From ef6a3c63112e865d632ff7c478ba7c7160cad0d1 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Tue, 22 Mar 2011 16:30:52 -0700 Subject: mm: add replace_page_cache_page() function This function basically does: remove_from_page_cache(old); page_cache_release(old); add_to_page_cache_locked(new); Except it does this atomically, so there's no possibility for the "add" to fail because of a race. If memory cgroups are enabled, then the memory cgroup charge is also moved from the old page to the new. This function is currently used by fuse to move pages into the page cache on read, instead of copying the page contents. [minchan.kim@gmail.com: add freepage() hook to replace_page_cache_page()] Signed-off-by: Miklos Szeredi Acked-by: Rik van Riel Acked-by: KAMEZAWA Hiroyuki Cc: Mel Gorman Signed-off-by: Minchan Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/pagemap.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux/pagemap.h') diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index 9c66e99..26946ad 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -457,6 +457,7 @@ int add_to_page_cache_lru(struct page *page, struct address_space *mapping, pgoff_t index, gfp_t gfp_mask); 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); /* * Like add_to_page_cache_locked, but used to add newly allocated pages: -- cgit v1.1 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/linux/pagemap.h') diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index 26946ad..0aa258f 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 v1.1 From 702cfbf93aaf3a091b0c64c8766c1ade0a820c38 Mon Sep 17 00:00:00 2001 From: Minchan Kim Date: Tue, 22 Mar 2011 16:32:43 -0700 Subject: mm: goodbye remove_from_page_cache() Now delete_from_page_cache() replaces remove_from_page_cache(). So we remove remove_from_page_cache so fs or something out of mainline will notice it when compile time and can fix it. 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 Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/pagemap.h | 1 - 1 file changed, 1 deletion(-) (limited to 'include/linux/pagemap.h') diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index 0aa258f..ea36ff2 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -456,7 +456,6 @@ int add_to_page_cache_locked(struct page *page, struct address_space *mapping, 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 v1.1 From e64a782fec684c29a8204c51b3cb554dce588592 Mon Sep 17 00:00:00 2001 From: Minchan Kim Date: Tue, 22 Mar 2011 16:32:44 -0700 Subject: mm: change __remove_from_page_cache() Now we renamed remove_from_page_cache with delete_from_page_cache. As consistency of __remove_from_swap_cache and remove_from_swap_cache, we change internal page cache handling function name, too. 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 Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/pagemap.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux/pagemap.h') diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index ea36ff2..29ebba5 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -456,7 +456,7 @@ int add_to_page_cache_locked(struct page *page, struct address_space *mapping, 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 __delete_from_page_cache(struct page *page); int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask); /* -- cgit v1.1