Re: [PATCH] NFSD: Keep existing listners on portlist error

["J. Bruce Fields" <bfields@fieldses.org>]

On Wed, Oct 06, 2021 at 10:43:14AM -0400, Benjamin Coddington wrote:
> On 6 Oct 2021, at 10:33, J. Bruce Fields wrote:
> 
> >On Wed, Oct 06, 2021 at 10:18:05AM -0400, Benjamin Coddington wrote:
> >>If nfsd has existing listening sockets without any processes,
> >>then an error
> >>returned from svc_create_xprt() for an additional transport will
> >>remove
> >>those existing listeners.  We're seeing this in practice when
> >>userspace
> >>attempts to create rpcrdma transports without having the rpcrdma
> >>modules
> >>present before creating nfsd kernel processes.  Fix this by
> >>checking for
> >>existing sockets before callingn nfsd_destroy().
> >
> >That seems like an improvement.
> >
> >I'm curious, though, what the rpc.nfsd behavior is on partial failure.
> >And what do we want it to be?
> >
> >If a user runs rpc.nfsd expecting it to start up tcp and rdma, but
> >rdma
> >fails, do we want rpc.nfsd to succeed or fail?  Should it exit
> >with nfsd
> >running or not?
> 
> I lean toward having it fail - but I think that's a different patch for
> rpc.nfsd.  Right now rpc.nfsd exists without error, but you end up
> without
> any listeners at all.
> 
> Do you want a patch for rpc.nfsd instead?

I think we need the kernel fix.  I agree that it's weird to shut down
the server on a failure to add a listener--better to leave usrespace to
decide if it wants to do that.

--b.