[PATCH] Fix regression errors in NFSRDMA

[Steve Wise <swise@opengridcomputing.com>]

From: Tom Tucker <tom@ogc.us>

A few changes regressed the client and server transports for NFSRDMA.

The server regression was caused by the addition of rq_next_page
(afc59400d6c65bad66d4ad0b2daf879cbff8e23e). There were a few places that
were missed with the update of the rq_respages array.

The client regression was due to additional XDR sanity checking
(64bd577ea0021f5903505de061b3b7d8a785ee94) that exposed a latent bug in
the NFSRDMA client. The bug is that if there were inline data, then the
rpcrdma_fixup_inline function would would incorrectly set the XDR page_len
to zero. Since the decode_read3resok logic previously computed this
value from the reported len - header len, the bug was not symptomatic.

Signed-off-by: Tom Tucker <tom@ogc.us>
Tested-by: Steve Wise <swise@ogc.us>
---

 net/sunrpc/xprtrdma/rpc_rdma.c          |    3 +--
 net/sunrpc/xprtrdma/svc_rdma_recvfrom.c |   12 ++++--------
 net/sunrpc/xprtrdma/svc_rdma_sendto.c   |    1 +
 3 files changed, 6 insertions(+), 10 deletions(-)

diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c
index e03725b..e811c40 100644
--- a/net/sunrpc/xprtrdma/rpc_rdma.c
+++ b/net/sunrpc/xprtrdma/rpc_rdma.c
@@ -650,8 +650,7 @@ rpcrdma_inline_fixup(struct rpc_rqst *rqst, char *srcp, int copy_len, int pad)
 			page_base = 0;
 		}
 		rqst->rq_rcv_buf.page_len = olen - copy_len;
-	} else
-		rqst->rq_rcv_buf.page_len = 0;
+	}
 
 	if (copy_len && rqst->rq_rcv_buf.tail[0].iov_len) {
 		curlen = copy_len;
diff --git a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
index 0ce7552..8d904e4 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
@@ -90,6 +90,7 @@ static void rdma_build_arg_xdr(struct svc_rqst *rqstp,
 		sge_no++;
 	}
 	rqstp->rq_respages = &rqstp->rq_pages[sge_no];
+	rqstp->rq_next_page = rqstp->rq_respages + 1;
 
 	/* We should never run out of SGE because the limit is defined to
 	 * support the max allowed RPC data length
@@ -169,6 +170,7 @@ static int map_read_chunks(struct svcxprt_rdma *xprt,
 		 */
 		head->arg.pages[page_no] = rqstp->rq_arg.pages[page_no];
 		rqstp->rq_respages = &rqstp->rq_arg.pages[page_no+1];
+		rqstp->rq_next_page = rqstp->rq_respages + 1;
 
 		byte_count -= sge_bytes;
 		ch_bytes -= sge_bytes;
@@ -276,6 +278,7 @@ static int fast_reg_read_chunks(struct svcxprt_rdma *xprt,
 
 	/* rq_respages points one past arg pages */
 	rqstp->rq_respages = &rqstp->rq_arg.pages[page_no];
+	rqstp->rq_next_page = rqstp->rq_respages + 1;
 
 	/* Create the reply and chunk maps */
 	offset = 0;
@@ -520,13 +523,6 @@ next_sge:
 	for (ch_no = 0; &rqstp->rq_pages[ch_no] < rqstp->rq_respages; ch_no++)
 		rqstp->rq_pages[ch_no] = NULL;
 
-	/*
-	 * Detach res pages. If svc_release sees any it will attempt to
-	 * put them.
-	 */
-	while (rqstp->rq_next_page != rqstp->rq_respages)
-		*(--rqstp->rq_next_page) = NULL;
-
 	return err;
 }
 
@@ -550,7 +546,7 @@ static int rdma_read_complete(struct svc_rqst *rqstp,
 
 	/* rq_respages starts after the last arg page */
 	rqstp->rq_respages = &rqstp->rq_arg.pages[page_no];
-	rqstp->rq_next_page = &rqstp->rq_arg.pages[page_no];
+	rqstp->rq_next_page = rqstp->rq_respages + 1;
 
 	/* Rebuild rq_arg head and tail. */
 	rqstp->rq_arg.head[0] = head->arg.head[0];
diff --git a/net/sunrpc/xprtrdma/svc_rdma_sendto.c b/net/sunrpc/xprtrdma/svc_rdma_sendto.c
index c1d124d..11e90f8 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_sendto.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_sendto.c
@@ -625,6 +625,7 @@ static int send_reply(struct svcxprt_rdma *rdma,
 		if (page_no+1 >= sge_no)
 			ctxt->sge[page_no+1].length = 0;
 	}
+	rqstp->rq_next_page = rqstp->rq_respages + 1;
 	BUG_ON(sge_no > rdma->sc_max_sge);
 	memset(&send_wr, 0, sizeof send_wr);
 	ctxt->wr_op = IB_WR_SEND;