[CentOS] /dev/mapper/cl-root filesystem corrupted?

Mon Dec 7 01:20:23 UTC 2020
Robert G. (Doc) Savage <dsavage at peaknet.net>

A client's (truly ancient) file server running CentOS 7 suddenly
started misbehaving, and I believe the ext4 filesystem on
/dev/mapper/cl-root may be corrupted. A reboot fails with a file system
check and drops me into maintenance mode. I tried booting from a live
C7 DVD and as root running e2fsck. It complains that the superblock
could not be read and suggests running "e2fsck -b 8193 <device>". That
also fails.

Is there a way to more forcefully "encourage" e2fsck to do its job
without totally destroying that filesystem?

--Doc Savage
    Fairview Heights, IL