Btrfs: Add inode map, and the start of file extent items

Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c
index f5b36c7..24cfd6d 100644
--- a/fs/btrfs/file-item.c
+++ b/fs/btrfs/file-item.c
@@ -4,4 +4,10 @@
 #include "radix-tree.h"
 #include "ctree.h"
 #include "disk-io.h"
+#include "transaction.h"
 
+int btrfs_create_file(struct btrfs_trans_handle *trans,
+		      struct btrfs_root *root, u64 dirid, u64 *objectid)
+{
+	return 0;
+}