Re: [sshfs] SSHFS gets stuck if connection is lost

[Thue J. K. <th...@gm...>]

I just tried starting both sshfs and a normal openssh sftp client at the
same time, both against the same server, as an experiment.

When I rebooted the remote server, the ssh client said "Connection to
thuejk.dk closed by remote host.". The sshfs mount didn't say anything, and
will still hang any "ls" command which tries to read from the sshfs mount
point.

At least in this case, it seems that sshfs should know that the other end is
going away permanently, but fails to act appropriately.

Regards, Thue

2011/1/24 Miklos Szeredi <mi...@sz...>

> On Fri, 21 Jan 2011, Thue Janus Kristensen wrote:
> > If I have an SSHFS-mounted filesystem and the established sftp-connection
> > becomes invalid, for example if I restart my router, SSHFS bugs out. For
> > example, if I try to do a ls of the mounted directory, the ls hangs
> forever.
> >
> > Why doesn't SSHFS automatically unmount the now invalid mount point, or
> at
> > least return a read error to ls?
>
> SSHFS doesn't know, it uses ssh, which in turns uses TCP sockets,
> which behave badly in the presense of dynamic IP.
>
> The solution would be to give sshfs a timeout after which it kills the
> hanging ssh connection and starts up a new one.
>
> Returning an error may not be the right thing, the network might just
> be down temporarily.  Unfortunately there's no way to differentiate a
> temporary network outage from a changed IP address in the router,
> which will cause TCP connections to hang "permanently".
>
> Thanks,
> Miklos
>