mm, dax: convert vmf_insert_pfn_pmd() to pfn_t

Similar to the conversion of vm_insert_mixed() use pfn_t in the
vmf_insert_pfn_pmd() to tag the resulting pte with _PAGE_DEVICE when the
pfn is backed by a devm_memremap_pages() mapping.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave@sr71.net>
Cc: Matthew Wilcox <willy@linux.intel.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/pfn_t.h b/include/linux/pfn_t.h
index bdaa275..0703b53 100644
--- a/include/linux/pfn_t.h
+++ b/include/linux/pfn_t.h
@@ -77,6 +77,13 @@
 }
 #endif
 
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+static inline pmd_t pfn_t_pmd(pfn_t pfn, pgprot_t pgprot)
+{
+	return pfn_pmd(pfn_t_to_pfn(pfn), pgprot);
+}
+#endif
+
 #ifdef __HAVE_ARCH_PTE_DEVMAP
 static inline bool pfn_t_devmap(pfn_t pfn)
 {
@@ -90,5 +97,6 @@
 	return false;
 }
 pte_t pte_mkdevmap(pte_t pte);
+pmd_t pmd_mkdevmap(pmd_t pmd);
 #endif
 #endif /* _LINUX_PFN_T_H_ */