summaryrefslogtreecommitdiff
path: root/fs/cifs/transport.c
blob: 7efbab013957551c1812f73d833426a537bd99c7 (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
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
/*
 *   fs/cifs/transport.c
 *
 *   Copyright (C) International Business Machines  Corp., 2002,2008
 *   Author(s): Steve French (sfrench@us.ibm.com)
 *   Jeremy Allison (jra@samba.org) 2006.
 *
 *   This library is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU Lesser General Public License as published
 *   by the Free Software Foundation; either version 2.1 of the License, or
 *   (at your option) any later version.
 *
 *   This library is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
 *   the GNU Lesser General Public License for more details.
 *
 *   You should have received a copy of the GNU Lesser General Public License
 *   along with this library; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#include <linux/fs.h>
#include <linux/list.h>
#include <linux/gfp.h>
#include <linux/wait.h>
#include <linux/net.h>
#include <linux/delay.h>
#include <linux/freezer.h>
#include <linux/tcp.h>
#include <linux/bvec.h>
#include <linux/highmem.h>
#include <linux/uaccess.h>
#include <asm/processor.h>
#include <linux/mempool.h>
#include "cifspdu.h"
#include "cifsglob.h"
#include "cifsproto.h"
#include "cifs_debug.h"

void
cifs_wake_up_task(struct mid_q_entry *mid)
{
	wake_up_process(mid->callback_data);
}

struct mid_q_entry *
AllocMidQEntry(const struct smb_hdr *smb_buffer, struct TCP_Server_Info *server)
{
	struct mid_q_entry *temp;

	if (server == NULL) {
		cifs_dbg(VFS, "Null TCP session in AllocMidQEntry\n");
		return NULL;
	}

	temp = mempool_alloc(cifs_mid_poolp, GFP_NOFS);
	memset(temp, 0, sizeof(struct mid_q_entry));
	temp->mid = get_mid(smb_buffer);
	temp->pid = current->pid;
	temp->command = cpu_to_le16(smb_buffer->Command);
	cifs_dbg(FYI, "For smb_command %d\n", smb_buffer->Command);
	/*	do_gettimeofday(&temp->when_sent);*/ /* easier to use jiffies */
	/* when mid allocated can be before when sent */
	temp->when_alloc = jiffies;
	temp->server = server;

	/*
	 * The default is for the mid to be synchronous, so the
	 * default callback just wakes up the current task.
	 */
	temp->callback = cifs_wake_up_task;
	temp->callback_data = current;

	atomic_inc(&midCount);
	temp->mid_state = MID_REQUEST_ALLOCATED;
	return temp;
}

void
DeleteMidQEntry(struct mid_q_entry *midEntry)
{
#ifdef CONFIG_CIFS_STATS2
	__le16 command = midEntry->server->vals->lock_cmd;
	unsigned long now;
#endif
	midEntry->mid_state = MID_FREE;
	atomic_dec(&midCount);
	if (midEntry->large_buf)
		cifs_buf_release(midEntry->resp_buf);
	else
		cifs_small_buf_release(midEntry->resp_buf);
#ifdef CONFIG_CIFS_STATS2
	now = jiffies;
	/* commands taking longer than one second are indications that
	   something is wrong, unless it is quite a slow link or server */
	if (time_after(now, midEntry->when_alloc + HZ)) {
		if ((cifsFYI & CIFS_TIMER) && (midEntry->command != command)) {
			pr_debug(" CIFS slow rsp: cmd %d mid %llu",
			       midEntry->command, midEntry->mid);
			pr_info(" A: 0x%lx S: 0x%lx R: 0x%lx\n",
			       now - midEntry->when_alloc,
			       now - midEntry->when_sent,
			       now - midEntry->when_received);
		}
	}
#endif
	mempool_free(midEntry, cifs_mid_poolp);
}

void
cifs_delete_mid(struct mid_q_entry *mid)
{
	spin_lock(&GlobalMid_Lock);
	list_del(&mid->qhead);
	spin_unlock(&GlobalMid_Lock);

	DeleteMidQEntry(mid);
}

/*
 * smb_send_kvec - send an array of kvecs to the server
 * @server:	Server to send the data to
 * @smb_msg:	Message to send
 * @sent:	amount of data sent on socket is stored here
 *
 * Our basic "send data to server" function. Should be called with srv_mutex
 * held. The caller is responsible for handling the results.
 */
static int
smb_send_kvec(struct TCP_Server_Info *server, struct msghdr *smb_msg,
	      size_t *sent)
{
	int rc = 0;
	int retries = 0;
	struct socket *ssocket = server->ssocket;

	*sent = 0;

	smb_msg->msg_name = (struct sockaddr *) &server->dstaddr;
	smb_msg->msg_namelen = sizeof(struct sockaddr);
	smb_msg->msg_control = NULL;
	smb_msg->msg_controllen = 0;
	if (server->noblocksnd)
		smb_msg->msg_flags = MSG_DONTWAIT + MSG_NOSIGNAL;
	else
		smb_msg->msg_flags = MSG_NOSIGNAL;

	while (msg_data_left(smb_msg)) {
		/*
		 * If blocking send, we try 3 times, since each can block
		 * for 5 seconds. For nonblocking  we have to try more
		 * but wait increasing amounts of time allowing time for
		 * socket to clear.  The overall time we wait in either
		 * case to send on the socket is about 15 seconds.
		 * Similarly we wait for 15 seconds for a response from
		 * the server in SendReceive[2] for the server to send
		 * a response back for most types of requests (except
		 * SMB Write past end of file which can be slow, and
		 * blocking lock operations). NFS waits slightly longer
		 * than CIFS, but this can make it take longer for
		 * nonresponsive servers to be detected and 15 seconds
		 * is more than enough time for modern networks to
		 * send a packet.  In most cases if we fail to send
		 * after the retries we will kill the socket and
		 * reconnect which may clear the network problem.
		 */
		rc = sock_sendmsg(ssocket, smb_msg);
		if (rc == -EAGAIN) {
			retries++;
			if (retries >= 14 ||
			    (!server->noblocksnd && (retries > 2))) {
				cifs_dbg(VFS, "sends on sock %p stuck for 15 seconds\n",
					 ssocket);
				return -EAGAIN;
			}
			msleep(1 << retries);
			continue;
		}

		if (rc < 0)
			return rc;

		if (rc == 0) {
			/* should never happen, letting socket clear before
			   retrying is our only obvious option here */
			cifs_dbg(VFS, "tcp sent no data\n");
			msleep(500);
			continue;
		}

		/* send was at least partially successful */
		*sent += rc;
		retries = 0; /* in case we get ENOSPC on the next send */
	}
	return 0;
}

static unsigned long
rqst_len(struct smb_rqst *rqst)
{
	unsigned int i;
	struct kvec *iov = rqst->rq_iov;
	unsigned long buflen = 0;

	/* total up iov array first */
	for (i = 0; i < rqst->rq_nvec; i++)
		buflen += iov[i].iov_len;

	/* add in the page array if there is one */
	if (rqst->rq_npages) {
		buflen += rqst->rq_pagesz * (rqst->rq_npages - 1);
		buflen += rqst->rq_tailsz;
	}

	return buflen;
}

static int
__smb_send_rqst(struct TCP_Server_Info *server, struct smb_rqst *rqst)
{
	int rc;
	struct kvec *iov = rqst->rq_iov;
	int n_vec = rqst->rq_nvec;
	unsigned int smb_buf_length = get_rfc1002_length(iov[0].iov_base);
	unsigned long send_length;
	unsigned int i;
	size_t total_len = 0, sent, size;
	struct socket *ssocket = server->ssocket;
	struct msghdr smb_msg;
	int val = 1;

	if (ssocket == NULL)
		return -ENOTSOCK;

	/* sanity check send length */
	send_length = rqst_len(rqst);
	if (send_length != smb_buf_length + 4) {
		WARN(1, "Send length mismatch(send_length=%lu smb_buf_length=%u)\n",
			send_length, smb_buf_length);
		return -EIO;
	}

	if (n_vec < 2)
		return -EIO;

	cifs_dbg(FYI, "Sending smb: smb_len=%u\n", smb_buf_length);
	dump_smb(iov[0].iov_base, iov[0].iov_len);
	dump_smb(iov[1].iov_base, iov[1].iov_len);

	/* cork the socket */
	kernel_setsockopt(ssocket, SOL_TCP, TCP_CORK,
				(char *)&val, sizeof(val));

	size = 0;
	for (i = 0; i < n_vec; i++)
		size += iov[i].iov_len;

	iov_iter_kvec(&smb_msg.msg_iter, WRITE | ITER_KVEC, iov, n_vec, size);

	rc = smb_send_kvec(server, &smb_msg, &sent);
	if (rc < 0)
		goto uncork;

	total_len += sent;

	/* now walk the page array and send each page in it */
	for (i = 0; i < rqst->rq_npages; i++) {
		size_t len = i == rqst->rq_npages - 1
				? rqst->rq_tailsz
				: rqst->rq_pagesz;
		struct bio_vec bvec = {
			.bv_page = rqst->rq_pages[i],
			.bv_len = len
		};
		iov_iter_bvec(&smb_msg.msg_iter, WRITE | ITER_BVEC,
			      &bvec, 1, len);
		rc = smb_send_kvec(server, &smb_msg, &sent);
		if (rc < 0)
			break;

		total_len += sent;
	}

uncork:
	/* uncork it */
	val = 0;
	kernel_setsockopt(ssocket, SOL_TCP, TCP_CORK,
				(char *)&val, sizeof(val));

	if ((total_len > 0) && (total_len != smb_buf_length + 4)) {
		cifs_dbg(FYI, "partial send (wanted=%u sent=%zu): terminating session\n",
			 smb_buf_length + 4, total_len);
		/*
		 * If we have only sent part of an SMB then the next SMB could
		 * be taken as the remainder of this one. We need to kill the
		 * socket so the server throws away the partial SMB
		 */
		server->tcpStatus = CifsNeedReconnect;
	}

	if (rc < 0 && rc != -EINTR)
		cifs_dbg(VFS, "Error %d sending data on socket to server\n",
			 rc);
	else
		rc = 0;

	return rc;
}

static int
smb_send_rqst(struct TCP_Server_Info *server, struct smb_rqst *rqst, int flags)
{
	struct smb_rqst cur_rqst;
	int rc;

	if (!(flags & CIFS_TRANSFORM_REQ))
		return __smb_send_rqst(server, rqst);

	if (!server->ops->init_transform_rq ||
	    !server->ops->free_transform_rq) {
		cifs_dbg(VFS, "Encryption requested but transform callbacks are missed\n");
		return -EIO;
	}

	rc = server->ops->init_transform_rq(server, &cur_rqst, rqst);
	if (rc)
		return rc;

	rc = __smb_send_rqst(server, &cur_rqst);
	server->ops->free_transform_rq(&cur_rqst);
	return rc;
}

int
smb_send(struct TCP_Server_Info *server, struct smb_hdr *smb_buffer,
	 unsigned int smb_buf_length)
{
	struct kvec iov[2];
	struct smb_rqst rqst = { .rq_iov = iov,
				 .rq_nvec = 2 };

	iov[0].iov_base = smb_buffer;
	iov[0].iov_len = 4;
	iov[1].iov_base = (char *)smb_buffer + 4;
	iov[1].iov_len = smb_buf_length;

	return __smb_send_rqst(server, &rqst);
}

static int
wait_for_free_credits(struct TCP_Server_Info *server, const int timeout,
		      int *credits)
{
	int rc;

	spin_lock(&server->req_lock);
	if (timeout == CIFS_ASYNC_OP) {
		/* oplock breaks must not be held up */
		server->in_flight++;
		*credits -= 1;
		spin_unlock(&server->req_lock);
		return 0;
	}

	while (1) {
		if (*credits <= 0) {
			spin_unlock(&server->req_lock);
			cifs_num_waiters_inc(server);
			rc = wait_event_killable(server->request_q,
						 has_credits(server, credits));
			cifs_num_waiters_dec(server);
			if (rc)
				return rc;
			spin_lock(&server->req_lock);
		} else {
			if (server->tcpStatus == CifsExiting) {
				spin_unlock(&server->req_lock);
				return -ENOENT;
			}

			/*
			 * Can not count locking commands against total
			 * as they are allowed to block on server.
			 */

			/* update # of requests on the wire to server */
			if (timeout != CIFS_BLOCKING_OP) {
				*credits -= 1;
				server->in_flight++;
			}
			spin_unlock(&server->req_lock);
			break;
		}
	}
	return 0;
}

static int
wait_for_free_request(struct TCP_Server_Info *server, const int timeout,
		      const int optype)
{
	int *val;

	val = server->ops->get_credits_field(server, optype);
	/* Since an echo is already inflight, no need to wait to send another */
	if (*val <= 0 && optype == CIFS_ECHO_OP)
		return -EAGAIN;
	return wait_for_free_credits(server, timeout, val);
}

int
cifs_wait_mtu_credits(struct TCP_Server_Info *server, unsigned int size,
		      unsigned int *num, unsigned int *credits)
{
	*num = size;
	*credits = 0;
	return 0;
}

static int allocate_mid(struct cifs_ses *ses, struct smb_hdr *in_buf,
			struct mid_q_entry **ppmidQ)
{
	if (ses->server->tcpStatus == CifsExiting) {
		return -ENOENT;
	}

	if (ses->server->tcpStatus == CifsNeedReconnect) {
		cifs_dbg(FYI, "tcp session dead - return to caller to retry\n");
		return -EAGAIN;
	}

	if (ses->status == CifsNew) {
		if ((in_buf->Command != SMB_COM_SESSION_SETUP_ANDX) &&
			(in_buf->Command != SMB_COM_NEGOTIATE))
			return -EAGAIN;
		/* else ok - we are setting up session */
	}

	if (ses->status == CifsExiting) {
		/* check if SMB session is bad because we are setting it up */
		if (in_buf->Command != SMB_COM_LOGOFF_ANDX)
			return -EAGAIN;
		/* else ok - we are shutting down session */
	}

	*ppmidQ = AllocMidQEntry(in_buf, ses->server);
	if (*ppmidQ == NULL)
		return -ENOMEM;
	spin_lock(&GlobalMid_Lock);
	list_add_tail(&(*ppmidQ)->qhead, &ses->server->pending_mid_q);
	spin_unlock(&GlobalMid_Lock);
	return 0;
}

static int
wait_for_response(struct TCP_Server_Info *server, struct mid_q_entry *midQ)
{
	int error;

	error = wait_event_freezekillable_unsafe(server->response_q,
				    midQ->mid_state != MID_REQUEST_SUBMITTED);
	if (error < 0)
		return -ERESTARTSYS;

	return 0;
}

struct mid_q_entry *
cifs_setup_async_request(struct TCP_Server_Info *server, struct smb_rqst *rqst)
{
	int rc;
	struct smb_hdr *hdr = (struct smb_hdr *)rqst->rq_iov[0].iov_base;
	struct mid_q_entry *mid;

	if (rqst->rq_iov[0].iov_len != 4 ||
	    rqst->rq_iov[0].iov_base + 4 != rqst->rq_iov[1].iov_base)
		return ERR_PTR(-EIO);

	/* enable signing if server requires it */
	if (server->sign)
		hdr->Flags2 |= SMBFLG2_SECURITY_SIGNATURE;

	mid = AllocMidQEntry(hdr, server);
	if (mid == NULL)
		return ERR_PTR(-ENOMEM);

	rc = cifs_sign_rqst(rqst, server, &mid->sequence_number);
	if (rc) {
		DeleteMidQEntry(mid);
		return ERR_PTR(rc);
	}

	return mid;
}

/*
 * Send a SMB request and set the callback function in the mid to handle
 * the result. Caller is responsible for dealing with timeouts.
 */
int
cifs_call_async(struct TCP_Server_Info *server, struct smb_rqst *rqst,
		mid_receive_t *receive, mid_callback_t *callback,
		mid_handle_t *handle, void *cbdata, const int flags)
{
	int rc, timeout, optype;
	struct mid_q_entry *mid;
	unsigned int credits = 0;

	timeout = flags & CIFS_TIMEOUT_MASK;
	optype = flags & CIFS_OP_MASK;

	if ((flags & CIFS_HAS_CREDITS) == 0) {
		rc = wait_for_free_request(server, timeout, optype);
		if (rc)
			return rc;
		credits = 1;
	}

	mutex_lock(&server->srv_mutex);
	mid = server->ops->setup_async_request(server, rqst);
	if (IS_ERR(mid)) {
		mutex_unlock(&server->srv_mutex);
		add_credits_and_wake_if(server, credits, optype);
		return PTR_ERR(mid);
	}

	mid->receive = receive;
	mid->callback = callback;
	mid->callback_data = cbdata;
	mid->handle = handle;
	mid->mid_state = MID_REQUEST_SUBMITTED;

	/* put it on the pending_mid_q */
	spin_lock(&GlobalMid_Lock);
	list_add_tail(&mid->qhead, &server->pending_mid_q);
	spin_unlock(&GlobalMid_Lock);

	/*
	 * Need to store the time in mid before calling I/O. For call_async,
	 * I/O response may come back and free the mid entry on another thread.
	 */
	cifs_save_when_sent(mid);
	cifs_in_send_inc(server);
	rc = smb_send_rqst(server, rqst, flags);
	cifs_in_send_dec(server);

	if (rc < 0) {
		server->sequence_number -= 2;
		cifs_delete_mid(mid);
	}

	mutex_unlock(&server->srv_mutex);

	if (rc == 0)
		return 0;

	add_credits_and_wake_if(server, credits, optype);
	return rc;
}

/*
 *
 * Send an SMB Request.  No response info (other than return code)
 * needs to be parsed.
 *
 * flags indicate the type of request buffer and how long to wait
 * and whether to log NT STATUS code (error) before mapping it to POSIX error
 *
 */
int
SendReceiveNoRsp(const unsigned int xid, struct cifs_ses *ses,
		 char *in_buf, int flags)
{
	int rc;
	struct kvec iov[1];
	struct kvec rsp_iov;
	int resp_buf_type;

	iov[0].iov_base = in_buf;
	iov[0].iov_len = get_rfc1002_length(in_buf) + 4;
	flags |= CIFS_NO_RESP;
	rc = SendReceive2(xid, ses, iov, 1, &resp_buf_type, flags, &rsp_iov);
	cifs_dbg(NOISY, "SendRcvNoRsp flags %d rc %d\n", flags, rc);

	return rc;
}

static int
cifs_sync_mid_result(struct mid_q_entry *mid, struct TCP_Server_Info *server)
{
	int rc = 0;

	cifs_dbg(FYI, "%s: cmd=%d mid=%llu state=%d\n",
		 __func__, le16_to_cpu(mid->command), mid->mid, mid->mid_state);

	spin_lock(&GlobalMid_Lock);
	switch (mid->mid_state) {
	case MID_RESPONSE_RECEIVED:
		spin_unlock(&GlobalMid_Lock);
		return rc;
	case MID_RETRY_NEEDED:
		rc = -EAGAIN;
		break;
	case MID_RESPONSE_MALFORMED:
		rc = -EIO;
		break;
	case MID_SHUTDOWN:
		rc = -EHOSTDOWN;
		break;
	default:
		list_del_init(&mid->qhead);
		cifs_dbg(VFS, "%s: invalid mid state mid=%llu state=%d\n",
			 __func__, mid->mid, mid->mid_state);
		rc = -EIO;
	}
	spin_unlock(&GlobalMid_Lock);

	DeleteMidQEntry(mid);
	return rc;
}

static inline int
send_cancel(struct TCP_Server_Info *server, struct smb_rqst *rqst,
	    struct mid_q_entry *mid)
{
	return server->ops->send_cancel ?
				server->ops->send_cancel(server, rqst, mid) : 0;
}

int
cifs_check_receive(struct mid_q_entry *mid, struct TCP_Server_Info *server,
		   bool log_error)
{
	unsigned int len = get_rfc1002_length(mid->resp_buf) + 4;

	dump_smb(mid->resp_buf, min_t(u32, 92, len));

	/* convert the length into a more usable form */
	if (server->sign) {
		struct kvec iov[2];
		int rc = 0;
		struct smb_rqst rqst = { .rq_iov = iov,
					 .rq_nvec = 2 };

		iov[0].iov_base = mid->resp_buf;
		iov[0].iov_len = 4;
		iov[1].iov_base = (char *)mid->resp_buf + 4;
		iov[1].iov_len = len - 4;
		/* FIXME: add code to kill session */
		rc = cifs_verify_signature(&rqst, server,
					   mid->sequence_number);
		if (rc)
			cifs_dbg(VFS, "SMB signature verification returned error = %d\n",
				 rc);
	}

	/* BB special case reconnect tid and uid here? */
	return map_smb_to_linux_error(mid->resp_buf, log_error);
}

struct mid_q_entry *
cifs_setup_request(struct cifs_ses *ses, struct smb_rqst *rqst)
{
	int rc;
	struct smb_hdr *hdr = (struct smb_hdr *)rqst->rq_iov[0].iov_base;
	struct mid_q_entry *mid;

	if (rqst->rq_iov[0].iov_len != 4 ||
	    rqst->rq_iov[0].iov_base + 4 != rqst->rq_iov[1].iov_base)
		return ERR_PTR(-EIO);

	rc = allocate_mid(ses, hdr, &mid);
	if (rc)
		return ERR_PTR(rc);
	rc = cifs_sign_rqst(rqst, ses->server, &mid->sequence_number);
	if (rc) {
		cifs_delete_mid(mid);
		return ERR_PTR(rc);
	}
	return mid;
}

int
cifs_send_recv(const unsigned int xid, struct cifs_ses *ses,
	       struct smb_rqst *rqst, int *resp_buf_type, const int flags,
	       struct kvec *resp_iov)
{
	int rc = 0;
	int timeout, optype;
	struct mid_q_entry *midQ;
	unsigned int credits = 1;
	char *buf;

	timeout = flags & CIFS_TIMEOUT_MASK;
	optype = flags & CIFS_OP_MASK;

	*resp_buf_type = CIFS_NO_BUFFER;  /* no response buf yet */

	if ((ses == NULL) || (ses->server == NULL)) {
		cifs_dbg(VFS, "Null session\n");
		return -EIO;
	}

	if (ses->server->tcpStatus == CifsExiting)
		return -ENOENT;

	/*
	 * Ensure that we do not send more than 50 overlapping requests
	 * to the same server. We may make this configurable later or
	 * use ses->maxReq.
	 */

	rc = wait_for_free_request(ses->server, timeout, optype);
	if (rc)
		return rc;

	/*
	 * Make sure that we sign in the same order that we send on this socket
	 * and avoid races inside tcp sendmsg code that could cause corruption
	 * of smb data.
	 */

	mutex_lock(&ses->server->srv_mutex);

	midQ = ses->server->ops->setup_request(ses, rqst);
	if (IS_ERR(midQ)) {
		mutex_unlock(&ses->server->srv_mutex);
		/* Update # of requests on wire to server */
		add_credits(ses->server, 1, optype);
		return PTR_ERR(midQ);
	}

	midQ->mid_state = MID_REQUEST_SUBMITTED;
	cifs_in_send_inc(ses->server);
	rc = smb_send_rqst(ses->server, rqst, flags);
	cifs_in_send_dec(ses->server);
	cifs_save_when_sent(midQ);

	if (rc < 0)
		ses->server->sequence_number -= 2;
	mutex_unlock(&ses->server->srv_mutex);

	if (rc < 0)
		goto out;

	if (timeout == CIFS_ASYNC_OP)
		goto out;

	rc = wait_for_response(ses->server, midQ);
	if (rc != 0) {
		cifs_dbg(FYI, "Cancelling wait for mid %llu\n",	midQ->mid);
		send_cancel(ses->server, rqst, midQ);
		spin_lock(&GlobalMid_Lock);
		if (midQ->mid_state == MID_REQUEST_SUBMITTED) {
			midQ->mid_flags |= MID_WAIT_CANCELLED;
			midQ->callback = DeleteMidQEntry;
			spin_unlock(&GlobalMid_Lock);
			add_credits(ses->server, 1, optype);
			return rc;
		}
		spin_unlock(&GlobalMid_Lock);
	}

	rc = cifs_sync_mid_result(midQ, ses->server);
	if (rc != 0) {
		add_credits(ses->server, 1, optype);
		return rc;
	}

	if (!midQ->resp_buf || midQ->mid_state != MID_RESPONSE_RECEIVED) {
		rc = -EIO;
		cifs_dbg(FYI, "Bad MID state?\n");
		goto out;
	}

	buf = (char *)midQ->resp_buf;
	resp_iov->iov_base = buf;
	resp_iov->iov_len = get_rfc1002_length(buf) + 4;
	if (midQ->large_buf)
		*resp_buf_type = CIFS_LARGE_BUFFER;
	else
		*resp_buf_type = CIFS_SMALL_BUFFER;

	credits = ses->server->ops->get_credits(midQ);

	rc = ses->server->ops->check_receive(midQ, ses->server,
					     flags & CIFS_LOG_ERROR);

	/* mark it so buf will not be freed by cifs_delete_mid */
	if ((flags & CIFS_NO_RESP) == 0)
		midQ->resp_buf = NULL;
out:
	cifs_delete_mid(midQ);
	add_credits(ses->server, credits, optype);

	return rc;
}

int
SendReceive2(const unsigned int xid, struct cifs_ses *ses,
	     struct kvec *iov, int n_vec, int *resp_buf_type /* ret */,
	     const int flags, struct kvec *resp_iov)
{
	struct smb_rqst rqst;
	struct kvec *new_iov;
	int rc;

	new_iov = kmalloc(sizeof(struct kvec) * (n_vec + 1), GFP_KERNEL);
	if (!new_iov)
		return -ENOMEM;

	/* 1st iov is a RFC1001 length followed by the rest of the packet */
	memcpy(new_iov + 1, iov, (sizeof(struct kvec) * n_vec));

	new_iov[0].iov_base = new_iov[1].iov_base;
	new_iov[0].iov_len = 4;
	new_iov[1].iov_base += 4;
	new_iov[1].iov_len -= 4;

	memset(&rqst, 0, sizeof(struct smb_rqst));
	rqst.rq_iov = new_iov;
	rqst.rq_nvec = n_vec + 1;

	rc = cifs_send_recv(xid, ses, &rqst, resp_buf_type, flags, resp_iov);
	kfree(new_iov);
	return rc;
}

int
SendReceive(const unsigned int xid, struct cifs_ses *ses,
	    struct smb_hdr *in_buf, struct smb_hdr *out_buf,
	    int *pbytes_returned, const int timeout)
{
	int rc = 0;
	struct mid_q_entry *midQ;
	unsigned int len = be32_to_cpu(in_buf->smb_buf_length);
	struct kvec iov = { .iov_base = in_buf, .iov_len = len };
	struct smb_rqst rqst = { .rq_iov = &iov, .rq_nvec = 1 };

	if (ses == NULL) {
		cifs_dbg(VFS, "Null smb session\n");
		return -EIO;
	}
	if (ses->server == NULL) {
		cifs_dbg(VFS, "Null tcp session\n");
		return -EIO;
	}

	if (ses->server->tcpStatus == CifsExiting)
		return -ENOENT;

	/* Ensure that we do not send more than 50 overlapping requests
	   to the same server. We may make this configurable later or
	   use ses->maxReq */

	if (len > CIFSMaxBufSize + MAX_CIFS_HDR_SIZE - 4) {
		cifs_dbg(VFS, "Illegal length, greater than maximum frame, %d\n",
			 len);
		return -EIO;
	}

	rc = wait_for_free_request(ses->server, timeout, 0);
	if (rc)
		return rc;

	/* make sure that we sign in the same order that we send on this socket
	   and avoid races inside tcp sendmsg code that could cause corruption
	   of smb data */

	mutex_lock(&ses->server->srv_mutex);

	rc = allocate_mid(ses, in_buf, &midQ);
	if (rc) {
		mutex_unlock(&ses->server->srv_mutex);
		/* Update # of requests on wire to server */
		add_credits(ses->server, 1, 0);
		return rc;
	}

	rc = cifs_sign_smb(in_buf, ses->server, &midQ->sequence_number);
	if (rc) {
		mutex_unlock(&ses->server->srv_mutex);
		goto out;
	}

	midQ->mid_state = MID_REQUEST_SUBMITTED;

	cifs_in_send_inc(ses->server);
	rc = smb_send(ses->server, in_buf, len);
	cifs_in_send_dec(ses->server);
	cifs_save_when_sent(midQ);

	if (rc < 0)
		ses->server->sequence_number -= 2;

	mutex_unlock(&ses->server->srv_mutex);

	if (rc < 0)
		goto out;

	if (timeout == CIFS_ASYNC_OP)
		goto out;

	rc = wait_for_response(ses->server, midQ);
	if (rc != 0) {
		send_cancel(ses->server, &rqst, midQ);
		spin_lock(&GlobalMid_Lock);
		if (midQ->mid_state == MID_REQUEST_SUBMITTED) {
			/* no longer considered to be "in-flight" */
			midQ->callback = DeleteMidQEntry;
			spin_unlock(&GlobalMid_Lock);
			add_credits(ses->server, 1, 0);
			return rc;
		}
		spin_unlock(&GlobalMid_Lock);
	}

	rc = cifs_sync_mid_result(midQ, ses->server);
	if (rc != 0) {
		add_credits(ses->server, 1, 0);
		return rc;
	}

	if (!midQ->resp_buf || !out_buf ||
	    midQ->mid_state != MID_RESPONSE_RECEIVED) {
		rc = -EIO;
		cifs_dbg(VFS, "Bad MID state?\n");
		goto out;
	}

	*pbytes_returned = get_rfc1002_length(midQ->resp_buf);
	memcpy(out_buf, midQ->resp_buf, *pbytes_returned + 4);
	rc = cifs_check_receive(midQ, ses->server, 0);
out:
	cifs_delete_mid(midQ);
	add_credits(ses->server, 1, 0);

	return rc;
}

/* We send a LOCKINGX_CANCEL_LOCK to cause the Windows
   blocking lock to return. */

static int
send_lock_cancel(const unsigned int xid, struct cifs_tcon *tcon,
			struct smb_hdr *in_buf,
			struct smb_hdr *out_buf)
{
	int bytes_returned;
	struct cifs_ses *ses = tcon->ses;
	LOCK_REQ *pSMB = (LOCK_REQ *)in_buf;

	/* We just modify the current in_buf to change
	   the type of lock from LOCKING_ANDX_SHARED_LOCK
	   or LOCKING_ANDX_EXCLUSIVE_LOCK to
	   LOCKING_ANDX_CANCEL_LOCK. */

	pSMB->LockType = LOCKING_ANDX_CANCEL_LOCK|LOCKING_ANDX_LARGE_FILES;
	pSMB->Timeout = 0;
	pSMB->hdr.Mid = get_next_mid(ses->server);

	return SendReceive(xid, ses, in_buf, out_buf,
			&bytes_returned, 0);
}

int
SendReceiveBlockingLock(const unsigned int xid, struct cifs_tcon *tcon,
	    struct smb_hdr *in_buf, struct smb_hdr *out_buf,
	    int *pbytes_returned)
{
	int rc = 0;
	int rstart = 0;
	struct mid_q_entry *midQ;
	struct cifs_ses *ses;
	unsigned int len = be32_to_cpu(in_buf->smb_buf_length);
	struct kvec iov = { .iov_base = in_buf, .iov_len = len };
	struct smb_rqst rqst = { .rq_iov = &iov, .rq_nvec = 1 };

	if (tcon == NULL || tcon->ses == NULL) {
		cifs_dbg(VFS, "Null smb session\n");
		return -EIO;
	}
	ses = tcon->ses;

	if (ses->server == NULL) {
		cifs_dbg(VFS, "Null tcp session\n");
		return -EIO;
	}

	if (ses->server->tcpStatus == CifsExiting)
		return -ENOENT;

	/* Ensure that we do not send more than 50 overlapping requests
	   to the same server. We may make this configurable later or
	   use ses->maxReq */

	if (len > CIFSMaxBufSize + MAX_CIFS_HDR_SIZE - 4) {
		cifs_dbg(VFS, "Illegal length, greater than maximum frame, %d\n",
			 len);
		return -EIO;
	}

	rc = wait_for_free_request(ses->server, CIFS_BLOCKING_OP, 0);
	if (rc)
		return rc;

	/* make sure that we sign in the same order that we send on this socket
	   and avoid races inside tcp sendmsg code that could cause corruption
	   of smb data */

	mutex_lock(&ses->server->srv_mutex);

	rc = allocate_mid(ses, in_buf, &midQ);
	if (rc) {
		mutex_unlock(&ses->server->srv_mutex);
		return rc;
	}

	rc = cifs_sign_smb(in_buf, ses->server, &midQ->sequence_number);
	if (rc) {
		cifs_delete_mid(midQ);
		mutex_unlock(&ses->server->srv_mutex);
		return rc;
	}

	midQ->mid_state = MID_REQUEST_SUBMITTED;
	cifs_in_send_inc(ses->server);
	rc = smb_send(ses->server, in_buf, len);
	cifs_in_send_dec(ses->server);
	cifs_save_when_sent(midQ);

	if (rc < 0)
		ses->server->sequence_number -= 2;

	mutex_unlock(&ses->server->srv_mutex);

	if (rc < 0) {
		cifs_delete_mid(midQ);
		return rc;
	}

	/* Wait for a reply - allow signals to interrupt. */
	rc = wait_event_interruptible(ses->server->response_q,
		(!(midQ->mid_state == MID_REQUEST_SUBMITTED)) ||
		((ses->server->tcpStatus != CifsGood) &&
		 (ses->server->tcpStatus != CifsNew)));

	/* Were we interrupted by a signal ? */
	if ((rc == -ERESTARTSYS) &&
		(midQ->mid_state == MID_REQUEST_SUBMITTED) &&
		((ses->server->tcpStatus == CifsGood) ||
		 (ses->server->tcpStatus == CifsNew))) {

		if (in_buf->Command == SMB_COM_TRANSACTION2) {
			/* POSIX lock. We send a NT_CANCEL SMB to cause the
			   blocking lock to return. */
			rc = send_cancel(ses->server, &rqst, midQ);
			if (rc) {
				cifs_delete_mid(midQ);
				return rc;
			}
		} else {
			/* Windows lock. We send a LOCKINGX_CANCEL_LOCK
			   to cause the blocking lock to return. */

			rc = send_lock_cancel(xid, tcon, in_buf, out_buf);

			/* If we get -ENOLCK back the lock may have
			   already been removed. Don't exit in this case. */
			if (rc && rc != -ENOLCK) {
				cifs_delete_mid(midQ);
				return rc;
			}
		}

		rc = wait_for_response(ses->server, midQ);
		if (rc) {
			send_cancel(ses->server, &rqst, midQ);
			spin_lock(&GlobalMid_Lock);
			if (midQ->mid_state == MID_REQUEST_SUBMITTED) {
				/* no longer considered to be "in-flight" */
				midQ->callback = DeleteMidQEntry;
				spin_unlock(&GlobalMid_Lock);
				return rc;
			}
			spin_unlock(&GlobalMid_Lock);
		}

		/* We got the response - restart system call. */
		rstart = 1;
	}

	rc = cifs_sync_mid_result(midQ, ses->server);
	if (rc != 0)
		return rc;

	/* rcvd frame is ok */
	if (out_buf == NULL || midQ->mid_state != MID_RESPONSE_RECEIVED) {
		rc = -EIO;
		cifs_dbg(VFS, "Bad MID state?\n");
		goto out;
	}

	*pbytes_returned = get_rfc1002_length(midQ->resp_buf);
	memcpy(out_buf, midQ->resp_buf, *pbytes_returned + 4);
	rc = cifs_check_receive(midQ, ses->server, 0);
out:
	cifs_delete_mid(midQ);
	if (rstart && rc == -EACCES)
		return -ERESTARTSYS;
	return rc;
}