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