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Date: Wed, 13 May 2015 19:22:33 +0800
From: Wen Congyang <wency@cn.fujitsu.com>
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Subject: Re: [Qemu-devel] [PATCH v2 10/11] blockdev: Block device IO during
 blockdev-backup transaction
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To: Fam Zheng <famz@redhat.com>, qemu-devel@nongnu.org
Cc: Kevin Wolf <kwolf@redhat.com>, qemu-block@nongnu.org, jcody@redhat.com, armbru@redhat.com, mreitz@redhat.com, Stefan Hajnoczi <stefanha@redhat.com>, pbonzini@redhat.com

On 05/14/2015 01:28 AM, Fam Zheng wrote:
> Signed-off-by: Fam Zheng <famz@redhat.com>
> ---
>  blockdev.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/blockdev.c b/blockdev.c
> index ae52d27..bd28183 100644
> --- a/blockdev.c
> +++ b/blockdev.c
> @@ -1649,6 +1649,7 @@ typedef struct BlockdevBackupState {
>      BlockDriverState *bs;
>      BlockJob *job;
>      AioContext *aio_context;
> +    Error *blocker;
>  } BlockdevBackupState;
>  
>  static void blockdev_backup_prepare(BlkTransactionState *common, Error **errp)
> @@ -1685,6 +1686,10 @@ static void blockdev_backup_prepare(BlkTransactionState *common, Error **errp)
>      }
>      aio_context_acquire(state->aio_context);
>  
> +    state->bs = bs;
> +    error_setg(&state->blocker, "blockdev-backup in progress");
> +    bdrv_op_block(bs, BLOCK_OP_TYPE_DEVICE_IO, state->blocker);
> +

Do you test this patch? You need to read from bs to do backup!!
If the mode is none, you also need to write to bs!!

Thanks
Wen Congyang

>      qmp_blockdev_backup(backup->device, backup->target,
>                          backup->sync,
>                          backup->has_speed, backup->speed,
> @@ -1696,7 +1701,6 @@ static void blockdev_backup_prepare(BlkTransactionState *common, Error **errp)
>          return;
>      }
>  
> -    state->bs = bs;
>      state->job = state->bs->job;
>  }
>  
> @@ -1715,6 +1719,10 @@ static void blockdev_backup_clean(BlkTransactionState *common)
>  {
>      BlockdevBackupState *state = DO_UPCAST(BlockdevBackupState, common, common);
>  
> +    if (state->bs) {
> +        bdrv_op_unblock(state->bs, BLOCK_OP_TYPE_DEVICE_IO, state->blocker);
> +        error_free(state->blocker);
> +    }
>      if (state->aio_context) {
>          aio_context_release(state->aio_context);
>      }
>