Re: [Qemu-devel] [PATCH V6 8/8] block: Use graph node name as reference in bdrv_file_open().

[Max Reitz <mreitz@redhat.com>]

On 27.01.2014 15:36, Benoît Canet wrote:
> Le Friday 24 Jan 2014 à 15:54:39 (+0100), Max Reitz a écrit :
>> On 24.01.2014 15:48, Kevin Wolf wrote:
>>> Am 24.01.2014 um 14:37 hat Max Reitz geschrieben:
>>>> On 24.01.2014 14:26, Kevin Wolf wrote:
>>>>> Am 23.01.2014 um 21:31 hat Benoît Canet geschrieben:
>>>>>> Signed-off-by: Benoit Canet <benoit@irqsave.net>
>>>>>> ---
>>>>>>   block.c | 6 +++---
>>>>>>   1 file changed, 3 insertions(+), 3 deletions(-)
>>>>> I'm not going to merge this one yet. It breaks qemu-iotests case 071,
>>>>> which would have to be adapted.
>>>>>
>>>>> However, first of all I'd like to hear the opinions of at least Eric and
>>>>> Max on what BlockRef should really refer to. I think node names make
>>>>> most sense, but perhaps it's a bit inconvenient and the command line
>>>>> should default to node-name = id when id is set, but node-name isn't?
>>>> The QAPI schema is pretty clear about this: “references the ID of an
>>>> existing block device.”
>>> Sure, that's because I wrote that text before we had a node name.
>>>
>>> However, in 1.7 references didn't work yet, so we still have all freedom
>>> to change the interface as we like.
>> Yes, that's right.
>>
>>>> However, if the ID cannot be found, I think
>>>> we should interpret it as a reference to the node name.
>>>>
>>>> Therefore, I'd first try bdrv_find() and if that returns NULL, try
>>>> again with bdrv_find_node().
>>> I think I would prefer to avoid such ambiguities. Otherwise a management
>>> tool that wants to use the node name needs to check first if it's not
>>> already used as a device name somewhere else and would therefore operate
>>> on the wrong device.
>>>
>>> On the other hand, a management tool using the same names for devices
>>> and nodes just gets what it deserves.
>>>
>>> Perhaps we should use a common namespace for both, i.e. you get an error
>>> if you try to assign a node name that is already a device name and vice
>>> versa?
>> This is what I would go for. However, then I don't really know why
>> we should separate the ID and the node name in the first place
>> (although that's probably because I haven't followed the discussion
>> around node names).
>>
>> Max
> Ping,
>
> I still want to make quorum merge.
> What should be done for the references ?
>
> Best regards
>
> Benoît

My only problem is that I don't really know what IDs are for, then. ;-)

Currently, I think using the node name is probably (more) correct and it 
can't hurt anyone; thus, I'm okay with this patch.

Max