Re: Network Shares disconnected by Network Manager

[Dan Williams <dcbw redhat com>]

On Wed, 2009-11-18 at 17:54 +0000, Neil Broadley wrote:
> 2009/11/17 Dan Williams <dcbw redhat com>
>         
>         On Mon, 2009-11-09 at 13:37 +0000, Neil Broadley wrote:
>         > Regarding Ubuntu launchpad bug :
>         >
>         https://bugs.launchpad.net/ubuntu/+source/samba/+bug/211631?comments=all
>         >
>         > (brief summary : During shutdown/restart, Network Manager
>         brings down
>         > wifi interface so quickly that remote samba filesystems in
>         fstab
>         > "hang" with the "CIFS VFS server not responding" error.)
>         >
>         > In comment 117, James asks :
>         > Would it be possible for NetworkManager to bring up & down
>         configured
>         > mount points as part of it's configuration settings? That
>         way, it
>         > unmounts just before bringing the network down and mounts
>         the
>         > filesystems after bring the network up ? A simple checkbox
>         would
>         > suffice e.g "Control Network Shares".
>         >
>         > Is this feasible, or on the Network Manager roadmap
>         already?  Note
>         > that this bug is only apparent on WIFI connected systems.  A
>         wired
>         > connection is apparently kept up long enough such that the
>         remote
>         > filesystems are unmounted cleanly.  Also ticking "Available
>         to all
>         > users" has no effect on this bug.  It would seem to require
>         some
>         > hacking of the Network Manager app itself and the way it
>         processes
>         > WIFI connections on shutdown/restart.
>         
>         
>         I think you're looking for pre-down scripts which are being
>         discussed.
>         WRT to the mount points, we have to be really careful to not
>         make
>         NetworkManager into an amoeba octopus so complex it falls
>         over.  Doing
>         mounts would best be done from dispatcher scripts or dbus
>         clients, or
>         even upstart triggers.
>         
>         NM provides the *event*, but there are so many use-cases that
>         the
>         mechanism should be provided by those cases, not
>         NetworkManager.
>         
>         Dan
>         
> 
> Magic, thanks, Dan.  I think you're referring to Mark Hedges post
> (http://mail.gnome.org/archives/networkmanager-list/2009-November/msg00088.html), so I'll follow that discussion.  Sadly, no replies as of yet though!

I'm getting to it :)

> I've already tried the dispatcher scripts in Ubuntu 9.10, but it
> appears that the lack of pre-down support means that the wifi
> connection is already long gone before they fire.  If support for
> pre-down scripts comes back, then I'll be able to call my
> umountcifs.sh script and handle the dismount cleanly.

Important to note that for wifi especially, your connection is more
likely to drop than for you to disconnect it yourself while in range of
the AP.  In that case the connection *will* already be gone and there's
nothing you can do about it; that's the nature of wifi.

It's probably still an open question as to whether pre-down scripts even
get run when the connection is already gone (wifi disconnect, pulled
cable, other event that NM cannot control) because most anything that a
script could do here in the case of network-already-down should be done
in post-down instead.

Dan

> Agree that NM shouldn't be all things to all people, but I did like
> the "concept" of James' suggestion for NM to manage shares.
> Implementing it in all use-cases would be a nightmare though, I
> suppose.
> 
> Neil.