[MTD/flash] Why or when df does not show a line for rootfs?

Hello

On my freshly installed Archer C7, I have

# df Filesystem 1K-blocks Used Available Use% Mounted on /dev/root 3584 3584 0 100% /rom tmpfs 62616 72 62544 0% /tmp /dev/mtdblock3 11328 1556 9772 14% /overlay overlayfs:/overlay 11328 1556 9772 14% / tmpfs 512 0 512 0% /dev

On the extroot instructions, and everywhere else, there is a line with rootfs that is mounted at /. I am having all kinds of trouble with setting up extroot, that may be due to my choice of using JFFS2, but I'd like to eliminate this possibility anyway. Am I missing something, and in case I am, how do I fix it?