From 01514bdd5aece46f3579f12c1286ea4491394002 Mon Sep 17 00:00:00 2001
From: Sage Weil <sage@redhat.com>
Date: Sat, 9 Feb 2019 13:42:49 -0600
Subject: [PATCH] mon: record 'min_mon_release' file and prevent startup if
 it's too old

Signed-off-by: Sage Weil <sage@redhat.com>
---
 src/ceph_mon.cc          | 22 ++++++++++++++++++++++
 src/mon/MonmapMonitor.cc | 10 ++++++++++
 2 files changed, 32 insertions(+)

diff --git a/src/ceph_mon.cc b/src/ceph_mon.cc
index 68828cdf650af..4d7fa9b1c4eef 100644
--- a/src/ceph_mon.cc
+++ b/src/ceph_mon.cc
@@ -558,6 +558,28 @@ int main(int argc, const char **argv)
   register_async_signal_handler(SIGHUP, sighup_handler);
 
   MonitorDBStore *store = new MonitorDBStore(g_conf()->mon_data);
+
+  // make sure we aren't upgrading too fast
+  {
+    string val;
+    int r = store->read_meta("min_mon_release", &val);
+    if (r >= 0 && val.size()) {
+      int min = atoi(val.c_str());
+      if (min &&
+	  min + 2 < (int)ceph_release()) {
+	derr << "recorded min_mon_release is " << min
+	     << " (" << ceph_release_name(min)
+	     << ") which is >2 releases older than installed "
+	     << ceph_release() << " (" << ceph_release_name(ceph_release())
+	     << "); you can only upgrade 2 releases at a time" << dendl;
+	derr << "you should first upgrade to "
+	     << (min + 1) << " (" << ceph_release_name(min + 1) << ") or "
+	     << (min + 2) << " (" << ceph_release_name(min + 2) << ")" << dendl;
+	prefork.exit(1);
+      }
+    }
+  }
+
   {
     ostringstream oss;
     err = store->open(oss);
diff --git a/src/mon/MonmapMonitor.cc b/src/mon/MonmapMonitor.cc
index 94a51c1846cfb..0c44894dab1e5 100644
--- a/src/mon/MonmapMonitor.cc
+++ b/src/mon/MonmapMonitor.cc
@@ -81,6 +81,16 @@ void MonmapMonitor::update_from_paxos(bool *need_bootstrap)
   }
 
   check_subs();
+
+  // make sure we've recorded min_mon_release
+  string val;
+  if (mon->store->read_meta("min_mon_release", &val) < 0 ||
+      val.size() == 0 ||
+      atoi(val.c_str()) != (int)ceph_release()) {
+    dout(10) << __func__ << " updating min_mon_release meta" << dendl;
+    mon->store->write_meta("min_mon_release",
+			   stringify(ceph_release()));
+  }
 }
 
 void MonmapMonitor::create_pending()
-- 
2.39.5