On Thu, Mar 25, 2010 at 08:27:26PM +0800, Miao Xie wrote:
> From: Zhao Lei <zhaolei@xxxxxxxxxxxxxx>
>
> We don't need to convert PAGE_CACHE_SIZE to u64 in bit operation.
For code like this:
u64 size = (some number that doesn't fit in 32 bits)
if (size & (PAGE_CACHE_SIZE - 1)) {
}
The answer should be the same either way. But if the code gets
switched:
start = size & ~(PAGE_CACHE_SIZE - 1);
Some arches are going to get the wrong answer here. We had a few bugs
like this early on and I went through and casted everything to be
consistent. While this patch is correct, I would rather leave the casts
to avoid subtle problems later on as the code changes.
-chris
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