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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 <linux/netfs.h>
15#include "internal.h"
16
17static int afs_writepages_region(struct address_space *mapping,
18 struct writeback_control *wbc,
19 loff_t start, loff_t end, loff_t *_next,
20 bool max_one_loop);
21
22static void afs_write_to_cache(struct afs_vnode *vnode, loff_t start, size_t len,
23 loff_t i_size, bool caching);
24
25#ifdef CONFIG_AFS_FSCACHE
26/*
27 * Mark a page as having been made dirty and thus needing writeback. We also
28 * need to pin the cache object to write back to.
29 */
30bool afs_dirty_folio(struct address_space *mapping, struct folio *folio)
31{
32 return fscache_dirty_folio(mapping, folio,
33 afs_vnode_cache(AFS_FS_I(mapping->host)));
34}
35static void afs_folio_start_fscache(bool caching, struct folio *folio)
36{
37 if (caching)
38 folio_start_fscache(folio);
39}
40#else
41static void afs_folio_start_fscache(bool caching, struct folio *folio)
42{
43}
44#endif
45
46/*
47 * Flush out a conflicting write. This may extend the write to the surrounding
48 * pages if also dirty and contiguous to the conflicting region..
49 */
50static int afs_flush_conflicting_write(struct address_space *mapping,
51 struct folio *folio)
52{
53 struct writeback_control wbc = {
54 .sync_mode = WB_SYNC_ALL,
55 .nr_to_write = LONG_MAX,
56 .range_start = folio_pos(folio),
57 .range_end = LLONG_MAX,
58 };
59 loff_t next;
60
61 return afs_writepages_region(mapping, &wbc, folio_pos(folio), LLONG_MAX,
62 &next, true);
63}
64
65/*
66 * prepare to perform part of a write to a page
67 */
68int afs_write_begin(struct file *file, struct address_space *mapping,
69 loff_t pos, unsigned len,
70 struct page **_page, void **fsdata)
71{
72 struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
73 struct folio *folio;
74 unsigned long priv;
75 unsigned f, from;
76 unsigned t, to;
77 pgoff_t index;
78 int ret;
79
80 _enter("{%llx:%llu},%llx,%x",
81 vnode->fid.vid, vnode->fid.vnode, pos, len);
82
83 /* Prefetch area to be written into the cache if we're caching this
84 * file. We need to do this before we get a lock on the page in case
85 * there's more than one writer competing for the same cache block.
86 */
87 ret = netfs_write_begin(&vnode->netfs, file, mapping, pos, len, &folio, fsdata);
88 if (ret < 0)
89 return ret;
90
91 index = folio_index(folio);
92 from = pos - index * PAGE_SIZE;
93 to = from + len;
94
95try_again:
96 /* See if this page is already partially written in a way that we can
97 * merge the new write with.
98 */
99 if (folio_test_private(folio)) {
100 priv = (unsigned long)folio_get_private(folio);
101 f = afs_folio_dirty_from(folio, priv);
102 t = afs_folio_dirty_to(folio, priv);
103 ASSERTCMP(f, <=, t);
104
105 if (folio_test_writeback(folio)) {
106 trace_afs_folio_dirty(vnode, tracepoint_string("alrdy"), folio);
107 folio_unlock(folio);
108 goto wait_for_writeback;
109 }
110 /* If the file is being filled locally, allow inter-write
111 * spaces to be merged into writes. If it's not, only write
112 * back what the user gives us.
113 */
114 if (!test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags) &&
115 (to < f || from > t))
116 goto flush_conflicting_write;
117 }
118
119 *_page = folio_file_page(folio, pos / PAGE_SIZE);
120 _leave(" = 0");
121 return 0;
122
123 /* The previous write and this write aren't adjacent or overlapping, so
124 * flush the page out.
125 */
126flush_conflicting_write:
127 trace_afs_folio_dirty(vnode, tracepoint_string("confl"), folio);
128 folio_unlock(folio);
129
130 ret = afs_flush_conflicting_write(mapping, folio);
131 if (ret < 0)
132 goto error;
133
134wait_for_writeback:
135 ret = folio_wait_writeback_killable(folio);
136 if (ret < 0)
137 goto error;
138
139 ret = folio_lock_killable(folio);
140 if (ret < 0)
141 goto error;
142 goto try_again;
143
144error:
145 folio_put(folio);
146 _leave(" = %d", ret);
147 return ret;
148}
149
150/*
151 * finalise part of a write to a page
152 */
153int afs_write_end(struct file *file, struct address_space *mapping,
154 loff_t pos, unsigned len, unsigned copied,
155 struct page *subpage, void *fsdata)
156{
157 struct folio *folio = page_folio(subpage);
158 struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
159 unsigned long priv;
160 unsigned int f, from = offset_in_folio(folio, pos);
161 unsigned int t, to = from + copied;
162 loff_t i_size, write_end_pos;
163
164 _enter("{%llx:%llu},{%lx}",
165 vnode->fid.vid, vnode->fid.vnode, folio_index(folio));
166
167 if (!folio_test_uptodate(folio)) {
168 if (copied < len) {
169 copied = 0;
170 goto out;
171 }
172
173 folio_mark_uptodate(folio);
174 }
175
176 if (copied == 0)
177 goto out;
178
179 write_end_pos = pos + copied;
180
181 i_size = i_size_read(&vnode->netfs.inode);
182 if (write_end_pos > i_size) {
183 write_seqlock(&vnode->cb_lock);
184 i_size = i_size_read(&vnode->netfs.inode);
185 if (write_end_pos > i_size)
186 afs_set_i_size(vnode, write_end_pos);
187 write_sequnlock(&vnode->cb_lock);
188 fscache_update_cookie(afs_vnode_cache(vnode), NULL, &write_end_pos);
189 }
190
191 if (folio_test_private(folio)) {
192 priv = (unsigned long)folio_get_private(folio);
193 f = afs_folio_dirty_from(folio, priv);
194 t = afs_folio_dirty_to(folio, priv);
195 if (from < f)
196 f = from;
197 if (to > t)
198 t = to;
199 priv = afs_folio_dirty(folio, f, t);
200 folio_change_private(folio, (void *)priv);
201 trace_afs_folio_dirty(vnode, tracepoint_string("dirty+"), folio);
202 } else {
203 priv = afs_folio_dirty(folio, from, to);
204 folio_attach_private(folio, (void *)priv);
205 trace_afs_folio_dirty(vnode, tracepoint_string("dirty"), folio);
206 }
207
208 if (folio_mark_dirty(folio))
209 _debug("dirtied %lx", folio_index(folio));
210
211out:
212 folio_unlock(folio);
213 folio_put(folio);
214 return copied;
215}
216
217/*
218 * kill all the pages in the given range
219 */
220static void afs_kill_pages(struct address_space *mapping,
221 loff_t start, loff_t len)
222{
223 struct afs_vnode *vnode = AFS_FS_I(mapping->host);
224 struct folio *folio;
225 pgoff_t index = start / PAGE_SIZE;
226 pgoff_t last = (start + len - 1) / PAGE_SIZE, next;
227
228 _enter("{%llx:%llu},%llx @%llx",
229 vnode->fid.vid, vnode->fid.vnode, len, start);
230
231 do {
232 _debug("kill %lx (to %lx)", index, last);
233
234 folio = filemap_get_folio(mapping, index);
235 if (!folio) {
236 next = index + 1;
237 continue;
238 }
239
240 next = folio_next_index(folio);
241
242 folio_clear_uptodate(folio);
243 folio_end_writeback(folio);
244 folio_lock(folio);
245 generic_error_remove_page(mapping, &folio->page);
246 folio_unlock(folio);
247 folio_put(folio);
248
249 } while (index = next, index <= last);
250
251 _leave("");
252}
253
254/*
255 * Redirty all the pages in a given range.
256 */
257static void afs_redirty_pages(struct writeback_control *wbc,
258 struct address_space *mapping,
259 loff_t start, loff_t len)
260{
261 struct afs_vnode *vnode = AFS_FS_I(mapping->host);
262 struct folio *folio;
263 pgoff_t index = start / PAGE_SIZE;
264 pgoff_t last = (start + len - 1) / PAGE_SIZE, next;
265
266 _enter("{%llx:%llu},%llx @%llx",
267 vnode->fid.vid, vnode->fid.vnode, len, start);
268
269 do {
270 _debug("redirty %llx @%llx", len, start);
271
272 folio = filemap_get_folio(mapping, index);
273 if (!folio) {
274 next = index + 1;
275 continue;
276 }
277
278 next = index + folio_nr_pages(folio);
279 folio_redirty_for_writepage(wbc, folio);
280 folio_end_writeback(folio);
281 folio_put(folio);
282 } while (index = next, index <= last);
283
284 _leave("");
285}
286
287/*
288 * completion of write to server
289 */
290static void afs_pages_written_back(struct afs_vnode *vnode, loff_t start, unsigned int len)
291{
292 struct address_space *mapping = vnode->netfs.inode.i_mapping;
293 struct folio *folio;
294 pgoff_t end;
295
296 XA_STATE(xas, &mapping->i_pages, start / PAGE_SIZE);
297
298 _enter("{%llx:%llu},{%x @%llx}",
299 vnode->fid.vid, vnode->fid.vnode, len, start);
300
301 rcu_read_lock();
302
303 end = (start + len - 1) / PAGE_SIZE;
304 xas_for_each(&xas, folio, end) {
305 if (!folio_test_writeback(folio)) {
306 kdebug("bad %x @%llx page %lx %lx",
307 len, start, folio_index(folio), end);
308 ASSERT(folio_test_writeback(folio));
309 }
310
311 trace_afs_folio_dirty(vnode, tracepoint_string("clear"), folio);
312 folio_detach_private(folio);
313 folio_end_writeback(folio);
314 }
315
316 rcu_read_unlock();
317
318 afs_prune_wb_keys(vnode);
319 _leave("");
320}
321
322/*
323 * Find a key to use for the writeback. We cached the keys used to author the
324 * writes on the vnode. *_wbk will contain the last writeback key used or NULL
325 * and we need to start from there if it's set.
326 */
327static int afs_get_writeback_key(struct afs_vnode *vnode,
328 struct afs_wb_key **_wbk)
329{
330 struct afs_wb_key *wbk = NULL;
331 struct list_head *p;
332 int ret = -ENOKEY, ret2;
333
334 spin_lock(&vnode->wb_lock);
335 if (*_wbk)
336 p = (*_wbk)->vnode_link.next;
337 else
338 p = vnode->wb_keys.next;
339
340 while (p != &vnode->wb_keys) {
341 wbk = list_entry(p, struct afs_wb_key, vnode_link);
342 _debug("wbk %u", key_serial(wbk->key));
343 ret2 = key_validate(wbk->key);
344 if (ret2 == 0) {
345 refcount_inc(&wbk->usage);
346 _debug("USE WB KEY %u", key_serial(wbk->key));
347 break;
348 }
349
350 wbk = NULL;
351 if (ret == -ENOKEY)
352 ret = ret2;
353 p = p->next;
354 }
355
356 spin_unlock(&vnode->wb_lock);
357 if (*_wbk)
358 afs_put_wb_key(*_wbk);
359 *_wbk = wbk;
360 return 0;
361}
362
363static void afs_store_data_success(struct afs_operation *op)
364{
365 struct afs_vnode *vnode = op->file[0].vnode;
366
367 op->ctime = op->file[0].scb.status.mtime_client;
368 afs_vnode_commit_status(op, &op->file[0]);
369 if (op->error == 0) {
370 if (!op->store.laundering)
371 afs_pages_written_back(vnode, op->store.pos, op->store.size);
372 afs_stat_v(vnode, n_stores);
373 atomic_long_add(op->store.size, &afs_v2net(vnode)->n_store_bytes);
374 }
375}
376
377static const struct afs_operation_ops afs_store_data_operation = {
378 .issue_afs_rpc = afs_fs_store_data,
379 .issue_yfs_rpc = yfs_fs_store_data,
380 .success = afs_store_data_success,
381};
382
383/*
384 * write to a file
385 */
386static int afs_store_data(struct afs_vnode *vnode, struct iov_iter *iter, loff_t pos,
387 bool laundering)
388{
389 struct afs_operation *op;
390 struct afs_wb_key *wbk = NULL;
391 loff_t size = iov_iter_count(iter);
392 int ret = -ENOKEY;
393
394 _enter("%s{%llx:%llu.%u},%llx,%llx",
395 vnode->volume->name,
396 vnode->fid.vid,
397 vnode->fid.vnode,
398 vnode->fid.unique,
399 size, pos);
400
401 ret = afs_get_writeback_key(vnode, &wbk);
402 if (ret) {
403 _leave(" = %d [no keys]", ret);
404 return ret;
405 }
406
407 op = afs_alloc_operation(wbk->key, vnode->volume);
408 if (IS_ERR(op)) {
409 afs_put_wb_key(wbk);
410 return -ENOMEM;
411 }
412
413 afs_op_set_vnode(op, 0, vnode);
414 op->file[0].dv_delta = 1;
415 op->file[0].modification = true;
416 op->store.write_iter = iter;
417 op->store.pos = pos;
418 op->store.size = size;
419 op->store.i_size = max(pos + size, vnode->netfs.remote_i_size);
420 op->store.laundering = laundering;
421 op->mtime = vnode->netfs.inode.i_mtime;
422 op->flags |= AFS_OPERATION_UNINTR;
423 op->ops = &afs_store_data_operation;
424
425try_next_key:
426 afs_begin_vnode_operation(op);
427 afs_wait_for_operation(op);
428
429 switch (op->error) {
430 case -EACCES:
431 case -EPERM:
432 case -ENOKEY:
433 case -EKEYEXPIRED:
434 case -EKEYREJECTED:
435 case -EKEYREVOKED:
436 _debug("next");
437
438 ret = afs_get_writeback_key(vnode, &wbk);
439 if (ret == 0) {
440 key_put(op->key);
441 op->key = key_get(wbk->key);
442 goto try_next_key;
443 }
444 break;
445 }
446
447 afs_put_wb_key(wbk);
448 _leave(" = %d", op->error);
449 return afs_put_operation(op);
450}
451
452/*
453 * Extend the region to be written back to include subsequent contiguously
454 * dirty pages if possible, but don't sleep while doing so.
455 *
456 * If this page holds new content, then we can include filler zeros in the
457 * writeback.
458 */
459static void afs_extend_writeback(struct address_space *mapping,
460 struct afs_vnode *vnode,
461 long *_count,
462 loff_t start,
463 loff_t max_len,
464 bool new_content,
465 bool caching,
466 unsigned int *_len)
467{
468 struct pagevec pvec;
469 struct folio *folio;
470 unsigned long priv;
471 unsigned int psize, filler = 0;
472 unsigned int f, t;
473 loff_t len = *_len;
474 pgoff_t index = (start + len) / PAGE_SIZE;
475 bool stop = true;
476 unsigned int i;
477
478 XA_STATE(xas, &mapping->i_pages, index);
479 pagevec_init(&pvec);
480
481 do {
482 /* Firstly, we gather up a batch of contiguous dirty pages
483 * under the RCU read lock - but we can't clear the dirty flags
484 * there if any of those pages are mapped.
485 */
486 rcu_read_lock();
487
488 xas_for_each(&xas, folio, ULONG_MAX) {
489 stop = true;
490 if (xas_retry(&xas, folio))
491 continue;
492 if (xa_is_value(folio))
493 break;
494 if (folio_index(folio) != index)
495 break;
496
497 if (!folio_try_get_rcu(folio)) {
498 xas_reset(&xas);
499 continue;
500 }
501
502 /* Has the page moved or been split? */
503 if (unlikely(folio != xas_reload(&xas))) {
504 folio_put(folio);
505 break;
506 }
507
508 if (!folio_trylock(folio)) {
509 folio_put(folio);
510 break;
511 }
512 if (!folio_test_dirty(folio) ||
513 folio_test_writeback(folio) ||
514 folio_test_fscache(folio)) {
515 folio_unlock(folio);
516 folio_put(folio);
517 break;
518 }
519
520 psize = folio_size(folio);
521 priv = (unsigned long)folio_get_private(folio);
522 f = afs_folio_dirty_from(folio, priv);
523 t = afs_folio_dirty_to(folio, priv);
524 if (f != 0 && !new_content) {
525 folio_unlock(folio);
526 folio_put(folio);
527 break;
528 }
529
530 len += filler + t;
531 filler = psize - t;
532 if (len >= max_len || *_count <= 0)
533 stop = true;
534 else if (t == psize || new_content)
535 stop = false;
536
537 index += folio_nr_pages(folio);
538 if (!pagevec_add(&pvec, &folio->page))
539 break;
540 if (stop)
541 break;
542 }
543
544 if (!stop)
545 xas_pause(&xas);
546 rcu_read_unlock();
547
548 /* Now, if we obtained any pages, we can shift them to being
549 * writable and mark them for caching.
550 */
551 if (!pagevec_count(&pvec))
552 break;
553
554 for (i = 0; i < pagevec_count(&pvec); i++) {
555 folio = page_folio(pvec.pages[i]);
556 trace_afs_folio_dirty(vnode, tracepoint_string("store+"), folio);
557
558 if (!folio_clear_dirty_for_io(folio))
559 BUG();
560 if (folio_start_writeback(folio))
561 BUG();
562 afs_folio_start_fscache(caching, folio);
563
564 *_count -= folio_nr_pages(folio);
565 folio_unlock(folio);
566 }
567
568 pagevec_release(&pvec);
569 cond_resched();
570 } while (!stop);
571
572 *_len = len;
573}
574
575/*
576 * Synchronously write back the locked page and any subsequent non-locked dirty
577 * pages.
578 */
579static ssize_t afs_write_back_from_locked_folio(struct address_space *mapping,
580 struct writeback_control *wbc,
581 struct folio *folio,
582 loff_t start, loff_t end)
583{
584 struct afs_vnode *vnode = AFS_FS_I(mapping->host);
585 struct iov_iter iter;
586 unsigned long priv;
587 unsigned int offset, to, len, max_len;
588 loff_t i_size = i_size_read(&vnode->netfs.inode);
589 bool new_content = test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags);
590 bool caching = fscache_cookie_enabled(afs_vnode_cache(vnode));
591 long count = wbc->nr_to_write;
592 int ret;
593
594 _enter(",%lx,%llx-%llx", folio_index(folio), start, end);
595
596 if (folio_start_writeback(folio))
597 BUG();
598 afs_folio_start_fscache(caching, folio);
599
600 count -= folio_nr_pages(folio);
601
602 /* Find all consecutive lockable dirty pages that have contiguous
603 * written regions, stopping when we find a page that is not
604 * immediately lockable, is not dirty or is missing, or we reach the
605 * end of the range.
606 */
607 priv = (unsigned long)folio_get_private(folio);
608 offset = afs_folio_dirty_from(folio, priv);
609 to = afs_folio_dirty_to(folio, priv);
610 trace_afs_folio_dirty(vnode, tracepoint_string("store"), folio);
611
612 len = to - offset;
613 start += offset;
614 if (start < i_size) {
615 /* Trim the write to the EOF; the extra data is ignored. Also
616 * put an upper limit on the size of a single storedata op.
617 */
618 max_len = 65536 * 4096;
619 max_len = min_t(unsigned long long, max_len, end - start + 1);
620 max_len = min_t(unsigned long long, max_len, i_size - start);
621
622 if (len < max_len &&
623 (to == folio_size(folio) || new_content))
624 afs_extend_writeback(mapping, vnode, &count,
625 start, max_len, new_content,
626 caching, &len);
627 len = min_t(loff_t, len, max_len);
628 }
629
630 /* We now have a contiguous set of dirty pages, each with writeback
631 * set; the first page is still locked at this point, but all the rest
632 * have been unlocked.
633 */
634 folio_unlock(folio);
635
636 if (start < i_size) {
637 _debug("write back %x @%llx [%llx]", len, start, i_size);
638
639 /* Speculatively write to the cache. We have to fix this up
640 * later if the store fails.
641 */
642 afs_write_to_cache(vnode, start, len, i_size, caching);
643
644 iov_iter_xarray(&iter, ITER_SOURCE, &mapping->i_pages, start, len);
645 ret = afs_store_data(vnode, &iter, start, false);
646 } else {
647 _debug("write discard %x @%llx [%llx]", len, start, i_size);
648
649 /* The dirty region was entirely beyond the EOF. */
650 fscache_clear_page_bits(mapping, start, len, caching);
651 afs_pages_written_back(vnode, start, len);
652 ret = 0;
653 }
654
655 switch (ret) {
656 case 0:
657 wbc->nr_to_write = count;
658 ret = len;
659 break;
660
661 default:
662 pr_notice("kAFS: Unexpected error from FS.StoreData %d\n", ret);
663 fallthrough;
664 case -EACCES:
665 case -EPERM:
666 case -ENOKEY:
667 case -EKEYEXPIRED:
668 case -EKEYREJECTED:
669 case -EKEYREVOKED:
670 case -ENETRESET:
671 afs_redirty_pages(wbc, mapping, start, len);
672 mapping_set_error(mapping, ret);
673 break;
674
675 case -EDQUOT:
676 case -ENOSPC:
677 afs_redirty_pages(wbc, mapping, start, len);
678 mapping_set_error(mapping, -ENOSPC);
679 break;
680
681 case -EROFS:
682 case -EIO:
683 case -EREMOTEIO:
684 case -EFBIG:
685 case -ENOENT:
686 case -ENOMEDIUM:
687 case -ENXIO:
688 trace_afs_file_error(vnode, ret, afs_file_error_writeback_fail);
689 afs_kill_pages(mapping, start, len);
690 mapping_set_error(mapping, ret);
691 break;
692 }
693
694 _leave(" = %d", ret);
695 return ret;
696}
697
698/*
699 * write a region of pages back to the server
700 */
701static int afs_writepages_region(struct address_space *mapping,
702 struct writeback_control *wbc,
703 loff_t start, loff_t end, loff_t *_next,
704 bool max_one_loop)
705{
706 struct folio *folio;
707 struct page *head_page;
708 ssize_t ret;
709 int n, skips = 0;
710
711 _enter("%llx,%llx,", start, end);
712
713 do {
714 pgoff_t index = start / PAGE_SIZE;
715
716 n = find_get_pages_range_tag(mapping, &index, end / PAGE_SIZE,
717 PAGECACHE_TAG_DIRTY, 1, &head_page);
718 if (!n)
719 break;
720
721 folio = page_folio(head_page);
722 start = folio_pos(folio); /* May regress with THPs */
723
724 _debug("wback %lx", folio_index(folio));
725
726 /* At this point we hold neither the i_pages lock nor the
727 * page lock: the page may be truncated or invalidated
728 * (changing page->mapping to NULL), or even swizzled
729 * back from swapper_space to tmpfs file mapping
730 */
731 if (wbc->sync_mode != WB_SYNC_NONE) {
732 ret = folio_lock_killable(folio);
733 if (ret < 0) {
734 folio_put(folio);
735 return ret;
736 }
737 } else {
738 if (!folio_trylock(folio)) {
739 folio_put(folio);
740 return 0;
741 }
742 }
743
744 if (folio_mapping(folio) != mapping ||
745 !folio_test_dirty(folio)) {
746 start += folio_size(folio);
747 folio_unlock(folio);
748 folio_put(folio);
749 continue;
750 }
751
752 if (folio_test_writeback(folio) ||
753 folio_test_fscache(folio)) {
754 folio_unlock(folio);
755 if (wbc->sync_mode != WB_SYNC_NONE) {
756 folio_wait_writeback(folio);
757#ifdef CONFIG_AFS_FSCACHE
758 folio_wait_fscache(folio);
759#endif
760 } else {
761 start += folio_size(folio);
762 }
763 folio_put(folio);
764 if (wbc->sync_mode == WB_SYNC_NONE) {
765 if (skips >= 5 || need_resched())
766 break;
767 skips++;
768 }
769 continue;
770 }
771
772 if (!folio_clear_dirty_for_io(folio))
773 BUG();
774 ret = afs_write_back_from_locked_folio(mapping, wbc, folio, start, end);
775 folio_put(folio);
776 if (ret < 0) {
777 _leave(" = %zd", ret);
778 return ret;
779 }
780
781 start += ret;
782
783 if (max_one_loop)
784 break;
785
786 cond_resched();
787 } while (wbc->nr_to_write > 0);
788
789 *_next = start;
790 _leave(" = 0 [%llx]", *_next);
791 return 0;
792}
793
794/*
795 * write some of the pending data back to the server
796 */
797int afs_writepages(struct address_space *mapping,
798 struct writeback_control *wbc)
799{
800 struct afs_vnode *vnode = AFS_FS_I(mapping->host);
801 loff_t start, next;
802 int ret;
803
804 _enter("");
805
806 /* We have to be careful as we can end up racing with setattr()
807 * truncating the pagecache since the caller doesn't take a lock here
808 * to prevent it.
809 */
810 if (wbc->sync_mode == WB_SYNC_ALL)
811 down_read(&vnode->validate_lock);
812 else if (!down_read_trylock(&vnode->validate_lock))
813 return 0;
814
815 if (wbc->range_cyclic) {
816 start = mapping->writeback_index * PAGE_SIZE;
817 ret = afs_writepages_region(mapping, wbc, start, LLONG_MAX,
818 &next, false);
819 if (ret == 0) {
820 mapping->writeback_index = next / PAGE_SIZE;
821 if (start > 0 && wbc->nr_to_write > 0) {
822 ret = afs_writepages_region(mapping, wbc, 0,
823 start, &next, false);
824 if (ret == 0)
825 mapping->writeback_index =
826 next / PAGE_SIZE;
827 }
828 }
829 } else if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) {
830 ret = afs_writepages_region(mapping, wbc, 0, LLONG_MAX,
831 &next, false);
832 if (wbc->nr_to_write > 0 && ret == 0)
833 mapping->writeback_index = next / PAGE_SIZE;
834 } else {
835 ret = afs_writepages_region(mapping, wbc,
836 wbc->range_start, wbc->range_end,
837 &next, false);
838 }
839
840 up_read(&vnode->validate_lock);
841 _leave(" = %d", ret);
842 return ret;
843}
844
845/*
846 * write to an AFS file
847 */
848ssize_t afs_file_write(struct kiocb *iocb, struct iov_iter *from)
849{
850 struct afs_vnode *vnode = AFS_FS_I(file_inode(iocb->ki_filp));
851 struct afs_file *af = iocb->ki_filp->private_data;
852 ssize_t result;
853 size_t count = iov_iter_count(from);
854
855 _enter("{%llx:%llu},{%zu},",
856 vnode->fid.vid, vnode->fid.vnode, count);
857
858 if (IS_SWAPFILE(&vnode->netfs.inode)) {
859 printk(KERN_INFO
860 "AFS: Attempt to write to active swap file!\n");
861 return -EBUSY;
862 }
863
864 if (!count)
865 return 0;
866
867 result = afs_validate(vnode, af->key);
868 if (result < 0)
869 return result;
870
871 result = generic_file_write_iter(iocb, from);
872
873 _leave(" = %zd", result);
874 return result;
875}
876
877/*
878 * flush any dirty pages for this process, and check for write errors.
879 * - the return status from this call provides a reliable indication of
880 * whether any write errors occurred for this process.
881 */
882int afs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
883{
884 struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
885 struct afs_file *af = file->private_data;
886 int ret;
887
888 _enter("{%llx:%llu},{n=%pD},%d",
889 vnode->fid.vid, vnode->fid.vnode, file,
890 datasync);
891
892 ret = afs_validate(vnode, af->key);
893 if (ret < 0)
894 return ret;
895
896 return file_write_and_wait_range(file, start, end);
897}
898
899/*
900 * notification that a previously read-only page is about to become writable
901 * - if it returns an error, the caller will deliver a bus error signal
902 */
903vm_fault_t afs_page_mkwrite(struct vm_fault *vmf)
904{
905 struct folio *folio = page_folio(vmf->page);
906 struct file *file = vmf->vma->vm_file;
907 struct inode *inode = file_inode(file);
908 struct afs_vnode *vnode = AFS_FS_I(inode);
909 struct afs_file *af = file->private_data;
910 unsigned long priv;
911 vm_fault_t ret = VM_FAULT_RETRY;
912
913 _enter("{{%llx:%llu}},{%lx}", vnode->fid.vid, vnode->fid.vnode, folio_index(folio));
914
915 afs_validate(vnode, af->key);
916
917 sb_start_pagefault(inode->i_sb);
918
919 /* Wait for the page to be written to the cache before we allow it to
920 * be modified. We then assume the entire page will need writing back.
921 */
922#ifdef CONFIG_AFS_FSCACHE
923 if (folio_test_fscache(folio) &&
924 folio_wait_fscache_killable(folio) < 0)
925 goto out;
926#endif
927
928 if (folio_wait_writeback_killable(folio))
929 goto out;
930
931 if (folio_lock_killable(folio) < 0)
932 goto out;
933
934 /* We mustn't change folio->private until writeback is complete as that
935 * details the portion of the page we need to write back and we might
936 * need to redirty the page if there's a problem.
937 */
938 if (folio_wait_writeback_killable(folio) < 0) {
939 folio_unlock(folio);
940 goto out;
941 }
942
943 priv = afs_folio_dirty(folio, 0, folio_size(folio));
944 priv = afs_folio_dirty_mmapped(priv);
945 if (folio_test_private(folio)) {
946 folio_change_private(folio, (void *)priv);
947 trace_afs_folio_dirty(vnode, tracepoint_string("mkwrite+"), folio);
948 } else {
949 folio_attach_private(folio, (void *)priv);
950 trace_afs_folio_dirty(vnode, tracepoint_string("mkwrite"), folio);
951 }
952 file_update_time(file);
953
954 ret = VM_FAULT_LOCKED;
955out:
956 sb_end_pagefault(inode->i_sb);
957 return ret;
958}
959
960/*
961 * Prune the keys cached for writeback. The caller must hold vnode->wb_lock.
962 */
963void afs_prune_wb_keys(struct afs_vnode *vnode)
964{
965 LIST_HEAD(graveyard);
966 struct afs_wb_key *wbk, *tmp;
967
968 /* Discard unused keys */
969 spin_lock(&vnode->wb_lock);
970
971 if (!mapping_tagged(&vnode->netfs.inode.i_data, PAGECACHE_TAG_WRITEBACK) &&
972 !mapping_tagged(&vnode->netfs.inode.i_data, PAGECACHE_TAG_DIRTY)) {
973 list_for_each_entry_safe(wbk, tmp, &vnode->wb_keys, vnode_link) {
974 if (refcount_read(&wbk->usage) == 1)
975 list_move(&wbk->vnode_link, &graveyard);
976 }
977 }
978
979 spin_unlock(&vnode->wb_lock);
980
981 while (!list_empty(&graveyard)) {
982 wbk = list_entry(graveyard.next, struct afs_wb_key, vnode_link);
983 list_del(&wbk->vnode_link);
984 afs_put_wb_key(wbk);
985 }
986}
987
988/*
989 * Clean up a page during invalidation.
990 */
991int afs_launder_folio(struct folio *folio)
992{
993 struct afs_vnode *vnode = AFS_FS_I(folio_inode(folio));
994 struct iov_iter iter;
995 struct bio_vec bv[1];
996 unsigned long priv;
997 unsigned int f, t;
998 int ret = 0;
999
1000 _enter("{%lx}", folio->index);
1001
1002 priv = (unsigned long)folio_get_private(folio);
1003 if (folio_clear_dirty_for_io(folio)) {
1004 f = 0;
1005 t = folio_size(folio);
1006 if (folio_test_private(folio)) {
1007 f = afs_folio_dirty_from(folio, priv);
1008 t = afs_folio_dirty_to(folio, priv);
1009 }
1010
1011 bv[0].bv_page = &folio->page;
1012 bv[0].bv_offset = f;
1013 bv[0].bv_len = t - f;
1014 iov_iter_bvec(&iter, ITER_SOURCE, bv, 1, bv[0].bv_len);
1015
1016 trace_afs_folio_dirty(vnode, tracepoint_string("launder"), folio);
1017 ret = afs_store_data(vnode, &iter, folio_pos(folio) + f, true);
1018 }
1019
1020 trace_afs_folio_dirty(vnode, tracepoint_string("laundered"), folio);
1021 folio_detach_private(folio);
1022 folio_wait_fscache(folio);
1023 return ret;
1024}
1025
1026/*
1027 * Deal with the completion of writing the data to the cache.
1028 */
1029static void afs_write_to_cache_done(void *priv, ssize_t transferred_or_error,
1030 bool was_async)
1031{
1032 struct afs_vnode *vnode = priv;
1033
1034 if (IS_ERR_VALUE(transferred_or_error) &&
1035 transferred_or_error != -ENOBUFS)
1036 afs_invalidate_cache(vnode, 0);
1037}
1038
1039/*
1040 * Save the write to the cache also.
1041 */
1042static void afs_write_to_cache(struct afs_vnode *vnode,
1043 loff_t start, size_t len, loff_t i_size,
1044 bool caching)
1045{
1046 fscache_write_to_cache(afs_vnode_cache(vnode),
1047 vnode->netfs.inode.i_mapping, start, len, i_size,
1048 afs_write_to_cache_done, vnode, caching);
1049}
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_CACHE_SIZE > i_size)
97 len = i_size - pos;
98 else
99 len = PAGE_CACHE_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->f_dentry->d_inode);
124 struct page *page;
125 struct key *key = file->private_data;
126 unsigned from = pos & (PAGE_CACHE_SIZE - 1);
127 unsigned to = from + len;
128 pgoff_t index = pos >> PAGE_CACHE_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_CACHE_SIZE) {
155 ret = afs_fill_page(vnode, key, index << PAGE_CACHE_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->f_dentry->d_inode);
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 page_cache_release(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 set_bit(AS_ENOSPC,
402 &wb->vnode->vfs_inode.i_mapping->flags);
403 break;
404 case -EROFS:
405 case -EIO:
406 case -EREMOTEIO:
407 case -EFBIG:
408 case -ENOENT:
409 case -ENOMEDIUM:
410 case -ENXIO:
411 afs_kill_pages(wb->vnode, true, first, last);
412 set_bit(AS_EIO, &wb->vnode->vfs_inode.i_mapping->flags);
413 break;
414 case -EACCES:
415 case -EPERM:
416 case -ENOKEY:
417 case -EKEYEXPIRED:
418 case -EKEYREJECTED:
419 case -EKEYREVOKED:
420 afs_kill_pages(wb->vnode, false, first, last);
421 break;
422 default:
423 break;
424 }
425 } else {
426 ret = count;
427 }
428
429 _leave(" = %d", ret);
430 return ret;
431}
432
433/*
434 * write a page back to the server
435 * - the caller locked the page for us
436 */
437int afs_writepage(struct page *page, struct writeback_control *wbc)
438{
439 struct afs_writeback *wb;
440 int ret;
441
442 _enter("{%lx},", page->index);
443
444 wb = (struct afs_writeback *) page_private(page);
445 ASSERT(wb != NULL);
446
447 ret = afs_write_back_from_locked_page(wb, page);
448 unlock_page(page);
449 if (ret < 0) {
450 _leave(" = %d", ret);
451 return 0;
452 }
453
454 wbc->nr_to_write -= ret;
455
456 _leave(" = 0");
457 return 0;
458}
459
460/*
461 * write a region of pages back to the server
462 */
463static int afs_writepages_region(struct address_space *mapping,
464 struct writeback_control *wbc,
465 pgoff_t index, pgoff_t end, pgoff_t *_next)
466{
467 struct afs_writeback *wb;
468 struct page *page;
469 int ret, n;
470
471 _enter(",,%lx,%lx,", index, end);
472
473 do {
474 n = find_get_pages_tag(mapping, &index, PAGECACHE_TAG_DIRTY,
475 1, &page);
476 if (!n)
477 break;
478
479 _debug("wback %lx", page->index);
480
481 if (page->index > end) {
482 *_next = index;
483 page_cache_release(page);
484 _leave(" = 0 [%lx]", *_next);
485 return 0;
486 }
487
488 /* at this point we hold neither mapping->tree_lock nor lock on
489 * the page itself: the page may be truncated or invalidated
490 * (changing page->mapping to NULL), or even swizzled back from
491 * swapper_space to tmpfs file mapping
492 */
493 lock_page(page);
494
495 if (page->mapping != mapping) {
496 unlock_page(page);
497 page_cache_release(page);
498 continue;
499 }
500
501 if (wbc->sync_mode != WB_SYNC_NONE)
502 wait_on_page_writeback(page);
503
504 if (PageWriteback(page) || !PageDirty(page)) {
505 unlock_page(page);
506 continue;
507 }
508
509 wb = (struct afs_writeback *) page_private(page);
510 ASSERT(wb != NULL);
511
512 spin_lock(&wb->vnode->writeback_lock);
513 wb->state = AFS_WBACK_WRITING;
514 spin_unlock(&wb->vnode->writeback_lock);
515
516 ret = afs_write_back_from_locked_page(wb, page);
517 unlock_page(page);
518 page_cache_release(page);
519 if (ret < 0) {
520 _leave(" = %d", ret);
521 return ret;
522 }
523
524 wbc->nr_to_write -= ret;
525
526 cond_resched();
527 } while (index < end && wbc->nr_to_write > 0);
528
529 *_next = index;
530 _leave(" = 0 [%lx]", *_next);
531 return 0;
532}
533
534/*
535 * write some of the pending data back to the server
536 */
537int afs_writepages(struct address_space *mapping,
538 struct writeback_control *wbc)
539{
540 pgoff_t start, end, next;
541 int ret;
542
543 _enter("");
544
545 if (wbc->range_cyclic) {
546 start = mapping->writeback_index;
547 end = -1;
548 ret = afs_writepages_region(mapping, wbc, start, end, &next);
549 if (start > 0 && wbc->nr_to_write > 0 && ret == 0)
550 ret = afs_writepages_region(mapping, wbc, 0, start,
551 &next);
552 mapping->writeback_index = next;
553 } else if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) {
554 end = (pgoff_t)(LLONG_MAX >> PAGE_CACHE_SHIFT);
555 ret = afs_writepages_region(mapping, wbc, 0, end, &next);
556 if (wbc->nr_to_write > 0)
557 mapping->writeback_index = next;
558 } else {
559 start = wbc->range_start >> PAGE_CACHE_SHIFT;
560 end = wbc->range_end >> PAGE_CACHE_SHIFT;
561 ret = afs_writepages_region(mapping, wbc, start, end, &next);
562 }
563
564 _leave(" = %d", ret);
565 return ret;
566}
567
568/*
569 * completion of write to server
570 */
571void afs_pages_written_back(struct afs_vnode *vnode, struct afs_call *call)
572{
573 struct afs_writeback *wb = call->wb;
574 struct pagevec pv;
575 unsigned count, loop;
576 pgoff_t first = call->first, last = call->last;
577 bool free_wb;
578
579 _enter("{%x:%u},{%lx-%lx}",
580 vnode->fid.vid, vnode->fid.vnode, first, last);
581
582 ASSERT(wb != NULL);
583
584 pagevec_init(&pv, 0);
585
586 do {
587 _debug("done %lx-%lx", first, last);
588
589 count = last - first + 1;
590 if (count > PAGEVEC_SIZE)
591 count = PAGEVEC_SIZE;
592 pv.nr = find_get_pages_contig(call->mapping, first, count,
593 pv.pages);
594 ASSERTCMP(pv.nr, ==, count);
595
596 spin_lock(&vnode->writeback_lock);
597 for (loop = 0; loop < count; loop++) {
598 struct page *page = pv.pages[loop];
599 end_page_writeback(page);
600 if (page_private(page) == (unsigned long) wb) {
601 set_page_private(page, 0);
602 ClearPagePrivate(page);
603 wb->usage--;
604 }
605 }
606 free_wb = false;
607 if (wb->usage == 0) {
608 afs_unlink_writeback(wb);
609 free_wb = true;
610 }
611 spin_unlock(&vnode->writeback_lock);
612 first += count;
613 if (free_wb) {
614 afs_free_writeback(wb);
615 wb = NULL;
616 }
617
618 __pagevec_release(&pv);
619 } while (first <= last);
620
621 _leave("");
622}
623
624/*
625 * write to an AFS file
626 */
627ssize_t afs_file_write(struct kiocb *iocb, const struct iovec *iov,
628 unsigned long nr_segs, loff_t pos)
629{
630 struct dentry *dentry = iocb->ki_filp->f_path.dentry;
631 struct afs_vnode *vnode = AFS_FS_I(dentry->d_inode);
632 ssize_t result;
633 size_t count = iov_length(iov, nr_segs);
634
635 _enter("{%x.%u},{%zu},%lu,",
636 vnode->fid.vid, vnode->fid.vnode, count, nr_segs);
637
638 if (IS_SWAPFILE(&vnode->vfs_inode)) {
639 printk(KERN_INFO
640 "AFS: Attempt to write to active swap file!\n");
641 return -EBUSY;
642 }
643
644 if (!count)
645 return 0;
646
647 result = generic_file_aio_write(iocb, iov, nr_segs, pos);
648 if (IS_ERR_VALUE(result)) {
649 _leave(" = %zd", result);
650 return result;
651 }
652
653 _leave(" = %zd", result);
654 return result;
655}
656
657/*
658 * flush the vnode to the fileserver
659 */
660int afs_writeback_all(struct afs_vnode *vnode)
661{
662 struct address_space *mapping = vnode->vfs_inode.i_mapping;
663 struct writeback_control wbc = {
664 .sync_mode = WB_SYNC_ALL,
665 .nr_to_write = LONG_MAX,
666 .range_cyclic = 1,
667 };
668 int ret;
669
670 _enter("");
671
672 ret = mapping->a_ops->writepages(mapping, &wbc);
673 __mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
674
675 _leave(" = %d", ret);
676 return ret;
677}
678
679/*
680 * flush any dirty pages for this process, and check for write errors.
681 * - the return status from this call provides a reliable indication of
682 * whether any write errors occurred for this process.
683 */
684int afs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
685{
686 struct dentry *dentry = file->f_path.dentry;
687 struct inode *inode = file->f_mapping->host;
688 struct afs_writeback *wb, *xwb;
689 struct afs_vnode *vnode = AFS_FS_I(dentry->d_inode);
690 int ret;
691
692 _enter("{%x:%u},{n=%s},%d",
693 vnode->fid.vid, vnode->fid.vnode, dentry->d_name.name,
694 datasync);
695
696 ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
697 if (ret)
698 return ret;
699 mutex_lock(&inode->i_mutex);
700
701 /* use a writeback record as a marker in the queue - when this reaches
702 * the front of the queue, all the outstanding writes are either
703 * completed or rejected */
704 wb = kzalloc(sizeof(*wb), GFP_KERNEL);
705 if (!wb) {
706 ret = -ENOMEM;
707 goto out;
708 }
709 wb->vnode = vnode;
710 wb->first = 0;
711 wb->last = -1;
712 wb->offset_first = 0;
713 wb->to_last = PAGE_SIZE;
714 wb->usage = 1;
715 wb->state = AFS_WBACK_SYNCING;
716 init_waitqueue_head(&wb->waitq);
717
718 spin_lock(&vnode->writeback_lock);
719 list_for_each_entry(xwb, &vnode->writebacks, link) {
720 if (xwb->state == AFS_WBACK_PENDING)
721 xwb->state = AFS_WBACK_CONFLICTING;
722 }
723 list_add_tail(&wb->link, &vnode->writebacks);
724 spin_unlock(&vnode->writeback_lock);
725
726 /* push all the outstanding writebacks to the server */
727 ret = afs_writeback_all(vnode);
728 if (ret < 0) {
729 afs_put_writeback(wb);
730 _leave(" = %d [wb]", ret);
731 goto out;
732 }
733
734 /* wait for the preceding writes to actually complete */
735 ret = wait_event_interruptible(wb->waitq,
736 wb->state == AFS_WBACK_COMPLETE ||
737 vnode->writebacks.next == &wb->link);
738 afs_put_writeback(wb);
739 _leave(" = %d", ret);
740out:
741 mutex_unlock(&inode->i_mutex);
742 return ret;
743}
744
745/*
746 * notification that a previously read-only page is about to become writable
747 * - if it returns an error, the caller will deliver a bus error signal
748 */
749int afs_page_mkwrite(struct vm_area_struct *vma, struct page *page)
750{
751 struct afs_vnode *vnode = AFS_FS_I(vma->vm_file->f_mapping->host);
752
753 _enter("{{%x:%u}},{%lx}",
754 vnode->fid.vid, vnode->fid.vnode, page->index);
755
756 /* wait for the page to be written to the cache before we allow it to
757 * be modified */
758#ifdef CONFIG_AFS_FSCACHE
759 fscache_wait_on_page_write(vnode->cache, page);
760#endif
761
762 _leave(" = 0");
763 return 0;
764}