1 files changed, 21 insertions, 0 deletions

diff --git a/fs/ocfs2/dlm/dlmmaster.c b/fs/ocfs2/dlm/dlmmaster.c
index 21081bcfa091..78ba77bf3a77 100644
--- a/fs/ocfs2/dlm/dlmmaster.c
+++ b/fs/ocfs2/dlm/dlmmaster.c
@@ -2000,6 +2000,23 @@ static void dlm_assert_master_worker(struct dlm_work_item *item, void *data)
                 }
         }
 
+        /*
+         * If we're migrating this lock to someone else, we are no
+         * longer allowed to assert out own mastery.  OTOH, we need to
+         * prevent migration from starting while we're still asserting
+         * our dominance.  The reserved ast delays migration.
+         */
+        spin_lock(&res->spinlock);
+        if (res->state & DLM_LOCK_RES_MIGRATING) {
+                mlog(0, "Someone asked us to assert mastery, but we're "
+                     "in the middle of migration.  Skipping assert, "
+                     "the new master will handle that.\n");
+                spin_unlock(&res->spinlock);
+                goto put;
+        } else
+                __dlm_lockres_reserve_ast(res);
+        spin_unlock(&res->spinlock);
+
         /* this call now finishes out the nodemap
          * even if one or more nodes die */
         mlog(0, "worker about to master %.*s here, this=%u\n",
@@ -2012,6 +2029,10 @@ static void dlm_assert_master_worker(struct dlm_work_item *item, void *data)
                 mlog_errno(ret);
         }
 
+        /* Ok, we've asserted ourselves.  Let's let migration start. */
+        dlm_lockres_release_ast(dlm, res);
+
+put:
         dlm_lockres_put(res);
 
         mlog(0, "finished with dlm_assert_master_worker\n");