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

[Alexander Graf]

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().
>   

Or another function call hook to change the backing device state from RO
to RW.

Alex