I want to implement a qemu block driver which like qeme/block/iscsi.c.

Here are my questions:

    some targets have be attached to guest system, and then the targets info

have changed. How can I update the connection to targets online? I mean 

the disk in guest system does not change, just update the connection to the 

back-end storage, and the operation can't affect guest system. I can't find a 

nova-api or libvirt-api to meet my needs now.