From 94901f61b85e754a8ba4e1b8eee2e1ee4b04bca1 Mon Sep 17 00:00:00 2001
From: antirez <antirez@gmail.com>
Date: Fri, 27 Mar 2020 16:19:56 +0100
Subject: [PATCH] PSYNC2: fix backlog_idx when adjusting for meaningful offset

See #7002.
---
 src/replication.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/replication.c b/src/replication.c
index e62afb2fb..20f9a2129 100644
--- a/src/replication.c
+++ b/src/replication.c
@@ -2755,6 +2755,9 @@ void replicationCacheMasterUsingMyself(void) {
                 delta);
         server.master_initial_offset = server.master_repl_meaningful_offset;
         server.repl_backlog_histlen -= delta;
+        server.repl_backlog_idx =
+            (server.repl_backlog_idx + (server.repl_backlog_size - delta)) %
+            server.repl_backlog_size;
         if (server.repl_backlog_histlen < 0) server.repl_backlog_histlen = 0;
     }