[PATCH 05/20] NFSD: Invoke svc_encode_result_payload() in "read" NFSD encoders

[Chuck Lever <chuck.lever@oracle.com>]

Have the NFSD encoders annotate the boundaries of every
direct-data-placement eligible result data payload. Then change
svcrdma to use that annotation instead of the xdr->page_len
when handling Write chunks.

For NFSv4 on RDMA, that enables the ability to recognize multiple
result payloads per compound. This is a pre-requisite for supporting
multiple Write chunks per RPC transaction.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 fs/nfsd/nfs3xdr.c                     |    4 ++++
 fs/nfsd/nfs4xdr.c                     |    3 +++
 fs/nfsd/nfsxdr.c                      |    4 ++++
 net/sunrpc/xprtrdma/svc_rdma_sendto.c |   24 +++++++-----------------
 4 files changed, 18 insertions(+), 17 deletions(-)

diff --git a/fs/nfsd/nfs3xdr.c b/fs/nfsd/nfs3xdr.c
index 9c23b6acf234..f38cd31dbbec 100644
--- a/fs/nfsd/nfs3xdr.c
+++ b/fs/nfsd/nfs3xdr.c
@@ -720,6 +720,8 @@ nfs3svc_encode_readlinkres(struct svc_rqst *rqstp, __be32 *p)
 			*p = 0;
 			rqstp->rq_res.tail[0].iov_len = 4 - (resp->len&3);
 		}
+		svc_encode_result_payload(rqstp, rqstp->rq_res.head[0].iov_len,
+					  resp->len);
 		return 1;
 	} else
 		return xdr_ressize_check(rqstp, p);
@@ -746,6 +748,8 @@ nfs3svc_encode_readres(struct svc_rqst *rqstp, __be32 *p)
 			*p = 0;
 			rqstp->rq_res.tail[0].iov_len = 4 - (resp->count & 3);
 		}
+		svc_encode_result_payload(rqstp, rqstp->rq_res.head[0].iov_len,
+					  resp->count);
 		return 1;
 	} else
 		return xdr_ressize_check(rqstp, p);
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 7e24fb3ca36e..e56f0385022c 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -3777,6 +3777,8 @@ static __be32 nfsd4_encode_splice_read(
 		buf->page_len = 0;
 		return nfserr;
 	}
+	svc_encode_result_payload(read->rd_rqstp, buf->head[0].iov_len,
+				  maxcount);
 
 	*(p++) = htonl(eof);
 	*(p++) = htonl(maxcount);
@@ -3921,6 +3923,7 @@ nfsd4_encode_readlink(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd
 		xdr_truncate_encode(xdr, length_offset);
 		return nfserr;
 	}
+	svc_encode_result_payload(readlink->rl_rqstp, length_offset, maxcount);
 
 	wire_count = htonl(maxcount);
 	write_bytes_to_xdr_buf(xdr->buf, length_offset, &wire_count, 4);
diff --git a/fs/nfsd/nfsxdr.c b/fs/nfsd/nfsxdr.c
index 8a288c8fcd57..a23ea58a098e 100644
--- a/fs/nfsd/nfsxdr.c
+++ b/fs/nfsd/nfsxdr.c
@@ -483,6 +483,8 @@ nfssvc_encode_readlinkres(struct svc_rqst *rqstp, __be32 *p)
 		*p = 0;
 		rqstp->rq_res.tail[0].iov_len = 4 - (resp->len&3);
 	}
+	svc_encode_result_payload(rqstp, rqstp->rq_res.head[0].iov_len,
+				  resp->len);
 	return 1;
 }
 
@@ -507,6 +509,8 @@ nfssvc_encode_readres(struct svc_rqst *rqstp, __be32 *p)
 		*p = 0;
 		rqstp->rq_res.tail[0].iov_len = 4 - (resp->count&3);
 	}
+	svc_encode_result_payload(rqstp, rqstp->rq_res.head[0].iov_len,
+				  resp->count);
 	return 1;
 }
 
diff --git a/net/sunrpc/xprtrdma/svc_rdma_sendto.c b/net/sunrpc/xprtrdma/svc_rdma_sendto.c
index c8411b4f3492..d6436c13d5c4 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_sendto.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_sendto.c
@@ -448,7 +448,6 @@ static ssize_t svc_rdma_encode_write_chunk(__be32 *src,
  * svc_rdma_encode_write_list - Encode RPC Reply's Write chunk list
  * @rctxt: Reply context with information about the RPC Call
  * @sctxt: Send context for the RPC Reply
- * @length: size in bytes of the payload in the first Write chunk
  *
  * The client provides a Write chunk list in the Call message. Fill
  * in the segments in the first Write chunk in the Reply's transport
@@ -465,12 +464,12 @@ static ssize_t svc_rdma_encode_write_chunk(__be32 *src,
  */
 static ssize_t
 svc_rdma_encode_write_list(const struct svc_rdma_recv_ctxt *rctxt,
-			   struct svc_rdma_send_ctxt *sctxt,
-			   unsigned int length)
+			   struct svc_rdma_send_ctxt *sctxt)
 {
 	ssize_t len, ret;
 
-	ret = svc_rdma_encode_write_chunk(rctxt->rc_write_list, sctxt, length);
+	ret = svc_rdma_encode_write_chunk(rctxt->rc_write_list, sctxt,
+					  rctxt->rc_read_payload_length);
 	if (ret < 0)
 		return ret;
 	len = ret;
@@ -923,21 +922,12 @@ int svc_rdma_sendto(struct svc_rqst *rqstp)
 		goto err0;
 	if (wr_lst) {
 		/* XXX: Presume the client sent only one Write chunk */
-		unsigned long offset;
-		unsigned int length;
-
-		if (rctxt->rc_read_payload_length) {
-			offset = rctxt->rc_read_payload_offset;
-			length = rctxt->rc_read_payload_length;
-		} else {
-			offset = xdr->head[0].iov_len;
-			length = xdr->page_len;
-		}
-		ret = svc_rdma_send_write_chunk(rdma, wr_lst, xdr, offset,
-						length);
+		ret = svc_rdma_send_write_chunk(rdma, wr_lst, xdr,
+						rctxt->rc_read_payload_offset,
+						rctxt->rc_read_payload_length);
 		if (ret < 0)
 			goto err2;
-		if (svc_rdma_encode_write_list(rctxt, sctxt, length) < 0)
+		if (svc_rdma_encode_write_list(rctxt, sctxt) < 0)
 			goto err0;
 	} else {
 		if (xdr_stream_encode_item_absent(&sctxt->sc_stream) < 0)