xprt_rdma.h (18704B)
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. 23 * 24 * Neither the name of the Network Appliance, Inc. nor the names of 25 * its contributors may be used to endorse or promote products 26 * derived from this software without specific prior written 27 * permission. 28 * 29 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 30 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 31 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 32 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 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, 36 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 37 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 38 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 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#include <linux/llist.h> 51 52#include <rdma/rdma_cm.h> /* RDMA connection api */ 53#include <rdma/ib_verbs.h> /* RDMA verbs api */ 54 55#include <linux/sunrpc/clnt.h> /* rpc_xprt */ 56#include <linux/sunrpc/rpc_rdma_cid.h> /* completion IDs */ 57#include <linux/sunrpc/rpc_rdma.h> /* RPC/RDMA protocol */ 58#include <linux/sunrpc/xprtrdma.h> /* xprt parameters */ 59 60#define RDMA_RESOLVE_TIMEOUT (5000) /* 5 seconds */ 61#define RDMA_CONNECT_RETRY_MAX (2) /* retries if no listener backlog */ 62 63#define RPCRDMA_BIND_TO (60U * HZ) 64#define RPCRDMA_INIT_REEST_TO (5U * HZ) 65#define RPCRDMA_MAX_REEST_TO (30U * HZ) 66#define RPCRDMA_IDLE_DISC_TO (5U * 60 * HZ) 67 68/* 69 * RDMA Endpoint -- connection endpoint details 70 */ 71struct rpcrdma_mr; 72struct rpcrdma_ep { 73 struct kref re_kref; 74 struct rdma_cm_id *re_id; 75 struct ib_pd *re_pd; 76 unsigned int re_max_rdma_segs; 77 unsigned int re_max_fr_depth; 78 struct rpcrdma_mr *re_write_pad_mr; 79 enum ib_mr_type re_mrtype; 80 struct completion re_done; 81 unsigned int re_send_count; 82 unsigned int re_send_batch; 83 unsigned int re_max_inline_send; 84 unsigned int re_max_inline_recv; 85 int re_async_rc; 86 int re_connect_status; 87 atomic_t re_receiving; 88 atomic_t re_force_disconnect; 89 struct ib_qp_init_attr re_attr; 90 wait_queue_head_t re_connect_wait; 91 struct rpc_xprt *re_xprt; 92 struct rpcrdma_connect_private 93 re_cm_private; 94 struct rdma_conn_param re_remote_cma; 95 int re_receive_count; 96 unsigned int re_max_requests; /* depends on device */ 97 unsigned int re_inline_send; /* negotiated */ 98 unsigned int re_inline_recv; /* negotiated */ 99 100 atomic_t re_completion_ids; 101 102 char re_write_pad[XDR_UNIT]; 103}; 104 105/* Pre-allocate extra Work Requests for handling reverse-direction 106 * Receives and Sends. This is a fixed value because the Work Queues 107 * are allocated when the forward channel is set up, long before the 108 * backchannel is provisioned. This value is two times 109 * NFS4_DEF_CB_SLOT_TABLE_SIZE. 110 */ 111#if defined(CONFIG_SUNRPC_BACKCHANNEL) 112#define RPCRDMA_BACKWARD_WRS (32) 113#else 114#define RPCRDMA_BACKWARD_WRS (0) 115#endif 116 117/* Registered buffer -- registered kmalloc'd memory for RDMA SEND/RECV 118 */ 119 120struct rpcrdma_regbuf { 121 struct ib_sge rg_iov; 122 struct ib_device *rg_device; 123 enum dma_data_direction rg_direction; 124 void *rg_data; 125}; 126 127static inline u64 rdmab_addr(struct rpcrdma_regbuf *rb) 128{ 129 return rb->rg_iov.addr; 130} 131 132static inline u32 rdmab_length(struct rpcrdma_regbuf *rb) 133{ 134 return rb->rg_iov.length; 135} 136 137static inline u32 rdmab_lkey(struct rpcrdma_regbuf *rb) 138{ 139 return rb->rg_iov.lkey; 140} 141 142static inline struct ib_device *rdmab_device(struct rpcrdma_regbuf *rb) 143{ 144 return rb->rg_device; 145} 146 147static inline void *rdmab_data(const struct rpcrdma_regbuf *rb) 148{ 149 return rb->rg_data; 150} 151 152#define RPCRDMA_DEF_GFP (GFP_NOIO | __GFP_NOWARN) 153 154/* To ensure a transport can always make forward progress, 155 * the number of RDMA segments allowed in header chunk lists 156 * is capped at 16. This prevents less-capable devices from 157 * overrunning the Send buffer while building chunk lists. 158 * 159 * Elements of the Read list take up more room than the 160 * Write list or Reply chunk. 16 read segments means the 161 * chunk lists cannot consume more than 162 * 163 * ((16 + 2) * read segment size) + 1 XDR words, 164 * 165 * or about 400 bytes. The fixed part of the header is 166 * another 24 bytes. Thus when the inline threshold is 167 * 1024 bytes, at least 600 bytes are available for RPC 168 * message bodies. 169 */ 170enum { 171 RPCRDMA_MAX_HDR_SEGS = 16, 172}; 173 174/* 175 * struct rpcrdma_rep -- this structure encapsulates state required 176 * to receive and complete an RPC Reply, asychronously. It needs 177 * several pieces of state: 178 * 179 * o receive buffer and ib_sge (donated to provider) 180 * o status of receive (success or not, length, inv rkey) 181 * o bookkeeping state to get run by reply handler (XDR stream) 182 * 183 * These structures are allocated during transport initialization. 184 * N of these are associated with a transport instance, managed by 185 * struct rpcrdma_buffer. N is the max number of outstanding RPCs. 186 */ 187 188struct rpcrdma_rep { 189 struct ib_cqe rr_cqe; 190 struct rpc_rdma_cid rr_cid; 191 192 __be32 rr_xid; 193 __be32 rr_vers; 194 __be32 rr_proc; 195 int rr_wc_flags; 196 u32 rr_inv_rkey; 197 bool rr_temp; 198 struct rpcrdma_regbuf *rr_rdmabuf; 199 struct rpcrdma_xprt *rr_rxprt; 200 struct rpc_rqst *rr_rqst; 201 struct xdr_buf rr_hdrbuf; 202 struct xdr_stream rr_stream; 203 struct llist_node rr_node; 204 struct ib_recv_wr rr_recv_wr; 205 struct list_head rr_all; 206}; 207 208/* To reduce the rate at which a transport invokes ib_post_recv 209 * (and thus the hardware doorbell rate), xprtrdma posts Receive 210 * WRs in batches. 211 * 212 * Setting this to zero disables Receive post batching. 213 */ 214enum { 215 RPCRDMA_MAX_RECV_BATCH = 7, 216}; 217 218/* struct rpcrdma_sendctx - DMA mapped SGEs to unmap after Send completes 219 */ 220struct rpcrdma_req; 221struct rpcrdma_sendctx { 222 struct ib_cqe sc_cqe; 223 struct rpc_rdma_cid sc_cid; 224 struct rpcrdma_req *sc_req; 225 unsigned int sc_unmap_count; 226 struct ib_sge sc_sges[]; 227}; 228 229/* 230 * struct rpcrdma_mr - external memory region metadata 231 * 232 * An external memory region is any buffer or page that is registered 233 * on the fly (ie, not pre-registered). 234 */ 235struct rpcrdma_req; 236struct rpcrdma_mr { 237 struct list_head mr_list; 238 struct rpcrdma_req *mr_req; 239 240 struct ib_mr *mr_ibmr; 241 struct ib_device *mr_device; 242 struct scatterlist *mr_sg; 243 int mr_nents; 244 enum dma_data_direction mr_dir; 245 struct ib_cqe mr_cqe; 246 struct completion mr_linv_done; 247 union { 248 struct ib_reg_wr mr_regwr; 249 struct ib_send_wr mr_invwr; 250 }; 251 struct rpcrdma_xprt *mr_xprt; 252 u32 mr_handle; 253 u32 mr_length; 254 u64 mr_offset; 255 struct list_head mr_all; 256 struct rpc_rdma_cid mr_cid; 257}; 258 259/* 260 * struct rpcrdma_req -- structure central to the request/reply sequence. 261 * 262 * N of these are associated with a transport instance, and stored in 263 * struct rpcrdma_buffer. N is the max number of outstanding requests. 264 * 265 * It includes pre-registered buffer memory for send AND recv. 266 * The recv buffer, however, is not owned by this structure, and 267 * is "donated" to the hardware when a recv is posted. When a 268 * reply is handled, the recv buffer used is given back to the 269 * struct rpcrdma_req associated with the request. 270 * 271 * In addition to the basic memory, this structure includes an array 272 * of iovs for send operations. The reason is that the iovs passed to 273 * ib_post_{send,recv} must not be modified until the work request 274 * completes. 275 */ 276 277/* Maximum number of page-sized "segments" per chunk list to be 278 * registered or invalidated. Must handle a Reply chunk: 279 */ 280enum { 281 RPCRDMA_MAX_IOV_SEGS = 3, 282 RPCRDMA_MAX_DATA_SEGS = ((1 * 1024 * 1024) / PAGE_SIZE) + 1, 283 RPCRDMA_MAX_SEGS = RPCRDMA_MAX_DATA_SEGS + 284 RPCRDMA_MAX_IOV_SEGS, 285}; 286 287/* Arguments for DMA mapping and registration */ 288struct rpcrdma_mr_seg { 289 u32 mr_len; /* length of segment */ 290 struct page *mr_page; /* underlying struct page */ 291 u64 mr_offset; /* IN: page offset, OUT: iova */ 292}; 293 294/* The Send SGE array is provisioned to send a maximum size 295 * inline request: 296 * - RPC-over-RDMA header 297 * - xdr_buf head iovec 298 * - RPCRDMA_MAX_INLINE bytes, in pages 299 * - xdr_buf tail iovec 300 * 301 * The actual number of array elements consumed by each RPC 302 * depends on the device's max_sge limit. 303 */ 304enum { 305 RPCRDMA_MIN_SEND_SGES = 3, 306 RPCRDMA_MAX_PAGE_SGES = RPCRDMA_MAX_INLINE >> PAGE_SHIFT, 307 RPCRDMA_MAX_SEND_SGES = 1 + 1 + RPCRDMA_MAX_PAGE_SGES + 1, 308}; 309 310struct rpcrdma_buffer; 311struct rpcrdma_req { 312 struct list_head rl_list; 313 struct rpc_rqst rl_slot; 314 struct rpcrdma_rep *rl_reply; 315 struct xdr_stream rl_stream; 316 struct xdr_buf rl_hdrbuf; 317 struct ib_send_wr rl_wr; 318 struct rpcrdma_sendctx *rl_sendctx; 319 struct rpcrdma_regbuf *rl_rdmabuf; /* xprt header */ 320 struct rpcrdma_regbuf *rl_sendbuf; /* rq_snd_buf */ 321 struct rpcrdma_regbuf *rl_recvbuf; /* rq_rcv_buf */ 322 323 struct list_head rl_all; 324 struct kref rl_kref; 325 326 struct list_head rl_free_mrs; 327 struct list_head rl_registered; 328 struct rpcrdma_mr_seg rl_segments[RPCRDMA_MAX_SEGS]; 329}; 330 331static inline struct rpcrdma_req * 332rpcr_to_rdmar(const struct rpc_rqst *rqst) 333{ 334 return container_of(rqst, struct rpcrdma_req, rl_slot); 335} 336 337static inline void 338rpcrdma_mr_push(struct rpcrdma_mr *mr, struct list_head *list) 339{ 340 list_add(&mr->mr_list, list); 341} 342 343static inline struct rpcrdma_mr * 344rpcrdma_mr_pop(struct list_head *list) 345{ 346 struct rpcrdma_mr *mr; 347 348 mr = list_first_entry_or_null(list, struct rpcrdma_mr, mr_list); 349 if (mr) 350 list_del_init(&mr->mr_list); 351 return mr; 352} 353 354/* 355 * struct rpcrdma_buffer -- holds list/queue of pre-registered memory for 356 * inline requests/replies, and client/server credits. 357 * 358 * One of these is associated with a transport instance 359 */ 360struct rpcrdma_buffer { 361 spinlock_t rb_lock; 362 struct list_head rb_send_bufs; 363 struct list_head rb_mrs; 364 365 unsigned long rb_sc_head; 366 unsigned long rb_sc_tail; 367 unsigned long rb_sc_last; 368 struct rpcrdma_sendctx **rb_sc_ctxs; 369 370 struct list_head rb_allreqs; 371 struct list_head rb_all_mrs; 372 struct list_head rb_all_reps; 373 374 struct llist_head rb_free_reps; 375 376 __be32 rb_max_requests; 377 u32 rb_credits; /* most recent credit grant */ 378 379 u32 rb_bc_srv_max_requests; 380 u32 rb_bc_max_requests; 381 382 struct work_struct rb_refresh_worker; 383}; 384 385/* 386 * Statistics for RPCRDMA 387 */ 388struct rpcrdma_stats { 389 /* accessed when sending a call */ 390 unsigned long read_chunk_count; 391 unsigned long write_chunk_count; 392 unsigned long reply_chunk_count; 393 unsigned long long total_rdma_request; 394 395 /* rarely accessed error counters */ 396 unsigned long long pullup_copy_count; 397 unsigned long hardway_register_count; 398 unsigned long failed_marshal_count; 399 unsigned long bad_reply_count; 400 unsigned long mrs_recycled; 401 unsigned long mrs_orphaned; 402 unsigned long mrs_allocated; 403 unsigned long empty_sendctx_q; 404 405 /* accessed when receiving a reply */ 406 unsigned long long total_rdma_reply; 407 unsigned long long fixup_copy_count; 408 unsigned long reply_waits_for_send; 409 unsigned long local_inv_needed; 410 unsigned long nomsg_call_count; 411 unsigned long bcall_count; 412}; 413 414/* 415 * RPCRDMA transport -- encapsulates the structures above for 416 * integration with RPC. 417 * 418 * The contained structures are embedded, not pointers, 419 * for convenience. This structure need not be visible externally. 420 * 421 * It is allocated and initialized during mount, and released 422 * during unmount. 423 */ 424struct rpcrdma_xprt { 425 struct rpc_xprt rx_xprt; 426 struct rpcrdma_ep *rx_ep; 427 struct rpcrdma_buffer rx_buf; 428 struct delayed_work rx_connect_worker; 429 struct rpc_timeout rx_timeout; 430 struct rpcrdma_stats rx_stats; 431}; 432 433#define rpcx_to_rdmax(x) container_of(x, struct rpcrdma_xprt, rx_xprt) 434 435static inline const char * 436rpcrdma_addrstr(const struct rpcrdma_xprt *r_xprt) 437{ 438 return r_xprt->rx_xprt.address_strings[RPC_DISPLAY_ADDR]; 439} 440 441static inline const char * 442rpcrdma_portstr(const struct rpcrdma_xprt *r_xprt) 443{ 444 return r_xprt->rx_xprt.address_strings[RPC_DISPLAY_PORT]; 445} 446 447/* Setting this to 0 ensures interoperability with early servers. 448 * Setting this to 1 enhances certain unaligned read/write performance. 449 * Default is 0, see sysctl entry and rpc_rdma.c rpcrdma_convert_iovs() */ 450extern int xprt_rdma_pad_optimize; 451 452/* This setting controls the hunt for a supported memory 453 * registration strategy. 454 */ 455extern unsigned int xprt_rdma_memreg_strategy; 456 457/* 458 * Endpoint calls - xprtrdma/verbs.c 459 */ 460void rpcrdma_force_disconnect(struct rpcrdma_ep *ep); 461void rpcrdma_flush_disconnect(struct rpcrdma_xprt *r_xprt, struct ib_wc *wc); 462int rpcrdma_xprt_connect(struct rpcrdma_xprt *r_xprt); 463void rpcrdma_xprt_disconnect(struct rpcrdma_xprt *r_xprt); 464 465void rpcrdma_post_recvs(struct rpcrdma_xprt *r_xprt, int needed, bool temp); 466 467/* 468 * Buffer calls - xprtrdma/verbs.c 469 */ 470struct rpcrdma_req *rpcrdma_req_create(struct rpcrdma_xprt *r_xprt, size_t size, 471 gfp_t flags); 472int rpcrdma_req_setup(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req); 473void rpcrdma_req_destroy(struct rpcrdma_req *req); 474int rpcrdma_buffer_create(struct rpcrdma_xprt *); 475void rpcrdma_buffer_destroy(struct rpcrdma_buffer *); 476struct rpcrdma_sendctx *rpcrdma_sendctx_get_locked(struct rpcrdma_xprt *r_xprt); 477 478struct rpcrdma_mr *rpcrdma_mr_get(struct rpcrdma_xprt *r_xprt); 479void rpcrdma_mrs_refresh(struct rpcrdma_xprt *r_xprt); 480 481struct rpcrdma_req *rpcrdma_buffer_get(struct rpcrdma_buffer *); 482void rpcrdma_buffer_put(struct rpcrdma_buffer *buffers, 483 struct rpcrdma_req *req); 484void rpcrdma_rep_put(struct rpcrdma_buffer *buf, struct rpcrdma_rep *rep); 485void rpcrdma_reply_put(struct rpcrdma_buffer *buffers, struct rpcrdma_req *req); 486 487bool rpcrdma_regbuf_realloc(struct rpcrdma_regbuf *rb, size_t size, 488 gfp_t flags); 489bool __rpcrdma_regbuf_dma_map(struct rpcrdma_xprt *r_xprt, 490 struct rpcrdma_regbuf *rb); 491 492/** 493 * rpcrdma_regbuf_is_mapped - check if buffer is DMA mapped 494 * 495 * Returns true if the buffer is now mapped to rb->rg_device. 496 */ 497static inline bool rpcrdma_regbuf_is_mapped(struct rpcrdma_regbuf *rb) 498{ 499 return rb->rg_device != NULL; 500} 501 502/** 503 * rpcrdma_regbuf_dma_map - DMA-map a regbuf 504 * @r_xprt: controlling transport instance 505 * @rb: regbuf to be mapped 506 * 507 * Returns true if the buffer is currently DMA mapped. 508 */ 509static inline bool rpcrdma_regbuf_dma_map(struct rpcrdma_xprt *r_xprt, 510 struct rpcrdma_regbuf *rb) 511{ 512 if (likely(rpcrdma_regbuf_is_mapped(rb))) 513 return true; 514 return __rpcrdma_regbuf_dma_map(r_xprt, rb); 515} 516 517/* 518 * Wrappers for chunk registration, shared by read/write chunk code. 519 */ 520 521static inline enum dma_data_direction 522rpcrdma_data_dir(bool writing) 523{ 524 return writing ? DMA_FROM_DEVICE : DMA_TO_DEVICE; 525} 526 527/* Memory registration calls xprtrdma/frwr_ops.c 528 */ 529void frwr_reset(struct rpcrdma_req *req); 530int frwr_query_device(struct rpcrdma_ep *ep, const struct ib_device *device); 531int frwr_mr_init(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr *mr); 532void frwr_mr_release(struct rpcrdma_mr *mr); 533struct rpcrdma_mr_seg *frwr_map(struct rpcrdma_xprt *r_xprt, 534 struct rpcrdma_mr_seg *seg, 535 int nsegs, bool writing, __be32 xid, 536 struct rpcrdma_mr *mr); 537int frwr_send(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req); 538void frwr_reminv(struct rpcrdma_rep *rep, struct list_head *mrs); 539void frwr_unmap_sync(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req); 540void frwr_unmap_async(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req); 541int frwr_wp_create(struct rpcrdma_xprt *r_xprt); 542 543/* 544 * RPC/RDMA protocol calls - xprtrdma/rpc_rdma.c 545 */ 546 547enum rpcrdma_chunktype { 548 rpcrdma_noch = 0, 549 rpcrdma_noch_pullup, 550 rpcrdma_noch_mapped, 551 rpcrdma_readch, 552 rpcrdma_areadch, 553 rpcrdma_writech, 554 rpcrdma_replych 555}; 556 557int rpcrdma_prepare_send_sges(struct rpcrdma_xprt *r_xprt, 558 struct rpcrdma_req *req, u32 hdrlen, 559 struct xdr_buf *xdr, 560 enum rpcrdma_chunktype rtype); 561void rpcrdma_sendctx_unmap(struct rpcrdma_sendctx *sc); 562int rpcrdma_marshal_req(struct rpcrdma_xprt *r_xprt, struct rpc_rqst *rqst); 563void rpcrdma_set_max_header_sizes(struct rpcrdma_ep *ep); 564void rpcrdma_reset_cwnd(struct rpcrdma_xprt *r_xprt); 565void rpcrdma_complete_rqst(struct rpcrdma_rep *rep); 566void rpcrdma_unpin_rqst(struct rpcrdma_rep *rep); 567void rpcrdma_reply_handler(struct rpcrdma_rep *rep); 568 569static inline void rpcrdma_set_xdrlen(struct xdr_buf *xdr, size_t len) 570{ 571 xdr->head[0].iov_len = len; 572 xdr->len = len; 573} 574 575/* RPC/RDMA module init - xprtrdma/transport.c 576 */ 577extern unsigned int xprt_rdma_max_inline_read; 578extern unsigned int xprt_rdma_max_inline_write; 579void xprt_rdma_format_addresses(struct rpc_xprt *xprt, struct sockaddr *sap); 580void xprt_rdma_free_addresses(struct rpc_xprt *xprt); 581void xprt_rdma_close(struct rpc_xprt *xprt); 582void xprt_rdma_print_stats(struct rpc_xprt *xprt, struct seq_file *seq); 583int xprt_rdma_init(void); 584void xprt_rdma_cleanup(void); 585 586/* Backchannel calls - xprtrdma/backchannel.c 587 */ 588#if defined(CONFIG_SUNRPC_BACKCHANNEL) 589int xprt_rdma_bc_setup(struct rpc_xprt *, unsigned int); 590size_t xprt_rdma_bc_maxpayload(struct rpc_xprt *); 591unsigned int xprt_rdma_bc_max_slots(struct rpc_xprt *); 592int rpcrdma_bc_post_recv(struct rpcrdma_xprt *, unsigned int); 593void rpcrdma_bc_receive_call(struct rpcrdma_xprt *, struct rpcrdma_rep *); 594int xprt_rdma_bc_send_reply(struct rpc_rqst *rqst); 595void xprt_rdma_bc_free_rqst(struct rpc_rqst *); 596void xprt_rdma_bc_destroy(struct rpc_xprt *, unsigned int); 597#endif /* CONFIG_SUNRPC_BACKCHANNEL */ 598 599extern struct xprt_class xprt_rdma_bc; 600 601#endif /* _LINUX_SUNRPC_XPRT_RDMA_H */