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Subject[PATCH] add page->mapping handling interface [1/35] interface definitions

- changes page->mapping from address_space* to unsigned long
- add page_mapping_anon() function.
- add linux/page-cache.h
- add page_inode() function
- add page_is_pagecache() function
- add pagecaceh_consisten() function for pagecache consistency test.
- expoterd swapper_space. inline function page_mapping() refers this.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

---
include/linux/fs.h | 1 +
include/linux/mm.h | 20 +++++++++++++++++---
include/linux/mm_types.h | 2 +-
include/linux/page-cache.h | 39 +++++++++++++++++++++++++++++++++++++++
mm/swap_state.c | 2 ++
5 files changed, 60 insertions(+), 4 deletions(-)

Index: test-2.6.23-rc4-mm1/include/linux/page-cache.h
===================================================================
--- /dev/null
+++ test-2.6.23-rc4-mm1/include/linux/page-cache.h
@@ -0,0 +1,39 @@
+/*
+ * For interface definitions between memory management and file systems.
+ * - This file defines small interface functions for handling page cache.
+ */
+
+#ifndef _LINUX_PAGECACHE_H
+#define _LINUX_PAGECACHE_H
+
+#include <linux/mm.h>
+/* page_mapping_xxx() function is defined in mm.h */
+
+static inline int page_is_pagecache(struct page *page)
+{
+ if (!page->mapping || (page->mapping & PAGE_MAPPING_ANON))
+ return 0;
+ return 1;
+}
+
+/*
+ * Return an inode this page belongs to
+ */
+
+static inline struct inode *page_inode(struct page *page)
+{
+ if (!page_is_pagecache(page))
+ return NULL;
+ return page_mapping_cache(page)->host;
+}
+
+/*
+ * Test a page is a page-cache of an address_space.
+ */
+static inline int
+pagecache_consistent(struct page *page, struct address_space *as)
+{
+ return (page_mapping(page) == as);
+}
+
+#endif
Index: test-2.6.23-rc4-mm1/include/linux/fs.h
===================================================================
--- test-2.6.23-rc4-mm1.orig/include/linux/fs.h
+++ test-2.6.23-rc4-mm1/include/linux/fs.h
@@ -582,6 +582,7 @@ static inline int mapping_writably_mappe
return mapping->i_mmap_writable != 0;
}

+#include <linux/page-cache.h>
/*
* Use sequence counter to get consistent i_size on 32-bit processors.
*/
Index: test-2.6.23-rc4-mm1/include/linux/mm_types.h
===================================================================
--- test-2.6.23-rc4-mm1.orig/include/linux/mm_types.h
+++ test-2.6.23-rc4-mm1/include/linux/mm_types.h
@@ -48,7 +48,7 @@ struct page {
* indicates order in the buddy
* system if PG_buddy is set.
*/
- struct address_space *mapping; /* If low bit clear, points to
+ unsigned long mapping; /* If low bit clear, points to
* inode address_space, or NULL.
* If page mapped as anonymous
* memory, low bit is set, and
Index: test-2.6.23-rc4-mm1/include/linux/mm.h
===================================================================
--- test-2.6.23-rc4-mm1.orig/include/linux/mm.h
+++ test-2.6.23-rc4-mm1/include/linux/mm.h
@@ -563,7 +563,7 @@ void page_address_init(void);
extern struct address_space swapper_space;
static inline struct address_space *page_mapping(struct page *page)
{
- struct address_space *mapping = page->mapping;
+ struct address_space *mapping = (struct address_space *)page->mapping;

VM_BUG_ON(PageSlab(page));
if (unlikely(PageSwapCache(page)))
@@ -579,7 +579,21 @@ static inline struct address_space *page

static inline int PageAnon(struct page *page)
{
- return ((unsigned long)page->mapping & PAGE_MAPPING_ANON) != 0;
+ return (page->mapping & PAGE_MAPPING_ANON) != 0;
+}
+
+static inline struct anon_vma *page_mapping_anon(struct page *page)
+{
+ if (PageAnon(page))
+ return (struct anon_vma *)(page->mapping - PAGE_MAPPING_ANON);
+ return NULL;
+}
+
+static inline struct address_space *page_mapping_cache(struct page *page)
+{
+ if (PageAnon(page))
+ return NULL;
+ return (struct address_space *) page->mapping;
}

/*
@@ -848,7 +862,7 @@ static inline pmd_t *pmd_alloc(struct mm
#define pte_lock_init(_page) do { \
spin_lock_init(__pte_lockptr(_page)); \
} while (0)
-#define pte_lock_deinit(page) ((page)->mapping = NULL)
+#define pte_lock_deinit(page) ((page)->mapping = 0)
#define pte_lockptr(mm, pmd) ({(void)(mm); __pte_lockptr(pmd_page(*(pmd)));})
#else
/*
Index: test-2.6.23-rc4-mm1/mm/swap_state.c
===================================================================
--- test-2.6.23-rc4-mm1.orig/mm/swap_state.c
+++ test-2.6.23-rc4-mm1/mm/swap_state.c
@@ -45,6 +45,8 @@ struct address_space swapper_space = {
.backing_dev_info = &swap_backing_dev_info,
};

+EXPORT_SYMBOL(swapper_space);
+
#define INC_CACHE_INFO(x) do { swap_cache_info.x++; } while (0)

static struct {
-
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