[Users] vzmigrate issues

[Toby Burress]

When vzmigrate is used to migrate a server with the `--online` option,
the guest's state is dumped, transfered to the destination server,
and resumed.

It looks like vzmigrate is hardcoded to put the dumpfile in /var/tmp,
even when DUMPDIR is defined in /etc/vz/vz.conf.  This leads to a nasty
surprise when /var/tmp isn't all that big and the dump fills the disk.
It looks like this causes the dump process to get stuck in disk wait,
and the jail is inaccessible until the host is rebooted.

Is there a way to have dump estimate the amount of space it will need,
and die if it doesn't have that space?  If I patch vzmigrate to look in
vz.conf for DUMPDIR, should I submit that to this list?

Thanks