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@xxxxxxxxxxxxx>
---
include/linux/pagemap.h | 23 +++++++++++++++++++++++
1 file changed, 23 insertions(+)
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 83d24b41fb04..86956e97cd5e 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
--
2.29.2
