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[AFS]: Add support for the CB.GetCapabilities operation.
[linux-2.6/kmemtrace.git] / fs / afs / rxrpc.c
blobe7b047328a39df53e6efb774f95baaddc9dcd14e
1 /* Maintain an RxRPC server socket to do AFS communications through
2 *
3 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 */
11
12 #include <net/sock.h>
13 #include <net/af_rxrpc.h>
14 #include <rxrpc/packet.h>
15 #include "internal.h"
16 #include "afs_cm.h"
17
18 static struct socket *afs_socket; /* my RxRPC socket */
19 static struct workqueue_struct *afs_async_calls;
20 static atomic_t afs_outstanding_calls;
21 static atomic_t afs_outstanding_skbs;
22
23 static void afs_wake_up_call_waiter(struct afs_call *);
24 static int afs_wait_for_call_to_complete(struct afs_call *);
25 static void afs_wake_up_async_call(struct afs_call *);
26 static int afs_dont_wait_for_call_to_complete(struct afs_call *);
27 static void afs_process_async_call(struct work_struct *);
28 static void afs_rx_interceptor(struct sock *, unsigned long, struct sk_buff *);
29 static int afs_deliver_cm_op_id(struct afs_call *, struct sk_buff *, bool);
30
31 /* synchronous call management */
32 const struct afs_wait_mode afs_sync_call = {
33 .rx_wakeup = afs_wake_up_call_waiter,
34 .wait = afs_wait_for_call_to_complete,
35 };
36
37 /* asynchronous call management */
38 const struct afs_wait_mode afs_async_call = {
39 .rx_wakeup = afs_wake_up_async_call,
40 .wait = afs_dont_wait_for_call_to_complete,
41 };
42
43 /* asynchronous incoming call management */
44 static const struct afs_wait_mode afs_async_incoming_call = {
45 .rx_wakeup = afs_wake_up_async_call,
46 };
47
48 /* asynchronous incoming call initial processing */
49 static const struct afs_call_type afs_RXCMxxxx = {
50 .name = "CB.xxxx",
51 .deliver = afs_deliver_cm_op_id,
52 .abort_to_error = afs_abort_to_error,
53 };
54
55 static void afs_collect_incoming_call(struct work_struct *);
56
57 static struct sk_buff_head afs_incoming_calls;
58 static DECLARE_WORK(afs_collect_incoming_call_work, afs_collect_incoming_call);
59
60 /*
61 * open an RxRPC socket and bind it to be a server for callback notifications
62 * - the socket is left in blocking mode and non-blocking ops use MSG_DONTWAIT
63 */
64 int afs_open_socket(void)
65 {
66 struct sockaddr_rxrpc srx;
67 struct socket *socket;
68 int ret;
69
70 _enter("");
71
72 skb_queue_head_init(&afs_incoming_calls);
73
74 afs_async_calls = create_singlethread_workqueue("kafsd");
75 if (!afs_async_calls) {
76 _leave(" = -ENOMEM [wq]");
77 return -ENOMEM;
78 }
79
80 ret = sock_create_kern(AF_RXRPC, SOCK_DGRAM, PF_INET, &socket);
81 if (ret < 0) {
82 destroy_workqueue(afs_async_calls);
83 _leave(" = %d [socket]", ret);
84 return ret;
85 }
86
87 socket->sk->sk_allocation = GFP_NOFS;
88
89 /* bind the callback manager's address to make this a server socket */
90 srx.srx_family = AF_RXRPC;
91 srx.srx_service = CM_SERVICE;
92 srx.transport_type = SOCK_DGRAM;
93 srx.transport_len = sizeof(srx.transport.sin);
94 srx.transport.sin.sin_family = AF_INET;
95 srx.transport.sin.sin_port = htons(AFS_CM_PORT);
96 memset(&srx.transport.sin.sin_addr, 0,
97 sizeof(srx.transport.sin.sin_addr));
98
99 ret = kernel_bind(socket, (struct sockaddr *) &srx, sizeof(srx));
100 if (ret < 0) {
101 sock_release(socket);
102 _leave(" = %d [bind]", ret);
103 return ret;
104 }
105
106 rxrpc_kernel_intercept_rx_messages(socket, afs_rx_interceptor);
107
108 afs_socket = socket;
109 _leave(" = 0");
110 return 0;
111 }
112
113 /*
114 * close the RxRPC socket AFS was using
115 */
116 void afs_close_socket(void)
117 {
118 _enter("");
119
120 sock_release(afs_socket);
121
122 _debug("dework");
123 destroy_workqueue(afs_async_calls);
124
125 ASSERTCMP(atomic_read(&afs_outstanding_skbs), ==, 0);
126 ASSERTCMP(atomic_read(&afs_outstanding_calls), ==, 0);
127 _leave("");
128 }
129
130 /*
131 * note that the data in a socket buffer is now delivered and that the buffer
132 * should be freed
133 */
134 static void afs_data_delivered(struct sk_buff *skb)
135 {
136 if (!skb) {
137 _debug("DLVR NULL [%d]", atomic_read(&afs_outstanding_skbs));
138 dump_stack();
139 } else {
140 _debug("DLVR %p{%u} [%d]",
141 skb, skb->mark, atomic_read(&afs_outstanding_skbs));
142 if (atomic_dec_return(&afs_outstanding_skbs) == -1)
143 BUG();
144 rxrpc_kernel_data_delivered(skb);
145 }
146 }
147
148 /*
149 * free a socket buffer
150 */
151 static void afs_free_skb(struct sk_buff *skb)
152 {
153 if (!skb) {
154 _debug("FREE NULL [%d]", atomic_read(&afs_outstanding_skbs));
155 dump_stack();
156 } else {
157 _debug("FREE %p{%u} [%d]",
158 skb, skb->mark, atomic_read(&afs_outstanding_skbs));
159 if (atomic_dec_return(&afs_outstanding_skbs) == -1)
160 BUG();
161 rxrpc_kernel_free_skb(skb);
162 }
163 }
164
165 /*
166 * free a call
167 */
168 static void afs_free_call(struct afs_call *call)
169 {
170 _debug("DONE %p{%s} [%d]",
171 call, call->type->name, atomic_read(&afs_outstanding_calls));
172 if (atomic_dec_return(&afs_outstanding_calls) == -1)
173 BUG();
174
175 ASSERTCMP(call->rxcall, ==, NULL);
176 ASSERT(!work_pending(&call->async_work));
177 ASSERT(skb_queue_empty(&call->rx_queue));
178 ASSERT(call->type->name != NULL);
179
180 kfree(call->request);
181 kfree(call);
182 }
183
184 /*
185 * allocate a call with flat request and reply buffers
186 */
187 struct afs_call *afs_alloc_flat_call(const struct afs_call_type *type,
188 size_t request_size, size_t reply_size)
189 {
190 struct afs_call *call;
191
192 call = kzalloc(sizeof(*call), GFP_NOFS);
193 if (!call)
194 goto nomem_call;
195
196 _debug("CALL %p{%s} [%d]",
197 call, type->name, atomic_read(&afs_outstanding_calls));
198 atomic_inc(&afs_outstanding_calls);
199
200 call->type = type;
201 call->request_size = request_size;
202 call->reply_max = reply_size;
203
204 if (request_size) {
205 call->request = kmalloc(request_size, GFP_NOFS);
206 if (!call->request)
207 goto nomem_free;
208 }
209
210 if (reply_size) {
211 call->buffer = kmalloc(reply_size, GFP_NOFS);
212 if (!call->buffer)
213 goto nomem_free;
214 }
215
216 init_waitqueue_head(&call->waitq);
217 skb_queue_head_init(&call->rx_queue);
218 return call;
219
220 nomem_free:
221 afs_free_call(call);
222 nomem_call:
223 return NULL;
224 }
225
226 /*
227 * clean up a call with flat buffer
228 */
229 void afs_flat_call_destructor(struct afs_call *call)
230 {
231 _enter("");
232
233 kfree(call->request);
234 call->request = NULL;
235 kfree(call->buffer);
236 call->buffer = NULL;
237 }
238
239 /*
240 * initiate a call
241 */
242 int afs_make_call(struct in_addr *addr, struct afs_call *call, gfp_t gfp,
243 const struct afs_wait_mode *wait_mode)
244 {
245 struct sockaddr_rxrpc srx;
246 struct rxrpc_call *rxcall;
247 struct msghdr msg;
248 struct kvec iov[1];
249 int ret;
250
251 _enter("%x,{%d},", addr->s_addr, ntohs(call->port));
252
253 ASSERT(call->type != NULL);
254 ASSERT(call->type->name != NULL);
255
256 _debug("MAKE %p{%s} [%d]",
257 call, call->type->name, atomic_read(&afs_outstanding_calls));
258
259 call->wait_mode = wait_mode;
260 INIT_WORK(&call->async_work, afs_process_async_call);
261
262 memset(&srx, 0, sizeof(srx));
263 srx.srx_family = AF_RXRPC;
264 srx.srx_service = call->service_id;
265 srx.transport_type = SOCK_DGRAM;
266 srx.transport_len = sizeof(srx.transport.sin);
267 srx.transport.sin.sin_family = AF_INET;
268 srx.transport.sin.sin_port = call->port;
269 memcpy(&srx.transport.sin.sin_addr, addr, 4);
270
271 /* create a call */
272 rxcall = rxrpc_kernel_begin_call(afs_socket, &srx, call->key,
273 (unsigned long) call, gfp);
274 call->key = NULL;
275 if (IS_ERR(rxcall)) {
276 ret = PTR_ERR(rxcall);
277 goto error_kill_call;
278 }
279
280 call->rxcall = rxcall;
281
282 /* send the request */
283 iov[0].iov_base = call->request;
284 iov[0].iov_len = call->request_size;
285
286 msg.msg_name = NULL;
287 msg.msg_namelen = 0;
288 msg.msg_iov = (struct iovec *) iov;
289 msg.msg_iovlen = 1;
290 msg.msg_control = NULL;
291 msg.msg_controllen = 0;
292 msg.msg_flags = 0;
293
294 /* have to change the state *before* sending the last packet as RxRPC
295 * might give us the reply before it returns from sending the
296 * request */
297 call->state = AFS_CALL_AWAIT_REPLY;
298 ret = rxrpc_kernel_send_data(rxcall, &msg, call->request_size);
299 if (ret < 0)
300 goto error_do_abort;
301
302 /* at this point, an async call may no longer exist as it may have
303 * already completed */
304 return wait_mode->wait(call);
305
306 error_do_abort:
307 rxrpc_kernel_abort_call(rxcall, RX_USER_ABORT);
308 rxrpc_kernel_end_call(rxcall);
309 call->rxcall = NULL;
310 error_kill_call:
311 call->type->destructor(call);
312 afs_free_call(call);
313 _leave(" = %d", ret);
314 return ret;
315 }
316
317 /*
318 * handles intercepted messages that were arriving in the socket's Rx queue
319 * - called with the socket receive queue lock held to ensure message ordering
320 * - called with softirqs disabled
321 */
322 static void afs_rx_interceptor(struct sock *sk, unsigned long user_call_ID,
323 struct sk_buff *skb)
324 {
325 struct afs_call *call = (struct afs_call *) user_call_ID;
326
327 _enter("%p,,%u", call, skb->mark);
328
329 _debug("ICPT %p{%u} [%d]",
330 skb, skb->mark, atomic_read(&afs_outstanding_skbs));
331
332 ASSERTCMP(sk, ==, afs_socket->sk);
333 atomic_inc(&afs_outstanding_skbs);
334
335 if (!call) {
336 /* its an incoming call for our callback service */
337 skb_queue_tail(&afs_incoming_calls, skb);
338 schedule_work(&afs_collect_incoming_call_work);
339 } else {
340 /* route the messages directly to the appropriate call */
341 skb_queue_tail(&call->rx_queue, skb);
342 call->wait_mode->rx_wakeup(call);
343 }
344
345 _leave("");
346 }
347
348 /*
349 * deliver messages to a call
350 */
351 static void afs_deliver_to_call(struct afs_call *call)
352 {
353 struct sk_buff *skb;
354 bool last;
355 u32 abort_code;
356 int ret;
357
358 _enter("");
359
360 while ((call->state == AFS_CALL_AWAIT_REPLY ||
361 call->state == AFS_CALL_AWAIT_OP_ID ||
362 call->state == AFS_CALL_AWAIT_REQUEST ||
363 call->state == AFS_CALL_AWAIT_ACK) &&
364 (skb = skb_dequeue(&call->rx_queue))) {
365 switch (skb->mark) {
366 case RXRPC_SKB_MARK_DATA:
367 _debug("Rcv DATA");
368 last = rxrpc_kernel_is_data_last(skb);
369 ret = call->type->deliver(call, skb, last);
370 switch (ret) {
371 case 0:
372 if (last &&
373 call->state == AFS_CALL_AWAIT_REPLY)
374 call->state = AFS_CALL_COMPLETE;
375 break;
376 case -ENOTCONN:
377 abort_code = RX_CALL_DEAD;
378 goto do_abort;
379 case -ENOTSUPP:
380 abort_code = RX_INVALID_OPERATION;
381 goto do_abort;
382 default:
383 abort_code = RXGEN_CC_UNMARSHAL;
384 if (call->state != AFS_CALL_AWAIT_REPLY)
385 abort_code = RXGEN_SS_UNMARSHAL;
386 do_abort:
387 rxrpc_kernel_abort_call(call->rxcall,
388 abort_code);
389 call->error = ret;
390 call->state = AFS_CALL_ERROR;
391 break;
392 }
393 afs_data_delivered(skb);
394 skb = NULL;
395 continue;
396 case RXRPC_SKB_MARK_FINAL_ACK:
397 _debug("Rcv ACK");
398 call->state = AFS_CALL_COMPLETE;
399 break;
400 case RXRPC_SKB_MARK_BUSY:
401 _debug("Rcv BUSY");
402 call->error = -EBUSY;
403 call->state = AFS_CALL_BUSY;
404 break;
405 case RXRPC_SKB_MARK_REMOTE_ABORT:
406 abort_code = rxrpc_kernel_get_abort_code(skb);
407 call->error = call->type->abort_to_error(abort_code);
408 call->state = AFS_CALL_ABORTED;
409 _debug("Rcv ABORT %u -> %d", abort_code, call->error);
410 break;
411 case RXRPC_SKB_MARK_NET_ERROR:
412 call->error = -rxrpc_kernel_get_error_number(skb);
413 call->state = AFS_CALL_ERROR;
414 _debug("Rcv NET ERROR %d", call->error);
415 break;
416 case RXRPC_SKB_MARK_LOCAL_ERROR:
417 call->error = -rxrpc_kernel_get_error_number(skb);
418 call->state = AFS_CALL_ERROR;
419 _debug("Rcv LOCAL ERROR %d", call->error);
420 break;
421 default:
422 BUG();
423 break;
424 }
425
426 afs_free_skb(skb);
427 }
428
429 /* make sure the queue is empty if the call is done with (we might have
430 * aborted the call early because of an unmarshalling error) */
431 if (call->state >= AFS_CALL_COMPLETE) {
432 while ((skb = skb_dequeue(&call->rx_queue)))
433 afs_free_skb(skb);
434 if (call->incoming) {
435 rxrpc_kernel_end_call(call->rxcall);
436 call->rxcall = NULL;
437 call->type->destructor(call);
438 afs_free_call(call);
439 }
440 }
441
442 _leave("");
443 }
444
445 /*
446 * wait synchronously for a call to complete
447 */
448 static int afs_wait_for_call_to_complete(struct afs_call *call)
449 {
450 struct sk_buff *skb;
451 int ret;
452
453 DECLARE_WAITQUEUE(myself, current);
454
455 _enter("");
456
457 add_wait_queue(&call->waitq, &myself);
458 for (;;) {
459 set_current_state(TASK_INTERRUPTIBLE);
460
461 /* deliver any messages that are in the queue */
462 if (!skb_queue_empty(&call->rx_queue)) {
463 __set_current_state(TASK_RUNNING);
464 afs_deliver_to_call(call);
465 continue;
466 }
467
468 ret = call->error;
469 if (call->state >= AFS_CALL_COMPLETE)
470 break;
471 ret = -EINTR;
472 if (signal_pending(current))
473 break;
474 schedule();
475 }
476
477 remove_wait_queue(&call->waitq, &myself);
478 __set_current_state(TASK_RUNNING);
479
480 /* kill the call */
481 if (call->state < AFS_CALL_COMPLETE) {
482 _debug("call incomplete");
483 rxrpc_kernel_abort_call(call->rxcall, RX_CALL_DEAD);
484 while ((skb = skb_dequeue(&call->rx_queue)))
485 afs_free_skb(skb);
486 }
487
488 _debug("call complete");
489 rxrpc_kernel_end_call(call->rxcall);
490 call->rxcall = NULL;
491 call->type->destructor(call);
492 afs_free_call(call);
493 _leave(" = %d", ret);
494 return ret;
495 }
496
497 /*
498 * wake up a waiting call
499 */
500 static void afs_wake_up_call_waiter(struct afs_call *call)
501 {
502 wake_up(&call->waitq);
503 }
504
505 /*
506 * wake up an asynchronous call
507 */
508 static void afs_wake_up_async_call(struct afs_call *call)
509 {
510 _enter("");
511 queue_work(afs_async_calls, &call->async_work);
512 }
513
514 /*
515 * put a call into asynchronous mode
516 * - mustn't touch the call descriptor as the call my have completed by the
517 * time we get here
518 */
519 static int afs_dont_wait_for_call_to_complete(struct afs_call *call)
520 {
521 _enter("");
522 return -EINPROGRESS;
523 }
524
525 /*
526 * delete an asynchronous call
527 */
528 static void afs_delete_async_call(struct work_struct *work)
529 {
530 struct afs_call *call =
531 container_of(work, struct afs_call, async_work);
532
533 _enter("");
534
535 afs_free_call(call);
536
537 _leave("");
538 }
539
540 /*
541 * perform processing on an asynchronous call
542 * - on a multiple-thread workqueue this work item may try to run on several
543 * CPUs at the same time
544 */
545 static void afs_process_async_call(struct work_struct *work)
546 {
547 struct afs_call *call =
548 container_of(work, struct afs_call, async_work);
549
550 _enter("");
551
552 if (!skb_queue_empty(&call->rx_queue))
553 afs_deliver_to_call(call);
554
555 if (call->state >= AFS_CALL_COMPLETE && call->wait_mode) {
556 if (call->wait_mode->async_complete)
557 call->wait_mode->async_complete(call->reply,
558 call->error);
559 call->reply = NULL;
560
561 /* kill the call */
562 rxrpc_kernel_end_call(call->rxcall);
563 call->rxcall = NULL;
564 if (call->type->destructor)
565 call->type->destructor(call);
566
567 /* we can't just delete the call because the work item may be
568 * queued */
569 PREPARE_WORK(&call->async_work, afs_delete_async_call);
570 queue_work(afs_async_calls, &call->async_work);
571 }
572
573 _leave("");
574 }
575
576 /*
577 * empty a socket buffer into a flat reply buffer
578 */
579 void afs_transfer_reply(struct afs_call *call, struct sk_buff *skb)
580 {
581 size_t len = skb->len;
582
583 if (skb_copy_bits(skb, 0, call->buffer + call->reply_size, len) < 0)
584 BUG();
585 call->reply_size += len;
586 }
587
588 /*
589 * accept the backlog of incoming calls
590 */
591 static void afs_collect_incoming_call(struct work_struct *work)
592 {
593 struct rxrpc_call *rxcall;
594 struct afs_call *call = NULL;
595 struct sk_buff *skb;
596
597 while ((skb = skb_dequeue(&afs_incoming_calls))) {
598 _debug("new call");
599
600 /* don't need the notification */
601 afs_free_skb(skb);
602
603 if (!call) {
604 call = kzalloc(sizeof(struct afs_call), GFP_KERNEL);
605 if (!call) {
606 rxrpc_kernel_reject_call(afs_socket);
607 return;
608 }
609
610 INIT_WORK(&call->async_work, afs_process_async_call);
611 call->wait_mode = &afs_async_incoming_call;
612 call->type = &afs_RXCMxxxx;
613 init_waitqueue_head(&call->waitq);
614 skb_queue_head_init(&call->rx_queue);
615 call->state = AFS_CALL_AWAIT_OP_ID;
616
617 _debug("CALL %p{%s} [%d]",
618 call, call->type->name,
619 atomic_read(&afs_outstanding_calls));
620 atomic_inc(&afs_outstanding_calls);
621 }
622
623 rxcall = rxrpc_kernel_accept_call(afs_socket,
624 (unsigned long) call);
625 if (!IS_ERR(rxcall)) {
626 call->rxcall = rxcall;
627 call = NULL;
628 }
629 }
630
631 if (call)
632 afs_free_call(call);
633 }
634
635 /*
636 * grab the operation ID from an incoming cache manager call
637 */
638 static int afs_deliver_cm_op_id(struct afs_call *call, struct sk_buff *skb,
639 bool last)
640 {
641 size_t len = skb->len;
642 void *oibuf = (void *) &call->operation_ID;
643
644 _enter("{%u},{%zu},%d", call->offset, len, last);
645
646 ASSERTCMP(call->offset, <, 4);
647
648 /* the operation ID forms the first four bytes of the request data */
649 len = min_t(size_t, len, 4 - call->offset);
650 if (skb_copy_bits(skb, 0, oibuf + call->offset, len) < 0)
651 BUG();
652 if (!pskb_pull(skb, len))
653 BUG();
654 call->offset += len;
655
656 if (call->offset < 4) {
657 if (last) {
658 _leave(" = -EBADMSG [op ID short]");
659 return -EBADMSG;
660 }
661 _leave(" = 0 [incomplete]");
662 return 0;
663 }
664
665 call->state = AFS_CALL_AWAIT_REQUEST;
666
667 /* ask the cache manager to route the call (it'll change the call type
668 * if successful) */
669 if (!afs_cm_incoming_call(call))
670 return -ENOTSUPP;
671
672 /* pass responsibility for the remainer of this message off to the
673 * cache manager op */
674 return call->type->deliver(call, skb, last);
675 }
676
677 /*
678 * send an empty reply
679 */
680 void afs_send_empty_reply(struct afs_call *call)
681 {
682 struct msghdr msg;
683 struct iovec iov[1];
684
685 _enter("");
686
687 iov[0].iov_base = NULL;
688 iov[0].iov_len = 0;
689 msg.msg_name = NULL;
690 msg.msg_namelen = 0;
691 msg.msg_iov = iov;
692 msg.msg_iovlen = 0;
693 msg.msg_control = NULL;
694 msg.msg_controllen = 0;
695 msg.msg_flags = 0;
696
697 call->state = AFS_CALL_AWAIT_ACK;
698 switch (rxrpc_kernel_send_data(call->rxcall, &msg, 0)) {
699 case 0:
700 _leave(" [replied]");
701 return;
702
703 case -ENOMEM:
704 _debug("oom");
705 rxrpc_kernel_abort_call(call->rxcall, RX_USER_ABORT);
706 default:
707 rxrpc_kernel_end_call(call->rxcall);
708 call->rxcall = NULL;
709 call->type->destructor(call);
710 afs_free_call(call);
711 _leave(" [error]");
712 return;
713 }
714 }
715
716 /*
717 * send a simple reply
718 */
719 void afs_send_simple_reply(struct afs_call *call, const void *buf, size_t len)
720 {
721 struct msghdr msg;
722 struct iovec iov[1];
723
724 _enter("");
725
726 iov[0].iov_base = (void *) buf;
727 iov[0].iov_len = len;
728 msg.msg_name = NULL;
729 msg.msg_namelen = 0;
730 msg.msg_iov = iov;
731 msg.msg_iovlen = 1;
732 msg.msg_control = NULL;
733 msg.msg_controllen = 0;
734 msg.msg_flags = 0;
735
736 call->state = AFS_CALL_AWAIT_ACK;
737 switch (rxrpc_kernel_send_data(call->rxcall, &msg, len)) {
738 case 0:
739 _leave(" [replied]");
740 return;
741
742 case -ENOMEM:
743 _debug("oom");
744 rxrpc_kernel_abort_call(call->rxcall, RX_USER_ABORT);
745 default:
746 rxrpc_kernel_end_call(call->rxcall);
747 call->rxcall = NULL;
748 call->type->destructor(call);
749 afs_free_call(call);
750 _leave(" [error]");
751 return;
752 }
753 }
754
755 /*
756 * extract a piece of data from the received data socket buffers
757 */
758 int afs_extract_data(struct afs_call *call, struct sk_buff *skb,
759 bool last, void *buf, size_t count)
760 {
761 size_t len = skb->len;
762
763 _enter("{%u},{%zu},%d,,%zu", call->offset, len, last, count);
764
765 ASSERTCMP(call->offset, <, count);
766
767 len = min_t(size_t, len, count - call->offset);
768 if (skb_copy_bits(skb, 0, buf + call->offset, len) < 0 ||
769 !pskb_pull(skb, len))
770 BUG();
771 call->offset += len;
772
773 if (call->offset < count) {
774 if (last) {
775 _leave(" = -EBADMSG [%d < %lu]", call->offset, count);
776 return -EBADMSG;
777 }
778 _leave(" = -EAGAIN");
779 return -EAGAIN;
780 }
781 return 0;
782 }
kmemtrace - Kernel memory tracer