From: Fujii Masao <fujii@postgresql.org>
Date: Tue, 12 Jul 2022 00:31:57 +0000 (+0900)
Subject: Prevent BASE_BACKUP in the middle of another backup in the same session.
X-Git-Tag: REL_10_22~24
X-Git-Url: http://git.postgresql.org/gitweb/?a=commitdiff_plain;h=dd831afc44bf77dd1fd8095d684153bbf5544e1c;p=postgresql.git

Prevent BASE_BACKUP in the middle of another backup in the same session.

Multiple non-exclusive backups are able to be run conrrently in different
sessions. But, in the same session, only one non-exclusive backup can be
run at the same moment. If pg_backup_start (pg_start_backup in v14 or before)
is called in the middle of another non-exclusive backup in the same session,
an error is thrown.

However, previously, in logical replication walsender mode, even if that
walsender session had already called pg_backup_start and started
a non-exclusive backup, it could execute BASE_BACKUP command and
start another non-exclusive backup. Which caused subsequent pg_backup_stop
to throw an error because BASE_BACKUP unexpectedly reset the session state
marked by pg_backup_start.

This commit prevents BASE_BACKUP command in the middle of another
non-exclusive backup in the same session.

Back-patch to all supported branches.

Author: Fujii Masao
Reviewed-by: Kyotaro Horiguchi, Masahiko Sawada, Michael Paquier, Robert Haas
Discussion: https://postgr.es/m/3374718f-9fbf-a950-6d66-d973e027f44c@oss.nttdata.com
---

diff --git a/src/backend/replication/basebackup.c b/src/backend/replication/basebackup.c
index dfb0f4741fe..9ba3e3f2cd9 100644
--- a/src/backend/replication/basebackup.c
+++ b/src/backend/replication/basebackup.c
@@ -705,6 +705,12 @@ SendBaseBackup(BaseBackupCmd *cmd)
 {
 	DIR		   *dir;
 	basebackup_options opt;
+	SessionBackupState status = get_backup_status();
+
+	if (status == SESSION_BACKUP_NON_EXCLUSIVE)
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("a backup is already in progress in this session")));
 
 	parse_basebackup_options(cmd->options, &opt);