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Date: Fri, 23 May 2014 14:48:43 +0200
From: Stefan Hajnoczi <stefanha@gmail.com>
Message-ID: <20140523124843.GC5990@stefanha-thinkpad.hitronhub.home>
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In-Reply-To: <1400815403-7719-7-git-send-email-famz@redhat.com>
Subject: Re: [Qemu-devel] [PATCH 6/7] block: Use bdrv_set_backing_hd
 everywhere
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To: Fam Zheng <famz@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>, Benoit Canet <benoit@irqsave.net>, jcody@redhat.com, qemu-devel@nongnu.org, Max Reitz <mreitz@redhat.com>, Stefan Hajnoczi <stefanha@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>

On Fri, May 23, 2014 at 11:23:22AM +0800, Fam Zheng wrote:
> We need to handle the coming backing_blocker properly, so don't open
> code the assignment, instead, call bdrv_set_backing_hd to change
> backing_hd.
> 
> Signed-off-by: Fam Zheng <famz@redhat.com>
> ---
>  block.c        | 4 ++--
>  block/stream.c | 4 ++--
>  block/vvfat.c  | 2 +-
>  3 files changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/block.c b/block.c
> index 911ba68..91c866c 100644
> --- a/block.c
> +++ b/block.c
> @@ -2652,13 +2652,13 @@ int bdrv_drop_intermediate(BlockDriverState *active, BlockDriverState *top,
>      if (ret) {
>          goto exit;
>      }
> -    new_top_bs->backing_hd = base_bs;
> +    bdrv_set_backing_hd(new_top_bs, base_bs);
>  
>      bdrv_refresh_limits(new_top_bs);

Please ignore what I said about backing_hd and base_bs being non-NULL,
it doesn't matter.  bdrv_set_backing_hd() always calls
bdrv_refresh_limits() so we definitely don't need to call it again here.