From f981c5950fa85916ba49bea5d9a7a5078f47e569 Mon Sep 17 00:00:00 2001 From: Mel Gorman Date: Tue, 31 Jul 2012 16:44:47 -0700 Subject: mm: methods for teaching filesystems about PG_swapcache pages In order to teach filesystems to handle swap cache pages, three new page functions are introduced: pgoff_t page_file_index(struct page *); loff_t page_file_offset(struct page *); struct address_space *page_file_mapping(struct page *); page_file_index() - gives the offset of this page in the file in PAGE_CACHE_SIZE blocks. Like page->index is for mapped pages, this function also gives the correct index for PG_swapcache pages. page_file_offset() - uses page_file_index(), so that it will give the expected result, even for PG_swapcache pages. page_file_mapping() - gives the mapping backing the actual page; that is for swap cache pages it will give swap_file->f_mapping. Signed-off-by: Peter Zijlstra Signed-off-by: Mel Gorman Reviewed-by: Rik van Riel Cc: Christoph Hellwig Cc: David S. Miller Cc: Eric B Munson Cc: Eric Paris Cc: James Morris Cc: Mel Gorman Cc: Mike Christie Cc: Neil Brown Cc: Sebastian Andrzej Siewior Cc: Trond Myklebust Cc: Xiaotian Feng Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/swap.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux/swap.h') diff --git a/include/linux/swap.h b/include/linux/swap.h index 9a16bb1..e62425d 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -356,6 +356,7 @@ extern unsigned int count_swap_pages(int, int); extern sector_t map_swap_page(struct page *, struct block_device **); extern sector_t swapdev_block(int, pgoff_t); extern int page_swapcount(struct page *); +extern struct swap_info_struct *page_swap_info(struct page *); extern int reuse_swap_page(struct page *); extern int try_to_free_swap(struct page *); struct backing_dev_info; -- cgit v1.1