bugfix: WAL delivery timeout could cause PostgreSQL instance to be left in in_backup state

Author: gsmolk

src/backup.c

@@ -1076,6 +1076,12 @@ pg_start_backup(const char *label, bool smooth, pgBackup *backup)
 						   2,
 						   params);
 
+	/*
+	 * Set flag that pg_start_backup() was called. If an error will happen it
+	 * is necessary to call pg_stop_backup() in backup_cleanup().
+	 */
+	backup_in_progress = true;
+
 	/* Extract timeline and LSN from results of pg_start_backup() */
 	XLogDataFromLSN(PQgetvalue(res, 0, 0), &xlogid, &xrecoff);
 	/* Calculate LSN */
@@ -1108,12 +1114,6 @@ pg_start_backup(const char *label, bool smooth, pgBackup *backup)
 	/* Wait for start_lsn to be replayed by replica */
 	if (from_replica)
 		wait_replica_wal_lsn(backup->start_lsn, true);
-
-	/*
-	 * Set flag that pg_start_backup() was called. If an error will happen it
-	 * is necessary to call pg_stop_backup() in backup_cleanup().
-	 */
-	backup_in_progress = true;
 }
 
 /*