diff --git a/cmds/sm/src/com/android/commands/sm/Sm.java b/cmds/sm/src/com/android/commands/sm/Sm.java
index db3772d..658d662 100644
--- a/cmds/sm/src/com/android/commands/sm/Sm.java
+++ b/cmds/sm/src/com/android/commands/sm/Sm.java
@@ -94,6 +94,8 @@
             runGetFbeMode();
         } else if ("fstrim".equals(op)) {
             runFstrim();
+        } else if ("set-virtual-disk".equals(op)) {
+            runSetVirtualDisk();
         } else {
             throw new IllegalArgumentException();
         }
@@ -225,6 +227,12 @@
         mSm.fstrim(0);
     }
 
+    public void runSetVirtualDisk() throws RemoteException {
+        final boolean virtualDisk = Boolean.parseBoolean(nextArg());
+        mSm.setDebugFlags(virtualDisk ? StorageManager.DEBUG_VIRTUAL_DISK : 0,
+                StorageManager.DEBUG_VIRTUAL_DISK);
+    }
+
     private String nextArg() {
         if (mNextArg >= mArgs.length) {
             return null;
@@ -240,6 +248,7 @@
         System.err.println("       sm has-adoptable");
         System.err.println("       sm get-primary-storage-uuid");
         System.err.println("       sm set-force-adoptable [true|false]");
+        System.err.println("       sm set-virtual-disk [true|false]");
         System.err.println("");
         System.err.println("       sm partition DISK [public|private|mixed] [ratio]");
         System.err.println("       sm mount VOLUME");
diff --git a/core/java/android/os/Parcel.java b/core/java/android/os/Parcel.java
index 7a39d23..034edcf 100644
--- a/core/java/android/os/Parcel.java
+++ b/core/java/android/os/Parcel.java
@@ -2036,14 +2036,20 @@
         }
     }
 
+    /** @deprecated use {@link android.system.Os#open(String, int, int)} */
+    @Deprecated
+    static native FileDescriptor openFileDescriptor(String file, int mode)
+            throws FileNotFoundException;
 
-    /*package*/ static native FileDescriptor openFileDescriptor(String file,
-            int mode) throws FileNotFoundException;
-    /*package*/ static native FileDescriptor dupFileDescriptor(FileDescriptor orig)
-            throws IOException;
-    /*package*/ static native void closeFileDescriptor(FileDescriptor desc)
-            throws IOException;
-    /*package*/ static native void clearFileDescriptor(FileDescriptor desc);
+    /** @deprecated use {@link android.system.Os#dup(FileDescriptor)} */
+    @Deprecated
+    static native FileDescriptor dupFileDescriptor(FileDescriptor orig) throws IOException;
+
+    /** @deprecated use {@link android.system.Os#close(FileDescriptor)} */
+    @Deprecated
+    static native void closeFileDescriptor(FileDescriptor desc) throws IOException;
+
+    static native void clearFileDescriptor(FileDescriptor desc);
 
     /**
      * Read a byte value from the parcel at the current dataPosition().
diff --git a/core/java/android/os/ParcelFileDescriptor.java b/core/java/android/os/ParcelFileDescriptor.java
index 8882672..3212139 100644
--- a/core/java/android/os/ParcelFileDescriptor.java
+++ b/core/java/android/os/ParcelFileDescriptor.java
@@ -17,11 +17,21 @@
 package android.os;
 
 import static android.system.OsConstants.AF_UNIX;
+import static android.system.OsConstants.O_APPEND;
+import static android.system.OsConstants.O_CREAT;
+import static android.system.OsConstants.O_RDONLY;
+import static android.system.OsConstants.O_RDWR;
+import static android.system.OsConstants.O_TRUNC;
+import static android.system.OsConstants.O_WRONLY;
 import static android.system.OsConstants.SEEK_SET;
-import static android.system.OsConstants.SOCK_STREAM;
 import static android.system.OsConstants.SOCK_SEQPACKET;
+import static android.system.OsConstants.SOCK_STREAM;
+import static android.system.OsConstants.S_IROTH;
+import static android.system.OsConstants.S_IRWXG;
+import static android.system.OsConstants.S_IRWXU;
 import static android.system.OsConstants.S_ISLNK;
 import static android.system.OsConstants.S_ISREG;
+import static android.system.OsConstants.S_IWOTH;
 
 import android.content.BroadcastReceiver;
 import android.content.ContentProvider;
@@ -33,6 +43,7 @@
 import android.util.Log;
 
 import dalvik.system.CloseGuard;
+
 import libcore.io.IoUtils;
 import libcore.io.Memory;
 
@@ -279,8 +290,28 @@
                     "Must specify MODE_READ_ONLY, MODE_WRITE_ONLY, or MODE_READ_WRITE");
         }
 
+        int flags = 0;
+        switch (mode & MODE_READ_WRITE) {
+            case 0:
+            case MODE_READ_ONLY: flags = O_RDONLY; break;
+            case MODE_WRITE_ONLY: flags = O_WRONLY; break;
+            case MODE_READ_WRITE: flags = O_RDWR; break;
+        }
+
+        if ((mode & MODE_CREATE) != 0) flags |= O_CREAT;
+        if ((mode & MODE_TRUNCATE) != 0) flags |= O_TRUNC;
+        if ((mode & MODE_APPEND) != 0) flags |= O_APPEND;
+
+        int realMode = S_IRWXU | S_IRWXG;
+        if ((mode & MODE_WORLD_READABLE) != 0) realMode |= S_IROTH;
+        if ((mode & MODE_WORLD_WRITEABLE) != 0) realMode |= S_IWOTH;
+
         final String path = file.getPath();
-        return Parcel.openFileDescriptor(path, mode);
+        try {
+            return Os.open(path, flags, realMode);
+        } catch (ErrnoException e) {
+            throw new FileNotFoundException(e.getMessage());
+        }
     }
 
     /**
diff --git a/core/java/android/os/storage/StorageManager.java b/core/java/android/os/storage/StorageManager.java
index 53c9a23..7e1b5ab 100644
--- a/core/java/android/os/storage/StorageManager.java
+++ b/core/java/android/os/storage/StorageManager.java
@@ -113,6 +113,8 @@
     public static final String PROP_EMULATE_FBE = "persist.sys.emulate_fbe";
     /** {@hide} */
     public static final String PROP_SDCARDFS = "persist.sys.sdcardfs";
+    /** {@hide} */
+    public static final String PROP_VIRTUAL_DISK = "persist.sys.virtual_disk";
 
     /** {@hide} */
     public static final String UUID_PRIVATE_INTERNAL = null;
@@ -140,6 +142,8 @@
     public static final int DEBUG_SDCARDFS_FORCE_ON = 1 << 2;
     /** {@hide} */
     public static final int DEBUG_SDCARDFS_FORCE_OFF = 1 << 3;
+    /** {@hide} */
+    public static final int DEBUG_VIRTUAL_DISK = 1 << 4;
 
     // NOTE: keep in sync with installd
     /** {@hide} */
diff --git a/services/core/java/com/android/server/StorageManagerService.java b/services/core/java/com/android/server/StorageManagerService.java
index 8e6310f..9b4b55e 100644
--- a/services/core/java/com/android/server/StorageManagerService.java
+++ b/services/core/java/com/android/server/StorageManagerService.java
@@ -2078,6 +2078,20 @@
                 Binder.restoreCallingIdentity(token);
             }
         }
+
+        if ((mask & StorageManager.DEBUG_VIRTUAL_DISK) != 0) {
+            final boolean enabled = (flags & StorageManager.DEBUG_VIRTUAL_DISK) != 0;
+
+            final long token = Binder.clearCallingIdentity();
+            try {
+                SystemProperties.set(StorageManager.PROP_VIRTUAL_DISK, Boolean.toString(enabled));
+
+                // Reset storage to kick new setting into place
+                mHandler.obtainMessage(H_RESET).sendToTarget();
+            } finally {
+                Binder.restoreCallingIdentity(token);
+            }
+        }
     }
 
     @Override