Re: [Qemu-devel] [PATCH] block: do not probe zero-sized disks

[Stefan Hajnoczi <stefanha@gmail.com>]

On Thu, Jan 10, 2013 at 03:39:27PM +0100, Paolo Bonzini wrote:
> A blank CD or DVD is visible as a zero-sized disks.  Probing such
> disks will lead to an EIO and a failure to start the VM.  Treating
> them as raw is a better solution.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  block.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/block.c b/block.c
> index c05875f..b9da10e 100644
> --- a/block.c
> +++ b/block.c
> @@ -532,7 +532,7 @@ static int find_image_format(const char *filename, BlockDriver **pdrv)
>      }
>  
>      /* Return the raw BlockDriver * to scsi-generic devices or empty drives */
> -    if (bs->sg || !bdrv_is_inserted(bs)) {
> +    if (bs->sg || !bdrv_is_inserted(bs) || bdrv_getlength(bs) == 0) {

Looks good but I wouldn't understand the reason for the zero size check
when reading the code.  Please add a comment so no one changes/removes
this code in the future.

Stefan