Re: [Qemu-devel] [PATCH v4 7/7] block: Allow backup on referenced named BlockDriverState

[Fam Zheng <famz@redhat.com>]

On 2013年11月25日 19:23, Kevin Wolf wrote:
> Am 22.11.2013 um 06:24 hat Fam Zheng geschrieben:
>> Drive backup is a read only operation on source bs. We want to allow
>> this specific case to enable image-fleecing. Note that when
>> image-fleecing job starts, the job still add its blocker to source bs,
>> and any other operation on it will be blocked by that.
>>
>> Signed-off-by: Fam Zheng <famz@redhat.com>
>> ---
>>   block.c | 2 ++
>>   1 file changed, 2 insertions(+)
>>
>> diff --git a/block.c b/block.c
>> index a5da656..d30be51 100644
>> --- a/block.c
>> +++ b/block.c
>> @@ -1179,6 +1179,8 @@ int bdrv_open(BlockDriverState *bs, const char *filename, QDict *options,
>>                              "device is used as backing hd of '%s'",
>>                              bs->device_name);
>>                   bdrv_op_block_all(bs->backing_hd, bs->backing_blocker);
>> +                bdrv_op_unblock(bs->backing_hd, BLOCK_OP_TYPE_BACKUP,
>> +                                bs->backing_blocker);
>>                   pstrcpy(bs->backing_file, sizeof(bs->backing_file),
>>                           bs->backing_hd->filename);
>>                   pstrcpy(bs->backing_format, sizeof(bs->backing_format),
>
> We probably need separate blockers for "can be a backup source" and "can
> be a backup target". Because I think this allows using it as a
> read-write target as well, which was not intended.
>

Yes. Will do it.

> Do we need to cover this in other parts of the code as well, like when
> adding a new BDS during external snapshot creation?
>

Does it have a name? If not I think we are safe there.

Fam