[PATCH 14/17] gup: Convert for_each_compound_head() to gup_for_each_folio()

["Matthew Wilcox (Oracle)" <willy@infradead.org>]

This macro can be considerably simplified by returning the folio from
gup_folio_next() instead of void from compound_next().  Convert both
callers to work on folios instead of pages.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 mm/gup.c | 47 ++++++++++++++++++++++++-----------------------
 1 file changed, 24 insertions(+), 23 deletions(-)

diff --git a/mm/gup.c b/mm/gup.c
index 7bd1e4a2648a..eaffa6807609 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -239,31 +239,29 @@ static inline void compound_range_next(unsigned long i, unsigned long npages,
 	     __i < __npages; __i += __ntails, \
 	     compound_range_next(__i, __npages, __list, &(__head), &(__ntails)))
 
-static inline void compound_next(unsigned long i, unsigned long npages,
-				 struct page **list, struct page **head,
-				 unsigned int *ntails)
+static inline struct folio *gup_folio_next(unsigned long i,
+		unsigned long npages, struct page **list, unsigned int *ntails)
 {
-	struct page *page;
+	struct folio *folio;
 	unsigned int nr;
 
 	if (i >= npages)
-		return;
+		return NULL;
 
-	page = compound_head(list[i]);
+	folio = page_folio(list[i]);
 	for (nr = i + 1; nr < npages; nr++) {
-		if (compound_head(list[nr]) != page)
+		if (page_folio(list[nr]) != folio)
 			break;
 	}
 
-	*head = page;
 	*ntails = nr - i;
+	return folio;
 }
 
-#define for_each_compound_head(__i, __list, __npages, __head, __ntails) \
-	for (__i = 0, \
-	     compound_next(__i, __npages, __list, &(__head), &(__ntails)); \
-	     __i < __npages; __i += __ntails, \
-	     compound_next(__i, __npages, __list, &(__head), &(__ntails)))
+#define gup_for_each_folio(__i, __list, __npages, __folio, __ntails) \
+	for (__i = 0; \
+	     (__folio = gup_folio_next(__i, __npages, __list, &(__ntails))) != NULL; \
+	     __i += __ntails)
 
 /**
  * unpin_user_pages_dirty_lock() - release and optionally dirty gup-pinned pages
@@ -291,15 +289,15 @@ void unpin_user_pages_dirty_lock(struct page **pages, unsigned long npages,
 				 bool make_dirty)
 {
 	unsigned long index;
-	struct page *head;
-	unsigned int ntails;
+	struct folio *folio;
+	unsigned int nr;
 
 	if (!make_dirty) {
 		unpin_user_pages(pages, npages);
 		return;
 	}
 
-	for_each_compound_head(index, pages, npages, head, ntails) {
+	gup_for_each_folio(index, pages, npages, folio, nr) {
 		/*
 		 * Checking PageDirty at this point may race with
 		 * clear_page_dirty_for_io(), but that's OK. Two key
@@ -320,9 +318,12 @@ void unpin_user_pages_dirty_lock(struct page **pages, unsigned long npages,
 		 * written back, so it gets written back again in the
 		 * next writeback cycle. This is harmless.
 		 */
-		if (!PageDirty(head))
-			set_page_dirty_lock(head);
-		put_compound_head(head, ntails, FOLL_PIN);
+		if (!folio_test_dirty(folio)) {
+			folio_lock(folio);
+			folio_mark_dirty(folio);
+			folio_unlock(folio);
+		}
+		gup_put_folio(folio, nr, FOLL_PIN);
 	}
 }
 EXPORT_SYMBOL(unpin_user_pages_dirty_lock);
@@ -375,8 +376,8 @@ EXPORT_SYMBOL(unpin_user_page_range_dirty_lock);
 void unpin_user_pages(struct page **pages, unsigned long npages)
 {
 	unsigned long index;
-	struct page *head;
-	unsigned int ntails;
+	struct folio *folio;
+	unsigned int nr;
 
 	/*
 	 * If this WARN_ON() fires, then the system *might* be leaking pages (by
@@ -386,8 +387,8 @@ void unpin_user_pages(struct page **pages, unsigned long npages)
 	if (WARN_ON(IS_ERR_VALUE(npages)))
 		return;
 
-	for_each_compound_head(index, pages, npages, head, ntails)
-		put_compound_head(head, ntails, FOLL_PIN);
+	gup_for_each_folio(index, pages, npages, folio, nr)
+		gup_put_folio(folio, nr, FOLL_PIN);
 }
 EXPORT_SYMBOL(unpin_user_pages);
 
-- 
2.33.0