| Message ID | 20210305041901.2396498-10-willy@infradead.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Page folios | expand |
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
On Sat, Mar 13, 2021 at 12:37:16PM -0800, Andrew Morton wrote: > 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? Certainly. > > +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. It is ... but only for files. So maybe folio_file_page()?
On Sat, Mar 13, 2021 at 12:37:16PM -0800, Andrew Morton wrote: > 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? Yes, I think documenting all these helpers would be very useful. The lack of good commens on some of the page related existing helpers has driven me insane sometimes.
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; +} + +/* 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
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. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> --- include/linux/pagemap.h | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+)