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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * mm/truncate.c - code for taking down pages from address_spaces
4 *
5 * Copyright (C) 2002, Linus Torvalds
6 *
7 * 10Sep2002 Andrew Morton
8 * Initial version.
9 */
10
11#include <linux/kernel.h>
12#include <linux/backing-dev.h>
13#include <linux/dax.h>
14#include <linux/gfp.h>
15#include <linux/mm.h>
16#include <linux/swap.h>
17#include <linux/export.h>
18#include <linux/pagemap.h>
19#include <linux/highmem.h>
20#include <linux/pagevec.h>
21#include <linux/task_io_accounting_ops.h>
22#include <linux/buffer_head.h> /* grr. try_to_release_page */
23#include <linux/shmem_fs.h>
24#include <linux/rmap.h>
25#include "internal.h"
26
27/*
28 * Regular page slots are stabilized by the page lock even without the tree
29 * itself locked. These unlocked entries need verification under the tree
30 * lock.
31 */
32static inline void __clear_shadow_entry(struct address_space *mapping,
33 pgoff_t index, void *entry)
34{
35 XA_STATE(xas, &mapping->i_pages, index);
36
37 xas_set_update(&xas, workingset_update_node);
38 if (xas_load(&xas) != entry)
39 return;
40 xas_store(&xas, NULL);
41}
42
43static void clear_shadow_entry(struct address_space *mapping, pgoff_t index,
44 void *entry)
45{
46 spin_lock(&mapping->host->i_lock);
47 xa_lock_irq(&mapping->i_pages);
48 __clear_shadow_entry(mapping, index, entry);
49 xa_unlock_irq(&mapping->i_pages);
50 if (mapping_shrinkable(mapping))
51 inode_add_lru(mapping->host);
52 spin_unlock(&mapping->host->i_lock);
53}
54
55/*
56 * Unconditionally remove exceptional entries. Usually called from truncate
57 * path. Note that the folio_batch may be altered by this function by removing
58 * exceptional entries similar to what folio_batch_remove_exceptionals() does.
59 */
60static void truncate_folio_batch_exceptionals(struct address_space *mapping,
61 struct folio_batch *fbatch, pgoff_t *indices)
62{
63 int i, j;
64 bool dax;
65
66 /* Handled by shmem itself */
67 if (shmem_mapping(mapping))
68 return;
69
70 for (j = 0; j < folio_batch_count(fbatch); j++)
71 if (xa_is_value(fbatch->folios[j]))
72 break;
73
74 if (j == folio_batch_count(fbatch))
75 return;
76
77 dax = dax_mapping(mapping);
78 if (!dax) {
79 spin_lock(&mapping->host->i_lock);
80 xa_lock_irq(&mapping->i_pages);
81 }
82
83 for (i = j; i < folio_batch_count(fbatch); i++) {
84 struct folio *folio = fbatch->folios[i];
85 pgoff_t index = indices[i];
86
87 if (!xa_is_value(folio)) {
88 fbatch->folios[j++] = folio;
89 continue;
90 }
91
92 if (unlikely(dax)) {
93 dax_delete_mapping_entry(mapping, index);
94 continue;
95 }
96
97 __clear_shadow_entry(mapping, index, folio);
98 }
99
100 if (!dax) {
101 xa_unlock_irq(&mapping->i_pages);
102 if (mapping_shrinkable(mapping))
103 inode_add_lru(mapping->host);
104 spin_unlock(&mapping->host->i_lock);
105 }
106 fbatch->nr = j;
107}
108
109/*
110 * Invalidate exceptional entry if easily possible. This handles exceptional
111 * entries for invalidate_inode_pages().
112 */
113static int invalidate_exceptional_entry(struct address_space *mapping,
114 pgoff_t index, void *entry)
115{
116 /* Handled by shmem itself, or for DAX we do nothing. */
117 if (shmem_mapping(mapping) || dax_mapping(mapping))
118 return 1;
119 clear_shadow_entry(mapping, index, entry);
120 return 1;
121}
122
123/*
124 * Invalidate exceptional entry if clean. This handles exceptional entries for
125 * invalidate_inode_pages2() so for DAX it evicts only clean entries.
126 */
127static int invalidate_exceptional_entry2(struct address_space *mapping,
128 pgoff_t index, void *entry)
129{
130 /* Handled by shmem itself */
131 if (shmem_mapping(mapping))
132 return 1;
133 if (dax_mapping(mapping))
134 return dax_invalidate_mapping_entry_sync(mapping, index);
135 clear_shadow_entry(mapping, index, entry);
136 return 1;
137}
138
139/**
140 * folio_invalidate - Invalidate part or all of a folio.
141 * @folio: The folio which is affected.
142 * @offset: start of the range to invalidate
143 * @length: length of the range to invalidate
144 *
145 * folio_invalidate() is called when all or part of the folio has become
146 * invalidated by a truncate operation.
147 *
148 * folio_invalidate() does not have to release all buffers, but it must
149 * ensure that no dirty buffer is left outside @offset and that no I/O
150 * is underway against any of the blocks which are outside the truncation
151 * point. Because the caller is about to free (and possibly reuse) those
152 * blocks on-disk.
153 */
154void folio_invalidate(struct folio *folio, size_t offset, size_t length)
155{
156 const struct address_space_operations *aops = folio->mapping->a_ops;
157
158 if (aops->invalidate_folio)
159 aops->invalidate_folio(folio, offset, length);
160}
161EXPORT_SYMBOL_GPL(folio_invalidate);
162
163/*
164 * If truncate cannot remove the fs-private metadata from the page, the page
165 * becomes orphaned. It will be left on the LRU and may even be mapped into
166 * user pagetables if we're racing with filemap_fault().
167 *
168 * We need to bail out if page->mapping is no longer equal to the original
169 * mapping. This happens a) when the VM reclaimed the page while we waited on
170 * its lock, b) when a concurrent invalidate_mapping_pages got there first and
171 * c) when tmpfs swizzles a page between a tmpfs inode and swapper_space.
172 */
173static void truncate_cleanup_folio(struct folio *folio)
174{
175 if (folio_mapped(folio))
176 unmap_mapping_folio(folio);
177
178 if (folio_has_private(folio))
179 folio_invalidate(folio, 0, folio_size(folio));
180
181 /*
182 * Some filesystems seem to re-dirty the page even after
183 * the VM has canceled the dirty bit (eg ext3 journaling).
184 * Hence dirty accounting check is placed after invalidation.
185 */
186 folio_cancel_dirty(folio);
187 folio_clear_mappedtodisk(folio);
188}
189
190int truncate_inode_folio(struct address_space *mapping, struct folio *folio)
191{
192 if (folio->mapping != mapping)
193 return -EIO;
194
195 truncate_cleanup_folio(folio);
196 filemap_remove_folio(folio);
197 return 0;
198}
199
200/*
201 * Handle partial folios. The folio may be entirely within the
202 * range if a split has raced with us. If not, we zero the part of the
203 * folio that's within the [start, end] range, and then split the folio if
204 * it's large. split_page_range() will discard pages which now lie beyond
205 * i_size, and we rely on the caller to discard pages which lie within a
206 * newly created hole.
207 *
208 * Returns false if splitting failed so the caller can avoid
209 * discarding the entire folio which is stubbornly unsplit.
210 */
211bool truncate_inode_partial_folio(struct folio *folio, loff_t start, loff_t end)
212{
213 loff_t pos = folio_pos(folio);
214 unsigned int offset, length;
215
216 if (pos < start)
217 offset = start - pos;
218 else
219 offset = 0;
220 length = folio_size(folio);
221 if (pos + length <= (u64)end)
222 length = length - offset;
223 else
224 length = end + 1 - pos - offset;
225
226 folio_wait_writeback(folio);
227 if (length == folio_size(folio)) {
228 truncate_inode_folio(folio->mapping, folio);
229 return true;
230 }
231
232 /*
233 * We may be zeroing pages we're about to discard, but it avoids
234 * doing a complex calculation here, and then doing the zeroing
235 * anyway if the page split fails.
236 */
237 folio_zero_range(folio, offset, length);
238
239 if (folio_has_private(folio))
240 folio_invalidate(folio, offset, length);
241 if (!folio_test_large(folio))
242 return true;
243 if (split_folio(folio) == 0)
244 return true;
245 if (folio_test_dirty(folio))
246 return false;
247 truncate_inode_folio(folio->mapping, folio);
248 return true;
249}
250
251/*
252 * Used to get rid of pages on hardware memory corruption.
253 */
254int generic_error_remove_page(struct address_space *mapping, struct page *page)
255{
256 VM_BUG_ON_PAGE(PageTail(page), page);
257
258 if (!mapping)
259 return -EINVAL;
260 /*
261 * Only punch for normal data pages for now.
262 * Handling other types like directories would need more auditing.
263 */
264 if (!S_ISREG(mapping->host->i_mode))
265 return -EIO;
266 return truncate_inode_folio(mapping, page_folio(page));
267}
268EXPORT_SYMBOL(generic_error_remove_page);
269
270static long mapping_evict_folio(struct address_space *mapping,
271 struct folio *folio)
272{
273 if (folio_test_dirty(folio) || folio_test_writeback(folio))
274 return 0;
275 /* The refcount will be elevated if any page in the folio is mapped */
276 if (folio_ref_count(folio) >
277 folio_nr_pages(folio) + folio_has_private(folio) + 1)
278 return 0;
279 if (folio_has_private(folio) && !filemap_release_folio(folio, 0))
280 return 0;
281
282 return remove_mapping(mapping, folio);
283}
284
285/**
286 * invalidate_inode_page() - Remove an unused page from the pagecache.
287 * @page: The page to remove.
288 *
289 * Safely invalidate one page from its pagecache mapping.
290 * It only drops clean, unused pages.
291 *
292 * Context: Page must be locked.
293 * Return: The number of pages successfully removed.
294 */
295long invalidate_inode_page(struct page *page)
296{
297 struct folio *folio = page_folio(page);
298 struct address_space *mapping = folio_mapping(folio);
299
300 /* The page may have been truncated before it was locked */
301 if (!mapping)
302 return 0;
303 return mapping_evict_folio(mapping, folio);
304}
305
306/**
307 * truncate_inode_pages_range - truncate range of pages specified by start & end byte offsets
308 * @mapping: mapping to truncate
309 * @lstart: offset from which to truncate
310 * @lend: offset to which to truncate (inclusive)
311 *
312 * Truncate the page cache, removing the pages that are between
313 * specified offsets (and zeroing out partial pages
314 * if lstart or lend + 1 is not page aligned).
315 *
316 * Truncate takes two passes - the first pass is nonblocking. It will not
317 * block on page locks and it will not block on writeback. The second pass
318 * will wait. This is to prevent as much IO as possible in the affected region.
319 * The first pass will remove most pages, so the search cost of the second pass
320 * is low.
321 *
322 * We pass down the cache-hot hint to the page freeing code. Even if the
323 * mapping is large, it is probably the case that the final pages are the most
324 * recently touched, and freeing happens in ascending file offset order.
325 *
326 * Note that since ->invalidate_folio() accepts range to invalidate
327 * truncate_inode_pages_range is able to handle cases where lend + 1 is not
328 * page aligned properly.
329 */
330void truncate_inode_pages_range(struct address_space *mapping,
331 loff_t lstart, loff_t lend)
332{
333 pgoff_t start; /* inclusive */
334 pgoff_t end; /* exclusive */
335 struct folio_batch fbatch;
336 pgoff_t indices[PAGEVEC_SIZE];
337 pgoff_t index;
338 int i;
339 struct folio *folio;
340 bool same_folio;
341
342 if (mapping_empty(mapping))
343 return;
344
345 /*
346 * 'start' and 'end' always covers the range of pages to be fully
347 * truncated. Partial pages are covered with 'partial_start' at the
348 * start of the range and 'partial_end' at the end of the range.
349 * Note that 'end' is exclusive while 'lend' is inclusive.
350 */
351 start = (lstart + PAGE_SIZE - 1) >> PAGE_SHIFT;
352 if (lend == -1)
353 /*
354 * lend == -1 indicates end-of-file so we have to set 'end'
355 * to the highest possible pgoff_t and since the type is
356 * unsigned we're using -1.
357 */
358 end = -1;
359 else
360 end = (lend + 1) >> PAGE_SHIFT;
361
362 folio_batch_init(&fbatch);
363 index = start;
364 while (index < end && find_lock_entries(mapping, &index, end - 1,
365 &fbatch, indices)) {
366 truncate_folio_batch_exceptionals(mapping, &fbatch, indices);
367 for (i = 0; i < folio_batch_count(&fbatch); i++)
368 truncate_cleanup_folio(fbatch.folios[i]);
369 delete_from_page_cache_batch(mapping, &fbatch);
370 for (i = 0; i < folio_batch_count(&fbatch); i++)
371 folio_unlock(fbatch.folios[i]);
372 folio_batch_release(&fbatch);
373 cond_resched();
374 }
375
376 same_folio = (lstart >> PAGE_SHIFT) == (lend >> PAGE_SHIFT);
377 folio = __filemap_get_folio(mapping, lstart >> PAGE_SHIFT, FGP_LOCK, 0);
378 if (folio) {
379 same_folio = lend < folio_pos(folio) + folio_size(folio);
380 if (!truncate_inode_partial_folio(folio, lstart, lend)) {
381 start = folio->index + folio_nr_pages(folio);
382 if (same_folio)
383 end = folio->index;
384 }
385 folio_unlock(folio);
386 folio_put(folio);
387 folio = NULL;
388 }
389
390 if (!same_folio)
391 folio = __filemap_get_folio(mapping, lend >> PAGE_SHIFT,
392 FGP_LOCK, 0);
393 if (folio) {
394 if (!truncate_inode_partial_folio(folio, lstart, lend))
395 end = folio->index;
396 folio_unlock(folio);
397 folio_put(folio);
398 }
399
400 index = start;
401 while (index < end) {
402 cond_resched();
403 if (!find_get_entries(mapping, &index, end - 1, &fbatch,
404 indices)) {
405 /* If all gone from start onwards, we're done */
406 if (index == start)
407 break;
408 /* Otherwise restart to make sure all gone */
409 index = start;
410 continue;
411 }
412
413 for (i = 0; i < folio_batch_count(&fbatch); i++) {
414 struct folio *folio = fbatch.folios[i];
415
416 /* We rely upon deletion not changing page->index */
417
418 if (xa_is_value(folio))
419 continue;
420
421 folio_lock(folio);
422 VM_BUG_ON_FOLIO(!folio_contains(folio, indices[i]), folio);
423 folio_wait_writeback(folio);
424 truncate_inode_folio(mapping, folio);
425 folio_unlock(folio);
426 }
427 truncate_folio_batch_exceptionals(mapping, &fbatch, indices);
428 folio_batch_release(&fbatch);
429 }
430}
431EXPORT_SYMBOL(truncate_inode_pages_range);
432
433/**
434 * truncate_inode_pages - truncate *all* the pages from an offset
435 * @mapping: mapping to truncate
436 * @lstart: offset from which to truncate
437 *
438 * Called under (and serialised by) inode->i_rwsem and
439 * mapping->invalidate_lock.
440 *
441 * Note: When this function returns, there can be a page in the process of
442 * deletion (inside __filemap_remove_folio()) in the specified range. Thus
443 * mapping->nrpages can be non-zero when this function returns even after
444 * truncation of the whole mapping.
445 */
446void truncate_inode_pages(struct address_space *mapping, loff_t lstart)
447{
448 truncate_inode_pages_range(mapping, lstart, (loff_t)-1);
449}
450EXPORT_SYMBOL(truncate_inode_pages);
451
452/**
453 * truncate_inode_pages_final - truncate *all* pages before inode dies
454 * @mapping: mapping to truncate
455 *
456 * Called under (and serialized by) inode->i_rwsem.
457 *
458 * Filesystems have to use this in the .evict_inode path to inform the
459 * VM that this is the final truncate and the inode is going away.
460 */
461void truncate_inode_pages_final(struct address_space *mapping)
462{
463 /*
464 * Page reclaim can not participate in regular inode lifetime
465 * management (can't call iput()) and thus can race with the
466 * inode teardown. Tell it when the address space is exiting,
467 * so that it does not install eviction information after the
468 * final truncate has begun.
469 */
470 mapping_set_exiting(mapping);
471
472 if (!mapping_empty(mapping)) {
473 /*
474 * As truncation uses a lockless tree lookup, cycle
475 * the tree lock to make sure any ongoing tree
476 * modification that does not see AS_EXITING is
477 * completed before starting the final truncate.
478 */
479 xa_lock_irq(&mapping->i_pages);
480 xa_unlock_irq(&mapping->i_pages);
481 }
482
483 truncate_inode_pages(mapping, 0);
484}
485EXPORT_SYMBOL(truncate_inode_pages_final);
486
487/**
488 * invalidate_mapping_pagevec - Invalidate all the unlocked pages of one inode
489 * @mapping: the address_space which holds the pages to invalidate
490 * @start: the offset 'from' which to invalidate
491 * @end: the offset 'to' which to invalidate (inclusive)
492 * @nr_pagevec: invalidate failed page number for caller
493 *
494 * This helper is similar to invalidate_mapping_pages(), except that it accounts
495 * for pages that are likely on a pagevec and counts them in @nr_pagevec, which
496 * will be used by the caller.
497 */
498unsigned long invalidate_mapping_pagevec(struct address_space *mapping,
499 pgoff_t start, pgoff_t end, unsigned long *nr_pagevec)
500{
501 pgoff_t indices[PAGEVEC_SIZE];
502 struct folio_batch fbatch;
503 pgoff_t index = start;
504 unsigned long ret;
505 unsigned long count = 0;
506 int i;
507
508 folio_batch_init(&fbatch);
509 while (find_lock_entries(mapping, &index, end, &fbatch, indices)) {
510 for (i = 0; i < folio_batch_count(&fbatch); i++) {
511 struct folio *folio = fbatch.folios[i];
512
513 /* We rely upon deletion not changing folio->index */
514
515 if (xa_is_value(folio)) {
516 count += invalidate_exceptional_entry(mapping,
517 indices[i], folio);
518 continue;
519 }
520
521 ret = mapping_evict_folio(mapping, folio);
522 folio_unlock(folio);
523 /*
524 * Invalidation is a hint that the folio is no longer
525 * of interest and try to speed up its reclaim.
526 */
527 if (!ret) {
528 deactivate_file_folio(folio);
529 /* It is likely on the pagevec of a remote CPU */
530 if (nr_pagevec)
531 (*nr_pagevec)++;
532 }
533 count += ret;
534 }
535 folio_batch_remove_exceptionals(&fbatch);
536 folio_batch_release(&fbatch);
537 cond_resched();
538 }
539 return count;
540}
541
542/**
543 * invalidate_mapping_pages - Invalidate all clean, unlocked cache of one inode
544 * @mapping: the address_space which holds the cache to invalidate
545 * @start: the offset 'from' which to invalidate
546 * @end: the offset 'to' which to invalidate (inclusive)
547 *
548 * This function removes pages that are clean, unmapped and unlocked,
549 * as well as shadow entries. It will not block on IO activity.
550 *
551 * If you want to remove all the pages of one inode, regardless of
552 * their use and writeback state, use truncate_inode_pages().
553 *
554 * Return: the number of the cache entries that were invalidated
555 */
556unsigned long invalidate_mapping_pages(struct address_space *mapping,
557 pgoff_t start, pgoff_t end)
558{
559 return invalidate_mapping_pagevec(mapping, start, end, NULL);
560}
561EXPORT_SYMBOL(invalidate_mapping_pages);
562
563/*
564 * This is like invalidate_inode_page(), except it ignores the page's
565 * refcount. We do this because invalidate_inode_pages2() needs stronger
566 * invalidation guarantees, and cannot afford to leave pages behind because
567 * shrink_page_list() has a temp ref on them, or because they're transiently
568 * sitting in the folio_add_lru() pagevecs.
569 */
570static int invalidate_complete_folio2(struct address_space *mapping,
571 struct folio *folio)
572{
573 if (folio->mapping != mapping)
574 return 0;
575
576 if (folio_has_private(folio) &&
577 !filemap_release_folio(folio, GFP_KERNEL))
578 return 0;
579
580 spin_lock(&mapping->host->i_lock);
581 xa_lock_irq(&mapping->i_pages);
582 if (folio_test_dirty(folio))
583 goto failed;
584
585 BUG_ON(folio_has_private(folio));
586 __filemap_remove_folio(folio, NULL);
587 xa_unlock_irq(&mapping->i_pages);
588 if (mapping_shrinkable(mapping))
589 inode_add_lru(mapping->host);
590 spin_unlock(&mapping->host->i_lock);
591
592 filemap_free_folio(mapping, folio);
593 return 1;
594failed:
595 xa_unlock_irq(&mapping->i_pages);
596 spin_unlock(&mapping->host->i_lock);
597 return 0;
598}
599
600static int folio_launder(struct address_space *mapping, struct folio *folio)
601{
602 if (!folio_test_dirty(folio))
603 return 0;
604 if (folio->mapping != mapping || mapping->a_ops->launder_folio == NULL)
605 return 0;
606 return mapping->a_ops->launder_folio(folio);
607}
608
609/**
610 * invalidate_inode_pages2_range - remove range of pages from an address_space
611 * @mapping: the address_space
612 * @start: the page offset 'from' which to invalidate
613 * @end: the page offset 'to' which to invalidate (inclusive)
614 *
615 * Any pages which are found to be mapped into pagetables are unmapped prior to
616 * invalidation.
617 *
618 * Return: -EBUSY if any pages could not be invalidated.
619 */
620int invalidate_inode_pages2_range(struct address_space *mapping,
621 pgoff_t start, pgoff_t end)
622{
623 pgoff_t indices[PAGEVEC_SIZE];
624 struct folio_batch fbatch;
625 pgoff_t index;
626 int i;
627 int ret = 0;
628 int ret2 = 0;
629 int did_range_unmap = 0;
630
631 if (mapping_empty(mapping))
632 return 0;
633
634 folio_batch_init(&fbatch);
635 index = start;
636 while (find_get_entries(mapping, &index, end, &fbatch, indices)) {
637 for (i = 0; i < folio_batch_count(&fbatch); i++) {
638 struct folio *folio = fbatch.folios[i];
639
640 /* We rely upon deletion not changing folio->index */
641
642 if (xa_is_value(folio)) {
643 if (!invalidate_exceptional_entry2(mapping,
644 indices[i], folio))
645 ret = -EBUSY;
646 continue;
647 }
648
649 if (!did_range_unmap && folio_mapped(folio)) {
650 /*
651 * If folio is mapped, before taking its lock,
652 * zap the rest of the file in one hit.
653 */
654 unmap_mapping_pages(mapping, indices[i],
655 (1 + end - indices[i]), false);
656 did_range_unmap = 1;
657 }
658
659 folio_lock(folio);
660 VM_BUG_ON_FOLIO(!folio_contains(folio, indices[i]), folio);
661 if (folio->mapping != mapping) {
662 folio_unlock(folio);
663 continue;
664 }
665 folio_wait_writeback(folio);
666
667 if (folio_mapped(folio))
668 unmap_mapping_folio(folio);
669 BUG_ON(folio_mapped(folio));
670
671 ret2 = folio_launder(mapping, folio);
672 if (ret2 == 0) {
673 if (!invalidate_complete_folio2(mapping, folio))
674 ret2 = -EBUSY;
675 }
676 if (ret2 < 0)
677 ret = ret2;
678 folio_unlock(folio);
679 }
680 folio_batch_remove_exceptionals(&fbatch);
681 folio_batch_release(&fbatch);
682 cond_resched();
683 }
684 /*
685 * For DAX we invalidate page tables after invalidating page cache. We
686 * could invalidate page tables while invalidating each entry however
687 * that would be expensive. And doing range unmapping before doesn't
688 * work as we have no cheap way to find whether page cache entry didn't
689 * get remapped later.
690 */
691 if (dax_mapping(mapping)) {
692 unmap_mapping_pages(mapping, start, end - start + 1, false);
693 }
694 return ret;
695}
696EXPORT_SYMBOL_GPL(invalidate_inode_pages2_range);
697
698/**
699 * invalidate_inode_pages2 - remove all pages from an address_space
700 * @mapping: the address_space
701 *
702 * Any pages which are found to be mapped into pagetables are unmapped prior to
703 * invalidation.
704 *
705 * Return: -EBUSY if any pages could not be invalidated.
706 */
707int invalidate_inode_pages2(struct address_space *mapping)
708{
709 return invalidate_inode_pages2_range(mapping, 0, -1);
710}
711EXPORT_SYMBOL_GPL(invalidate_inode_pages2);
712
713/**
714 * truncate_pagecache - unmap and remove pagecache that has been truncated
715 * @inode: inode
716 * @newsize: new file size
717 *
718 * inode's new i_size must already be written before truncate_pagecache
719 * is called.
720 *
721 * This function should typically be called before the filesystem
722 * releases resources associated with the freed range (eg. deallocates
723 * blocks). This way, pagecache will always stay logically coherent
724 * with on-disk format, and the filesystem would not have to deal with
725 * situations such as writepage being called for a page that has already
726 * had its underlying blocks deallocated.
727 */
728void truncate_pagecache(struct inode *inode, loff_t newsize)
729{
730 struct address_space *mapping = inode->i_mapping;
731 loff_t holebegin = round_up(newsize, PAGE_SIZE);
732
733 /*
734 * unmap_mapping_range is called twice, first simply for
735 * efficiency so that truncate_inode_pages does fewer
736 * single-page unmaps. However after this first call, and
737 * before truncate_inode_pages finishes, it is possible for
738 * private pages to be COWed, which remain after
739 * truncate_inode_pages finishes, hence the second
740 * unmap_mapping_range call must be made for correctness.
741 */
742 unmap_mapping_range(mapping, holebegin, 0, 1);
743 truncate_inode_pages(mapping, newsize);
744 unmap_mapping_range(mapping, holebegin, 0, 1);
745}
746EXPORT_SYMBOL(truncate_pagecache);
747
748/**
749 * truncate_setsize - update inode and pagecache for a new file size
750 * @inode: inode
751 * @newsize: new file size
752 *
753 * truncate_setsize updates i_size and performs pagecache truncation (if
754 * necessary) to @newsize. It will be typically be called from the filesystem's
755 * setattr function when ATTR_SIZE is passed in.
756 *
757 * Must be called with a lock serializing truncates and writes (generally
758 * i_rwsem but e.g. xfs uses a different lock) and before all filesystem
759 * specific block truncation has been performed.
760 */
761void truncate_setsize(struct inode *inode, loff_t newsize)
762{
763 loff_t oldsize = inode->i_size;
764
765 i_size_write(inode, newsize);
766 if (newsize > oldsize)
767 pagecache_isize_extended(inode, oldsize, newsize);
768 truncate_pagecache(inode, newsize);
769}
770EXPORT_SYMBOL(truncate_setsize);
771
772/**
773 * pagecache_isize_extended - update pagecache after extension of i_size
774 * @inode: inode for which i_size was extended
775 * @from: original inode size
776 * @to: new inode size
777 *
778 * Handle extension of inode size either caused by extending truncate or by
779 * write starting after current i_size. We mark the page straddling current
780 * i_size RO so that page_mkwrite() is called on the nearest write access to
781 * the page. This way filesystem can be sure that page_mkwrite() is called on
782 * the page before user writes to the page via mmap after the i_size has been
783 * changed.
784 *
785 * The function must be called after i_size is updated so that page fault
786 * coming after we unlock the page will already see the new i_size.
787 * The function must be called while we still hold i_rwsem - this not only
788 * makes sure i_size is stable but also that userspace cannot observe new
789 * i_size value before we are prepared to store mmap writes at new inode size.
790 */
791void pagecache_isize_extended(struct inode *inode, loff_t from, loff_t to)
792{
793 int bsize = i_blocksize(inode);
794 loff_t rounded_from;
795 struct page *page;
796 pgoff_t index;
797
798 WARN_ON(to > inode->i_size);
799
800 if (from >= to || bsize == PAGE_SIZE)
801 return;
802 /* Page straddling @from will not have any hole block created? */
803 rounded_from = round_up(from, bsize);
804 if (to <= rounded_from || !(rounded_from & (PAGE_SIZE - 1)))
805 return;
806
807 index = from >> PAGE_SHIFT;
808 page = find_lock_page(inode->i_mapping, index);
809 /* Page not cached? Nothing to do */
810 if (!page)
811 return;
812 /*
813 * See clear_page_dirty_for_io() for details why set_page_dirty()
814 * is needed.
815 */
816 if (page_mkclean(page))
817 set_page_dirty(page);
818 unlock_page(page);
819 put_page(page);
820}
821EXPORT_SYMBOL(pagecache_isize_extended);
822
823/**
824 * truncate_pagecache_range - unmap and remove pagecache that is hole-punched
825 * @inode: inode
826 * @lstart: offset of beginning of hole
827 * @lend: offset of last byte of hole
828 *
829 * This function should typically be called before the filesystem
830 * releases resources associated with the freed range (eg. deallocates
831 * blocks). This way, pagecache will always stay logically coherent
832 * with on-disk format, and the filesystem would not have to deal with
833 * situations such as writepage being called for a page that has already
834 * had its underlying blocks deallocated.
835 */
836void truncate_pagecache_range(struct inode *inode, loff_t lstart, loff_t lend)
837{
838 struct address_space *mapping = inode->i_mapping;
839 loff_t unmap_start = round_up(lstart, PAGE_SIZE);
840 loff_t unmap_end = round_down(1 + lend, PAGE_SIZE) - 1;
841 /*
842 * This rounding is currently just for example: unmap_mapping_range
843 * expands its hole outwards, whereas we want it to contract the hole
844 * inwards. However, existing callers of truncate_pagecache_range are
845 * doing their own page rounding first. Note that unmap_mapping_range
846 * allows holelen 0 for all, and we allow lend -1 for end of file.
847 */
848
849 /*
850 * Unlike in truncate_pagecache, unmap_mapping_range is called only
851 * once (before truncating pagecache), and without "even_cows" flag:
852 * hole-punching should not remove private COWed pages from the hole.
853 */
854 if ((u64)unmap_end > (u64)unmap_start)
855 unmap_mapping_range(mapping, unmap_start,
856 1 + unmap_end - unmap_start, 0);
857 truncate_inode_pages_range(mapping, lstart, lend);
858}
859EXPORT_SYMBOL(truncate_pagecache_range);
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * mm/truncate.c - code for taking down pages from address_spaces
4 *
5 * Copyright (C) 2002, Linus Torvalds
6 *
7 * 10Sep2002 Andrew Morton
8 * Initial version.
9 */
10
11#include <linux/kernel.h>
12#include <linux/backing-dev.h>
13#include <linux/dax.h>
14#include <linux/gfp.h>
15#include <linux/mm.h>
16#include <linux/swap.h>
17#include <linux/export.h>
18#include <linux/pagemap.h>
19#include <linux/highmem.h>
20#include <linux/pagevec.h>
21#include <linux/task_io_accounting_ops.h>
22#include <linux/buffer_head.h> /* grr. try_to_release_page,
23 do_invalidatepage */
24#include <linux/shmem_fs.h>
25#include <linux/cleancache.h>
26#include <linux/rmap.h>
27#include "internal.h"
28
29/*
30 * Regular page slots are stabilized by the page lock even without the tree
31 * itself locked. These unlocked entries need verification under the tree
32 * lock.
33 */
34static inline void __clear_shadow_entry(struct address_space *mapping,
35 pgoff_t index, void *entry)
36{
37 XA_STATE(xas, &mapping->i_pages, index);
38
39 xas_set_update(&xas, workingset_update_node);
40 if (xas_load(&xas) != entry)
41 return;
42 xas_store(&xas, NULL);
43 mapping->nrexceptional--;
44}
45
46static void clear_shadow_entry(struct address_space *mapping, pgoff_t index,
47 void *entry)
48{
49 xa_lock_irq(&mapping->i_pages);
50 __clear_shadow_entry(mapping, index, entry);
51 xa_unlock_irq(&mapping->i_pages);
52}
53
54/*
55 * Unconditionally remove exceptional entries. Usually called from truncate
56 * path. Note that the pagevec may be altered by this function by removing
57 * exceptional entries similar to what pagevec_remove_exceptionals does.
58 */
59static void truncate_exceptional_pvec_entries(struct address_space *mapping,
60 struct pagevec *pvec, pgoff_t *indices,
61 pgoff_t end)
62{
63 int i, j;
64 bool dax, lock;
65
66 /* Handled by shmem itself */
67 if (shmem_mapping(mapping))
68 return;
69
70 for (j = 0; j < pagevec_count(pvec); j++)
71 if (xa_is_value(pvec->pages[j]))
72 break;
73
74 if (j == pagevec_count(pvec))
75 return;
76
77 dax = dax_mapping(mapping);
78 lock = !dax && indices[j] < end;
79 if (lock)
80 xa_lock_irq(&mapping->i_pages);
81
82 for (i = j; i < pagevec_count(pvec); i++) {
83 struct page *page = pvec->pages[i];
84 pgoff_t index = indices[i];
85
86 if (!xa_is_value(page)) {
87 pvec->pages[j++] = page;
88 continue;
89 }
90
91 if (index >= end)
92 continue;
93
94 if (unlikely(dax)) {
95 dax_delete_mapping_entry(mapping, index);
96 continue;
97 }
98
99 __clear_shadow_entry(mapping, index, page);
100 }
101
102 if (lock)
103 xa_unlock_irq(&mapping->i_pages);
104 pvec->nr = j;
105}
106
107/*
108 * Invalidate exceptional entry if easily possible. This handles exceptional
109 * entries for invalidate_inode_pages().
110 */
111static int invalidate_exceptional_entry(struct address_space *mapping,
112 pgoff_t index, void *entry)
113{
114 /* Handled by shmem itself, or for DAX we do nothing. */
115 if (shmem_mapping(mapping) || dax_mapping(mapping))
116 return 1;
117 clear_shadow_entry(mapping, index, entry);
118 return 1;
119}
120
121/*
122 * Invalidate exceptional entry if clean. This handles exceptional entries for
123 * invalidate_inode_pages2() so for DAX it evicts only clean entries.
124 */
125static int invalidate_exceptional_entry2(struct address_space *mapping,
126 pgoff_t index, void *entry)
127{
128 /* Handled by shmem itself */
129 if (shmem_mapping(mapping))
130 return 1;
131 if (dax_mapping(mapping))
132 return dax_invalidate_mapping_entry_sync(mapping, index);
133 clear_shadow_entry(mapping, index, entry);
134 return 1;
135}
136
137/**
138 * do_invalidatepage - invalidate part or all of a page
139 * @page: the page which is affected
140 * @offset: start of the range to invalidate
141 * @length: length of the range to invalidate
142 *
143 * do_invalidatepage() is called when all or part of the page has become
144 * invalidated by a truncate operation.
145 *
146 * do_invalidatepage() does not have to release all buffers, but it must
147 * ensure that no dirty buffer is left outside @offset and that no I/O
148 * is underway against any of the blocks which are outside the truncation
149 * point. Because the caller is about to free (and possibly reuse) those
150 * blocks on-disk.
151 */
152void do_invalidatepage(struct page *page, unsigned int offset,
153 unsigned int length)
154{
155 void (*invalidatepage)(struct page *, unsigned int, unsigned int);
156
157 invalidatepage = page->mapping->a_ops->invalidatepage;
158#ifdef CONFIG_BLOCK
159 if (!invalidatepage)
160 invalidatepage = block_invalidatepage;
161#endif
162 if (invalidatepage)
163 (*invalidatepage)(page, offset, length);
164}
165
166/*
167 * If truncate cannot remove the fs-private metadata from the page, the page
168 * becomes orphaned. It will be left on the LRU and may even be mapped into
169 * user pagetables if we're racing with filemap_fault().
170 *
171 * We need to bale out if page->mapping is no longer equal to the original
172 * mapping. This happens a) when the VM reclaimed the page while we waited on
173 * its lock, b) when a concurrent invalidate_mapping_pages got there first and
174 * c) when tmpfs swizzles a page between a tmpfs inode and swapper_space.
175 */
176static void
177truncate_cleanup_page(struct address_space *mapping, struct page *page)
178{
179 if (page_mapped(page)) {
180 pgoff_t nr = PageTransHuge(page) ? HPAGE_PMD_NR : 1;
181 unmap_mapping_pages(mapping, page->index, nr, false);
182 }
183
184 if (page_has_private(page))
185 do_invalidatepage(page, 0, PAGE_SIZE);
186
187 /*
188 * Some filesystems seem to re-dirty the page even after
189 * the VM has canceled the dirty bit (eg ext3 journaling).
190 * Hence dirty accounting check is placed after invalidation.
191 */
192 cancel_dirty_page(page);
193 ClearPageMappedToDisk(page);
194}
195
196/*
197 * This is for invalidate_mapping_pages(). That function can be called at
198 * any time, and is not supposed to throw away dirty pages. But pages can
199 * be marked dirty at any time too, so use remove_mapping which safely
200 * discards clean, unused pages.
201 *
202 * Returns non-zero if the page was successfully invalidated.
203 */
204static int
205invalidate_complete_page(struct address_space *mapping, struct page *page)
206{
207 int ret;
208
209 if (page->mapping != mapping)
210 return 0;
211
212 if (page_has_private(page) && !try_to_release_page(page, 0))
213 return 0;
214
215 ret = remove_mapping(mapping, page);
216
217 return ret;
218}
219
220int truncate_inode_page(struct address_space *mapping, struct page *page)
221{
222 VM_BUG_ON_PAGE(PageTail(page), page);
223
224 if (page->mapping != mapping)
225 return -EIO;
226
227 truncate_cleanup_page(mapping, page);
228 delete_from_page_cache(page);
229 return 0;
230}
231
232/*
233 * Used to get rid of pages on hardware memory corruption.
234 */
235int generic_error_remove_page(struct address_space *mapping, struct page *page)
236{
237 if (!mapping)
238 return -EINVAL;
239 /*
240 * Only punch for normal data pages for now.
241 * Handling other types like directories would need more auditing.
242 */
243 if (!S_ISREG(mapping->host->i_mode))
244 return -EIO;
245 return truncate_inode_page(mapping, page);
246}
247EXPORT_SYMBOL(generic_error_remove_page);
248
249/*
250 * Safely invalidate one page from its pagecache mapping.
251 * It only drops clean, unused pages. The page must be locked.
252 *
253 * Returns 1 if the page is successfully invalidated, otherwise 0.
254 */
255int invalidate_inode_page(struct page *page)
256{
257 struct address_space *mapping = page_mapping(page);
258 if (!mapping)
259 return 0;
260 if (PageDirty(page) || PageWriteback(page))
261 return 0;
262 if (page_mapped(page))
263 return 0;
264 return invalidate_complete_page(mapping, page);
265}
266
267/**
268 * truncate_inode_pages_range - truncate range of pages specified by start & end byte offsets
269 * @mapping: mapping to truncate
270 * @lstart: offset from which to truncate
271 * @lend: offset to which to truncate (inclusive)
272 *
273 * Truncate the page cache, removing the pages that are between
274 * specified offsets (and zeroing out partial pages
275 * if lstart or lend + 1 is not page aligned).
276 *
277 * Truncate takes two passes - the first pass is nonblocking. It will not
278 * block on page locks and it will not block on writeback. The second pass
279 * will wait. This is to prevent as much IO as possible in the affected region.
280 * The first pass will remove most pages, so the search cost of the second pass
281 * is low.
282 *
283 * We pass down the cache-hot hint to the page freeing code. Even if the
284 * mapping is large, it is probably the case that the final pages are the most
285 * recently touched, and freeing happens in ascending file offset order.
286 *
287 * Note that since ->invalidatepage() accepts range to invalidate
288 * truncate_inode_pages_range is able to handle cases where lend + 1 is not
289 * page aligned properly.
290 */
291void truncate_inode_pages_range(struct address_space *mapping,
292 loff_t lstart, loff_t lend)
293{
294 pgoff_t start; /* inclusive */
295 pgoff_t end; /* exclusive */
296 unsigned int partial_start; /* inclusive */
297 unsigned int partial_end; /* exclusive */
298 struct pagevec pvec;
299 pgoff_t indices[PAGEVEC_SIZE];
300 pgoff_t index;
301 int i;
302
303 if (mapping->nrpages == 0 && mapping->nrexceptional == 0)
304 goto out;
305
306 /* Offsets within partial pages */
307 partial_start = lstart & (PAGE_SIZE - 1);
308 partial_end = (lend + 1) & (PAGE_SIZE - 1);
309
310 /*
311 * 'start' and 'end' always covers the range of pages to be fully
312 * truncated. Partial pages are covered with 'partial_start' at the
313 * start of the range and 'partial_end' at the end of the range.
314 * Note that 'end' is exclusive while 'lend' is inclusive.
315 */
316 start = (lstart + PAGE_SIZE - 1) >> PAGE_SHIFT;
317 if (lend == -1)
318 /*
319 * lend == -1 indicates end-of-file so we have to set 'end'
320 * to the highest possible pgoff_t and since the type is
321 * unsigned we're using -1.
322 */
323 end = -1;
324 else
325 end = (lend + 1) >> PAGE_SHIFT;
326
327 pagevec_init(&pvec);
328 index = start;
329 while (index < end && pagevec_lookup_entries(&pvec, mapping, index,
330 min(end - index, (pgoff_t)PAGEVEC_SIZE),
331 indices)) {
332 /*
333 * Pagevec array has exceptional entries and we may also fail
334 * to lock some pages. So we store pages that can be deleted
335 * in a new pagevec.
336 */
337 struct pagevec locked_pvec;
338
339 pagevec_init(&locked_pvec);
340 for (i = 0; i < pagevec_count(&pvec); i++) {
341 struct page *page = pvec.pages[i];
342
343 /* We rely upon deletion not changing page->index */
344 index = indices[i];
345 if (index >= end)
346 break;
347
348 if (xa_is_value(page))
349 continue;
350
351 if (!trylock_page(page))
352 continue;
353 WARN_ON(page_to_index(page) != index);
354 if (PageWriteback(page)) {
355 unlock_page(page);
356 continue;
357 }
358 if (page->mapping != mapping) {
359 unlock_page(page);
360 continue;
361 }
362 pagevec_add(&locked_pvec, page);
363 }
364 for (i = 0; i < pagevec_count(&locked_pvec); i++)
365 truncate_cleanup_page(mapping, locked_pvec.pages[i]);
366 delete_from_page_cache_batch(mapping, &locked_pvec);
367 for (i = 0; i < pagevec_count(&locked_pvec); i++)
368 unlock_page(locked_pvec.pages[i]);
369 truncate_exceptional_pvec_entries(mapping, &pvec, indices, end);
370 pagevec_release(&pvec);
371 cond_resched();
372 index++;
373 }
374 if (partial_start) {
375 struct page *page = find_lock_page(mapping, start - 1);
376 if (page) {
377 unsigned int top = PAGE_SIZE;
378 if (start > end) {
379 /* Truncation within a single page */
380 top = partial_end;
381 partial_end = 0;
382 }
383 wait_on_page_writeback(page);
384 zero_user_segment(page, partial_start, top);
385 cleancache_invalidate_page(mapping, page);
386 if (page_has_private(page))
387 do_invalidatepage(page, partial_start,
388 top - partial_start);
389 unlock_page(page);
390 put_page(page);
391 }
392 }
393 if (partial_end) {
394 struct page *page = find_lock_page(mapping, end);
395 if (page) {
396 wait_on_page_writeback(page);
397 zero_user_segment(page, 0, partial_end);
398 cleancache_invalidate_page(mapping, page);
399 if (page_has_private(page))
400 do_invalidatepage(page, 0,
401 partial_end);
402 unlock_page(page);
403 put_page(page);
404 }
405 }
406 /*
407 * If the truncation happened within a single page no pages
408 * will be released, just zeroed, so we can bail out now.
409 */
410 if (start >= end)
411 goto out;
412
413 index = start;
414 for ( ; ; ) {
415 cond_resched();
416 if (!pagevec_lookup_entries(&pvec, mapping, index,
417 min(end - index, (pgoff_t)PAGEVEC_SIZE), indices)) {
418 /* If all gone from start onwards, we're done */
419 if (index == start)
420 break;
421 /* Otherwise restart to make sure all gone */
422 index = start;
423 continue;
424 }
425 if (index == start && indices[0] >= end) {
426 /* All gone out of hole to be punched, we're done */
427 pagevec_remove_exceptionals(&pvec);
428 pagevec_release(&pvec);
429 break;
430 }
431
432 for (i = 0; i < pagevec_count(&pvec); i++) {
433 struct page *page = pvec.pages[i];
434
435 /* We rely upon deletion not changing page->index */
436 index = indices[i];
437 if (index >= end) {
438 /* Restart punch to make sure all gone */
439 index = start - 1;
440 break;
441 }
442
443 if (xa_is_value(page))
444 continue;
445
446 lock_page(page);
447 WARN_ON(page_to_index(page) != index);
448 wait_on_page_writeback(page);
449 truncate_inode_page(mapping, page);
450 unlock_page(page);
451 }
452 truncate_exceptional_pvec_entries(mapping, &pvec, indices, end);
453 pagevec_release(&pvec);
454 index++;
455 }
456
457out:
458 cleancache_invalidate_inode(mapping);
459}
460EXPORT_SYMBOL(truncate_inode_pages_range);
461
462/**
463 * truncate_inode_pages - truncate *all* the pages from an offset
464 * @mapping: mapping to truncate
465 * @lstart: offset from which to truncate
466 *
467 * Called under (and serialised by) inode->i_mutex.
468 *
469 * Note: When this function returns, there can be a page in the process of
470 * deletion (inside __delete_from_page_cache()) in the specified range. Thus
471 * mapping->nrpages can be non-zero when this function returns even after
472 * truncation of the whole mapping.
473 */
474void truncate_inode_pages(struct address_space *mapping, loff_t lstart)
475{
476 truncate_inode_pages_range(mapping, lstart, (loff_t)-1);
477}
478EXPORT_SYMBOL(truncate_inode_pages);
479
480/**
481 * truncate_inode_pages_final - truncate *all* pages before inode dies
482 * @mapping: mapping to truncate
483 *
484 * Called under (and serialized by) inode->i_mutex.
485 *
486 * Filesystems have to use this in the .evict_inode path to inform the
487 * VM that this is the final truncate and the inode is going away.
488 */
489void truncate_inode_pages_final(struct address_space *mapping)
490{
491 unsigned long nrexceptional;
492 unsigned long nrpages;
493
494 /*
495 * Page reclaim can not participate in regular inode lifetime
496 * management (can't call iput()) and thus can race with the
497 * inode teardown. Tell it when the address space is exiting,
498 * so that it does not install eviction information after the
499 * final truncate has begun.
500 */
501 mapping_set_exiting(mapping);
502
503 /*
504 * When reclaim installs eviction entries, it increases
505 * nrexceptional first, then decreases nrpages. Make sure we see
506 * this in the right order or we might miss an entry.
507 */
508 nrpages = mapping->nrpages;
509 smp_rmb();
510 nrexceptional = mapping->nrexceptional;
511
512 if (nrpages || nrexceptional) {
513 /*
514 * As truncation uses a lockless tree lookup, cycle
515 * the tree lock to make sure any ongoing tree
516 * modification that does not see AS_EXITING is
517 * completed before starting the final truncate.
518 */
519 xa_lock_irq(&mapping->i_pages);
520 xa_unlock_irq(&mapping->i_pages);
521 }
522
523 /*
524 * Cleancache needs notification even if there are no pages or shadow
525 * entries.
526 */
527 truncate_inode_pages(mapping, 0);
528}
529EXPORT_SYMBOL(truncate_inode_pages_final);
530
531/**
532 * invalidate_mapping_pages - Invalidate all the unlocked pages of one inode
533 * @mapping: the address_space which holds the pages to invalidate
534 * @start: the offset 'from' which to invalidate
535 * @end: the offset 'to' which to invalidate (inclusive)
536 *
537 * This function only removes the unlocked pages, if you want to
538 * remove all the pages of one inode, you must call truncate_inode_pages.
539 *
540 * invalidate_mapping_pages() will not block on IO activity. It will not
541 * invalidate pages which are dirty, locked, under writeback or mapped into
542 * pagetables.
543 *
544 * Return: the number of the pages that were invalidated
545 */
546unsigned long invalidate_mapping_pages(struct address_space *mapping,
547 pgoff_t start, pgoff_t end)
548{
549 pgoff_t indices[PAGEVEC_SIZE];
550 struct pagevec pvec;
551 pgoff_t index = start;
552 unsigned long ret;
553 unsigned long count = 0;
554 int i;
555
556 pagevec_init(&pvec);
557 while (index <= end && pagevec_lookup_entries(&pvec, mapping, index,
558 min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1,
559 indices)) {
560 for (i = 0; i < pagevec_count(&pvec); i++) {
561 struct page *page = pvec.pages[i];
562
563 /* We rely upon deletion not changing page->index */
564 index = indices[i];
565 if (index > end)
566 break;
567
568 if (xa_is_value(page)) {
569 invalidate_exceptional_entry(mapping, index,
570 page);
571 continue;
572 }
573
574 if (!trylock_page(page))
575 continue;
576
577 WARN_ON(page_to_index(page) != index);
578
579 /* Middle of THP: skip */
580 if (PageTransTail(page)) {
581 unlock_page(page);
582 continue;
583 } else if (PageTransHuge(page)) {
584 index += HPAGE_PMD_NR - 1;
585 i += HPAGE_PMD_NR - 1;
586 /*
587 * 'end' is in the middle of THP. Don't
588 * invalidate the page as the part outside of
589 * 'end' could be still useful.
590 */
591 if (index > end) {
592 unlock_page(page);
593 continue;
594 }
595
596 /* Take a pin outside pagevec */
597 get_page(page);
598
599 /*
600 * Drop extra pins before trying to invalidate
601 * the huge page.
602 */
603 pagevec_remove_exceptionals(&pvec);
604 pagevec_release(&pvec);
605 }
606
607 ret = invalidate_inode_page(page);
608 unlock_page(page);
609 /*
610 * Invalidation is a hint that the page is no longer
611 * of interest and try to speed up its reclaim.
612 */
613 if (!ret)
614 deactivate_file_page(page);
615 if (PageTransHuge(page))
616 put_page(page);
617 count += ret;
618 }
619 pagevec_remove_exceptionals(&pvec);
620 pagevec_release(&pvec);
621 cond_resched();
622 index++;
623 }
624 return count;
625}
626EXPORT_SYMBOL(invalidate_mapping_pages);
627
628/*
629 * This is like invalidate_complete_page(), except it ignores the page's
630 * refcount. We do this because invalidate_inode_pages2() needs stronger
631 * invalidation guarantees, and cannot afford to leave pages behind because
632 * shrink_page_list() has a temp ref on them, or because they're transiently
633 * sitting in the lru_cache_add() pagevecs.
634 */
635static int
636invalidate_complete_page2(struct address_space *mapping, struct page *page)
637{
638 unsigned long flags;
639
640 if (page->mapping != mapping)
641 return 0;
642
643 if (page_has_private(page) && !try_to_release_page(page, GFP_KERNEL))
644 return 0;
645
646 xa_lock_irqsave(&mapping->i_pages, flags);
647 if (PageDirty(page))
648 goto failed;
649
650 BUG_ON(page_has_private(page));
651 __delete_from_page_cache(page, NULL);
652 xa_unlock_irqrestore(&mapping->i_pages, flags);
653
654 if (mapping->a_ops->freepage)
655 mapping->a_ops->freepage(page);
656
657 put_page(page); /* pagecache ref */
658 return 1;
659failed:
660 xa_unlock_irqrestore(&mapping->i_pages, flags);
661 return 0;
662}
663
664static int do_launder_page(struct address_space *mapping, struct page *page)
665{
666 if (!PageDirty(page))
667 return 0;
668 if (page->mapping != mapping || mapping->a_ops->launder_page == NULL)
669 return 0;
670 return mapping->a_ops->launder_page(page);
671}
672
673/**
674 * invalidate_inode_pages2_range - remove range of pages from an address_space
675 * @mapping: the address_space
676 * @start: the page offset 'from' which to invalidate
677 * @end: the page offset 'to' which to invalidate (inclusive)
678 *
679 * Any pages which are found to be mapped into pagetables are unmapped prior to
680 * invalidation.
681 *
682 * Return: -EBUSY if any pages could not be invalidated.
683 */
684int invalidate_inode_pages2_range(struct address_space *mapping,
685 pgoff_t start, pgoff_t end)
686{
687 pgoff_t indices[PAGEVEC_SIZE];
688 struct pagevec pvec;
689 pgoff_t index;
690 int i;
691 int ret = 0;
692 int ret2 = 0;
693 int did_range_unmap = 0;
694
695 if (mapping->nrpages == 0 && mapping->nrexceptional == 0)
696 goto out;
697
698 pagevec_init(&pvec);
699 index = start;
700 while (index <= end && pagevec_lookup_entries(&pvec, mapping, index,
701 min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1,
702 indices)) {
703 for (i = 0; i < pagevec_count(&pvec); i++) {
704 struct page *page = pvec.pages[i];
705
706 /* We rely upon deletion not changing page->index */
707 index = indices[i];
708 if (index > end)
709 break;
710
711 if (xa_is_value(page)) {
712 if (!invalidate_exceptional_entry2(mapping,
713 index, page))
714 ret = -EBUSY;
715 continue;
716 }
717
718 lock_page(page);
719 WARN_ON(page_to_index(page) != index);
720 if (page->mapping != mapping) {
721 unlock_page(page);
722 continue;
723 }
724 wait_on_page_writeback(page);
725 if (page_mapped(page)) {
726 if (!did_range_unmap) {
727 /*
728 * Zap the rest of the file in one hit.
729 */
730 unmap_mapping_pages(mapping, index,
731 (1 + end - index), false);
732 did_range_unmap = 1;
733 } else {
734 /*
735 * Just zap this page
736 */
737 unmap_mapping_pages(mapping, index,
738 1, false);
739 }
740 }
741 BUG_ON(page_mapped(page));
742 ret2 = do_launder_page(mapping, page);
743 if (ret2 == 0) {
744 if (!invalidate_complete_page2(mapping, page))
745 ret2 = -EBUSY;
746 }
747 if (ret2 < 0)
748 ret = ret2;
749 unlock_page(page);
750 }
751 pagevec_remove_exceptionals(&pvec);
752 pagevec_release(&pvec);
753 cond_resched();
754 index++;
755 }
756 /*
757 * For DAX we invalidate page tables after invalidating page cache. We
758 * could invalidate page tables while invalidating each entry however
759 * that would be expensive. And doing range unmapping before doesn't
760 * work as we have no cheap way to find whether page cache entry didn't
761 * get remapped later.
762 */
763 if (dax_mapping(mapping)) {
764 unmap_mapping_pages(mapping, start, end - start + 1, false);
765 }
766out:
767 cleancache_invalidate_inode(mapping);
768 return ret;
769}
770EXPORT_SYMBOL_GPL(invalidate_inode_pages2_range);
771
772/**
773 * invalidate_inode_pages2 - remove all pages from an address_space
774 * @mapping: the address_space
775 *
776 * Any pages which are found to be mapped into pagetables are unmapped prior to
777 * invalidation.
778 *
779 * Return: -EBUSY if any pages could not be invalidated.
780 */
781int invalidate_inode_pages2(struct address_space *mapping)
782{
783 return invalidate_inode_pages2_range(mapping, 0, -1);
784}
785EXPORT_SYMBOL_GPL(invalidate_inode_pages2);
786
787/**
788 * truncate_pagecache - unmap and remove pagecache that has been truncated
789 * @inode: inode
790 * @newsize: new file size
791 *
792 * inode's new i_size must already be written before truncate_pagecache
793 * is called.
794 *
795 * This function should typically be called before the filesystem
796 * releases resources associated with the freed range (eg. deallocates
797 * blocks). This way, pagecache will always stay logically coherent
798 * with on-disk format, and the filesystem would not have to deal with
799 * situations such as writepage being called for a page that has already
800 * had its underlying blocks deallocated.
801 */
802void truncate_pagecache(struct inode *inode, loff_t newsize)
803{
804 struct address_space *mapping = inode->i_mapping;
805 loff_t holebegin = round_up(newsize, PAGE_SIZE);
806
807 /*
808 * unmap_mapping_range is called twice, first simply for
809 * efficiency so that truncate_inode_pages does fewer
810 * single-page unmaps. However after this first call, and
811 * before truncate_inode_pages finishes, it is possible for
812 * private pages to be COWed, which remain after
813 * truncate_inode_pages finishes, hence the second
814 * unmap_mapping_range call must be made for correctness.
815 */
816 unmap_mapping_range(mapping, holebegin, 0, 1);
817 truncate_inode_pages(mapping, newsize);
818 unmap_mapping_range(mapping, holebegin, 0, 1);
819}
820EXPORT_SYMBOL(truncate_pagecache);
821
822/**
823 * truncate_setsize - update inode and pagecache for a new file size
824 * @inode: inode
825 * @newsize: new file size
826 *
827 * truncate_setsize updates i_size and performs pagecache truncation (if
828 * necessary) to @newsize. It will be typically be called from the filesystem's
829 * setattr function when ATTR_SIZE is passed in.
830 *
831 * Must be called with a lock serializing truncates and writes (generally
832 * i_mutex but e.g. xfs uses a different lock) and before all filesystem
833 * specific block truncation has been performed.
834 */
835void truncate_setsize(struct inode *inode, loff_t newsize)
836{
837 loff_t oldsize = inode->i_size;
838
839 i_size_write(inode, newsize);
840 if (newsize > oldsize)
841 pagecache_isize_extended(inode, oldsize, newsize);
842 truncate_pagecache(inode, newsize);
843}
844EXPORT_SYMBOL(truncate_setsize);
845
846/**
847 * pagecache_isize_extended - update pagecache after extension of i_size
848 * @inode: inode for which i_size was extended
849 * @from: original inode size
850 * @to: new inode size
851 *
852 * Handle extension of inode size either caused by extending truncate or by
853 * write starting after current i_size. We mark the page straddling current
854 * i_size RO so that page_mkwrite() is called on the nearest write access to
855 * the page. This way filesystem can be sure that page_mkwrite() is called on
856 * the page before user writes to the page via mmap after the i_size has been
857 * changed.
858 *
859 * The function must be called after i_size is updated so that page fault
860 * coming after we unlock the page will already see the new i_size.
861 * The function must be called while we still hold i_mutex - this not only
862 * makes sure i_size is stable but also that userspace cannot observe new
863 * i_size value before we are prepared to store mmap writes at new inode size.
864 */
865void pagecache_isize_extended(struct inode *inode, loff_t from, loff_t to)
866{
867 int bsize = i_blocksize(inode);
868 loff_t rounded_from;
869 struct page *page;
870 pgoff_t index;
871
872 WARN_ON(to > inode->i_size);
873
874 if (from >= to || bsize == PAGE_SIZE)
875 return;
876 /* Page straddling @from will not have any hole block created? */
877 rounded_from = round_up(from, bsize);
878 if (to <= rounded_from || !(rounded_from & (PAGE_SIZE - 1)))
879 return;
880
881 index = from >> PAGE_SHIFT;
882 page = find_lock_page(inode->i_mapping, index);
883 /* Page not cached? Nothing to do */
884 if (!page)
885 return;
886 /*
887 * See clear_page_dirty_for_io() for details why set_page_dirty()
888 * is needed.
889 */
890 if (page_mkclean(page))
891 set_page_dirty(page);
892 unlock_page(page);
893 put_page(page);
894}
895EXPORT_SYMBOL(pagecache_isize_extended);
896
897/**
898 * truncate_pagecache_range - unmap and remove pagecache that is hole-punched
899 * @inode: inode
900 * @lstart: offset of beginning of hole
901 * @lend: offset of last byte of hole
902 *
903 * This function should typically be called before the filesystem
904 * releases resources associated with the freed range (eg. deallocates
905 * blocks). This way, pagecache will always stay logically coherent
906 * with on-disk format, and the filesystem would not have to deal with
907 * situations such as writepage being called for a page that has already
908 * had its underlying blocks deallocated.
909 */
910void truncate_pagecache_range(struct inode *inode, loff_t lstart, loff_t lend)
911{
912 struct address_space *mapping = inode->i_mapping;
913 loff_t unmap_start = round_up(lstart, PAGE_SIZE);
914 loff_t unmap_end = round_down(1 + lend, PAGE_SIZE) - 1;
915 /*
916 * This rounding is currently just for example: unmap_mapping_range
917 * expands its hole outwards, whereas we want it to contract the hole
918 * inwards. However, existing callers of truncate_pagecache_range are
919 * doing their own page rounding first. Note that unmap_mapping_range
920 * allows holelen 0 for all, and we allow lend -1 for end of file.
921 */
922
923 /*
924 * Unlike in truncate_pagecache, unmap_mapping_range is called only
925 * once (before truncating pagecache), and without "even_cows" flag:
926 * hole-punching should not remove private COWed pages from the hole.
927 */
928 if ((u64)unmap_end > (u64)unmap_start)
929 unmap_mapping_range(mapping, unmap_start,
930 1 + unmap_end - unmap_start, 0);
931 truncate_inode_pages_range(mapping, lstart, lend);
932}
933EXPORT_SYMBOL(truncate_pagecache_range);