[Patch v4 2/4] mm/migrate.c: wrap do_move_pages_to_node() and store_status()

[Wei Yang <richardw.yang@xxxxxxxxxxxxxxx>]

Usually, do_move_pages_to_node() and store_status() are used in
combination. We have three similar call sites.

Let's provide a wrapper for both function calls -
move_pages_and_store_status - to make the calling code easier to
maintain and fix (as noted by Yang Shi, the return value handling of
do_move_pages_to_node() has a flaw).

[david@xxxxxxxxxx rephrase changelog]

Signed-off-by: Wei Yang <richardw.yang@xxxxxxxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
---
 mm/migrate.c | 29 ++++++++++++++++++-----------
 1 file changed, 18 insertions(+), 11 deletions(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index 4c2a21856717..92e8c9396368 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1583,6 +1583,18 @@ static int add_page_for_migration(struct mm_struct *mm, unsigned long addr,
 	return err;
 }
 
+static int move_pages_and_store_status(struct mm_struct *mm, int node,
+		struct list_head *pagelist, int __user *status,
+		int start, int nr)
+{
+	int err;
+
+	err = do_move_pages_to_node(mm, pagelist, node);
+	if (err)
+		return err;
+	return store_status(status, start, node, nr);
+}
+
 /*
  * Migrate an array of page address onto an array of nodes and fill
  * the corresponding array of status.
@@ -1626,10 +1638,8 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes,
 			current_node = node;
 			start = i;
 		} else if (node != current_node) {
-			err = do_move_pages_to_node(mm, &pagelist, current_node);
-			if (err)
-				goto out;
-			err = store_status(status, start, current_node, i - start);
+			err = move_pages_and_store_status(mm, current_node,
+					&pagelist, status, start, i - start);
 			if (err)
 				goto out;
 			start = i;
@@ -1658,10 +1668,8 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes,
 		if (err)
 			goto out_flush;
 
-		err = do_move_pages_to_node(mm, &pagelist, current_node);
-		if (err)
-			goto out;
-		err = store_status(status, start, current_node, i - start);
+		err = move_pages_and_store_status(mm, current_node, &pagelist,
+				status, start, i - start);
 		if (err)
 			goto out;
 		current_node = NUMA_NO_NODE;
@@ -1671,9 +1679,8 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes,
 		return err;
 
 	/* Make sure we do not overwrite the existing error */
-	err1 = do_move_pages_to_node(mm, &pagelist, current_node);
-	if (!err1)
-		err1 = store_status(status, start, current_node, i - start);
+	err1 = move_pages_and_store_status(mm, current_node, &pagelist,
+				status, start, i - start);
 	if (err >= 0)
 		err = err1;
 out:
-- 
2.17.1