From: Xiaotian Feng Subject: [PATCH -mmotm 23/30] mm: methods for teaching filesystems about PG_swapcache pages Date: Tue, 13 Jul 2010 06:21:10 -0400 Message-ID: <20100713102110.2835.14816.sendpatchset@danny.redhat> References: <20100713101650.2835.15245.sendpatchset@danny.redhat> Cc: riel@redhat.com, cl@linux-foundation.org, a.p.zijlstra@chello.nl, Xiaotian Feng , linux-kernel@vger.kernel.org, lwang@redhat.com, penberg@cs.helsinki.fi, akpm@linux-foundation.org, davem@davemloft.net To: linux-mm@kvack.org, linux-nfs@vger.kernel.org, netdev@vger.kernel.org Return-path: In-Reply-To: <20100713101650.2835.15245.sendpatchset@danny.redhat> Sender: owner-linux-mm@kvack.org List-ID: >From 50e813068c51de733bbbdd04eb4af9c43919cd57 Mon Sep 17 00:00:00 2001 From: Xiaotian Feng Date: Tue, 13 Jul 2010 13:09:50 +0800 Subject: [PATCH 23/30] 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: Suresh Jayaraman Signed-off-by: Xiaotian Feng --- include/linux/mm.h | 25 +++++++++++++++++++++++++ include/linux/pagemap.h | 5 +++++ mm/swapfile.c | 19 +++++++++++++++++++ 3 files changed, 49 insertions(+), 0 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index 32033ba..0cf97fc 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -663,6 +663,17 @@ static inline void *page_rmapping(struct page *page) return (void *)((unsigned long)page->mapping & ~PAGE_MAPPING_FLAGS); } +extern struct address_space *__page_file_mapping(struct page *); + +static inline +struct address_space *page_file_mapping(struct page *page) +{ + if (unlikely(PageSwapCache(page))) + return __page_file_mapping(page); + + return page->mapping; +} + static inline int PageAnon(struct page *page) { return ((unsigned long)page->mapping & PAGE_MAPPING_ANON) != 0; @@ -679,6 +690,20 @@ static inline pgoff_t page_index(struct page *page) return page->index; } +extern pgoff_t __page_file_index(struct page *page); + +/* + * Return the file index of the page. Regular pagecache pages use ->index + * whereas swapcache pages use swp_offset(->private) + */ +static inline pgoff_t page_file_index(struct page *page) +{ + if (unlikely(PageSwapCache(page))) + return __page_file_index(page); + + return page->index; +} + /* * The atomic page->_mapcount, like _count, starts from -1: * so that transitions both from it and to it can be tracked, diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index e12cdc6..64eda5b 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -285,6 +285,11 @@ static inline loff_t page_offset(struct page *page) extern pgoff_t linear_hugepage_index(struct vm_area_struct *vma, unsigned long address); +static inline loff_t page_file_offset(struct page *page) +{ + return ((loff_t)page_file_index(page)) << PAGE_CACHE_SHIFT; +} + static inline pgoff_t linear_page_index(struct vm_area_struct *vma, unsigned long address) { diff --git a/mm/swapfile.c b/mm/swapfile.c index a7baef1..d8a05e4 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -2261,6 +2261,25 @@ struct swap_info_struct *page_swap_info(struct page *page) } /* + * out-of-line __page_file_ methods to avoid include hell. + */ + +struct address_space *__page_file_mapping(struct page *page) +{ + VM_BUG_ON(!PageSwapCache(page)); + return page_swap_info(page)->swap_file->f_mapping; +} +EXPORT_SYMBOL_GPL(__page_file_mapping); + +pgoff_t __page_file_index(struct page *page) +{ + swp_entry_t swap = { .val = page_private(page) }; + VM_BUG_ON(!PageSwapCache(page)); + return swp_offset(swap); +} +EXPORT_SYMBOL_GPL(__page_file_index); + +/* * swap_lock prevents swap_map being freed. Don't grab an extra * reference on the swaphandle, it doesn't matter if it becomes unused. */ -- 1.7.1.1 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org