ocfs2: Check the owner of a lockres inside the spinlock

The checking of lockres owner in dlm_update_lvb() is not inside spinlock
protection. I don't see problem in current call path of dlm_update_lvb().
But just for code robustness.
Signed-off-by: Wengang Wang <wen.gang.wang@oracle.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>

fs/ocfs2/dlm/dlmast.c

@@ -185,9 +185,8 @@ static void dlm_update_lvb(struct dlm_ctxt *dlm, struct dlm_lock_resource *res,
 	BUG_ON(!lksb);
 
 	/* only updates if this node masters the lockres */
+	spin_lock(&res->spinlock);
 	if (res->owner == dlm->node_num) {
-
-		spin_lock(&res->spinlock);
 		/* check the lksb flags for the direction */
 		if (lksb->flags & DLM_LKSB_GET_LVB) {
 			mlog(0, "getting lvb from lockres for %s node\n",
@@ -202,8 +201,8 @@ static void dlm_update_lvb(struct dlm_ctxt *dlm, struct dlm_lock_resource *res,
  		 * here. In the future we might want to clear it at the time
  		 * the put is actually done.
 		 */
-		spin_unlock(&res->spinlock);
 	}
+	spin_unlock(&res->spinlock);
 
 	/* reset any lvb flags on the lksb */
 	lksb->flags &= ~(DLM_LKSB_PUT_LVB|DLM_LKSB_GET_LVB);