From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([140.186.70.92]:51438)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <kwolf@redhat.com>) id 1RYbsy-0004Hv-7n
	for qemu-devel@nongnu.org; Thu, 08 Dec 2011 06:11:33 -0500
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <kwolf@redhat.com>) id 1RYbsx-0005Ot-AL
	for qemu-devel@nongnu.org; Thu, 08 Dec 2011 06:11:32 -0500
Received: from mx1.redhat.com ([209.132.183.28]:36618)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <kwolf@redhat.com>) id 1RYbsx-0005Op-0m
	for qemu-devel@nongnu.org; Thu, 08 Dec 2011 06:11:31 -0500
Message-ID: <4EE09C1E.4020305@redhat.com>
Date: Thu, 08 Dec 2011 12:14:38 +0100
From: Kevin Wolf <kwolf@redhat.com>
MIME-Version: 1.0
References: <1323322800-2560-1-git-send-email-zhihuili@linux.vnet.ibm.com>
In-Reply-To: <1323322800-2560-1-git-send-email-zhihuili@linux.vnet.ibm.com>
Content-Type: text/plain; charset=ISO-8859-15
Content-Transfer-Encoding: 7bit
Subject: Re: [Qemu-devel] [PATCH] block/cow : return real error code in cow.c
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Li Zhi Hui <zhihuili@linux.vnet.ibm.com>
Cc: qemu-devel@nongnu.org, stefanha@linux.vnet.ibm.com

Am 08.12.2011 06:40, schrieb Li Zhi Hui:
> Signed-off-by: Li Zhi Hui <zhihuili@linux.vnet.ibm.com>
> ---
>  block/cow.c |   22 ++++++++++++----------
>  1 files changed, 12 insertions(+), 10 deletions(-)
> 
> diff --git a/block/cow.c b/block/cow.c
> index 3c52735..383482b 100644
> --- a/block/cow.c
> +++ b/block/cow.c
> @@ -64,10 +64,11 @@ static int cow_open(BlockDriverState *bs, int flags)
>      struct cow_header_v2 cow_header;
>      int bitmap_size;
>      int64_t size;
> +    int ret;
>  
>      /* see if it is a cow image */
> -    if (bdrv_pread(bs->file, 0, &cow_header, sizeof(cow_header)) !=
> -            sizeof(cow_header)) {
> +    ret = bdrv_pread(bs->file, 0, &cow_header, sizeof(cow_header));
> +    if (ret < 0) {
>          goto fail;
>      }
>  

More context:

    if (be32_to_cpu(cow_header.magic) != COW_MAGIC ||
        be32_to_cpu(cow_header.version) != COW_VERSION) {
        goto fail;
    }

This jumps to fail: with uninitialised ret. Needs to be fixed.

> @@ -88,7 +89,7 @@ static int cow_open(BlockDriverState *bs, int flags)
>      qemu_co_mutex_init(&s->lock);
>      return 0;
>   fail:
> -    return -1;
> +    return ret;
>  }
>  
>  /*
> @@ -182,14 +183,14 @@ static int coroutine_fn cow_read(BlockDriverState *bs, int64_t sector_num,
>              ret = bdrv_pread(bs->file,
>                          s->cow_sectors_offset + sector_num * 512,
>                          buf, n * 512);
> -            if (ret != n * 512)
> -                return -1;
> +            if (ret < 0)
> +                return ret;

Please add braces here while touching the code.

>          } else {
>              if (bs->backing_hd) {
>                  /* read from the base image */
>                  ret = bdrv_read(bs->backing_hd, sector_num, buf, n);
>                  if (ret < 0)
> -                    return -1;
> +                    return ret;

And here.

Otherwise the patch looks good to me.

Kevin