xref: /linux/mm/truncate.c (revision e9de25dda359c9272998daddeae7788376a44e41)
11da177e4SLinus Torvalds /*
21da177e4SLinus Torvalds  * mm/truncate.c - code for taking down pages from address_spaces
31da177e4SLinus Torvalds  *
41da177e4SLinus Torvalds  * Copyright (C) 2002, Linus Torvalds
51da177e4SLinus Torvalds  *
6e1f8e874SFrancois Cami  * 10Sep2002	Andrew Morton
71da177e4SLinus Torvalds  *		Initial version.
81da177e4SLinus Torvalds  */
91da177e4SLinus Torvalds 
101da177e4SLinus Torvalds #include <linux/kernel.h>
114af3c9ccSAlexey Dobriyan #include <linux/backing-dev.h>
121da177e4SLinus Torvalds #include <linux/mm.h>
130fd0e6b0SNick Piggin #include <linux/swap.h>
141da177e4SLinus Torvalds #include <linux/module.h>
151da177e4SLinus Torvalds #include <linux/pagemap.h>
1601f2705dSNate Diller #include <linux/highmem.h>
171da177e4SLinus Torvalds #include <linux/pagevec.h>
18e08748ceSAndrew Morton #include <linux/task_io_accounting_ops.h>
191da177e4SLinus Torvalds #include <linux/buffer_head.h>	/* grr. try_to_release_page,
20aaa4059bSJan Kara 				   do_invalidatepage */
21ba470de4SRik van Riel #include "internal.h"
221da177e4SLinus Torvalds 
231da177e4SLinus Torvalds 
24cf9a2ae8SDavid Howells /**
2528bc44d7SFengguang Wu  * do_invalidatepage - invalidate part or all of a page
26cf9a2ae8SDavid Howells  * @page: the page which is affected
27cf9a2ae8SDavid Howells  * @offset: the index of the truncation point
28cf9a2ae8SDavid Howells  *
29cf9a2ae8SDavid Howells  * do_invalidatepage() is called when all or part of the page has become
30cf9a2ae8SDavid Howells  * invalidated by a truncate operation.
31cf9a2ae8SDavid Howells  *
32cf9a2ae8SDavid Howells  * do_invalidatepage() does not have to release all buffers, but it must
33cf9a2ae8SDavid Howells  * ensure that no dirty buffer is left outside @offset and that no I/O
34cf9a2ae8SDavid Howells  * is underway against any of the blocks which are outside the truncation
35cf9a2ae8SDavid Howells  * point.  Because the caller is about to free (and possibly reuse) those
36cf9a2ae8SDavid Howells  * blocks on-disk.
37cf9a2ae8SDavid Howells  */
38cf9a2ae8SDavid Howells void do_invalidatepage(struct page *page, unsigned long offset)
39cf9a2ae8SDavid Howells {
40cf9a2ae8SDavid Howells 	void (*invalidatepage)(struct page *, unsigned long);
41cf9a2ae8SDavid Howells 	invalidatepage = page->mapping->a_ops->invalidatepage;
429361401eSDavid Howells #ifdef CONFIG_BLOCK
43cf9a2ae8SDavid Howells 	if (!invalidatepage)
44cf9a2ae8SDavid Howells 		invalidatepage = block_invalidatepage;
459361401eSDavid Howells #endif
46cf9a2ae8SDavid Howells 	if (invalidatepage)
47cf9a2ae8SDavid Howells 		(*invalidatepage)(page, offset);
48cf9a2ae8SDavid Howells }
49cf9a2ae8SDavid Howells 
501da177e4SLinus Torvalds static inline void truncate_partial_page(struct page *page, unsigned partial)
511da177e4SLinus Torvalds {
52eebd2aa3SChristoph Lameter 	zero_user_segment(page, partial, PAGE_CACHE_SIZE);
53266cf658SDavid Howells 	if (page_has_private(page))
541da177e4SLinus Torvalds 		do_invalidatepage(page, partial);
551da177e4SLinus Torvalds }
561da177e4SLinus Torvalds 
57ecdfc978SLinus Torvalds /*
58ecdfc978SLinus Torvalds  * This cancels just the dirty bit on the kernel page itself, it
59ecdfc978SLinus Torvalds  * does NOT actually remove dirty bits on any mmap's that may be
60ecdfc978SLinus Torvalds  * around. It also leaves the page tagged dirty, so any sync
61ecdfc978SLinus Torvalds  * activity will still find it on the dirty lists, and in particular,
62ecdfc978SLinus Torvalds  * clear_page_dirty_for_io() will still look at the dirty bits in
63ecdfc978SLinus Torvalds  * the VM.
64ecdfc978SLinus Torvalds  *
65ecdfc978SLinus Torvalds  * Doing this should *normally* only ever be done when a page
66ecdfc978SLinus Torvalds  * is truncated, and is not actually mapped anywhere at all. However,
67ecdfc978SLinus Torvalds  * fs/buffer.c does this when it notices that somebody has cleaned
68ecdfc978SLinus Torvalds  * out all the buffers on a page without actually doing it through
69ecdfc978SLinus Torvalds  * the VM. Can you say "ext3 is horribly ugly"? Tought you could.
70ecdfc978SLinus Torvalds  */
71fba2591bSLinus Torvalds void cancel_dirty_page(struct page *page, unsigned int account_size)
72fba2591bSLinus Torvalds {
738368e328SLinus Torvalds 	if (TestClearPageDirty(page)) {
748368e328SLinus Torvalds 		struct address_space *mapping = page->mapping;
758368e328SLinus Torvalds 		if (mapping && mapping_cap_account_dirty(mapping)) {
763e67c098SAndrew Morton 			dec_zone_page_state(page, NR_FILE_DIRTY);
77c9e51e41SPeter Zijlstra 			dec_bdi_stat(mapping->backing_dev_info,
78c9e51e41SPeter Zijlstra 					BDI_RECLAIMABLE);
798368e328SLinus Torvalds 			if (account_size)
80fba2591bSLinus Torvalds 				task_io_account_cancelled_write(account_size);
81fba2591bSLinus Torvalds 		}
823e67c098SAndrew Morton 	}
838368e328SLinus Torvalds }
848368e328SLinus Torvalds EXPORT_SYMBOL(cancel_dirty_page);
85fba2591bSLinus Torvalds 
861da177e4SLinus Torvalds /*
871da177e4SLinus Torvalds  * If truncate cannot remove the fs-private metadata from the page, the page
8862e1c553SShaohua Li  * becomes orphaned.  It will be left on the LRU and may even be mapped into
8954cb8821SNick Piggin  * user pagetables if we're racing with filemap_fault().
901da177e4SLinus Torvalds  *
911da177e4SLinus Torvalds  * We need to bale out if page->mapping is no longer equal to the original
921da177e4SLinus Torvalds  * mapping.  This happens a) when the VM reclaimed the page while we waited on
93fc0ecff6SAndrew Morton  * its lock, b) when a concurrent invalidate_mapping_pages got there first and
941da177e4SLinus Torvalds  * c) when tmpfs swizzles a page between a tmpfs inode and swapper_space.
951da177e4SLinus Torvalds  */
96750b4987SNick Piggin static int
971da177e4SLinus Torvalds truncate_complete_page(struct address_space *mapping, struct page *page)
981da177e4SLinus Torvalds {
991da177e4SLinus Torvalds 	if (page->mapping != mapping)
100750b4987SNick Piggin 		return -EIO;
1011da177e4SLinus Torvalds 
102266cf658SDavid Howells 	if (page_has_private(page))
1031da177e4SLinus Torvalds 		do_invalidatepage(page, 0);
1041da177e4SLinus Torvalds 
105a2b34564SBjorn Steinbrink 	cancel_dirty_page(page, PAGE_CACHE_SIZE);
106a2b34564SBjorn Steinbrink 
107ba470de4SRik van Riel 	clear_page_mlock(page);
108787d2214SNick Piggin 	remove_from_page_cache(page);
1091da177e4SLinus Torvalds 	ClearPageMappedToDisk(page);
1101da177e4SLinus Torvalds 	page_cache_release(page);	/* pagecache ref */
111750b4987SNick Piggin 	return 0;
1121da177e4SLinus Torvalds }
1131da177e4SLinus Torvalds 
1141da177e4SLinus Torvalds /*
115fc0ecff6SAndrew Morton  * This is for invalidate_mapping_pages().  That function can be called at
1161da177e4SLinus Torvalds  * any time, and is not supposed to throw away dirty pages.  But pages can
1170fd0e6b0SNick Piggin  * be marked dirty at any time too, so use remove_mapping which safely
1180fd0e6b0SNick Piggin  * discards clean, unused pages.
1191da177e4SLinus Torvalds  *
1201da177e4SLinus Torvalds  * Returns non-zero if the page was successfully invalidated.
1211da177e4SLinus Torvalds  */
1221da177e4SLinus Torvalds static int
1231da177e4SLinus Torvalds invalidate_complete_page(struct address_space *mapping, struct page *page)
1241da177e4SLinus Torvalds {
1250fd0e6b0SNick Piggin 	int ret;
1260fd0e6b0SNick Piggin 
1271da177e4SLinus Torvalds 	if (page->mapping != mapping)
1281da177e4SLinus Torvalds 		return 0;
1291da177e4SLinus Torvalds 
130266cf658SDavid Howells 	if (page_has_private(page) && !try_to_release_page(page, 0))
1311da177e4SLinus Torvalds 		return 0;
1321da177e4SLinus Torvalds 
133ba470de4SRik van Riel 	clear_page_mlock(page);
1340fd0e6b0SNick Piggin 	ret = remove_mapping(mapping, page);
1350fd0e6b0SNick Piggin 
1360fd0e6b0SNick Piggin 	return ret;
1371da177e4SLinus Torvalds }
1381da177e4SLinus Torvalds 
139750b4987SNick Piggin int truncate_inode_page(struct address_space *mapping, struct page *page)
140750b4987SNick Piggin {
141750b4987SNick Piggin 	if (page_mapped(page)) {
142750b4987SNick Piggin 		unmap_mapping_range(mapping,
143750b4987SNick Piggin 				   (loff_t)page->index << PAGE_CACHE_SHIFT,
144750b4987SNick Piggin 				   PAGE_CACHE_SIZE, 0);
145750b4987SNick Piggin 	}
146750b4987SNick Piggin 	return truncate_complete_page(mapping, page);
147750b4987SNick Piggin }
148750b4987SNick Piggin 
14983f78668SWu Fengguang /*
15025718736SAndi Kleen  * Used to get rid of pages on hardware memory corruption.
15125718736SAndi Kleen  */
15225718736SAndi Kleen int generic_error_remove_page(struct address_space *mapping, struct page *page)
15325718736SAndi Kleen {
15425718736SAndi Kleen 	if (!mapping)
15525718736SAndi Kleen 		return -EINVAL;
15625718736SAndi Kleen 	/*
15725718736SAndi Kleen 	 * Only punch for normal data pages for now.
15825718736SAndi Kleen 	 * Handling other types like directories would need more auditing.
15925718736SAndi Kleen 	 */
16025718736SAndi Kleen 	if (!S_ISREG(mapping->host->i_mode))
16125718736SAndi Kleen 		return -EIO;
16225718736SAndi Kleen 	return truncate_inode_page(mapping, page);
16325718736SAndi Kleen }
16425718736SAndi Kleen EXPORT_SYMBOL(generic_error_remove_page);
16525718736SAndi Kleen 
16625718736SAndi Kleen /*
16783f78668SWu Fengguang  * Safely invalidate one page from its pagecache mapping.
16883f78668SWu Fengguang  * It only drops clean, unused pages. The page must be locked.
16983f78668SWu Fengguang  *
17083f78668SWu Fengguang  * Returns 1 if the page is successfully invalidated, otherwise 0.
17183f78668SWu Fengguang  */
17283f78668SWu Fengguang int invalidate_inode_page(struct page *page)
17383f78668SWu Fengguang {
17483f78668SWu Fengguang 	struct address_space *mapping = page_mapping(page);
17583f78668SWu Fengguang 	if (!mapping)
17683f78668SWu Fengguang 		return 0;
17783f78668SWu Fengguang 	if (PageDirty(page) || PageWriteback(page))
17883f78668SWu Fengguang 		return 0;
17983f78668SWu Fengguang 	if (page_mapped(page))
18083f78668SWu Fengguang 		return 0;
18183f78668SWu Fengguang 	return invalidate_complete_page(mapping, page);
18283f78668SWu Fengguang }
18383f78668SWu Fengguang 
1841da177e4SLinus Torvalds /**
1850643245fSRandy Dunlap  * truncate_inode_pages - truncate range of pages specified by start & end byte offsets
1861da177e4SLinus Torvalds  * @mapping: mapping to truncate
1871da177e4SLinus Torvalds  * @lstart: offset from which to truncate
188d7339071SHans Reiser  * @lend: offset to which to truncate
1891da177e4SLinus Torvalds  *
190d7339071SHans Reiser  * Truncate the page cache, removing the pages that are between
191d7339071SHans Reiser  * specified offsets (and zeroing out partial page
192d7339071SHans Reiser  * (if lstart is not page aligned)).
1931da177e4SLinus Torvalds  *
1941da177e4SLinus Torvalds  * Truncate takes two passes - the first pass is nonblocking.  It will not
1951da177e4SLinus Torvalds  * block on page locks and it will not block on writeback.  The second pass
1961da177e4SLinus Torvalds  * will wait.  This is to prevent as much IO as possible in the affected region.
1971da177e4SLinus Torvalds  * The first pass will remove most pages, so the search cost of the second pass
1981da177e4SLinus Torvalds  * is low.
1991da177e4SLinus Torvalds  *
2001da177e4SLinus Torvalds  * When looking at page->index outside the page lock we need to be careful to
2011da177e4SLinus Torvalds  * copy it into a local to avoid races (it could change at any time).
2021da177e4SLinus Torvalds  *
2031da177e4SLinus Torvalds  * We pass down the cache-hot hint to the page freeing code.  Even if the
2041da177e4SLinus Torvalds  * mapping is large, it is probably the case that the final pages are the most
2051da177e4SLinus Torvalds  * recently touched, and freeing happens in ascending file offset order.
2061da177e4SLinus Torvalds  */
207d7339071SHans Reiser void truncate_inode_pages_range(struct address_space *mapping,
208d7339071SHans Reiser 				loff_t lstart, loff_t lend)
2091da177e4SLinus Torvalds {
2101da177e4SLinus Torvalds 	const pgoff_t start = (lstart + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
211d7339071SHans Reiser 	pgoff_t end;
2121da177e4SLinus Torvalds 	const unsigned partial = lstart & (PAGE_CACHE_SIZE - 1);
2131da177e4SLinus Torvalds 	struct pagevec pvec;
2141da177e4SLinus Torvalds 	pgoff_t next;
2151da177e4SLinus Torvalds 	int i;
2161da177e4SLinus Torvalds 
2171da177e4SLinus Torvalds 	if (mapping->nrpages == 0)
2181da177e4SLinus Torvalds 		return;
2191da177e4SLinus Torvalds 
220d7339071SHans Reiser 	BUG_ON((lend & (PAGE_CACHE_SIZE - 1)) != (PAGE_CACHE_SIZE - 1));
221d7339071SHans Reiser 	end = (lend >> PAGE_CACHE_SHIFT);
222d7339071SHans Reiser 
2231da177e4SLinus Torvalds 	pagevec_init(&pvec, 0);
2241da177e4SLinus Torvalds 	next = start;
225d7339071SHans Reiser 	while (next <= end &&
226d7339071SHans Reiser 	       pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
2271da177e4SLinus Torvalds 		for (i = 0; i < pagevec_count(&pvec); i++) {
2281da177e4SLinus Torvalds 			struct page *page = pvec.pages[i];
2291da177e4SLinus Torvalds 			pgoff_t page_index = page->index;
2301da177e4SLinus Torvalds 
231d7339071SHans Reiser 			if (page_index > end) {
232d7339071SHans Reiser 				next = page_index;
233d7339071SHans Reiser 				break;
234d7339071SHans Reiser 			}
235d7339071SHans Reiser 
2361da177e4SLinus Torvalds 			if (page_index > next)
2371da177e4SLinus Torvalds 				next = page_index;
2381da177e4SLinus Torvalds 			next++;
239529ae9aaSNick Piggin 			if (!trylock_page(page))
2401da177e4SLinus Torvalds 				continue;
2411da177e4SLinus Torvalds 			if (PageWriteback(page)) {
2421da177e4SLinus Torvalds 				unlock_page(page);
2431da177e4SLinus Torvalds 				continue;
2441da177e4SLinus Torvalds 			}
245750b4987SNick Piggin 			truncate_inode_page(mapping, page);
2461da177e4SLinus Torvalds 			unlock_page(page);
2471da177e4SLinus Torvalds 		}
2481da177e4SLinus Torvalds 		pagevec_release(&pvec);
2491da177e4SLinus Torvalds 		cond_resched();
2501da177e4SLinus Torvalds 	}
2511da177e4SLinus Torvalds 
2521da177e4SLinus Torvalds 	if (partial) {
2531da177e4SLinus Torvalds 		struct page *page = find_lock_page(mapping, start - 1);
2541da177e4SLinus Torvalds 		if (page) {
2551da177e4SLinus Torvalds 			wait_on_page_writeback(page);
2561da177e4SLinus Torvalds 			truncate_partial_page(page, partial);
2571da177e4SLinus Torvalds 			unlock_page(page);
2581da177e4SLinus Torvalds 			page_cache_release(page);
2591da177e4SLinus Torvalds 		}
2601da177e4SLinus Torvalds 	}
2611da177e4SLinus Torvalds 
2621da177e4SLinus Torvalds 	next = start;
2631da177e4SLinus Torvalds 	for ( ; ; ) {
2641da177e4SLinus Torvalds 		cond_resched();
2651da177e4SLinus Torvalds 		if (!pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
2661da177e4SLinus Torvalds 			if (next == start)
2671da177e4SLinus Torvalds 				break;
2681da177e4SLinus Torvalds 			next = start;
2691da177e4SLinus Torvalds 			continue;
2701da177e4SLinus Torvalds 		}
271d7339071SHans Reiser 		if (pvec.pages[0]->index > end) {
272d7339071SHans Reiser 			pagevec_release(&pvec);
273d7339071SHans Reiser 			break;
274d7339071SHans Reiser 		}
2751da177e4SLinus Torvalds 		for (i = 0; i < pagevec_count(&pvec); i++) {
2761da177e4SLinus Torvalds 			struct page *page = pvec.pages[i];
2771da177e4SLinus Torvalds 
278d7339071SHans Reiser 			if (page->index > end)
279d7339071SHans Reiser 				break;
2801da177e4SLinus Torvalds 			lock_page(page);
2811da177e4SLinus Torvalds 			wait_on_page_writeback(page);
282750b4987SNick Piggin 			truncate_inode_page(mapping, page);
2831da177e4SLinus Torvalds 			if (page->index > next)
2841da177e4SLinus Torvalds 				next = page->index;
2851da177e4SLinus Torvalds 			next++;
2861da177e4SLinus Torvalds 			unlock_page(page);
2871da177e4SLinus Torvalds 		}
2881da177e4SLinus Torvalds 		pagevec_release(&pvec);
2891da177e4SLinus Torvalds 	}
2901da177e4SLinus Torvalds }
291d7339071SHans Reiser EXPORT_SYMBOL(truncate_inode_pages_range);
2921da177e4SLinus Torvalds 
293d7339071SHans Reiser /**
294d7339071SHans Reiser  * truncate_inode_pages - truncate *all* the pages from an offset
295d7339071SHans Reiser  * @mapping: mapping to truncate
296d7339071SHans Reiser  * @lstart: offset from which to truncate
297d7339071SHans Reiser  *
2981b1dcc1bSJes Sorensen  * Called under (and serialised by) inode->i_mutex.
299d7339071SHans Reiser  */
300d7339071SHans Reiser void truncate_inode_pages(struct address_space *mapping, loff_t lstart)
301d7339071SHans Reiser {
302d7339071SHans Reiser 	truncate_inode_pages_range(mapping, lstart, (loff_t)-1);
303d7339071SHans Reiser }
3041da177e4SLinus Torvalds EXPORT_SYMBOL(truncate_inode_pages);
3051da177e4SLinus Torvalds 
30628697355SMike Waychison /**
30728697355SMike Waychison  * invalidate_mapping_pages - Invalidate all the unlocked pages of one inode
30828697355SMike Waychison  * @mapping: the address_space which holds the pages to invalidate
30928697355SMike Waychison  * @start: the offset 'from' which to invalidate
31028697355SMike Waychison  * @end: the offset 'to' which to invalidate (inclusive)
31128697355SMike Waychison  *
31228697355SMike Waychison  * This function only removes the unlocked pages, if you want to
31328697355SMike Waychison  * remove all the pages of one inode, you must call truncate_inode_pages.
31428697355SMike Waychison  *
31528697355SMike Waychison  * invalidate_mapping_pages() will not block on IO activity. It will not
31628697355SMike Waychison  * invalidate pages which are dirty, locked, under writeback or mapped into
31728697355SMike Waychison  * pagetables.
31828697355SMike Waychison  */
31928697355SMike Waychison unsigned long invalidate_mapping_pages(struct address_space *mapping,
32028697355SMike Waychison 				       pgoff_t start, pgoff_t end)
3211da177e4SLinus Torvalds {
3221da177e4SLinus Torvalds 	struct pagevec pvec;
3231da177e4SLinus Torvalds 	pgoff_t next = start;
3241da177e4SLinus Torvalds 	unsigned long ret = 0;
3251da177e4SLinus Torvalds 	int i;
3261da177e4SLinus Torvalds 
3271da177e4SLinus Torvalds 	pagevec_init(&pvec, 0);
3281da177e4SLinus Torvalds 	while (next <= end &&
3291da177e4SLinus Torvalds 			pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
3301da177e4SLinus Torvalds 		for (i = 0; i < pagevec_count(&pvec); i++) {
3311da177e4SLinus Torvalds 			struct page *page = pvec.pages[i];
332e0f23603SNeilBrown 			pgoff_t index;
333e0f23603SNeilBrown 			int lock_failed;
3341da177e4SLinus Torvalds 
335529ae9aaSNick Piggin 			lock_failed = !trylock_page(page);
336e0f23603SNeilBrown 
337e0f23603SNeilBrown 			/*
338e0f23603SNeilBrown 			 * We really shouldn't be looking at the ->index of an
339e0f23603SNeilBrown 			 * unlocked page.  But we're not allowed to lock these
340e0f23603SNeilBrown 			 * pages.  So we rely upon nobody altering the ->index
341e0f23603SNeilBrown 			 * of this (pinned-by-us) page.
342e0f23603SNeilBrown 			 */
343e0f23603SNeilBrown 			index = page->index;
344e0f23603SNeilBrown 			if (index > next)
345e0f23603SNeilBrown 				next = index;
3461da177e4SLinus Torvalds 			next++;
347e0f23603SNeilBrown 			if (lock_failed)
3481da177e4SLinus Torvalds 				continue;
349e0f23603SNeilBrown 
35083f78668SWu Fengguang 			ret += invalidate_inode_page(page);
35183f78668SWu Fengguang 
3521da177e4SLinus Torvalds 			unlock_page(page);
3531da177e4SLinus Torvalds 			if (next > end)
3541da177e4SLinus Torvalds 				break;
3551da177e4SLinus Torvalds 		}
3561da177e4SLinus Torvalds 		pagevec_release(&pvec);
357fc9a07e7SAndrew Morton 		cond_resched();
3581da177e4SLinus Torvalds 	}
3591da177e4SLinus Torvalds 	return ret;
3601da177e4SLinus Torvalds }
36154bc4855SAnton Altaparmakov EXPORT_SYMBOL(invalidate_mapping_pages);
3621da177e4SLinus Torvalds 
363bd4c8ce4SAndrew Morton /*
364bd4c8ce4SAndrew Morton  * This is like invalidate_complete_page(), except it ignores the page's
365bd4c8ce4SAndrew Morton  * refcount.  We do this because invalidate_inode_pages2() needs stronger
366bd4c8ce4SAndrew Morton  * invalidation guarantees, and cannot afford to leave pages behind because
3672706a1b8SAnderson Briglia  * shrink_page_list() has a temp ref on them, or because they're transiently
3682706a1b8SAnderson Briglia  * sitting in the lru_cache_add() pagevecs.
369bd4c8ce4SAndrew Morton  */
370bd4c8ce4SAndrew Morton static int
371bd4c8ce4SAndrew Morton invalidate_complete_page2(struct address_space *mapping, struct page *page)
372bd4c8ce4SAndrew Morton {
373bd4c8ce4SAndrew Morton 	if (page->mapping != mapping)
374bd4c8ce4SAndrew Morton 		return 0;
375bd4c8ce4SAndrew Morton 
376266cf658SDavid Howells 	if (page_has_private(page) && !try_to_release_page(page, GFP_KERNEL))
377bd4c8ce4SAndrew Morton 		return 0;
378bd4c8ce4SAndrew Morton 
37919fd6231SNick Piggin 	spin_lock_irq(&mapping->tree_lock);
380bd4c8ce4SAndrew Morton 	if (PageDirty(page))
381bd4c8ce4SAndrew Morton 		goto failed;
382bd4c8ce4SAndrew Morton 
383ba470de4SRik van Riel 	clear_page_mlock(page);
384266cf658SDavid Howells 	BUG_ON(page_has_private(page));
385bd4c8ce4SAndrew Morton 	__remove_from_page_cache(page);
38619fd6231SNick Piggin 	spin_unlock_irq(&mapping->tree_lock);
387e767e056SDaisuke Nishimura 	mem_cgroup_uncharge_cache_page(page);
388bd4c8ce4SAndrew Morton 	page_cache_release(page);	/* pagecache ref */
389bd4c8ce4SAndrew Morton 	return 1;
390bd4c8ce4SAndrew Morton failed:
39119fd6231SNick Piggin 	spin_unlock_irq(&mapping->tree_lock);
392bd4c8ce4SAndrew Morton 	return 0;
393bd4c8ce4SAndrew Morton }
394bd4c8ce4SAndrew Morton 
395e3db7691STrond Myklebust static int do_launder_page(struct address_space *mapping, struct page *page)
396e3db7691STrond Myklebust {
397e3db7691STrond Myklebust 	if (!PageDirty(page))
398e3db7691STrond Myklebust 		return 0;
399e3db7691STrond Myklebust 	if (page->mapping != mapping || mapping->a_ops->launder_page == NULL)
400e3db7691STrond Myklebust 		return 0;
401e3db7691STrond Myklebust 	return mapping->a_ops->launder_page(page);
402e3db7691STrond Myklebust }
403e3db7691STrond Myklebust 
4041da177e4SLinus Torvalds /**
4051da177e4SLinus Torvalds  * invalidate_inode_pages2_range - remove range of pages from an address_space
40667be2dd1SMartin Waitz  * @mapping: the address_space
4071da177e4SLinus Torvalds  * @start: the page offset 'from' which to invalidate
4081da177e4SLinus Torvalds  * @end: the page offset 'to' which to invalidate (inclusive)
4091da177e4SLinus Torvalds  *
4101da177e4SLinus Torvalds  * Any pages which are found to be mapped into pagetables are unmapped prior to
4111da177e4SLinus Torvalds  * invalidation.
4121da177e4SLinus Torvalds  *
4136ccfa806SHisashi Hifumi  * Returns -EBUSY if any pages could not be invalidated.
4141da177e4SLinus Torvalds  */
4151da177e4SLinus Torvalds int invalidate_inode_pages2_range(struct address_space *mapping,
4161da177e4SLinus Torvalds 				  pgoff_t start, pgoff_t end)
4171da177e4SLinus Torvalds {
4181da177e4SLinus Torvalds 	struct pagevec pvec;
4191da177e4SLinus Torvalds 	pgoff_t next;
4201da177e4SLinus Torvalds 	int i;
4211da177e4SLinus Torvalds 	int ret = 0;
4220dd1334fSHisashi Hifumi 	int ret2 = 0;
4231da177e4SLinus Torvalds 	int did_range_unmap = 0;
4241da177e4SLinus Torvalds 	int wrapped = 0;
4251da177e4SLinus Torvalds 
4261da177e4SLinus Torvalds 	pagevec_init(&pvec, 0);
4271da177e4SLinus Torvalds 	next = start;
4287b965e08STrond Myklebust 	while (next <= end && !wrapped &&
4291da177e4SLinus Torvalds 		pagevec_lookup(&pvec, mapping, next,
4301da177e4SLinus Torvalds 			min(end - next, (pgoff_t)PAGEVEC_SIZE - 1) + 1)) {
4317b965e08STrond Myklebust 		for (i = 0; i < pagevec_count(&pvec); i++) {
4321da177e4SLinus Torvalds 			struct page *page = pvec.pages[i];
4331da177e4SLinus Torvalds 			pgoff_t page_index;
4341da177e4SLinus Torvalds 
4351da177e4SLinus Torvalds 			lock_page(page);
4361da177e4SLinus Torvalds 			if (page->mapping != mapping) {
4371da177e4SLinus Torvalds 				unlock_page(page);
4381da177e4SLinus Torvalds 				continue;
4391da177e4SLinus Torvalds 			}
4401da177e4SLinus Torvalds 			page_index = page->index;
4411da177e4SLinus Torvalds 			next = page_index + 1;
4421da177e4SLinus Torvalds 			if (next == 0)
4431da177e4SLinus Torvalds 				wrapped = 1;
4441da177e4SLinus Torvalds 			if (page_index > end) {
4451da177e4SLinus Torvalds 				unlock_page(page);
4461da177e4SLinus Torvalds 				break;
4471da177e4SLinus Torvalds 			}
4481da177e4SLinus Torvalds 			wait_on_page_writeback(page);
449d00806b1SNick Piggin 			if (page_mapped(page)) {
4501da177e4SLinus Torvalds 				if (!did_range_unmap) {
4511da177e4SLinus Torvalds 					/*
4521da177e4SLinus Torvalds 					 * Zap the rest of the file in one hit.
4531da177e4SLinus Torvalds 					 */
4541da177e4SLinus Torvalds 					unmap_mapping_range(mapping,
455479ef592SOleg Drokin 					   (loff_t)page_index<<PAGE_CACHE_SHIFT,
456479ef592SOleg Drokin 					   (loff_t)(end - page_index + 1)
4571da177e4SLinus Torvalds 							<< PAGE_CACHE_SHIFT,
4581da177e4SLinus Torvalds 					    0);
4591da177e4SLinus Torvalds 					did_range_unmap = 1;
4601da177e4SLinus Torvalds 				} else {
4611da177e4SLinus Torvalds 					/*
4621da177e4SLinus Torvalds 					 * Just zap this page
4631da177e4SLinus Torvalds 					 */
4641da177e4SLinus Torvalds 					unmap_mapping_range(mapping,
465479ef592SOleg Drokin 					  (loff_t)page_index<<PAGE_CACHE_SHIFT,
4661da177e4SLinus Torvalds 					  PAGE_CACHE_SIZE, 0);
4671da177e4SLinus Torvalds 				}
4681da177e4SLinus Torvalds 			}
469d00806b1SNick Piggin 			BUG_ON(page_mapped(page));
4700dd1334fSHisashi Hifumi 			ret2 = do_launder_page(mapping, page);
4710dd1334fSHisashi Hifumi 			if (ret2 == 0) {
4720dd1334fSHisashi Hifumi 				if (!invalidate_complete_page2(mapping, page))
4736ccfa806SHisashi Hifumi 					ret2 = -EBUSY;
4740dd1334fSHisashi Hifumi 			}
4750dd1334fSHisashi Hifumi 			if (ret2 < 0)
4760dd1334fSHisashi Hifumi 				ret = ret2;
4771da177e4SLinus Torvalds 			unlock_page(page);
4781da177e4SLinus Torvalds 		}
4791da177e4SLinus Torvalds 		pagevec_release(&pvec);
4801da177e4SLinus Torvalds 		cond_resched();
4811da177e4SLinus Torvalds 	}
4821da177e4SLinus Torvalds 	return ret;
4831da177e4SLinus Torvalds }
4841da177e4SLinus Torvalds EXPORT_SYMBOL_GPL(invalidate_inode_pages2_range);
4851da177e4SLinus Torvalds 
4861da177e4SLinus Torvalds /**
4871da177e4SLinus Torvalds  * invalidate_inode_pages2 - remove all pages from an address_space
48867be2dd1SMartin Waitz  * @mapping: the address_space
4891da177e4SLinus Torvalds  *
4901da177e4SLinus Torvalds  * Any pages which are found to be mapped into pagetables are unmapped prior to
4911da177e4SLinus Torvalds  * invalidation.
4921da177e4SLinus Torvalds  *
493*e9de25ddSPeng Tao  * Returns -EBUSY if any pages could not be invalidated.
4941da177e4SLinus Torvalds  */
4951da177e4SLinus Torvalds int invalidate_inode_pages2(struct address_space *mapping)
4961da177e4SLinus Torvalds {
4971da177e4SLinus Torvalds 	return invalidate_inode_pages2_range(mapping, 0, -1);
4981da177e4SLinus Torvalds }
4991da177e4SLinus Torvalds EXPORT_SYMBOL_GPL(invalidate_inode_pages2);
50025d9e2d1Snpiggin@suse.de 
50125d9e2d1Snpiggin@suse.de /**
50225d9e2d1Snpiggin@suse.de  * truncate_pagecache - unmap and remove pagecache that has been truncated
50325d9e2d1Snpiggin@suse.de  * @inode: inode
50425d9e2d1Snpiggin@suse.de  * @old: old file offset
50525d9e2d1Snpiggin@suse.de  * @new: new file offset
50625d9e2d1Snpiggin@suse.de  *
50725d9e2d1Snpiggin@suse.de  * inode's new i_size must already be written before truncate_pagecache
50825d9e2d1Snpiggin@suse.de  * is called.
50925d9e2d1Snpiggin@suse.de  *
51025d9e2d1Snpiggin@suse.de  * This function should typically be called before the filesystem
51125d9e2d1Snpiggin@suse.de  * releases resources associated with the freed range (eg. deallocates
51225d9e2d1Snpiggin@suse.de  * blocks). This way, pagecache will always stay logically coherent
51325d9e2d1Snpiggin@suse.de  * with on-disk format, and the filesystem would not have to deal with
51425d9e2d1Snpiggin@suse.de  * situations such as writepage being called for a page that has already
51525d9e2d1Snpiggin@suse.de  * had its underlying blocks deallocated.
51625d9e2d1Snpiggin@suse.de  */
51725d9e2d1Snpiggin@suse.de void truncate_pagecache(struct inode *inode, loff_t old, loff_t new)
51825d9e2d1Snpiggin@suse.de {
51925d9e2d1Snpiggin@suse.de 	if (new < old) {
52025d9e2d1Snpiggin@suse.de 		struct address_space *mapping = inode->i_mapping;
52125d9e2d1Snpiggin@suse.de 
52225d9e2d1Snpiggin@suse.de 		/*
52325d9e2d1Snpiggin@suse.de 		 * unmap_mapping_range is called twice, first simply for
52425d9e2d1Snpiggin@suse.de 		 * efficiency so that truncate_inode_pages does fewer
52525d9e2d1Snpiggin@suse.de 		 * single-page unmaps.  However after this first call, and
52625d9e2d1Snpiggin@suse.de 		 * before truncate_inode_pages finishes, it is possible for
52725d9e2d1Snpiggin@suse.de 		 * private pages to be COWed, which remain after
52825d9e2d1Snpiggin@suse.de 		 * truncate_inode_pages finishes, hence the second
52925d9e2d1Snpiggin@suse.de 		 * unmap_mapping_range call must be made for correctness.
53025d9e2d1Snpiggin@suse.de 		 */
53125d9e2d1Snpiggin@suse.de 		unmap_mapping_range(mapping, new + PAGE_SIZE - 1, 0, 1);
53225d9e2d1Snpiggin@suse.de 		truncate_inode_pages(mapping, new);
53325d9e2d1Snpiggin@suse.de 		unmap_mapping_range(mapping, new + PAGE_SIZE - 1, 0, 1);
53425d9e2d1Snpiggin@suse.de 	}
53525d9e2d1Snpiggin@suse.de }
53625d9e2d1Snpiggin@suse.de EXPORT_SYMBOL(truncate_pagecache);
53725d9e2d1Snpiggin@suse.de 
53825d9e2d1Snpiggin@suse.de /**
53925d9e2d1Snpiggin@suse.de  * vmtruncate - unmap mappings "freed" by truncate() syscall
54025d9e2d1Snpiggin@suse.de  * @inode: inode of the file used
54125d9e2d1Snpiggin@suse.de  * @offset: file offset to start truncating
54225d9e2d1Snpiggin@suse.de  *
54325d9e2d1Snpiggin@suse.de  * NOTE! We have to be ready to update the memory sharing
54425d9e2d1Snpiggin@suse.de  * between the file and the memory map for a potential last
54525d9e2d1Snpiggin@suse.de  * incomplete page.  Ugly, but necessary.
54625d9e2d1Snpiggin@suse.de  */
54725d9e2d1Snpiggin@suse.de int vmtruncate(struct inode *inode, loff_t offset)
54825d9e2d1Snpiggin@suse.de {
54925d9e2d1Snpiggin@suse.de 	loff_t oldsize;
55025d9e2d1Snpiggin@suse.de 	int error;
55125d9e2d1Snpiggin@suse.de 
55225d9e2d1Snpiggin@suse.de 	error = inode_newsize_ok(inode, offset);
55325d9e2d1Snpiggin@suse.de 	if (error)
55425d9e2d1Snpiggin@suse.de 		return error;
55525d9e2d1Snpiggin@suse.de 	oldsize = inode->i_size;
55625d9e2d1Snpiggin@suse.de 	i_size_write(inode, offset);
55725d9e2d1Snpiggin@suse.de 	truncate_pagecache(inode, oldsize, offset);
55825d9e2d1Snpiggin@suse.de 	if (inode->i_op->truncate)
55925d9e2d1Snpiggin@suse.de 		inode->i_op->truncate(inode);
56025d9e2d1Snpiggin@suse.de 
56125d9e2d1Snpiggin@suse.de 	return error;
56225d9e2d1Snpiggin@suse.de }
56325d9e2d1Snpiggin@suse.de EXPORT_SYMBOL(vmtruncate);
564