なんか動きがおかしいと思ったらroになっとる……
再起動するの怖いけど再起動するしか無さそう

$ mount | grep ' / '
/dev/mapper/t430s--vg-root on / type ext4 (ro,noatime,nodiratime,quota,usrquota,grpquota,errors=remount-ro)
$ sudo mount -oremount,rw /
mount: /: cannot remount /dev/mapper/t430s--vg-root read-write, is write-protected.