To support the NFSv4.1 backchannel on RDMA connections, add a
mechanism for sending a backwards-direction RPC/RDMA call on a
connection established by a client.
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
---
include/linux/sunrpc/svc_rdma.h | 2 +
net/sunrpc/xprtrdma/svc_rdma_sendto.c | 61 +++++++++++++++++++++++++++++++++
2 files changed, 63 insertions(+)
diff --git a/include/linux/sunrpc/svc_rdma.h b/include/linux/sunrpc/svc_rdma.h
index f71c625..bf9b17b 100644
--- a/include/linux/sunrpc/svc_rdma.h
+++ b/include/linux/sunrpc/svc_rdma.h
@@ -215,6 +215,8 @@ extern int rdma_read_chunk_frmr(struct svcxprt_rdma *, struct svc_rqst *,
extern int svc_rdma_sendto(struct svc_rqst *);
extern struct rpcrdma_read_chunk *
svc_rdma_get_read_chunk(struct rpcrdma_msg *);
+extern int svc_rdma_bc_post_send(struct svcxprt_rdma *,
+ struct svc_rdma_op_ctxt *, struct xdr_buf *);
/* svc_rdma_transport.c */
extern int svc_rdma_send(struct svcxprt_rdma *, struct ib_send_wr *);
diff --git a/net/sunrpc/xprtrdma/svc_rdma_sendto.c b/net/sunrpc/xprtrdma/svc_rdma_sendto.c
index bad5eaa..846df63 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_sendto.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_sendto.c
@@ -648,3 +648,64 @@ int svc_rdma_sendto(struct svc_rqst *rqstp)
svc_rdma_put_context(ctxt, 0);
return ret;
}
+
+/* Send a backwards direction RPC call.
+ *
+ * Caller holds the connection's mutex and has already marshaled the
+ * RPC/RDMA request. Before sending the request, this API also posts
+ * an extra receive buffer to catch the bc reply for this request.
+ */
+int svc_rdma_bc_post_send(struct svcxprt_rdma *rdma,
+ struct svc_rdma_op_ctxt *ctxt, struct xdr_buf *sndbuf)
+{
+ struct svc_rdma_req_map *vec;
+ struct ib_send_wr send_wr;
+ int ret;
+
+ vec = svc_rdma_get_req_map();
+ ret = map_xdr(rdma, sndbuf, vec);
+ if (ret)
+ goto out;
+
+ /* Post a recv buffer to handle reply for this request */
+ ret = svc_rdma_post_recv(rdma);
+ if (ret) {
+ pr_err("svcrdma: Failed to post bc receive buffer, err=%d. "
+ "Closing transport %p.\n", ret, rdma);
+ set_bit(XPT_CLOSE, &rdma->sc_xprt.xpt_flags);
+ ret = -ENOTCONN;
+ goto out;
+ }
+
+ ctxt->wr_op = IB_WR_SEND;
+ ctxt->direction = DMA_TO_DEVICE;
+ ctxt->sge[0].lkey = rdma->sc_dma_lkey;
+ ctxt->sge[0].length = sndbuf->len;
+ ctxt->sge[0].addr =
+ ib_dma_map_page(rdma->sc_cm_id->device, ctxt->pages[0], 0,
+ sndbuf->len, DMA_TO_DEVICE);
+ if (ib_dma_mapping_error(rdma->sc_cm_id->device, ctxt->sge[0].addr)) {
+ svc_rdma_unmap_dma(ctxt);
+ ret = -EIO;
+ goto out;
+ }
+ atomic_inc(&rdma->sc_dma_used);
+
+ memset(&send_wr, 0, sizeof send_wr);
+ send_wr.wr_id = (unsigned long)ctxt;
+ send_wr.sg_list = ctxt->sge;
+ send_wr.num_sge = 1;
+ send_wr.opcode = IB_WR_SEND;
+ send_wr.send_flags = IB_SEND_SIGNALED;
+
+ ret = svc_rdma_send(rdma, &send_wr);
+ if (ret) {
+ svc_rdma_unmap_dma(ctxt);
+ ret = -EIO;
+ goto out;
+ }
+out:
+ svc_rdma_put_req_map(vec);
+ dprintk("svcrdma: %s returns %d\n", __func__, ret);
+ return ret;
+}
--
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