[22/36] compound pages: Add new support functions

clameter
2007-08-28T19:21:41Z

[-- Attachment #1: 0022-compound-pages-Add-new-support-functions.patch --]
[-- Type: text/plain, Size: 1082 bytes --]

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 files changed, 15 insertions(+), 0 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 3e9e8fe..fa4cbab 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -362,6 +362,21 @@ static inline void set_compound_order(struct page *page, unsigned long order)
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
--
1.5.2.4

--