Pointers to contiguous pages

Pointers to contiguous pages

[Luciano A. Stertz]

alloc_pages with the desired order of pages. I'll fill these pages with 
data and need to add them to the page cache. So I need individual 
pointers to each page contained in the buffer. How do I get them?
     Is the following code correct?

     unsigned long pfn;
     struct page *page = alloc_pages(mask, order);
     if (!page)
         return;

     /* Fill the pages... */

     pfn = page_to_pfn(page)
     for (i=0; i<(1<<order); i++, pfn++)
     {
         struct page *p = pfn_to_page(pfn);
         ...
     }

     Is this correct? Is there a better way to do this?

     Thanks in advance,
         Luciano

	P.S.: I tryied kernelnewbies first, but I guess the question is too 
specific, nobody answered yet...


-- 
Luciano A. Stertz
luciano@tteng.com.br
T&T Engenheiros Associados Ltda
http://www.tteng.com.br
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Re: Pointers to contiguous pages

[Martin J. Bligh]

> alloc_pages with the desired order of pages. I'll fill these pages with data and need to add them to the page cache. So I need individual pointers to each page contained in the buffer. How do I get them?
>      Is the following code correct?
> 
>      unsigned long pfn;
>      struct page *page = alloc_pages(mask, order);
>      if (!page)
>          return;
> 
>      /* Fill the pages... */
> 
>      pfn = page_to_pfn(page)
>      for (i=0; i<(1<<order); i++, pfn++)
>      {
>          struct page *p = pfn_to_page(pfn);
>          ...
>      }
> 
>      Is this correct? Is there a better way to do this?
> 
>      Thanks in advance,
>          Luciano
> 
> 	P.S.: I tryied kernelnewbies first, but I guess the question is too specific, nobody answered yet...

Looks about right to me, except I'm not sure I'd bother calling pfn_to_page
each time (it's not fast on more complex systems), something like this 
should work (roughly):

      unsigned long pfn;
      struct page *page = alloc_pages(mask, order);
      if (!page)
          return;
 
      /* Fill the pages... */
 
      for (i=0; i<(1<<order); i++)
      {
          struct page *p = page + i;
          ...
      }

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