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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 <linux/netfs.h>
15#include <linux/fscache.h>
16#include "internal.h"
17
18/*
19 * mark a page as having been made dirty and thus needing writeback
20 */
21int afs_set_page_dirty(struct page *page)
22{
23 _enter("");
24 return __set_page_dirty_nobuffers(page);
25}
26
27/*
28 * prepare to perform part of a write to a page
29 */
30int afs_write_begin(struct file *file, struct address_space *mapping,
31 loff_t pos, unsigned len, unsigned flags,
32 struct page **_page, void **fsdata)
33{
34 struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
35 struct page *page;
36 unsigned long priv;
37 unsigned f, from;
38 unsigned t, to;
39 pgoff_t index;
40 int ret;
41
42 _enter("{%llx:%llu},%llx,%x",
43 vnode->fid.vid, vnode->fid.vnode, pos, len);
44
45 /* Prefetch area to be written into the cache if we're caching this
46 * file. We need to do this before we get a lock on the page in case
47 * there's more than one writer competing for the same cache block.
48 */
49 ret = netfs_write_begin(file, mapping, pos, len, flags, &page, fsdata,
50 &afs_req_ops, NULL);
51 if (ret < 0)
52 return ret;
53
54 index = page->index;
55 from = pos - index * PAGE_SIZE;
56 to = from + len;
57
58try_again:
59 /* See if this page is already partially written in a way that we can
60 * merge the new write with.
61 */
62 if (PagePrivate(page)) {
63 priv = page_private(page);
64 f = afs_page_dirty_from(page, priv);
65 t = afs_page_dirty_to(page, priv);
66 ASSERTCMP(f, <=, t);
67
68 if (PageWriteback(page)) {
69 trace_afs_page_dirty(vnode, tracepoint_string("alrdy"), page);
70 goto flush_conflicting_write;
71 }
72 /* If the file is being filled locally, allow inter-write
73 * spaces to be merged into writes. If it's not, only write
74 * back what the user gives us.
75 */
76 if (!test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags) &&
77 (to < f || from > t))
78 goto flush_conflicting_write;
79 }
80
81 *_page = page;
82 _leave(" = 0");
83 return 0;
84
85 /* The previous write and this write aren't adjacent or overlapping, so
86 * flush the page out.
87 */
88flush_conflicting_write:
89 _debug("flush conflict");
90 ret = write_one_page(page);
91 if (ret < 0)
92 goto error;
93
94 ret = lock_page_killable(page);
95 if (ret < 0)
96 goto error;
97 goto try_again;
98
99error:
100 put_page(page);
101 _leave(" = %d", ret);
102 return ret;
103}
104
105/*
106 * finalise part of a write to a page
107 */
108int afs_write_end(struct file *file, struct address_space *mapping,
109 loff_t pos, unsigned len, unsigned copied,
110 struct page *page, void *fsdata)
111{
112 struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
113 unsigned long priv;
114 unsigned int f, from = pos & (thp_size(page) - 1);
115 unsigned int t, to = from + copied;
116 loff_t i_size, maybe_i_size;
117
118 _enter("{%llx:%llu},{%lx}",
119 vnode->fid.vid, vnode->fid.vnode, page->index);
120
121 if (!PageUptodate(page)) {
122 if (copied < len) {
123 copied = 0;
124 goto out;
125 }
126
127 SetPageUptodate(page);
128 }
129
130 if (copied == 0)
131 goto out;
132
133 maybe_i_size = pos + copied;
134
135 i_size = i_size_read(&vnode->vfs_inode);
136 if (maybe_i_size > i_size) {
137 write_seqlock(&vnode->cb_lock);
138 i_size = i_size_read(&vnode->vfs_inode);
139 if (maybe_i_size > i_size)
140 afs_set_i_size(vnode, maybe_i_size);
141 write_sequnlock(&vnode->cb_lock);
142 }
143
144 if (PagePrivate(page)) {
145 priv = page_private(page);
146 f = afs_page_dirty_from(page, priv);
147 t = afs_page_dirty_to(page, priv);
148 if (from < f)
149 f = from;
150 if (to > t)
151 t = to;
152 priv = afs_page_dirty(page, f, t);
153 set_page_private(page, priv);
154 trace_afs_page_dirty(vnode, tracepoint_string("dirty+"), page);
155 } else {
156 priv = afs_page_dirty(page, from, to);
157 attach_page_private(page, (void *)priv);
158 trace_afs_page_dirty(vnode, tracepoint_string("dirty"), page);
159 }
160
161 if (set_page_dirty(page))
162 _debug("dirtied %lx", page->index);
163
164out:
165 unlock_page(page);
166 put_page(page);
167 return copied;
168}
169
170/*
171 * kill all the pages in the given range
172 */
173static void afs_kill_pages(struct address_space *mapping,
174 loff_t start, loff_t len)
175{
176 struct afs_vnode *vnode = AFS_FS_I(mapping->host);
177 struct pagevec pv;
178 unsigned int loop, psize;
179
180 _enter("{%llx:%llu},%llx @%llx",
181 vnode->fid.vid, vnode->fid.vnode, len, start);
182
183 pagevec_init(&pv);
184
185 do {
186 _debug("kill %llx @%llx", len, start);
187
188 pv.nr = find_get_pages_contig(mapping, start / PAGE_SIZE,
189 PAGEVEC_SIZE, pv.pages);
190 if (pv.nr == 0)
191 break;
192
193 for (loop = 0; loop < pv.nr; loop++) {
194 struct page *page = pv.pages[loop];
195
196 if (page->index * PAGE_SIZE >= start + len)
197 break;
198
199 psize = thp_size(page);
200 start += psize;
201 len -= psize;
202 ClearPageUptodate(page);
203 end_page_writeback(page);
204 lock_page(page);
205 generic_error_remove_page(mapping, page);
206 unlock_page(page);
207 }
208
209 __pagevec_release(&pv);
210 } while (len > 0);
211
212 _leave("");
213}
214
215/*
216 * Redirty all the pages in a given range.
217 */
218static void afs_redirty_pages(struct writeback_control *wbc,
219 struct address_space *mapping,
220 loff_t start, loff_t len)
221{
222 struct afs_vnode *vnode = AFS_FS_I(mapping->host);
223 struct pagevec pv;
224 unsigned int loop, psize;
225
226 _enter("{%llx:%llu},%llx @%llx",
227 vnode->fid.vid, vnode->fid.vnode, len, start);
228
229 pagevec_init(&pv);
230
231 do {
232 _debug("redirty %llx @%llx", len, start);
233
234 pv.nr = find_get_pages_contig(mapping, start / PAGE_SIZE,
235 PAGEVEC_SIZE, pv.pages);
236 if (pv.nr == 0)
237 break;
238
239 for (loop = 0; loop < pv.nr; loop++) {
240 struct page *page = pv.pages[loop];
241
242 if (page->index * PAGE_SIZE >= start + len)
243 break;
244
245 psize = thp_size(page);
246 start += psize;
247 len -= psize;
248 redirty_page_for_writepage(wbc, page);
249 end_page_writeback(page);
250 }
251
252 __pagevec_release(&pv);
253 } while (len > 0);
254
255 _leave("");
256}
257
258/*
259 * completion of write to server
260 */
261static void afs_pages_written_back(struct afs_vnode *vnode, loff_t start, unsigned int len)
262{
263 struct address_space *mapping = vnode->vfs_inode.i_mapping;
264 struct page *page;
265 pgoff_t end;
266
267 XA_STATE(xas, &mapping->i_pages, start / PAGE_SIZE);
268
269 _enter("{%llx:%llu},{%x @%llx}",
270 vnode->fid.vid, vnode->fid.vnode, len, start);
271
272 rcu_read_lock();
273
274 end = (start + len - 1) / PAGE_SIZE;
275 xas_for_each(&xas, page, end) {
276 if (!PageWriteback(page)) {
277 kdebug("bad %x @%llx page %lx %lx", len, start, page->index, end);
278 ASSERT(PageWriteback(page));
279 }
280
281 trace_afs_page_dirty(vnode, tracepoint_string("clear"), page);
282 detach_page_private(page);
283 page_endio(page, true, 0);
284 }
285
286 rcu_read_unlock();
287
288 afs_prune_wb_keys(vnode);
289 _leave("");
290}
291
292/*
293 * Find a key to use for the writeback. We cached the keys used to author the
294 * writes on the vnode. *_wbk will contain the last writeback key used or NULL
295 * and we need to start from there if it's set.
296 */
297static int afs_get_writeback_key(struct afs_vnode *vnode,
298 struct afs_wb_key **_wbk)
299{
300 struct afs_wb_key *wbk = NULL;
301 struct list_head *p;
302 int ret = -ENOKEY, ret2;
303
304 spin_lock(&vnode->wb_lock);
305 if (*_wbk)
306 p = (*_wbk)->vnode_link.next;
307 else
308 p = vnode->wb_keys.next;
309
310 while (p != &vnode->wb_keys) {
311 wbk = list_entry(p, struct afs_wb_key, vnode_link);
312 _debug("wbk %u", key_serial(wbk->key));
313 ret2 = key_validate(wbk->key);
314 if (ret2 == 0) {
315 refcount_inc(&wbk->usage);
316 _debug("USE WB KEY %u", key_serial(wbk->key));
317 break;
318 }
319
320 wbk = NULL;
321 if (ret == -ENOKEY)
322 ret = ret2;
323 p = p->next;
324 }
325
326 spin_unlock(&vnode->wb_lock);
327 if (*_wbk)
328 afs_put_wb_key(*_wbk);
329 *_wbk = wbk;
330 return 0;
331}
332
333static void afs_store_data_success(struct afs_operation *op)
334{
335 struct afs_vnode *vnode = op->file[0].vnode;
336
337 op->ctime = op->file[0].scb.status.mtime_client;
338 afs_vnode_commit_status(op, &op->file[0]);
339 if (op->error == 0) {
340 if (!op->store.laundering)
341 afs_pages_written_back(vnode, op->store.pos, op->store.size);
342 afs_stat_v(vnode, n_stores);
343 atomic_long_add(op->store.size, &afs_v2net(vnode)->n_store_bytes);
344 }
345}
346
347static const struct afs_operation_ops afs_store_data_operation = {
348 .issue_afs_rpc = afs_fs_store_data,
349 .issue_yfs_rpc = yfs_fs_store_data,
350 .success = afs_store_data_success,
351};
352
353/*
354 * write to a file
355 */
356static int afs_store_data(struct afs_vnode *vnode, struct iov_iter *iter, loff_t pos,
357 bool laundering)
358{
359 struct afs_operation *op;
360 struct afs_wb_key *wbk = NULL;
361 loff_t size = iov_iter_count(iter), i_size;
362 int ret = -ENOKEY;
363
364 _enter("%s{%llx:%llu.%u},%llx,%llx",
365 vnode->volume->name,
366 vnode->fid.vid,
367 vnode->fid.vnode,
368 vnode->fid.unique,
369 size, pos);
370
371 ret = afs_get_writeback_key(vnode, &wbk);
372 if (ret) {
373 _leave(" = %d [no keys]", ret);
374 return ret;
375 }
376
377 op = afs_alloc_operation(wbk->key, vnode->volume);
378 if (IS_ERR(op)) {
379 afs_put_wb_key(wbk);
380 return -ENOMEM;
381 }
382
383 i_size = i_size_read(&vnode->vfs_inode);
384
385 afs_op_set_vnode(op, 0, vnode);
386 op->file[0].dv_delta = 1;
387 op->file[0].modification = true;
388 op->store.write_iter = iter;
389 op->store.pos = pos;
390 op->store.size = size;
391 op->store.i_size = max(pos + size, i_size);
392 op->store.laundering = laundering;
393 op->mtime = vnode->vfs_inode.i_mtime;
394 op->flags |= AFS_OPERATION_UNINTR;
395 op->ops = &afs_store_data_operation;
396
397try_next_key:
398 afs_begin_vnode_operation(op);
399 afs_wait_for_operation(op);
400
401 switch (op->error) {
402 case -EACCES:
403 case -EPERM:
404 case -ENOKEY:
405 case -EKEYEXPIRED:
406 case -EKEYREJECTED:
407 case -EKEYREVOKED:
408 _debug("next");
409
410 ret = afs_get_writeback_key(vnode, &wbk);
411 if (ret == 0) {
412 key_put(op->key);
413 op->key = key_get(wbk->key);
414 goto try_next_key;
415 }
416 break;
417 }
418
419 afs_put_wb_key(wbk);
420 _leave(" = %d", op->error);
421 return afs_put_operation(op);
422}
423
424/*
425 * Extend the region to be written back to include subsequent contiguously
426 * dirty pages if possible, but don't sleep while doing so.
427 *
428 * If this page holds new content, then we can include filler zeros in the
429 * writeback.
430 */
431static void afs_extend_writeback(struct address_space *mapping,
432 struct afs_vnode *vnode,
433 long *_count,
434 loff_t start,
435 loff_t max_len,
436 bool new_content,
437 unsigned int *_len)
438{
439 struct pagevec pvec;
440 struct page *page;
441 unsigned long priv;
442 unsigned int psize, filler = 0;
443 unsigned int f, t;
444 loff_t len = *_len;
445 pgoff_t index = (start + len) / PAGE_SIZE;
446 bool stop = true;
447 unsigned int i;
448
449 XA_STATE(xas, &mapping->i_pages, index);
450 pagevec_init(&pvec);
451
452 do {
453 /* Firstly, we gather up a batch of contiguous dirty pages
454 * under the RCU read lock - but we can't clear the dirty flags
455 * there if any of those pages are mapped.
456 */
457 rcu_read_lock();
458
459 xas_for_each(&xas, page, ULONG_MAX) {
460 stop = true;
461 if (xas_retry(&xas, page))
462 continue;
463 if (xa_is_value(page))
464 break;
465 if (page->index != index)
466 break;
467
468 if (!page_cache_get_speculative(page)) {
469 xas_reset(&xas);
470 continue;
471 }
472
473 /* Has the page moved or been split? */
474 if (unlikely(page != xas_reload(&xas))) {
475 put_page(page);
476 break;
477 }
478
479 if (!trylock_page(page)) {
480 put_page(page);
481 break;
482 }
483 if (!PageDirty(page) || PageWriteback(page)) {
484 unlock_page(page);
485 put_page(page);
486 break;
487 }
488
489 psize = thp_size(page);
490 priv = page_private(page);
491 f = afs_page_dirty_from(page, priv);
492 t = afs_page_dirty_to(page, priv);
493 if (f != 0 && !new_content) {
494 unlock_page(page);
495 put_page(page);
496 break;
497 }
498
499 len += filler + t;
500 filler = psize - t;
501 if (len >= max_len || *_count <= 0)
502 stop = true;
503 else if (t == psize || new_content)
504 stop = false;
505
506 index += thp_nr_pages(page);
507 if (!pagevec_add(&pvec, page))
508 break;
509 if (stop)
510 break;
511 }
512
513 if (!stop)
514 xas_pause(&xas);
515 rcu_read_unlock();
516
517 /* Now, if we obtained any pages, we can shift them to being
518 * writable and mark them for caching.
519 */
520 if (!pagevec_count(&pvec))
521 break;
522
523 for (i = 0; i < pagevec_count(&pvec); i++) {
524 page = pvec.pages[i];
525 trace_afs_page_dirty(vnode, tracepoint_string("store+"), page);
526
527 if (!clear_page_dirty_for_io(page))
528 BUG();
529 if (test_set_page_writeback(page))
530 BUG();
531
532 *_count -= thp_nr_pages(page);
533 unlock_page(page);
534 }
535
536 pagevec_release(&pvec);
537 cond_resched();
538 } while (!stop);
539
540 *_len = len;
541}
542
543/*
544 * Synchronously write back the locked page and any subsequent non-locked dirty
545 * pages.
546 */
547static ssize_t afs_write_back_from_locked_page(struct address_space *mapping,
548 struct writeback_control *wbc,
549 struct page *page,
550 loff_t start, loff_t end)
551{
552 struct afs_vnode *vnode = AFS_FS_I(mapping->host);
553 struct iov_iter iter;
554 unsigned long priv;
555 unsigned int offset, to, len, max_len;
556 loff_t i_size = i_size_read(&vnode->vfs_inode);
557 bool new_content = test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags);
558 long count = wbc->nr_to_write;
559 int ret;
560
561 _enter(",%lx,%llx-%llx", page->index, start, end);
562
563 if (test_set_page_writeback(page))
564 BUG();
565
566 count -= thp_nr_pages(page);
567
568 /* Find all consecutive lockable dirty pages that have contiguous
569 * written regions, stopping when we find a page that is not
570 * immediately lockable, is not dirty or is missing, or we reach the
571 * end of the range.
572 */
573 priv = page_private(page);
574 offset = afs_page_dirty_from(page, priv);
575 to = afs_page_dirty_to(page, priv);
576 trace_afs_page_dirty(vnode, tracepoint_string("store"), page);
577
578 len = to - offset;
579 start += offset;
580 if (start < i_size) {
581 /* Trim the write to the EOF; the extra data is ignored. Also
582 * put an upper limit on the size of a single storedata op.
583 */
584 max_len = 65536 * 4096;
585 max_len = min_t(unsigned long long, max_len, end - start + 1);
586 max_len = min_t(unsigned long long, max_len, i_size - start);
587
588 if (len < max_len &&
589 (to == thp_size(page) || new_content))
590 afs_extend_writeback(mapping, vnode, &count,
591 start, max_len, new_content, &len);
592 len = min_t(loff_t, len, max_len);
593 }
594
595 /* We now have a contiguous set of dirty pages, each with writeback
596 * set; the first page is still locked at this point, but all the rest
597 * have been unlocked.
598 */
599 unlock_page(page);
600
601 if (start < i_size) {
602 _debug("write back %x @%llx [%llx]", len, start, i_size);
603
604 iov_iter_xarray(&iter, WRITE, &mapping->i_pages, start, len);
605 ret = afs_store_data(vnode, &iter, start, false);
606 } else {
607 _debug("write discard %x @%llx [%llx]", len, start, i_size);
608
609 /* The dirty region was entirely beyond the EOF. */
610 afs_pages_written_back(vnode, start, len);
611 ret = 0;
612 }
613
614 switch (ret) {
615 case 0:
616 wbc->nr_to_write = count;
617 ret = len;
618 break;
619
620 default:
621 pr_notice("kAFS: Unexpected error from FS.StoreData %d\n", ret);
622 fallthrough;
623 case -EACCES:
624 case -EPERM:
625 case -ENOKEY:
626 case -EKEYEXPIRED:
627 case -EKEYREJECTED:
628 case -EKEYREVOKED:
629 afs_redirty_pages(wbc, mapping, start, len);
630 mapping_set_error(mapping, ret);
631 break;
632
633 case -EDQUOT:
634 case -ENOSPC:
635 afs_redirty_pages(wbc, mapping, start, len);
636 mapping_set_error(mapping, -ENOSPC);
637 break;
638
639 case -EROFS:
640 case -EIO:
641 case -EREMOTEIO:
642 case -EFBIG:
643 case -ENOENT:
644 case -ENOMEDIUM:
645 case -ENXIO:
646 trace_afs_file_error(vnode, ret, afs_file_error_writeback_fail);
647 afs_kill_pages(mapping, start, len);
648 mapping_set_error(mapping, ret);
649 break;
650 }
651
652 _leave(" = %d", ret);
653 return ret;
654}
655
656/*
657 * write a page back to the server
658 * - the caller locked the page for us
659 */
660int afs_writepage(struct page *page, struct writeback_control *wbc)
661{
662 ssize_t ret;
663 loff_t start;
664
665 _enter("{%lx},", page->index);
666
667 start = page->index * PAGE_SIZE;
668 ret = afs_write_back_from_locked_page(page->mapping, wbc, page,
669 start, LLONG_MAX - start);
670 if (ret < 0) {
671 _leave(" = %zd", ret);
672 return ret;
673 }
674
675 _leave(" = 0");
676 return 0;
677}
678
679/*
680 * write a region of pages back to the server
681 */
682static int afs_writepages_region(struct address_space *mapping,
683 struct writeback_control *wbc,
684 loff_t start, loff_t end, loff_t *_next)
685{
686 struct page *page;
687 ssize_t ret;
688 int n;
689
690 _enter("%llx,%llx,", start, end);
691
692 do {
693 pgoff_t index = start / PAGE_SIZE;
694
695 n = find_get_pages_range_tag(mapping, &index, end / PAGE_SIZE,
696 PAGECACHE_TAG_DIRTY, 1, &page);
697 if (!n)
698 break;
699
700 start = (loff_t)page->index * PAGE_SIZE; /* May regress with THPs */
701
702 _debug("wback %lx", page->index);
703
704 /* At this point we hold neither the i_pages lock nor the
705 * page lock: the page may be truncated or invalidated
706 * (changing page->mapping to NULL), or even swizzled
707 * back from swapper_space to tmpfs file mapping
708 */
709 if (wbc->sync_mode != WB_SYNC_NONE) {
710 ret = lock_page_killable(page);
711 if (ret < 0) {
712 put_page(page);
713 return ret;
714 }
715 } else {
716 if (!trylock_page(page)) {
717 put_page(page);
718 return 0;
719 }
720 }
721
722 if (page->mapping != mapping || !PageDirty(page)) {
723 start += thp_size(page);
724 unlock_page(page);
725 put_page(page);
726 continue;
727 }
728
729 if (PageWriteback(page)) {
730 unlock_page(page);
731 if (wbc->sync_mode != WB_SYNC_NONE)
732 wait_on_page_writeback(page);
733 put_page(page);
734 continue;
735 }
736
737 if (!clear_page_dirty_for_io(page))
738 BUG();
739 ret = afs_write_back_from_locked_page(mapping, wbc, page, start, end);
740 put_page(page);
741 if (ret < 0) {
742 _leave(" = %zd", ret);
743 return ret;
744 }
745
746 start += ret;
747
748 cond_resched();
749 } while (wbc->nr_to_write > 0);
750
751 *_next = start;
752 _leave(" = 0 [%llx]", *_next);
753 return 0;
754}
755
756/*
757 * write some of the pending data back to the server
758 */
759int afs_writepages(struct address_space *mapping,
760 struct writeback_control *wbc)
761{
762 struct afs_vnode *vnode = AFS_FS_I(mapping->host);
763 loff_t start, next;
764 int ret;
765
766 _enter("");
767
768 /* We have to be careful as we can end up racing with setattr()
769 * truncating the pagecache since the caller doesn't take a lock here
770 * to prevent it.
771 */
772 if (wbc->sync_mode == WB_SYNC_ALL)
773 down_read(&vnode->validate_lock);
774 else if (!down_read_trylock(&vnode->validate_lock))
775 return 0;
776
777 if (wbc->range_cyclic) {
778 start = mapping->writeback_index * PAGE_SIZE;
779 ret = afs_writepages_region(mapping, wbc, start, LLONG_MAX, &next);
780 if (ret == 0) {
781 mapping->writeback_index = next / PAGE_SIZE;
782 if (start > 0 && wbc->nr_to_write > 0) {
783 ret = afs_writepages_region(mapping, wbc, 0,
784 start, &next);
785 if (ret == 0)
786 mapping->writeback_index =
787 next / PAGE_SIZE;
788 }
789 }
790 } else if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) {
791 ret = afs_writepages_region(mapping, wbc, 0, LLONG_MAX, &next);
792 if (wbc->nr_to_write > 0 && ret == 0)
793 mapping->writeback_index = next / PAGE_SIZE;
794 } else {
795 ret = afs_writepages_region(mapping, wbc,
796 wbc->range_start, wbc->range_end, &next);
797 }
798
799 up_read(&vnode->validate_lock);
800 _leave(" = %d", ret);
801 return ret;
802}
803
804/*
805 * write to an AFS file
806 */
807ssize_t afs_file_write(struct kiocb *iocb, struct iov_iter *from)
808{
809 struct afs_vnode *vnode = AFS_FS_I(file_inode(iocb->ki_filp));
810 struct afs_file *af = iocb->ki_filp->private_data;
811 ssize_t result;
812 size_t count = iov_iter_count(from);
813
814 _enter("{%llx:%llu},{%zu},",
815 vnode->fid.vid, vnode->fid.vnode, count);
816
817 if (IS_SWAPFILE(&vnode->vfs_inode)) {
818 printk(KERN_INFO
819 "AFS: Attempt to write to active swap file!\n");
820 return -EBUSY;
821 }
822
823 if (!count)
824 return 0;
825
826 result = afs_validate(vnode, af->key);
827 if (result < 0)
828 return result;
829
830 result = generic_file_write_iter(iocb, from);
831
832 _leave(" = %zd", result);
833 return result;
834}
835
836/*
837 * flush any dirty pages for this process, and check for write errors.
838 * - the return status from this call provides a reliable indication of
839 * whether any write errors occurred for this process.
840 */
841int afs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
842{
843 struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
844 struct afs_file *af = file->private_data;
845 int ret;
846
847 _enter("{%llx:%llu},{n=%pD},%d",
848 vnode->fid.vid, vnode->fid.vnode, file,
849 datasync);
850
851 ret = afs_validate(vnode, af->key);
852 if (ret < 0)
853 return ret;
854
855 return file_write_and_wait_range(file, start, end);
856}
857
858/*
859 * notification that a previously read-only page is about to become writable
860 * - if it returns an error, the caller will deliver a bus error signal
861 */
862vm_fault_t afs_page_mkwrite(struct vm_fault *vmf)
863{
864 struct page *page = thp_head(vmf->page);
865 struct file *file = vmf->vma->vm_file;
866 struct inode *inode = file_inode(file);
867 struct afs_vnode *vnode = AFS_FS_I(inode);
868 struct afs_file *af = file->private_data;
869 unsigned long priv;
870 vm_fault_t ret = VM_FAULT_RETRY;
871
872 _enter("{{%llx:%llu}},{%lx}", vnode->fid.vid, vnode->fid.vnode, page->index);
873
874 afs_validate(vnode, af->key);
875
876 sb_start_pagefault(inode->i_sb);
877
878 /* Wait for the page to be written to the cache before we allow it to
879 * be modified. We then assume the entire page will need writing back.
880 */
881#ifdef CONFIG_AFS_FSCACHE
882 if (PageFsCache(page) &&
883 wait_on_page_fscache_killable(page) < 0)
884 goto out;
885#endif
886
887 if (wait_on_page_writeback_killable(page))
888 goto out;
889
890 if (lock_page_killable(page) < 0)
891 goto out;
892
893 /* We mustn't change page->private until writeback is complete as that
894 * details the portion of the page we need to write back and we might
895 * need to redirty the page if there's a problem.
896 */
897 if (wait_on_page_writeback_killable(page) < 0) {
898 unlock_page(page);
899 goto out;
900 }
901
902 priv = afs_page_dirty(page, 0, thp_size(page));
903 priv = afs_page_dirty_mmapped(priv);
904 if (PagePrivate(page)) {
905 set_page_private(page, priv);
906 trace_afs_page_dirty(vnode, tracepoint_string("mkwrite+"), page);
907 } else {
908 attach_page_private(page, (void *)priv);
909 trace_afs_page_dirty(vnode, tracepoint_string("mkwrite"), page);
910 }
911 file_update_time(file);
912
913 ret = VM_FAULT_LOCKED;
914out:
915 sb_end_pagefault(inode->i_sb);
916 return ret;
917}
918
919/*
920 * Prune the keys cached for writeback. The caller must hold vnode->wb_lock.
921 */
922void afs_prune_wb_keys(struct afs_vnode *vnode)
923{
924 LIST_HEAD(graveyard);
925 struct afs_wb_key *wbk, *tmp;
926
927 /* Discard unused keys */
928 spin_lock(&vnode->wb_lock);
929
930 if (!mapping_tagged(&vnode->vfs_inode.i_data, PAGECACHE_TAG_WRITEBACK) &&
931 !mapping_tagged(&vnode->vfs_inode.i_data, PAGECACHE_TAG_DIRTY)) {
932 list_for_each_entry_safe(wbk, tmp, &vnode->wb_keys, vnode_link) {
933 if (refcount_read(&wbk->usage) == 1)
934 list_move(&wbk->vnode_link, &graveyard);
935 }
936 }
937
938 spin_unlock(&vnode->wb_lock);
939
940 while (!list_empty(&graveyard)) {
941 wbk = list_entry(graveyard.next, struct afs_wb_key, vnode_link);
942 list_del(&wbk->vnode_link);
943 afs_put_wb_key(wbk);
944 }
945}
946
947/*
948 * Clean up a page during invalidation.
949 */
950int afs_launder_page(struct page *page)
951{
952 struct address_space *mapping = page->mapping;
953 struct afs_vnode *vnode = AFS_FS_I(mapping->host);
954 struct iov_iter iter;
955 struct bio_vec bv[1];
956 unsigned long priv;
957 unsigned int f, t;
958 int ret = 0;
959
960 _enter("{%lx}", page->index);
961
962 priv = page_private(page);
963 if (clear_page_dirty_for_io(page)) {
964 f = 0;
965 t = thp_size(page);
966 if (PagePrivate(page)) {
967 f = afs_page_dirty_from(page, priv);
968 t = afs_page_dirty_to(page, priv);
969 }
970
971 bv[0].bv_page = page;
972 bv[0].bv_offset = f;
973 bv[0].bv_len = t - f;
974 iov_iter_bvec(&iter, WRITE, bv, 1, bv[0].bv_len);
975
976 trace_afs_page_dirty(vnode, tracepoint_string("launder"), page);
977 ret = afs_store_data(vnode, &iter, page_offset(page) + f, true);
978 }
979
980 trace_afs_page_dirty(vnode, tracepoint_string("laundered"), page);
981 detach_page_private(page);
982 wait_on_page_fscache(page);
983 return ret;
984}