svcrdma: Preserve Receive buffer until svc_rdma_sendto

Rather than releasing the incoming svc_rdma_recv_ctxt at the end of
svc_rdma_recvfrom, hold onto it until svc_rdma_sendto.

This permits the contents of the Receive buffer to be preserved
through svc_process and then referenced directly in sendto as it
constructs Write and Reply chunks to return to the client.

The real changes will come in subsequent patches.

Note: I cannot use ->xpo_release_rqst for this purpose because that
is called _before_ ->xpo_sendto. svc_rdma_sendto uses information in
the received Call transport header to construct the Reply transport
header, which is preserved in the RPC's Receive buffer.

The historical comment in svc_send() isn't helpful: it is already
obvious that ->xpo_release_rqst is being called before ->xpo_sendto,
but there is no explanation for this ordering going back to the
beginning of the git era.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

diff --git a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
index ecfe7c90a2684cc5cb5f4dab4d9348a98922e146..d9fef5211116e98aa81237a2389f756f6422df7f 100644 (file)
--- a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
@@ -789,7 +789,7 @@ int svc_rdma_recvfrom(struct svc_rqst *rqstp)
                goto out_readchunk;
 
 complete:
-       svc_rdma_recv_ctxt_put(rdma_xprt, ctxt);
+       rqstp->rq_xprt_ctxt = ctxt;
        rqstp->rq_prot = IPPROTO_MAX;
        svc_xprt_copy_addrs(rqstp, xprt);
        return rqstp->rq_arg.len;

diff --git a/net/sunrpc/xprtrdma/svc_rdma_sendto.c b/net/sunrpc/xprtrdma/svc_rdma_sendto.c
index a397d9a3d80e9228ee30495268095beeddd56702..cbbde70eeec5433c5851e28e2cc32fcfc35dd230 100644 (file)
--- a/net/sunrpc/xprtrdma/svc_rdma_sendto.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_sendto.c
@@ -623,6 +623,7 @@ int svc_rdma_sendto(struct svc_rqst *rqstp)
        struct svc_xprt *xprt = rqstp->rq_xprt;
        struct svcxprt_rdma *rdma =
                container_of(xprt, struct svcxprt_rdma, sc_xprt);
+       struct svc_rdma_recv_ctxt *rctxt = rqstp->rq_xprt_ctxt;
        __be32 *p, *rdma_argp, *rdma_resp, *wr_lst, *rp_ch;
        struct xdr_buf *xdr = &rqstp->rq_res;
        struct page *res_page;
@@ -675,7 +676,12 @@ int svc_rdma_sendto(struct svc_rqst *rqstp)
                                      wr_lst, rp_ch);
        if (ret < 0)
                goto err0;
-       return 0;
+       ret = 0;
+
+out:
+       rqstp->rq_xprt_ctxt = NULL;
+       svc_rdma_recv_ctxt_put(rdma, rctxt);
+       return ret;
 
  err2:
        if (ret != -E2BIG && ret != -EINVAL)
@@ -684,12 +690,14 @@ int svc_rdma_sendto(struct svc_rqst *rqstp)
        ret = svc_rdma_send_error_msg(rdma, rdma_resp, rqstp);
        if (ret < 0)
                goto err0;
-       return 0;
+       ret = 0;
+       goto out;
 
  err1:
        put_page(res_page);
  err0:
        trace_svcrdma_send_failed(rqstp, ret);
        set_bit(XPT_CLOSE, &xprt->xpt_flags);
-       return -ENOTCONN;
+       ret = -ENOTCONN;
+       goto out;
 }