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