If no drive=... option is passed (for an empty drive), we don't only
lack the BlockBackend normally created by parse_drive(), but we also
need to manually call blk_attach_dev().
This fixes at least a segfault when unplugging such devices, the bug
that they didn't show up in query-block, and probably some more
problems.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
83b4fe0ed5