From f10906b3fdb720ef822478c7221836d67becef2b Mon Sep 17 00:00:00 2001
From: Sage Weil <sage@newdream.net>
Date: Thu, 7 Oct 2010 07:52:50 -0700
Subject: [PATCH] mds: respawn (instead of suicide) on being marked down

This makes temporarily laggy daemons will restart and rejoin the cluster
in standby mode.

Signed-off-by: Sage Weil <sage@newdream.net>
---
 src/cmds.cc    |  5 +++++
 src/mds/MDS.cc | 26 ++++++++++++++++++++++++--
 src/mds/MDS.h  |  4 ++++
 3 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/src/cmds.cc b/src/cmds.cc
index 549790d513c4d..e4e8375bad490 100644
--- a/src/cmds.cc
+++ b/src/cmds.cc
@@ -107,6 +107,11 @@ int main(int argc, const char **argv)
   
   // start mds
   MDS *mds = new MDS(g_conf.id, messenger, &mc);
+
+  // in case we have to respawn...
+  mds->orig_argc = argc;
+  mds->orig_argv = argv;
+
   mds->init();
   
   messenger->wait();
diff --git a/src/mds/MDS.cc b/src/mds/MDS.cc
index 49969668d5894..41d893a72e429 100644
--- a/src/mds/MDS.cc
+++ b/src/mds/MDS.cc
@@ -87,6 +87,9 @@ MDS::MDS(const char *n, Messenger *m, MonClient *mc) :
   logclient(messenger, &mc->monmap, mc),
   sessionmap(this) {
 
+  orig_argc = 0;
+  orig_argv = NULL;
+
   last_tid = 0;
 
   monc->set_messenger(messenger);
@@ -814,8 +817,8 @@ void MDS::handle_mds_map(MMDSMap *m)
       dout(10) << "not in map yet" << dendl;
     } else {
       dout(1) << "handle_mds_map i (" << addr
-	      << ") dne in the mdsmap, killing myself" << dendl;
-      suicide();
+	      << ") dne in the mdsmap, respawning myself" << dendl;
+      respawn();
     }
     goto out;
   }
@@ -1344,6 +1347,25 @@ void MDS::suicide()
   monc->shutdown();
 }
 
+void MDS::respawn()
+{
+  dout(1) << "respawn" << dendl;
+
+  char *new_argv[orig_argc+1];
+  dout(1) << " e: '" << orig_argv[0] << "'" << dendl;
+  for (int i=0; i<orig_argc; i++) {
+    new_argv[i] = (char *)orig_argv[i];
+    dout(1) << " " << i << ": '" << orig_argv[i] << "'" << dendl;
+  }
+  new_argv[orig_argc] = NULL;
+
+  dout(1) << " cwd " << get_current_dir_name() << dendl;
+
+  execv(orig_argv[0], new_argv);
+
+  dout(0) << "respawn execv " << orig_argv[0] << " failed with " << strerror(errno) << dendl;
+  suicide();
+}
 
 
 
diff --git a/src/mds/MDS.h b/src/mds/MDS.h
index a8b0e70d73c8f..eb34c88752bd6 100644
--- a/src/mds/MDS.h
+++ b/src/mds/MDS.h
@@ -178,6 +178,8 @@ class MDS : public Dispatcher {
 
   Logger       *logger, *mlogger;
 
+  int orig_argc;
+  const char **orig_argv;
 
  protected:
   // -- MDS state --
@@ -364,7 +366,9 @@ class MDS : public Dispatcher {
   void active_start();
   void stopping_start();
   void stopping_done();
+
   void suicide();
+  void respawn();
 
   void tick();
   
-- 
2.39.5