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

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 ^^.