GHacks.net posted a tutorial about converting ext2/3 partitions to ext4
Let’s say you’re a little bit behind the times. You’ve wanted to do some upgrading of your Linux machines but you’ve just not really had the time. Or let’s say you did do some upgrading of your Linux system but you didn’t make any changes to your file system and you’re still running a machine with either ext2 or ext3. Now that’s not necessarily a bad thing as both file systems work and work well. But let’s say you do want to take advantage of some of the features of ext4.Convert ext2/3 to ext4
In this article I am going to show you how to migrate your ext2 or ext3 partition to ext4. I will use a Ubuntu machine as an example. I want to warn you that you could lose data by doing this so, following good administrative practices, back up your data! Once you are certain you have that backup of your data, it’s time to begin.