Contents of /alx-src/tags/kernel26-2.6.12-alx-r9/fs/fs-writeback.c
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Wed Mar 4 11:03:09 2009 UTC (15 years, 2 months ago) by niro
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Wed Mar 4 11:03:09 2009 UTC (15 years, 2 months ago) by niro
File MIME type: text/plain
File size: 20142 byte(s)
Tag kernel26-2.6.12-alx-r9
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 | inodes_stat.nr_unused++; |
234 | } |
235 | } |
236 | wake_up_inode(inode); |
237 | return ret; |
238 | } |
239 | |
240 | /* |
241 | * Write out an inode's dirty pages. Called under inode_lock. |
242 | */ |
243 | static int |
244 | __writeback_single_inode(struct inode *inode, |
245 | struct writeback_control *wbc) |
246 | { |
247 | wait_queue_head_t *wqh; |
248 | |
249 | if ((wbc->sync_mode != WB_SYNC_ALL) && (inode->i_state & I_LOCK)) { |
250 | list_move(&inode->i_list, &inode->i_sb->s_dirty); |
251 | return 0; |
252 | } |
253 | |
254 | /* |
255 | * It's a data-integrity sync. We must wait. |
256 | */ |
257 | if (inode->i_state & I_LOCK) { |
258 | DEFINE_WAIT_BIT(wq, &inode->i_state, __I_LOCK); |
259 | |
260 | wqh = bit_waitqueue(&inode->i_state, __I_LOCK); |
261 | do { |
262 | __iget(inode); |
263 | spin_unlock(&inode_lock); |
264 | __wait_on_bit(wqh, &wq, inode_wait, |
265 | TASK_UNINTERRUPTIBLE); |
266 | iput(inode); |
267 | spin_lock(&inode_lock); |
268 | } while (inode->i_state & I_LOCK); |
269 | } |
270 | return __sync_single_inode(inode, wbc); |
271 | } |
272 | |
273 | /* |
274 | * Write out a superblock's list of dirty inodes. A wait will be performed |
275 | * upon no inodes, all inodes or the final one, depending upon sync_mode. |
276 | * |
277 | * If older_than_this is non-NULL, then only write out inodes which |
278 | * had their first dirtying at a time earlier than *older_than_this. |
279 | * |
280 | * If we're a pdlfush thread, then implement pdflush collision avoidance |
281 | * against the entire list. |
282 | * |
283 | * WB_SYNC_HOLD is a hack for sys_sync(): reattach the inode to sb->s_dirty so |
284 | * that it can be located for waiting on in __writeback_single_inode(). |
285 | * |
286 | * Called under inode_lock. |
287 | * |
288 | * If `bdi' is non-zero then we're being asked to writeback a specific queue. |
289 | * This function assumes that the blockdev superblock's inodes are backed by |
290 | * a variety of queues, so all inodes are searched. For other superblocks, |
291 | * assume that all inodes are backed by the same queue. |
292 | * |
293 | * FIXME: this linear search could get expensive with many fileystems. But |
294 | * how to fix? We need to go from an address_space to all inodes which share |
295 | * a queue with that address_space. (Easy: have a global "dirty superblocks" |
296 | * list). |
297 | * |
298 | * The inodes to be written are parked on sb->s_io. They are moved back onto |
299 | * sb->s_dirty as they are selected for writing. This way, none can be missed |
300 | * on the writer throttling path, and we get decent balancing between many |
301 | * throttled threads: we don't want them all piling up on __wait_on_inode. |
302 | */ |
303 | static void |
304 | sync_sb_inodes(struct super_block *sb, struct writeback_control *wbc) |
305 | { |
306 | const unsigned long start = jiffies; /* livelock avoidance */ |
307 | |
308 | if (!wbc->for_kupdate || list_empty(&sb->s_io)) |
309 | list_splice_init(&sb->s_dirty, &sb->s_io); |
310 | |
311 | while (!list_empty(&sb->s_io)) { |
312 | struct inode *inode = list_entry(sb->s_io.prev, |
313 | struct inode, i_list); |
314 | struct address_space *mapping = inode->i_mapping; |
315 | struct backing_dev_info *bdi = mapping->backing_dev_info; |
316 | long pages_skipped; |
317 | |
318 | if (!bdi_cap_writeback_dirty(bdi)) { |
319 | list_move(&inode->i_list, &sb->s_dirty); |
320 | if (sb == blockdev_superblock) { |
321 | /* |
322 | * Dirty memory-backed blockdev: the ramdisk |
323 | * driver does this. Skip just this inode |
324 | */ |
325 | continue; |
326 | } |
327 | /* |
328 | * Dirty memory-backed inode against a filesystem other |
329 | * than the kernel-internal bdev filesystem. Skip the |
330 | * entire superblock. |
331 | */ |
332 | break; |
333 | } |
334 | |
335 | if (wbc->nonblocking && bdi_write_congested(bdi)) { |
336 | wbc->encountered_congestion = 1; |
337 | if (sb != blockdev_superblock) |
338 | break; /* Skip a congested fs */ |
339 | list_move(&inode->i_list, &sb->s_dirty); |
340 | continue; /* Skip a congested blockdev */ |
341 | } |
342 | |
343 | if (wbc->bdi && bdi != wbc->bdi) { |
344 | if (sb != blockdev_superblock) |
345 | break; /* fs has the wrong queue */ |
346 | list_move(&inode->i_list, &sb->s_dirty); |
347 | continue; /* blockdev has wrong queue */ |
348 | } |
349 | |
350 | /* Was this inode dirtied after sync_sb_inodes was called? */ |
351 | if (time_after(inode->dirtied_when, start)) |
352 | break; |
353 | |
354 | /* Was this inode dirtied too recently? */ |
355 | if (wbc->older_than_this && time_after(inode->dirtied_when, |
356 | *wbc->older_than_this)) |
357 | break; |
358 | |
359 | /* Is another pdflush already flushing this queue? */ |
360 | if (current_is_pdflush() && !writeback_acquire(bdi)) |
361 | break; |
362 | |
363 | BUG_ON(inode->i_state & I_FREEING); |
364 | __iget(inode); |
365 | pages_skipped = wbc->pages_skipped; |
366 | __writeback_single_inode(inode, wbc); |
367 | if (wbc->sync_mode == WB_SYNC_HOLD) { |
368 | inode->dirtied_when = jiffies; |
369 | list_move(&inode->i_list, &sb->s_dirty); |
370 | } |
371 | if (current_is_pdflush()) |
372 | writeback_release(bdi); |
373 | if (wbc->pages_skipped != pages_skipped) { |
374 | /* |
375 | * writeback is not making progress due to locked |
376 | * buffers. Skip this inode for now. |
377 | */ |
378 | list_move(&inode->i_list, &sb->s_dirty); |
379 | } |
380 | spin_unlock(&inode_lock); |
381 | cond_resched(); |
382 | iput(inode); |
383 | spin_lock(&inode_lock); |
384 | if (wbc->nr_to_write <= 0) |
385 | break; |
386 | } |
387 | return; /* Leave any unwritten inodes on s_io */ |
388 | } |
389 | |
390 | /* |
391 | * Start writeback of dirty pagecache data against all unlocked inodes. |
392 | * |
393 | * Note: |
394 | * We don't need to grab a reference to superblock here. If it has non-empty |
395 | * ->s_dirty it's hadn't been killed yet and kill_super() won't proceed |
396 | * past sync_inodes_sb() until both the ->s_dirty and ->s_io lists are |
397 | * empty. Since __sync_single_inode() regains inode_lock before it finally moves |
398 | * inode from superblock lists we are OK. |
399 | * |
400 | * If `older_than_this' is non-zero then only flush inodes which have a |
401 | * flushtime older than *older_than_this. |
402 | * |
403 | * If `bdi' is non-zero then we will scan the first inode against each |
404 | * superblock until we find the matching ones. One group will be the dirty |
405 | * inodes against a filesystem. Then when we hit the dummy blockdev superblock, |
406 | * sync_sb_inodes will seekout the blockdev which matches `bdi'. Maybe not |
407 | * super-efficient but we're about to do a ton of I/O... |
408 | */ |
409 | void |
410 | writeback_inodes(struct writeback_control *wbc) |
411 | { |
412 | struct super_block *sb; |
413 | |
414 | might_sleep(); |
415 | spin_lock(&sb_lock); |
416 | restart: |
417 | sb = sb_entry(super_blocks.prev); |
418 | for (; sb != sb_entry(&super_blocks); sb = sb_entry(sb->s_list.prev)) { |
419 | if (!list_empty(&sb->s_dirty) || !list_empty(&sb->s_io)) { |
420 | /* we're making our own get_super here */ |
421 | sb->s_count++; |
422 | spin_unlock(&sb_lock); |
423 | /* |
424 | * If we can't get the readlock, there's no sense in |
425 | * waiting around, most of the time the FS is going to |
426 | * be unmounted by the time it is released. |
427 | */ |
428 | if (down_read_trylock(&sb->s_umount)) { |
429 | if (sb->s_root) { |
430 | spin_lock(&inode_lock); |
431 | sync_sb_inodes(sb, wbc); |
432 | spin_unlock(&inode_lock); |
433 | } |
434 | up_read(&sb->s_umount); |
435 | } |
436 | spin_lock(&sb_lock); |
437 | if (__put_super_and_need_restart(sb)) |
438 | goto restart; |
439 | } |
440 | if (wbc->nr_to_write <= 0) |
441 | break; |
442 | } |
443 | spin_unlock(&sb_lock); |
444 | } |
445 | |
446 | /* |
447 | * writeback and wait upon the filesystem's dirty inodes. The caller will |
448 | * do this in two passes - one to write, and one to wait. WB_SYNC_HOLD is |
449 | * used to park the written inodes on sb->s_dirty for the wait pass. |
450 | * |
451 | * A finite limit is set on the number of pages which will be written. |
452 | * To prevent infinite livelock of sys_sync(). |
453 | * |
454 | * We add in the number of potentially dirty inodes, because each inode write |
455 | * can dirty pagecache in the underlying blockdev. |
456 | */ |
457 | void sync_inodes_sb(struct super_block *sb, int wait) |
458 | { |
459 | struct writeback_control wbc = { |
460 | .sync_mode = wait ? WB_SYNC_ALL : WB_SYNC_HOLD, |
461 | }; |
462 | unsigned long nr_dirty = read_page_state(nr_dirty); |
463 | unsigned long nr_unstable = read_page_state(nr_unstable); |
464 | |
465 | wbc.nr_to_write = nr_dirty + nr_unstable + |
466 | (inodes_stat.nr_inodes - inodes_stat.nr_unused) + |
467 | nr_dirty + nr_unstable; |
468 | wbc.nr_to_write += wbc.nr_to_write / 2; /* Bit more for luck */ |
469 | spin_lock(&inode_lock); |
470 | sync_sb_inodes(sb, &wbc); |
471 | spin_unlock(&inode_lock); |
472 | } |
473 | |
474 | /* |
475 | * Rather lame livelock avoidance. |
476 | */ |
477 | static void set_sb_syncing(int val) |
478 | { |
479 | struct super_block *sb; |
480 | spin_lock(&sb_lock); |
481 | sb = sb_entry(super_blocks.prev); |
482 | for (; sb != sb_entry(&super_blocks); sb = sb_entry(sb->s_list.prev)) { |
483 | sb->s_syncing = val; |
484 | } |
485 | spin_unlock(&sb_lock); |
486 | } |
487 | |
488 | /* |
489 | * Find a superblock with inodes that need to be synced |
490 | */ |
491 | static struct super_block *get_super_to_sync(void) |
492 | { |
493 | struct super_block *sb; |
494 | restart: |
495 | spin_lock(&sb_lock); |
496 | sb = sb_entry(super_blocks.prev); |
497 | for (; sb != sb_entry(&super_blocks); sb = sb_entry(sb->s_list.prev)) { |
498 | if (sb->s_syncing) |
499 | continue; |
500 | sb->s_syncing = 1; |
501 | sb->s_count++; |
502 | spin_unlock(&sb_lock); |
503 | down_read(&sb->s_umount); |
504 | if (!sb->s_root) { |
505 | drop_super(sb); |
506 | goto restart; |
507 | } |
508 | return sb; |
509 | } |
510 | spin_unlock(&sb_lock); |
511 | return NULL; |
512 | } |
513 | |
514 | /** |
515 | * sync_inodes - writes all inodes to disk |
516 | * @wait: wait for completion |
517 | * |
518 | * sync_inodes() goes through each super block's dirty inode list, writes the |
519 | * inodes out, waits on the writeout and puts the inodes back on the normal |
520 | * list. |
521 | * |
522 | * This is for sys_sync(). fsync_dev() uses the same algorithm. The subtle |
523 | * part of the sync functions is that the blockdev "superblock" is processed |
524 | * last. This is because the write_inode() function of a typical fs will |
525 | * perform no I/O, but will mark buffers in the blockdev mapping as dirty. |
526 | * What we want to do is to perform all that dirtying first, and then write |
527 | * back all those inode blocks via the blockdev mapping in one sweep. So the |
528 | * additional (somewhat redundant) sync_blockdev() calls here are to make |
529 | * sure that really happens. Because if we call sync_inodes_sb(wait=1) with |
530 | * outstanding dirty inodes, the writeback goes block-at-a-time within the |
531 | * filesystem's write_inode(). This is extremely slow. |
532 | */ |
533 | void sync_inodes(int wait) |
534 | { |
535 | struct super_block *sb; |
536 | |
537 | set_sb_syncing(0); |
538 | while ((sb = get_super_to_sync()) != NULL) { |
539 | sync_inodes_sb(sb, 0); |
540 | sync_blockdev(sb->s_bdev); |
541 | drop_super(sb); |
542 | } |
543 | if (wait) { |
544 | set_sb_syncing(0); |
545 | while ((sb = get_super_to_sync()) != NULL) { |
546 | sync_inodes_sb(sb, 1); |
547 | sync_blockdev(sb->s_bdev); |
548 | drop_super(sb); |
549 | } |
550 | } |
551 | } |
552 | |
553 | /** |
554 | * write_inode_now - write an inode to disk |
555 | * @inode: inode to write to disk |
556 | * @sync: whether the write should be synchronous or not |
557 | * |
558 | * This function commits an inode to disk immediately if it is |
559 | * dirty. This is primarily needed by knfsd. |
560 | */ |
561 | |
562 | int write_inode_now(struct inode *inode, int sync) |
563 | { |
564 | int ret; |
565 | struct writeback_control wbc = { |
566 | .nr_to_write = LONG_MAX, |
567 | .sync_mode = WB_SYNC_ALL, |
568 | }; |
569 | |
570 | if (!mapping_cap_writeback_dirty(inode->i_mapping)) |
571 | return 0; |
572 | |
573 | might_sleep(); |
574 | spin_lock(&inode_lock); |
575 | ret = __writeback_single_inode(inode, &wbc); |
576 | spin_unlock(&inode_lock); |
577 | if (sync) |
578 | wait_on_inode(inode); |
579 | return ret; |
580 | } |
581 | EXPORT_SYMBOL(write_inode_now); |
582 | |
583 | /** |
584 | * sync_inode - write an inode and its pages to disk. |
585 | * @inode: the inode to sync |
586 | * @wbc: controls the writeback mode |
587 | * |
588 | * sync_inode() will write an inode and its pages to disk. It will also |
589 | * correctly update the inode on its superblock's dirty inode lists and will |
590 | * update inode->i_state. |
591 | * |
592 | * The caller must have a ref on the inode. |
593 | */ |
594 | int sync_inode(struct inode *inode, struct writeback_control *wbc) |
595 | { |
596 | int ret; |
597 | |
598 | spin_lock(&inode_lock); |
599 | ret = __writeback_single_inode(inode, wbc); |
600 | spin_unlock(&inode_lock); |
601 | return ret; |
602 | } |
603 | EXPORT_SYMBOL(sync_inode); |
604 | |
605 | /** |
606 | * generic_osync_inode - flush all dirty data for a given inode to disk |
607 | * @inode: inode to write |
608 | * @mapping: the address_space that should be flushed |
609 | * @what: what to write and wait upon |
610 | * |
611 | * This can be called by file_write functions for files which have the |
612 | * O_SYNC flag set, to flush dirty writes to disk. |
613 | * |
614 | * @what is a bitmask, specifying which part of the inode's data should be |
615 | * written and waited upon: |
616 | * |
617 | * OSYNC_DATA: i_mapping's dirty data |
618 | * OSYNC_METADATA: the buffers at i_mapping->private_list |
619 | * OSYNC_INODE: the inode itself |
620 | */ |
621 | |
622 | int generic_osync_inode(struct inode *inode, struct address_space *mapping, int what) |
623 | { |
624 | int err = 0; |
625 | int need_write_inode_now = 0; |
626 | int err2; |
627 | |
628 | current->flags |= PF_SYNCWRITE; |
629 | if (what & OSYNC_DATA) |
630 | err = filemap_fdatawrite(mapping); |
631 | if (what & (OSYNC_METADATA|OSYNC_DATA)) { |
632 | err2 = sync_mapping_buffers(mapping); |
633 | if (!err) |
634 | err = err2; |
635 | } |
636 | if (what & OSYNC_DATA) { |
637 | err2 = filemap_fdatawait(mapping); |
638 | if (!err) |
639 | err = err2; |
640 | } |
641 | current->flags &= ~PF_SYNCWRITE; |
642 | |
643 | spin_lock(&inode_lock); |
644 | if ((inode->i_state & I_DIRTY) && |
645 | ((what & OSYNC_INODE) || (inode->i_state & I_DIRTY_DATASYNC))) |
646 | need_write_inode_now = 1; |
647 | spin_unlock(&inode_lock); |
648 | |
649 | if (need_write_inode_now) { |
650 | err2 = write_inode_now(inode, 1); |
651 | if (!err) |
652 | err = err2; |
653 | } |
654 | else |
655 | wait_on_inode(inode); |
656 | |
657 | return err; |
658 | } |
659 | |
660 | EXPORT_SYMBOL(generic_osync_inode); |
661 | |
662 | /** |
663 | * writeback_acquire: attempt to get exclusive writeback access to a device |
664 | * @bdi: the device's backing_dev_info structure |
665 | * |
666 | * It is a waste of resources to have more than one pdflush thread blocked on |
667 | * a single request queue. Exclusion at the request_queue level is obtained |
668 | * via a flag in the request_queue's backing_dev_info.state. |
669 | * |
670 | * Non-request_queue-backed address_spaces will share default_backing_dev_info, |
671 | * unless they implement their own. Which is somewhat inefficient, as this |
672 | * may prevent concurrent writeback against multiple devices. |
673 | */ |
674 | int writeback_acquire(struct backing_dev_info *bdi) |
675 | { |
676 | return !test_and_set_bit(BDI_pdflush, &bdi->state); |
677 | } |
678 | |
679 | /** |
680 | * writeback_in_progress: determine whether there is writeback in progress |
681 | * against a backing device. |
682 | * @bdi: the device's backing_dev_info structure. |
683 | */ |
684 | int writeback_in_progress(struct backing_dev_info *bdi) |
685 | { |
686 | return test_bit(BDI_pdflush, &bdi->state); |
687 | } |
688 | |
689 | /** |
690 | * writeback_release: relinquish exclusive writeback access against a device. |
691 | * @bdi: the device's backing_dev_info structure |
692 | */ |
693 | void writeback_release(struct backing_dev_info *bdi) |
694 | { |
695 | BUG_ON(!writeback_in_progress(bdi)); |
696 | clear_bit(BDI_pdflush, &bdi->state); |
697 | } |