[22/41] compound pages: Add new support functions

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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 <[email protected]>
 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 1692dd6..6f3a8d6 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -363,6 +363,21 @@ 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

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