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Date: Thu, 5 Dec 2013 11:33:50 +0100
From: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20131205103350.GD9629@stefanha-thinkpad.redhat.com>
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Subject: Re: [Qemu-devel] [PATCHv3 1.8 7/9] qemu-img: round down request
 length to an aligned sector
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To: Peter Lieven <pl@kamp.de>
Cc: kwolf@redhat.com, Stefan Hajnoczi <stefanha@gmail.com>, qemu-devel@nongnu.org, pbonzini@redhat.com

On Wed, Dec 04, 2013 at 04:56:19PM +0100, Peter Lieven wrote:
> Am 04.12.2013 16:49, schrieb Stefan Hajnoczi:
> > On Wed, Nov 27, 2013 at 11:07:07AM +0100, Peter Lieven wrote:
> >> @@ -1397,19 +1396,21 @@ static int img_convert(int argc, char **argv)
> >>          }
> >>      }
> >>  
> >> +    cluster_sectors = 0;
> >> +    ret = bdrv_get_info(out_bs, &bdi);
> >> +    if (ret < 0 && compress) {
> >> +        error_report("could not get block driver info");
> >> +        goto out;
> >> +    } else {
> >> +        cluster_sectors = bdi.cluster_size / BDRV_SECTOR_SIZE;
> >> +    }
> > Why do we only report error if 'compress' is set?  cluster_sectors must
> > be valid and we cannot guarantee that if bdrv_get_info() failed.
> You mean this should be:
> 
> +    if (ret < 0) {
> +        if (compress) {
> +            error_report("could not get block driver info");
> +            goto out;
> +        }
> +    } else {
> +        cluster_sectors = bdi.cluster_size / BDRV_SECTOR_SIZE;
> +    }
> 
> 
> if cluster_sectors is 0 the alignment logic is skipped, but we cannot
> guarantee that bdi is zero and stays zero if the call fails.
> 
> can you fix that when you pick up the patch?

Sure.

Stefan