HADOOP-12055. Deprecate usage of NativeIO#link. Contributed by Andrew Wang.

(cherry picked from commit e46cb80002)

hadoop-common-project/hadoop-common/CHANGES.txt

@@ -150,6 +150,8 @@ Release 2.8.0 - UNRELEASED
     HADOOP-12056. Use DirectoryStream in DiskChecker#checkDirs to detect
     errors when listing a directory. (Zhihai Xu via wang)
 
+    HADOOP-12055. Deprecate usage of NativeIO#link. (Andrew Wang via cnauroth)
+
   OPTIMIZATIONS
 
     HADOOP-11785. Reduce the number of listStatus operation in distcp

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

@@ -881,6 +881,17 @@ public class NativeIO {
     }
   }
 
+  /**
+   * Creates a hardlink "dst" that points to "src".
+   *
+   * This is deprecated since JDK7 NIO can create hardlinks via the
+   * {@link java.nio.file.Files} API.
+   *
+   * @param src source file
+   * @param dst hardlink location
+   * @throws IOException
+   */
+  @Deprecated
   public static void link(File src, File dst) throws IOException {
     if (!nativeLoaded) {
       HardLink.createHardLink(src, dst);

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataStorage.java

@@ -1044,7 +1044,7 @@ public class DataStorage extends Storage {
               idBasedLayoutSingleLinks.size());
           for (int j = iCopy; j < upperBound; j++) {
             LinkArgs cur = idBasedLayoutSingleLinks.get(j);
-            NativeIO.link(cur.src, cur.dst);
+            HardLink.createHardLink(cur.src, cur.dst);
           }
           return null;
         }