From: John Spray <john.spray@redhat.com>
Date: Mon, 19 Sep 2016 14:22:01 +0000 (+0100)
Subject: mds: use a random nonce in Messenger
X-Git-Tag: v10.2.6~36^2~12^2~1
X-Git-Url: http://git.apps.os.sepia.ceph.com/?a=commitdiff_plain;h=bcf228913e41604fb83aad08449dddad566f5def;p=ceph.git

mds: use a random nonce in Messenger

The MDS is a client to the OSDs, and responds
to blacklists by respawning itself.  Usually
respawns of a daemonized process result in a PID
change, but it's not guaranteed, and it's definitely
not the case when someone runs in foreground (e.g.
teuthology).

Using a random nonce makes sure we won't match
against an existing blacklist entry from a failed
instance of an MDS daemon with the same name as us.

Related to: http://tracker.ceph.com/issues/17236
Signed-off-by: John Spray <john.spray@redhat.com>

(cherry picked from commit 5ba612882750dae6f0b057c660cd283293a18a3f)

Conflicts:
	src/ceph_mds.cc : Messenger::create() prototype is different
---

diff --git a/src/ceph_mds.cc b/src/ceph_mds.cc
index efe22e6b995ff..58bda1b5422ac 100644
--- a/src/ceph_mds.cc
+++ b/src/ceph_mds.cc
@@ -136,9 +136,12 @@ int main(int argc, const char **argv)
       "MDS names may not start with a numeric digit." << dendl;
   }
 
+  uint64_t nonce = 0;
+  get_random_bytes((char*)&nonce, sizeof(nonce));
+
   Messenger *msgr = Messenger::create(g_ceph_context, g_conf->ms_type,
 				      entity_name_t::MDS(-1), "mds",
-				      getpid());
+				      nonce);
   if (!msgr)
     exit(1);
   msgr->set_cluster_protocol(CEPH_MDS_PROTOCOL);