-static ssize_t idmap_pipe_upcall(struct file *, struct rpc_pipe_msg *, char *,
- size_t);
-static ssize_t idmap_pipe_downcall(struct file *, const char *, size_t);
+static ssize_t idmap_pipe_upcall(struct file *, struct rpc_pipe_msg *,
+ char __user *, size_t);
+static ssize_t idmap_pipe_downcall(struct file *, const char __user *,
+ size_t);