Re: ufs_dirbad: /mnt: bad dir ino 50626 at offset 0: mangled entry

On Fri, Oct 22, 2021 at 10:36:01AM -0400, mike tancsa wrote:
> In one of my VMs, I do a bunch of testing to a nano image on /dev/md0 
> and increasingly I am getting a panic on umounting the file system
> 
> The image is just
> 
> truncate -s 5G /tmp/junk.bin
> mdconfig -f /tmp/junk.bin
> 
> and then I dd my nano image, mount it, make some configuration changes 
> and then umount it.
> 
> After cycles of this, unmounts, mounts etc, I get
> 
> 
> panic: ufs_dirbad: /mnt: bad dir ino 50626 at offset 0: mangled entry
> cpuid = 1
> time = 1634912598
> KDB: stack backtrace:
> #0 0xffffffff80c77035 at kdb_backtrace+0x65
> #1 0xffffffff80c28a47 at vpanic+0x187
> #2 0xffffffff80c288b3 at panic+0x43
> #3 0xffffffff80f345f7 at ufs_lookup_ino+0xdc7
> #4 0xffffffff80ceae1d at vfs_cache_lookup+0xad
> #5 0xffffffff80cf872c at lookup+0x46c
> #6 0xffffffff80cf785c at namei+0x26c
> #7 0xffffffff80d1c979 at vn_open_cred+0x509
> #8 0xffffffff80d12a3e at kern_openat+0x26e
> #9 0xffffffff810b4d3c at amd64_syscall+0x10c
> #10 0xffffffff8108bdab at fast_syscall_common+0xf8
> Uptime: 4m48s
> 
> I forced an fsck on reboot, and the file system is clean. I also deleted 
> /mnt and recreated the directory and still get this issue.  Any idea 
> what might be causing it or how I can better track it down ?

Is the VM image stored on ZFS?  Which kernel revision is the host running?