diff --git a/modules/elasticsearch/src/main/java/org/elasticsearch/index/engine/robin/RobinEngine.java b/modules/elasticsearch/src/main/java/org/elasticsearch/index/engine/robin/RobinEngine.java
index 73494dcc39d..53e79f11676 100644
--- a/modules/elasticsearch/src/main/java/org/elasticsearch/index/engine/robin/RobinEngine.java
+++ b/modules/elasticsearch/src/main/java/org/elasticsearch/index/engine/robin/RobinEngine.java
@@ -843,8 +843,10 @@ public class RobinEngine extends AbstractIndexShardComponent implements Engine {
                             indexWriter.commit(MapBuilder.<String, String>newMapBuilder().put(Translog.TRANSLOG_ID_KEY, Long.toString(translogId)).map());
                             translog.makeTransientCurrent();
                         } catch (Exception e) {
+                            translog.revertTransient();
                             throw new FlushFailedEngineException(shardId, e);
                         } catch (OutOfMemoryError e) {
+                            translog.revertTransient();
                             failEngine(e);
                             throw new FlushFailedEngineException(shardId, e);
                         }
diff --git a/modules/elasticsearch/src/main/java/org/elasticsearch/index/translog/Translog.java b/modules/elasticsearch/src/main/java/org/elasticsearch/index/translog/Translog.java
index c739af308e7..768a1b26dd5 100644
--- a/modules/elasticsearch/src/main/java/org/elasticsearch/index/translog/Translog.java
+++ b/modules/elasticsearch/src/main/java/org/elasticsearch/index/translog/Translog.java
@@ -87,6 +87,11 @@ public interface Translog extends IndexShardComponent {
      */
     void makeTransientCurrent();
 
+    /**
+     * Reverts back to not have a transient translog.
+     */
+    void revertTransient();
+
     /**
      * Adds a create operation to the transaction log.
      */
diff --git a/modules/elasticsearch/src/main/java/org/elasticsearch/index/translog/fs/FsTranslog.java b/modules/elasticsearch/src/main/java/org/elasticsearch/index/translog/fs/FsTranslog.java
index a9617b18ebd..582cf5163c2 100644
--- a/modules/elasticsearch/src/main/java/org/elasticsearch/index/translog/fs/FsTranslog.java
+++ b/modules/elasticsearch/src/main/java/org/elasticsearch/index/translog/fs/FsTranslog.java
@@ -35,12 +35,15 @@ import org.elasticsearch.index.translog.TranslogStreams;
 import java.io.File;
 import java.io.IOException;
 import java.nio.channels.ClosedChannelException;
+import java.util.concurrent.locks.ReadWriteLock;
+import java.util.concurrent.locks.ReentrantReadWriteLock;
 
 /**
  * @author kimchy (shay.banon)
  */
 public class FsTranslog extends AbstractIndexShardComponent implements Translog {
 
+    private final ReadWriteLock rwl = new ReentrantReadWriteLock();
     private final File location;
 
     private volatile FsTranslogFile current;
@@ -93,74 +96,118 @@ public class FsTranslog extends AbstractIndexShardComponent implements Translog
     }
 
     @Override public void clearUnreferenced() {
-        File[] files = location.listFiles();
-        if (files != null) {
-            for (File file : files) {
-                if (file.getName().equals("translog-" + current.id())) {
-                    continue;
-                }
-                try {
-                    file.delete();
-                } catch (Exception e) {
-                    // ignore
+        rwl.writeLock().lock();
+        try {
+            File[] files = location.listFiles();
+            if (files != null) {
+                for (File file : files) {
+                    if (file.getName().equals("translog-" + current.id())) {
+                        continue;
+                    }
+                    if (trans != null && file.getName().equals("translog-" + trans.id())) {
+                        continue;
+                    }
+                    try {
+                        file.delete();
+                    } catch (Exception e) {
+                        // ignore
+                    }
                 }
             }
+        } finally {
+            rwl.writeLock().unlock();
         }
     }
 
     @Override public void newTranslog(long id) throws TranslogException {
-        FsTranslogFile newFile;
+        rwl.writeLock().lock();
         try {
-            newFile = new FsTranslogFile(shardId, id, new RafReference(new File(location, "translog-" + id)));
-        } catch (IOException e) {
-            throw new TranslogException(shardId, "failed to create new translog file", e);
-        }
-        FsTranslogFile old = current;
-        current = newFile;
-        if (old != null) {
-            // we might create a new translog overriding the current translog id
-            boolean delete = true;
-            if (old.id() == id) {
-                delete = false;
+            FsTranslogFile newFile;
+            try {
+                newFile = new FsTranslogFile(shardId, id, new RafReference(new File(location, "translog-" + id)));
+            } catch (IOException e) {
+                throw new TranslogException(shardId, "failed to create new translog file", e);
             }
-            old.close(delete);
+            FsTranslogFile old = current;
+            current = newFile;
+            if (old != null) {
+                // we might create a new translog overriding the current translog id
+                boolean delete = true;
+                if (old.id() == id) {
+                    delete = false;
+                }
+                old.close(delete);
+            }
+        } finally {
+            rwl.writeLock().unlock();
         }
     }
 
     @Override public void newTransientTranslog(long id) throws TranslogException {
+        rwl.writeLock().lock();
         try {
+            assert this.trans == null;
             this.trans = new FsTranslogFile(shardId, id, new RafReference(new File(location, "translog-" + id)));
         } catch (IOException e) {
             throw new TranslogException(shardId, "failed to create new translog file", e);
+        } finally {
+            rwl.writeLock().unlock();
         }
     }
 
     @Override public void makeTransientCurrent() {
-        this.current = this.trans;
-        this.trans = null;
+        FsTranslogFile old;
+        rwl.writeLock().lock();
+        try {
+            assert this.trans != null;
+            old = current;
+            this.current = this.trans;
+            this.trans = null;
+        } finally {
+            rwl.writeLock().unlock();
+        }
+        old.close(true);
+    }
+
+    @Override public void revertTransient() {
+        FsTranslogFile old;
+        rwl.writeLock().lock();
+        try {
+            old = trans;
+            this.trans = null;
+        } finally {
+            rwl.writeLock().unlock();
+        }
+        old.close(true);
     }
 
     public byte[] read(Location location) {
-        FsTranslogFile trans = this.trans;
-        if (trans != null && trans.id() == location.translogId) {
-            try {
-                return trans.read(location);
-            } catch (Exception e) {
-                // ignore
+        rwl.readLock().lock();
+        try {
+            FsTranslogFile trans = this.trans;
+            if (trans != null && trans.id() == location.translogId) {
+                try {
+                    return trans.read(location);
+                } catch (Exception e) {
+                    // ignore
+                }
             }
-        }
-        if (current.id() == location.translogId) {
-            try {
-                return current.read(location);
-            } catch (IOException e) {
-                // ignore
+            if (current.id() == location.translogId) {
+                try {
+                    return current.read(location);
+                } catch (Exception e) {
+                    // ignore
+                }
             }
+            return null;
+        } finally {
+            rwl.readLock().unlock();
         }
-        return null;
     }
 
     @Override public Location add(Operation operation) throws TranslogException {
         CachedStreamOutput.Entry cachedEntry = CachedStreamOutput.popEntry();
+        rwl.readLock().lock();
         try {
             BytesStreamOutput out = cachedEntry.cachedBytes();
             out.writeInt(0); // marker for the size...
@@ -187,6 +234,7 @@ public class FsTranslog extends AbstractIndexShardComponent implements Translog
         } catch (Exception e) {
             throw new TranslogException(shardId, "Failed to write operation [" + operation + "]", e);
         } finally {
+            rwl.readLock().unlock();
             CachedStreamOutput.pushEntry(cachedEntry);
         }
     }
@@ -222,13 +270,18 @@ public class FsTranslog extends AbstractIndexShardComponent implements Translog
     }
 
     @Override public void close(boolean delete) {
-        FsTranslogFile current1 = this.current;
-        if (current1 != null) {
-            current1.close(delete);
-        }
-        current1 = this.trans;
-        if (current1 != null) {
-            current1.close(delete);
+        rwl.writeLock().lock();
+        try {
+            FsTranslogFile current1 = this.current;
+            if (current1 != null) {
+                current1.close(delete);
+            }
+            current1 = this.trans;
+            if (current1 != null) {
+                current1.close(delete);
+            }
+        } finally {
+            rwl.writeLock().unlock();
         }
     }
 }