HDFS-5215. dfs.datanode.du.reserved is not considered while computing

available space ( Brahma Reddy Battula via Yongjun Zhang)

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

@@ -421,6 +421,9 @@ Release 2.8.0 - UNRELEASED
     HDFS-7916. 'reportBadBlocks' from datanodes to standby Node BPServiceActor
     goes for infinite loop (vinayakumarb)
 
+    HDFS-5215. dfs.datanode.du.reserved is not considered while computing
+    available space ( Brahma Reddy Battula via Yongjun Zhang)
+
 Release 2.7.0 - UNRELEASED
 
   INCOMPATIBLE CHANGES

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

@@ -2494,9 +2494,9 @@ class FsDatasetImpl implements FsDatasetSpi<FsVolumeImpl> {
    */
   private static class VolumeInfo {
     final String directory;
-    final long usedSpace;
-    final long freeSpace;
-    final long reservedSpace;
+    final long usedSpace; // size of space used by HDFS
+    final long freeSpace; // size of free space excluding reserved space
+    final long reservedSpace; // size of space reserved for non-HDFS and RBW
 
     VolumeInfo(FsVolumeImpl v, long usedSpace, long freeSpace) {
       this.directory = v.toString();

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

@@ -305,9 +305,11 @@ public class FsVolumeImpl implements FsVolumeSpi {
   }
   
   /**
-   * Calculate the capacity of the filesystem, after removing any
-   * reserved capacity.
-   * @return the unreserved number of bytes left in this filesystem. May be zero.
+   * Return either the configured capacity of the file system if configured; or
+   * the capacity of the file system excluding space reserved for non-HDFS.
+   * 
+   * @return the unreserved number of bytes left in this filesystem. May be
+   *         zero.
    */
   @VisibleForTesting
   public long getCapacity() {
@@ -329,10 +331,16 @@ public class FsVolumeImpl implements FsVolumeSpi {
     this.configuredCapacity = capacity;
   }
 
+  /*
+   * Calculate the available space of the filesystem, excluding space reserved
+   * for non-HDFS and space reserved for RBW
+   * 
+   * @return the available number of bytes left in this filesystem. May be zero.
+   */
   @Override
   public long getAvailable() throws IOException {
     long remaining = getCapacity() - getDfsUsed() - reservedForRbw.get();
-    long available = usage.getAvailable();
+    long available = usage.getAvailable() - reserved - reservedForRbw.get();
     if (remaining > available) {
       remaining = available;
     }