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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 | * | |
11 | * 10Apr2002 Andrew Morton | |
12 | * Split out of fs/inode.c | |
13 | * Additions for address_space-based writeback | |
14 | */ | |
15 | ||
16 | #include <linux/kernel.h> | |
17 | #include <linux/module.h> | |
18 | #include <linux/spinlock.h> | |
19 | #include <linux/slab.h> | |
20 | #include <linux/sched.h> | |
21 | #include <linux/fs.h> | |
22 | #include <linux/mm.h> | |
23 | #include <linux/kthread.h> | |
24 | #include <linux/freezer.h> | |
25 | #include <linux/writeback.h> | |
26 | #include <linux/blkdev.h> | |
27 | #include <linux/backing-dev.h> | |
28 | #include <linux/buffer_head.h> | |
29 | #include <linux/tracepoint.h> | |
30 | #include "internal.h" | |
31 | ||
32 | /* | |
33 | * Passed into wb_writeback(), essentially a subset of writeback_control | |
34 | */ | |
35 | struct wb_writeback_work { | |
36 | long nr_pages; | |
37 | struct super_block *sb; | |
38 | enum writeback_sync_modes sync_mode; | |
39 | unsigned int for_kupdate:1; | |
40 | unsigned int range_cyclic:1; | |
41 | unsigned int for_background:1; | |
42 | ||
43 | struct list_head list; /* pending work list */ | |
44 | struct completion *done; /* set if the caller waits */ | |
45 | }; | |
46 | ||
47 | /* | |
48 | * Include the creation of the trace points after defining the | |
49 | * wb_writeback_work structure so that the definition remains local to this | |
50 | * file. | |
51 | */ | |
52 | #define CREATE_TRACE_POINTS | |
53 | #include <trace/events/writeback.h> | |
54 | ||
55 | /* | |
56 | * We don't actually have pdflush, but this one is exported though /proc... | |
57 | */ | |
58 | int nr_pdflush_threads; | |
59 | ||
60 | /** | |
61 | * writeback_in_progress - determine whether there is writeback in progress | |
62 | * @bdi: the device's backing_dev_info structure. | |
63 | * | |
64 | * Determine whether there is writeback waiting to be handled against a | |
65 | * backing device. | |
66 | */ | |
67 | int writeback_in_progress(struct backing_dev_info *bdi) | |
68 | { | |
69 | return test_bit(BDI_writeback_running, &bdi->state); | |
70 | } | |
71 | ||
72 | static inline struct backing_dev_info *inode_to_bdi(struct inode *inode) | |
73 | { | |
74 | struct super_block *sb = inode->i_sb; | |
75 | ||
76 | if (strcmp(sb->s_type->name, "bdev") == 0) | |
77 | return inode->i_mapping->backing_dev_info; | |
78 | ||
79 | return sb->s_bdi; | |
80 | } | |
81 | ||
82 | static inline struct inode *wb_inode(struct list_head *head) | |
83 | { | |
84 | return list_entry(head, struct inode, i_wb_list); | |
85 | } | |
86 | ||
87 | static void bdi_queue_work(struct backing_dev_info *bdi, | |
88 | struct wb_writeback_work *work) | |
89 | { | |
90 | trace_writeback_queue(bdi, work); | |
91 | ||
92 | spin_lock_bh(&bdi->wb_lock); | |
93 | list_add_tail(&work->list, &bdi->work_list); | |
94 | if (bdi->wb.task) { | |
95 | wake_up_process(bdi->wb.task); | |
96 | } else { | |
97 | /* | |
98 | * The bdi thread isn't there, wake up the forker thread which | |
99 | * will create and run it. | |
100 | */ | |
101 | trace_writeback_nothread(bdi, work); | |
102 | wake_up_process(default_backing_dev_info.wb.task); | |
103 | } | |
104 | spin_unlock_bh(&bdi->wb_lock); | |
105 | } | |
106 | ||
107 | static void | |
108 | __bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages, | |
109 | bool range_cyclic, bool for_background) | |
110 | { | |
111 | struct wb_writeback_work *work; | |
112 | ||
113 | /* | |
114 | * This is WB_SYNC_NONE writeback, so if allocation fails just | |
115 | * wakeup the thread for old dirty data writeback | |
116 | */ | |
117 | work = kzalloc(sizeof(*work), GFP_ATOMIC); | |
118 | if (!work) { | |
119 | if (bdi->wb.task) { | |
120 | trace_writeback_nowork(bdi); | |
121 | wake_up_process(bdi->wb.task); | |
122 | } | |
123 | return; | |
124 | } | |
125 | ||
126 | work->sync_mode = WB_SYNC_NONE; | |
127 | work->nr_pages = nr_pages; | |
128 | work->range_cyclic = range_cyclic; | |
129 | work->for_background = for_background; | |
130 | ||
131 | bdi_queue_work(bdi, work); | |
132 | } | |
133 | ||
134 | /** | |
135 | * bdi_start_writeback - start writeback | |
136 | * @bdi: the backing device to write from | |
137 | * @nr_pages: the number of pages to write | |
138 | * | |
139 | * Description: | |
140 | * This does WB_SYNC_NONE opportunistic writeback. The IO is only | |
141 | * started when this function returns, we make no guarentees on | |
142 | * completion. Caller need not hold sb s_umount semaphore. | |
143 | * | |
144 | */ | |
145 | void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages) | |
146 | { | |
147 | __bdi_start_writeback(bdi, nr_pages, true, false); | |
148 | } | |
149 | ||
150 | /** | |
151 | * bdi_start_background_writeback - start background writeback | |
152 | * @bdi: the backing device to write from | |
153 | * | |
154 | * Description: | |
155 | * This does WB_SYNC_NONE background writeback. The IO is only | |
156 | * started when this function returns, we make no guarentees on | |
157 | * completion. Caller need not hold sb s_umount semaphore. | |
158 | */ | |
159 | void bdi_start_background_writeback(struct backing_dev_info *bdi) | |
160 | { | |
161 | __bdi_start_writeback(bdi, LONG_MAX, true, true); | |
162 | } | |
163 | ||
164 | /* | |
165 | * Redirty an inode: set its when-it-was dirtied timestamp and move it to the | |
166 | * furthest end of its superblock's dirty-inode list. | |
167 | * | |
168 | * Before stamping the inode's ->dirtied_when, we check to see whether it is | |
169 | * already the most-recently-dirtied inode on the b_dirty list. If that is | |
170 | * the case then the inode must have been redirtied while it was being written | |
171 | * out and we don't reset its dirtied_when. | |
172 | */ | |
173 | static void redirty_tail(struct inode *inode) | |
174 | { | |
175 | struct bdi_writeback *wb = &inode_to_bdi(inode)->wb; | |
176 | ||
177 | if (!list_empty(&wb->b_dirty)) { | |
178 | struct inode *tail; | |
179 | ||
180 | tail = wb_inode(wb->b_dirty.next); | |
181 | if (time_before(inode->dirtied_when, tail->dirtied_when)) | |
182 | inode->dirtied_when = jiffies; | |
183 | } | |
184 | list_move(&inode->i_wb_list, &wb->b_dirty); | |
185 | } | |
186 | ||
187 | /* | |
188 | * requeue inode for re-scanning after bdi->b_io list is exhausted. | |
189 | */ | |
190 | static void requeue_io(struct inode *inode) | |
191 | { | |
192 | struct bdi_writeback *wb = &inode_to_bdi(inode)->wb; | |
193 | ||
194 | list_move(&inode->i_wb_list, &wb->b_more_io); | |
195 | } | |
196 | ||
197 | static void inode_sync_complete(struct inode *inode) | |
198 | { | |
199 | /* | |
200 | * Prevent speculative execution through spin_unlock(&inode_lock); | |
201 | */ | |
202 | smp_mb(); | |
203 | wake_up_bit(&inode->i_state, __I_SYNC); | |
204 | } | |
205 | ||
206 | static bool inode_dirtied_after(struct inode *inode, unsigned long t) | |
207 | { | |
208 | bool ret = time_after(inode->dirtied_when, t); | |
209 | #ifndef CONFIG_64BIT | |
210 | /* | |
211 | * For inodes being constantly redirtied, dirtied_when can get stuck. | |
212 | * It _appears_ to be in the future, but is actually in distant past. | |
213 | * This test is necessary to prevent such wrapped-around relative times | |
214 | * from permanently stopping the whole bdi writeback. | |
215 | */ | |
216 | ret = ret && time_before_eq(inode->dirtied_when, jiffies); | |
217 | #endif | |
218 | return ret; | |
219 | } | |
220 | ||
221 | /* | |
222 | * Move expired dirty inodes from @delaying_queue to @dispatch_queue. | |
223 | */ | |
224 | static void move_expired_inodes(struct list_head *delaying_queue, | |
225 | struct list_head *dispatch_queue, | |
226 | unsigned long *older_than_this) | |
227 | { | |
228 | LIST_HEAD(tmp); | |
229 | struct list_head *pos, *node; | |
230 | struct super_block *sb = NULL; | |
231 | struct inode *inode; | |
232 | int do_sb_sort = 0; | |
233 | ||
234 | while (!list_empty(delaying_queue)) { | |
235 | inode = wb_inode(delaying_queue->prev); | |
236 | if (older_than_this && | |
237 | inode_dirtied_after(inode, *older_than_this)) | |
238 | break; | |
239 | if (sb && sb != inode->i_sb) | |
240 | do_sb_sort = 1; | |
241 | sb = inode->i_sb; | |
242 | list_move(&inode->i_wb_list, &tmp); | |
243 | } | |
244 | ||
245 | /* just one sb in list, splice to dispatch_queue and we're done */ | |
246 | if (!do_sb_sort) { | |
247 | list_splice(&tmp, dispatch_queue); | |
248 | return; | |
249 | } | |
250 | ||
251 | /* Move inodes from one superblock together */ | |
252 | while (!list_empty(&tmp)) { | |
253 | sb = wb_inode(tmp.prev)->i_sb; | |
254 | list_for_each_prev_safe(pos, node, &tmp) { | |
255 | inode = wb_inode(pos); | |
256 | if (inode->i_sb == sb) | |
257 | list_move(&inode->i_wb_list, dispatch_queue); | |
258 | } | |
259 | } | |
260 | } | |
261 | ||
262 | /* | |
263 | * Queue all expired dirty inodes for io, eldest first. | |
264 | * Before | |
265 | * newly dirtied b_dirty b_io b_more_io | |
266 | * =============> gf edc BA | |
267 | * After | |
268 | * newly dirtied b_dirty b_io b_more_io | |
269 | * =============> g fBAedc | |
270 | * | | |
271 | * +--> dequeue for IO | |
272 | */ | |
273 | static void queue_io(struct bdi_writeback *wb, unsigned long *older_than_this) | |
274 | { | |
275 | list_splice_init(&wb->b_more_io, &wb->b_io); | |
276 | move_expired_inodes(&wb->b_dirty, &wb->b_io, older_than_this); | |
277 | } | |
278 | ||
279 | static int write_inode(struct inode *inode, struct writeback_control *wbc) | |
280 | { | |
281 | if (inode->i_sb->s_op->write_inode && !is_bad_inode(inode)) | |
282 | return inode->i_sb->s_op->write_inode(inode, wbc); | |
283 | return 0; | |
284 | } | |
285 | ||
286 | /* | |
287 | * Wait for writeback on an inode to complete. | |
288 | */ | |
289 | static void inode_wait_for_writeback(struct inode *inode) | |
290 | { | |
291 | DEFINE_WAIT_BIT(wq, &inode->i_state, __I_SYNC); | |
292 | wait_queue_head_t *wqh; | |
293 | ||
294 | wqh = bit_waitqueue(&inode->i_state, __I_SYNC); | |
295 | while (inode->i_state & I_SYNC) { | |
296 | spin_unlock(&inode_lock); | |
297 | __wait_on_bit(wqh, &wq, inode_wait, TASK_UNINTERRUPTIBLE); | |
298 | spin_lock(&inode_lock); | |
299 | } | |
300 | } | |
301 | ||
302 | /* | |
303 | * Write out an inode's dirty pages. Called under inode_lock. Either the | |
304 | * caller has ref on the inode (either via __iget or via syscall against an fd) | |
305 | * or the inode has I_WILL_FREE set (via generic_forget_inode) | |
306 | * | |
307 | * If `wait' is set, wait on the writeout. | |
308 | * | |
309 | * The whole writeout design is quite complex and fragile. We want to avoid | |
310 | * starvation of particular inodes when others are being redirtied, prevent | |
311 | * livelocks, etc. | |
312 | * | |
313 | * Called under inode_lock. | |
314 | */ | |
315 | static int | |
316 | writeback_single_inode(struct inode *inode, struct writeback_control *wbc) | |
317 | { | |
318 | struct address_space *mapping = inode->i_mapping; | |
319 | unsigned dirty; | |
320 | int ret; | |
321 | ||
322 | if (!atomic_read(&inode->i_count)) | |
323 | WARN_ON(!(inode->i_state & (I_WILL_FREE|I_FREEING))); | |
324 | else | |
325 | WARN_ON(inode->i_state & I_WILL_FREE); | |
326 | ||
327 | if (inode->i_state & I_SYNC) { | |
328 | /* | |
329 | * If this inode is locked for writeback and we are not doing | |
330 | * writeback-for-data-integrity, move it to b_more_io so that | |
331 | * writeback can proceed with the other inodes on s_io. | |
332 | * | |
333 | * We'll have another go at writing back this inode when we | |
334 | * completed a full scan of b_io. | |
335 | */ | |
336 | if (wbc->sync_mode != WB_SYNC_ALL) { | |
337 | requeue_io(inode); | |
338 | return 0; | |
339 | } | |
340 | ||
341 | /* | |
342 | * It's a data-integrity sync. We must wait. | |
343 | */ | |
344 | inode_wait_for_writeback(inode); | |
345 | } | |
346 | ||
347 | BUG_ON(inode->i_state & I_SYNC); | |
348 | ||
349 | /* Set I_SYNC, reset I_DIRTY_PAGES */ | |
350 | inode->i_state |= I_SYNC; | |
351 | inode->i_state &= ~I_DIRTY_PAGES; | |
352 | spin_unlock(&inode_lock); | |
353 | ||
354 | ret = do_writepages(mapping, wbc); | |
355 | ||
356 | /* | |
357 | * Make sure to wait on the data before writing out the metadata. | |
358 | * This is important for filesystems that modify metadata on data | |
359 | * I/O completion. | |
360 | */ | |
361 | if (wbc->sync_mode == WB_SYNC_ALL) { | |
362 | int err = filemap_fdatawait(mapping); | |
363 | if (ret == 0) | |
364 | ret = err; | |
365 | } | |
366 | ||
367 | /* | |
368 | * Some filesystems may redirty the inode during the writeback | |
369 | * due to delalloc, clear dirty metadata flags right before | |
370 | * write_inode() | |
371 | */ | |
372 | spin_lock(&inode_lock); | |
373 | dirty = inode->i_state & I_DIRTY; | |
374 | inode->i_state &= ~(I_DIRTY_SYNC | I_DIRTY_DATASYNC); | |
375 | spin_unlock(&inode_lock); | |
376 | /* Don't write the inode if only I_DIRTY_PAGES was set */ | |
377 | if (dirty & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) { | |
378 | int err = write_inode(inode, wbc); | |
379 | if (ret == 0) | |
380 | ret = err; | |
381 | } | |
382 | ||
383 | spin_lock(&inode_lock); | |
384 | inode->i_state &= ~I_SYNC; | |
385 | if (!(inode->i_state & I_FREEING)) { | |
386 | if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) { | |
387 | /* | |
388 | * We didn't write back all the pages. nfs_writepages() | |
389 | * sometimes bales out without doing anything. | |
390 | */ | |
391 | inode->i_state |= I_DIRTY_PAGES; | |
392 | if (wbc->nr_to_write <= 0) { | |
393 | /* | |
394 | * slice used up: queue for next turn | |
395 | */ | |
396 | requeue_io(inode); | |
397 | } else { | |
398 | /* | |
399 | * Writeback blocked by something other than | |
400 | * congestion. Delay the inode for some time to | |
401 | * avoid spinning on the CPU (100% iowait) | |
402 | * retrying writeback of the dirty page/inode | |
403 | * that cannot be performed immediately. | |
404 | */ | |
405 | redirty_tail(inode); | |
406 | } | |
407 | } else if (inode->i_state & I_DIRTY) { | |
408 | /* | |
409 | * Filesystems can dirty the inode during writeback | |
410 | * operations, such as delayed allocation during | |
411 | * submission or metadata updates after data IO | |
412 | * completion. | |
413 | */ | |
414 | redirty_tail(inode); | |
415 | } else { | |
416 | /* | |
417 | * The inode is clean. At this point we either have | |
418 | * a reference to the inode or it's on it's way out. | |
419 | * No need to add it back to the LRU. | |
420 | */ | |
421 | list_del_init(&inode->i_wb_list); | |
422 | } | |
423 | } | |
424 | inode_sync_complete(inode); | |
425 | return ret; | |
426 | } | |
427 | ||
428 | /* | |
429 | * For background writeback the caller does not have the sb pinned | |
430 | * before calling writeback. So make sure that we do pin it, so it doesn't | |
431 | * go away while we are writing inodes from it. | |
432 | */ | |
433 | static bool pin_sb_for_writeback(struct super_block *sb) | |
434 | { | |
435 | spin_lock(&sb_lock); | |
436 | if (list_empty(&sb->s_instances)) { | |
437 | spin_unlock(&sb_lock); | |
438 | return false; | |
439 | } | |
440 | ||
441 | sb->s_count++; | |
442 | spin_unlock(&sb_lock); | |
443 | ||
444 | if (down_read_trylock(&sb->s_umount)) { | |
445 | if (sb->s_root) | |
446 | return true; | |
447 | up_read(&sb->s_umount); | |
448 | } | |
449 | ||
450 | put_super(sb); | |
451 | return false; | |
452 | } | |
453 | ||
454 | /* | |
455 | * Write a portion of b_io inodes which belong to @sb. | |
456 | * | |
457 | * If @only_this_sb is true, then find and write all such | |
458 | * inodes. Otherwise write only ones which go sequentially | |
459 | * in reverse order. | |
460 | * | |
461 | * Return 1, if the caller writeback routine should be | |
462 | * interrupted. Otherwise return 0. | |
463 | */ | |
464 | static int writeback_sb_inodes(struct super_block *sb, struct bdi_writeback *wb, | |
465 | struct writeback_control *wbc, bool only_this_sb) | |
466 | { | |
467 | while (!list_empty(&wb->b_io)) { | |
468 | long pages_skipped; | |
469 | struct inode *inode = wb_inode(wb->b_io.prev); | |
470 | ||
471 | if (inode->i_sb != sb) { | |
472 | if (only_this_sb) { | |
473 | /* | |
474 | * We only want to write back data for this | |
475 | * superblock, move all inodes not belonging | |
476 | * to it back onto the dirty list. | |
477 | */ | |
478 | redirty_tail(inode); | |
479 | continue; | |
480 | } | |
481 | ||
482 | /* | |
483 | * The inode belongs to a different superblock. | |
484 | * Bounce back to the caller to unpin this and | |
485 | * pin the next superblock. | |
486 | */ | |
487 | return 0; | |
488 | } | |
489 | ||
490 | /* | |
491 | * Don't bother with new inodes or inodes beeing freed, first | |
492 | * kind does not need peridic writeout yet, and for the latter | |
493 | * kind writeout is handled by the freer. | |
494 | */ | |
495 | if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) { | |
496 | requeue_io(inode); | |
497 | continue; | |
498 | } | |
499 | ||
500 | /* | |
501 | * Was this inode dirtied after sync_sb_inodes was called? | |
502 | * This keeps sync from extra jobs and livelock. | |
503 | */ | |
504 | if (inode_dirtied_after(inode, wbc->wb_start)) | |
505 | return 1; | |
506 | ||
507 | __iget(inode); | |
508 | pages_skipped = wbc->pages_skipped; | |
509 | writeback_single_inode(inode, wbc); | |
510 | if (wbc->pages_skipped != pages_skipped) { | |
511 | /* | |
512 | * writeback is not making progress due to locked | |
513 | * buffers. Skip this inode for now. | |
514 | */ | |
515 | redirty_tail(inode); | |
516 | } | |
517 | spin_unlock(&inode_lock); | |
518 | iput(inode); | |
519 | cond_resched(); | |
520 | spin_lock(&inode_lock); | |
521 | if (wbc->nr_to_write <= 0) { | |
522 | wbc->more_io = 1; | |
523 | return 1; | |
524 | } | |
525 | if (!list_empty(&wb->b_more_io)) | |
526 | wbc->more_io = 1; | |
527 | } | |
528 | /* b_io is empty */ | |
529 | return 1; | |
530 | } | |
531 | ||
532 | void writeback_inodes_wb(struct bdi_writeback *wb, | |
533 | struct writeback_control *wbc) | |
534 | { | |
535 | int ret = 0; | |
536 | ||
537 | if (!wbc->wb_start) | |
538 | wbc->wb_start = jiffies; /* livelock avoidance */ | |
539 | spin_lock(&inode_lock); | |
540 | if (!wbc->for_kupdate || list_empty(&wb->b_io)) | |
541 | queue_io(wb, wbc->older_than_this); | |
542 | ||
543 | while (!list_empty(&wb->b_io)) { | |
544 | struct inode *inode = wb_inode(wb->b_io.prev); | |
545 | struct super_block *sb = inode->i_sb; | |
546 | ||
547 | if (!pin_sb_for_writeback(sb)) { | |
548 | requeue_io(inode); | |
549 | continue; | |
550 | } | |
551 | ret = writeback_sb_inodes(sb, wb, wbc, false); | |
552 | drop_super(sb); | |
553 | ||
554 | if (ret) | |
555 | break; | |
556 | } | |
557 | spin_unlock(&inode_lock); | |
558 | /* Leave any unwritten inodes on b_io */ | |
559 | } | |
560 | ||
561 | static void __writeback_inodes_sb(struct super_block *sb, | |
562 | struct bdi_writeback *wb, struct writeback_control *wbc) | |
563 | { | |
564 | WARN_ON(!rwsem_is_locked(&sb->s_umount)); | |
565 | ||
566 | spin_lock(&inode_lock); | |
567 | if (!wbc->for_kupdate || list_empty(&wb->b_io)) | |
568 | queue_io(wb, wbc->older_than_this); | |
569 | writeback_sb_inodes(sb, wb, wbc, true); | |
570 | spin_unlock(&inode_lock); | |
571 | } | |
572 | ||
573 | /* | |
574 | * The maximum number of pages to writeout in a single bdi flush/kupdate | |
575 | * operation. We do this so we don't hold I_SYNC against an inode for | |
576 | * enormous amounts of time, which would block a userspace task which has | |
577 | * been forced to throttle against that inode. Also, the code reevaluates | |
578 | * the dirty each time it has written this many pages. | |
579 | */ | |
580 | #define MAX_WRITEBACK_PAGES 1024 | |
581 | ||
582 | static inline bool over_bground_thresh(void) | |
583 | { | |
584 | unsigned long background_thresh, dirty_thresh; | |
585 | ||
586 | global_dirty_limits(&background_thresh, &dirty_thresh); | |
587 | ||
588 | return (global_page_state(NR_FILE_DIRTY) + | |
589 | global_page_state(NR_UNSTABLE_NFS) > background_thresh); | |
590 | } | |
591 | ||
592 | /* | |
593 | * Explicit flushing or periodic writeback of "old" data. | |
594 | * | |
595 | * Define "old": the first time one of an inode's pages is dirtied, we mark the | |
596 | * dirtying-time in the inode's address_space. So this periodic writeback code | |
597 | * just walks the superblock inode list, writing back any inodes which are | |
598 | * older than a specific point in time. | |
599 | * | |
600 | * Try to run once per dirty_writeback_interval. But if a writeback event | |
601 | * takes longer than a dirty_writeback_interval interval, then leave a | |
602 | * one-second gap. | |
603 | * | |
604 | * older_than_this takes precedence over nr_to_write. So we'll only write back | |
605 | * all dirty pages if they are all attached to "old" mappings. | |
606 | */ | |
607 | static long wb_writeback(struct bdi_writeback *wb, | |
608 | struct wb_writeback_work *work) | |
609 | { | |
610 | struct writeback_control wbc = { | |
611 | .sync_mode = work->sync_mode, | |
612 | .older_than_this = NULL, | |
613 | .for_kupdate = work->for_kupdate, | |
614 | .for_background = work->for_background, | |
615 | .range_cyclic = work->range_cyclic, | |
616 | }; | |
617 | unsigned long oldest_jif; | |
618 | long wrote = 0; | |
619 | struct inode *inode; | |
620 | ||
621 | if (wbc.for_kupdate) { | |
622 | wbc.older_than_this = &oldest_jif; | |
623 | oldest_jif = jiffies - | |
624 | msecs_to_jiffies(dirty_expire_interval * 10); | |
625 | } | |
626 | if (!wbc.range_cyclic) { | |
627 | wbc.range_start = 0; | |
628 | wbc.range_end = LLONG_MAX; | |
629 | } | |
630 | ||
631 | wbc.wb_start = jiffies; /* livelock avoidance */ | |
632 | for (;;) { | |
633 | /* | |
634 | * Stop writeback when nr_pages has been consumed | |
635 | */ | |
636 | if (work->nr_pages <= 0) | |
637 | break; | |
638 | ||
639 | /* | |
640 | * For background writeout, stop when we are below the | |
641 | * background dirty threshold | |
642 | */ | |
643 | if (work->for_background && !over_bground_thresh()) | |
644 | break; | |
645 | ||
646 | wbc.more_io = 0; | |
647 | wbc.nr_to_write = MAX_WRITEBACK_PAGES; | |
648 | wbc.pages_skipped = 0; | |
649 | ||
650 | trace_wbc_writeback_start(&wbc, wb->bdi); | |
651 | if (work->sb) | |
652 | __writeback_inodes_sb(work->sb, wb, &wbc); | |
653 | else | |
654 | writeback_inodes_wb(wb, &wbc); | |
655 | trace_wbc_writeback_written(&wbc, wb->bdi); | |
656 | ||
657 | work->nr_pages -= MAX_WRITEBACK_PAGES - wbc.nr_to_write; | |
658 | wrote += MAX_WRITEBACK_PAGES - wbc.nr_to_write; | |
659 | ||
660 | /* | |
661 | * If we consumed everything, see if we have more | |
662 | */ | |
663 | if (wbc.nr_to_write <= 0) | |
664 | continue; | |
665 | /* | |
666 | * Didn't write everything and we don't have more IO, bail | |
667 | */ | |
668 | if (!wbc.more_io) | |
669 | break; | |
670 | /* | |
671 | * Did we write something? Try for more | |
672 | */ | |
673 | if (wbc.nr_to_write < MAX_WRITEBACK_PAGES) | |
674 | continue; | |
675 | /* | |
676 | * Nothing written. Wait for some inode to | |
677 | * become available for writeback. Otherwise | |
678 | * we'll just busyloop. | |
679 | */ | |
680 | spin_lock(&inode_lock); | |
681 | if (!list_empty(&wb->b_more_io)) { | |
682 | inode = wb_inode(wb->b_more_io.prev); | |
683 | trace_wbc_writeback_wait(&wbc, wb->bdi); | |
684 | inode_wait_for_writeback(inode); | |
685 | } | |
686 | spin_unlock(&inode_lock); | |
687 | } | |
688 | ||
689 | return wrote; | |
690 | } | |
691 | ||
692 | /* | |
693 | * Return the next wb_writeback_work struct that hasn't been processed yet. | |
694 | */ | |
695 | static struct wb_writeback_work * | |
696 | get_next_work_item(struct backing_dev_info *bdi) | |
697 | { | |
698 | struct wb_writeback_work *work = NULL; | |
699 | ||
700 | spin_lock_bh(&bdi->wb_lock); | |
701 | if (!list_empty(&bdi->work_list)) { | |
702 | work = list_entry(bdi->work_list.next, | |
703 | struct wb_writeback_work, list); | |
704 | list_del_init(&work->list); | |
705 | } | |
706 | spin_unlock_bh(&bdi->wb_lock); | |
707 | return work; | |
708 | } | |
709 | ||
710 | /* | |
711 | * Add in the number of potentially dirty inodes, because each inode | |
712 | * write can dirty pagecache in the underlying blockdev. | |
713 | */ | |
714 | static unsigned long get_nr_dirty_pages(void) | |
715 | { | |
716 | return global_page_state(NR_FILE_DIRTY) + | |
717 | global_page_state(NR_UNSTABLE_NFS) + | |
718 | get_nr_dirty_inodes(); | |
719 | } | |
720 | ||
721 | static long wb_check_old_data_flush(struct bdi_writeback *wb) | |
722 | { | |
723 | unsigned long expired; | |
724 | long nr_pages; | |
725 | ||
726 | /* | |
727 | * When set to zero, disable periodic writeback | |
728 | */ | |
729 | if (!dirty_writeback_interval) | |
730 | return 0; | |
731 | ||
732 | expired = wb->last_old_flush + | |
733 | msecs_to_jiffies(dirty_writeback_interval * 10); | |
734 | if (time_before(jiffies, expired)) | |
735 | return 0; | |
736 | ||
737 | wb->last_old_flush = jiffies; | |
738 | nr_pages = get_nr_dirty_pages(); | |
739 | ||
740 | if (nr_pages) { | |
741 | struct wb_writeback_work work = { | |
742 | .nr_pages = nr_pages, | |
743 | .sync_mode = WB_SYNC_NONE, | |
744 | .for_kupdate = 1, | |
745 | .range_cyclic = 1, | |
746 | }; | |
747 | ||
748 | return wb_writeback(wb, &work); | |
749 | } | |
750 | ||
751 | return 0; | |
752 | } | |
753 | ||
754 | /* | |
755 | * Retrieve work items and do the writeback they describe | |
756 | */ | |
757 | long wb_do_writeback(struct bdi_writeback *wb, int force_wait) | |
758 | { | |
759 | struct backing_dev_info *bdi = wb->bdi; | |
760 | struct wb_writeback_work *work; | |
761 | long wrote = 0; | |
762 | ||
763 | set_bit(BDI_writeback_running, &wb->bdi->state); | |
764 | while ((work = get_next_work_item(bdi)) != NULL) { | |
765 | /* | |
766 | * Override sync mode, in case we must wait for completion | |
767 | * because this thread is exiting now. | |
768 | */ | |
769 | if (force_wait) | |
770 | work->sync_mode = WB_SYNC_ALL; | |
771 | ||
772 | trace_writeback_exec(bdi, work); | |
773 | ||
774 | wrote += wb_writeback(wb, work); | |
775 | ||
776 | /* | |
777 | * Notify the caller of completion if this is a synchronous | |
778 | * work item, otherwise just free it. | |
779 | */ | |
780 | if (work->done) | |
781 | complete(work->done); | |
782 | else | |
783 | kfree(work); | |
784 | } | |
785 | ||
786 | /* | |
787 | * Check for periodic writeback, kupdated() style | |
788 | */ | |
789 | wrote += wb_check_old_data_flush(wb); | |
790 | clear_bit(BDI_writeback_running, &wb->bdi->state); | |
791 | ||
792 | return wrote; | |
793 | } | |
794 | ||
795 | /* | |
796 | * Handle writeback of dirty data for the device backed by this bdi. Also | |
797 | * wakes up periodically and does kupdated style flushing. | |
798 | */ | |
799 | int bdi_writeback_thread(void *data) | |
800 | { | |
801 | struct bdi_writeback *wb = data; | |
802 | struct backing_dev_info *bdi = wb->bdi; | |
803 | long pages_written; | |
804 | ||
805 | current->flags |= PF_SWAPWRITE; | |
806 | set_freezable(); | |
807 | wb->last_active = jiffies; | |
808 | ||
809 | /* | |
810 | * Our parent may run at a different priority, just set us to normal | |
811 | */ | |
812 | set_user_nice(current, 0); | |
813 | ||
814 | trace_writeback_thread_start(bdi); | |
815 | ||
816 | while (!kthread_should_stop()) { | |
817 | /* | |
818 | * Remove own delayed wake-up timer, since we are already awake | |
819 | * and we'll take care of the preriodic write-back. | |
820 | */ | |
821 | del_timer(&wb->wakeup_timer); | |
822 | ||
823 | pages_written = wb_do_writeback(wb, 0); | |
824 | ||
825 | trace_writeback_pages_written(pages_written); | |
826 | ||
827 | if (pages_written) | |
828 | wb->last_active = jiffies; | |
829 | ||
830 | set_current_state(TASK_INTERRUPTIBLE); | |
831 | if (!list_empty(&bdi->work_list) || kthread_should_stop()) { | |
832 | __set_current_state(TASK_RUNNING); | |
833 | continue; | |
834 | } | |
835 | ||
836 | if (wb_has_dirty_io(wb) && dirty_writeback_interval) | |
837 | schedule_timeout(msecs_to_jiffies(dirty_writeback_interval * 10)); | |
838 | else { | |
839 | /* | |
840 | * We have nothing to do, so can go sleep without any | |
841 | * timeout and save power. When a work is queued or | |
842 | * something is made dirty - we will be woken up. | |
843 | */ | |
844 | schedule(); | |
845 | } | |
846 | ||
847 | try_to_freeze(); | |
848 | } | |
849 | ||
850 | /* Flush any work that raced with us exiting */ | |
851 | if (!list_empty(&bdi->work_list)) | |
852 | wb_do_writeback(wb, 1); | |
853 | ||
854 | trace_writeback_thread_stop(bdi); | |
855 | return 0; | |
856 | } | |
857 | ||
858 | ||
859 | /* | |
860 | * Start writeback of `nr_pages' pages. If `nr_pages' is zero, write back | |
861 | * the whole world. | |
862 | */ | |
863 | void wakeup_flusher_threads(long nr_pages) | |
864 | { | |
865 | struct backing_dev_info *bdi; | |
866 | ||
867 | if (!nr_pages) { | |
868 | nr_pages = global_page_state(NR_FILE_DIRTY) + | |
869 | global_page_state(NR_UNSTABLE_NFS); | |
870 | } | |
871 | ||
872 | rcu_read_lock(); | |
873 | list_for_each_entry_rcu(bdi, &bdi_list, bdi_list) { | |
874 | if (!bdi_has_dirty_io(bdi)) | |
875 | continue; | |
876 | __bdi_start_writeback(bdi, nr_pages, false, false); | |
877 | } | |
878 | rcu_read_unlock(); | |
879 | } | |
880 | ||
881 | static noinline void block_dump___mark_inode_dirty(struct inode *inode) | |
882 | { | |
883 | if (inode->i_ino || strcmp(inode->i_sb->s_id, "bdev")) { | |
884 | struct dentry *dentry; | |
885 | const char *name = "?"; | |
886 | ||
887 | dentry = d_find_alias(inode); | |
888 | if (dentry) { | |
889 | spin_lock(&dentry->d_lock); | |
890 | name = (const char *) dentry->d_name.name; | |
891 | } | |
892 | printk(KERN_DEBUG | |
893 | "%s(%d): dirtied inode %lu (%s) on %s\n", | |
894 | current->comm, task_pid_nr(current), inode->i_ino, | |
895 | name, inode->i_sb->s_id); | |
896 | if (dentry) { | |
897 | spin_unlock(&dentry->d_lock); | |
898 | dput(dentry); | |
899 | } | |
900 | } | |
901 | } | |
902 | ||
903 | /** | |
904 | * __mark_inode_dirty - internal function | |
905 | * @inode: inode to mark | |
906 | * @flags: what kind of dirty (i.e. I_DIRTY_SYNC) | |
907 | * Mark an inode as dirty. Callers should use mark_inode_dirty or | |
908 | * mark_inode_dirty_sync. | |
909 | * | |
910 | * Put the inode on the super block's dirty list. | |
911 | * | |
912 | * CAREFUL! We mark it dirty unconditionally, but move it onto the | |
913 | * dirty list only if it is hashed or if it refers to a blockdev. | |
914 | * If it was not hashed, it will never be added to the dirty list | |
915 | * even if it is later hashed, as it will have been marked dirty already. | |
916 | * | |
917 | * In short, make sure you hash any inodes _before_ you start marking | |
918 | * them dirty. | |
919 | * | |
920 | * This function *must* be atomic for the I_DIRTY_PAGES case - | |
921 | * set_page_dirty() is called under spinlock in several places. | |
922 | * | |
923 | * Note that for blockdevs, inode->dirtied_when represents the dirtying time of | |
924 | * the block-special inode (/dev/hda1) itself. And the ->dirtied_when field of | |
925 | * the kernel-internal blockdev inode represents the dirtying time of the | |
926 | * blockdev's pages. This is why for I_DIRTY_PAGES we always use | |
927 | * page->mapping->host, so the page-dirtying time is recorded in the internal | |
928 | * blockdev inode. | |
929 | */ | |
930 | void __mark_inode_dirty(struct inode *inode, int flags) | |
931 | { | |
932 | struct super_block *sb = inode->i_sb; | |
933 | struct backing_dev_info *bdi = NULL; | |
934 | bool wakeup_bdi = false; | |
935 | ||
936 | /* | |
937 | * Don't do this for I_DIRTY_PAGES - that doesn't actually | |
938 | * dirty the inode itself | |
939 | */ | |
940 | if (flags & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) { | |
941 | if (sb->s_op->dirty_inode) | |
942 | sb->s_op->dirty_inode(inode); | |
943 | } | |
944 | ||
945 | /* | |
946 | * make sure that changes are seen by all cpus before we test i_state | |
947 | * -- mikulas | |
948 | */ | |
949 | smp_mb(); | |
950 | ||
951 | /* avoid the locking if we can */ | |
952 | if ((inode->i_state & flags) == flags) | |
953 | return; | |
954 | ||
955 | if (unlikely(block_dump)) | |
956 | block_dump___mark_inode_dirty(inode); | |
957 | ||
958 | spin_lock(&inode_lock); | |
959 | if ((inode->i_state & flags) != flags) { | |
960 | const int was_dirty = inode->i_state & I_DIRTY; | |
961 | ||
962 | inode->i_state |= flags; | |
963 | ||
964 | /* | |
965 | * If the inode is being synced, just update its dirty state. | |
966 | * The unlocker will place the inode on the appropriate | |
967 | * superblock list, based upon its state. | |
968 | */ | |
969 | if (inode->i_state & I_SYNC) | |
970 | goto out; | |
971 | ||
972 | /* | |
973 | * Only add valid (hashed) inodes to the superblock's | |
974 | * dirty list. Add blockdev inodes as well. | |
975 | */ | |
976 | if (!S_ISBLK(inode->i_mode)) { | |
977 | if (inode_unhashed(inode)) | |
978 | goto out; | |
979 | } | |
980 | if (inode->i_state & I_FREEING) | |
981 | goto out; | |
982 | ||
983 | /* | |
984 | * If the inode was already on b_dirty/b_io/b_more_io, don't | |
985 | * reposition it (that would break b_dirty time-ordering). | |
986 | */ | |
987 | if (!was_dirty) { | |
988 | bdi = inode_to_bdi(inode); | |
989 | ||
990 | if (bdi_cap_writeback_dirty(bdi)) { | |
991 | WARN(!test_bit(BDI_registered, &bdi->state), | |
992 | "bdi-%s not registered\n", bdi->name); | |
993 | ||
994 | /* | |
995 | * If this is the first dirty inode for this | |
996 | * bdi, we have to wake-up the corresponding | |
997 | * bdi thread to make sure background | |
998 | * write-back happens later. | |
999 | */ | |
1000 | if (!wb_has_dirty_io(&bdi->wb)) | |
1001 | wakeup_bdi = true; | |
1002 | } | |
1003 | ||
1004 | inode->dirtied_when = jiffies; | |
1005 | list_move(&inode->i_wb_list, &bdi->wb.b_dirty); | |
1006 | } | |
1007 | } | |
1008 | out: | |
1009 | spin_unlock(&inode_lock); | |
1010 | ||
1011 | if (wakeup_bdi) | |
1012 | bdi_wakeup_thread_delayed(bdi); | |
1013 | } | |
1014 | EXPORT_SYMBOL(__mark_inode_dirty); | |
1015 | ||
1016 | /* | |
1017 | * Write out a superblock's list of dirty inodes. A wait will be performed | |
1018 | * upon no inodes, all inodes or the final one, depending upon sync_mode. | |
1019 | * | |
1020 | * If older_than_this is non-NULL, then only write out inodes which | |
1021 | * had their first dirtying at a time earlier than *older_than_this. | |
1022 | * | |
1023 | * If `bdi' is non-zero then we're being asked to writeback a specific queue. | |
1024 | * This function assumes that the blockdev superblock's inodes are backed by | |
1025 | * a variety of queues, so all inodes are searched. For other superblocks, | |
1026 | * assume that all inodes are backed by the same queue. | |
1027 | * | |
1028 | * The inodes to be written are parked on bdi->b_io. They are moved back onto | |
1029 | * bdi->b_dirty as they are selected for writing. This way, none can be missed | |
1030 | * on the writer throttling path, and we get decent balancing between many | |
1031 | * throttled threads: we don't want them all piling up on inode_sync_wait. | |
1032 | */ | |
1033 | static void wait_sb_inodes(struct super_block *sb) | |
1034 | { | |
1035 | struct inode *inode, *old_inode = NULL; | |
1036 | ||
1037 | /* | |
1038 | * We need to be protected against the filesystem going from | |
1039 | * r/o to r/w or vice versa. | |
1040 | */ | |
1041 | WARN_ON(!rwsem_is_locked(&sb->s_umount)); | |
1042 | ||
1043 | spin_lock(&inode_lock); | |
1044 | ||
1045 | /* | |
1046 | * Data integrity sync. Must wait for all pages under writeback, | |
1047 | * because there may have been pages dirtied before our sync | |
1048 | * call, but which had writeout started before we write it out. | |
1049 | * In which case, the inode may not be on the dirty list, but | |
1050 | * we still have to wait for that writeout. | |
1051 | */ | |
1052 | list_for_each_entry(inode, &sb->s_inodes, i_sb_list) { | |
1053 | struct address_space *mapping; | |
1054 | ||
1055 | if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) | |
1056 | continue; | |
1057 | mapping = inode->i_mapping; | |
1058 | if (mapping->nrpages == 0) | |
1059 | continue; | |
1060 | __iget(inode); | |
1061 | spin_unlock(&inode_lock); | |
1062 | /* | |
1063 | * We hold a reference to 'inode' so it couldn't have | |
1064 | * been removed from s_inodes list while we dropped the | |
1065 | * inode_lock. We cannot iput the inode now as we can | |
1066 | * be holding the last reference and we cannot iput it | |
1067 | * under inode_lock. So we keep the reference and iput | |
1068 | * it later. | |
1069 | */ | |
1070 | iput(old_inode); | |
1071 | old_inode = inode; | |
1072 | ||
1073 | filemap_fdatawait(mapping); | |
1074 | ||
1075 | cond_resched(); | |
1076 | ||
1077 | spin_lock(&inode_lock); | |
1078 | } | |
1079 | spin_unlock(&inode_lock); | |
1080 | iput(old_inode); | |
1081 | } | |
1082 | ||
1083 | /** | |
1084 | * writeback_inodes_sb - writeback dirty inodes from given super_block | |
1085 | * @sb: the superblock | |
1086 | * | |
1087 | * Start writeback on some inodes on this super_block. No guarantees are made | |
1088 | * on how many (if any) will be written, and this function does not wait | |
1089 | * for IO completion of submitted IO. The number of pages submitted is | |
1090 | * returned. | |
1091 | */ | |
1092 | void writeback_inodes_sb(struct super_block *sb) | |
1093 | { | |
1094 | DECLARE_COMPLETION_ONSTACK(done); | |
1095 | struct wb_writeback_work work = { | |
1096 | .sb = sb, | |
1097 | .sync_mode = WB_SYNC_NONE, | |
1098 | .done = &done, | |
1099 | }; | |
1100 | ||
1101 | WARN_ON(!rwsem_is_locked(&sb->s_umount)); | |
1102 | ||
1103 | work.nr_pages = get_nr_dirty_pages(); | |
1104 | ||
1105 | bdi_queue_work(sb->s_bdi, &work); | |
1106 | wait_for_completion(&done); | |
1107 | } | |
1108 | EXPORT_SYMBOL(writeback_inodes_sb); | |
1109 | ||
1110 | /** | |
1111 | * writeback_inodes_sb_if_idle - start writeback if none underway | |
1112 | * @sb: the superblock | |
1113 | * | |
1114 | * Invoke writeback_inodes_sb if no writeback is currently underway. | |
1115 | * Returns 1 if writeback was started, 0 if not. | |
1116 | */ | |
1117 | int writeback_inodes_sb_if_idle(struct super_block *sb) | |
1118 | { | |
1119 | if (!writeback_in_progress(sb->s_bdi)) { | |
1120 | down_read(&sb->s_umount); | |
1121 | writeback_inodes_sb(sb); | |
1122 | up_read(&sb->s_umount); | |
1123 | return 1; | |
1124 | } else | |
1125 | return 0; | |
1126 | } | |
1127 | EXPORT_SYMBOL(writeback_inodes_sb_if_idle); | |
1128 | ||
1129 | /** | |
1130 | * sync_inodes_sb - sync sb inode pages | |
1131 | * @sb: the superblock | |
1132 | * | |
1133 | * This function writes and waits on any dirty inode belonging to this | |
1134 | * super_block. The number of pages synced is returned. | |
1135 | */ | |
1136 | void sync_inodes_sb(struct super_block *sb) | |
1137 | { | |
1138 | DECLARE_COMPLETION_ONSTACK(done); | |
1139 | struct wb_writeback_work work = { | |
1140 | .sb = sb, | |
1141 | .sync_mode = WB_SYNC_ALL, | |
1142 | .nr_pages = LONG_MAX, | |
1143 | .range_cyclic = 0, | |
1144 | .done = &done, | |
1145 | }; | |
1146 | ||
1147 | WARN_ON(!rwsem_is_locked(&sb->s_umount)); | |
1148 | ||
1149 | bdi_queue_work(sb->s_bdi, &work); | |
1150 | wait_for_completion(&done); | |
1151 | ||
1152 | wait_sb_inodes(sb); | |
1153 | } | |
1154 | EXPORT_SYMBOL(sync_inodes_sb); | |
1155 | ||
1156 | /** | |
1157 | * write_inode_now - write an inode to disk | |
1158 | * @inode: inode to write to disk | |
1159 | * @sync: whether the write should be synchronous or not | |
1160 | * | |
1161 | * This function commits an inode to disk immediately if it is dirty. This is | |
1162 | * primarily needed by knfsd. | |
1163 | * | |
1164 | * The caller must either have a ref on the inode or must have set I_WILL_FREE. | |
1165 | */ | |
1166 | int write_inode_now(struct inode *inode, int sync) | |
1167 | { | |
1168 | int ret; | |
1169 | struct writeback_control wbc = { | |
1170 | .nr_to_write = LONG_MAX, | |
1171 | .sync_mode = sync ? WB_SYNC_ALL : WB_SYNC_NONE, | |
1172 | .range_start = 0, | |
1173 | .range_end = LLONG_MAX, | |
1174 | }; | |
1175 | ||
1176 | if (!mapping_cap_writeback_dirty(inode->i_mapping)) | |
1177 | wbc.nr_to_write = 0; | |
1178 | ||
1179 | might_sleep(); | |
1180 | spin_lock(&inode_lock); | |
1181 | ret = writeback_single_inode(inode, &wbc); | |
1182 | spin_unlock(&inode_lock); | |
1183 | if (sync) | |
1184 | inode_sync_wait(inode); | |
1185 | return ret; | |
1186 | } | |
1187 | EXPORT_SYMBOL(write_inode_now); | |
1188 | ||
1189 | /** | |
1190 | * sync_inode - write an inode and its pages to disk. | |
1191 | * @inode: the inode to sync | |
1192 | * @wbc: controls the writeback mode | |
1193 | * | |
1194 | * sync_inode() will write an inode and its pages to disk. It will also | |
1195 | * correctly update the inode on its superblock's dirty inode lists and will | |
1196 | * update inode->i_state. | |
1197 | * | |
1198 | * The caller must have a ref on the inode. | |
1199 | */ | |
1200 | int sync_inode(struct inode *inode, struct writeback_control *wbc) | |
1201 | { | |
1202 | int ret; | |
1203 | ||
1204 | spin_lock(&inode_lock); | |
1205 | ret = writeback_single_inode(inode, wbc); | |
1206 | spin_unlock(&inode_lock); | |
1207 | return ret; | |
1208 | } | |
1209 | EXPORT_SYMBOL(sync_inode); | |
1210 | ||
1211 | /** | |
1212 | * sync_inode - write an inode to disk | |
1213 | * @inode: the inode to sync | |
1214 | * @wait: wait for I/O to complete. | |
1215 | * | |
1216 | * Write an inode to disk and adjust it's dirty state after completion. | |
1217 | * | |
1218 | * Note: only writes the actual inode, no associated data or other metadata. | |
1219 | */ | |
1220 | int sync_inode_metadata(struct inode *inode, int wait) | |
1221 | { | |
1222 | struct writeback_control wbc = { | |
1223 | .sync_mode = wait ? WB_SYNC_ALL : WB_SYNC_NONE, | |
1224 | .nr_to_write = 0, /* metadata-only */ | |
1225 | }; | |
1226 | ||
1227 | return sync_inode(inode, &wbc); | |
1228 | } | |
1229 | EXPORT_SYMBOL(sync_inode_metadata); |