HDFS-6830. BlockInfo.addStorage fails when DN changes the storage for a block replica. (Arpit Agarwal)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1616883 13f79535-47bb-0310-9956-ffa450edef68

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

@@ -479,6 +479,9 @@ Release 2.6.0 - UNRELEASED
     HDFS-6791. A block could remain under replicated if all of its replicas are on
     decommissioned nodes. (Ming Ma via jing9)
 
+    HDFS-6830. BlockInfo.addStorage fails when DN changes the storage for a
+    block replica. (Arpit Agarwal)
+
 Release 2.5.0 - UNRELEASED
 
   INCOMPATIBLE CHANGES

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/BlockInfo.java

@@ -194,24 +194,12 @@ public int numNodes() {
    * Add a {@link DatanodeStorageInfo} location for a block
    */
   boolean addStorage(DatanodeStorageInfo storage) {
-    boolean added = true;
-    int idx = findDatanode(storage.getDatanodeDescriptor());
-    if(idx >= 0) {
-      if (getStorageInfo(idx) == storage) { // the storage is already there
-        return false;
-      } else {
-        // The block is on the DN but belongs to a different storage.
-        // Update our state.
-        removeStorage(getStorageInfo(idx));
-        added = false;      // Just updating storage. Return false.
-      }
-    }
     // find the last null node
     int lastNode = ensureCapacity(1);
     setStorageInfo(lastNode, storage);
     setNext(lastNode, null);
     setPrevious(lastNode, null);
-    return added;
+    return true;
   }
 
   /**
@@ -240,16 +228,18 @@ assert getPrevious(dnIndex) == null && getNext(dnIndex) == null :
    * Find specified DatanodeDescriptor.
    * @return index or -1 if not found.
    */
-  int findDatanode(DatanodeDescriptor dn) {
+  boolean findDatanode(DatanodeDescriptor dn) {
     int len = getCapacity();
     for(int idx = 0; idx < len; idx++) {
       DatanodeDescriptor cur = getDatanode(idx);
-      if(cur == dn)
-        return idx;
-      if(cur == null)
+      if(cur == dn) {
+        return true;
+      }
+      if(cur == null) {
         break;
+      }
     }
-    return -1;
+    return false;
   }
   /**
    * Find specified DatanodeStorageInfo.

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/BlockManager.java

@@ -2065,7 +2065,7 @@ private BlockInfo processReportedBlock(
     // Add replica if appropriate. If the replica was previously corrupt
     // but now okay, it might need to be updated.
     if (reportedState == ReplicaState.FINALIZED
-        && (storedBlock.findDatanode(dn) < 0
+        && (!storedBlock.findDatanode(dn)
         || corruptReplicas.isReplicaCorrupt(storedBlock, dn))) {
       toAdd.add(storedBlock);
     }
@@ -2246,7 +2246,7 @@ void addStoredBlockUnderConstruction(StatefulBlockInfo ucBlock,
         storageInfo, ucBlock.reportedBlock, ucBlock.reportedState);
 
     if (ucBlock.reportedState == ReplicaState.FINALIZED &&
-        block.findDatanode(storageInfo.getDatanodeDescriptor()) < 0) {
+        !block.findDatanode(storageInfo.getDatanodeDescriptor())) {
       addStoredBlock(block, storageInfo, null, true);
     }
   } 

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/DatanodeStorageInfo.java

@@ -208,12 +208,28 @@ long getBlockPoolUsed() {
   }
 
   public boolean addBlock(BlockInfo b) {
-    if(!b.addStorage(this))
-      return false;
+    // First check whether the block belongs to a different storage
+    // on the same DN.
+    boolean replaced = false;
+    DatanodeStorageInfo otherStorage =
+        b.findStorageInfo(getDatanodeDescriptor());
+
+    if (otherStorage != null) {
+      if (otherStorage != this) {
+        // The block belongs to a different storage. Remove it first.
+        otherStorage.removeBlock(b);
+        replaced = true;
+      } else {
+        // The block is already associated with this storage.
+        return false;
+      }
+    }
+
     // add to the head of the data-node list
+    b.addStorage(this);
     blockList = b.listInsert(blockList, this);
     numBlocks++;
-    return true;
+    return !replaced;
   }
 
   boolean removeBlock(BlockInfo b) {

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/blockmanagement/TestBlockInfo.java

@@ -17,6 +17,7 @@
  */
 package org.apache.hadoop.hdfs.server.blockmanagement;
 
+import static org.hamcrest.core.Is.is;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
 
@@ -59,17 +60,24 @@ public void testAddStorage() throws Exception {
 
 
   @Test
-  public void testReplaceStorageIfDifferetnOneAlreadyExistedFromSameDataNode() throws Exception {
-    BlockInfo blockInfo = new BlockInfo(3);
+  public void testReplaceStorage() throws Exception {
 
+    // Create two dummy storages.
     final DatanodeStorageInfo storage1 = DFSTestUtil.createDatanodeStorageInfo("storageID1", "127.0.0.1");
     final DatanodeStorageInfo storage2 = new DatanodeStorageInfo(storage1.getDatanodeDescriptor(), new DatanodeStorage("storageID2"));
+    final int NUM_BLOCKS = 10;
+    BlockInfo[] blockInfos = new BlockInfo[NUM_BLOCKS];
 
-    blockInfo.addStorage(storage1);
-    boolean added = blockInfo.addStorage(storage2);
+    // Create a few dummy blocks and add them to the first storage.
+    for (int i = 0; i < NUM_BLOCKS; ++i) {
+      blockInfos[i] = new BlockInfo(3);
+      storage1.addBlock(blockInfos[i]);
+    }
 
-    Assert.assertFalse(added);
-    Assert.assertEquals(storage2, blockInfo.getStorageInfo(0));
+    // Try to move one of the blocks to a different storage.
+    boolean added = storage2.addBlock(blockInfos[NUM_BLOCKS/2]);
+    Assert.assertThat(added, is(false));
+    Assert.assertThat(blockInfos[NUM_BLOCKS/2].getStorageInfo(0), is(storage2));
   }
 
   @Test