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