diff --git a/api/current.txt b/api/current.txt
index 231495fa02c1d..e8c975880983f 100644
--- a/api/current.txt
+++ b/api/current.txt
@@ -38234,6 +38234,7 @@ package android.provider {
     field public static final String COLUMN_MIME_TYPE = "mime_type";
     field public static final String COLUMN_SIZE = "_size";
     field public static final String COLUMN_SUMMARY = "summary";
+    field public static final int FLAG_DIR_BLOCKS_TREE = 32768; // 0x8000
     field public static final int FLAG_DIR_PREFERS_GRID = 16; // 0x10
     field public static final int FLAG_DIR_PREFERS_LAST_MODIFIED = 32; // 0x20
     field public static final int FLAG_DIR_SUPPORTS_CREATE = 8; // 0x8
diff --git a/core/java/android/provider/DocumentsContract.java b/core/java/android/provider/DocumentsContract.java
index fd81178d2cfbf..eb09930005b52 100644
--- a/core/java/android/provider/DocumentsContract.java
+++ b/core/java/android/provider/DocumentsContract.java
@@ -363,15 +363,22 @@ public final class DocumentsContract {
          * <p>
          * Type: INTEGER (int)
          *
-         * @see #FLAG_SUPPORTS_WRITE
-         * @see #FLAG_SUPPORTS_DELETE
-         * @see #FLAG_SUPPORTS_THUMBNAIL
+         * @see #FLAG_DIR_BLOCKS_TREE
          * @see #FLAG_DIR_PREFERS_GRID
          * @see #FLAG_DIR_PREFERS_LAST_MODIFIED
-         * @see #FLAG_VIRTUAL_DOCUMENT
+         * @see #FLAG_DIR_SUPPORTS_CREATE
+         * @see #FLAG_PARTIAL
          * @see #FLAG_SUPPORTS_COPY
+         * @see #FLAG_SUPPORTS_DELETE
+         * @see #FLAG_SUPPORTS_METADATA
          * @see #FLAG_SUPPORTS_MOVE
          * @see #FLAG_SUPPORTS_REMOVE
+         * @see #FLAG_SUPPORTS_RENAME
+         * @see #FLAG_SUPPORTS_SETTINGS
+         * @see #FLAG_SUPPORTS_THUMBNAIL
+         * @see #FLAG_SUPPORTS_WRITE
+         * @see #FLAG_VIRTUAL_DOCUMENT
+         * @see #FLAG_WEB_LINKABLE
          */
         public static final String COLUMN_FLAGS = "flags";
 
@@ -542,6 +549,23 @@ public final class DocumentsContract {
          * @see DocumentsContract#getDocumentMetadata(ContentInterface, Uri)
          */
         public static final int FLAG_SUPPORTS_METADATA = 1 << 14;
+
+        /**
+         * Flag indicating that a document is a directory that wants to block itself
+         * from being selected when the user launches an {@link Intent#ACTION_OPEN_DOCUMENT_TREE}
+         * intent. Only valid when {@link #COLUMN_MIME_TYPE} is {@link #MIME_TYPE_DIR}.
+         * <p>
+         * Note that this flag <em>only</em> applies to the single directory to which it is
+         * applied. It does <em>not</em> block the user from selecting either a parent or
+         * child directory during an {@link Intent#ACTION_OPEN_DOCUMENT_TREE} request.
+         * In particular, the only way to guarantee that a specific directory can never
+         * be granted via an {@link Intent#ACTION_OPEN_DOCUMENT_TREE} request is to ensure
+         * that both it and <em>all of its parent directories</em> have set this flag.
+         *
+         * @see Intent#ACTION_OPEN_DOCUMENT_TREE
+         * @see #COLUMN_FLAGS
+         */
+        public static final int FLAG_DIR_BLOCKS_TREE = 1 << 15;
     }
 
     /**
diff --git a/core/java/com/android/internal/content/FileSystemProvider.java b/core/java/com/android/internal/content/FileSystemProvider.java
index cdb79abbb7ceb..f5708a5c89afa 100644
--- a/core/java/com/android/internal/content/FileSystemProvider.java
+++ b/core/java/com/android/internal/content/FileSystemProvider.java
@@ -17,6 +17,7 @@
 package com.android.internal.content;
 
 import android.annotation.CallSuper;
+import android.annotation.NonNull;
 import android.annotation.Nullable;
 import android.content.ContentResolver;
 import android.content.Intent;
@@ -552,6 +553,11 @@ public abstract class FileSystemProvider extends DocumentsProvider {
                     flags |= Document.FLAG_SUPPORTS_DELETE;
                     flags |= Document.FLAG_SUPPORTS_RENAME;
                     flags |= Document.FLAG_SUPPORTS_MOVE;
+
+                    if (shouldBlockFromTree(docId)) {
+                        flags |= Document.FLAG_DIR_BLOCKS_TREE;
+                    }
+
                 } else {
                     flags |= Document.FLAG_SUPPORTS_WRITE;
                     flags |= Document.FLAG_SUPPORTS_DELETE;
@@ -592,6 +598,10 @@ public abstract class FileSystemProvider extends DocumentsProvider {
         return row;
     }
 
+    protected boolean shouldBlockFromTree(@NonNull String docId) {
+        return false;
+    }
+
     protected boolean typeSupportsMetadata(String mimeType) {
         return MetadataReader.isSupportedMimeType(mimeType)
                 || Document.MIME_TYPE_DIR.equals(mimeType);
diff --git a/packages/ExternalStorageProvider/src/com/android/externalstorage/ExternalStorageProvider.java b/packages/ExternalStorageProvider/src/com/android/externalstorage/ExternalStorageProvider.java
index 1b27b52f1fa14..48d34ae7ba47f 100644
--- a/packages/ExternalStorageProvider/src/com/android/externalstorage/ExternalStorageProvider.java
+++ b/packages/ExternalStorageProvider/src/com/android/externalstorage/ExternalStorageProvider.java
@@ -16,6 +16,7 @@
 
 package com.android.externalstorage;
 
+import android.annotation.NonNull;
 import android.annotation.Nullable;
 import android.app.usage.StorageStatsManager;
 import android.content.ContentResolver;
@@ -298,6 +299,53 @@ public class ExternalStorageProvider extends FileSystemProvider {
         return projection != null ? projection : DEFAULT_ROOT_PROJECTION;
     }
 
+    /**
+     * Check that the directory is the root of storage or blocked file from tree.
+     *
+     * @param docId the docId of the directory to be checked
+     * @return true, should be blocked from tree. Otherwise, false.
+     */
+    @Override
+    protected boolean shouldBlockFromTree(@NonNull String docId) {
+        try {
+            final File dir = getFileForDocId(docId, true /* visible */).getCanonicalFile();
+            if (!dir.isDirectory()) {
+                return false;
+            }
+
+            final String path = dir.getAbsolutePath();
+
+            // Block Download folder from tree
+            if (MediaStore.Downloads.isDownloadDir(path)) {
+                return true;
+            }
+
+            final ArrayMap<String, RootInfo> roots = new ArrayMap<>();
+
+            synchronized (mRootsLock) {
+                roots.putAll(mRoots);
+            }
+
+            // block root of storage
+            for (int i = 0; i < roots.size(); i++) {
+                RootInfo rootInfo = roots.valueAt(i);
+                // skip home root
+                if (TextUtils.equals(rootInfo.rootId, ROOT_ID_HOME)) {
+                    continue;
+                }
+
+                // block the root of storage
+                if (TextUtils.equals(path, rootInfo.visiblePath.getAbsolutePath())) {
+                    return true;
+                }
+            }
+            return false;
+        } catch (IOException e) {
+            throw new IllegalArgumentException(
+                    "Failed to determine if " + docId + " should block from tree " + ": " + e);
+        }
+    }
+
     @Override
     protected String getDocIdForFile(File file) throws FileNotFoundException {
         return getDocIdForFileMaybeCreate(file, false);