xref: /openbmc/linux/net/sunrpc/xprtrdma/xprt_rdma.h (revision 4f89e4b8)
1 /* SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause */
2 /*
3  * Copyright (c) 2014-2017 Oracle.  All rights reserved.
4  * Copyright (c) 2003-2007 Network Appliance, Inc. All rights reserved.
5  *
6  * This software is available to you under a choice of one of two
7  * licenses.  You may choose to be licensed under the terms of the GNU
8  * General Public License (GPL) Version 2, available from the file
9  * COPYING in the main directory of this source tree, or the BSD-type
10  * license below:
11  *
12  * Redistribution and use in source and binary forms, with or without
13  * modification, are permitted provided that the following conditions
14  * are met:
15  *
16  *      Redistributions of source code must retain the above copyright
17  *      notice, this list of conditions and the following disclaimer.
18  *
19  *      Redistributions in binary form must reproduce the above
20  *      copyright notice, this list of conditions and the following
21  *      disclaimer in the documentation and/or other materials provided
22  *      with the distribution.
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25  *      its contributors may be used to endorse or promote products
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29  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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31  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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33  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
34  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
35  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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39  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
40  */
41 
42 #ifndef _LINUX_SUNRPC_XPRT_RDMA_H
43 #define _LINUX_SUNRPC_XPRT_RDMA_H
44 
45 #include <linux/wait.h> 		/* wait_queue_head_t, etc */
46 #include <linux/spinlock.h> 		/* spinlock_t, etc */
47 #include <linux/atomic.h>		/* atomic_t, etc */
48 #include <linux/kref.h>			/* struct kref */
49 #include <linux/workqueue.h>		/* struct work_struct */
50 
51 #include <rdma/rdma_cm.h>		/* RDMA connection api */
52 #include <rdma/ib_verbs.h>		/* RDMA verbs api */
53 
54 #include <linux/sunrpc/clnt.h> 		/* rpc_xprt */
55 #include <linux/sunrpc/rpc_rdma.h> 	/* RPC/RDMA protocol */
56 #include <linux/sunrpc/xprtrdma.h> 	/* xprt parameters */
57 
58 #define RDMA_RESOLVE_TIMEOUT	(5000)	/* 5 seconds */
59 #define RDMA_CONNECT_RETRY_MAX	(2)	/* retries if no listener backlog */
60 
61 #define RPCRDMA_BIND_TO		(60U * HZ)
62 #define RPCRDMA_INIT_REEST_TO	(5U * HZ)
63 #define RPCRDMA_MAX_REEST_TO	(30U * HZ)
64 #define RPCRDMA_IDLE_DISC_TO	(5U * 60 * HZ)
65 
66 /*
67  * Interface Adapter -- one per transport instance
68  */
69 struct rpcrdma_ia {
70 	struct rdma_cm_id 	*ri_id;
71 	struct ib_pd		*ri_pd;
72 	int			ri_async_rc;
73 	unsigned int		ri_max_segs;
74 	unsigned int		ri_max_frwr_depth;
75 	unsigned int		ri_max_send_sges;
76 	bool			ri_implicit_roundup;
77 	enum ib_mr_type		ri_mrtype;
78 	unsigned long		ri_flags;
79 	struct completion	ri_done;
80 	struct completion	ri_remove_done;
81 };
82 
83 enum {
84 	RPCRDMA_IAF_REMOVING = 0,
85 };
86 
87 /*
88  * RDMA Endpoint -- one per transport instance
89  */
90 
91 struct rpcrdma_ep {
92 	unsigned int		rep_send_count;
93 	unsigned int		rep_send_batch;
94 	unsigned int		rep_max_inline_send;
95 	unsigned int		rep_max_inline_recv;
96 	int			rep_connected;
97 	struct ib_qp_init_attr	rep_attr;
98 	wait_queue_head_t 	rep_connect_wait;
99 	struct rpcrdma_connect_private	rep_cm_private;
100 	struct rdma_conn_param	rep_remote_cma;
101 	unsigned int		rep_max_requests;	/* set by /proc */
102 	unsigned int		rep_inline_send;	/* negotiated */
103 	unsigned int		rep_inline_recv;	/* negotiated */
104 	int			rep_receive_count;
105 };
106 
107 /* Pre-allocate extra Work Requests for handling backward receives
108  * and sends. This is a fixed value because the Work Queues are
109  * allocated when the forward channel is set up, long before the
110  * backchannel is provisioned. This value is two times
111  * NFS4_DEF_CB_SLOT_TABLE_SIZE.
112  */
113 #if defined(CONFIG_SUNRPC_BACKCHANNEL)
114 #define RPCRDMA_BACKWARD_WRS (32)
115 #else
116 #define RPCRDMA_BACKWARD_WRS (0)
117 #endif
118 
119 /* Registered buffer -- registered kmalloc'd memory for RDMA SEND/RECV
120  *
121  * The below structure appears at the front of a large region of kmalloc'd
122  * memory, which always starts on a good alignment boundary.
123  */
124 
125 struct rpcrdma_regbuf {
126 	struct ib_sge		rg_iov;
127 	struct ib_device	*rg_device;
128 	enum dma_data_direction	rg_direction;
129 	void			*rg_data;
130 };
131 
132 static inline u64 rdmab_addr(struct rpcrdma_regbuf *rb)
133 {
134 	return rb->rg_iov.addr;
135 }
136 
137 static inline u32 rdmab_length(struct rpcrdma_regbuf *rb)
138 {
139 	return rb->rg_iov.length;
140 }
141 
142 static inline u32 rdmab_lkey(struct rpcrdma_regbuf *rb)
143 {
144 	return rb->rg_iov.lkey;
145 }
146 
147 static inline struct ib_device *rdmab_device(struct rpcrdma_regbuf *rb)
148 {
149 	return rb->rg_device;
150 }
151 
152 static inline void *rdmab_data(const struct rpcrdma_regbuf *rb)
153 {
154 	return rb->rg_data;
155 }
156 
157 #define RPCRDMA_DEF_GFP		(GFP_NOIO | __GFP_NOWARN)
158 
159 /* To ensure a transport can always make forward progress,
160  * the number of RDMA segments allowed in header chunk lists
161  * is capped at 8. This prevents less-capable devices and
162  * memory registrations from overrunning the Send buffer
163  * while building chunk lists.
164  *
165  * Elements of the Read list take up more room than the
166  * Write list or Reply chunk. 8 read segments means the Read
167  * list (or Write list or Reply chunk) cannot consume more
168  * than
169  *
170  * ((8 + 2) * read segment size) + 1 XDR words, or 244 bytes.
171  *
172  * And the fixed part of the header is another 24 bytes.
173  *
174  * The smallest inline threshold is 1024 bytes, ensuring that
175  * at least 750 bytes are available for RPC messages.
176  */
177 enum {
178 	RPCRDMA_MAX_HDR_SEGS = 8,
179 	RPCRDMA_HDRBUF_SIZE = 256,
180 };
181 
182 /*
183  * struct rpcrdma_rep -- this structure encapsulates state required
184  * to receive and complete an RPC Reply, asychronously. It needs
185  * several pieces of state:
186  *
187  *   o receive buffer and ib_sge (donated to provider)
188  *   o status of receive (success or not, length, inv rkey)
189  *   o bookkeeping state to get run by reply handler (XDR stream)
190  *
191  * These structures are allocated during transport initialization.
192  * N of these are associated with a transport instance, managed by
193  * struct rpcrdma_buffer. N is the max number of outstanding RPCs.
194  */
195 
196 struct rpcrdma_rep {
197 	struct ib_cqe		rr_cqe;
198 	__be32			rr_xid;
199 	__be32			rr_vers;
200 	__be32			rr_proc;
201 	int			rr_wc_flags;
202 	u32			rr_inv_rkey;
203 	bool			rr_temp;
204 	struct rpcrdma_regbuf	*rr_rdmabuf;
205 	struct rpcrdma_xprt	*rr_rxprt;
206 	struct rpc_rqst		*rr_rqst;
207 	struct xdr_buf		rr_hdrbuf;
208 	struct xdr_stream	rr_stream;
209 	struct list_head	rr_list;
210 	struct ib_recv_wr	rr_recv_wr;
211 };
212 
213 /* To reduce the rate at which a transport invokes ib_post_recv
214  * (and thus the hardware doorbell rate), xprtrdma posts Receive
215  * WRs in batches.
216  *
217  * Setting this to zero disables Receive post batching.
218  */
219 enum {
220 	RPCRDMA_MAX_RECV_BATCH = 7,
221 };
222 
223 /* struct rpcrdma_sendctx - DMA mapped SGEs to unmap after Send completes
224  */
225 struct rpcrdma_req;
226 struct rpcrdma_xprt;
227 struct rpcrdma_sendctx {
228 	struct ib_send_wr	sc_wr;
229 	struct ib_cqe		sc_cqe;
230 	struct ib_device	*sc_device;
231 	struct rpcrdma_xprt	*sc_xprt;
232 	struct rpcrdma_req	*sc_req;
233 	unsigned int		sc_unmap_count;
234 	struct ib_sge		sc_sges[];
235 };
236 
237 /*
238  * struct rpcrdma_mr - external memory region metadata
239  *
240  * An external memory region is any buffer or page that is registered
241  * on the fly (ie, not pre-registered).
242  */
243 struct rpcrdma_req;
244 struct rpcrdma_frwr {
245 	struct ib_mr			*fr_mr;
246 	struct ib_cqe			fr_cqe;
247 	struct completion		fr_linv_done;
248 	struct rpcrdma_req		*fr_req;
249 	union {
250 		struct ib_reg_wr	fr_regwr;
251 		struct ib_send_wr	fr_invwr;
252 	};
253 };
254 
255 struct rpcrdma_mr {
256 	struct list_head	mr_list;
257 	struct scatterlist	*mr_sg;
258 	int			mr_nents;
259 	enum dma_data_direction	mr_dir;
260 	struct rpcrdma_frwr	frwr;
261 	struct rpcrdma_xprt	*mr_xprt;
262 	u32			mr_handle;
263 	u32			mr_length;
264 	u64			mr_offset;
265 	struct work_struct	mr_recycle;
266 	struct list_head	mr_all;
267 };
268 
269 /*
270  * struct rpcrdma_req -- structure central to the request/reply sequence.
271  *
272  * N of these are associated with a transport instance, and stored in
273  * struct rpcrdma_buffer. N is the max number of outstanding requests.
274  *
275  * It includes pre-registered buffer memory for send AND recv.
276  * The recv buffer, however, is not owned by this structure, and
277  * is "donated" to the hardware when a recv is posted. When a
278  * reply is handled, the recv buffer used is given back to the
279  * struct rpcrdma_req associated with the request.
280  *
281  * In addition to the basic memory, this structure includes an array
282  * of iovs for send operations. The reason is that the iovs passed to
283  * ib_post_{send,recv} must not be modified until the work request
284  * completes.
285  */
286 
287 /* Maximum number of page-sized "segments" per chunk list to be
288  * registered or invalidated. Must handle a Reply chunk:
289  */
290 enum {
291 	RPCRDMA_MAX_IOV_SEGS	= 3,
292 	RPCRDMA_MAX_DATA_SEGS	= ((1 * 1024 * 1024) / PAGE_SIZE) + 1,
293 	RPCRDMA_MAX_SEGS	= RPCRDMA_MAX_DATA_SEGS +
294 				  RPCRDMA_MAX_IOV_SEGS,
295 };
296 
297 struct rpcrdma_mr_seg {		/* chunk descriptors */
298 	u32		mr_len;		/* length of chunk or segment */
299 	struct page	*mr_page;	/* owning page, if any */
300 	char		*mr_offset;	/* kva if no page, else offset */
301 };
302 
303 /* The Send SGE array is provisioned to send a maximum size
304  * inline request:
305  * - RPC-over-RDMA header
306  * - xdr_buf head iovec
307  * - RPCRDMA_MAX_INLINE bytes, in pages
308  * - xdr_buf tail iovec
309  *
310  * The actual number of array elements consumed by each RPC
311  * depends on the device's max_sge limit.
312  */
313 enum {
314 	RPCRDMA_MIN_SEND_SGES = 3,
315 	RPCRDMA_MAX_PAGE_SGES = RPCRDMA_MAX_INLINE >> PAGE_SHIFT,
316 	RPCRDMA_MAX_SEND_SGES = 1 + 1 + RPCRDMA_MAX_PAGE_SGES + 1,
317 };
318 
319 struct rpcrdma_buffer;
320 struct rpcrdma_req {
321 	struct list_head	rl_list;
322 	struct rpc_rqst		rl_slot;
323 	struct rpcrdma_rep	*rl_reply;
324 	struct xdr_stream	rl_stream;
325 	struct xdr_buf		rl_hdrbuf;
326 	struct rpcrdma_sendctx	*rl_sendctx;
327 	struct rpcrdma_regbuf	*rl_rdmabuf;	/* xprt header */
328 	struct rpcrdma_regbuf	*rl_sendbuf;	/* rq_snd_buf */
329 	struct rpcrdma_regbuf	*rl_recvbuf;	/* rq_rcv_buf */
330 
331 	struct list_head	rl_all;
332 	struct kref		rl_kref;
333 
334 	struct list_head	rl_registered;	/* registered segments */
335 	struct rpcrdma_mr_seg	rl_segments[RPCRDMA_MAX_SEGS];
336 };
337 
338 static inline struct rpcrdma_req *
339 rpcr_to_rdmar(const struct rpc_rqst *rqst)
340 {
341 	return container_of(rqst, struct rpcrdma_req, rl_slot);
342 }
343 
344 static inline void
345 rpcrdma_mr_push(struct rpcrdma_mr *mr, struct list_head *list)
346 {
347 	list_add_tail(&mr->mr_list, list);
348 }
349 
350 static inline struct rpcrdma_mr *
351 rpcrdma_mr_pop(struct list_head *list)
352 {
353 	struct rpcrdma_mr *mr;
354 
355 	mr = list_first_entry(list, struct rpcrdma_mr, mr_list);
356 	list_del_init(&mr->mr_list);
357 	return mr;
358 }
359 
360 /*
361  * struct rpcrdma_buffer -- holds list/queue of pre-registered memory for
362  * inline requests/replies, and client/server credits.
363  *
364  * One of these is associated with a transport instance
365  */
366 struct rpcrdma_buffer {
367 	spinlock_t		rb_mrlock;	/* protect rb_mrs list */
368 	struct list_head	rb_mrs;
369 	struct list_head	rb_all;
370 
371 	unsigned long		rb_sc_head;
372 	unsigned long		rb_sc_tail;
373 	unsigned long		rb_sc_last;
374 	struct rpcrdma_sendctx	**rb_sc_ctxs;
375 
376 	spinlock_t		rb_lock;	/* protect buf lists */
377 	struct list_head	rb_send_bufs;
378 	struct list_head	rb_recv_bufs;
379 	struct list_head	rb_allreqs;
380 
381 	u32			rb_max_requests;
382 	u32			rb_credits;	/* most recent credit grant */
383 
384 	u32			rb_bc_srv_max_requests;
385 	u32			rb_bc_max_requests;
386 
387 	struct delayed_work	rb_refresh_worker;
388 };
389 
390 /*
391  * Statistics for RPCRDMA
392  */
393 struct rpcrdma_stats {
394 	/* accessed when sending a call */
395 	unsigned long		read_chunk_count;
396 	unsigned long		write_chunk_count;
397 	unsigned long		reply_chunk_count;
398 	unsigned long long	total_rdma_request;
399 
400 	/* rarely accessed error counters */
401 	unsigned long long	pullup_copy_count;
402 	unsigned long		hardway_register_count;
403 	unsigned long		failed_marshal_count;
404 	unsigned long		bad_reply_count;
405 	unsigned long		mrs_recycled;
406 	unsigned long		mrs_orphaned;
407 	unsigned long		mrs_allocated;
408 	unsigned long		empty_sendctx_q;
409 
410 	/* accessed when receiving a reply */
411 	unsigned long long	total_rdma_reply;
412 	unsigned long long	fixup_copy_count;
413 	unsigned long		reply_waits_for_send;
414 	unsigned long		local_inv_needed;
415 	unsigned long		nomsg_call_count;
416 	unsigned long		bcall_count;
417 };
418 
419 /*
420  * RPCRDMA transport -- encapsulates the structures above for
421  * integration with RPC.
422  *
423  * The contained structures are embedded, not pointers,
424  * for convenience. This structure need not be visible externally.
425  *
426  * It is allocated and initialized during mount, and released
427  * during unmount.
428  */
429 struct rpcrdma_xprt {
430 	struct rpc_xprt		rx_xprt;
431 	struct rpcrdma_ia	rx_ia;
432 	struct rpcrdma_ep	rx_ep;
433 	struct rpcrdma_buffer	rx_buf;
434 	struct delayed_work	rx_connect_worker;
435 	struct rpc_timeout	rx_timeout;
436 	struct rpcrdma_stats	rx_stats;
437 };
438 
439 #define rpcx_to_rdmax(x) container_of(x, struct rpcrdma_xprt, rx_xprt)
440 
441 static inline const char *
442 rpcrdma_addrstr(const struct rpcrdma_xprt *r_xprt)
443 {
444 	return r_xprt->rx_xprt.address_strings[RPC_DISPLAY_ADDR];
445 }
446 
447 static inline const char *
448 rpcrdma_portstr(const struct rpcrdma_xprt *r_xprt)
449 {
450 	return r_xprt->rx_xprt.address_strings[RPC_DISPLAY_PORT];
451 }
452 
453 /* Setting this to 0 ensures interoperability with early servers.
454  * Setting this to 1 enhances certain unaligned read/write performance.
455  * Default is 0, see sysctl entry and rpc_rdma.c rpcrdma_convert_iovs() */
456 extern int xprt_rdma_pad_optimize;
457 
458 /* This setting controls the hunt for a supported memory
459  * registration strategy.
460  */
461 extern unsigned int xprt_rdma_memreg_strategy;
462 
463 /*
464  * Interface Adapter calls - xprtrdma/verbs.c
465  */
466 int rpcrdma_ia_open(struct rpcrdma_xprt *xprt);
467 void rpcrdma_ia_remove(struct rpcrdma_ia *ia);
468 void rpcrdma_ia_close(struct rpcrdma_ia *);
469 
470 /*
471  * Endpoint calls - xprtrdma/verbs.c
472  */
473 int rpcrdma_ep_create(struct rpcrdma_xprt *r_xprt);
474 void rpcrdma_ep_destroy(struct rpcrdma_xprt *r_xprt);
475 int rpcrdma_ep_connect(struct rpcrdma_ep *, struct rpcrdma_ia *);
476 void rpcrdma_ep_disconnect(struct rpcrdma_ep *, struct rpcrdma_ia *);
477 
478 int rpcrdma_ep_post(struct rpcrdma_ia *, struct rpcrdma_ep *,
479 				struct rpcrdma_req *);
480 
481 /*
482  * Buffer calls - xprtrdma/verbs.c
483  */
484 struct rpcrdma_req *rpcrdma_req_create(struct rpcrdma_xprt *r_xprt, size_t size,
485 				       gfp_t flags);
486 void rpcrdma_req_destroy(struct rpcrdma_req *req);
487 int rpcrdma_buffer_create(struct rpcrdma_xprt *);
488 void rpcrdma_buffer_destroy(struct rpcrdma_buffer *);
489 struct rpcrdma_sendctx *rpcrdma_sendctx_get_locked(struct rpcrdma_xprt *r_xprt);
490 
491 struct rpcrdma_mr *rpcrdma_mr_get(struct rpcrdma_xprt *r_xprt);
492 void rpcrdma_mr_put(struct rpcrdma_mr *mr);
493 void rpcrdma_mr_unmap_and_put(struct rpcrdma_mr *mr);
494 
495 static inline void
496 rpcrdma_mr_recycle(struct rpcrdma_mr *mr)
497 {
498 	schedule_work(&mr->mr_recycle);
499 }
500 
501 struct rpcrdma_req *rpcrdma_buffer_get(struct rpcrdma_buffer *);
502 void rpcrdma_buffer_put(struct rpcrdma_buffer *buffers,
503 			struct rpcrdma_req *req);
504 void rpcrdma_recv_buffer_put(struct rpcrdma_rep *);
505 
506 bool rpcrdma_regbuf_realloc(struct rpcrdma_regbuf *rb, size_t size,
507 			    gfp_t flags);
508 bool __rpcrdma_regbuf_dma_map(struct rpcrdma_xprt *r_xprt,
509 			      struct rpcrdma_regbuf *rb);
510 
511 /**
512  * rpcrdma_regbuf_is_mapped - check if buffer is DMA mapped
513  *
514  * Returns true if the buffer is now mapped to rb->rg_device.
515  */
516 static inline bool rpcrdma_regbuf_is_mapped(struct rpcrdma_regbuf *rb)
517 {
518 	return rb->rg_device != NULL;
519 }
520 
521 /**
522  * rpcrdma_regbuf_dma_map - DMA-map a regbuf
523  * @r_xprt: controlling transport instance
524  * @rb: regbuf to be mapped
525  *
526  * Returns true if the buffer is currently DMA mapped.
527  */
528 static inline bool rpcrdma_regbuf_dma_map(struct rpcrdma_xprt *r_xprt,
529 					  struct rpcrdma_regbuf *rb)
530 {
531 	if (likely(rpcrdma_regbuf_is_mapped(rb)))
532 		return true;
533 	return __rpcrdma_regbuf_dma_map(r_xprt, rb);
534 }
535 
536 /*
537  * Wrappers for chunk registration, shared by read/write chunk code.
538  */
539 
540 static inline enum dma_data_direction
541 rpcrdma_data_dir(bool writing)
542 {
543 	return writing ? DMA_FROM_DEVICE : DMA_TO_DEVICE;
544 }
545 
546 /* Memory registration calls xprtrdma/frwr_ops.c
547  */
548 bool frwr_is_supported(struct ib_device *device);
549 void frwr_reset(struct rpcrdma_req *req);
550 int frwr_open(struct rpcrdma_ia *ia, struct rpcrdma_ep *ep);
551 int frwr_init_mr(struct rpcrdma_ia *ia, struct rpcrdma_mr *mr);
552 void frwr_release_mr(struct rpcrdma_mr *mr);
553 size_t frwr_maxpages(struct rpcrdma_xprt *r_xprt);
554 struct rpcrdma_mr_seg *frwr_map(struct rpcrdma_xprt *r_xprt,
555 				struct rpcrdma_mr_seg *seg,
556 				int nsegs, bool writing, __be32 xid,
557 				struct rpcrdma_mr **mr);
558 int frwr_send(struct rpcrdma_ia *ia, struct rpcrdma_req *req);
559 void frwr_reminv(struct rpcrdma_rep *rep, struct list_head *mrs);
560 void frwr_unmap_sync(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req);
561 void frwr_unmap_async(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req);
562 
563 /*
564  * RPC/RDMA protocol calls - xprtrdma/rpc_rdma.c
565  */
566 
567 enum rpcrdma_chunktype {
568 	rpcrdma_noch = 0,
569 	rpcrdma_readch,
570 	rpcrdma_areadch,
571 	rpcrdma_writech,
572 	rpcrdma_replych
573 };
574 
575 int rpcrdma_prepare_send_sges(struct rpcrdma_xprt *r_xprt,
576 			      struct rpcrdma_req *req, u32 hdrlen,
577 			      struct xdr_buf *xdr,
578 			      enum rpcrdma_chunktype rtype);
579 void rpcrdma_sendctx_unmap(struct rpcrdma_sendctx *sc);
580 int rpcrdma_marshal_req(struct rpcrdma_xprt *r_xprt, struct rpc_rqst *rqst);
581 void rpcrdma_set_max_header_sizes(struct rpcrdma_xprt *);
582 void rpcrdma_complete_rqst(struct rpcrdma_rep *rep);
583 void rpcrdma_reply_handler(struct rpcrdma_rep *rep);
584 
585 static inline void rpcrdma_set_xdrlen(struct xdr_buf *xdr, size_t len)
586 {
587 	xdr->head[0].iov_len = len;
588 	xdr->len = len;
589 }
590 
591 /* RPC/RDMA module init - xprtrdma/transport.c
592  */
593 extern unsigned int xprt_rdma_slot_table_entries;
594 extern unsigned int xprt_rdma_max_inline_read;
595 extern unsigned int xprt_rdma_max_inline_write;
596 void xprt_rdma_format_addresses(struct rpc_xprt *xprt, struct sockaddr *sap);
597 void xprt_rdma_free_addresses(struct rpc_xprt *xprt);
598 void xprt_rdma_close(struct rpc_xprt *xprt);
599 void xprt_rdma_print_stats(struct rpc_xprt *xprt, struct seq_file *seq);
600 int xprt_rdma_init(void);
601 void xprt_rdma_cleanup(void);
602 
603 /* Backchannel calls - xprtrdma/backchannel.c
604  */
605 #if defined(CONFIG_SUNRPC_BACKCHANNEL)
606 int xprt_rdma_bc_setup(struct rpc_xprt *, unsigned int);
607 size_t xprt_rdma_bc_maxpayload(struct rpc_xprt *);
608 unsigned int xprt_rdma_bc_max_slots(struct rpc_xprt *);
609 int rpcrdma_bc_post_recv(struct rpcrdma_xprt *, unsigned int);
610 void rpcrdma_bc_receive_call(struct rpcrdma_xprt *, struct rpcrdma_rep *);
611 int xprt_rdma_bc_send_reply(struct rpc_rqst *rqst);
612 void xprt_rdma_bc_free_rqst(struct rpc_rqst *);
613 void xprt_rdma_bc_destroy(struct rpc_xprt *, unsigned int);
614 #endif	/* CONFIG_SUNRPC_BACKCHANNEL */
615 
616 extern struct xprt_class xprt_rdma_bc;
617 
618 #endif				/* _LINUX_SUNRPC_XPRT_RDMA_H */
619