HDFS-14915. Move Superuser Check Before Taking Lock For Encryption API. Contributed by Ayush Saxena.

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

@@ -7437,10 +7437,10 @@ public class FSNamesystem implements Namesystem, FSNamesystemMBean,
       Metadata metadata = FSDirEncryptionZoneOp.ensureKeyIsInitialized(dir,
           keyName, src);
       final FSPermissionChecker pc = getPermissionChecker();
+      checkSuperuserPrivilege(pc);
       checkOperation(OperationCategory.WRITE);
       writeLock();
       try {
-        checkSuperuserPrivilege(pc);
         checkOperation(OperationCategory.WRITE);
         checkNameNodeSafeMode("Cannot create encryption zone on " + src);
         resultingStat = FSDirEncryptionZoneOp.createEncryptionZone(dir, src,
@@ -7496,10 +7496,10 @@ public class FSNamesystem implements Namesystem, FSNamesystemMBean,
     boolean success = false;
     checkOperation(OperationCategory.READ);
     final FSPermissionChecker pc = getPermissionChecker();
+    checkSuperuserPrivilege(pc);
     readLock();
     try {
       checkOperation(OperationCategory.READ);
-      checkSuperuserPrivilege(pc);
       final BatchedListEntries<EncryptionZone> ret =
           FSDirEncryptionZoneOp.listEncryptionZones(dir, prevId);
       success = true;
@@ -7533,10 +7533,10 @@ public class FSNamesystem implements Namesystem, FSNamesystemMBean,
     boolean success = false;
     checkOperation(OperationCategory.READ);
     final FSPermissionChecker pc = getPermissionChecker();
+    checkSuperuserPrivilege(pc);
     readLock();
     try {
       checkOperation(OperationCategory.READ);
-      checkSuperuserPrivilege(pc);
       final BatchedListEntries<ZoneReencryptionStatus> ret =
           FSDirEncryptionZoneOp.listReencryptionStatus(dir, prevId);
       success = true;
@@ -7567,7 +7567,6 @@ public class FSNamesystem implements Namesystem, FSNamesystemMBean,
     }
     writeLock();
     try {
-      checkSuperuserPrivilege(pc);
       checkOperation(OperationCategory.WRITE);
       checkNameNodeSafeMode("NameNode in safemode, cannot " + action
           + " re-encryption on zone " + zone);