Currently the Linux server can not decode RDMA_NOMSG type requests.
The client sends the RPC/RDMA header via RDMA SEND. The header has
a read chunk list that conveys the RPC and NFS headers and the NFS
payload (if any).

Large operations like NFSv4 CREATE(NF4LNK) will by conveyed via
RDMA_NOMSG, so add this support.

Signed-off-by: Chuck Lever <[email protected]>
---

 include/linux/sunrpc/svc_rdma.h         |    1 +
 net/sunrpc/xprtrdma/svc_rdma_recvfrom.c |   39 +++++++++++++++++++++++++++++--
 2 files changed, 37 insertions(+), 3 deletions(-)

diff --git a/include/linux/sunrpc/svc_rdma.h b/include/linux/sunrpc/svc_rdma.h
index f161e30..c343a94 100644
--- a/include/linux/sunrpc/svc_rdma.h
+++ b/include/linux/sunrpc/svc_rdma.h
@@ -79,6 +79,7 @@ struct svc_rdma_op_ctxt {
        enum ib_wr_opcode wr_op;
        enum ib_wc_status wc_status;
        u32 byte_len;
+       u32 position;
        struct svcxprt_rdma *xprt;
        unsigned long flags;
        enum dma_data_direction direction;
diff --git a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c 
b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
index a67dd1a..36cf51a 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
@@ -60,6 +60,7 @@ static void rdma_build_arg_xdr(struct svc_rqst *rqstp,
                               struct svc_rdma_op_ctxt *ctxt,
                               u32 byte_count)
 {
+       struct rpcrdma_msg *rmsgp;
        struct page *page;
        u32 bc;
        int sge_no;
@@ -82,7 +83,14 @@ static void rdma_build_arg_xdr(struct svc_rqst *rqstp,
        /* If data remains, store it in the pagelist */
        rqstp->rq_arg.page_len = bc;
        rqstp->rq_arg.page_base = 0;
-       rqstp->rq_arg.pages = &rqstp->rq_pages[1];
+
+       /* RDMA_NOMSG: RDMA READ data should land just after RDMA RECV data */
+       rmsgp = (struct rpcrdma_msg *)rqstp->rq_arg.head[0].iov_base;
+       if (be32_to_cpu(rmsgp->rm_type) == RDMA_NOMSG)
+               rqstp->rq_arg.pages = &rqstp->rq_pages[0];
+       else
+               rqstp->rq_arg.pages = &rqstp->rq_pages[1];
+
        sge_no = 1;
        while (bc && sge_no < ctxt->count) {
                page = ctxt->pages[sge_no];
@@ -383,7 +391,6 @@ static int rdma_read_chunks(struct svcxprt_rdma *xprt,
         */
        head->arg.head[0] = rqstp->rq_arg.head[0];
        head->arg.tail[0] = rqstp->rq_arg.tail[0];
-       head->arg.pages = &head->pages[head->count];
        head->hdr_count = head->count;
        head->arg.page_base = 0;
        head->arg.page_len = 0;
@@ -393,9 +400,17 @@ static int rdma_read_chunks(struct svcxprt_rdma *xprt,
        ch = (struct rpcrdma_read_chunk *)&rmsgp->rm_body.rm_chunks[0];
        position = be32_to_cpu(ch->rc_position);
 
+       /* RDMA_NOMSG: RDMA READ data should land just after RDMA RECV data */
+       if (position == 0) {
+               head->arg.pages = &head->pages[0];
+               page_offset = head->byte_len;
+       } else {
+               head->arg.pages = &head->pages[head->count];
+               page_offset = 0;
+       }
+
        ret = 0;
        page_no = 0;
-       page_offset = 0;
        for (; ch->rc_discrim != xdr_zero; ch++) {
                if (be32_to_cpu(ch->rc_position) != position)
                        goto err;
@@ -418,7 +433,10 @@ static int rdma_read_chunks(struct svcxprt_rdma *xprt,
                        head->arg.buflen += ret;
                }
        }
+
        ret = 1;
+       head->position = position;
+
  err:
        /* Detach arg pages. svc_recv will replenish them */
        for (page_no = 0;
@@ -465,6 +483,21 @@ static int rdma_read_complete(struct svc_rqst *rqstp,
                put_page(rqstp->rq_pages[page_no]);
                rqstp->rq_pages[page_no] = head->pages[page_no];
        }
+
+       /* Adjustments made for RDMA_NOMSG type requests */
+       if (head->position == 0) {
+               if (head->arg.len <= head->sge[0].length) {
+                       head->arg.head[0].iov_len = head->arg.len -
+                                                       head->byte_len;
+                       head->arg.page_len = 0;
+               } else {
+                       head->arg.head[0].iov_len = head->sge[0].length -
+                                                               head->byte_len;
+                       head->arg.page_len = head->arg.len -
+                                               head->sge[0].length;
+               }
+       }
+
        /* Point rq_arg.pages past header */
        rdma_fix_xdr_pad(&head->arg);
        rqstp->rq_arg.pages = &rqstp->rq_pages[head->hdr_count];

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