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Date: Mon, 3 Oct 2016 17:51:20 +0000 (UTC)
From: "Karthik Palaniappan (JIRA)" <jira@apache.org>
To: hdfs-dev@hadoop.apache.org
Message-ID: <JIRA.13009288.1475517056000.723070.1475517080645@Atlassian.JIRA>
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References: <JIRA.13009288.1475517056000@Atlassian.JIRA> <JIRA.13009288.1475517056164@arcas>
Subject: [jira] [Created] (HDFS-10948) HDFS setOwner no-op should not
 generate an edit log transaction
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archived-at: Mon, 03 Oct 2016 17:51:23 -0000

Karthik Palaniappan created HDFS-10948:
------------------------------------------

             Summary: HDFS setOwner no-op should not generate an edit log transaction
                 Key: HDFS-10948
                 URL: https://issues.apache.org/jira/browse/HDFS-10948
             Project: Hadoop HDFS
          Issue Type: Bug
          Components: hdfs
    Affects Versions: 2.7.0
            Reporter: Karthik Palaniappan
            Priority: Minor


The HDFS setOwner RPC takes a path, optional username, and optional groupname (see ClientNamenodeProtocol.proto). If neither username nor groupname are set, the RPC is a no-op. However, an entry in the edit log is still committed, and when retrieved through getEditsFromTxid, both username and groupname are set to the empty string.

This does not match the behavior of the setTimes RPC. There atime and mtime are both required, and you can set "-1" to indicated "don't change the time". If both are set to "-1", the RPC is a no-op, and appropriately no edit log transaction is created.

Here's an example of an (untested) patch to fix the issue:

```
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSDirAttrOp.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSDirAttrOp.java
index 3dc1c30..0728bc5 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSDirAttrOp.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSDirAttrOp.java
@@ -77,6 +77,7 @@ static HdfsFileStatus setOwner(
     if (FSDirectory.isExactReservedName(src)) {
       throw new InvalidPathException(src);
     }
+    boolean changed = false;
     FSPermissionChecker pc = fsd.getPermissionChecker();
     INodesInPath iip;
     fsd.writeLock();
@@ -92,11 +93,13 @@ static HdfsFileStatus setOwner(
           throw new AccessControlException("User does not belong to " + group);
         }
       }
-      unprotectedSetOwner(fsd, src, username, group);
+      changed = unprotectedSetOwner(fsd, src, username, group);
     } finally {
       fsd.writeUnlock();
     }
-    fsd.getEditLog().logSetOwner(src, username, group);
+    if (changed) {
+      fsd.getEditLog().logSetOwner(src, username, group);
+    }
     return fsd.getAuditFileInfo(iip);
   }
 
@@ -287,22 +290,27 @@ static void unprotectedSetPermission(
     inode.setPermission(permissions, snapshotId);
   }
 
-  static void unprotectedSetOwner(
+  static boolean unprotectedSetOwner(
       FSDirectory fsd, String src, String username, String groupname)
       throws FileNotFoundException, UnresolvedLinkException,
       QuotaExceededException, SnapshotAccessControlException {
     assert fsd.hasWriteLock();
+    boolean status = false;
     final INodesInPath inodesInPath = fsd.getINodesInPath4Write(src, true);
     INode inode = inodesInPath.getLastINode();
     if (inode == null) {
       throw new FileNotFoundException("File does not exist: " + src);
     }
     if (username != null) {
+      status = true;
       inode = inode.setUser(username, inodesInPath.getLatestSnapshotId());
     }
     if (groupname != null) {
+      status = true;
       inode.setGroup(groupname, inodesInPath.getLatestSnapshotId());
     }
+
+    return status;
   }
 
   static boolean setTimes(
```


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