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Re: [Qemu-block] [PATCH v5 23/42] blockdev: Use CAF in external_snapshot
From: |
Max Reitz |
Subject: |
Re: [Qemu-block] [PATCH v5 23/42] blockdev: Use CAF in external_snapshot_prepare() |
Date: |
Fri, 14 Jun 2019 18:20:34 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 |
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?
Max
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[Qemu-block] [PATCH v5 23/42] blockdev: Use CAF in external_snapshot_prepare(), Max Reitz, 2019/06/12
[Qemu-block] [PATCH v5 24/42] block: Use child access functions for QAPI queries, Max Reitz, 2019/06/12
[Qemu-block] [PATCH v5 25/42] mirror: Deal with filters, Max Reitz, 2019/06/12
[Qemu-block] [PATCH v5 22/42] block: Use CAFs in bdrv_get_allocated_file_size(), Max Reitz, 2019/06/12