[PATCH v2 01/20] mm: factor out large folio handling from folio_order() into folio_large_order()

[David Hildenbrand <david@xxxxxxxxxx>]

Let's factor it out into a simple helper function. This helper will
also come in handy when working with code where we know that our
folio is large.

Maybe in the future we'll have the order readily available for small and
large folios; in that case, folio_large_order() would simply translate to
folio_order().

Reviewed-by: Lance Yang <ioworker0@xxxxxxxxx>
Reviewed-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
---
 include/linux/mm.h | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index d82feabbe44f8..d00214e22a174 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1194,6 +1194,11 @@ struct inode;
 
 extern void prep_compound_page(struct page *page, unsigned int order);
 
+static inline unsigned int folio_large_order(const struct folio *folio)
+{
+	return folio->_flags_1 & 0xff;
+}
+
 /*
  * compound_order() can be called without holding a reference, which means
  * that niceties like page_folio() don't work.  These callers should be
@@ -1207,7 +1212,7 @@ static inline unsigned int compound_order(struct page *page)
 
 	if (!test_bit(PG_head, &folio->flags))
 		return 0;
-	return folio->_flags_1 & 0xff;
+	return folio_large_order(folio);
 }
 
 /**
@@ -1223,7 +1228,7 @@ static inline unsigned int folio_order(const struct folio *folio)
 {
 	if (!folio_test_large(folio))
 		return 0;
-	return folio->_flags_1 & 0xff;
+	return folio_large_order(folio);
 }
 
 #include <linux/huge_mm.h>
@@ -2139,7 +2144,7 @@ static inline long folio_nr_pages(const struct folio *folio)
 #ifdef CONFIG_64BIT
 	return folio->_folio_nr_pages;
 #else
-	return 1L << (folio->_flags_1 & 0xff);
+	return 1L << folio_large_order(folio);
 #endif
 }
 
@@ -2164,7 +2169,7 @@ static inline unsigned long compound_nr(struct page *page)
 #ifdef CONFIG_64BIT
 	return folio->_folio_nr_pages;
 #else
-	return 1L << (folio->_flags_1 & 0xff);
+	return 1L << folio_large_order(folio);
 #endif
 }
 
-- 
2.48.1