ocfs2_dlm: Fix lockres ref counting bug

During umount, the umount thread migrates the lockres' and the dlm_thread
frees the empty lockres'. Due to a race, the reference counting on the
lockres goes awry leading to extra puts.

Signed-off-by: Sunil Mushran <sunil.mushran@oracle.com>
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/fs/ocfs2/dlm/dlmdomain.c b/fs/ocfs2/dlm/dlmdomain.c
index 6087c4749fee..dbbac184c261 100644
--- a/fs/ocfs2/dlm/dlmdomain.c
+++ b/fs/ocfs2/dlm/dlmdomain.c
@@ -138,8 +138,10 @@ static void dlm_unregister_domain_handlers(struct dlm_ctxt *dlm);
 
 void __dlm_unhash_lockres(struct dlm_lock_resource *lockres)
 {
-        hlist_del_init(&lockres->hash_node);
-        dlm_lockres_put(lockres);
+        if (!hlist_unhashed(&lockres->hash_node)) {
+                hlist_del_init(&lockres->hash_node);
+                dlm_lockres_put(lockres);
+        }
 }
 
 void __dlm_insert_lockres(struct dlm_ctxt *dlm,