kern/112206: 4.11-stable disk free space problem

[qzheng]

>Number:         112206
>Category:       kern
>Synopsis:       4.11-stable disk free space problem
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sat Apr 28 14:10:09 GMT 2007
>Closed-Date:
>Last-Modified:
>Originator:     qzheng
>Release:        4.11
>Organization:
>Environment:
FreeBSD rs.sunnet.org 4.11-STABLE FreeBSD 4.11-STABLE #2: Fri Apr 15 17:04:37 CST 2005     root at rs.sunnet.org:/usr/obj/usr/src/sys/RS  i386
>Description:
this is a production server running for about 1 year without rebooting, our root directory recently reported file system full, so I did following jobs:

echo '' > those large log file
mv  those large directories to another parition and do a ln -s

but df -h still reports like:
Filesystem    Size   Used  Avail Capacity  Mounted on
/dev/ad0s1a    14G    12G   472M    96%    /

and a week later the root file system got to be full again, I checked the simple root filesystem but cant find any large file/dir there can use 12G space, so I tried to do a fastboot, and then df -h reports:

Filesystem    Size   Used  Avail Capacity  Mounted on
/dev/ad0s1a    14G   639M    12G     5%    /

that meant have to do a rebooting to force the UFS calculates the real disk usage, right?
>How-To-Repeat:

>Fix:

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