[deliverable/linux.git] / include / linux / sunrpc / svc_rdma.h

/*
 * 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>
 */

#ifndef SVC_RDMA_H
#define SVC_RDMA_H
#include <linux/sunrpc/xdr.h>
#include <linux/sunrpc/svcsock.h>
#include <linux/sunrpc/rpc_rdma.h>
#include <rdma/ib_verbs.h>
#include <rdma/rdma_cm.h>
#define SVCRDMA_DEBUG

/* RPC/RDMA parameters and stats */
extern unsigned int svcrdma_ord;
extern unsigned int svcrdma_max_requests;
extern unsigned int svcrdma_max_req_size;

extern atomic_t rdma_stat_recv;
extern atomic_t rdma_stat_read;
extern atomic_t rdma_stat_write;
extern atomic_t rdma_stat_sq_starve;
extern atomic_t rdma_stat_rq_starve;
extern atomic_t rdma_stat_rq_poll;
extern atomic_t rdma_stat_rq_prod;
extern atomic_t rdma_stat_sq_poll;
extern atomic_t rdma_stat_sq_prod;

#define RPCRDMA_VERSION 1

/*
 * Contexts are built when an RDMA request is created and are a
 * record of the resources that can be recovered when the request
 * completes.
 */
struct svc_rdma_op_ctxt {
	struct svc_rdma_op_ctxt *read_hdr;
	int hdr_count;
	struct list_head free_list;
	struct xdr_buf arg;
	struct list_head dto_q;
	enum ib_wr_opcode wr_op;
	enum ib_wc_status wc_status;
	u32 byte_len;
	struct svcxprt_rdma *xprt;
	unsigned long flags;
	enum dma_data_direction direction;
	int count;
	struct ib_sge sge[RPCSVC_MAXPAGES];
	struct page *pages[RPCSVC_MAXPAGES];
};

/*
 * NFS_ requests are mapped on the client side by the chunk lists in
 * the RPCRDMA header. During the fetching of the RPC from the client
 * and the writing of the reply to the client, the memory in the
 * client and the memory in the server must be mapped as contiguous
 * vaddr/len for access by the hardware. These data strucures keep
 * these mappings.
 *
 * For an RDMA_WRITE, the 'sge' maps the RPC REPLY. For RDMA_READ, the
 * 'sge' in the svc_rdma_req_map maps the server side RPC reply and the
 * 'ch' field maps the read-list of the RPCRDMA header to the 'sge'
 * mapping of the reply.
 */
struct svc_rdma_chunk_sge {
	int start;		/* sge no for this chunk */
	int count;		/* sge count for this chunk */
};
struct svc_rdma_req_map {
	unsigned long count;
	union {
		struct kvec sge[RPCSVC_MAXPAGES];
		struct svc_rdma_chunk_sge ch[RPCSVC_MAXPAGES];
	};
};

#define RDMACTXT_F_LAST_CTXT	2

struct svcxprt_rdma {
	struct svc_xprt      sc_xprt;		/* SVC transport structure */
	struct rdma_cm_id    *sc_cm_id;		/* RDMA connection id */
	struct list_head     sc_accept_q;	/* Conn. waiting accept */
	int		     sc_ord;		/* RDMA read limit */
	wait_queue_head_t    sc_read_wait;
	int                  sc_max_sge;

	int                  sc_sq_depth;	/* Depth of SQ */
	atomic_t             sc_sq_count;	/* Number of SQ WR on queue */

	int                  sc_max_requests;	/* Depth of RQ */
	int                  sc_max_req_size;	/* Size of each RQ WR buf */

	struct ib_pd         *sc_pd;

	atomic_t	     sc_ctxt_used;
	struct list_head     sc_ctxt_free;
	int		     sc_ctxt_cnt;
	int		     sc_ctxt_bump;
	int		     sc_ctxt_max;
	spinlock_t	     sc_ctxt_lock;
	struct list_head     sc_rq_dto_q;
	spinlock_t	     sc_rq_dto_lock;
	struct ib_qp         *sc_qp;
	struct ib_cq         *sc_rq_cq;
	struct ib_cq         *sc_sq_cq;
	struct ib_mr         *sc_phys_mr;	/* MR for server memory */

	spinlock_t	     sc_lock;		/* transport lock */

	wait_queue_head_t    sc_send_wait;	/* SQ exhaustion waitlist */
	unsigned long	     sc_flags;
	struct list_head     sc_dto_q;		/* DTO tasklet I/O pending Q */
	struct list_head     sc_read_complete_q;
	spinlock_t           sc_read_complete_lock;
	struct work_struct   sc_work;
};
/* sc_flags */
#define RDMAXPRT_RQ_PENDING	1
#define RDMAXPRT_SQ_PENDING	2
#define RDMAXPRT_CONN_PENDING	3

#define RPCRDMA_LISTEN_BACKLOG  10
/* The default ORD value is based on two outstanding full-size writes with a
 * page size of 4k, or 32k * 2 ops / 4k = 16 outstanding RDMA_READ.  */
#define RPCRDMA_ORD             (64/4)
#define RPCRDMA_SQ_DEPTH_MULT   8
#define RPCRDMA_MAX_THREADS     16
#define RPCRDMA_MAX_REQUESTS    16
#define RPCRDMA_MAX_REQ_SIZE    4096

/* svc_rdma_marshal.c */
extern void svc_rdma_rcl_chunk_counts(struct rpcrdma_read_chunk *,
				      int *, int *);
extern int svc_rdma_xdr_decode_req(struct rpcrdma_msg **, struct svc_rqst *);
extern int svc_rdma_xdr_decode_deferred_req(struct svc_rqst *);
extern int svc_rdma_xdr_encode_error(struct svcxprt_rdma *,
				     struct rpcrdma_msg *,
				     enum rpcrdma_errcode, u32 *);
extern void svc_rdma_xdr_encode_write_list(struct rpcrdma_msg *, int);
extern void svc_rdma_xdr_encode_reply_array(struct rpcrdma_write_array *, int);
extern void svc_rdma_xdr_encode_array_chunk(struct rpcrdma_write_array *, int,
					    u32, u64, u32);
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 *);

/* svc_rdma_recvfrom.c */
extern int svc_rdma_recvfrom(struct svc_rqst *);

/* svc_rdma_sendto.c */
extern int svc_rdma_sendto(struct svc_rqst *);

/* svc_rdma_transport.c */
extern int svc_rdma_send(struct svcxprt_rdma *, struct ib_send_wr *);
extern void svc_rdma_send_error(struct svcxprt_rdma *, struct rpcrdma_msg *,
				enum rpcrdma_errcode);
struct page *svc_rdma_get_page(void);
extern int svc_rdma_post_recv(struct svcxprt_rdma *);
extern int svc_rdma_create_listen(struct svc_serv *, int, struct sockaddr *);
extern struct svc_rdma_op_ctxt *svc_rdma_get_context(struct svcxprt_rdma *);
extern void svc_rdma_put_context(struct svc_rdma_op_ctxt *, int);
extern struct svc_rdma_req_map *svc_rdma_get_req_map(void);
extern void svc_rdma_put_req_map(struct svc_rdma_req_map *);
extern void svc_sq_reap(struct svcxprt_rdma *);
extern void svc_rq_reap(struct svcxprt_rdma *);
extern struct svc_xprt_class svc_rdma_class;
extern void svc_rdma_prep_reply_hdr(struct svc_rqst *);

/* svc_rdma.c */
extern int svc_rdma_init(void);
extern void svc_rdma_cleanup(void);

/*
 * Returns the address of the first read chunk or <nul> if no read chunk is
 * present
 */
static inline struct rpcrdma_read_chunk *
svc_rdma_get_read_chunk(struct rpcrdma_msg *rmsgp)
{
	struct rpcrdma_read_chunk *ch =
		(struct rpcrdma_read_chunk *)&rmsgp->rm_body.rm_chunks[0];

	if (ch->rc_discrim == 0)
		return NULL;

	return ch;
}

/*
 * Returns the address of the first read write array element or <nul> if no
 * write array list is present
 */
static inline struct rpcrdma_write_array *
svc_rdma_get_write_array(struct rpcrdma_msg *rmsgp)
{
	if (rmsgp->rm_body.rm_chunks[0] != 0
	    || rmsgp->rm_body.rm_chunks[1] == 0)
		return NULL;

	return (struct rpcrdma_write_array *)&rmsgp->rm_body.rm_chunks[1];
}

/*
 * Returns the address of the first reply array element or <nul> if no
 * reply array is present
 */
static inline struct rpcrdma_write_array *
svc_rdma_get_reply_array(struct rpcrdma_msg *rmsgp)
{
	struct rpcrdma_read_chunk *rch;
	struct rpcrdma_write_array *wr_ary;
	struct rpcrdma_write_array *rp_ary;

	/* XXX: Need to fix when reply list may occur with read-list and/or
	 * write list */
	if (rmsgp->rm_body.rm_chunks[0] != 0 ||
	    rmsgp->rm_body.rm_chunks[1] != 0)
		return NULL;

	rch = svc_rdma_get_read_chunk(rmsgp);
	if (rch) {
		while (rch->rc_discrim)
			rch++;

		/* The reply list follows an empty write array located
		 * at 'rc_position' here. The reply array is at rc_target.
		 */
		rp_ary = (struct rpcrdma_write_array *)&rch->rc_target;

		goto found_it;
	}

	wr_ary = svc_rdma_get_write_array(rmsgp);
	if (wr_ary) {
		rp_ary = (struct rpcrdma_write_array *)
			&wr_ary->
			wc_array[wr_ary->wc_nchunks].wc_target.rs_length;

		goto found_it;
	}

	/* No read list, no write list */
	rp_ary = (struct rpcrdma_write_array *)
		&rmsgp->rm_body.rm_chunks[2];

 found_it:
	if (rp_ary->wc_discrim == 0)
		return NULL;

	return rp_ary;
}
#endif
Commit	Line	Data
d21b05f1 TT	1	/*
	2	* Copyright (c) 2005-2006 Network Appliance, Inc. All rights reserved.
	3	*
	4	* This software is available to you under a choice of one of two
	5	* licenses. You may choose to be licensed under the terms of the GNU
	6	* General Public License (GPL) Version 2, available from the file
	7	* COPYING in the main directory of this source tree, or the BSD-type
	8	* license below:
	9	*
	10	* Redistribution and use in source and binary forms, with or without
	11	* modification, are permitted provided that the following conditions
	12	* are met:
	13	*
	14	* Redistributions of source code must retain the above copyright
	15	* notice, this list of conditions and the following disclaimer.
	16	*
	17	* Redistributions in binary form must reproduce the above
	18	* copyright notice, this list of conditions and the following
	19	* disclaimer in the documentation and/or other materials provided
	20	* with the distribution.
	21	*
	22	* Neither the name of the Network Appliance, Inc. nor the names of
	23	* its contributors may be used to endorse or promote products
	24	* derived from this software without specific prior written
	25	* permission.
	26	*
	27	* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
	28	* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
	29	* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
	30	* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
	31	* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	32	* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
	33	* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	34	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	35	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	36	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
	37	* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	38	*
	39	* Author: Tom Tucker <tom@opengridcomputing.com>
	40	*/
	41
	42	#ifndef SVC_RDMA_H
	43	#define SVC_RDMA_H
	44	#include <linux/sunrpc/xdr.h>
	45	#include <linux/sunrpc/svcsock.h>
	46	#include <linux/sunrpc/rpc_rdma.h>
	47	#include <rdma/ib_verbs.h>
	48	#include <rdma/rdma_cm.h>
	49	#define SVCRDMA_DEBUG
	50
	51	/* RPC/RDMA parameters and stats */
	52	extern unsigned int svcrdma_ord;
	53	extern unsigned int svcrdma_max_requests;
	54	extern unsigned int svcrdma_max_req_size;
	55
	56	extern atomic_t rdma_stat_recv;
	57	extern atomic_t rdma_stat_read;
	58	extern atomic_t rdma_stat_write;
	59	extern atomic_t rdma_stat_sq_starve;
	60	extern atomic_t rdma_stat_rq_starve;
	61	extern atomic_t rdma_stat_rq_poll;
	62	extern atomic_t rdma_stat_rq_prod;
	63	extern atomic_t rdma_stat_sq_poll;
	64	extern atomic_t rdma_stat_sq_prod;
65
66	#define RPCRDMA_VERSION 1
67
68	/*
69	* Contexts are built when an RDMA request is created and are a
70	* record of the resources that can be recovered when the request
71	* completes.
72	*/
73	struct svc_rdma_op_ctxt {
02e7452d	74	struct svc_rdma_op_ctxt *read_hdr;
f820c57e	75	int hdr_count;
87407673	76	struct list_head free_list;
d21b05f1 TT	77	struct xdr_buf arg;
	78	struct list_head dto_q;
	79	enum ib_wr_opcode wr_op;
	80	enum ib_wc_status wc_status;
	81	u32 byte_len;
	82	struct svcxprt_rdma *xprt;
	83	unsigned long flags;
	84	enum dma_data_direction direction;
	85	int count;
	86	struct ib_sge sge[RPCSVC_MAXPAGES];
	87	struct page *pages[RPCSVC_MAXPAGES];
	88	};
	89
ab96dddb TT	90	/*
	91	* NFS_ requests are mapped on the client side by the chunk lists in
	92	* the RPCRDMA header. During the fetching of the RPC from the client
	93	* and the writing of the reply to the client, the memory in the
	94	* client and the memory in the server must be mapped as contiguous
	95	* vaddr/len for access by the hardware. These data strucures keep
	96	* these mappings.
	97	*
	98	* For an RDMA_WRITE, the 'sge' maps the RPC REPLY. For RDMA_READ, the
	99	* 'sge' in the svc_rdma_req_map maps the server side RPC reply and the
	100	* 'ch' field maps the read-list of the RPCRDMA header to the 'sge'
	101	* mapping of the reply.
	102	*/
	103	struct svc_rdma_chunk_sge {
	104	int start; /* sge no for this chunk */
	105	int count; /* sge count for this chunk */
	106	};
	107	struct svc_rdma_req_map {
	108	unsigned long count;
	109	union {
	110	struct kvec sge[RPCSVC_MAXPAGES];
	111	struct svc_rdma_chunk_sge ch[RPCSVC_MAXPAGES];
	112	};
	113	};
	114
d21b05f1 TT	115	#define RDMACTXT_F_LAST_CTXT 2
	116
	117	struct svcxprt_rdma {
	118	struct svc_xprt sc_xprt; /* SVC transport structure */
	119	struct rdma_cm_id sc_cm_id; / RDMA connection id */
	120	struct list_head sc_accept_q; /* Conn. waiting accept */
	121	int sc_ord; /* RDMA read limit */
	122	wait_queue_head_t sc_read_wait;
	123	int sc_max_sge;
	124
	125	int sc_sq_depth; /* Depth of SQ */
	126	atomic_t sc_sq_count; /* Number of SQ WR on queue */
	127
	128	int sc_max_requests; /* Depth of RQ */
	129	int sc_max_req_size; /* Size of each RQ WR buf */
	130
	131	struct ib_pd *sc_pd;
	132
87407673 TT	133	atomic_t sc_ctxt_used;
87407673 TT	134	struct list_head sc_ctxt_free;
d21b05f1 TT	135	int sc_ctxt_cnt;
	136	int sc_ctxt_bump;
	137	int sc_ctxt_max;
	138	spinlock_t sc_ctxt_lock;
	139	struct list_head sc_rq_dto_q;
	140	spinlock_t sc_rq_dto_lock;
	141	struct ib_qp *sc_qp;
	142	struct ib_cq *sc_rq_cq;
	143	struct ib_cq *sc_sq_cq;
	144	struct ib_mr sc_phys_mr; / MR for server memory */
	145
	146	spinlock_t sc_lock; /* transport lock */
	147
	148	wait_queue_head_t sc_send_wait; /* SQ exhaustion waitlist */
	149	unsigned long sc_flags;
	150	struct list_head sc_dto_q; /* DTO tasklet I/O pending Q */
	151	struct list_head sc_read_complete_q;
	152	spinlock_t sc_read_complete_lock;
8da91ea8	153	struct work_struct sc_work;
d21b05f1 TT	154	};
	155	/* sc_flags */
	156	#define RDMAXPRT_RQ_PENDING 1
	157	#define RDMAXPRT_SQ_PENDING 2
	158	#define RDMAXPRT_CONN_PENDING 3
	159
	160	#define RPCRDMA_LISTEN_BACKLOG 10
	161	/* The default ORD value is based on two outstanding full-size writes with a
	162	* page size of 4k, or 32k * 2 ops / 4k = 16 outstanding RDMA_READ. */
	163	#define RPCRDMA_ORD (64/4)
	164	#define RPCRDMA_SQ_DEPTH_MULT 8
	165	#define RPCRDMA_MAX_THREADS 16
	166	#define RPCRDMA_MAX_REQUESTS 16
	167	#define RPCRDMA_MAX_REQ_SIZE 4096
	168
	169	/* svc_rdma_marshal.c */
	170	extern void svc_rdma_rcl_chunk_counts(struct rpcrdma_read_chunk *,
	171	int , int );
	172	extern int svc_rdma_xdr_decode_req(struct rpcrdma_msg *, struct svc_rqst );
	173	extern int svc_rdma_xdr_decode_deferred_req(struct svc_rqst *);
	174	extern int svc_rdma_xdr_encode_error(struct svcxprt_rdma *,
	175	struct rpcrdma_msg *,
	176	enum rpcrdma_errcode, u32 *);
	177	extern void svc_rdma_xdr_encode_write_list(struct rpcrdma_msg *, int);
	178	extern void svc_rdma_xdr_encode_reply_array(struct rpcrdma_write_array *, int);
	179	extern void svc_rdma_xdr_encode_array_chunk(struct rpcrdma_write_array *, int,
	180	u32, u64, u32);
	181	extern void svc_rdma_xdr_encode_reply_header(struct svcxprt_rdma *,
	182	struct rpcrdma_msg *,
	183	struct rpcrdma_msg *,
	184	enum rpcrdma_proc);
	185	extern int svc_rdma_xdr_get_reply_hdr_len(struct rpcrdma_msg *);
	186
	187	/* svc_rdma_recvfrom.c */
	188	extern int svc_rdma_recvfrom(struct svc_rqst *);
	189
	190	/* svc_rdma_sendto.c */
	191	extern int svc_rdma_sendto(struct svc_rqst *);
	192
	193	/* svc_rdma_transport.c */
	194	extern int svc_rdma_send(struct svcxprt_rdma , struct ib_send_wr );
008fdbc5 TT	195	extern void svc_rdma_send_error(struct svcxprt_rdma , struct rpcrdma_msg ,
008fdbc5 TT	196	enum rpcrdma_errcode);
d21b05f1 TT	197	struct page *svc_rdma_get_page(void);
	198	extern int svc_rdma_post_recv(struct svcxprt_rdma *);
	199	extern int svc_rdma_create_listen(struct svc_serv , int, struct sockaddr );
	200	extern struct svc_rdma_op_ctxt svc_rdma_get_context(struct svcxprt_rdma );
	201	extern void svc_rdma_put_context(struct svc_rdma_op_ctxt *, int);
ab96dddb TT	202	extern struct svc_rdma_req_map *svc_rdma_get_req_map(void);
ab96dddb TT	203	extern void svc_rdma_put_req_map(struct svc_rdma_req_map *);
d21b05f1 TT	204	extern void svc_sq_reap(struct svcxprt_rdma *);
	205	extern void svc_rq_reap(struct svcxprt_rdma *);
	206	extern struct svc_xprt_class svc_rdma_class;
	207	extern void svc_rdma_prep_reply_hdr(struct svc_rqst *);
	208
	209	/* svc_rdma.c */
	210	extern int svc_rdma_init(void);
	211	extern void svc_rdma_cleanup(void);
	212
	213	/*
	214	* Returns the address of the first read chunk or <nul> if no read chunk is
	215	* present
	216	*/
	217	static inline struct rpcrdma_read_chunk *
	218	svc_rdma_get_read_chunk(struct rpcrdma_msg *rmsgp)
	219	{
	220	struct rpcrdma_read_chunk *ch =
	221	(struct rpcrdma_read_chunk *)&rmsgp->rm_body.rm_chunks[0];
	222
	223	if (ch->rc_discrim == 0)
	224	return NULL;
	225
	226	return ch;
	227	}
	228
	229	/*
	230	* Returns the address of the first read write array element or <nul> if no
	231	* write array list is present
	232	*/
	233	static inline struct rpcrdma_write_array *
	234	svc_rdma_get_write_array(struct rpcrdma_msg *rmsgp)
	235	{
	236	if (rmsgp->rm_body.rm_chunks[0] != 0
	237	\|\| rmsgp->rm_body.rm_chunks[1] == 0)
	238	return NULL;
	239
	240	return (struct rpcrdma_write_array *)&rmsgp->rm_body.rm_chunks[1];
	241	}
	242
	243	/*
	244	* Returns the address of the first reply array element or <nul> if no
	245	* reply array is present
	246	*/
	247	static inline struct rpcrdma_write_array *
	248	svc_rdma_get_reply_array(struct rpcrdma_msg *rmsgp)
	249	{
	250	struct rpcrdma_read_chunk *rch;
	251	struct rpcrdma_write_array *wr_ary;
	252	struct rpcrdma_write_array *rp_ary;
	253
	254	/* XXX: Need to fix when reply list may occur with read-list and/or
	255	* write list */
	256	if (rmsgp->rm_body.rm_chunks[0] != 0 \|\|
	257	rmsgp->rm_body.rm_chunks[1] != 0)
	258	return NULL;
	259
	260	rch = svc_rdma_get_read_chunk(rmsgp);
	261	if (rch) {
	262	while (rch->rc_discrim)
	263	rch++;
	264
	265	/* The reply list follows an empty write array located
	266	* at 'rc_position' here. The reply array is at rc_target.
	267	*/
268	rp_ary = (struct rpcrdma_write_array *)&rch->rc_target;
269
270	goto found_it;
271	}
272
273	wr_ary = svc_rdma_get_write_array(rmsgp);
274	if (wr_ary) {
275	rp_ary = (struct rpcrdma_write_array *)
276	&wr_ary->
277	wc_array[wr_ary->wc_nchunks].wc_target.rs_length;
278
279	goto found_it;
280	}
281
282	/* No read list, no write list */
283	rp_ary = (struct rpcrdma_write_array *)
284	&rmsgp->rm_body.rm_chunks[2];
285
286	found_it:
287	if (rp_ary->wc_discrim == 0)
288	return NULL;
289
290	return rp_ary;
291	}
292	#endif