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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * fs/fs-writeback.c | |
3 | * | |
4 | * Copyright (C) 2002, Linus Torvalds. | |
5 | * | |
6 | * Contains all the functions related to writing back and waiting | |
7 | * upon dirty inodes against superblocks, and writing back dirty | |
8 | * pages against inodes. ie: data writeback. Writeout of the | |
9 | * inode itself is not handled here. | |
10 | * | |
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> | |
f5ff8422 | 17 | #include <linux/module.h> |
1da177e4 LT |
18 | #include <linux/spinlock.h> |
19 | #include <linux/sched.h> | |
20 | #include <linux/fs.h> | |
21 | #include <linux/mm.h> | |
22 | #include <linux/writeback.h> | |
23 | #include <linux/blkdev.h> | |
24 | #include <linux/backing-dev.h> | |
25 | #include <linux/buffer_head.h> | |
07f3f05c | 26 | #include "internal.h" |
1da177e4 LT |
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", | |
ba25f9dc | 92 | current->comm, task_pid_nr(current), inode->i_ino, |
1da177e4 LT |
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 | /* | |
1c0eeaf5 | 103 | * If the inode is being synced, just update its dirty state. |
1da177e4 LT |
104 | * The unlocker will place the inode on the appropriate |
105 | * superblock list, based upon its state. | |
106 | */ | |
1c0eeaf5 | 107 | if (inode->i_state & I_SYNC) |
1da177e4 LT |
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 | /* | |
2c136579 | 122 | * If the inode was already on s_dirty/s_io/s_more_io, don't |
1da177e4 LT |
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 | ||
6610a0bc AM |
143 | /* |
144 | * Redirty an inode: set its when-it-was dirtied timestamp and move it to the | |
145 | * furthest end of its superblock's dirty-inode list. | |
146 | * | |
147 | * Before stamping the inode's ->dirtied_when, we check to see whether it is | |
148 | * already the most-recently-dirtied inode on the s_dirty list. If that is | |
149 | * the case then the inode must have been redirtied while it was being written | |
150 | * out and we don't reset its dirtied_when. | |
151 | */ | |
152 | static void redirty_tail(struct inode *inode) | |
153 | { | |
154 | struct super_block *sb = inode->i_sb; | |
155 | ||
156 | if (!list_empty(&sb->s_dirty)) { | |
157 | struct inode *tail_inode; | |
158 | ||
159 | tail_inode = list_entry(sb->s_dirty.next, struct inode, i_list); | |
160 | if (!time_after_eq(inode->dirtied_when, | |
161 | tail_inode->dirtied_when)) | |
162 | inode->dirtied_when = jiffies; | |
163 | } | |
164 | list_move(&inode->i_list, &sb->s_dirty); | |
165 | } | |
166 | ||
c986d1e2 | 167 | /* |
0e0f4fc2 | 168 | * requeue inode for re-scanning after sb->s_io list is exhausted. |
c986d1e2 | 169 | */ |
0e0f4fc2 | 170 | static void requeue_io(struct inode *inode) |
c986d1e2 | 171 | { |
0e0f4fc2 | 172 | list_move(&inode->i_list, &inode->i_sb->s_more_io); |
c986d1e2 AM |
173 | } |
174 | ||
1c0eeaf5 JE |
175 | static void inode_sync_complete(struct inode *inode) |
176 | { | |
177 | /* | |
178 | * Prevent speculative execution through spin_unlock(&inode_lock); | |
179 | */ | |
180 | smp_mb(); | |
181 | wake_up_bit(&inode->i_state, __I_SYNC); | |
182 | } | |
183 | ||
2c136579 FW |
184 | /* |
185 | * Move expired dirty inodes from @delaying_queue to @dispatch_queue. | |
186 | */ | |
187 | static void move_expired_inodes(struct list_head *delaying_queue, | |
188 | struct list_head *dispatch_queue, | |
189 | unsigned long *older_than_this) | |
190 | { | |
191 | while (!list_empty(delaying_queue)) { | |
192 | struct inode *inode = list_entry(delaying_queue->prev, | |
193 | struct inode, i_list); | |
194 | if (older_than_this && | |
195 | time_after(inode->dirtied_when, *older_than_this)) | |
196 | break; | |
197 | list_move(&inode->i_list, dispatch_queue); | |
198 | } | |
199 | } | |
200 | ||
201 | /* | |
202 | * Queue all expired dirty inodes for io, eldest first. | |
203 | */ | |
204 | static void queue_io(struct super_block *sb, | |
205 | unsigned long *older_than_this) | |
206 | { | |
207 | list_splice_init(&sb->s_more_io, sb->s_io.prev); | |
208 | move_expired_inodes(&sb->s_dirty, &sb->s_io, older_than_this); | |
209 | } | |
210 | ||
08d8e974 FW |
211 | int sb_has_dirty_inodes(struct super_block *sb) |
212 | { | |
213 | return !list_empty(&sb->s_dirty) || | |
214 | !list_empty(&sb->s_io) || | |
215 | !list_empty(&sb->s_more_io); | |
216 | } | |
217 | EXPORT_SYMBOL(sb_has_dirty_inodes); | |
218 | ||
1da177e4 LT |
219 | /* |
220 | * Write a single inode's dirty pages and inode data out to disk. | |
221 | * If `wait' is set, wait on the writeout. | |
222 | * | |
223 | * The whole writeout design is quite complex and fragile. We want to avoid | |
224 | * starvation of particular inodes when others are being redirtied, prevent | |
225 | * livelocks, etc. | |
226 | * | |
227 | * Called under inode_lock. | |
228 | */ | |
229 | static int | |
230 | __sync_single_inode(struct inode *inode, struct writeback_control *wbc) | |
231 | { | |
232 | unsigned dirty; | |
233 | struct address_space *mapping = inode->i_mapping; | |
1da177e4 LT |
234 | int wait = wbc->sync_mode == WB_SYNC_ALL; |
235 | int ret; | |
236 | ||
1c0eeaf5 | 237 | BUG_ON(inode->i_state & I_SYNC); |
1da177e4 | 238 | |
1c0eeaf5 | 239 | /* Set I_SYNC, reset I_DIRTY */ |
1da177e4 | 240 | dirty = inode->i_state & I_DIRTY; |
1c0eeaf5 | 241 | inode->i_state |= I_SYNC; |
1da177e4 LT |
242 | inode->i_state &= ~I_DIRTY; |
243 | ||
244 | spin_unlock(&inode_lock); | |
245 | ||
246 | ret = do_writepages(mapping, wbc); | |
247 | ||
248 | /* Don't write the inode if only I_DIRTY_PAGES was set */ | |
249 | if (dirty & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) { | |
250 | int err = write_inode(inode, wait); | |
251 | if (ret == 0) | |
252 | ret = err; | |
253 | } | |
254 | ||
255 | if (wait) { | |
256 | int err = filemap_fdatawait(mapping); | |
257 | if (ret == 0) | |
258 | ret = err; | |
259 | } | |
260 | ||
261 | spin_lock(&inode_lock); | |
1c0eeaf5 | 262 | inode->i_state &= ~I_SYNC; |
1da177e4 LT |
263 | if (!(inode->i_state & I_FREEING)) { |
264 | if (!(inode->i_state & I_DIRTY) && | |
265 | mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) { | |
266 | /* | |
267 | * We didn't write back all the pages. nfs_writepages() | |
268 | * sometimes bales out without doing anything. Redirty | |
2c136579 | 269 | * the inode; Move it from s_io onto s_more_io/s_dirty. |
1b43ef91 AM |
270 | */ |
271 | /* | |
272 | * akpm: if the caller was the kupdate function we put | |
273 | * this inode at the head of s_dirty so it gets first | |
274 | * consideration. Otherwise, move it to the tail, for | |
275 | * the reasons described there. I'm not really sure | |
276 | * how much sense this makes. Presumably I had a good | |
277 | * reasons for doing it this way, and I'd rather not | |
278 | * muck with it at present. | |
1da177e4 LT |
279 | */ |
280 | if (wbc->for_kupdate) { | |
281 | /* | |
2c136579 FW |
282 | * For the kupdate function we move the inode |
283 | * to s_more_io so it will get more writeout as | |
284 | * soon as the queue becomes uncongested. | |
1da177e4 LT |
285 | */ |
286 | inode->i_state |= I_DIRTY_PAGES; | |
8bc3be27 FW |
287 | if (wbc->nr_to_write <= 0) { |
288 | /* | |
289 | * slice used up: queue for next turn | |
290 | */ | |
291 | requeue_io(inode); | |
292 | } else { | |
293 | /* | |
294 | * somehow blocked: retry later | |
295 | */ | |
296 | redirty_tail(inode); | |
297 | } | |
1da177e4 LT |
298 | } else { |
299 | /* | |
300 | * Otherwise fully redirty the inode so that | |
301 | * other inodes on this superblock will get some | |
302 | * writeout. Otherwise heavy writing to one | |
303 | * file would indefinitely suspend writeout of | |
304 | * all the other files. | |
305 | */ | |
306 | inode->i_state |= I_DIRTY_PAGES; | |
1b43ef91 | 307 | redirty_tail(inode); |
1da177e4 LT |
308 | } |
309 | } else if (inode->i_state & I_DIRTY) { | |
310 | /* | |
311 | * Someone redirtied the inode while were writing back | |
312 | * the pages. | |
313 | */ | |
6610a0bc | 314 | redirty_tail(inode); |
1da177e4 LT |
315 | } else if (atomic_read(&inode->i_count)) { |
316 | /* | |
317 | * The inode is clean, inuse | |
318 | */ | |
319 | list_move(&inode->i_list, &inode_in_use); | |
320 | } else { | |
321 | /* | |
322 | * The inode is clean, unused | |
323 | */ | |
324 | list_move(&inode->i_list, &inode_unused); | |
1da177e4 LT |
325 | } |
326 | } | |
1c0eeaf5 | 327 | inode_sync_complete(inode); |
1da177e4 LT |
328 | return ret; |
329 | } | |
330 | ||
331 | /* | |
7f04c26d AA |
332 | * Write out an inode's dirty pages. Called under inode_lock. Either the |
333 | * caller has ref on the inode (either via __iget or via syscall against an fd) | |
334 | * or the inode has I_WILL_FREE set (via generic_forget_inode) | |
1da177e4 LT |
335 | */ |
336 | static int | |
7f04c26d | 337 | __writeback_single_inode(struct inode *inode, struct writeback_control *wbc) |
1da177e4 LT |
338 | { |
339 | wait_queue_head_t *wqh; | |
340 | ||
7f04c26d | 341 | if (!atomic_read(&inode->i_count)) |
659603ef | 342 | WARN_ON(!(inode->i_state & (I_WILL_FREE|I_FREEING))); |
7f04c26d AA |
343 | else |
344 | WARN_ON(inode->i_state & I_WILL_FREE); | |
345 | ||
1c0eeaf5 | 346 | if ((wbc->sync_mode != WB_SYNC_ALL) && (inode->i_state & I_SYNC)) { |
65cb9b47 AM |
347 | /* |
348 | * We're skipping this inode because it's locked, and we're not | |
2c136579 FW |
349 | * doing writeback-for-data-integrity. Move it to s_more_io so |
350 | * that writeback can proceed with the other inodes on s_io. | |
351 | * We'll have another go at writing back this inode when we | |
352 | * completed a full scan of s_io. | |
65cb9b47 | 353 | */ |
0e0f4fc2 | 354 | requeue_io(inode); |
2d544564 | 355 | return 0; |
1da177e4 LT |
356 | } |
357 | ||
358 | /* | |
359 | * It's a data-integrity sync. We must wait. | |
360 | */ | |
1c0eeaf5 JE |
361 | if (inode->i_state & I_SYNC) { |
362 | DEFINE_WAIT_BIT(wq, &inode->i_state, __I_SYNC); | |
1da177e4 | 363 | |
1c0eeaf5 | 364 | wqh = bit_waitqueue(&inode->i_state, __I_SYNC); |
1da177e4 | 365 | do { |
1da177e4 LT |
366 | spin_unlock(&inode_lock); |
367 | __wait_on_bit(wqh, &wq, inode_wait, | |
368 | TASK_UNINTERRUPTIBLE); | |
1da177e4 | 369 | spin_lock(&inode_lock); |
1c0eeaf5 | 370 | } while (inode->i_state & I_SYNC); |
1da177e4 LT |
371 | } |
372 | return __sync_single_inode(inode, wbc); | |
373 | } | |
374 | ||
375 | /* | |
376 | * Write out a superblock's list of dirty inodes. A wait will be performed | |
377 | * upon no inodes, all inodes or the final one, depending upon sync_mode. | |
378 | * | |
379 | * If older_than_this is non-NULL, then only write out inodes which | |
380 | * had their first dirtying at a time earlier than *older_than_this. | |
381 | * | |
382 | * If we're a pdlfush thread, then implement pdflush collision avoidance | |
383 | * against the entire list. | |
384 | * | |
385 | * WB_SYNC_HOLD is a hack for sys_sync(): reattach the inode to sb->s_dirty so | |
386 | * that it can be located for waiting on in __writeback_single_inode(). | |
387 | * | |
388 | * Called under inode_lock. | |
389 | * | |
390 | * If `bdi' is non-zero then we're being asked to writeback a specific queue. | |
391 | * This function assumes that the blockdev superblock's inodes are backed by | |
392 | * a variety of queues, so all inodes are searched. For other superblocks, | |
393 | * assume that all inodes are backed by the same queue. | |
394 | * | |
395 | * FIXME: this linear search could get expensive with many fileystems. But | |
396 | * how to fix? We need to go from an address_space to all inodes which share | |
397 | * a queue with that address_space. (Easy: have a global "dirty superblocks" | |
398 | * list). | |
399 | * | |
400 | * The inodes to be written are parked on sb->s_io. They are moved back onto | |
401 | * sb->s_dirty as they are selected for writing. This way, none can be missed | |
402 | * on the writer throttling path, and we get decent balancing between many | |
1c0eeaf5 | 403 | * throttled threads: we don't want them all piling up on inode_sync_wait. |
1da177e4 LT |
404 | */ |
405 | static void | |
406 | sync_sb_inodes(struct super_block *sb, struct writeback_control *wbc) | |
407 | { | |
408 | const unsigned long start = jiffies; /* livelock avoidance */ | |
409 | ||
410 | if (!wbc->for_kupdate || list_empty(&sb->s_io)) | |
2c136579 | 411 | queue_io(sb, wbc->older_than_this); |
1da177e4 LT |
412 | |
413 | while (!list_empty(&sb->s_io)) { | |
414 | struct inode *inode = list_entry(sb->s_io.prev, | |
415 | struct inode, i_list); | |
416 | struct address_space *mapping = inode->i_mapping; | |
417 | struct backing_dev_info *bdi = mapping->backing_dev_info; | |
418 | long pages_skipped; | |
419 | ||
420 | if (!bdi_cap_writeback_dirty(bdi)) { | |
9852a0e7 | 421 | redirty_tail(inode); |
7b0de42d | 422 | if (sb_is_blkdev_sb(sb)) { |
1da177e4 LT |
423 | /* |
424 | * Dirty memory-backed blockdev: the ramdisk | |
425 | * driver does this. Skip just this inode | |
426 | */ | |
427 | continue; | |
428 | } | |
429 | /* | |
430 | * Dirty memory-backed inode against a filesystem other | |
431 | * than the kernel-internal bdev filesystem. Skip the | |
432 | * entire superblock. | |
433 | */ | |
434 | break; | |
435 | } | |
436 | ||
437 | if (wbc->nonblocking && bdi_write_congested(bdi)) { | |
438 | wbc->encountered_congestion = 1; | |
7b0de42d | 439 | if (!sb_is_blkdev_sb(sb)) |
1da177e4 | 440 | break; /* Skip a congested fs */ |
0e0f4fc2 | 441 | requeue_io(inode); |
1da177e4 LT |
442 | continue; /* Skip a congested blockdev */ |
443 | } | |
444 | ||
445 | if (wbc->bdi && bdi != wbc->bdi) { | |
7b0de42d | 446 | if (!sb_is_blkdev_sb(sb)) |
1da177e4 | 447 | break; /* fs has the wrong queue */ |
0e0f4fc2 | 448 | requeue_io(inode); |
1da177e4 LT |
449 | continue; /* blockdev has wrong queue */ |
450 | } | |
451 | ||
452 | /* Was this inode dirtied after sync_sb_inodes was called? */ | |
453 | if (time_after(inode->dirtied_when, start)) | |
454 | break; | |
455 | ||
1da177e4 LT |
456 | /* Is another pdflush already flushing this queue? */ |
457 | if (current_is_pdflush() && !writeback_acquire(bdi)) | |
458 | break; | |
459 | ||
460 | BUG_ON(inode->i_state & I_FREEING); | |
461 | __iget(inode); | |
462 | pages_skipped = wbc->pages_skipped; | |
463 | __writeback_single_inode(inode, wbc); | |
464 | if (wbc->sync_mode == WB_SYNC_HOLD) { | |
465 | inode->dirtied_when = jiffies; | |
466 | list_move(&inode->i_list, &sb->s_dirty); | |
467 | } | |
468 | if (current_is_pdflush()) | |
469 | writeback_release(bdi); | |
470 | if (wbc->pages_skipped != pages_skipped) { | |
471 | /* | |
472 | * writeback is not making progress due to locked | |
473 | * buffers. Skip this inode for now. | |
474 | */ | |
f57b9b7b | 475 | redirty_tail(inode); |
1da177e4 LT |
476 | } |
477 | spin_unlock(&inode_lock); | |
1da177e4 | 478 | iput(inode); |
4ffc8444 | 479 | cond_resched(); |
1da177e4 | 480 | spin_lock(&inode_lock); |
8bc3be27 FW |
481 | if (wbc->nr_to_write <= 0) { |
482 | wbc->more_io = 1; | |
1da177e4 | 483 | break; |
8bc3be27 FW |
484 | } |
485 | if (!list_empty(&sb->s_more_io)) | |
486 | wbc->more_io = 1; | |
1da177e4 LT |
487 | } |
488 | return; /* Leave any unwritten inodes on s_io */ | |
489 | } | |
490 | ||
491 | /* | |
492 | * Start writeback of dirty pagecache data against all unlocked inodes. | |
493 | * | |
494 | * Note: | |
495 | * We don't need to grab a reference to superblock here. If it has non-empty | |
496 | * ->s_dirty it's hadn't been killed yet and kill_super() won't proceed | |
2c136579 | 497 | * past sync_inodes_sb() until the ->s_dirty/s_io/s_more_io lists are all |
1da177e4 LT |
498 | * empty. Since __sync_single_inode() regains inode_lock before it finally moves |
499 | * inode from superblock lists we are OK. | |
500 | * | |
501 | * If `older_than_this' is non-zero then only flush inodes which have a | |
502 | * flushtime older than *older_than_this. | |
503 | * | |
504 | * If `bdi' is non-zero then we will scan the first inode against each | |
505 | * superblock until we find the matching ones. One group will be the dirty | |
506 | * inodes against a filesystem. Then when we hit the dummy blockdev superblock, | |
507 | * sync_sb_inodes will seekout the blockdev which matches `bdi'. Maybe not | |
508 | * super-efficient but we're about to do a ton of I/O... | |
509 | */ | |
510 | void | |
511 | writeback_inodes(struct writeback_control *wbc) | |
512 | { | |
513 | struct super_block *sb; | |
514 | ||
515 | might_sleep(); | |
516 | spin_lock(&sb_lock); | |
517 | restart: | |
797074e4 | 518 | list_for_each_entry_reverse(sb, &super_blocks, s_list) { |
08d8e974 | 519 | if (sb_has_dirty_inodes(sb)) { |
1da177e4 LT |
520 | /* we're making our own get_super here */ |
521 | sb->s_count++; | |
522 | spin_unlock(&sb_lock); | |
523 | /* | |
524 | * If we can't get the readlock, there's no sense in | |
525 | * waiting around, most of the time the FS is going to | |
526 | * be unmounted by the time it is released. | |
527 | */ | |
528 | if (down_read_trylock(&sb->s_umount)) { | |
529 | if (sb->s_root) { | |
530 | spin_lock(&inode_lock); | |
531 | sync_sb_inodes(sb, wbc); | |
532 | spin_unlock(&inode_lock); | |
533 | } | |
534 | up_read(&sb->s_umount); | |
535 | } | |
536 | spin_lock(&sb_lock); | |
537 | if (__put_super_and_need_restart(sb)) | |
538 | goto restart; | |
539 | } | |
540 | if (wbc->nr_to_write <= 0) | |
541 | break; | |
542 | } | |
543 | spin_unlock(&sb_lock); | |
544 | } | |
545 | ||
546 | /* | |
547 | * writeback and wait upon the filesystem's dirty inodes. The caller will | |
548 | * do this in two passes - one to write, and one to wait. WB_SYNC_HOLD is | |
549 | * used to park the written inodes on sb->s_dirty for the wait pass. | |
550 | * | |
551 | * A finite limit is set on the number of pages which will be written. | |
552 | * To prevent infinite livelock of sys_sync(). | |
553 | * | |
554 | * We add in the number of potentially dirty inodes, because each inode write | |
555 | * can dirty pagecache in the underlying blockdev. | |
556 | */ | |
557 | void sync_inodes_sb(struct super_block *sb, int wait) | |
558 | { | |
559 | struct writeback_control wbc = { | |
560 | .sync_mode = wait ? WB_SYNC_ALL : WB_SYNC_HOLD, | |
111ebb6e OH |
561 | .range_start = 0, |
562 | .range_end = LLONG_MAX, | |
1da177e4 | 563 | }; |
b1e7a8fd | 564 | unsigned long nr_dirty = global_page_state(NR_FILE_DIRTY); |
fd39fc85 | 565 | unsigned long nr_unstable = global_page_state(NR_UNSTABLE_NFS); |
1da177e4 LT |
566 | |
567 | wbc.nr_to_write = nr_dirty + nr_unstable + | |
568 | (inodes_stat.nr_inodes - inodes_stat.nr_unused) + | |
569 | nr_dirty + nr_unstable; | |
570 | wbc.nr_to_write += wbc.nr_to_write / 2; /* Bit more for luck */ | |
571 | spin_lock(&inode_lock); | |
572 | sync_sb_inodes(sb, &wbc); | |
573 | spin_unlock(&inode_lock); | |
574 | } | |
575 | ||
576 | /* | |
577 | * Rather lame livelock avoidance. | |
578 | */ | |
579 | static void set_sb_syncing(int val) | |
580 | { | |
581 | struct super_block *sb; | |
582 | spin_lock(&sb_lock); | |
797074e4 | 583 | list_for_each_entry_reverse(sb, &super_blocks, s_list) |
1da177e4 | 584 | sb->s_syncing = val; |
1da177e4 LT |
585 | spin_unlock(&sb_lock); |
586 | } | |
587 | ||
1da177e4 | 588 | /** |
67be2dd1 MW |
589 | * sync_inodes - writes all inodes to disk |
590 | * @wait: wait for completion | |
1da177e4 LT |
591 | * |
592 | * sync_inodes() goes through each super block's dirty inode list, writes the | |
593 | * inodes out, waits on the writeout and puts the inodes back on the normal | |
594 | * list. | |
595 | * | |
596 | * This is for sys_sync(). fsync_dev() uses the same algorithm. The subtle | |
597 | * part of the sync functions is that the blockdev "superblock" is processed | |
598 | * last. This is because the write_inode() function of a typical fs will | |
599 | * perform no I/O, but will mark buffers in the blockdev mapping as dirty. | |
600 | * What we want to do is to perform all that dirtying first, and then write | |
601 | * back all those inode blocks via the blockdev mapping in one sweep. So the | |
602 | * additional (somewhat redundant) sync_blockdev() calls here are to make | |
603 | * sure that really happens. Because if we call sync_inodes_sb(wait=1) with | |
604 | * outstanding dirty inodes, the writeback goes block-at-a-time within the | |
605 | * filesystem's write_inode(). This is extremely slow. | |
606 | */ | |
618f0636 | 607 | static void __sync_inodes(int wait) |
1da177e4 LT |
608 | { |
609 | struct super_block *sb; | |
610 | ||
618f0636 KK |
611 | spin_lock(&sb_lock); |
612 | restart: | |
613 | list_for_each_entry(sb, &super_blocks, s_list) { | |
614 | if (sb->s_syncing) | |
615 | continue; | |
616 | sb->s_syncing = 1; | |
617 | sb->s_count++; | |
618 | spin_unlock(&sb_lock); | |
619 | down_read(&sb->s_umount); | |
620 | if (sb->s_root) { | |
621 | sync_inodes_sb(sb, wait); | |
622 | sync_blockdev(sb->s_bdev); | |
623 | } | |
624 | up_read(&sb->s_umount); | |
625 | spin_lock(&sb_lock); | |
626 | if (__put_super_and_need_restart(sb)) | |
627 | goto restart; | |
1da177e4 | 628 | } |
618f0636 KK |
629 | spin_unlock(&sb_lock); |
630 | } | |
631 | ||
632 | void sync_inodes(int wait) | |
633 | { | |
634 | set_sb_syncing(0); | |
635 | __sync_inodes(0); | |
636 | ||
1da177e4 LT |
637 | if (wait) { |
638 | set_sb_syncing(0); | |
618f0636 | 639 | __sync_inodes(1); |
1da177e4 LT |
640 | } |
641 | } | |
642 | ||
643 | /** | |
7f04c26d AA |
644 | * write_inode_now - write an inode to disk |
645 | * @inode: inode to write to disk | |
646 | * @sync: whether the write should be synchronous or not | |
647 | * | |
648 | * This function commits an inode to disk immediately if it is dirty. This is | |
649 | * primarily needed by knfsd. | |
1da177e4 | 650 | * |
7f04c26d | 651 | * The caller must either have a ref on the inode or must have set I_WILL_FREE. |
1da177e4 | 652 | */ |
1da177e4 LT |
653 | int write_inode_now(struct inode *inode, int sync) |
654 | { | |
655 | int ret; | |
656 | struct writeback_control wbc = { | |
657 | .nr_to_write = LONG_MAX, | |
18914b18 | 658 | .sync_mode = sync ? WB_SYNC_ALL : WB_SYNC_NONE, |
111ebb6e OH |
659 | .range_start = 0, |
660 | .range_end = LLONG_MAX, | |
1da177e4 LT |
661 | }; |
662 | ||
663 | if (!mapping_cap_writeback_dirty(inode->i_mapping)) | |
49364ce2 | 664 | wbc.nr_to_write = 0; |
1da177e4 LT |
665 | |
666 | might_sleep(); | |
667 | spin_lock(&inode_lock); | |
668 | ret = __writeback_single_inode(inode, &wbc); | |
669 | spin_unlock(&inode_lock); | |
670 | if (sync) | |
1c0eeaf5 | 671 | inode_sync_wait(inode); |
1da177e4 LT |
672 | return ret; |
673 | } | |
674 | EXPORT_SYMBOL(write_inode_now); | |
675 | ||
676 | /** | |
677 | * sync_inode - write an inode and its pages to disk. | |
678 | * @inode: the inode to sync | |
679 | * @wbc: controls the writeback mode | |
680 | * | |
681 | * sync_inode() will write an inode and its pages to disk. It will also | |
682 | * correctly update the inode on its superblock's dirty inode lists and will | |
683 | * update inode->i_state. | |
684 | * | |
685 | * The caller must have a ref on the inode. | |
686 | */ | |
687 | int sync_inode(struct inode *inode, struct writeback_control *wbc) | |
688 | { | |
689 | int ret; | |
690 | ||
691 | spin_lock(&inode_lock); | |
692 | ret = __writeback_single_inode(inode, wbc); | |
693 | spin_unlock(&inode_lock); | |
694 | return ret; | |
695 | } | |
696 | EXPORT_SYMBOL(sync_inode); | |
697 | ||
698 | /** | |
699 | * generic_osync_inode - flush all dirty data for a given inode to disk | |
700 | * @inode: inode to write | |
67be2dd1 | 701 | * @mapping: the address_space that should be flushed |
1da177e4 LT |
702 | * @what: what to write and wait upon |
703 | * | |
704 | * This can be called by file_write functions for files which have the | |
705 | * O_SYNC flag set, to flush dirty writes to disk. | |
706 | * | |
707 | * @what is a bitmask, specifying which part of the inode's data should be | |
b8887e6e | 708 | * written and waited upon. |
1da177e4 LT |
709 | * |
710 | * OSYNC_DATA: i_mapping's dirty data | |
711 | * OSYNC_METADATA: the buffers at i_mapping->private_list | |
712 | * OSYNC_INODE: the inode itself | |
713 | */ | |
714 | ||
715 | int generic_osync_inode(struct inode *inode, struct address_space *mapping, int what) | |
716 | { | |
717 | int err = 0; | |
718 | int need_write_inode_now = 0; | |
719 | int err2; | |
720 | ||
1da177e4 LT |
721 | if (what & OSYNC_DATA) |
722 | err = filemap_fdatawrite(mapping); | |
723 | if (what & (OSYNC_METADATA|OSYNC_DATA)) { | |
724 | err2 = sync_mapping_buffers(mapping); | |
725 | if (!err) | |
726 | err = err2; | |
727 | } | |
728 | if (what & OSYNC_DATA) { | |
729 | err2 = filemap_fdatawait(mapping); | |
730 | if (!err) | |
731 | err = err2; | |
732 | } | |
1da177e4 LT |
733 | |
734 | spin_lock(&inode_lock); | |
735 | if ((inode->i_state & I_DIRTY) && | |
736 | ((what & OSYNC_INODE) || (inode->i_state & I_DIRTY_DATASYNC))) | |
737 | need_write_inode_now = 1; | |
738 | spin_unlock(&inode_lock); | |
739 | ||
740 | if (need_write_inode_now) { | |
741 | err2 = write_inode_now(inode, 1); | |
742 | if (!err) | |
743 | err = err2; | |
744 | } | |
745 | else | |
1c0eeaf5 | 746 | inode_sync_wait(inode); |
1da177e4 LT |
747 | |
748 | return err; | |
749 | } | |
750 | ||
751 | EXPORT_SYMBOL(generic_osync_inode); | |
752 | ||
753 | /** | |
754 | * writeback_acquire: attempt to get exclusive writeback access to a device | |
755 | * @bdi: the device's backing_dev_info structure | |
756 | * | |
757 | * It is a waste of resources to have more than one pdflush thread blocked on | |
758 | * a single request queue. Exclusion at the request_queue level is obtained | |
759 | * via a flag in the request_queue's backing_dev_info.state. | |
760 | * | |
761 | * Non-request_queue-backed address_spaces will share default_backing_dev_info, | |
762 | * unless they implement their own. Which is somewhat inefficient, as this | |
763 | * may prevent concurrent writeback against multiple devices. | |
764 | */ | |
765 | int writeback_acquire(struct backing_dev_info *bdi) | |
766 | { | |
767 | return !test_and_set_bit(BDI_pdflush, &bdi->state); | |
768 | } | |
769 | ||
770 | /** | |
771 | * writeback_in_progress: determine whether there is writeback in progress | |
1da177e4 | 772 | * @bdi: the device's backing_dev_info structure. |
b8887e6e RD |
773 | * |
774 | * Determine whether there is writeback in progress against a backing device. | |
1da177e4 LT |
775 | */ |
776 | int writeback_in_progress(struct backing_dev_info *bdi) | |
777 | { | |
778 | return test_bit(BDI_pdflush, &bdi->state); | |
779 | } | |
780 | ||
781 | /** | |
782 | * writeback_release: relinquish exclusive writeback access against a device. | |
783 | * @bdi: the device's backing_dev_info structure | |
784 | */ | |
785 | void writeback_release(struct backing_dev_info *bdi) | |
786 | { | |
787 | BUG_ON(!writeback_in_progress(bdi)); | |
788 | clear_bit(BDI_pdflush, &bdi->state); | |
789 | } |