svcrdma: Add a batch Receive posting mechanism

Introduce a server-side mechanism similar to commit e340c2d6ef2a
("xprtrdma: Reduce the doorbell rate (Receive)") to post Receive
WRs in batch. Its first consumer is svc_rdma_post_recvs(), which
posts the initial set of Receive WRs.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

diff --git a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
index 04148a6..0c6aa86 100644 (file)
--- a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
@@ -264,6 +264,47 @@ void svc_rdma_release_rqst(struct svc_rqst *rqstp)
                svc_rdma_recv_ctxt_put(rdma, ctxt);
 }
 
+static bool svc_rdma_refresh_recvs(struct svcxprt_rdma *rdma,
+                                  unsigned int wanted, bool temp)
+{
+       const struct ib_recv_wr *bad_wr = NULL;
+       struct svc_rdma_recv_ctxt *ctxt;
+       struct ib_recv_wr *recv_chain;
+       int ret;
+
+       if (test_bit(XPT_CLOSE, &rdma->sc_xprt.xpt_flags))
+               return false;
+
+       recv_chain = NULL;
+       while (wanted--) {
+               ctxt = svc_rdma_recv_ctxt_get(rdma);
+               if (!ctxt)
+                       break;
+
+               trace_svcrdma_post_recv(ctxt);
+               ctxt->rc_temp = temp;
+               ctxt->rc_recv_wr.next = recv_chain;
+               recv_chain = &ctxt->rc_recv_wr;
+       }
+       if (!recv_chain)
+               return false;
+
+       ret = ib_post_recv(rdma->sc_qp, recv_chain, &bad_wr);
+       if (ret)
+               goto err_free;
+       return true;
+
+err_free:
+       trace_svcrdma_rq_post_err(rdma, ret);
+       while (bad_wr) {
+               ctxt = container_of(bad_wr, struct svc_rdma_recv_ctxt,
+                                   rc_recv_wr);
+               bad_wr = bad_wr->next;
+               svc_rdma_recv_ctxt_put(rdma, ctxt);
+       }
+       return false;
+}
+
 static int __svc_rdma_post_recv(struct svcxprt_rdma *rdma,
                                struct svc_rdma_recv_ctxt *ctxt)
 {
@@ -301,20 +342,7 @@ static int svc_rdma_post_recv(struct svcxprt_rdma *rdma)
  */
 bool svc_rdma_post_recvs(struct svcxprt_rdma *rdma)
 {
-       struct svc_rdma_recv_ctxt *ctxt;
-       unsigned int i;
-       int ret;
-
-       for (i = 0; i < rdma->sc_max_requests; i++) {
-               ctxt = svc_rdma_recv_ctxt_get(rdma);
-               if (!ctxt)
-                       return false;
-               ctxt->rc_temp = true;
-               ret = __svc_rdma_post_recv(rdma, ctxt);
-               if (ret)
-                       return false;
-       }
-       return true;
+       return svc_rdma_refresh_recvs(rdma, rdma->sc_max_requests, true);
 }
 
 /**