Major Description
Patrick Hunt noticed that our HdfsDirectory code was a bit behind Blur here - the read call we are using may not read all of the requested bytes - it returns the number of bytes actually written - which we ignore.
Blur moved to using a seek and then readFully call - synchronizing across the two calls to deal with clones.
We have seen that really kills performance, and using the readFully call that lets you pass the position rather than first doing a seek, performs much better and does not require the synchronization.
I also noticed that the seekInternal impl should not seek but be a no op since we are seeking on the read.