[PATCH 07/17] gup: Add gup_put_folio()

["Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>]

put_compound_head() is turned into a call to gup_put_folio().
This removes the last call to put_page_refs(), so delete it.

Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
---
 mm/gup.c | 44 +++++++++++++++-----------------------------
 1 file changed, 15 insertions(+), 29 deletions(-)

diff --git a/mm/gup.c b/mm/gup.c
index 58e5cfaaa676..6d827f7d66d8 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -36,29 +36,11 @@ static void folio_pincount_add(struct folio *folio, int refs)
 	atomic_add(refs, folio_pincount_ptr(folio));
 }
 
-static void hpage_pincount_sub(struct page *page, int refs)
+static void folio_pincount_sub(struct folio *folio, int refs)
 {
-	VM_BUG_ON_PAGE(!hpage_pincount_available(page), page);
-	VM_BUG_ON_PAGE(page != compound_head(page), page);
-
-	atomic_sub(refs, compound_pincount_ptr(page));
-}
-
-/* Equivalent to calling put_page() @refs times. */
-static void put_page_refs(struct page *page, int refs)
-{
-#ifdef CONFIG_DEBUG_VM
-	if (VM_WARN_ON_ONCE_PAGE(page_ref_count(page) < refs, page))
-		return;
-#endif
+	VM_BUG_ON_FOLIO(!folio_pincount_available(folio), folio);
 
-	/*
-	 * Calling put_page() for each ref is unnecessarily slow. Only the last
-	 * ref needs a put_page().
-	 */
-	if (refs > 1)
-		page_ref_sub(page, refs - 1);
-	put_page(page);
+	atomic_sub(refs, folio_pincount_ptr(folio));
 }
 
 /*
@@ -175,19 +157,23 @@ struct page *try_grab_compound_head(struct page *page,
 	return NULL;
 }
 
-static void put_compound_head(struct page *page, int refs, unsigned int flags)
+static void gup_put_folio(struct folio *folio, int refs, unsigned int flags)
 {
 	if (flags & FOLL_PIN) {
-		mod_node_page_state(page_pgdat(page), NR_FOLL_PIN_RELEASED,
-				    refs);
-
-		if (hpage_pincount_available(page))
-			hpage_pincount_sub(page, refs);
+		node_stat_mod_folio(folio, NR_FOLL_PIN_RELEASED, refs);
+		if (folio_pincount_available(folio))
+			folio_pincount_sub(folio, refs);
 		else
 			refs *= GUP_PIN_COUNTING_BIAS;
 	}
 
-	put_page_refs(page, refs);
+	folio_put_refs(folio, refs);
+}
+
+static void put_compound_head(struct page *page, int refs, unsigned int flags)
+{
+	VM_BUG_ON_PAGE(PageTail(page), page);
+	gup_put_folio((struct folio *)page, refs, flags);
 }
 
 /**
@@ -228,7 +214,7 @@ bool __must_check try_grab_page(struct page *page, unsigned int flags)
  */
 void unpin_user_page(struct page *page)
 {
-	put_compound_head(compound_head(page), 1, FOLL_PIN);
+	gup_put_folio(page_folio(page), 1, FOLL_PIN);
 }
 EXPORT_SYMBOL(unpin_user_page);
 
-- 
2.33.0