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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 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);
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/gfp.h>
13#include <linux/mm.h>
14#include <linux/swap.h>
15#include <linux/export.h>
16#include <linux/pagemap.h>
17#include <linux/highmem.h>
18#include <linux/pagevec.h>
19#include <linux/task_io_accounting_ops.h>
20#include <linux/buffer_head.h> /* grr. try_to_release_page,
21 do_invalidatepage */
22#include <linux/cleancache.h>
23#include "internal.h"
24
25static void clear_exceptional_entry(struct address_space *mapping,
26 pgoff_t index, void *entry)
27{
28 struct radix_tree_node *node;
29 void **slot;
30
31 /* Handled by shmem itself */
32 if (shmem_mapping(mapping))
33 return;
34
35 spin_lock_irq(&mapping->tree_lock);
36 /*
37 * Regular page slots are stabilized by the page lock even
38 * without the tree itself locked. These unlocked entries
39 * need verification under the tree lock.
40 */
41 if (!__radix_tree_lookup(&mapping->page_tree, index, &node, &slot))
42 goto unlock;
43 if (*slot != entry)
44 goto unlock;
45 radix_tree_replace_slot(slot, NULL);
46 mapping->nrshadows--;
47 if (!node)
48 goto unlock;
49 workingset_node_shadows_dec(node);
50 /*
51 * Don't track node without shadow entries.
52 *
53 * Avoid acquiring the list_lru lock if already untracked.
54 * The list_empty() test is safe as node->private_list is
55 * protected by mapping->tree_lock.
56 */
57 if (!workingset_node_shadows(node) &&
58 !list_empty(&node->private_list))
59 list_lru_del(&workingset_shadow_nodes, &node->private_list);
60 __radix_tree_delete_node(&mapping->page_tree, node);
61unlock:
62 spin_unlock_irq(&mapping->tree_lock);
63}
64
65/**
66 * do_invalidatepage - invalidate part or all of a page
67 * @page: the page which is affected
68 * @offset: start of the range to invalidate
69 * @length: length of the range to invalidate
70 *
71 * do_invalidatepage() is called when all or part of the page has become
72 * invalidated by a truncate operation.
73 *
74 * do_invalidatepage() does not have to release all buffers, but it must
75 * ensure that no dirty buffer is left outside @offset and that no I/O
76 * is underway against any of the blocks which are outside the truncation
77 * point. Because the caller is about to free (and possibly reuse) those
78 * blocks on-disk.
79 */
80void do_invalidatepage(struct page *page, unsigned int offset,
81 unsigned int length)
82{
83 void (*invalidatepage)(struct page *, unsigned int, unsigned int);
84
85 invalidatepage = page->mapping->a_ops->invalidatepage;
86#ifdef CONFIG_BLOCK
87 if (!invalidatepage)
88 invalidatepage = block_invalidatepage;
89#endif
90 if (invalidatepage)
91 (*invalidatepage)(page, offset, length);
92}
93
94/*
95 * This cancels just the dirty bit on the kernel page itself, it
96 * does NOT actually remove dirty bits on any mmap's that may be
97 * around. It also leaves the page tagged dirty, so any sync
98 * activity will still find it on the dirty lists, and in particular,
99 * clear_page_dirty_for_io() will still look at the dirty bits in
100 * the VM.
101 *
102 * Doing this should *normally* only ever be done when a page
103 * is truncated, and is not actually mapped anywhere at all. However,
104 * fs/buffer.c does this when it notices that somebody has cleaned
105 * out all the buffers on a page without actually doing it through
106 * the VM. Can you say "ext3 is horribly ugly"? Tought you could.
107 */
108void cancel_dirty_page(struct page *page, unsigned int account_size)
109{
110 if (TestClearPageDirty(page)) {
111 struct address_space *mapping = page->mapping;
112 if (mapping && mapping_cap_account_dirty(mapping)) {
113 dec_zone_page_state(page, NR_FILE_DIRTY);
114 dec_bdi_stat(mapping->backing_dev_info,
115 BDI_RECLAIMABLE);
116 if (account_size)
117 task_io_account_cancelled_write(account_size);
118 }
119 }
120}
121EXPORT_SYMBOL(cancel_dirty_page);
122
123/*
124 * If truncate cannot remove the fs-private metadata from the page, the page
125 * becomes orphaned. It will be left on the LRU and may even be mapped into
126 * user pagetables if we're racing with filemap_fault().
127 *
128 * We need to bale out if page->mapping is no longer equal to the original
129 * mapping. This happens a) when the VM reclaimed the page while we waited on
130 * its lock, b) when a concurrent invalidate_mapping_pages got there first and
131 * c) when tmpfs swizzles a page between a tmpfs inode and swapper_space.
132 */
133static int
134truncate_complete_page(struct address_space *mapping, struct page *page)
135{
136 if (page->mapping != mapping)
137 return -EIO;
138
139 if (page_has_private(page))
140 do_invalidatepage(page, 0, PAGE_CACHE_SIZE);
141
142 cancel_dirty_page(page, PAGE_CACHE_SIZE);
143
144 ClearPageMappedToDisk(page);
145 delete_from_page_cache(page);
146 return 0;
147}
148
149/*
150 * This is for invalidate_mapping_pages(). That function can be called at
151 * any time, and is not supposed to throw away dirty pages. But pages can
152 * be marked dirty at any time too, so use remove_mapping which safely
153 * discards clean, unused pages.
154 *
155 * Returns non-zero if the page was successfully invalidated.
156 */
157static int
158invalidate_complete_page(struct address_space *mapping, struct page *page)
159{
160 int ret;
161
162 if (page->mapping != mapping)
163 return 0;
164
165 if (page_has_private(page) && !try_to_release_page(page, 0))
166 return 0;
167
168 ret = remove_mapping(mapping, page);
169
170 return ret;
171}
172
173int truncate_inode_page(struct address_space *mapping, struct page *page)
174{
175 if (page_mapped(page)) {
176 unmap_mapping_range(mapping,
177 (loff_t)page->index << PAGE_CACHE_SHIFT,
178 PAGE_CACHE_SIZE, 0);
179 }
180 return truncate_complete_page(mapping, page);
181}
182
183/*
184 * Used to get rid of pages on hardware memory corruption.
185 */
186int generic_error_remove_page(struct address_space *mapping, struct page *page)
187{
188 if (!mapping)
189 return -EINVAL;
190 /*
191 * Only punch for normal data pages for now.
192 * Handling other types like directories would need more auditing.
193 */
194 if (!S_ISREG(mapping->host->i_mode))
195 return -EIO;
196 return truncate_inode_page(mapping, page);
197}
198EXPORT_SYMBOL(generic_error_remove_page);
199
200/*
201 * Safely invalidate one page from its pagecache mapping.
202 * It only drops clean, unused pages. The page must be locked.
203 *
204 * Returns 1 if the page is successfully invalidated, otherwise 0.
205 */
206int invalidate_inode_page(struct page *page)
207{
208 struct address_space *mapping = page_mapping(page);
209 if (!mapping)
210 return 0;
211 if (PageDirty(page) || PageWriteback(page))
212 return 0;
213 if (page_mapped(page))
214 return 0;
215 return invalidate_complete_page(mapping, page);
216}
217
218/**
219 * truncate_inode_pages_range - truncate range of pages specified by start & end byte offsets
220 * @mapping: mapping to truncate
221 * @lstart: offset from which to truncate
222 * @lend: offset to which to truncate (inclusive)
223 *
224 * Truncate the page cache, removing the pages that are between
225 * specified offsets (and zeroing out partial pages
226 * if lstart or lend + 1 is not page aligned).
227 *
228 * Truncate takes two passes - the first pass is nonblocking. It will not
229 * block on page locks and it will not block on writeback. The second pass
230 * will wait. This is to prevent as much IO as possible in the affected region.
231 * The first pass will remove most pages, so the search cost of the second pass
232 * is low.
233 *
234 * We pass down the cache-hot hint to the page freeing code. Even if the
235 * mapping is large, it is probably the case that the final pages are the most
236 * recently touched, and freeing happens in ascending file offset order.
237 *
238 * Note that since ->invalidatepage() accepts range to invalidate
239 * truncate_inode_pages_range is able to handle cases where lend + 1 is not
240 * page aligned properly.
241 */
242void truncate_inode_pages_range(struct address_space *mapping,
243 loff_t lstart, loff_t lend)
244{
245 pgoff_t start; /* inclusive */
246 pgoff_t end; /* exclusive */
247 unsigned int partial_start; /* inclusive */
248 unsigned int partial_end; /* exclusive */
249 struct pagevec pvec;
250 pgoff_t indices[PAGEVEC_SIZE];
251 pgoff_t index;
252 int i;
253
254 cleancache_invalidate_inode(mapping);
255 if (mapping->nrpages == 0 && mapping->nrshadows == 0)
256 return;
257
258 /* Offsets within partial pages */
259 partial_start = lstart & (PAGE_CACHE_SIZE - 1);
260 partial_end = (lend + 1) & (PAGE_CACHE_SIZE - 1);
261
262 /*
263 * 'start' and 'end' always covers the range of pages to be fully
264 * truncated. Partial pages are covered with 'partial_start' at the
265 * start of the range and 'partial_end' at the end of the range.
266 * Note that 'end' is exclusive while 'lend' is inclusive.
267 */
268 start = (lstart + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
269 if (lend == -1)
270 /*
271 * lend == -1 indicates end-of-file so we have to set 'end'
272 * to the highest possible pgoff_t and since the type is
273 * unsigned we're using -1.
274 */
275 end = -1;
276 else
277 end = (lend + 1) >> PAGE_CACHE_SHIFT;
278
279 pagevec_init(&pvec, 0);
280 index = start;
281 while (index < end && pagevec_lookup_entries(&pvec, mapping, index,
282 min(end - index, (pgoff_t)PAGEVEC_SIZE),
283 indices)) {
284 mem_cgroup_uncharge_start();
285 for (i = 0; i < pagevec_count(&pvec); i++) {
286 struct page *page = pvec.pages[i];
287
288 /* We rely upon deletion not changing page->index */
289 index = indices[i];
290 if (index >= end)
291 break;
292
293 if (radix_tree_exceptional_entry(page)) {
294 clear_exceptional_entry(mapping, index, page);
295 continue;
296 }
297
298 if (!trylock_page(page))
299 continue;
300 WARN_ON(page->index != index);
301 if (PageWriteback(page)) {
302 unlock_page(page);
303 continue;
304 }
305 truncate_inode_page(mapping, page);
306 unlock_page(page);
307 }
308 pagevec_remove_exceptionals(&pvec);
309 pagevec_release(&pvec);
310 mem_cgroup_uncharge_end();
311 cond_resched();
312 index++;
313 }
314
315 if (partial_start) {
316 struct page *page = find_lock_page(mapping, start - 1);
317 if (page) {
318 unsigned int top = PAGE_CACHE_SIZE;
319 if (start > end) {
320 /* Truncation within a single page */
321 top = partial_end;
322 partial_end = 0;
323 }
324 wait_on_page_writeback(page);
325 zero_user_segment(page, partial_start, top);
326 cleancache_invalidate_page(mapping, page);
327 if (page_has_private(page))
328 do_invalidatepage(page, partial_start,
329 top - partial_start);
330 unlock_page(page);
331 page_cache_release(page);
332 }
333 }
334 if (partial_end) {
335 struct page *page = find_lock_page(mapping, end);
336 if (page) {
337 wait_on_page_writeback(page);
338 zero_user_segment(page, 0, partial_end);
339 cleancache_invalidate_page(mapping, page);
340 if (page_has_private(page))
341 do_invalidatepage(page, 0,
342 partial_end);
343 unlock_page(page);
344 page_cache_release(page);
345 }
346 }
347 /*
348 * If the truncation happened within a single page no pages
349 * will be released, just zeroed, so we can bail out now.
350 */
351 if (start >= end)
352 return;
353
354 index = start;
355 for ( ; ; ) {
356 cond_resched();
357 if (!pagevec_lookup_entries(&pvec, mapping, index,
358 min(end - index, (pgoff_t)PAGEVEC_SIZE),
359 indices)) {
360 if (index == start)
361 break;
362 index = start;
363 continue;
364 }
365 if (index == start && indices[0] >= end) {
366 pagevec_remove_exceptionals(&pvec);
367 pagevec_release(&pvec);
368 break;
369 }
370 mem_cgroup_uncharge_start();
371 for (i = 0; i < pagevec_count(&pvec); i++) {
372 struct page *page = pvec.pages[i];
373
374 /* We rely upon deletion not changing page->index */
375 index = indices[i];
376 if (index >= end)
377 break;
378
379 if (radix_tree_exceptional_entry(page)) {
380 clear_exceptional_entry(mapping, index, page);
381 continue;
382 }
383
384 lock_page(page);
385 WARN_ON(page->index != index);
386 wait_on_page_writeback(page);
387 truncate_inode_page(mapping, page);
388 unlock_page(page);
389 }
390 pagevec_remove_exceptionals(&pvec);
391 pagevec_release(&pvec);
392 mem_cgroup_uncharge_end();
393 index++;
394 }
395 cleancache_invalidate_inode(mapping);
396}
397EXPORT_SYMBOL(truncate_inode_pages_range);
398
399/**
400 * truncate_inode_pages - truncate *all* the pages from an offset
401 * @mapping: mapping to truncate
402 * @lstart: offset from which to truncate
403 *
404 * Called under (and serialised by) inode->i_mutex.
405 *
406 * Note: When this function returns, there can be a page in the process of
407 * deletion (inside __delete_from_page_cache()) in the specified range. Thus
408 * mapping->nrpages can be non-zero when this function returns even after
409 * truncation of the whole mapping.
410 */
411void truncate_inode_pages(struct address_space *mapping, loff_t lstart)
412{
413 truncate_inode_pages_range(mapping, lstart, (loff_t)-1);
414}
415EXPORT_SYMBOL(truncate_inode_pages);
416
417/**
418 * truncate_inode_pages_final - truncate *all* pages before inode dies
419 * @mapping: mapping to truncate
420 *
421 * Called under (and serialized by) inode->i_mutex.
422 *
423 * Filesystems have to use this in the .evict_inode path to inform the
424 * VM that this is the final truncate and the inode is going away.
425 */
426void truncate_inode_pages_final(struct address_space *mapping)
427{
428 unsigned long nrshadows;
429 unsigned long nrpages;
430
431 /*
432 * Page reclaim can not participate in regular inode lifetime
433 * management (can't call iput()) and thus can race with the
434 * inode teardown. Tell it when the address space is exiting,
435 * so that it does not install eviction information after the
436 * final truncate has begun.
437 */
438 mapping_set_exiting(mapping);
439
440 /*
441 * When reclaim installs eviction entries, it increases
442 * nrshadows first, then decreases nrpages. Make sure we see
443 * this in the right order or we might miss an entry.
444 */
445 nrpages = mapping->nrpages;
446 smp_rmb();
447 nrshadows = mapping->nrshadows;
448
449 if (nrpages || nrshadows) {
450 /*
451 * As truncation uses a lockless tree lookup, cycle
452 * the tree lock to make sure any ongoing tree
453 * modification that does not see AS_EXITING is
454 * completed before starting the final truncate.
455 */
456 spin_lock_irq(&mapping->tree_lock);
457 spin_unlock_irq(&mapping->tree_lock);
458
459 truncate_inode_pages(mapping, 0);
460 }
461}
462EXPORT_SYMBOL(truncate_inode_pages_final);
463
464/**
465 * invalidate_mapping_pages - Invalidate all the unlocked pages of one inode
466 * @mapping: the address_space which holds the pages to invalidate
467 * @start: the offset 'from' which to invalidate
468 * @end: the offset 'to' which to invalidate (inclusive)
469 *
470 * This function only removes the unlocked pages, if you want to
471 * remove all the pages of one inode, you must call truncate_inode_pages.
472 *
473 * invalidate_mapping_pages() will not block on IO activity. It will not
474 * invalidate pages which are dirty, locked, under writeback or mapped into
475 * pagetables.
476 */
477unsigned long invalidate_mapping_pages(struct address_space *mapping,
478 pgoff_t start, pgoff_t end)
479{
480 pgoff_t indices[PAGEVEC_SIZE];
481 struct pagevec pvec;
482 pgoff_t index = start;
483 unsigned long ret;
484 unsigned long count = 0;
485 int i;
486
487 pagevec_init(&pvec, 0);
488 while (index <= end && pagevec_lookup_entries(&pvec, mapping, index,
489 min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1,
490 indices)) {
491 mem_cgroup_uncharge_start();
492 for (i = 0; i < pagevec_count(&pvec); i++) {
493 struct page *page = pvec.pages[i];
494
495 /* We rely upon deletion not changing page->index */
496 index = indices[i];
497 if (index > end)
498 break;
499
500 if (radix_tree_exceptional_entry(page)) {
501 clear_exceptional_entry(mapping, index, page);
502 continue;
503 }
504
505 if (!trylock_page(page))
506 continue;
507 WARN_ON(page->index != index);
508 ret = invalidate_inode_page(page);
509 unlock_page(page);
510 /*
511 * Invalidation is a hint that the page is no longer
512 * of interest and try to speed up its reclaim.
513 */
514 if (!ret)
515 deactivate_page(page);
516 count += ret;
517 }
518 pagevec_remove_exceptionals(&pvec);
519 pagevec_release(&pvec);
520 mem_cgroup_uncharge_end();
521 cond_resched();
522 index++;
523 }
524 return count;
525}
526EXPORT_SYMBOL(invalidate_mapping_pages);
527
528/*
529 * This is like invalidate_complete_page(), except it ignores the page's
530 * refcount. We do this because invalidate_inode_pages2() needs stronger
531 * invalidation guarantees, and cannot afford to leave pages behind because
532 * shrink_page_list() has a temp ref on them, or because they're transiently
533 * sitting in the lru_cache_add() pagevecs.
534 */
535static int
536invalidate_complete_page2(struct address_space *mapping, struct page *page)
537{
538 if (page->mapping != mapping)
539 return 0;
540
541 if (page_has_private(page) && !try_to_release_page(page, GFP_KERNEL))
542 return 0;
543
544 spin_lock_irq(&mapping->tree_lock);
545 if (PageDirty(page))
546 goto failed;
547
548 BUG_ON(page_has_private(page));
549 __delete_from_page_cache(page, NULL);
550 spin_unlock_irq(&mapping->tree_lock);
551 mem_cgroup_uncharge_cache_page(page);
552
553 if (mapping->a_ops->freepage)
554 mapping->a_ops->freepage(page);
555
556 page_cache_release(page); /* pagecache ref */
557 return 1;
558failed:
559 spin_unlock_irq(&mapping->tree_lock);
560 return 0;
561}
562
563static int do_launder_page(struct address_space *mapping, struct page *page)
564{
565 if (!PageDirty(page))
566 return 0;
567 if (page->mapping != mapping || mapping->a_ops->launder_page == NULL)
568 return 0;
569 return mapping->a_ops->launder_page(page);
570}
571
572/**
573 * invalidate_inode_pages2_range - remove range of pages from an address_space
574 * @mapping: the address_space
575 * @start: the page offset 'from' which to invalidate
576 * @end: the page offset 'to' which to invalidate (inclusive)
577 *
578 * Any pages which are found to be mapped into pagetables are unmapped prior to
579 * invalidation.
580 *
581 * Returns -EBUSY if any pages could not be invalidated.
582 */
583int invalidate_inode_pages2_range(struct address_space *mapping,
584 pgoff_t start, pgoff_t end)
585{
586 pgoff_t indices[PAGEVEC_SIZE];
587 struct pagevec pvec;
588 pgoff_t index;
589 int i;
590 int ret = 0;
591 int ret2 = 0;
592 int did_range_unmap = 0;
593
594 cleancache_invalidate_inode(mapping);
595 pagevec_init(&pvec, 0);
596 index = start;
597 while (index <= end && pagevec_lookup_entries(&pvec, mapping, index,
598 min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1,
599 indices)) {
600 mem_cgroup_uncharge_start();
601 for (i = 0; i < pagevec_count(&pvec); i++) {
602 struct page *page = pvec.pages[i];
603
604 /* We rely upon deletion not changing page->index */
605 index = indices[i];
606 if (index > end)
607 break;
608
609 if (radix_tree_exceptional_entry(page)) {
610 clear_exceptional_entry(mapping, index, page);
611 continue;
612 }
613
614 lock_page(page);
615 WARN_ON(page->index != index);
616 if (page->mapping != mapping) {
617 unlock_page(page);
618 continue;
619 }
620 wait_on_page_writeback(page);
621 if (page_mapped(page)) {
622 if (!did_range_unmap) {
623 /*
624 * Zap the rest of the file in one hit.
625 */
626 unmap_mapping_range(mapping,
627 (loff_t)index << PAGE_CACHE_SHIFT,
628 (loff_t)(1 + end - index)
629 << PAGE_CACHE_SHIFT,
630 0);
631 did_range_unmap = 1;
632 } else {
633 /*
634 * Just zap this page
635 */
636 unmap_mapping_range(mapping,
637 (loff_t)index << PAGE_CACHE_SHIFT,
638 PAGE_CACHE_SIZE, 0);
639 }
640 }
641 BUG_ON(page_mapped(page));
642 ret2 = do_launder_page(mapping, page);
643 if (ret2 == 0) {
644 if (!invalidate_complete_page2(mapping, page))
645 ret2 = -EBUSY;
646 }
647 if (ret2 < 0)
648 ret = ret2;
649 unlock_page(page);
650 }
651 pagevec_remove_exceptionals(&pvec);
652 pagevec_release(&pvec);
653 mem_cgroup_uncharge_end();
654 cond_resched();
655 index++;
656 }
657 cleancache_invalidate_inode(mapping);
658 return ret;
659}
660EXPORT_SYMBOL_GPL(invalidate_inode_pages2_range);
661
662/**
663 * invalidate_inode_pages2 - remove all pages from an address_space
664 * @mapping: the address_space
665 *
666 * Any pages which are found to be mapped into pagetables are unmapped prior to
667 * invalidation.
668 *
669 * Returns -EBUSY if any pages could not be invalidated.
670 */
671int invalidate_inode_pages2(struct address_space *mapping)
672{
673 return invalidate_inode_pages2_range(mapping, 0, -1);
674}
675EXPORT_SYMBOL_GPL(invalidate_inode_pages2);
676
677/**
678 * truncate_pagecache - unmap and remove pagecache that has been truncated
679 * @inode: inode
680 * @newsize: new file size
681 *
682 * inode's new i_size must already be written before truncate_pagecache
683 * is called.
684 *
685 * This function should typically be called before the filesystem
686 * releases resources associated with the freed range (eg. deallocates
687 * blocks). This way, pagecache will always stay logically coherent
688 * with on-disk format, and the filesystem would not have to deal with
689 * situations such as writepage being called for a page that has already
690 * had its underlying blocks deallocated.
691 */
692void truncate_pagecache(struct inode *inode, loff_t newsize)
693{
694 struct address_space *mapping = inode->i_mapping;
695 loff_t holebegin = round_up(newsize, PAGE_SIZE);
696
697 /*
698 * unmap_mapping_range is called twice, first simply for
699 * efficiency so that truncate_inode_pages does fewer
700 * single-page unmaps. However after this first call, and
701 * before truncate_inode_pages finishes, it is possible for
702 * private pages to be COWed, which remain after
703 * truncate_inode_pages finishes, hence the second
704 * unmap_mapping_range call must be made for correctness.
705 */
706 unmap_mapping_range(mapping, holebegin, 0, 1);
707 truncate_inode_pages(mapping, newsize);
708 unmap_mapping_range(mapping, holebegin, 0, 1);
709}
710EXPORT_SYMBOL(truncate_pagecache);
711
712/**
713 * truncate_setsize - update inode and pagecache for a new file size
714 * @inode: inode
715 * @newsize: new file size
716 *
717 * truncate_setsize updates i_size and performs pagecache truncation (if
718 * necessary) to @newsize. It will be typically be called from the filesystem's
719 * setattr function when ATTR_SIZE is passed in.
720 *
721 * Must be called with inode_mutex held and before all filesystem specific
722 * block truncation has been performed.
723 */
724void truncate_setsize(struct inode *inode, loff_t newsize)
725{
726 i_size_write(inode, newsize);
727 truncate_pagecache(inode, newsize);
728}
729EXPORT_SYMBOL(truncate_setsize);
730
731/**
732 * truncate_pagecache_range - unmap and remove pagecache that is hole-punched
733 * @inode: inode
734 * @lstart: offset of beginning of hole
735 * @lend: offset of last byte of hole
736 *
737 * This function should typically be called before the filesystem
738 * releases resources associated with the freed range (eg. deallocates
739 * blocks). This way, pagecache will always stay logically coherent
740 * with on-disk format, and the filesystem would not have to deal with
741 * situations such as writepage being called for a page that has already
742 * had its underlying blocks deallocated.
743 */
744void truncate_pagecache_range(struct inode *inode, loff_t lstart, loff_t lend)
745{
746 struct address_space *mapping = inode->i_mapping;
747 loff_t unmap_start = round_up(lstart, PAGE_SIZE);
748 loff_t unmap_end = round_down(1 + lend, PAGE_SIZE) - 1;
749 /*
750 * This rounding is currently just for example: unmap_mapping_range
751 * expands its hole outwards, whereas we want it to contract the hole
752 * inwards. However, existing callers of truncate_pagecache_range are
753 * doing their own page rounding first. Note that unmap_mapping_range
754 * allows holelen 0 for all, and we allow lend -1 for end of file.
755 */
756
757 /*
758 * Unlike in truncate_pagecache, unmap_mapping_range is called only
759 * once (before truncating pagecache), and without "even_cows" flag:
760 * hole-punching should not remove private COWed pages from the hole.
761 */
762 if ((u64)unmap_end > (u64)unmap_start)
763 unmap_mapping_range(mapping, unmap_start,
764 1 + unmap_end - unmap_start, 0);
765 truncate_inode_pages_range(mapping, lstart, lend);
766}
767EXPORT_SYMBOL(truncate_pagecache_range);