summaryrefslogtreecommitdiff
path: root/fs/afs/rxrpc.c
blob: 4f6b00efc27c2ddf71894dae00509c9cf21e7c19 (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
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
/* Maintain an RxRPC server socket to do AFS communications through
 *
 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/slab.h>
#include <linux/sched/signal.h>

#include <net/sock.h>
#include <net/af_rxrpc.h>
#include <rxrpc/packet.h>
#include "internal.h"
#include "afs_cm.h"

struct socket *afs_socket; /* my RxRPC socket */
static struct workqueue_struct *afs_async_calls;
static struct afs_call *afs_spare_incoming_call;
atomic_t afs_outstanding_calls;

static void afs_wake_up_call_waiter(struct sock *, struct rxrpc_call *, unsigned long);
static int afs_wait_for_call_to_complete(struct afs_call *);
static void afs_wake_up_async_call(struct sock *, struct rxrpc_call *, unsigned long);
static void afs_process_async_call(struct work_struct *);
static void afs_rx_new_call(struct sock *, struct rxrpc_call *, unsigned long);
static void afs_rx_discard_new_call(struct rxrpc_call *, unsigned long);
static int afs_deliver_cm_op_id(struct afs_call *);

/* asynchronous incoming call initial processing */
static const struct afs_call_type afs_RXCMxxxx = {
	.name		= "CB.xxxx",
	.deliver	= afs_deliver_cm_op_id,
	.abort_to_error	= afs_abort_to_error,
};

static void afs_charge_preallocation(struct work_struct *);

static DECLARE_WORK(afs_charge_preallocation_work, afs_charge_preallocation);

static int afs_wait_atomic_t(atomic_t *p)
{
	schedule();
	return 0;
}

/*
 * open an RxRPC socket and bind it to be a server for callback notifications
 * - the socket is left in blocking mode and non-blocking ops use MSG_DONTWAIT
 */
int afs_open_socket(void)
{
	struct sockaddr_rxrpc srx;
	struct socket *socket;
	int ret;

	_enter("");

	ret = -ENOMEM;
	afs_async_calls = alloc_workqueue("kafsd", WQ_MEM_RECLAIM, 0);
	if (!afs_async_calls)
		goto error_0;

	ret = sock_create_kern(&init_net, AF_RXRPC, SOCK_DGRAM, PF_INET, &socket);
	if (ret < 0)
		goto error_1;

	socket->sk->sk_allocation = GFP_NOFS;

	/* bind the callback manager's address to make this a server socket */
	srx.srx_family			= AF_RXRPC;
	srx.srx_service			= CM_SERVICE;
	srx.transport_type		= SOCK_DGRAM;
	srx.transport_len		= sizeof(srx.transport.sin);
	srx.transport.sin.sin_family	= AF_INET;
	srx.transport.sin.sin_port	= htons(AFS_CM_PORT);
	memset(&srx.transport.sin.sin_addr, 0,
	       sizeof(srx.transport.sin.sin_addr));

	ret = kernel_bind(socket, (struct sockaddr *) &srx, sizeof(srx));
	if (ret < 0)
		goto error_2;

	rxrpc_kernel_new_call_notification(socket, afs_rx_new_call,
					   afs_rx_discard_new_call);

	ret = kernel_listen(socket, INT_MAX);
	if (ret < 0)
		goto error_2;

	afs_socket = socket;
	afs_charge_preallocation(NULL);
	_leave(" = 0");
	return 0;

error_2:
	sock_release(socket);
error_1:
	destroy_workqueue(afs_async_calls);
error_0:
	_leave(" = %d", ret);
	return ret;
}

/*
 * close the RxRPC socket AFS was using
 */
void afs_close_socket(void)
{
	_enter("");

	kernel_listen(afs_socket, 0);
	flush_workqueue(afs_async_calls);

	if (afs_spare_incoming_call) {
		afs_put_call(afs_spare_incoming_call);
		afs_spare_incoming_call = NULL;
	}

	_debug("outstanding %u", atomic_read(&afs_outstanding_calls));
	wait_on_atomic_t(&afs_outstanding_calls, afs_wait_atomic_t,
			 TASK_UNINTERRUPTIBLE);
	_debug("no outstanding calls");

	kernel_sock_shutdown(afs_socket, SHUT_RDWR);
	flush_workqueue(afs_async_calls);
	sock_release(afs_socket);

	_debug("dework");
	destroy_workqueue(afs_async_calls);
	_leave("");
}

/*
 * Allocate a call.
 */
static struct afs_call *afs_alloc_call(const struct afs_call_type *type,
				       gfp_t gfp)
{
	struct afs_call *call;
	int o;

	call = kzalloc(sizeof(*call), gfp);
	if (!call)
		return NULL;

	call->type = type;
	atomic_set(&call->usage, 1);
	INIT_WORK(&call->async_work, afs_process_async_call);
	init_waitqueue_head(&call->waitq);

	o = atomic_inc_return(&afs_outstanding_calls);
	trace_afs_call(call, afs_call_trace_alloc, 1, o,
		       __builtin_return_address(0));
	return call;
}

/*
 * Dispose of a reference on a call.
 */
void afs_put_call(struct afs_call *call)
{
	int n = atomic_dec_return(&call->usage);
	int o = atomic_read(&afs_outstanding_calls);

	trace_afs_call(call, afs_call_trace_put, n + 1, o,
		       __builtin_return_address(0));

	ASSERTCMP(n, >=, 0);
	if (n == 0) {
		ASSERT(!work_pending(&call->async_work));
		ASSERT(call->type->name != NULL);

		if (call->rxcall) {
			rxrpc_kernel_end_call(afs_socket, call->rxcall);
			call->rxcall = NULL;
		}
		if (call->type->destructor)
			call->type->destructor(call);

		kfree(call->request);
		kfree(call);

		o = atomic_dec_return(&afs_outstanding_calls);
		trace_afs_call(call, afs_call_trace_free, 0, o,
			       __builtin_return_address(0));
		if (o == 0)
			wake_up_atomic_t(&afs_outstanding_calls);
	}
}

/*
 * Queue the call for actual work.  Returns 0 unconditionally for convenience.
 */
int afs_queue_call_work(struct afs_call *call)
{
	int u = atomic_inc_return(&call->usage);

	trace_afs_call(call, afs_call_trace_work, u,
		       atomic_read(&afs_outstanding_calls),
		       __builtin_return_address(0));

	INIT_WORK(&call->work, call->type->work);

	if (!queue_work(afs_wq, &call->work))
		afs_put_call(call);
	return 0;
}

/*
 * allocate a call with flat request and reply buffers
 */
struct afs_call *afs_alloc_flat_call(const struct afs_call_type *type,
				     size_t request_size, size_t reply_max)
{
	struct afs_call *call;

	call = afs_alloc_call(type, GFP_NOFS);
	if (!call)
		goto nomem_call;

	if (request_size) {
		call->request_size = request_size;
		call->request = kmalloc(request_size, GFP_NOFS);
		if (!call->request)
			goto nomem_free;
	}

	if (reply_max) {
		call->reply_max = reply_max;
		call->buffer = kmalloc(reply_max, GFP_NOFS);
		if (!call->buffer)
			goto nomem_free;
	}

	init_waitqueue_head(&call->waitq);
	return call;

nomem_free:
	afs_put_call(call);
nomem_call:
	return NULL;
}

/*
 * clean up a call with flat buffer
 */
void afs_flat_call_destructor(struct afs_call *call)
{
	_enter("");

	kfree(call->request);
	call->request = NULL;
	kfree(call->buffer);
	call->buffer = NULL;
}

/*
 * attach the data from a bunch of pages on an inode to a call
 */
static int afs_send_pages(struct afs_call *call, struct msghdr *msg,
			  struct kvec *iov)
{
	struct page *pages[8];
	unsigned count, n, loop, offset, to;
	pgoff_t first = call->first, last = call->last;
	int ret;

	_enter("");

	offset = call->first_offset;
	call->first_offset = 0;

	do {
		_debug("attach %lx-%lx", first, last);

		count = last - first + 1;
		if (count > ARRAY_SIZE(pages))
			count = ARRAY_SIZE(pages);
		n = find_get_pages_contig(call->mapping, first, count, pages);
		ASSERTCMP(n, ==, count);

		loop = 0;
		do {
			msg->msg_flags = 0;
			to = PAGE_SIZE;
			if (first + loop >= last)
				to = call->last_to;
			else
				msg->msg_flags = MSG_MORE;
			iov->iov_base = kmap(pages[loop]) + offset;
			iov->iov_len = to - offset;
			offset = 0;

			_debug("- range %u-%u%s",
			       offset, to, msg->msg_flags ? " [more]" : "");
			iov_iter_kvec(&msg->msg_iter, WRITE | ITER_KVEC,
				      iov, 1, to - offset);

			/* have to change the state *before* sending the last
			 * packet as RxRPC might give us the reply before it
			 * returns from sending the request */
			if (first + loop >= last)
				call->state = AFS_CALL_AWAIT_REPLY;
			ret = rxrpc_kernel_send_data(afs_socket, call->rxcall,
						     msg, to - offset);
			kunmap(pages[loop]);
			if (ret < 0)
				break;
		} while (++loop < count);
		first += count;

		for (loop = 0; loop < count; loop++)
			put_page(pages[loop]);
		if (ret < 0)
			break;
	} while (first <= last);

	_leave(" = %d", ret);
	return ret;
}

/*
 * initiate a call
 */
int afs_make_call(struct in_addr *addr, struct afs_call *call, gfp_t gfp,
		  bool async)
{
	struct sockaddr_rxrpc srx;
	struct rxrpc_call *rxcall;
	struct msghdr msg;
	struct kvec iov[1];
	int ret;

	_enter("%x,{%d},", addr->s_addr, ntohs(call->port));

	ASSERT(call->type != NULL);
	ASSERT(call->type->name != NULL);

	_debug("____MAKE %p{%s,%x} [%d]____",
	       call, call->type->name, key_serial(call->key),
	       atomic_read(&afs_outstanding_calls));

	call->async = async;

	memset(&srx, 0, sizeof(srx));
	srx.srx_family = AF_RXRPC;
	srx.srx_service = call->service_id;
	srx.transport_type = SOCK_DGRAM;
	srx.transport_len = sizeof(srx.transport.sin);
	srx.transport.sin.sin_family = AF_INET;
	srx.transport.sin.sin_port = call->port;
	memcpy(&srx.transport.sin.sin_addr, addr, 4);

	/* create a call */
	rxcall = rxrpc_kernel_begin_call(afs_socket, &srx, call->key,
					 (unsigned long) call, gfp,
					 (async ?
					  afs_wake_up_async_call :
					  afs_wake_up_call_waiter));
	call->key = NULL;
	if (IS_ERR(rxcall)) {
		ret = PTR_ERR(rxcall);
		goto error_kill_call;
	}

	call->rxcall = rxcall;

	/* send the request */
	iov[0].iov_base	= call->request;
	iov[0].iov_len	= call->request_size;

	msg.msg_name		= NULL;
	msg.msg_namelen		= 0;
	iov_iter_kvec(&msg.msg_iter, WRITE | ITER_KVEC, iov, 1,
		      call->request_size);
	msg.msg_control		= NULL;
	msg.msg_controllen	= 0;
	msg.msg_flags		= (call->send_pages ? MSG_MORE : 0);

	/* have to change the state *before* sending the last packet as RxRPC
	 * might give us the reply before it returns from sending the
	 * request */
	if (!call->send_pages)
		call->state = AFS_CALL_AWAIT_REPLY;
	ret = rxrpc_kernel_send_data(afs_socket, rxcall,
				     &msg, call->request_size);
	if (ret < 0)
		goto error_do_abort;

	if (call->send_pages) {
		ret = afs_send_pages(call, &msg, iov);
		if (ret < 0)
			goto error_do_abort;
	}

	/* at this point, an async call may no longer exist as it may have
	 * already completed */
	if (call->async)
		return -EINPROGRESS;

	return afs_wait_for_call_to_complete(call);

error_do_abort:
	rxrpc_kernel_abort_call(afs_socket, rxcall, RX_USER_ABORT, -ret, "KSD");
error_kill_call:
	afs_put_call(call);
	_leave(" = %d", ret);
	return ret;
}

/*
 * deliver messages to a call
 */
static void afs_deliver_to_call(struct afs_call *call)
{
	u32 abort_code;
	int ret;

	_enter("%s", call->type->name);

	while (call->state == AFS_CALL_AWAIT_REPLY ||
	       call->state == AFS_CALL_AWAIT_OP_ID ||
	       call->state == AFS_CALL_AWAIT_REQUEST ||
	       call->state == AFS_CALL_AWAIT_ACK
	       ) {
		if (call->state == AFS_CALL_AWAIT_ACK) {
			size_t offset = 0;
			ret = rxrpc_kernel_recv_data(afs_socket, call->rxcall,
						     NULL, 0, &offset, false,
						     &call->abort_code);
			trace_afs_recv_data(call, 0, offset, false, ret);

			if (ret == -EINPROGRESS || ret == -EAGAIN)
				return;
			if (ret == 1 || ret < 0) {
				call->state = AFS_CALL_COMPLETE;
				goto done;
			}
			return;
		}

		ret = call->type->deliver(call);
		switch (ret) {
		case 0:
			if (call->state == AFS_CALL_AWAIT_REPLY)
				call->state = AFS_CALL_COMPLETE;
			goto done;
		case -EINPROGRESS:
		case -EAGAIN:
			goto out;
		case -ENOTCONN:
			abort_code = RX_CALL_DEAD;
			rxrpc_kernel_abort_call(afs_socket, call->rxcall,
						abort_code, -ret, "KNC");
			goto do_abort;
		case -ENOTSUPP:
			abort_code = RX_INVALID_OPERATION;
			rxrpc_kernel_abort_call(afs_socket, call->rxcall,
						abort_code, -ret, "KIV");
			goto do_abort;
		case -ENODATA:
		case -EBADMSG:
		case -EMSGSIZE:
		default:
			abort_code = RXGEN_CC_UNMARSHAL;
			if (call->state != AFS_CALL_AWAIT_REPLY)
				abort_code = RXGEN_SS_UNMARSHAL;
			rxrpc_kernel_abort_call(afs_socket, call->rxcall,
						abort_code, EBADMSG, "KUM");
			goto do_abort;
		}
	}

done:
	if (call->state == AFS_CALL_COMPLETE && call->incoming)
		afs_put_call(call);
out:
	_leave("");
	return;

do_abort:
	call->error = ret;
	call->state = AFS_CALL_COMPLETE;
	goto done;
}

/*
 * wait synchronously for a call to complete
 */
static int afs_wait_for_call_to_complete(struct afs_call *call)
{
	const char *abort_why;
	int ret;

	DECLARE_WAITQUEUE(myself, current);

	_enter("");

	add_wait_queue(&call->waitq, &myself);
	for (;;) {
		set_current_state(TASK_INTERRUPTIBLE);

		/* deliver any messages that are in the queue */
		if (call->state < AFS_CALL_COMPLETE && call->need_attention) {
			call->need_attention = false;
			__set_current_state(TASK_RUNNING);
			afs_deliver_to_call(call);
			continue;
		}

		abort_why = "KWC";
		ret = call->error;
		if (call->state == AFS_CALL_COMPLETE)
			break;
		abort_why = "KWI";
		ret = -EINTR;
		if (signal_pending(current))
			break;
		schedule();
	}

	remove_wait_queue(&call->waitq, &myself);
	__set_current_state(TASK_RUNNING);

	/* kill the call */
	if (call->state < AFS_CALL_COMPLETE) {
		_debug("call incomplete");
		rxrpc_kernel_abort_call(afs_socket, call->rxcall,
					RX_CALL_DEAD, -ret, abort_why);
	}

	_debug("call complete");
	afs_put_call(call);
	_leave(" = %d", ret);
	return ret;
}

/*
 * wake up a waiting call
 */
static void afs_wake_up_call_waiter(struct sock *sk, struct rxrpc_call *rxcall,
				    unsigned long call_user_ID)
{
	struct afs_call *call = (struct afs_call *)call_user_ID;

	call->need_attention = true;
	wake_up(&call->waitq);
}

/*
 * wake up an asynchronous call
 */
static void afs_wake_up_async_call(struct sock *sk, struct rxrpc_call *rxcall,
				   unsigned long call_user_ID)
{
	struct afs_call *call = (struct afs_call *)call_user_ID;
	int u;

	trace_afs_notify_call(rxcall, call);
	call->need_attention = true;

	u = __atomic_add_unless(&call->usage, 1, 0);
	if (u != 0) {
		trace_afs_call(call, afs_call_trace_wake, u,
			       atomic_read(&afs_outstanding_calls),
			       __builtin_return_address(0));

		if (!queue_work(afs_async_calls, &call->async_work))
			afs_put_call(call);
	}
}

/*
 * Delete an asynchronous call.  The work item carries a ref to the call struct
 * that we need to release.
 */
static void afs_delete_async_call(struct work_struct *work)
{
	struct afs_call *call = container_of(work, struct afs_call, async_work);

	_enter("");

	afs_put_call(call);

	_leave("");
}

/*
 * Perform I/O processing on an asynchronous call.  The work item carries a ref
 * to the call struct that we either need to release or to pass on.
 */
static void afs_process_async_call(struct work_struct *work)
{
	struct afs_call *call = container_of(work, struct afs_call, async_work);

	_enter("");

	if (call->state < AFS_CALL_COMPLETE && call->need_attention) {
		call->need_attention = false;
		afs_deliver_to_call(call);
	}

	if (call->state == AFS_CALL_COMPLETE) {
		call->reply = NULL;

		/* We have two refs to release - one from the alloc and one
		 * queued with the work item - and we can't just deallocate the
		 * call because the work item may be queued again.
		 */
		call->async_work.func = afs_delete_async_call;
		if (!queue_work(afs_async_calls, &call->async_work))
			afs_put_call(call);
	}

	afs_put_call(call);
	_leave("");
}

static void afs_rx_attach(struct rxrpc_call *rxcall, unsigned long user_call_ID)
{
	struct afs_call *call = (struct afs_call *)user_call_ID;

	call->rxcall = rxcall;
}

/*
 * Charge the incoming call preallocation.
 */
static void afs_charge_preallocation(struct work_struct *work)
{
	struct afs_call *call = afs_spare_incoming_call;

	for (;;) {
		if (!call) {
			call = afs_alloc_call(&afs_RXCMxxxx, GFP_KERNEL);
			if (!call)
				break;

			call->async = true;
			call->state = AFS_CALL_AWAIT_OP_ID;
			init_waitqueue_head(&call->waitq);
		}

		if (rxrpc_kernel_charge_accept(afs_socket,
					       afs_wake_up_async_call,
					       afs_rx_attach,
					       (unsigned long)call,
					       GFP_KERNEL) < 0)
			break;
		call = NULL;
	}
	afs_spare_incoming_call = call;
}

/*
 * Discard a preallocated call when a socket is shut down.
 */
static void afs_rx_discard_new_call(struct rxrpc_call *rxcall,
				    unsigned long user_call_ID)
{
	struct afs_call *call = (struct afs_call *)user_call_ID;

	call->rxcall = NULL;
	afs_put_call(call);
}

/*
 * Notification of an incoming call.
 */
static void afs_rx_new_call(struct sock *sk, struct rxrpc_call *rxcall,
			    unsigned long user_call_ID)
{
	queue_work(afs_wq, &afs_charge_preallocation_work);
}

/*
 * Grab the operation ID from an incoming cache manager call.  The socket
 * buffer is discarded on error or if we don't yet have sufficient data.
 */
static int afs_deliver_cm_op_id(struct afs_call *call)
{
	int ret;

	_enter("{%zu}", call->offset);

	ASSERTCMP(call->offset, <, 4);

	/* the operation ID forms the first four bytes of the request data */
	ret = afs_extract_data(call, &call->tmp, 4, true);
	if (ret < 0)
		return ret;

	call->operation_ID = ntohl(call->tmp);
	call->state = AFS_CALL_AWAIT_REQUEST;
	call->offset = 0;

	/* ask the cache manager to route the call (it'll change the call type
	 * if successful) */
	if (!afs_cm_incoming_call(call))
		return -ENOTSUPP;

	trace_afs_cb_call(call);

	/* pass responsibility for the remainer of this message off to the
	 * cache manager op */
	return call->type->deliver(call);
}

/*
 * send an empty reply
 */
void afs_send_empty_reply(struct afs_call *call)
{
	struct msghdr msg;

	_enter("");

	msg.msg_name		= NULL;
	msg.msg_namelen		= 0;
	iov_iter_kvec(&msg.msg_iter, WRITE | ITER_KVEC, NULL, 0, 0);
	msg.msg_control		= NULL;
	msg.msg_controllen	= 0;
	msg.msg_flags		= 0;

	call->state = AFS_CALL_AWAIT_ACK;
	switch (rxrpc_kernel_send_data(afs_socket, call->rxcall, &msg, 0)) {
	case 0:
		_leave(" [replied]");
		return;

	case -ENOMEM:
		_debug("oom");
		rxrpc_kernel_abort_call(afs_socket, call->rxcall,
					RX_USER_ABORT, ENOMEM, "KOO");
	default:
		_leave(" [error]");
		return;
	}
}

/*
 * send a simple reply
 */
void afs_send_simple_reply(struct afs_call *call, const void *buf, size_t len)
{
	struct msghdr msg;
	struct kvec iov[1];
	int n;

	_enter("");

	iov[0].iov_base		= (void *) buf;
	iov[0].iov_len		= len;
	msg.msg_name		= NULL;
	msg.msg_namelen		= 0;
	iov_iter_kvec(&msg.msg_iter, WRITE | ITER_KVEC, iov, 1, len);
	msg.msg_control		= NULL;
	msg.msg_controllen	= 0;
	msg.msg_flags		= 0;

	call->state = AFS_CALL_AWAIT_ACK;
	n = rxrpc_kernel_send_data(afs_socket, call->rxcall, &msg, len);
	if (n >= 0) {
		/* Success */
		_leave(" [replied]");
		return;
	}

	if (n == -ENOMEM) {
		_debug("oom");
		rxrpc_kernel_abort_call(afs_socket, call->rxcall,
					RX_USER_ABORT, ENOMEM, "KOO");
	}
	_leave(" [error]");
}

/*
 * Extract a piece of data from the received data socket buffers.
 */
int afs_extract_data(struct afs_call *call, void *buf, size_t count,
		     bool want_more)
{
	int ret;

	_enter("{%s,%zu},,%zu,%d",
	       call->type->name, call->offset, count, want_more);

	ASSERTCMP(call->offset, <=, count);

	ret = rxrpc_kernel_recv_data(afs_socket, call->rxcall,
				     buf, count, &call->offset,
				     want_more, &call->abort_code);
	trace_afs_recv_data(call, count, call->offset, want_more, ret);
	if (ret == 0 || ret == -EAGAIN)
		return ret;

	if (ret == 1) {
		switch (call->state) {
		case AFS_CALL_AWAIT_REPLY:
			call->state = AFS_CALL_COMPLETE;
			break;
		case AFS_CALL_AWAIT_REQUEST:
			call->state = AFS_CALL_REPLYING;
			break;
		default:
			break;
		}
		return 0;
	}

	if (ret == -ECONNABORTED)
		call->error = call->type->abort_to_error(call->abort_code);
	else
		call->error = ret;
	call->state = AFS_CALL_COMPLETE;
	return ret;
}