Re: [PATCH v9 10/10] fsdax: set a CoW flag when associate reflink mappings

[Christoph Hellwig]

On Sun, Dec 26, 2021 at 10:34:39PM +0800, Shiyang Ruan wrote:
> +#define FS_DAX_MAPPING_COW	1UL
> +
> +#define MAPPING_SET_COW(m)	(m = (struct address_space *)FS_DAX_MAPPING_COW)
> +#define MAPPING_TEST_COW(m)	(((unsigned long)m & FS_DAX_MAPPING_COW) == \
> +					FS_DAX_MAPPING_COW)

These really should be inline functions and probably use lower case
names.

But different question, how does this not conflict with:

#define PAGE_MAPPING_ANON       0x1

in page-flags.h?

Either way I think this flag should move to page-flags.h and be
integrated with the PAGE_MAPPING_FLAGS infrastucture.