 | * Write an inode to disk and adjust its dirty state after completion. |
c3765016 CH |
2340 | * |
2341 | * Note: only writes the actual inode, no associated data or other metadata. | |
2342 | */ | |
2343 | int sync_inode_metadata(struct inode *inode, int wait) | |
2344 | { | |
2345 | struct writeback_control wbc = { | |
2346 | .sync_mode = wait ? WB_SYNC_ALL : WB_SYNC_NONE, | |
2347 | .nr_to_write = 0, /* metadata-only */ | |
2348 | }; | |
2349 | ||
2350 | return sync_inode(inode, &wbc); | |
2351 | } | |
2352 | EXPORT_SYMBOL(sync_inode_metadata); |