ocfs2/dlm: Do not purge lockres that is being migrated dlm_purge_lockres()

This patch attempts to fix a fine race between purging and migration.

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

1 files changed, 18 insertions, 2 deletions

diff --git a/fs/ocfs2/dlm/dlmthread.c b/fs/ocfs2/dlm/dlmthread.c
index 4060bb328bc8..d490b66ad9d7 100644
--- a/fs/ocfs2/dlm/dlmthread.c
+++ b/fs/ocfs2/dlm/dlmthread.c
@@ -162,12 +162,28 @@ static int dlm_purge_lockres(struct dlm_ctxt *dlm,
 
         spin_lock(&res->spinlock);
         if (!__dlm_lockres_unused(res)) {
-                spin_unlock(&res->spinlock);
                 mlog(0, "%s:%.*s: tried to purge but not unused\n",
                      dlm->name, res->lockname.len, res->lockname.name);
-                return -ENOTEMPTY;
+                __dlm_print_one_lock_resource(res);
+                spin_unlock(&res->spinlock);
+                BUG();
         }
+
+        if (res->state & DLM_LOCK_RES_MIGRATING) {
+                mlog(0, "%s:%.*s: Delay dropref as this lockres is "
+                     "being remastered\n", dlm->name, res->lockname.len,
+                     res->lockname.name);
+                /* Re-add the lockres to the end of the purge list */
+                if (!list_empty(&res->purge)) {
+                        list_del_init(&res->purge);
+                        list_add_tail(&res->purge, &dlm->purge_list);
+                }
+                spin_unlock(&res->spinlock);
+                return 0;
+        }
+
         master = (res->owner == dlm->node_num);
+
         if (!master)
                 res->state |= DLM_LOCK_RES_DROPPING_REF;
         spin_unlock(&res->spinlock);