Ext4 filesystem development plan has been made public. A team of engineers from Red Hat, ClusterFS, IBM, and Bull want to extend the Ext3 filesystem. They have proposed a series of patches on the Linux kernel mailing list, to add support for very large filesystems, and after a long discussion they decided to roll these changes into a new version called Ext4.
"Given the recent discussion on LKML two weeks ago, it is clear that many people feel they have a stake in the future development plans of the ext2/ext3 filesystem, as it one of the most popular and commonly used filesystems, particular amongst the kernel development community. For
this reason, the stakes are higher than it would be for other filesystems."
To address these issues, the ext2/3 developers would like to propose the following path forward:
- They want to create a new filesystem codebase in the 2.6 kernel tree in /usr/src/linux/fs/ext4 that will initially register itself as the "ext3dev" filesystem.
- The bug fixes to fix 32-bit cleanliness issues, security/oops problems will go into fs/ext3, but all new development work will go into fs/ext4.
- The ext4 code base will continue to mount older ext3 filesystems, as this is necessary to ensure a future smooth upgrade path from ext3 to ext4 users.
- At some point, probably in 6-9 months, when they are satisfied with the set of features that have been added to fs/ext4, and confident that the filesystem format has stabilized, they will submit a patch which causes the fs/ext4 code to register itself as the ext4 filesystem.
"The implementation may still require some shakedown before we are all confident that it is as stable as ext3 is today. At that point, perhaps 12-18 months out, we may request that the code in fs/ext3/*.c be deleted and that fs/ext4 register itself as supporting the ext3 filesystem as well."