new helper: file_inode(file)

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/autofs4/autofs_i.h b/fs/autofs4/autofs_i.h
index b785e77..3f1128b 100644
--- a/fs/autofs4/autofs_i.h
+++ b/fs/autofs4/autofs_i.h
@@ -273,7 +273,7 @@
 {
 	if (!pipe->f_op || !pipe->f_op->write)
 		return -EINVAL;
-	if (!S_ISFIFO(pipe->f_dentry->d_inode->i_mode))
+	if (!S_ISFIFO(file_inode(pipe)->i_mode))
 		return -EINVAL;
 	/* We want a packet pipe */
 	pipe->f_flags |= O_DIRECT;