Re: [Qemu-devel] [PATCH v2 5/6] qmp: Add blockdev-mirror command

[Max Reitz <mreitz@redhat.com>]

On 25.06.2015 05:22, Fam Zheng wrote:
> This will start a mirror job from a named device to another named
> device, its relation with drive-mirror is similar with blockdev-backup
> to drive-backup.
>
> In blockdev-mirror, the target node should be prepared by blockdev-add,
> which will be responsible for assigning a name to the new node, so
> 'node-name' in drive-mirror is dropped.
>
> Signed-off-by: Fam Zheng <famz@redhat.com>
> ---
>   blockdev.c           | 61 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>   qapi/block-core.json | 47 ++++++++++++++++++++++++++++++++++++++++
>   qmp-commands.hx      | 48 +++++++++++++++++++++++++++++++++++++++++
>   3 files changed, 156 insertions(+)
>
> diff --git a/blockdev.c b/blockdev.c
> index de6383f..e0dba07 100644
> --- a/blockdev.c
> +++ b/blockdev.c
> @@ -2932,6 +2932,10 @@ static void blockdev_mirror_common(BlockDriverState *bs,
>       if (bdrv_op_is_blocked(target, BLOCK_OP_TYPE_MIRROR_TARGET, errp)) {
>           return;
>       }
> +    if (target->blk) {
> +        error_setg(errp, "Cannot mirror to an attached block device");
> +        return;
> +    }

1) Why?

2) I think this should be noted in the QMP interface documentation. "the 
name of the device to mirror to" sounds like it is actually meant to be 
an attached block device.

Max