Re: [Qemu-block] [PATCH v8 12/36] virtio-blk: Apply lock-mode when realize

[Max Reitz]

On 30.09.2016 14:09, Fam Zheng wrote:
> Signed-off-by: Fam Zheng <address@hidden>
> ---
>  hw/block/virtio-blk.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
> index 3a6112f..ce65615 100644
> --- a/hw/block/virtio-blk.c
> +++ b/hw/block/virtio-blk.c
> @@ -896,6 +896,11 @@ static void virtio_blk_device_realize(DeviceState *dev, 
> Error **errp)
>          error_setg(errp, "num-queues property must be larger than 0");
>          return;
>      }
> +    blk_lock_image(conf->conf.blk, conf->conf.lock_mode, &err);
> +    if (err) {
> +        error_propagate(errp, err);
> +        return;
> +    }
>  
>      blkconf_serial(&conf->conf, &conf->serial);
>      blkconf_apply_backend_options(&conf->conf);
> 

Hmmm... Patch 3 introduced the conf.lock_mode field, but didn't do
anything with it. That is a bit weird. Now you're applying it here but
can't set it anywhere. That's a bit weird, too. Well, behavior won't
change as this probably just means that now everything explicitly
unlocked instead of implicitly "because we don't have locking yet".

Maybe it would make sense to move the introduction of conf.lock_mode to
an own patch and explain in the commit message that this field will be
implicitly set to 0, so until the user is able to control the field,
every BB (and thus BDS tree) will not be locked (thus not changing
behavior).

Max

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