Re: [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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