svcrdma: Generalize svc_rdma_xdr_decode_req()

Clean up: Pass in just the piece of the svc_rqst that is needed
here.

While we're in the area, add an informative documenting comment.

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

3 files changed, 24 insertions, 12 deletions

diff --git a/include/linux/sunrpc/svc_rdma.h b/include/linux/sunrpc/svc_rdma.h
index 3081339968c3..d6917b896d3a 100644
--- a/include/linux/sunrpc/svc_rdma.h
+++ b/include/linux/sunrpc/svc_rdma.h
@@ -199,7 +199,7 @@ extern int svc_rdma_handle_bc_reply(struct rpc_xprt *xprt,
                                     struct xdr_buf *rcvbuf);
 
 /* svc_rdma_marshal.c */
-extern int svc_rdma_xdr_decode_req(struct rpcrdma_msg *, struct svc_rqst *);
+extern int svc_rdma_xdr_decode_req(struct xdr_buf *);
 extern int svc_rdma_xdr_encode_error(struct svcxprt_rdma *,
                                      struct rpcrdma_msg *,
                                      enum rpcrdma_errcode, __be32 *);
diff --git a/net/sunrpc/xprtrdma/svc_rdma_marshal.c b/net/sunrpc/xprtrdma/svc_rdma_marshal.c
index 765bca47c74d..0ba9887f3e22 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_marshal.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_marshal.c
@@ -145,19 +145,32 @@ static __be32 *decode_reply_array(__be32 *va, __be32 *vaend)
         return (__be32 *)&ary->wc_array[nchunks];
 }
 
-int svc_rdma_xdr_decode_req(struct rpcrdma_msg *rmsgp, struct svc_rqst *rqstp)
+/**
+ * svc_rdma_xdr_decode_req - Parse incoming RPC-over-RDMA header
+ * @rq_arg: Receive buffer
+ *
+ * On entry, xdr->head[0].iov_base points to first byte in the
+ * RPC-over-RDMA header.
+ *
+ * On successful exit, head[0] points to first byte past the
+ * RPC-over-RDMA header. For RDMA_MSG, this is the RPC message.
+ * The length of the RPC-over-RDMA header is returned.
+ */
+int svc_rdma_xdr_decode_req(struct xdr_buf *rq_arg)
 {
+        struct rpcrdma_msg *rmsgp;
         __be32 *va, *vaend;
         unsigned int len;
         u32 hdr_len;
 
         /* Verify that there's enough bytes for header + something */
-        if (rqstp->rq_arg.len <= RPCRDMA_HDRLEN_ERR) {
+        if (rq_arg->len <= RPCRDMA_HDRLEN_ERR) {
                 dprintk("svcrdma: header too short = %d\n",
-                        rqstp->rq_arg.len);
+                        rq_arg->len);
                 return -EINVAL;
         }
 
+        rmsgp = (struct rpcrdma_msg *)rq_arg->head[0].iov_base;
         if (rmsgp->rm_vers != rpcrdma_version) {
                 dprintk("%s: bad version %u\n", __func__,
                         be32_to_cpu(rmsgp->rm_vers));
@@ -189,10 +202,10 @@ int svc_rdma_xdr_decode_req(struct rpcrdma_msg *rmsgp, struct svc_rqst *rqstp)
                         be32_to_cpu(rmsgp->rm_body.rm_padded.rm_thresh);
 
                 va = &rmsgp->rm_body.rm_padded.rm_pempty[4];
-                rqstp->rq_arg.head[0].iov_base = va;
+                rq_arg->head[0].iov_base = va;
                 len = (u32)((unsigned long)va - (unsigned long)rmsgp);
-                rqstp->rq_arg.head[0].iov_len -= len;
-                if (len > rqstp->rq_arg.len)
+                rq_arg->head[0].iov_len -= len;
+                if (len > rq_arg->len)
                         return -EINVAL;
                 return len;
         default:
@@ -205,7 +218,7 @@ int svc_rdma_xdr_decode_req(struct rpcrdma_msg *rmsgp, struct svc_rqst *rqstp)
          * chunk list and a reply chunk list.
          */
         va = &rmsgp->rm_body.rm_chunks[0];
-        vaend = (__be32 *)((unsigned long)rmsgp + rqstp->rq_arg.len);
+        vaend = (__be32 *)((unsigned long)rmsgp + rq_arg->len);
         va = decode_read_list(va, vaend);
         if (!va) {
                 dprintk("svcrdma: failed to decode read list\n");
@@ -222,10 +235,9 @@ int svc_rdma_xdr_decode_req(struct rpcrdma_msg *rmsgp, struct svc_rqst *rqstp)
                 return -EINVAL;
         }
 
-        rqstp->rq_arg.head[0].iov_base = va;
+        rq_arg->head[0].iov_base = va;
         hdr_len = (unsigned long)va - (unsigned long)rmsgp;
-        rqstp->rq_arg.head[0].iov_len -= hdr_len;
-
+        rq_arg->head[0].iov_len -= hdr_len;
         return hdr_len;
 }
 
diff --git a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
index 1b72f351fbd3..c984b0aaecb1 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
@@ -636,7 +636,7 @@ int svc_rdma_recvfrom(struct svc_rqst *rqstp)
 
         /* Decode the RDMA header. */
         rmsgp = (struct rpcrdma_msg *)rqstp->rq_arg.head[0].iov_base;
-        ret = svc_rdma_xdr_decode_req(rmsgp, rqstp);
+        ret = svc_rdma_xdr_decode_req(&rqstp->rq_arg);
         if (ret < 0)
                 goto out_err;
         if (ret == 0)