The concept of a metadata server is no longer needed in a distributed file system. In distributed file systems, it offers a common view point of all the files separated among different servers. Files/directories on these storage servers are accessed in normal ways.
For example, the permissions for files/directories can be set as in usual system permission model, i.e. the owner, group and others. The access to the file system basically depends on how the particular protocol is designed to work on the same.