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