qemu: snapshot: Forbid snapshots when backing is a scsi passthrough disk
qemu: snapshot: Forbid snapshots when backing is a scsi passthrough disk

https://bugzilla.redhat.com/show_bug.cgi?id=1034993

SCSI passthrough disks (<disk .. device="lun">) can't be used as backing
for snapshots. Currently with upstream qemu the vm crashes on such
attempt.

This patch adds a early check to catch an attempt to do such a snapshot
and rejects it right away. qemu will fix the issue but this will let us
control the error message.

datto/libvirt,elmarco/libvirt,taget/libvirt,rlaager/libvirt,crobinso/libvirt,zippy2/libvirt,eskultety/libvirt,eskultety/libvirt,jfehlig/libvirt,taget/libvirt,nertpinx/libvirt,datto/libvirt,jfehlig/libvirt,jardasgit/libvirt,VenkatDatta/libvirt,datto/libvirt,jfehlig/libvirt,elmarco/libvirt,VenkatDatta/libvirt,eskultety/libvirt,shugaoye/libvirt,fabianfreyer/libvirt,shugaoye/libvirt,olafhering/libvirt,andreabolognani/libvirt,rlaager/libvirt,nertpinx/libvirt,crobinso/libvirt,agx/libvirt,fabianfreyer/libvirt,jardasgit/libvirt,elmarco/libvirt,jardasgit/libvirt,nertpinx/libvirt,eskultety/libvirt,shugaoye/libvirt,andreabolognani/libvirt,agx/libvirt,agx/libvirt,fabianfreyer/libvirt,shugaoye/libvirt,jardasgit/libvirt,libvirt/libvirt,agx/libvirt,shugaoye/libvirt,taget/libvirt,zippy2/libvirt,crobinso/libvirt,VenkatDatta/libvirt,zippy2/libvirt,jfehlig/libvirt,rlaager/libvirt,olafhering/libvirt,VenkatDatta/libvirt,crobinso/libvirt,nertpinx/libvirt,agx/libvirt,libvirt/libvirt,taget/libvirt,andreabolognani/libvirt,libvirt/libvirt,eskultety/libvirt,olafhering/libvirt,datto/libvirt,rlaager/libvirt,elmarco/libvirt,rlaager/libvirt,VenkatDatta/libvirt,olafhering/libvirt,datto/libvirt,andreabolognani/libvirt,taget/libvirt,nertpinx/libvirt,fabianfreyer/libvirt,zippy2/libvirt,fabianfreyer/libvirt,libvirt/libvirt,elmarco/libvirt,jardasgit/libvirt,andreabolognani/libvirt