[jira] [Commented] (HDFS-16816) RBF: auto-create user home dir for trash paths by router

["ASF GitHub Bot (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HDFS-16816?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17623306#comment-17623306 ] 

ASF GitHub Bot commented on HDFS-16816:
---------------------------------------

mkuchenbecker commented on code in PR #5071:
URL: https://github.com/apache/hadoop/pull/5071#discussion_r1003591256


##########
hadoop-hdfs-project/hadoop-hdfs-rbf/src/main/java/org/apache/hadoop/hdfs/server/federation/router/RouterClientProtocol.java:
##########
@@ -723,6 +723,49 @@ public boolean delete(String src, boolean recursive) throws IOException {
     }
   }
 
+  // Create missing user home dirs for trash paths.
+  // We assume the router is running with super-user privilege (can create
+  // user home dir in /user dir).
+  private void createUserHomeForTrashPath(List<RemoteLocation> locations) throws IOException {
+    List<RemoteLocation> missingUserHomes = new ArrayList<>();
+
+    // Identify missing trash roots
+    for(RemoteLocation loc: locations) {
+
+      String path = loc.getDest();
+      // Continue if not a trash path
+      if (!MountTableResolver.isTrashPath(path)) {
+        continue;
+      }
+
+      // Check whether user home dir exists at the destination namespace
+      String trashRoot = MountTableResolver.getTrashRoot();
+      String userHome = new Path(trashRoot).getParent().toUri().getPath();
+      RemoteLocation userHomeLoc = new RemoteLocation(loc, userHome);
+      RemoteMethod method = new RemoteMethod("getFileInfo", new Class<?>[] {String.class}, new RemoteParam());
+      HdfsFileStatus ret = rpcClient.invokeSingle(userHomeLoc, method, HdfsFileStatus.class);
+      if (ret == null) {
+        missingUserHomes.add(userHomeLoc);
+      }
+    }
+
+    if (!missingUserHomes.isEmpty()) {

Review Comment:
   Is this logic correct? When missingUserHomes is populated once while looping through locations this will always be true. 
   
   Should this instead be in a separate loop over missingUserHomes?





> RBF: auto-create user home dir for trash paths by router
> --------------------------------------------------------
>
>                 Key: HDFS-16816
>                 URL: https://issues.apache.org/jira/browse/HDFS-16816
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>          Components: rbf
>            Reporter: Xing Lin
>            Priority: Minor
>
> In RBF, trash files are moved to trash root under user's home dir at the corresponding namespace/namenode where the files reside. This was added in HDFS-16024. When the user home dir is not created before-hand at a namenode, we run into permission denied exceptions when trying to create the parent dir for the trash file before moving the file into it. We propose to enhance Router, to auto-create a user home's dir at the namenode for trash paths, using router's identity (which is assumed to be a super-user).



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