Multiple Read-Only Layers Added To OverlayFS
The OverlayFS changes were submitted today for the Linux 3.20 kernel. The changes for the Linux 3.20 merge window add support for handling multiple read-only layers to OverlayFS. The changes also make the writable upper-layer optional.
In total these OverlayFS "ovl" changes make up a few hundred lines of code. More details for OverlayFS users can be found via the pull request.