Re: [PATCH v2 3/5] SUNRPC: make RPC service dependable on rpcbind clients creation

Jeff Layton
2011-09-09T19:01:17Z

On Fri, 09 Sep 2011 14:44:34 -0400
Trond Myklebust <Trond.Myklebust@netapp.com> wrote:

> On Fri, 2011-09-09 at 20:41 +0400, Stanislav Kinsbursky wrote:
> > 09.09.2011 18:07, Jeff Layton пишет:
> > > On Fri, 09 Sep 2011 16:08:44 +0400
> > > Stanislav Kinsbursky<skinsbursky@parallels.com> wrote:
> > >
> > >> Create rcbind clients or increase rpcbind users counter during RPC service
> > >> creation and decrease this counter (and possibly destroy those clients) on RPC
> > >> service destruction.
> > >>
> > >> Signed-off-by: Stanislav Kinsbursky<skinsbursky@parallels.com>
> > >>
> > >> ---
> > >> include/linux/sunrpc/clnt.h | 2 ++
> > >> net/sunrpc/rpcb_clnt.c | 2 +-
> > >> net/sunrpc/svc.c | 13 +++++++++++--
> > >> 3 files changed, 14 insertions(+), 3 deletions(-)
> > >>
> > >> diff --git a/include/linux/sunrpc/clnt.h b/include/linux/sunrpc/clnt.h
> > >> index db7bcaf..65a8115 100644
> > >> --- a/include/linux/sunrpc/clnt.h
> > >> +++ b/include/linux/sunrpc/clnt.h
> > >> @@ -135,10 +135,12 @@ void rpc_shutdown_client(struct rpc_clnt *);
> > >> void rpc_release_client(struct rpc_clnt *);
> > >> void rpc_task_release_client(struct rpc_task *);
> > >>
> > >> +int rpcb_create_local(void);
> > >> int rpcb_register(u32, u32, int, unsigned short);
> > >> int rpcb_v4_register(const u32 program, const u32 version,
> > >> const struct sockaddr *address,
> > >> const char *netid);
> > >> +void rpcb_put_local(void);
> > >> void rpcb_getport_async(struct rpc_task *);
> > >>
> > >> void rpc_call_start(struct rpc_task *);
> > >> diff --git a/net/sunrpc/rpcb_clnt.c b/net/sunrpc/rpcb_clnt.c
> > >> index b4cc0f1..437ec60 100644
> > >> --- a/net/sunrpc/rpcb_clnt.c
> > >> +++ b/net/sunrpc/rpcb_clnt.c
> > >> @@ -318,7 +318,7 @@ out:
> > >> * Returns zero on success, otherwise a negative errno value
> > >> * is returned.
> > >> */
> > >> -static int rpcb_create_local(void)
> > >> +int rpcb_create_local(void)
> > >> {
> > >> static DEFINE_MUTEX(rpcb_create_local_mutex);
> > >> int result = 0;
> > >> diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c
> > >> index 6a69a11..9095c0e 100644
> > >> --- a/net/sunrpc/svc.c
> > >> +++ b/net/sunrpc/svc.c
> > >> @@ -367,8 +367,11 @@ __svc_create(struct svc_program *prog, unsigned int bufsize, int npools,
> > >> unsigned int xdrsize;
> > >> unsigned int i;
> > >>
> > >> - if (!(serv = kzalloc(sizeof(*serv), GFP_KERNEL)))
> > >> + if (rpcb_create_local()< 0)
> > >> return NULL;
> > >> +
> > >> + if (!(serv = kzalloc(sizeof(*serv), GFP_KERNEL)))
> > >> + goto out_err;
> > >> serv->sv_name = prog->pg_name;
> > >> serv->sv_program = prog;
> > >> serv->sv_nrthreads = 1;
> > >> @@ -403,7 +406,7 @@ __svc_create(struct svc_program *prog, unsigned int bufsize, int npools,
> > >> GFP_KERNEL);
> > >> if (!serv->sv_pools) {
> > >> kfree(serv);
> > >> - return NULL;
> > >> + goto out_err;
> > >> }
> > >>
> > >> for (i = 0; i< serv->sv_nrpools; i++) {
> > >> @@ -423,6 +426,10 @@ __svc_create(struct svc_program *prog, unsigned int bufsize, int npools,
> > >> svc_unregister(serv);
> > >>
> > >> return serv;
> > >> +
> > >> +out_err:
> > >> + rpcb_put_local();
> > >> + return NULL;
> > >> }
> > >>
> > >> struct svc_serv *
> > >> @@ -491,6 +498,8 @@ svc_destroy(struct svc_serv *serv)
> > >> svc_unregister(serv);
> > >> kfree(serv->sv_pools);
> > >> kfree(serv);
> > >> +
> > >> + rpcb_put_local();
> > >> }
> > >> EXPORT_SYMBOL_GPL(svc_destroy);
> > >>
> > >>
> > >
> > > I don't get it -- what's the advantage of creating rpcbind clients in
> > > __svc_create vs. the old way of creating them just before we plan to
> > > use them?
> > >
> >
> > The main problem here is not in creation, but in destroying those clients.
> > Now rpcbind clients are created during rpcb_register(). I.e. once per every family, program version and so on.
> > But can be unregistered for all protocol families by one call. So it's impossible to put reference counting for those clients in the place, where they are created now.
>
> Could we perhaps set up a 'struct pernet_operations' to create a
> destructor for them?
>

An even easier idea might be to just not take a reference to the
rpcbind client for svc_programs that have vs_hidden set on every
version.

--
Jeff Layton <jlayton@redhat.com>