Re: [PATCH 03/12] mm: Methods for teaching filesystems about PG_swapcachepages

[Rik van Riel]

On 06/20/2012 05:37 AM, Mel Gorman wrote:
> In order to teach filesystems to handle swap cache pages, three new
> page functions are introduced:
>
>    pgoff_t page_file_index(struct page *);
>    loff_t page_file_offset(struct page *);
>    struct address_space *page_file_mapping(struct page *);
>
> page_file_index() - gives the offset of this page in the file in
> PAGE_CACHE_SIZE blocks. Like page->index is for mapped pages, this
> function also gives the correct index for PG_swapcache pages.
>
> page_file_offset() - uses page_file_index(), so that it will give
> the expected result, even for PG_swapcache pages.
>
> page_file_mapping() - gives the mapping backing the actual page;
> that is for swap cache pages it will give swap_file->f_mapping.
>
> Signed-off-by: Peter Zijlstra<a.p.zijlstra@xxxxxxxxx>
> Signed-off-by: Mel Gorman<mgorman@xxxxxxx>

Reviewed-by: Rik van Riel<riel@xxxxxxxxxx>

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