From 695d7ad51179d4f1f5e4168dec3758e3ffa4fe4d Mon Sep 17 00:00:00 2001
From: Patrick Donnelly <pdonnell@redhat.com>
Date: Sat, 14 Oct 2017 13:47:53 -0700
Subject: [PATCH] mds: prevent trim count from underflowing

Fixes: http://tracker.ceph.com/issues/21807

Signed-off-by: Patrick Donnelly <pdonnell@redhat.com>
(cherry picked from commit 452bdd8b35643ed82d8614efcd4ca22688392eb6)
---
 src/mds/MDCache.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/mds/MDCache.cc b/src/mds/MDCache.cc
index a2510f989819..9fc0c25b7ef6 100644
--- a/src/mds/MDCache.cc
+++ b/src/mds/MDCache.cc
@@ -6481,8 +6481,8 @@ void MDCache::trim_lru(uint64_t count, map<mds_rank_t, MCacheExpire*> &expiremap
       unexpirables.push_back(dn);
     } else {
       trimmed++;
+      if (count > 0) count--;
     }
-    count--;
   }
 
   for (auto &dn : unexpirables) {
-- 
2.47.3