Re: [Qemu-devel] [PATCH v5 23/42] blockdev: Use CAF in external_snapshot_prepare()

[Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>]

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 <mreitz@redhat.com>
>>
>> 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 <vsementsov@virtuozzo.com>
>>
>> [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