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Subject[24/37] compound pages: Add new support functions
compound_pages(page)	-> Determines base pages of a compound page

compound_shift(page) -> Determine the page shift of a compound page

compound_size(page) -> Determine the size of a compound page

Signed-off-by: Christoph Lameter <clameter@sgi.com>

---
include/linux/mm.h | 15 +++++++++++++++
1 file changed, 15 insertions(+)

Index: vps/include/linux/mm.h
===================================================================
--- vps.orig/include/linux/mm.h 2007-06-11 15:56:37.000000000 -0700
+++ vps/include/linux/mm.h 2007-06-12 19:06:28.000000000 -0700
@@ -365,6 +365,21 @@ static inline void set_compound_order(st
page[1].lru.prev = (void *)order;
}

+static inline int compound_pages(struct page *page)
+{
+ return 1 << compound_order(page);
+}
+
+static inline int compound_shift(struct page *page)
+{
+ return PAGE_SHIFT + compound_order(page);
+}
+
+static inline int compound_size(struct page *page)
+{
+ return PAGE_SIZE << compound_order(page);
+}
+
/*
* Multiple processes may "see" the same page. E.g. for untouched
* mappings of /dev/null, all processes see the same page full of
--
-
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