Re: [9fans] What do I need for a small 9P2000 server @ Linux ?

["Eric Van Hensbergen" <ericvh@gmail.com>]

On 6/28/07, Enrico Weigelt <weigelt@metux.de> wrote:
> The 9p driver in linux-2.6.19 (which currently is the latest
> stable in Gentoo) is some bit broken. First I had to fix the
> init function to abort if the result code if the called functions
> (ie. register_filesystem) is non-zero instead of zero ;o
> And if you're mounting the npfs or u9fs server and chdir into
> the mountpoint's subdir under the mountpoint itself, the process
> will hang (forever?). Obviously an recursion problem.
>

yeah - bad luck on that kernel -- I was a crappy maintainer and wasn't
doing proper regressions and some runtime bugs slipped in without me
seeing it.  You should be able to backport the fs/9p code from the
latest and greatest official kernel (not the v9fs devel directory)
without much trouble and things will be much more stable for you.

The recursive mount problem is something that you have to watch
yourself on -- single threaded file servers (like spfs and u9fs) will
just end up blocking indefinitely.  There are cases where you can
screw with multithreaded file servers and blow your kernel stack
recursing.  When it comes down to it, it is a misconfiguration, you
shouldn't loopback mount stuff in such a way that you recurse -- one
way around it is to always mount in a new namespace (which is what
Plan 9 does).  Without private name spaces there are no good solutions
which we could work out.

          -eric