Introduce dry run option for attaching the device. This will allow us to verify if passphrase and key is valid without decrypting whole device. Reviewed by: cem@, allanjude@ Differential Revision: https://reviews.freebsd.org/D15000
head/sbin/geom/class/eli/geli.8
head/sbin/geom/class/eli/geom_eli.c
head/sys/geom/eli/g_eli_ctl.c