Is There a Defragmenter for Ext2fs?

Yes. There is defrag, a Linux file system defragmenter for ext2,
Minix, and old-style ext file systems. It is available at
ftp://metalab.unc.edu/pub/Linux/system/filesystems/defrag-0.70.tar.gz.

Users of the ext2 file system can probably do without defrag, because
ext2 contains extra code to keep fragmentation reduced even in very
full file systems.