[PATCH RFC 4/9] NFSD: Invoke svc_encode_read_payload in "read" NFSD encoders

[Chuck Lever <chuck.lever@xxxxxxxxxx>]

Have the NFSD encoders annotate the boundaries of every
direct-data-placement eligible READ 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
READ payloads per compound. Next step is to support multiple Write
chunks.

Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
---
 fs/nfsd/nfs3xdr.c                     |    4 ++++
 fs/nfsd/nfs4xdr.c                     |    3 +++
 fs/nfsd/nfsxdr.c                      |    4 ++++
 net/sunrpc/xprtrdma/svc_rdma_sendto.c |   15 +++------------
 4 files changed, 14 insertions(+), 12 deletions(-)

diff --git a/fs/nfsd/nfs3xdr.c b/fs/nfsd/nfs3xdr.c
index aae514d40b64..8c272efbc94e 100644
--- a/fs/nfsd/nfs3xdr.c
+++ b/fs/nfsd/nfs3xdr.c
@@ -712,6 +712,8 @@ void fill_post_wcc(struct svc_fh *fhp)
 			*p = 0;
 			rqstp->rq_res.tail[0].iov_len = 4 - (resp->len&3);
 		}
+		svc_encode_read_payload(rqstp, rqstp->rq_res.head[0].iov_len,
+					resp->len);
 		return 1;
 	} else
 		return xdr_ressize_check(rqstp, p);
@@ -737,6 +739,8 @@ void fill_post_wcc(struct svc_fh *fhp)
 			*p = 0;
 			rqstp->rq_res.tail[0].iov_len = 4 - (resp->count & 3);
 		}
+		svc_encode_read_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 262f9fc76e4e..a8d3f8f035a0 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -3547,6 +3547,8 @@ static __be32 nfsd4_encode_splice_read(
 		buf->page_len = 0;
 		return nfserr;
 	}
+	svc_encode_read_payload(read->rd_rqstp, buf->head[0].iov_len,
+				maxcount);
 
 	*(p++) = htonl(eof);
 	*(p++) = htonl(maxcount);
@@ -3713,6 +3715,7 @@ static __be32 nfsd4_encode_readv(struct nfsd4_compoundres *resp,
 		xdr_truncate_encode(xdr, length_offset);
 		return nfserr;
 	}
+	svc_encode_read_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 b51fe515f06f..98ea417042a6 100644
--- a/fs/nfsd/nfsxdr.c
+++ b/fs/nfsd/nfsxdr.c
@@ -462,6 +462,8 @@ __be32 *nfs2svc_encode_fattr(struct svc_rqst *rqstp, __be32 *p, struct svc_fh *f
 		*p = 0;
 		rqstp->rq_res.tail[0].iov_len = 4 - (resp->len&3);
 	}
+	svc_encode_read_payload(rqstp, rqstp->rq_res.head[0].iov_len,
+				resp->len);
 	return 1;
 }
 
@@ -482,6 +484,8 @@ __be32 *nfs2svc_encode_fattr(struct svc_rqst *rqstp, __be32 *p, struct svc_fh *f
 		*p = 0;
 		rqstp->rq_res.tail[0].iov_len = 4 - (resp->count&3);
 	}
+	svc_encode_read_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 8ea21ca351e2..40b4843be869 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_sendto.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_sendto.c
@@ -875,18 +875,9 @@ int svc_rdma_sendto(struct svc_rqst *rqstp)
 
 	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;
 		svc_rdma_xdr_encode_write_list(rdma_resp, wr_lst, ret);