net/sunrpc/xprtrdma/svc_rdma_marshal.c - kernel/mindspeed - Git at Google

 /*
  * Copyright (c) 2005-2006 Network Appliance, Inc. All rights reserved.
  *
  * This software is available to you under a choice of one of two
  * licenses.  You may choose to be licensed under the terms of the GNU
  * General Public License (GPL) Version 2, available from the file
  * COPYING in the main directory of this source tree, or the BSD-type
  * license below:
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  *      Redistributions of source code must retain the above copyright
  *      notice, this list of conditions and the following disclaimer.
  *
  *      Redistributions in binary form must reproduce the above
  *      copyright notice, this list of conditions and the following
  *      disclaimer in the documentation and/or other materials provided
  *      with the distribution.
  *
  *      Neither the name of the Network Appliance, Inc. nor the names of
  *      its contributors may be used to endorse or promote products
  *      derived from this software without specific prior written
  *      permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  * Author: Tom Tucker <tom@opengridcomputing.com>
  */

 #include <linux/sunrpc/xdr.h>
 #include <linux/sunrpc/debug.h>
 #include <asm/unaligned.h>
 #include <linux/sunrpc/rpc_rdma.h>
 #include <linux/sunrpc/svc_rdma.h>

 #define RPCDBG_FACILITY	RPCDBG_SVCXPRT

 /*
  * Decodes a read chunk list. The expected format is as follows:
  *    descrim  : xdr_one
  *    position : u32 offset into XDR stream
  *    handle   : u32 RKEY
  *    . . .
  *  end-of-list: xdr_zero
  */
 static u32 *decode_read_list(u32 *va, u32 *vaend)
 {
 	struct rpcrdma_read_chunk *ch = (struct rpcrdma_read_chunk *)va;

 	while (ch->rc_discrim != xdr_zero) {
 		if (((unsigned long)ch + sizeof(struct rpcrdma_read_chunk)) >
 		    (unsigned long)vaend) {
 			dprintk("svcrdma: vaend=%p, ch=%p\n", vaend, ch);
 			return NULL;
 		}
 		ch++;
 	}
 	return (u32 *)&ch->rc_position;
 }

 /*
  * Decodes a write chunk list. The expected format is as follows:
  *    descrim  : xdr_one
  *    nchunks  : <count>
  *       handle   : u32 RKEY              ---+
  *       length   : u32 <len of segment>     |
  *       offset   : remove va                + <count>
  *       . . .                               |
  *                                        ---+
  */
 static u32 *decode_write_list(u32 *va, u32 *vaend)
 {
 	unsigned long start, end;
 	int nchunks;

 	struct rpcrdma_write_array *ary =
 		(struct rpcrdma_write_array *)va;

 	/* Check for not write-array */
 	if (ary->wc_discrim == xdr_zero)
 		return (u32 *)&ary->wc_nchunks;

 	if ((unsigned long)ary + sizeof(struct rpcrdma_write_array) >
 	    (unsigned long)vaend) {
 		dprintk("svcrdma: ary=%p, vaend=%p\n", ary, vaend);
 		return NULL;
 	}
 	nchunks = ntohl(ary->wc_nchunks);

 	start = (unsigned long)&ary->wc_array[0];
 	end = (unsigned long)vaend;
 	if (nchunks < 0 ||
 	    nchunks > (SIZE_MAX - start) / sizeof(struct rpcrdma_write_chunk) ||
 	    (start + (sizeof(struct rpcrdma_write_chunk) * nchunks)) > end) {
 		dprintk("svcrdma: ary=%p, wc_nchunks=%d, vaend=%p\n",
 			ary, nchunks, vaend);
 		return NULL;
 	}
 	/*
 	 * rs_length is the 2nd 4B field in wc_target and taking its
 	 * address skips the list terminator
 	 */
 	return (u32 *)&ary->wc_array[nchunks].wc_target.rs_length;
 }

 static u32 *decode_reply_array(u32 *va, u32 *vaend)
 {
 	unsigned long start, end;
 	int nchunks;
 	struct rpcrdma_write_array *ary =
 		(struct rpcrdma_write_array *)va;

 	/* Check for no reply-array */
 	if (ary->wc_discrim == xdr_zero)
 		return (u32 *)&ary->wc_nchunks;

 	if ((unsigned long)ary + sizeof(struct rpcrdma_write_array) >
 	    (unsigned long)vaend) {
 		dprintk("svcrdma: ary=%p, vaend=%p\n", ary, vaend);
 		return NULL;
 	}
 	nchunks = ntohl(ary->wc_nchunks);

 	start = (unsigned long)&ary->wc_array[0];
 	end = (unsigned long)vaend;
 	if (nchunks < 0 ||
 	    nchunks > (SIZE_MAX - start) / sizeof(struct rpcrdma_write_chunk) ||
 	    (start + (sizeof(struct rpcrdma_write_chunk) * nchunks)) > end) {
 		dprintk("svcrdma: ary=%p, wc_nchunks=%d, vaend=%p\n",
 			ary, nchunks, vaend);
 		return NULL;
 	}
 	return (u32 *)&ary->wc_array[nchunks];
 }

 int svc_rdma_xdr_decode_req(struct rpcrdma_msg **rdma_req,
 			    struct svc_rqst *rqstp)
 {
 	struct rpcrdma_msg *rmsgp = NULL;
 	u32 *va;
 	u32 *vaend;
 	u32 hdr_len;

 	rmsgp = (struct rpcrdma_msg *)rqstp->rq_arg.head[0].iov_base;

 	/* Verify that there's enough bytes for header + something */
 	if (rqstp->rq_arg.len <= RPCRDMA_HDRLEN_MIN) {
 		dprintk("svcrdma: header too short = %d\n",
 			rqstp->rq_arg.len);
 		return -EINVAL;
 	}

 	/* Decode the header */
 	rmsgp->rm_xid = ntohl(rmsgp->rm_xid);
 	rmsgp->rm_vers = ntohl(rmsgp->rm_vers);
 	rmsgp->rm_credit = ntohl(rmsgp->rm_credit);
 	rmsgp->rm_type = ntohl(rmsgp->rm_type);

 	if (rmsgp->rm_vers != RPCRDMA_VERSION)
 		return -ENOSYS;

 	/* Pull in the extra for the padded case and bump our pointer */
 	if (rmsgp->rm_type == RDMA_MSGP) {
 		int hdrlen;
 		rmsgp->rm_body.rm_padded.rm_align =
 			ntohl(rmsgp->rm_body.rm_padded.rm_align);
 		rmsgp->rm_body.rm_padded.rm_thresh =
 			ntohl(rmsgp->rm_body.rm_padded.rm_thresh);

 		va = &rmsgp->rm_body.rm_padded.rm_pempty[4];
 		rqstp->rq_arg.head[0].iov_base = va;
 		hdrlen = (u32)((unsigned long)va - (unsigned long)rmsgp);
 		rqstp->rq_arg.head[0].iov_len -= hdrlen;
 		if (hdrlen > rqstp->rq_arg.len)
 			return -EINVAL;
 		return hdrlen;
 	}

 	/* The chunk list may contain either a read chunk list or a write
 	 * chunk list and a reply chunk list.
 	 */
 	va = &rmsgp->rm_body.rm_chunks[0];
 	vaend = (u32 *)((unsigned long)rmsgp + rqstp->rq_arg.len);
 	va = decode_read_list(va, vaend);
 	if (!va)
 		return -EINVAL;
 	va = decode_write_list(va, vaend);
 	if (!va)
 		return -EINVAL;
 	va = decode_reply_array(va, vaend);
 	if (!va)
 		return -EINVAL;

 	rqstp->rq_arg.head[0].iov_base = va;
 	hdr_len = (unsigned long)va - (unsigned long)rmsgp;
 	rqstp->rq_arg.head[0].iov_len -= hdr_len;

 	*rdma_req = rmsgp;
 	return hdr_len;
 }

 int svc_rdma_xdr_decode_deferred_req(struct svc_rqst *rqstp)
 {
 	struct rpcrdma_msg *rmsgp = NULL;
 	struct rpcrdma_read_chunk *ch;
 	struct rpcrdma_write_array *ary;
 	u32 *va;
 	u32 hdrlen;

 	dprintk("svcrdma: processing deferred RDMA header on rqstp=%p\n",
 		rqstp);
 	rmsgp = (struct rpcrdma_msg *)rqstp->rq_arg.head[0].iov_base;

 	/* Pull in the extra for the padded case and bump our pointer */
 	if (rmsgp->rm_type == RDMA_MSGP) {
 		va = &rmsgp->rm_body.rm_padded.rm_pempty[4];
 		rqstp->rq_arg.head[0].iov_base = va;
 		hdrlen = (u32)((unsigned long)va - (unsigned long)rmsgp);
 		rqstp->rq_arg.head[0].iov_len -= hdrlen;
 		return hdrlen;
 	}

 	/*
 	 * Skip all chunks to find RPC msg. These were previously processed
 	 */
 	va = &rmsgp->rm_body.rm_chunks[0];

 	/* Skip read-list */
 	for (ch = (struct rpcrdma_read_chunk *)va;
 	     ch->rc_discrim != xdr_zero; ch++);
 	va = (u32 *)&ch->rc_position;

 	/* Skip write-list */
 	ary = (struct rpcrdma_write_array *)va;
 	if (ary->wc_discrim == xdr_zero)
 		va = (u32 *)&ary->wc_nchunks;
 	else
 		/*
 		 * rs_length is the 2nd 4B field in wc_target and taking its
 		 * address skips the list terminator
 		 */
 		va = (u32 *)&ary->wc_array[ary->wc_nchunks].wc_target.rs_length;

 	/* Skip reply-array */
 	ary = (struct rpcrdma_write_array *)va;
 	if (ary->wc_discrim == xdr_zero)
 		va = (u32 *)&ary->wc_nchunks;
 	else
 		va = (u32 *)&ary->wc_array[ary->wc_nchunks];

 	rqstp->rq_arg.head[0].iov_base = va;
 	hdrlen = (unsigned long)va - (unsigned long)rmsgp;
 	rqstp->rq_arg.head[0].iov_len -= hdrlen;

 	return hdrlen;
 }

 int svc_rdma_xdr_encode_error(struct svcxprt_rdma *xprt,
 			      struct rpcrdma_msg *rmsgp,
 			      enum rpcrdma_errcode err, u32 *va)
 {
 	u32 *startp = va;

 	*va++ = htonl(rmsgp->rm_xid);
 	*va++ = htonl(rmsgp->rm_vers);
 	*va++ = htonl(xprt->sc_max_requests);
 	*va++ = htonl(RDMA_ERROR);
 	*va++ = htonl(err);
 	if (err == ERR_VERS) {
 		*va++ = htonl(RPCRDMA_VERSION);
 		*va++ = htonl(RPCRDMA_VERSION);
 	}

 	return (int)((unsigned long)va - (unsigned long)startp);
 }

 int svc_rdma_xdr_get_reply_hdr_len(struct rpcrdma_msg *rmsgp)
 {
 	struct rpcrdma_write_array *wr_ary;

 	/* There is no read-list in a reply */

 	/* 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[ntohl(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[ntohl(wr_ary->wc_nchunks)];
 	else
 		wr_ary = (struct rpcrdma_write_array *)
 			&wr_ary->wc_nchunks;

 	return (unsigned long) wr_ary - (unsigned long) rmsgp;
 }

 void svc_rdma_xdr_encode_write_list(struct rpcrdma_msg *rmsgp, int chunks)
 {
 	struct rpcrdma_write_array *ary;

 	/* no read-list */
 	rmsgp->rm_body.rm_chunks[0] = xdr_zero;

 	/* write-array discrim */
 	ary = (struct rpcrdma_write_array *)
 		&rmsgp->rm_body.rm_chunks[1];
 	ary->wc_discrim = xdr_one;
 	ary->wc_nchunks = htonl(chunks);

 	/* write-list terminator */
 	ary->wc_array[chunks].wc_target.rs_handle = xdr_zero;

 	/* reply-array discriminator */
 	ary->wc_array[chunks].wc_target.rs_length = xdr_zero;
 }

 void svc_rdma_xdr_encode_reply_array(struct rpcrdma_write_array *ary,
 				 int chunks)
 {
 	ary->wc_discrim = xdr_one;
 	ary->wc_nchunks = htonl(chunks);
 }

 void svc_rdma_xdr_encode_array_chunk(struct rpcrdma_write_array *ary,
 				     int chunk_no,
 				     __be32 rs_handle,
 				     __be64 rs_offset,
 				     u32 write_len)
 {
 	struct rpcrdma_segment *seg = &ary->wc_array[chunk_no].wc_target;
 	seg->rs_handle = rs_handle;
 	seg->rs_offset = rs_offset;
 	seg->rs_length = htonl(write_len);
 }

 void svc_rdma_xdr_encode_reply_header(struct svcxprt_rdma *xprt,
 				  struct rpcrdma_msg *rdma_argp,
 				  struct rpcrdma_msg *rdma_resp,
 				  enum rpcrdma_proc rdma_type)
 {
 	rdma_resp->rm_xid = htonl(rdma_argp->rm_xid);
 	rdma_resp->rm_vers = htonl(rdma_argp->rm_vers);
 	rdma_resp->rm_credit = htonl(xprt->sc_max_requests);
 	rdma_resp->rm_type = htonl(rdma_type);

 	/* Encode <nul> chunks lists */
 	rdma_resp->rm_body.rm_chunks[0] = xdr_zero;
 	rdma_resp->rm_body.rm_chunks[1] = xdr_zero;
 	rdma_resp->rm_body.rm_chunks[2] = xdr_zero;
 }
	/*
	* Copyright (c) 2005-2006 Network Appliance, Inc. All rights reserved.
	*
	* This software is available to you under a choice of one of two
	* licenses. You may choose to be licensed under the terms of the GNU
	* General Public License (GPL) Version 2, available from the file
	* COPYING in the main directory of this source tree, or the BSD-type
	* license below:
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions
	* are met:
	*
	* Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	*
	* Redistributions in binary form must reproduce the above
	* copyright notice, this list of conditions and the following
	* disclaimer in the documentation and/or other materials provided
	* with the distribution.
	*
	* Neither the name of the Network Appliance, Inc. nor the names of
	* its contributors may be used to endorse or promote products
	* derived from this software without specific prior written
	* permission.
	*
	* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
	* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
	* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
	* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
	* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
	* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
	* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*
	* Author: Tom Tucker <tom@opengridcomputing.com>
	*/

	#include <linux/sunrpc/xdr.h>
	#include <linux/sunrpc/debug.h>
	#include <asm/unaligned.h>
	#include <linux/sunrpc/rpc_rdma.h>
	#include <linux/sunrpc/svc_rdma.h>

	#define RPCDBG_FACILITY RPCDBG_SVCXPRT

	/*
	* Decodes a read chunk list. The expected format is as follows:
	* descrim : xdr_one
	* position : u32 offset into XDR stream
	* handle : u32 RKEY
	* . . .
	* end-of-list: xdr_zero
	*/
	static u32 decode_read_list(u32 va, u32 *vaend)
	{
	struct rpcrdma_read_chunk ch = (struct rpcrdma_read_chunk )va;

	while (ch->rc_discrim != xdr_zero) {
	if (((unsigned long)ch + sizeof(struct rpcrdma_read_chunk)) >
	(unsigned long)vaend) {
	dprintk("svcrdma: vaend=%p, ch=%p\n", vaend, ch);
	return NULL;
	}
	ch++;
	}
	return (u32 *)&ch->rc_position;
	}

	/*
	* Decodes a write chunk list. The expected format is as follows:
	* descrim : xdr_one
	* nchunks : <count>
	* handle : u32 RKEY ---+
	* length : u32 <len of segment> \|
	* offset : remove va + <count>
	* . . . \|
	* ---+
	*/
	static u32 decode_write_list(u32 va, u32 *vaend)
	{
	unsigned long start, end;
	int nchunks;

	struct rpcrdma_write_array *ary =
	(struct rpcrdma_write_array *)va;

	/* Check for not write-array */
	if (ary->wc_discrim == xdr_zero)
	return (u32 *)&ary->wc_nchunks;

	if ((unsigned long)ary + sizeof(struct rpcrdma_write_array) >
	(unsigned long)vaend) {
	dprintk("svcrdma: ary=%p, vaend=%p\n", ary, vaend);
	return NULL;
	}
	nchunks = ntohl(ary->wc_nchunks);

	start = (unsigned long)&ary->wc_array[0];
	end = (unsigned long)vaend;
	if (nchunks < 0 \|\|
	nchunks > (SIZE_MAX - start) / sizeof(struct rpcrdma_write_chunk) \|\|
	(start + (sizeof(struct rpcrdma_write_chunk) * nchunks)) > end) {
	dprintk("svcrdma: ary=%p, wc_nchunks=%d, vaend=%p\n",
	ary, nchunks, vaend);
	return NULL;
	}
	/*
	* rs_length is the 2nd 4B field in wc_target and taking its
	* address skips the list terminator
	*/
	return (u32 *)&ary->wc_array[nchunks].wc_target.rs_length;
	}

	static u32 decode_reply_array(u32 va, u32 *vaend)
	{
	unsigned long start, end;
	int nchunks;
	struct rpcrdma_write_array *ary =
	(struct rpcrdma_write_array *)va;

	/* Check for no reply-array */
	if (ary->wc_discrim == xdr_zero)
	return (u32 *)&ary->wc_nchunks;

	if ((unsigned long)ary + sizeof(struct rpcrdma_write_array) >
	(unsigned long)vaend) {
	dprintk("svcrdma: ary=%p, vaend=%p\n", ary, vaend);
	return NULL;
	}
	nchunks = ntohl(ary->wc_nchunks);

	start = (unsigned long)&ary->wc_array[0];
	end = (unsigned long)vaend;
	if (nchunks < 0 \|\|
	nchunks > (SIZE_MAX - start) / sizeof(struct rpcrdma_write_chunk) \|\|
	(start + (sizeof(struct rpcrdma_write_chunk) * nchunks)) > end) {
	dprintk("svcrdma: ary=%p, wc_nchunks=%d, vaend=%p\n",
	ary, nchunks, vaend);
	return NULL;
	}
	return (u32 *)&ary->wc_array[nchunks];
	}

	int svc_rdma_xdr_decode_req(struct rpcrdma_msg **rdma_req,
	struct svc_rqst *rqstp)
	{
	struct rpcrdma_msg *rmsgp = NULL;
	u32 *va;
	u32 *vaend;
	u32 hdr_len;

	rmsgp = (struct rpcrdma_msg *)rqstp->rq_arg.head[0].iov_base;

	/* Verify that there's enough bytes for header + something */
	if (rqstp->rq_arg.len <= RPCRDMA_HDRLEN_MIN) {
	dprintk("svcrdma: header too short = %d\n",
	rqstp->rq_arg.len);
	return -EINVAL;
	}

	/* Decode the header */
	rmsgp->rm_xid = ntohl(rmsgp->rm_xid);
	rmsgp->rm_vers = ntohl(rmsgp->rm_vers);
	rmsgp->rm_credit = ntohl(rmsgp->rm_credit);
	rmsgp->rm_type = ntohl(rmsgp->rm_type);

	if (rmsgp->rm_vers != RPCRDMA_VERSION)
	return -ENOSYS;

	/* Pull in the extra for the padded case and bump our pointer */
	if (rmsgp->rm_type == RDMA_MSGP) {
	int hdrlen;
	rmsgp->rm_body.rm_padded.rm_align =
	ntohl(rmsgp->rm_body.rm_padded.rm_align);
	rmsgp->rm_body.rm_padded.rm_thresh =
	ntohl(rmsgp->rm_body.rm_padded.rm_thresh);

	va = &rmsgp->rm_body.rm_padded.rm_pempty[4];
	rqstp->rq_arg.head[0].iov_base = va;
	hdrlen = (u32)((unsigned long)va - (unsigned long)rmsgp);
	rqstp->rq_arg.head[0].iov_len -= hdrlen;
	if (hdrlen > rqstp->rq_arg.len)
	return -EINVAL;
	return hdrlen;
	}

	/* The chunk list may contain either a read chunk list or a write
	* chunk list and a reply chunk list.
	*/
	va = &rmsgp->rm_body.rm_chunks[0];
	vaend = (u32 *)((unsigned long)rmsgp + rqstp->rq_arg.len);
	va = decode_read_list(va, vaend);
	if (!va)
	return -EINVAL;
	va = decode_write_list(va, vaend);
	if (!va)
	return -EINVAL;
	va = decode_reply_array(va, vaend);
	if (!va)
	return -EINVAL;

	rqstp->rq_arg.head[0].iov_base = va;
	hdr_len = (unsigned long)va - (unsigned long)rmsgp;
	rqstp->rq_arg.head[0].iov_len -= hdr_len;

	*rdma_req = rmsgp;
	return hdr_len;
	}

	int svc_rdma_xdr_decode_deferred_req(struct svc_rqst *rqstp)
	{
	struct rpcrdma_msg *rmsgp = NULL;
	struct rpcrdma_read_chunk *ch;
	struct rpcrdma_write_array *ary;
	u32 *va;
	u32 hdrlen;

	dprintk("svcrdma: processing deferred RDMA header on rqstp=%p\n",
	rqstp);
	rmsgp = (struct rpcrdma_msg *)rqstp->rq_arg.head[0].iov_base;

	/* Pull in the extra for the padded case and bump our pointer */
	if (rmsgp->rm_type == RDMA_MSGP) {
	va = &rmsgp->rm_body.rm_padded.rm_pempty[4];
	rqstp->rq_arg.head[0].iov_base = va;
	hdrlen = (u32)((unsigned long)va - (unsigned long)rmsgp);
	rqstp->rq_arg.head[0].iov_len -= hdrlen;
	return hdrlen;
	}

	/*
	* Skip all chunks to find RPC msg. These were previously processed
	*/
	va = &rmsgp->rm_body.rm_chunks[0];

	/* Skip read-list */
	for (ch = (struct rpcrdma_read_chunk *)va;
	ch->rc_discrim != xdr_zero; ch++);
	va = (u32 *)&ch->rc_position;

	/* Skip write-list */
	ary = (struct rpcrdma_write_array *)va;
	if (ary->wc_discrim == xdr_zero)
	va = (u32 *)&ary->wc_nchunks;
	else
	/*
	* rs_length is the 2nd 4B field in wc_target and taking its
	* address skips the list terminator
	*/
	va = (u32 *)&ary->wc_array[ary->wc_nchunks].wc_target.rs_length;

	/* Skip reply-array */
	ary = (struct rpcrdma_write_array *)va;
	if (ary->wc_discrim == xdr_zero)
	va = (u32 *)&ary->wc_nchunks;
	else
	va = (u32 *)&ary->wc_array[ary->wc_nchunks];

	rqstp->rq_arg.head[0].iov_base = va;
	hdrlen = (unsigned long)va - (unsigned long)rmsgp;
	rqstp->rq_arg.head[0].iov_len -= hdrlen;

	return hdrlen;
	}

	int svc_rdma_xdr_encode_error(struct svcxprt_rdma *xprt,
	struct rpcrdma_msg *rmsgp,
	enum rpcrdma_errcode err, u32 *va)
	{
	u32 *startp = va;

	*va++ = htonl(rmsgp->rm_xid);
	*va++ = htonl(rmsgp->rm_vers);
	*va++ = htonl(xprt->sc_max_requests);
	*va++ = htonl(RDMA_ERROR);
	*va++ = htonl(err);
	if (err == ERR_VERS) {
	*va++ = htonl(RPCRDMA_VERSION);
	*va++ = htonl(RPCRDMA_VERSION);
	}

	return (int)((unsigned long)va - (unsigned long)startp);
	}

	int svc_rdma_xdr_get_reply_hdr_len(struct rpcrdma_msg *rmsgp)
	{
	struct rpcrdma_write_array *wr_ary;

	/* There is no read-list in a reply */

	/* 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[ntohl(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[ntohl(wr_ary->wc_nchunks)];
	else
	wr_ary = (struct rpcrdma_write_array *)
	&wr_ary->wc_nchunks;

	return (unsigned long) wr_ary - (unsigned long) rmsgp;
	}

	void svc_rdma_xdr_encode_write_list(struct rpcrdma_msg *rmsgp, int chunks)
	{
	struct rpcrdma_write_array *ary;

	/* no read-list */
	rmsgp->rm_body.rm_chunks[0] = xdr_zero;

	/* write-array discrim */
	ary = (struct rpcrdma_write_array *)
	&rmsgp->rm_body.rm_chunks[1];
	ary->wc_discrim = xdr_one;
	ary->wc_nchunks = htonl(chunks);

	/* write-list terminator */
	ary->wc_array[chunks].wc_target.rs_handle = xdr_zero;

	/* reply-array discriminator */
	ary->wc_array[chunks].wc_target.rs_length = xdr_zero;
	}

	void svc_rdma_xdr_encode_reply_array(struct rpcrdma_write_array *ary,
	int chunks)
	{
	ary->wc_discrim = xdr_one;
	ary->wc_nchunks = htonl(chunks);
	}

	void svc_rdma_xdr_encode_array_chunk(struct rpcrdma_write_array *ary,
	int chunk_no,
	__be32 rs_handle,
	__be64 rs_offset,
	u32 write_len)
	{
	struct rpcrdma_segment *seg = &ary->wc_array[chunk_no].wc_target;
	seg->rs_handle = rs_handle;
	seg->rs_offset = rs_offset;
	seg->rs_length = htonl(write_len);
	}

	void svc_rdma_xdr_encode_reply_header(struct svcxprt_rdma *xprt,
	struct rpcrdma_msg *rdma_argp,
	struct rpcrdma_msg *rdma_resp,
	enum rpcrdma_proc rdma_type)
	{
	rdma_resp->rm_xid = htonl(rdma_argp->rm_xid);
	rdma_resp->rm_vers = htonl(rdma_argp->rm_vers);
	rdma_resp->rm_credit = htonl(xprt->sc_max_requests);
	rdma_resp->rm_type = htonl(rdma_type);

	/* Encode <nul> chunks lists */
	rdma_resp->rm_body.rm_chunks[0] = xdr_zero;
	rdma_resp->rm_body.rm_chunks[1] = xdr_zero;
	rdma_resp->rm_body.rm_chunks[2] = xdr_zero;
	}