HDFS-16430. Add validation to maximum blocks in EC group when adding an EC policy (#3899). Contributed by daimin.

Reviewed-by: tomscut <litao@bigo.sg>
Signed-off-by: Ayush Saxena <ayushsaxena@apache.org>
(cherry picked from commit 5ef335da1ed49e06cc8973412952e09ed08bb9c0)

 Conflicts:
	hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/ErasureCodingPolicyManager.java

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

@@ -19,6 +19,7 @@ package org.apache.hadoop.hdfs.server.namenode;
 
 import org.apache.hadoop.thirdparty.com.google.common.annotations.VisibleForTesting;
 import org.apache.hadoop.thirdparty.com.google.common.base.Preconditions;
+import org.apache.hadoop.hdfs.server.common.HdfsServerConstants;
 import org.apache.hadoop.HadoopIllegalArgumentException;
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.conf.Configuration;
@@ -304,6 +305,12 @@ public final class ErasureCodingPolicyManager {
           + policy.getCodecName() + " is not supported");
     }
 
+    int blocksInGroup = policy.getNumDataUnits() + policy.getNumParityUnits();
+    if (blocksInGroup > HdfsServerConstants.MAX_BLOCKS_IN_GROUP) {
+      throw new HadoopIllegalArgumentException("Number of data and parity blocks in an EC group " +
+          blocksInGroup + " should not exceed maximum " + HdfsServerConstants.MAX_BLOCKS_IN_GROUP);
+    }
+
     if (policy.getCellSize() > maxCellSize) {
       throw new HadoopIllegalArgumentException("Cell size " +
           policy.getCellSize() + " should not exceed maximum " +

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

@@ -747,6 +747,15 @@ public class TestErasureCodingPolicies {
     assertEquals(1, responses.length);
     assertFalse(responses[0].isSucceed());
 
+    // Test numDataUnits + numParityUnits > 16
+    toAddSchema = new ECSchema("rs", 14, 4);
+    newPolicy =
+        new ErasureCodingPolicy(toAddSchema, 128 * 1024 * 1024);
+    policyArray = new ErasureCodingPolicy[]{newPolicy};
+    responses = fs.addErasureCodingPolicies(policyArray);
+    assertEquals(1, responses.length);
+    assertFalse(responses[0].isSucceed());
+
     // Test too big cell size
     toAddSchema = new ECSchema("rs", 3, 2);
     newPolicy =