1 files changed, 103 insertions, 45 deletions

diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c
index bc8bd6577467..c10d9699441c 100644
--- a/net/sunrpc/xprtrdma/rpc_rdma.c
+++ b/net/sunrpc/xprtrdma/rpc_rdma.c
@@ -441,6 +441,11 @@ rpcrdma_marshal_req(struct rpc_rqst *rqst)
 	enum rpcrdma_chunktype rtype, wtype;
 	struct rpcrdma_msg *headerp;
 
+#if defined(CONFIG_SUNRPC_BACKCHANNEL)
+	if (test_bit(RPC_BC_PA_IN_USE, &rqst->rq_bc_pa_state))
+		return rpcrdma_bc_marshal_reply(rqst);
+#endif
+
 	/*
 	 * rpclen gets amount of data in first buffer, which is the
 	 * pre-registered buffer.
@@ -711,6 +716,37 @@ rpcrdma_connect_worker(struct work_struct *work)
 	spin_unlock_bh(&xprt->transport_lock);
 }
 
+#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
+rpcrdma_is_bcall(struct rpcrdma_msg *headerp)
+{
+	__be32 *p = (__be32 *)headerp;
+
+	if (headerp->rm_type != rdma_msg)
+		return false;
+	if (headerp->rm_body.rm_chunks[0] != xdr_zero)
+		return false;
+	if (headerp->rm_body.rm_chunks[1] != xdr_zero)
+		return false;
+	if (headerp->rm_body.rm_chunks[2] != xdr_zero)
+		return false;
+
+	/* sanity */
+	if (p[7] != headerp->rm_xid)
+		return false;
+	/* call direction */
+	if (p[8] != cpu_to_be32(RPC_CALL))
+		return false;
+
+	return true;
+}
+#endif	/* CONFIG_SUNRPC_BACKCHANNEL */
+
 /*
  * This function is called when an async event is posted to
  * the connection which changes the connection state. All it
@@ -723,8 +759,8 @@ rpcrdma_conn_func(struct rpcrdma_ep *ep)
 	schedule_delayed_work(&ep->rep_connect_worker, 0);
 }
 
-/*
- * Called as a tasklet to do req/reply match and complete a request
+/* Process received RPC/RDMA messages.
+ *
  * Errors must result in the RPC task either being awakened, or
  * allowed to timeout, to discover the errors at that time.
  */
@@ -741,52 +777,32 @@ rpcrdma_reply_handler(struct rpcrdma_rep *rep)
 	unsigned long cwnd;
 	u32 credits;
 
-	/* Check status. If bad, signal disconnect and return rep to pool */
-	if (rep->rr_len == ~0U) {
-		rpcrdma_recv_buffer_put(rep);
-		if (r_xprt->rx_ep.rep_connected == 1) {
-			r_xprt->rx_ep.rep_connected = -EIO;
-			rpcrdma_conn_func(&r_xprt->rx_ep);
-		}
-		return;
-	}
-	if (rep->rr_len < RPCRDMA_HDRLEN_MIN) {
-		dprintk("RPC:       %s: short/invalid reply\n", __func__);
-		goto repost;
-	}
+	dprintk("RPC:       %s: incoming rep %p\n", __func__, rep);
+
+	if (rep->rr_len == RPCRDMA_BAD_LEN)
+		goto out_badstatus;
+	if (rep->rr_len < RPCRDMA_HDRLEN_MIN)
+		goto out_shortreply;
+
 	headerp = rdmab_to_msg(rep->rr_rdmabuf);
-	if (headerp->rm_vers != rpcrdma_version) {
-		dprintk("RPC:       %s: invalid version %d\n",
-			__func__, be32_to_cpu(headerp->rm_vers));
-		goto repost;
-	}
+	if (headerp->rm_vers != rpcrdma_version)
+		goto out_badversion;
+#if defined(CONFIG_SUNRPC_BACKCHANNEL)
+	if (rpcrdma_is_bcall(headerp))
+		goto out_bcall;
+#endif
 
-	/* Get XID and try for a match. */
-	spin_lock(&xprt->transport_lock);
+	/* Match incoming rpcrdma_rep to an rpcrdma_req to
+	 * get context for handling any incoming chunks.
+	 */
+	spin_lock_bh(&xprt->transport_lock);
 	rqst = xprt_lookup_rqst(xprt, headerp->rm_xid);
-	if (rqst == NULL) {
-		spin_unlock(&xprt->transport_lock);
-		dprintk("RPC:       %s: reply 0x%p failed "
-			"to match any request xid 0x%08x len %d\n",
-			__func__, rep, be32_to_cpu(headerp->rm_xid),
-			rep->rr_len);
-repost:
-		r_xprt->rx_stats.bad_reply_count++;
-		if (rpcrdma_ep_post_recv(&r_xprt->rx_ia, &r_xprt->rx_ep, rep))
-			rpcrdma_recv_buffer_put(rep);
+	if (!rqst)
+		goto out_nomatch;
 
-		return;
-	}
-
-	/* get request object */
 	req = rpcr_to_rdmar(rqst);
-	if (req->rl_reply) {
-		spin_unlock(&xprt->transport_lock);
-		dprintk("RPC:       %s: duplicate reply 0x%p to RPC "
-			"request 0x%p: xid 0x%08x\n", __func__, rep, req,
-			be32_to_cpu(headerp->rm_xid));
-		goto repost;
-	}
+	if (req->rl_reply)
+		goto out_duplicate;
 
 	dprintk("RPC:       %s: reply 0x%p completes request 0x%p\n"
 		"                   RPC request 0x%p xid 0x%08x\n",
@@ -883,8 +899,50 @@ badheader:
 	if (xprt->cwnd > cwnd)
 		xprt_release_rqst_cong(rqst->rq_task);
 
+	xprt_complete_rqst(rqst->rq_task, status);
+	spin_unlock_bh(&xprt->transport_lock);
 	dprintk("RPC:       %s: xprt_complete_rqst(0x%p, 0x%p, %d)\n",
 			__func__, xprt, rqst, status);
-	xprt_complete_rqst(rqst->rq_task, status);
-	spin_unlock(&xprt->transport_lock);
+	return;
+
+out_badstatus:
+	rpcrdma_recv_buffer_put(rep);
+	if (r_xprt->rx_ep.rep_connected == 1) {
+		r_xprt->rx_ep.rep_connected = -EIO;
+		rpcrdma_conn_func(&r_xprt->rx_ep);
+	}
+	return;
+
+#if defined(CONFIG_SUNRPC_BACKCHANNEL)
+out_bcall:
+	rpcrdma_bc_receive_call(r_xprt, rep);
+	return;
+#endif
+
+out_shortreply:
+	dprintk("RPC:       %s: short/invalid reply\n", __func__);
+	goto repost;
+
+out_badversion:
+	dprintk("RPC:       %s: invalid version %d\n",
+		__func__, be32_to_cpu(headerp->rm_vers));
+	goto repost;
+
+out_nomatch:
+	spin_unlock_bh(&xprt->transport_lock);
+	dprintk("RPC:       %s: no match for incoming xid 0x%08x len %d\n",
+		__func__, be32_to_cpu(headerp->rm_xid),
+		rep->rr_len);
+	goto repost;
+
+out_duplicate:
+	spin_unlock_bh(&xprt->transport_lock);
+	dprintk("RPC:       %s: "
+		"duplicate reply %p to RPC request %p: xid 0x%08x\n",
+		__func__, rep, req, be32_to_cpu(headerp->rm_xid));
+
+repost:
+	r_xprt->rx_stats.bad_reply_count++;
+	if (rpcrdma_ep_post_recv(&r_xprt->rx_ia, &r_xprt->rx_ep, rep))
+		rpcrdma_recv_buffer_put(rep);
 }