[PATCH 05/10] mm: Methods for teaching filesystems about PG_swapcache pages
From: Mel Gorman <mgorman@suse.de>
Date: 2011-09-09 11:02:54
Also in:
linux-mm, linux-nfs, lkml
Subsystem:
memory management, memory management - core, memory management - swap, page cache, the rest · Maintainers:
Andrew Morton, David Hildenbrand, Chris Li, Kairui Song, Matthew Wilcox, Jan Kara, Linus Torvalds
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 <redacted> Signed-off-by: Mel Gorman <mgorman@suse.de> --- 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 7438071..45442a8 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h@@ -787,6 +787,17 @@ 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;
@@ -803,6 +814,20 @@ 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 cfaaa69..d4d4bda 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h@@ -286,6 +286,11 @@ static inline loff_t page_offset(struct page *page) return ((loff_t)page->index) << PAGE_CACHE_SHIFT; } +static inline loff_t page_file_offset(struct page *page) +{ + return ((loff_t)page_file_index(page)) << PAGE_CACHE_SHIFT; +} + extern pgoff_t linear_hugepage_index(struct vm_area_struct *vma, unsigned long address);
diff --git a/mm/swapfile.c b/mm/swapfile.c
index c49cb33..806b994 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c@@ -2232,6 +2232,25 @@ 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. */
--
1.7.3.4
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