HDFS-9516. Truncate file fails with data dirs on multiple disks. Contributed by Plamen Jeliazkov.

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

@@ -33,6 +33,9 @@ Release 2.7.3 - UNRELEASED
     HDFS-9314. Improve BlockPlacementPolicyDefault's picking of excess
     replicas. (Xiao Chen via zhz)
 
+    HDFS-9516. Truncate file fails with data dirs on multiple disks.
+    (Plamen Jeliazkov via shv)
+
 Release 2.7.2 - UNRELEASED
 
   INCOMPATIBLE CHANGES

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/FsDatasetImpl.java

@@ -2442,8 +2442,14 @@ class FsDatasetImpl implements FsDatasetSpi<FsVolumeImpl> {
       } else {
         // Copying block to a new block with new blockId.
         // Not truncating original block.
+        FsVolumeSpi volume = rur.getVolume();
+        String blockPath = blockFile.getAbsolutePath();
+        String volumePath = volume.getBasePath();
+        assert blockPath.startsWith(volumePath) :
+            "New block file: " + blockPath + " must be on " +
+                "same volume as recovery replica: " + volumePath;
         ReplicaBeingWritten newReplicaInfo = new ReplicaBeingWritten(
-            newBlockId, recoveryId, rur.getVolume(), blockFile.getParentFile(),
+            newBlockId, recoveryId, volume, blockFile.getParentFile(),
             newlength);
         newReplicaInfo.setNumBytes(newlength);
         volumeMap.add(bpid, newReplicaInfo);
@@ -2459,10 +2465,8 @@ class FsDatasetImpl implements FsDatasetSpi<FsVolumeImpl> {
       ReplicaUnderRecovery replicaInfo, String bpid, long newBlkId, long newGS)
       throws IOException {
     String blockFileName = Block.BLOCK_FILE_PREFIX + newBlkId;
-    FsVolumeReference v = volumes.getNextVolume(
-        replicaInfo.getVolume().getStorageType(), replicaInfo.getNumBytes());
-    final File tmpDir = ((FsVolumeImpl) v.getVolume())
-        .getBlockPoolSlice(bpid).getTmpDir();
+    FsVolumeImpl v = (FsVolumeImpl) replicaInfo.getVolume();
+    final File tmpDir = v.getBlockPoolSlice(bpid).getTmpDir();
     final File destDir = DatanodeUtil.idToBlockDir(tmpDir, newBlkId);
     final File dstBlockFile = new File(destDir, blockFileName);
     final File dstMetaFile = FsDatasetUtil.getMetaFile(dstBlockFile, newGS);