1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* handling of writes to regular files and writing back to the server
3 *
4 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8 #include <linux/backing-dev.h>
9 #include <linux/slab.h>
10 #include <linux/fs.h>
11 #include <linux/pagemap.h>
12 #include <linux/writeback.h>
13 #include <linux/pagevec.h>
14 #include <linux/netfs.h>
15 #include <linux/fscache.h>
16 #include "internal.h"
17
18 /*
19 * mark a page as having been made dirty and thus needing writeback
20 */
afs_set_page_dirty(struct page * page)21 int afs_set_page_dirty(struct page *page)
22 {
23 _enter("");
24 return __set_page_dirty_nobuffers(page);
25 }
26
27 /*
28 * prepare to perform part of a write to a page
29 */
afs_write_begin(struct file * file,struct address_space * mapping,loff_t pos,unsigned len,unsigned flags,struct page ** _page,void ** fsdata)30 int afs_write_begin(struct file *file, struct address_space *mapping,
31 loff_t pos, unsigned len, unsigned flags,
32 struct page **_page, void **fsdata)
33 {
34 struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
35 struct page *page;
36 unsigned long priv;
37 unsigned f, from;
38 unsigned t, to;
39 pgoff_t index;
40 int ret;
41
42 _enter("{%llx:%llu},%llx,%x",
43 vnode->fid.vid, vnode->fid.vnode, pos, len);
44
45 /* Prefetch area to be written into the cache if we're caching this
46 * file. We need to do this before we get a lock on the page in case
47 * there's more than one writer competing for the same cache block.
48 */
49 ret = netfs_write_begin(file, mapping, pos, len, flags, &page, fsdata,
50 &afs_req_ops, NULL);
51 if (ret < 0)
52 return ret;
53
54 index = page->index;
55 from = pos - index * PAGE_SIZE;
56 to = from + len;
57
58 try_again:
59 /* See if this page is already partially written in a way that we can
60 * merge the new write with.
61 */
62 if (PagePrivate(page)) {
63 priv = page_private(page);
64 f = afs_page_dirty_from(page, priv);
65 t = afs_page_dirty_to(page, priv);
66 ASSERTCMP(f, <=, t);
67
68 if (PageWriteback(page)) {
69 trace_afs_page_dirty(vnode, tracepoint_string("alrdy"), page);
70 goto flush_conflicting_write;
71 }
72 /* If the file is being filled locally, allow inter-write
73 * spaces to be merged into writes. If it's not, only write
74 * back what the user gives us.
75 */
76 if (!test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags) &&
77 (to < f || from > t))
78 goto flush_conflicting_write;
79 }
80
81 *_page = page;
82 _leave(" = 0");
83 return 0;
84
85 /* The previous write and this write aren't adjacent or overlapping, so
86 * flush the page out.
87 */
88 flush_conflicting_write:
89 _debug("flush conflict");
90 ret = write_one_page(page);
91 if (ret < 0)
92 goto error;
93
94 ret = lock_page_killable(page);
95 if (ret < 0)
96 goto error;
97 goto try_again;
98
99 error:
100 put_page(page);
101 _leave(" = %d", ret);
102 return ret;
103 }
104
105 /*
106 * finalise part of a write to a page
107 */
afs_write_end(struct file * file,struct address_space * mapping,loff_t pos,unsigned len,unsigned copied,struct page * page,void * fsdata)108 int afs_write_end(struct file *file, struct address_space *mapping,
109 loff_t pos, unsigned len, unsigned copied,
110 struct page *page, void *fsdata)
111 {
112 struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
113 unsigned long priv;
114 unsigned int f, from = pos & (thp_size(page) - 1);
115 unsigned int t, to = from + copied;
116 loff_t i_size, maybe_i_size;
117
118 _enter("{%llx:%llu},{%lx}",
119 vnode->fid.vid, vnode->fid.vnode, page->index);
120
121 if (!PageUptodate(page)) {
122 if (copied < len) {
123 copied = 0;
124 goto out;
125 }
126
127 SetPageUptodate(page);
128 }
129
130 if (copied == 0)
131 goto out;
132
133 maybe_i_size = pos + copied;
134
135 i_size = i_size_read(&vnode->vfs_inode);
136 if (maybe_i_size > i_size) {
137 write_seqlock(&vnode->cb_lock);
138 i_size = i_size_read(&vnode->vfs_inode);
139 if (maybe_i_size > i_size)
140 afs_set_i_size(vnode, maybe_i_size);
141 write_sequnlock(&vnode->cb_lock);
142 }
143
144 if (PagePrivate(page)) {
145 priv = page_private(page);
146 f = afs_page_dirty_from(page, priv);
147 t = afs_page_dirty_to(page, priv);
148 if (from < f)
149 f = from;
150 if (to > t)
151 t = to;
152 priv = afs_page_dirty(page, f, t);
153 set_page_private(page, priv);
154 trace_afs_page_dirty(vnode, tracepoint_string("dirty+"), page);
155 } else {
156 priv = afs_page_dirty(page, from, to);
157 attach_page_private(page, (void *)priv);
158 trace_afs_page_dirty(vnode, tracepoint_string("dirty"), page);
159 }
160
161 if (set_page_dirty(page))
162 _debug("dirtied %lx", page->index);
163
164 out:
165 unlock_page(page);
166 put_page(page);
167 return copied;
168 }
169
170 /*
171 * kill all the pages in the given range
172 */
afs_kill_pages(struct address_space * mapping,loff_t start,loff_t len)173 static void afs_kill_pages(struct address_space *mapping,
174 loff_t start, loff_t len)
175 {
176 struct afs_vnode *vnode = AFS_FS_I(mapping->host);
177 struct pagevec pv;
178 unsigned int loop, psize;
179
180 _enter("{%llx:%llu},%llx @%llx",
181 vnode->fid.vid, vnode->fid.vnode, len, start);
182
183 pagevec_init(&pv);
184
185 do {
186 _debug("kill %llx @%llx", len, start);
187
188 pv.nr = find_get_pages_contig(mapping, start / PAGE_SIZE,
189 PAGEVEC_SIZE, pv.pages);
190 if (pv.nr == 0)
191 break;
192
193 for (loop = 0; loop < pv.nr; loop++) {
194 struct page *page = pv.pages[loop];
195
196 if (page->index * PAGE_SIZE >= start + len)
197 break;
198
199 psize = thp_size(page);
200 start += psize;
201 len -= psize;
202 ClearPageUptodate(page);
203 end_page_writeback(page);
204 lock_page(page);
205 generic_error_remove_page(mapping, page);
206 unlock_page(page);
207 }
208
209 __pagevec_release(&pv);
210 } while (len > 0);
211
212 _leave("");
213 }
214
215 /*
216 * Redirty all the pages in a given range.
217 */
afs_redirty_pages(struct writeback_control * wbc,struct address_space * mapping,loff_t start,loff_t len)218 static void afs_redirty_pages(struct writeback_control *wbc,
219 struct address_space *mapping,
220 loff_t start, loff_t len)
221 {
222 struct afs_vnode *vnode = AFS_FS_I(mapping->host);
223 struct pagevec pv;
224 unsigned int loop, psize;
225
226 _enter("{%llx:%llu},%llx @%llx",
227 vnode->fid.vid, vnode->fid.vnode, len, start);
228
229 pagevec_init(&pv);
230
231 do {
232 _debug("redirty %llx @%llx", len, start);
233
234 pv.nr = find_get_pages_contig(mapping, start / PAGE_SIZE,
235 PAGEVEC_SIZE, pv.pages);
236 if (pv.nr == 0)
237 break;
238
239 for (loop = 0; loop < pv.nr; loop++) {
240 struct page *page = pv.pages[loop];
241
242 if (page->index * PAGE_SIZE >= start + len)
243 break;
244
245 psize = thp_size(page);
246 start += psize;
247 len -= psize;
248 redirty_page_for_writepage(wbc, page);
249 end_page_writeback(page);
250 }
251
252 __pagevec_release(&pv);
253 } while (len > 0);
254
255 _leave("");
256 }
257
258 /*
259 * completion of write to server
260 */
afs_pages_written_back(struct afs_vnode * vnode,loff_t start,unsigned int len)261 static void afs_pages_written_back(struct afs_vnode *vnode, loff_t start, unsigned int len)
262 {
263 struct address_space *mapping = vnode->vfs_inode.i_mapping;
264 struct page *page;
265 pgoff_t end;
266
267 XA_STATE(xas, &mapping->i_pages, start / PAGE_SIZE);
268
269 _enter("{%llx:%llu},{%x @%llx}",
270 vnode->fid.vid, vnode->fid.vnode, len, start);
271
272 rcu_read_lock();
273
274 end = (start + len - 1) / PAGE_SIZE;
275 xas_for_each(&xas, page, end) {
276 if (!PageWriteback(page)) {
277 kdebug("bad %x @%llx page %lx %lx", len, start, page->index, end);
278 ASSERT(PageWriteback(page));
279 }
280
281 trace_afs_page_dirty(vnode, tracepoint_string("clear"), page);
282 detach_page_private(page);
283 page_endio(page, true, 0);
284 }
285
286 rcu_read_unlock();
287
288 afs_prune_wb_keys(vnode);
289 _leave("");
290 }
291
292 /*
293 * Find a key to use for the writeback. We cached the keys used to author the
294 * writes on the vnode. *_wbk will contain the last writeback key used or NULL
295 * and we need to start from there if it's set.
296 */
afs_get_writeback_key(struct afs_vnode * vnode,struct afs_wb_key ** _wbk)297 static int afs_get_writeback_key(struct afs_vnode *vnode,
298 struct afs_wb_key **_wbk)
299 {
300 struct afs_wb_key *wbk = NULL;
301 struct list_head *p;
302 int ret = -ENOKEY, ret2;
303
304 spin_lock(&vnode->wb_lock);
305 if (*_wbk)
306 p = (*_wbk)->vnode_link.next;
307 else
308 p = vnode->wb_keys.next;
309
310 while (p != &vnode->wb_keys) {
311 wbk = list_entry(p, struct afs_wb_key, vnode_link);
312 _debug("wbk %u", key_serial(wbk->key));
313 ret2 = key_validate(wbk->key);
314 if (ret2 == 0) {
315 refcount_inc(&wbk->usage);
316 _debug("USE WB KEY %u", key_serial(wbk->key));
317 break;
318 }
319
320 wbk = NULL;
321 if (ret == -ENOKEY)
322 ret = ret2;
323 p = p->next;
324 }
325
326 spin_unlock(&vnode->wb_lock);
327 if (*_wbk)
328 afs_put_wb_key(*_wbk);
329 *_wbk = wbk;
330 return 0;
331 }
332
afs_store_data_success(struct afs_operation * op)333 static void afs_store_data_success(struct afs_operation *op)
334 {
335 struct afs_vnode *vnode = op->file[0].vnode;
336
337 op->ctime = op->file[0].scb.status.mtime_client;
338 afs_vnode_commit_status(op, &op->file[0]);
339 if (op->error == 0) {
340 if (!op->store.laundering)
341 afs_pages_written_back(vnode, op->store.pos, op->store.size);
342 afs_stat_v(vnode, n_stores);
343 atomic_long_add(op->store.size, &afs_v2net(vnode)->n_store_bytes);
344 }
345 }
346
347 static const struct afs_operation_ops afs_store_data_operation = {
348 .issue_afs_rpc = afs_fs_store_data,
349 .issue_yfs_rpc = yfs_fs_store_data,
350 .success = afs_store_data_success,
351 };
352
353 /*
354 * write to a file
355 */
afs_store_data(struct afs_vnode * vnode,struct iov_iter * iter,loff_t pos,bool laundering)356 static int afs_store_data(struct afs_vnode *vnode, struct iov_iter *iter, loff_t pos,
357 bool laundering)
358 {
359 struct afs_operation *op;
360 struct afs_wb_key *wbk = NULL;
361 loff_t size = iov_iter_count(iter), i_size;
362 int ret = -ENOKEY;
363
364 _enter("%s{%llx:%llu.%u},%llx,%llx",
365 vnode->volume->name,
366 vnode->fid.vid,
367 vnode->fid.vnode,
368 vnode->fid.unique,
369 size, pos);
370
371 ret = afs_get_writeback_key(vnode, &wbk);
372 if (ret) {
373 _leave(" = %d [no keys]", ret);
374 return ret;
375 }
376
377 op = afs_alloc_operation(wbk->key, vnode->volume);
378 if (IS_ERR(op)) {
379 afs_put_wb_key(wbk);
380 return -ENOMEM;
381 }
382
383 i_size = i_size_read(&vnode->vfs_inode);
384
385 afs_op_set_vnode(op, 0, vnode);
386 op->file[0].dv_delta = 1;
387 op->file[0].modification = true;
388 op->store.write_iter = iter;
389 op->store.pos = pos;
390 op->store.size = size;
391 op->store.i_size = max(pos + size, i_size);
392 op->store.laundering = laundering;
393 op->mtime = vnode->vfs_inode.i_mtime;
394 op->flags |= AFS_OPERATION_UNINTR;
395 op->ops = &afs_store_data_operation;
396
397 try_next_key:
398 afs_begin_vnode_operation(op);
399 afs_wait_for_operation(op);
400
401 switch (op->error) {
402 case -EACCES:
403 case -EPERM:
404 case -ENOKEY:
405 case -EKEYEXPIRED:
406 case -EKEYREJECTED:
407 case -EKEYREVOKED:
408 _debug("next");
409
410 ret = afs_get_writeback_key(vnode, &wbk);
411 if (ret == 0) {
412 key_put(op->key);
413 op->key = key_get(wbk->key);
414 goto try_next_key;
415 }
416 break;
417 }
418
419 afs_put_wb_key(wbk);
420 _leave(" = %d", op->error);
421 return afs_put_operation(op);
422 }
423
424 /*
425 * Extend the region to be written back to include subsequent contiguously
426 * dirty pages if possible, but don't sleep while doing so.
427 *
428 * If this page holds new content, then we can include filler zeros in the
429 * writeback.
430 */
afs_extend_writeback(struct address_space * mapping,struct afs_vnode * vnode,long * _count,loff_t start,loff_t max_len,bool new_content,unsigned int * _len)431 static void afs_extend_writeback(struct address_space *mapping,
432 struct afs_vnode *vnode,
433 long *_count,
434 loff_t start,
435 loff_t max_len,
436 bool new_content,
437 unsigned int *_len)
438 {
439 struct pagevec pvec;
440 struct page *page;
441 unsigned long priv;
442 unsigned int psize, filler = 0;
443 unsigned int f, t;
444 loff_t len = *_len;
445 pgoff_t index = (start + len) / PAGE_SIZE;
446 bool stop = true;
447 unsigned int i;
448
449 XA_STATE(xas, &mapping->i_pages, index);
450 pagevec_init(&pvec);
451
452 do {
453 /* Firstly, we gather up a batch of contiguous dirty pages
454 * under the RCU read lock - but we can't clear the dirty flags
455 * there if any of those pages are mapped.
456 */
457 rcu_read_lock();
458
459 xas_for_each(&xas, page, ULONG_MAX) {
460 stop = true;
461 if (xas_retry(&xas, page))
462 continue;
463 if (xa_is_value(page))
464 break;
465 if (page->index != index)
466 break;
467
468 if (!page_cache_get_speculative(page)) {
469 xas_reset(&xas);
470 continue;
471 }
472
473 /* Has the page moved or been split? */
474 if (unlikely(page != xas_reload(&xas))) {
475 put_page(page);
476 break;
477 }
478
479 if (!trylock_page(page)) {
480 put_page(page);
481 break;
482 }
483 if (!PageDirty(page) || PageWriteback(page)) {
484 unlock_page(page);
485 put_page(page);
486 break;
487 }
488
489 psize = thp_size(page);
490 priv = page_private(page);
491 f = afs_page_dirty_from(page, priv);
492 t = afs_page_dirty_to(page, priv);
493 if (f != 0 && !new_content) {
494 unlock_page(page);
495 put_page(page);
496 break;
497 }
498
499 len += filler + t;
500 filler = psize - t;
501 if (len >= max_len || *_count <= 0)
502 stop = true;
503 else if (t == psize || new_content)
504 stop = false;
505
506 index += thp_nr_pages(page);
507 if (!pagevec_add(&pvec, page))
508 break;
509 if (stop)
510 break;
511 }
512
513 if (!stop)
514 xas_pause(&xas);
515 rcu_read_unlock();
516
517 /* Now, if we obtained any pages, we can shift them to being
518 * writable and mark them for caching.
519 */
520 if (!pagevec_count(&pvec))
521 break;
522
523 for (i = 0; i < pagevec_count(&pvec); i++) {
524 page = pvec.pages[i];
525 trace_afs_page_dirty(vnode, tracepoint_string("store+"), page);
526
527 if (!clear_page_dirty_for_io(page))
528 BUG();
529 if (test_set_page_writeback(page))
530 BUG();
531
532 *_count -= thp_nr_pages(page);
533 unlock_page(page);
534 }
535
536 pagevec_release(&pvec);
537 cond_resched();
538 } while (!stop);
539
540 *_len = len;
541 }
542
543 /*
544 * Synchronously write back the locked page and any subsequent non-locked dirty
545 * pages.
546 */
afs_write_back_from_locked_page(struct address_space * mapping,struct writeback_control * wbc,struct page * page,loff_t start,loff_t end)547 static ssize_t afs_write_back_from_locked_page(struct address_space *mapping,
548 struct writeback_control *wbc,
549 struct page *page,
550 loff_t start, loff_t end)
551 {
552 struct afs_vnode *vnode = AFS_FS_I(mapping->host);
553 struct iov_iter iter;
554 unsigned long priv;
555 unsigned int offset, to, len, max_len;
556 loff_t i_size = i_size_read(&vnode->vfs_inode);
557 bool new_content = test_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags);
558 long count = wbc->nr_to_write;
559 int ret;
560
561 _enter(",%lx,%llx-%llx", page->index, start, end);
562
563 if (test_set_page_writeback(page))
564 BUG();
565
566 count -= thp_nr_pages(page);
567
568 /* Find all consecutive lockable dirty pages that have contiguous
569 * written regions, stopping when we find a page that is not
570 * immediately lockable, is not dirty or is missing, or we reach the
571 * end of the range.
572 */
573 priv = page_private(page);
574 offset = afs_page_dirty_from(page, priv);
575 to = afs_page_dirty_to(page, priv);
576 trace_afs_page_dirty(vnode, tracepoint_string("store"), page);
577
578 len = to - offset;
579 start += offset;
580 if (start < i_size) {
581 /* Trim the write to the EOF; the extra data is ignored. Also
582 * put an upper limit on the size of a single storedata op.
583 */
584 max_len = 65536 * 4096;
585 max_len = min_t(unsigned long long, max_len, end - start + 1);
586 max_len = min_t(unsigned long long, max_len, i_size - start);
587
588 if (len < max_len &&
589 (to == thp_size(page) || new_content))
590 afs_extend_writeback(mapping, vnode, &count,
591 start, max_len, new_content, &len);
592 len = min_t(loff_t, len, max_len);
593 }
594
595 /* We now have a contiguous set of dirty pages, each with writeback
596 * set; the first page is still locked at this point, but all the rest
597 * have been unlocked.
598 */
599 unlock_page(page);
600
601 if (start < i_size) {
602 _debug("write back %x @%llx [%llx]", len, start, i_size);
603
604 iov_iter_xarray(&iter, WRITE, &mapping->i_pages, start, len);
605 ret = afs_store_data(vnode, &iter, start, false);
606 } else {
607 _debug("write discard %x @%llx [%llx]", len, start, i_size);
608
609 /* The dirty region was entirely beyond the EOF. */
610 afs_pages_written_back(vnode, start, len);
611 ret = 0;
612 }
613
614 switch (ret) {
615 case 0:
616 wbc->nr_to_write = count;
617 ret = len;
618 break;
619
620 default:
621 pr_notice("kAFS: Unexpected error from FS.StoreData %d\n", ret);
622 fallthrough;
623 case -EACCES:
624 case -EPERM:
625 case -ENOKEY:
626 case -EKEYEXPIRED:
627 case -EKEYREJECTED:
628 case -EKEYREVOKED:
629 case -ENETRESET:
630 afs_redirty_pages(wbc, mapping, start, len);
631 mapping_set_error(mapping, ret);
632 break;
633
634 case -EDQUOT:
635 case -ENOSPC:
636 afs_redirty_pages(wbc, mapping, start, len);
637 mapping_set_error(mapping, -ENOSPC);
638 break;
639
640 case -EROFS:
641 case -EIO:
642 case -EREMOTEIO:
643 case -EFBIG:
644 case -ENOENT:
645 case -ENOMEDIUM:
646 case -ENXIO:
647 trace_afs_file_error(vnode, ret, afs_file_error_writeback_fail);
648 afs_kill_pages(mapping, start, len);
649 mapping_set_error(mapping, ret);
650 break;
651 }
652
653 _leave(" = %d", ret);
654 return ret;
655 }
656
657 /*
658 * write a page back to the server
659 * - the caller locked the page for us
660 */
afs_writepage(struct page * page,struct writeback_control * wbc)661 int afs_writepage(struct page *page, struct writeback_control *wbc)
662 {
663 ssize_t ret;
664 loff_t start;
665
666 _enter("{%lx},", page->index);
667
668 start = page->index * PAGE_SIZE;
669 ret = afs_write_back_from_locked_page(page->mapping, wbc, page,
670 start, LLONG_MAX - start);
671 if (ret < 0) {
672 _leave(" = %zd", ret);
673 return ret;
674 }
675
676 _leave(" = 0");
677 return 0;
678 }
679
680 /*
681 * write a region of pages back to the server
682 */
afs_writepages_region(struct address_space * mapping,struct writeback_control * wbc,loff_t start,loff_t end,loff_t * _next)683 static int afs_writepages_region(struct address_space *mapping,
684 struct writeback_control *wbc,
685 loff_t start, loff_t end, loff_t *_next)
686 {
687 struct page *page;
688 ssize_t ret;
689 int n;
690
691 _enter("%llx,%llx,", start, end);
692
693 do {
694 pgoff_t index = start / PAGE_SIZE;
695
696 n = find_get_pages_range_tag(mapping, &index, end / PAGE_SIZE,
697 PAGECACHE_TAG_DIRTY, 1, &page);
698 if (!n)
699 break;
700
701 start = (loff_t)page->index * PAGE_SIZE; /* May regress with THPs */
702
703 _debug("wback %lx", page->index);
704
705 /* At this point we hold neither the i_pages lock nor the
706 * page lock: the page may be truncated or invalidated
707 * (changing page->mapping to NULL), or even swizzled
708 * back from swapper_space to tmpfs file mapping
709 */
710 if (wbc->sync_mode != WB_SYNC_NONE) {
711 ret = lock_page_killable(page);
712 if (ret < 0) {
713 put_page(page);
714 return ret;
715 }
716 } else {
717 if (!trylock_page(page)) {
718 put_page(page);
719 return 0;
720 }
721 }
722
723 if (page->mapping != mapping || !PageDirty(page)) {
724 start += thp_size(page);
725 unlock_page(page);
726 put_page(page);
727 continue;
728 }
729
730 if (PageWriteback(page)) {
731 unlock_page(page);
732 if (wbc->sync_mode != WB_SYNC_NONE)
733 wait_on_page_writeback(page);
734 put_page(page);
735 continue;
736 }
737
738 if (!clear_page_dirty_for_io(page))
739 BUG();
740 ret = afs_write_back_from_locked_page(mapping, wbc, page, start, end);
741 put_page(page);
742 if (ret < 0) {
743 _leave(" = %zd", ret);
744 return ret;
745 }
746
747 start += ret;
748
749 cond_resched();
750 } while (wbc->nr_to_write > 0);
751
752 *_next = start;
753 _leave(" = 0 [%llx]", *_next);
754 return 0;
755 }
756
757 /*
758 * write some of the pending data back to the server
759 */
afs_writepages(struct address_space * mapping,struct writeback_control * wbc)760 int afs_writepages(struct address_space *mapping,
761 struct writeback_control *wbc)
762 {
763 struct afs_vnode *vnode = AFS_FS_I(mapping->host);
764 loff_t start, next;
765 int ret;
766
767 _enter("");
768
769 /* We have to be careful as we can end up racing with setattr()
770 * truncating the pagecache since the caller doesn't take a lock here
771 * to prevent it.
772 */
773 if (wbc->sync_mode == WB_SYNC_ALL)
774 down_read(&vnode->validate_lock);
775 else if (!down_read_trylock(&vnode->validate_lock))
776 return 0;
777
778 if (wbc->range_cyclic) {
779 start = mapping->writeback_index * PAGE_SIZE;
780 ret = afs_writepages_region(mapping, wbc, start, LLONG_MAX, &next);
781 if (ret == 0) {
782 mapping->writeback_index = next / PAGE_SIZE;
783 if (start > 0 && wbc->nr_to_write > 0) {
784 ret = afs_writepages_region(mapping, wbc, 0,
785 start, &next);
786 if (ret == 0)
787 mapping->writeback_index =
788 next / PAGE_SIZE;
789 }
790 }
791 } else if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) {
792 ret = afs_writepages_region(mapping, wbc, 0, LLONG_MAX, &next);
793 if (wbc->nr_to_write > 0 && ret == 0)
794 mapping->writeback_index = next / PAGE_SIZE;
795 } else {
796 ret = afs_writepages_region(mapping, wbc,
797 wbc->range_start, wbc->range_end, &next);
798 }
799
800 up_read(&vnode->validate_lock);
801 _leave(" = %d", ret);
802 return ret;
803 }
804
805 /*
806 * write to an AFS file
807 */
afs_file_write(struct kiocb * iocb,struct iov_iter * from)808 ssize_t afs_file_write(struct kiocb *iocb, struct iov_iter *from)
809 {
810 struct afs_vnode *vnode = AFS_FS_I(file_inode(iocb->ki_filp));
811 struct afs_file *af = iocb->ki_filp->private_data;
812 ssize_t result;
813 size_t count = iov_iter_count(from);
814
815 _enter("{%llx:%llu},{%zu},",
816 vnode->fid.vid, vnode->fid.vnode, count);
817
818 if (IS_SWAPFILE(&vnode->vfs_inode)) {
819 printk(KERN_INFO
820 "AFS: Attempt to write to active swap file!\n");
821 return -EBUSY;
822 }
823
824 if (!count)
825 return 0;
826
827 result = afs_validate(vnode, af->key);
828 if (result < 0)
829 return result;
830
831 result = generic_file_write_iter(iocb, from);
832
833 _leave(" = %zd", result);
834 return result;
835 }
836
837 /*
838 * flush any dirty pages for this process, and check for write errors.
839 * - the return status from this call provides a reliable indication of
840 * whether any write errors occurred for this process.
841 */
afs_fsync(struct file * file,loff_t start,loff_t end,int datasync)842 int afs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
843 {
844 struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
845 struct afs_file *af = file->private_data;
846 int ret;
847
848 _enter("{%llx:%llu},{n=%pD},%d",
849 vnode->fid.vid, vnode->fid.vnode, file,
850 datasync);
851
852 ret = afs_validate(vnode, af->key);
853 if (ret < 0)
854 return ret;
855
856 return file_write_and_wait_range(file, start, end);
857 }
858
859 /*
860 * notification that a previously read-only page is about to become writable
861 * - if it returns an error, the caller will deliver a bus error signal
862 */
afs_page_mkwrite(struct vm_fault * vmf)863 vm_fault_t afs_page_mkwrite(struct vm_fault *vmf)
864 {
865 struct page *page = thp_head(vmf->page);
866 struct file *file = vmf->vma->vm_file;
867 struct inode *inode = file_inode(file);
868 struct afs_vnode *vnode = AFS_FS_I(inode);
869 struct afs_file *af = file->private_data;
870 unsigned long priv;
871 vm_fault_t ret = VM_FAULT_RETRY;
872
873 _enter("{{%llx:%llu}},{%lx}", vnode->fid.vid, vnode->fid.vnode, page->index);
874
875 afs_validate(vnode, af->key);
876
877 sb_start_pagefault(inode->i_sb);
878
879 /* Wait for the page to be written to the cache before we allow it to
880 * be modified. We then assume the entire page will need writing back.
881 */
882 #ifdef CONFIG_AFS_FSCACHE
883 if (PageFsCache(page) &&
884 wait_on_page_fscache_killable(page) < 0)
885 goto out;
886 #endif
887
888 if (wait_on_page_writeback_killable(page))
889 goto out;
890
891 if (lock_page_killable(page) < 0)
892 goto out;
893
894 /* We mustn't change page->private until writeback is complete as that
895 * details the portion of the page we need to write back and we might
896 * need to redirty the page if there's a problem.
897 */
898 if (wait_on_page_writeback_killable(page) < 0) {
899 unlock_page(page);
900 goto out;
901 }
902
903 priv = afs_page_dirty(page, 0, thp_size(page));
904 priv = afs_page_dirty_mmapped(priv);
905 if (PagePrivate(page)) {
906 set_page_private(page, priv);
907 trace_afs_page_dirty(vnode, tracepoint_string("mkwrite+"), page);
908 } else {
909 attach_page_private(page, (void *)priv);
910 trace_afs_page_dirty(vnode, tracepoint_string("mkwrite"), page);
911 }
912 file_update_time(file);
913
914 ret = VM_FAULT_LOCKED;
915 out:
916 sb_end_pagefault(inode->i_sb);
917 return ret;
918 }
919
920 /*
921 * Prune the keys cached for writeback. The caller must hold vnode->wb_lock.
922 */
afs_prune_wb_keys(struct afs_vnode * vnode)923 void afs_prune_wb_keys(struct afs_vnode *vnode)
924 {
925 LIST_HEAD(graveyard);
926 struct afs_wb_key *wbk, *tmp;
927
928 /* Discard unused keys */
929 spin_lock(&vnode->wb_lock);
930
931 if (!mapping_tagged(&vnode->vfs_inode.i_data, PAGECACHE_TAG_WRITEBACK) &&
932 !mapping_tagged(&vnode->vfs_inode.i_data, PAGECACHE_TAG_DIRTY)) {
933 list_for_each_entry_safe(wbk, tmp, &vnode->wb_keys, vnode_link) {
934 if (refcount_read(&wbk->usage) == 1)
935 list_move(&wbk->vnode_link, &graveyard);
936 }
937 }
938
939 spin_unlock(&vnode->wb_lock);
940
941 while (!list_empty(&graveyard)) {
942 wbk = list_entry(graveyard.next, struct afs_wb_key, vnode_link);
943 list_del(&wbk->vnode_link);
944 afs_put_wb_key(wbk);
945 }
946 }
947
948 /*
949 * Clean up a page during invalidation.
950 */
afs_launder_page(struct page * page)951 int afs_launder_page(struct page *page)
952 {
953 struct address_space *mapping = page->mapping;
954 struct afs_vnode *vnode = AFS_FS_I(mapping->host);
955 struct iov_iter iter;
956 struct bio_vec bv[1];
957 unsigned long priv;
958 unsigned int f, t;
959 int ret = 0;
960
961 _enter("{%lx}", page->index);
962
963 priv = page_private(page);
964 if (clear_page_dirty_for_io(page)) {
965 f = 0;
966 t = thp_size(page);
967 if (PagePrivate(page)) {
968 f = afs_page_dirty_from(page, priv);
969 t = afs_page_dirty_to(page, priv);
970 }
971
972 bv[0].bv_page = page;
973 bv[0].bv_offset = f;
974 bv[0].bv_len = t - f;
975 iov_iter_bvec(&iter, WRITE, bv, 1, bv[0].bv_len);
976
977 trace_afs_page_dirty(vnode, tracepoint_string("launder"), page);
978 ret = afs_store_data(vnode, &iter, page_offset(page) + f, true);
979 }
980
981 trace_afs_page_dirty(vnode, tracepoint_string("laundered"), page);
982 detach_page_private(page);
983 wait_on_page_fscache(page);
984 return ret;
985 }
986