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 */ |
0e175a18 | 56 | enum wb_reason reason; /* why was writeback initiated? */ |
c4a77a6c | 57 | |
8010c3b6 | 58 | struct list_head list; /* pending work list */ |
cc395d7f | 59 | struct wb_completion *done; /* set if the caller waits */ |
03ba3782 JA |
60 | }; |
61 | ||
cc395d7f TH |
62 | /* |
63 | * If one wants to wait for one or more wb_writeback_works, each work's | |
64 | * ->done should be set to a wb_completion defined using the following | |
65 | * macro. Once all work items are issued with wb_queue_work(), the caller | |
66 | * can wait for the completion of all using wb_wait_for_completion(). Work | |
67 | * items which are waited upon aren't freed automatically on completion. | |
68 | */ | |
69 | #define DEFINE_WB_COMPLETION_ONSTACK(cmpl) \ | |
70 | struct wb_completion cmpl = { \ | |
71 | .cnt = ATOMIC_INIT(1), \ | |
72 | } | |
73 | ||
74 | ||
a2f48706 TT |
75 | /* |
76 | * If an inode is constantly having its pages dirtied, but then the | |
77 | * updates stop dirtytime_expire_interval seconds in the past, it's | |
78 | * possible for the worst case time between when an inode has its | |
79 | * timestamps updated and when they finally get written out to be two | |
80 | * dirtytime_expire_intervals. We set the default to 12 hours (in | |
81 | * seconds), which means most of the time inodes will have their | |
82 | * timestamps written to disk after 12 hours, but in the worst case a | |
83 | * few inodes might not their timestamps updated for 24 hours. | |
84 | */ | |
85 | unsigned int dirtytime_expire_interval = 12 * 60 * 60; | |
86 | ||
7ccf19a8 NP |
87 | static inline struct inode *wb_inode(struct list_head *head) |
88 | { | |
c7f54084 | 89 | return list_entry(head, struct inode, i_io_list); |
7ccf19a8 NP |
90 | } |
91 | ||
15eb77a0 WF |
92 | /* |
93 | * Include the creation of the trace points after defining the | |
94 | * wb_writeback_work structure and inline functions so that the definition | |
95 | * remains local to this file. | |
96 | */ | |
97 | #define CREATE_TRACE_POINTS | |
98 | #include <trace/events/writeback.h> | |
99 | ||
774016b2 SW |
100 | EXPORT_TRACEPOINT_SYMBOL_GPL(wbc_writepage); |
101 | ||
d6c10f1f TH |
102 | static bool wb_io_lists_populated(struct bdi_writeback *wb) |
103 | { | |
104 | if (wb_has_dirty_io(wb)) { | |
105 | return false; | |
106 | } else { | |
107 | set_bit(WB_has_dirty_io, &wb->state); | |
95a46c65 | 108 | WARN_ON_ONCE(!wb->avg_write_bandwidth); |
766a9d6e TH |
109 | atomic_long_add(wb->avg_write_bandwidth, |
110 | &wb->bdi->tot_write_bandwidth); | |
d6c10f1f TH |
111 | return true; |
112 | } | |
113 | } | |
114 | ||
115 | static void wb_io_lists_depopulated(struct bdi_writeback *wb) | |
116 | { | |
117 | if (wb_has_dirty_io(wb) && list_empty(&wb->b_dirty) && | |
766a9d6e | 118 | list_empty(&wb->b_io) && list_empty(&wb->b_more_io)) { |
d6c10f1f | 119 | clear_bit(WB_has_dirty_io, &wb->state); |
95a46c65 TH |
120 | WARN_ON_ONCE(atomic_long_sub_return(wb->avg_write_bandwidth, |
121 | &wb->bdi->tot_write_bandwidth) < 0); | |
766a9d6e | 122 | } |
d6c10f1f TH |
123 | } |
124 | ||
125 | /** | |
c7f54084 | 126 | * inode_io_list_move_locked - move an inode onto a bdi_writeback IO list |
d6c10f1f TH |
127 | * @inode: inode to be moved |
128 | * @wb: target bdi_writeback | |
129 | * @head: one of @wb->b_{dirty|io|more_io} | |
130 | * | |
c7f54084 | 131 | * Move @inode->i_io_list to @list of @wb and set %WB_has_dirty_io. |
d6c10f1f TH |
132 | * Returns %true if @inode is the first occupant of the !dirty_time IO |
133 | * lists; otherwise, %false. | |
134 | */ | |
c7f54084 | 135 | static bool inode_io_list_move_locked(struct inode *inode, |
d6c10f1f TH |
136 | struct bdi_writeback *wb, |
137 | struct list_head *head) | |
138 | { | |
139 | assert_spin_locked(&wb->list_lock); | |
140 | ||
c7f54084 | 141 | list_move(&inode->i_io_list, head); |
d6c10f1f TH |
142 | |
143 | /* dirty_time doesn't count as dirty_io until expiration */ | |
144 | if (head != &wb->b_dirty_time) | |
145 | return wb_io_lists_populated(wb); | |
146 | ||
147 | wb_io_lists_depopulated(wb); | |
148 | return false; | |
149 | } | |
150 | ||
151 | /** | |
c7f54084 | 152 | * inode_io_list_del_locked - remove an inode from its bdi_writeback IO list |
d6c10f1f TH |
153 | * @inode: inode to be removed |
154 | * @wb: bdi_writeback @inode is being removed from | |
155 | * | |
156 | * Remove @inode which may be on one of @wb->b_{dirty|io|more_io} lists and | |
157 | * clear %WB_has_dirty_io if all are empty afterwards. | |
158 | */ | |
c7f54084 | 159 | static void inode_io_list_del_locked(struct inode *inode, |
d6c10f1f TH |
160 | struct bdi_writeback *wb) |
161 | { | |
162 | assert_spin_locked(&wb->list_lock); | |
163 | ||
c7f54084 | 164 | list_del_init(&inode->i_io_list); |
d6c10f1f TH |
165 | wb_io_lists_depopulated(wb); |
166 | } | |
167 | ||
f0054bb1 | 168 | static void wb_wakeup(struct bdi_writeback *wb) |
5acda9d1 | 169 | { |
f0054bb1 TH |
170 | spin_lock_bh(&wb->work_lock); |
171 | if (test_bit(WB_registered, &wb->state)) | |
172 | mod_delayed_work(bdi_wq, &wb->dwork, 0); | |
173 | spin_unlock_bh(&wb->work_lock); | |
5acda9d1 JK |
174 | } |
175 | ||
f0054bb1 TH |
176 | static void wb_queue_work(struct bdi_writeback *wb, |
177 | struct wb_writeback_work *work) | |
6585027a | 178 | { |
5634cc2a | 179 | trace_writeback_queue(wb, work); |
6585027a | 180 | |
f0054bb1 | 181 | spin_lock_bh(&wb->work_lock); |
8a1270cd | 182 | if (!test_bit(WB_registered, &wb->state)) |
5acda9d1 | 183 | goto out_unlock; |
cc395d7f TH |
184 | if (work->done) |
185 | atomic_inc(&work->done->cnt); | |
f0054bb1 TH |
186 | list_add_tail(&work->list, &wb->work_list); |
187 | mod_delayed_work(bdi_wq, &wb->dwork, 0); | |
5acda9d1 | 188 | out_unlock: |
f0054bb1 | 189 | spin_unlock_bh(&wb->work_lock); |
1da177e4 LT |
190 | } |
191 | ||
cc395d7f TH |
192 | /** |
193 | * wb_wait_for_completion - wait for completion of bdi_writeback_works | |
194 | * @bdi: bdi work items were issued to | |
195 | * @done: target wb_completion | |
196 | * | |
197 | * Wait for one or more work items issued to @bdi with their ->done field | |
198 | * set to @done, which should have been defined with | |
199 | * DEFINE_WB_COMPLETION_ONSTACK(). This function returns after all such | |
200 | * work items are completed. Work items which are waited upon aren't freed | |
201 | * automatically on completion. | |
202 | */ | |
203 | static void wb_wait_for_completion(struct backing_dev_info *bdi, | |
204 | struct wb_completion *done) | |
205 | { | |
206 | atomic_dec(&done->cnt); /* put down the initial count */ | |
207 | wait_event(bdi->wb_waitq, !atomic_read(&done->cnt)); | |
208 | } | |
209 | ||
703c2708 TH |
210 | #ifdef CONFIG_CGROUP_WRITEBACK |
211 | ||
2a814908 TH |
212 | /* parameters for foreign inode detection, see wb_detach_inode() */ |
213 | #define WB_FRN_TIME_SHIFT 13 /* 1s = 2^13, upto 8 secs w/ 16bit */ | |
214 | #define WB_FRN_TIME_AVG_SHIFT 3 /* avg = avg * 7/8 + new * 1/8 */ | |
215 | #define WB_FRN_TIME_CUT_DIV 2 /* ignore rounds < avg / 2 */ | |
216 | #define WB_FRN_TIME_PERIOD (2 * (1 << WB_FRN_TIME_SHIFT)) /* 2s */ | |
217 | ||
218 | #define WB_FRN_HIST_SLOTS 16 /* inode->i_wb_frn_history is 16bit */ | |
219 | #define WB_FRN_HIST_UNIT (WB_FRN_TIME_PERIOD / WB_FRN_HIST_SLOTS) | |
220 | /* each slot's duration is 2s / 16 */ | |
221 | #define WB_FRN_HIST_THR_SLOTS (WB_FRN_HIST_SLOTS / 2) | |
222 | /* if foreign slots >= 8, switch */ | |
223 | #define WB_FRN_HIST_MAX_SLOTS (WB_FRN_HIST_THR_SLOTS / 2 + 1) | |
224 | /* one round can affect upto 5 slots */ | |
225 | ||
21c6321f TH |
226 | void __inode_attach_wb(struct inode *inode, struct page *page) |
227 | { | |
228 | struct backing_dev_info *bdi = inode_to_bdi(inode); | |
229 | struct bdi_writeback *wb = NULL; | |
230 | ||
231 | if (inode_cgwb_enabled(inode)) { | |
232 | struct cgroup_subsys_state *memcg_css; | |
233 | ||
234 | if (page) { | |
235 | memcg_css = mem_cgroup_css_from_page(page); | |
236 | wb = wb_get_create(bdi, memcg_css, GFP_ATOMIC); | |
237 | } else { | |
238 | /* must pin memcg_css, see wb_get_create() */ | |
239 | memcg_css = task_get_css(current, memory_cgrp_id); | |
240 | wb = wb_get_create(bdi, memcg_css, GFP_ATOMIC); | |
241 | css_put(memcg_css); | |
242 | } | |
243 | } | |
244 | ||
245 | if (!wb) | |
246 | wb = &bdi->wb; | |
247 | ||
248 | /* | |
249 | * There may be multiple instances of this function racing to | |
250 | * update the same inode. Use cmpxchg() to tell the winner. | |
251 | */ | |
252 | if (unlikely(cmpxchg(&inode->i_wb, NULL, wb))) | |
253 | wb_put(wb); | |
254 | } | |
255 | ||
87e1d789 TH |
256 | /** |
257 | * locked_inode_to_wb_and_lock_list - determine a locked inode's wb and lock it | |
258 | * @inode: inode of interest with i_lock held | |
259 | * | |
260 | * Returns @inode's wb with its list_lock held. @inode->i_lock must be | |
261 | * held on entry and is released on return. The returned wb is guaranteed | |
262 | * to stay @inode's associated wb until its list_lock is released. | |
263 | */ | |
264 | static struct bdi_writeback * | |
265 | locked_inode_to_wb_and_lock_list(struct inode *inode) | |
266 | __releases(&inode->i_lock) | |
267 | __acquires(&wb->list_lock) | |
268 | { | |
269 | while (true) { | |
270 | struct bdi_writeback *wb = inode_to_wb(inode); | |
271 | ||
272 | /* | |
273 | * inode_to_wb() association is protected by both | |
274 | * @inode->i_lock and @wb->list_lock but list_lock nests | |
275 | * outside i_lock. Drop i_lock and verify that the | |
276 | * association hasn't changed after acquiring list_lock. | |
277 | */ | |
278 | wb_get(wb); | |
279 | spin_unlock(&inode->i_lock); | |
280 | spin_lock(&wb->list_lock); | |
281 | wb_put(wb); /* not gonna deref it anymore */ | |
282 | ||
aaa2cacf TH |
283 | /* i_wb may have changed inbetween, can't use inode_to_wb() */ |
284 | if (likely(wb == inode->i_wb)) | |
87e1d789 TH |
285 | return wb; /* @inode already has ref */ |
286 | ||
287 | spin_unlock(&wb->list_lock); | |
288 | cpu_relax(); | |
289 | spin_lock(&inode->i_lock); | |
290 | } | |
291 | } | |
292 | ||
293 | /** | |
294 | * inode_to_wb_and_lock_list - determine an inode's wb and lock it | |
295 | * @inode: inode of interest | |
296 | * | |
297 | * Same as locked_inode_to_wb_and_lock_list() but @inode->i_lock isn't held | |
298 | * on entry. | |
299 | */ | |
300 | static struct bdi_writeback *inode_to_wb_and_lock_list(struct inode *inode) | |
301 | __acquires(&wb->list_lock) | |
302 | { | |
303 | spin_lock(&inode->i_lock); | |
304 | return locked_inode_to_wb_and_lock_list(inode); | |
305 | } | |
306 | ||
682aa8e1 TH |
307 | struct inode_switch_wbs_context { |
308 | struct inode *inode; | |
309 | struct bdi_writeback *new_wb; | |
310 | ||
311 | struct rcu_head rcu_head; | |
312 | struct work_struct work; | |
313 | }; | |
314 | ||
315 | static void inode_switch_wbs_work_fn(struct work_struct *work) | |
316 | { | |
317 | struct inode_switch_wbs_context *isw = | |
318 | container_of(work, struct inode_switch_wbs_context, work); | |
319 | struct inode *inode = isw->inode; | |
d10c8095 TH |
320 | struct address_space *mapping = inode->i_mapping; |
321 | struct bdi_writeback *old_wb = inode->i_wb; | |
682aa8e1 | 322 | struct bdi_writeback *new_wb = isw->new_wb; |
d10c8095 TH |
323 | struct radix_tree_iter iter; |
324 | bool switched = false; | |
325 | void **slot; | |
682aa8e1 TH |
326 | |
327 | /* | |
328 | * By the time control reaches here, RCU grace period has passed | |
329 | * since I_WB_SWITCH assertion and all wb stat update transactions | |
330 | * between unlocked_inode_to_wb_begin/end() are guaranteed to be | |
331 | * synchronizing against mapping->tree_lock. | |
d10c8095 TH |
332 | * |
333 | * Grabbing old_wb->list_lock, inode->i_lock and mapping->tree_lock | |
334 | * gives us exclusion against all wb related operations on @inode | |
335 | * including IO list manipulations and stat updates. | |
682aa8e1 | 336 | */ |
d10c8095 TH |
337 | if (old_wb < new_wb) { |
338 | spin_lock(&old_wb->list_lock); | |
339 | spin_lock_nested(&new_wb->list_lock, SINGLE_DEPTH_NESTING); | |
340 | } else { | |
341 | spin_lock(&new_wb->list_lock); | |
342 | spin_lock_nested(&old_wb->list_lock, SINGLE_DEPTH_NESTING); | |
343 | } | |
682aa8e1 | 344 | spin_lock(&inode->i_lock); |
d10c8095 TH |
345 | spin_lock_irq(&mapping->tree_lock); |
346 | ||
347 | /* | |
348 | * Once I_FREEING is visible under i_lock, the eviction path owns | |
c7f54084 | 349 | * the inode and we shouldn't modify ->i_io_list. |
d10c8095 TH |
350 | */ |
351 | if (unlikely(inode->i_state & I_FREEING)) | |
352 | goto skip_switch; | |
353 | ||
354 | /* | |
355 | * Count and transfer stats. Note that PAGECACHE_TAG_DIRTY points | |
356 | * to possibly dirty pages while PAGECACHE_TAG_WRITEBACK points to | |
357 | * pages actually under underwriteback. | |
358 | */ | |
359 | radix_tree_for_each_tagged(slot, &mapping->page_tree, &iter, 0, | |
360 | PAGECACHE_TAG_DIRTY) { | |
361 | struct page *page = radix_tree_deref_slot_protected(slot, | |
362 | &mapping->tree_lock); | |
363 | if (likely(page) && PageDirty(page)) { | |
364 | __dec_wb_stat(old_wb, WB_RECLAIMABLE); | |
365 | __inc_wb_stat(new_wb, WB_RECLAIMABLE); | |
366 | } | |
367 | } | |
368 | ||
369 | radix_tree_for_each_tagged(slot, &mapping->page_tree, &iter, 0, | |
370 | PAGECACHE_TAG_WRITEBACK) { | |
371 | struct page *page = radix_tree_deref_slot_protected(slot, | |
372 | &mapping->tree_lock); | |
373 | if (likely(page)) { | |
374 | WARN_ON_ONCE(!PageWriteback(page)); | |
375 | __dec_wb_stat(old_wb, WB_WRITEBACK); | |
376 | __inc_wb_stat(new_wb, WB_WRITEBACK); | |
377 | } | |
378 | } | |
379 | ||
380 | wb_get(new_wb); | |
381 | ||
382 | /* | |
383 | * Transfer to @new_wb's IO list if necessary. The specific list | |
384 | * @inode was on is ignored and the inode is put on ->b_dirty which | |
385 | * is always correct including from ->b_dirty_time. The transfer | |
386 | * preserves @inode->dirtied_when ordering. | |
387 | */ | |
c7f54084 | 388 | if (!list_empty(&inode->i_io_list)) { |
d10c8095 TH |
389 | struct inode *pos; |
390 | ||
c7f54084 | 391 | inode_io_list_del_locked(inode, old_wb); |
d10c8095 | 392 | inode->i_wb = new_wb; |
c7f54084 | 393 | list_for_each_entry(pos, &new_wb->b_dirty, i_io_list) |
d10c8095 TH |
394 | if (time_after_eq(inode->dirtied_when, |
395 | pos->dirtied_when)) | |
396 | break; | |
c7f54084 | 397 | inode_io_list_move_locked(inode, new_wb, pos->i_io_list.prev); |
d10c8095 TH |
398 | } else { |
399 | inode->i_wb = new_wb; | |
400 | } | |
682aa8e1 | 401 | |
d10c8095 | 402 | /* ->i_wb_frn updates may race wbc_detach_inode() but doesn't matter */ |
682aa8e1 TH |
403 | inode->i_wb_frn_winner = 0; |
404 | inode->i_wb_frn_avg_time = 0; | |
405 | inode->i_wb_frn_history = 0; | |
d10c8095 TH |
406 | switched = true; |
407 | skip_switch: | |
682aa8e1 TH |
408 | /* |
409 | * Paired with load_acquire in unlocked_inode_to_wb_begin() and | |
410 | * ensures that the new wb is visible if they see !I_WB_SWITCH. | |
411 | */ | |
412 | smp_store_release(&inode->i_state, inode->i_state & ~I_WB_SWITCH); | |
413 | ||
d10c8095 | 414 | spin_unlock_irq(&mapping->tree_lock); |
682aa8e1 | 415 | spin_unlock(&inode->i_lock); |
d10c8095 TH |
416 | spin_unlock(&new_wb->list_lock); |
417 | spin_unlock(&old_wb->list_lock); | |
682aa8e1 | 418 | |
d10c8095 TH |
419 | if (switched) { |
420 | wb_wakeup(new_wb); | |
421 | wb_put(old_wb); | |
422 | } | |
682aa8e1 | 423 | wb_put(new_wb); |
d10c8095 TH |
424 | |
425 | iput(inode); | |
682aa8e1 TH |
426 | kfree(isw); |
427 | } | |
428 | ||
429 | static void inode_switch_wbs_rcu_fn(struct rcu_head *rcu_head) | |
430 | { | |
431 | struct inode_switch_wbs_context *isw = container_of(rcu_head, | |
432 | struct inode_switch_wbs_context, rcu_head); | |
433 | ||
434 | /* needs to grab bh-unsafe locks, bounce to work item */ | |
435 | INIT_WORK(&isw->work, inode_switch_wbs_work_fn); | |
436 | schedule_work(&isw->work); | |
437 | } | |
438 | ||
439 | /** | |
440 | * inode_switch_wbs - change the wb association of an inode | |
441 | * @inode: target inode | |
442 | * @new_wb_id: ID of the new wb | |
443 | * | |
444 | * Switch @inode's wb association to the wb identified by @new_wb_id. The | |
445 | * switching is performed asynchronously and may fail silently. | |
446 | */ | |
447 | static void inode_switch_wbs(struct inode *inode, int new_wb_id) | |
448 | { | |
449 | struct backing_dev_info *bdi = inode_to_bdi(inode); | |
450 | struct cgroup_subsys_state *memcg_css; | |
451 | struct inode_switch_wbs_context *isw; | |
452 | ||
453 | /* noop if seems to be already in progress */ | |
454 | if (inode->i_state & I_WB_SWITCH) | |
455 | return; | |
456 | ||
457 | isw = kzalloc(sizeof(*isw), GFP_ATOMIC); | |
458 | if (!isw) | |
459 | return; | |
460 | ||
461 | /* find and pin the new wb */ | |
462 | rcu_read_lock(); | |
463 | memcg_css = css_from_id(new_wb_id, &memory_cgrp_subsys); | |
464 | if (memcg_css) | |
465 | isw->new_wb = wb_get_create(bdi, memcg_css, GFP_ATOMIC); | |
466 | rcu_read_unlock(); | |
467 | if (!isw->new_wb) | |
468 | goto out_free; | |
469 | ||
470 | /* while holding I_WB_SWITCH, no one else can update the association */ | |
471 | spin_lock(&inode->i_lock); | |
472 | if (inode->i_state & (I_WB_SWITCH | I_FREEING) || | |
473 | inode_to_wb(inode) == isw->new_wb) { | |
474 | spin_unlock(&inode->i_lock); | |
475 | goto out_free; | |
476 | } | |
477 | inode->i_state |= I_WB_SWITCH; | |
478 | spin_unlock(&inode->i_lock); | |
479 | ||
480 | ihold(inode); | |
481 | isw->inode = inode; | |
482 | ||
483 | /* | |
484 | * In addition to synchronizing among switchers, I_WB_SWITCH tells | |
485 | * the RCU protected stat update paths to grab the mapping's | |
486 | * tree_lock so that stat transfer can synchronize against them. | |
487 | * Let's continue after I_WB_SWITCH is guaranteed to be visible. | |
488 | */ | |
489 | call_rcu(&isw->rcu_head, inode_switch_wbs_rcu_fn); | |
490 | return; | |
491 | ||
492 | out_free: | |
493 | if (isw->new_wb) | |
494 | wb_put(isw->new_wb); | |
495 | kfree(isw); | |
496 | } | |
497 | ||
b16b1deb TH |
498 | /** |
499 | * wbc_attach_and_unlock_inode - associate wbc with target inode and unlock it | |
500 | * @wbc: writeback_control of interest | |
501 | * @inode: target inode | |
502 | * | |
503 | * @inode is locked and about to be written back under the control of @wbc. | |
504 | * Record @inode's writeback context into @wbc and unlock the i_lock. On | |
505 | * writeback completion, wbc_detach_inode() should be called. This is used | |
506 | * to track the cgroup writeback context. | |
507 | */ | |
508 | void wbc_attach_and_unlock_inode(struct writeback_control *wbc, | |
509 | struct inode *inode) | |
510 | { | |
dd73e4b7 TH |
511 | if (!inode_cgwb_enabled(inode)) { |
512 | spin_unlock(&inode->i_lock); | |
513 | return; | |
514 | } | |
515 | ||
b16b1deb | 516 | wbc->wb = inode_to_wb(inode); |
2a814908 TH |
517 | wbc->inode = inode; |
518 | ||
519 | wbc->wb_id = wbc->wb->memcg_css->id; | |
520 | wbc->wb_lcand_id = inode->i_wb_frn_winner; | |
521 | wbc->wb_tcand_id = 0; | |
522 | wbc->wb_bytes = 0; | |
523 | wbc->wb_lcand_bytes = 0; | |
524 | wbc->wb_tcand_bytes = 0; | |
525 | ||
b16b1deb TH |
526 | wb_get(wbc->wb); |
527 | spin_unlock(&inode->i_lock); | |
e8a7abf5 TH |
528 | |
529 | /* | |
530 | * A dying wb indicates that the memcg-blkcg mapping has changed | |
531 | * and a new wb is already serving the memcg. Switch immediately. | |
532 | */ | |
533 | if (unlikely(wb_dying(wbc->wb))) | |
534 | inode_switch_wbs(inode, wbc->wb_id); | |
b16b1deb TH |
535 | } |
536 | ||
537 | /** | |
2a814908 TH |
538 | * wbc_detach_inode - disassociate wbc from inode and perform foreign detection |
539 | * @wbc: writeback_control of the just finished writeback | |
b16b1deb TH |
540 | * |
541 | * To be called after a writeback attempt of an inode finishes and undoes | |
542 | * wbc_attach_and_unlock_inode(). Can be called under any context. | |
2a814908 TH |
543 | * |
544 | * As concurrent write sharing of an inode is expected to be very rare and | |
545 | * memcg only tracks page ownership on first-use basis severely confining | |
546 | * the usefulness of such sharing, cgroup writeback tracks ownership | |
547 | * per-inode. While the support for concurrent write sharing of an inode | |
548 | * is deemed unnecessary, an inode being written to by different cgroups at | |
549 | * different points in time is a lot more common, and, more importantly, | |
550 | * charging only by first-use can too readily lead to grossly incorrect | |
551 | * behaviors (single foreign page can lead to gigabytes of writeback to be | |
552 | * incorrectly attributed). | |
553 | * | |
554 | * To resolve this issue, cgroup writeback detects the majority dirtier of | |
555 | * an inode and transfers the ownership to it. To avoid unnnecessary | |
556 | * oscillation, the detection mechanism keeps track of history and gives | |
557 | * out the switch verdict only if the foreign usage pattern is stable over | |
558 | * a certain amount of time and/or writeback attempts. | |
559 | * | |
560 | * On each writeback attempt, @wbc tries to detect the majority writer | |
561 | * using Boyer-Moore majority vote algorithm. In addition to the byte | |
562 | * count from the majority voting, it also counts the bytes written for the | |
563 | * current wb and the last round's winner wb (max of last round's current | |
564 | * wb, the winner from two rounds ago, and the last round's majority | |
565 | * candidate). Keeping track of the historical winner helps the algorithm | |
566 | * to semi-reliably detect the most active writer even when it's not the | |
567 | * absolute majority. | |
568 | * | |
569 | * Once the winner of the round is determined, whether the winner is | |
570 | * foreign or not and how much IO time the round consumed is recorded in | |
571 | * inode->i_wb_frn_history. If the amount of recorded foreign IO time is | |
572 | * over a certain threshold, the switch verdict is given. | |
b16b1deb TH |
573 | */ |
574 | void wbc_detach_inode(struct writeback_control *wbc) | |
575 | { | |
2a814908 TH |
576 | struct bdi_writeback *wb = wbc->wb; |
577 | struct inode *inode = wbc->inode; | |
dd73e4b7 TH |
578 | unsigned long avg_time, max_bytes, max_time; |
579 | u16 history; | |
2a814908 TH |
580 | int max_id; |
581 | ||
dd73e4b7 TH |
582 | if (!wb) |
583 | return; | |
584 | ||
585 | history = inode->i_wb_frn_history; | |
586 | avg_time = inode->i_wb_frn_avg_time; | |
587 | ||
2a814908 TH |
588 | /* pick the winner of this round */ |
589 | if (wbc->wb_bytes >= wbc->wb_lcand_bytes && | |
590 | wbc->wb_bytes >= wbc->wb_tcand_bytes) { | |
591 | max_id = wbc->wb_id; | |
592 | max_bytes = wbc->wb_bytes; | |
593 | } else if (wbc->wb_lcand_bytes >= wbc->wb_tcand_bytes) { | |
594 | max_id = wbc->wb_lcand_id; | |
595 | max_bytes = wbc->wb_lcand_bytes; | |
596 | } else { | |
597 | max_id = wbc->wb_tcand_id; | |
598 | max_bytes = wbc->wb_tcand_bytes; | |
599 | } | |
600 | ||
601 | /* | |
602 | * Calculate the amount of IO time the winner consumed and fold it | |
603 | * into the running average kept per inode. If the consumed IO | |
604 | * time is lower than avag / WB_FRN_TIME_CUT_DIV, ignore it for | |
605 | * deciding whether to switch or not. This is to prevent one-off | |
606 | * small dirtiers from skewing the verdict. | |
607 | */ | |
608 | max_time = DIV_ROUND_UP((max_bytes >> PAGE_SHIFT) << WB_FRN_TIME_SHIFT, | |
609 | wb->avg_write_bandwidth); | |
610 | if (avg_time) | |
611 | avg_time += (max_time >> WB_FRN_TIME_AVG_SHIFT) - | |
612 | (avg_time >> WB_FRN_TIME_AVG_SHIFT); | |
613 | else | |
614 | avg_time = max_time; /* immediate catch up on first run */ | |
615 | ||
616 | if (max_time >= avg_time / WB_FRN_TIME_CUT_DIV) { | |
617 | int slots; | |
618 | ||
619 | /* | |
620 | * The switch verdict is reached if foreign wb's consume | |
621 | * more than a certain proportion of IO time in a | |
622 | * WB_FRN_TIME_PERIOD. This is loosely tracked by 16 slot | |
623 | * history mask where each bit represents one sixteenth of | |
624 | * the period. Determine the number of slots to shift into | |
625 | * history from @max_time. | |
626 | */ | |
627 | slots = min(DIV_ROUND_UP(max_time, WB_FRN_HIST_UNIT), | |
628 | (unsigned long)WB_FRN_HIST_MAX_SLOTS); | |
629 | history <<= slots; | |
630 | if (wbc->wb_id != max_id) | |
631 | history |= (1U << slots) - 1; | |
632 | ||
633 | /* | |
634 | * Switch if the current wb isn't the consistent winner. | |
635 | * If there are multiple closely competing dirtiers, the | |
636 | * inode may switch across them repeatedly over time, which | |
637 | * is okay. The main goal is avoiding keeping an inode on | |
638 | * the wrong wb for an extended period of time. | |
639 | */ | |
682aa8e1 TH |
640 | if (hweight32(history) > WB_FRN_HIST_THR_SLOTS) |
641 | inode_switch_wbs(inode, max_id); | |
2a814908 TH |
642 | } |
643 | ||
644 | /* | |
645 | * Multiple instances of this function may race to update the | |
646 | * following fields but we don't mind occassional inaccuracies. | |
647 | */ | |
648 | inode->i_wb_frn_winner = max_id; | |
649 | inode->i_wb_frn_avg_time = min(avg_time, (unsigned long)U16_MAX); | |
650 | inode->i_wb_frn_history = history; | |
651 | ||
b16b1deb TH |
652 | wb_put(wbc->wb); |
653 | wbc->wb = NULL; | |
654 | } | |
655 | ||
2a814908 TH |
656 | /** |
657 | * wbc_account_io - account IO issued during writeback | |
658 | * @wbc: writeback_control of the writeback in progress | |
659 | * @page: page being written out | |
660 | * @bytes: number of bytes being written out | |
661 | * | |
662 | * @bytes from @page are about to written out during the writeback | |
663 | * controlled by @wbc. Keep the book for foreign inode detection. See | |
664 | * wbc_detach_inode(). | |
665 | */ | |
666 | void wbc_account_io(struct writeback_control *wbc, struct page *page, | |
667 | size_t bytes) | |
668 | { | |
669 | int id; | |
670 | ||
671 | /* | |
672 | * pageout() path doesn't attach @wbc to the inode being written | |
673 | * out. This is intentional as we don't want the function to block | |
674 | * behind a slow cgroup. Ultimately, we want pageout() to kick off | |
675 | * regular writeback instead of writing things out itself. | |
676 | */ | |
677 | if (!wbc->wb) | |
678 | return; | |
679 | ||
680 | rcu_read_lock(); | |
681 | id = mem_cgroup_css_from_page(page)->id; | |
682 | rcu_read_unlock(); | |
683 | ||
684 | if (id == wbc->wb_id) { | |
685 | wbc->wb_bytes += bytes; | |
686 | return; | |
687 | } | |
688 | ||
689 | if (id == wbc->wb_lcand_id) | |
690 | wbc->wb_lcand_bytes += bytes; | |
691 | ||
692 | /* Boyer-Moore majority vote algorithm */ | |
693 | if (!wbc->wb_tcand_bytes) | |
694 | wbc->wb_tcand_id = id; | |
695 | if (id == wbc->wb_tcand_id) | |
696 | wbc->wb_tcand_bytes += bytes; | |
697 | else | |
698 | wbc->wb_tcand_bytes -= min(bytes, wbc->wb_tcand_bytes); | |
699 | } | |
5aa2a96b | 700 | EXPORT_SYMBOL_GPL(wbc_account_io); |
2a814908 | 701 | |
703c2708 TH |
702 | /** |
703 | * inode_congested - test whether an inode is congested | |
60292bcc | 704 | * @inode: inode to test for congestion (may be NULL) |
703c2708 TH |
705 | * @cong_bits: mask of WB_[a]sync_congested bits to test |
706 | * | |
707 | * Tests whether @inode is congested. @cong_bits is the mask of congestion | |
708 | * bits to test and the return value is the mask of set bits. | |
709 | * | |
710 | * If cgroup writeback is enabled for @inode, the congestion state is | |
711 | * determined by whether the cgwb (cgroup bdi_writeback) for the blkcg | |
712 | * associated with @inode is congested; otherwise, the root wb's congestion | |
713 | * state is used. | |
60292bcc TH |
714 | * |
715 | * @inode is allowed to be NULL as this function is often called on | |
716 | * mapping->host which is NULL for the swapper space. | |
703c2708 TH |
717 | */ |
718 | int inode_congested(struct inode *inode, int cong_bits) | |
719 | { | |
5cb8b824 TH |
720 | /* |
721 | * Once set, ->i_wb never becomes NULL while the inode is alive. | |
722 | * Start transaction iff ->i_wb is visible. | |
723 | */ | |
aaa2cacf | 724 | if (inode && inode_to_wb_is_valid(inode)) { |
5cb8b824 TH |
725 | struct bdi_writeback *wb; |
726 | bool locked, congested; | |
727 | ||
728 | wb = unlocked_inode_to_wb_begin(inode, &locked); | |
729 | congested = wb_congested(wb, cong_bits); | |
730 | unlocked_inode_to_wb_end(inode, locked); | |
731 | return congested; | |
703c2708 TH |
732 | } |
733 | ||
734 | return wb_congested(&inode_to_bdi(inode)->wb, cong_bits); | |
735 | } | |
736 | EXPORT_SYMBOL_GPL(inode_congested); | |
737 | ||
f2b65121 TH |
738 | /** |
739 | * wb_split_bdi_pages - split nr_pages to write according to bandwidth | |
740 | * @wb: target bdi_writeback to split @nr_pages to | |
741 | * @nr_pages: number of pages to write for the whole bdi | |
742 | * | |
743 | * Split @wb's portion of @nr_pages according to @wb's write bandwidth in | |
744 | * relation to the total write bandwidth of all wb's w/ dirty inodes on | |
745 | * @wb->bdi. | |
746 | */ | |
747 | static long wb_split_bdi_pages(struct bdi_writeback *wb, long nr_pages) | |
748 | { | |
749 | unsigned long this_bw = wb->avg_write_bandwidth; | |
750 | unsigned long tot_bw = atomic_long_read(&wb->bdi->tot_write_bandwidth); | |
751 | ||
752 | if (nr_pages == LONG_MAX) | |
753 | return LONG_MAX; | |
754 | ||
755 | /* | |
756 | * This may be called on clean wb's and proportional distribution | |
757 | * may not make sense, just use the original @nr_pages in those | |
758 | * cases. In general, we wanna err on the side of writing more. | |
759 | */ | |
760 | if (!tot_bw || this_bw >= tot_bw) | |
761 | return nr_pages; | |
762 | else | |
763 | return DIV_ROUND_UP_ULL((u64)nr_pages * this_bw, tot_bw); | |
764 | } | |
765 | ||
db125360 TH |
766 | /** |
767 | * bdi_split_work_to_wbs - split a wb_writeback_work to all wb's of a bdi | |
768 | * @bdi: target backing_dev_info | |
769 | * @base_work: wb_writeback_work to issue | |
770 | * @skip_if_busy: skip wb's which already have writeback in progress | |
771 | * | |
772 | * Split and issue @base_work to all wb's (bdi_writeback's) of @bdi which | |
773 | * have dirty inodes. If @base_work->nr_page isn't %LONG_MAX, it's | |
774 | * distributed to the busy wbs according to each wb's proportion in the | |
775 | * total active write bandwidth of @bdi. | |
776 | */ | |
777 | static void bdi_split_work_to_wbs(struct backing_dev_info *bdi, | |
778 | struct wb_writeback_work *base_work, | |
779 | bool skip_if_busy) | |
780 | { | |
1ed8d48c | 781 | int next_memcg_id = 0; |
db125360 TH |
782 | struct bdi_writeback *wb; |
783 | struct wb_iter iter; | |
784 | ||
785 | might_sleep(); | |
db125360 TH |
786 | restart: |
787 | rcu_read_lock(); | |
1ed8d48c | 788 | bdi_for_each_wb(wb, bdi, &iter, next_memcg_id) { |
8a1270cd TH |
789 | DEFINE_WB_COMPLETION_ONSTACK(fallback_work_done); |
790 | struct wb_writeback_work fallback_work; | |
791 | struct wb_writeback_work *work; | |
792 | long nr_pages; | |
793 | ||
006a0973 TH |
794 | /* SYNC_ALL writes out I_DIRTY_TIME too */ |
795 | if (!wb_has_dirty_io(wb) && | |
796 | (base_work->sync_mode == WB_SYNC_NONE || | |
797 | list_empty(&wb->b_dirty_time))) | |
798 | continue; | |
799 | if (skip_if_busy && writeback_in_progress(wb)) | |
db125360 TH |
800 | continue; |
801 | ||
8a1270cd TH |
802 | nr_pages = wb_split_bdi_pages(wb, base_work->nr_pages); |
803 | ||
804 | work = kmalloc(sizeof(*work), GFP_ATOMIC); | |
805 | if (work) { | |
806 | *work = *base_work; | |
807 | work->nr_pages = nr_pages; | |
808 | work->auto_free = 1; | |
809 | wb_queue_work(wb, work); | |
810 | continue; | |
db125360 | 811 | } |
8a1270cd TH |
812 | |
813 | /* alloc failed, execute synchronously using on-stack fallback */ | |
814 | work = &fallback_work; | |
815 | *work = *base_work; | |
816 | work->nr_pages = nr_pages; | |
817 | work->auto_free = 0; | |
818 | work->done = &fallback_work_done; | |
819 | ||
820 | wb_queue_work(wb, work); | |
821 | ||
822 | next_memcg_id = wb->memcg_css->id + 1; | |
823 | rcu_read_unlock(); | |
824 | wb_wait_for_completion(bdi, &fallback_work_done); | |
825 | goto restart; | |
db125360 TH |
826 | } |
827 | rcu_read_unlock(); | |
828 | } | |
829 | ||
f2b65121 TH |
830 | #else /* CONFIG_CGROUP_WRITEBACK */ |
831 | ||
87e1d789 TH |
832 | static struct bdi_writeback * |
833 | locked_inode_to_wb_and_lock_list(struct inode *inode) | |
834 | __releases(&inode->i_lock) | |
835 | __acquires(&wb->list_lock) | |
836 | { | |
837 | struct bdi_writeback *wb = inode_to_wb(inode); | |
838 | ||
839 | spin_unlock(&inode->i_lock); | |
840 | spin_lock(&wb->list_lock); | |
841 | return wb; | |
842 | } | |
843 | ||
844 | static struct bdi_writeback *inode_to_wb_and_lock_list(struct inode *inode) | |
845 | __acquires(&wb->list_lock) | |
846 | { | |
847 | struct bdi_writeback *wb = inode_to_wb(inode); | |
848 | ||
849 | spin_lock(&wb->list_lock); | |
850 | return wb; | |
851 | } | |
852 | ||
f2b65121 TH |
853 | static long wb_split_bdi_pages(struct bdi_writeback *wb, long nr_pages) |
854 | { | |
855 | return nr_pages; | |
856 | } | |
857 | ||
db125360 TH |
858 | static void bdi_split_work_to_wbs(struct backing_dev_info *bdi, |
859 | struct wb_writeback_work *base_work, | |
860 | bool skip_if_busy) | |
861 | { | |
862 | might_sleep(); | |
863 | ||
006a0973 | 864 | if (!skip_if_busy || !writeback_in_progress(&bdi->wb)) { |
db125360 | 865 | base_work->auto_free = 0; |
db125360 TH |
866 | wb_queue_work(&bdi->wb, base_work); |
867 | } | |
868 | } | |
869 | ||
703c2708 TH |
870 | #endif /* CONFIG_CGROUP_WRITEBACK */ |
871 | ||
c00ddad3 TH |
872 | void wb_start_writeback(struct bdi_writeback *wb, long nr_pages, |
873 | bool range_cyclic, enum wb_reason reason) | |
b6e51316 | 874 | { |
c00ddad3 TH |
875 | struct wb_writeback_work *work; |
876 | ||
877 | if (!wb_has_dirty_io(wb)) | |
878 | return; | |
879 | ||
880 | /* | |
881 | * This is WB_SYNC_NONE writeback, so if allocation fails just | |
882 | * wakeup the thread for old dirty data writeback | |
883 | */ | |
884 | work = kzalloc(sizeof(*work), GFP_ATOMIC); | |
885 | if (!work) { | |
5634cc2a | 886 | trace_writeback_nowork(wb); |
c00ddad3 TH |
887 | wb_wakeup(wb); |
888 | return; | |
889 | } | |
890 | ||
891 | work->sync_mode = WB_SYNC_NONE; | |
892 | work->nr_pages = nr_pages; | |
893 | work->range_cyclic = range_cyclic; | |
894 | work->reason = reason; | |
ac7b19a3 | 895 | work->auto_free = 1; |
c00ddad3 TH |
896 | |
897 | wb_queue_work(wb, work); | |
c5444198 | 898 | } |
d3ddec76 | 899 | |
c5444198 | 900 | /** |
9ecf4866 TH |
901 | * wb_start_background_writeback - start background writeback |
902 | * @wb: bdi_writback to write from | |
c5444198 CH |
903 | * |
904 | * Description: | |
6585027a | 905 | * This makes sure WB_SYNC_NONE background writeback happens. When |
9ecf4866 | 906 | * this function returns, it is only guaranteed that for given wb |
6585027a JK |
907 | * some IO is happening if we are over background dirty threshold. |
908 | * Caller need not hold sb s_umount semaphore. | |
c5444198 | 909 | */ |
9ecf4866 | 910 | void wb_start_background_writeback(struct bdi_writeback *wb) |
c5444198 | 911 | { |
6585027a JK |
912 | /* |
913 | * We just wake up the flusher thread. It will perform background | |
914 | * writeback as soon as there is no other work to do. | |
915 | */ | |
5634cc2a | 916 | trace_writeback_wake_background(wb); |
9ecf4866 | 917 | wb_wakeup(wb); |
1da177e4 LT |
918 | } |
919 | ||
a66979ab DC |
920 | /* |
921 | * Remove the inode from the writeback list it is on. | |
922 | */ | |
c7f54084 | 923 | void inode_io_list_del(struct inode *inode) |
a66979ab | 924 | { |
87e1d789 | 925 | struct bdi_writeback *wb; |
f758eeab | 926 | |
87e1d789 | 927 | wb = inode_to_wb_and_lock_list(inode); |
c7f54084 | 928 | inode_io_list_del_locked(inode, wb); |
52ebea74 | 929 | spin_unlock(&wb->list_lock); |
a66979ab DC |
930 | } |
931 | ||
6610a0bc AM |
932 | /* |
933 | * Redirty an inode: set its when-it-was dirtied timestamp and move it to the | |
934 | * furthest end of its superblock's dirty-inode list. | |
935 | * | |
936 | * Before stamping the inode's ->dirtied_when, we check to see whether it is | |
66f3b8e2 | 937 | * already the most-recently-dirtied inode on the b_dirty list. If that is |
6610a0bc AM |
938 | * the case then the inode must have been redirtied while it was being written |
939 | * out and we don't reset its dirtied_when. | |
940 | */ | |
f758eeab | 941 | static void redirty_tail(struct inode *inode, struct bdi_writeback *wb) |
6610a0bc | 942 | { |
03ba3782 | 943 | if (!list_empty(&wb->b_dirty)) { |
66f3b8e2 | 944 | struct inode *tail; |
6610a0bc | 945 | |
7ccf19a8 | 946 | tail = wb_inode(wb->b_dirty.next); |
66f3b8e2 | 947 | if (time_before(inode->dirtied_when, tail->dirtied_when)) |
6610a0bc AM |
948 | inode->dirtied_when = jiffies; |
949 | } | |
c7f54084 | 950 | inode_io_list_move_locked(inode, wb, &wb->b_dirty); |
6610a0bc AM |
951 | } |
952 | ||
c986d1e2 | 953 | /* |
66f3b8e2 | 954 | * requeue inode for re-scanning after bdi->b_io list is exhausted. |
c986d1e2 | 955 | */ |
f758eeab | 956 | static void requeue_io(struct inode *inode, struct bdi_writeback *wb) |
c986d1e2 | 957 | { |
c7f54084 | 958 | inode_io_list_move_locked(inode, wb, &wb->b_more_io); |
c986d1e2 AM |
959 | } |
960 | ||
1c0eeaf5 JE |
961 | static void inode_sync_complete(struct inode *inode) |
962 | { | |
365b94ae | 963 | inode->i_state &= ~I_SYNC; |
4eff96dd JK |
964 | /* If inode is clean an unused, put it into LRU now... */ |
965 | inode_add_lru(inode); | |
365b94ae | 966 | /* Waiters must see I_SYNC cleared before being woken up */ |
1c0eeaf5 JE |
967 | smp_mb(); |
968 | wake_up_bit(&inode->i_state, __I_SYNC); | |
969 | } | |
970 | ||
d2caa3c5 JL |
971 | static bool inode_dirtied_after(struct inode *inode, unsigned long t) |
972 | { | |
973 | bool ret = time_after(inode->dirtied_when, t); | |
974 | #ifndef CONFIG_64BIT | |
975 | /* | |
976 | * For inodes being constantly redirtied, dirtied_when can get stuck. | |
977 | * It _appears_ to be in the future, but is actually in distant past. | |
978 | * This test is necessary to prevent such wrapped-around relative times | |
5b0830cb | 979 | * from permanently stopping the whole bdi writeback. |
d2caa3c5 JL |
980 | */ |
981 | ret = ret && time_before_eq(inode->dirtied_when, jiffies); | |
982 | #endif | |
983 | return ret; | |
984 | } | |
985 | ||
0ae45f63 TT |
986 | #define EXPIRE_DIRTY_ATIME 0x0001 |
987 | ||
2c136579 | 988 | /* |
0e2f2b23 | 989 | * Move expired (dirtied before work->older_than_this) dirty inodes from |
697e6fed | 990 | * @delaying_queue to @dispatch_queue. |
2c136579 | 991 | */ |
e84d0a4f | 992 | static int move_expired_inodes(struct list_head *delaying_queue, |
2c136579 | 993 | struct list_head *dispatch_queue, |
0ae45f63 | 994 | int flags, |
ad4e38dd | 995 | struct wb_writeback_work *work) |
2c136579 | 996 | { |
0ae45f63 TT |
997 | unsigned long *older_than_this = NULL; |
998 | unsigned long expire_time; | |
5c03449d SL |
999 | LIST_HEAD(tmp); |
1000 | struct list_head *pos, *node; | |
cf137307 | 1001 | struct super_block *sb = NULL; |
5c03449d | 1002 | struct inode *inode; |
cf137307 | 1003 | int do_sb_sort = 0; |
e84d0a4f | 1004 | int moved = 0; |
5c03449d | 1005 | |
0ae45f63 TT |
1006 | if ((flags & EXPIRE_DIRTY_ATIME) == 0) |
1007 | older_than_this = work->older_than_this; | |
a2f48706 TT |
1008 | else if (!work->for_sync) { |
1009 | expire_time = jiffies - (dirtytime_expire_interval * HZ); | |
0ae45f63 TT |
1010 | older_than_this = &expire_time; |
1011 | } | |
2c136579 | 1012 | while (!list_empty(delaying_queue)) { |
7ccf19a8 | 1013 | inode = wb_inode(delaying_queue->prev); |
0ae45f63 TT |
1014 | if (older_than_this && |
1015 | inode_dirtied_after(inode, *older_than_this)) | |
2c136579 | 1016 | break; |
c7f54084 | 1017 | list_move(&inode->i_io_list, &tmp); |
a8855990 | 1018 | moved++; |
0ae45f63 TT |
1019 | if (flags & EXPIRE_DIRTY_ATIME) |
1020 | set_bit(__I_DIRTY_TIME_EXPIRED, &inode->i_state); | |
a8855990 JK |
1021 | if (sb_is_blkdev_sb(inode->i_sb)) |
1022 | continue; | |
cf137307 JA |
1023 | if (sb && sb != inode->i_sb) |
1024 | do_sb_sort = 1; | |
1025 | sb = inode->i_sb; | |
5c03449d SL |
1026 | } |
1027 | ||
cf137307 JA |
1028 | /* just one sb in list, splice to dispatch_queue and we're done */ |
1029 | if (!do_sb_sort) { | |
1030 | list_splice(&tmp, dispatch_queue); | |
e84d0a4f | 1031 | goto out; |
cf137307 JA |
1032 | } |
1033 | ||
5c03449d SL |
1034 | /* Move inodes from one superblock together */ |
1035 | while (!list_empty(&tmp)) { | |
7ccf19a8 | 1036 | sb = wb_inode(tmp.prev)->i_sb; |
5c03449d | 1037 | list_for_each_prev_safe(pos, node, &tmp) { |
7ccf19a8 | 1038 | inode = wb_inode(pos); |
5c03449d | 1039 | if (inode->i_sb == sb) |
c7f54084 | 1040 | list_move(&inode->i_io_list, dispatch_queue); |
5c03449d | 1041 | } |
2c136579 | 1042 | } |
e84d0a4f WF |
1043 | out: |
1044 | return moved; | |
2c136579 FW |
1045 | } |
1046 | ||
1047 | /* | |
1048 | * Queue all expired dirty inodes for io, eldest first. | |
4ea879b9 WF |
1049 | * Before |
1050 | * newly dirtied b_dirty b_io b_more_io | |
1051 | * =============> gf edc BA | |
1052 | * After | |
1053 | * newly dirtied b_dirty b_io b_more_io | |
1054 | * =============> g fBAedc | |
1055 | * | | |
1056 | * +--> dequeue for IO | |
2c136579 | 1057 | */ |
ad4e38dd | 1058 | static void queue_io(struct bdi_writeback *wb, struct wb_writeback_work *work) |
66f3b8e2 | 1059 | { |
e84d0a4f | 1060 | int moved; |
0ae45f63 | 1061 | |
f758eeab | 1062 | assert_spin_locked(&wb->list_lock); |
4ea879b9 | 1063 | list_splice_init(&wb->b_more_io, &wb->b_io); |
0ae45f63 TT |
1064 | moved = move_expired_inodes(&wb->b_dirty, &wb->b_io, 0, work); |
1065 | moved += move_expired_inodes(&wb->b_dirty_time, &wb->b_io, | |
1066 | EXPIRE_DIRTY_ATIME, work); | |
d6c10f1f TH |
1067 | if (moved) |
1068 | wb_io_lists_populated(wb); | |
ad4e38dd | 1069 | trace_writeback_queue_io(wb, work, moved); |
66f3b8e2 JA |
1070 | } |
1071 | ||
a9185b41 | 1072 | static int write_inode(struct inode *inode, struct writeback_control *wbc) |
08d8e974 | 1073 | { |
9fb0a7da TH |
1074 | int ret; |
1075 | ||
1076 | if (inode->i_sb->s_op->write_inode && !is_bad_inode(inode)) { | |
1077 | trace_writeback_write_inode_start(inode, wbc); | |
1078 | ret = inode->i_sb->s_op->write_inode(inode, wbc); | |
1079 | trace_writeback_write_inode(inode, wbc); | |
1080 | return ret; | |
1081 | } | |
03ba3782 | 1082 | return 0; |
08d8e974 | 1083 | } |
08d8e974 | 1084 | |
1da177e4 | 1085 | /* |
169ebd90 JK |
1086 | * Wait for writeback on an inode to complete. Called with i_lock held. |
1087 | * Caller must make sure inode cannot go away when we drop i_lock. | |
01c03194 | 1088 | */ |
169ebd90 JK |
1089 | static void __inode_wait_for_writeback(struct inode *inode) |
1090 | __releases(inode->i_lock) | |
1091 | __acquires(inode->i_lock) | |
01c03194 CH |
1092 | { |
1093 | DEFINE_WAIT_BIT(wq, &inode->i_state, __I_SYNC); | |
1094 | wait_queue_head_t *wqh; | |
1095 | ||
1096 | wqh = bit_waitqueue(&inode->i_state, __I_SYNC); | |
250df6ed DC |
1097 | while (inode->i_state & I_SYNC) { |
1098 | spin_unlock(&inode->i_lock); | |
74316201 N |
1099 | __wait_on_bit(wqh, &wq, bit_wait, |
1100 | TASK_UNINTERRUPTIBLE); | |
250df6ed | 1101 | spin_lock(&inode->i_lock); |
58a9d3d8 | 1102 | } |
01c03194 CH |
1103 | } |
1104 | ||
169ebd90 JK |
1105 | /* |
1106 | * Wait for writeback on an inode to complete. Caller must have inode pinned. | |
1107 | */ | |
1108 | void inode_wait_for_writeback(struct inode *inode) | |
1109 | { | |
1110 | spin_lock(&inode->i_lock); | |
1111 | __inode_wait_for_writeback(inode); | |
1112 | spin_unlock(&inode->i_lock); | |
1113 | } | |
1114 | ||
1115 | /* | |
1116 | * Sleep until I_SYNC is cleared. This function must be called with i_lock | |
1117 | * held and drops it. It is aimed for callers not holding any inode reference | |
1118 | * so once i_lock is dropped, inode can go away. | |
1119 | */ | |
1120 | static void inode_sleep_on_writeback(struct inode *inode) | |
1121 | __releases(inode->i_lock) | |
1122 | { | |
1123 | DEFINE_WAIT(wait); | |
1124 | wait_queue_head_t *wqh = bit_waitqueue(&inode->i_state, __I_SYNC); | |
1125 | int sleep; | |
1126 | ||
1127 | prepare_to_wait(wqh, &wait, TASK_UNINTERRUPTIBLE); | |
1128 | sleep = inode->i_state & I_SYNC; | |
1129 | spin_unlock(&inode->i_lock); | |
1130 | if (sleep) | |
1131 | schedule(); | |
1132 | finish_wait(wqh, &wait); | |
1133 | } | |
1134 | ||
ccb26b5a JK |
1135 | /* |
1136 | * Find proper writeback list for the inode depending on its current state and | |
1137 | * possibly also change of its state while we were doing writeback. Here we | |
1138 | * handle things such as livelock prevention or fairness of writeback among | |
1139 | * inodes. This function can be called only by flusher thread - noone else | |
1140 | * processes all inodes in writeback lists and requeueing inodes behind flusher | |
1141 | * thread's back can have unexpected consequences. | |
1142 | */ | |
1143 | static void requeue_inode(struct inode *inode, struct bdi_writeback *wb, | |
1144 | struct writeback_control *wbc) | |
1145 | { | |
1146 | if (inode->i_state & I_FREEING) | |
1147 | return; | |
1148 | ||
1149 | /* | |
1150 | * Sync livelock prevention. Each inode is tagged and synced in one | |
1151 | * shot. If still dirty, it will be redirty_tail()'ed below. Update | |
1152 | * the dirty time to prevent enqueue and sync it again. | |
1153 | */ | |
1154 | if ((inode->i_state & I_DIRTY) && | |
1155 | (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)) | |
1156 | inode->dirtied_when = jiffies; | |
1157 | ||
4f8ad655 JK |
1158 | if (wbc->pages_skipped) { |
1159 | /* | |
1160 | * writeback is not making progress due to locked | |
1161 | * buffers. Skip this inode for now. | |
1162 | */ | |
1163 | redirty_tail(inode, wb); | |
1164 | return; | |
1165 | } | |
1166 | ||
ccb26b5a JK |
1167 | if (mapping_tagged(inode->i_mapping, PAGECACHE_TAG_DIRTY)) { |
1168 | /* | |
1169 | * We didn't write back all the pages. nfs_writepages() | |
1170 | * sometimes bales out without doing anything. | |
1171 | */ | |
1172 | if (wbc->nr_to_write <= 0) { | |
1173 | /* Slice used up. Queue for next turn. */ | |
1174 | requeue_io(inode, wb); | |
1175 | } else { | |
1176 | /* | |
1177 | * Writeback blocked by something other than | |
1178 | * congestion. Delay the inode for some time to | |
1179 | * avoid spinning on the CPU (100% iowait) | |
1180 | * retrying writeback of the dirty page/inode | |
1181 | * that cannot be performed immediately. | |
1182 | */ | |
1183 | redirty_tail(inode, wb); | |
1184 | } | |
1185 | } else if (inode->i_state & I_DIRTY) { | |
1186 | /* | |
1187 | * Filesystems can dirty the inode during writeback operations, | |
1188 | * such as delayed allocation during submission or metadata | |
1189 | * updates after data IO completion. | |
1190 | */ | |
1191 | redirty_tail(inode, wb); | |
0ae45f63 | 1192 | } else if (inode->i_state & I_DIRTY_TIME) { |
a2f48706 | 1193 | inode->dirtied_when = jiffies; |
c7f54084 | 1194 | inode_io_list_move_locked(inode, wb, &wb->b_dirty_time); |
ccb26b5a JK |
1195 | } else { |
1196 | /* The inode is clean. Remove from writeback lists. */ | |
c7f54084 | 1197 | inode_io_list_del_locked(inode, wb); |
ccb26b5a JK |
1198 | } |
1199 | } | |
1200 | ||
01c03194 | 1201 | /* |
4f8ad655 JK |
1202 | * Write out an inode and its dirty pages. Do not update the writeback list |
1203 | * linkage. That is left to the caller. The caller is also responsible for | |
1204 | * setting I_SYNC flag and calling inode_sync_complete() to clear it. | |
1da177e4 LT |
1205 | */ |
1206 | static int | |
cd8ed2a4 | 1207 | __writeback_single_inode(struct inode *inode, struct writeback_control *wbc) |
1da177e4 | 1208 | { |
1da177e4 | 1209 | struct address_space *mapping = inode->i_mapping; |
251d6a47 | 1210 | long nr_to_write = wbc->nr_to_write; |
01c03194 | 1211 | unsigned dirty; |
1da177e4 LT |
1212 | int ret; |
1213 | ||
4f8ad655 | 1214 | WARN_ON(!(inode->i_state & I_SYNC)); |
1da177e4 | 1215 | |
9fb0a7da TH |
1216 | trace_writeback_single_inode_start(inode, wbc, nr_to_write); |
1217 | ||
1da177e4 LT |
1218 | ret = do_writepages(mapping, wbc); |
1219 | ||
26821ed4 CH |
1220 | /* |
1221 | * Make sure to wait on the data before writing out the metadata. | |
1222 | * This is important for filesystems that modify metadata on data | |
7747bd4b DC |
1223 | * I/O completion. We don't do it for sync(2) writeback because it has a |
1224 | * separate, external IO completion path and ->sync_fs for guaranteeing | |
1225 | * inode metadata is written back correctly. | |
26821ed4 | 1226 | */ |
7747bd4b | 1227 | if (wbc->sync_mode == WB_SYNC_ALL && !wbc->for_sync) { |
26821ed4 | 1228 | int err = filemap_fdatawait(mapping); |
1da177e4 LT |
1229 | if (ret == 0) |
1230 | ret = err; | |
1231 | } | |
1232 | ||
5547e8aa DM |
1233 | /* |
1234 | * Some filesystems may redirty the inode during the writeback | |
1235 | * due to delalloc, clear dirty metadata flags right before | |
1236 | * write_inode() | |
1237 | */ | |
250df6ed | 1238 | spin_lock(&inode->i_lock); |
9c6ac78e | 1239 | |
5547e8aa | 1240 | dirty = inode->i_state & I_DIRTY; |
a2f48706 TT |
1241 | if (inode->i_state & I_DIRTY_TIME) { |
1242 | if ((dirty & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) || | |
1243 | unlikely(inode->i_state & I_DIRTY_TIME_EXPIRED) || | |
1244 | unlikely(time_after(jiffies, | |
1245 | (inode->dirtied_time_when + | |
1246 | dirtytime_expire_interval * HZ)))) { | |
1247 | dirty |= I_DIRTY_TIME | I_DIRTY_TIME_EXPIRED; | |
1248 | trace_writeback_lazytime(inode); | |
1249 | } | |
1250 | } else | |
1251 | inode->i_state &= ~I_DIRTY_TIME_EXPIRED; | |
0ae45f63 | 1252 | inode->i_state &= ~dirty; |
9c6ac78e TH |
1253 | |
1254 | /* | |
1255 | * Paired with smp_mb() in __mark_inode_dirty(). This allows | |
1256 | * __mark_inode_dirty() to test i_state without grabbing i_lock - | |
1257 | * either they see the I_DIRTY bits cleared or we see the dirtied | |
1258 | * inode. | |
1259 | * | |
1260 | * I_DIRTY_PAGES is always cleared together above even if @mapping | |
1261 | * still has dirty pages. The flag is reinstated after smp_mb() if | |
1262 | * necessary. This guarantees that either __mark_inode_dirty() | |
1263 | * sees clear I_DIRTY_PAGES or we see PAGECACHE_TAG_DIRTY. | |
1264 | */ | |
1265 | smp_mb(); | |
1266 | ||
1267 | if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) | |
1268 | inode->i_state |= I_DIRTY_PAGES; | |
1269 | ||
250df6ed | 1270 | spin_unlock(&inode->i_lock); |
9c6ac78e | 1271 | |
0ae45f63 TT |
1272 | if (dirty & I_DIRTY_TIME) |
1273 | mark_inode_dirty_sync(inode); | |
26821ed4 | 1274 | /* Don't write the inode if only I_DIRTY_PAGES was set */ |
0ae45f63 | 1275 | if (dirty & ~I_DIRTY_PAGES) { |
a9185b41 | 1276 | int err = write_inode(inode, wbc); |
1da177e4 LT |
1277 | if (ret == 0) |
1278 | ret = err; | |
1279 | } | |
4f8ad655 JK |
1280 | trace_writeback_single_inode(inode, wbc, nr_to_write); |
1281 | return ret; | |
1282 | } | |
1283 | ||
1284 | /* | |
1285 | * Write out an inode's dirty pages. Either the caller has an active reference | |
1286 | * on the inode or the inode has I_WILL_FREE set. | |
1287 | * | |
1288 | * This function is designed to be called for writing back one inode which | |
1289 | * we go e.g. from filesystem. Flusher thread uses __writeback_single_inode() | |
1290 | * and does more profound writeback list handling in writeback_sb_inodes(). | |
1291 | */ | |
1292 | static int | |
1293 | writeback_single_inode(struct inode *inode, struct bdi_writeback *wb, | |
1294 | struct writeback_control *wbc) | |
1295 | { | |
1296 | int ret = 0; | |
1297 | ||
1298 | spin_lock(&inode->i_lock); | |
1299 | if (!atomic_read(&inode->i_count)) | |
1300 | WARN_ON(!(inode->i_state & (I_WILL_FREE|I_FREEING))); | |
1301 | else | |
1302 | WARN_ON(inode->i_state & I_WILL_FREE); | |
1303 | ||
1304 | if (inode->i_state & I_SYNC) { | |
1305 | if (wbc->sync_mode != WB_SYNC_ALL) | |
1306 | goto out; | |
1307 | /* | |
169ebd90 JK |
1308 | * It's a data-integrity sync. We must wait. Since callers hold |
1309 | * inode reference or inode has I_WILL_FREE set, it cannot go | |
1310 | * away under us. | |
4f8ad655 | 1311 | */ |
169ebd90 | 1312 | __inode_wait_for_writeback(inode); |
4f8ad655 JK |
1313 | } |
1314 | WARN_ON(inode->i_state & I_SYNC); | |
1315 | /* | |
f9b0e058 JK |
1316 | * Skip inode if it is clean and we have no outstanding writeback in |
1317 | * WB_SYNC_ALL mode. We don't want to mess with writeback lists in this | |
1318 | * function since flusher thread may be doing for example sync in | |
1319 | * parallel and if we move the inode, it could get skipped. So here we | |
1320 | * make sure inode is on some writeback list and leave it there unless | |
1321 | * we have completely cleaned the inode. | |
4f8ad655 | 1322 | */ |
0ae45f63 | 1323 | if (!(inode->i_state & I_DIRTY_ALL) && |
f9b0e058 JK |
1324 | (wbc->sync_mode != WB_SYNC_ALL || |
1325 | !mapping_tagged(inode->i_mapping, PAGECACHE_TAG_WRITEBACK))) | |
4f8ad655 JK |
1326 | goto out; |
1327 | inode->i_state |= I_SYNC; | |
b16b1deb | 1328 | wbc_attach_and_unlock_inode(wbc, inode); |
4f8ad655 | 1329 | |
cd8ed2a4 | 1330 | ret = __writeback_single_inode(inode, wbc); |
1da177e4 | 1331 | |
b16b1deb | 1332 | wbc_detach_inode(wbc); |
f758eeab | 1333 | spin_lock(&wb->list_lock); |
250df6ed | 1334 | spin_lock(&inode->i_lock); |
4f8ad655 JK |
1335 | /* |
1336 | * If inode is clean, remove it from writeback lists. Otherwise don't | |
1337 | * touch it. See comment above for explanation. | |
1338 | */ | |
0ae45f63 | 1339 | if (!(inode->i_state & I_DIRTY_ALL)) |
c7f54084 | 1340 | inode_io_list_del_locked(inode, wb); |
4f8ad655 | 1341 | spin_unlock(&wb->list_lock); |
1c0eeaf5 | 1342 | inode_sync_complete(inode); |
4f8ad655 JK |
1343 | out: |
1344 | spin_unlock(&inode->i_lock); | |
1da177e4 LT |
1345 | return ret; |
1346 | } | |
1347 | ||
a88a341a | 1348 | static long writeback_chunk_size(struct bdi_writeback *wb, |
1a12d8bd | 1349 | struct wb_writeback_work *work) |
d46db3d5 WF |
1350 | { |
1351 | long pages; | |
1352 | ||
1353 | /* | |
1354 | * WB_SYNC_ALL mode does livelock avoidance by syncing dirty | |
1355 | * inodes/pages in one big loop. Setting wbc.nr_to_write=LONG_MAX | |
1356 | * here avoids calling into writeback_inodes_wb() more than once. | |
1357 | * | |
1358 | * The intended call sequence for WB_SYNC_ALL writeback is: | |
1359 | * | |
1360 | * wb_writeback() | |
1361 | * writeback_sb_inodes() <== called only once | |
1362 | * write_cache_pages() <== called once for each inode | |
1363 | * (quickly) tag currently dirty pages | |
1364 | * (maybe slowly) sync all tagged pages | |
1365 | */ | |
1366 | if (work->sync_mode == WB_SYNC_ALL || work->tagged_writepages) | |
1367 | pages = LONG_MAX; | |
1a12d8bd | 1368 | else { |
a88a341a | 1369 | pages = min(wb->avg_write_bandwidth / 2, |
dcc25ae7 | 1370 | global_wb_domain.dirty_limit / DIRTY_SCOPE); |
1a12d8bd WF |
1371 | pages = min(pages, work->nr_pages); |
1372 | pages = round_down(pages + MIN_WRITEBACK_PAGES, | |
1373 | MIN_WRITEBACK_PAGES); | |
1374 | } | |
d46db3d5 WF |
1375 | |
1376 | return pages; | |
1377 | } | |
1378 | ||
f11c9c5c ES |
1379 | /* |
1380 | * Write a portion of b_io inodes which belong to @sb. | |
edadfb10 | 1381 | * |
d46db3d5 | 1382 | * Return the number of pages and/or inodes written. |
0ba13fd1 LT |
1383 | * |
1384 | * NOTE! This is called with wb->list_lock held, and will | |
1385 | * unlock and relock that for each inode it ends up doing | |
1386 | * IO for. | |
f11c9c5c | 1387 | */ |
d46db3d5 WF |
1388 | static long writeback_sb_inodes(struct super_block *sb, |
1389 | struct bdi_writeback *wb, | |
1390 | struct wb_writeback_work *work) | |
1da177e4 | 1391 | { |
d46db3d5 WF |
1392 | struct writeback_control wbc = { |
1393 | .sync_mode = work->sync_mode, | |
1394 | .tagged_writepages = work->tagged_writepages, | |
1395 | .for_kupdate = work->for_kupdate, | |
1396 | .for_background = work->for_background, | |
7747bd4b | 1397 | .for_sync = work->for_sync, |
d46db3d5 WF |
1398 | .range_cyclic = work->range_cyclic, |
1399 | .range_start = 0, | |
1400 | .range_end = LLONG_MAX, | |
1401 | }; | |
1402 | unsigned long start_time = jiffies; | |
1403 | long write_chunk; | |
1404 | long wrote = 0; /* count both pages and inodes */ | |
1405 | ||
03ba3782 | 1406 | while (!list_empty(&wb->b_io)) { |
7ccf19a8 | 1407 | struct inode *inode = wb_inode(wb->b_io.prev); |
edadfb10 CH |
1408 | |
1409 | if (inode->i_sb != sb) { | |
d46db3d5 | 1410 | if (work->sb) { |
edadfb10 CH |
1411 | /* |
1412 | * We only want to write back data for this | |
1413 | * superblock, move all inodes not belonging | |
1414 | * to it back onto the dirty list. | |
1415 | */ | |
f758eeab | 1416 | redirty_tail(inode, wb); |
edadfb10 CH |
1417 | continue; |
1418 | } | |
1419 | ||
1420 | /* | |
1421 | * The inode belongs to a different superblock. | |
1422 | * Bounce back to the caller to unpin this and | |
1423 | * pin the next superblock. | |
1424 | */ | |
d46db3d5 | 1425 | break; |
edadfb10 CH |
1426 | } |
1427 | ||
9843b76a | 1428 | /* |
331cbdee WL |
1429 | * Don't bother with new inodes or inodes being freed, first |
1430 | * kind does not need periodic writeout yet, and for the latter | |
9843b76a CH |
1431 | * kind writeout is handled by the freer. |
1432 | */ | |
250df6ed | 1433 | spin_lock(&inode->i_lock); |
9843b76a | 1434 | if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) { |
250df6ed | 1435 | spin_unlock(&inode->i_lock); |
fcc5c222 | 1436 | redirty_tail(inode, wb); |
7ef0d737 NP |
1437 | continue; |
1438 | } | |
cc1676d9 JK |
1439 | if ((inode->i_state & I_SYNC) && wbc.sync_mode != WB_SYNC_ALL) { |
1440 | /* | |
1441 | * If this inode is locked for writeback and we are not | |
1442 | * doing writeback-for-data-integrity, move it to | |
1443 | * b_more_io so that writeback can proceed with the | |
1444 | * other inodes on s_io. | |
1445 | * | |
1446 | * We'll have another go at writing back this inode | |
1447 | * when we completed a full scan of b_io. | |
1448 | */ | |
1449 | spin_unlock(&inode->i_lock); | |
1450 | requeue_io(inode, wb); | |
1451 | trace_writeback_sb_inodes_requeue(inode); | |
1452 | continue; | |
1453 | } | |
f0d07b7f JK |
1454 | spin_unlock(&wb->list_lock); |
1455 | ||
4f8ad655 JK |
1456 | /* |
1457 | * We already requeued the inode if it had I_SYNC set and we | |
1458 | * are doing WB_SYNC_NONE writeback. So this catches only the | |
1459 | * WB_SYNC_ALL case. | |
1460 | */ | |
169ebd90 JK |
1461 | if (inode->i_state & I_SYNC) { |
1462 | /* Wait for I_SYNC. This function drops i_lock... */ | |
1463 | inode_sleep_on_writeback(inode); | |
1464 | /* Inode may be gone, start again */ | |
ead188f9 | 1465 | spin_lock(&wb->list_lock); |
169ebd90 JK |
1466 | continue; |
1467 | } | |
4f8ad655 | 1468 | inode->i_state |= I_SYNC; |
b16b1deb | 1469 | wbc_attach_and_unlock_inode(&wbc, inode); |
169ebd90 | 1470 | |
a88a341a | 1471 | write_chunk = writeback_chunk_size(wb, work); |
d46db3d5 WF |
1472 | wbc.nr_to_write = write_chunk; |
1473 | wbc.pages_skipped = 0; | |
250df6ed | 1474 | |
169ebd90 JK |
1475 | /* |
1476 | * We use I_SYNC to pin the inode in memory. While it is set | |
1477 | * evict_inode() will wait so the inode cannot be freed. | |
1478 | */ | |
cd8ed2a4 | 1479 | __writeback_single_inode(inode, &wbc); |
250df6ed | 1480 | |
b16b1deb | 1481 | wbc_detach_inode(&wbc); |
d46db3d5 WF |
1482 | work->nr_pages -= write_chunk - wbc.nr_to_write; |
1483 | wrote += write_chunk - wbc.nr_to_write; | |
590dca3a CM |
1484 | |
1485 | if (need_resched()) { | |
1486 | /* | |
1487 | * We're trying to balance between building up a nice | |
1488 | * long list of IOs to improve our merge rate, and | |
1489 | * getting those IOs out quickly for anyone throttling | |
1490 | * in balance_dirty_pages(). cond_resched() doesn't | |
1491 | * unplug, so get our IOs out the door before we | |
1492 | * give up the CPU. | |
1493 | */ | |
1494 | blk_flush_plug(current); | |
1495 | cond_resched(); | |
1496 | } | |
1497 | ||
1498 | ||
4f8ad655 JK |
1499 | spin_lock(&wb->list_lock); |
1500 | spin_lock(&inode->i_lock); | |
0ae45f63 | 1501 | if (!(inode->i_state & I_DIRTY_ALL)) |
d46db3d5 | 1502 | wrote++; |
4f8ad655 JK |
1503 | requeue_inode(inode, wb, &wbc); |
1504 | inode_sync_complete(inode); | |
0f1b1fd8 | 1505 | spin_unlock(&inode->i_lock); |
590dca3a | 1506 | |
d46db3d5 WF |
1507 | /* |
1508 | * bail out to wb_writeback() often enough to check | |
1509 | * background threshold and other termination conditions. | |
1510 | */ | |
1511 | if (wrote) { | |
1512 | if (time_is_before_jiffies(start_time + HZ / 10UL)) | |
1513 | break; | |
1514 | if (work->nr_pages <= 0) | |
1515 | break; | |
8bc3be27 | 1516 | } |
1da177e4 | 1517 | } |
d46db3d5 | 1518 | return wrote; |
f11c9c5c ES |
1519 | } |
1520 | ||
d46db3d5 WF |
1521 | static long __writeback_inodes_wb(struct bdi_writeback *wb, |
1522 | struct wb_writeback_work *work) | |
f11c9c5c | 1523 | { |
d46db3d5 WF |
1524 | unsigned long start_time = jiffies; |
1525 | long wrote = 0; | |
38f21977 | 1526 | |
f11c9c5c | 1527 | while (!list_empty(&wb->b_io)) { |
7ccf19a8 | 1528 | struct inode *inode = wb_inode(wb->b_io.prev); |
f11c9c5c | 1529 | struct super_block *sb = inode->i_sb; |
9ecc2738 | 1530 | |
eb6ef3df | 1531 | if (!trylock_super(sb)) { |
0e995816 | 1532 | /* |
eb6ef3df | 1533 | * trylock_super() may fail consistently due to |
0e995816 WF |
1534 | * s_umount being grabbed by someone else. Don't use |
1535 | * requeue_io() to avoid busy retrying the inode/sb. | |
1536 | */ | |
1537 | redirty_tail(inode, wb); | |
edadfb10 | 1538 | continue; |
f11c9c5c | 1539 | } |
d46db3d5 | 1540 | wrote += writeback_sb_inodes(sb, wb, work); |
eb6ef3df | 1541 | up_read(&sb->s_umount); |
f11c9c5c | 1542 | |
d46db3d5 WF |
1543 | /* refer to the same tests at the end of writeback_sb_inodes */ |
1544 | if (wrote) { | |
1545 | if (time_is_before_jiffies(start_time + HZ / 10UL)) | |
1546 | break; | |
1547 | if (work->nr_pages <= 0) | |
1548 | break; | |
1549 | } | |
f11c9c5c | 1550 | } |
66f3b8e2 | 1551 | /* Leave any unwritten inodes on b_io */ |
d46db3d5 | 1552 | return wrote; |
66f3b8e2 JA |
1553 | } |
1554 | ||
7d9f073b | 1555 | static long writeback_inodes_wb(struct bdi_writeback *wb, long nr_pages, |
0e175a18 | 1556 | enum wb_reason reason) |
edadfb10 | 1557 | { |
d46db3d5 WF |
1558 | struct wb_writeback_work work = { |
1559 | .nr_pages = nr_pages, | |
1560 | .sync_mode = WB_SYNC_NONE, | |
1561 | .range_cyclic = 1, | |
0e175a18 | 1562 | .reason = reason, |
d46db3d5 | 1563 | }; |
505a666e | 1564 | struct blk_plug plug; |
edadfb10 | 1565 | |
505a666e | 1566 | blk_start_plug(&plug); |
f758eeab | 1567 | spin_lock(&wb->list_lock); |
424b351f | 1568 | if (list_empty(&wb->b_io)) |
ad4e38dd | 1569 | queue_io(wb, &work); |
d46db3d5 | 1570 | __writeback_inodes_wb(wb, &work); |
f758eeab | 1571 | spin_unlock(&wb->list_lock); |
505a666e | 1572 | blk_finish_plug(&plug); |
edadfb10 | 1573 | |
d46db3d5 WF |
1574 | return nr_pages - work.nr_pages; |
1575 | } | |
03ba3782 | 1576 | |
03ba3782 JA |
1577 | /* |
1578 | * Explicit flushing or periodic writeback of "old" data. | |
66f3b8e2 | 1579 | * |
03ba3782 JA |
1580 | * Define "old": the first time one of an inode's pages is dirtied, we mark the |
1581 | * dirtying-time in the inode's address_space. So this periodic writeback code | |
1582 | * just walks the superblock inode list, writing back any inodes which are | |
1583 | * older than a specific point in time. | |
66f3b8e2 | 1584 | * |
03ba3782 JA |
1585 | * Try to run once per dirty_writeback_interval. But if a writeback event |
1586 | * takes longer than a dirty_writeback_interval interval, then leave a | |
1587 | * one-second gap. | |
66f3b8e2 | 1588 | * |
03ba3782 JA |
1589 | * older_than_this takes precedence over nr_to_write. So we'll only write back |
1590 | * all dirty pages if they are all attached to "old" mappings. | |
66f3b8e2 | 1591 | */ |
c4a77a6c | 1592 | static long wb_writeback(struct bdi_writeback *wb, |
83ba7b07 | 1593 | struct wb_writeback_work *work) |
66f3b8e2 | 1594 | { |
e98be2d5 | 1595 | unsigned long wb_start = jiffies; |
d46db3d5 | 1596 | long nr_pages = work->nr_pages; |
0dc83bd3 | 1597 | unsigned long oldest_jif; |
a5989bdc | 1598 | struct inode *inode; |
d46db3d5 | 1599 | long progress; |
505a666e | 1600 | struct blk_plug plug; |
66f3b8e2 | 1601 | |
0dc83bd3 JK |
1602 | oldest_jif = jiffies; |
1603 | work->older_than_this = &oldest_jif; | |
38f21977 | 1604 | |
505a666e | 1605 | blk_start_plug(&plug); |
e8dfc305 | 1606 | spin_lock(&wb->list_lock); |
03ba3782 JA |
1607 | for (;;) { |
1608 | /* | |
d3ddec76 | 1609 | * Stop writeback when nr_pages has been consumed |
03ba3782 | 1610 | */ |
83ba7b07 | 1611 | if (work->nr_pages <= 0) |
03ba3782 | 1612 | break; |
66f3b8e2 | 1613 | |
aa373cf5 JK |
1614 | /* |
1615 | * Background writeout and kupdate-style writeback may | |
1616 | * run forever. Stop them if there is other work to do | |
1617 | * so that e.g. sync can proceed. They'll be restarted | |
1618 | * after the other works are all done. | |
1619 | */ | |
1620 | if ((work->for_background || work->for_kupdate) && | |
f0054bb1 | 1621 | !list_empty(&wb->work_list)) |
aa373cf5 JK |
1622 | break; |
1623 | ||
38f21977 | 1624 | /* |
d3ddec76 WF |
1625 | * For background writeout, stop when we are below the |
1626 | * background dirty threshold | |
38f21977 | 1627 | */ |
aa661bbe | 1628 | if (work->for_background && !wb_over_bg_thresh(wb)) |
03ba3782 | 1629 | break; |
38f21977 | 1630 | |
1bc36b64 JK |
1631 | /* |
1632 | * Kupdate and background works are special and we want to | |
1633 | * include all inodes that need writing. Livelock avoidance is | |
1634 | * handled by these works yielding to any other work so we are | |
1635 | * safe. | |
1636 | */ | |
ba9aa839 | 1637 | if (work->for_kupdate) { |
0dc83bd3 | 1638 | oldest_jif = jiffies - |
ba9aa839 | 1639 | msecs_to_jiffies(dirty_expire_interval * 10); |
1bc36b64 | 1640 | } else if (work->for_background) |
0dc83bd3 | 1641 | oldest_jif = jiffies; |
028c2dd1 | 1642 | |
5634cc2a | 1643 | trace_writeback_start(wb, work); |
e8dfc305 | 1644 | if (list_empty(&wb->b_io)) |
ad4e38dd | 1645 | queue_io(wb, work); |
83ba7b07 | 1646 | if (work->sb) |
d46db3d5 | 1647 | progress = writeback_sb_inodes(work->sb, wb, work); |
edadfb10 | 1648 | else |
d46db3d5 | 1649 | progress = __writeback_inodes_wb(wb, work); |
5634cc2a | 1650 | trace_writeback_written(wb, work); |
028c2dd1 | 1651 | |
e98be2d5 | 1652 | wb_update_bandwidth(wb, wb_start); |
03ba3782 JA |
1653 | |
1654 | /* | |
e6fb6da2 WF |
1655 | * Did we write something? Try for more |
1656 | * | |
1657 | * Dirty inodes are moved to b_io for writeback in batches. | |
1658 | * The completion of the current batch does not necessarily | |
1659 | * mean the overall work is done. So we keep looping as long | |
1660 | * as made some progress on cleaning pages or inodes. | |
03ba3782 | 1661 | */ |
d46db3d5 | 1662 | if (progress) |
71fd05a8 JA |
1663 | continue; |
1664 | /* | |
e6fb6da2 | 1665 | * No more inodes for IO, bail |
71fd05a8 | 1666 | */ |
b7a2441f | 1667 | if (list_empty(&wb->b_more_io)) |
03ba3782 | 1668 | break; |
71fd05a8 JA |
1669 | /* |
1670 | * Nothing written. Wait for some inode to | |
1671 | * become available for writeback. Otherwise | |
1672 | * we'll just busyloop. | |
1673 | */ | |
71fd05a8 | 1674 | if (!list_empty(&wb->b_more_io)) { |
5634cc2a | 1675 | trace_writeback_wait(wb, work); |
7ccf19a8 | 1676 | inode = wb_inode(wb->b_more_io.prev); |
250df6ed | 1677 | spin_lock(&inode->i_lock); |
f0d07b7f | 1678 | spin_unlock(&wb->list_lock); |
169ebd90 JK |
1679 | /* This function drops i_lock... */ |
1680 | inode_sleep_on_writeback(inode); | |
f0d07b7f | 1681 | spin_lock(&wb->list_lock); |
03ba3782 JA |
1682 | } |
1683 | } | |
e8dfc305 | 1684 | spin_unlock(&wb->list_lock); |
505a666e | 1685 | blk_finish_plug(&plug); |
03ba3782 | 1686 | |
d46db3d5 | 1687 | return nr_pages - work->nr_pages; |
03ba3782 JA |
1688 | } |
1689 | ||
1690 | /* | |
83ba7b07 | 1691 | * Return the next wb_writeback_work struct that hasn't been processed yet. |
03ba3782 | 1692 | */ |
f0054bb1 | 1693 | static struct wb_writeback_work *get_next_work_item(struct bdi_writeback *wb) |
03ba3782 | 1694 | { |
83ba7b07 | 1695 | struct wb_writeback_work *work = NULL; |
03ba3782 | 1696 | |
f0054bb1 TH |
1697 | spin_lock_bh(&wb->work_lock); |
1698 | if (!list_empty(&wb->work_list)) { | |
1699 | work = list_entry(wb->work_list.next, | |
83ba7b07 CH |
1700 | struct wb_writeback_work, list); |
1701 | list_del_init(&work->list); | |
03ba3782 | 1702 | } |
f0054bb1 | 1703 | spin_unlock_bh(&wb->work_lock); |
83ba7b07 | 1704 | return work; |
03ba3782 JA |
1705 | } |
1706 | ||
cdf01dd5 LT |
1707 | /* |
1708 | * Add in the number of potentially dirty inodes, because each inode | |
1709 | * write can dirty pagecache in the underlying blockdev. | |
1710 | */ | |
1711 | static unsigned long get_nr_dirty_pages(void) | |
1712 | { | |
1713 | return global_page_state(NR_FILE_DIRTY) + | |
1714 | global_page_state(NR_UNSTABLE_NFS) + | |
1715 | get_nr_dirty_inodes(); | |
1716 | } | |
1717 | ||
6585027a JK |
1718 | static long wb_check_background_flush(struct bdi_writeback *wb) |
1719 | { | |
aa661bbe | 1720 | if (wb_over_bg_thresh(wb)) { |
6585027a JK |
1721 | |
1722 | struct wb_writeback_work work = { | |
1723 | .nr_pages = LONG_MAX, | |
1724 | .sync_mode = WB_SYNC_NONE, | |
1725 | .for_background = 1, | |
1726 | .range_cyclic = 1, | |
0e175a18 | 1727 | .reason = WB_REASON_BACKGROUND, |
6585027a JK |
1728 | }; |
1729 | ||
1730 | return wb_writeback(wb, &work); | |
1731 | } | |
1732 | ||
1733 | return 0; | |
1734 | } | |
1735 | ||
03ba3782 JA |
1736 | static long wb_check_old_data_flush(struct bdi_writeback *wb) |
1737 | { | |
1738 | unsigned long expired; | |
1739 | long nr_pages; | |
1740 | ||
69b62d01 JA |
1741 | /* |
1742 | * When set to zero, disable periodic writeback | |
1743 | */ | |
1744 | if (!dirty_writeback_interval) | |
1745 | return 0; | |
1746 | ||
03ba3782 JA |
1747 | expired = wb->last_old_flush + |
1748 | msecs_to_jiffies(dirty_writeback_interval * 10); | |
1749 | if (time_before(jiffies, expired)) | |
1750 | return 0; | |
1751 | ||
1752 | wb->last_old_flush = jiffies; | |
cdf01dd5 | 1753 | nr_pages = get_nr_dirty_pages(); |
03ba3782 | 1754 | |
c4a77a6c | 1755 | if (nr_pages) { |
83ba7b07 | 1756 | struct wb_writeback_work work = { |
c4a77a6c JA |
1757 | .nr_pages = nr_pages, |
1758 | .sync_mode = WB_SYNC_NONE, | |
1759 | .for_kupdate = 1, | |
1760 | .range_cyclic = 1, | |
0e175a18 | 1761 | .reason = WB_REASON_PERIODIC, |
c4a77a6c JA |
1762 | }; |
1763 | ||
83ba7b07 | 1764 | return wb_writeback(wb, &work); |
c4a77a6c | 1765 | } |
03ba3782 JA |
1766 | |
1767 | return 0; | |
1768 | } | |
1769 | ||
1770 | /* | |
1771 | * Retrieve work items and do the writeback they describe | |
1772 | */ | |
25d130ba | 1773 | static long wb_do_writeback(struct bdi_writeback *wb) |
03ba3782 | 1774 | { |
83ba7b07 | 1775 | struct wb_writeback_work *work; |
c4a77a6c | 1776 | long wrote = 0; |
03ba3782 | 1777 | |
4452226e | 1778 | set_bit(WB_writeback_running, &wb->state); |
f0054bb1 | 1779 | while ((work = get_next_work_item(wb)) != NULL) { |
cc395d7f | 1780 | struct wb_completion *done = work->done; |
03ba3782 | 1781 | |
5634cc2a | 1782 | trace_writeback_exec(wb, work); |
455b2864 | 1783 | |
83ba7b07 | 1784 | wrote += wb_writeback(wb, work); |
03ba3782 | 1785 | |
8a1270cd | 1786 | if (work->auto_free) |
83ba7b07 | 1787 | kfree(work); |
cc395d7f TH |
1788 | if (done && atomic_dec_and_test(&done->cnt)) |
1789 | wake_up_all(&wb->bdi->wb_waitq); | |
03ba3782 JA |
1790 | } |
1791 | ||
1792 | /* | |
1793 | * Check for periodic writeback, kupdated() style | |
1794 | */ | |
1795 | wrote += wb_check_old_data_flush(wb); | |
6585027a | 1796 | wrote += wb_check_background_flush(wb); |
4452226e | 1797 | clear_bit(WB_writeback_running, &wb->state); |
03ba3782 JA |
1798 | |
1799 | return wrote; | |
1800 | } | |
1801 | ||
1802 | /* | |
1803 | * Handle writeback of dirty data for the device backed by this bdi. Also | |
839a8e86 | 1804 | * reschedules periodically and does kupdated style flushing. |
03ba3782 | 1805 | */ |
f0054bb1 | 1806 | void wb_workfn(struct work_struct *work) |
03ba3782 | 1807 | { |
839a8e86 TH |
1808 | struct bdi_writeback *wb = container_of(to_delayed_work(work), |
1809 | struct bdi_writeback, dwork); | |
03ba3782 JA |
1810 | long pages_written; |
1811 | ||
f0054bb1 | 1812 | set_worker_desc("flush-%s", dev_name(wb->bdi->dev)); |
766f9164 | 1813 | current->flags |= PF_SWAPWRITE; |
455b2864 | 1814 | |
839a8e86 | 1815 | if (likely(!current_is_workqueue_rescuer() || |
4452226e | 1816 | !test_bit(WB_registered, &wb->state))) { |
6467716a | 1817 | /* |
f0054bb1 | 1818 | * The normal path. Keep writing back @wb until its |
839a8e86 | 1819 | * work_list is empty. Note that this path is also taken |
f0054bb1 | 1820 | * if @wb is shutting down even when we're running off the |
839a8e86 | 1821 | * rescuer as work_list needs to be drained. |
6467716a | 1822 | */ |
839a8e86 | 1823 | do { |
25d130ba | 1824 | pages_written = wb_do_writeback(wb); |
839a8e86 | 1825 | trace_writeback_pages_written(pages_written); |
f0054bb1 | 1826 | } while (!list_empty(&wb->work_list)); |
839a8e86 TH |
1827 | } else { |
1828 | /* | |
1829 | * bdi_wq can't get enough workers and we're running off | |
1830 | * the emergency worker. Don't hog it. Hopefully, 1024 is | |
1831 | * enough for efficient IO. | |
1832 | */ | |
f0054bb1 | 1833 | pages_written = writeback_inodes_wb(wb, 1024, |
839a8e86 | 1834 | WB_REASON_FORKER_THREAD); |
455b2864 | 1835 | trace_writeback_pages_written(pages_written); |
03ba3782 JA |
1836 | } |
1837 | ||
f0054bb1 | 1838 | if (!list_empty(&wb->work_list)) |
6ca738d6 DB |
1839 | mod_delayed_work(bdi_wq, &wb->dwork, 0); |
1840 | else if (wb_has_dirty_io(wb) && dirty_writeback_interval) | |
f0054bb1 | 1841 | wb_wakeup_delayed(wb); |
455b2864 | 1842 | |
839a8e86 | 1843 | current->flags &= ~PF_SWAPWRITE; |
03ba3782 JA |
1844 | } |
1845 | ||
1846 | /* | |
b8c2f347 CH |
1847 | * Start writeback of `nr_pages' pages. If `nr_pages' is zero, write back |
1848 | * the whole world. | |
03ba3782 | 1849 | */ |
0e175a18 | 1850 | void wakeup_flusher_threads(long nr_pages, enum wb_reason reason) |
03ba3782 | 1851 | { |
b8c2f347 | 1852 | struct backing_dev_info *bdi; |
03ba3782 | 1853 | |
47df3dde JK |
1854 | if (!nr_pages) |
1855 | nr_pages = get_nr_dirty_pages(); | |
03ba3782 | 1856 | |
b8c2f347 | 1857 | rcu_read_lock(); |
f2b65121 TH |
1858 | list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) { |
1859 | struct bdi_writeback *wb; | |
1860 | struct wb_iter iter; | |
1861 | ||
1862 | if (!bdi_has_dirty_io(bdi)) | |
1863 | continue; | |
1864 | ||
1865 | bdi_for_each_wb(wb, bdi, &iter, 0) | |
1866 | wb_start_writeback(wb, wb_split_bdi_pages(wb, nr_pages), | |
1867 | false, reason); | |
1868 | } | |
cfc4ba53 | 1869 | rcu_read_unlock(); |
1da177e4 LT |
1870 | } |
1871 | ||
a2f48706 TT |
1872 | /* |
1873 | * Wake up bdi's periodically to make sure dirtytime inodes gets | |
1874 | * written back periodically. We deliberately do *not* check the | |
1875 | * b_dirtytime list in wb_has_dirty_io(), since this would cause the | |
1876 | * kernel to be constantly waking up once there are any dirtytime | |
1877 | * inodes on the system. So instead we define a separate delayed work | |
1878 | * function which gets called much more rarely. (By default, only | |
1879 | * once every 12 hours.) | |
1880 | * | |
1881 | * If there is any other write activity going on in the file system, | |
1882 | * this function won't be necessary. But if the only thing that has | |
1883 | * happened on the file system is a dirtytime inode caused by an atime | |
1884 | * update, we need this infrastructure below to make sure that inode | |
1885 | * eventually gets pushed out to disk. | |
1886 | */ | |
1887 | static void wakeup_dirtytime_writeback(struct work_struct *w); | |
1888 | static DECLARE_DELAYED_WORK(dirtytime_work, wakeup_dirtytime_writeback); | |
1889 | ||
1890 | static void wakeup_dirtytime_writeback(struct work_struct *w) | |
1891 | { | |
1892 | struct backing_dev_info *bdi; | |
1893 | ||
1894 | rcu_read_lock(); | |
1895 | list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) { | |
001fe6f6 TH |
1896 | struct bdi_writeback *wb; |
1897 | struct wb_iter iter; | |
1898 | ||
1899 | bdi_for_each_wb(wb, bdi, &iter, 0) | |
1900 | if (!list_empty(&bdi->wb.b_dirty_time)) | |
1901 | wb_wakeup(&bdi->wb); | |
a2f48706 TT |
1902 | } |
1903 | rcu_read_unlock(); | |
1904 | schedule_delayed_work(&dirtytime_work, dirtytime_expire_interval * HZ); | |
1905 | } | |
1906 | ||
1907 | static int __init start_dirtytime_writeback(void) | |
1908 | { | |
1909 | schedule_delayed_work(&dirtytime_work, dirtytime_expire_interval * HZ); | |
1910 | return 0; | |
1911 | } | |
1912 | __initcall(start_dirtytime_writeback); | |
1913 | ||
1efff914 TT |
1914 | int dirtytime_interval_handler(struct ctl_table *table, int write, |
1915 | void __user *buffer, size_t *lenp, loff_t *ppos) | |
1916 | { | |
1917 | int ret; | |
1918 | ||
1919 | ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); | |
1920 | if (ret == 0 && write) | |
1921 | mod_delayed_work(system_wq, &dirtytime_work, 0); | |
1922 | return ret; | |
1923 | } | |
1924 | ||
03ba3782 JA |
1925 | static noinline void block_dump___mark_inode_dirty(struct inode *inode) |
1926 | { | |
1927 | if (inode->i_ino || strcmp(inode->i_sb->s_id, "bdev")) { | |
1928 | struct dentry *dentry; | |
1929 | const char *name = "?"; | |
1930 | ||
1931 | dentry = d_find_alias(inode); | |
1932 | if (dentry) { | |
1933 | spin_lock(&dentry->d_lock); | |
1934 | name = (const char *) dentry->d_name.name; | |
1935 | } | |
1936 | printk(KERN_DEBUG | |
1937 | "%s(%d): dirtied inode %lu (%s) on %s\n", | |
1938 | current->comm, task_pid_nr(current), inode->i_ino, | |
1939 | name, inode->i_sb->s_id); | |
1940 | if (dentry) { | |
1941 | spin_unlock(&dentry->d_lock); | |
1942 | dput(dentry); | |
1943 | } | |
1944 | } | |
1945 | } | |
1946 | ||
1947 | /** | |
1948 | * __mark_inode_dirty - internal function | |
1949 | * @inode: inode to mark | |
1950 | * @flags: what kind of dirty (i.e. I_DIRTY_SYNC) | |
1951 | * Mark an inode as dirty. Callers should use mark_inode_dirty or | |
1952 | * mark_inode_dirty_sync. | |
1da177e4 | 1953 | * |
03ba3782 JA |
1954 | * Put the inode on the super block's dirty list. |
1955 | * | |
1956 | * CAREFUL! We mark it dirty unconditionally, but move it onto the | |
1957 | * dirty list only if it is hashed or if it refers to a blockdev. | |
1958 | * If it was not hashed, it will never be added to the dirty list | |
1959 | * even if it is later hashed, as it will have been marked dirty already. | |
1960 | * | |
1961 | * In short, make sure you hash any inodes _before_ you start marking | |
1962 | * them dirty. | |
1da177e4 | 1963 | * |
03ba3782 JA |
1964 | * Note that for blockdevs, inode->dirtied_when represents the dirtying time of |
1965 | * the block-special inode (/dev/hda1) itself. And the ->dirtied_when field of | |
1966 | * the kernel-internal blockdev inode represents the dirtying time of the | |
1967 | * blockdev's pages. This is why for I_DIRTY_PAGES we always use | |
1968 | * page->mapping->host, so the page-dirtying time is recorded in the internal | |
1969 | * blockdev inode. | |
1da177e4 | 1970 | */ |
0ae45f63 | 1971 | #define I_DIRTY_INODE (I_DIRTY_SYNC | I_DIRTY_DATASYNC) |
03ba3782 | 1972 | void __mark_inode_dirty(struct inode *inode, int flags) |
1da177e4 | 1973 | { |
03ba3782 | 1974 | struct super_block *sb = inode->i_sb; |
0ae45f63 TT |
1975 | int dirtytime; |
1976 | ||
1977 | trace_writeback_mark_inode_dirty(inode, flags); | |
1da177e4 | 1978 | |
03ba3782 JA |
1979 | /* |
1980 | * Don't do this for I_DIRTY_PAGES - that doesn't actually | |
1981 | * dirty the inode itself | |
1982 | */ | |
0ae45f63 | 1983 | if (flags & (I_DIRTY_SYNC | I_DIRTY_DATASYNC | I_DIRTY_TIME)) { |
9fb0a7da TH |
1984 | trace_writeback_dirty_inode_start(inode, flags); |
1985 | ||
03ba3782 | 1986 | if (sb->s_op->dirty_inode) |
aa385729 | 1987 | sb->s_op->dirty_inode(inode, flags); |
9fb0a7da TH |
1988 | |
1989 | trace_writeback_dirty_inode(inode, flags); | |
03ba3782 | 1990 | } |
0ae45f63 TT |
1991 | if (flags & I_DIRTY_INODE) |
1992 | flags &= ~I_DIRTY_TIME; | |
1993 | dirtytime = flags & I_DIRTY_TIME; | |
03ba3782 JA |
1994 | |
1995 | /* | |
9c6ac78e TH |
1996 | * Paired with smp_mb() in __writeback_single_inode() for the |
1997 | * following lockless i_state test. See there for details. | |
03ba3782 JA |
1998 | */ |
1999 | smp_mb(); | |
2000 | ||
0ae45f63 TT |
2001 | if (((inode->i_state & flags) == flags) || |
2002 | (dirtytime && (inode->i_state & I_DIRTY_INODE))) | |
03ba3782 JA |
2003 | return; |
2004 | ||
2005 | if (unlikely(block_dump)) | |
2006 | block_dump___mark_inode_dirty(inode); | |
2007 | ||
250df6ed | 2008 | spin_lock(&inode->i_lock); |
0ae45f63 TT |
2009 | if (dirtytime && (inode->i_state & I_DIRTY_INODE)) |
2010 | goto out_unlock_inode; | |
03ba3782 JA |
2011 | if ((inode->i_state & flags) != flags) { |
2012 | const int was_dirty = inode->i_state & I_DIRTY; | |
2013 | ||
52ebea74 TH |
2014 | inode_attach_wb(inode, NULL); |
2015 | ||
0ae45f63 TT |
2016 | if (flags & I_DIRTY_INODE) |
2017 | inode->i_state &= ~I_DIRTY_TIME; | |
03ba3782 JA |
2018 | inode->i_state |= flags; |
2019 | ||
2020 | /* | |
2021 | * If the inode is being synced, just update its dirty state. | |
2022 | * The unlocker will place the inode on the appropriate | |
2023 | * superblock list, based upon its state. | |
2024 | */ | |
2025 | if (inode->i_state & I_SYNC) | |
250df6ed | 2026 | goto out_unlock_inode; |
03ba3782 JA |
2027 | |
2028 | /* | |
2029 | * Only add valid (hashed) inodes to the superblock's | |
2030 | * dirty list. Add blockdev inodes as well. | |
2031 | */ | |
2032 | if (!S_ISBLK(inode->i_mode)) { | |
1d3382cb | 2033 | if (inode_unhashed(inode)) |
250df6ed | 2034 | goto out_unlock_inode; |
03ba3782 | 2035 | } |
a4ffdde6 | 2036 | if (inode->i_state & I_FREEING) |
250df6ed | 2037 | goto out_unlock_inode; |
03ba3782 JA |
2038 | |
2039 | /* | |
2040 | * If the inode was already on b_dirty/b_io/b_more_io, don't | |
2041 | * reposition it (that would break b_dirty time-ordering). | |
2042 | */ | |
2043 | if (!was_dirty) { | |
87e1d789 | 2044 | struct bdi_writeback *wb; |
d6c10f1f | 2045 | struct list_head *dirty_list; |
a66979ab | 2046 | bool wakeup_bdi = false; |
253c34e9 | 2047 | |
87e1d789 | 2048 | wb = locked_inode_to_wb_and_lock_list(inode); |
253c34e9 | 2049 | |
0747259d TH |
2050 | WARN(bdi_cap_writeback_dirty(wb->bdi) && |
2051 | !test_bit(WB_registered, &wb->state), | |
2052 | "bdi-%s not registered\n", wb->bdi->name); | |
03ba3782 JA |
2053 | |
2054 | inode->dirtied_when = jiffies; | |
a2f48706 TT |
2055 | if (dirtytime) |
2056 | inode->dirtied_time_when = jiffies; | |
d6c10f1f | 2057 | |
a2f48706 | 2058 | if (inode->i_state & (I_DIRTY_INODE | I_DIRTY_PAGES)) |
0747259d | 2059 | dirty_list = &wb->b_dirty; |
a2f48706 | 2060 | else |
0747259d | 2061 | dirty_list = &wb->b_dirty_time; |
d6c10f1f | 2062 | |
c7f54084 | 2063 | wakeup_bdi = inode_io_list_move_locked(inode, wb, |
d6c10f1f TH |
2064 | dirty_list); |
2065 | ||
0747259d | 2066 | spin_unlock(&wb->list_lock); |
0ae45f63 | 2067 | trace_writeback_dirty_inode_enqueue(inode); |
a66979ab | 2068 | |
d6c10f1f TH |
2069 | /* |
2070 | * If this is the first dirty inode for this bdi, | |
2071 | * we have to wake-up the corresponding bdi thread | |
2072 | * to make sure background write-back happens | |
2073 | * later. | |
2074 | */ | |
0747259d TH |
2075 | if (bdi_cap_writeback_dirty(wb->bdi) && wakeup_bdi) |
2076 | wb_wakeup_delayed(wb); | |
a66979ab | 2077 | return; |
1da177e4 | 2078 | } |
1da177e4 | 2079 | } |
250df6ed DC |
2080 | out_unlock_inode: |
2081 | spin_unlock(&inode->i_lock); | |
253c34e9 | 2082 | |
03ba3782 JA |
2083 | } |
2084 | EXPORT_SYMBOL(__mark_inode_dirty); | |
2085 | ||
e97fedb9 DC |
2086 | /* |
2087 | * The @s_sync_lock is used to serialise concurrent sync operations | |
2088 | * to avoid lock contention problems with concurrent wait_sb_inodes() calls. | |
2089 | * Concurrent callers will block on the s_sync_lock rather than doing contending | |
2090 | * walks. The queueing maintains sync(2) required behaviour as all the IO that | |
2091 | * has been issued up to the time this function is enter is guaranteed to be | |
2092 | * completed by the time we have gained the lock and waited for all IO that is | |
2093 | * in progress regardless of the order callers are granted the lock. | |
2094 | */ | |
b6e51316 | 2095 | static void wait_sb_inodes(struct super_block *sb) |
03ba3782 JA |
2096 | { |
2097 | struct inode *inode, *old_inode = NULL; | |
2098 | ||
2099 | /* | |
2100 | * We need to be protected against the filesystem going from | |
2101 | * r/o to r/w or vice versa. | |
2102 | */ | |
b6e51316 | 2103 | WARN_ON(!rwsem_is_locked(&sb->s_umount)); |
03ba3782 | 2104 | |
e97fedb9 | 2105 | mutex_lock(&sb->s_sync_lock); |
74278da9 | 2106 | spin_lock(&sb->s_inode_list_lock); |
03ba3782 JA |
2107 | |
2108 | /* | |
2109 | * Data integrity sync. Must wait for all pages under writeback, | |
2110 | * because there may have been pages dirtied before our sync | |
2111 | * call, but which had writeout started before we write it out. | |
2112 | * In which case, the inode may not be on the dirty list, but | |
2113 | * we still have to wait for that writeout. | |
2114 | */ | |
b6e51316 | 2115 | list_for_each_entry(inode, &sb->s_inodes, i_sb_list) { |
250df6ed | 2116 | struct address_space *mapping = inode->i_mapping; |
03ba3782 | 2117 | |
250df6ed DC |
2118 | spin_lock(&inode->i_lock); |
2119 | if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) || | |
2120 | (mapping->nrpages == 0)) { | |
2121 | spin_unlock(&inode->i_lock); | |
03ba3782 | 2122 | continue; |
250df6ed | 2123 | } |
03ba3782 | 2124 | __iget(inode); |
250df6ed | 2125 | spin_unlock(&inode->i_lock); |
74278da9 | 2126 | spin_unlock(&sb->s_inode_list_lock); |
55fa6091 | 2127 | |
03ba3782 | 2128 | /* |
55fa6091 DC |
2129 | * We hold a reference to 'inode' so it couldn't have been |
2130 | * removed from s_inodes list while we dropped the | |
74278da9 | 2131 | * s_inode_list_lock. We cannot iput the inode now as we can |
55fa6091 | 2132 | * be holding the last reference and we cannot iput it under |
74278da9 | 2133 | * s_inode_list_lock. So we keep the reference and iput it |
55fa6091 | 2134 | * later. |
03ba3782 JA |
2135 | */ |
2136 | iput(old_inode); | |
2137 | old_inode = inode; | |
2138 | ||
2139 | filemap_fdatawait(mapping); | |
2140 | ||
2141 | cond_resched(); | |
2142 | ||
74278da9 | 2143 | spin_lock(&sb->s_inode_list_lock); |
03ba3782 | 2144 | } |
74278da9 | 2145 | spin_unlock(&sb->s_inode_list_lock); |
03ba3782 | 2146 | iput(old_inode); |
e97fedb9 | 2147 | mutex_unlock(&sb->s_sync_lock); |
1da177e4 LT |
2148 | } |
2149 | ||
f30a7d0c TH |
2150 | static void __writeback_inodes_sb_nr(struct super_block *sb, unsigned long nr, |
2151 | enum wb_reason reason, bool skip_if_busy) | |
1da177e4 | 2152 | { |
cc395d7f | 2153 | DEFINE_WB_COMPLETION_ONSTACK(done); |
83ba7b07 | 2154 | struct wb_writeback_work work = { |
6e6938b6 WF |
2155 | .sb = sb, |
2156 | .sync_mode = WB_SYNC_NONE, | |
2157 | .tagged_writepages = 1, | |
2158 | .done = &done, | |
2159 | .nr_pages = nr, | |
0e175a18 | 2160 | .reason = reason, |
3c4d7165 | 2161 | }; |
e7972912 | 2162 | struct backing_dev_info *bdi = sb->s_bdi; |
d8a8559c | 2163 | |
e7972912 | 2164 | if (!bdi_has_dirty_io(bdi) || bdi == &noop_backing_dev_info) |
6eedc701 | 2165 | return; |
cf37e972 | 2166 | WARN_ON(!rwsem_is_locked(&sb->s_umount)); |
f30a7d0c | 2167 | |
db125360 | 2168 | bdi_split_work_to_wbs(sb->s_bdi, &work, skip_if_busy); |
cc395d7f | 2169 | wb_wait_for_completion(bdi, &done); |
e913fc82 | 2170 | } |
f30a7d0c TH |
2171 | |
2172 | /** | |
2173 | * writeback_inodes_sb_nr - writeback dirty inodes from given super_block | |
2174 | * @sb: the superblock | |
2175 | * @nr: the number of pages to write | |
2176 | * @reason: reason why some writeback work initiated | |
2177 | * | |
2178 | * Start writeback on some inodes on this super_block. No guarantees are made | |
2179 | * on how many (if any) will be written, and this function does not wait | |
2180 | * for IO completion of submitted IO. | |
2181 | */ | |
2182 | void writeback_inodes_sb_nr(struct super_block *sb, | |
2183 | unsigned long nr, | |
2184 | enum wb_reason reason) | |
2185 | { | |
2186 | __writeback_inodes_sb_nr(sb, nr, reason, false); | |
2187 | } | |
3259f8be CM |
2188 | EXPORT_SYMBOL(writeback_inodes_sb_nr); |
2189 | ||
2190 | /** | |
2191 | * writeback_inodes_sb - writeback dirty inodes from given super_block | |
2192 | * @sb: the superblock | |
786228ab | 2193 | * @reason: reason why some writeback work was initiated |
3259f8be CM |
2194 | * |
2195 | * Start writeback on some inodes on this super_block. No guarantees are made | |
2196 | * on how many (if any) will be written, and this function does not wait | |
2197 | * for IO completion of submitted IO. | |
2198 | */ | |
0e175a18 | 2199 | void writeback_inodes_sb(struct super_block *sb, enum wb_reason reason) |
3259f8be | 2200 | { |
0e175a18 | 2201 | return writeback_inodes_sb_nr(sb, get_nr_dirty_pages(), reason); |
3259f8be | 2202 | } |
0e3c9a22 | 2203 | EXPORT_SYMBOL(writeback_inodes_sb); |
e913fc82 | 2204 | |
17bd55d0 | 2205 | /** |
10ee27a0 | 2206 | * try_to_writeback_inodes_sb_nr - try to start writeback if none underway |
17bd55d0 | 2207 | * @sb: the superblock |
10ee27a0 MX |
2208 | * @nr: the number of pages to write |
2209 | * @reason: the reason of writeback | |
17bd55d0 | 2210 | * |
10ee27a0 | 2211 | * Invoke writeback_inodes_sb_nr if no writeback is currently underway. |
17bd55d0 ES |
2212 | * Returns 1 if writeback was started, 0 if not. |
2213 | */ | |
f30a7d0c TH |
2214 | bool try_to_writeback_inodes_sb_nr(struct super_block *sb, unsigned long nr, |
2215 | enum wb_reason reason) | |
17bd55d0 | 2216 | { |
10ee27a0 | 2217 | if (!down_read_trylock(&sb->s_umount)) |
f30a7d0c | 2218 | return false; |
10ee27a0 | 2219 | |
f30a7d0c | 2220 | __writeback_inodes_sb_nr(sb, nr, reason, true); |
10ee27a0 | 2221 | up_read(&sb->s_umount); |
f30a7d0c | 2222 | return true; |
17bd55d0 | 2223 | } |
10ee27a0 | 2224 | EXPORT_SYMBOL(try_to_writeback_inodes_sb_nr); |
17bd55d0 | 2225 | |
3259f8be | 2226 | /** |
10ee27a0 | 2227 | * try_to_writeback_inodes_sb - try to start writeback if none underway |
3259f8be | 2228 | * @sb: the superblock |
786228ab | 2229 | * @reason: reason why some writeback work was initiated |
3259f8be | 2230 | * |
10ee27a0 | 2231 | * Implement by try_to_writeback_inodes_sb_nr() |
3259f8be CM |
2232 | * Returns 1 if writeback was started, 0 if not. |
2233 | */ | |
f30a7d0c | 2234 | bool try_to_writeback_inodes_sb(struct super_block *sb, enum wb_reason reason) |
3259f8be | 2235 | { |
10ee27a0 | 2236 | return try_to_writeback_inodes_sb_nr(sb, get_nr_dirty_pages(), reason); |
3259f8be | 2237 | } |
10ee27a0 | 2238 | EXPORT_SYMBOL(try_to_writeback_inodes_sb); |
3259f8be | 2239 | |
d8a8559c JA |
2240 | /** |
2241 | * sync_inodes_sb - sync sb inode pages | |
0dc83bd3 | 2242 | * @sb: the superblock |
d8a8559c JA |
2243 | * |
2244 | * This function writes and waits on any dirty inode belonging to this | |
0dc83bd3 | 2245 | * super_block. |
d8a8559c | 2246 | */ |
0dc83bd3 | 2247 | void sync_inodes_sb(struct super_block *sb) |
d8a8559c | 2248 | { |
cc395d7f | 2249 | DEFINE_WB_COMPLETION_ONSTACK(done); |
83ba7b07 | 2250 | struct wb_writeback_work work = { |
3c4d7165 CH |
2251 | .sb = sb, |
2252 | .sync_mode = WB_SYNC_ALL, | |
2253 | .nr_pages = LONG_MAX, | |
2254 | .range_cyclic = 0, | |
83ba7b07 | 2255 | .done = &done, |
0e175a18 | 2256 | .reason = WB_REASON_SYNC, |
7747bd4b | 2257 | .for_sync = 1, |
3c4d7165 | 2258 | }; |
e7972912 | 2259 | struct backing_dev_info *bdi = sb->s_bdi; |
3c4d7165 | 2260 | |
006a0973 TH |
2261 | /* |
2262 | * Can't skip on !bdi_has_dirty() because we should wait for !dirty | |
2263 | * inodes under writeback and I_DIRTY_TIME inodes ignored by | |
2264 | * bdi_has_dirty() need to be written out too. | |
2265 | */ | |
2266 | if (bdi == &noop_backing_dev_info) | |
6eedc701 | 2267 | return; |
cf37e972 CH |
2268 | WARN_ON(!rwsem_is_locked(&sb->s_umount)); |
2269 | ||
db125360 | 2270 | bdi_split_work_to_wbs(bdi, &work, false); |
cc395d7f | 2271 | wb_wait_for_completion(bdi, &done); |
83ba7b07 | 2272 | |
b6e51316 | 2273 | wait_sb_inodes(sb); |
1da177e4 | 2274 | } |
d8a8559c | 2275 | EXPORT_SYMBOL(sync_inodes_sb); |
1da177e4 | 2276 | |
1da177e4 | 2277 | /** |
7f04c26d AA |
2278 | * write_inode_now - write an inode to disk |
2279 | * @inode: inode to write to disk | |
2280 | * @sync: whether the write should be synchronous or not | |
2281 | * | |
2282 | * This function commits an inode to disk immediately if it is dirty. This is | |
2283 | * primarily needed by knfsd. | |
1da177e4 | 2284 | * |
7f04c26d | 2285 | * The caller must either have a ref on the inode or must have set I_WILL_FREE. |
1da177e4 | 2286 | */ |
1da177e4 LT |
2287 | int write_inode_now(struct inode *inode, int sync) |
2288 | { | |
f758eeab | 2289 | struct bdi_writeback *wb = &inode_to_bdi(inode)->wb; |
1da177e4 LT |
2290 | struct writeback_control wbc = { |
2291 | .nr_to_write = LONG_MAX, | |
18914b18 | 2292 | .sync_mode = sync ? WB_SYNC_ALL : WB_SYNC_NONE, |
111ebb6e OH |
2293 | .range_start = 0, |
2294 | .range_end = LLONG_MAX, | |
1da177e4 LT |
2295 | }; |
2296 | ||
2297 | if (!mapping_cap_writeback_dirty(inode->i_mapping)) | |
49364ce2 | 2298 | wbc.nr_to_write = 0; |
1da177e4 LT |
2299 | |
2300 | might_sleep(); | |
4f8ad655 | 2301 | return writeback_single_inode(inode, wb, &wbc); |
1da177e4 LT |
2302 | } |
2303 | EXPORT_SYMBOL(write_inode_now); | |
2304 | ||
2305 | /** | |
2306 | * sync_inode - write an inode and its pages to disk. | |
2307 | * @inode: the inode to sync | |
2308 | * @wbc: controls the writeback mode | |
2309 | * | |
2310 | * sync_inode() will write an inode and its pages to disk. It will also | |
2311 | * correctly update the inode on its superblock's dirty inode lists and will | |
2312 | * update inode->i_state. | |
2313 | * | |
2314 | * The caller must have a ref on the inode. | |
2315 | */ | |
2316 | int sync_inode(struct inode *inode, struct writeback_control *wbc) | |
2317 | { | |
4f8ad655 | 2318 | return writeback_single_inode(inode, &inode_to_bdi(inode)->wb, wbc); |
1da177e4 LT |
2319 | } |
2320 | EXPORT_SYMBOL(sync_inode); | |
c3765016 CH |
2321 | |
2322 | /** | |
c691b9d9 | 2323 | * sync_inode_metadata - write an inode to disk |
c3765016 CH |
2324 | * @inode: the inode to sync |
2325 | * @wait: wait for I/O to complete. | |
2326 | * | |
c691b9d9 | 2327 | * Write an inode to disk and adjust its dirty state after completion. |
c3765016 CH |
2328 | * |
2329 | * Note: only writes the actual inode, no associated data or other metadata. | |
2330 | */ | |
2331 | int sync_inode_metadata(struct inode *inode, int wait) | |
2332 | { | |
2333 | struct writeback_control wbc = { | |
2334 | .sync_mode = wait ? WB_SYNC_ALL : WB_SYNC_NONE, | |
2335 | .nr_to_write = 0, /* metadata-only */ | |
2336 | }; | |
2337 | ||
2338 | return sync_inode(inode, &wbc); | |
2339 | } | |
2340 | EXPORT_SYMBOL(sync_inode_metadata); |