Fix potential FSImage corruption. Contributed by Ekanth Sethuramalingam & Arpit Agarwal.

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

@@ -38,7 +38,8 @@ import com.google.common.collect.ImmutableList;
  * [1:3) -- the type of the entry (AclEntryType) <br>
  * [3:6) -- the permission of the entry (FsAction) <br>
  * [6:7) -- A flag to indicate whether Named entry or not <br>
- * [7:32) -- the name of the entry, which is an ID that points to a <br>
+ * [7:8) -- Reserved <br>
+ * [8:32) -- the name of the entry, which is an ID that points to a <br>
  * string in the StringTableSection. <br>
  */
 public enum AclEntryStatusFormat {
@@ -47,7 +48,8 @@ public enum AclEntryStatusFormat {
   TYPE(SCOPE.BITS, 2),
   PERMISSION(TYPE.BITS, 3),
   NAMED_ENTRY_CHECK(PERMISSION.BITS, 1),
-  NAME(NAMED_ENTRY_CHECK.BITS, 25);
+  RESERVED(NAMED_ENTRY_CHECK.BITS, 1),
+  NAME(RESERVED.BITS, 24);
 
   private final LongBitFormat BITS;
 

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

@@ -35,8 +35,8 @@ public abstract class INodeWithAdditionalFields extends INode
     implements LinkedElement {
   enum PermissionStatusFormat {
     MODE(null, 16),
-    GROUP(MODE.BITS, 25),
-    USER(GROUP.BITS, 23);
+    GROUP(MODE.BITS, 24),
+    USER(GROUP.BITS, 24);
 
     final LongBitFormat BITS;
 

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

@@ -27,25 +27,56 @@ import org.apache.hadoop.hdfs.XAttrHelper;
 
 import com.google.common.base.Preconditions;
 import com.google.common.primitives.Ints;
+import org.apache.hadoop.hdfs.util.LongBitFormat;
 
 /**
  * Class to pack XAttrs into byte[].<br>
  * For each XAttr:<br>
  *   The first 4 bytes represents XAttr namespace and name<br>
  *     [0:3)  - XAttr namespace<br>
- *     [3:32) - The name of the entry, which is an ID that points to a
+ *     [3:8) - Reserved<br>
+ *     [8:32) - The name of the entry, which is an ID that points to a
  *              string in map<br>
  *   The following two bytes represents the length of XAttr value<br>
  *   The remaining bytes is the XAttr value<br>
  */
 class XAttrFormat {
-  private static final int XATTR_NAMESPACE_MASK = (1 << 3) - 1;
-  private static final int XATTR_NAMESPACE_OFFSET = 29;
-  private static final int XATTR_NAME_MASK = (1 << 29) - 1;
-  private static final int XATTR_NAME_ID_MAX = 1 << 29;
+  private enum XAttrStatusFormat {
+
+    NAMESPACE(null, 3),
+    RESERVED(NAMESPACE.BITS, 5),
+    NAME(RESERVED.BITS, 24);
+
+    private final LongBitFormat BITS;
+
+    XAttrStatusFormat(LongBitFormat previous, int length) {
+      BITS = new LongBitFormat(name(), previous, length, 0);
+    }
+
+    static XAttr.NameSpace getNamespace(int xattrStatus) {
+      int ordinal = (int) NAMESPACE.BITS.retrieve(xattrStatus);
+      return XAttr.NameSpace.values()[ordinal];
+    }
+
+    static String getName(int xattrStatus) {
+      int id = (int) NAME.BITS.retrieve(xattrStatus);
+      return XAttrStorage.getName(id);
+    }
+
+    static int toInt(XAttr.NameSpace namespace, String name) {
+      long xattrStatusInt = 0;
+
+      xattrStatusInt = NAMESPACE.BITS
+          .combine(namespace.ordinal(), xattrStatusInt);
+      int nid = XAttrStorage.getNameSerialNumber(name);
+      xattrStatusInt = NAME.BITS
+          .combine(nid, xattrStatusInt);
+
+      return (int) xattrStatusInt;
+    }
+  }
+
   private static final int XATTR_VALUE_LEN_MAX = 1 << 16;
-  private static final XAttr.NameSpace[] XATTR_NAMESPACE_VALUES =
-      XAttr.NameSpace.values();
 
   /**
    * Unpack byte[] to XAttrs.
@@ -64,10 +95,8 @@ class XAttrFormat {
       int v = Ints.fromBytes(attrs[i], attrs[i + 1],
           attrs[i + 2], attrs[i + 3]);
       i += 4;
-      int ns = (v >> XATTR_NAMESPACE_OFFSET) & XATTR_NAMESPACE_MASK;
-      int nid = v & XATTR_NAME_MASK;
-      builder.setNameSpace(XATTR_NAMESPACE_VALUES[ns]);
-      builder.setName(XAttrStorage.getName(nid));
+      builder.setNameSpace(XAttrStatusFormat.getNamespace(v));
+      builder.setName(XAttrStatusFormat.getName(v));
       int vlen = ((0xff & attrs[i]) << 8) | (0xff & attrs[i + 1]);
       i += 2;
       if (vlen > 0) {
@@ -100,10 +129,8 @@ class XAttrFormat {
       int v = Ints.fromBytes(attrs[i], attrs[i + 1],
           attrs[i + 2], attrs[i + 3]);
       i += 4;
-      int ns = (v >> XATTR_NAMESPACE_OFFSET) & XATTR_NAMESPACE_MASK;
-      int nid = v & XATTR_NAME_MASK;
-      XAttr.NameSpace namespace = XATTR_NAMESPACE_VALUES[ns];
-      String name = XAttrStorage.getName(nid);
+      XAttr.NameSpace namespace = XAttrStatusFormat.getNamespace(v);
+      String name = XAttrStatusFormat.getName(v);
       int vlen = ((0xff & attrs[i]) << 8) | (0xff & attrs[i + 1]);
       i += 2;
       if (xAttr.getNameSpace() == namespace &&
@@ -134,15 +161,7 @@ class XAttrFormat {
     ByteArrayOutputStream out = new ByteArrayOutputStream();
     try {
       for (XAttr a : xAttrs) {
-        int nsOrd = a.getNameSpace().ordinal();
-        Preconditions.checkArgument(nsOrd < 8, "Too many namespaces.");
-        int nid = XAttrStorage.getNameSerialNumber(a.getName());
-        Preconditions.checkArgument(nid < XATTR_NAME_ID_MAX,
-            "Too large serial number of the xattr name");
-
-        // big-endian
-        int v = ((nsOrd & XATTR_NAMESPACE_MASK) << XATTR_NAMESPACE_OFFSET)
-            | (nid & XATTR_NAME_MASK);
+        int v = XAttrStatusFormat.toInt(a.getNameSpace(), a.getName());
         out.write(Ints.toByteArray(v));
         int vlen = a.getValue() == null ? 0 : a.getValue().length;
         Preconditions.checkArgument(vlen < XATTR_VALUE_LEN_MAX,