1 files changed, 13 insertions, 0 deletions

diff --git a/fs/ocfs2/dlm/dlmmaster.c b/fs/ocfs2/dlm/dlmmaster.c
index a6944b25fd5b..fdf4b41d0609 100644
--- a/fs/ocfs2/dlm/dlmmaster.c
+++ b/fs/ocfs2/dlm/dlmmaster.c
@@ -757,6 +757,19 @@ lookup:
         if (tmpres) {
                 spin_unlock(&dlm->spinlock);
                 spin_lock(&tmpres->spinlock);
+
+                /*
+                 * Right after dlm spinlock was released, dlm_thread could have
+                 * purged the lockres. Check if lockres got unhashed. If so
+                 * start over.
+                 */
+                if (hlist_unhashed(&tmpres->hash_node)) {
+                        spin_unlock(&tmpres->spinlock);
+                        dlm_lockres_put(tmpres);
+                        tmpres = NULL;
+                        goto lookup;
+                }
+
                 /* Wait on the thread that is mastering the resource */
                 if (tmpres->owner == DLM_LOCK_RES_OWNER_UNKNOWN) {
                         __dlm_wait_on_lockres(tmpres);