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);
55 * If truncate cannot remove the fs-private metadata from the page, the page
56 * becomes anonymous. It will be left on the LRU and may even be mapped into
57 * user pagetables if we're racing with filemap_nopage().
59 * We need to bale out if page->mapping is no longer equal to the original
60 * mapping. This happens a) when the VM reclaimed the page while we waited on
61 * its lock, b) when a concurrent invalidate_inode_pages got there first and
62 * c) when tmpfs swizzles a page between a tmpfs inode and swapper_space.
65 truncate_complete_page(struct address_space *mapping, struct page *page)
67 if (page->mapping != mapping)
70 if (PagePrivate(page))
71 do_invalidatepage(page, 0);
73 if (test_clear_page_dirty(page))
74 task_io_account_cancelled_write(PAGE_CACHE_SIZE);
75 ClearPageUptodate(page);
76 ClearPageMappedToDisk(page);
77 remove_from_page_cache(page);
78 page_cache_release(page); /* pagecache ref */
82 * This is for invalidate_inode_pages(). That function can be called at
83 * any time, and is not supposed to throw away dirty pages. But pages can
84 * be marked dirty at any time too, so use remove_mapping which safely
85 * discards clean, unused pages.
87 * Returns non-zero if the page was successfully invalidated.
90 invalidate_complete_page(struct address_space *mapping, struct page *page)
94 if (page->mapping != mapping)
97 if (PagePrivate(page) && !try_to_release_page(page, 0))
100 ret = remove_mapping(mapping, page);
106 * truncate_inode_pages - truncate range of pages specified by start and
108 * @mapping: mapping to truncate
109 * @lstart: offset from which to truncate
110 * @lend: offset to which to truncate
112 * Truncate the page cache, removing the pages that are between
113 * specified offsets (and zeroing out partial page
114 * (if lstart is not page aligned)).
116 * Truncate takes two passes - the first pass is nonblocking. It will not
117 * block on page locks and it will not block on writeback. The second pass
118 * will wait. This is to prevent as much IO as possible in the affected region.
119 * The first pass will remove most pages, so the search cost of the second pass
122 * When looking at page->index outside the page lock we need to be careful to
123 * copy it into a local to avoid races (it could change at any time).
125 * We pass down the cache-hot hint to the page freeing code. Even if the
126 * mapping is large, it is probably the case that the final pages are the most
127 * recently touched, and freeing happens in ascending file offset order.
129 void truncate_inode_pages_range(struct address_space *mapping,
130 loff_t lstart, loff_t lend)
132 const pgoff_t start = (lstart + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
134 const unsigned partial = lstart & (PAGE_CACHE_SIZE - 1);
139 if (mapping->nrpages == 0)
142 BUG_ON((lend & (PAGE_CACHE_SIZE - 1)) != (PAGE_CACHE_SIZE - 1));
143 end = (lend >> PAGE_CACHE_SHIFT);
145 pagevec_init(&pvec, 0);
147 while (next <= end &&
148 pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
149 for (i = 0; i < pagevec_count(&pvec); i++) {
150 struct page *page = pvec.pages[i];
151 pgoff_t page_index = page->index;
153 if (page_index > end) {
158 if (page_index > next)
161 if (TestSetPageLocked(page))
163 if (PageWriteback(page)) {
167 truncate_complete_page(mapping, page);
170 pagevec_release(&pvec);
175 struct page *page = find_lock_page(mapping, start - 1);
177 wait_on_page_writeback(page);
178 truncate_partial_page(page, partial);
180 page_cache_release(page);
187 if (!pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
193 if (pvec.pages[0]->index > end) {
194 pagevec_release(&pvec);
197 for (i = 0; i < pagevec_count(&pvec); i++) {
198 struct page *page = pvec.pages[i];
200 if (page->index > end)
203 wait_on_page_writeback(page);
204 if (page->index > next)
207 truncate_complete_page(mapping, page);
210 pagevec_release(&pvec);
213 EXPORT_SYMBOL(truncate_inode_pages_range);
216 * truncate_inode_pages - truncate *all* the pages from an offset
217 * @mapping: mapping to truncate
218 * @lstart: offset from which to truncate
220 * Called under (and serialised by) inode->i_mutex.
222 void truncate_inode_pages(struct address_space *mapping, loff_t lstart)
224 truncate_inode_pages_range(mapping, lstart, (loff_t)-1);
226 EXPORT_SYMBOL(truncate_inode_pages);
229 * invalidate_mapping_pages - Invalidate all the unlocked pages of one inode
230 * @mapping: the address_space which holds the pages to invalidate
231 * @start: the offset 'from' which to invalidate
232 * @end: the offset 'to' which to invalidate (inclusive)
234 * This function only removes the unlocked pages, if you want to
235 * remove all the pages of one inode, you must call truncate_inode_pages.
237 * invalidate_mapping_pages() will not block on IO activity. It will not
238 * invalidate pages which are dirty, locked, under writeback or mapped into
241 unsigned long invalidate_mapping_pages(struct address_space *mapping,
242 pgoff_t start, pgoff_t end)
245 pgoff_t next = start;
246 unsigned long ret = 0;
249 pagevec_init(&pvec, 0);
250 while (next <= end &&
251 pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
252 for (i = 0; i < pagevec_count(&pvec); i++) {
253 struct page *page = pvec.pages[i];
257 lock_failed = TestSetPageLocked(page);
260 * We really shouldn't be looking at the ->index of an
261 * unlocked page. But we're not allowed to lock these
262 * pages. So we rely upon nobody altering the ->index
263 * of this (pinned-by-us) page.
272 if (PageDirty(page) || PageWriteback(page))
274 if (page_mapped(page))
276 ret += invalidate_complete_page(mapping, page);
282 pagevec_release(&pvec);
287 unsigned long invalidate_inode_pages(struct address_space *mapping)
289 return invalidate_mapping_pages(mapping, 0, ~0UL);
291 EXPORT_SYMBOL(invalidate_inode_pages);
294 * This is like invalidate_complete_page(), except it ignores the page's
295 * refcount. We do this because invalidate_inode_pages2() needs stronger
296 * invalidation guarantees, and cannot afford to leave pages behind because
297 * shrink_list() has a temp ref on them, or because they're transiently sitting
298 * in the lru_cache_add() pagevecs.
301 invalidate_complete_page2(struct address_space *mapping, struct page *page)
303 if (page->mapping != mapping)
306 if (PagePrivate(page) && !try_to_release_page(page, GFP_KERNEL))
309 write_lock_irq(&mapping->tree_lock);
313 BUG_ON(PagePrivate(page));
314 __remove_from_page_cache(page);
315 write_unlock_irq(&mapping->tree_lock);
316 ClearPageUptodate(page);
317 page_cache_release(page); /* pagecache ref */
320 write_unlock_irq(&mapping->tree_lock);
325 * invalidate_inode_pages2_range - remove range of pages from an address_space
326 * @mapping: the address_space
327 * @start: the page offset 'from' which to invalidate
328 * @end: the page offset 'to' which to invalidate (inclusive)
330 * Any pages which are found to be mapped into pagetables are unmapped prior to
333 * Returns -EIO if any pages could not be invalidated.
335 int invalidate_inode_pages2_range(struct address_space *mapping,
336 pgoff_t start, pgoff_t end)
342 int did_range_unmap = 0;
345 pagevec_init(&pvec, 0);
347 while (next <= end && !ret && !wrapped &&
348 pagevec_lookup(&pvec, mapping, next,
349 min(end - next, (pgoff_t)PAGEVEC_SIZE - 1) + 1)) {
350 for (i = 0; !ret && i < pagevec_count(&pvec); i++) {
351 struct page *page = pvec.pages[i];
356 if (page->mapping != mapping) {
360 page_index = page->index;
361 next = page_index + 1;
364 if (page_index > end) {
368 wait_on_page_writeback(page);
369 while (page_mapped(page)) {
370 if (!did_range_unmap) {
372 * Zap the rest of the file in one hit.
374 unmap_mapping_range(mapping,
375 (loff_t)page_index<<PAGE_CACHE_SHIFT,
376 (loff_t)(end - page_index + 1)
384 unmap_mapping_range(mapping,
385 (loff_t)page_index<<PAGE_CACHE_SHIFT,
389 was_dirty = test_clear_page_dirty(page);
390 if (!invalidate_complete_page2(mapping, page)) {
392 set_page_dirty(page);
397 pagevec_release(&pvec);
403 EXPORT_SYMBOL_GPL(invalidate_inode_pages2_range);
406 * invalidate_inode_pages2 - remove all pages from an address_space
407 * @mapping: the address_space
409 * Any pages which are found to be mapped into pagetables are unmapped prior to
412 * Returns -EIO if any pages could not be invalidated.
414 int invalidate_inode_pages2(struct address_space *mapping)
416 return invalidate_inode_pages2_range(mapping, 0, -1);
418 EXPORT_SYMBOL_GPL(invalidate_inode_pages2);