I have to join two file systems, one read-only (squashfs) and one read-write (ext4). My plan is to mount the read-write filesystem over the read-only flesystem so it appears writable. When I make some changes on the read-only filesystem, the changes should go to the read-write file system.
I am using Linux 3.17, Ubuntu 14.10, and came across these file systems: aufs, unionfs and overlayfs. I don't know what their differences from each other are and what to use for this situation. Could anybody show me the differences between aufs, unionfs and overlayfs, or just suggest the best one to use with this situation?