Messages in this thread Patch in this message | | | Date | Sat, 13 Mar 2021 12:37:16 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH v4 09/25] mm: Add folio_index, folio_page and folio_contains |
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On Fri, 5 Mar 2021 04:18:45 +0000 "Matthew Wilcox (Oracle)" <willy@infradead.org> wrote:
> folio_index() is the equivalent of page_index() for folios. folio_page() > finds the page in a folio for a page cache index. folio_contains() > tells you whether a folio contains a particular page cache index. >
copy-paste changelog into each function's covering comment?
> --- > include/linux/pagemap.h | 23 +++++++++++++++++++++++ > 1 file changed, 23 insertions(+) > > diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h > index f07c03da83f6..5094b50f7680 100644 > --- a/include/linux/pagemap.h > +++ b/include/linux/pagemap.h > @@ -447,6 +447,29 @@ static inline bool thp_contains(struct page *head, pgoff_t index) > return page_index(head) == (index & ~(thp_nr_pages(head) - 1UL)); > } > > +static inline pgoff_t folio_index(struct folio *folio) > +{ > + if (unlikely(FolioSwapCache(folio))) > + return __page_file_index(&folio->page); > + return folio->page.index; > +} > + > +static inline struct page *folio_page(struct folio *folio, pgoff_t index) > +{ > + index -= folio_index(folio); > + VM_BUG_ON_FOLIO(index >= folio_nr_pages(folio), folio); > + return &folio->page + index; > +}
One would expect folio_page() to be the reverse of page_folio(), only it isn't anything like that.
> +/* Does this folio contain this index? */ > +static inline bool folio_contains(struct folio *folio, pgoff_t index) > +{ > + /* HugeTLBfs indexes the page cache in units of hpage_size */ > + if (PageHuge(&folio->page)) > + return folio->page.index == index; > + return index - folio_index(folio) < folio_nr_pages(folio); > +} > + > /* > * Given the page we found in the page cache, return the page corresponding > * to this index in the file
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