Re: [Qemu-devel] [PATCH v2 10/11] blockdev: Block device IO during blockdev-backup transaction

[Wen Congyang <wency@cn.fujitsu.com>]

On 05/13/2015 08:55 PM, Fam Zheng wrote:
> On Wed, 05/13 19:22, Wen Congyang wrote:
>> 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!!
> 
> This blocker is only temporary and is removed in blockdev_backup_clean before
> qmp_transaction returns.

Yes. Another question:
We will use bdrv_op_block_all() in the job, and don't unblock BLOCK_OP_TYPE_DEVICE_IO.
Is it OK?

Thanks
Wen Congyang

> 
> Fam
> 
>>
>> 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);
>>>      }
>>>
>>
> .
>