Index: lucene/contrib/CHANGES.txt
===================================================================
--- lucene/contrib/CHANGES.txt	(revision 1133480)
+++ lucene/contrib/CHANGES.txt	(working copy)
@@ -79,6 +79,12 @@
    First/SecondPassGroupingCollector.  (Martijn van Groningen, Mike
    McCandless)
 
+Bug Fixes
+
+  * LUCENE-3185: Fix bug in NRTCachingDirectory.deleteFile that would
+    always throw exception and sometimes fail to actually delete the
+    file.  (Mike McCandless)
+
 Build
 
  * LUCENE-3149: Upgrade contrib/icu's ICU jar file to ICU 4.8. 
Index: lucene/contrib/misc/src/test/org/apache/lucene/store/TestNRTCachingDirectory.java
===================================================================
--- lucene/contrib/misc/src/test/org/apache/lucene/store/TestNRTCachingDirectory.java	(revision 1133480)
+++ lucene/contrib/misc/src/test/org/apache/lucene/store/TestNRTCachingDirectory.java	(working copy)
@@ -111,4 +111,12 @@
     conf.setMergeScheduler(cachedFSDir.getMergeScheduler());
     IndexWriter writer = new IndexWriter(cachedFSDir, conf);
   }
+
+  public void testDeleteFile() throws Exception {
+    Directory dir = new NRTCachingDirectory(newDirectory(), 2.0, 25.0);
+    dir.createOutput("foo.txt").close();
+    dir.deleteFile("foo.txt");
+    assertEquals(0, dir.listAll().length);
+    dir.close();
+  }
 }
Index: lucene/contrib/misc/src/java/org/apache/lucene/store/NRTCachingDirectory.java
===================================================================
--- lucene/contrib/misc/src/java/org/apache/lucene/store/NRTCachingDirectory.java	(revision 1133480)
+++ lucene/contrib/misc/src/java/org/apache/lucene/store/NRTCachingDirectory.java	(working copy)
@@ -136,12 +136,15 @@
 
   @Override
   public synchronized void deleteFile(String name) throws IOException {
-    // Delete from both, in case we are currently uncaching:
     if (VERBOSE) {
       System.out.println("nrtdir.deleteFile name=" + name);
     }
-    cache.deleteFile(name);
-    delegate.deleteFile(name);
+    if (cache.fileExists(name)) {
+      assert !delegate.fileExists(name);
+      cache.deleteFile(name);
+    } else {
+      delegate.deleteFile(name);
+    }
   }
 
   @Override