From 1ec0099838bc73430c82ed0f79fc30aaee555421 Mon Sep 17 00:00:00 2001
From: John Spray <john.spray@redhat.com>
Date: Wed, 11 Nov 2015 11:11:44 +0000
Subject: [PATCH] mds: fix `tell session evict`

Don't try waiting on empty context gatherbuilder.

Signed-off-by: John Spray <john.spray@redhat.com>
---
 src/mds/MDSRank.cc | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/mds/MDSRank.cc b/src/mds/MDSRank.cc
index fcb8efdda4bd..ba03d1331302 100644
--- a/src/mds/MDSRank.cc
+++ b/src/mds/MDSRank.cc
@@ -1795,8 +1795,14 @@ std::vector<entity_name_t> MDSRankDispatcher::evict_sessions(
     }
   }
 
+  dout(20) << __func__ << " matched " << victims.size() << " sessions" << dendl;
+
   std::vector<entity_name_t> result;
 
+  if (victims.empty()) {
+    return result;
+  }
+
   C_SaferCond on_safe;
   C_GatherBuilder gather(g_ceph_context, &on_safe);
   for (const auto s : victims) {
-- 
2.47.3