Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * fs/fs-writeback.c | |
3 | * | |
4 | * Copyright (C) 2002, Linus Torvalds. | |
5 | * | |
6 | * Contains all the functions related to writing back and waiting | |
7 | * upon dirty inodes against superblocks, and writing back dirty | |
8 | * pages against inodes. ie: data writeback. Writeout of the | |
9 | * inode itself is not handled here. | |
10 | * | |
e1f8e874 | 11 | * 10Apr2002 Andrew Morton |
1da177e4 LT |
12 | * Split out of fs/inode.c |
13 | * Additions for address_space-based writeback | |
14 | */ | |
15 | ||
16 | #include <linux/kernel.h> | |
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 | 27 | |
66f3b8e2 | 28 | #define inode_to_bdi(inode) ((inode)->i_mapping->backing_dev_info) |
f11b00f3 AB |
29 | |
30 | /** | |
31 | * writeback_acquire - attempt to get exclusive writeback access to a device | |
32 | * @bdi: the device's backing_dev_info structure | |
33 | * | |
34 | * It is a waste of resources to have more than one pdflush thread blocked on | |
35 | * a single request queue. Exclusion at the request_queue level is obtained | |
36 | * via a flag in the request_queue's backing_dev_info.state. | |
37 | * | |
38 | * Non-request_queue-backed address_spaces will share default_backing_dev_info, | |
39 | * unless they implement their own. Which is somewhat inefficient, as this | |
40 | * may prevent concurrent writeback against multiple devices. | |
41 | */ | |
42 | static int writeback_acquire(struct backing_dev_info *bdi) | |
43 | { | |
44 | return !test_and_set_bit(BDI_pdflush, &bdi->state); | |
45 | } | |
46 | ||
47 | /** | |
48 | * writeback_in_progress - determine whether there is writeback in progress | |
49 | * @bdi: the device's backing_dev_info structure. | |
50 | * | |
51 | * Determine whether there is writeback in progress against a backing device. | |
52 | */ | |
53 | int writeback_in_progress(struct backing_dev_info *bdi) | |
54 | { | |
55 | return test_bit(BDI_pdflush, &bdi->state); | |
56 | } | |
57 | ||
58 | /** | |
59 | * writeback_release - relinquish exclusive writeback access against a device. | |
60 | * @bdi: the device's backing_dev_info structure | |
61 | */ | |
62 | static void writeback_release(struct backing_dev_info *bdi) | |
63 | { | |
64 | BUG_ON(!writeback_in_progress(bdi)); | |
65 | clear_bit(BDI_pdflush, &bdi->state); | |
66 | } | |
67 | ||
4195f73d NP |
68 | static noinline void block_dump___mark_inode_dirty(struct inode *inode) |
69 | { | |
70 | if (inode->i_ino || strcmp(inode->i_sb->s_id, "bdev")) { | |
71 | struct dentry *dentry; | |
72 | const char *name = "?"; | |
73 | ||
74 | dentry = d_find_alias(inode); | |
75 | if (dentry) { | |
76 | spin_lock(&dentry->d_lock); | |
77 | name = (const char *) dentry->d_name.name; | |
78 | } | |
79 | printk(KERN_DEBUG | |
80 | "%s(%d): dirtied inode %lu (%s) on %s\n", | |
81 | current->comm, task_pid_nr(current), inode->i_ino, | |
82 | name, inode->i_sb->s_id); | |
83 | if (dentry) { | |
84 | spin_unlock(&dentry->d_lock); | |
85 | dput(dentry); | |
86 | } | |
87 | } | |
88 | } | |
89 | ||
1da177e4 LT |
90 | /** |
91 | * __mark_inode_dirty - internal function | |
92 | * @inode: inode to mark | |
93 | * @flags: what kind of dirty (i.e. I_DIRTY_SYNC) | |
94 | * Mark an inode as dirty. Callers should use mark_inode_dirty or | |
95 | * mark_inode_dirty_sync. | |
96 | * | |
97 | * Put the inode on the super block's dirty list. | |
98 | * | |
99 | * CAREFUL! We mark it dirty unconditionally, but move it onto the | |
100 | * dirty list only if it is hashed or if it refers to a blockdev. | |
101 | * If it was not hashed, it will never be added to the dirty list | |
102 | * even if it is later hashed, as it will have been marked dirty already. | |
103 | * | |
104 | * In short, make sure you hash any inodes _before_ you start marking | |
105 | * them dirty. | |
106 | * | |
107 | * This function *must* be atomic for the I_DIRTY_PAGES case - | |
108 | * set_page_dirty() is called under spinlock in several places. | |
109 | * | |
110 | * Note that for blockdevs, inode->dirtied_when represents the dirtying time of | |
111 | * the block-special inode (/dev/hda1) itself. And the ->dirtied_when field of | |
112 | * the kernel-internal blockdev inode represents the dirtying time of the | |
113 | * blockdev's pages. This is why for I_DIRTY_PAGES we always use | |
114 | * page->mapping->host, so the page-dirtying time is recorded in the internal | |
115 | * blockdev inode. | |
116 | */ | |
117 | void __mark_inode_dirty(struct inode *inode, int flags) | |
118 | { | |
119 | struct super_block *sb = inode->i_sb; | |
120 | ||
121 | /* | |
122 | * Don't do this for I_DIRTY_PAGES - that doesn't actually | |
123 | * dirty the inode itself | |
124 | */ | |
125 | if (flags & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) { | |
126 | if (sb->s_op->dirty_inode) | |
127 | sb->s_op->dirty_inode(inode); | |
128 | } | |
129 | ||
130 | /* | |
131 | * make sure that changes are seen by all cpus before we test i_state | |
132 | * -- mikulas | |
133 | */ | |
134 | smp_mb(); | |
135 | ||
136 | /* avoid the locking if we can */ | |
137 | if ((inode->i_state & flags) == flags) | |
138 | return; | |
139 | ||
4195f73d NP |
140 | if (unlikely(block_dump)) |
141 | block_dump___mark_inode_dirty(inode); | |
1da177e4 LT |
142 | |
143 | spin_lock(&inode_lock); | |
144 | if ((inode->i_state & flags) != flags) { | |
145 | const int was_dirty = inode->i_state & I_DIRTY; | |
146 | ||
147 | inode->i_state |= flags; | |
148 | ||
149 | /* | |
1c0eeaf5 | 150 | * If the inode is being synced, just update its dirty state. |
1da177e4 LT |
151 | * The unlocker will place the inode on the appropriate |
152 | * superblock list, based upon its state. | |
153 | */ | |
1c0eeaf5 | 154 | if (inode->i_state & I_SYNC) |
1da177e4 LT |
155 | goto out; |
156 | ||
157 | /* | |
158 | * Only add valid (hashed) inodes to the superblock's | |
159 | * dirty list. Add blockdev inodes as well. | |
160 | */ | |
161 | if (!S_ISBLK(inode->i_mode)) { | |
162 | if (hlist_unhashed(&inode->i_hash)) | |
163 | goto out; | |
164 | } | |
165 | if (inode->i_state & (I_FREEING|I_CLEAR)) | |
166 | goto out; | |
167 | ||
168 | /* | |
66f3b8e2 JA |
169 | * If the inode was already on b_dirty/b_io/b_more_io, don't |
170 | * reposition it (that would break b_dirty time-ordering). | |
1da177e4 LT |
171 | */ |
172 | if (!was_dirty) { | |
173 | inode->dirtied_when = jiffies; | |
66f3b8e2 JA |
174 | list_move(&inode->i_list, |
175 | &inode_to_bdi(inode)->b_dirty); | |
1da177e4 LT |
176 | } |
177 | } | |
178 | out: | |
179 | spin_unlock(&inode_lock); | |
180 | } | |
181 | ||
182 | EXPORT_SYMBOL(__mark_inode_dirty); | |
183 | ||
184 | static int write_inode(struct inode *inode, int sync) | |
185 | { | |
186 | if (inode->i_sb->s_op->write_inode && !is_bad_inode(inode)) | |
187 | return inode->i_sb->s_op->write_inode(inode, sync); | |
188 | return 0; | |
189 | } | |
190 | ||
6610a0bc AM |
191 | /* |
192 | * Redirty an inode: set its when-it-was dirtied timestamp and move it to the | |
193 | * furthest end of its superblock's dirty-inode list. | |
194 | * | |
195 | * Before stamping the inode's ->dirtied_when, we check to see whether it is | |
66f3b8e2 | 196 | * already the most-recently-dirtied inode on the b_dirty list. If that is |
6610a0bc AM |
197 | * the case then the inode must have been redirtied while it was being written |
198 | * out and we don't reset its dirtied_when. | |
199 | */ | |
200 | static void redirty_tail(struct inode *inode) | |
201 | { | |
66f3b8e2 | 202 | struct backing_dev_info *bdi = inode_to_bdi(inode); |
6610a0bc | 203 | |
66f3b8e2 JA |
204 | if (!list_empty(&bdi->b_dirty)) { |
205 | struct inode *tail; | |
6610a0bc | 206 | |
66f3b8e2 JA |
207 | tail = list_entry(bdi->b_dirty.next, struct inode, i_list); |
208 | if (time_before(inode->dirtied_when, tail->dirtied_when)) | |
6610a0bc AM |
209 | inode->dirtied_when = jiffies; |
210 | } | |
66f3b8e2 | 211 | list_move(&inode->i_list, &bdi->b_dirty); |
6610a0bc AM |
212 | } |
213 | ||
c986d1e2 | 214 | /* |
66f3b8e2 | 215 | * requeue inode for re-scanning after bdi->b_io list is exhausted. |
c986d1e2 | 216 | */ |
0e0f4fc2 | 217 | static void requeue_io(struct inode *inode) |
c986d1e2 | 218 | { |
66f3b8e2 | 219 | list_move(&inode->i_list, &inode_to_bdi(inode)->b_more_io); |
c986d1e2 AM |
220 | } |
221 | ||
1c0eeaf5 JE |
222 | static void inode_sync_complete(struct inode *inode) |
223 | { | |
224 | /* | |
225 | * Prevent speculative execution through spin_unlock(&inode_lock); | |
226 | */ | |
227 | smp_mb(); | |
228 | wake_up_bit(&inode->i_state, __I_SYNC); | |
229 | } | |
230 | ||
d2caa3c5 JL |
231 | static bool inode_dirtied_after(struct inode *inode, unsigned long t) |
232 | { | |
233 | bool ret = time_after(inode->dirtied_when, t); | |
234 | #ifndef CONFIG_64BIT | |
235 | /* | |
236 | * For inodes being constantly redirtied, dirtied_when can get stuck. | |
237 | * It _appears_ to be in the future, but is actually in distant past. | |
238 | * This test is necessary to prevent such wrapped-around relative times | |
239 | * from permanently stopping the whole pdflush writeback. | |
240 | */ | |
241 | ret = ret && time_before_eq(inode->dirtied_when, jiffies); | |
242 | #endif | |
243 | return ret; | |
244 | } | |
245 | ||
2c136579 FW |
246 | /* |
247 | * Move expired dirty inodes from @delaying_queue to @dispatch_queue. | |
248 | */ | |
249 | static void move_expired_inodes(struct list_head *delaying_queue, | |
250 | struct list_head *dispatch_queue, | |
251 | unsigned long *older_than_this) | |
252 | { | |
253 | while (!list_empty(delaying_queue)) { | |
254 | struct inode *inode = list_entry(delaying_queue->prev, | |
255 | struct inode, i_list); | |
256 | if (older_than_this && | |
d2caa3c5 | 257 | inode_dirtied_after(inode, *older_than_this)) |
2c136579 FW |
258 | break; |
259 | list_move(&inode->i_list, dispatch_queue); | |
260 | } | |
261 | } | |
262 | ||
263 | /* | |
264 | * Queue all expired dirty inodes for io, eldest first. | |
265 | */ | |
66f3b8e2 JA |
266 | static void queue_io(struct backing_dev_info *bdi, |
267 | unsigned long *older_than_this) | |
268 | { | |
269 | list_splice_init(&bdi->b_more_io, bdi->b_io.prev); | |
270 | move_expired_inodes(&bdi->b_dirty, &bdi->b_io, older_than_this); | |
271 | } | |
272 | ||
273 | static int sb_on_inode_list(struct super_block *sb, struct list_head *list) | |
2c136579 | 274 | { |
66f3b8e2 JA |
275 | struct inode *inode; |
276 | int ret = 0; | |
277 | ||
278 | spin_lock(&inode_lock); | |
279 | list_for_each_entry(inode, list, i_list) { | |
280 | if (inode->i_sb == sb) { | |
281 | ret = 1; | |
282 | break; | |
283 | } | |
284 | } | |
285 | spin_unlock(&inode_lock); | |
286 | return ret; | |
2c136579 FW |
287 | } |
288 | ||
08d8e974 FW |
289 | int sb_has_dirty_inodes(struct super_block *sb) |
290 | { | |
66f3b8e2 JA |
291 | struct backing_dev_info *bdi; |
292 | int ret = 0; | |
293 | ||
294 | /* | |
295 | * This is REALLY expensive right now, but it'll go away | |
296 | * when the bdi writeback is introduced | |
297 | */ | |
298 | mutex_lock(&bdi_lock); | |
299 | list_for_each_entry(bdi, &bdi_list, bdi_list) { | |
300 | if (sb_on_inode_list(sb, &bdi->b_dirty) || | |
301 | sb_on_inode_list(sb, &bdi->b_io) || | |
302 | sb_on_inode_list(sb, &bdi->b_more_io)) { | |
303 | ret = 1; | |
304 | break; | |
305 | } | |
306 | } | |
307 | mutex_unlock(&bdi_lock); | |
308 | ||
309 | return ret; | |
08d8e974 FW |
310 | } |
311 | EXPORT_SYMBOL(sb_has_dirty_inodes); | |
312 | ||
1da177e4 | 313 | /* |
01c03194 CH |
314 | * Wait for writeback on an inode to complete. |
315 | */ | |
316 | static void inode_wait_for_writeback(struct inode *inode) | |
317 | { | |
318 | DEFINE_WAIT_BIT(wq, &inode->i_state, __I_SYNC); | |
319 | wait_queue_head_t *wqh; | |
320 | ||
321 | wqh = bit_waitqueue(&inode->i_state, __I_SYNC); | |
322 | do { | |
323 | spin_unlock(&inode_lock); | |
324 | __wait_on_bit(wqh, &wq, inode_wait, TASK_UNINTERRUPTIBLE); | |
325 | spin_lock(&inode_lock); | |
326 | } while (inode->i_state & I_SYNC); | |
327 | } | |
328 | ||
329 | /* | |
330 | * Write out an inode's dirty pages. Called under inode_lock. Either the | |
331 | * caller has ref on the inode (either via __iget or via syscall against an fd) | |
332 | * or the inode has I_WILL_FREE set (via generic_forget_inode) | |
333 | * | |
1da177e4 LT |
334 | * If `wait' is set, wait on the writeout. |
335 | * | |
336 | * The whole writeout design is quite complex and fragile. We want to avoid | |
337 | * starvation of particular inodes when others are being redirtied, prevent | |
338 | * livelocks, etc. | |
339 | * | |
340 | * Called under inode_lock. | |
341 | */ | |
342 | static int | |
01c03194 | 343 | writeback_single_inode(struct inode *inode, struct writeback_control *wbc) |
1da177e4 | 344 | { |
1da177e4 | 345 | struct address_space *mapping = inode->i_mapping; |
1da177e4 | 346 | int wait = wbc->sync_mode == WB_SYNC_ALL; |
01c03194 | 347 | unsigned dirty; |
1da177e4 LT |
348 | int ret; |
349 | ||
01c03194 CH |
350 | if (!atomic_read(&inode->i_count)) |
351 | WARN_ON(!(inode->i_state & (I_WILL_FREE|I_FREEING))); | |
352 | else | |
353 | WARN_ON(inode->i_state & I_WILL_FREE); | |
354 | ||
355 | if (inode->i_state & I_SYNC) { | |
356 | /* | |
357 | * If this inode is locked for writeback and we are not doing | |
66f3b8e2 | 358 | * writeback-for-data-integrity, move it to b_more_io so that |
01c03194 CH |
359 | * writeback can proceed with the other inodes on s_io. |
360 | * | |
361 | * We'll have another go at writing back this inode when we | |
66f3b8e2 | 362 | * completed a full scan of b_io. |
01c03194 CH |
363 | */ |
364 | if (!wait) { | |
365 | requeue_io(inode); | |
366 | return 0; | |
367 | } | |
368 | ||
369 | /* | |
370 | * It's a data-integrity sync. We must wait. | |
371 | */ | |
372 | inode_wait_for_writeback(inode); | |
373 | } | |
374 | ||
1c0eeaf5 | 375 | BUG_ON(inode->i_state & I_SYNC); |
1da177e4 | 376 | |
1c0eeaf5 | 377 | /* Set I_SYNC, reset I_DIRTY */ |
1da177e4 | 378 | dirty = inode->i_state & I_DIRTY; |
1c0eeaf5 | 379 | inode->i_state |= I_SYNC; |
1da177e4 LT |
380 | inode->i_state &= ~I_DIRTY; |
381 | ||
382 | spin_unlock(&inode_lock); | |
383 | ||
384 | ret = do_writepages(mapping, wbc); | |
385 | ||
386 | /* Don't write the inode if only I_DIRTY_PAGES was set */ | |
387 | if (dirty & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) { | |
388 | int err = write_inode(inode, wait); | |
389 | if (ret == 0) | |
390 | ret = err; | |
391 | } | |
392 | ||
393 | if (wait) { | |
394 | int err = filemap_fdatawait(mapping); | |
395 | if (ret == 0) | |
396 | ret = err; | |
397 | } | |
398 | ||
399 | spin_lock(&inode_lock); | |
1c0eeaf5 | 400 | inode->i_state &= ~I_SYNC; |
84a89245 | 401 | if (!(inode->i_state & (I_FREEING | I_CLEAR))) { |
1da177e4 LT |
402 | if (!(inode->i_state & I_DIRTY) && |
403 | mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) { | |
404 | /* | |
405 | * We didn't write back all the pages. nfs_writepages() | |
406 | * sometimes bales out without doing anything. Redirty | |
66f3b8e2 | 407 | * the inode; Move it from b_io onto b_more_io/b_dirty. |
1b43ef91 AM |
408 | */ |
409 | /* | |
410 | * akpm: if the caller was the kupdate function we put | |
66f3b8e2 | 411 | * this inode at the head of b_dirty so it gets first |
1b43ef91 AM |
412 | * consideration. Otherwise, move it to the tail, for |
413 | * the reasons described there. I'm not really sure | |
414 | * how much sense this makes. Presumably I had a good | |
415 | * reasons for doing it this way, and I'd rather not | |
416 | * muck with it at present. | |
1da177e4 LT |
417 | */ |
418 | if (wbc->for_kupdate) { | |
419 | /* | |
2c136579 | 420 | * For the kupdate function we move the inode |
66f3b8e2 | 421 | * to b_more_io so it will get more writeout as |
2c136579 | 422 | * soon as the queue becomes uncongested. |
1da177e4 LT |
423 | */ |
424 | inode->i_state |= I_DIRTY_PAGES; | |
8bc3be27 FW |
425 | if (wbc->nr_to_write <= 0) { |
426 | /* | |
427 | * slice used up: queue for next turn | |
428 | */ | |
429 | requeue_io(inode); | |
430 | } else { | |
431 | /* | |
432 | * somehow blocked: retry later | |
433 | */ | |
434 | redirty_tail(inode); | |
435 | } | |
1da177e4 LT |
436 | } else { |
437 | /* | |
438 | * Otherwise fully redirty the inode so that | |
439 | * other inodes on this superblock will get some | |
440 | * writeout. Otherwise heavy writing to one | |
441 | * file would indefinitely suspend writeout of | |
442 | * all the other files. | |
443 | */ | |
444 | inode->i_state |= I_DIRTY_PAGES; | |
1b43ef91 | 445 | redirty_tail(inode); |
1da177e4 LT |
446 | } |
447 | } else if (inode->i_state & I_DIRTY) { | |
448 | /* | |
449 | * Someone redirtied the inode while were writing back | |
450 | * the pages. | |
451 | */ | |
6610a0bc | 452 | redirty_tail(inode); |
1da177e4 LT |
453 | } else if (atomic_read(&inode->i_count)) { |
454 | /* | |
455 | * The inode is clean, inuse | |
456 | */ | |
457 | list_move(&inode->i_list, &inode_in_use); | |
458 | } else { | |
459 | /* | |
460 | * The inode is clean, unused | |
461 | */ | |
462 | list_move(&inode->i_list, &inode_unused); | |
1da177e4 LT |
463 | } |
464 | } | |
1c0eeaf5 | 465 | inode_sync_complete(inode); |
1da177e4 LT |
466 | return ret; |
467 | } | |
468 | ||
66f3b8e2 JA |
469 | static void generic_sync_bdi_inodes(struct backing_dev_info *bdi, |
470 | struct writeback_control *wbc, | |
471 | struct super_block *sb) | |
1da177e4 | 472 | { |
66f3b8e2 | 473 | const int is_blkdev_sb = sb_is_blkdev_sb(sb); |
1da177e4 LT |
474 | const unsigned long start = jiffies; /* livelock avoidance */ |
475 | ||
ae8547b0 | 476 | spin_lock(&inode_lock); |
1da177e4 | 477 | |
66f3b8e2 JA |
478 | if (!wbc->for_kupdate || list_empty(&bdi->b_io)) |
479 | queue_io(bdi, wbc->older_than_this); | |
480 | ||
481 | while (!list_empty(&bdi->b_io)) { | |
482 | struct inode *inode = list_entry(bdi->b_io.prev, | |
1da177e4 | 483 | struct inode, i_list); |
1da177e4 LT |
484 | long pages_skipped; |
485 | ||
66f3b8e2 JA |
486 | /* |
487 | * super block given and doesn't match, skip this inode | |
488 | */ | |
489 | if (sb && sb != inode->i_sb) { | |
490 | redirty_tail(inode); | |
491 | continue; | |
492 | } | |
493 | ||
1da177e4 | 494 | if (!bdi_cap_writeback_dirty(bdi)) { |
9852a0e7 | 495 | redirty_tail(inode); |
66f3b8e2 | 496 | if (is_blkdev_sb) { |
1da177e4 LT |
497 | /* |
498 | * Dirty memory-backed blockdev: the ramdisk | |
499 | * driver does this. Skip just this inode | |
500 | */ | |
501 | continue; | |
502 | } | |
503 | /* | |
504 | * Dirty memory-backed inode against a filesystem other | |
505 | * than the kernel-internal bdev filesystem. Skip the | |
506 | * entire superblock. | |
507 | */ | |
508 | break; | |
509 | } | |
510 | ||
84a89245 | 511 | if (inode->i_state & (I_NEW | I_WILL_FREE)) { |
7ef0d737 NP |
512 | requeue_io(inode); |
513 | continue; | |
514 | } | |
515 | ||
1da177e4 LT |
516 | if (wbc->nonblocking && bdi_write_congested(bdi)) { |
517 | wbc->encountered_congestion = 1; | |
66f3b8e2 | 518 | if (!is_blkdev_sb) |
1da177e4 | 519 | break; /* Skip a congested fs */ |
0e0f4fc2 | 520 | requeue_io(inode); |
1da177e4 LT |
521 | continue; /* Skip a congested blockdev */ |
522 | } | |
523 | ||
524 | if (wbc->bdi && bdi != wbc->bdi) { | |
66f3b8e2 | 525 | if (!is_blkdev_sb) |
1da177e4 | 526 | break; /* fs has the wrong queue */ |
0e0f4fc2 | 527 | requeue_io(inode); |
1da177e4 LT |
528 | continue; /* blockdev has wrong queue */ |
529 | } | |
530 | ||
d2caa3c5 JL |
531 | /* |
532 | * Was this inode dirtied after sync_sb_inodes was called? | |
533 | * This keeps sync from extra jobs and livelock. | |
534 | */ | |
535 | if (inode_dirtied_after(inode, start)) | |
1da177e4 LT |
536 | break; |
537 | ||
1da177e4 LT |
538 | /* Is another pdflush already flushing this queue? */ |
539 | if (current_is_pdflush() && !writeback_acquire(bdi)) | |
540 | break; | |
541 | ||
84a89245 | 542 | BUG_ON(inode->i_state & (I_FREEING | I_CLEAR)); |
1da177e4 LT |
543 | __iget(inode); |
544 | pages_skipped = wbc->pages_skipped; | |
01c03194 | 545 | writeback_single_inode(inode, wbc); |
1da177e4 LT |
546 | if (current_is_pdflush()) |
547 | writeback_release(bdi); | |
548 | if (wbc->pages_skipped != pages_skipped) { | |
549 | /* | |
550 | * writeback is not making progress due to locked | |
551 | * buffers. Skip this inode for now. | |
552 | */ | |
f57b9b7b | 553 | redirty_tail(inode); |
1da177e4 LT |
554 | } |
555 | spin_unlock(&inode_lock); | |
1da177e4 | 556 | iput(inode); |
4ffc8444 | 557 | cond_resched(); |
1da177e4 | 558 | spin_lock(&inode_lock); |
8bc3be27 FW |
559 | if (wbc->nr_to_write <= 0) { |
560 | wbc->more_io = 1; | |
1da177e4 | 561 | break; |
8bc3be27 | 562 | } |
66f3b8e2 | 563 | if (!list_empty(&bdi->b_more_io)) |
8bc3be27 | 564 | wbc->more_io = 1; |
1da177e4 | 565 | } |
38f21977 | 566 | |
66f3b8e2 JA |
567 | spin_unlock(&inode_lock); |
568 | /* Leave any unwritten inodes on b_io */ | |
569 | } | |
570 | ||
571 | /* | |
572 | * Write out a superblock's list of dirty inodes. A wait will be performed | |
573 | * upon no inodes, all inodes or the final one, depending upon sync_mode. | |
574 | * | |
575 | * If older_than_this is non-NULL, then only write out inodes which | |
576 | * had their first dirtying at a time earlier than *older_than_this. | |
577 | * | |
578 | * If we're a pdlfush thread, then implement pdflush collision avoidance | |
579 | * against the entire list. | |
580 | * | |
581 | * If `bdi' is non-zero then we're being asked to writeback a specific queue. | |
582 | * This function assumes that the blockdev superblock's inodes are backed by | |
583 | * a variety of queues, so all inodes are searched. For other superblocks, | |
584 | * assume that all inodes are backed by the same queue. | |
585 | * | |
586 | * FIXME: this linear search could get expensive with many fileystems. But | |
587 | * how to fix? We need to go from an address_space to all inodes which share | |
588 | * a queue with that address_space. (Easy: have a global "dirty superblocks" | |
589 | * list). | |
590 | * | |
591 | * The inodes to be written are parked on bdi->b_io. They are moved back onto | |
592 | * bdi->b_dirty as they are selected for writing. This way, none can be missed | |
593 | * on the writer throttling path, and we get decent balancing between many | |
594 | * throttled threads: we don't want them all piling up on inode_sync_wait. | |
595 | */ | |
596 | static void generic_sync_sb_inodes(struct super_block *sb, | |
597 | struct writeback_control *wbc) | |
598 | { | |
599 | struct backing_dev_info *bdi; | |
600 | ||
601 | if (!wbc->bdi) { | |
602 | mutex_lock(&bdi_lock); | |
603 | list_for_each_entry(bdi, &bdi_list, bdi_list) | |
604 | generic_sync_bdi_inodes(bdi, wbc, sb); | |
605 | mutex_unlock(&bdi_lock); | |
606 | } else | |
607 | generic_sync_bdi_inodes(wbc->bdi, wbc, sb); | |
608 | ||
609 | if (wbc->sync_mode == WB_SYNC_ALL) { | |
38f21977 NP |
610 | struct inode *inode, *old_inode = NULL; |
611 | ||
66f3b8e2 JA |
612 | spin_lock(&inode_lock); |
613 | ||
38f21977 NP |
614 | /* |
615 | * Data integrity sync. Must wait for all pages under writeback, | |
616 | * because there may have been pages dirtied before our sync | |
617 | * call, but which had writeout started before we write it out. | |
618 | * In which case, the inode may not be on the dirty list, but | |
619 | * we still have to wait for that writeout. | |
620 | */ | |
621 | list_for_each_entry(inode, &sb->s_inodes, i_sb_list) { | |
622 | struct address_space *mapping; | |
623 | ||
b6fac63c WF |
624 | if (inode->i_state & |
625 | (I_FREEING|I_CLEAR|I_WILL_FREE|I_NEW)) | |
38f21977 NP |
626 | continue; |
627 | mapping = inode->i_mapping; | |
628 | if (mapping->nrpages == 0) | |
629 | continue; | |
630 | __iget(inode); | |
631 | spin_unlock(&inode_lock); | |
632 | /* | |
633 | * We hold a reference to 'inode' so it couldn't have | |
634 | * been removed from s_inodes list while we dropped the | |
635 | * inode_lock. We cannot iput the inode now as we can | |
636 | * be holding the last reference and we cannot iput it | |
637 | * under inode_lock. So we keep the reference and iput | |
638 | * it later. | |
639 | */ | |
640 | iput(old_inode); | |
641 | old_inode = inode; | |
642 | ||
643 | filemap_fdatawait(mapping); | |
644 | ||
645 | cond_resched(); | |
646 | ||
647 | spin_lock(&inode_lock); | |
648 | } | |
649 | spin_unlock(&inode_lock); | |
650 | iput(old_inode); | |
66f3b8e2 | 651 | } |
1da177e4 LT |
652 | } |
653 | ||
654 | /* | |
655 | * Start writeback of dirty pagecache data against all unlocked inodes. | |
656 | * | |
657 | * Note: | |
658 | * We don't need to grab a reference to superblock here. If it has non-empty | |
66f3b8e2 JA |
659 | * ->b_dirty it's hadn't been killed yet and kill_super() won't proceed |
660 | * past sync_inodes_sb() until the ->b_dirty/b_io/b_more_io lists are all | |
1da177e4 LT |
661 | * empty. Since __sync_single_inode() regains inode_lock before it finally moves |
662 | * inode from superblock lists we are OK. | |
663 | * | |
664 | * If `older_than_this' is non-zero then only flush inodes which have a | |
665 | * flushtime older than *older_than_this. | |
666 | * | |
667 | * If `bdi' is non-zero then we will scan the first inode against each | |
668 | * superblock until we find the matching ones. One group will be the dirty | |
669 | * inodes against a filesystem. Then when we hit the dummy blockdev superblock, | |
670 | * sync_sb_inodes will seekout the blockdev which matches `bdi'. Maybe not | |
671 | * super-efficient but we're about to do a ton of I/O... | |
672 | */ | |
673 | void | |
674 | writeback_inodes(struct writeback_control *wbc) | |
675 | { | |
676 | struct super_block *sb; | |
677 | ||
678 | might_sleep(); | |
679 | spin_lock(&sb_lock); | |
680 | restart: | |
797074e4 | 681 | list_for_each_entry_reverse(sb, &super_blocks, s_list) { |
08d8e974 | 682 | if (sb_has_dirty_inodes(sb)) { |
1da177e4 LT |
683 | /* we're making our own get_super here */ |
684 | sb->s_count++; | |
685 | spin_unlock(&sb_lock); | |
686 | /* | |
687 | * If we can't get the readlock, there's no sense in | |
688 | * waiting around, most of the time the FS is going to | |
689 | * be unmounted by the time it is released. | |
690 | */ | |
691 | if (down_read_trylock(&sb->s_umount)) { | |
ae8547b0 | 692 | if (sb->s_root) |
d8a8559c | 693 | generic_sync_sb_inodes(sb, wbc); |
1da177e4 LT |
694 | up_read(&sb->s_umount); |
695 | } | |
696 | spin_lock(&sb_lock); | |
697 | if (__put_super_and_need_restart(sb)) | |
698 | goto restart; | |
699 | } | |
700 | if (wbc->nr_to_write <= 0) | |
701 | break; | |
702 | } | |
703 | spin_unlock(&sb_lock); | |
704 | } | |
705 | ||
d8a8559c JA |
706 | /** |
707 | * writeback_inodes_sb - writeback dirty inodes from given super_block | |
708 | * @sb: the superblock | |
1da177e4 | 709 | * |
d8a8559c JA |
710 | * Start writeback on some inodes on this super_block. No guarantees are made |
711 | * on how many (if any) will be written, and this function does not wait | |
712 | * for IO completion of submitted IO. The number of pages submitted is | |
713 | * returned. | |
1da177e4 | 714 | */ |
d8a8559c | 715 | long writeback_inodes_sb(struct super_block *sb) |
1da177e4 LT |
716 | { |
717 | struct writeback_control wbc = { | |
d8a8559c | 718 | .sync_mode = WB_SYNC_NONE, |
111ebb6e OH |
719 | .range_start = 0, |
720 | .range_end = LLONG_MAX, | |
1da177e4 | 721 | }; |
d8a8559c JA |
722 | unsigned long nr_dirty = global_page_state(NR_FILE_DIRTY); |
723 | unsigned long nr_unstable = global_page_state(NR_UNSTABLE_NFS); | |
724 | long nr_to_write; | |
1da177e4 | 725 | |
d8a8559c | 726 | nr_to_write = nr_dirty + nr_unstable + |
38f21977 | 727 | (inodes_stat.nr_inodes - inodes_stat.nr_unused); |
38f21977 | 728 | |
d8a8559c JA |
729 | wbc.nr_to_write = nr_to_write; |
730 | generic_sync_sb_inodes(sb, &wbc); | |
731 | return nr_to_write - wbc.nr_to_write; | |
732 | } | |
733 | EXPORT_SYMBOL(writeback_inodes_sb); | |
734 | ||
735 | /** | |
736 | * sync_inodes_sb - sync sb inode pages | |
737 | * @sb: the superblock | |
738 | * | |
739 | * This function writes and waits on any dirty inode belonging to this | |
740 | * super_block. The number of pages synced is returned. | |
741 | */ | |
742 | long sync_inodes_sb(struct super_block *sb) | |
743 | { | |
744 | struct writeback_control wbc = { | |
745 | .sync_mode = WB_SYNC_ALL, | |
746 | .range_start = 0, | |
747 | .range_end = LLONG_MAX, | |
748 | }; | |
749 | long nr_to_write = LONG_MAX; /* doesn't actually matter */ | |
750 | ||
751 | wbc.nr_to_write = nr_to_write; | |
752 | generic_sync_sb_inodes(sb, &wbc); | |
753 | return nr_to_write - wbc.nr_to_write; | |
1da177e4 | 754 | } |
d8a8559c | 755 | EXPORT_SYMBOL(sync_inodes_sb); |
1da177e4 | 756 | |
1da177e4 | 757 | /** |
7f04c26d AA |
758 | * write_inode_now - write an inode to disk |
759 | * @inode: inode to write to disk | |
760 | * @sync: whether the write should be synchronous or not | |
761 | * | |
762 | * This function commits an inode to disk immediately if it is dirty. This is | |
763 | * primarily needed by knfsd. | |
1da177e4 | 764 | * |
7f04c26d | 765 | * The caller must either have a ref on the inode or must have set I_WILL_FREE. |
1da177e4 | 766 | */ |
1da177e4 LT |
767 | int write_inode_now(struct inode *inode, int sync) |
768 | { | |
769 | int ret; | |
770 | struct writeback_control wbc = { | |
771 | .nr_to_write = LONG_MAX, | |
18914b18 | 772 | .sync_mode = sync ? WB_SYNC_ALL : WB_SYNC_NONE, |
111ebb6e OH |
773 | .range_start = 0, |
774 | .range_end = LLONG_MAX, | |
1da177e4 LT |
775 | }; |
776 | ||
777 | if (!mapping_cap_writeback_dirty(inode->i_mapping)) | |
49364ce2 | 778 | wbc.nr_to_write = 0; |
1da177e4 LT |
779 | |
780 | might_sleep(); | |
781 | spin_lock(&inode_lock); | |
01c03194 | 782 | ret = writeback_single_inode(inode, &wbc); |
1da177e4 LT |
783 | spin_unlock(&inode_lock); |
784 | if (sync) | |
1c0eeaf5 | 785 | inode_sync_wait(inode); |
1da177e4 LT |
786 | return ret; |
787 | } | |
788 | EXPORT_SYMBOL(write_inode_now); | |
789 | ||
790 | /** | |
791 | * sync_inode - write an inode and its pages to disk. | |
792 | * @inode: the inode to sync | |
793 | * @wbc: controls the writeback mode | |
794 | * | |
795 | * sync_inode() will write an inode and its pages to disk. It will also | |
796 | * correctly update the inode on its superblock's dirty inode lists and will | |
797 | * update inode->i_state. | |
798 | * | |
799 | * The caller must have a ref on the inode. | |
800 | */ | |
801 | int sync_inode(struct inode *inode, struct writeback_control *wbc) | |
802 | { | |
803 | int ret; | |
804 | ||
805 | spin_lock(&inode_lock); | |
01c03194 | 806 | ret = writeback_single_inode(inode, wbc); |
1da177e4 LT |
807 | spin_unlock(&inode_lock); |
808 | return ret; | |
809 | } | |
810 | EXPORT_SYMBOL(sync_inode); | |
811 | ||
812 | /** | |
813 | * generic_osync_inode - flush all dirty data for a given inode to disk | |
814 | * @inode: inode to write | |
67be2dd1 | 815 | * @mapping: the address_space that should be flushed |
1da177e4 LT |
816 | * @what: what to write and wait upon |
817 | * | |
818 | * This can be called by file_write functions for files which have the | |
819 | * O_SYNC flag set, to flush dirty writes to disk. | |
820 | * | |
821 | * @what is a bitmask, specifying which part of the inode's data should be | |
b8887e6e | 822 | * written and waited upon. |
1da177e4 LT |
823 | * |
824 | * OSYNC_DATA: i_mapping's dirty data | |
825 | * OSYNC_METADATA: the buffers at i_mapping->private_list | |
826 | * OSYNC_INODE: the inode itself | |
827 | */ | |
828 | ||
829 | int generic_osync_inode(struct inode *inode, struct address_space *mapping, int what) | |
830 | { | |
831 | int err = 0; | |
832 | int need_write_inode_now = 0; | |
833 | int err2; | |
834 | ||
1da177e4 LT |
835 | if (what & OSYNC_DATA) |
836 | err = filemap_fdatawrite(mapping); | |
837 | if (what & (OSYNC_METADATA|OSYNC_DATA)) { | |
838 | err2 = sync_mapping_buffers(mapping); | |
839 | if (!err) | |
840 | err = err2; | |
841 | } | |
842 | if (what & OSYNC_DATA) { | |
843 | err2 = filemap_fdatawait(mapping); | |
844 | if (!err) | |
845 | err = err2; | |
846 | } | |
1da177e4 LT |
847 | |
848 | spin_lock(&inode_lock); | |
849 | if ((inode->i_state & I_DIRTY) && | |
850 | ((what & OSYNC_INODE) || (inode->i_state & I_DIRTY_DATASYNC))) | |
851 | need_write_inode_now = 1; | |
852 | spin_unlock(&inode_lock); | |
853 | ||
854 | if (need_write_inode_now) { | |
855 | err2 = write_inode_now(inode, 1); | |
856 | if (!err) | |
857 | err = err2; | |
858 | } | |
859 | else | |
1c0eeaf5 | 860 | inode_sync_wait(inode); |
1da177e4 LT |
861 | |
862 | return err; | |
863 | } | |
1da177e4 | 864 | EXPORT_SYMBOL(generic_osync_inode); |