new helper: file_inode(file)

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/kernel/fork.c b/kernel/fork.c
index c535f33..4ff724f 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -413,7 +413,7 @@
 		tmp->vm_next = tmp->vm_prev = NULL;
 		file = tmp->vm_file;
 		if (file) {
-			struct inode *inode = file->f_path.dentry->d_inode;
+			struct inode *inode = file_inode(file);
 			struct address_space *mapping = file->f_mapping;
 
 			get_file(file);