svcrdma: Another sendto chunk list parsing update

Commit 5fdca6531434 ("svcrdma: Renovate sendto chunk list parsing")
missed a spot. svc_rdma_xdr_get_reply_hdr_len() also assumes the
Write list has only one Write chunk. There's no harm in making this
code more general.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

4 files changed, 38 insertions, 25 deletions

diff --git a/include/linux/sunrpc/rpc_rdma.h b/include/linux/sunrpc/rpc_rdma.h
index cfda6adcf33c..245fc59b7324 100644
--- a/include/linux/sunrpc/rpc_rdma.h
+++ b/include/linux/sunrpc/rpc_rdma.h
@@ -110,6 +110,15 @@ struct rpcrdma_msg {
 };
 
 /*
+ * XDR sizes, in quads
+ */
+enum {
+        rpcrdma_fixed_maxsz     = 4,
+        rpcrdma_segment_maxsz   = 4,
+        rpcrdma_readchunk_maxsz = 2 + rpcrdma_segment_maxsz,
+};
+
+/*
  * Smallest RPC/RDMA header: rm_xid through rm_type, then rm_nochunks
  */
 #define RPCRDMA_HDRLEN_MIN      (sizeof(__be32) * 7)
diff --git a/include/linux/sunrpc/svc_rdma.h b/include/linux/sunrpc/svc_rdma.h
index 757fb963696c..551c51816352 100644
--- a/include/linux/sunrpc/svc_rdma.h
+++ b/include/linux/sunrpc/svc_rdma.h
@@ -218,7 +218,7 @@ extern void svc_rdma_xdr_encode_reply_header(struct svcxprt_rdma *,
                                              struct rpcrdma_msg *,
                                              struct rpcrdma_msg *,
                                              enum rpcrdma_proc);
-extern int svc_rdma_xdr_get_reply_hdr_len(struct rpcrdma_msg *);
+extern unsigned int svc_rdma_xdr_get_reply_hdr_len(__be32 *rdma_resp);
 
 /* svc_rdma_recvfrom.c */
 extern int svc_rdma_recvfrom(struct svc_rqst *);
diff --git a/net/sunrpc/xprtrdma/svc_rdma_marshal.c b/net/sunrpc/xprtrdma/svc_rdma_marshal.c
index 0ba9887f3e22..4e7203439e2f 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_marshal.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_marshal.c
@@ -260,32 +260,35 @@ int svc_rdma_xdr_encode_error(struct svcxprt_rdma *xprt,
         return (int)((unsigned long)va - (unsigned long)startp);
 }
 
-int svc_rdma_xdr_get_reply_hdr_len(struct rpcrdma_msg *rmsgp)
+/**
+ * svc_rdma_xdr_get_reply_hdr_length - Get length of Reply transport header
+ * @rdma_resp: buffer containing Reply transport header
+ *
+ * Returns length of transport header, in bytes.
+ */
+unsigned int svc_rdma_xdr_get_reply_hdr_len(__be32 *rdma_resp)
 {
-        struct rpcrdma_write_array *wr_ary;
+        unsigned int nsegs;
+        __be32 *p;
 
-        /* There is no read-list in a reply */
+        p = rdma_resp;
 
-        /* skip write list */
-        wr_ary = (struct rpcrdma_write_array *)
-                &rmsgp->rm_body.rm_chunks[1];
-        if (wr_ary->wc_discrim)
-                wr_ary = (struct rpcrdma_write_array *)
-                        &wr_ary->wc_array[be32_to_cpu(wr_ary->wc_nchunks)].
-                        wc_target.rs_length;
-        else
-                wr_ary = (struct rpcrdma_write_array *)
-                        &wr_ary->wc_nchunks;
-
-        /* skip reply array */
-        if (wr_ary->wc_discrim)
-                wr_ary = (struct rpcrdma_write_array *)
-                        &wr_ary->wc_array[be32_to_cpu(wr_ary->wc_nchunks)];
-        else
-                wr_ary = (struct rpcrdma_write_array *)
-                        &wr_ary->wc_nchunks;
-
-        return (unsigned long) wr_ary - (unsigned long) rmsgp;
+        /* RPC-over-RDMA V1 replies never have a Read list. */
+        p += rpcrdma_fixed_maxsz + 1;
+
+        /* Skip Write list. */
+        while (*p++ != xdr_zero) {
+                nsegs = be32_to_cpup(p++);
+                p += nsegs * rpcrdma_segment_maxsz;
+        }
+
+        /* Skip Reply chunk. */
+        if (*p++ != xdr_zero) {
+                nsegs = be32_to_cpup(p++);
+                p += nsegs * rpcrdma_segment_maxsz;
+        }
+
+        return (unsigned long)p - (unsigned long)rdma_resp;
 }
 
 void svc_rdma_xdr_encode_write_list(struct rpcrdma_msg *rmsgp, int chunks)
diff --git a/net/sunrpc/xprtrdma/svc_rdma_sendto.c b/net/sunrpc/xprtrdma/svc_rdma_sendto.c
index ad4d286a83c5..ba76f1617965 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_sendto.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_sendto.c
@@ -476,7 +476,8 @@ static int send_reply(struct svcxprt_rdma *rdma,
 
         /* Prepare the SGE for the RPCRDMA Header */
         ctxt->sge[0].lkey = rdma->sc_pd->local_dma_lkey;
-        ctxt->sge[0].length = svc_rdma_xdr_get_reply_hdr_len(rdma_resp);
+        ctxt->sge[0].length =
+            svc_rdma_xdr_get_reply_hdr_len((__be32 *)rdma_resp);
         ctxt->sge[0].addr =
             ib_dma_map_page(rdma->sc_cm_id->device, page, 0,
                             ctxt->sge[0].length, DMA_TO_DEVICE);