On Sat, 2022-09-03 at 21:06 -0400, Nicholas D Steeves wrote: > First, the automated case: Currently DI statically sets the rootfs to be > "subvolume=@rootfs", which is a value unique to Debian. The simple > thing to do is to detect that a device has been formatted to btrfs > before mounting, and then try to mount "-o subvol=@rootfs" as Ansgar > suggested. One step more flexible is to have a Rescue policy of > something like only supporting read-write subvolumes with a name that > matches '.*\@rootfs.*', and that exist in the / of the volume. Ie: > maxdepth=1.
Why not set the default subvolume to @rootfs then? (What `btrfs subvolume set-default` does.) That would also be useful for use with `systemd-gpt-auto-generator`. It would not help with existing systems using @rootfs, but be compatible with installations not using that. > awk '{print $1}' < /MOUNTPOINT/etc/issue > or perhaps > grep 'ID\=debian' < /etc/os-release It should also test for `/usr/lib/os-release` in case the symlink in `/etc/` is not present. Ansgar