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

[Stefan Hajnoczi]

On Fri, Apr 25, 2014 at 02:50:29PM +0800, Fam Zheng wrote:
> bdrv_get_info could fail. Add check before using the returned value.
> 
> Signed-off-by: Fam Zheng <address@hidden>
> ---
>  block/mirror.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/block/mirror.c b/block/mirror.c
> index 0ef41f9..fafcc93 100644
> --- a/block/mirror.c
> +++ b/block/mirror.c
> @@ -339,8 +339,8 @@ 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) {
>              s->buf_size = MAX(s->buf_size, bdi.cluster_size);
>              s->cow_bitmap = bitmap_new(length);
>          }

Please explain why it's okay to ignore errors.

Stefan