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>

diff --git a/fs/ocfs2/dlm/dlmthread.c b/fs/ocfs2/dlm/dlmthread.c
index 4060bb328bc8a08c22bbd77c59835d757ebdcda5..d490b66ad9d75e1ca24667cd6a7c8626d30200e0 100644 (file)
--- 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);