It's critical not to perform any write on a volume without an exclusive lock on it.
That lock is only acquired if ChkDsk is started in RW mode.
Also added an assert in write routine, to make sure that when we're about to perform
a write operation, we're really allowed to do so.
This will avoid volume corruptions when a simple "chkdsk" is issued from cmd.
To put it simple: check will really check now, and won't attempt any repair.
CORE-14119
For instance, when repair is required, we can ask the caller whether we should
continue or not in case locking failed.
Also, introduced a hack for 1st stage where IopParseDevice() hack is in usage
so that broken NTSTATUS is diverted to appropriate status.
That way, usetup will properly continue even if locking failed (due to its
callback stub!)
CORE-14087
