Re: [Qemu-devel] [PATCH 5/5] mirror: Check for bdrv_get_info result

[Jeff Cody <jcody@redhat.com>]

On Wed, Nov 13, 2013 at 08:53:14AM +0800, Fam Zheng wrote:
> bdrv_get_info could fail. Add check before using the returned value.
> 
> Signed-off-by: Fam Zheng <famz@redhat.com>
> ---
>  block/mirror.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/block/mirror.c b/block/mirror.c
> index 7b95acf..c0c321b 100644
> --- a/block/mirror.c
> +++ b/block/mirror.c
> @@ -320,8 +320,8 @@ static void coroutine_fn mirror_run(void *opaque)
>      bdrv_get_backing_filename(s->target, backing_filename,
>                                sizeof(backing_filename));
>      if (backing_filename[0] && !s->target->backing_hd) {
> -        bdrv_get_info(s->target, &bdi);
> -        if (s->granularity < bdi.cluster_size) {
> +        ret = bdrv_get_info(s->target, &bdi);
> +        if (ret == 0 && s->granularity < bdi.cluster_size) {

For ret < 0, I think we should exit on error (at least in cases where
ret < 0 && ret != -ENOTSUP).

>              s->buf_size = MAX(s->buf_size, bdi.cluster_size);
>              s->cow_bitmap = bitmap_new(length);
>          }