Re: [Qemu-block] [Qemu-devel] [PATCH] qemu-img: implement copy offload (-C) for dd

[Eric Blake]

On 2/21/19 11:37 AM, Sergio Lopez wrote:
> This parameter is analogous to convert's "-C", making use of
> bdrv_co_copy_range().

The last time I tried to patch 'qemu-img dd', it was pointed out that it
already has several bugs (where it is not on feature-parity with real
dd), and that we REALLY want to make it a syntactic sugar wrapper around
'qemu-img convert', rather than duplicating code (which means that
qemu-img convert needs to make it easier to do arbitrary offsets and
subsets - although to some extent you can already do that with
--image-opts and appropriate raw driver wrappers).

https://lists.gnu.org/archive/html/qemu-devel/2018-08/msg02618.html

> 
> Signed-off-by: Sergio Lopez <address@hidden>
> ---
>  qemu-img-cmds.hx |   4 +-
>  qemu-img.c       | 146 ++++++++++++++++++++++++++++++++++++-----------
>  qemu-img.texi    |   2 +-
>  3 files changed, 117 insertions(+), 35 deletions(-)

In other words, this feels like a lot of code compared to being able to
just forward on to an appropriate qemu-img convert command, and I think
our time would be better spent on that.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org