xen: add pinned page flag

Add a new definition for PG_owner_priv_1 to define PG_pinned on Xen
pagetable pages.
Signed-off-by: NJeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: NChris Wright <chrisw@sous-sol.org>

include/linux/page-flags.h

@@ -92,6 +92,7 @@
 
 /* PG_owner_priv_1 users should have descriptive aliases */
 #define PG_checked		PG_owner_priv_1 /* Used by some filesystems */
+#define PG_pinned		PG_owner_priv_1	/* Xen pinned pagetable */
 
 #if (BITS_PER_LONG > 32)
 /*
@@ -170,6 +171,10 @@ static inline void SetPageUptodate(struct page *page)
 #define SetPageChecked(page)	set_bit(PG_checked, &(page)->flags)
 #define ClearPageChecked(page)	clear_bit(PG_checked, &(page)->flags)
 
+#define PagePinned(page)	test_bit(PG_pinned, &(page)->flags)
+#define SetPagePinned(page)	set_bit(PG_pinned, &(page)->flags)
+#define ClearPagePinned(page)	clear_bit(PG_pinned, &(page)->flags)
+
 #define PageReserved(page)	test_bit(PG_reserved, &(page)->flags)
 #define SetPageReserved(page)	set_bit(PG_reserved, &(page)->flags)
 #define ClearPageReserved(page)	clear_bit(PG_reserved, &(page)->flags)