Merge from trunk. HDFS-6620. Snapshot docs should specify about preserve options with cp command. Contributed by Stephen Chu.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2.5@1607687 13f79535-47bb-0310-9956-ffa450edef68

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

@@ -239,6 +239,9 @@ Release 2.5.0 - UNRELEASED
     HDFS-6610. TestShortCircuitLocalRead tests sometimes timeout on slow
     machines. (Charles Lamb via wang)
 
+    HDFS-6620. Snapshot docs should specify about preserve options with cp command
+    (Stephen Chu via umamahesh)
+
   OPTIMIZATIONS
 
     HDFS-6214. Webhdfs has poor throughput for files >2GB (daryn)

hadoop-hdfs-project/hadoop-hdfs/src/site/xdoc/HdfsSnapshots.xml

@@ -97,7 +97,9 @@
     <li>Listing the files in snapshot <code>s0</code>:
       <source>hdfs dfs -ls /foo/.snapshot/s0</source></li>
     <li>Copying a file from snapshot <code>s0</code>:
-      <source>hdfs dfs -cp /foo/.snapshot/s0/bar /tmp</source></li>
+      <source>hdfs dfs -cp -ptopax /foo/.snapshot/s0/bar /tmp</source>
+      <p>Note that this example uses the preserve option to preserve
+         timestamps, ownership, permission, ACLs and XAttrs.</p></li>
   </ul>
   </subsection>
   </section>

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/snapshot/TestXAttrWithSnapshot.java

@@ -26,6 +26,7 @@ import java.util.Map;
 
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.FileSystem;
+import org.apache.hadoop.fs.FsShell;
 import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.fs.XAttrSetFlag;
 import org.apache.hadoop.fs.permission.FsPermission;
@@ -38,6 +39,7 @@ import org.apache.hadoop.hdfs.protocol.SnapshotAccessControlException;
 import org.apache.hadoop.hdfs.server.namenode.NameNode;
 import org.apache.hadoop.hdfs.server.namenode.NameNodeAdapter;
 import org.apache.hadoop.io.IOUtils;
+import org.apache.hadoop.util.ToolRunner;
 import org.junit.AfterClass;
 import org.junit.Assert;
 import org.junit.Before;
@@ -57,6 +59,7 @@ public class TestXAttrWithSnapshot {
   private static int pathCount = 0;
   private static Path path, snapshotPath;
   private static String snapshotName;
+  private final int SUCCESS = 0;
   // XAttrs
   private static final String name1 = "user.a1";
   private static final byte[] value1 = { 0x31, 0x32, 0x33 };
@@ -351,6 +354,26 @@ public class TestXAttrWithSnapshot {
     hdfs.removeXAttr(filePath, name1);
   }
 
+  /**
+   * Test that users can copy a snapshot while preserving its xattrs.
+   */
+  @Test (timeout = 120000)
+  public void testCopySnapshotShouldPreserveXAttrs() throws Exception {
+    FileSystem.mkdirs(hdfs, path, FsPermission.createImmutable((short) 0700));
+    hdfs.setXAttr(path, name1, value1);
+    hdfs.setXAttr(path, name2, value2);
+    SnapshotTestHelper.createSnapshot(hdfs, path, snapshotName);
+    Path snapshotCopy = new Path(path.toString() + "-copy");
+    String[] argv = new String[] { "-cp", "-px", snapshotPath.toUri().toString(),
+        snapshotCopy.toUri().toString() };
+    int ret = ToolRunner.run(new FsShell(conf), argv);
+    assertEquals("cp -px is not working on a snapshot", SUCCESS, ret);
+
+    Map<String, byte[]> xattrs = hdfs.getXAttrs(snapshotCopy);
+    assertArrayEquals(value1, xattrs.get(name1));
+    assertArrayEquals(value2, xattrs.get(name2));
+  }
+
   /**
    * Initialize the cluster, wait for it to become active, and get FileSystem
    * instances for our test users.