Re: [BK PATCH 2.5] Introduce 64-bit versions of PAGE_{CACHE_,}{MASK,ALIGN}

[Andrew Morton <akpm@zip.com.au>]

Anton Altaparmakov wrote:
> 
> Linus,
> 
> This patch introduces 64-bit versions of PAGE_{CACHE_,}MASK and
> PAGE_{CACHE_,}ALIGN:
>         PAGE_{CACHE_,}MASK_LL and PAGE_{CACHE_,}ALIGN_LL.
> 
> These are needed when 64-bit values are worked with on 32-bit
> architectures, otherwise the high 32-bits are destroyed.
> 
> ...
>  #define PAGE_SIZE      (1UL << PAGE_SHIFT)
>  #define PAGE_MASK      (~(PAGE_SIZE-1))
> +#define PAGE_MASK_LL   (~(u64)(PAGE_SIZE-1))

The problem here is that we've explicitly forced the
PAGE_foo type to unsigned long.

If we instead take the "UL" out of PAGE_SIZE altogether,
the compiler can then promote the type of PAGE_SIZE and PAGE_MASK
to the widest type being used in the expression (ie: long long)
and everything should work.

Which seems to be a much cleaner solution, if it works.

Will it work?

-