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 cookie: afs_vnode_cache(vnode: AFS_FS_I(inode: 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: &wbc, start: folio_pos(folio), LLONG_MAX,
62 next: &next, max_one_loop: 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(inode: file_inode(f: 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, index: 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(inode: file_inode(f: 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(inode: &vnode->netfs.inode);
182 if (write_end_pos > i_size) {
183 write_seqlock(sl: &vnode->cb_lock);
184 i_size = i_size_read(inode: &vnode->netfs.inode);
185 if (write_end_pos > i_size)
186 afs_set_i_size(vnode, size: write_end_pos);
187 write_sequnlock(sl: &vnode->cb_lock);
188 fscache_update_cookie(cookie: afs_vnode_cache(vnode), NULL, object_size: &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, from: f, to: t);
200 folio_change_private(folio, data: (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, data: (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(inode: 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 (IS_ERR(ptr: 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, page: &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(inode: 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 (IS_ERR(ptr: 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(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(key: wbk->key);
344 if (ret2 == 0) {
345 refcount_inc(r: &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(lock: &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, start: op->store.pos, len: op->store.size);
372 afs_stat_v(vnode, n_stores);
373 atomic_long_add(i: op->store.size, v: &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(i: 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: &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(ptr: op)) {
409 afs_put_wb_key(wbk);
410 return -ENOMEM;
411 }
412
413 afs_op_set_vnode(op, n: 0, vnode);
414 op->file[0].dv_delta = 1;
415 op->file[0].modification = true;
416 op->store.pos = pos;
417 op->store.size = size;
418 op->store.laundering = laundering;
419 op->flags |= AFS_OPERATION_UNINTR;
420 op->ops = &afs_store_data_operation;
421
422try_next_key:
423 afs_begin_vnode_operation(op);
424
425 op->store.write_iter = iter;
426 op->store.i_size = max(pos + size, vnode->netfs.remote_i_size);
427 op->mtime = inode_get_mtime(inode: &vnode->netfs.inode);
428
429 afs_wait_for_operation(op);
430
431 switch (op->error) {
432 case -EACCES:
433 case -EPERM:
434 case -ENOKEY:
435 case -EKEYEXPIRED:
436 case -EKEYREJECTED:
437 case -EKEYREVOKED:
438 _debug("next");
439
440 ret = afs_get_writeback_key(vnode, wbk: &wbk);
441 if (ret == 0) {
442 key_put(key: op->key);
443 op->key = key_get(key: wbk->key);
444 goto try_next_key;
445 }
446 break;
447 }
448
449 afs_put_wb_key(wbk);
450 _leave(" = %d", op->error);
451 return afs_put_operation(op);
452}
453
454/*
455 * Extend the region to be written back to include subsequent contiguously
456 * dirty pages if possible, but don't sleep while doing so.
457 *
458 * If this page holds new content, then we can include filler zeros in the
459 * writeback.
460 */
461static void afs_extend_writeback(struct address_space *mapping,
462 struct afs_vnode *vnode,
463 long *_count,
464 loff_t start,
465 loff_t max_len,
466 bool new_content,
467 bool caching,
468 unsigned int *_len)
469{
470 struct folio_batch fbatch;
471 struct folio *folio;
472 unsigned long priv;
473 unsigned int psize, filler = 0;
474 unsigned int f, t;
475 loff_t len = *_len;
476 pgoff_t index = (start + len) / PAGE_SIZE;
477 bool stop = true;
478 unsigned int i;
479
480 XA_STATE(xas, &mapping->i_pages, index);
481 folio_batch_init(fbatch: &fbatch);
482
483 do {
484 /* Firstly, we gather up a batch of contiguous dirty pages
485 * under the RCU read lock - but we can't clear the dirty flags
486 * there if any of those pages are mapped.
487 */
488 rcu_read_lock();
489
490 xas_for_each(&xas, folio, ULONG_MAX) {
491 stop = true;
492 if (xas_retry(xas: &xas, entry: folio))
493 continue;
494 if (xa_is_value(entry: folio))
495 break;
496 if (folio_index(folio) != index)
497 break;
498
499 if (!folio_try_get_rcu(folio)) {
500 xas_reset(xas: &xas);
501 continue;
502 }
503
504 /* Has the page moved or been split? */
505 if (unlikely(folio != xas_reload(&xas))) {
506 folio_put(folio);
507 break;
508 }
509
510 if (!folio_trylock(folio)) {
511 folio_put(folio);
512 break;
513 }
514 if (!folio_test_dirty(folio) ||
515 folio_test_writeback(folio) ||
516 folio_test_fscache(folio)) {
517 folio_unlock(folio);
518 folio_put(folio);
519 break;
520 }
521
522 psize = folio_size(folio);
523 priv = (unsigned long)folio_get_private(folio);
524 f = afs_folio_dirty_from(folio, priv);
525 t = afs_folio_dirty_to(folio, priv);
526 if (f != 0 && !new_content) {
527 folio_unlock(folio);
528 folio_put(folio);
529 break;
530 }
531
532 len += filler + t;
533 filler = psize - t;
534 if (len >= max_len || *_count <= 0)
535 stop = true;
536 else if (t == psize || new_content)
537 stop = false;
538
539 index += folio_nr_pages(folio);
540 if (!folio_batch_add(fbatch: &fbatch, folio))
541 break;
542 if (stop)
543 break;
544 }
545
546 if (!stop)
547 xas_pause(&xas);
548 rcu_read_unlock();
549
550 /* Now, if we obtained any folios, we can shift them to being
551 * writable and mark them for caching.
552 */
553 if (!folio_batch_count(fbatch: &fbatch))
554 break;
555
556 for (i = 0; i < folio_batch_count(fbatch: &fbatch); i++) {
557 folio = fbatch.folios[i];
558 trace_afs_folio_dirty(vnode, tracepoint_string("store+"), folio);
559
560 if (!folio_clear_dirty_for_io(folio))
561 BUG();
562 if (folio_start_writeback(folio))
563 BUG();
564 afs_folio_start_fscache(caching, folio);
565
566 *_count -= folio_nr_pages(folio);
567 folio_unlock(folio);
568 }
569
570 folio_batch_release(fbatch: &fbatch);
571 cond_resched();
572 } while (!stop);
573
574 *_len = len;
575}
576
577/*
578 * Synchronously write back the locked page and any subsequent non-locked dirty
579 * pages.
580 */
581static ssize_t afs_write_back_from_locked_folio(struct address_space *mapping,
582 struct writeback_control *wbc,
583 struct folio *folio,
584 loff_t start, loff_t end)
585{
586 struct afs_vnode *vnode = AFS_FS_I(inode: mapping->host);
587 struct iov_iter iter;
588 unsigned long priv;
589 unsigned int offset, to, len, max_len;
590 loff_t i_size = i_size_read(inode: &vnode->netfs.inode);
591 bool new_content = test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags);
592 bool caching = fscache_cookie_enabled(afs_vnode_cache(vnode));
593 long count = wbc->nr_to_write;
594 int ret;
595
596 _enter(",%lx,%llx-%llx", folio_index(folio), start, end);
597
598 if (folio_start_writeback(folio))
599 BUG();
600 afs_folio_start_fscache(caching, folio);
601
602 count -= folio_nr_pages(folio);
603
604 /* Find all consecutive lockable dirty pages that have contiguous
605 * written regions, stopping when we find a page that is not
606 * immediately lockable, is not dirty or is missing, or we reach the
607 * end of the range.
608 */
609 priv = (unsigned long)folio_get_private(folio);
610 offset = afs_folio_dirty_from(folio, priv);
611 to = afs_folio_dirty_to(folio, priv);
612 trace_afs_folio_dirty(vnode, tracepoint_string("store"), folio);
613
614 len = to - offset;
615 start += offset;
616 if (start < i_size) {
617 /* Trim the write to the EOF; the extra data is ignored. Also
618 * put an upper limit on the size of a single storedata op.
619 */
620 max_len = 65536 * 4096;
621 max_len = min_t(unsigned long long, max_len, end - start + 1);
622 max_len = min_t(unsigned long long, max_len, i_size - start);
623
624 if (len < max_len &&
625 (to == folio_size(folio) || new_content))
626 afs_extend_writeback(mapping, vnode, count: &count,
627 start, max_len, new_content,
628 caching, len: &len);
629 len = min_t(loff_t, len, max_len);
630 }
631
632 /* We now have a contiguous set of dirty pages, each with writeback
633 * set; the first page is still locked at this point, but all the rest
634 * have been unlocked.
635 */
636 folio_unlock(folio);
637
638 if (start < i_size) {
639 _debug("write back %x @%llx [%llx]", len, start, i_size);
640
641 /* Speculatively write to the cache. We have to fix this up
642 * later if the store fails.
643 */
644 afs_write_to_cache(vnode, start, len, i_size, caching);
645
646 iov_iter_xarray(i: &iter, ITER_SOURCE, xarray: &mapping->i_pages, start, count: len);
647 ret = afs_store_data(vnode, iter: &iter, pos: start, laundering: false);
648 } else {
649 _debug("write discard %x @%llx [%llx]", len, start, i_size);
650
651 /* The dirty region was entirely beyond the EOF. */
652 fscache_clear_page_bits(mapping, start, len, caching);
653 afs_pages_written_back(vnode, start, len);
654 ret = 0;
655 }
656
657 switch (ret) {
658 case 0:
659 wbc->nr_to_write = count;
660 ret = len;
661 break;
662
663 default:
664 pr_notice("kAFS: Unexpected error from FS.StoreData %d\n", ret);
665 fallthrough;
666 case -EACCES:
667 case -EPERM:
668 case -ENOKEY:
669 case -EKEYEXPIRED:
670 case -EKEYREJECTED:
671 case -EKEYREVOKED:
672 case -ENETRESET:
673 afs_redirty_pages(wbc, mapping, start, len);
674 mapping_set_error(mapping, error: ret);
675 break;
676
677 case -EDQUOT:
678 case -ENOSPC:
679 afs_redirty_pages(wbc, mapping, start, len);
680 mapping_set_error(mapping, error: -ENOSPC);
681 break;
682
683 case -EROFS:
684 case -EIO:
685 case -EREMOTEIO:
686 case -EFBIG:
687 case -ENOENT:
688 case -ENOMEDIUM:
689 case -ENXIO:
690 trace_afs_file_error(vnode, error: ret, where: afs_file_error_writeback_fail);
691 afs_kill_pages(mapping, start, len);
692 mapping_set_error(mapping, error: ret);
693 break;
694 }
695
696 _leave(" = %d", ret);
697 return ret;
698}
699
700/*
701 * write a region of pages back to the server
702 */
703static int afs_writepages_region(struct address_space *mapping,
704 struct writeback_control *wbc,
705 loff_t start, loff_t end, loff_t *_next,
706 bool max_one_loop)
707{
708 struct folio *folio;
709 struct folio_batch fbatch;
710 ssize_t ret;
711 unsigned int i;
712 int n, skips = 0;
713
714 _enter("%llx,%llx,", start, end);
715 folio_batch_init(fbatch: &fbatch);
716
717 do {
718 pgoff_t index = start / PAGE_SIZE;
719
720 n = filemap_get_folios_tag(mapping, start: &index, end: end / PAGE_SIZE,
721 PAGECACHE_TAG_DIRTY, fbatch: &fbatch);
722
723 if (!n)
724 break;
725 for (i = 0; i < n; i++) {
726 folio = fbatch.folios[i];
727 start = folio_pos(folio); /* May regress with THPs */
728
729 _debug("wback %lx", folio_index(folio));
730
731 /* At this point we hold neither the i_pages lock nor the
732 * page lock: the page may be truncated or invalidated
733 * (changing page->mapping to NULL), or even swizzled
734 * back from swapper_space to tmpfs file mapping
735 */
736try_again:
737 if (wbc->sync_mode != WB_SYNC_NONE) {
738 ret = folio_lock_killable(folio);
739 if (ret < 0) {
740 folio_batch_release(fbatch: &fbatch);
741 return ret;
742 }
743 } else {
744 if (!folio_trylock(folio))
745 continue;
746 }
747
748 if (folio->mapping != mapping ||
749 !folio_test_dirty(folio)) {
750 start += folio_size(folio);
751 folio_unlock(folio);
752 continue;
753 }
754
755 if (folio_test_writeback(folio) ||
756 folio_test_fscache(folio)) {
757 folio_unlock(folio);
758 if (wbc->sync_mode != WB_SYNC_NONE) {
759 folio_wait_writeback(folio);
760#ifdef CONFIG_AFS_FSCACHE
761 folio_wait_fscache(folio);
762#endif
763 goto try_again;
764 }
765
766 start += folio_size(folio);
767 if (wbc->sync_mode == WB_SYNC_NONE) {
768 if (skips >= 5 || need_resched()) {
769 *_next = start;
770 folio_batch_release(fbatch: &fbatch);
771 _leave(" = 0 [%llx]", *_next);
772 return 0;
773 }
774 skips++;
775 }
776 continue;
777 }
778
779 if (!folio_clear_dirty_for_io(folio))
780 BUG();
781 ret = afs_write_back_from_locked_folio(mapping, wbc,
782 folio, start, end);
783 if (ret < 0) {
784 _leave(" = %zd", ret);
785 folio_batch_release(fbatch: &fbatch);
786 return ret;
787 }
788
789 start += ret;
790 }
791
792 folio_batch_release(fbatch: &fbatch);
793 cond_resched();
794 } while (wbc->nr_to_write > 0);
795
796 *_next = start;
797 _leave(" = 0 [%llx]", *_next);
798 return 0;
799}
800
801/*
802 * write some of the pending data back to the server
803 */
804int afs_writepages(struct address_space *mapping,
805 struct writeback_control *wbc)
806{
807 struct afs_vnode *vnode = AFS_FS_I(inode: mapping->host);
808 loff_t start, next;
809 int ret;
810
811 _enter("");
812
813 /* We have to be careful as we can end up racing with setattr()
814 * truncating the pagecache since the caller doesn't take a lock here
815 * to prevent it.
816 */
817 if (wbc->sync_mode == WB_SYNC_ALL)
818 down_read(sem: &vnode->validate_lock);
819 else if (!down_read_trylock(sem: &vnode->validate_lock))
820 return 0;
821
822 if (wbc->range_cyclic) {
823 start = mapping->writeback_index * PAGE_SIZE;
824 ret = afs_writepages_region(mapping, wbc, start, LLONG_MAX,
825 next: &next, max_one_loop: false);
826 if (ret == 0) {
827 mapping->writeback_index = next / PAGE_SIZE;
828 if (start > 0 && wbc->nr_to_write > 0) {
829 ret = afs_writepages_region(mapping, wbc, start: 0,
830 end: start, next: &next, max_one_loop: false);
831 if (ret == 0)
832 mapping->writeback_index =
833 next / PAGE_SIZE;
834 }
835 }
836 } else if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) {
837 ret = afs_writepages_region(mapping, wbc, start: 0, LLONG_MAX,
838 next: &next, max_one_loop: false);
839 if (wbc->nr_to_write > 0 && ret == 0)
840 mapping->writeback_index = next / PAGE_SIZE;
841 } else {
842 ret = afs_writepages_region(mapping, wbc,
843 start: wbc->range_start, end: wbc->range_end,
844 next: &next, max_one_loop: false);
845 }
846
847 up_read(sem: &vnode->validate_lock);
848 _leave(" = %d", ret);
849 return ret;
850}
851
852/*
853 * write to an AFS file
854 */
855ssize_t afs_file_write(struct kiocb *iocb, struct iov_iter *from)
856{
857 struct afs_vnode *vnode = AFS_FS_I(inode: file_inode(f: iocb->ki_filp));
858 struct afs_file *af = iocb->ki_filp->private_data;
859 ssize_t result;
860 size_t count = iov_iter_count(i: from);
861
862 _enter("{%llx:%llu},{%zu},",
863 vnode->fid.vid, vnode->fid.vnode, count);
864
865 if (IS_SWAPFILE(&vnode->netfs.inode)) {
866 printk(KERN_INFO
867 "AFS: Attempt to write to active swap file!\n");
868 return -EBUSY;
869 }
870
871 if (!count)
872 return 0;
873
874 result = afs_validate(vnode, af->key);
875 if (result < 0)
876 return result;
877
878 result = generic_file_write_iter(iocb, from);
879
880 _leave(" = %zd", result);
881 return result;
882}
883
884/*
885 * flush any dirty pages for this process, and check for write errors.
886 * - the return status from this call provides a reliable indication of
887 * whether any write errors occurred for this process.
888 */
889int afs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
890{
891 struct afs_vnode *vnode = AFS_FS_I(inode: file_inode(f: file));
892 struct afs_file *af = file->private_data;
893 int ret;
894
895 _enter("{%llx:%llu},{n=%pD},%d",
896 vnode->fid.vid, vnode->fid.vnode, file,
897 datasync);
898
899 ret = afs_validate(vnode, af->key);
900 if (ret < 0)
901 return ret;
902
903 return file_write_and_wait_range(file, start, end);
904}
905
906/*
907 * notification that a previously read-only page is about to become writable
908 * - if it returns an error, the caller will deliver a bus error signal
909 */
910vm_fault_t afs_page_mkwrite(struct vm_fault *vmf)
911{
912 struct folio *folio = page_folio(vmf->page);
913 struct file *file = vmf->vma->vm_file;
914 struct inode *inode = file_inode(f: file);
915 struct afs_vnode *vnode = AFS_FS_I(inode);
916 struct afs_file *af = file->private_data;
917 unsigned long priv;
918 vm_fault_t ret = VM_FAULT_RETRY;
919
920 _enter("{{%llx:%llu}},{%lx}", vnode->fid.vid, vnode->fid.vnode, folio_index(folio));
921
922 afs_validate(vnode, af->key);
923
924 sb_start_pagefault(sb: inode->i_sb);
925
926 /* Wait for the page to be written to the cache before we allow it to
927 * be modified. We then assume the entire page will need writing back.
928 */
929#ifdef CONFIG_AFS_FSCACHE
930 if (folio_test_fscache(folio) &&
931 folio_wait_fscache_killable(folio) < 0)
932 goto out;
933#endif
934
935 if (folio_wait_writeback_killable(folio))
936 goto out;
937
938 if (folio_lock_killable(folio) < 0)
939 goto out;
940
941 /* We mustn't change folio->private until writeback is complete as that
942 * details the portion of the page we need to write back and we might
943 * need to redirty the page if there's a problem.
944 */
945 if (folio_wait_writeback_killable(folio) < 0) {
946 folio_unlock(folio);
947 goto out;
948 }
949
950 priv = afs_folio_dirty(folio, from: 0, to: folio_size(folio));
951 priv = afs_folio_dirty_mmapped(priv);
952 if (folio_test_private(folio)) {
953 folio_change_private(folio, data: (void *)priv);
954 trace_afs_folio_dirty(vnode, tracepoint_string("mkwrite+"), folio);
955 } else {
956 folio_attach_private(folio, data: (void *)priv);
957 trace_afs_folio_dirty(vnode, tracepoint_string("mkwrite"), folio);
958 }
959 file_update_time(file);
960
961 ret = VM_FAULT_LOCKED;
962out:
963 sb_end_pagefault(sb: inode->i_sb);
964 return ret;
965}
966
967/*
968 * Prune the keys cached for writeback. The caller must hold vnode->wb_lock.
969 */
970void afs_prune_wb_keys(struct afs_vnode *vnode)
971{
972 LIST_HEAD(graveyard);
973 struct afs_wb_key *wbk, *tmp;
974
975 /* Discard unused keys */
976 spin_lock(lock: &vnode->wb_lock);
977
978 if (!mapping_tagged(mapping: &vnode->netfs.inode.i_data, PAGECACHE_TAG_WRITEBACK) &&
979 !mapping_tagged(mapping: &vnode->netfs.inode.i_data, PAGECACHE_TAG_DIRTY)) {
980 list_for_each_entry_safe(wbk, tmp, &vnode->wb_keys, vnode_link) {
981 if (refcount_read(r: &wbk->usage) == 1)
982 list_move(list: &wbk->vnode_link, head: &graveyard);
983 }
984 }
985
986 spin_unlock(lock: &vnode->wb_lock);
987
988 while (!list_empty(head: &graveyard)) {
989 wbk = list_entry(graveyard.next, struct afs_wb_key, vnode_link);
990 list_del(entry: &wbk->vnode_link);
991 afs_put_wb_key(wbk);
992 }
993}
994
995/*
996 * Clean up a page during invalidation.
997 */
998int afs_launder_folio(struct folio *folio)
999{
1000 struct afs_vnode *vnode = AFS_FS_I(inode: folio_inode(folio));
1001 struct iov_iter iter;
1002 struct bio_vec bv;
1003 unsigned long priv;
1004 unsigned int f, t;
1005 int ret = 0;
1006
1007 _enter("{%lx}", folio->index);
1008
1009 priv = (unsigned long)folio_get_private(folio);
1010 if (folio_clear_dirty_for_io(folio)) {
1011 f = 0;
1012 t = folio_size(folio);
1013 if (folio_test_private(folio)) {
1014 f = afs_folio_dirty_from(folio, priv);
1015 t = afs_folio_dirty_to(folio, priv);
1016 }
1017
1018 bvec_set_folio(bv: &bv, folio, len: t - f, offset: f);
1019 iov_iter_bvec(i: &iter, ITER_SOURCE, bvec: &bv, nr_segs: 1, count: bv.bv_len);
1020
1021 trace_afs_folio_dirty(vnode, tracepoint_string("launder"), folio);
1022 ret = afs_store_data(vnode, iter: &iter, pos: folio_pos(folio) + f, laundering: true);
1023 }
1024
1025 trace_afs_folio_dirty(vnode, tracepoint_string("laundered"), folio);
1026 folio_detach_private(folio);
1027 folio_wait_fscache(folio);
1028 return ret;
1029}
1030
1031/*
1032 * Deal with the completion of writing the data to the cache.
1033 */
1034static void afs_write_to_cache_done(void *priv, ssize_t transferred_or_error,
1035 bool was_async)
1036{
1037 struct afs_vnode *vnode = priv;
1038
1039 if (IS_ERR_VALUE(transferred_or_error) &&
1040 transferred_or_error != -ENOBUFS)
1041 afs_invalidate_cache(vnode, flags: 0);
1042}
1043
1044/*
1045 * Save the write to the cache also.
1046 */
1047static void afs_write_to_cache(struct afs_vnode *vnode,
1048 loff_t start, size_t len, loff_t i_size,
1049 bool caching)
1050{
1051 fscache_write_to_cache(cookie: afs_vnode_cache(vnode),
1052 mapping: vnode->netfs.inode.i_mapping, start, len, i_size,
1053 term_func: afs_write_to_cache_done, term_func_priv: vnode, caching);
1054}
1055

source code of linux/fs/afs/write.c