misc/88355: df reports negative drive space

[Michael P. Soulier]

>Number:         88355
>Category:       misc
>Synopsis:       df reports negative drive space
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Tue Nov 01 17:40:13 GMT 2005
>Closed-Date:
>Last-Modified:
>Originator:     Michael P. Soulier
>Release:        5.4
>Organization:
>Environment:
FreeBSD kanga.digitaltorque.ca 5.4-RELEASE FreeBSD 5.4-RELEASE #0: Sun May  8 10:21:06 UTC 2005     root at harlow.cse.buffalo.edu:/usr/obj/usr/src/sys/GENERIC  i386         
>Description:
I have a 200Gig Maxtor drive. It is partitioned in several pieces, but the bulk of the space is mounted at /usr. Oddly, df reports negative space on the / partition. 

msoulier at kanga$ df
Filesystem  1K-blocks     Used     Avail Capacity  Mounted on
/dev/ad0s1a    253678   249376    -15992   107%    /
devfs               1        1         0   100%    /dev
/dev/ad0s1e    253678       16    233368     0%    /tmp
/dev/ad0s1f 191645218 10722808 165590794     6%    /usr
/dev/ad0s1d    253678    23066    210318    10%    /var

msoulier at kanga$ df -h
Filesystem     Size    Used   Avail Capacity  Mounted on
/dev/ad0s1a    248M    244M    -16M   107%    /
devfs          1.0K    1.0K      0B   100%    /dev
/dev/ad0s1e    248M     16K    228M     0%    /tmp
/dev/ad0s1f    183G     10G    158G     6%    /usr
/dev/ad0s1d    248M     23M    205M    10%    /var

Any reason why this would happen?
>How-To-Repeat:
In my case, install Maxtor 200Gig drive with FreeBSD 5.4, and run df. 
>Fix:
              
>Release-Note:
>Audit-Trail:
>Unformatted: