HDFS-13586. Fsync fails on directories on Windows. Contributed by Lukas Majercack.

(cherry picked from commit 8783613696674aba4ae1739c6e8f48cda0d1c386)

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/io/IOUtils.java

@@ -398,6 +398,13 @@ public class IOUtils {
           "File/Directory " + fileToSync.getAbsolutePath() + " does not exist");
     }
     boolean isDir = fileToSync.isDirectory();
+
+    // HDFS-13586, FileChannel.open fails with AccessDeniedException
+    // for any directory, ignore.
+    if (isDir && Shell.WINDOWS) {
+      return;
+    }
+
     // If the file is a directory we have to open read-only, for regular files
     // we must open r/w for the fsync to have an effect. See
     // http://blog.httrack.com/blog/2013/11/15/