[Samba] Unmountable Linux Samba mounts

[Rob Gillen]

Some of you might be familiar with the strange way that Linux will
sometimes disallow umount-ing or listing directory contents of a mounted
smb share, returning the error text, "Input/output error."  I believe
this error happens when a smb share is mounted, then that remote share
is removed.  This is a seriously annoying problem, because restarting
Samba does not solve the problem, nor does changing runlevels.  I am
guessing that it may be a kernel-level problem, so I am looking for more
information and possibly some confirmation on this.  I have tried
changing the runlevel to [S]ingle level user, which is running pretty
much nothing save kernel processes and a simple shell. At this level, a
'mount' command still shows the shares to be mounted, and also at this
level it is still impossible to umount them.  The only solution that I
have found so far is rebooting, which I think is an unacceptable way to
handle such a problem.

On a possibly related side note, during the time that I could not remove
the unmountable mounted smb shares, the dhcpd daemon that was running on
the box also seemed to start malfunctioning.  On the Linux box
(Mandrake), everything appeared to be fine; that is, I was able to
restart the dhcpd daemon without any errors.  But none of the other
networked machines which normally get served addresses from it were
getting addresses.  Unfortunately, I wasn't able to sniff packets, so I
don't know what kind of communication (or lack thereof) was occurring,
but it did seem like network traffic was being blocked in the Linux box
from something.  It was a frustrating exercise trying to figure out why
my other boxes were not getting addresses.  Strangely enough, after I
rebooted the Mandrake box, everything worked as normal again, and the
other boxes got their IP addresses fine.

Like I said, I don't know for sure if the dhcpd thing was related to the
smb mount problem, but I'll try to repeat the problem when I get some
time and see if it recurs.  If anybody has seen the same problem or
something similar, I would appreciate it if you could share how you
resolved it.  As I also said, this might be strictly a Linux related
problem.  I don't have any other platforms to test it out on.

Thanks,
Rob