HDFS-17855. ViewFS with linkMergeSlash generates invalid paths during listStatus/listLocatedStatus operations, causing InvalidPathException or incorrect path resolution

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/viewfs/InodeTree.java

@@ -719,7 +719,7 @@ protected InodeTree(final Configuration config, final String viewName,
 
     if (isMergeSlashConfigured) {
       Preconditions.checkNotNull(mergeSlashTarget);
-      root = new INodeLink<T>(mountTableName, ugi,
+      root = new INodeLink<T>("/", ugi,
           initAndGetTargetFs(), mergeSlashTarget);
       mountPoints.add(new MountPoint<T>("/", (INodeLink<T>) root));
       rootFallbackLink = null;

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/fs/viewfs/TestViewFileSystemLinkMergeSlash.java

@@ -28,7 +28,9 @@
 import org.apache.hadoop.fs.FileSystem;
 import org.apache.hadoop.fs.FileSystemTestHelper;
 import org.apache.hadoop.fs.FsConstants;
+import org.apache.hadoop.fs.LocatedFileStatus;
 import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.fs.RemoteIterator;
 import org.apache.hadoop.hdfs.DFSConfigKeys;
 import org.apache.hadoop.hdfs.DistributedFileSystem;
 import org.apache.hadoop.hdfs.MiniDFSCluster;
@@ -42,6 +44,7 @@
 import org.slf4j.LoggerFactory;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 import static org.junit.jupiter.api.Assertions.fail;
 
@@ -228,4 +231,136 @@ public void testChildFileSystems() throws Exception {
     assertEquals(DistributedFileSystem.class, childFs[0].getClass(),
         "Unexpected child filesystem!");
   }
+
+  @Test
+  public void testListStatusReturnsCorrectPaths() throws Exception {
+    String clusterName = "ClusterLMS1";
+    URI viewFsUri = new URI(FsConstants.VIEWFS_SCHEME, clusterName,
+        "/", null, null);
+
+    Configuration conf = new Configuration();
+    ConfigUtil.addLinkMergeSlash(conf, clusterName,
+        fsDefault.getUri());
+
+    FileSystem vfs = FileSystem.get(viewFsUri, conf);
+
+    // Create test directory structure
+    Path testDir = new Path("/testListStatus");
+    Path subDir1 = new Path(testDir, "subdir1");
+    Path subDir2 = new Path(testDir, "subdir2");
+    Path file1 = new Path(testDir, "file1.txt");
+
+    try {
+      fsDefault.mkdirs(subDir1);
+      fsDefault.mkdirs(subDir2);
+      fsDefault.create(file1).close();
+
+      // Test listStatus returns correct ViewFS paths
+      FileStatus[] statuses = vfs.listStatus(testDir);
+      assertEquals(3, statuses.length, "Should have 3 items");
+
+      for (FileStatus status : statuses) {
+        Path path = status.getPath();
+        // Path should be viewfs:// URI, not hdfs://
+        assertEquals(FsConstants.VIEWFS_SCHEME, path.toUri().getScheme(),
+            "Scheme should be viewfs");
+        assertEquals(clusterName, path.toUri().getAuthority(),
+            "Authority should match cluster name");
+        // Path should start with /testListStatus, not contain cluster name
+        assertTrue(path.toString().startsWith("viewfs://" + clusterName + "/testListStatus/"),
+            "Path should be absolute and correct: " + path);
+        assertFalse(path.toString().contains(clusterName + "/" + clusterName),
+            "Path should not contain duplicate cluster name: " + path);
+      }
+    } finally {
+      fsDefault.delete(testDir, true);
+      vfs.close();
+    }
+  }
+
+  @Test
+  public void testListLocatedStatusReturnsCorrectPaths() throws Exception {
+    String clusterName = "ClusterLMS1";
+    URI viewFsUri = new URI(FsConstants.VIEWFS_SCHEME, clusterName,
+        "/", null, null);
+
+    Configuration conf = new Configuration();
+    ConfigUtil.addLinkMergeSlash(conf, clusterName,
+        fsDefault.getUri());
+
+    FileSystem vfs = FileSystem.get(viewFsUri, conf);
+
+    // Create test directory structure
+    Path testDir = new Path("/testListLocatedStatus");
+    Path file1 = new Path(testDir, "file1.txt");
+    Path file2 = new Path(testDir, "file2.txt");
+
+    try {
+      fsDefault.mkdirs(testDir);
+      fsDefault.create(file1).close();
+      fsDefault.create(file2).close();
+
+      // Test listLocatedStatus returns correct ViewFS paths
+      RemoteIterator<LocatedFileStatus> iter = vfs.listLocatedStatus(testDir);
+      int count = 0;
+      while (iter.hasNext()) {
+        LocatedFileStatus status = iter.next();
+        Path path = status.getPath();
+        count++;
+
+        // Path should be viewfs:// URI
+        assertEquals(FsConstants.VIEWFS_SCHEME, path.toUri().getScheme(),
+            "Scheme should be viewfs");
+        assertEquals(clusterName, path.toUri().getAuthority(),
+            "Authority should match cluster name");
+        // Path should be absolute and not contain relative path issues
+        assertTrue(path.toString().startsWith("viewfs://" + clusterName + "/testListLocatedStatus/"),
+            "Path should start correctly: " + path);
+        assertFalse(path.toString().contains(clusterName + "/" + clusterName),
+            "Path should not contain duplicate cluster name: " + path);
+      }
+      assertEquals(2, count, "Should have 2 files");
+    } finally {
+      fsDefault.delete(testDir, true);
+      vfs.close();
+    }
+  }
+
+  @Test
+  public void testResolvedPathIsAbsolute() throws Exception {
+    String clusterName = "ClusterLMS1";
+    URI viewFsUri = new URI(FsConstants.VIEWFS_SCHEME, clusterName,
+        "/", null, null);
+
+    Configuration conf = new Configuration();
+    ConfigUtil.addLinkMergeSlash(conf, clusterName,
+        fsDefault.getUri());
+
+    FileSystem vfs = FileSystem.get(viewFsUri, conf);
+
+    // Create nested directory structure
+    Path baseDir = new Path("/user/history/done");
+    Path yearDir = new Path(baseDir, "2021");
+
+    try {
+      fsDefault.mkdirs(yearDir);
+
+      // This is the exact scenario that caused the bug
+      FileStatus[] statuses = vfs.listStatus(baseDir);
+      assertEquals(1, statuses.length, "Should have 1 directory");
+
+      Path resultPath = statuses[0].getPath();
+      String expectedPath = "viewfs://" + clusterName + "/user/history/done/2021";
+      assertEquals(expectedPath, resultPath.toString(),
+          "Path should be correctly formed");
+
+      // Verify path is absolute (starts with /)
+      assertTrue(resultPath.toUri().getPath().startsWith("/"),
+          "Path should be absolute");
+    } finally {
+      fsDefault.delete(new Path("/user"), true);
+      vfs.close();
+    }
+  }
 }
+