svcrdma: Make RDMA_ERROR messages work

Fix several issues with svc_rdma_send_error():

 - Post a receive buffer to replace the one that was consumed by
   the incoming request
 - Posting a send should use DMA_TO_DEVICE, not DMA_FROM_DEVICE
 - No need to put_page _and_ free pages in svc_rdma_put_context
 - Make sure the sge is set up completely in case the error
   path goes through svc_rdma_unmap_dma()
 - Replace the use of ENOSYS, which has a reserved meaning

Related fixes in svc_rdma_recvfrom():

 - Don't leak the ctxt associated with the incoming request
 - Don't close the connection after sending an error reply
 - Let svc_rdma_send_error() figure out the right header error code

As a last clean up, move svc_rdma_send_error() to svc_rdma_sendto.c
with other similar functions. There is some common logic in these
functions that could someday be combined to reduce code duplication.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Devesh Sharma <devesh.sharma@broadcom.com>
Tested-by: Devesh Sharma <devesh.sharma@broadcom.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

5 files changed, 74 insertions, 67 deletions

diff --git a/include/linux/sunrpc/svc_rdma.h b/include/linux/sunrpc/svc_rdma.h
index aef47dd2bd1a..42e852230a03 100644
--- a/include/linux/sunrpc/svc_rdma.h
+++ b/include/linux/sunrpc/svc_rdma.h
@@ -228,11 +228,11 @@ extern int svc_rdma_map_xdr(struct svcxprt_rdma *, struct xdr_buf *,
 extern int svc_rdma_sendto(struct svc_rqst *);
 extern struct rpcrdma_read_chunk *
         svc_rdma_get_read_chunk(struct rpcrdma_msg *);
+extern void svc_rdma_send_error(struct svcxprt_rdma *, struct rpcrdma_msg *,
+                                int);
 
 /* svc_rdma_transport.c */
 extern int svc_rdma_send(struct svcxprt_rdma *, struct ib_send_wr *);
-extern void svc_rdma_send_error(struct svcxprt_rdma *, struct rpcrdma_msg *,
-                                enum rpcrdma_errcode);
 extern int svc_rdma_post_recv(struct svcxprt_rdma *, gfp_t);
 extern int svc_rdma_repost_recv(struct svcxprt_rdma *, gfp_t);
 extern int svc_rdma_create_listen(struct svc_serv *, int, struct sockaddr *);
diff --git a/net/sunrpc/xprtrdma/svc_rdma_marshal.c b/net/sunrpc/xprtrdma/svc_rdma_marshal.c
index e2fca7617242..f74fc523d95b 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_marshal.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_marshal.c
@@ -162,7 +162,7 @@ int svc_rdma_xdr_decode_req(struct rpcrdma_msg **rdma_req,
         }
 
         if (rmsgp->rm_vers != rpcrdma_version)
-                return -ENOSYS;
+                return -EPROTONOSUPPORT;
 
         /* Pull in the extra for the padded case and bump our pointer */
         if (rmsgp->rm_type == rdma_msgp) {
diff --git a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
index acf15b8bca70..0f09052110a7 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
@@ -612,7 +612,6 @@ int svc_rdma_recvfrom(struct svc_rqst *rqstp)
         struct svc_rdma_op_ctxt *ctxt = NULL;
         struct rpcrdma_msg *rmsgp;
         int ret = 0;
-        int len;
 
         dprintk("svcrdma: rqstp=%p\n", rqstp);
 
@@ -654,15 +653,10 @@ int svc_rdma_recvfrom(struct svc_rqst *rqstp)
         rdma_build_arg_xdr(rqstp, ctxt, ctxt->byte_len);
 
         /* Decode the RDMA header. */
-        len = svc_rdma_xdr_decode_req(&rmsgp, rqstp);
-        rqstp->rq_xprt_hlen = len;
-
-        /* If the request is invalid, reply with an error */
-        if (len < 0) {
-                if (len == -ENOSYS)
-                        svc_rdma_send_error(rdma_xprt, rmsgp, ERR_VERS);
-                goto close_out;
-        }
+        ret = svc_rdma_xdr_decode_req(&rmsgp, rqstp);
+        if (ret < 0)
+                goto out_err;
+        rqstp->rq_xprt_hlen = ret;
 
         if (svc_rdma_is_backchannel_reply(xprt, rmsgp)) {
                 ret = svc_rdma_handle_bc_reply(xprt->xpt_bc_xprt, rmsgp,
@@ -698,6 +692,11 @@ int svc_rdma_recvfrom(struct svc_rqst *rqstp)
         svc_xprt_copy_addrs(rqstp, xprt);
         return ret;
 
+out_err:
+        svc_rdma_send_error(rdma_xprt, rmsgp, ret);
+        svc_rdma_put_context(ctxt, 0);
+        return 0;
+
  close_out:
         if (ctxt)
                 svc_rdma_put_context(ctxt, 1);
diff --git a/net/sunrpc/xprtrdma/svc_rdma_sendto.c b/net/sunrpc/xprtrdma/svc_rdma_sendto.c
index ace9efa7aa6c..a26ca569f257 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_sendto.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_sendto.c
@@ -652,3 +652,65 @@ int svc_rdma_sendto(struct svc_rqst *rqstp)
         set_bit(XPT_CLOSE, &rdma->sc_xprt.xpt_flags);
         return -ENOTCONN;
 }
+
+void svc_rdma_send_error(struct svcxprt_rdma *xprt, struct rpcrdma_msg *rmsgp,
+                         int status)
+{
+        struct ib_send_wr err_wr;
+        struct page *p;
+        struct svc_rdma_op_ctxt *ctxt;
+        enum rpcrdma_errcode err;
+        __be32 *va;
+        int length;
+        int ret;
+
+        ret = svc_rdma_repost_recv(xprt, GFP_KERNEL);
+        if (ret)
+                return;
+
+        p = alloc_page(GFP_KERNEL);
+        if (!p)
+                return;
+        va = page_address(p);
+
+        /* XDR encode an error reply */
+        err = ERR_CHUNK;
+        if (status == -EPROTONOSUPPORT)
+                err = ERR_VERS;
+        length = svc_rdma_xdr_encode_error(xprt, rmsgp, err, va);
+
+        ctxt = svc_rdma_get_context(xprt);
+        ctxt->direction = DMA_TO_DEVICE;
+        ctxt->count = 1;
+        ctxt->pages[0] = p;
+
+        /* Prepare SGE for local address */
+        ctxt->sge[0].lkey = xprt->sc_pd->local_dma_lkey;
+        ctxt->sge[0].length = length;
+        ctxt->sge[0].addr = ib_dma_map_page(xprt->sc_cm_id->device,
+                                            p, 0, length, DMA_TO_DEVICE);
+        if (ib_dma_mapping_error(xprt->sc_cm_id->device, ctxt->sge[0].addr)) {
+                dprintk("svcrdma: Error mapping buffer for protocol error\n");
+                svc_rdma_put_context(ctxt, 1);
+                return;
+        }
+        atomic_inc(&xprt->sc_dma_used);
+
+        /* Prepare SEND WR */
+        memset(&err_wr, 0, sizeof(err_wr));
+        ctxt->wr_op = IB_WR_SEND;
+        err_wr.wr_id = (unsigned long)ctxt;
+        err_wr.sg_list = ctxt->sge;
+        err_wr.num_sge = 1;
+        err_wr.opcode = IB_WR_SEND;
+        err_wr.send_flags = IB_SEND_SIGNALED;
+
+        /* Post It */
+        ret = svc_rdma_send(xprt, &err_wr);
+        if (ret) {
+                dprintk("svcrdma: Error %d posting send for protocol error\n",
+                        ret);
+                svc_rdma_unmap_dma(ctxt);
+                svc_rdma_put_context(ctxt, 1);
+        }
+}
diff --git a/net/sunrpc/xprtrdma/svc_rdma_transport.c b/net/sunrpc/xprtrdma/svc_rdma_transport.c
index 03fdfce45493..15c8fa3ee794 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_transport.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_transport.c
@@ -1433,57 +1433,3 @@ int svc_rdma_send(struct svcxprt_rdma *xprt, struct ib_send_wr *wr)
         }
         return ret;
 }
-
-void svc_rdma_send_error(struct svcxprt_rdma *xprt, struct rpcrdma_msg *rmsgp,
-                         enum rpcrdma_errcode err)
-{
-        struct ib_send_wr err_wr;
-        struct page *p;
-        struct svc_rdma_op_ctxt *ctxt;
-        __be32 *va;
-        int length;
-        int ret;
-
-        p = alloc_page(GFP_KERNEL);
-        if (!p)
-                return;
-        va = page_address(p);
-
-        /* XDR encode error */
-        length = svc_rdma_xdr_encode_error(xprt, rmsgp, err, va);
-
-        ctxt = svc_rdma_get_context(xprt);
-        ctxt->direction = DMA_FROM_DEVICE;
-        ctxt->count = 1;
-        ctxt->pages[0] = p;
-
-        /* Prepare SGE for local address */
-        ctxt->sge[0].addr = ib_dma_map_page(xprt->sc_cm_id->device,
-                                            p, 0, length, DMA_FROM_DEVICE);
-        if (ib_dma_mapping_error(xprt->sc_cm_id->device, ctxt->sge[0].addr)) {
-                put_page(p);
-                svc_rdma_put_context(ctxt, 1);
-                return;
-        }
-        atomic_inc(&xprt->sc_dma_used);
-        ctxt->sge[0].lkey = xprt->sc_pd->local_dma_lkey;
-        ctxt->sge[0].length = length;
-
-        /* Prepare SEND WR */
-        memset(&err_wr, 0, sizeof err_wr);
-        ctxt->wr_op = IB_WR_SEND;
-        err_wr.wr_id = (unsigned long)ctxt;
-        err_wr.sg_list = ctxt->sge;
-        err_wr.num_sge = 1;
-        err_wr.opcode = IB_WR_SEND;
-        err_wr.send_flags = IB_SEND_SIGNALED;
-
-        /* Post It */
-        ret = svc_rdma_send(xprt, &err_wr);
-        if (ret) {
-                dprintk("svcrdma: Error %d posting send for protocol error\n",
-                        ret);
-                svc_rdma_unmap_dma(ctxt);
-                svc_rdma_put_context(ctxt, 1);
-        }
-}