I wrote a filesystem that could be mounted in any machine compatible with the Filesystem in Userspace (FUSE) module (Linux, FreeBSD, OpenBSD, NetBSD, OpenSolaris, Minix 3, Android and macOS). I tested it on CentOS. The filesystem is structured like the extended file system (ext). The main benefit of this filesystem is its simplicity relative to other filesystem implementations.
If you'd like to see the code, please feel free to email me.