Index: lucene/backwards/src/test-framework/org/apache/lucene/store/MockIndexOutputWrapper.java
===================================================================
--- lucene/backwards/src/test-framework/org/apache/lucene/store/MockIndexOutputWrapper.java	(revision 1127471)
+++ lucene/backwards/src/test-framework/org/apache/lucene/store/MockIndexOutputWrapper.java	(working copy)
@@ -43,30 +43,53 @@
     this.delegate = delegate;
   }
 
+  private void safeMaybeThrowDeterministicException() throws IOException {
+    try {
+      dir.maybeThrowDeterministicException();
+    } catch (IOException e) {
+      closeInternal();
+      throw e;
+    }
+  }
+  
+  private void safeMaybeThrowIOException() throws IOException {
+    try {
+      dir.maybeThrowIOException();
+    } catch (IOException e) {
+      closeInternal();
+      throw e;
+    }
+  }
+
+  // Closes w/o checking dir.maybeThrow...
+  private void closeInternal() throws IOException {
+    delegate.close();
+    if (dir.trackDiskUsage) {
+      // Now compute actual disk usage & track the maxUsedSize
+      // in the MockDirectoryWrapper:
+      long size = dir.getRecomputedActualSizeInBytes();
+      if (size > dir.maxUsedSize) {
+        dir.maxUsedSize = size;
+      }
+    }
+    synchronized(dir) {
+      dir.openFileHandles.remove(this);
+      dir.openFilesForWrite.remove(name);
+    }
+  }
+  
   @Override
   public void close() throws IOException {
     try {
       dir.maybeThrowDeterministicException();
     } finally {
-      delegate.close();
-      if (dir.trackDiskUsage) {
-        // Now compute actual disk usage & track the maxUsedSize
-        // in the MockDirectoryWrapper:
-        long size = dir.getRecomputedActualSizeInBytes();
-        if (size > dir.maxUsedSize) {
-          dir.maxUsedSize = size;
-        }
-      }
-      synchronized(dir) {
-        dir.openFileHandles.remove(this);
-        dir.openFilesForWrite.remove(name);
-      }
+      closeInternal();
     }
   }
 
   @Override
   public void flush() throws IOException {
-    dir.maybeThrowDeterministicException();
+    safeMaybeThrowDeterministicException();
     delegate.flush();
   }
 
@@ -123,13 +146,13 @@
       }
     }
 
-    dir.maybeThrowDeterministicException();
+    safeMaybeThrowDeterministicException();
 
     if (first) {
       // Maybe throw random exception; only do this on first
       // write to a new file:
       first = false;
-      dir.maybeThrowIOException();
+      safeMaybeThrowIOException();
     }
   }
 
@@ -157,6 +180,6 @@
   public void copyBytes(IndexInput input, long numBytes) throws IOException {
     delegate.copyBytes(input, numBytes);
     // TODO: we may need to check disk full here as well
-    dir.maybeThrowDeterministicException();
+    safeMaybeThrowDeterministicException();
   }
 }
Index: lucene/src/test-framework/org/apache/lucene/store/MockIndexOutputWrapper.java
===================================================================
--- lucene/src/test-framework/org/apache/lucene/store/MockIndexOutputWrapper.java	(revision 1127471)
+++ lucene/src/test-framework/org/apache/lucene/store/MockIndexOutputWrapper.java	(working copy)
@@ -43,30 +43,53 @@
     this.delegate = delegate;
   }
 
+  private void safeMaybeThrowDeterministicException() throws IOException {
+    try {
+      dir.maybeThrowDeterministicException();
+    } catch (IOException e) {
+      closeInternal();
+      throw e;
+    }
+  }
+  
+  private void safeMaybeThrowIOException() throws IOException {
+    try {
+      dir.maybeThrowIOException();
+    } catch (IOException e) {
+      closeInternal();
+      throw e;
+    }
+  }
+  
+  // Closes w/o checking dir.maybeThrow...
+  private void closeInternal() throws IOException {
+    delegate.close();
+    if (dir.trackDiskUsage) {
+      // Now compute actual disk usage & track the maxUsedSize
+      // in the MockDirectoryWrapper:
+      long size = dir.getRecomputedActualSizeInBytes();
+      if (size > dir.maxUsedSize) {
+        dir.maxUsedSize = size;
+      }
+    }
+    synchronized(dir) {
+      dir.openFileHandles.remove(this);
+      dir.openFilesForWrite.remove(name);
+    }
+  }
+  
   @Override
   public void close() throws IOException {
     try {
       dir.maybeThrowDeterministicException();
     } finally {
-      delegate.close();
-      if (dir.trackDiskUsage) {
-        // Now compute actual disk usage & track the maxUsedSize
-        // in the MockDirectoryWrapper:
-        long size = dir.getRecomputedActualSizeInBytes();
-        if (size > dir.maxUsedSize) {
-          dir.maxUsedSize = size;
-        }
-      }
-      synchronized(dir) {
-        dir.openFileHandles.remove(this);
-        dir.openFilesForWrite.remove(name);
-      }
+      closeInternal();
     }
   }
 
   @Override
   public void flush() throws IOException {
-    dir.maybeThrowDeterministicException();
+    safeMaybeThrowDeterministicException();
     delegate.flush();
   }
 
@@ -123,13 +146,13 @@
       }
     }
 
-    dir.maybeThrowDeterministicException();
+    safeMaybeThrowDeterministicException();
 
     if (first) {
       // Maybe throw random exception; only do this on first
       // write to a new file:
       first = false;
-      dir.maybeThrowIOException();
+      safeMaybeThrowIOException();
     }
   }
 
@@ -157,6 +180,6 @@
   public void copyBytes(IndexInput input, long numBytes) throws IOException {
     delegate.copyBytes(input, numBytes);
     // TODO: we may need to check disk full here as well
-    dir.maybeThrowDeterministicException();
+    safeMaybeThrowDeterministicException();
   }
 }