[Libguestfs] external call to v2v (vdsm integration)

Hi, I have several question regarding error handling when we call v2v from vdsm: 1. do you have return code values table? 2. how can vdsm determine if operations success/fail assuming vdsm crushed or the service restarted. 3. what is the best strategy to cancel blocked I/O calls? Thanks, Shahar.