[PATCH 3/9] mm/rmap: refactor lazyfree unmap commit path to commit_ttu_lazyfree_folio()

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

Clean up the code by refactoring the post-pte-clearing path of lazyfree
folio unmapping, into commit_ttu_lazyfree_folio().

No functional change is intended.

Signed-off-by: Dev Jain <dev.jain@arm.com>
---
 mm/rmap.c | 93 ++++++++++++++++++++++++++++++++-----------------------
 1 file changed, 54 insertions(+), 39 deletions(-)

diff --git a/mm/rmap.c b/mm/rmap.c
index 1fa020edd954a..a61978141ee3f 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1966,6 +1966,57 @@ static inline unsigned int folio_unmap_pte_batch(struct folio *folio,
 				     FPB_RESPECT_WRITE | FPB_RESPECT_SOFT_DIRTY);
 }
 
+static inline int commit_ttu_lazyfree_folio(struct vm_area_struct *vma,
+		struct folio *folio, unsigned long address, pte_t *ptep,
+		pte_t pteval, long nr_pages)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	int ref_count, map_count;
+
+	/*
+	 * Synchronize with gup_pte_range():
+	 * - clear PTE; barrier; read refcount
+	 * - inc refcount; barrier; read PTE
+	 */
+	smp_mb();
+
+	ref_count = folio_ref_count(folio);
+	map_count = folio_mapcount(folio);
+
+	/*
+	 * Order reads for page refcount and dirty flag
+	 * (see comments in __remove_mapping()).
+	 */
+	smp_rmb();
+
+	if (folio_test_dirty(folio) && !(vma->vm_flags & VM_DROPPABLE)) {
+		/*
+		 * redirtied either using the page table or a previously
+		 * obtained GUP reference.
+		 */
+		set_ptes(mm, address, ptep, pteval, nr_pages);
+		folio_set_swapbacked(folio);
+		return 1;
+	}
+
+	if (ref_count != 1 + map_count) {
+		/*
+		 * Additional reference. Could be a GUP reference or any
+		 * speculative reference. GUP users must mark the folio
+		 * dirty if there was a modification. This folio cannot be
+		 * reclaimed right now either way, so act just like nothing
+		 * happened.
+		 * We'll come back here later and detect if the folio was
+		 * dirtied when the additional reference is gone.
+		 */
+		set_ptes(mm, address, ptep, pteval, nr_pages);
+		return 1;
+	}
+
+	add_mm_counter(mm, MM_ANONPAGES, -nr_pages);
+	return 0;
+}
+
 /*
  * @arg: enum ttu_flags will be passed to this argument
  */
@@ -2227,46 +2278,10 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma,
 
 			/* MADV_FREE page check */
 			if (!folio_test_swapbacked(folio)) {
-				int ref_count, map_count;
-
-				/*
-				 * Synchronize with gup_pte_range():
-				 * - clear PTE; barrier; read refcount
-				 * - inc refcount; barrier; read PTE
-				 */
-				smp_mb();
-
-				ref_count = folio_ref_count(folio);
-				map_count = folio_mapcount(folio);
-
-				/*
-				 * Order reads for page refcount and dirty flag
-				 * (see comments in __remove_mapping()).
-				 */
-				smp_rmb();
-
-				if (folio_test_dirty(folio) && !(vma->vm_flags & VM_DROPPABLE)) {
-					/*
-					 * redirtied either using the page table or a previously
-					 * obtained GUP reference.
-					 */
-					set_ptes(mm, address, pvmw.pte, pteval, nr_pages);
-					folio_set_swapbacked(folio);
+				if (commit_ttu_lazyfree_folio(vma, folio, address,
+							      pvmw.pte, pteval,
+							      nr_pages))
 					goto walk_abort;
-				} else if (ref_count != 1 + map_count) {
-					/*
-					 * Additional reference. Could be a GUP reference or any
-					 * speculative reference. GUP users must mark the folio
-					 * dirty if there was a modification. This folio cannot be
-					 * reclaimed right now either way, so act just like nothing
-					 * happened.
-					 * We'll come back here later and detect if the folio was
-					 * dirtied when the additional reference is gone.
-					 */
-					set_ptes(mm, address, pvmw.pte, pteval, nr_pages);
-					goto walk_abort;
-				}
-				add_mm_counter(mm, MM_ANONPAGES, -nr_pages);
 				goto discard;
 			}
 
-- 
2.34.1