kern/39978: FFS triggers LOCKDEBUG in readdir

[reinoud%NetBSD.org@localhost]

        Note: There was a bad value `' for the field `Class'.
        It was set to the default value of `sw-bug'.

>Number:         39978
>Category:       kern
>Synopsis:       FFS triggers LOCKDEBUG in readdir
>Confidential:   no
>Severity:       critical
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Nov 20 15:30:00 +0000 2008
>Originator:     Reinoud Zandijk
>Release:        NetBSD 5.99.02
>Organization:
NetBSD
        
>Environment:
        
        
System:
NetBSD luiaard.13thmonkey.org 5.99.02 NetBSD 5.99.02 (DISKLESS.luiaard) #2:
Thu Nov 20 16:13:50 CET 2008
reinoud%heethoofdje.13thmonkey.org@localhost:/usr/sources/cvs.netbsd.org/src-nilfs/sys/arch/i386/compile/DISKLESS.luiaard
i386
Architecture: i386
Machine: i386
>Description:

A simple `ls' will panic a VNODE_LOCKDEBUG kernel on a correctly fresh
formatted FFS partition in readdir whereas this doesn't happen on LFS nor UDF.

It panics with
panic: vop_readdir: vp: locked 0, expected 1

Trace:
#3  0xc082feb1 in panic (fmt=0xc0cc8c20 "vop_readdir: vp: locked %d, expected
%d") at ../../../../kern/subr_prf.c:229
#4  0xc09ab4bc in VOP_READDIR (vp=0xc739f514, uio=0xc73a2c18, cred=0xc6266b40, 
eofflag=0xc73a2c14, cookies=0x0, ncookies=0x0) at 
../../../../kern/vnode_if.c:1182
#5  0xc0996828 in vn_readdir (fp=0xc7108a40, bf=0xbb90d000 <Address 0xbb90d000 
out of bounds>, segflg=0, count=4096, done=0xc73a2c7c, l=0xc738a840, 
cookies=0x0, ncookies=0x0) at ../../../../kern/vfs_vnops.c:394
#6  0xc0994f04 in sys___getdents30 (l=0xc738a840, uap=0xc73a2cf0, 
retval=0xc73a2ce8) at ../../../../kern/vfs_syscalls.c:3556
#7  0xc085c970 in sy_call (sy=0xc0d354a8, l=0xc738a840, uap=0xc73a2cf0, 
rval=0xc73a2ce8) at ../../../../sys/syscallvar.h:61
#8  0xc085c7f1 in syscall (frame=0xc73a2d48) at 
../../../../arch/i386/i386/syscall.c:112
#9  0xc010057c in syscall1 ()

        
>How-To-Repeat:

luiaard# newfs /dev/rwd0e
/dev/rwd0e: 9538.6MB (19534976 sectors) block size 16384, fragment size 2048
        using 52 cylinder groups of 183.44MB, 11740 blks, 23168 inodes.
super-block backups (for fsck_ffs -b #) at:
32, 375712, 751392, 1127072, 1502752, 1878432, 2254112, 2629792, 3005472, 
3381152, 3756832,
...............................................................................................
luiaard# 
luiaard# mount /dev/wd0e /mnt
luiaard# 
luiaard# ls /mnt
panic: vop_readdir: vp: locked 0, expected 1
entering kgdb

        
>Fix:
Disable VNODE_LOCKDEBUG :)

        

>Unformatted: