[PATCH 5/5] mm/rmap: add anon folio unmap dispatcher function

[Dev Jain <dev.jain@arm.com>]

Add ttu_anon_folio() as the common entry point for anonymous folio
unmapping. It dispatches to the lazyfree or swapbacked helper as
appropriate, and centralizes restoration of cleared PTEs on failure.

No functional change intended.

Signed-off-by: Dev Jain <dev.jain@arm.com>
---
 mm/rmap.c | 59 +++++++++++++++++++++++++++++++++----------------------
 1 file changed, 36 insertions(+), 23 deletions(-)

diff --git a/mm/rmap.c b/mm/rmap.c
index ade78df5be2bd..f021ecd51a4a2 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -2171,6 +2171,40 @@ static inline bool ttu_anon_swapbacked_folio(struct vm_area_struct *vma, struct
 	return true;
 }
 
+static inline bool ttu_anon_folio(struct vm_area_struct *vma, struct folio *folio,
+		struct page *subpage, unsigned long address, pte_t *ptep,
+		pte_t pteval, unsigned long nr_pages)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	bool ret;
+
+	/*
+	 * Store the swap location in the pte.
+	 * See handle_pte_fault() ...
+	 */
+	if (unlikely(folio_test_swapbacked(folio) !=
+			folio_test_swapcache(folio))) {
+		WARN_ON_ONCE(1);
+		return false;
+	}
+
+	/* MADV_FREE page check */
+	if (!folio_test_swapbacked(folio)) {
+		ret = ttu_anon_lazyfree_folio(vma, folio);
+		if (ret)
+			add_mm_counter(mm, MM_ANONPAGES, -nr_pages);
+	} else {
+		/* nr_pages > 1 not supported yet */
+		ret = ttu_anon_swapbacked_folio(vma, folio, subpage, address,
+						ptep, pteval);
+	}
+
+	if (!ret)
+		set_ptes(mm, address, ptep, pteval, nr_pages);
+
+	return ret;
+}
+
 /*
  * @arg: enum ttu_flags will be passed to this argument
  */
@@ -2351,31 +2385,10 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
 			 */
 			dec_mm_counter(mm, mm_counter(folio));
 		} else if (folio_test_anon(folio)) {
-			/*
-			 * Store the swap location in the pte.
-			 * See handle_pte_fault() ...
-			 */
-			if (unlikely(folio_test_swapbacked(folio) !=
-					folio_test_swapcache(folio))) {
-				WARN_ON_ONCE(1);
+			if (!ttu_anon_folio(vma, folio, subpage, address,
+					    pvmw.pte, pteval, nr_pages))
 				goto walk_abort;
-			}
 
-			/* MADV_FREE page check */
-			if (!folio_test_swapbacked(folio)) {
-				if (!ttu_anon_lazyfree_folio(vma, folio)) {
-					set_ptes(mm, address, pvmw.pte, pteval, nr_pages);
-					goto walk_abort;
-				}
-				add_mm_counter(mm, MM_ANONPAGES, -nr_pages);
-				goto finish_unmap;
-			}
-
-			if (!ttu_anon_swapbacked_folio(vma, folio, subpage, address,
-						pvmw.pte, pteval)) {
-				set_pte_at(mm, address, pvmw.pte, pteval);
-				goto walk_abort;
-			}
 			goto finish_unmap;
 		} else {
 			/*
-- 
2.43.0