HDFS-8592. SafeModeException never get unwrapped. Contributed by Haohui Mai.

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

@@ -895,6 +895,8 @@ Release 2.8.0 - UNRELEASED
     HDFS-8607. TestFileCorruption doesn't work as expected. (Walter Su via
     Arpit Agarwal)
 
+    HDFS-8592. SafeModeException never get unwrapped. (wheat9)
+
 Release 2.7.1 - UNRELEASED
 
   INCOMPATIBLE CHANGES

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystem.java

@@ -1323,7 +1323,7 @@ public class FSNamesystem implements Namesystem, FSNamesystemMBean,
   void checkNameNodeSafeMode(String errorMsg)
       throws RetriableException, SafeModeException {
     if (isInSafeMode()) {
-      SafeModeException se = new SafeModeException(errorMsg, safeMode);
+      SafeModeException se = newSafemodeException(errorMsg);
       if (haEnabled && haContext != null
           && haContext.getState().getServiceState() == HAServiceState.ACTIVE
           && shouldRetrySafeMode(this.safeMode)) {
@@ -1334,6 +1334,11 @@ public class FSNamesystem implements Namesystem, FSNamesystemMBean,
     }
   }
 
+  private SafeModeException newSafemodeException(String errorMsg) {
+    return new SafeModeException(errorMsg + ". Name node is in safe " +
+        "mode.\n" + safeMode.getTurnOffTip());
+  }
+
   boolean isPermissionEnabled() {
     return isPermissionEnabled;
   }
@@ -1803,8 +1808,8 @@ public class FSNamesystem implements Namesystem, FSNamesystemMBean,
       for (LocatedBlock b : ret.blocks.getLocatedBlocks()) {
         // if safemode & no block locations yet then throw safemodeException
         if ((b.getLocations() == null) || (b.getLocations().length == 0)) {
-          SafeModeException se = new SafeModeException(
-              "Zero blocklocations for " + src, safeMode);
+          SafeModeException se = newSafemodeException(
+              "Zero blocklocations for " + src);
           if (haEnabled && haContext != null &&
               haContext.getState().getServiceState() == HAServiceState.ACTIVE) {
             throw new RetriableException(se);

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/SafeModeException.java

@@ -32,8 +32,7 @@ import org.apache.hadoop.classification.InterfaceStability;
 @InterfaceStability.Evolving
 public class SafeModeException extends IOException {
   private static final long serialVersionUID = 1L;
-
-  public SafeModeException(String text, FSNamesystem.SafeModeInfo mode ) {
-    super(text + ". Name node is in safe mode.\n" + mode.getTurnOffTip());
+  public SafeModeException(String msg) {
+    super(msg);
   }
 }

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestSafeMode.java

@@ -295,8 +295,8 @@ public class TestSafeMode {
       fail(msg);
     } catch (RemoteException re) {
       assertEquals(SafeModeException.class.getName(), re.getClassName());
-      GenericTestUtils.assertExceptionContains(
-          "Name node is in safe mode", re);
+      GenericTestUtils.assertExceptionContains("Name node is in safe mode", re);
+    } catch (SafeModeException ignored) {
     } catch (IOException ioe) {
       fail(msg + " " + StringUtils.stringifyException(ioe));
     }