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Re: [PATCH v3 2/6] nbd: Add 'qemu-nbd -A' to expose allocation depth
From: |
Eric Blake |
Subject: |
Re: [PATCH v3 2/6] nbd: Add 'qemu-nbd -A' to expose allocation depth |
Date: |
Fri, 9 Oct 2020 07:13:11 -0500 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 |
On 10/9/20 4:03 AM, Richard W.M. Jones wrote:
>>> +++ b/qapi/block-core.json
>>> @@ -3882,9 +3882,12 @@
>>> #
>>> # @tls-creds: TLS credentials ID
>>> #
>>> -# @x-dirty-bitmap: A "qemu:dirty-bitmap:NAME" string to query in place of
>>> +# @x-dirty-bitmap: A metacontext name such as "qemu:dirty-bitmap:NAME" or
>>
>> What is a "metacontext"?
>>
>> Aside: nbd.h spells it "meta context". The two spellings suggest
>> different meanings to me. Using meta- as a prefix modifies the prefixed
>> word, as in metadata (data that provides information about other data).
>> Separated by space, meta becomes a noun. None of its common meanings
>> seem to apply here. Recommend to pick an appropriate one of
>> "metacontext", "meta-context", "meta context", and stick to it.
>
> In the NBD protocol it's called a "metadata context". This is
> abbreviated to "...META_CONTEXT" in the names of constants,
> eg. NBD_OPT_SET_META_CONTEXT. For the reasons you gave I don't think
> it's a very good name, but it's what we have.
>
> https://github.com/NetworkBlockDevice/nbd/blob/master/doc/proto.md#metadata-querying
>
> What it actually is, is a string, like "base:allocation" or
> "qemu:dirty-bitmap:<NAME>" which selects which metadata you want to
> query in NBD_CMD_BLOCK_STATUS commands.
Sounds like documenting it as a "metadata context name" is probably the
one to use then. I'll make that adjustment.
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
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- [PATCH v3 0/6] Exposing backing-chain allocation over NBD, Eric Blake, 2020/10/08
- [PATCH v3 1/6] nbd: Add new qemu:allocation-depth metacontext, Eric Blake, 2020/10/08
- [PATCH v3 3/6] nbd: Update qapi to support multiple bitmaps, Eric Blake, 2020/10/08
- [PATCH v3 4/6] nbd: Simplify qemu bitmap context name, Eric Blake, 2020/10/08
- [PATCH v3 5/6] nbd: Refactor counting of meta contexts, Eric Blake, 2020/10/08
- [PATCH v3 6/6] nbd: Allow export of multiple bitmaps for one device, Eric Blake, 2020/10/08
- [PATCH v3 2/6] nbd: Add 'qemu-nbd -A' to expose allocation depth, Eric Blake, 2020/10/08