svcrdma: Add a service to register a Fast Reg MR with the device

Fast Reg MR introduces a new WR type. Add a service to register the
region with the adapter and update the completion handling to support
completions with a NULL WR context.
Signed-off-by: Tom Tucker <tom@opengridcomputing.com>

include/linux/sunrpc/svc_rdma.h

@@ -214,6 +214,7 @@ extern struct svc_rdma_op_ctxt *svc_rdma_get_context(struct svcxprt_rdma *);
 extern void svc_rdma_put_context(struct svc_rdma_op_ctxt *, int);
 extern struct svc_rdma_req_map *svc_rdma_get_req_map(void);
 extern void svc_rdma_put_req_map(struct svc_rdma_req_map *);
+extern int svc_rdma_fastreg(struct svcxprt_rdma *, struct svc_rdma_fastreg_mr *);
 extern struct svc_rdma_fastreg_mr *svc_rdma_get_frmr(struct svcxprt_rdma *);
 extern void svc_rdma_put_frmr(struct svcxprt_rdma *,
 			      struct svc_rdma_fastreg_mr *);

net/sunrpc/xprtrdma/svc_rdma_transport.c

@@ -326,35 +326,12 @@ static void rq_cq_reap(struct svcxprt_rdma *xprt)
 }
 
 /*
- * Send Queue Completion Handler - potentially called on interrupt context.
- *
- * Note that caller must hold a transport reference.
+ * Processs a completion context
  */
-static void sq_cq_reap(struct svcxprt_rdma *xprt)
+static void process_context(struct svcxprt_rdma *xprt,
+			    struct svc_rdma_op_ctxt *ctxt)
 {
-	struct svc_rdma_op_ctxt *ctxt = NULL;
-	struct ib_wc wc;
-	struct ib_cq *cq = xprt->sc_sq_cq;
-	int ret;
-
-
-	if (!test_and_clear_bit(RDMAXPRT_SQ_PENDING, &xprt->sc_flags))
-		return;
-
-	ib_req_notify_cq(xprt->sc_sq_cq, IB_CQ_NEXT_COMP);
-	atomic_inc(&rdma_stat_sq_poll);
-	while ((ret = ib_poll_cq(cq, 1, &wc)) > 0) {
-		ctxt = (struct svc_rdma_op_ctxt *)(unsigned long)wc.wr_id;
-		xprt = ctxt->xprt;
-
 	svc_rdma_unmap_dma(ctxt);
-		if (wc.status != IB_WC_SUCCESS)
-			/* Close the transport */
-			set_bit(XPT_CLOSE, &xprt->sc_xprt.xpt_flags);
-
-		/* Decrement used SQ WR count */
-		atomic_dec(&xprt->sc_sq_count);
-		wake_up(&xprt->sc_send_wait);
 
 	switch (ctxt->wr_op) {
 	case IB_WR_SEND:
@@ -381,10 +358,42 @@ static void sq_cq_reap(struct svcxprt_rdma *xprt)
 
 	default:
 		printk(KERN_ERR "svcrdma: unexpected completion type, "
-			       "opcode=%d, status=%d\n",
-			       wc.opcode, wc.status);
+		       "opcode=%d\n",
+		       ctxt->wr_op);
 		break;
 	}
+}
+
+/*
+ * Send Queue Completion Handler - potentially called on interrupt context.
+ *
+ * Note that caller must hold a transport reference.
+ */
+static void sq_cq_reap(struct svcxprt_rdma *xprt)
+{
+	struct svc_rdma_op_ctxt *ctxt = NULL;
+	struct ib_wc wc;
+	struct ib_cq *cq = xprt->sc_sq_cq;
+	int ret;
+
+	if (!test_and_clear_bit(RDMAXPRT_SQ_PENDING, &xprt->sc_flags))
+		return;
+
+	ib_req_notify_cq(xprt->sc_sq_cq, IB_CQ_NEXT_COMP);
+	atomic_inc(&rdma_stat_sq_poll);
+	while ((ret = ib_poll_cq(cq, 1, &wc)) > 0) {
+		if (wc.status != IB_WC_SUCCESS)
+			/* Close the transport */
+			set_bit(XPT_CLOSE, &xprt->sc_xprt.xpt_flags);
+
+		/* Decrement used SQ WR count */
+		atomic_dec(&xprt->sc_sq_count);
+		wake_up(&xprt->sc_send_wait);
+
+		ctxt = (struct svc_rdma_op_ctxt *)(unsigned long)wc.wr_id;
+		if (ctxt)
+			process_context(xprt, ctxt);
+
 		svc_xprt_put(&xprt->sc_xprt);
 	}
 
@@ -1184,6 +1193,40 @@ static int svc_rdma_has_wspace(struct svc_xprt *xprt)
 	return 1;
 }
 
+/*
+ * Attempt to register the kvec representing the RPC memory with the
+ * device.
+ *
+ * Returns:
+ *  NULL : The device does not support fastreg or there were no more
+ *         fastreg mr.
+ *  frmr : The kvec register request was successfully posted.
+ *    <0 : An error was encountered attempting to register the kvec.
+ */
+int svc_rdma_fastreg(struct svcxprt_rdma *xprt,
+		     struct svc_rdma_fastreg_mr *frmr)
+{
+	struct ib_send_wr fastreg_wr;
+	u8 key;
+
+	/* Bump the key */
+	key = (u8)(frmr->mr->lkey & 0x000000FF);
+	ib_update_fast_reg_key(frmr->mr, ++key);
+
+	/* Prepare FASTREG WR */
+	memset(&fastreg_wr, 0, sizeof fastreg_wr);
+	fastreg_wr.opcode = IB_WR_FAST_REG_MR;
+	fastreg_wr.send_flags = IB_SEND_SIGNALED;
+	fastreg_wr.wr.fast_reg.iova_start = (unsigned long)frmr->kva;
+	fastreg_wr.wr.fast_reg.page_list = frmr->page_list;
+	fastreg_wr.wr.fast_reg.page_list_len = frmr->page_list_len;
+	fastreg_wr.wr.fast_reg.page_shift = PAGE_SHIFT;
+	fastreg_wr.wr.fast_reg.length = frmr->map_len;
+	fastreg_wr.wr.fast_reg.access_flags = frmr->access_flags;
+	fastreg_wr.wr.fast_reg.rkey = frmr->mr->lkey;
+	return svc_rdma_send(xprt, &fastreg_wr);
+}
+
 int svc_rdma_send(struct svcxprt_rdma *xprt, struct ib_send_wr *wr)
 {
 	struct ib_send_wr *bad_wr;
@@ -1193,8 +1236,6 @@ int svc_rdma_send(struct svcxprt_rdma *xprt, struct ib_send_wr *wr)
 		return -ENOTCONN;
 
 	BUG_ON(wr->send_flags != IB_SEND_SIGNALED);
-	BUG_ON(((struct svc_rdma_op_ctxt *)(unsigned long)wr->wr_id)->wr_op !=
-		wr->opcode);
 	/* If the SQ is full, wait until an SQ entry is available */
 	while (1) {
 		spin_lock_bh(&xprt->sc_lock);