nfs4: fix removal of derived states

Motivation:
when derived state is not released, parent (open) state
disposal should take care and remove them, for instance,
CLOSE must release all locks associated with an opened
file.

Current implementation disposes the derived states, but
doesn't remove them, which leads to a memory leak.

Modification:
remove state if it's not disposed.

Result:
fixes state id leak

Acked-by: Paul Millar
Target: master

core/src/main/java/org/dcache/nfs/v4/NFS4Client.java

@@ -324,7 +324,14 @@ public NFS4State createState(StateOwner stateOwner, NFS4State openState) throws
 
         NFS4State state = new NFS4State(openState, stateOwner, _stateHandler.createStateId(this, _stateIdCounter.incrementAndGet()));
         if (openState != null) {
-            openState.addDisposeListener(s -> state.tryDispose());
+            openState.addDisposeListener(s -> {
+                // remove and dispose derived states.
+                NFS4State nfsState = _clientStates.remove(state.stateid());
+                if (nfsState != null) {
+                    _log.debug("removing derived state {}", nfsState);
+                    nfsState.tryDispose();
+                }
+            });
         }
         _clientStates.put(state.stateid(), state);
         return state;

core/src/main/java/org/dcache/nfs/v4/NFS4State.java

@@ -19,6 +19,7 @@
  */
 package org.dcache.nfs.v4;
 
+import com.google.common.base.MoreObjects;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -123,4 +124,15 @@ public StateOwner getStateOwner() {
     synchronized public void addDisposeListener(StateDisposeListener disposeListener) {
         _disposeListeners.add(disposeListener);
     }
+
+    @Override
+    public String toString() {
+        return MoreObjects.toStringHelper(this.getClass().getSimpleName())
+                .add("stateid", _stateid)
+                .add("open-stateid", _openState == null? null : _openState.stateid())
+                .add("owner", _owner.getRawStateOwner())
+                .add("confirmed", _isConfimed)
+                .omitNullValues()
+                .toString();
+    }
 }