2 * mm/truncate.c - code for taking down pages from address_spaces
4 * Copyright (C) 2002, Linus Torvalds
6 * 10Sep2002 Andrew Morton
10 #include <linux/kernel.h>
11 #include <linux/backing-dev.h>
12 #include <linux/gfp.h>
14 #include <linux/swap.h>
15 #include <linux/module.h>
16 #include <linux/pagemap.h>
17 #include <linux/highmem.h>
18 #include <linux/pagevec.h>
19 #include <linux/task_io_accounting_ops.h>
20 #include <linux/buffer_head.h> /* grr. try_to_release_page,
26 * do_invalidatepage - invalidate part or all of a page
27 * @page: the page which is affected
28 * @offset: the index of the truncation point
30 * do_invalidatepage() is called when all or part of the page has become
31 * invalidated by a truncate operation.
33 * do_invalidatepage() does not have to release all buffers, but it must
34 * ensure that no dirty buffer is left outside @offset and that no I/O
35 * is underway against any of the blocks which are outside the truncation
36 * point. Because the caller is about to free (and possibly reuse) those
39 void do_invalidatepage(struct page *page, unsigned long offset)
41 void (*invalidatepage)(struct page *, unsigned long);
42 invalidatepage = page->mapping->a_ops->invalidatepage;
45 invalidatepage = block_invalidatepage;
48 (*invalidatepage)(page, offset);
51 static inline void truncate_partial_page(struct page *page, unsigned partial)
53 zero_user_segment(page, partial, PAGE_CACHE_SIZE);
54 if (page_has_private(page))
55 do_invalidatepage(page, partial);
59 * This cancels just the dirty bit on the kernel page itself, it
60 * does NOT actually remove dirty bits on any mmap's that may be
61 * around. It also leaves the page tagged dirty, so any sync
62 * activity will still find it on the dirty lists, and in particular,
63 * clear_page_dirty_for_io() will still look at the dirty bits in
66 * Doing this should *normally* only ever be done when a page
67 * is truncated, and is not actually mapped anywhere at all. However,
68 * fs/buffer.c does this when it notices that somebody has cleaned
69 * out all the buffers on a page without actually doing it through
70 * the VM. Can you say "ext3 is horribly ugly"? Tought you could.
72 void cancel_dirty_page(struct page *page, unsigned int account_size)
74 if (TestClearPageDirty(page)) {
75 struct address_space *mapping = page->mapping;
76 if (mapping && mapping_cap_account_dirty(mapping)) {
77 dec_zone_page_state(page, NR_FILE_DIRTY);
78 dec_bdi_stat(mapping->backing_dev_info,
81 task_io_account_cancelled_write(account_size);
85 EXPORT_SYMBOL(cancel_dirty_page);
88 * If truncate cannot remove the fs-private metadata from the page, the page
89 * becomes orphaned. It will be left on the LRU and may even be mapped into
90 * user pagetables if we're racing with filemap_fault().
92 * We need to bale out if page->mapping is no longer equal to the original
93 * mapping. This happens a) when the VM reclaimed the page while we waited on
94 * its lock, b) when a concurrent invalidate_mapping_pages got there first and
95 * c) when tmpfs swizzles a page between a tmpfs inode and swapper_space.
98 truncate_complete_page(struct address_space *mapping, struct page *page)
100 if (page->mapping != mapping)
103 if (page_has_private(page))
104 do_invalidatepage(page, 0);
106 cancel_dirty_page(page, PAGE_CACHE_SIZE);
108 clear_page_mlock(page);
109 remove_from_page_cache(page);
110 ClearPageMappedToDisk(page);
111 page_cache_release(page); /* pagecache ref */
116 * This is for invalidate_mapping_pages(). That function can be called at
117 * any time, and is not supposed to throw away dirty pages. But pages can
118 * be marked dirty at any time too, so use remove_mapping which safely
119 * discards clean, unused pages.
121 * Returns non-zero if the page was successfully invalidated.
124 invalidate_complete_page(struct address_space *mapping, struct page *page)
128 if (page->mapping != mapping)
131 if (page_has_private(page) && !try_to_release_page(page, 0))
134 clear_page_mlock(page);
135 ret = remove_mapping(mapping, page);
140 int truncate_inode_page(struct address_space *mapping, struct page *page)
142 if (page_mapped(page)) {
143 unmap_mapping_range(mapping,
144 (loff_t)page->index << PAGE_CACHE_SHIFT,
147 return truncate_complete_page(mapping, page);
151 * Used to get rid of pages on hardware memory corruption.
153 int generic_error_remove_page(struct address_space *mapping, struct page *page)
158 * Only punch for normal data pages for now.
159 * Handling other types like directories would need more auditing.
161 if (!S_ISREG(mapping->host->i_mode))
163 return truncate_inode_page(mapping, page);
165 EXPORT_SYMBOL(generic_error_remove_page);
168 * Safely invalidate one page from its pagecache mapping.
169 * It only drops clean, unused pages. The page must be locked.
171 * Returns 1 if the page is successfully invalidated, otherwise 0.
173 int invalidate_inode_page(struct page *page)
175 struct address_space *mapping = page_mapping(page);
178 if (PageDirty(page) || PageWriteback(page))
180 if (page_mapped(page))
182 return invalidate_complete_page(mapping, page);
186 * truncate_inode_pages - truncate range of pages specified by start & end byte offsets
187 * @mapping: mapping to truncate
188 * @lstart: offset from which to truncate
189 * @lend: offset to which to truncate
191 * Truncate the page cache, removing the pages that are between
192 * specified offsets (and zeroing out partial page
193 * (if lstart is not page aligned)).
195 * Truncate takes two passes - the first pass is nonblocking. It will not
196 * block on page locks and it will not block on writeback. The second pass
197 * will wait. This is to prevent as much IO as possible in the affected region.
198 * The first pass will remove most pages, so the search cost of the second pass
201 * When looking at page->index outside the page lock we need to be careful to
202 * copy it into a local to avoid races (it could change at any time).
204 * We pass down the cache-hot hint to the page freeing code. Even if the
205 * mapping is large, it is probably the case that the final pages are the most
206 * recently touched, and freeing happens in ascending file offset order.
208 void truncate_inode_pages_range(struct address_space *mapping,
209 loff_t lstart, loff_t lend)
211 const pgoff_t start = (lstart + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
213 const unsigned partial = lstart & (PAGE_CACHE_SIZE - 1);
218 if (mapping->nrpages == 0)
221 BUG_ON((lend & (PAGE_CACHE_SIZE - 1)) != (PAGE_CACHE_SIZE - 1));
222 end = (lend >> PAGE_CACHE_SHIFT);
224 pagevec_init(&pvec, 0);
226 while (next <= end &&
227 pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
228 mem_cgroup_uncharge_start();
229 for (i = 0; i < pagevec_count(&pvec); i++) {
230 struct page *page = pvec.pages[i];
231 pgoff_t page_index = page->index;
233 if (page_index > end) {
238 if (page_index > next)
241 if (!trylock_page(page))
243 if (PageWriteback(page)) {
247 truncate_inode_page(mapping, page);
250 pagevec_release(&pvec);
251 mem_cgroup_uncharge_end();
256 struct page *page = find_lock_page(mapping, start - 1);
258 wait_on_page_writeback(page);
259 truncate_partial_page(page, partial);
261 page_cache_release(page);
268 if (!pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
274 if (pvec.pages[0]->index > end) {
275 pagevec_release(&pvec);
278 mem_cgroup_uncharge_start();
279 for (i = 0; i < pagevec_count(&pvec); i++) {
280 struct page *page = pvec.pages[i];
282 if (page->index > end)
285 wait_on_page_writeback(page);
286 truncate_inode_page(mapping, page);
287 if (page->index > next)
292 pagevec_release(&pvec);
293 mem_cgroup_uncharge_end();
296 EXPORT_SYMBOL(truncate_inode_pages_range);
299 * truncate_inode_pages - truncate *all* the pages from an offset
300 * @mapping: mapping to truncate
301 * @lstart: offset from which to truncate
303 * Called under (and serialised by) inode->i_mutex.
305 void truncate_inode_pages(struct address_space *mapping, loff_t lstart)
307 truncate_inode_pages_range(mapping, lstart, (loff_t)-1);
309 EXPORT_SYMBOL(truncate_inode_pages);
312 * invalidate_mapping_pages - Invalidate all the unlocked pages of one inode
313 * @mapping: the address_space which holds the pages to invalidate
314 * @start: the offset 'from' which to invalidate
315 * @end: the offset 'to' which to invalidate (inclusive)
317 * This function only removes the unlocked pages, if you want to
318 * remove all the pages of one inode, you must call truncate_inode_pages.
320 * invalidate_mapping_pages() will not block on IO activity. It will not
321 * invalidate pages which are dirty, locked, under writeback or mapped into
324 unsigned long invalidate_mapping_pages(struct address_space *mapping,
325 pgoff_t start, pgoff_t end)
328 pgoff_t next = start;
329 unsigned long ret = 0;
332 pagevec_init(&pvec, 0);
333 while (next <= end &&
334 pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
335 mem_cgroup_uncharge_start();
336 for (i = 0; i < pagevec_count(&pvec); i++) {
337 struct page *page = pvec.pages[i];
341 lock_failed = !trylock_page(page);
344 * We really shouldn't be looking at the ->index of an
345 * unlocked page. But we're not allowed to lock these
346 * pages. So we rely upon nobody altering the ->index
347 * of this (pinned-by-us) page.
356 ret += invalidate_inode_page(page);
362 pagevec_release(&pvec);
363 mem_cgroup_uncharge_end();
368 EXPORT_SYMBOL(invalidate_mapping_pages);
371 * This is like invalidate_complete_page(), except it ignores the page's
372 * refcount. We do this because invalidate_inode_pages2() needs stronger
373 * invalidation guarantees, and cannot afford to leave pages behind because
374 * shrink_page_list() has a temp ref on them, or because they're transiently
375 * sitting in the lru_cache_add() pagevecs.
378 invalidate_complete_page2(struct address_space *mapping, struct page *page)
380 if (page->mapping != mapping)
383 if (page_has_private(page) && !try_to_release_page(page, GFP_KERNEL))
386 spin_lock_irq(&mapping->tree_lock);
390 clear_page_mlock(page);
391 BUG_ON(page_has_private(page));
392 __remove_from_page_cache(page);
393 spin_unlock_irq(&mapping->tree_lock);
394 mem_cgroup_uncharge_cache_page(page);
396 if (mapping->a_ops->freepage)
397 mapping->a_ops->freepage(page);
399 page_cache_release(page); /* pagecache ref */
402 spin_unlock_irq(&mapping->tree_lock);
406 static int do_launder_page(struct address_space *mapping, struct page *page)
408 if (!PageDirty(page))
410 if (page->mapping != mapping || mapping->a_ops->launder_page == NULL)
412 return mapping->a_ops->launder_page(page);
416 * invalidate_inode_pages2_range - remove range of pages from an address_space
417 * @mapping: the address_space
418 * @start: the page offset 'from' which to invalidate
419 * @end: the page offset 'to' which to invalidate (inclusive)
421 * Any pages which are found to be mapped into pagetables are unmapped prior to
424 * Returns -EBUSY if any pages could not be invalidated.
426 int invalidate_inode_pages2_range(struct address_space *mapping,
427 pgoff_t start, pgoff_t end)
434 int did_range_unmap = 0;
437 pagevec_init(&pvec, 0);
439 while (next <= end && !wrapped &&
440 pagevec_lookup(&pvec, mapping, next,
441 min(end - next, (pgoff_t)PAGEVEC_SIZE - 1) + 1)) {
442 mem_cgroup_uncharge_start();
443 for (i = 0; i < pagevec_count(&pvec); i++) {
444 struct page *page = pvec.pages[i];
448 if (page->mapping != mapping) {
452 page_index = page->index;
453 next = page_index + 1;
456 if (page_index > end) {
460 wait_on_page_writeback(page);
461 if (page_mapped(page)) {
462 if (!did_range_unmap) {
464 * Zap the rest of the file in one hit.
466 unmap_mapping_range(mapping,
467 (loff_t)page_index<<PAGE_CACHE_SHIFT,
468 (loff_t)(end - page_index + 1)
476 unmap_mapping_range(mapping,
477 (loff_t)page_index<<PAGE_CACHE_SHIFT,
481 BUG_ON(page_mapped(page));
482 ret2 = do_launder_page(mapping, page);
484 if (!invalidate_complete_page2(mapping, page))
491 pagevec_release(&pvec);
492 mem_cgroup_uncharge_end();
497 EXPORT_SYMBOL_GPL(invalidate_inode_pages2_range);
500 * invalidate_inode_pages2 - remove all pages from an address_space
501 * @mapping: the address_space
503 * Any pages which are found to be mapped into pagetables are unmapped prior to
506 * Returns -EBUSY if any pages could not be invalidated.
508 int invalidate_inode_pages2(struct address_space *mapping)
510 return invalidate_inode_pages2_range(mapping, 0, -1);
512 EXPORT_SYMBOL_GPL(invalidate_inode_pages2);
515 * truncate_pagecache - unmap and remove pagecache that has been truncated
517 * @old: old file offset
518 * @new: new file offset
520 * inode's new i_size must already be written before truncate_pagecache
523 * This function should typically be called before the filesystem
524 * releases resources associated with the freed range (eg. deallocates
525 * blocks). This way, pagecache will always stay logically coherent
526 * with on-disk format, and the filesystem would not have to deal with
527 * situations such as writepage being called for a page that has already
528 * had its underlying blocks deallocated.
530 void truncate_pagecache(struct inode *inode, loff_t old, loff_t new)
532 struct address_space *mapping = inode->i_mapping;
535 * unmap_mapping_range is called twice, first simply for
536 * efficiency so that truncate_inode_pages does fewer
537 * single-page unmaps. However after this first call, and
538 * before truncate_inode_pages finishes, it is possible for
539 * private pages to be COWed, which remain after
540 * truncate_inode_pages finishes, hence the second
541 * unmap_mapping_range call must be made for correctness.
543 unmap_mapping_range(mapping, new + PAGE_SIZE - 1, 0, 1);
544 truncate_inode_pages(mapping, new);
545 unmap_mapping_range(mapping, new + PAGE_SIZE - 1, 0, 1);
547 EXPORT_SYMBOL(truncate_pagecache);
550 * truncate_setsize - update inode and pagecache for a new file size
552 * @newsize: new file size
554 * truncate_setsize updates i_size and performs pagecache truncation (if
555 * necessary) to @newsize. It will be typically be called from the filesystem's
556 * setattr function when ATTR_SIZE is passed in.
558 * Must be called with inode_mutex held and before all filesystem specific
559 * block truncation has been performed.
561 void truncate_setsize(struct inode *inode, loff_t newsize)
565 oldsize = inode->i_size;
566 i_size_write(inode, newsize);
568 truncate_pagecache(inode, oldsize, newsize);
570 EXPORT_SYMBOL(truncate_setsize);
573 * vmtruncate - unmap mappings "freed" by truncate() syscall
574 * @inode: inode of the file used
575 * @offset: file offset to start truncating
577 * This function is deprecated and truncate_setsize or truncate_pagecache
578 * should be used instead, together with filesystem specific block truncation.
580 int vmtruncate(struct inode *inode, loff_t offset)
584 error = inode_newsize_ok(inode, offset);
588 truncate_setsize(inode, offset);
589 if (inode->i_op->truncate)
590 inode->i_op->truncate(inode);
593 EXPORT_SYMBOL(vmtruncate);