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