inhibit_m_s_w_k_s_during_upgrade.txt

diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 99823df3c7..b1495c4754 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -52,6 +52,7 @@
 #include "storage/proc.h"
 #include "storage/procarray.h"
 #include "utils/builtins.h"
+#include "utils/guc_hooks.h"
 
 /*
  * Replication slot on-disk data structure.
@@ -111,6 +112,17 @@ static void RestoreSlotFromDisk(const char *name);
 static void CreateSlotOnDisk(ReplicationSlot *slot);
 static void SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel);
 
+/*
+ * GUC check_hook for max_slot_wal_keep_size
+ */
+bool
+check_max_slot_wal_keep_size(int *newval, void **extra, GucSource source)
+{
+	if (IsBinaryUpgrade && *newval != -1)
+		return false;
+	return true;
+}
+
 /*
  * Report shared-memory space needed by ReplicationSlotsShmemInit.
  */
diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c
index 7605eff9b9..818ffdb2ae 100644
--- a/src/backend/utils/misc/guc_tables.c
+++ b/src/backend/utils/misc/guc_tables.c
@@ -2845,7 +2845,7 @@ struct config_int ConfigureNamesInt[] =
 		},
 		&max_slot_wal_keep_size_mb,
 		-1, -1, MAX_KILOBYTES,
-		NULL, NULL, NULL
+		check_max_slot_wal_keep_size, NULL, NULL
 	},
 
 	{
diff --git a/src/include/utils/guc_hooks.h b/src/include/utils/guc_hooks.h
index 2a191830a8..3d74483f44 100644
--- a/src/include/utils/guc_hooks.h
+++ b/src/include/utils/guc_hooks.h
@@ -84,6 +84,8 @@ extern bool check_maintenance_io_concurrency(int *newval, void **extra,
 extern void assign_maintenance_io_concurrency(int newval, void *extra);
 extern bool check_max_connections(int *newval, void **extra, GucSource source);
 extern bool check_max_wal_senders(int *newval, void **extra, GucSource source);
+extern bool check_max_slot_wal_keep_size(int *newval, void **extra,
+										 GucSource source);
 extern void assign_max_wal_size(int newval, void *extra);
 extern bool check_max_worker_processes(int *newval, void **extra,
 									   GucSource source);