bonnie++ failed on locally mounted NFS

[Tai-hwa Liang]

   Searching PR database for 'drastic I/O error' returns kern/33203,
which seems a little bit irrelevant as there is no 'bad cookie' error 
in -CURRENT.

cur /tmp> uname -a
FreeBSD cur.local.domain 9.0-CURRENT FreeBSD 9.0-CURRENT #23: Sat Aug 14 07:25:01 CST 2010 root at cur.local.domain:/usr/src/sys/i386/compile/cur  i386
cur /tmp> cat /etc/exports
/home/test	-maproot=root
cur /tmp> sudo mount localhost:/home/test /mnt/nfs && cd /mnt/nfs && mount
/dev/ad0s2a on / (ufs, NFS exported, local)
devfs on /dev (devfs, local, multilabel)
/dev/ad0s2e on /var (ufs, local, soft-updates)
/dev/ad0s2d.journal on /usr (ufs, asynchronous, NFS exported, local)
/dev/md0 on /tmp (ufs, local, soft-updates)
/dev/ad0s2f.eli on /home (ufs, NFS exported, local, soft-updates)
localhost:/home/test on /mnt/nfs (nfs)
cur /mnt/nfs> bonnie++
Writing a byte at a time...done
Writing intelligently...done
Rewriting...done
Reading a byte at a time...done
Reading intelligently...done
start 'em...done...done...done...done...done...
Create files in sequential order...done.
Stat files in sequential order...done.
Delete files in sequential order...Bonnie: drastic I/O error (rmdir):
Directory not empty
Cleaning up test directory after error.
Exit 1
cur /mnt/nfs>

   Reproducible with RELENG_7, RELENG_8 and -CURRENT.  However, running
bonnie++ on local file system such like UFS won't fail.