HADOOP-18144: getTrashRoot in ViewFileSystem should return a path in ViewFS.

To get the new behavior, define fs.viewfs.trash.force-inside-mount-point to be true.

If the trash root for path p is in the same mount point as path p,
and one of:
* The mount point isn't at the top of the target fs.
* The resolved path of path is root (eg it is the fallback FS).
* The trash root isn't in user's target fs home directory.
get the corresponding viewFS path for the trash root and return it.
Otherwise, use <mnt>/.Trash/<user>.

Signed-off-by: Owen O'Malley <oomalley@linkedin.com>

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

@@ -191,8 +191,8 @@ public boolean moveToTrash(Path path) throws IOException {
         cause = e;
       }
     }
-    throw (IOException)
+    throw new IOException("Failed to move " + path + " to trash " + trashPath,
-      new IOException("Failed to move to trash: " + path).initCause(cause);
+        cause);
   }
 
   @SuppressWarnings("deprecation")

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

@@ -134,8 +134,9 @@ public interface Constants {
       HCFSMountTableConfigLoader.class;
 
   /**
-   * Enable ViewFileSystem to return a trashRoot which is local to mount point.
+   * Force ViewFileSystem to return a trashRoot that is inside a mount point.
    */
-  String CONFIG_VIEWFS_MOUNT_POINT_LOCAL_TRASH = "fs.viewfs.mount.point.local.trash";
+  String CONFIG_VIEWFS_TRASH_FORCE_INSIDE_MOUNT_POINT =
-  boolean CONFIG_VIEWFS_MOUNT_POINT_LOCAL_TRASH_DEFAULT = false;
+      "fs.viewfs.trash.force-inside-mount-point";
+  boolean CONFIG_VIEWFS_TRASH_FORCE_INSIDE_MOUNT_POINT_DEFAULT = false;
 }

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

@@ -25,8 +25,8 @@
 import static org.apache.hadoop.fs.viewfs.Constants.CONFIG_VIEWFS_MOUNT_LINKS_AS_SYMLINKS;
 import static org.apache.hadoop.fs.viewfs.Constants.CONFIG_VIEWFS_MOUNT_LINKS_AS_SYMLINKS_DEFAULT;
 import static org.apache.hadoop.fs.viewfs.Constants.PERMISSION_555;
-import static org.apache.hadoop.fs.viewfs.Constants.CONFIG_VIEWFS_MOUNT_POINT_LOCAL_TRASH;
+import static org.apache.hadoop.fs.viewfs.Constants.CONFIG_VIEWFS_TRASH_FORCE_INSIDE_MOUNT_POINT;
-import static org.apache.hadoop.fs.viewfs.Constants.CONFIG_VIEWFS_MOUNT_POINT_LOCAL_TRASH_DEFAULT;
+import static org.apache.hadoop.fs.viewfs.Constants.CONFIG_VIEWFS_TRASH_FORCE_INSIDE_MOUNT_POINT_DEFAULT;
 
 import java.util.function.Function;
 import java.io.FileNotFoundException;
@@ -1132,47 +1132,77 @@ public Collection<? extends BlockStoragePolicySpi> getAllStoragePolicies()
    * Get the trash root directory for current user when the path
    * specified is deleted.
    *
-   * If CONFIG_VIEWFS_MOUNT_POINT_LOCAL_TRASH is not set, return
+   * If FORCE_INSIDE_MOUNT_POINT flag is not set, return the default trash root
-   * the default trash root from targetFS.
+   * from targetFS.
    *
-   * When CONFIG_VIEWFS_MOUNT_POINT_LOCAL_TRASH is set to true,
+   * When FORCE_INSIDE_MOUNT_POINT is set to true,
-   * 1) If path p is in fallback FS or from the same mount point as the default
+   * <ol>
-   *    trash root for targetFS, return the default trash root for targetFS.
+   *   <li>
-   * 2) else, return a trash root in the mounted targetFS
+   *     If the trash root for path p is in the same mount point as path p,
-   *    (/mntpoint/.Trash/{user})
+   *       and one of:
+   *       <ol>
+   *         <li>The mount point isn't at the top of the target fs.</li>
+   *         <li>The resolved path of path is root (in fallback FS).</li>
+   *         <li>The trash isn't in user's target fs home directory
+   *            get the corresponding viewFS path for the trash root and return
+   *            it.
+   *         </li>
+   *       </ol>
+   *   </li>
+   *   <li>
+   *     else, return the trash root under the root of the mount point
+   *     (/{mntpoint}/.Trash/{user}).
+   *   </li>
+   * </ol>
+   *
+   * These conditions handle several different important cases:
+   * <ul>
+   *   <li>File systems may need to have more local trash roots, such as
+   *         encryption zones or snapshot roots.</li>
+   *   <li>The fallback mount should use the user's home directory.</li>
+   *   <li>Cloud storage systems should not use trash in an implicity defined
+   *        home directory, per a container, unless it is the fallback fs.</li>
+   * </ul>
    *
    * @param path the trash root of the path to be determined.
    * @return the trash root path.
    */
   @Override
   public Path getTrashRoot(Path path) {
-    boolean useMountPointLocalTrash =
-        config.getBoolean(CONFIG_VIEWFS_MOUNT_POINT_LOCAL_TRASH,
-            CONFIG_VIEWFS_MOUNT_POINT_LOCAL_TRASH_DEFAULT);
 
     try {
       InodeTree.ResolveResult<FileSystem> res =
           fsState.resolve(getUriPath(path), true);
+      Path targetFSTrashRoot =
+          res.targetFileSystem.getTrashRoot(res.remainingPath);
 
-      Path trashRoot = res.targetFileSystem.getTrashRoot(res.remainingPath);
+      // Allow clients to use old behavior of delegating to target fs.
-      if (!useMountPointLocalTrash) {
+      if (!config.getBoolean(CONFIG_VIEWFS_TRASH_FORCE_INSIDE_MOUNT_POINT,
-        return trashRoot;
+          CONFIG_VIEWFS_TRASH_FORCE_INSIDE_MOUNT_POINT_DEFAULT)) {
+        return targetFSTrashRoot;
+      }
+
+      // The trash root path from the target fs
+      String targetFSTrashRootPath = targetFSTrashRoot.toUri().getPath();
+      // The mount point path in the target fs
+      String mountTargetPath = res.targetFileSystem.getUri().getPath();
+      if (!mountTargetPath.endsWith("/")) {
+        mountTargetPath = mountTargetPath + "/";
+      }
+
+      Path targetFsUserHome = res.targetFileSystem.getHomeDirectory();
+      if (targetFSTrashRootPath.startsWith(mountTargetPath) &&
+          !(mountTargetPath.equals(ROOT_PATH.toString()) &&
+              !res.resolvedPath.equals(ROOT_PATH.toString()) &&
+              (targetFsUserHome != null && targetFSTrashRootPath.startsWith(
+                  targetFsUserHome.toUri().getPath())))) {
+        String relativeTrashRoot =
+            targetFSTrashRootPath.substring(mountTargetPath.length());
+        return makeQualified(new Path(res.resolvedPath, relativeTrashRoot));
       } else {
-        // Path p is either in a mount point or in the fallback FS
+        // Return the trash root for the mount point.
-
+        return makeQualified(new Path(res.resolvedPath,
-        if (ROOT_PATH.equals(new Path(res.resolvedPath))
+            TRASH_PREFIX + "/" + ugi.getShortUserName()));
-            || trashRoot.toUri().getPath().startsWith(res.resolvedPath)) {
-          // Path p is in the fallback FS or targetFileSystem.trashRoot is in
-          // the same mount point as Path p
-          return trashRoot;
-        } else {
-          // targetFileSystem.trashRoot is in a different mount point from
-          // Path p. Return the trash root for the mount point.
-          Path mountPointRoot =
-              res.targetFileSystem.getFileStatus(new Path("/")).getPath();
-          return new Path(mountPointRoot,
-              TRASH_PREFIX + "/" + ugi.getShortUserName());
-        }
       }
     } catch (IOException | IllegalArgumentException e) {
       throw new NotInMountpointException(path, "getTrashRoot");
@@ -1182,72 +1212,78 @@ public Path getTrashRoot(Path path) {
   /**
    * Get all the trash roots for current user or all users.
    *
+   * When FORCE_INSIDE_MOUNT_POINT is set to true, we also return trash roots
+   * under the root of each mount point, with their viewFS paths.
+   *
    * @param allUsers return trash roots for all users if true.
    * @return all Trash root directories.
    */
   @Override
   public Collection<FileStatus> getTrashRoots(boolean allUsers) {
-    List<FileStatus> trashRoots = new ArrayList<>();
+    // A map from targetFSPath -> FileStatus.
+    // FileStatus can be from targetFS or viewFS.
+    HashMap<Path, FileStatus> trashRoots = new HashMap<>();
     for (FileSystem fs : getChildFileSystems()) {
-      trashRoots.addAll(fs.getTrashRoots(allUsers));
+      for (FileStatus trash : fs.getTrashRoots(allUsers)) {
+        trashRoots.put(trash.getPath(), trash);
+      }
     }
 
-    // Add trash dirs for each mount point
+    // Return trashRoots if FORCE_INSIDE_MOUNT_POINT is disabled.
-    boolean useMountPointLocalTrash =
+    if (!config.getBoolean(CONFIG_VIEWFS_TRASH_FORCE_INSIDE_MOUNT_POINT,
-        config.getBoolean(CONFIG_VIEWFS_MOUNT_POINT_LOCAL_TRASH,
+        CONFIG_VIEWFS_TRASH_FORCE_INSIDE_MOUNT_POINT_DEFAULT)) {
-            CONFIG_VIEWFS_MOUNT_POINT_LOCAL_TRASH_DEFAULT);
+      return trashRoots.values();
-    if (useMountPointLocalTrash) {
+    }
 
-      Set<Path> currentTrashPaths = new HashSet<>();
+    // Get trash roots in TRASH_PREFIX dir inside mount points and fallback FS.
-      for (FileStatus file : trashRoots) {
+    List<InodeTree.MountPoint<FileSystem>> mountPoints =
-        currentTrashPaths.add(file.getPath());
+        fsState.getMountPoints();
-      }
+    // If we have a fallback FS, add a mount point for it as <"", fallback FS>.
+    // The source path of a mount point shall not end with '/', thus for
+    // fallback fs, we set its mount point src as "".
+    if (fsState.getRootFallbackLink() != null) {
+      mountPoints.add(new InodeTree.MountPoint<>("",
+          fsState.getRootFallbackLink()));
+    }
 
-      MountPoint[] mountPoints = getMountPoints();
+    try {
-      try {
+      for (InodeTree.MountPoint<FileSystem> mountPoint : mountPoints) {
-        for (int i = 0; i < mountPoints.length; i++) {
-          Path trashRoot = makeQualified(
-              new Path(mountPoints[i].mountedOnPath + "/" + TRASH_PREFIX));
 
-          // Continue if trashRoot does not exist for this filesystem
+        Path trashRoot =
-          if (!exists(trashRoot)) {
+            makeQualified(new Path(mountPoint.src + "/" + TRASH_PREFIX));
-            continue;
+
+        // Continue if trashRoot does not exist for this mount point
+        if (!exists(trashRoot)) {
+          continue;
+        }
+
+        FileSystem targetFS = mountPoint.target.getTargetFileSystem();
+        if (!allUsers) {
+          Path userTrashRoot = new Path(trashRoot, ugi.getShortUserName());
+          if (exists(userTrashRoot)) {
+            Path targetFSUserTrashRoot = targetFS.makeQualified(
+                new Path(targetFS.getUri().getPath(),
+                    TRASH_PREFIX + "/" + ugi.getShortUserName()));
+            trashRoots.put(targetFSUserTrashRoot, getFileStatus(userTrashRoot));
           }
-
+        } else {
-          InodeTree.ResolveResult<FileSystem> res =
+          FileStatus[] mountPointTrashRoots = listStatus(trashRoot);
-              fsState.resolve(getUriPath(trashRoot), true);
+          for (FileStatus trash : mountPointTrashRoots) {
-
+            // Remove the mountPoint and the leading '/' to get the
-          if (!allUsers) {
+            // relative targetFsTrash path
-            Path userTrash =
+            String targetFsTrash = trash.getPath().toUri().getPath()
-                new Path("/" + TRASH_PREFIX + "/" + ugi.getShortUserName());
+                .substring(mountPoint.src.length() + 1);
-            try {
+            Path targetFsTrashPath = targetFS.makeQualified(
-              FileStatus file = res.targetFileSystem.getFileStatus(userTrash);
+                new Path(targetFS.getUri().getPath(), targetFsTrash));
-              if (!currentTrashPaths.contains(file.getPath())) {
+            trashRoots.put(targetFsTrashPath, trash);
-                trashRoots.add(file);
-                currentTrashPaths.add(file.getPath());
-              }
-            } catch (FileNotFoundException ignored) {
-            }
-          } else {
-            FileStatus[] targetFsTrashRoots =
-                res.targetFileSystem.listStatus(new Path("/" + TRASH_PREFIX));
-            for (FileStatus file : targetFsTrashRoots) {
-              // skip if we already include it in currentTrashPaths
-              if (currentTrashPaths.contains(file.getPath())) {
-                continue;
-              }
-
-              trashRoots.add(file);
-              currentTrashPaths.add(file.getPath());
-            }
           }
         }
-      } catch (IOException e) {
-        LOG.warn("Exception in get all trash roots", e);
       }
+    } catch (IOException e) {
+      LOG.warn("Exception in get all trash roots for mount points", e);
     }
 
-    return trashRoots;
+    return trashRoots.values();
   }
 
   @Override

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/fs/viewfs/TestViewFileSystemLocalFileSystem.java

@@ -33,6 +33,8 @@
 import org.apache.hadoop.fs.FileStatus;
 import org.apache.hadoop.fs.FileSystem;
 import org.apache.hadoop.fs.Path;
+import static org.apache.hadoop.fs.FileSystem.TRASH_PREFIX;
+import org.apache.hadoop.security.UserGroupInformation;
 
 import org.junit.After;
 import org.junit.Before;
@@ -61,6 +63,13 @@ public void setUp() throws Exception {
     
   }
 
+  @Override
+  Path getTrashRootInFallBackFS() throws IOException {
+    return new Path(
+        "/" + TRASH_PREFIX + "/" + UserGroupInformation.getCurrentUser()
+            .getShortUserName());
+  }
+
   @Test
   public void testNflyWriteSimple() throws IOException {
     LOG.info("Starting testNflyWriteSimple");

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/fs/viewfs/TestViewFileSystemWithAuthorityLocalFileSystem.java

@@ -25,6 +25,9 @@
 import org.apache.hadoop.fs.FileSystemTestHelper;
 import org.apache.hadoop.fs.FsConstants;
 import org.apache.hadoop.fs.Path;
+import static org.apache.hadoop.fs.FileSystem.TRASH_PREFIX;
+import org.apache.hadoop.security.UserGroupInformation;
+import java.io.IOException;
 
 import org.junit.After;
 import org.junit.Assert;
@@ -63,6 +66,13 @@ public void tearDown() throws Exception {
     super.tearDown();
   }
  
+  @Override
+  Path getTrashRootInFallBackFS() throws IOException {
+    return new Path(
+        "/" + TRASH_PREFIX + "/" + UserGroupInformation.getCurrentUser()
+            .getShortUserName());
+  }
+
   @Override
   @Test
   public void testBasicPaths() {

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/fs/viewfs/ViewFileSystemBaseTest.java

@@ -69,7 +69,7 @@
 import static org.apache.hadoop.fs.FileSystemTestHelper.*;
 import static org.apache.hadoop.fs.viewfs.Constants.CONFIG_VIEWFS_ENABLE_INNER_CACHE;
 import static org.apache.hadoop.fs.viewfs.Constants.PERMISSION_555;
-import static org.apache.hadoop.fs.viewfs.Constants.CONFIG_VIEWFS_MOUNT_POINT_LOCAL_TRASH;
+import static org.apache.hadoop.fs.viewfs.Constants.CONFIG_VIEWFS_TRASH_FORCE_INSIDE_MOUNT_POINT;
 import static org.apache.hadoop.fs.FileSystem.TRASH_PREFIX;
 
 import org.junit.After;
@@ -1104,35 +1104,46 @@ public void testTrashRoot() throws IOException {
     Assert.assertTrue("", fsView.getTrashRoots(true).size() > 0);
   }
 
+  // Default implementation of getTrashRoot for a fallback FS mounted at root:
+  // e.g., fallbackFS.uri.getPath = '/'
+  Path getTrashRootInFallBackFS() throws IOException {
+    return new Path(fsTarget.getHomeDirectory().toUri().getPath(),
+        TRASH_PREFIX);
+  }
+
   /**
-   * Test the localized trash root for getTrashRoot.
+   * Test TRASH_FORCE_INSIDE_MOUNT_POINT feature for getTrashRoot.
    */
   @Test
-  public void testTrashRootLocalizedTrash() throws IOException {
+  public void testTrashRootForceInsideMountPoint() throws IOException {
     UserGroupInformation ugi = UserGroupInformation.getCurrentUser();
     Configuration conf2 = new Configuration(conf);
-    conf2.setBoolean(CONFIG_VIEWFS_MOUNT_POINT_LOCAL_TRASH, true);
+    conf2.setBoolean(CONFIG_VIEWFS_TRASH_FORCE_INSIDE_MOUNT_POINT, true);
     ConfigUtil.addLinkFallback(conf2, targetTestRoot.toUri());
     FileSystem fsView2 = FileSystem.get(FsConstants.VIEWFS_URI, conf2);
 
-    // Case 1: path p not in the default FS.
+    // Case 1: path p in the /data mount point.
-    // Return a trash root within the mount point.
+    // Return a trash root within the /data mount point.
     Path dataTestPath = new Path("/data/dir/file");
-    Path dataTrashRoot = new Path(targetTestRoot,
+    Path dataTrashRoot = fsView2.makeQualified(
-        "data/" + TRASH_PREFIX + "/" + ugi.getShortUserName());
+        new Path("/data/" + TRASH_PREFIX + "/" + ugi.getShortUserName()));
     Assert.assertEquals(dataTrashRoot, fsView2.getTrashRoot(dataTestPath));
 
-    // Case 2: path p not found in mount table, fall back to the default FS
+    // Case 2: path p not found in mount table.
-    // Return a trash root in user home dir
+    // Return a trash root in fallback FS.
     Path nonExistentPath = new Path("/nonExistentDir/nonExistentFile");
-    Path userTrashRoot = new Path(fsTarget.getHomeDirectory(), TRASH_PREFIX);
+    Path expectedTrash =
-    Assert.assertEquals(userTrashRoot, fsView2.getTrashRoot(nonExistentPath));
+        fsView2.makeQualified(getTrashRootInFallBackFS());
+    Assert.assertEquals(expectedTrash, fsView2.getTrashRoot(nonExistentPath));
 
-    // Case 3: turn off the CONFIG_VIEWFS_MOUNT_POINT_LOCAL_TRASH flag.
+    // Case 3: turn off the CONFIG_VIEWFS_TRASH_FORCE_INSIDE_MOUNT_POINT flag.
     // Return a trash root in user home dir.
-    conf2.setBoolean(CONFIG_VIEWFS_MOUNT_POINT_LOCAL_TRASH, false);
+    conf2.setBoolean(CONFIG_VIEWFS_TRASH_FORCE_INSIDE_MOUNT_POINT, false);
     fsView2 = FileSystem.get(FsConstants.VIEWFS_URI, conf2);
-    Assert.assertEquals(userTrashRoot, fsView2.getTrashRoot(dataTestPath));
+    Path targetFSUserHomeTrashRoot = fsTarget.makeQualified(
+        new Path(fsTarget.getHomeDirectory(), TRASH_PREFIX));
+    Assert.assertEquals(targetFSUserHomeTrashRoot,
+        fsView2.getTrashRoot(dataTestPath));
 
     // Case 4: viewFS without fallback. Expect exception for a nonExistent path
     conf2 = new Configuration(conf);
@@ -1141,30 +1152,14 @@ public void testTrashRootLocalizedTrash() throws IOException {
       fsView2.getTrashRoot(nonExistentPath);
     } catch (NotInMountpointException ignored) {
     }
-
-    // Case 5: path p is in the same mount point as targetFS.getTrashRoot().
-    // Return targetFS.getTrashRoot()
-    // Use a new Configuration object, so that we can start with an empty
-    // mount table. This would avoid a conflict between the /user link in
-    // setupMountPoints() and homeDir we will need to setup for this test.
-    // default homeDir for hdfs is /user/.
-    Configuration conf3 = ViewFileSystemTestSetup.createConfig();
-    Path homeDir = fsTarget.getHomeDirectory();
-    String homeParentDir = homeDir.getParent().toUri().getPath();
-    conf3.setBoolean(CONFIG_VIEWFS_MOUNT_POINT_LOCAL_TRASH, true);
-    ConfigUtil.addLink(conf3, homeParentDir,
-        new Path(targetTestRoot, homeParentDir).toUri());
-    Path homeTestPath = new Path(homeDir.toUri().getPath(), "testuser/file");
-    FileSystem fsView3 = FileSystem.get(FsConstants.VIEWFS_URI, conf3);
-    Assert.assertEquals(userTrashRoot, fsView3.getTrashRoot(homeTestPath));
   }
 
   /**
    * A mocked FileSystem which returns a deep trash dir.
    */
-  static class MockTrashRootFS extends MockFileSystem {
+  static class DeepTrashRootMockFS extends MockFileSystem {
     public static final Path TRASH =
-        new Path("/mnt/very/deep/deep/trash/dir/.Trash");
+        new Path("/vol/very/deep/deep/trash/dir/.Trash");
 
     @Override
     public Path getTrashRoot(Path path) {
@@ -1173,28 +1168,31 @@ public Path getTrashRoot(Path path) {
   }
 
   /**
-   * Test a trash root that is inside a mount point for getTrashRoot
+   * Test getTrashRoot that is very deep inside a mount point.
    */
   @Test
   public void testTrashRootDeepTrashDir() throws IOException {
 
     Configuration conf2 = ViewFileSystemTestSetup.createConfig();
-    conf2.setBoolean(CONFIG_VIEWFS_MOUNT_POINT_LOCAL_TRASH, true);
+    conf2.setBoolean(CONFIG_VIEWFS_TRASH_FORCE_INSIDE_MOUNT_POINT, true);
-    conf2.setClass("fs.mocktrashfs.impl", MockTrashRootFS.class,
+    conf2.setClass("fs.mocktrashfs.impl", DeepTrashRootMockFS.class,
         FileSystem.class);
-    ConfigUtil.addLink(conf2, "/mnt", URI.create("mocktrashfs://mnt/path"));
+    ConfigUtil.addLink(conf2, "/mnt/datavol1",
-    Path testPath = new Path(MockTrashRootFS.TRASH, "projs/proj");
+        URI.create("mocktrashfs://localhost/vol"));
+    Path testPath = new Path("/mnt/datavol1/projs/proj");
     FileSystem fsView2 = FileSystem.get(FsConstants.VIEWFS_URI, conf2);
-    Assert.assertEquals(MockTrashRootFS.TRASH, fsView2.getTrashRoot(testPath));
+    Path expectedTrash = fsView2.makeQualified(
+        new Path("/mnt/datavol1/very/deep/deep/trash/dir/.Trash"));
+    Assert.assertEquals(expectedTrash, fsView2.getTrashRoot(testPath));
   }
 
   /**
-   * Test localized trash roots in getTrashRoots() for all users.
+   * Test getTrashRoots() for all users.
    */
   @Test
   public void testTrashRootsAllUsers() throws IOException {
     Configuration conf2 = new Configuration(conf);
-    conf2.setBoolean(CONFIG_VIEWFS_MOUNT_POINT_LOCAL_TRASH, true);
+    conf2.setBoolean(CONFIG_VIEWFS_TRASH_FORCE_INSIDE_MOUNT_POINT, true);
     FileSystem fsView2 = FileSystem.get(FsConstants.VIEWFS_URI, conf2);
 
     // Case 1: verify correct trash roots from fsView and fsView2
@@ -1230,17 +1228,27 @@ public void testTrashRootsAllUsers() throws IOException {
     FileSystem fsView4 = FileSystem.get(FsConstants.VIEWFS_URI, conf4);
     int trashRootsNum4 = fsView4.getTrashRoots(true).size();
     Assert.assertEquals(afterTrashRootsNum2 + 2, trashRootsNum4);
+
+    // Case 4: test trash roots in fallback FS
+    fsTarget.mkdirs(new Path(targetTestRoot, ".Trash/user10"));
+    fsTarget.mkdirs(new Path(targetTestRoot, ".Trash/user11"));
+    fsTarget.mkdirs(new Path(targetTestRoot, ".Trash/user12"));
+    Configuration conf5 = new Configuration(conf2);
+    ConfigUtil.addLinkFallback(conf5, targetTestRoot.toUri());
+    FileSystem fsView5 = FileSystem.get(FsConstants.VIEWFS_URI, conf5);
+    int trashRootsNum5 = fsView5.getTrashRoots(true).size();
+    Assert.assertEquals(afterTrashRootsNum2 + 3, trashRootsNum5);
   }
 
   /**
-   * Test localized trash roots in getTrashRoots() for current user.
+   * Test getTrashRoots() for current user.
    */
   @Test
   public void testTrashRootsCurrentUser() throws IOException {
     String currentUser =
         UserGroupInformation.getCurrentUser().getShortUserName();
     Configuration conf2 = new Configuration(conf);
-    conf2.setBoolean(CONFIG_VIEWFS_MOUNT_POINT_LOCAL_TRASH, true);
+    conf2.setBoolean(CONFIG_VIEWFS_TRASH_FORCE_INSIDE_MOUNT_POINT, true);
     FileSystem fsView2 = FileSystem.get(FsConstants.VIEWFS_URI, conf2);
 
     int beforeTrashRootNum = fsView.getTrashRoots(false).size();
@@ -1256,6 +1264,14 @@ public void testTrashRootsCurrentUser() throws IOException {
     int afterTrashRootsNum2 = fsView2.getTrashRoots(false).size();
     Assert.assertEquals(beforeTrashRootNum, afterTrashRootsNum);
     Assert.assertEquals(beforeTrashRootNum2 + 2, afterTrashRootsNum2);
+
+    // Test trash roots in fallback FS
+    Configuration conf3 = new Configuration(conf2);
+    fsTarget.mkdirs(new Path(targetTestRoot, TRASH_PREFIX + "/" + currentUser));
+    ConfigUtil.addLinkFallback(conf3, targetTestRoot.toUri());
+    FileSystem fsView3 = FileSystem.get(FsConstants.VIEWFS_URI, conf3);
+    int trashRootsNum3 = fsView3.getTrashRoots(false).size();
+    Assert.assertEquals(afterTrashRootsNum2 + 1, trashRootsNum3);
   }
 
   @Test(expected = NotInMountpointException.class)

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

@@ -55,6 +55,7 @@
 import org.apache.hadoop.test.GenericTestUtils;
 import static org.apache.hadoop.fs.CommonConfigurationKeysPublic.FS_TRASH_INTERVAL_KEY;
 import static org.apache.hadoop.fs.CommonConfigurationKeysPublic.IPC_CLIENT_CONNECT_MAX_RETRIES_KEY;
+import static org.apache.hadoop.fs.FileSystem.TRASH_PREFIX;
 
 import org.junit.After;
 import org.junit.AfterClass;
@@ -181,6 +182,13 @@ int getExpectedDelegationTokenCountWithCredentials() {
     return 2;
   }
 
+  @Override
+  Path getTrashRootInFallBackFS() throws IOException {
+    return new Path(
+        "/" + TRASH_PREFIX + "/" + UserGroupInformation.getCurrentUser()
+            .getShortUserName());
+  }
+
   @Test
   public void testTrashRootsAfterEncryptionZoneDeletion() throws Exception {
     final Path zone = new Path("/EZ");