from here

Boot from repair disk

On prompt, skip to shell

vgscan -v --mknodes  (double lines at the end)

This will find and create /dev/xxx/ nodes for the lvm. But it is not mounted so it’s good.

Now activate the volumes, it still does not actually mount them, so still good.

vgchange -a y

Now see what volumes are active with another lvscan

lvscan

I have /dev/centos/root which is what I need to fix. It is an XFS volume so this time I do

xfs_repair /dev/centos/root

Reboot