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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
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}