This is the result of trying to hunt down a problem I have with the creat stress test, where I seem to run out of some resource (inodes?) on a ufs2 file system when "soft update" is enabled.
#!/bin/sh

tst() {
   umount /tmp
   fsck -y /tmp
   mount /tmp
   df -hi /tmp | head -1
   cd /
   for i in `jot 10`; do
      (cd /tmp/stressX; find . -delete)
      sync; sync; sync
      cd /tmp/stress2/testcases/creat
      d=`date '+%T'`
      f=`df -hi /tmp | tail -1`
      echo $d $f
      ./creat -t 1m -i 10 -h
   done
   cd /
   umount /tmp
   fsck -y /tmp
   mount /tmp
   d=`date '+%T'`
   f=`df -hi /tmp | tail -1`
   echo $d $f
}

umount /tmp
tunefs -n disable /tmp
mount /tmp
tst

echo ""
umount /tmp
tunefs -n enable /tmp
mount /tmp
tst

---

Script started on Thu Sep 22 09:53:55 2005
# uname -a
FreeBSD  6.0-BETA5 FreeBSD 6.0-BETA5 #1: Mon Sep 19 09:23:01 CEST 2005     pho@crashbox.osted.lan:/usr/src/sys/i386/compile/Generic  i386
# sh ./x.sh
tunefs: soft updates cleared
** /dev/ad0s1e
** Last Mounted on /tmp
** Phase 1 - Check Blocks and Sizes
** Phase 2 - Check Pathnames
** Phase 3 - Check Connectivity
** Phase 4 - Check Reference Counts
** Phase 5 - Check Cyl groups
604 files, 172072 used, 840943 free (519 frags, 105053 blocks, 0.1% fragmentation)
Filesystem     Size    Used   Avail Capacity iused  ifree %iused  Mounted on
09:54:09 /dev/ad0s1e 1.9G 336M 1.4G 18% 603 282019 0% /tmp
09:55:37 /dev/ad0s1e 1.9G 336M 1.4G 18% 603 282019 0% /tmp
09:57:06 /dev/ad0s1e 1.9G 336M 1.4G 18% 603 282019 0% /tmp
09:58:31 /dev/ad0s1e 1.9G 336M 1.4G 18% 603 282019 0% /tmp
09:59:56 /dev/ad0s1e 1.9G 336M 1.4G 18% 603 282019 0% /tmp
10:01:22 /dev/ad0s1e 1.9G 336M 1.4G 18% 603 282019 0% /tmp
10:02:51 /dev/ad0s1e 1.9G 336M 1.4G 18% 603 282019 0% /tmp
10:04:16 /dev/ad0s1e 1.9G 336M 1.4G 18% 603 282019 0% /tmp
10:05:47 /dev/ad0s1e 1.9G 336M 1.4G 18% 603 282019 0% /tmp
10:07:13 /dev/ad0s1e 1.9G 336M 1.4G 18% 603 282019 0% /tmp
** /dev/ad0s1e
** Last Mounted on /tmp
** Phase 1 - Check Blocks and Sizes
** Phase 2 - Check Pathnames
** Phase 3 - Check Connectivity
** Phase 4 - Check Reference Counts
** Phase 5 - Check Cyl groups
604 files, 172072 used, 840943 free (519 frags, 105053 blocks, 0.1% fragmentation)
10:08:45 /dev/ad0s1e 1.9G 336M 1.4G 18% 604 282018 0% /tmp

tunefs: soft updates set
** /dev/ad0s1e
** Last Mounted on /tmp
** Phase 1 - Check Blocks and Sizes
** Phase 2 - Check Pathnames
** Phase 3 - Check Connectivity
** Phase 4 - Check Reference Counts
** Phase 5 - Check Cyl groups
604 files, 172072 used, 840943 free (519 frags, 105053 blocks, 0.1% fragmentation)
Filesystem     Size    Used   Avail Capacity iused  ifree %iused  Mounted on
10:08:47 /dev/ad0s1e 1.9G 336M 1.4G 18% 603 282019 0% /tmp
10:09:57 /dev/ad0s1e 1.9G 336M 1.4G 18% 632 281990 0% /tmp
10:11:03 /dev/ad0s1e 1.9G 336M 1.4G 18% 638 281984 0% /tmp
10:12:13 /dev/ad0s1e 1.9G 336M 1.4G 18% 638 281984 0% /tmp
10:13:17 /dev/ad0s1e 1.9G 336M 1.4G 18% 638 281984 0% /tmp
10:14:25 /dev/ad0s1e 1.9G 336M 1.4G 18% 641 281981 0% /tmp
10:15:34 /dev/ad0s1e 1.9G 336M 1.4G 18% 646 281976 0% /tmp
10:16:39 /dev/ad0s1e 1.9G 336M 1.4G 18% 653 281969 0% /tmp

/tmp: create/symlink failed, no inodes free

/tmp: create/symlink failed, no inodes free

/tmp: create/symlink failed, no inodes free
creat: 
/tmp: create/symlink failed, no inodes free

/tmp: create/symlink failed, no inodes free

/tmp: create/symlink failed, no inodes free

/tmp: create/symlink failed, no inodes free

/tmp: create/symlink failed, no inodes free
creat(p00527.07879)creat: creat: : creat(p00523.08786)creat(p00520.08786)No space left on device
: : 
/tmp: create/symlink failed, no inodes free
No space left on device
No space left on device
creat: creat: creat: creat: creat: creat: creat(p00521.06463)creat(p00518.00000)creat(p00524.05121)creat(p00525.06602)creat(p00526.07120)creat(p00522.07639): : : : No space left on device
: : No space left on device
No space left on device
No space left on device
No space left on device
No space left on device

/tmp: create/symlink failed, no inodes free
creat: creat(p00519.07596): No space left on device
10:17:43 /dev/ad0s1e 1.9G 336M 1.4G 18% 668 281954 0% /tmp
10:18:48 /dev/ad0s1e 1.9G 336M 1.4G 18% 673 281949 0% /tmp

/tmp: create/symlink failed, no inodes free

/tmp: create/symlink failed, no inodes free

/tmp: create/symlink failed, no inodes free

/tmp: create/symlink failed, no inodes free

/tmp: create/symlink failed, no inodes free
creat: creat: creat: creat: creat: creat(p00565.07298)creat(p00564.14107)creat(p00566.07494)creat(p00558.03703)creat(p00563.07544): : : : : No space left on device
No space left on device
No space left on device
No space left on device
No space left on device

/tmp: create/symlink failed, no inodes free
creat: creat(p00559.06796): No space left on device

/tmp: create/symlink failed, no inodes free
creat: creat(p00562.06609): No space left on device

/tmp: create/symlink failed, no inodes free

/tmp: create/symlink failed, no inodes free

/tmp: create/symlink failed, no inodes free
creat: creat: creat(p00564.01120): No space left on device
creat: creat(p00565.00231)creat(p00558.00013): : No space left on device
No space left on device
** /dev/ad0s1e
** Last Mounted on /tmp
** Phase 1 - Check Blocks and Sizes
** Phase 2 - Check Pathnames
** Phase 3 - Check Connectivity
** Phase 4 - Check Reference Counts
ZERO LENGTH DIR I=23582  OWNER=root MODE=40770
SIZE=0 MTIME=Sep 22 10:19 2005 
CLEAR? yes

LINK COUNT DIR I=188420  OWNER=pho MODE=40777
SIZE=512 MTIME=Sep 22 10:19 2005  COUNT 3 SHOULD BE 2
ADJUST? yes

** Phase 5 - Check Cyl groups
FREE BLK COUNT(S) WRONG IN SUPERBLK
SALVAGE? yes

SUMMARY INFORMATION BAD
SALVAGE? yes

BLK(S) MISSING IN BIT MAPS
SALVAGE? yes

604 files, 172072 used, 840943 free (519 frags, 105053 blocks, 0.1% fragmentation)

***** FILE SYSTEM WAS MODIFIED *****
10:19:57 /dev/ad0s1e 1.9G 336M 1.4G 18% 604 282018 0% /tmp
# 

From the console:
pid 558 (creat), uid 0 inumber 188423 on /tmp: out of inodes
/tmp: unmount pending error: blocks 0 files -83