2 * mm/truncate.c - code for taking down pages from address_spaces
4 * Copyright (C) 2002, Linus Torvalds
6 * 10Sep2002 akpm@zip.com.au
10 #include <linux/kernel.h>
12 #include <linux/swap.h>
13 #include <linux/module.h>
14 #include <linux/pagemap.h>
15 #include <linux/pagevec.h>
16 #include <linux/task_io_accounting_ops.h>
17 #include <linux/buffer_head.h> /* grr. try_to_release_page,
22 * do_invalidatepage - invalidate part of all of a page
23 * @page: the page which is affected
24 * @offset: the index of the truncation point
26 * do_invalidatepage() is called when all or part of the page has become
27 * invalidated by a truncate operation.
29 * do_invalidatepage() does not have to release all buffers, but it must
30 * ensure that no dirty buffer is left outside @offset and that no I/O
31 * is underway against any of the blocks which are outside the truncation
32 * point. Because the caller is about to free (and possibly reuse) those
35 void do_invalidatepage(struct page *page, unsigned long offset)
37 void (*invalidatepage)(struct page *, unsigned long);
38 invalidatepage = page->mapping->a_ops->invalidatepage;
41 invalidatepage = block_invalidatepage;
44 (*invalidatepage)(page, offset);
47 static inline void truncate_partial_page(struct page *page, unsigned partial)
49 memclear_highpage_flush(page, partial, PAGE_CACHE_SIZE-partial);
50 if (PagePrivate(page))
51 do_invalidatepage(page, partial);
54 void cancel_dirty_page(struct page *page, unsigned int account_size)
56 /* If we're cancelling the page, it had better not be mapped any more */
57 if (page_mapped(page)) {
58 static unsigned int warncount;
60 WARN_ON(++warncount < 5);
63 if (TestClearPageDirty(page) && account_size &&
64 mapping_cap_account_dirty(page->mapping)) {
65 dec_zone_page_state(page, NR_FILE_DIRTY);
66 task_io_account_cancelled_write(account_size);
71 * If truncate cannot remove the fs-private metadata from the page, the page
72 * becomes anonymous. It will be left on the LRU and may even be mapped into
73 * user pagetables if we're racing with filemap_nopage().
75 * We need to bale out if page->mapping is no longer equal to the original
76 * mapping. This happens a) when the VM reclaimed the page while we waited on
77 * its lock, b) when a concurrent invalidate_inode_pages got there first and
78 * c) when tmpfs swizzles a page between a tmpfs inode and swapper_space.
81 truncate_complete_page(struct address_space *mapping, struct page *page)
83 if (page->mapping != mapping)
86 cancel_dirty_page(page, PAGE_CACHE_SIZE);
88 if (PagePrivate(page))
89 do_invalidatepage(page, 0);
91 ClearPageUptodate(page);
92 ClearPageMappedToDisk(page);
93 remove_from_page_cache(page);
94 page_cache_release(page); /* pagecache ref */
98 * This is for invalidate_inode_pages(). That function can be called at
99 * any time, and is not supposed to throw away dirty pages. But pages can
100 * be marked dirty at any time too, so use remove_mapping which safely
101 * discards clean, unused pages.
103 * Returns non-zero if the page was successfully invalidated.
106 invalidate_complete_page(struct address_space *mapping, struct page *page)
110 if (page->mapping != mapping)
113 if (PagePrivate(page) && !try_to_release_page(page, 0))
116 ret = remove_mapping(mapping, page);
122 * truncate_inode_pages - truncate range of pages specified by start and
124 * @mapping: mapping to truncate
125 * @lstart: offset from which to truncate
126 * @lend: offset to which to truncate
128 * Truncate the page cache, removing the pages that are between
129 * specified offsets (and zeroing out partial page
130 * (if lstart is not page aligned)).
132 * Truncate takes two passes - the first pass is nonblocking. It will not
133 * block on page locks and it will not block on writeback. The second pass
134 * will wait. This is to prevent as much IO as possible in the affected region.
135 * The first pass will remove most pages, so the search cost of the second pass
138 * When looking at page->index outside the page lock we need to be careful to
139 * copy it into a local to avoid races (it could change at any time).
141 * We pass down the cache-hot hint to the page freeing code. Even if the
142 * mapping is large, it is probably the case that the final pages are the most
143 * recently touched, and freeing happens in ascending file offset order.
145 void truncate_inode_pages_range(struct address_space *mapping,
146 loff_t lstart, loff_t lend)
148 const pgoff_t start = (lstart + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
150 const unsigned partial = lstart & (PAGE_CACHE_SIZE - 1);
155 if (mapping->nrpages == 0)
158 BUG_ON((lend & (PAGE_CACHE_SIZE - 1)) != (PAGE_CACHE_SIZE - 1));
159 end = (lend >> PAGE_CACHE_SHIFT);
161 pagevec_init(&pvec, 0);
163 while (next <= end &&
164 pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
165 for (i = 0; i < pagevec_count(&pvec); i++) {
166 struct page *page = pvec.pages[i];
167 pgoff_t page_index = page->index;
169 if (page_index > end) {
174 if (page_index > next)
177 if (TestSetPageLocked(page))
179 if (PageWriteback(page)) {
183 truncate_complete_page(mapping, page);
186 pagevec_release(&pvec);
191 struct page *page = find_lock_page(mapping, start - 1);
193 wait_on_page_writeback(page);
194 truncate_partial_page(page, partial);
196 page_cache_release(page);
203 if (!pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
209 if (pvec.pages[0]->index > end) {
210 pagevec_release(&pvec);
213 for (i = 0; i < pagevec_count(&pvec); i++) {
214 struct page *page = pvec.pages[i];
216 if (page->index > end)
219 wait_on_page_writeback(page);
220 if (page->index > next)
223 truncate_complete_page(mapping, page);
226 pagevec_release(&pvec);
229 EXPORT_SYMBOL(truncate_inode_pages_range);
232 * truncate_inode_pages - truncate *all* the pages from an offset
233 * @mapping: mapping to truncate
234 * @lstart: offset from which to truncate
236 * Called under (and serialised by) inode->i_mutex.
238 void truncate_inode_pages(struct address_space *mapping, loff_t lstart)
240 truncate_inode_pages_range(mapping, lstart, (loff_t)-1);
242 EXPORT_SYMBOL(truncate_inode_pages);
245 * invalidate_mapping_pages - Invalidate all the unlocked pages of one inode
246 * @mapping: the address_space which holds the pages to invalidate
247 * @start: the offset 'from' which to invalidate
248 * @end: the offset 'to' which to invalidate (inclusive)
250 * This function only removes the unlocked pages, if you want to
251 * remove all the pages of one inode, you must call truncate_inode_pages.
253 * invalidate_mapping_pages() will not block on IO activity. It will not
254 * invalidate pages which are dirty, locked, under writeback or mapped into
257 unsigned long invalidate_mapping_pages(struct address_space *mapping,
258 pgoff_t start, pgoff_t end)
261 pgoff_t next = start;
262 unsigned long ret = 0;
265 pagevec_init(&pvec, 0);
266 while (next <= end &&
267 pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
268 for (i = 0; i < pagevec_count(&pvec); i++) {
269 struct page *page = pvec.pages[i];
273 lock_failed = TestSetPageLocked(page);
276 * We really shouldn't be looking at the ->index of an
277 * unlocked page. But we're not allowed to lock these
278 * pages. So we rely upon nobody altering the ->index
279 * of this (pinned-by-us) page.
288 if (PageDirty(page) || PageWriteback(page))
290 if (page_mapped(page))
292 ret += invalidate_complete_page(mapping, page);
298 pagevec_release(&pvec);
303 unsigned long invalidate_inode_pages(struct address_space *mapping)
305 return invalidate_mapping_pages(mapping, 0, ~0UL);
307 EXPORT_SYMBOL(invalidate_inode_pages);
310 * This is like invalidate_complete_page(), except it ignores the page's
311 * refcount. We do this because invalidate_inode_pages2() needs stronger
312 * invalidation guarantees, and cannot afford to leave pages behind because
313 * shrink_list() has a temp ref on them, or because they're transiently sitting
314 * in the lru_cache_add() pagevecs.
317 invalidate_complete_page2(struct address_space *mapping, struct page *page)
319 if (page->mapping != mapping)
322 if (PagePrivate(page) && !try_to_release_page(page, GFP_KERNEL))
325 write_lock_irq(&mapping->tree_lock);
329 BUG_ON(PagePrivate(page));
330 __remove_from_page_cache(page);
331 write_unlock_irq(&mapping->tree_lock);
332 ClearPageUptodate(page);
333 page_cache_release(page); /* pagecache ref */
336 write_unlock_irq(&mapping->tree_lock);
341 * invalidate_inode_pages2_range - remove range of pages from an address_space
342 * @mapping: the address_space
343 * @start: the page offset 'from' which to invalidate
344 * @end: the page offset 'to' which to invalidate (inclusive)
346 * Any pages which are found to be mapped into pagetables are unmapped prior to
349 * Returns -EIO if any pages could not be invalidated.
351 int invalidate_inode_pages2_range(struct address_space *mapping,
352 pgoff_t start, pgoff_t end)
358 int did_range_unmap = 0;
361 pagevec_init(&pvec, 0);
363 while (next <= end && !ret && !wrapped &&
364 pagevec_lookup(&pvec, mapping, next,
365 min(end - next, (pgoff_t)PAGEVEC_SIZE - 1) + 1)) {
366 for (i = 0; !ret && i < pagevec_count(&pvec); i++) {
367 struct page *page = pvec.pages[i];
371 if (page->mapping != mapping) {
375 page_index = page->index;
376 next = page_index + 1;
379 if (page_index > end) {
383 wait_on_page_writeback(page);
384 while (page_mapped(page)) {
385 if (!did_range_unmap) {
387 * Zap the rest of the file in one hit.
389 unmap_mapping_range(mapping,
390 (loff_t)page_index<<PAGE_CACHE_SHIFT,
391 (loff_t)(end - page_index + 1)
399 unmap_mapping_range(mapping,
400 (loff_t)page_index<<PAGE_CACHE_SHIFT,
404 if (!invalidate_complete_page2(mapping, page))
408 pagevec_release(&pvec);
414 EXPORT_SYMBOL_GPL(invalidate_inode_pages2_range);
417 * invalidate_inode_pages2 - remove all pages from an address_space
418 * @mapping: the address_space
420 * Any pages which are found to be mapped into pagetables are unmapped prior to
423 * Returns -EIO if any pages could not be invalidated.
425 int invalidate_inode_pages2(struct address_space *mapping)
427 return invalidate_inode_pages2_range(mapping, 0, -1);
429 EXPORT_SYMBOL_GPL(invalidate_inode_pages2);