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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// SPDX-License-Identifier: GPL-2.0-or-later
2/* handling of writes to regular files and writing back to the server
3 *
4 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8#include <linux/backing-dev.h>
9#include <linux/slab.h>
10#include <linux/fs.h>
11#include <linux/pagemap.h>
12#include <linux/writeback.h>
13#include <linux/pagevec.h>
14#include "internal.h"
15
16/*
17 * mark a page as having been made dirty and thus needing writeback
18 */
19int afs_set_page_dirty(struct page *page)
20{
21 _enter("");
22 return __set_page_dirty_nobuffers(page);
23}
24
25/*
26 * partly or wholly fill a page that's under preparation for writing
27 */
28static int afs_fill_page(struct afs_vnode *vnode, struct key *key,
29 loff_t pos, unsigned int len, struct page *page)
30{
31 struct afs_read *req;
32 size_t p;
33 void *data;
34 int ret;
35
36 _enter(",,%llu", (unsigned long long)pos);
37
38 if (pos >= vnode->vfs_inode.i_size) {
39 p = pos & ~PAGE_MASK;
40 ASSERTCMP(p + len, <=, PAGE_SIZE);
41 data = kmap(page);
42 memset(data + p, 0, len);
43 kunmap(page);
44 return 0;
45 }
46
47 req = kzalloc(struct_size(req, array, 1), GFP_KERNEL);
48 if (!req)
49 return -ENOMEM;
50
51 refcount_set(&req->usage, 1);
52 req->pos = pos;
53 req->len = len;
54 req->nr_pages = 1;
55 req->pages = req->array;
56 req->pages[0] = page;
57 get_page(page);
58
59 ret = afs_fetch_data(vnode, key, req);
60 afs_put_read(req);
61 if (ret < 0) {
62 if (ret == -ENOENT) {
63 _debug("got NOENT from server"
64 " - marking file deleted and stale");
65 set_bit(AFS_VNODE_DELETED, &vnode->flags);
66 ret = -ESTALE;
67 }
68 }
69
70 _leave(" = %d", ret);
71 return ret;
72}
73
74/*
75 * prepare to perform part of a write to a page
76 */
77int afs_write_begin(struct file *file, struct address_space *mapping,
78 loff_t pos, unsigned len, unsigned flags,
79 struct page **pagep, void **fsdata)
80{
81 struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
82 struct page *page;
83 struct key *key = afs_file_key(file);
84 unsigned long priv;
85 unsigned f, from = pos & (PAGE_SIZE - 1);
86 unsigned t, to = from + len;
87 pgoff_t index = pos >> PAGE_SHIFT;
88 int ret;
89
90 _enter("{%llx:%llu},{%lx},%u,%u",
91 vnode->fid.vid, vnode->fid.vnode, index, from, to);
92
93 /* We want to store information about how much of a page is altered in
94 * page->private.
95 */
96 BUILD_BUG_ON(PAGE_SIZE > 32768 && sizeof(page->private) < 8);
97
98 page = grab_cache_page_write_begin(mapping, index, flags);
99 if (!page)
100 return -ENOMEM;
101
102 if (!PageUptodate(page) && len != PAGE_SIZE) {
103 ret = afs_fill_page(vnode, key, pos & PAGE_MASK, PAGE_SIZE, page);
104 if (ret < 0) {
105 unlock_page(page);
106 put_page(page);
107 _leave(" = %d [prep]", ret);
108 return ret;
109 }
110 SetPageUptodate(page);
111 }
112
113 /* page won't leak in error case: it eventually gets cleaned off LRU */
114 *pagep = page;
115
116try_again:
117 /* See if this page is already partially written in a way that we can
118 * merge the new write with.
119 */
120 t = f = 0;
121 if (PagePrivate(page)) {
122 priv = page_private(page);
123 f = priv & AFS_PRIV_MAX;
124 t = priv >> AFS_PRIV_SHIFT;
125 ASSERTCMP(f, <=, t);
126 }
127
128 if (f != t) {
129 if (PageWriteback(page)) {
130 trace_afs_page_dirty(vnode, tracepoint_string("alrdy"),
131 page->index, priv);
132 goto flush_conflicting_write;
133 }
134 /* If the file is being filled locally, allow inter-write
135 * spaces to be merged into writes. If it's not, only write
136 * back what the user gives us.
137 */
138 if (!test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags) &&
139 (to < f || from > t))
140 goto flush_conflicting_write;
141 if (from < f)
142 f = from;
143 if (to > t)
144 t = to;
145 } else {
146 f = from;
147 t = to;
148 }
149
150 priv = (unsigned long)t << AFS_PRIV_SHIFT;
151 priv |= f;
152 trace_afs_page_dirty(vnode, tracepoint_string("begin"),
153 page->index, priv);
154 SetPagePrivate(page);
155 set_page_private(page, priv);
156 _leave(" = 0");
157 return 0;
158
159 /* The previous write and this write aren't adjacent or overlapping, so
160 * flush the page out.
161 */
162flush_conflicting_write:
163 _debug("flush conflict");
164 ret = write_one_page(page);
165 if (ret < 0) {
166 _leave(" = %d", ret);
167 return ret;
168 }
169
170 ret = lock_page_killable(page);
171 if (ret < 0) {
172 _leave(" = %d", ret);
173 return ret;
174 }
175 goto try_again;
176}
177
178/*
179 * finalise part of a write to a page
180 */
181int afs_write_end(struct file *file, struct address_space *mapping,
182 loff_t pos, unsigned len, unsigned copied,
183 struct page *page, void *fsdata)
184{
185 struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
186 struct key *key = afs_file_key(file);
187 loff_t i_size, maybe_i_size;
188 int ret;
189
190 _enter("{%llx:%llu},{%lx}",
191 vnode->fid.vid, vnode->fid.vnode, page->index);
192
193 maybe_i_size = pos + copied;
194
195 i_size = i_size_read(&vnode->vfs_inode);
196 if (maybe_i_size > i_size) {
197 write_seqlock(&vnode->cb_lock);
198 i_size = i_size_read(&vnode->vfs_inode);
199 if (maybe_i_size > i_size)
200 i_size_write(&vnode->vfs_inode, maybe_i_size);
201 write_sequnlock(&vnode->cb_lock);
202 }
203
204 if (!PageUptodate(page)) {
205 if (copied < len) {
206 /* Try and load any missing data from the server. The
207 * unmarshalling routine will take care of clearing any
208 * bits that are beyond the EOF.
209 */
210 ret = afs_fill_page(vnode, key, pos + copied,
211 len - copied, page);
212 if (ret < 0)
213 goto out;
214 }
215 SetPageUptodate(page);
216 }
217
218 set_page_dirty(page);
219 if (PageDirty(page))
220 _debug("dirtied");
221 ret = copied;
222
223out:
224 unlock_page(page);
225 put_page(page);
226 return ret;
227}
228
229/*
230 * kill all the pages in the given range
231 */
232static void afs_kill_pages(struct address_space *mapping,
233 pgoff_t first, pgoff_t last)
234{
235 struct afs_vnode *vnode = AFS_FS_I(mapping->host);
236 struct pagevec pv;
237 unsigned count, loop;
238
239 _enter("{%llx:%llu},%lx-%lx",
240 vnode->fid.vid, vnode->fid.vnode, first, last);
241
242 pagevec_init(&pv);
243
244 do {
245 _debug("kill %lx-%lx", first, last);
246
247 count = last - first + 1;
248 if (count > PAGEVEC_SIZE)
249 count = PAGEVEC_SIZE;
250 pv.nr = find_get_pages_contig(mapping, first, count, pv.pages);
251 ASSERTCMP(pv.nr, ==, count);
252
253 for (loop = 0; loop < count; loop++) {
254 struct page *page = pv.pages[loop];
255 ClearPageUptodate(page);
256 SetPageError(page);
257 end_page_writeback(page);
258 if (page->index >= first)
259 first = page->index + 1;
260 lock_page(page);
261 generic_error_remove_page(mapping, page);
262 unlock_page(page);
263 }
264
265 __pagevec_release(&pv);
266 } while (first <= last);
267
268 _leave("");
269}
270
271/*
272 * Redirty all the pages in a given range.
273 */
274static void afs_redirty_pages(struct writeback_control *wbc,
275 struct address_space *mapping,
276 pgoff_t first, pgoff_t last)
277{
278 struct afs_vnode *vnode = AFS_FS_I(mapping->host);
279 struct pagevec pv;
280 unsigned count, loop;
281
282 _enter("{%llx:%llu},%lx-%lx",
283 vnode->fid.vid, vnode->fid.vnode, first, last);
284
285 pagevec_init(&pv);
286
287 do {
288 _debug("redirty %lx-%lx", first, last);
289
290 count = last - first + 1;
291 if (count > PAGEVEC_SIZE)
292 count = PAGEVEC_SIZE;
293 pv.nr = find_get_pages_contig(mapping, first, count, pv.pages);
294 ASSERTCMP(pv.nr, ==, count);
295
296 for (loop = 0; loop < count; loop++) {
297 struct page *page = pv.pages[loop];
298
299 redirty_page_for_writepage(wbc, page);
300 end_page_writeback(page);
301 if (page->index >= first)
302 first = page->index + 1;
303 }
304
305 __pagevec_release(&pv);
306 } while (first <= last);
307
308 _leave("");
309}
310
311/*
312 * completion of write to server
313 */
314static void afs_pages_written_back(struct afs_vnode *vnode,
315 pgoff_t first, pgoff_t last)
316{
317 struct pagevec pv;
318 unsigned long priv;
319 unsigned count, loop;
320
321 _enter("{%llx:%llu},{%lx-%lx}",
322 vnode->fid.vid, vnode->fid.vnode, first, last);
323
324 pagevec_init(&pv);
325
326 do {
327 _debug("done %lx-%lx", first, last);
328
329 count = last - first + 1;
330 if (count > PAGEVEC_SIZE)
331 count = PAGEVEC_SIZE;
332 pv.nr = find_get_pages_contig(vnode->vfs_inode.i_mapping,
333 first, count, pv.pages);
334 ASSERTCMP(pv.nr, ==, count);
335
336 for (loop = 0; loop < count; loop++) {
337 priv = page_private(pv.pages[loop]);
338 trace_afs_page_dirty(vnode, tracepoint_string("clear"),
339 pv.pages[loop]->index, priv);
340 set_page_private(pv.pages[loop], 0);
341 end_page_writeback(pv.pages[loop]);
342 }
343 first += count;
344 __pagevec_release(&pv);
345 } while (first <= last);
346
347 afs_prune_wb_keys(vnode);
348 _leave("");
349}
350
351/*
352 * Find a key to use for the writeback. We cached the keys used to author the
353 * writes on the vnode. *_wbk will contain the last writeback key used or NULL
354 * and we need to start from there if it's set.
355 */
356static int afs_get_writeback_key(struct afs_vnode *vnode,
357 struct afs_wb_key **_wbk)
358{
359 struct afs_wb_key *wbk = NULL;
360 struct list_head *p;
361 int ret = -ENOKEY, ret2;
362
363 spin_lock(&vnode->wb_lock);
364 if (*_wbk)
365 p = (*_wbk)->vnode_link.next;
366 else
367 p = vnode->wb_keys.next;
368
369 while (p != &vnode->wb_keys) {
370 wbk = list_entry(p, struct afs_wb_key, vnode_link);
371 _debug("wbk %u", key_serial(wbk->key));
372 ret2 = key_validate(wbk->key);
373 if (ret2 == 0) {
374 refcount_inc(&wbk->usage);
375 _debug("USE WB KEY %u", key_serial(wbk->key));
376 break;
377 }
378
379 wbk = NULL;
380 if (ret == -ENOKEY)
381 ret = ret2;
382 p = p->next;
383 }
384
385 spin_unlock(&vnode->wb_lock);
386 if (*_wbk)
387 afs_put_wb_key(*_wbk);
388 *_wbk = wbk;
389 return 0;
390}
391
392static void afs_store_data_success(struct afs_operation *op)
393{
394 struct afs_vnode *vnode = op->file[0].vnode;
395
396 op->ctime = op->file[0].scb.status.mtime_client;
397 afs_vnode_commit_status(op, &op->file[0]);
398 if (op->error == 0) {
399 afs_pages_written_back(vnode, op->store.first, op->store.last);
400 afs_stat_v(vnode, n_stores);
401 atomic_long_add((op->store.last * PAGE_SIZE + op->store.last_to) -
402 (op->store.first * PAGE_SIZE + op->store.first_offset),
403 &afs_v2net(vnode)->n_store_bytes);
404 }
405}
406
407static const struct afs_operation_ops afs_store_data_operation = {
408 .issue_afs_rpc = afs_fs_store_data,
409 .issue_yfs_rpc = yfs_fs_store_data,
410 .success = afs_store_data_success,
411};
412
413/*
414 * write to a file
415 */
416static int afs_store_data(struct address_space *mapping,
417 pgoff_t first, pgoff_t last,
418 unsigned offset, unsigned to)
419{
420 struct afs_vnode *vnode = AFS_FS_I(mapping->host);
421 struct afs_operation *op;
422 struct afs_wb_key *wbk = NULL;
423 int ret;
424
425 _enter("%s{%llx:%llu.%u},%lx,%lx,%x,%x",
426 vnode->volume->name,
427 vnode->fid.vid,
428 vnode->fid.vnode,
429 vnode->fid.unique,
430 first, last, offset, to);
431
432 ret = afs_get_writeback_key(vnode, &wbk);
433 if (ret) {
434 _leave(" = %d [no keys]", ret);
435 return ret;
436 }
437
438 op = afs_alloc_operation(wbk->key, vnode->volume);
439 if (IS_ERR(op)) {
440 afs_put_wb_key(wbk);
441 return -ENOMEM;
442 }
443
444 afs_op_set_vnode(op, 0, vnode);
445 op->file[0].dv_delta = 1;
446 op->store.mapping = mapping;
447 op->store.first = first;
448 op->store.last = last;
449 op->store.first_offset = offset;
450 op->store.last_to = to;
451 op->mtime = vnode->vfs_inode.i_mtime;
452 op->flags |= AFS_OPERATION_UNINTR;
453 op->ops = &afs_store_data_operation;
454
455try_next_key:
456 afs_begin_vnode_operation(op);
457 afs_wait_for_operation(op);
458
459 switch (op->error) {
460 case -EACCES:
461 case -EPERM:
462 case -ENOKEY:
463 case -EKEYEXPIRED:
464 case -EKEYREJECTED:
465 case -EKEYREVOKED:
466 _debug("next");
467
468 ret = afs_get_writeback_key(vnode, &wbk);
469 if (ret == 0) {
470 key_put(op->key);
471 op->key = key_get(wbk->key);
472 goto try_next_key;
473 }
474 break;
475 }
476
477 afs_put_wb_key(wbk);
478 _leave(" = %d", op->error);
479 return afs_put_operation(op);
480}
481
482/*
483 * Synchronously write back the locked page and any subsequent non-locked dirty
484 * pages.
485 */
486static int afs_write_back_from_locked_page(struct address_space *mapping,
487 struct writeback_control *wbc,
488 struct page *primary_page,
489 pgoff_t final_page)
490{
491 struct afs_vnode *vnode = AFS_FS_I(mapping->host);
492 struct page *pages[8], *page;
493 unsigned long count, priv;
494 unsigned n, offset, to, f, t;
495 pgoff_t start, first, last;
496 loff_t i_size, end;
497 int loop, ret;
498
499 _enter(",%lx", primary_page->index);
500
501 count = 1;
502 if (test_set_page_writeback(primary_page))
503 BUG();
504
505 /* Find all consecutive lockable dirty pages that have contiguous
506 * written regions, stopping when we find a page that is not
507 * immediately lockable, is not dirty or is missing, or we reach the
508 * end of the range.
509 */
510 start = primary_page->index;
511 priv = page_private(primary_page);
512 offset = priv & AFS_PRIV_MAX;
513 to = priv >> AFS_PRIV_SHIFT;
514 trace_afs_page_dirty(vnode, tracepoint_string("store"),
515 primary_page->index, priv);
516
517 WARN_ON(offset == to);
518 if (offset == to)
519 trace_afs_page_dirty(vnode, tracepoint_string("WARN"),
520 primary_page->index, priv);
521
522 if (start >= final_page ||
523 (to < PAGE_SIZE && !test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags)))
524 goto no_more;
525
526 start++;
527 do {
528 _debug("more %lx [%lx]", start, count);
529 n = final_page - start + 1;
530 if (n > ARRAY_SIZE(pages))
531 n = ARRAY_SIZE(pages);
532 n = find_get_pages_contig(mapping, start, ARRAY_SIZE(pages), pages);
533 _debug("fgpc %u", n);
534 if (n == 0)
535 goto no_more;
536 if (pages[0]->index != start) {
537 do {
538 put_page(pages[--n]);
539 } while (n > 0);
540 goto no_more;
541 }
542
543 for (loop = 0; loop < n; loop++) {
544 page = pages[loop];
545 if (to != PAGE_SIZE &&
546 !test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags))
547 break;
548 if (page->index > final_page)
549 break;
550 if (!trylock_page(page))
551 break;
552 if (!PageDirty(page) || PageWriteback(page)) {
553 unlock_page(page);
554 break;
555 }
556
557 priv = page_private(page);
558 f = priv & AFS_PRIV_MAX;
559 t = priv >> AFS_PRIV_SHIFT;
560 if (f != 0 &&
561 !test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags)) {
562 unlock_page(page);
563 break;
564 }
565 to = t;
566
567 trace_afs_page_dirty(vnode, tracepoint_string("store+"),
568 page->index, priv);
569
570 if (!clear_page_dirty_for_io(page))
571 BUG();
572 if (test_set_page_writeback(page))
573 BUG();
574 unlock_page(page);
575 put_page(page);
576 }
577 count += loop;
578 if (loop < n) {
579 for (; loop < n; loop++)
580 put_page(pages[loop]);
581 goto no_more;
582 }
583
584 start += loop;
585 } while (start <= final_page && count < 65536);
586
587no_more:
588 /* We now have a contiguous set of dirty pages, each with writeback
589 * set; the first page is still locked at this point, but all the rest
590 * have been unlocked.
591 */
592 unlock_page(primary_page);
593
594 first = primary_page->index;
595 last = first + count - 1;
596
597 end = (loff_t)last * PAGE_SIZE + to;
598 i_size = i_size_read(&vnode->vfs_inode);
599
600 _debug("write back %lx[%u..] to %lx[..%u]", first, offset, last, to);
601 if (end > i_size)
602 to = i_size & ~PAGE_MASK;
603
604 ret = afs_store_data(mapping, first, last, offset, to);
605 switch (ret) {
606 case 0:
607 ret = count;
608 break;
609
610 default:
611 pr_notice("kAFS: Unexpected error from FS.StoreData %d\n", ret);
612 fallthrough;
613 case -EACCES:
614 case -EPERM:
615 case -ENOKEY:
616 case -EKEYEXPIRED:
617 case -EKEYREJECTED:
618 case -EKEYREVOKED:
619 afs_redirty_pages(wbc, mapping, first, last);
620 mapping_set_error(mapping, ret);
621 break;
622
623 case -EDQUOT:
624 case -ENOSPC:
625 afs_redirty_pages(wbc, mapping, first, last);
626 mapping_set_error(mapping, -ENOSPC);
627 break;
628
629 case -EROFS:
630 case -EIO:
631 case -EREMOTEIO:
632 case -EFBIG:
633 case -ENOENT:
634 case -ENOMEDIUM:
635 case -ENXIO:
636 trace_afs_file_error(vnode, ret, afs_file_error_writeback_fail);
637 afs_kill_pages(mapping, first, last);
638 mapping_set_error(mapping, ret);
639 break;
640 }
641
642 _leave(" = %d", ret);
643 return ret;
644}
645
646/*
647 * write a page back to the server
648 * - the caller locked the page for us
649 */
650int afs_writepage(struct page *page, struct writeback_control *wbc)
651{
652 int ret;
653
654 _enter("{%lx},", page->index);
655
656 ret = afs_write_back_from_locked_page(page->mapping, wbc, page,
657 wbc->range_end >> PAGE_SHIFT);
658 if (ret < 0) {
659 _leave(" = %d", ret);
660 return 0;
661 }
662
663 wbc->nr_to_write -= ret;
664
665 _leave(" = 0");
666 return 0;
667}
668
669/*
670 * write a region of pages back to the server
671 */
672static int afs_writepages_region(struct address_space *mapping,
673 struct writeback_control *wbc,
674 pgoff_t index, pgoff_t end, pgoff_t *_next)
675{
676 struct page *page;
677 int ret, n;
678
679 _enter(",,%lx,%lx,", index, end);
680
681 do {
682 n = find_get_pages_range_tag(mapping, &index, end,
683 PAGECACHE_TAG_DIRTY, 1, &page);
684 if (!n)
685 break;
686
687 _debug("wback %lx", page->index);
688
689 /*
690 * at this point we hold neither the i_pages lock nor the
691 * page lock: the page may be truncated or invalidated
692 * (changing page->mapping to NULL), or even swizzled
693 * back from swapper_space to tmpfs file mapping
694 */
695 ret = lock_page_killable(page);
696 if (ret < 0) {
697 put_page(page);
698 _leave(" = %d", ret);
699 return ret;
700 }
701
702 if (page->mapping != mapping || !PageDirty(page)) {
703 unlock_page(page);
704 put_page(page);
705 continue;
706 }
707
708 if (PageWriteback(page)) {
709 unlock_page(page);
710 if (wbc->sync_mode != WB_SYNC_NONE)
711 wait_on_page_writeback(page);
712 put_page(page);
713 continue;
714 }
715
716 if (!clear_page_dirty_for_io(page))
717 BUG();
718 ret = afs_write_back_from_locked_page(mapping, wbc, page, end);
719 put_page(page);
720 if (ret < 0) {
721 _leave(" = %d", ret);
722 return ret;
723 }
724
725 wbc->nr_to_write -= ret;
726
727 cond_resched();
728 } while (index < end && wbc->nr_to_write > 0);
729
730 *_next = index;
731 _leave(" = 0 [%lx]", *_next);
732 return 0;
733}
734
735/*
736 * write some of the pending data back to the server
737 */
738int afs_writepages(struct address_space *mapping,
739 struct writeback_control *wbc)
740{
741 struct afs_vnode *vnode = AFS_FS_I(mapping->host);
742 pgoff_t start, end, next;
743 int ret;
744
745 _enter("");
746
747 /* We have to be careful as we can end up racing with setattr()
748 * truncating the pagecache since the caller doesn't take a lock here
749 * to prevent it.
750 */
751 if (wbc->sync_mode == WB_SYNC_ALL)
752 down_read(&vnode->validate_lock);
753 else if (!down_read_trylock(&vnode->validate_lock))
754 return 0;
755
756 if (wbc->range_cyclic) {
757 start = mapping->writeback_index;
758 end = -1;
759 ret = afs_writepages_region(mapping, wbc, start, end, &next);
760 if (start > 0 && wbc->nr_to_write > 0 && ret == 0)
761 ret = afs_writepages_region(mapping, wbc, 0, start,
762 &next);
763 mapping->writeback_index = next;
764 } else if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) {
765 end = (pgoff_t)(LLONG_MAX >> PAGE_SHIFT);
766 ret = afs_writepages_region(mapping, wbc, 0, end, &next);
767 if (wbc->nr_to_write > 0)
768 mapping->writeback_index = next;
769 } else {
770 start = wbc->range_start >> PAGE_SHIFT;
771 end = wbc->range_end >> PAGE_SHIFT;
772 ret = afs_writepages_region(mapping, wbc, start, end, &next);
773 }
774
775 up_read(&vnode->validate_lock);
776 _leave(" = %d", ret);
777 return ret;
778}
779
780/*
781 * write to an AFS file
782 */
783ssize_t afs_file_write(struct kiocb *iocb, struct iov_iter *from)
784{
785 struct afs_vnode *vnode = AFS_FS_I(file_inode(iocb->ki_filp));
786 ssize_t result;
787 size_t count = iov_iter_count(from);
788
789 _enter("{%llx:%llu},{%zu},",
790 vnode->fid.vid, vnode->fid.vnode, count);
791
792 if (IS_SWAPFILE(&vnode->vfs_inode)) {
793 printk(KERN_INFO
794 "AFS: Attempt to write to active swap file!\n");
795 return -EBUSY;
796 }
797
798 if (!count)
799 return 0;
800
801 result = generic_file_write_iter(iocb, from);
802
803 _leave(" = %zd", result);
804 return result;
805}
806
807/*
808 * flush any dirty pages for this process, and check for write errors.
809 * - the return status from this call provides a reliable indication of
810 * whether any write errors occurred for this process.
811 */
812int afs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
813{
814 struct inode *inode = file_inode(file);
815 struct afs_vnode *vnode = AFS_FS_I(inode);
816
817 _enter("{%llx:%llu},{n=%pD},%d",
818 vnode->fid.vid, vnode->fid.vnode, file,
819 datasync);
820
821 return file_write_and_wait_range(file, start, end);
822}
823
824/*
825 * notification that a previously read-only page is about to become writable
826 * - if it returns an error, the caller will deliver a bus error signal
827 */
828vm_fault_t afs_page_mkwrite(struct vm_fault *vmf)
829{
830 struct file *file = vmf->vma->vm_file;
831 struct inode *inode = file_inode(file);
832 struct afs_vnode *vnode = AFS_FS_I(inode);
833 unsigned long priv;
834
835 _enter("{{%llx:%llu}},{%lx}",
836 vnode->fid.vid, vnode->fid.vnode, vmf->page->index);
837
838 sb_start_pagefault(inode->i_sb);
839
840 /* Wait for the page to be written to the cache before we allow it to
841 * be modified. We then assume the entire page will need writing back.
842 */
843#ifdef CONFIG_AFS_FSCACHE
844 fscache_wait_on_page_write(vnode->cache, vmf->page);
845#endif
846
847 if (PageWriteback(vmf->page) &&
848 wait_on_page_bit_killable(vmf->page, PG_writeback) < 0)
849 return VM_FAULT_RETRY;
850
851 if (lock_page_killable(vmf->page) < 0)
852 return VM_FAULT_RETRY;
853
854 /* We mustn't change page->private until writeback is complete as that
855 * details the portion of the page we need to write back and we might
856 * need to redirty the page if there's a problem.
857 */
858 wait_on_page_writeback(vmf->page);
859
860 priv = (unsigned long)PAGE_SIZE << AFS_PRIV_SHIFT; /* To */
861 priv |= 0; /* From */
862 trace_afs_page_dirty(vnode, tracepoint_string("mkwrite"),
863 vmf->page->index, priv);
864 SetPagePrivate(vmf->page);
865 set_page_private(vmf->page, priv);
866 file_update_time(file);
867
868 sb_end_pagefault(inode->i_sb);
869 return VM_FAULT_LOCKED;
870}
871
872/*
873 * Prune the keys cached for writeback. The caller must hold vnode->wb_lock.
874 */
875void afs_prune_wb_keys(struct afs_vnode *vnode)
876{
877 LIST_HEAD(graveyard);
878 struct afs_wb_key *wbk, *tmp;
879
880 /* Discard unused keys */
881 spin_lock(&vnode->wb_lock);
882
883 if (!mapping_tagged(&vnode->vfs_inode.i_data, PAGECACHE_TAG_WRITEBACK) &&
884 !mapping_tagged(&vnode->vfs_inode.i_data, PAGECACHE_TAG_DIRTY)) {
885 list_for_each_entry_safe(wbk, tmp, &vnode->wb_keys, vnode_link) {
886 if (refcount_read(&wbk->usage) == 1)
887 list_move(&wbk->vnode_link, &graveyard);
888 }
889 }
890
891 spin_unlock(&vnode->wb_lock);
892
893 while (!list_empty(&graveyard)) {
894 wbk = list_entry(graveyard.next, struct afs_wb_key, vnode_link);
895 list_del(&wbk->vnode_link);
896 afs_put_wb_key(wbk);
897 }
898}
899
900/*
901 * Clean up a page during invalidation.
902 */
903int afs_launder_page(struct page *page)
904{
905 struct address_space *mapping = page->mapping;
906 struct afs_vnode *vnode = AFS_FS_I(mapping->host);
907 unsigned long priv;
908 unsigned int f, t;
909 int ret = 0;
910
911 _enter("{%lx}", page->index);
912
913 priv = page_private(page);
914 if (clear_page_dirty_for_io(page)) {
915 f = 0;
916 t = PAGE_SIZE;
917 if (PagePrivate(page)) {
918 f = priv & AFS_PRIV_MAX;
919 t = priv >> AFS_PRIV_SHIFT;
920 }
921
922 trace_afs_page_dirty(vnode, tracepoint_string("launder"),
923 page->index, priv);
924 ret = afs_store_data(mapping, page->index, page->index, t, f);
925 }
926
927 trace_afs_page_dirty(vnode, tracepoint_string("laundered"),
928 page->index, priv);
929 set_page_private(page, 0);
930 ClearPagePrivate(page);
931
932#ifdef CONFIG_AFS_FSCACHE
933 if (PageFsCache(page)) {
934 fscache_wait_on_page_write(vnode->cache, page);
935 fscache_uncache_page(vnode->cache, page);
936 }
937#endif
938 return ret;
939}