HDFS-8099. Change "DFSInputStream has been closed already" message to debug log level (Charles Lamb via Colin P. McCabe)

(cherry picked from commit 30acb7372ab97adf9bc86ead529c96cfe36e2396)

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -91,6 +91,9 @@ Release 2.8.0 - UNRELEASED
     HDFS-8101. DFSClient use of non-constant DFSConfigKeys pulls in WebHDFS
     classes at runtime. (Sean Busbey via atm)
 
+    HDFS-8099. Change "DFSInputStream has been closed already" message to
+    debug log level (Charles Lamb via Colin P. McCabe)
+
   OPTIMIZATIONS
 
     HDFS-8026. Trace FSOutputSummer#writeChecksumChunks rather than

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/DFSInputStream.java

@@ -666,7 +666,7 @@ implements ByteBufferReadable, CanSetDropBehind, CanSetReadahead,
   @Override
   public synchronized void close() throws IOException {
     if (!closed.compareAndSet(false, true)) {
-      DFSClient.LOG.warn("DFSInputStream has been closed already");
+      DFSClient.LOG.debug("DFSInputStream has been closed already");
       return;
     }
     dfsClient.checkOpen();