Re: [Qemu-devel] [PATCH v3 2/8] block: set snapshot option for block devices in blkreplay module

[Paolo Bonzini]

On 20/09/2016 14:31, Pavel Dovgalyuk wrote:
>      /* Open the image file */
>      bs->file = bdrv_open_child(NULL, options, "image",
> @@ -40,6 +112,43 @@ static int blkreplay_open(BlockDriverState *bs, QDict 
> *options, int flags,
>          goto fail;
>      }
>  
> +    opts = qemu_opts_create(&blkreplay_runtime_opts, NULL, 0, &error_abort);
> +    qemu_opts_absorb_qdict(opts, options, &local_err);
> +    if (local_err) {
> +        ret = -EINVAL;
> +        goto fail;
> +    }
> +
> +    /* Prepare options QDict for the overlay file */
> +    qdict_put(snapshot_options, "file.driver",
> +              qstring_from_str("file"));
> +    qdict_put(snapshot_options, "driver",
> +              qstring_from_str("qcow2"));
> +
> +    snapshot = qemu_opt_get(opts, "overlay");
> +    if (snapshot) {
> +        qdict_put(snapshot_options, "file.filename",
> +                  qstring_from_str(snapshot));
> +    } else {
> +        char tmp_filename[PATH_MAX + 1];
> +        ret = get_tmp_filename(tmp_filename, PATH_MAX + 1);
> +        if (ret < 0) {
> +            error_setg_errno(errp, -ret, "Could not get temporary filename");
> +            goto fail;
> +        }

No, this is unnecessary.  The image is unused in this case, so you can
specify the overlay as image=foo.qcow2.


Paolo