[PATCH,RFC 04/09] svcrdma: Add a service to register a Fast Reg MR with the device

[Tom Tucker <tom@opengridcomputing.com>]

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          |    1 +
  net/sunrpc/xprtrdma/svc_rdma_transport.c |   53 
++++++++++++++++++++++++++---
  2 files changed, 48 insertions(+), 6 deletions(-)

diff --git a/include/linux/sunrpc/svc_rdma.h 
b/include/linux/sunrpc/svc_rdma.h
index 100754e..6899b71 100644
--- a/include/linux/sunrpc/svc_rdma.h
+++ b/include/linux/sunrpc/svc_rdma.h
@@ -219,6 +219,7 @@ 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 *);
diff --git a/net/sunrpc/xprtrdma/svc_rdma_transport.c 
b/net/sunrpc/xprtrdma/svc_rdma_transport.c
index 8586c7d..b8c642d 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_transport.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_transport.c
@@ -344,10 +344,6 @@ static void sq_cq_reap(struct svcxprt_rdma *xprt)
  	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);
@@ -356,6 +352,11 @@ static void sq_cq_reap(struct svcxprt_rdma *xprt)
  		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)
+			goto skip_it;
+		svc_rdma_unmap_dma(ctxt);
+
  		switch (ctxt->wr_op) {
  		case IB_WR_SEND:
  			svc_rdma_put_context(ctxt, 1);
@@ -385,6 +386,7 @@ static void sq_cq_reap(struct svcxprt_rdma *xprt)
  			       wc.opcode, wc.status);
  			break;
  		}
+	skip_it:
  		svc_xprt_put(&xprt->sc_xprt);
  	}

@@ -1203,6 +1205,47 @@ 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;
+	int ret;
+
+	/* 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;
+	ret = svc_rdma_send(xprt, &fastreg_wr);
+	dprintk("svcrdma:%s: reg lkey %08x kva %p mrlen %lu pages %d ret %d\n",
+		__func__, frmr->mr->lkey, frmr->kva, frmr->map_len,
+		frmr->page_list_len,
+		ret);
+
+	return ret;
+}
+
  int svc_rdma_send(struct svcxprt_rdma *xprt, struct ib_send_wr *wr)
  {
  	struct ib_send_wr *bad_wr;
@@ -1212,8 +1255,6 @@ 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);