aboutsummaryrefslogtreecommitdiff
path: root/net/sunrpc/xprtrdma/transport.c
blob: 8915e42240d38b057ed4c6477bd78b7f1f0dc897 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
/*
 * Copyright (c) 2014-2017 Oracle.  All rights reserved.
 * Copyright (c) 2003-2007 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.
 */

/*
 * transport.c
 *
 * This file contains the top-level implementation of an RPC RDMA
 * transport.
 *
 * Naming convention: functions beginning with xprt_ are part of the
 * transport switch. All others are RPC RDMA internal.
 */

#include <linux/module.h>
#include <linux/slab.h>
#include <linux/seq_file.h>
#include <linux/smp.h>

#include <linux/sunrpc/addr.h>
#include <linux/sunrpc/svc_rdma.h>

#include "xprt_rdma.h"
#include <trace/events/rpcrdma.h>

#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
# define RPCDBG_FACILITY	RPCDBG_TRANS
#endif

/*
 * tunables
 */

static unsigned int xprt_rdma_slot_table_entries = RPCRDMA_DEF_SLOT_TABLE;
unsigned int xprt_rdma_max_inline_read = RPCRDMA_DEF_INLINE;
unsigned int xprt_rdma_max_inline_write = RPCRDMA_DEF_INLINE;
unsigned int xprt_rdma_memreg_strategy		= RPCRDMA_FRWR;
int xprt_rdma_pad_optimize;

#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)

static unsigned int min_slot_table_size = RPCRDMA_MIN_SLOT_TABLE;
static unsigned int max_slot_table_size = RPCRDMA_MAX_SLOT_TABLE;
static unsigned int min_inline_size = RPCRDMA_MIN_INLINE;
static unsigned int max_inline_size = RPCRDMA_MAX_INLINE;
static unsigned int max_padding = PAGE_SIZE;
static unsigned int min_memreg = RPCRDMA_BOUNCEBUFFERS;
static unsigned int max_memreg = RPCRDMA_LAST - 1;
static unsigned int dummy;

static struct ctl_table_header *sunrpc_table_header;

static struct ctl_table xr_tunables_table[] = {
	{
		.procname	= "rdma_slot_table_entries",
		.data		= &xprt_rdma_slot_table_entries,
		.maxlen		= sizeof(unsigned int),
		.mode		= 0644,
		.proc_handler	= proc_dointvec_minmax,
		.extra1		= &min_slot_table_size,
		.extra2		= &max_slot_table_size
	},
	{
		.procname	= "rdma_max_inline_read",
		.data		= &xprt_rdma_max_inline_read,
		.maxlen		= sizeof(unsigned int),
		.mode		= 0644,
		.proc_handler	= proc_dointvec_minmax,
		.extra1		= &min_inline_size,
		.extra2		= &max_inline_size,
	},
	{
		.procname	= "rdma_max_inline_write",
		.data		= &xprt_rdma_max_inline_write,
		.maxlen		= sizeof(unsigned int),
		.mode		= 0644,
		.proc_handler	= proc_dointvec_minmax,
		.extra1		= &min_inline_size,
		.extra2		= &max_inline_size,
	},
	{
		.procname	= "rdma_inline_write_padding",
		.data		= &dummy,
		.maxlen		= sizeof(unsigned int),
		.mode		= 0644,
		.proc_handler	= proc_dointvec_minmax,
		.extra1		= SYSCTL_ZERO,
		.extra2		= &max_padding,
	},
	{
		.procname	= "rdma_memreg_strategy",
		.data		= &xprt_rdma_memreg_strategy,
		.maxlen		= sizeof(unsigned int),
		.mode		= 0644,
		.proc_handler	= proc_dointvec_minmax,
		.extra1		= &min_memreg,
		.extra2		= &max_memreg,
	},
	{
		.procname	= "rdma_pad_optimize",
		.data		= &xprt_rdma_pad_optimize,
		.maxlen		= sizeof(unsigned int),
		.mode		= 0644,
		.proc_handler	= proc_dointvec,
	},
	{ },
};

static struct ctl_table sunrpc_table[] = {
	{
		.procname	= "sunrpc",
		.mode		= 0555,
		.child		= xr_tunables_table
	},
	{ },
};

#endif

static const struct rpc_xprt_ops xprt_rdma_procs;

static void
xprt_rdma_format_addresses4(struct rpc_xprt *xprt, struct sockaddr *sap)
{
	struct sockaddr_in *sin = (struct sockaddr_in *)sap;
	char buf[20];

	snprintf(buf, sizeof(buf), "%08x", ntohl(sin->sin_addr.s_addr));
	xprt->address_strings[RPC_DISPLAY_HEX_ADDR] = kstrdup(buf, GFP_KERNEL);

	xprt->address_strings[RPC_DISPLAY_NETID] = RPCBIND_NETID_RDMA;
}

static void
xprt_rdma_format_addresses6(struct rpc_xprt *xprt, struct sockaddr *sap)
{
	struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)sap;
	char buf[40];

	snprintf(buf, sizeof(buf), "%pi6", &sin6->sin6_addr);
	xprt->address_strings[RPC_DISPLAY_HEX_ADDR] = kstrdup(buf, GFP_KERNEL);

	xprt->address_strings[RPC_DISPLAY_NETID] = RPCBIND_NETID_RDMA6;
}

void
xprt_rdma_format_addresses(struct rpc_xprt *xprt, struct sockaddr *sap)
{
	char buf[128];

	switch (sap->sa_family) {
	case AF_INET:
		xprt_rdma_format_addresses4(xprt, sap);
		break;
	case AF_INET6:
		xprt_rdma_format_addresses6(xprt, sap);
		break;
	default:
		pr_err("rpcrdma: Unrecognized address family\n");
		return;
	}

	(void)rpc_ntop(sap, buf, sizeof(buf));
	xprt->address_strings[RPC_DISPLAY_ADDR] = kstrdup(buf, GFP_KERNEL);

	snprintf(buf, sizeof(buf), "%u", rpc_get_port(sap));
	xprt->address_strings[RPC_DISPLAY_PORT] = kstrdup(buf, GFP_KERNEL);

	snprintf(buf, sizeof(buf), "%4hx", rpc_get_port(sap));
	xprt->address_strings[RPC_DISPLAY_HEX_PORT] = kstrdup(buf, GFP_KERNEL);

	xprt->address_strings[RPC_DISPLAY_PROTO] = "rdma";
}

void
xprt_rdma_free_addresses(struct rpc_xprt *xprt)
{
	unsigned int i;

	for (i = 0; i < RPC_DISPLAY_MAX; i++)
		switch (i) {
		case RPC_DISPLAY_PROTO:
		case RPC_DISPLAY_NETID:
			continue;
		default:
			kfree(xprt->address_strings[i]);
		}
}

/**
 * xprt_rdma_connect_worker - establish connection in the background
 * @work: worker thread context
 *
 * Requester holds the xprt's send lock to prevent activity on this
 * transport while a fresh connection is being established. RPC tasks
 * sleep on the xprt's pending queue waiting for connect to complete.
 */
static void
xprt_rdma_connect_worker(struct work_struct *work)
{
	struct rpcrdma_xprt *r_xprt = container_of(work, struct rpcrdma_xprt,
						   rx_connect_worker.work);
	struct rpc_xprt *xprt = &r_xprt->rx_xprt;
	int rc;

	rc = rpcrdma_xprt_connect(r_xprt);
	xprt_clear_connecting(xprt);
	if (!rc) {
		xprt->connect_cookie++;
		xprt->stat.connect_count++;
		xprt->stat.connect_time += (long)jiffies -
					   xprt->stat.connect_start;
		xprt_set_connected(xprt);
		rc = -EAGAIN;
	} else {
		/* Force a call to xprt_rdma_close to clean up */
		spin_lock(&xprt->transport_lock);
		set_bit(XPRT_CLOSE_WAIT, &xprt->state);
		spin_unlock(&xprt->transport_lock);
	}
	xprt_wake_pending_tasks(xprt, rc);
}

/**
 * xprt_rdma_inject_disconnect - inject a connection fault
 * @xprt: transport context
 *
 * If @xprt is connected, disconnect it to simulate spurious connection
 * loss.
 */
static void
xprt_rdma_inject_disconnect(struct rpc_xprt *xprt)
{
	struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);

	trace_xprtrdma_op_inject_dsc(r_xprt);
	rdma_disconnect(r_xprt->rx_ep->re_id);
}

/**
 * xprt_rdma_destroy - Full tear down of transport
 * @xprt: doomed transport context
 *
 * Caller guarantees there will be no more calls to us with
 * this @xprt.
 */
static void
xprt_rdma_destroy(struct rpc_xprt *xprt)
{
	struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);

	cancel_delayed_work_sync(&r_xprt->rx_connect_worker);

	rpcrdma_xprt_disconnect(r_xprt);
	rpcrdma_buffer_destroy(&r_xprt->rx_buf);

	xprt_rdma_free_addresses(xprt);
	xprt_free(xprt);

	module_put(THIS_MODULE);
}

/* 60 second timeout, no retries */
static const struct rpc_timeout xprt_rdma_default_timeout = {
	.to_initval = 60 * HZ,
	.to_maxval = 60 * HZ,
};

/**
 * xprt_setup_rdma - Set up transport to use RDMA
 *
 * @args: rpc transport arguments
 */
static struct rpc_xprt *
xprt_setup_rdma(struct xprt_create *args)
{
	struct rpc_xprt *xprt;
	struct rpcrdma_xprt *new_xprt;
	struct sockaddr *sap;
	int rc;

	if (args->addrlen > sizeof(xprt->addr))
		return ERR_PTR(-EBADF);

	if (!try_module_get(THIS_MODULE))
		return ERR_PTR(-EIO);

	xprt = xprt_alloc(args->net, sizeof(struct rpcrdma_xprt), 0,
			  xprt_rdma_slot_table_entries);
	if (!xprt) {
		module_put(THIS_MODULE);
		return ERR_PTR(-ENOMEM);
	}

	xprt->timeout = &xprt_rdma_default_timeout;
	xprt->connect_timeout = xprt->timeout->to_initval;
	xprt->max_reconnect_timeout = xprt->timeout->to_maxval;
	xprt->bind_timeout = RPCRDMA_BIND_TO;
	xprt->reestablish_timeout = RPCRDMA_INIT_REEST_TO;
	xprt->idle_timeout = RPCRDMA_IDLE_DISC_TO;

	xprt->resvport = 0;		/* privileged port not needed */
	xprt->ops = &xprt_rdma_procs;

	/*
	 * Set up RDMA-specific connect data.
	 */
	sap = args->dstaddr;

	/* Ensure xprt->addr holds valid server TCP (not RDMA)
	 * address, for any side protocols which peek at it */
	xprt->prot = IPPROTO_TCP;
	xprt->addrlen = args->addrlen;
	memcpy(&xprt->addr, sap, xprt->addrlen);

	if (rpc_get_port(sap))
		xprt_set_bound(xprt);
	xprt_rdma_format_addresses(xprt, sap);

	new_xprt = rpcx_to_rdmax(xprt);
	rc = rpcrdma_buffer_create(new_xprt);
	if (rc) {
		xprt_rdma_free_addresses(xprt);
		xprt_free(xprt);
		module_put(THIS_MODULE);
		return ERR_PTR(rc);
	}

	INIT_DELAYED_WORK(&new_xprt->rx_connect_worker,
			  xprt_rdma_connect_worker);

	xprt->max_payload = RPCRDMA_MAX_DATA_SEGS << PAGE_SHIFT;

	return xprt;
}

/**
 * xprt_rdma_close - close a transport connection
 * @xprt: transport context
 *
 * Called during autoclose or device removal.
 *
 * Caller holds @xprt's send lock to prevent activity on this
 * transport while the connection is torn down.
 */
void xprt_rdma_close(struct rpc_xprt *xprt)
{
	struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);

	rpcrdma_xprt_disconnect(r_xprt);

	xprt->reestablish_timeout = 0;
	++xprt->connect_cookie;
	xprt_disconnect_done(xprt);
}

/**
 * xprt_rdma_set_port - update server port with rpcbind result
 * @xprt: controlling RPC transport
 * @port: new port value
 *
 * Transport connect status is unchanged.
 */
static void
xprt_rdma_set_port(struct rpc_xprt *xprt, u16 port)
{
	struct sockaddr *sap = (struct sockaddr *)&xprt->addr;
	char buf[8];

	rpc_set_port(sap, port);

	kfree(xprt->address_strings[RPC_DISPLAY_PORT]);
	snprintf(buf, sizeof(buf), "%u", port);
	xprt->address_strings[RPC_DISPLAY_PORT] = kstrdup(buf, GFP_KERNEL);

	kfree(xprt->address_strings[RPC_DISPLAY_HEX_PORT]);
	snprintf(buf, sizeof(buf), "%4hx", port);
	xprt->address_strings[RPC_DISPLAY_HEX_PORT] = kstrdup(buf, GFP_KERNEL);
}

/**
 * xprt_rdma_timer - invoked when an RPC times out
 * @xprt: controlling RPC transport
 * @task: RPC task that timed out
 *
 * Invoked when the transport is still connected, but an RPC
 * retransmit timeout occurs.
 *
 * Since RDMA connections don't have a keep-alive, forcibly
 * disconnect and retry to connect. This drives full
 * detection of the network path, and retransmissions of
 * all pending RPCs.
 */
static void
xprt_rdma_timer(struct rpc_xprt *xprt, struct rpc_task *task)
{
	xprt_force_disconnect(xprt);
}

/**
 * xprt_rdma_set_connect_timeout - set timeouts for establishing a connection
 * @xprt: controlling transport instance
 * @connect_timeout: reconnect timeout after client disconnects
 * @reconnect_timeout: reconnect timeout after server disconnects
 *
 */
static void xprt_rdma_set_connect_timeout(struct rpc_xprt *xprt,
					  unsigned long connect_timeout,
					  unsigned long reconnect_timeout)
{
	struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);

	trace_xprtrdma_op_set_cto(r_xprt, connect_timeout, reconnect_timeout);

	spin_lock(&xprt->transport_lock);

	if (connect_timeout < xprt->connect_timeout) {
		struct rpc_timeout to;
		unsigned long initval;

		to = *xprt->timeout;
		initval = connect_timeout;
		if (initval < RPCRDMA_INIT_REEST_TO << 1)
			initval = RPCRDMA_INIT_REEST_TO << 1;
		to.to_initval = initval;
		to.to_maxval = initval;
		r_xprt->rx_timeout = to;
		xprt->timeout = &r_xprt->rx_timeout;
		xprt->connect_timeout = connect_timeout;
	}

	if (reconnect_timeout < xprt->max_reconnect_timeout)
		xprt->max_reconnect_timeout = reconnect_timeout;

	spin_unlock(&xprt->transport_lock);
}

/**
 * xprt_rdma_connect - schedule an attempt to reconnect
 * @xprt: transport state
 * @task: RPC scheduler context (unused)
 *
 */
static void
xprt_rdma_connect(struct rpc_xprt *xprt, struct rpc_task *task)
{
	struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
	struct rpcrdma_ep *ep = r_xprt->rx_ep;
	unsigned long delay;

	delay = 0;
	if (ep && ep->re_connect_status != 0) {
		delay = xprt_reconnect_delay(xprt);
		xprt_reconnect_backoff(xprt, RPCRDMA_INIT_REEST_TO);
	}
	trace_xprtrdma_op_connect(r_xprt, delay);
	queue_delayed_work(xprtiod_workqueue, &r_xprt->rx_connect_worker,
			   delay);
}

/**
 * xprt_rdma_alloc_slot - allocate an rpc_rqst
 * @xprt: controlling RPC transport
 * @task: RPC task requesting a fresh rpc_rqst
 *
 * tk_status values:
 *	%0 if task->tk_rqstp points to a fresh rpc_rqst
 *	%-EAGAIN if no rpc_rqst is available; queued on backlog
 */
static void
xprt_rdma_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
{
	struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
	struct rpcrdma_req *req;

	req = rpcrdma_buffer_get(&r_xprt->rx_buf);
	if (!req)
		goto out_sleep;
	task->tk_rqstp = &req->rl_slot;
	task->tk_status = 0;
	return;

out_sleep:
	set_bit(XPRT_CONGESTED, &xprt->state);
	rpc_sleep_on(&xprt->backlog, task, NULL);
	task->tk_status = -EAGAIN;
}

/**
 * xprt_rdma_free_slot - release an rpc_rqst
 * @xprt: controlling RPC transport
 * @rqst: rpc_rqst to release
 *
 */
static void
xprt_rdma_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *rqst)
{
	struct rpcrdma_xprt *r_xprt =
		container_of(xprt, struct rpcrdma_xprt, rx_xprt);

	memset(rqst, 0, sizeof(*rqst));
	rpcrdma_buffer_put(&r_xprt->rx_buf, rpcr_to_rdmar(rqst));
	if (unlikely(!rpc_wake_up_next(&xprt->backlog)))
		clear_bit(XPRT_CONGESTED, &xprt->state);
}

static bool rpcrdma_check_regbuf(struct rpcrdma_xprt *r_xprt,
				 struct rpcrdma_regbuf *rb, size_t size,
				 gfp_t flags)
{
	if (unlikely(rdmab_length(rb) < size)) {
		if (!rpcrdma_regbuf_realloc(rb, size, flags))
			return false;
		r_xprt->rx_stats.hardway_register_count += size;
	}
	return true;
}

/**
 * xprt_rdma_allocate - allocate transport resources for an RPC
 * @task: RPC task
 *
 * Return values:
 *        0:	Success; rq_buffer points to RPC buffer to use
 *   ENOMEM:	Out of memory, call again later
 *      EIO:	A permanent error occurred, do not retry
 */
static int
xprt_rdma_allocate(struct rpc_task *task)
{
	struct rpc_rqst *rqst = task->tk_rqstp;
	struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(rqst->rq_xprt);
	struct rpcrdma_req *req = rpcr_to_rdmar(rqst);
	gfp_t flags;

	flags = RPCRDMA_DEF_GFP;
	if (RPC_IS_SWAPPER(task))
		flags = __GFP_MEMALLOC | GFP_NOWAIT | __GFP_NOWARN;

	if (!rpcrdma_check_regbuf(r_xprt, req->rl_sendbuf, rqst->rq_callsize,
				  flags))
		goto out_fail;
	if (!rpcrdma_check_regbuf(r_xprt, req->rl_recvbuf, rqst->rq_rcvsize,
				  flags))
		goto out_fail;

	rqst->rq_buffer = rdmab_data(req->rl_sendbuf);
	rqst->rq_rbuffer = rdmab_data(req->rl_recvbuf);
	return 0;

out_fail:
	return -ENOMEM;
}

/**
 * xprt_rdma_free - release resources allocated by xprt_rdma_allocate
 * @task: RPC task
 *
 * Caller guarantees rqst->rq_buffer is non-NULL.
 */
static void
xprt_rdma_free(struct rpc_task *task)
{
	struct rpc_rqst *rqst = task->tk_rqstp;
	struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(rqst->rq_xprt);
	struct rpcrdma_req *req = rpcr_to_rdmar(rqst);

	if (!list_empty(&req->rl_registered))
		frwr_unmap_sync(r_xprt, req);

	/* XXX: If the RPC is completing because of a signal and
	 * not because a reply was received, we ought to ensure
	 * that the Send completion has fired, so that memory
	 * involved with the Send is not still visible to the NIC.
	 */
}

/**
 * xprt_rdma_send_request - marshal and send an RPC request
 * @rqst: RPC message in rq_snd_buf
 *
 * Caller holds the transport's write lock.
 *
 * Returns:
 *	%0 if the RPC message has been sent
 *	%-ENOTCONN if the caller should reconnect and call again
 *	%-EAGAIN if the caller should call again
 *	%-ENOBUFS if the caller should call again after a delay
 *	%-EMSGSIZE if encoding ran out of buffer space. The request
 *		was not sent. Do not try to send this message again.
 *	%-EIO if an I/O error occurred. The request was not sent.
 *		Do not try to send this message again.
 */
static int
xprt_rdma_send_request(struct rpc_rqst *rqst)
{
	struct rpc_xprt *xprt = rqst->rq_xprt;
	struct rpcrdma_req *req = rpcr_to_rdmar(rqst);
	struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
	int rc = 0;

#if defined(CONFIG_SUNRPC_BACKCHANNEL)
	if (unlikely(!rqst->rq_buffer))
		return xprt_rdma_bc_send_reply(rqst);
#endif	/* CONFIG_SUNRPC_BACKCHANNEL */

	if (!xprt_connected(xprt))
		return -ENOTCONN;

	if (!xprt_request_get_cong(xprt, rqst))
		return -EBADSLT;

	rc = rpcrdma_marshal_req(r_xprt, rqst);
	if (rc < 0)
		goto failed_marshal;

	/* Must suppress retransmit to maintain credits */
	if (rqst->rq_connect_cookie == xprt->connect_cookie)
		goto drop_connection;
	rqst->rq_xtime = ktime_get();

	if (rpcrdma_post_sends(r_xprt, req))
		goto drop_connection;

	rqst->rq_xmit_bytes_sent += rqst->rq_snd_buf.len;

	/* An RPC with no reply will throw off credit accounting,
	 * so drop the connection to reset the credit grant.
	 */
	if (!rpc_reply_expected(rqst->rq_task))
		goto drop_connection;
	return 0;

failed_marshal:
	if (rc != -ENOTCONN)
		return rc;
drop_connection:
	xprt_rdma_close(xprt);
	return -ENOTCONN;
}

void xprt_rdma_print_stats(struct rpc_xprt *xprt, struct seq_file *seq)
{
	struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
	long idle_time = 0;

	if (xprt_connected(xprt))
		idle_time = (long)(jiffies - xprt->last_used) / HZ;

	seq_puts(seq, "\txprt:\trdma ");
	seq_printf(seq, "%u %lu %lu %lu %ld %lu %lu %lu %llu %llu ",
		   0,	/* need a local port? */
		   xprt->stat.bind_count,
		   xprt->stat.connect_count,
		   xprt->stat.connect_time / HZ,
		   idle_time,
		   xprt->stat.sends,
		   xprt->stat.recvs,
		   xprt->stat.bad_xids,
		   xprt->stat.req_u,
		   xprt->stat.bklog_u);
	seq_printf(seq, "%lu %lu %lu %llu %llu %llu %llu %lu %lu %lu %lu ",
		   r_xprt->rx_stats.read_chunk_count,
		   r_xprt->rx_stats.write_chunk_count,
		   r_xprt->rx_stats.reply_chunk_count,
		   r_xprt->rx_stats.total_rdma_request,
		   r_xprt->rx_stats.total_rdma_reply,
		   r_xprt->rx_stats.pullup_copy_count,
		   r_xprt->rx_stats.fixup_copy_count,
		   r_xprt->rx_stats.hardway_register_count,
		   r_xprt->rx_stats.failed_marshal_count,
		   r_xprt->rx_stats.bad_reply_count,
		   r_xprt->rx_stats.nomsg_call_count);
	seq_printf(seq, "%lu %lu %lu %lu %lu %lu\n",
		   r_xprt->rx_stats.mrs_recycled,
		   r_xprt->rx_stats.mrs_orphaned,
		   r_xprt->rx_stats.mrs_allocated,
		   r_xprt->rx_stats.local_inv_needed,
		   r_xprt->rx_stats.empty_sendctx_q,
		   r_xprt->rx_stats.reply_waits_for_send);
}

static int
xprt_rdma_enable_swap(struct rpc_xprt *xprt)
{
	return 0;
}

static void
xprt_rdma_disable_swap(struct rpc_xprt *xprt)
{
}

/*
 * Plumbing for rpc transport switch and kernel module
 */

static const struct rpc_xprt_ops xprt_rdma_procs = {
	.reserve_xprt		= xprt_reserve_xprt_cong,
	.release_xprt		= xprt_release_xprt_cong, /* sunrpc/xprt.c */
	.alloc_slot		= xprt_rdma_alloc_slot,
	.free_slot		= xprt_rdma_free_slot,
	.release_request	= xprt_release_rqst_cong,       /* ditto */
	.wait_for_reply_request	= xprt_wait_for_reply_request_def, /* ditto */
	.timer			= xprt_rdma_timer,
	.rpcbind		= rpcb_getport_async,	/* sunrpc/rpcb_clnt.c */
	.set_port		= xprt_rdma_set_port,
	.connect		= xprt_rdma_connect,
	.buf_alloc		= xprt_rdma_allocate,
	.buf_free		= xprt_rdma_free,
	.send_request		= xprt_rdma_send_request,
	.close			= xprt_rdma_close,
	.destroy		= xprt_rdma_destroy,
	.set_connect_timeout	= xprt_rdma_set_connect_timeout,
	.print_stats		= xprt_rdma_print_stats,
	.enable_swap		= xprt_rdma_enable_swap,
	.disable_swap		= xprt_rdma_disable_swap,
	.inject_disconnect	= xprt_rdma_inject_disconnect,
#if defined(CONFIG_SUNRPC_BACKCHANNEL)
	.bc_setup		= xprt_rdma_bc_setup,
	.bc_maxpayload		= xprt_rdma_bc_maxpayload,
	.bc_num_slots		= xprt_rdma_bc_max_slots,
	.bc_free_rqst		= xprt_rdma_bc_free_rqst,
	.bc_destroy		= xprt_rdma_bc_destroy,
#endif
};

static struct xprt_class xprt_rdma = {
	.list			= LIST_HEAD_INIT(xprt_rdma.list),
	.name			= "rdma",
	.owner			= THIS_MODULE,
	.ident			= XPRT_TRANSPORT_RDMA,
	.setup			= xprt_setup_rdma,
};

void xprt_rdma_cleanup(void)
{
#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
	if (sunrpc_table_header) {
		unregister_sysctl_table(sunrpc_table_header);
		sunrpc_table_header = NULL;
	}
#endif

	xprt_unregister_transport(&xprt_rdma);
	xprt_unregister_transport(&xprt_rdma_bc);
}

int xprt_rdma_init(void)
{
	int rc;

	rc = xprt_register_transport(&xprt_rdma);
	if (rc)
		return rc;

	rc = xprt_register_transport(&xprt_rdma_bc);
	if (rc) {
		xprt_unregister_transport(&xprt_rdma);
		return rc;
	}

#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
	if (!sunrpc_table_header)
		sunrpc_table_header = register_sysctl_table(sunrpc_table);
#endif
	return 0;
}