> On Nov 23, 2015, at 7:44 PM, Tom Talpey <[email protected]> wrote: > > On 11/23/2015 5:20 PM, Chuck Lever wrote: >> To support the NFSv4.1 backchannel on RDMA connections, add a >> capability for receiving an RPC/RDMA reply on a connection >> established by a client. >> >> Signed-off-by: Chuck Lever <[email protected]> >> --- >> net/sunrpc/xprtrdma/rpc_rdma.c | 76 >> +++++++++++++++++++++++++++++++ >> net/sunrpc/xprtrdma/svc_rdma_recvfrom.c | 60 ++++++++++++++++++++++++ >> net/sunrpc/xprtrdma/xprt_rdma.h | 4 ++ >> 3 files changed, 140 insertions(+) >> >> diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c >> index c10d969..fef0623 100644 >> --- a/net/sunrpc/xprtrdma/rpc_rdma.c >> +++ b/net/sunrpc/xprtrdma/rpc_rdma.c >> @@ -946,3 +946,79 @@ repost: >> if (rpcrdma_ep_post_recv(&r_xprt->rx_ia, &r_xprt->rx_ep, rep)) >> rpcrdma_recv_buffer_put(rep); >> } >> + >> +#if defined(CONFIG_SUNRPC_BACKCHANNEL) >> + >> +int >> +rpcrdma_handle_bc_reply(struct rpc_xprt *xprt, struct rpcrdma_msg *rmsgp, >> + struct xdr_buf *rcvbuf) >> +{ >> + struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt); >> + struct kvec *dst, *src = &rcvbuf->head[0]; >> + struct rpc_rqst *req; >> + unsigned long cwnd; >> + u32 credits; >> + size_t len; >> + __be32 xid; >> + __be32 *p; >> + int ret; >> + >> + p = (__be32 *)src->iov_base; >> + len = src->iov_len; >> + xid = rmsgp->rm_xid; >> + >> + pr_info("%s: xid=%08x, length=%zu\n", >> + __func__, be32_to_cpu(xid), len); >> + pr_info("%s: RPC/RDMA: %*ph\n", >> + __func__, (int)RPCRDMA_HDRLEN_MIN, rmsgp); >> + pr_info("%s: RPC: %*ph\n", >> + __func__, (int)len, p); >> + >> + ret = -EAGAIN; >> + if (src->iov_len < 24) >> + goto out_shortreply; >> + >> + spin_lock_bh(&xprt->transport_lock); >> + req = xprt_lookup_rqst(xprt, xid); >> + if (!req) >> + goto out_notfound; >> + >> + dst = &req->rq_private_buf.head[0]; >> + memcpy(&req->rq_private_buf, &req->rq_rcv_buf, sizeof(struct xdr_buf)); >> + if (dst->iov_len < len) >> + goto out_unlock; >> + memcpy(dst->iov_base, p, len); >> + >> + credits = be32_to_cpu(rmsgp->rm_credit); >> + if (credits == 0) >> + credits = 1; /* don't deadlock */ >> + else if (credits > r_xprt->rx_buf.rb_bc_max_requests) >> + credits = r_xprt->rx_buf.rb_bc_max_requests; >> + >> + cwnd = xprt->cwnd; >> + xprt->cwnd = credits << RPC_CWNDSHIFT; >> + if (xprt->cwnd > cwnd) >> + xprt_release_rqst_cong(req->rq_task); >> + >> + ret = 0; >> + xprt_complete_rqst(req->rq_task, rcvbuf->len); >> + rcvbuf->len = 0; >> + >> +out_unlock: >> + spin_unlock_bh(&xprt->transport_lock); >> +out: >> + return ret; >> + >> +out_shortreply: >> + pr_info("svcrdma: short bc reply: xprt=%p, len=%zu\n", >> + xprt, src->iov_len); >> + goto out; >> + >> +out_notfound: >> + pr_info("svcrdma: unrecognized bc reply: xprt=%p, xid=%08x\n", >> + xprt, be32_to_cpu(xid)); >> + >> + goto out_unlock; >> +} >> + >> +#endif /* CONFIG_SUNRPC_BACKCHANNEL */ >> diff --git a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c >> b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c >> index ff4f01e..2b762b5 100644 >> --- a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c >> +++ b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c >> @@ -47,6 +47,7 @@ >> #include <rdma/ib_verbs.h> >> #include <rdma/rdma_cm.h> >> #include <linux/sunrpc/svc_rdma.h> >> +#include "xprt_rdma.h" >> >> #define RPCDBG_FACILITY RPCDBG_SVCXPRT >> >> @@ -567,6 +568,42 @@ static int rdma_read_complete(struct svc_rqst *rqstp, >> return ret; >> } >> >> +#if defined(CONFIG_SUNRPC_BACKCHANNEL) >> + >> +/* By convention, backchannel calls arrive via rdma_msg type >> + * messages, and never populate the chunk lists. This makes >> + * the RPC/RDMA header small and fixed in size, so it is >> + * straightforward to check the RPC header's direction field. >> + */ >> +static bool >> +svc_rdma_is_backchannel_reply(struct svc_xprt *xprt, struct rpcrdma_msg >> *rmsgp) >> +{ >> + __be32 *p = (__be32 *)rmsgp; >> + >> + if (!xprt->xpt_bc_xprt) >> + return false; >> + >> + if (rmsgp->rm_type != rdma_msg) >> + return false; >> + if (rmsgp->rm_body.rm_chunks[0] != xdr_zero) >> + return false; >> + if (rmsgp->rm_body.rm_chunks[1] != xdr_zero) >> + return false; >> + if (rmsgp->rm_body.rm_chunks[2] != xdr_zero) >> + return false; > > The above assertion is only true for the NFS behavior as spec'd > today (no chunk-bearing bulk data on existing backchannel NFS > protocol messages). That at least deserves a comment.
Not sure what you mean: https://datatracker.ietf.org/doc/draft-ietf-nfsv4-rpcrdma-bidirection/ says a chunk-less message is how a backward RPC reply goes over RPC/RDMA. NFS is not in the picture here. > Or, why > not simply ignore the chunks? They're not the receiver's problem. This check is done before the chunks are parsed. The point is the receiver has to verify that the RPC-over-RDMA header is the small, fix-sized kind _first_ before it can go look at the CALLDIR field in the RPC header. >> + >> + /* sanity */ >> + if (p[7] != rmsgp->rm_xid) >> + return false; >> + /* call direction */ >> + if (p[8] == cpu_to_be32(RPC_CALL)) >> + return false; >> + >> + return true; >> +} >> + >> +#endif /* CONFIG_SUNRPC_BACKCHANNEL */ >> + >> /* >> * Set up the rqstp thread context to point to the RQ buffer. If >> * necessary, pull additional data from the client with an RDMA_READ >> @@ -632,6 +669,17 @@ int svc_rdma_recvfrom(struct svc_rqst *rqstp) >> goto close_out; >> } >> >> +#if defined(CONFIG_SUNRPC_BACKCHANNEL) >> + if (svc_rdma_is_backchannel_reply(xprt, rmsgp)) { >> + ret = rpcrdma_handle_bc_reply(xprt->xpt_bc_xprt, rmsgp, >> + &rqstp->rq_arg); >> + svc_rdma_put_context(ctxt, 0); >> + if (ret) >> + goto repost; >> + return ret; >> + } >> +#endif >> + >> /* Read read-list data. */ >> ret = rdma_read_chunks(rdma_xprt, rmsgp, rqstp, ctxt); >> if (ret > 0) { >> @@ -668,4 +716,16 @@ int svc_rdma_recvfrom(struct svc_rqst *rqstp) >> set_bit(XPT_CLOSE, &xprt->xpt_flags); >> defer: >> return 0; >> + >> +#if defined(CONFIG_SUNRPC_BACKCHANNEL) >> +repost: >> + ret = svc_rdma_post_recv(rdma_xprt); >> + if (ret) { >> + pr_info("svcrdma: could not post a receive buffer, err=%d." >> + "Closing transport %p.\n", ret, rdma_xprt); >> + set_bit(XPT_CLOSE, &rdma_xprt->sc_xprt.xpt_flags); >> + ret = -ENOTCONN; >> + } >> + return ret; >> +#endif >> } >> diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h >> b/net/sunrpc/xprtrdma/xprt_rdma.h >> index ac7f8d4..9aeff2b 100644 >> --- a/net/sunrpc/xprtrdma/xprt_rdma.h >> +++ b/net/sunrpc/xprtrdma/xprt_rdma.h >> @@ -309,6 +309,8 @@ struct rpcrdma_buffer { >> u32 rb_bc_srv_max_requests; >> spinlock_t rb_reqslock; /* protect rb_allreqs */ >> struct list_head rb_allreqs; >> + >> + u32 rb_bc_max_requests; >> }; >> #define rdmab_to_ia(b) (&container_of((b), struct rpcrdma_xprt, >> rx_buf)->rx_ia) >> >> @@ -511,6 +513,8 @@ void rpcrdma_reply_handler(struct rpcrdma_rep *); >> * RPC/RDMA protocol calls - xprtrdma/rpc_rdma.c >> */ >> int rpcrdma_marshal_req(struct rpc_rqst *); >> +int rpcrdma_handle_bc_reply(struct rpc_xprt *, struct rpcrdma_msg *, >> + struct xdr_buf *); >> >> /* RPC/RDMA module init - xprtrdma/transport.c >> */ >> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-nfs" in >> the body of a message to [email protected] >> More majordomo info at http://vger.kernel.org/majordomo-info.html >> >> > -- > To unsubscribe from this list: send the line "unsubscribe linux-nfs" in > the body of a message to [email protected] > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Chuck Lever -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
