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SubjectRe: [PATCH v9 10/10] fsdax: set a CoW flag when associate reflink mappings
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在 2022/1/21 15:16, Christoph Hellwig 写道:
> On Fri, Jan 21, 2022 at 10:33:58AM +0800, Shiyang Ruan wrote:
>>>
>>> But different question, how does this not conflict with:
>>>
>>> #define PAGE_MAPPING_ANON 0x1
>>>
>>> in page-flags.h?
>>
>> Now we are treating dax pages, so I think its flags should be different from
>> normal page. In another word, PAGE_MAPPING_ANON is a flag of rmap mechanism
>> for normal page, it doesn't work for dax page. And now, we have dax rmap
>> for dax page. So, I think this two kinds of flags are supposed to be used
>> in different mechanisms and won't conflect.
>
> It just needs someone to use folio_test_anon in a place where a DAX
> folio can be passed. This probably should not happen, but we need to
> clearly document that.
>
>>> Either way I think this flag should move to page-flags.h and be
>>> integrated with the PAGE_MAPPING_FLAGS infrastucture.
>>
>> And that's why I keep them in this dax.c file.
>
> But that does not integrate it with the infrastructure. For people
> to debug things it needs to be next to PAGE_MAPPING_ANON and have
> documentation explaining why they are exclusive.

Ok, understood.


--
Thanks,
Ruan.


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