On Mon, Jun 10, 2019 at 08:29:26PM -0700, Darrick J. Wong wrote: > ...and administrators often mkfs over mounted filesystems because we let > them read and write block devices. Granted I tried to fix that once and > LVM totally stopped working... That must have been a long time ago. We now overload O_EXCL on blockdevice to only allow a single exclusive openers, and mounted filesystems as well as raid drivers have been setting set for at leat 10 years.