DM_READONLY_FLAG
dev->dmi.flags |= DM_READONLY_FLAG;
if (param->flags & DM_READONLY_FLAG)
set_disk_ro(dm_disk(md), !!(dmi->flags & DM_READONLY_FLAG));
param->flags &= ~(DM_SUSPEND_FLAG | DM_READONLY_FLAG |
param->flags |= DM_READONLY_FLAG;
param->flags |= DM_READONLY_FLAG;