From 97cecb5a254fec22d28ef32235d888bfbfd7c783 Mon Sep 17 00:00:00 2001 From: Minchan Kim Date: Tue, 22 Mar 2011 16:30:53 -0700 Subject: mm: introduce delete_from_page_cache() Presently we increase the page refcount in add_to_page_cache() but don't decrease it in remove_from_page_cache(). Such asymmetry adds confusion, requiring that callers notice it and a comment explaining why they release a page reference. It's not a good API. A long time ago, Hugh tried it (http://lkml.org/lkml/2004/10/24/140) but gave up because reiser4's drop_page() had to unlock the page between removing it from page cache and doing the page_cache_release(). But now the situation is changed. I think at least things in current mainline don't have any obstacles. The problem is for out-of-mainline filesystems - if they have done such things as reiser4, this patch could be a problem but they will discover this at compile time since we remove remove_from_page_cache(). This patch: This function works as just wrapper remove_from_page_cache(). The difference is that it decreases page references in itself. So caller have to make sure it has a page reference before calling. This patch is ready for removing remove_from_page_cache(). Signed-off-by: Minchan Kim Cc: Christoph Hellwig Acked-by: Hugh Dickins Acked-by: Mel Gorman Reviewed-by: KAMEZAWA Hiroyuki Reviewed-by: Johannes Weiner Reviewed-by: KOSAKI Motohiro Cc: Edward Shishkin Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/pagemap.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include') diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index 26946ad483bf..0aa258f4678d 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -455,6 +455,7 @@ int add_to_page_cache_locked(struct page *page, struct address_space *mapping, pgoff_t index, gfp_t gfp_mask); int add_to_page_cache_lru(struct page *page, struct address_space *mapping, pgoff_t index, gfp_t gfp_mask); +extern void delete_from_page_cache(struct page *page); extern void remove_from_page_cache(struct page *page); extern void __remove_from_page_cache(struct page *page); int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask); -- cgit v1.2.3