[PATCH 09/12] mm: add page_rmappable_folio() wrapper

[Hugh Dickins]

folio_prep_large_rmappable() is being used repeatedly along with a
conversion from page to folio, a check non-NULL, a check order > 1:
wrap it all up into struct folio *page_rmappable_folio(struct page *).

Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx>
---
 include/linux/huge_mm.h | 13 +++++++++++++
 mm/mempolicy.c          | 17 +++--------------
 mm/page_alloc.c         |  8 ++------
 3 files changed, 18 insertions(+), 20 deletions(-)

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index fa0350b0812a..58e7662a8a62 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -141,6 +141,15 @@ unsigned long thp_get_unmapped_area(struct file *filp, unsigned long addr,
 		unsigned long len, unsigned long pgoff, unsigned long flags);
 
 void folio_prep_large_rmappable(struct folio *folio);
+static inline struct folio *page_rmappable_folio(struct page *page)
+{
+	struct folio *folio = (struct folio *)page;
+
+	if (folio && folio_order(folio) > 1)
+		folio_prep_large_rmappable(folio);
+	return folio;
+}
+
 bool can_split_folio(struct folio *folio, int *pextra_pins);
 int split_huge_page_to_list(struct page *page, struct list_head *list);
 static inline int split_huge_page(struct page *page)
@@ -281,6 +290,10 @@ static inline bool hugepage_vma_check(struct vm_area_struct *vma,
 }
 
 static inline void folio_prep_large_rmappable(struct folio *folio) {}
+static inline struct folio *page_rmappable_folio(struct page *page)
+{
+	return (struct folio *)page;
+}
 
 #define transparent_hugepage_flags 0UL
 
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 7ab6102d7da4..4c3b3f535630 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -2137,10 +2137,7 @@ struct folio *vma_alloc_folio(gfp_t gfp, int order, struct vm_area_struct *vma,
 		mpol_cond_put(pol);
 		gfp |= __GFP_COMP;
 		page = alloc_page_interleave(gfp, order, nid);
-		folio = (struct folio *)page;
-		if (folio && order > 1)
-			folio_prep_large_rmappable(folio);
-		goto out;
+		return page_rmappable_folio(page);
 	}
 
 	if (pol->mode == MPOL_PREFERRED_MANY) {
@@ -2150,10 +2147,7 @@ struct folio *vma_alloc_folio(gfp_t gfp, int order, struct vm_area_struct *vma,
 		gfp |= __GFP_COMP;
 		page = alloc_pages_preferred_many(gfp, order, node, pol);
 		mpol_cond_put(pol);
-		folio = (struct folio *)page;
-		if (folio && order > 1)
-			folio_prep_large_rmappable(folio);
-		goto out;
+		return page_rmappable_folio(page);
 	}
 
 	if (unlikely(IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && hugepage)) {
@@ -2247,12 +2241,7 @@ EXPORT_SYMBOL(alloc_pages);
 
 struct folio *folio_alloc(gfp_t gfp, unsigned order)
 {
-	struct page *page = alloc_pages(gfp | __GFP_COMP, order);
-	struct folio *folio = (struct folio *)page;
-
-	if (folio && order > 1)
-		folio_prep_large_rmappable(folio);
-	return folio;
+	return page_rmappable_folio(alloc_pages(gfp | __GFP_COMP, order));
 }
 EXPORT_SYMBOL(folio_alloc);
 
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 95546f376302..5b1707d9025a 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4456,12 +4456,8 @@ struct folio *__folio_alloc(gfp_t gfp, unsigned int order, int preferred_nid,
 		nodemask_t *nodemask)
 {
 	struct page *page = __alloc_pages(gfp | __GFP_COMP, order,
-			preferred_nid, nodemask);
-	struct folio *folio = (struct folio *)page;
-
-	if (folio && order > 1)
-		folio_prep_large_rmappable(folio);
-	return folio;
+					  preferred_nid, nodemask);
+	return page_rmappable_folio(page);
 }
 EXPORT_SYMBOL(__folio_alloc);
 
-- 
2.35.3