GL iNet GL AR300M

https://openwrt.org/toh/gl.inet/gl-ar300m

Without a USB Flash drive;

/dev/mtdblock4: /rom (squashfs, Boot Image)

/dev/mtdblock5 /overlay (where all the read / write stuff is stored)

...to mount the above /dev/mtdblock5 (in the instance of changing from a USB Flash Drive designated as /overlay) and access FSTAB

mkdir /tmp/mtd5

mount -t jffs2 /dev/mtdblock5 /tmp/mtd5

nano /tmp/mtd5/upper/etc/config/fstab

Why do that?

Disk (USB Flash Drive) Maintenance silly! Especially if the router is in a location where one can't easily pull out the external USB Flash Drive.

fsck.ext4 /dev/WhatEverSDAx

Emergency Situation

If booted to an external USB Flash Drive that has issues, base commands are available in /rom/bin (where /rom is a directory in MTDBLOCK4).