HAMMER2 - mounting root from dm_crypt

[Daniel Bilik]

Hi.

After getting enough courage from responses on this mailing list [1], I've
decided to migrate my system to hammer2 on dm_target_crypt(4)ed volume.

Basically, I've been following "Manual Crypto Installation" guide [2],
just making newfs_hammer2 instead of newfs_hammer. But there was a problem
when mounting the filesystem. Instead of...

mount /dev/mapper/root /mnt

... which gave me "Invalid argument" error, I had to...

mount /dev/mapper/root at ROOT /mnt

Then I've placed the system there, modified loader.conf(5) to include...

vfs.root.realroot="crypt:hammer2:/dev/serno/<serial-of-disk>.s1d:root"

... and rebooted the machine, but initrd failed to mount rootfs. Looking at
the content of initrd, I've found out that /etc/rcmount_crypt is trying to
do the right thing (ie. to mount hammer2 rootfs) but the same wrong way
(ie. with missing "@ROOT" suffix). So I've modified the script (see
attachment) and regenerated initrd. The system is now booting fine,
properly mounting hammer2 rootfs from a crypted partition.

The question is... Does hammer2 really require "@" suffix to be mounted,
even for the root of the filesystem? Or have I created my hammer2
filesystem some wrong way? If it's by design and "@" is required,
then /etc/rcmount_crypt from initrd is probably missing that bit... Is
my modification of the script sufficiently generic to be pushed to master?

Thank you.

--
						Daniel

[1] http://lists.dragonflybsd.org/pipermail/users/2018-December/358019.html
[2] http://www.dragonflybsd.org/docs/handbook/Installation/#index5h1
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