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Date: Sun, 12 Jun 2016 10:26:16 +0800
From: Fam Zheng <famz@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH] block-backend: allow flush on devices with
 open tray
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To: John Snow <jsnow@redhat.com>
Cc: qemu-block@nongnu.org, kwolf@redhat.com, qemu-devel@nongnu.org, mreitz@redhat.com

On Fri, 06/10 17:59, John Snow wrote:
> If a device still has an attached BDS because the medium has not yet
> been removed, we will be unable to migrate to a new host because
> blk_flush will return an error for that backend.
> 
> Replace the call to blk_is_available to blk_is_inserted to weaken
> the check and allow flushes from the backend to work, while still
> disallowing flushes from the frontend/device model to work.
> 
> This fixes a regression present in 2.6.0 caused by the following commit:
> fe1a9cbc339bb54d20f1ca4c1e8788d16944d5cf
> block: Move some bdrv_*_all() functions to BB
> 
> Signed-off-by: John Snow <jsnow@redhat.com>
> ---
>  block/block-backend.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/block/block-backend.c b/block/block-backend.c
> index 34500e6..d1e875e 100644
> --- a/block/block-backend.c
> +++ b/block/block-backend.c
> @@ -1122,7 +1122,7 @@ int blk_co_flush(BlockBackend *blk)
>  
>  int blk_flush(BlockBackend *blk)
>  {
> -    if (!blk_is_available(blk)) {
> +    if (!blk_is_inserted(blk)) {
>          return -ENOMEDIUM;
>      }
>  
> -- 
> 2.4.11
> 
> 

Reviewed-by: Fam Zheng <famz@redhat.com>