staging: lustre: tidy up ldlm_resource_putref()

1/ the return value of ldlm_resource_putref() is never
  used, so change it to return 'void'.
2/ Move all of the code to run on the last putref to
   __ldlm_resource_putref_final().  This means a lock
   is taken in one function and dropped in another, but
   that isn't too uncommon, and will disappear in a future
   patch.
   Now that the code it together, it becomes apparent that
   we are dropping a ref on the namespace *before* the last
   use.  So keep the ref until after.

Signed-off-by: NeilBrown <neilb@suse.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/include/lustre_dlm.h

@@ -1190,7 +1190,7 @@ struct ldlm_resource *ldlm_resource_get(struct ldlm_namespace *ns,
 					struct ldlm_resource *parent,
 					const struct ldlm_res_id *,
 					enum ldlm_type type, int create);
-int ldlm_resource_putref(struct ldlm_resource *res);
+void ldlm_resource_putref(struct ldlm_resource *res);
 void ldlm_resource_add_lock(struct ldlm_resource *res,
 			    struct list_head *head,
 			    struct ldlm_lock *lock);

drivers/staging/lustre/lustre/ldlm/ldlm_resource.c

@@ -1195,6 +1195,7 @@ static void __ldlm_resource_putref_final(struct cfs_hash_bd *bd,
 					 struct ldlm_resource *res)
 {
 	struct ldlm_ns_bucket *nsb = res->lr_ns_bucket;
+	struct ldlm_namespace *ns = nsb->nsb_namespace;
 
 	if (!list_empty(&res->lr_granted)) {
 		ldlm_resource_dump(D_ERROR, res);
@@ -1206,15 +1207,18 @@ static void __ldlm_resource_putref_final(struct cfs_hash_bd *bd,
 		LBUG();
 	}
 
-	cfs_hash_bd_del_locked(nsb->nsb_namespace->ns_rs_hash,
+	cfs_hash_bd_del_locked(ns->ns_rs_hash,
 			       bd, &res->lr_hash);
 	lu_ref_fini(&res->lr_reference);
+	cfs_hash_bd_unlock(ns->ns_rs_hash, bd, 1);
+	if (ns->ns_lvbo && ns->ns_lvbo->lvbo_free)
+		ns->ns_lvbo->lvbo_free(res);
 	if (cfs_hash_bd_count_get(bd) == 0)
-		ldlm_namespace_put(nsb->nsb_namespace);
+		ldlm_namespace_put(ns);
+	kmem_cache_free(ldlm_resource_slab, res);
 }
 
-/* Returns 1 if the resource was freed, 0 if it remains. */
-int ldlm_resource_putref(struct ldlm_resource *res)
+void ldlm_resource_putref(struct ldlm_resource *res)
 {
 	struct ldlm_namespace *ns = ldlm_res_to_ns(res);
 	struct cfs_hash_bd   bd;
@@ -1224,15 +1228,8 @@ int ldlm_resource_putref(struct ldlm_resource *res)
 	       res, atomic_read(&res->lr_refcount) - 1);
 
 	cfs_hash_bd_get(ns->ns_rs_hash, &res->lr_name, &bd);
-	if (cfs_hash_bd_dec_and_lock(ns->ns_rs_hash, &bd, &res->lr_refcount)) {
+	if (cfs_hash_bd_dec_and_lock(ns->ns_rs_hash, &bd, &res->lr_refcount))
 		__ldlm_resource_putref_final(&bd, res);
-		cfs_hash_bd_unlock(ns->ns_rs_hash, &bd, 1);
-		if (ns->ns_lvbo && ns->ns_lvbo->lvbo_free)
-			ns->ns_lvbo->lvbo_free(res);
-		kmem_cache_free(ldlm_resource_slab, res);
-		return 1;
-	}
-	return 0;
 }
 EXPORT_SYMBOL(ldlm_resource_putref);