CHROMIUM: add boot-to-device mapper support.

include/linux/device-mapper.h

Index: include/linux/device-mapper.h
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index df7607e6dce80ec188d061524103fbdf822cd2a7..dd050b185848ac3b4a3940e3ac9d94d29d2a9971 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -216,6 +216,12 @@ void dm_set_mdptr(struct mapped_device *md, void *ptr);
 void *dm_get_mdptr(struct mapped_device *md);
 
 /*
+ * Export the device via the ioctl interface (uses mdptr).
+ */
+int dm_ioctl_export(struct mapped_device *md, const char *name,
+		    const char *uuid);
+
+/*
  * A device can still be used while suspended, but I/O is deferred.
  */
 int dm_suspend(struct mapped_device *md, unsigned suspend_flags);