Description of problem:


Upstream has a description for erasure coding with overwrites. We need to determine if it should be supported in downstream.

http://docs.ceph.com/docs/master/rados/operations/erasure-code/#erasure-coding-with-overwrites

Set pool values would have the following:

allow_ec_overwrites::
Description;;
  Whether writes to an erasure coded pool can update part of an object,
  so cephfs and rbd can use it. See Erasure Coding with Overwrites for
  more details.
Type;;
  Boolean