How to mount network FS over rootfs?

Question

linux

There is a router with a small amount of memory and the inability to connect a USB flash drive.
I plan to mount NFS or SSHFS "on top" of rootfs (which is read only), on which all changes will occur. Is it possible to do this?

Answer 1

I don't think this will work: you need to mount the remote filesystem to the root first, and then do something like "mount --rbind /something/", which will break the remote filesystem mount (if it works at all).
And any disconnect will lead to a kernel panic.
I think it's better, easier, safer for you to mount /var and /usr over the network, since only the first should be written to in production mode, and the second is usually the thickest.

Answer 2

Try OverlayFS if available in the kernel.
There is an example here.