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Date: Wed, 13 Nov 2013 15:36:10 +0800
From: Amos Kong <akong@redhat.com>
Message-ID: <20131113073610.GA17674@amosk.info>
References: <1384315458-23417-1-git-send-email-famz@redhat.com>
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In-Reply-To: <1384315458-23417-1-git-send-email-famz@redhat.com>
Subject: Re: [Qemu-devel] [PATCH] qemu-img: Fix content mismatch offset of
 image compare
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To: Fam Zheng <famz@redhat.com>
Cc: kwolf@redhat.com, Miroslav Rezanina <mrezanin@redhat.com>, qemu-devel@nongnu.org, stefanha@redhat.com

On Wed, Nov 13, 2013 at 12:04:18PM +0800, Fam Zheng wrote:
> We were lucky to pass qemu-iotests 048 (qemu-img compare case) but when
> I tried to run with TEST_DIR=/tmp (tmpfs), it fails with a very weird
> mismatch offset. This fixes the bug.
> 
> In the if branch, setting ret to 1 before using it makes dead code in
> the next line: pnum is never added to mismatch offset even if ret was 0.
> 
> Signed-off-by: Fam Zheng <famz@redhat.com>
> ---
>  qemu-img.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/qemu-img.c b/qemu-img.c
> index bf3fb4f..2bab20d 100644
> --- a/qemu-img.c
> +++ b/qemu-img.c
> @@ -1020,10 +1020,10 @@ static int img_compare(int argc, char **argv)
>                  }
>                  ret = compare_sectors(buf1, buf2, nb_sectors, &pnum);
>                  if (ret || pnum != nb_sectors) {
> -                    ret = 1;
>                      qprintf(quiet, "Content mismatch at offset %" PRId64 "!\n",
>                              sectors_to_bytes(
>                                  ret ? sector_num : sector_num + pnum));
> +                    ret = 1;

Looks good

>                      goto out;
>                  }
>              }
> -- 
> 1.8.4.2
> 

-- 
			Amos.