Messages in this thread | | | Date | Wed, 27 Oct 2004 09:01:24 -0700 | From | "Martin J. Bligh" <> | Subject | Re: news about IDE PIO HIGHMEM bug (was: Re: 2.6.9-mm1) |
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--"Martin J. Bligh" <mbligh@aracnet.com> wrote (on Wednesday, October 27, 2004 08:52:39 -0700):
>> Bartlomiej Zolnierkiewicz wrote: >>> We have stuct page of the first page and a offset. >>> We need to obtain struct page of the current page and map it. >> >> >> Opening this question to a wider audience. >> >> struct scatterlist gives us struct page*, and an offset+length pair. The struct page* is the _starting_ page of a potentially multi-page run of data. >> >> The question: how does one get struct page* for the second, and successive pages in a known-contiguous multi-page run, if one only knows the first page? > > If it's a higher order allocation, just page+1 should be safe. If it just > happens to be contig, it might cross a discontig boundary, and not obey > that rule. Very unlikely, but possible.
To repeat what I said in IRC ... ;-)
Actually, you could check this with the pfns being the same when >> MAX_ORDER-1. We should be aligned on a MAX_ORDER boundary, I think.
However, pfn_to_page(page_to_pfn(page) + 1) might be safer. If rather slower.
M.
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