[libvirt] [PATCH v2 10/12] getstats: add new flag for block backing chain

[Eric Blake]

On 12/16/2014 08:11 AM, Peter Krempa wrote:
> On 12/16/14 09:04, Eric Blake wrote:
>> This patch introduces access to allocation information about
>> a backing chain of a live domain.  While querying storage
>> volumes for read-only disks could provide some of the details,
>> there is one case where we have to rely on qemu: when doing
>> a block commit into a backing file, where that file is stored
>> in qcow2 format on a host block device, we want to know the
>> current highest write offset into that image, in order to know
>> if the disk must be resized larger.  qemu-img does not
>> (currently) show this information, and none of the earlier
>> block APIs were extensible enough to expose it.  But
>> virDomainListGetStats is perfect for the job!
>>

>>   *                      block device.
>> + * "block.<num>.backingIndex" - unsigned int giving the <backingStore> index,
>> + *                              when backing images are listed.
> 
> You add the field to this help, but ...
> 

>> -I<--block> returns:
>> +I<--block> returns information about disks associated with each
>> +domain.  Using the I<--backing> flag extends this information to
>> +cover all resources in the backing chain, rather than the default
>> +of limiting information to the active layer for each guest disk.
>> +Information listed includes:
>>  "block.count" - number of block devices on this domain,
>>  "block.<num>.name" - name of the target of the block device <num>,
>>  "block.<num>.path" - file source of block device <num>, if it is a
>>
> 
> ... not to the manpage.
> 
> ACK with ^^.

Fixed and pushed.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 539 bytes
Desc: OpenPGP digital signature
URL: <http://listman.redhat.com/archives/libvir-list/attachments/20141217/da31b96a/attachment-0001.sig>