Re: [Qemu-devel] [Qemu-block] [PATCH v5 6/6] docs/interop: add nbd.txt

[John Snow]

On 06/20/2018 10:16 AM, Vladimir Sementsov-Ogievskiy wrote:
> 20.06.2018 14:33, Eric Blake wrote:
>> On 06/09/2018 10:17 AM, Vladimir Sementsov-Ogievskiy wrote:
>>> Describe new metadata namespace: "qemu".
>>>
>>> Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
>>> ---
>>>   docs/interop/nbd.txt | 37 +++++++++++++++++++++++++++++++++++++
>>>   MAINTAINERS          |  1 +
>>>   2 files changed, 38 insertions(+)
>>>   create mode 100644 docs/interop/nbd.txt
>>>
>>> diff --git a/docs/interop/nbd.txt b/docs/interop/nbd.txt
>>> new file mode 100644
>>> index 0000000000..7366269fc0
>>> --- /dev/null
>>> +++ b/docs/interop/nbd.txt
>>> @@ -0,0 +1,37 @@
>>> +Qemu supports NBD protocol, and has internal NBD client (look at
>>
>> s/supports/supports the/
>>
>>> +block/nbd.c), internal NBD server (look at blockdev-nbd.c) as well as
>>
>> s/internal/an internal/2
>>
>>> +external NBD server tool - qemu-nbd.c. The common code is placed in
>>
>> s/external/an external/
>>
>>> +nbd/*.
>>> +
>>> +NBD protocol is specified here:
>>
>> s/NBD/The NBD/
>>
>>> +https://github.com/NetworkBlockDevice/nbd/blob/master/doc/proto.md
>>> +
>>> +This following paragraphs describe some specific properties of NBD
>>> +protocol realization in Qemu.
>>> +
>>> +
>>> += Metadata namespaces =
>>> +
>>> +Qemu supports "base:allocation" metadata context as defined in the NBD
>>
>> s/supports/supports the/
>>
>>> +protocol specification and defines own metadata namespace: "qemu".
>>
>> s/own/an additional/
>>
>>> +
>>> +
>>> +== "qemu" namespace ==
>>> +
>>> +For now, the only type of metadata context in the namespace is dirty
>>> +bitmap. All available metadata contexts have the following form:
>>
>> maybe:
>>
>> The "qemu" namespace currently contains only one type of context,
>> related to exposing the contents of a dirty bitmap alongside the
>> associated disk contents.  The available metadata context has the
>> following form:
> 
> Ok
> 
>>
>>> +
>>> +   qemu:dirty-bitmap:<dirty-bitmap-export-name>
>>> +
>>> +Each dirty-bitmap metadata context defines the only one flag for
>>> +extents in reply for NBD_CMD_BLOCK_STATUS:
>>> +
>>> +    bit 0: NBD_STATE_DIRTY, means that the extent is "dirty"
>>> +
>>> +For NBD_OPT_LIST_META_CONTEXT the following queries are supported
>>> +additionally to "qemu:dirty-bitmap:<dirty-bitmap-export-name>":
>>
>> s/additionally/in addition/
>>
>>> +
>>> +* "qemu:" : returns list of all available metadata contexts in the
>>> +            namespace.
>>> +* "qemu:dirty-bitmap:" : returns list of all available dirty-bitmap
>>> +                         metadata contexts.
>>> diff --git a/MAINTAINERS b/MAINTAINERS
>>> index e187b1f18f..887b479440 100644
>>> --- a/MAINTAINERS
>>> +++ b/MAINTAINERS
>>> @@ -1923,6 +1923,7 @@ F: nbd/
>>>   F: include/block/nbd*
>>>   F: qemu-nbd.*
>>>   F: blockdev-nbd.c
>>> +F: docs/interop/nbd.txt
>>>   T: git git://repo.or.cz/qemu/ericb.git nbd
>>>     NFS
>>>
>>
>> Reviewed-by: Eric Blake <address@hidden>
>>
>> At this point, I think I'll touch up the issues I've spotted and
>> submit a pull request, in order to make it easier for me to test my
>> libvirt code.
>>
> 
> Ok, thank you!
> 

ACK; the x- prefixes will help us get everything rolling together much
faster and gives us some leeway to change things later as needed.

Vladimir, can you jog our memories and let us know which series still
need to hit QEMU for 3.0 for safe persistence/migration et al?

(Not including any of my own qemu-img patches which I'll get to by freeze.)