mm: Export migrate_page_move_mapping and migrate_page_copy

Export these symbols such that UBIFS can implement
->migratepage.

Cc: stable@vger.kernel.org
Signed-off-by: Richard Weinberger <richard@nod.at>
Acked-by: Christoph Hellwig <hch@lst.de>
diff --git a/mm/migrate.c b/mm/migrate.c
index 9baf41c..bd3fdc2 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -431,6 +431,7 @@
 
 	return MIGRATEPAGE_SUCCESS;
 }
+EXPORT_SYMBOL(migrate_page_move_mapping);
 
 /*
  * The expected number of remaining references is the same as that
@@ -586,6 +587,7 @@
 
 	mem_cgroup_migrate(page, newpage);
 }
+EXPORT_SYMBOL(migrate_page_copy);
 
 /************************************************************
  *                    Migration functions