kern/157724: [GEOM] gpart 'add' command must preserve gap for schemes

[Eir Nym]

>Number:         157724
>Category:       kern
>Synopsis:       [GEOM] gpart 'add' command must preserve gap for schemes
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Thu Jun 09 07:30:11 UTC 2011
>Closed-Date:
>Last-Modified:
>Originator:     Eir Nym
>Release:        FreeBSD-CURRENT r222277
>Organization:
Private Person
>Environment:
>Description:
Any GEOM scheme has reserved space at the beginning. And this space must be preserved by gpart 'add' command.
>How-To-Repeat:
Short example with BSD scheme (same with MBR, GPT and others):
#gpart create -s MBR ada0
#gpart add -t freebsd -s 999 ada0
#gpart create -s BSD ada0
#gpart show ada0s1
=> 0 999 ada0s1 BSD
   0 999 - free -
#gpart add -t freebsd-ufs ada0s1
#gpart show ada0s1
=> 0 999 ada0s1 BSD
   0 999 freebsd-ufs

/// This partition scheme is currently invalid. ///
#gpart delete -i 1 ada0s1
#gpart destroy ada0s1
#bsdlabel -w ada0s1
#gpart show ada0s1
=> 0 999 ada0s1 BSD
   0 16  -free-
   16 983 !0
/// This partition scheme is currently valid ///
>Fix:


>Release-Note:
>Audit-Trail:
>Unformatted: