From 8bf19a216cc667d817313c6f07510425dc1aa106 Mon Sep 17 00:00:00 2001
From: zeekling <lingzhaohui@zeekling.cn>
Date: Sun, 31 Mar 2024 21:39:21 +0800
Subject: [PATCH] =?UTF-8?q?=20=E5=A2=9E=E5=8A=A0hdfs=E4=BB=A3=E7=A0=81?=
 =?UTF-8?q?=E6=B3=A8=E9=87=8A?=
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---
 .../org/apache/hadoop/hdfs/server/namenode/FSDirectory.java    | 3 +++
 .../org/apache/hadoop/hdfs/server/namenode/FSNamesystem.java   | 1 +
 .../hadoop/hdfs/server/namenode/INodeAttributeProvider.java    | 1 +
 3 files changed, 5 insertions(+)

diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSDirectory.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSDirectory.java
index 37b368c31f..eb23a2a760 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSDirectory.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSDirectory.java
@@ -201,6 +201,9 @@ private static INodeDirectory createRoot(FSNamesystem namesystem) {
   private final String supergroup;
   private final INodeId inodeId;
 
+  /**
+   * 写editlog。
+   */
   private final FSEditLog editLog;
 
   private HdfsFileStatus[] reservedStatuses;
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystem.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystem.java
index 3267b6fc12..dd966b9e4d 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystem.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystem.java
@@ -1233,6 +1233,7 @@ private void loadFSImage(StartupOption startOpt) throws IOException {
     writeLock();
     try {
       // We shouldn't be calling saveNamespace if we've come up in standby state.
+      // 根据启动选项及其对应存储目录(${dfs.name.dir})，分析存储目录，必要的话从先前的事务恢复过来
       MetaRecoveryContext recovery = startOpt.createRecoveryContext();
       final boolean staleImage
           = fsImage.recoverTransitionRead(startOpt, this, recovery);
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/INodeAttributeProvider.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/INodeAttributeProvider.java
index e83c962a4a..c4834bcc25 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/INodeAttributeProvider.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/INodeAttributeProvider.java
@@ -34,6 +34,7 @@
 @InterfaceStability.Unstable
 public abstract class INodeAttributeProvider {
 
+  // 访问控制执行者接口
   public static class AuthorizationContext {
     private String fsOwner;
     private String supergroup;