[libvirt] storage conf: Add key-value options to storage pools

[Michael Chapman]

On Tue, 3 Jun 2014, Ján Tomko wrote:
> On 05/28/2014 11:38 AM, Wido den Hollander wrote:
>> This series of patches adds the ability to pass down options to the
>> storage pool drivers.
>>
>> In the case of NFS users can specify mount options and in the case of
>> RBD users can specify options for librados to influence some behavior.
>>
>> All options and values are checked on input validity to prevent injection
>> of malicious commands.
>>
>
> Should we allow arbitrary options?

Ceph in particular has a tendency to add new options with each release, 
and I'm not really sure that it's feasible for libvirt to know about all 
of these options natively.

For instance, I've been running libvirt with a local patch that let's me 
attach arbitrary options to RBD disks. This lets me configure things like 
"rbd cache size" and "rbd cache writethrough until flush" on a per-disk 
basis. Previous discussion on this list has indicated that some people 
would find Ceph's debugging options useful as well.

- Michael