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-rw-r--r--fs/afs/write.c835
1 files changed, 835 insertions, 0 deletions
diff --git a/fs/afs/write.c b/fs/afs/write.c
new file mode 100644
index 000000000000..83ff29262816
--- /dev/null
+++ b/fs/afs/write.c
@@ -0,0 +1,835 @@
1/* handling of writes to regular files and writing back to the server
2 *
3 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 */
11
12#include <linux/slab.h>
13#include <linux/fs.h>
14#include <linux/pagemap.h>
15#include <linux/writeback.h>
16#include <linux/pagevec.h>
17#include "internal.h"
18
19static int afs_write_back_from_locked_page(struct afs_writeback *wb,
20 struct page *page);
21
22/*
23 * mark a page as having been made dirty and thus needing writeback
24 */
25int afs_set_page_dirty(struct page *page)
26{
27 _enter("");
28 return __set_page_dirty_nobuffers(page);
29}
30
31/*
32 * unlink a writeback record because its usage has reached zero
33 * - must be called with the wb->vnode->writeback_lock held
34 */
35static void afs_unlink_writeback(struct afs_writeback *wb)
36{
37 struct afs_writeback *front;
38 struct afs_vnode *vnode = wb->vnode;
39
40 list_del_init(&wb->link);
41 if (!list_empty(&vnode->writebacks)) {
42 /* if an fsync rises to the front of the queue then wake it
43 * up */
44 front = list_entry(vnode->writebacks.next,
45 struct afs_writeback, link);
46 if (front->state == AFS_WBACK_SYNCING) {
47 _debug("wake up sync");
48 front->state = AFS_WBACK_COMPLETE;
49 wake_up(&front->waitq);
50 }
51 }
52}
53
54/*
55 * free a writeback record
56 */
57static void afs_free_writeback(struct afs_writeback *wb)
58{
59 _enter("");
60 key_put(wb->key);
61 kfree(wb);
62}
63
64/*
65 * dispose of a reference to a writeback record
66 */
67void afs_put_writeback(struct afs_writeback *wb)
68{
69 struct afs_vnode *vnode = wb->vnode;
70
71 _enter("{%d}", wb->usage);
72
73 spin_lock(&vnode->writeback_lock);
74 if (--wb->usage == 0)
75 afs_unlink_writeback(wb);
76 else
77 wb = NULL;
78 spin_unlock(&vnode->writeback_lock);
79 if (wb)
80 afs_free_writeback(wb);
81}
82
83/*
84 * partly or wholly fill a page that's under preparation for writing
85 */
86static int afs_fill_page(struct afs_vnode *vnode, struct key *key,
87 unsigned start, unsigned len, struct page *page)
88{
89 int ret;
90
91 _enter(",,%u,%u", start, len);
92
93 ASSERTCMP(start + len, <=, PAGE_SIZE);
94
95 ret = afs_vnode_fetch_data(vnode, key, start, len, page);
96 if (ret < 0) {
97 if (ret == -ENOENT) {
98 _debug("got NOENT from server"
99 " - marking file deleted and stale");
100 set_bit(AFS_VNODE_DELETED, &vnode->flags);
101 ret = -ESTALE;
102 }
103 }
104
105 _leave(" = %d", ret);
106 return ret;
107}
108
109/*
110 * prepare a page for being written to
111 */
112static int afs_prepare_page(struct afs_vnode *vnode, struct page *page,
113 struct key *key, unsigned offset, unsigned to)
114{
115 unsigned eof, tail, start, stop, len;
116 loff_t i_size, pos;
117 void *p;
118 int ret;
119
120 _enter("");
121
122 if (offset == 0 && to == PAGE_SIZE)
123 return 0;
124
125 p = kmap(page);
126
127 i_size = i_size_read(&vnode->vfs_inode);
128 pos = (loff_t) page->index << PAGE_SHIFT;
129 if (pos >= i_size) {
130 /* partial write, page beyond EOF */
131 _debug("beyond");
132 if (offset > 0)
133 memset(p, 0, offset);
134 if (to < PAGE_SIZE)
135 memset(p + to, 0, PAGE_SIZE - to);
136 kunmap(page);
137 return 0;
138 }
139
140 if (i_size - pos >= PAGE_SIZE) {
141 /* partial write, page entirely before EOF */
142 _debug("before");
143 tail = eof = PAGE_SIZE;
144 } else {
145 /* partial write, page overlaps EOF */
146 eof = i_size - pos;
147 _debug("overlap %u", eof);
148 tail = max(eof, to);
149 if (tail < PAGE_SIZE)
150 memset(p + tail, 0, PAGE_SIZE - tail);
151 if (offset > eof)
152 memset(p + eof, 0, PAGE_SIZE - eof);
153 }
154
155 kunmap(p);
156
157 ret = 0;
158 if (offset > 0 || eof > to) {
159 /* need to fill one or two bits that aren't going to be written
160 * (cover both fillers in one read if there are two) */
161 start = (offset > 0) ? 0 : to;
162 stop = (eof > to) ? eof : offset;
163 len = stop - start;
164 _debug("wr=%u-%u av=0-%u rd=%u@%u",
165 offset, to, eof, start, len);
166 ret = afs_fill_page(vnode, key, start, len, page);
167 }
168
169 _leave(" = %d", ret);
170 return ret;
171}
172
173/*
174 * prepare to perform part of a write to a page
175 * - the caller holds the page locked, preventing it from being written out or
176 * modified by anyone else
177 */
178int afs_prepare_write(struct file *file, struct page *page,
179 unsigned offset, unsigned to)
180{
181 struct afs_writeback *candidate, *wb;
182 struct afs_vnode *vnode = AFS_FS_I(file->f_dentry->d_inode);
183 struct key *key = file->private_data;
184 pgoff_t index;
185 int ret;
186
187 _enter("{%x:%u},{%lx},%u,%u",
188 vnode->fid.vid, vnode->fid.vnode, page->index, offset, to);
189
190 candidate = kzalloc(sizeof(*candidate), GFP_KERNEL);
191 if (!candidate)
192 return -ENOMEM;
193 candidate->vnode = vnode;
194 candidate->first = candidate->last = page->index;
195 candidate->offset_first = offset;
196 candidate->to_last = to;
197 candidate->usage = 1;
198 candidate->state = AFS_WBACK_PENDING;
199 init_waitqueue_head(&candidate->waitq);
200
201 if (!PageUptodate(page)) {
202 _debug("not up to date");
203 ret = afs_prepare_page(vnode, page, key, offset, to);
204 if (ret < 0) {
205 kfree(candidate);
206 _leave(" = %d [prep]", ret);
207 return ret;
208 }
209 SetPageUptodate(page);
210 }
211
212try_again:
213 index = page->index;
214 spin_lock(&vnode->writeback_lock);
215
216 /* see if this page is already pending a writeback under a suitable key
217 * - if so we can just join onto that one */
218 wb = (struct afs_writeback *) page_private(page);
219 if (wb) {
220 if (wb->key == key && wb->state == AFS_WBACK_PENDING)
221 goto subsume_in_current_wb;
222 goto flush_conflicting_wb;
223 }
224
225 if (index > 0) {
226 /* see if we can find an already pending writeback that we can
227 * append this page to */
228 list_for_each_entry(wb, &vnode->writebacks, link) {
229 if (wb->last == index - 1 && wb->key == key &&
230 wb->state == AFS_WBACK_PENDING)
231 goto append_to_previous_wb;
232 }
233 }
234
235 list_add_tail(&candidate->link, &vnode->writebacks);
236 candidate->key = key_get(key);
237 spin_unlock(&vnode->writeback_lock);
238 SetPagePrivate(page);
239 set_page_private(page, (unsigned long) candidate);
240 _leave(" = 0 [new]");
241 return 0;
242
243subsume_in_current_wb:
244 _debug("subsume");
245 ASSERTRANGE(wb->first, <=, index, <=, wb->last);
246 if (index == wb->first && offset < wb->offset_first)
247 wb->offset_first = offset;
248 if (index == wb->last && to > wb->to_last)
249 wb->to_last = to;
250 spin_unlock(&vnode->writeback_lock);
251 kfree(candidate);
252 _leave(" = 0 [sub]");
253 return 0;
254
255append_to_previous_wb:
256 _debug("append into %lx-%lx", wb->first, wb->last);
257 wb->usage++;
258 wb->last++;
259 wb->to_last = to;
260 spin_unlock(&vnode->writeback_lock);
261 SetPagePrivate(page);
262 set_page_private(page, (unsigned long) wb);
263 kfree(candidate);
264 _leave(" = 0 [app]");
265 return 0;
266
267 /* the page is currently bound to another context, so if it's dirty we
268 * need to flush it before we can use the new context */
269flush_conflicting_wb:
270 _debug("flush conflict");
271 if (wb->state == AFS_WBACK_PENDING)
272 wb->state = AFS_WBACK_CONFLICTING;
273 spin_unlock(&vnode->writeback_lock);
274 if (PageDirty(page)) {
275 ret = afs_write_back_from_locked_page(wb, page);
276 if (ret < 0) {
277 afs_put_writeback(candidate);
278 _leave(" = %d", ret);
279 return ret;
280 }
281 }
282
283 /* the page holds a ref on the writeback record */
284 afs_put_writeback(wb);
285 set_page_private(page, 0);
286 ClearPagePrivate(page);
287 goto try_again;
288}
289
290/*
291 * finalise part of a write to a page
292 */
293int afs_commit_write(struct file *file, struct page *page,
294 unsigned offset, unsigned to)
295{
296 struct afs_vnode *vnode = AFS_FS_I(file->f_dentry->d_inode);
297 loff_t i_size, maybe_i_size;
298
299 _enter("{%x:%u},{%lx},%u,%u",
300 vnode->fid.vid, vnode->fid.vnode, page->index, offset, to);
301
302 maybe_i_size = (loff_t) page->index << PAGE_SHIFT;
303 maybe_i_size += to;
304
305 i_size = i_size_read(&vnode->vfs_inode);
306 if (maybe_i_size > i_size) {
307 spin_lock(&vnode->writeback_lock);
308 i_size = i_size_read(&vnode->vfs_inode);
309 if (maybe_i_size > i_size)
310 i_size_write(&vnode->vfs_inode, maybe_i_size);
311 spin_unlock(&vnode->writeback_lock);
312 }
313
314 set_page_dirty(page);
315
316 if (PageDirty(page))
317 _debug("dirtied");
318
319 return 0;
320}
321
322/*
323 * kill all the pages in the given range
324 */
325static void afs_kill_pages(struct afs_vnode *vnode, bool error,
326 pgoff_t first, pgoff_t last)
327{
328 struct pagevec pv;
329 unsigned count, loop;
330
331 _enter("{%x:%u},%lx-%lx",
332 vnode->fid.vid, vnode->fid.vnode, first, last);
333
334 pagevec_init(&pv, 0);
335
336 do {
337 _debug("kill %lx-%lx", first, last);
338
339 count = last - first + 1;
340 if (count > PAGEVEC_SIZE)
341 count = PAGEVEC_SIZE;
342 pv.nr = find_get_pages_contig(vnode->vfs_inode.i_mapping,
343 first, count, pv.pages);
344 ASSERTCMP(pv.nr, ==, count);
345
346 for (loop = 0; loop < count; loop++) {
347 ClearPageUptodate(pv.pages[loop]);
348 if (error)
349 SetPageError(pv.pages[loop]);
350 end_page_writeback(pv.pages[loop]);
351 }
352
353 __pagevec_release(&pv);
354 } while (first < last);
355
356 _leave("");
357}
358
359/*
360 * synchronously write back the locked page and any subsequent non-locked dirty
361 * pages also covered by the same writeback record
362 */
363static int afs_write_back_from_locked_page(struct afs_writeback *wb,
364 struct page *primary_page)
365{
366 struct page *pages[8], *page;
367 unsigned long count;
368 unsigned n, offset, to;
369 pgoff_t start, first, last;
370 int loop, ret;
371
372 _enter(",%lx", primary_page->index);
373
374 count = 1;
375 if (!clear_page_dirty_for_io(primary_page))
376 BUG();
377 if (test_set_page_writeback(primary_page))
378 BUG();
379
380 /* find all consecutive lockable dirty pages, stopping when we find a
381 * page that is not immediately lockable, is not dirty or is missing,
382 * or we reach the end of the range */
383 start = primary_page->index;
384 if (start >= wb->last)
385 goto no_more;
386 start++;
387 do {
388 _debug("more %lx [%lx]", start, count);
389 n = wb->last - start + 1;
390 if (n > ARRAY_SIZE(pages))
391 n = ARRAY_SIZE(pages);
392 n = find_get_pages_contig(wb->vnode->vfs_inode.i_mapping,
393 start, n, pages);
394 _debug("fgpc %u", n);
395 if (n == 0)
396 goto no_more;
397 if (pages[0]->index != start) {
398 for (n--; n >= 0; n--)
399 put_page(pages[n]);
400 goto no_more;
401 }
402
403 for (loop = 0; loop < n; loop++) {
404 page = pages[loop];
405 if (page->index > wb->last)
406 break;
407 if (TestSetPageLocked(page))
408 break;
409 if (!PageDirty(page) ||
410 page_private(page) != (unsigned long) wb) {
411 unlock_page(page);
412 break;
413 }
414 if (!clear_page_dirty_for_io(page))
415 BUG();
416 if (test_set_page_writeback(page))
417 BUG();
418 unlock_page(page);
419 put_page(page);
420 }
421 count += loop;
422 if (loop < n) {
423 for (; loop < n; loop++)
424 put_page(pages[loop]);
425 goto no_more;
426 }
427
428 start += loop;
429 } while (start <= wb->last && count < 65536);
430
431no_more:
432 /* we now have a contiguous set of dirty pages, each with writeback set
433 * and the dirty mark cleared; the first page is locked and must remain
434 * so, all the rest are unlocked */
435 first = primary_page->index;
436 last = first + count - 1;
437
438 offset = (first == wb->first) ? wb->offset_first : 0;
439 to = (last == wb->last) ? wb->to_last : PAGE_SIZE;
440
441 _debug("write back %lx[%u..] to %lx[..%u]", first, offset, last, to);
442
443 ret = afs_vnode_store_data(wb, first, last, offset, to);
444 if (ret < 0) {
445 switch (ret) {
446 case -EDQUOT:
447 case -ENOSPC:
448 set_bit(AS_ENOSPC,
449 &wb->vnode->vfs_inode.i_mapping->flags);
450 break;
451 case -EROFS:
452 case -EIO:
453 case -EREMOTEIO:
454 case -EFBIG:
455 case -ENOENT:
456 case -ENOMEDIUM:
457 case -ENXIO:
458 afs_kill_pages(wb->vnode, true, first, last);
459 set_bit(AS_EIO, &wb->vnode->vfs_inode.i_mapping->flags);
460 break;
461 case -EACCES:
462 case -EPERM:
463 case -ENOKEY:
464 case -EKEYEXPIRED:
465 case -EKEYREJECTED:
466 case -EKEYREVOKED:
467 afs_kill_pages(wb->vnode, false, first, last);
468 break;
469 default:
470 break;
471 }
472 } else {
473 ret = count;
474 }
475
476 _leave(" = %d", ret);
477 return ret;
478}
479
480/*
481 * write a page back to the server
482 * - the caller locked the page for us
483 */
484int afs_writepage(struct page *page, struct writeback_control *wbc)
485{
486 struct backing_dev_info *bdi = page->mapping->backing_dev_info;
487 struct afs_writeback *wb;
488 int ret;
489
490 _enter("{%lx},", page->index);
491
492 if (wbc->sync_mode != WB_SYNC_NONE)
493 wait_on_page_writeback(page);
494
495 if (PageWriteback(page) || !PageDirty(page)) {
496 unlock_page(page);
497 return 0;
498 }
499
500 wb = (struct afs_writeback *) page_private(page);
501 ASSERT(wb != NULL);
502
503 ret = afs_write_back_from_locked_page(wb, page);
504 unlock_page(page);
505 if (ret < 0) {
506 _leave(" = %d", ret);
507 return 0;
508 }
509
510 wbc->nr_to_write -= ret;
511 if (wbc->nonblocking && bdi_write_congested(bdi))
512 wbc->encountered_congestion = 1;
513
514 _leave(" = 0");
515 return 0;
516}
517
518/*
519 * write a region of pages back to the server
520 */
521int afs_writepages_region(struct address_space *mapping,
522 struct writeback_control *wbc,
523 pgoff_t index, pgoff_t end, pgoff_t *_next)
524{
525 struct backing_dev_info *bdi = mapping->backing_dev_info;
526 struct afs_writeback *wb;
527 struct page *page;
528 int ret, n;
529
530 _enter(",,%lx,%lx,", index, end);
531
532 do {
533 n = find_get_pages_tag(mapping, &index, PAGECACHE_TAG_DIRTY,
534 1, &page);
535 if (!n)
536 break;
537
538 _debug("wback %lx", page->index);
539
540 if (page->index > end) {
541 *_next = index;
542 page_cache_release(page);
543 _leave(" = 0 [%lx]", *_next);
544 return 0;
545 }
546
547 /* at this point we hold neither mapping->tree_lock nor lock on
548 * the page itself: the page may be truncated or invalidated
549 * (changing page->mapping to NULL), or even swizzled back from
550 * swapper_space to tmpfs file mapping
551 */
552 lock_page(page);
553
554 if (page->mapping != mapping) {
555 unlock_page(page);
556 page_cache_release(page);
557 continue;
558 }
559
560 if (wbc->sync_mode != WB_SYNC_NONE)
561 wait_on_page_writeback(page);
562
563 if (PageWriteback(page) || !PageDirty(page)) {
564 unlock_page(page);
565 continue;
566 }
567
568 wb = (struct afs_writeback *) page_private(page);
569 ASSERT(wb != NULL);
570
571 spin_lock(&wb->vnode->writeback_lock);
572 wb->state = AFS_WBACK_WRITING;
573 spin_unlock(&wb->vnode->writeback_lock);
574
575 ret = afs_write_back_from_locked_page(wb, page);
576 unlock_page(page);
577 page_cache_release(page);
578 if (ret < 0) {
579 _leave(" = %d", ret);
580 return ret;
581 }
582
583 wbc->nr_to_write -= ret;
584
585 if (wbc->nonblocking && bdi_write_congested(bdi)) {
586 wbc->encountered_congestion = 1;
587 break;
588 }
589
590 cond_resched();
591 } while (index < end && wbc->nr_to_write > 0);
592
593 *_next = index;
594 _leave(" = 0 [%lx]", *_next);
595 return 0;
596}
597
598/*
599 * write some of the pending data back to the server
600 */
601int afs_writepages(struct address_space *mapping,
602 struct writeback_control *wbc)
603{
604 struct backing_dev_info *bdi = mapping->backing_dev_info;
605 pgoff_t start, end, next;
606 int ret;
607
608 _enter("");
609
610 if (wbc->nonblocking && bdi_write_congested(bdi)) {
611 wbc->encountered_congestion = 1;
612 _leave(" = 0 [congest]");
613 return 0;
614 }
615
616 if (wbc->range_cyclic) {
617 start = mapping->writeback_index;
618 end = -1;
619 ret = afs_writepages_region(mapping, wbc, start, end, &next);
620 if (start > 0 && wbc->nr_to_write > 0 && ret == 0 &&
621 !(wbc->nonblocking && wbc->encountered_congestion))
622 ret = afs_writepages_region(mapping, wbc, 0, start,
623 &next);
624 mapping->writeback_index = next;
625 } else if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) {
626 end = (pgoff_t)(LLONG_MAX >> PAGE_CACHE_SHIFT);
627 ret = afs_writepages_region(mapping, wbc, 0, end, &next);
628 if (wbc->nr_to_write > 0)
629 mapping->writeback_index = next;
630 } else {
631 start = wbc->range_start >> PAGE_CACHE_SHIFT;
632 end = wbc->range_end >> PAGE_CACHE_SHIFT;
633 ret = afs_writepages_region(mapping, wbc, start, end, &next);
634 }
635
636 _leave(" = %d", ret);
637 return ret;
638}
639
640/*
641 * write an inode back
642 */
643int afs_write_inode(struct inode *inode, int sync)
644{
645 struct afs_vnode *vnode = AFS_FS_I(inode);
646 int ret;
647
648 _enter("{%x:%u},", vnode->fid.vid, vnode->fid.vnode);
649
650 ret = 0;
651 if (sync) {
652 ret = filemap_fdatawait(inode->i_mapping);
653 if (ret < 0)
654 __mark_inode_dirty(inode, I_DIRTY_DATASYNC);
655 }
656
657 _leave(" = %d", ret);
658 return ret;
659}
660
661/*
662 * completion of write to server
663 */
664void afs_pages_written_back(struct afs_vnode *vnode, struct afs_call *call)
665{
666 struct afs_writeback *wb = call->wb;
667 struct pagevec pv;
668 unsigned count, loop;
669 pgoff_t first = call->first, last = call->last;
670 bool free_wb;
671
672 _enter("{%x:%u},{%lx-%lx}",
673 vnode->fid.vid, vnode->fid.vnode, first, last);
674
675 ASSERT(wb != NULL);
676
677 pagevec_init(&pv, 0);
678
679 do {
680 _debug("attach %lx-%lx", first, last);
681
682 count = last - first + 1;
683 if (count > PAGEVEC_SIZE)
684 count = PAGEVEC_SIZE;
685 pv.nr = find_get_pages_contig(call->mapping, first, count,
686 pv.pages);
687 ASSERTCMP(pv.nr, ==, count);
688
689 spin_lock(&vnode->writeback_lock);
690 for (loop = 0; loop < count; loop++) {
691 struct page *page = pv.pages[loop];
692 end_page_writeback(page);
693 if (page_private(page) == (unsigned long) wb) {
694 set_page_private(page, 0);
695 ClearPagePrivate(page);
696 wb->usage--;
697 }
698 }
699 free_wb = false;
700 if (wb->usage == 0) {
701 afs_unlink_writeback(wb);
702 free_wb = true;
703 }
704 spin_unlock(&vnode->writeback_lock);
705 first += count;
706 if (free_wb) {
707 afs_free_writeback(wb);
708 wb = NULL;
709 }
710
711 __pagevec_release(&pv);
712 } while (first < last);
713
714 _leave("");
715}
716
717/*
718 * write to an AFS file
719 */
720ssize_t afs_file_write(struct kiocb *iocb, const struct iovec *iov,
721 unsigned long nr_segs, loff_t pos)
722{
723 struct dentry *dentry = iocb->ki_filp->f_path.dentry;
724 struct afs_vnode *vnode = AFS_FS_I(dentry->d_inode);
725 ssize_t result;
726 size_t count = iov_length(iov, nr_segs);
727 int ret;
728
729 _enter("{%x.%u},{%zu},%lu,",
730 vnode->fid.vid, vnode->fid.vnode, count, nr_segs);
731
732 if (IS_SWAPFILE(&vnode->vfs_inode)) {
733 printk(KERN_INFO
734 "AFS: Attempt to write to active swap file!\n");
735 return -EBUSY;
736 }
737
738 if (!count)
739 return 0;
740
741 result = generic_file_aio_write(iocb, iov, nr_segs, pos);
742 if (IS_ERR_VALUE(result)) {
743 _leave(" = %zd", result);
744 return result;
745 }
746
747 /* return error values for O_SYNC and IS_SYNC() */
748 if (IS_SYNC(&vnode->vfs_inode) || iocb->ki_filp->f_flags & O_SYNC) {
749 ret = afs_fsync(iocb->ki_filp, dentry, 1);
750 if (ret < 0)
751 result = ret;
752 }
753
754 _leave(" = %zd", result);
755 return result;
756}
757
758/*
759 * flush the vnode to the fileserver
760 */
761int afs_writeback_all(struct afs_vnode *vnode)
762{
763 struct address_space *mapping = vnode->vfs_inode.i_mapping;
764 struct writeback_control wbc = {
765 .bdi = mapping->backing_dev_info,
766 .sync_mode = WB_SYNC_ALL,
767 .nr_to_write = LONG_MAX,
768 .for_writepages = 1,
769 .range_cyclic = 1,
770 };
771 int ret;
772
773 _enter("");
774
775 ret = mapping->a_ops->writepages(mapping, &wbc);
776 __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
777
778 _leave(" = %d", ret);
779 return ret;
780}
781
782/*
783 * flush any dirty pages for this process, and check for write errors.
784 * - the return status from this call provides a reliable indication of
785 * whether any write errors occurred for this process.
786 */
787int afs_fsync(struct file *file, struct dentry *dentry, int datasync)
788{
789 struct afs_writeback *wb, *xwb;
790 struct afs_vnode *vnode = AFS_FS_I(dentry->d_inode);
791 int ret;
792
793 _enter("{%x:%u},{n=%s},%d",
794 vnode->fid.vid, vnode->fid.vnode, dentry->d_name.name,
795 datasync);
796
797 /* use a writeback record as a marker in the queue - when this reaches
798 * the front of the queue, all the outstanding writes are either
799 * completed or rejected */
800 wb = kzalloc(sizeof(*wb), GFP_KERNEL);
801 if (!wb)
802 return -ENOMEM;
803 wb->vnode = vnode;
804 wb->first = 0;
805 wb->last = -1;
806 wb->offset_first = 0;
807 wb->to_last = PAGE_SIZE;
808 wb->usage = 1;
809 wb->state = AFS_WBACK_SYNCING;
810 init_waitqueue_head(&wb->waitq);
811
812 spin_lock(&vnode->writeback_lock);
813 list_for_each_entry(xwb, &vnode->writebacks, link) {
814 if (xwb->state == AFS_WBACK_PENDING)
815 xwb->state = AFS_WBACK_CONFLICTING;
816 }
817 list_add_tail(&wb->link, &vnode->writebacks);
818 spin_unlock(&vnode->writeback_lock);
819
820 /* push all the outstanding writebacks to the server */
821 ret = afs_writeback_all(vnode);
822 if (ret < 0) {
823 afs_put_writeback(wb);
824 _leave(" = %d [wb]", ret);
825 return ret;
826 }
827
828 /* wait for the preceding writes to actually complete */
829 ret = wait_event_interruptible(wb->waitq,
830 wb->state == AFS_WBACK_COMPLETE ||
831 vnode->writebacks.next == &wb->link);
832 afs_put_writeback(wb);
833 _leave(" = %d", ret);
834 return ret;
835}
generated by cgit v1.2.2 (git 2.25.0) at 2024-12-14 07:59:27 -0500