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-rw-r--r--include/linux/pagemap.h12
1 files changed, 12 insertions, 0 deletions
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 0a97b583ee8d..e1474ae18c88 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -399,6 +399,18 @@ static inline struct page *read_mapping_page(struct address_space *mapping,
}
/*
+ * Get the offset in PAGE_SIZE.
+ * (TODO: hugepage should have ->index in PAGE_SIZE)
+ */
+static inline pgoff_t page_to_pgoff(struct page *page)
+{
+ if (unlikely(PageHeadHuge(page)))
+ return page->index << compound_order(page);
+ else
+ return page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
+}
+
+/*
* Return byte-offset into filesystem object for page.
*/
static inline loff_t page_offset(struct page *page)