BTRFS file system has been updated to version 4.
EasyNAS is being tested for competability , and in the next release of EasyNAS it will be installed.  However it will not come in the online firmware update, you will have to re install EasyNAS to get this features.

What’s new in BTRFSv4:

  • bug fixes
  • Better quota management
  • more stability
  • fix filesystem

    and many more.
    many of the BTRFS features will slowly be adopted to EasyNAS