GetTrashRoots(): include trash roots in fallback FS as well.

Author: Xing Lin

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

@@ -1235,9 +1235,19 @@ public Collection<FileStatus> getTrashRoots(boolean allUsers) {
       return trashRoots.values();
     }
 
-    // Get trash roots in TRASH_PREFIX dir inside mount points.
+    // Get trash roots in TRASH_PREFIX dir inside mount points and fallback FS.
+    List<InodeTree.MountPoint<FileSystem>> mountPoints =
+        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()));
+    }
+
     try {
-      for (InodeTree.MountPoint<FileSystem> mountPoint : fsState.getMountPoints()) {
+      for (InodeTree.MountPoint<FileSystem> mountPoint : mountPoints) {
 
         Path trashRoot =
             makeQualified(new Path(mountPoint.src + "/" + TRASH_PREFIX));
@@ -1270,7 +1280,7 @@ public Collection<FileStatus> getTrashRoots(boolean allUsers) {
         }
       }
     } catch (IOException e) {
-      LOG.warn("Exception in get all trash roots", e);
+      LOG.warn("Exception in get all trash roots for mount points", e);
     }
 
     return trashRoots.values();

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

@@ -1228,6 +1228,16 @@ 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);
   }
 
   /**
@@ -1254,6 +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)