This patch adds some code for parsing fs.permissions.umask-mode and sending permission bits in the hdfsCreateDirectory rpc to the NameNode. This fixes a bug whereby hdfsCreateDirectory would fail with this message:
org.apache.hadoop.native.HadoopCore.IOException: conn_process_response: error com.google.protobuf.UninitializedMessageException: Message missing required fields: masked.perm
Clearly we'll also need this for the file write path, when we're creating new files.
We don't handle "fancy" fs.permissions.umask-mode values like "rw-r-
r-" etc. yet. It's not too difficult to do that, but it's better to do it in a follow-on JIRA to avoid complicating this one. For now, we just deal with numeric umasks.