[RFC PATCH 02/11] mm: Add put_folio

[Matthew Wilcox (Oracle)]

If we know we have a folio, we can call put_folio() instead of put_page()
and save the overhead of calling compound_head().  Also skips the
devmap checks.

Signed-off-by: Matthew Wilcox (Oracle) <wi...@infradead.org>
---
 include/linux/mm.h | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 7db9a10f084b..80d38cc9561c 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1189,9 +1189,15 @@ static inline __must_check bool try_get_page(struct page 
*page)
        return true;
 }
 
+static inline void put_folio(struct folio *folio)
+{
+       if (put_page_testzero(&folio->page))
+               __put_page(&folio->page);
+}
+
 static inline void put_page(struct page *page)
 {
-       page = compound_head(page);
+       struct folio *folio = page_folio(page);
 
        /*
         * For devmap managed pages we need to catch refcount transition from
@@ -1199,13 +1205,12 @@ static inline void put_page(struct page *page)
         * need to inform the device driver through callback. See
         * include/linux/memremap.h and HMM for details.
         */
-       if (page_is_devmap_managed(page)) {
-               put_devmap_managed_page(page);
+       if (page_is_devmap_managed(&folio->page)) {
+               put_devmap_managed_page(&folio->page);
                return;
        }
 
-       if (put_page_testzero(page))
-               __put_page(page);
+       put_folio(folio);
 }
 
 /*
-- 
2.29.2