| /* |
| * mm/truncate.c - code for taking down pages from address_spaces |
| * |
| * Copyright (C) 2002, Linus Torvalds |
| * |
| * 10Sep2002 akpm@zip.com.au |
| * Initial version. |
| */ |
| |
| #include <linux/kernel.h> |
| #include <linux/mm.h> |
| #include <linux/module.h> |
| #include <linux/pagemap.h> |
| #include <linux/pagevec.h> |
| #include <linux/buffer_head.h> /* grr. try_to_release_page, |
| do_invalidatepage */ |
| |
| |
| static inline void truncate_partial_page(struct page *page, unsigned partial) |
| { |
| memclear_highpage_flush(page, partial, PAGE_CACHE_SIZE-partial); |
| if (PagePrivate(page)) |
| do_invalidatepage(page, partial); |
| } |
| |
| /* |
| * If truncate cannot remove the fs-private metadata from the page, the page |
| * becomes anonymous. It will be left on the LRU and may even be mapped into |
| * user pagetables if we're racing with filemap_nopage(). |
| * |
| * We need to bale out if page->mapping is no longer equal to the original |
| * mapping. This happens a) when the VM reclaimed the page while we waited on |
| * its lock, b) when a concurrent invalidate_inode_pages got there first and |
| * c) when tmpfs swizzles a page between a tmpfs inode and swapper_space. |
| */ |
| static void |
| truncate_complete_page(struct address_space *mapping, struct page *page) |
| { |
| if (page->mapping != mapping) |
| return; |
| |
| if (PagePrivate(page)) |
| do_invalidatepage(page, 0); |
| |
| clear_page_dirty(page); |
| ClearPageUptodate(page); |
| ClearPageMappedToDisk(page); |
| remove_from_page_cache(page); |
| page_cache_release(page); /* pagecache ref */ |
| } |
| |
| /* |
| * This is for invalidate_inode_pages(). That function can be called at |
| * any time, and is not supposed to throw away dirty pages. But pages can |
| * be marked dirty at any time too. So we re-check the dirtiness inside |
| * ->tree_lock. That provides exclusion against the __set_page_dirty |
| * functions. |
| * |
| * Returns non-zero if the page was successfully invalidated. |
| */ |
| static int |
| invalidate_complete_page(struct address_space *mapping, struct page *page) |
| { |
| if (page->mapping != mapping) |
| return 0; |
| |
| if (PagePrivate(page) && !try_to_release_page(page, 0)) |
| return 0; |
| |
| write_lock_irq(&mapping->tree_lock); |
| if (PageDirty(page)) { |
| write_unlock_irq(&mapping->tree_lock); |
| return 0; |
| } |
| |
| BUG_ON(PagePrivate(page)); |
| __remove_from_page_cache(page); |
| write_unlock_irq(&mapping->tree_lock); |
| ClearPageUptodate(page); |
| page_cache_release(page); /* pagecache ref */ |
| return 1; |
| } |
| |
| /** |
| * truncate_inode_pages - truncate range of pages specified by start and |
| * end byte offsets |
| * @mapping: mapping to truncate |
| * @lstart: offset from which to truncate |
| * @lend: offset to which to truncate |
| * |
| * Truncate the page cache, removing the pages that are between |
| * specified offsets (and zeroing out partial page |
| * (if lstart is not page aligned)). |
| * |
| * Truncate takes two passes - the first pass is nonblocking. It will not |
| * block on page locks and it will not block on writeback. The second pass |
| * will wait. This is to prevent as much IO as possible in the affected region. |
| * The first pass will remove most pages, so the search cost of the second pass |
| * is low. |
| * |
| * When looking at page->index outside the page lock we need to be careful to |
| * copy it into a local to avoid races (it could change at any time). |
| * |
| * We pass down the cache-hot hint to the page freeing code. Even if the |
| * mapping is large, it is probably the case that the final pages are the most |
| * recently touched, and freeing happens in ascending file offset order. |
| */ |
| void truncate_inode_pages_range(struct address_space *mapping, |
| loff_t lstart, loff_t lend) |
| { |
| const pgoff_t start = (lstart + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT; |
| pgoff_t end; |
| const unsigned partial = lstart & (PAGE_CACHE_SIZE - 1); |
| struct pagevec pvec; |
| pgoff_t next; |
| int i; |
| |
| if (mapping->nrpages == 0) |
| return; |
| |
| BUG_ON((lend & (PAGE_CACHE_SIZE - 1)) != (PAGE_CACHE_SIZE - 1)); |
| end = (lend >> PAGE_CACHE_SHIFT); |
| |
| pagevec_init(&pvec, 0); |
| next = start; |
| while (next <= end && |
| pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) { |
| for (i = 0; i < pagevec_count(&pvec); i++) { |
| struct page *page = pvec.pages[i]; |
| pgoff_t page_index = page->index; |
| |
| if (page_index > end) { |
| next = page_index; |
| break; |
| } |
| |
| if (page_index > next) |
| next = page_index; |
| next++; |
| if (TestSetPageLocked(page)) |
| continue; |
| if (PageWriteback(page)) { |
| unlock_page(page); |
| continue; |
| } |
| truncate_complete_page(mapping, page); |
| unlock_page(page); |
| } |
| pagevec_release(&pvec); |
| cond_resched(); |
| } |
| |
| if (partial) { |
| struct page *page = find_lock_page(mapping, start - 1); |
| if (page) { |
| wait_on_page_writeback(page); |
| truncate_partial_page(page, partial); |
| unlock_page(page); |
| page_cache_release(page); |
| } |
| } |
| |
| next = start; |
| for ( ; ; ) { |
| cond_resched(); |
| if (!pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) { |
| if (next == start) |
| break; |
| next = start; |
| continue; |
| } |
| if (pvec.pages[0]->index > end) { |
| pagevec_release(&pvec); |
| break; |
| } |
| for (i = 0; i < pagevec_count(&pvec); i++) { |
| struct page *page = pvec.pages[i]; |
| |
| if (page->index > end) |
| break; |
| lock_page(page); |
| wait_on_page_writeback(page); |
| if (page->index > next) |
| next = page->index; |
| next++; |
| truncate_complete_page(mapping, page); |
| unlock_page(page); |
| } |
| pagevec_release(&pvec); |
| } |
| } |
| EXPORT_SYMBOL(truncate_inode_pages_range); |
| |
| /** |
| * truncate_inode_pages - truncate *all* the pages from an offset |
| * @mapping: mapping to truncate |
| * @lstart: offset from which to truncate |
| * |
| * Called under (and serialised by) inode->i_mutex. |
| */ |
| void truncate_inode_pages(struct address_space *mapping, loff_t lstart) |
| { |
| truncate_inode_pages_range(mapping, lstart, (loff_t)-1); |
| } |
| EXPORT_SYMBOL(truncate_inode_pages); |
| |
| /** |
| * invalidate_mapping_pages - Invalidate all the unlocked pages of one inode |
| * @mapping: the address_space which holds the pages to invalidate |
| * @start: the offset 'from' which to invalidate |
| * @end: the offset 'to' which to invalidate (inclusive) |
| * |
| * This function only removes the unlocked pages, if you want to |
| * remove all the pages of one inode, you must call truncate_inode_pages. |
| * |
| * invalidate_mapping_pages() will not block on IO activity. It will not |
| * invalidate pages which are dirty, locked, under writeback or mapped into |
| * pagetables. |
| */ |
| unsigned long invalidate_mapping_pages(struct address_space *mapping, |
| pgoff_t start, pgoff_t end) |
| { |
| struct pagevec pvec; |
| pgoff_t next = start; |
| unsigned long ret = 0; |
| int i; |
| |
| pagevec_init(&pvec, 0); |
| while (next <= end && |
| pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) { |
| for (i = 0; i < pagevec_count(&pvec); i++) { |
| struct page *page = pvec.pages[i]; |
| |
| if (TestSetPageLocked(page)) { |
| next++; |
| continue; |
| } |
| if (page->index > next) |
| next = page->index; |
| next++; |
| if (PageDirty(page) || PageWriteback(page)) |
| goto unlock; |
| if (page_mapped(page)) |
| goto unlock; |
| ret += invalidate_complete_page(mapping, page); |
| unlock: |
| unlock_page(page); |
| if (next > end) |
| break; |
| } |
| pagevec_release(&pvec); |
| } |
| return ret; |
| } |
| |
| unsigned long invalidate_inode_pages(struct address_space *mapping) |
| { |
| return invalidate_mapping_pages(mapping, 0, ~0UL); |
| } |
| |
| EXPORT_SYMBOL(invalidate_inode_pages); |
| |
| /** |
| * invalidate_inode_pages2_range - remove range of pages from an address_space |
| * @mapping: the address_space |
| * @start: the page offset 'from' which to invalidate |
| * @end: the page offset 'to' which to invalidate (inclusive) |
| * |
| * Any pages which are found to be mapped into pagetables are unmapped prior to |
| * invalidation. |
| * |
| * Returns -EIO if any pages could not be invalidated. |
| */ |
| int invalidate_inode_pages2_range(struct address_space *mapping, |
| pgoff_t start, pgoff_t end) |
| { |
| struct pagevec pvec; |
| pgoff_t next; |
| int i; |
| int ret = 0; |
| int did_range_unmap = 0; |
| int wrapped = 0; |
| |
| pagevec_init(&pvec, 0); |
| next = start; |
| while (next <= end && !ret && !wrapped && |
| pagevec_lookup(&pvec, mapping, next, |
| min(end - next, (pgoff_t)PAGEVEC_SIZE - 1) + 1)) { |
| for (i = 0; !ret && i < pagevec_count(&pvec); i++) { |
| struct page *page = pvec.pages[i]; |
| pgoff_t page_index; |
| int was_dirty; |
| |
| lock_page(page); |
| if (page->mapping != mapping) { |
| unlock_page(page); |
| continue; |
| } |
| page_index = page->index; |
| next = page_index + 1; |
| if (next == 0) |
| wrapped = 1; |
| if (page_index > end) { |
| unlock_page(page); |
| break; |
| } |
| wait_on_page_writeback(page); |
| while (page_mapped(page)) { |
| if (!did_range_unmap) { |
| /* |
| * Zap the rest of the file in one hit. |
| */ |
| unmap_mapping_range(mapping, |
| (loff_t)page_index<<PAGE_CACHE_SHIFT, |
| (loff_t)(end - page_index + 1) |
| << PAGE_CACHE_SHIFT, |
| 0); |
| did_range_unmap = 1; |
| } else { |
| /* |
| * Just zap this page |
| */ |
| unmap_mapping_range(mapping, |
| (loff_t)page_index<<PAGE_CACHE_SHIFT, |
| PAGE_CACHE_SIZE, 0); |
| } |
| } |
| was_dirty = test_clear_page_dirty(page); |
| if (!invalidate_complete_page(mapping, page)) { |
| if (was_dirty) |
| set_page_dirty(page); |
| ret = -EIO; |
| } |
| unlock_page(page); |
| } |
| pagevec_release(&pvec); |
| cond_resched(); |
| } |
| return ret; |
| } |
| EXPORT_SYMBOL_GPL(invalidate_inode_pages2_range); |
| |
| /** |
| * invalidate_inode_pages2 - remove all pages from an address_space |
| * @mapping: the address_space |
| * |
| * Any pages which are found to be mapped into pagetables are unmapped prior to |
| * invalidation. |
| * |
| * Returns -EIO if any pages could not be invalidated. |
| */ |
| int invalidate_inode_pages2(struct address_space *mapping) |
| { |
| return invalidate_inode_pages2_range(mapping, 0, -1); |
| } |
| EXPORT_SYMBOL_GPL(invalidate_inode_pages2); |