wait, is ext4 really that large of a filesystem? df -m tells me my root partition is ~6900 mb, but gparted can't resize it below 8048 mb.
maybe i should switch to a different fs...
@flussence yeah, seems like that's the issue. i've backed up all the data onto a btrfs partition, and the overhead is way lower.
in fact, i just did a full backup and reformat, so my root partition is now btrfs.