Comment 24 for bug 1890803

@xnox,
Your attached patch, which says simply to not error if no fstab file
exists will ultimately hide further errors.

I suspect there are (at least) 3 scenarios:
a.) /etc/fstab exists. happy. this works fine.

b.) /etc/fstab does not exist, there is only one system mount, which can
be read from root= kernel command line. your patch makes this case work
fine.

c.) systemd .mount entries (or some other mechanism) are used.
Your patch turns a warning message from overlayroot into a silent failure.

Additionally, I'm not sure how your patch would work. I think the problem
is that root is not getting re-mounted RW. That is typically done
by systemd, and I thought fstab played a role in conveying that intent to
systemd.

Somehow overlayroot has to convey to systemd that / needs to be mounted
read-write. And also... with 'recurse' functionality, any system mounts
other than / need to be updated. For the 'c' case above, overlayroot
would need new function to do that.