Works perfectly now!
I did:
~$ sudo mkfs.ext3 -I 128 -m 0 -L Mandriva /dev/sda3
mke2fs 1.40.8 (13-Mar-2008) Filesystem label=Mandriva OS type: Linux Block size=4096 (log=2) Fragment size=4096 (log=2) 453376 inodes, 1811328 blocks 0 blocks (0.00%) reserved for the super user First data block=0 Maximum filesystem blocks=1858076672 56 block groups 32768 blocks per group, 32768 fragments per group 8096 inodes per group Superblock backups stored on blocks: 32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632
Writing inode tables: done Creating journal (32768 blocks): done Writing superblocks and filesystem accounting information: done
This filesystem will be automatically checked every 33 mounts or 180 days, whichever comes first. Use tune2fs -c or -i to override.
Except when you reinstall Mandriva, after designating the partition mount point as '/', you have to be careful on the next screen ('Choose to format') to NOT format (untick the box)--otherwise it would probably reformat it with default 256 bytes inodes.
So now I can access mandriva with fs-driver fine, and I can boot it with any of the grub formats ('configfile,' 'symlink', direct, as well as chainloader).
Thanks a bunch