On Thu, Apr 09, 2015 at 11:39:28AM +0100, Stefan Hajnoczi wrote: > > The goal would be to convert this: > > > > [A] -> [B] -> [C] -> [D] > > > > into this: > > > > [A] -> [B] -> [X] -> [D] > > > > where [D] is the active image and [X] would be a copy of [C]. The > > latter would be unlinked from the chain. > > > > A use case would be to move disk images across different storage > > backends. > > The simple solution to that problem is: > > Assumption: backing files are read only. (True in most cases.) > > 1. Copy the backing files using cp(1) or another method. > 2. Issue QMP 'change-backing-file' command so that [D] uses [X] instead > of [C]. > > So it can be done today already.
So do you think it would be better to implement this somewhere else? The code that I have for QEMU is quite simple, the actual algorithm doesn't change, it only needs to do the changing of backing files in mirror_exit(). Berto