fs/afs: use new return type vm_fault_t
[muen/linux.git] / fs / afs / write.c
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  */
23 int 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  */
32 static 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  */
71 int 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
110 try_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          */
156 flush_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  */
175 int 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
217 out:
218         unlock_page(page);
219         put_page(page);
220         return ret;
221 }
222
223 /*
224  * kill all the pages in the given range
225  */
226 static 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  */
267 static 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  */
307 static 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. */
328 try_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
345 found_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  */
392 static 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
492 no_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  */
549 int 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  */
571 static 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  */
637 int 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  */
671 void 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  */
711 ssize_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  */
740 int 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  */
756 vm_fault_t 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  */
802 void 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  */
830 int 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 }