HDFS-16204. Improve FSDirEncryptionZoneOp related parameter comments. (#3368)

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

@@ -75,7 +75,7 @@ final class FSDirEncryptionZoneOp {
    * Invoke KeyProvider APIs to generate an encrypted data encryption key for
    * an encryption zone. Should not be called with any locks held.
    *
-   * @param fsd fsdirectory
+   * @param fsd the namespace tree.
    * @param ezKeyName key name of an encryption zone
    * @return New EDEK, or null if ezKeyName is null
    * @throws IOException
@@ -142,11 +142,12 @@ final class FSDirEncryptionZoneOp {
   /**
    * Create an encryption zone on directory path using the specified key.
    *
-   * @param fsd fsdirectory
+   * @param fsd the namespace tree.
    * @param srcArg the path of a directory which will be the root of the
    *               encryption zone. The directory must be empty
    * @param pc permission checker to check fs permission
-   * @param cipher cipher
+   * @param cipher the name of the cipher suite, which will be used
+   *               when it is generated.
    * @param keyName name of a key which must be present in the configured
    *                KeyProvider
    * @param logRetryCache whether to record RPC ids in editlog for retry cache
@@ -180,7 +181,7 @@ final class FSDirEncryptionZoneOp {
   /**
    * Get the encryption zone for the specified path.
    *
-   * @param fsd fsdirectory
+   * @param fsd the namespace tree.
    * @param srcArg the path of a file or directory to get the EZ for
    * @param pc permission checker to check fs permission
    * @return the EZ with file status.
@@ -400,7 +401,7 @@ final class FSDirEncryptionZoneOp {
   /**
    * Set the FileEncryptionInfo for an INode.
    *
-   * @param fsd fsdirectory
+   * @param fsd the namespace tree.
    * @param info file encryption information
    * @param flag action when setting xattr. Either CREATE or REPLACE.
    * @throws IOException
@@ -430,7 +431,7 @@ final class FSDirEncryptionZoneOp {
    * returns a consolidated FileEncryptionInfo instance. Null is returned
    * for non-encrypted or raw files.
    *
-   * @param fsd fsdirectory
+   * @param fsd the namespace tree.
    * @param iip inodes in the path containing the file, passed in to
    *            avoid obtaining the list of inodes again
    * @return consolidated file encryption info; null for non-encrypted files
@@ -487,7 +488,7 @@ final class FSDirEncryptionZoneOp {
    * else throw a retry exception.  The startFile method generates the EDEK
    * outside of the lock so the zone must be reverified.
    *
-   * @param dir fsdirectory
+   * @param dir the namespace tree.
    * @param iip inodes in the file path
    * @param ezInfo the encryption key
    * @return FileEncryptionInfo for the file