I’m on a MacBookPro and simple did an SSH into 192.168.8.1 (default) with root and here’s the output from “df -h”:

root@GL-AR300M:~# df -h
Filesystem Size Used Available Use% Mounted on
rootfs 102.3M 104.0K 97.4M 0% /
/dev/root 6.5M 6.5M 0 100% /rom
tmpfs 61.4M 988.0K 60.4M 2% /tmp
/dev/ubi0_1 102.3M 104.0K 97.4M 0% /overlay
overlayfs:/overlay 102.3M 104.0K 97.4M 0% /
tmpfs 512.0K 0 512.0K 0% /dev