On Jul 17, 2014, at 2:36 PM, J. Bruce Fields <bfields@xxxxxxxxxxxx> wrote: > On Wed, Jul 16, 2014 at 03:38:32PM -0400, Chuck Lever wrote: >> The current code always selects XPRT_TRANSPORT_BC_TCP for the back >> channel, even when the forward channel was not TCP (eg, RDMA). When >> a 4.1 mount is attempted with RDMA, the server panics in the TCP BC >> code when trying to send CB_NULL. >> >> Instead, construct the transport protocol number from the forward >> channel transport or'd with XPRT_TRANSPORT_BC. Transports that do >> not support bi-directional RPC will not have registered a "BC" >> transport, causing create_backchannel_client() to fail immediately. >> >> Fixes: https://bugzilla.linux-nfs.org/show_bug.cgi?id=265 >> Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx> >> --- >> Hi Bruce- >> >> What do you think of this approach? > > OK by me. (So clients use a separate tcp connection for the > backchannel?) Right. The current plan is that, for NFSv4.1 over RDMA, the Linux client will create an additional TCP connection and bind it to the same session as the RDMA transport. The TCP connection will be used solely for callback operations. The forward channel on that connection will not be used, except for BIND_CONN_TO_SESSION operations. > --b. > >> >> >> fs/nfsd/nfs4callback.c | 3 ++- >> include/linux/sunrpc/svc_xprt.h | 1 + >> net/sunrpc/svcsock.c | 2 ++ >> net/sunrpc/xprt.c | 2 +- >> net/sunrpc/xprtrdma/svc_rdma_transport.c | 1 + >> 5 files changed, 7 insertions(+), 2 deletions(-) >> >> diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c >> index 2c73cae..0f23ad0 100644 >> --- a/fs/nfsd/nfs4callback.c >> +++ b/fs/nfsd/nfs4callback.c >> @@ -689,7 +689,8 @@ static int setup_callback_client(struct nfs4_client *clp, struct nfs4_cb_conn *c >> clp->cl_cb_session = ses; >> args.bc_xprt = conn->cb_xprt; >> args.prognumber = clp->cl_cb_session->se_cb_prog; >> - args.protocol = XPRT_TRANSPORT_BC_TCP; >> + args.protocol = conn->cb_xprt->xpt_class->xcl_ident | >> + XPRT_TRANSPORT_BC; >> args.authflavor = ses->se_cb_sec.flavor; >> } >> /* Create RPC client */ >> diff --git a/include/linux/sunrpc/svc_xprt.h b/include/linux/sunrpc/svc_xprt.h >> index 7235040..5d9d6f8 100644 >> --- a/include/linux/sunrpc/svc_xprt.h >> +++ b/include/linux/sunrpc/svc_xprt.h >> @@ -33,6 +33,7 @@ struct svc_xprt_class { >> struct svc_xprt_ops *xcl_ops; >> struct list_head xcl_list; >> u32 xcl_max_payload; >> + int xcl_ident; >> }; >> >> /* >> diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c >> index b507cd3..b2437ee 100644 >> --- a/net/sunrpc/svcsock.c >> +++ b/net/sunrpc/svcsock.c >> @@ -692,6 +692,7 @@ static struct svc_xprt_class svc_udp_class = { >> .xcl_owner = THIS_MODULE, >> .xcl_ops = &svc_udp_ops, >> .xcl_max_payload = RPCSVC_MAXPAYLOAD_UDP, >> + .xcl_ident = XPRT_TRANSPORT_UDP, >> }; >> >> static void svc_udp_init(struct svc_sock *svsk, struct svc_serv *serv) >> @@ -1292,6 +1293,7 @@ static struct svc_xprt_class svc_tcp_class = { >> .xcl_owner = THIS_MODULE, >> .xcl_ops = &svc_tcp_ops, >> .xcl_max_payload = RPCSVC_MAXPAYLOAD_TCP, >> + .xcl_ident = XPRT_TRANSPORT_TCP, >> }; >> >> void svc_init_xprt_sock(void) >> diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c >> index c3b2b33..51c6316 100644 >> --- a/net/sunrpc/xprt.c >> +++ b/net/sunrpc/xprt.c >> @@ -1306,7 +1306,7 @@ struct rpc_xprt *xprt_create_transport(struct xprt_create *args) >> } >> } >> spin_unlock(&xprt_list_lock); >> - printk(KERN_ERR "RPC: transport (%d) not supported\n", args->ident); >> + dprintk("RPC: transport (%d) not supported\n", args->ident); >> return ERR_PTR(-EIO); >> >> found: >> diff --git a/net/sunrpc/xprtrdma/svc_rdma_transport.c b/net/sunrpc/xprtrdma/svc_rdma_transport.c >> index e7323fb..06a5d92 100644 >> --- a/net/sunrpc/xprtrdma/svc_rdma_transport.c >> +++ b/net/sunrpc/xprtrdma/svc_rdma_transport.c >> @@ -92,6 +92,7 @@ struct svc_xprt_class svc_rdma_class = { >> .xcl_owner = THIS_MODULE, >> .xcl_ops = &svc_rdma_ops, >> .xcl_max_payload = RPCSVC_MAXPAYLOAD_TCP, >> + .xcl_ident = XPRT_TRANSPORT_RDMA, >> }; >> >> struct svc_rdma_op_ctxt *svc_rdma_get_context(struct svcxprt_rdma *xprt) >> -- Chuck Lever chuck[dot]lever[at]oracle[dot]com -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
