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Date: Wed, 1 Aug 2012 16:31:34 +0100
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From: Stefan Hajnoczi <stefanha@gmail.com>
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Subject: Re: [Qemu-devel] [PATCH 3/6] add-cow file format
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To: Dong Xu Wang <wdongxu@linux.vnet.ibm.com>
Cc: kwolf@redhat.com, qemu-devel@nongnu.org

On Tue, Jul 31, 2012 at 5:51 PM, Dong Xu Wang
<wdongxu@linux.vnet.ibm.com> wrote:
> +    if (backing_filename) {
> +        header.features |= ADD_COW_F_BACKING_FILE;
> +        header.backing_filename_offset = sizeof(header) + 16 * 2;

It's not obvious what 16 * 2 is.

> +    ret = bdrv_pwrite(bs, sizeof(le_header) + 16,
> +        image_format ? image_format : "raw",
> +        image_format ? sizeof(image_format) : sizeof("raw"));

sizeof(image_format)?  I think this should be strlen(image_format).

Stefan