mount of ext2fs volume stuck in "D+" state (disk uninterruptible wait)

[Kris Kennaway]

Joe Peterson wrote:
> I just tried (under FreeBSD 7.0-RC1) to mount an ext2fs volume - I've
> mounted it before with no trouble on this same FreeBSD version.  This
> time, mount appeared to hang.  I noticed that I can see the contents of
> the volume under the mount point, so the mount seemed to "work", but the
> process is stuff.  "ps" shows:
> 
> root   1307  0.0  0.0  3156   792  p6  D+    5:21PM   0:00.00 mount
> /mnt/linux-home
> 
> The "ps" man page says that "D" means: "Marks a process in disk (or
> other short term, uninterruptible) wait."
> 
> Is there any way I can investigate what is going on?  I cannot umount
> (device busy) or break out of the mount command...

http://www.freebsd.org/doc/en_US.ISO8859-1/books/developers-handbook/kerneldebug.html

Kris