Undocumented zfs command

In the process of tracking down a ZFS mount problem (btw, a zpool will not mount automatically if the mount point exists), I realized that my ZFS swap volume was not available to FreeBSD. After some poking around, I found the /etc/rc.d/zvol script, which led me to the 'zfs volinit' command. This command is not documented in the man page or command usage, but it seems to be the goo that gets volumes going. Also, set the org.freebsd:swap=on property on your swap volume, to have it started automatically by the rc scripts.