diff --git a/lucene/src/java/org/apache/lucene/codecs/lucene40/Lucene40LiveDocsFormat.java b/lucene/src/java/org/apache/lucene/codecs/lucene40/Lucene40LiveDocsFormat.java
index 768d3d7d7b3..76850fc1e14 100644
--- a/lucene/src/java/org/apache/lucene/codecs/lucene40/Lucene40LiveDocsFormat.java
+++ b/lucene/src/java/org/apache/lucene/codecs/lucene40/Lucene40LiveDocsFormat.java
@@ -4,6 +4,7 @@ import java.io.IOException;
 import java.util.Set;
 
 import org.apache.lucene.codecs.LiveDocsFormat;
+import org.apache.lucene.index.IndexFileNames;
 import org.apache.lucene.index.SegmentInfo;
 import org.apache.lucene.store.Directory;
 import org.apache.lucene.store.IOContext;
@@ -21,22 +22,36 @@ public class Lucene40LiveDocsFormat extends LiveDocsFormat {
 
   @Override
   public Bits readLiveDocs(Directory dir, SegmentInfo info, IOContext context) throws IOException {
-    // nocommit: compute filename here
-    return new BitVector(dir, info.getDelFileName(), context);
+    String filename = IndexFileNames.fileNameFromGeneration(info.name, IndexFileNames.DELETES_EXTENSION, info.getDelGen());
+    return new BitVector(dir, filename, context);
   }
 
   @Override
   public void writeLiveDocs(MutableBits bits, Directory dir, SegmentInfo info, IOContext context) throws IOException {
-    // nocommit: compute filename here
     // nocommit: this api is ugly...
-    ((BitVector)bits).write(dir, info.getDelFileName(), context);
+    String filename = IndexFileNames.fileNameFromGeneration(info.name, IndexFileNames.DELETES_EXTENSION, info.getDelGen());
+    
+    // nocommit: is it somehow cleaner to still have IW do this try/finally/delete stuff and add abort() instead?
+    boolean success = false;
+    try {
+      ((BitVector)bits).write(dir, filename, context);
+      success = true;
+    } finally {
+      if (!success) {
+        try {
+          dir.deleteFile(filename);
+        } catch (Throwable t) {
+          // suppress this so we keep throwing the
+          // original exception
+        }
+      }
+    }
   }
 
   @Override
   public void files(Directory dir, SegmentInfo info, Set<String> files) throws IOException {
-    // nocommit: compute filename here
     if (info.hasDeletions()) {
-      files.add(info.getDelFileName());
+      files.add(IndexFileNames.fileNameFromGeneration(info.name, IndexFileNames.DELETES_EXTENSION, info.getDelGen()));
     }
   }
 }
diff --git a/lucene/src/java/org/apache/lucene/index/CheckIndex.java b/lucene/src/java/org/apache/lucene/index/CheckIndex.java
index efac32a9c5c..a993fb8f27c 100644
--- a/lucene/src/java/org/apache/lucene/index/CheckIndex.java
+++ b/lucene/src/java/org/apache/lucene/index/CheckIndex.java
@@ -174,8 +174,8 @@ public class CheckIndex {
       /** True if this segment has pending deletions. */
       public boolean hasDeletions;
 
-      /** Name of the current deletions file name. */
-      public String deletionsFileName;
+      /** Current deletions generation. */
+      public long deletionsGen;
     
       /** Number of deleted documents. */
       public int numDeleted;
@@ -526,15 +526,14 @@ public class CheckIndex {
           segInfoStat.docStoreCompoundFile = info.getDocStoreIsCompoundFile();
         }
 
-        final String delFileName = info.getDelFileName();
-        if (delFileName == null){
+        if (info.hasDeletions()) {
           msg("    no deletions");
           segInfoStat.hasDeletions = false;
         }
         else{
-          msg("    has deletions [delFileName=" + delFileName + "]");
+          msg("    has deletions [delGen=" + info.getDelGen() + "]");
           segInfoStat.hasDeletions = true;
-          segInfoStat.deletionsFileName = delFileName;
+          segInfoStat.deletionsGen = info.getDelGen();
         }
         if (infoStream != null)
           infoStream.print("    test: open reader.........");
diff --git a/lucene/src/java/org/apache/lucene/index/IndexWriter.java b/lucene/src/java/org/apache/lucene/index/IndexWriter.java
index c94c47862fe..512157f063a 100644
--- a/lucene/src/java/org/apache/lucene/index/IndexWriter.java
+++ b/lucene/src/java/org/apache/lucene/index/IndexWriter.java
@@ -616,7 +616,6 @@ public class IndexWriter implements Closeable, TwoPhaseCommit {
         // We can write directly to the actual name (vs to a
         // .tmp & renaming it) because the file is not live
         // until segments file is written:
-        final String delFileName = info.getDelFileName();
         boolean success = false;
         try {
           info.getCodec().liveDocsFormat().writeLiveDocs(liveDocs, dir, info, IOContext.DEFAULT);
@@ -624,12 +623,6 @@ public class IndexWriter implements Closeable, TwoPhaseCommit {
         } finally {
           if (!success) {
             info.reset(sav);
-            try {
-              dir.deleteFile(delFileName);
-            } catch (Throwable t) {
-              // Suppress this so we keep throwing the
-              // original exception
-            }
           }
         }
         assert (info.docCount - liveDocs.count()) == info.getDelCount() + pendingDeleteCount:
@@ -2257,32 +2250,19 @@ public class IndexWriter implements Closeable, TwoPhaseCommit {
         assert delCount > 0;
         newSegment.setDelCount(delCount);
         newSegment.advanceDelGen();
-        final String delFileName = newSegment.getDelFileName();
         if (infoStream.isEnabled("IW")) {
-          infoStream.message("IW", "flush: write " + delCount + " deletes to " + delFileName);
+          infoStream.message("IW", "flush: write " + delCount + " deletes gen=" + flushedSegment.segmentInfo.getDelGen());
         }
-        boolean success2 = false;
-        try {
-          // TODO: in the NRT case it'd be better to hand
-          // this del vector over to the
-          // shortly-to-be-opened SegmentReader and let it
-          // carry the changes; there's no reason to use
-          // filesystem as intermediary here.
+
+        // TODO: in the NRT case it'd be better to hand
+        // this del vector over to the
+        // shortly-to-be-opened SegmentReader and let it
+        // carry the changes; there's no reason to use
+        // filesystem as intermediary here.
           
-          SegmentInfo info = flushedSegment.segmentInfo;
-          Codec codec = info.getCodec();
-          codec.liveDocsFormat().writeLiveDocs(flushedSegment.liveDocs, directory, info, context);
-          success2 = true;
-        } finally {
-          if (!success2) {
-            try {
-              directory.deleteFile(delFileName);
-            } catch (Throwable t) {
-              // suppress this so we keep throwing the
-              // original exception
-            }
-          }
-        }
+        SegmentInfo info = flushedSegment.segmentInfo;
+        Codec codec = info.getCodec();
+        codec.liveDocsFormat().writeLiveDocs(flushedSegment.liveDocs, directory, info, context);
       }
 
       success = true;
diff --git a/lucene/src/java/org/apache/lucene/index/SegmentInfo.java b/lucene/src/java/org/apache/lucene/index/SegmentInfo.java
index 1da48086864..d5b01d6d38d 100644
--- a/lucene/src/java/org/apache/lucene/index/SegmentInfo.java
+++ b/lucene/src/java/org/apache/lucene/index/SegmentInfo.java
@@ -326,16 +326,6 @@ public final class SegmentInfo implements Cloneable {
     return si;
   }
 
-  public String getDelFileName() {
-    if (delGen == NO) {
-      // In this case we know there is no deletion filename
-      // against this segment
-      return null;
-    } else {
-      return IndexFileNames.fileNameFromGeneration(name, IndexFileNames.DELETES_EXTENSION, delGen);
-    }
-  }
-
   /**
    * @deprecated separate norms are not supported in >= 4.0
    */