In pg_upgrade, only lock the old cluster if link mode is used, and do it

right after we restore the schema (a common failure point), and right
before we do the link operation.

Per suggesgtions from Robert and ^!C^!^@lvaro

4 files changed, 24 insertions, 19 deletions

diff --git a/contrib/pg_upgrade/check.c b/contrib/pg_upgrade/check.c
index 891eb9a9f0d..a5f63eb6c80 100644
--- a/contrib/pg_upgrade/check.c
+++ b/contrib/pg_upgrade/check.c
@@ -148,9 +148,8 @@ report_clusters_compatible(void)
 	}
 
 	pg_log(PG_REPORT, "\n"
-		   "If pg_upgrade fails after this point, you must re-initdb the new cluster\n"
-		   "before continuing.  You will also need to remove the \".old\" suffix from\n"
-		   "%s/global/pg_control.old.\n", old_cluster.pgdata);
+		   "If pg_upgrade fails after this point, you must re-initdb the\n"
+		   "new cluster before continuing.\n");
 }
 
 
@@ -198,8 +197,8 @@ output_completion_banner(char *deletion_script_file_name)
 	/* Did we copy the free space files? */
 	if (GET_MAJOR_VERSION(old_cluster.major_version) >= 804)
 		pg_log(PG_REPORT,
-			   "Optimizer statistics are not transferred by pg_upgrade so consider\n"
-			   "running:\n"
+			   "Optimizer statistics are not transferred by pg_upgrade so\n"
+			   "consider running:\n"
 			   "    vacuumdb --all --analyze-only\n"
 			   "on the newly-upgraded cluster.\n\n");
 	else
diff --git a/contrib/pg_upgrade/controldata.c b/contrib/pg_upgrade/controldata.c
index 8560d881193..5239601dc6b 100644
--- a/contrib/pg_upgrade/controldata.c
+++ b/contrib/pg_upgrade/controldata.c
@@ -516,11 +516,12 @@ check_control_data(ControlData *oldctrl,
 
 
 void
-rename_old_pg_control(void)
+disable_old_cluster(void)
 {
 	char		old_path[MAXPGPATH],
 				new_path[MAXPGPATH];
 
+	/* rename pg_control so old server cannot be accidentally started */
 	prep_status("Adding \".old\" suffix to old global/pg_control");
 
 	snprintf(old_path, sizeof(old_path), "%s/global/pg_control", old_cluster.pgdata);
@@ -528,4 +529,10 @@ rename_old_pg_control(void)
 	if (pg_mv_file(old_path, new_path) != 0)
 		pg_log(PG_FATAL, "Unable to rename %s to %s.\n", old_path, new_path);
 	check_ok();
+
+	pg_log(PG_REPORT, "\n"
+		   "If you want to start the old cluster, you will need to remove\n"
+		   "the \".old\" suffix from %s/global/pg_control.old.\n"
+		   "Because \"link\" mode was used, the old cluster cannot be safely\n"
+		   "started once the new cluster has been started.\n\n", old_cluster.pgdata);
 }
diff --git a/contrib/pg_upgrade/pg_upgrade.c b/contrib/pg_upgrade/pg_upgrade.c
index 15b30fc0de0..3078bcd4cd0 100644
--- a/contrib/pg_upgrade/pg_upgrade.c
+++ b/contrib/pg_upgrade/pg_upgrade.c
@@ -43,7 +43,6 @@
 #include <langinfo.h>
 #endif
 
-static void disable_old_cluster(void);
 static void prepare_new_cluster(void);
 static void prepare_new_databases(void);
 static void create_new_objects(void);
@@ -87,7 +86,6 @@ main(int argc, char **argv)
 	pg_log(PG_REPORT, "\nPerforming Upgrade\n");
 	pg_log(PG_REPORT, "------------------\n");
 
-	disable_old_cluster();
 	prepare_new_cluster();
 
 	stop_postmaster(false);
@@ -109,6 +107,16 @@ main(int argc, char **argv)
 
 	stop_postmaster(false);
 
+	/*
+	 *	Most failures happen in create_new_objects(), which has
+	 *	completed at this point.  We do this here because it is just
+	 *	before linking, which will link the old and new cluster data
+	 *	files, preventing the old cluster from being safely started
+	 *	once the new cluster is started.
+	 */
+	if (user_opts.transfer_mode == TRANSFER_MODE_LINK)
+		disable_old_cluster();
+
 	transfer_all_new_dbs(&old_cluster.dbarr, &new_cluster.dbarr,
 						 old_cluster.pgdata, new_cluster.pgdata);
 
@@ -177,14 +185,6 @@ setup(char *argv0, bool live_check)
 
 
 static void
-disable_old_cluster(void)
-{
-	/* rename pg_control so old server cannot be accidentally started */
-	rename_old_pg_control();
-}
-
-
-static void
 prepare_new_cluster(void)
 {
 	/*
diff --git a/contrib/pg_upgrade/pg_upgrade.h b/contrib/pg_upgrade/pg_upgrade.h
index 58d5201bfca..a95481509db 100644
--- a/contrib/pg_upgrade/pg_upgrade.h
+++ b/contrib/pg_upgrade/pg_upgrade.h
@@ -282,8 +282,8 @@ void		create_script_for_old_cluster_deletion(char **deletion_script_file_name);
 /* controldata.c */
 
 void		get_control_data(ClusterInfo *cluster, bool live_check);
-void check_control_data(ControlData *oldctrl,
-				   ControlData *newctrl);
+void		check_control_data(ControlData *oldctrl, ControlData *newctrl);
+void		disable_old_cluster(void);
 
 
 /* dump.c */
@@ -298,7 +298,6 @@ int exec_prog(bool throw_error, const char *cmd, ...)
 	__attribute__((format(PG_PRINTF_ATTRIBUTE, 2, 3)));
 void		verify_directories(void);
 bool		is_server_running(const char *datadir);
-void		rename_old_pg_control(void);
 
 
 /* file.c */