Re: [Qemu-devel] [PATCH] qemu-img: return allocated size for block device with qcow2 format

[Eric Blake <eblake@redhat.com>]

On 05/02/2018 08:34 AM, Ivan Ren wrote:
> qemu-img info with a block device which has a qcow2 format always
> return 0 for disk size, and this can not reflect the qcow2 size
> and the used space of the block device. This patch return the
> allocated size of qcow2 as the disk size.

How does this differ from what qemu can already give you at runtime via 
the wr_highest_offset property in BlockDeviceStats, and related to the 
write_threshold ('block-set-write-threshold command, 
BLOCK_WRITE_THRESHOLD event)?  Is there any code we can reuse, rather 
than writing something from scratch?

> 
> Signed-off-by: Ivan Ren <ivanren@tencent.com>
> ---
>   block/qcow2-bitmap.c |  69 +++++++++++++++++
>   block/qcow2.c        | 212 +++++++++++++++++++++++++++++++++++++++++++++++++++
>   block/qcow2.h        |  42 ++++++++++
>   3 files changed, 323 insertions(+)
> 

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org