From 86a4bed6732b18ee3dcf729d7e5fc784b6680843 Mon Sep 17 00:00:00 2001
From: Somnath Roy <somnath.roy@sandisk.com>
Date: Mon, 15 Sep 2014 17:23:51 -0700
Subject: [PATCH] FileStore: Race condition during object delete is fixed

There was a race condition (hence OSD crash) between lfn_unlink
and lfn_open. The reason was FDCache lookup was called without
taking index lock from lfn_open. Lookup will increase reference
count and thus Clear will not be able to delete those FDs. FDs
will be leaked. The assert within FDCache clear was hitting
because of this.

Fixes: #9480

Signed-off-by: Somnath Roy <somnath.roy@sandisk.com>
---
 src/os/FileStore.cc | 27 +++++++++++----------------
 1 file changed, 11 insertions(+), 16 deletions(-)

diff --git a/src/os/FileStore.cc b/src/os/FileStore.cc
index e91bda69d371..f22ca6bb25cc 100644
--- a/src/os/FileStore.cc
+++ b/src/os/FileStore.cc
@@ -230,23 +230,9 @@ int FileStore::lfn_open(coll_t cid,
 	   oid.generation == ghobject_t::NO_GEN ));
   assert(outfd);
   int r = 0;
-
   bool need_lock = true;
-  if (!replaying) {
-    *outfd = fdcache.lookup(oid);
-    if (*outfd) {
-      if (!index) {
-        return 0;
-      } else {
-        if (!((*index).index)) {
-          r = get_index(cid, index);
-          return r;
-        }
-      }
-    }
-  }
-
   int flags = O_RDWR;
+
   if (create)
     flags |= O_CREAT;
 
@@ -254,7 +240,6 @@ int FileStore::lfn_open(coll_t cid,
   if (!index) {
     index = &index2;
   }
-
   if (!((*index).index)) {
     r = get_index(cid, index);
   } else {
@@ -266,6 +251,16 @@ int FileStore::lfn_open(coll_t cid,
   if (need_lock) {
     ((*index).index)->access_lock.get_write();
   }
+  if (!replaying) {
+    *outfd = fdcache.lookup(oid);
+    if (*outfd) {
+      if (need_lock) {
+        ((*index).index)->access_lock.put_write();
+      }
+      return 0;
+    }
+  }
+
 
   IndexedPath path2;
   IndexedPath *path = &path2;
-- 
2.47.3