LU-4801 ldlm: discard l_lock from struct ldlm_lock.

[fs/lustre-release.git] / lustre / ldlm / l_lock.c

diff --git a/lustre/ldlm/l_lock.c b/lustre/ldlm/l_lock.c
index a4f7c85..6d37af1 100644 (file)
--- a/lustre/ldlm/l_lock.c
+++ b/lustre/ldlm/l_lock.c
@@ -41,19 +41,24 @@
  *
  * LDLM locking uses resource to serialize access to locks
  * but there is a case when we change resource of lock upon
- * enqueue reply. We rely on lock->l_resource = new_res
+ * enqueue reply. We rely on rcu_assign_pointer(lock->l_resource, new_res)
  * being an atomic operation.
  */
 struct ldlm_resource *lock_res_and_lock(struct ldlm_lock *lock)
 {
-       /* on server-side resource of lock doesn't change */
-       if (!ldlm_is_ns_srv(lock))
-               spin_lock(&lock->l_lock);
+       struct ldlm_resource *res;
 
-       lock_res(lock->l_resource);
-
-       ldlm_set_res_locked(lock);
-       return lock->l_resource;
+       rcu_read_lock();
+       while (1) {
+               res = rcu_dereference(lock->l_resource);
+               lock_res(res);
+               if (res == lock->l_resource) {
+                       ldlm_set_res_locked(lock);
+                       rcu_read_unlock();
+                       return res;
+               }
+               unlock_res(res);
+       }
 }
 EXPORT_SYMBOL(lock_res_and_lock);
 
@@ -62,11 +67,8 @@ EXPORT_SYMBOL(lock_res_and_lock);
  */
 void unlock_res_and_lock(struct ldlm_lock *lock)
 {
-       /* on server-side resource of lock doesn't change */
        ldlm_clear_res_locked(lock);
 
        unlock_res(lock->l_resource);
-       if (!ldlm_is_ns_srv(lock))
-               spin_unlock(&lock->l_lock);
 }
 EXPORT_SYMBOL(unlock_res_and_lock);