[issue1667] disklabel / disklabel64 change needs reboot / disk change

[Matthew Dillon]

:Changing disk label from disklabel to disklabel64 format
:or vice versa needs reboot (or disk change, eg natacontrol detach / attach).
:
:This has worked without reboot earlier,
:as described in disklabel(8) & disklabel64(8);
:problem was introduced with devfs as I remeber.
:
:Problem seems to be that in kernel disklabel survives
:erasure of label on device (disklabel -W .. / dd if=/dev/zero of=DISK ..)
:
: -thomas

    Devfs is supposed to flag writes to the dos slice and/or label area
    and re-probe.  There's probably some logic missing.

						-Matt