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,
22 #include <linux/cleancache.h>
27 * do_invalidatepage - invalidate part or all of a page
28 * @page: the page which is affected
29 * @offset: the index of the truncation point
31 * do_invalidatepage() is called when all or part of the page has become
32 * invalidated by a truncate operation.
34 * do_invalidatepage() does not have to release all buffers, but it must
35 * ensure that no dirty buffer is left outside @offset and that no I/O
36 * is underway against any of the blocks which are outside the truncation
37 * point. Because the caller is about to free (and possibly reuse) those
40 void do_invalidatepage(struct page *page, unsigned long offset)
42 void (*invalidatepage)(struct page *, unsigned long);
43 invalidatepage = page->mapping->a_ops->invalidatepage;
46 invalidatepage = block_invalidatepage;
49 (*invalidatepage)(page, offset);
52 static inline void truncate_partial_page(struct page *page, unsigned partial)
54 zero_user_segment(page, partial, PAGE_CACHE_SIZE);
55 cleancache_flush_page(page->mapping, page);
56 if (page_has_private(page))
57 do_invalidatepage(page, partial);
61 * This cancels just the dirty bit on the kernel page itself, it
62 * does NOT actually remove dirty bits on any mmap's that may be
63 * around. It also leaves the page tagged dirty, so any sync
64 * activity will still find it on the dirty lists, and in particular,
65 * clear_page_dirty_for_io() will still look at the dirty bits in
68 * Doing this should *normally* only ever be done when a page
69 * is truncated, and is not actually mapped anywhere at all. However,
70 * fs/buffer.c does this when it notices that somebody has cleaned
71 * out all the buffers on a page without actually doing it through
72 * the VM. Can you say "ext3 is horribly ugly"? Tought you could.
74 void cancel_dirty_page(struct page *page, unsigned int account_size)
76 if (TestClearPageDirty(page)) {
77 struct address_space *mapping = page->mapping;
78 if (mapping && mapping_cap_account_dirty(mapping)) {
79 dec_zone_page_state(page, NR_FILE_DIRTY);
80 dec_bdi_stat(mapping->backing_dev_info,
83 task_io_account_cancelled_write(account_size);
87 EXPORT_SYMBOL(cancel_dirty_page);
90 * If truncate cannot remove the fs-private metadata from the page, the page
91 * becomes orphaned. It will be left on the LRU and may even be mapped into
92 * user pagetables if we're racing with filemap_fault().
94 * We need to bale out if page->mapping is no longer equal to the original
95 * mapping. This happens a) when the VM reclaimed the page while we waited on
96 * its lock, b) when a concurrent invalidate_mapping_pages got there first and
97 * c) when tmpfs swizzles a page between a tmpfs inode and swapper_space.
100 truncate_complete_page(struct address_space *mapping, struct page *page)
102 if (page->mapping != mapping)
105 if (page_has_private(page))
106 do_invalidatepage(page, 0);
108 cancel_dirty_page(page, PAGE_CACHE_SIZE);
110 clear_page_mlock(page);
111 ClearPageMappedToDisk(page);
112 delete_from_page_cache(page);
117 * This is for invalidate_mapping_pages(). That function can be called at
118 * any time, and is not supposed to throw away dirty pages. But pages can
119 * be marked dirty at any time too, so use remove_mapping which safely
120 * discards clean, unused pages.
122 * Returns non-zero if the page was successfully invalidated.
125 invalidate_complete_page(struct address_space *mapping, struct page *page)
129 if (page->mapping != mapping)
132 if (page_has_private(page) && !try_to_release_page(page, 0))
135 clear_page_mlock(page);
136 ret = remove_mapping(mapping, page);
141 int truncate_inode_page(struct address_space *mapping, struct page *page)
143 if (page_mapped(page)) {
144 unmap_mapping_range(mapping,
145 (loff_t)page->index << PAGE_CACHE_SHIFT,
148 return truncate_complete_page(mapping, page);
152 * Used to get rid of pages on hardware memory corruption.
154 int generic_error_remove_page(struct address_space *mapping, struct page *page)
159 * Only punch for normal data pages for now.
160 * Handling other types like directories would need more auditing.
162 if (!S_ISREG(mapping->host->i_mode))
164 return truncate_inode_page(mapping, page);
166 EXPORT_SYMBOL(generic_error_remove_page);
169 * Safely invalidate one page from its pagecache mapping.
170 * It only drops clean, unused pages. The page must be locked.
172 * Returns 1 if the page is successfully invalidated, otherwise 0.
174 int invalidate_inode_page(struct page *page)
176 struct address_space *mapping = page_mapping(page);
179 if (PageDirty(page) || PageWriteback(page))
181 if (page_mapped(page))
183 return invalidate_complete_page(mapping, page);
187 * truncate_inode_pages - truncate range of pages specified by start & end byte offsets
188 * @mapping: mapping to truncate
189 * @lstart: offset from which to truncate
190 * @lend: offset to which to truncate
192 * Truncate the page cache, removing the pages that are between
193 * specified offsets (and zeroing out partial page
194 * (if lstart is not page aligned)).
196 * Truncate takes two passes - the first pass is nonblocking. It will not
197 * block on page locks and it will not block on writeback. The second pass
198 * will wait. This is to prevent as much IO as possible in the affected region.
199 * The first pass will remove most pages, so the search cost of the second pass
202 * When looking at page->index outside the page lock we need to be careful to
203 * copy it into a local to avoid races (it could change at any time).
205 * We pass down the cache-hot hint to the page freeing code. Even if the
206 * mapping is large, it is probably the case that the final pages are the most
207 * recently touched, and freeing happens in ascending file offset order.
209 void truncate_inode_pages_range(struct address_space *mapping,
210 loff_t lstart, loff_t lend)
212 const pgoff_t start = (lstart + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
214 const unsigned partial = lstart & (PAGE_CACHE_SIZE - 1);
219 cleancache_flush_inode(mapping);
220 if (mapping->nrpages == 0)
223 BUG_ON((lend & (PAGE_CACHE_SIZE - 1)) != (PAGE_CACHE_SIZE - 1));
224 end = (lend >> PAGE_CACHE_SHIFT);
226 pagevec_init(&pvec, 0);
228 while (next <= end &&
229 pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
230 mem_cgroup_uncharge_start();
231 for (i = 0; i < pagevec_count(&pvec); i++) {
232 struct page *page = pvec.pages[i];
233 pgoff_t page_index = page->index;
235 if (page_index > end) {
240 if (page_index > next)
243 if (!trylock_page(page))
245 if (PageWriteback(page)) {
249 truncate_inode_page(mapping, page);
252 pagevec_release(&pvec);
253 mem_cgroup_uncharge_end();
258 struct page *page = find_lock_page(mapping, start - 1);
260 wait_on_page_writeback(page);
261 truncate_partial_page(page, partial);
263 page_cache_release(page);
270 if (!pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
276 if (pvec.pages[0]->index > end) {
277 pagevec_release(&pvec);
280 mem_cgroup_uncharge_start();
281 for (i = 0; i < pagevec_count(&pvec); i++) {
282 struct page *page = pvec.pages[i];
284 if (page->index > end)
287 wait_on_page_writeback(page);
288 truncate_inode_page(mapping, page);
289 if (page->index > next)
294 pagevec_release(&pvec);
295 mem_cgroup_uncharge_end();
297 cleancache_flush_inode(mapping);
299 EXPORT_SYMBOL(truncate_inode_pages_range);
302 * truncate_inode_pages - truncate *all* the pages from an offset
303 * @mapping: mapping to truncate
304 * @lstart: offset from which to truncate
306 * Called under (and serialised by) inode->i_mutex.
308 void truncate_inode_pages(struct address_space *mapping, loff_t lstart)
310 truncate_inode_pages_range(mapping, lstart, (loff_t)-1);
312 EXPORT_SYMBOL(truncate_inode_pages);
315 * invalidate_mapping_pages - Invalidate all the unlocked pages of one inode
316 * @mapping: the address_space which holds the pages to invalidate
317 * @start: the offset 'from' which to invalidate
318 * @end: the offset 'to' which to invalidate (inclusive)
320 * This function only removes the unlocked pages, if you want to
321 * remove all the pages of one inode, you must call truncate_inode_pages.
323 * invalidate_mapping_pages() will not block on IO activity. It will not
324 * invalidate pages which are dirty, locked, under writeback or mapped into
327 unsigned long invalidate_mapping_pages(struct address_space *mapping,
328 pgoff_t start, pgoff_t end)
331 pgoff_t next = start;
333 unsigned long count = 0;
336 pagevec_init(&pvec, 0);
337 while (next <= end &&
338 pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
339 mem_cgroup_uncharge_start();
340 for (i = 0; i < pagevec_count(&pvec); i++) {
341 struct page *page = pvec.pages[i];
345 lock_failed = !trylock_page(page);
348 * We really shouldn't be looking at the ->index of an
349 * unlocked page. But we're not allowed to lock these
350 * pages. So we rely upon nobody altering the ->index
351 * of this (pinned-by-us) page.
360 ret = invalidate_inode_page(page);
363 * Invalidation is a hint that the page is no longer
364 * of interest and try to speed up its reclaim.
367 deactivate_page(page);
372 pagevec_release(&pvec);
373 mem_cgroup_uncharge_end();
378 EXPORT_SYMBOL(invalidate_mapping_pages);
381 * This is like invalidate_complete_page(), except it ignores the page's
382 * refcount. We do this because invalidate_inode_pages2() needs stronger
383 * invalidation guarantees, and cannot afford to leave pages behind because
384 * shrink_page_list() has a temp ref on them, or because they're transiently
385 * sitting in the lru_cache_add() pagevecs.
388 invalidate_complete_page2(struct address_space *mapping, struct page *page)
390 if (page->mapping != mapping)
393 if (page_has_private(page) && !try_to_release_page(page, GFP_KERNEL))
396 spin_lock_irq(&mapping->tree_lock);
400 clear_page_mlock(page);
401 BUG_ON(page_has_private(page));
402 __delete_from_page_cache(page);
403 spin_unlock_irq(&mapping->tree_lock);
404 mem_cgroup_uncharge_cache_page(page);
406 if (mapping->a_ops->freepage)
407 mapping->a_ops->freepage(page);
409 page_cache_release(page); /* pagecache ref */
412 spin_unlock_irq(&mapping->tree_lock);
416 static int do_launder_page(struct address_space *mapping, struct page *page)
418 if (!PageDirty(page))
420 if (page->mapping != mapping || mapping->a_ops->launder_page == NULL)
422 return mapping->a_ops->launder_page(page);
426 * invalidate_inode_pages2_range - remove range of pages from an address_space
427 * @mapping: the address_space
428 * @start: the page offset 'from' which to invalidate
429 * @end: the page offset 'to' which to invalidate (inclusive)
431 * Any pages which are found to be mapped into pagetables are unmapped prior to
434 * Returns -EBUSY if any pages could not be invalidated.
436 int invalidate_inode_pages2_range(struct address_space *mapping,
437 pgoff_t start, pgoff_t end)
444 int did_range_unmap = 0;
447 cleancache_flush_inode(mapping);
448 pagevec_init(&pvec, 0);
450 while (next <= end && !wrapped &&
451 pagevec_lookup(&pvec, mapping, next,
452 min(end - next, (pgoff_t)PAGEVEC_SIZE - 1) + 1)) {
453 mem_cgroup_uncharge_start();
454 for (i = 0; i < pagevec_count(&pvec); i++) {
455 struct page *page = pvec.pages[i];
459 if (page->mapping != mapping) {
463 page_index = page->index;
464 next = page_index + 1;
467 if (page_index > end) {
471 wait_on_page_writeback(page);
472 if (page_mapped(page)) {
473 if (!did_range_unmap) {
475 * Zap the rest of the file in one hit.
477 unmap_mapping_range(mapping,
478 (loff_t)page_index<<PAGE_CACHE_SHIFT,
479 (loff_t)(end - page_index + 1)
487 unmap_mapping_range(mapping,
488 (loff_t)page_index<<PAGE_CACHE_SHIFT,
492 BUG_ON(page_mapped(page));
493 ret2 = do_launder_page(mapping, page);
495 if (!invalidate_complete_page2(mapping, page))
502 pagevec_release(&pvec);
503 mem_cgroup_uncharge_end();
506 cleancache_flush_inode(mapping);
509 EXPORT_SYMBOL_GPL(invalidate_inode_pages2_range);
512 * invalidate_inode_pages2 - remove all pages from an address_space
513 * @mapping: the address_space
515 * Any pages which are found to be mapped into pagetables are unmapped prior to
518 * Returns -EBUSY if any pages could not be invalidated.
520 int invalidate_inode_pages2(struct address_space *mapping)
522 return invalidate_inode_pages2_range(mapping, 0, -1);
524 EXPORT_SYMBOL_GPL(invalidate_inode_pages2);
527 * truncate_pagecache - unmap and remove pagecache that has been truncated
529 * @old: old file offset
530 * @new: new file offset
532 * inode's new i_size must already be written before truncate_pagecache
535 * This function should typically be called before the filesystem
536 * releases resources associated with the freed range (eg. deallocates
537 * blocks). This way, pagecache will always stay logically coherent
538 * with on-disk format, and the filesystem would not have to deal with
539 * situations such as writepage being called for a page that has already
540 * had its underlying blocks deallocated.
542 void truncate_pagecache(struct inode *inode, loff_t old, loff_t new)
544 struct address_space *mapping = inode->i_mapping;
547 * unmap_mapping_range is called twice, first simply for
548 * efficiency so that truncate_inode_pages does fewer
549 * single-page unmaps. However after this first call, and
550 * before truncate_inode_pages finishes, it is possible for
551 * private pages to be COWed, which remain after
552 * truncate_inode_pages finishes, hence the second
553 * unmap_mapping_range call must be made for correctness.
555 unmap_mapping_range(mapping, new + PAGE_SIZE - 1, 0, 1);
556 truncate_inode_pages(mapping, new);
557 unmap_mapping_range(mapping, new + PAGE_SIZE - 1, 0, 1);
559 EXPORT_SYMBOL(truncate_pagecache);
562 * truncate_setsize - update inode and pagecache for a new file size
564 * @newsize: new file size
566 * truncate_setsize updates i_size and performs pagecache truncation (if
567 * necessary) to @newsize. It will be typically be called from the filesystem's
568 * setattr function when ATTR_SIZE is passed in.
570 * Must be called with inode_mutex held and before all filesystem specific
571 * block truncation has been performed.
573 void truncate_setsize(struct inode *inode, loff_t newsize)
577 oldsize = inode->i_size;
578 i_size_write(inode, newsize);
580 truncate_pagecache(inode, oldsize, newsize);
582 EXPORT_SYMBOL(truncate_setsize);
585 * vmtruncate - unmap mappings "freed" by truncate() syscall
586 * @inode: inode of the file used
587 * @offset: file offset to start truncating
589 * This function is deprecated and truncate_setsize or truncate_pagecache
590 * should be used instead, together with filesystem specific block truncation.
592 int vmtruncate(struct inode *inode, loff_t offset)
596 error = inode_newsize_ok(inode, offset);
600 truncate_setsize(inode, offset);
601 if (inode->i_op->truncate)
602 inode->i_op->truncate(inode);
605 EXPORT_SYMBOL(vmtruncate);