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 */
afs_set_page_dirty(struct page * page)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 */
afs_fill_page(struct afs_vnode * vnode,struct key * key,loff_t pos,unsigned int len,struct page * page)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 */
afs_write_begin(struct file * file,struct address_space * mapping,loff_t pos,unsigned len,unsigned flags,struct page ** pagep,void ** fsdata)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 */
afs_write_end(struct file * file,struct address_space * mapping,loff_t pos,unsigned len,unsigned copied,struct page * page,void * fsdata)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 write_seqlock(&vnode->cb_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 write_sequnlock(&vnode->cb_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 */
afs_kill_pages(struct address_space * mapping,pgoff_t first,pgoff_t last)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 unlock_page(page);
257 }
258
259 __pagevec_release(&pv);
260 } while (first <= last);
261
262 _leave("");
263 }
264
265 /*
266 * Redirty all the pages in a given range.
267 */
afs_redirty_pages(struct writeback_control * wbc,struct address_space * mapping,pgoff_t first,pgoff_t last)268 static void afs_redirty_pages(struct writeback_control *wbc,
269 struct address_space *mapping,
270 pgoff_t first, pgoff_t last)
271 {
272 struct afs_vnode *vnode = AFS_FS_I(mapping->host);
273 struct pagevec pv;
274 unsigned count, loop;
275
276 _enter("{%x:%u},%lx-%lx",
277 vnode->fid.vid, vnode->fid.vnode, first, last);
278
279 pagevec_init(&pv);
280
281 do {
282 _debug("redirty %lx-%lx", first, last);
283
284 count = last - first + 1;
285 if (count > PAGEVEC_SIZE)
286 count = PAGEVEC_SIZE;
287 pv.nr = find_get_pages_contig(mapping, first, count, pv.pages);
288 ASSERTCMP(pv.nr, ==, count);
289
290 for (loop = 0; loop < count; loop++) {
291 struct page *page = pv.pages[loop];
292
293 redirty_page_for_writepage(wbc, page);
294 end_page_writeback(page);
295 if (page->index >= first)
296 first = page->index + 1;
297 }
298
299 __pagevec_release(&pv);
300 } while (first <= last);
301
302 _leave("");
303 }
304
305 /*
306 * write to a file
307 */
afs_store_data(struct address_space * mapping,pgoff_t first,pgoff_t last,unsigned offset,unsigned to)308 static int afs_store_data(struct address_space *mapping,
309 pgoff_t first, pgoff_t last,
310 unsigned offset, unsigned to)
311 {
312 struct afs_vnode *vnode = AFS_FS_I(mapping->host);
313 struct afs_fs_cursor fc;
314 struct afs_wb_key *wbk = NULL;
315 struct list_head *p;
316 int ret = -ENOKEY, ret2;
317
318 _enter("%s{%x:%u.%u},%lx,%lx,%x,%x",
319 vnode->volume->name,
320 vnode->fid.vid,
321 vnode->fid.vnode,
322 vnode->fid.unique,
323 first, last, offset, to);
324
325 spin_lock(&vnode->wb_lock);
326 p = vnode->wb_keys.next;
327
328 /* Iterate through the list looking for a valid key to use. */
329 try_next_key:
330 while (p != &vnode->wb_keys) {
331 wbk = list_entry(p, struct afs_wb_key, vnode_link);
332 _debug("wbk %u", key_serial(wbk->key));
333 ret2 = key_validate(wbk->key);
334 if (ret2 == 0)
335 goto found_key;
336 if (ret == -ENOKEY)
337 ret = ret2;
338 p = p->next;
339 }
340
341 spin_unlock(&vnode->wb_lock);
342 afs_put_wb_key(wbk);
343 _leave(" = %d [no keys]", ret);
344 return ret;
345
346 found_key:
347 refcount_inc(&wbk->usage);
348 spin_unlock(&vnode->wb_lock);
349
350 _debug("USE WB KEY %u", key_serial(wbk->key));
351
352 ret = -ERESTARTSYS;
353 if (afs_begin_vnode_operation(&fc, vnode, wbk->key)) {
354 while (afs_select_fileserver(&fc)) {
355 fc.cb_break = afs_calc_vnode_cb_break(vnode);
356 afs_fs_store_data(&fc, mapping, first, last, offset, to);
357 }
358
359 afs_check_for_remote_deletion(&fc, fc.vnode);
360 afs_vnode_commit_status(&fc, vnode, fc.cb_break);
361 ret = afs_end_vnode_operation(&fc);
362 }
363
364 switch (ret) {
365 case 0:
366 afs_stat_v(vnode, n_stores);
367 atomic_long_add((last * PAGE_SIZE + to) -
368 (first * PAGE_SIZE + offset),
369 &afs_v2net(vnode)->n_store_bytes);
370 break;
371 case -EACCES:
372 case -EPERM:
373 case -ENOKEY:
374 case -EKEYEXPIRED:
375 case -EKEYREJECTED:
376 case -EKEYREVOKED:
377 _debug("next");
378 spin_lock(&vnode->wb_lock);
379 p = wbk->vnode_link.next;
380 afs_put_wb_key(wbk);
381 goto try_next_key;
382 }
383
384 afs_put_wb_key(wbk);
385 _leave(" = %d", ret);
386 return ret;
387 }
388
389 /*
390 * Synchronously write back the locked page and any subsequent non-locked dirty
391 * pages.
392 */
afs_write_back_from_locked_page(struct address_space * mapping,struct writeback_control * wbc,struct page * primary_page,pgoff_t final_page)393 static int afs_write_back_from_locked_page(struct address_space *mapping,
394 struct writeback_control *wbc,
395 struct page *primary_page,
396 pgoff_t final_page)
397 {
398 struct afs_vnode *vnode = AFS_FS_I(mapping->host);
399 struct page *pages[8], *page;
400 unsigned long count, priv;
401 unsigned n, offset, to, f, t;
402 pgoff_t start, first, last;
403 int loop, ret;
404
405 _enter(",%lx", primary_page->index);
406
407 count = 1;
408 if (test_set_page_writeback(primary_page))
409 BUG();
410
411 /* Find all consecutive lockable dirty pages that have contiguous
412 * written regions, stopping when we find a page that is not
413 * immediately lockable, is not dirty or is missing, or we reach the
414 * end of the range.
415 */
416 start = primary_page->index;
417 priv = page_private(primary_page);
418 offset = priv & AFS_PRIV_MAX;
419 to = priv >> AFS_PRIV_SHIFT;
420 trace_afs_page_dirty(vnode, tracepoint_string("store"),
421 primary_page->index, priv);
422
423 WARN_ON(offset == to);
424 if (offset == to)
425 trace_afs_page_dirty(vnode, tracepoint_string("WARN"),
426 primary_page->index, priv);
427
428 if (start >= final_page ||
429 (to < PAGE_SIZE && !test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags)))
430 goto no_more;
431
432 start++;
433 do {
434 _debug("more %lx [%lx]", start, count);
435 n = final_page - start + 1;
436 if (n > ARRAY_SIZE(pages))
437 n = ARRAY_SIZE(pages);
438 n = find_get_pages_contig(mapping, start, ARRAY_SIZE(pages), pages);
439 _debug("fgpc %u", n);
440 if (n == 0)
441 goto no_more;
442 if (pages[0]->index != start) {
443 do {
444 put_page(pages[--n]);
445 } while (n > 0);
446 goto no_more;
447 }
448
449 for (loop = 0; loop < n; loop++) {
450 page = pages[loop];
451 if (to != PAGE_SIZE &&
452 !test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags))
453 break;
454 if (page->index > final_page)
455 break;
456 if (!trylock_page(page))
457 break;
458 if (!PageDirty(page) || PageWriteback(page)) {
459 unlock_page(page);
460 break;
461 }
462
463 priv = page_private(page);
464 f = priv & AFS_PRIV_MAX;
465 t = priv >> AFS_PRIV_SHIFT;
466 if (f != 0 &&
467 !test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags)) {
468 unlock_page(page);
469 break;
470 }
471 to = t;
472
473 trace_afs_page_dirty(vnode, tracepoint_string("store+"),
474 page->index, priv);
475
476 if (!clear_page_dirty_for_io(page))
477 BUG();
478 if (test_set_page_writeback(page))
479 BUG();
480 unlock_page(page);
481 put_page(page);
482 }
483 count += loop;
484 if (loop < n) {
485 for (; loop < n; loop++)
486 put_page(pages[loop]);
487 goto no_more;
488 }
489
490 start += loop;
491 } while (start <= final_page && count < 65536);
492
493 no_more:
494 /* We now have a contiguous set of dirty pages, each with writeback
495 * set; the first page is still locked at this point, but all the rest
496 * have been unlocked.
497 */
498 unlock_page(primary_page);
499
500 first = primary_page->index;
501 last = first + count - 1;
502
503 _debug("write back %lx[%u..] to %lx[..%u]", first, offset, last, to);
504
505 ret = afs_store_data(mapping, first, last, offset, to);
506 switch (ret) {
507 case 0:
508 ret = count;
509 break;
510
511 default:
512 pr_notice("kAFS: Unexpected error from FS.StoreData %d\n", ret);
513 /* Fall through */
514 case -EACCES:
515 case -EPERM:
516 case -ENOKEY:
517 case -EKEYEXPIRED:
518 case -EKEYREJECTED:
519 case -EKEYREVOKED:
520 afs_redirty_pages(wbc, mapping, first, last);
521 mapping_set_error(mapping, ret);
522 break;
523
524 case -EDQUOT:
525 case -ENOSPC:
526 afs_redirty_pages(wbc, mapping, first, last);
527 mapping_set_error(mapping, -ENOSPC);
528 break;
529
530 case -EROFS:
531 case -EIO:
532 case -EREMOTEIO:
533 case -EFBIG:
534 case -ENOENT:
535 case -ENOMEDIUM:
536 case -ENXIO:
537 afs_kill_pages(mapping, first, last);
538 mapping_set_error(mapping, ret);
539 break;
540 }
541
542 _leave(" = %d", ret);
543 return ret;
544 }
545
546 /*
547 * write a page back to the server
548 * - the caller locked the page for us
549 */
afs_writepage(struct page * page,struct writeback_control * wbc)550 int afs_writepage(struct page *page, struct writeback_control *wbc)
551 {
552 int ret;
553
554 _enter("{%lx},", page->index);
555
556 ret = afs_write_back_from_locked_page(page->mapping, wbc, page,
557 wbc->range_end >> PAGE_SHIFT);
558 if (ret < 0) {
559 _leave(" = %d", ret);
560 return 0;
561 }
562
563 wbc->nr_to_write -= ret;
564
565 _leave(" = 0");
566 return 0;
567 }
568
569 /*
570 * write a region of pages back to the server
571 */
afs_writepages_region(struct address_space * mapping,struct writeback_control * wbc,pgoff_t index,pgoff_t end,pgoff_t * _next)572 static int afs_writepages_region(struct address_space *mapping,
573 struct writeback_control *wbc,
574 pgoff_t index, pgoff_t end, pgoff_t *_next)
575 {
576 struct page *page;
577 int ret, n;
578
579 _enter(",,%lx,%lx,", index, end);
580
581 do {
582 n = find_get_pages_range_tag(mapping, &index, end,
583 PAGECACHE_TAG_DIRTY, 1, &page);
584 if (!n)
585 break;
586
587 _debug("wback %lx", page->index);
588
589 /*
590 * at this point we hold neither the i_pages lock nor the
591 * page lock: the page may be truncated or invalidated
592 * (changing page->mapping to NULL), or even swizzled
593 * back from swapper_space to tmpfs file mapping
594 */
595 ret = lock_page_killable(page);
596 if (ret < 0) {
597 put_page(page);
598 _leave(" = %d", ret);
599 return ret;
600 }
601
602 if (page->mapping != mapping || !PageDirty(page)) {
603 unlock_page(page);
604 put_page(page);
605 continue;
606 }
607
608 if (PageWriteback(page)) {
609 unlock_page(page);
610 if (wbc->sync_mode != WB_SYNC_NONE)
611 wait_on_page_writeback(page);
612 put_page(page);
613 continue;
614 }
615
616 if (!clear_page_dirty_for_io(page))
617 BUG();
618 ret = afs_write_back_from_locked_page(mapping, wbc, page, end);
619 put_page(page);
620 if (ret < 0) {
621 _leave(" = %d", ret);
622 return ret;
623 }
624
625 wbc->nr_to_write -= ret;
626
627 cond_resched();
628 } while (index < end && wbc->nr_to_write > 0);
629
630 *_next = index;
631 _leave(" = 0 [%lx]", *_next);
632 return 0;
633 }
634
635 /*
636 * write some of the pending data back to the server
637 */
afs_writepages(struct address_space * mapping,struct writeback_control * wbc)638 int afs_writepages(struct address_space *mapping,
639 struct writeback_control *wbc)
640 {
641 pgoff_t start, end, next;
642 int ret;
643
644 _enter("");
645
646 if (wbc->range_cyclic) {
647 start = mapping->writeback_index;
648 end = -1;
649 ret = afs_writepages_region(mapping, wbc, start, end, &next);
650 if (start > 0 && wbc->nr_to_write > 0 && ret == 0)
651 ret = afs_writepages_region(mapping, wbc, 0, start,
652 &next);
653 mapping->writeback_index = next;
654 } else if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) {
655 end = (pgoff_t)(LLONG_MAX >> PAGE_SHIFT);
656 ret = afs_writepages_region(mapping, wbc, 0, end, &next);
657 if (wbc->nr_to_write > 0)
658 mapping->writeback_index = next;
659 } else {
660 start = wbc->range_start >> PAGE_SHIFT;
661 end = wbc->range_end >> PAGE_SHIFT;
662 ret = afs_writepages_region(mapping, wbc, start, end, &next);
663 }
664
665 _leave(" = %d", ret);
666 return ret;
667 }
668
669 /*
670 * completion of write to server
671 */
afs_pages_written_back(struct afs_vnode * vnode,struct afs_call * call)672 void afs_pages_written_back(struct afs_vnode *vnode, struct afs_call *call)
673 {
674 struct pagevec pv;
675 unsigned long priv;
676 unsigned count, loop;
677 pgoff_t first = call->first, last = call->last;
678
679 _enter("{%x:%u},{%lx-%lx}",
680 vnode->fid.vid, vnode->fid.vnode, first, last);
681
682 pagevec_init(&pv);
683
684 do {
685 _debug("done %lx-%lx", first, last);
686
687 count = last - first + 1;
688 if (count > PAGEVEC_SIZE)
689 count = PAGEVEC_SIZE;
690 pv.nr = find_get_pages_contig(vnode->vfs_inode.i_mapping,
691 first, count, pv.pages);
692 ASSERTCMP(pv.nr, ==, count);
693
694 for (loop = 0; loop < count; loop++) {
695 priv = page_private(pv.pages[loop]);
696 trace_afs_page_dirty(vnode, tracepoint_string("clear"),
697 pv.pages[loop]->index, priv);
698 set_page_private(pv.pages[loop], 0);
699 end_page_writeback(pv.pages[loop]);
700 }
701 first += count;
702 __pagevec_release(&pv);
703 } while (first <= last);
704
705 afs_prune_wb_keys(vnode);
706 _leave("");
707 }
708
709 /*
710 * write to an AFS file
711 */
afs_file_write(struct kiocb * iocb,struct iov_iter * from)712 ssize_t afs_file_write(struct kiocb *iocb, struct iov_iter *from)
713 {
714 struct afs_vnode *vnode = AFS_FS_I(file_inode(iocb->ki_filp));
715 ssize_t result;
716 size_t count = iov_iter_count(from);
717
718 _enter("{%x.%u},{%zu},",
719 vnode->fid.vid, vnode->fid.vnode, count);
720
721 if (IS_SWAPFILE(&vnode->vfs_inode)) {
722 printk(KERN_INFO
723 "AFS: Attempt to write to active swap file!\n");
724 return -EBUSY;
725 }
726
727 if (!count)
728 return 0;
729
730 result = generic_file_write_iter(iocb, from);
731
732 _leave(" = %zd", result);
733 return result;
734 }
735
736 /*
737 * flush any dirty pages for this process, and check for write errors.
738 * - the return status from this call provides a reliable indication of
739 * whether any write errors occurred for this process.
740 */
afs_fsync(struct file * file,loff_t start,loff_t end,int datasync)741 int afs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
742 {
743 struct inode *inode = file_inode(file);
744 struct afs_vnode *vnode = AFS_FS_I(inode);
745
746 _enter("{%x:%u},{n=%pD},%d",
747 vnode->fid.vid, vnode->fid.vnode, file,
748 datasync);
749
750 return file_write_and_wait_range(file, start, end);
751 }
752
753 /*
754 * notification that a previously read-only page is about to become writable
755 * - if it returns an error, the caller will deliver a bus error signal
756 */
afs_page_mkwrite(struct vm_fault * vmf)757 vm_fault_t afs_page_mkwrite(struct vm_fault *vmf)
758 {
759 struct file *file = vmf->vma->vm_file;
760 struct inode *inode = file_inode(file);
761 struct afs_vnode *vnode = AFS_FS_I(inode);
762 unsigned long priv;
763
764 _enter("{{%x:%u}},{%lx}",
765 vnode->fid.vid, vnode->fid.vnode, vmf->page->index);
766
767 sb_start_pagefault(inode->i_sb);
768
769 /* Wait for the page to be written to the cache before we allow it to
770 * be modified. We then assume the entire page will need writing back.
771 */
772 #ifdef CONFIG_AFS_FSCACHE
773 fscache_wait_on_page_write(vnode->cache, vmf->page);
774 #endif
775
776 if (PageWriteback(vmf->page) &&
777 wait_on_page_bit_killable(vmf->page, PG_writeback) < 0)
778 return VM_FAULT_RETRY;
779
780 if (lock_page_killable(vmf->page) < 0)
781 return VM_FAULT_RETRY;
782
783 /* We mustn't change page->private until writeback is complete as that
784 * details the portion of the page we need to write back and we might
785 * need to redirty the page if there's a problem.
786 */
787 wait_on_page_writeback(vmf->page);
788
789 priv = (unsigned long)PAGE_SIZE << AFS_PRIV_SHIFT; /* To */
790 priv |= 0; /* From */
791 trace_afs_page_dirty(vnode, tracepoint_string("mkwrite"),
792 vmf->page->index, priv);
793 SetPagePrivate(vmf->page);
794 set_page_private(vmf->page, priv);
795 file_update_time(file);
796
797 sb_end_pagefault(inode->i_sb);
798 return VM_FAULT_LOCKED;
799 }
800
801 /*
802 * Prune the keys cached for writeback. The caller must hold vnode->wb_lock.
803 */
afs_prune_wb_keys(struct afs_vnode * vnode)804 void afs_prune_wb_keys(struct afs_vnode *vnode)
805 {
806 LIST_HEAD(graveyard);
807 struct afs_wb_key *wbk, *tmp;
808
809 /* Discard unused keys */
810 spin_lock(&vnode->wb_lock);
811
812 if (!mapping_tagged(&vnode->vfs_inode.i_data, PAGECACHE_TAG_WRITEBACK) &&
813 !mapping_tagged(&vnode->vfs_inode.i_data, PAGECACHE_TAG_DIRTY)) {
814 list_for_each_entry_safe(wbk, tmp, &vnode->wb_keys, vnode_link) {
815 if (refcount_read(&wbk->usage) == 1)
816 list_move(&wbk->vnode_link, &graveyard);
817 }
818 }
819
820 spin_unlock(&vnode->wb_lock);
821
822 while (!list_empty(&graveyard)) {
823 wbk = list_entry(graveyard.next, struct afs_wb_key, vnode_link);
824 list_del(&wbk->vnode_link);
825 afs_put_wb_key(wbk);
826 }
827 }
828
829 /*
830 * Clean up a page during invalidation.
831 */
afs_launder_page(struct page * page)832 int afs_launder_page(struct page *page)
833 {
834 struct address_space *mapping = page->mapping;
835 struct afs_vnode *vnode = AFS_FS_I(mapping->host);
836 unsigned long priv;
837 unsigned int f, t;
838 int ret = 0;
839
840 _enter("{%lx}", page->index);
841
842 priv = page_private(page);
843 if (clear_page_dirty_for_io(page)) {
844 f = 0;
845 t = PAGE_SIZE;
846 if (PagePrivate(page)) {
847 f = priv & AFS_PRIV_MAX;
848 t = priv >> AFS_PRIV_SHIFT;
849 }
850
851 trace_afs_page_dirty(vnode, tracepoint_string("launder"),
852 page->index, priv);
853 ret = afs_store_data(mapping, page->index, page->index, t, f);
854 }
855
856 trace_afs_page_dirty(vnode, tracepoint_string("laundered"),
857 page->index, priv);
858 set_page_private(page, 0);
859 ClearPagePrivate(page);
860
861 #ifdef CONFIG_AFS_FSCACHE
862 if (PageFsCache(page)) {
863 fscache_wait_on_page_write(vnode->cache, page);
864 fscache_uncache_page(vnode->cache, page);
865 }
866 #endif
867 return ret;
868 }
869