News Report: Introducing COMPOSEFS File System Version 1.0
Alexander Larsson, creator of Flatpak and a member of Red Hat, has announced the release of the first stable production version of the COMPOSEFS file system. This file system is specifically optimized for effectively storing the contents of multiple targeted disk images. The FS Composefs can be particularly useful for mounting container images and managing the Git-like Ostree repository. The project code is written in SI and is distributed under the GPLV2 license. For more information, visit the official blog post.
In the initial stages of development, Composefs was a separate Linux kernel module. However, the developers recognized the challenges of integrating the new file system into the main kernel composition. Consequently, they changed their approach and redesigned the project in the form of the FS Overlayfs and Erofs, which partially intersect with Composefs. This strategy allowed them to focus on advancing Overlayfs and Erofs patches that are essential for Composefs’ specific features. Further information about the project’s distribution can be found on GitHub.
Specifically, EROFS (EXTENDABLE READ-OLY FILE SYSTEM) functionality has been meeting the requirements of Composefs since version 5.15. In the case of Overlayfs, the changes have been implemented in multiple stages. For example, in kernel version 6.5, support for the “Data-One” layers, used exclusively for data storage separate from metadata, was included. Additionally, acceptance of changes related to preserving Hashi fs-verity in an extended attribute (xattr) Overlay.verity has recently been acknowledged in the test release of the 6.6-RC1 kernel. These changes signify the inclusion of all the necessary features in the main composition of the Linux kernel to ensure the proper functioning of Composefs. Further details about the changes can be found on the