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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 akpm@zip.com.au | |
12 | * Split out of fs/inode.c | |
13 | * Additions for address_space-based writeback | |
14 | */ | |
15 | ||
16 | #include <linux/kernel.h> | |
17 | #include <linux/spinlock.h> | |
18 | #include <linux/sched.h> | |
19 | #include <linux/fs.h> | |
20 | #include <linux/mm.h> | |
21 | #include <linux/writeback.h> | |
22 | #include <linux/blkdev.h> | |
23 | #include <linux/backing-dev.h> | |
24 | #include <linux/buffer_head.h> | |
25 | ||
26 | extern struct super_block *blockdev_superblock; | |
27 | ||
28 | /** | |
29 | * __mark_inode_dirty - internal function | |
30 | * @inode: inode to mark | |
31 | * @flags: what kind of dirty (i.e. I_DIRTY_SYNC) | |
32 | * Mark an inode as dirty. Callers should use mark_inode_dirty or | |
33 | * mark_inode_dirty_sync. | |
34 | * | |
35 | * Put the inode on the super block's dirty list. | |
36 | * | |
37 | * CAREFUL! We mark it dirty unconditionally, but move it onto the | |
38 | * dirty list only if it is hashed or if it refers to a blockdev. | |
39 | * If it was not hashed, it will never be added to the dirty list | |
40 | * even if it is later hashed, as it will have been marked dirty already. | |
41 | * | |
42 | * In short, make sure you hash any inodes _before_ you start marking | |
43 | * them dirty. | |
44 | * | |
45 | * This function *must* be atomic for the I_DIRTY_PAGES case - | |
46 | * set_page_dirty() is called under spinlock in several places. | |
47 | * | |
48 | * Note that for blockdevs, inode->dirtied_when represents the dirtying time of | |
49 | * the block-special inode (/dev/hda1) itself. And the ->dirtied_when field of | |
50 | * the kernel-internal blockdev inode represents the dirtying time of the | |
51 | * blockdev's pages. This is why for I_DIRTY_PAGES we always use | |
52 | * page->mapping->host, so the page-dirtying time is recorded in the internal | |
53 | * blockdev inode. | |
54 | */ | |
55 | void __mark_inode_dirty(struct inode *inode, int flags) | |
56 | { | |
57 | struct super_block *sb = inode->i_sb; | |
58 | ||
59 | /* | |
60 | * Don't do this for I_DIRTY_PAGES - that doesn't actually | |
61 | * dirty the inode itself | |
62 | */ | |
63 | if (flags & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) { | |
64 | if (sb->s_op->dirty_inode) | |
65 | sb->s_op->dirty_inode(inode); | |
66 | } | |
67 | ||
68 | /* | |
69 | * make sure that changes are seen by all cpus before we test i_state | |
70 | * -- mikulas | |
71 | */ | |
72 | smp_mb(); | |
73 | ||
74 | /* avoid the locking if we can */ | |
75 | if ((inode->i_state & flags) == flags) | |
76 | return; | |
77 | ||
78 | if (unlikely(block_dump)) { | |
79 | struct dentry *dentry = NULL; | |
80 | const char *name = "?"; | |
81 | ||
82 | if (!list_empty(&inode->i_dentry)) { | |
83 | dentry = list_entry(inode->i_dentry.next, | |
84 | struct dentry, d_alias); | |
85 | if (dentry && dentry->d_name.name) | |
86 | name = (const char *) dentry->d_name.name; | |
87 | } | |
88 | ||
89 | if (inode->i_ino || strcmp(inode->i_sb->s_id, "bdev")) | |
90 | printk(KERN_DEBUG | |
91 | "%s(%d): dirtied inode %lu (%s) on %s\n", | |
92 | current->comm, current->pid, inode->i_ino, | |
93 | name, inode->i_sb->s_id); | |
94 | } | |
95 | ||
96 | spin_lock(&inode_lock); | |
97 | if ((inode->i_state & flags) != flags) { | |
98 | const int was_dirty = inode->i_state & I_DIRTY; | |
99 | ||
100 | inode->i_state |= flags; | |
101 | ||
102 | /* | |
103 | * If the inode is locked, just update its dirty state. | |
104 | * The unlocker will place the inode on the appropriate | |
105 | * superblock list, based upon its state. | |
106 | */ | |
107 | if (inode->i_state & I_LOCK) | |
108 | goto out; | |
109 | ||
110 | /* | |
111 | * Only add valid (hashed) inodes to the superblock's | |
112 | * dirty list. Add blockdev inodes as well. | |
113 | */ | |
114 | if (!S_ISBLK(inode->i_mode)) { | |
115 | if (hlist_unhashed(&inode->i_hash)) | |
116 | goto out; | |
117 | } | |
118 | if (inode->i_state & (I_FREEING|I_CLEAR)) | |
119 | goto out; | |
120 | ||
121 | /* | |
122 | * If the inode was already on s_dirty or s_io, don't | |
123 | * reposition it (that would break s_dirty time-ordering). | |
124 | */ | |
125 | if (!was_dirty) { | |
126 | inode->dirtied_when = jiffies; | |
127 | list_move(&inode->i_list, &sb->s_dirty); | |
128 | } | |
129 | } | |
130 | out: | |
131 | spin_unlock(&inode_lock); | |
132 | } | |
133 | ||
134 | EXPORT_SYMBOL(__mark_inode_dirty); | |
135 | ||
136 | static int write_inode(struct inode *inode, int sync) | |
137 | { | |
138 | if (inode->i_sb->s_op->write_inode && !is_bad_inode(inode)) | |
139 | return inode->i_sb->s_op->write_inode(inode, sync); | |
140 | return 0; | |
141 | } | |
142 | ||
143 | /* | |
144 | * Write a single inode's dirty pages and inode data out to disk. | |
145 | * If `wait' is set, wait on the writeout. | |
146 | * | |
147 | * The whole writeout design is quite complex and fragile. We want to avoid | |
148 | * starvation of particular inodes when others are being redirtied, prevent | |
149 | * livelocks, etc. | |
150 | * | |
151 | * Called under inode_lock. | |
152 | */ | |
153 | static int | |
154 | __sync_single_inode(struct inode *inode, struct writeback_control *wbc) | |
155 | { | |
156 | unsigned dirty; | |
157 | struct address_space *mapping = inode->i_mapping; | |
158 | struct super_block *sb = inode->i_sb; | |
159 | int wait = wbc->sync_mode == WB_SYNC_ALL; | |
160 | int ret; | |
161 | ||
162 | BUG_ON(inode->i_state & I_LOCK); | |
163 | ||
164 | /* Set I_LOCK, reset I_DIRTY */ | |
165 | dirty = inode->i_state & I_DIRTY; | |
166 | inode->i_state |= I_LOCK; | |
167 | inode->i_state &= ~I_DIRTY; | |
168 | ||
169 | spin_unlock(&inode_lock); | |
170 | ||
171 | ret = do_writepages(mapping, wbc); | |
172 | ||
173 | /* Don't write the inode if only I_DIRTY_PAGES was set */ | |
174 | if (dirty & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) { | |
175 | int err = write_inode(inode, wait); | |
176 | if (ret == 0) | |
177 | ret = err; | |
178 | } | |
179 | ||
180 | if (wait) { | |
181 | int err = filemap_fdatawait(mapping); | |
182 | if (ret == 0) | |
183 | ret = err; | |
184 | } | |
185 | ||
186 | spin_lock(&inode_lock); | |
187 | inode->i_state &= ~I_LOCK; | |
188 | if (!(inode->i_state & I_FREEING)) { | |
189 | if (!(inode->i_state & I_DIRTY) && | |
190 | mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) { | |
191 | /* | |
192 | * We didn't write back all the pages. nfs_writepages() | |
193 | * sometimes bales out without doing anything. Redirty | |
194 | * the inode. It is still on sb->s_io. | |
195 | */ | |
196 | if (wbc->for_kupdate) { | |
197 | /* | |
198 | * For the kupdate function we leave the inode | |
199 | * at the head of sb_dirty so it will get more | |
200 | * writeout as soon as the queue becomes | |
201 | * uncongested. | |
202 | */ | |
203 | inode->i_state |= I_DIRTY_PAGES; | |
204 | list_move_tail(&inode->i_list, &sb->s_dirty); | |
205 | } else { | |
206 | /* | |
207 | * Otherwise fully redirty the inode so that | |
208 | * other inodes on this superblock will get some | |
209 | * writeout. Otherwise heavy writing to one | |
210 | * file would indefinitely suspend writeout of | |
211 | * all the other files. | |
212 | */ | |
213 | inode->i_state |= I_DIRTY_PAGES; | |
214 | inode->dirtied_when = jiffies; | |
215 | list_move(&inode->i_list, &sb->s_dirty); | |
216 | } | |
217 | } else if (inode->i_state & I_DIRTY) { | |
218 | /* | |
219 | * Someone redirtied the inode while were writing back | |
220 | * the pages. | |
221 | */ | |
222 | list_move(&inode->i_list, &sb->s_dirty); | |
223 | } else if (atomic_read(&inode->i_count)) { | |
224 | /* | |
225 | * The inode is clean, inuse | |
226 | */ | |
227 | list_move(&inode->i_list, &inode_in_use); | |
228 | } else { | |
229 | /* | |
230 | * The inode is clean, unused | |
231 | */ | |
232 | list_move(&inode->i_list, &inode_unused); | |
233 | } | |
234 | } | |
235 | wake_up_inode(inode); | |
236 | return ret; | |
237 | } | |
238 | ||
239 | /* | |
240 | * Write out an inode's dirty pages. Called under inode_lock. Either the | |
241 | * caller has ref on the inode (either via __iget or via syscall against an fd) | |
242 | * or the inode has I_WILL_FREE set (via generic_forget_inode) | |
243 | */ | |
244 | static int | |
245 | __writeback_single_inode(struct inode *inode, struct writeback_control *wbc) | |
246 | { | |
247 | wait_queue_head_t *wqh; | |
248 | ||
249 | if (!atomic_read(&inode->i_count)) | |
250 | WARN_ON(!(inode->i_state & (I_WILL_FREE|I_FREEING))); | |
251 | else | |
252 | WARN_ON(inode->i_state & I_WILL_FREE); | |
253 | ||
254 | if ((wbc->sync_mode != WB_SYNC_ALL) && (inode->i_state & I_LOCK)) { | |
255 | list_move(&inode->i_list, &inode->i_sb->s_dirty); | |
256 | return 0; | |
257 | } | |
258 | ||
259 | /* | |
260 | * It's a data-integrity sync. We must wait. | |
261 | */ | |
262 | if (inode->i_state & I_LOCK) { | |
263 | DEFINE_WAIT_BIT(wq, &inode->i_state, __I_LOCK); | |
264 | ||
265 | wqh = bit_waitqueue(&inode->i_state, __I_LOCK); | |
266 | do { | |
267 | spin_unlock(&inode_lock); | |
268 | __wait_on_bit(wqh, &wq, inode_wait, | |
269 | TASK_UNINTERRUPTIBLE); | |
270 | spin_lock(&inode_lock); | |
271 | } while (inode->i_state & I_LOCK); | |
272 | } | |
273 | return __sync_single_inode(inode, wbc); | |
274 | } | |
275 | ||
276 | /* | |
277 | * Write out a superblock's list of dirty inodes. A wait will be performed | |
278 | * upon no inodes, all inodes or the final one, depending upon sync_mode. | |
279 | * | |
280 | * If older_than_this is non-NULL, then only write out inodes which | |
281 | * had their first dirtying at a time earlier than *older_than_this. | |
282 | * | |
283 | * If we're a pdlfush thread, then implement pdflush collision avoidance | |
284 | * against the entire list. | |
285 | * | |
286 | * WB_SYNC_HOLD is a hack for sys_sync(): reattach the inode to sb->s_dirty so | |
287 | * that it can be located for waiting on in __writeback_single_inode(). | |
288 | * | |
289 | * Called under inode_lock. | |
290 | * | |
291 | * If `bdi' is non-zero then we're being asked to writeback a specific queue. | |
292 | * This function assumes that the blockdev superblock's inodes are backed by | |
293 | * a variety of queues, so all inodes are searched. For other superblocks, | |
294 | * assume that all inodes are backed by the same queue. | |
295 | * | |
296 | * FIXME: this linear search could get expensive with many fileystems. But | |
297 | * how to fix? We need to go from an address_space to all inodes which share | |
298 | * a queue with that address_space. (Easy: have a global "dirty superblocks" | |
299 | * list). | |
300 | * | |
301 | * The inodes to be written are parked on sb->s_io. They are moved back onto | |
302 | * sb->s_dirty as they are selected for writing. This way, none can be missed | |
303 | * on the writer throttling path, and we get decent balancing between many | |
304 | * throttled threads: we don't want them all piling up on __wait_on_inode. | |
305 | */ | |
306 | static void | |
307 | sync_sb_inodes(struct super_block *sb, struct writeback_control *wbc) | |
308 | { | |
309 | const unsigned long start = jiffies; /* livelock avoidance */ | |
310 | ||
311 | if (!wbc->for_kupdate || list_empty(&sb->s_io)) | |
312 | list_splice_init(&sb->s_dirty, &sb->s_io); | |
313 | ||
314 | while (!list_empty(&sb->s_io)) { | |
315 | struct inode *inode = list_entry(sb->s_io.prev, | |
316 | struct inode, i_list); | |
317 | struct address_space *mapping = inode->i_mapping; | |
318 | struct backing_dev_info *bdi = mapping->backing_dev_info; | |
319 | long pages_skipped; | |
320 | ||
321 | if (!bdi_cap_writeback_dirty(bdi)) { | |
322 | list_move(&inode->i_list, &sb->s_dirty); | |
323 | if (sb == blockdev_superblock) { | |
324 | /* | |
325 | * Dirty memory-backed blockdev: the ramdisk | |
326 | * driver does this. Skip just this inode | |
327 | */ | |
328 | continue; | |
329 | } | |
330 | /* | |
331 | * Dirty memory-backed inode against a filesystem other | |
332 | * than the kernel-internal bdev filesystem. Skip the | |
333 | * entire superblock. | |
334 | */ | |
335 | break; | |
336 | } | |
337 | ||
338 | if (wbc->nonblocking && bdi_write_congested(bdi)) { | |
339 | wbc->encountered_congestion = 1; | |
340 | if (sb != blockdev_superblock) | |
341 | break; /* Skip a congested fs */ | |
342 | list_move(&inode->i_list, &sb->s_dirty); | |
343 | continue; /* Skip a congested blockdev */ | |
344 | } | |
345 | ||
346 | if (wbc->bdi && bdi != wbc->bdi) { | |
347 | if (sb != blockdev_superblock) | |
348 | break; /* fs has the wrong queue */ | |
349 | list_move(&inode->i_list, &sb->s_dirty); | |
350 | continue; /* blockdev has wrong queue */ | |
351 | } | |
352 | ||
353 | /* Was this inode dirtied after sync_sb_inodes was called? */ | |
354 | if (time_after(inode->dirtied_when, start)) | |
355 | break; | |
356 | ||
357 | /* Was this inode dirtied too recently? */ | |
358 | if (wbc->older_than_this && time_after(inode->dirtied_when, | |
359 | *wbc->older_than_this)) | |
360 | break; | |
361 | ||
362 | /* Is another pdflush already flushing this queue? */ | |
363 | if (current_is_pdflush() && !writeback_acquire(bdi)) | |
364 | break; | |
365 | ||
366 | BUG_ON(inode->i_state & I_FREEING); | |
367 | __iget(inode); | |
368 | pages_skipped = wbc->pages_skipped; | |
369 | __writeback_single_inode(inode, wbc); | |
370 | if (wbc->sync_mode == WB_SYNC_HOLD) { | |
371 | inode->dirtied_when = jiffies; | |
372 | list_move(&inode->i_list, &sb->s_dirty); | |
373 | } | |
374 | if (current_is_pdflush()) | |
375 | writeback_release(bdi); | |
376 | if (wbc->pages_skipped != pages_skipped) { | |
377 | /* | |
378 | * writeback is not making progress due to locked | |
379 | * buffers. Skip this inode for now. | |
380 | */ | |
381 | list_move(&inode->i_list, &sb->s_dirty); | |
382 | } | |
383 | spin_unlock(&inode_lock); | |
384 | iput(inode); | |
385 | cond_resched(); | |
386 | spin_lock(&inode_lock); | |
387 | if (wbc->nr_to_write <= 0) | |
388 | break; | |
389 | } | |
390 | return; /* Leave any unwritten inodes on s_io */ | |
391 | } | |
392 | ||
393 | /* | |
394 | * Start writeback of dirty pagecache data against all unlocked inodes. | |
395 | * | |
396 | * Note: | |
397 | * We don't need to grab a reference to superblock here. If it has non-empty | |
398 | * ->s_dirty it's hadn't been killed yet and kill_super() won't proceed | |
399 | * past sync_inodes_sb() until both the ->s_dirty and ->s_io lists are | |
400 | * empty. Since __sync_single_inode() regains inode_lock before it finally moves | |
401 | * inode from superblock lists we are OK. | |
402 | * | |
403 | * If `older_than_this' is non-zero then only flush inodes which have a | |
404 | * flushtime older than *older_than_this. | |
405 | * | |
406 | * If `bdi' is non-zero then we will scan the first inode against each | |
407 | * superblock until we find the matching ones. One group will be the dirty | |
408 | * inodes against a filesystem. Then when we hit the dummy blockdev superblock, | |
409 | * sync_sb_inodes will seekout the blockdev which matches `bdi'. Maybe not | |
410 | * super-efficient but we're about to do a ton of I/O... | |
411 | */ | |
412 | void | |
413 | writeback_inodes(struct writeback_control *wbc) | |
414 | { | |
415 | struct super_block *sb; | |
416 | ||
417 | might_sleep(); | |
418 | spin_lock(&sb_lock); | |
419 | restart: | |
420 | sb = sb_entry(super_blocks.prev); | |
421 | for (; sb != sb_entry(&super_blocks); sb = sb_entry(sb->s_list.prev)) { | |
422 | if (!list_empty(&sb->s_dirty) || !list_empty(&sb->s_io)) { | |
423 | /* we're making our own get_super here */ | |
424 | sb->s_count++; | |
425 | spin_unlock(&sb_lock); | |
426 | /* | |
427 | * If we can't get the readlock, there's no sense in | |
428 | * waiting around, most of the time the FS is going to | |
429 | * be unmounted by the time it is released. | |
430 | */ | |
431 | if (down_read_trylock(&sb->s_umount)) { | |
432 | if (sb->s_root) { | |
433 | spin_lock(&inode_lock); | |
434 | sync_sb_inodes(sb, wbc); | |
435 | spin_unlock(&inode_lock); | |
436 | } | |
437 | up_read(&sb->s_umount); | |
438 | } | |
439 | spin_lock(&sb_lock); | |
440 | if (__put_super_and_need_restart(sb)) | |
441 | goto restart; | |
442 | } | |
443 | if (wbc->nr_to_write <= 0) | |
444 | break; | |
445 | } | |
446 | spin_unlock(&sb_lock); | |
447 | } | |
448 | ||
449 | /* | |
450 | * writeback and wait upon the filesystem's dirty inodes. The caller will | |
451 | * do this in two passes - one to write, and one to wait. WB_SYNC_HOLD is | |
452 | * used to park the written inodes on sb->s_dirty for the wait pass. | |
453 | * | |
454 | * A finite limit is set on the number of pages which will be written. | |
455 | * To prevent infinite livelock of sys_sync(). | |
456 | * | |
457 | * We add in the number of potentially dirty inodes, because each inode write | |
458 | * can dirty pagecache in the underlying blockdev. | |
459 | */ | |
460 | void sync_inodes_sb(struct super_block *sb, int wait) | |
461 | { | |
462 | struct writeback_control wbc = { | |
463 | .sync_mode = wait ? WB_SYNC_ALL : WB_SYNC_HOLD, | |
464 | }; | |
465 | unsigned long nr_dirty = read_page_state(nr_dirty); | |
466 | unsigned long nr_unstable = read_page_state(nr_unstable); | |
467 | ||
468 | wbc.nr_to_write = nr_dirty + nr_unstable + | |
469 | (inodes_stat.nr_inodes - inodes_stat.nr_unused) + | |
470 | nr_dirty + nr_unstable; | |
471 | wbc.nr_to_write += wbc.nr_to_write / 2; /* Bit more for luck */ | |
472 | spin_lock(&inode_lock); | |
473 | sync_sb_inodes(sb, &wbc); | |
474 | spin_unlock(&inode_lock); | |
475 | } | |
476 | ||
477 | /* | |
478 | * Rather lame livelock avoidance. | |
479 | */ | |
480 | static void set_sb_syncing(int val) | |
481 | { | |
482 | struct super_block *sb; | |
483 | spin_lock(&sb_lock); | |
484 | sb = sb_entry(super_blocks.prev); | |
485 | for (; sb != sb_entry(&super_blocks); sb = sb_entry(sb->s_list.prev)) { | |
486 | sb->s_syncing = val; | |
487 | } | |
488 | spin_unlock(&sb_lock); | |
489 | } | |
490 | ||
491 | /** | |
492 | * sync_inodes - writes all inodes to disk | |
493 | * @wait: wait for completion | |
494 | * | |
495 | * sync_inodes() goes through each super block's dirty inode list, writes the | |
496 | * inodes out, waits on the writeout and puts the inodes back on the normal | |
497 | * list. | |
498 | * | |
499 | * This is for sys_sync(). fsync_dev() uses the same algorithm. The subtle | |
500 | * part of the sync functions is that the blockdev "superblock" is processed | |
501 | * last. This is because the write_inode() function of a typical fs will | |
502 | * perform no I/O, but will mark buffers in the blockdev mapping as dirty. | |
503 | * What we want to do is to perform all that dirtying first, and then write | |
504 | * back all those inode blocks via the blockdev mapping in one sweep. So the | |
505 | * additional (somewhat redundant) sync_blockdev() calls here are to make | |
506 | * sure that really happens. Because if we call sync_inodes_sb(wait=1) with | |
507 | * outstanding dirty inodes, the writeback goes block-at-a-time within the | |
508 | * filesystem's write_inode(). This is extremely slow. | |
509 | */ | |
510 | static void __sync_inodes(int wait) | |
511 | { | |
512 | struct super_block *sb; | |
513 | ||
514 | spin_lock(&sb_lock); | |
515 | restart: | |
516 | list_for_each_entry(sb, &super_blocks, s_list) { | |
517 | if (sb->s_syncing) | |
518 | continue; | |
519 | sb->s_syncing = 1; | |
520 | sb->s_count++; | |
521 | spin_unlock(&sb_lock); | |
522 | down_read(&sb->s_umount); | |
523 | if (sb->s_root) { | |
524 | sync_inodes_sb(sb, wait); | |
525 | sync_blockdev(sb->s_bdev); | |
526 | } | |
527 | up_read(&sb->s_umount); | |
528 | spin_lock(&sb_lock); | |
529 | if (__put_super_and_need_restart(sb)) | |
530 | goto restart; | |
531 | } | |
532 | spin_unlock(&sb_lock); | |
533 | } | |
534 | ||
535 | void sync_inodes(int wait) | |
536 | { | |
537 | set_sb_syncing(0); | |
538 | __sync_inodes(0); | |
539 | ||
540 | if (wait) { | |
541 | set_sb_syncing(0); | |
542 | __sync_inodes(1); | |
543 | } | |
544 | } | |
545 | ||
546 | /** | |
547 | * write_inode_now - write an inode to disk | |
548 | * @inode: inode to write to disk | |
549 | * @sync: whether the write should be synchronous or not | |
550 | * | |
551 | * This function commits an inode to disk immediately if it is dirty. This is | |
552 | * primarily needed by knfsd. | |
553 | * | |
554 | * The caller must either have a ref on the inode or must have set I_WILL_FREE. | |
555 | */ | |
556 | int write_inode_now(struct inode *inode, int sync) | |
557 | { | |
558 | int ret; | |
559 | struct writeback_control wbc = { | |
560 | .nr_to_write = LONG_MAX, | |
561 | .sync_mode = WB_SYNC_ALL, | |
562 | }; | |
563 | ||
564 | if (!mapping_cap_writeback_dirty(inode->i_mapping)) | |
565 | wbc.nr_to_write = 0; | |
566 | ||
567 | might_sleep(); | |
568 | spin_lock(&inode_lock); | |
569 | ret = __writeback_single_inode(inode, &wbc); | |
570 | spin_unlock(&inode_lock); | |
571 | if (sync) | |
572 | wait_on_inode(inode); | |
573 | return ret; | |
574 | } | |
575 | EXPORT_SYMBOL(write_inode_now); | |
576 | ||
577 | /** | |
578 | * sync_inode - write an inode and its pages to disk. | |
579 | * @inode: the inode to sync | |
580 | * @wbc: controls the writeback mode | |
581 | * | |
582 | * sync_inode() will write an inode and its pages to disk. It will also | |
583 | * correctly update the inode on its superblock's dirty inode lists and will | |
584 | * update inode->i_state. | |
585 | * | |
586 | * The caller must have a ref on the inode. | |
587 | */ | |
588 | int sync_inode(struct inode *inode, struct writeback_control *wbc) | |
589 | { | |
590 | int ret; | |
591 | ||
592 | spin_lock(&inode_lock); | |
593 | ret = __writeback_single_inode(inode, wbc); | |
594 | spin_unlock(&inode_lock); | |
595 | return ret; | |
596 | } | |
597 | EXPORT_SYMBOL(sync_inode); | |
598 | ||
599 | /** | |
600 | * generic_osync_inode - flush all dirty data for a given inode to disk | |
601 | * @inode: inode to write | |
602 | * @mapping: the address_space that should be flushed | |
603 | * @what: what to write and wait upon | |
604 | * | |
605 | * This can be called by file_write functions for files which have the | |
606 | * O_SYNC flag set, to flush dirty writes to disk. | |
607 | * | |
608 | * @what is a bitmask, specifying which part of the inode's data should be | |
609 | * written and waited upon. | |
610 | * | |
611 | * OSYNC_DATA: i_mapping's dirty data | |
612 | * OSYNC_METADATA: the buffers at i_mapping->private_list | |
613 | * OSYNC_INODE: the inode itself | |
614 | */ | |
615 | ||
616 | int generic_osync_inode(struct inode *inode, struct address_space *mapping, int what) | |
617 | { | |
618 | int err = 0; | |
619 | int need_write_inode_now = 0; | |
620 | int err2; | |
621 | ||
622 | current->flags |= PF_SYNCWRITE; | |
623 | if (what & OSYNC_DATA) | |
624 | err = filemap_fdatawrite(mapping); | |
625 | if (what & (OSYNC_METADATA|OSYNC_DATA)) { | |
626 | err2 = sync_mapping_buffers(mapping); | |
627 | if (!err) | |
628 | err = err2; | |
629 | } | |
630 | if (what & OSYNC_DATA) { | |
631 | err2 = filemap_fdatawait(mapping); | |
632 | if (!err) | |
633 | err = err2; | |
634 | } | |
635 | current->flags &= ~PF_SYNCWRITE; | |
636 | ||
637 | spin_lock(&inode_lock); | |
638 | if ((inode->i_state & I_DIRTY) && | |
639 | ((what & OSYNC_INODE) || (inode->i_state & I_DIRTY_DATASYNC))) | |
640 | need_write_inode_now = 1; | |
641 | spin_unlock(&inode_lock); | |
642 | ||
643 | if (need_write_inode_now) { | |
644 | err2 = write_inode_now(inode, 1); | |
645 | if (!err) | |
646 | err = err2; | |
647 | } | |
648 | else | |
649 | wait_on_inode(inode); | |
650 | ||
651 | return err; | |
652 | } | |
653 | ||
654 | EXPORT_SYMBOL(generic_osync_inode); | |
655 | ||
656 | /** | |
657 | * writeback_acquire: attempt to get exclusive writeback access to a device | |
658 | * @bdi: the device's backing_dev_info structure | |
659 | * | |
660 | * It is a waste of resources to have more than one pdflush thread blocked on | |
661 | * a single request queue. Exclusion at the request_queue level is obtained | |
662 | * via a flag in the request_queue's backing_dev_info.state. | |
663 | * | |
664 | * Non-request_queue-backed address_spaces will share default_backing_dev_info, | |
665 | * unless they implement their own. Which is somewhat inefficient, as this | |
666 | * may prevent concurrent writeback against multiple devices. | |
667 | */ | |
668 | int writeback_acquire(struct backing_dev_info *bdi) | |
669 | { | |
670 | return !test_and_set_bit(BDI_pdflush, &bdi->state); | |
671 | } | |
672 | ||
673 | /** | |
674 | * writeback_in_progress: determine whether there is writeback in progress | |
675 | * @bdi: the device's backing_dev_info structure. | |
676 | * | |
677 | * Determine whether there is writeback in progress against a backing device. | |
678 | */ | |
679 | int writeback_in_progress(struct backing_dev_info *bdi) | |
680 | { | |
681 | return test_bit(BDI_pdflush, &bdi->state); | |
682 | } | |
683 | ||
684 | /** | |
685 | * writeback_release: relinquish exclusive writeback access against a device. | |
686 | * @bdi: the device's backing_dev_info structure | |
687 | */ | |
688 | void writeback_release(struct backing_dev_info *bdi) | |
689 | { | |
690 | BUG_ON(!writeback_in_progress(bdi)); | |
691 | clear_bit(BDI_pdflush, &bdi->state); | |
692 | } |