Re: [Qemu-devel] Re: [PATCH] block: Enable fall-back to read-only for backing file

[Jamie Lokier]

Christoph Hellwig wrote:
> On Mon, Feb 01, 2010 at 10:25:52AM +0100, Alexander Graf wrote:
> > We don't know beforehand if a user will use the commit comnand during  
> > tje runtime of the vm.
> > 
> > IMHO it'd be best to always open backing files read only and try to  
> > open them for write access on the commit command. That command can  
> > then fail gaciously.
> 
> That's another option.  Basically this means opening another
> BlockDriverState for the backing device that is writeable inside
> bdrv_commit().

I'd prefer that.  I like having higher confidence that random bugs in
Qemu are unlikely to accidentally modify precious backing files,
except when I've issued an explicit commit command.

-- Jamie