From: Sage Weil <sage@redhat.com>
Date: Wed, 23 Sep 2015 14:58:01 +0000 (-0400)
Subject: mon/Elector: do a trivial write on every election cycle
X-Git-Tag: v0.80.11~12^2
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=refs%2Fpull%2F6091%2Fhead;p=ceph.git

mon/Elector: do a trivial write on every election cycle

Currently we already do a small write when the *first* election in
a round happens (to update the election epoch).  If the backend
happens to fail while we are already in the midst of elections,
however, we may continue to call elections without verifying we
are still writeable.

Signed-off-by: Sage Weil <sage@redhat.com>
(cherry picked from commit ef909ccbdc303cce8a39edef255325127832ff16)

    Conflicts:
	src/mon/Elector.cc
            no MonitorDBStore::TransactionRef in firefly
---

diff --git a/src/mon/Elector.cc b/src/mon/Elector.cc
index 2ee10f7b960..debe58c551a 100644
--- a/src/mon/Elector.cc
+++ b/src/mon/Elector.cc
@@ -78,8 +78,15 @@ void Elector::start()
   init();
   
   // start by trying to elect me
-  if (epoch % 2 == 0) 
+  if (epoch % 2 == 0) {
     bump_epoch(epoch+1);  // odd == election cycle
+  } else {
+    // do a trivial db write just to ensure it is writeable.
+    MonitorDBStore::Transaction t;
+    t.put(Monitor::MONITOR_NAME, "election_writeable_test", rand());
+    int r = mon->store->apply_transaction(t);
+    assert(r >= 0);
+  }
   start_stamp = ceph_clock_now(g_ceph_context);
   electing_me = true;
   acked_me[mon->rank] = CEPH_FEATURES_ALL;