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From weic...@apache.org
Subject [hadoop] branch branch-2.10 updated: HDFS-13901. INode access time is ignored because of race between open and rename. Contributed by Jinglun.
Date Tue, 22 Oct 2019 23:50:11 GMT
This is an automated email from the ASF dual-hosted git repository.

weichiu pushed a commit to branch branch-2.10
in repository https://gitbox.apache.org/repos/asf/hadoop.git


The following commit(s) were added to refs/heads/branch-2.10 by this push:
     new 2b35153  HDFS-13901. INode access time is ignored because of race between open and
rename. Contributed by Jinglun.
2b35153 is described below

commit 2b351536e22aeb990016cf387ec27df2d1275a5e
Author: Wei-Chiu Chuang <weichiu@apache.org>
AuthorDate: Tue Oct 22 16:43:25 2019 -0700

    HDFS-13901. INode access time is ignored because of race between open and rename. Contributed
by Jinglun.
    
    (cherry picked from commit a805d80ebe3b1683049119d3d19e8b085141e3cf)
---
 .../server/namenode/FSDirStatAndListingOp.java     |  9 ++-
 .../hadoop/hdfs/server/namenode/FSNamesystem.java  | 36 +++-------
 .../apache/hadoop/hdfs/server/namenode/INode.java  | 12 ++++
 .../hdfs/server/namenode/TestDeleteRace.java       | 76 ++++++++++++++++++++++
 4 files changed, 105 insertions(+), 28 deletions(-)

diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSDirStatAndListingOp.java
b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSDirStatAndListingOp.java
index 4ada2be..fe0e85f 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSDirStatAndListingOp.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSDirStatAndListingOp.java
@@ -176,7 +176,7 @@ class FSDirStatAndListingOp {
       boolean updateAccessTime = fsd.isAccessTimeSupported()
           && !iip.isSnapshot()
           && now > inode.getAccessTime() + fsd.getAccessTimePrecision();
-      return new GetBlockLocationsResult(updateAccessTime, blocks);
+      return new GetBlockLocationsResult(updateAccessTime, blocks, iip);
     } finally {
       fsd.readUnlock();
     }
@@ -566,13 +566,18 @@ class FSDirStatAndListingOp {
   static class GetBlockLocationsResult {
     final boolean updateAccessTime;
     final LocatedBlocks blocks;
+    private final INodesInPath iip;
     boolean updateAccessTime() {
       return updateAccessTime;
     }
+    public INodesInPath getIIp() {
+      return iip;
+    }
     private GetBlockLocationsResult(
-        boolean updateAccessTime, LocatedBlocks blocks) {
+        boolean updateAccessTime, LocatedBlocks blocks, INodesInPath iip) {
       this.updateAccessTime = updateAccessTime;
       this.blocks = blocks;
+      this.iip = iip;
     }
   }
 }
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 fe84ebd..3536433 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
@@ -1836,11 +1836,13 @@ public class FSNamesystem implements Namesystem, FSNamesystemMBean,
     checkOperation(OperationCategory.READ);
     GetBlockLocationsResult res = null;
     FSPermissionChecker pc = getPermissionChecker();
+    final INode inode;
     readLock();
     try {
       checkOperation(OperationCategory.READ);
       res = FSDirStatAndListingOp.getBlockLocations(
           dir, pc, srcArg, offset, length, true);
+      inode = res.getIIp().getLastINode();
       if (isInSafeMode()) {
         for (LocatedBlock b : res.blocks.getLocatedBlocks()) {
           // if safemode & no block locations yet then throw safemodeException
@@ -1881,34 +1883,16 @@ public class FSNamesystem implements Namesystem, FSNamesystemMBean,
       final long now = now();
       try {
         checkOperation(OperationCategory.WRITE);
-        /**
-         * Resolve the path again and update the atime only when the file
-         * exists.
-         *
-         * XXX: Races can still occur even after resolving the path again.
-         * For example:
-         *
-         * <ul>
-         *   <li>Get the block location for "/a/b"</li>
-         *   <li>Rename "/a/b" to "/c/b"</li>
-         *   <li>The second resolution still points to "/a/b", which is
-         *   wrong.</li>
-         * </ul>
-         *
-         * The behavior is incorrect but consistent with the one before
-         * HDFS-7463. A better fix is to change the edit log of SetTime to
-         * use inode id instead of a path.
-         */
-        final INodesInPath iip = dir.resolvePath(pc, srcArg, DirOp.READ);
-        src = iip.getPath();
-
-        INode inode = iip.getLastINode();
-        boolean updateAccessTime = inode != null &&
+        boolean updateAccessTime =
             now > inode.getAccessTime() + dir.getAccessTimePrecision();
         if (!isInSafeMode() && updateAccessTime) {
-          boolean changed = FSDirAttrOp.setTimes(dir, iip, -1, now, false);
-          if (changed) {
-            getEditLog().logTimes(src, -1, now);
+          if (!inode.isDeleted()) {
+            src = inode.getFullPathName();
+            final INodesInPath iip = dir.resolvePath(pc, src, DirOp.READ);
+            boolean changed = FSDirAttrOp.setTimes(dir, iip, -1, now, false);
+            if (changed) {
+              getEditLog().logTimes(src, -1, now);
+            }
           }
         }
       } catch (Throwable e) {
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/INode.java
b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/INode.java
index 27c4244..1d2654e 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/INode.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/INode.java
@@ -600,6 +600,18 @@ public abstract class INode implements INodeAttributes, Diff.Element<byte[]>
{
     return DFSUtil.bytes2String(path);
   }
 
+  public boolean isDeleted() {
+    INode pInode = this;
+    while (pInode != null && !pInode.isRoot()) {
+      pInode = pInode.getParent();
+    }
+    if (pInode == null) {
+      return true;
+    } else {
+      return !pInode.isRoot();
+    }
+  }
+
   public byte[][] getPathComponents() {
     int n = 0;
     for (INode inode = this; inode != null; inode = inode.getParent()) {
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestDeleteRace.java
b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestDeleteRace.java
index a13574f..b581e8a 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestDeleteRace.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestDeleteRace.java
@@ -18,6 +18,7 @@
 package org.apache.hadoop.hdfs.server.namenode;
 
 import java.io.FileNotFoundException;
+import java.io.IOException;
 import java.util.AbstractMap;
 import java.util.ArrayList;
 import java.util.Comparator;
@@ -27,10 +28,13 @@ import java.util.List;
 import java.util.Map;
 import java.util.Set;
 import java.util.TreeSet;
+import java.util.concurrent.Semaphore;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.FileStatus;
+import org.apache.hadoop.fs.Options;
 import org.apache.hadoop.hdfs.AddBlockFlag;
 import org.apache.hadoop.fs.FSDataOutputStream;
 import org.apache.hadoop.fs.FileSystem;
@@ -66,6 +70,7 @@ import org.mockito.internal.util.reflection.Whitebox;
 
 import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_NAMENODE_LEASE_RECHECK_INTERVAL_MS_DEFAULT;
 import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_NAMENODE_LEASE_RECHECK_INTERVAL_MS_KEY;
+import static org.junit.Assert.assertNotEquals;
 
 /**
  * Test race between delete and other operations.  For now only addBlock()
@@ -442,4 +447,75 @@ public class TestDeleteRace {
       }
     }
   }
+
+  @Test(timeout = 20000)
+  public void testOpenRenameRace() throws Exception {
+    Configuration config = new Configuration();
+    config.setLong(DFSConfigKeys.DFS_NAMENODE_ACCESSTIME_PRECISION_KEY, 1);
+    MiniDFSCluster dfsCluster = null;
+    final String src = "/dir/src-file";
+    final String dst = "/dir/dst-file";
+    final DistributedFileSystem hdfs;
+    try {
+      dfsCluster = new MiniDFSCluster.Builder(config).build();
+      dfsCluster.waitActive();
+      final FSNamesystem fsn = dfsCluster.getNamesystem();
+      hdfs = dfsCluster.getFileSystem();
+      DFSTestUtil.createFile(hdfs, new Path(src), 5, (short) 1, 0xFEED);
+      FileStatus status = hdfs.getFileStatus(new Path(src));
+      long accessTime = status.getAccessTime();
+
+      final Semaphore openSem = new Semaphore(0);
+      final Semaphore renameSem = new Semaphore(0);
+      // 1.hold writeLock.
+      // 2.start open thread.
+      // 3.openSem & yield makes sure open thread wait on readLock.
+      // 4.start rename thread.
+      // 5.renameSem & yield makes sure rename thread wait on writeLock.
+      // 6.release writeLock, it's fair lock so open thread gets read lock.
+      // 7.open thread unlocks, rename gets write lock and does rename.
+      // 8.rename thread unlocks, open thread gets write lock and update time.
+      Thread open = new Thread(new Runnable() {
+        @Override public void run() {
+          try {
+            openSem.release();
+            fsn.getBlockLocations("foo", src, 0, 5);
+          } catch (IOException e) {
+          }
+        }
+      });
+      Thread rename = new Thread(new Runnable() {
+        @Override public void run() {
+          try {
+            openSem.acquire();
+            renameSem.release();
+            fsn.renameTo(src, dst, false, Options.Rename.NONE);
+          } catch (IOException e) {
+          } catch (InterruptedException e) {
+          }
+        }
+      });
+      fsn.writeLock();
+      open.start();
+      openSem.acquire();
+      Thread.yield();
+      openSem.release();
+      rename.start();
+      renameSem.acquire();
+      Thread.yield();
+      fsn.writeUnlock();
+
+      // wait open and rename threads finish.
+      open.join();
+      rename.join();
+
+      status = hdfs.getFileStatus(new Path(dst));
+      assertNotEquals(accessTime, status.getAccessTime());
+      dfsCluster.restartNameNode(0);
+    } finally {
+      if (dfsCluster != null) {
+        dfsCluster.shutdown();
+      }
+    }
+  }
 }


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