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SubjectRe: [patch 2/2] [PATCH] mm: Save soft-dirty bits on file pages
On Wed, 31 Jul 2013 00:41:56 +0400 Cyrill Gorcunov <gorcunov@gmail.com> wrote:

> +#define pte_to_pgoff(pte) \
> + ((((pte).pte_low >> (PTE_FILE_SHIFT1)) \
> + & ((1U << PTE_FILE_BITS1) - 1))) \
> + + ((((pte).pte_low >> (PTE_FILE_SHIFT2)) \
> + & ((1U << PTE_FILE_BITS2) - 1)) \
> + << (PTE_FILE_BITS1)) \
> + + ((((pte).pte_low >> (PTE_FILE_SHIFT3)) \
> + & ((1U << PTE_FILE_BITS3) - 1)) \
> + << (PTE_FILE_BITS1 + PTE_FILE_BITS2)) \
> + + ((((pte).pte_low >> (PTE_FILE_SHIFT4))) \
> + << (PTE_FILE_BITS1 + PTE_FILE_BITS2 + PTE_FILE_BITS3))
> +
> +#define pgoff_to_pte(off) \
> + ((pte_t) { .pte_low = \
> + ((((off)) & ((1U << PTE_FILE_BITS1) - 1)) << PTE_FILE_SHIFT1) \
> + + ((((off) >> PTE_FILE_BITS1) \
> + & ((1U << PTE_FILE_BITS2) - 1)) \
> + << PTE_FILE_SHIFT2) \
> + + ((((off) >> (PTE_FILE_BITS1 + PTE_FILE_BITS2)) \
> + & ((1U << PTE_FILE_BITS3) - 1)) \
> + << PTE_FILE_SHIFT3) \
> + + ((((off) >> \
> + (PTE_FILE_BITS1 + PTE_FILE_BITS2 + PTE_FILE_BITS3))) \
> + << PTE_FILE_SHIFT4) \
> + + _PAGE_FILE })

Good god.

I wonder if these can be turned into out-of-line functions in some form
which humans can understand.

or

#define pte_to_pgoff(pte)
frob(pte, PTE_FILE_SHIFT1, PTE_FILE_BITS1) +
frob(PTE_FILE_SHIFT2, PTE_FILE_BITS2) +
frob(PTE_FILE_SHIFT3, PTE_FILE_BITS3) +
frob(PTE_FILE_SHIFT4, PTE_FILE_BITS1 + PTE_FILE_BITS2 + PTE_FILE_BITS3)




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