VM: add "vm_insert_page()" function

This is what a lot of drivers will actually want to use to insert
individual pages into a user VMA.  It doesn't have the old PageReserved
restrictions of remap_pfn_range(), and it doesn't complain about partial
remappings.

The page you insert needs to be a nice clean kernel allocation, so you
can't insert arbitrary page mappings with this, but that's not what
people want.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 0e73f15..29f02d8 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -956,6 +956,7 @@
 unsigned long vmalloc_to_pfn(void *addr);
 int remap_pfn_range(struct vm_area_struct *, unsigned long addr,
 			unsigned long pfn, unsigned long size, pgprot_t);
+int vm_insert_page(struct vm_area_struct *, unsigned long addr, struct page *);
 
 struct page *follow_page(struct vm_area_struct *, unsigned long address,
 			unsigned int foll_flags);