panic: ufs_dirbad: bad dir

[Matthew Dillon]

:After a previous panic I got this panic while building world. After cleaning
:out /usr/obj I have been unable to repeat this panic again, so it's not
:reproducable (for now).
:
:Dump at leaf:~rumko/crash/bad_dir/ and the backtrace is:
:#0  dumpsys () at ./machine/thread.h:83
:#1  0xc01e6d95 in boot (howto=260) at /usr/src/sys/kern/kern_shutdown.c:375
:#2  0xc01e705a in panic (fmt=0xc0447c39 "ufs_dirbad: bad dir")

    This typically means the (ufs) filesystem got corrupted somehow.
    The panic is usually delayed significantly from the cause (by minutes,
    hours, or days), so by the time the panic occurs the original cause
    will have been lost.

						-Matt