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Re: [Qemu-devel] [PATCH v5 23/42] blockdev: Use CAF in external_snapshot
From: |
Vladimir Sementsov-Ogievskiy |
Subject: |
Re: [Qemu-devel] [PATCH v5 23/42] blockdev: Use CAF in external_snapshot_prepare() |
Date: |
Fri, 14 Jun 2019 16:58:13 +0000 |
14.06.2019 19:20, Max Reitz wrote:
> On 14.06.19 17:46, Vladimir Sementsov-Ogievskiy wrote:
>> 13.06.2019 1:09, Max Reitz wrote:
>>> This allows us to differentiate between filters and nodes with COW
>>> backing files: Filters cannot be used as overlays at all (for this
>>> function).
>>>
>>> Signed-off-by: Max Reitz <address@hidden>
>>
>> Overlay created in snapshot operation assumed to consume following writes
>> and it's filtered child becomes readonly.. And filter works in completely
>> another
>> way.
>>
>> Reviewed-by: Vladimir Sementsov-Ogievskiy <address@hidden>
>>
>> [hmm, I start to like using "filtered child" collocation when I say about
>> this thing.
>> didn't you think about renaming backing chain to filtered chain?]
>
> Hm. There are backing chains and there are backing chains. There are
> qemu-internal backing chains that consist of a healthy mix of filters
> and COW overlays, and then there are the more high-level backing chains
> the user actually manages, where only the overlays are important.
>
> I think it would make sense to rename the “qemu-internal backing chains"
> to “filter chains” or something. But that makes it sound a bit like it
> would only mean R/W filters... Maybe just “chain”?
>
> Actually, the only functions I find are is_backing_chain_frozen & Co,
> and they could simply become is_chain_frozen. Is there anything else?
Chain is too general, may be, blockchain? :)))
And to be serious, one more reason to rename it is yours
bdrv_backing_chain_next which is about user-backing-chain and differs from
frozen-chain related functions.
However, I don't think that these series is good place for this renaming,
it's rather big already.
--
Best regards,
Vladimir
- Re: [Qemu-devel] [PATCH v5 21/42] block: Use CAFs for debug breakpoints, (continued)
[Qemu-devel] [PATCH v5 20/42] block/snapshot: Fall back to storage child, Max Reitz, 2019/06/12
[Qemu-devel] [PATCH v5 23/42] blockdev: Use CAF in external_snapshot_prepare(), Max Reitz, 2019/06/12
[Qemu-devel] [PATCH v5 22/42] block: Use CAFs in bdrv_get_allocated_file_size(), Max Reitz, 2019/06/12
[Qemu-devel] [PATCH v5 25/42] mirror: Deal with filters, Max Reitz, 2019/06/12
[Qemu-devel] [PATCH v5 24/42] block: Use child access functions for QAPI queries, Max Reitz, 2019/06/12