HDFS-10458. getFileEncryptionInfo should return quickly for non-encrypted cluster.

(cherry picked from commit 6de9213df111a9a4ed875db995d67af72d08a798)
(cherry picked from commit 06e38c835d0ad9619d4bea662f2dd7d0f62007a9)

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

@@ -95,7 +95,7 @@ String getKeyName() {
     }
   }
 
-  private final TreeMap<Long, EncryptionZoneInt> encryptionZones;
+  private TreeMap<Long, EncryptionZoneInt> encryptionZones = null;
   private final FSDirectory dir;
   private final int maxListEncryptionZonesResponses;
 
@@ -106,7 +106,6 @@ String getKeyName() {
    */
   public EncryptionZoneManager(FSDirectory dir, Configuration conf) {
     this.dir = dir;
-    encryptionZones = new TreeMap<Long, EncryptionZoneInt>();
     maxListEncryptionZonesResponses = conf.getInt(
         DFSConfigKeys.DFS_NAMENODE_LIST_ENCRYPTION_ZONES_NUM_RESPONSES,
         DFSConfigKeys.DFS_NAMENODE_LIST_ENCRYPTION_ZONES_NUM_RESPONSES_DEFAULT
@@ -143,6 +142,9 @@ void unprotectedAddEncryptionZone(Long inodeId,
       CipherSuite suite, CryptoProtocolVersion version, String keyName) {
     final EncryptionZoneInt ez = new EncryptionZoneInt(
         inodeId, suite, version, keyName);
+    if (encryptionZones == null) {
+      encryptionZones = new TreeMap<>();
+    }
     encryptionZones.put(inodeId, ez);
   }
 
@@ -153,8 +155,10 @@ void unprotectedAddEncryptionZone(Long inodeId,
    */
   void removeEncryptionZone(Long inodeId) {
     assert dir.hasWriteLock();
+    if (hasCreatedEncryptionZone()) {
       encryptionZones.remove(inodeId);
     }
+  }
 
   /**
    * Returns true if an IIP is within an encryption zone.
@@ -201,6 +205,9 @@ String getKeyName(final INodesInPath iip) {
   private EncryptionZoneInt getEncryptionZoneForPath(INodesInPath iip) {
     assert dir.hasReadLock();
     Preconditions.checkNotNull(iip);
+    if (!hasCreatedEncryptionZone()) {
+      return null;
+    }
     List<INode> inodes = iip.getReadOnlyINodes();
     for (int i = inodes.size() - 1; i >= 0; i--) {
       final INode inode = inodes.get(i);
@@ -313,7 +320,8 @@ XAttr createEncryptionZone(String src, CipherSuite suite,
       throw new IOException("Attempt to create an encryption zone for a file.");
     }
 
-    if (encryptionZones.get(srcINode.getId()) != null) {
+    if (hasCreatedEncryptionZone() && encryptionZones.
+        get(srcINode.getId()) != null) {
       throw new IOException("Directory " + src + " is already an encryption " +
           "zone.");
     }
@@ -340,6 +348,10 @@ XAttr createEncryptionZone(String src, CipherSuite suite,
   BatchedListEntries<EncryptionZone> listEncryptionZones(long prevId)
       throws IOException {
     assert dir.hasReadLock();
+    if (!hasCreatedEncryptionZone()) {
+      final List<EncryptionZone> emptyZones = Lists.newArrayList();
+      return new BatchedListEntries<EncryptionZone>(emptyZones, false);
+    }
     NavigableMap<Long, EncryptionZoneInt> tailMap = encryptionZones.tailMap
         (prevId, false);
     final int numResponses = Math.min(maxListEncryptionZonesResponses,
@@ -379,7 +391,18 @@ BatchedListEntries<EncryptionZone> listEncryptionZones(long prevId)
    * @return number of encryption zones.
    */
   public int getNumEncryptionZones() {
-    return encryptionZones.size();
+    return hasCreatedEncryptionZone() ?
+        encryptionZones.size() : 0;
+  }
+
+  /**
+   * @return Whether there has been any attempt to create an encryption zone in
+   * the cluster at all. If not, it is safe to quickly return null when
+   * checking the encryption information of any file or directory in the
+   * cluster.
+   */
+  public boolean hasCreatedEncryptionZone() {
+    return encryptionZones != null;
   }
 
   /**
@@ -387,6 +410,9 @@ public int getNumEncryptionZones() {
    */
   String[] getKeyNames() {
     assert dir.hasReadLock();
+    if (!hasCreatedEncryptionZone()) {
+      return new String[0];
+    }
     String[] ret = new String[encryptionZones.size()];
     int index = 0;
     for (Map.Entry<Long, EncryptionZoneInt> entry : encryptionZones

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

@@ -254,7 +254,7 @@ static void setFileEncryptionInfo(final FSDirectory fsd, final String src,
   static FileEncryptionInfo getFileEncryptionInfo(final FSDirectory fsd,
       final INode inode, final int snapshotId, final INodesInPath iip)
       throws IOException {
-    if (!inode.isFile()) {
+    if (!inode.isFile() || !fsd.ezManager.hasCreatedEncryptionZone()) {
       return null;
     }
     fsd.readLock();