On Fri, 26 Jan 2024, Chuck Lever III wrote: > > > > On Jan 25, 2024, at 5:44 PM, NeilBrown <neilb@xxxxxxx> wrote: > > > > On Thu, 25 Jan 2024, Chuck Lever III wrote: > >> > >> > >>> On Jan 24, 2024, at 6:24 AM, Jeff Layton <jlayton@xxxxxxxxxx> wrote: > >>> > >>> On Wed, 2024-01-24 at 10:52 +0100, Lorenzo Bianconi wrote: > >>>> [...] > >>>>> > >>>>> That's a great question. We do need to properly support the -H option to > >>>>> rpc.nfsd. What we do today is look up the hostname or address using > >>>>> getaddrinfo, and then open a listening socket for that address and then > >>>>> pass that fd down to the kernel, which I think then takes the socket and > >>>>> sticks it on sv_permsocks. > >>>>> > >>>>> All of that seems a bit klunky. Ideally, I'd say the best thing would be > >>>>> to allow userland to pass the sockaddr we look up directly via netlink, > >>>>> and then let the kernel open the socket. That will probably mean > >>>>> refactoring some of the svc_xprt_create machinery to take a sockaddr, > >>>>> but I don't think it looks too hard to do. > >>>> > >>>> Do we already have a specific use case for it? I think we can even add it > >>>> later when we have a defined use case for it on top of the current series. > >>>> > >>> > >>> Yes: > >>> > >>> rpc.nfsd -H makes nfsd listen on a particular address and port. By > >>> passing down the sockaddr instead of an already-opened socket > >>> descriptor, we can achieve the goal without having to open sockets in > >>> userland. > >> > >> Tearing down a listener that was created that way would be a > >> use case for: > > > > Only if it was actually useful. > > Have you *ever* wanted to do that? Or heard from anyone else who did? > > Container shutdown will want to clear out any listener > that might have been created during the container's > lifetime. How is that done today? Is that simply handled > by net namespace tear-down? Yes. When the last thread in a netns exits, nfsd_last_thread() is called which closes all sockets. NeilBrown
