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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/backing-dev.h>
13#include <linux/slab.h>
14#include <linux/fs.h>
15#include <linux/pagemap.h>
16#include <linux/writeback.h>
17#include <linux/pagevec.h>
18#include "internal.h"
19
20/*
21 * mark a page as having been made dirty and thus needing writeback
22 */
23int afs_set_page_dirty(struct page *page)
24{
25 _enter("");
26 return __set_page_dirty_nobuffers(page);
27}
28
29/*
30 * partly or wholly fill a page that's under preparation for writing
31 */
32static int afs_fill_page(struct afs_vnode *vnode, struct key *key,
33 loff_t pos, unsigned int len, struct page *page)
34{
35 struct afs_read *req;
36 int ret;
37
38 _enter(",,%llu", (unsigned long long)pos);
39
40 req = kzalloc(sizeof(struct afs_read) + sizeof(struct page *),
41 GFP_KERNEL);
42 if (!req)
43 return -ENOMEM;
44
45 refcount_set(&req->usage, 1);
46 req->pos = pos;
47 req->len = len;
48 req->nr_pages = 1;
49 req->pages = req->array;
50 req->pages[0] = page;
51 get_page(page);
52
53 ret = afs_fetch_data(vnode, key, req);
54 afs_put_read(req);
55 if (ret < 0) {
56 if (ret == -ENOENT) {
57 _debug("got NOENT from server"
58 " - marking file deleted and stale");
59 set_bit(AFS_VNODE_DELETED, &vnode->flags);
60 ret = -ESTALE;
61 }
62 }
63
64 _leave(" = %d", ret);
65 return ret;
66}
67
68/*
69 * prepare to perform part of a write to a page
70 */
71int afs_write_begin(struct file *file, struct address_space *mapping,
72 loff_t pos, unsigned len, unsigned flags,
73 struct page **pagep, void **fsdata)
74{
75 struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
76 struct page *page;
77 struct key *key = afs_file_key(file);
78 unsigned long priv;
79 unsigned f, from = pos & (PAGE_SIZE - 1);
80 unsigned t, to = from + len;
81 pgoff_t index = pos >> PAGE_SHIFT;
82 int ret;
83
84 _enter("{%x:%u},{%lx},%u,%u",
85 vnode->fid.vid, vnode->fid.vnode, index, from, to);
86
87 /* We want to store information about how much of a page is altered in
88 * page->private.
89 */
90 BUILD_BUG_ON(PAGE_SIZE > 32768 && sizeof(page->private) < 8);
91
92 page = grab_cache_page_write_begin(mapping, index, flags);
93 if (!page)
94 return -ENOMEM;
95
96 if (!PageUptodate(page) && len != PAGE_SIZE) {
97 ret = afs_fill_page(vnode, key, pos & PAGE_MASK, PAGE_SIZE, page);
98 if (ret < 0) {
99 unlock_page(page);
100 put_page(page);
101 _leave(" = %d [prep]", ret);
102 return ret;
103 }
104 SetPageUptodate(page);
105 }
106
107 /* page won't leak in error case: it eventually gets cleaned off LRU */
108 *pagep = page;
109
110try_again:
111 /* See if this page is already partially written in a way that we can
112 * merge the new write with.
113 */
114 t = f = 0;
115 if (PagePrivate(page)) {
116 priv = page_private(page);
117 f = priv & AFS_PRIV_MAX;
118 t = priv >> AFS_PRIV_SHIFT;
119 ASSERTCMP(f, <=, t);
120 }
121
122 if (f != t) {
123 if (PageWriteback(page)) {
124 trace_afs_page_dirty(vnode, tracepoint_string("alrdy"),
125 page->index, priv);
126 goto flush_conflicting_write;
127 }
128 /* If the file is being filled locally, allow inter-write
129 * spaces to be merged into writes. If it's not, only write
130 * back what the user gives us.
131 */
132 if (!test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags) &&
133 (to < f || from > t))
134 goto flush_conflicting_write;
135 if (from < f)
136 f = from;
137 if (to > t)
138 t = to;
139 } else {
140 f = from;
141 t = to;
142 }
143
144 priv = (unsigned long)t << AFS_PRIV_SHIFT;
145 priv |= f;
146 trace_afs_page_dirty(vnode, tracepoint_string("begin"),
147 page->index, priv);
148 SetPagePrivate(page);
149 set_page_private(page, priv);
150 _leave(" = 0");
151 return 0;
152
153 /* The previous write and this write aren't adjacent or overlapping, so
154 * flush the page out.
155 */
156flush_conflicting_write:
157 _debug("flush conflict");
158 ret = write_one_page(page);
159 if (ret < 0) {
160 _leave(" = %d", ret);
161 return ret;
162 }
163
164 ret = lock_page_killable(page);
165 if (ret < 0) {
166 _leave(" = %d", ret);
167 return ret;
168 }
169 goto try_again;
170}
171
172/*
173 * finalise part of a write to a page
174 */
175int afs_write_end(struct file *file, struct address_space *mapping,
176 loff_t pos, unsigned len, unsigned copied,
177 struct page *page, void *fsdata)
178{
179 struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
180 struct key *key = afs_file_key(file);
181 loff_t i_size, maybe_i_size;
182 int ret;
183
184 _enter("{%x:%u},{%lx}",
185 vnode->fid.vid, vnode->fid.vnode, page->index);
186
187 maybe_i_size = pos + copied;
188
189 i_size = i_size_read(&vnode->vfs_inode);
190 if (maybe_i_size > i_size) {
191 spin_lock(&vnode->wb_lock);
192 i_size = i_size_read(&vnode->vfs_inode);
193 if (maybe_i_size > i_size)
194 i_size_write(&vnode->vfs_inode, maybe_i_size);
195 spin_unlock(&vnode->wb_lock);
196 }
197
198 if (!PageUptodate(page)) {
199 if (copied < len) {
200 /* Try and load any missing data from the server. The
201 * unmarshalling routine will take care of clearing any
202 * bits that are beyond the EOF.
203 */
204 ret = afs_fill_page(vnode, key, pos + copied,
205 len - copied, page);
206 if (ret < 0)
207 goto out;
208 }
209 SetPageUptodate(page);
210 }
211
212 set_page_dirty(page);
213 if (PageDirty(page))
214 _debug("dirtied");
215 ret = copied;
216
217out:
218 unlock_page(page);
219 put_page(page);
220 return ret;
221}
222
223/*
224 * kill all the pages in the given range
225 */
226static void afs_kill_pages(struct address_space *mapping,
227 pgoff_t first, pgoff_t last)
228{
229 struct afs_vnode *vnode = AFS_FS_I(mapping->host);
230 struct pagevec pv;
231 unsigned count, loop;
232
233 _enter("{%x:%u},%lx-%lx",
234 vnode->fid.vid, vnode->fid.vnode, first, last);
235
236 pagevec_init(&pv);
237
238 do {
239 _debug("kill %lx-%lx", first, last);
240
241 count = last - first + 1;
242 if (count > PAGEVEC_SIZE)
243 count = PAGEVEC_SIZE;
244 pv.nr = find_get_pages_contig(mapping, first, count, pv.pages);
245 ASSERTCMP(pv.nr, ==, count);
246
247 for (loop = 0; loop < count; loop++) {
248 struct page *page = pv.pages[loop];
249 ClearPageUptodate(page);
250 SetPageError(page);
251 end_page_writeback(page);
252 if (page->index >= first)
253 first = page->index + 1;
254 lock_page(page);
255 generic_error_remove_page(mapping, page);
256 }
257
258 __pagevec_release(&pv);
259 } while (first <= last);
260
261 _leave("");
262}
263
264/*
265 * Redirty all the pages in a given range.
266 */
267static void afs_redirty_pages(struct writeback_control *wbc,
268 struct address_space *mapping,
269 pgoff_t first, pgoff_t last)
270{
271 struct afs_vnode *vnode = AFS_FS_I(mapping->host);
272 struct pagevec pv;
273 unsigned count, loop;
274
275 _enter("{%x:%u},%lx-%lx",
276 vnode->fid.vid, vnode->fid.vnode, first, last);
277
278 pagevec_init(&pv);
279
280 do {
281 _debug("redirty %lx-%lx", first, last);
282
283 count = last - first + 1;
284 if (count > PAGEVEC_SIZE)
285 count = PAGEVEC_SIZE;
286 pv.nr = find_get_pages_contig(mapping, first, count, pv.pages);
287 ASSERTCMP(pv.nr, ==, count);
288
289 for (loop = 0; loop < count; loop++) {
290 struct page *page = pv.pages[loop];
291
292 redirty_page_for_writepage(wbc, page);
293 end_page_writeback(page);
294 if (page->index >= first)
295 first = page->index + 1;
296 }
297
298 __pagevec_release(&pv);
299 } while (first <= last);
300
301 _leave("");
302}
303
304/*
305 * write to a file
306 */
307static int afs_store_data(struct address_space *mapping,
308 pgoff_t first, pgoff_t last,
309 unsigned offset, unsigned to)
310{
311 struct afs_vnode *vnode = AFS_FS_I(mapping->host);
312 struct afs_fs_cursor fc;
313 struct afs_wb_key *wbk = NULL;
314 struct list_head *p;
315 int ret = -ENOKEY, ret2;
316
317 _enter("%s{%x:%u.%u},%lx,%lx,%x,%x",
318 vnode->volume->name,
319 vnode->fid.vid,
320 vnode->fid.vnode,
321 vnode->fid.unique,
322 first, last, offset, to);
323
324 spin_lock(&vnode->wb_lock);
325 p = vnode->wb_keys.next;
326
327 /* Iterate through the list looking for a valid key to use. */
328try_next_key:
329 while (p != &vnode->wb_keys) {
330 wbk = list_entry(p, struct afs_wb_key, vnode_link);
331 _debug("wbk %u", key_serial(wbk->key));
332 ret2 = key_validate(wbk->key);
333 if (ret2 == 0)
334 goto found_key;
335 if (ret == -ENOKEY)
336 ret = ret2;
337 p = p->next;
338 }
339
340 spin_unlock(&vnode->wb_lock);
341 afs_put_wb_key(wbk);
342 _leave(" = %d [no keys]", ret);
343 return ret;
344
345found_key:
346 refcount_inc(&wbk->usage);
347 spin_unlock(&vnode->wb_lock);
348
349 _debug("USE WB KEY %u", key_serial(wbk->key));
350
351 ret = -ERESTARTSYS;
352 if (afs_begin_vnode_operation(&fc, vnode, wbk->key)) {
353 while (afs_select_fileserver(&fc)) {
354 fc.cb_break = afs_calc_vnode_cb_break(vnode);
355 afs_fs_store_data(&fc, mapping, first, last, offset, to);
356 }
357
358 afs_check_for_remote_deletion(&fc, fc.vnode);
359 afs_vnode_commit_status(&fc, vnode, fc.cb_break);
360 ret = afs_end_vnode_operation(&fc);
361 }
362
363 switch (ret) {
364 case 0:
365 afs_stat_v(vnode, n_stores);
366 atomic_long_add((last * PAGE_SIZE + to) -
367 (first * PAGE_SIZE + offset),
368 &afs_v2net(vnode)->n_store_bytes);
369 break;
370 case -EACCES:
371 case -EPERM:
372 case -ENOKEY:
373 case -EKEYEXPIRED:
374 case -EKEYREJECTED:
375 case -EKEYREVOKED:
376 _debug("next");
377 spin_lock(&vnode->wb_lock);
378 p = wbk->vnode_link.next;
379 afs_put_wb_key(wbk);
380 goto try_next_key;
381 }
382
383 afs_put_wb_key(wbk);
384 _leave(" = %d", ret);
385 return ret;
386}
387
388/*
389 * Synchronously write back the locked page and any subsequent non-locked dirty
390 * pages.
391 */
392static int afs_write_back_from_locked_page(struct address_space *mapping,
393 struct writeback_control *wbc,
394 struct page *primary_page,
395 pgoff_t final_page)
396{
397 struct afs_vnode *vnode = AFS_FS_I(mapping->host);
398 struct page *pages[8], *page;
399 unsigned long count, priv;
400 unsigned n, offset, to, f, t;
401 pgoff_t start, first, last;
402 int loop, ret;
403
404 _enter(",%lx", primary_page->index);
405
406 count = 1;
407 if (test_set_page_writeback(primary_page))
408 BUG();
409
410 /* Find all consecutive lockable dirty pages that have contiguous
411 * written regions, stopping when we find a page that is not
412 * immediately lockable, is not dirty or is missing, or we reach the
413 * end of the range.
414 */
415 start = primary_page->index;
416 priv = page_private(primary_page);
417 offset = priv & AFS_PRIV_MAX;
418 to = priv >> AFS_PRIV_SHIFT;
419 trace_afs_page_dirty(vnode, tracepoint_string("store"),
420 primary_page->index, priv);
421
422 WARN_ON(offset == to);
423 if (offset == to)
424 trace_afs_page_dirty(vnode, tracepoint_string("WARN"),
425 primary_page->index, priv);
426
427 if (start >= final_page ||
428 (to < PAGE_SIZE && !test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags)))
429 goto no_more;
430
431 start++;
432 do {
433 _debug("more %lx [%lx]", start, count);
434 n = final_page - start + 1;
435 if (n > ARRAY_SIZE(pages))
436 n = ARRAY_SIZE(pages);
437 n = find_get_pages_contig(mapping, start, ARRAY_SIZE(pages), pages);
438 _debug("fgpc %u", n);
439 if (n == 0)
440 goto no_more;
441 if (pages[0]->index != start) {
442 do {
443 put_page(pages[--n]);
444 } while (n > 0);
445 goto no_more;
446 }
447
448 for (loop = 0; loop < n; loop++) {
449 page = pages[loop];
450 if (to != PAGE_SIZE &&
451 !test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags))
452 break;
453 if (page->index > final_page)
454 break;
455 if (!trylock_page(page))
456 break;
457 if (!PageDirty(page) || PageWriteback(page)) {
458 unlock_page(page);
459 break;
460 }
461
462 priv = page_private(page);
463 f = priv & AFS_PRIV_MAX;
464 t = priv >> AFS_PRIV_SHIFT;
465 if (f != 0 &&
466 !test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags)) {
467 unlock_page(page);
468 break;
469 }
470 to = t;
471
472 trace_afs_page_dirty(vnode, tracepoint_string("store+"),
473 page->index, priv);
474
475 if (!clear_page_dirty_for_io(page))
476 BUG();
477 if (test_set_page_writeback(page))
478 BUG();
479 unlock_page(page);
480 put_page(page);
481 }
482 count += loop;
483 if (loop < n) {
484 for (; loop < n; loop++)
485 put_page(pages[loop]);
486 goto no_more;
487 }
488
489 start += loop;
490 } while (start <= final_page && count < 65536);
491
492no_more:
493 /* We now have a contiguous set of dirty pages, each with writeback
494 * set; the first page is still locked at this point, but all the rest
495 * have been unlocked.
496 */
497 unlock_page(primary_page);
498
499 first = primary_page->index;
500 last = first + count - 1;
501
502 _debug("write back %lx[%u..] to %lx[..%u]", first, offset, last, to);
503
504 ret = afs_store_data(mapping, first, last, offset, to);
505 switch (ret) {
506 case 0:
507 ret = count;
508 break;
509
510 default:
511 pr_notice("kAFS: Unexpected error from FS.StoreData %d\n", ret);
512 /* Fall through */
513 case -EACCES:
514 case -EPERM:
515 case -ENOKEY:
516 case -EKEYEXPIRED:
517 case -EKEYREJECTED:
518 case -EKEYREVOKED:
519 afs_redirty_pages(wbc, mapping, first, last);
520 mapping_set_error(mapping, ret);
521 break;
522
523 case -EDQUOT:
524 case -ENOSPC:
525 afs_redirty_pages(wbc, mapping, first, last);
526 mapping_set_error(mapping, -ENOSPC);
527 break;
528
529 case -EROFS:
530 case -EIO:
531 case -EREMOTEIO:
532 case -EFBIG:
533 case -ENOENT:
534 case -ENOMEDIUM:
535 case -ENXIO:
536 afs_kill_pages(mapping, first, last);
537 mapping_set_error(mapping, ret);
538 break;
539 }
540
541 _leave(" = %d", ret);
542 return ret;
543}
544
545/*
546 * write a page back to the server
547 * - the caller locked the page for us
548 */
549int afs_writepage(struct page *page, struct writeback_control *wbc)
550{
551 int ret;
552
553 _enter("{%lx},", page->index);
554
555 ret = afs_write_back_from_locked_page(page->mapping, wbc, page,
556 wbc->range_end >> PAGE_SHIFT);
557 if (ret < 0) {
558 _leave(" = %d", ret);
559 return 0;
560 }
561
562 wbc->nr_to_write -= ret;
563
564 _leave(" = 0");
565 return 0;
566}
567
568/*
569 * write a region of pages back to the server
570 */
571static int afs_writepages_region(struct address_space *mapping,
572 struct writeback_control *wbc,
573 pgoff_t index, pgoff_t end, pgoff_t *_next)
574{
575 struct page *page;
576 int ret, n;
577
578 _enter(",,%lx,%lx,", index, end);
579
580 do {
581 n = find_get_pages_range_tag(mapping, &index, end,
582 PAGECACHE_TAG_DIRTY, 1, &page);
583 if (!n)
584 break;
585
586 _debug("wback %lx", page->index);
587
588 /*
589 * at this point we hold neither the i_pages lock nor the
590 * page lock: the page may be truncated or invalidated
591 * (changing page->mapping to NULL), or even swizzled
592 * back from swapper_space to tmpfs file mapping
593 */
594 ret = lock_page_killable(page);
595 if (ret < 0) {
596 put_page(page);
597 _leave(" = %d", ret);
598 return ret;
599 }
600
601 if (page->mapping != mapping || !PageDirty(page)) {
602 unlock_page(page);
603 put_page(page);
604 continue;
605 }
606
607 if (PageWriteback(page)) {
608 unlock_page(page);
609 if (wbc->sync_mode != WB_SYNC_NONE)
610 wait_on_page_writeback(page);
611 put_page(page);
612 continue;
613 }
614
615 if (!clear_page_dirty_for_io(page))
616 BUG();
617 ret = afs_write_back_from_locked_page(mapping, wbc, page, end);
618 put_page(page);
619 if (ret < 0) {
620 _leave(" = %d", ret);
621 return ret;
622 }
623
624 wbc->nr_to_write -= ret;
625
626 cond_resched();
627 } while (index < end && wbc->nr_to_write > 0);
628
629 *_next = index;
630 _leave(" = 0 [%lx]", *_next);
631 return 0;
632}
633
634/*
635 * write some of the pending data back to the server
636 */
637int afs_writepages(struct address_space *mapping,
638 struct writeback_control *wbc)
639{
640 pgoff_t start, end, next;
641 int ret;
642
643 _enter("");
644
645 if (wbc->range_cyclic) {
646 start = mapping->writeback_index;
647 end = -1;
648 ret = afs_writepages_region(mapping, wbc, start, end, &next);
649 if (start > 0 && wbc->nr_to_write > 0 && ret == 0)
650 ret = afs_writepages_region(mapping, wbc, 0, start,
651 &next);
652 mapping->writeback_index = next;
653 } else if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) {
654 end = (pgoff_t)(LLONG_MAX >> PAGE_SHIFT);
655 ret = afs_writepages_region(mapping, wbc, 0, end, &next);
656 if (wbc->nr_to_write > 0)
657 mapping->writeback_index = next;
658 } else {
659 start = wbc->range_start >> PAGE_SHIFT;
660 end = wbc->range_end >> PAGE_SHIFT;
661 ret = afs_writepages_region(mapping, wbc, start, end, &next);
662 }
663
664 _leave(" = %d", ret);
665 return ret;
666}
667
668/*
669 * completion of write to server
670 */
671void afs_pages_written_back(struct afs_vnode *vnode, struct afs_call *call)
672{
673 struct pagevec pv;
674 unsigned long priv;
675 unsigned count, loop;
676 pgoff_t first = call->first, last = call->last;
677
678 _enter("{%x:%u},{%lx-%lx}",
679 vnode->fid.vid, vnode->fid.vnode, first, last);
680
681 pagevec_init(&pv);
682
683 do {
684 _debug("done %lx-%lx", first, last);
685
686 count = last - first + 1;
687 if (count > PAGEVEC_SIZE)
688 count = PAGEVEC_SIZE;
689 pv.nr = find_get_pages_contig(vnode->vfs_inode.i_mapping,
690 first, count, pv.pages);
691 ASSERTCMP(pv.nr, ==, count);
692
693 for (loop = 0; loop < count; loop++) {
694 priv = page_private(pv.pages[loop]);
695 trace_afs_page_dirty(vnode, tracepoint_string("clear"),
696 pv.pages[loop]->index, priv);
697 set_page_private(pv.pages[loop], 0);
698 end_page_writeback(pv.pages[loop]);
699 }
700 first += count;
701 __pagevec_release(&pv);
702 } while (first <= last);
703
704 afs_prune_wb_keys(vnode);
705 _leave("");
706}
707
708/*
709 * write to an AFS file
710 */
711ssize_t afs_file_write(struct kiocb *iocb, struct iov_iter *from)
712{
713 struct afs_vnode *vnode = AFS_FS_I(file_inode(iocb->ki_filp));
714 ssize_t result;
715 size_t count = iov_iter_count(from);
716
717 _enter("{%x.%u},{%zu},",
718 vnode->fid.vid, vnode->fid.vnode, count);
719
720 if (IS_SWAPFILE(&vnode->vfs_inode)) {
721 printk(KERN_INFO
722 "AFS: Attempt to write to active swap file!\n");
723 return -EBUSY;
724 }
725
726 if (!count)
727 return 0;
728
729 result = generic_file_write_iter(iocb, from);
730
731 _leave(" = %zd", result);
732 return result;
733}
734
735/*
736 * flush any dirty pages for this process, and check for write errors.
737 * - the return status from this call provides a reliable indication of
738 * whether any write errors occurred for this process.
739 */
740int afs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
741{
742 struct inode *inode = file_inode(file);
743 struct afs_vnode *vnode = AFS_FS_I(inode);
744
745 _enter("{%x:%u},{n=%pD},%d",
746 vnode->fid.vid, vnode->fid.vnode, file,
747 datasync);
748
749 return file_write_and_wait_range(file, start, end);
750}
751
752/*
753 * notification that a previously read-only page is about to become writable
754 * - if it returns an error, the caller will deliver a bus error signal
755 */
756int afs_page_mkwrite(struct vm_fault *vmf)
757{
758 struct file *file = vmf->vma->vm_file;
759 struct inode *inode = file_inode(file);
760 struct afs_vnode *vnode = AFS_FS_I(inode);
761 unsigned long priv;
762
763 _enter("{{%x:%u}},{%lx}",
764 vnode->fid.vid, vnode->fid.vnode, vmf->page->index);
765
766 sb_start_pagefault(inode->i_sb);
767
768 /* Wait for the page to be written to the cache before we allow it to
769 * be modified. We then assume the entire page will need writing back.
770 */
771#ifdef CONFIG_AFS_FSCACHE
772 fscache_wait_on_page_write(vnode->cache, vmf->page);
773#endif
774
775 if (PageWriteback(vmf->page) &&
776 wait_on_page_bit_killable(vmf->page, PG_writeback) < 0)
777 return VM_FAULT_RETRY;
778
779 if (lock_page_killable(vmf->page) < 0)
780 return VM_FAULT_RETRY;
781
782 /* We mustn't change page->private until writeback is complete as that
783 * details the portion of the page we need to write back and we might
784 * need to redirty the page if there's a problem.
785 */
786 wait_on_page_writeback(vmf->page);
787
788 priv = (unsigned long)PAGE_SIZE << AFS_PRIV_SHIFT; /* To */
789 priv |= 0; /* From */
790 trace_afs_page_dirty(vnode, tracepoint_string("mkwrite"),
791 vmf->page->index, priv);
792 SetPagePrivate(vmf->page);
793 set_page_private(vmf->page, priv);
794
795 sb_end_pagefault(inode->i_sb);
796 return VM_FAULT_LOCKED;
797}
798
799/*
800 * Prune the keys cached for writeback. The caller must hold vnode->wb_lock.
801 */
802void afs_prune_wb_keys(struct afs_vnode *vnode)
803{
804 LIST_HEAD(graveyard);
805 struct afs_wb_key *wbk, *tmp;
806
807 /* Discard unused keys */
808 spin_lock(&vnode->wb_lock);
809
810 if (!mapping_tagged(&vnode->vfs_inode.i_data, PAGECACHE_TAG_WRITEBACK) &&
811 !mapping_tagged(&vnode->vfs_inode.i_data, PAGECACHE_TAG_DIRTY)) {
812 list_for_each_entry_safe(wbk, tmp, &vnode->wb_keys, vnode_link) {
813 if (refcount_read(&wbk->usage) == 1)
814 list_move(&wbk->vnode_link, &graveyard);
815 }
816 }
817
818 spin_unlock(&vnode->wb_lock);
819
820 while (!list_empty(&graveyard)) {
821 wbk = list_entry(graveyard.next, struct afs_wb_key, vnode_link);
822 list_del(&wbk->vnode_link);
823 afs_put_wb_key(wbk);
824 }
825}
826
827/*
828 * Clean up a page during invalidation.
829 */
830int afs_launder_page(struct page *page)
831{
832 struct address_space *mapping = page->mapping;
833 struct afs_vnode *vnode = AFS_FS_I(mapping->host);
834 unsigned long priv;
835 unsigned int f, t;
836 int ret = 0;
837
838 _enter("{%lx}", page->index);
839
840 priv = page_private(page);
841 if (clear_page_dirty_for_io(page)) {
842 f = 0;
843 t = PAGE_SIZE;
844 if (PagePrivate(page)) {
845 f = priv & AFS_PRIV_MAX;
846 t = priv >> AFS_PRIV_SHIFT;
847 }
848
849 trace_afs_page_dirty(vnode, tracepoint_string("launder"),
850 page->index, priv);
851 ret = afs_store_data(mapping, page->index, page->index, t, f);
852 }
853
854 trace_afs_page_dirty(vnode, tracepoint_string("laundered"),
855 page->index, priv);
856 set_page_private(page, 0);
857 ClearPagePrivate(page);
858
859#ifdef CONFIG_AFS_FSCACHE
860 if (PageFsCache(page)) {
861 fscache_wait_on_page_write(vnode->cache, page);
862 fscache_uncache_page(vnode->cache, page);
863 }
864#endif
865 return ret;
866}
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#include <linux/backing-dev.h>
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 <linux/aio.h>
18#include "internal.h"
19
20static int afs_write_back_from_locked_page(struct afs_writeback *wb,
21 struct page *page);
22
23/*
24 * mark a page as having been made dirty and thus needing writeback
25 */
26int afs_set_page_dirty(struct page *page)
27{
28 _enter("");
29 return __set_page_dirty_nobuffers(page);
30}
31
32/*
33 * unlink a writeback record because its usage has reached zero
34 * - must be called with the wb->vnode->writeback_lock held
35 */
36static void afs_unlink_writeback(struct afs_writeback *wb)
37{
38 struct afs_writeback *front;
39 struct afs_vnode *vnode = wb->vnode;
40
41 list_del_init(&wb->link);
42 if (!list_empty(&vnode->writebacks)) {
43 /* if an fsync rises to the front of the queue then wake it
44 * up */
45 front = list_entry(vnode->writebacks.next,
46 struct afs_writeback, link);
47 if (front->state == AFS_WBACK_SYNCING) {
48 _debug("wake up sync");
49 front->state = AFS_WBACK_COMPLETE;
50 wake_up(&front->waitq);
51 }
52 }
53}
54
55/*
56 * free a writeback record
57 */
58static void afs_free_writeback(struct afs_writeback *wb)
59{
60 _enter("");
61 key_put(wb->key);
62 kfree(wb);
63}
64
65/*
66 * dispose of a reference to a writeback record
67 */
68void afs_put_writeback(struct afs_writeback *wb)
69{
70 struct afs_vnode *vnode = wb->vnode;
71
72 _enter("{%d}", wb->usage);
73
74 spin_lock(&vnode->writeback_lock);
75 if (--wb->usage == 0)
76 afs_unlink_writeback(wb);
77 else
78 wb = NULL;
79 spin_unlock(&vnode->writeback_lock);
80 if (wb)
81 afs_free_writeback(wb);
82}
83
84/*
85 * partly or wholly fill a page that's under preparation for writing
86 */
87static int afs_fill_page(struct afs_vnode *vnode, struct key *key,
88 loff_t pos, struct page *page)
89{
90 loff_t i_size;
91 int ret;
92 int len;
93
94 _enter(",,%llu", (unsigned long long)pos);
95
96 i_size = i_size_read(&vnode->vfs_inode);
97 if (pos + PAGE_CACHE_SIZE > i_size)
98 len = i_size - pos;
99 else
100 len = PAGE_CACHE_SIZE;
101
102 ret = afs_vnode_fetch_data(vnode, key, pos, len, page);
103 if (ret < 0) {
104 if (ret == -ENOENT) {
105 _debug("got NOENT from server"
106 " - marking file deleted and stale");
107 set_bit(AFS_VNODE_DELETED, &vnode->flags);
108 ret = -ESTALE;
109 }
110 }
111
112 _leave(" = %d", ret);
113 return ret;
114}
115
116/*
117 * prepare to perform part of a write to a page
118 */
119int afs_write_begin(struct file *file, struct address_space *mapping,
120 loff_t pos, unsigned len, unsigned flags,
121 struct page **pagep, void **fsdata)
122{
123 struct afs_writeback *candidate, *wb;
124 struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
125 struct page *page;
126 struct key *key = file->private_data;
127 unsigned from = pos & (PAGE_CACHE_SIZE - 1);
128 unsigned to = from + len;
129 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
130 int ret;
131
132 _enter("{%x:%u},{%lx},%u,%u",
133 vnode->fid.vid, vnode->fid.vnode, index, from, to);
134
135 candidate = kzalloc(sizeof(*candidate), GFP_KERNEL);
136 if (!candidate)
137 return -ENOMEM;
138 candidate->vnode = vnode;
139 candidate->first = candidate->last = index;
140 candidate->offset_first = from;
141 candidate->to_last = to;
142 INIT_LIST_HEAD(&candidate->link);
143 candidate->usage = 1;
144 candidate->state = AFS_WBACK_PENDING;
145 init_waitqueue_head(&candidate->waitq);
146
147 page = grab_cache_page_write_begin(mapping, index, flags);
148 if (!page) {
149 kfree(candidate);
150 return -ENOMEM;
151 }
152 *pagep = page;
153 /* page won't leak in error case: it eventually gets cleaned off LRU */
154
155 if (!PageUptodate(page) && len != PAGE_CACHE_SIZE) {
156 ret = afs_fill_page(vnode, key, index << PAGE_CACHE_SHIFT, page);
157 if (ret < 0) {
158 kfree(candidate);
159 _leave(" = %d [prep]", ret);
160 return ret;
161 }
162 SetPageUptodate(page);
163 }
164
165try_again:
166 spin_lock(&vnode->writeback_lock);
167
168 /* see if this page is already pending a writeback under a suitable key
169 * - if so we can just join onto that one */
170 wb = (struct afs_writeback *) page_private(page);
171 if (wb) {
172 if (wb->key == key && wb->state == AFS_WBACK_PENDING)
173 goto subsume_in_current_wb;
174 goto flush_conflicting_wb;
175 }
176
177 if (index > 0) {
178 /* see if we can find an already pending writeback that we can
179 * append this page to */
180 list_for_each_entry(wb, &vnode->writebacks, link) {
181 if (wb->last == index - 1 && wb->key == key &&
182 wb->state == AFS_WBACK_PENDING)
183 goto append_to_previous_wb;
184 }
185 }
186
187 list_add_tail(&candidate->link, &vnode->writebacks);
188 candidate->key = key_get(key);
189 spin_unlock(&vnode->writeback_lock);
190 SetPagePrivate(page);
191 set_page_private(page, (unsigned long) candidate);
192 _leave(" = 0 [new]");
193 return 0;
194
195subsume_in_current_wb:
196 _debug("subsume");
197 ASSERTRANGE(wb->first, <=, index, <=, wb->last);
198 if (index == wb->first && from < wb->offset_first)
199 wb->offset_first = from;
200 if (index == wb->last && to > wb->to_last)
201 wb->to_last = to;
202 spin_unlock(&vnode->writeback_lock);
203 kfree(candidate);
204 _leave(" = 0 [sub]");
205 return 0;
206
207append_to_previous_wb:
208 _debug("append into %lx-%lx", wb->first, wb->last);
209 wb->usage++;
210 wb->last++;
211 wb->to_last = to;
212 spin_unlock(&vnode->writeback_lock);
213 SetPagePrivate(page);
214 set_page_private(page, (unsigned long) wb);
215 kfree(candidate);
216 _leave(" = 0 [app]");
217 return 0;
218
219 /* the page is currently bound to another context, so if it's dirty we
220 * need to flush it before we can use the new context */
221flush_conflicting_wb:
222 _debug("flush conflict");
223 if (wb->state == AFS_WBACK_PENDING)
224 wb->state = AFS_WBACK_CONFLICTING;
225 spin_unlock(&vnode->writeback_lock);
226 if (PageDirty(page)) {
227 ret = afs_write_back_from_locked_page(wb, page);
228 if (ret < 0) {
229 afs_put_writeback(candidate);
230 _leave(" = %d", ret);
231 return ret;
232 }
233 }
234
235 /* the page holds a ref on the writeback record */
236 afs_put_writeback(wb);
237 set_page_private(page, 0);
238 ClearPagePrivate(page);
239 goto try_again;
240}
241
242/*
243 * finalise part of a write to a page
244 */
245int afs_write_end(struct file *file, struct address_space *mapping,
246 loff_t pos, unsigned len, unsigned copied,
247 struct page *page, void *fsdata)
248{
249 struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
250 loff_t i_size, maybe_i_size;
251
252 _enter("{%x:%u},{%lx}",
253 vnode->fid.vid, vnode->fid.vnode, page->index);
254
255 maybe_i_size = pos + copied;
256
257 i_size = i_size_read(&vnode->vfs_inode);
258 if (maybe_i_size > i_size) {
259 spin_lock(&vnode->writeback_lock);
260 i_size = i_size_read(&vnode->vfs_inode);
261 if (maybe_i_size > i_size)
262 i_size_write(&vnode->vfs_inode, maybe_i_size);
263 spin_unlock(&vnode->writeback_lock);
264 }
265
266 set_page_dirty(page);
267 if (PageDirty(page))
268 _debug("dirtied");
269 unlock_page(page);
270 page_cache_release(page);
271
272 return copied;
273}
274
275/*
276 * kill all the pages in the given range
277 */
278static void afs_kill_pages(struct afs_vnode *vnode, bool error,
279 pgoff_t first, pgoff_t last)
280{
281 struct pagevec pv;
282 unsigned count, loop;
283
284 _enter("{%x:%u},%lx-%lx",
285 vnode->fid.vid, vnode->fid.vnode, first, last);
286
287 pagevec_init(&pv, 0);
288
289 do {
290 _debug("kill %lx-%lx", first, last);
291
292 count = last - first + 1;
293 if (count > PAGEVEC_SIZE)
294 count = PAGEVEC_SIZE;
295 pv.nr = find_get_pages_contig(vnode->vfs_inode.i_mapping,
296 first, count, pv.pages);
297 ASSERTCMP(pv.nr, ==, count);
298
299 for (loop = 0; loop < count; loop++) {
300 ClearPageUptodate(pv.pages[loop]);
301 if (error)
302 SetPageError(pv.pages[loop]);
303 end_page_writeback(pv.pages[loop]);
304 }
305
306 __pagevec_release(&pv);
307 } while (first < last);
308
309 _leave("");
310}
311
312/*
313 * synchronously write back the locked page and any subsequent non-locked dirty
314 * pages also covered by the same writeback record
315 */
316static int afs_write_back_from_locked_page(struct afs_writeback *wb,
317 struct page *primary_page)
318{
319 struct page *pages[8], *page;
320 unsigned long count;
321 unsigned n, offset, to;
322 pgoff_t start, first, last;
323 int loop, ret;
324
325 _enter(",%lx", primary_page->index);
326
327 count = 1;
328 if (!clear_page_dirty_for_io(primary_page))
329 BUG();
330 if (test_set_page_writeback(primary_page))
331 BUG();
332
333 /* find all consecutive lockable dirty pages, stopping when we find a
334 * page that is not immediately lockable, is not dirty or is missing,
335 * or we reach the end of the range */
336 start = primary_page->index;
337 if (start >= wb->last)
338 goto no_more;
339 start++;
340 do {
341 _debug("more %lx [%lx]", start, count);
342 n = wb->last - start + 1;
343 if (n > ARRAY_SIZE(pages))
344 n = ARRAY_SIZE(pages);
345 n = find_get_pages_contig(wb->vnode->vfs_inode.i_mapping,
346 start, n, pages);
347 _debug("fgpc %u", n);
348 if (n == 0)
349 goto no_more;
350 if (pages[0]->index != start) {
351 do {
352 put_page(pages[--n]);
353 } while (n > 0);
354 goto no_more;
355 }
356
357 for (loop = 0; loop < n; loop++) {
358 page = pages[loop];
359 if (page->index > wb->last)
360 break;
361 if (!trylock_page(page))
362 break;
363 if (!PageDirty(page) ||
364 page_private(page) != (unsigned long) wb) {
365 unlock_page(page);
366 break;
367 }
368 if (!clear_page_dirty_for_io(page))
369 BUG();
370 if (test_set_page_writeback(page))
371 BUG();
372 unlock_page(page);
373 put_page(page);
374 }
375 count += loop;
376 if (loop < n) {
377 for (; loop < n; loop++)
378 put_page(pages[loop]);
379 goto no_more;
380 }
381
382 start += loop;
383 } while (start <= wb->last && count < 65536);
384
385no_more:
386 /* we now have a contiguous set of dirty pages, each with writeback set
387 * and the dirty mark cleared; the first page is locked and must remain
388 * so, all the rest are unlocked */
389 first = primary_page->index;
390 last = first + count - 1;
391
392 offset = (first == wb->first) ? wb->offset_first : 0;
393 to = (last == wb->last) ? wb->to_last : PAGE_SIZE;
394
395 _debug("write back %lx[%u..] to %lx[..%u]", first, offset, last, to);
396
397 ret = afs_vnode_store_data(wb, first, last, offset, to);
398 if (ret < 0) {
399 switch (ret) {
400 case -EDQUOT:
401 case -ENOSPC:
402 set_bit(AS_ENOSPC,
403 &wb->vnode->vfs_inode.i_mapping->flags);
404 break;
405 case -EROFS:
406 case -EIO:
407 case -EREMOTEIO:
408 case -EFBIG:
409 case -ENOENT:
410 case -ENOMEDIUM:
411 case -ENXIO:
412 afs_kill_pages(wb->vnode, true, first, last);
413 set_bit(AS_EIO, &wb->vnode->vfs_inode.i_mapping->flags);
414 break;
415 case -EACCES:
416 case -EPERM:
417 case -ENOKEY:
418 case -EKEYEXPIRED:
419 case -EKEYREJECTED:
420 case -EKEYREVOKED:
421 afs_kill_pages(wb->vnode, false, first, last);
422 break;
423 default:
424 break;
425 }
426 } else {
427 ret = count;
428 }
429
430 _leave(" = %d", ret);
431 return ret;
432}
433
434/*
435 * write a page back to the server
436 * - the caller locked the page for us
437 */
438int afs_writepage(struct page *page, struct writeback_control *wbc)
439{
440 struct afs_writeback *wb;
441 int ret;
442
443 _enter("{%lx},", page->index);
444
445 wb = (struct afs_writeback *) page_private(page);
446 ASSERT(wb != NULL);
447
448 ret = afs_write_back_from_locked_page(wb, page);
449 unlock_page(page);
450 if (ret < 0) {
451 _leave(" = %d", ret);
452 return 0;
453 }
454
455 wbc->nr_to_write -= ret;
456
457 _leave(" = 0");
458 return 0;
459}
460
461/*
462 * write a region of pages back to the server
463 */
464static int afs_writepages_region(struct address_space *mapping,
465 struct writeback_control *wbc,
466 pgoff_t index, pgoff_t end, pgoff_t *_next)
467{
468 struct afs_writeback *wb;
469 struct page *page;
470 int ret, n;
471
472 _enter(",,%lx,%lx,", index, end);
473
474 do {
475 n = find_get_pages_tag(mapping, &index, PAGECACHE_TAG_DIRTY,
476 1, &page);
477 if (!n)
478 break;
479
480 _debug("wback %lx", page->index);
481
482 if (page->index > end) {
483 *_next = index;
484 page_cache_release(page);
485 _leave(" = 0 [%lx]", *_next);
486 return 0;
487 }
488
489 /* at this point we hold neither mapping->tree_lock nor lock on
490 * the page itself: the page may be truncated or invalidated
491 * (changing page->mapping to NULL), or even swizzled back from
492 * swapper_space to tmpfs file mapping
493 */
494 lock_page(page);
495
496 if (page->mapping != mapping) {
497 unlock_page(page);
498 page_cache_release(page);
499 continue;
500 }
501
502 if (wbc->sync_mode != WB_SYNC_NONE)
503 wait_on_page_writeback(page);
504
505 if (PageWriteback(page) || !PageDirty(page)) {
506 unlock_page(page);
507 continue;
508 }
509
510 wb = (struct afs_writeback *) page_private(page);
511 ASSERT(wb != NULL);
512
513 spin_lock(&wb->vnode->writeback_lock);
514 wb->state = AFS_WBACK_WRITING;
515 spin_unlock(&wb->vnode->writeback_lock);
516
517 ret = afs_write_back_from_locked_page(wb, page);
518 unlock_page(page);
519 page_cache_release(page);
520 if (ret < 0) {
521 _leave(" = %d", ret);
522 return ret;
523 }
524
525 wbc->nr_to_write -= ret;
526
527 cond_resched();
528 } while (index < end && wbc->nr_to_write > 0);
529
530 *_next = index;
531 _leave(" = 0 [%lx]", *_next);
532 return 0;
533}
534
535/*
536 * write some of the pending data back to the server
537 */
538int afs_writepages(struct address_space *mapping,
539 struct writeback_control *wbc)
540{
541 pgoff_t start, end, next;
542 int ret;
543
544 _enter("");
545
546 if (wbc->range_cyclic) {
547 start = mapping->writeback_index;
548 end = -1;
549 ret = afs_writepages_region(mapping, wbc, start, end, &next);
550 if (start > 0 && wbc->nr_to_write > 0 && ret == 0)
551 ret = afs_writepages_region(mapping, wbc, 0, start,
552 &next);
553 mapping->writeback_index = next;
554 } else if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) {
555 end = (pgoff_t)(LLONG_MAX >> PAGE_CACHE_SHIFT);
556 ret = afs_writepages_region(mapping, wbc, 0, end, &next);
557 if (wbc->nr_to_write > 0)
558 mapping->writeback_index = next;
559 } else {
560 start = wbc->range_start >> PAGE_CACHE_SHIFT;
561 end = wbc->range_end >> PAGE_CACHE_SHIFT;
562 ret = afs_writepages_region(mapping, wbc, start, end, &next);
563 }
564
565 _leave(" = %d", ret);
566 return ret;
567}
568
569/*
570 * completion of write to server
571 */
572void afs_pages_written_back(struct afs_vnode *vnode, struct afs_call *call)
573{
574 struct afs_writeback *wb = call->wb;
575 struct pagevec pv;
576 unsigned count, loop;
577 pgoff_t first = call->first, last = call->last;
578 bool free_wb;
579
580 _enter("{%x:%u},{%lx-%lx}",
581 vnode->fid.vid, vnode->fid.vnode, first, last);
582
583 ASSERT(wb != NULL);
584
585 pagevec_init(&pv, 0);
586
587 do {
588 _debug("done %lx-%lx", first, last);
589
590 count = last - first + 1;
591 if (count > PAGEVEC_SIZE)
592 count = PAGEVEC_SIZE;
593 pv.nr = find_get_pages_contig(call->mapping, first, count,
594 pv.pages);
595 ASSERTCMP(pv.nr, ==, count);
596
597 spin_lock(&vnode->writeback_lock);
598 for (loop = 0; loop < count; loop++) {
599 struct page *page = pv.pages[loop];
600 end_page_writeback(page);
601 if (page_private(page) == (unsigned long) wb) {
602 set_page_private(page, 0);
603 ClearPagePrivate(page);
604 wb->usage--;
605 }
606 }
607 free_wb = false;
608 if (wb->usage == 0) {
609 afs_unlink_writeback(wb);
610 free_wb = true;
611 }
612 spin_unlock(&vnode->writeback_lock);
613 first += count;
614 if (free_wb) {
615 afs_free_writeback(wb);
616 wb = NULL;
617 }
618
619 __pagevec_release(&pv);
620 } while (first <= last);
621
622 _leave("");
623}
624
625/*
626 * write to an AFS file
627 */
628ssize_t afs_file_write(struct kiocb *iocb, const struct iovec *iov,
629 unsigned long nr_segs, loff_t pos)
630{
631 struct afs_vnode *vnode = AFS_FS_I(file_inode(iocb->ki_filp));
632 ssize_t result;
633 size_t count = iov_length(iov, nr_segs);
634
635 _enter("{%x.%u},{%zu},%lu,",
636 vnode->fid.vid, vnode->fid.vnode, count, nr_segs);
637
638 if (IS_SWAPFILE(&vnode->vfs_inode)) {
639 printk(KERN_INFO
640 "AFS: Attempt to write to active swap file!\n");
641 return -EBUSY;
642 }
643
644 if (!count)
645 return 0;
646
647 result = generic_file_aio_write(iocb, iov, nr_segs, pos);
648 if (IS_ERR_VALUE(result)) {
649 _leave(" = %zd", result);
650 return result;
651 }
652
653 _leave(" = %zd", result);
654 return result;
655}
656
657/*
658 * flush the vnode to the fileserver
659 */
660int afs_writeback_all(struct afs_vnode *vnode)
661{
662 struct address_space *mapping = vnode->vfs_inode.i_mapping;
663 struct writeback_control wbc = {
664 .sync_mode = WB_SYNC_ALL,
665 .nr_to_write = LONG_MAX,
666 .range_cyclic = 1,
667 };
668 int ret;
669
670 _enter("");
671
672 ret = mapping->a_ops->writepages(mapping, &wbc);
673 __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
674
675 _leave(" = %d", ret);
676 return ret;
677}
678
679/*
680 * flush any dirty pages for this process, and check for write errors.
681 * - the return status from this call provides a reliable indication of
682 * whether any write errors occurred for this process.
683 */
684int afs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
685{
686 struct dentry *dentry = file->f_path.dentry;
687 struct inode *inode = file->f_mapping->host;
688 struct afs_writeback *wb, *xwb;
689 struct afs_vnode *vnode = AFS_FS_I(dentry->d_inode);
690 int ret;
691
692 _enter("{%x:%u},{n=%s},%d",
693 vnode->fid.vid, vnode->fid.vnode, dentry->d_name.name,
694 datasync);
695
696 ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
697 if (ret)
698 return ret;
699 mutex_lock(&inode->i_mutex);
700
701 /* use a writeback record as a marker in the queue - when this reaches
702 * the front of the queue, all the outstanding writes are either
703 * completed or rejected */
704 wb = kzalloc(sizeof(*wb), GFP_KERNEL);
705 if (!wb) {
706 ret = -ENOMEM;
707 goto out;
708 }
709 wb->vnode = vnode;
710 wb->first = 0;
711 wb->last = -1;
712 wb->offset_first = 0;
713 wb->to_last = PAGE_SIZE;
714 wb->usage = 1;
715 wb->state = AFS_WBACK_SYNCING;
716 init_waitqueue_head(&wb->waitq);
717
718 spin_lock(&vnode->writeback_lock);
719 list_for_each_entry(xwb, &vnode->writebacks, link) {
720 if (xwb->state == AFS_WBACK_PENDING)
721 xwb->state = AFS_WBACK_CONFLICTING;
722 }
723 list_add_tail(&wb->link, &vnode->writebacks);
724 spin_unlock(&vnode->writeback_lock);
725
726 /* push all the outstanding writebacks to the server */
727 ret = afs_writeback_all(vnode);
728 if (ret < 0) {
729 afs_put_writeback(wb);
730 _leave(" = %d [wb]", ret);
731 goto out;
732 }
733
734 /* wait for the preceding writes to actually complete */
735 ret = wait_event_interruptible(wb->waitq,
736 wb->state == AFS_WBACK_COMPLETE ||
737 vnode->writebacks.next == &wb->link);
738 afs_put_writeback(wb);
739 _leave(" = %d", ret);
740out:
741 mutex_unlock(&inode->i_mutex);
742 return ret;
743}
744
745/*
746 * notification that a previously read-only page is about to become writable
747 * - if it returns an error, the caller will deliver a bus error signal
748 */
749int afs_page_mkwrite(struct vm_area_struct *vma, struct page *page)
750{
751 struct afs_vnode *vnode = AFS_FS_I(vma->vm_file->f_mapping->host);
752
753 _enter("{{%x:%u}},{%lx}",
754 vnode->fid.vid, vnode->fid.vnode, page->index);
755
756 /* wait for the page to be written to the cache before we allow it to
757 * be modified */
758#ifdef CONFIG_AFS_FSCACHE
759 fscache_wait_on_page_write(vnode->cache, page);
760#endif
761
762 _leave(" = 0");
763 return 0;
764}