summaryrefslogtreecommitdiff
path: root/drivers/staging/pohmelfs/net.c
blob: d161237f73a9656cd238aacef90fffdba8dd87fa (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
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
/*
 * 2007+ Copyright (c) Evgeniy Polyakov <zbr@ioremap.net>
 * All rights reserved.
 *
 * 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.
 *
 * This program 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 General Public License for more details.
 */

#include <linux/fsnotify.h>
#include <linux/jhash.h>
#include <linux/in.h>
#include <linux/in6.h>
#include <linux/kthread.h>
#include <linux/pagemap.h>
#include <linux/poll.h>
#include <linux/swap.h>
#include <linux/syscalls.h>

#include "netfs.h"

static int pohmelfs_ftrans_size = 10240;
static u32 *pohmelfs_ftrans;

int pohmelfs_ftrans_init(void)
{
	pohmelfs_ftrans = vmalloc(pohmelfs_ftrans_size * 4);
	if (!pohmelfs_ftrans)
		return -ENOMEM;

	return 0;
}

void pohmelfs_ftrans_exit(void)
{
	vfree(pohmelfs_ftrans);
}

void pohmelfs_ftrans_clean(u64 id)
{
	if (pohmelfs_ftrans) {
		u32 i = id & 0xffffffff;
		int idx = i % pohmelfs_ftrans_size;

		pohmelfs_ftrans[idx] = 0;
	}
}

void pohmelfs_ftrans_update(u64 id)
{
	if (pohmelfs_ftrans) {
		u32 i = id & 0xffffffff;
		int idx = i % pohmelfs_ftrans_size;

		pohmelfs_ftrans[idx] = i;
	}
}

int pohmelfs_ftrans_check(u64 id)
{
	if (pohmelfs_ftrans) {
		u32 i = id & 0xffffffff;
		int idx = i % pohmelfs_ftrans_size;

		return (pohmelfs_ftrans[idx] == i);
	}

	return -1;
}

/*
 * Async machinery lives here.
 * All commands being sent to server do _not_ require sync reply,
 * instead, if it is really needed, like readdir or readpage, caller
 * sleeps waiting for data, which will be placed into provided buffer
 * and caller will be awakened.
 *
 * Every command response can come without some listener. For example
 * readdir response will add new objects into cache without appropriate
 * request from userspace. This is used in cache coherency.
 *
 * If object is not found for given data, it is discarded.
 *
 * All requests are received by dedicated kernel thread.
 */

/*
 * Basic network sending/receiving functions.
 * Blocked mode is used.
 */
static int netfs_data_recv(struct netfs_state *st, void *buf, u64 size)
{
	struct msghdr msg;
	struct kvec iov;
	int err;

	BUG_ON(!size);

	iov.iov_base = buf;
	iov.iov_len = size;

	msg.msg_iov = (struct iovec *)&iov;
	msg.msg_iovlen = 1;
	msg.msg_name = NULL;
	msg.msg_namelen = 0;
	msg.msg_control = NULL;
	msg.msg_controllen = 0;
	msg.msg_flags = MSG_DONTWAIT;

	err = kernel_recvmsg(st->socket, &msg, &iov, 1, iov.iov_len,
			msg.msg_flags);
	if (err <= 0) {
		printk("%s: failed to recv data: size: %llu, err: %d.\n", __func__, size, err);
		if (err == 0)
			err = -ECONNRESET;
	}

	return err;
}

static int pohmelfs_data_recv(struct netfs_state *st, void *data, unsigned int size)
{
	unsigned int revents = 0;
	unsigned int err_mask = POLLERR | POLLHUP | POLLRDHUP;
	unsigned int mask = err_mask | POLLIN;
	int err = 0;

	while (size && !err) {
		revents = netfs_state_poll(st);

		if (!(revents & mask)) {
			DEFINE_WAIT(wait);

			for (;;) {
				prepare_to_wait(&st->thread_wait, &wait, TASK_INTERRUPTIBLE);
				if (kthread_should_stop())
					break;

				revents = netfs_state_poll(st);

				if (revents & mask)
					break;

				if (signal_pending(current))
					break;

				schedule();
				continue;
			}
			finish_wait(&st->thread_wait, &wait);
		}

		err = 0;
		netfs_state_lock(st);
		if (st->socket && (st->read_socket == st->socket) && (revents & POLLIN)) {
			err = netfs_data_recv(st, data, size);
			if (err > 0) {
				data += err;
				size -= err;
				err = 0;
			} else if (err == 0)
				err = -ECONNRESET;
		}

		if (revents & err_mask) {
			printk("%s: revents: %x, socket: %p, size: %u, err: %d.\n",
					__func__, revents, st->socket, size, err);
			err = -ECONNRESET;
		}
		netfs_state_unlock(st);

		if (err < 0) {
			if (netfs_state_trylock_send(st)) {
				netfs_state_exit(st);
				err = netfs_state_init(st);
				if (!err)
					err = -EAGAIN;
				netfs_state_unlock_send(st);
			} else {
				st->need_reset = 1;
			}
		}

		if (kthread_should_stop())
			err = -ENODEV;

		if (err)
			printk("%s: socket: %p, read_socket: %p, revents: %x, rev_error: %d, "
					"should_stop: %d, size: %u, err: %d.\n",
				__func__, st->socket, st->read_socket,
				revents, revents & err_mask, kthread_should_stop(), size, err);
	}

	return err;
}

int pohmelfs_data_recv_and_check(struct netfs_state *st, void *data, unsigned int size)
{
	struct netfs_cmd *cmd = &st->cmd;
	int err;

	err = pohmelfs_data_recv(st, data, size);
	if (err)
		return err;

	return pohmelfs_crypto_process_input_data(&st->eng, cmd->iv, data, NULL, size);
}

/*
 * Polling machinery.
 */

struct netfs_poll_helper
{
	poll_table 		pt;
	struct netfs_state	*st;
};

static int netfs_queue_wake(wait_queue_t *wait, unsigned mode, int sync, void *key)
{
	struct netfs_state *st = container_of(wait, struct netfs_state, wait);

	wake_up(&st->thread_wait);
	return 1;
}

static void netfs_queue_func(struct file *file, wait_queue_head_t *whead,
				 poll_table *pt)
{
	struct netfs_state *st = container_of(pt, struct netfs_poll_helper, pt)->st;

	st->whead = whead;
	init_waitqueue_func_entry(&st->wait, netfs_queue_wake);
	add_wait_queue(whead, &st->wait);
}

static void netfs_poll_exit(struct netfs_state *st)
{
	if (st->whead) {
		remove_wait_queue(st->whead, &st->wait);
		st->whead = NULL;
	}
}

static int netfs_poll_init(struct netfs_state *st)
{
	struct netfs_poll_helper ph;

	ph.st = st;
	init_poll_funcptr(&ph.pt, &netfs_queue_func);

	st->socket->ops->poll(NULL, st->socket, &ph.pt);
	return 0;
}

/*
 * Get response for readpage command. We search inode and page in its mapping
 * and copy data into. If it was async request, then we queue page into shared
 * data and wakeup listener, who will copy it to userspace.
 *
 * There is a work in progress of allowing to call copy_to_user() directly from
 * async receiving kernel thread.
 */
static int pohmelfs_read_page_response(struct netfs_state *st)
{
	struct pohmelfs_sb *psb = st->psb;
	struct netfs_cmd *cmd = &st->cmd;
	struct inode *inode;
	struct page *page;
	int err = 0;

	if (cmd->size > PAGE_CACHE_SIZE) {
		err = -EINVAL;
		goto err_out_exit;
	}

	inode = ilookup(st->psb->sb, cmd->id);
	if (!inode) {
		printk("%s: failed to find inode: id: %llu.\n", __func__, cmd->id);
		err = -ENOENT;
		goto err_out_exit;
	}

	page = find_get_page(inode->i_mapping, cmd->start >> PAGE_CACHE_SHIFT);
	if (!page || !PageLocked(page)) {
		printk("%s: failed to find/lock page: page: %p, id: %llu, start: %llu, index: %llu.\n",
				__func__, page, cmd->id, cmd->start, cmd->start >> PAGE_CACHE_SHIFT);

		while (cmd->size) {
			unsigned int sz = min(cmd->size, st->size);

			err = pohmelfs_data_recv(st, st->data, sz);
			if (err)
				break;

			cmd->size -= sz;
		}

		err = -ENODEV;
		if (page)
			goto err_out_page_put;
		goto err_out_put;
	}

	if (cmd->size) {
		void *addr;

		addr = kmap(page);
		err = pohmelfs_data_recv(st, addr, cmd->size);
		kunmap(page);

		if (err)
			goto err_out_page_unlock;
	}

	dprintk("%s: page: %p, start: %llu, size: %u, locked: %d.\n",
		__func__, page, cmd->start, cmd->size, PageLocked(page));

	SetPageChecked(page);
	if ((psb->hash_string || psb->cipher_string) && psb->perform_crypto && cmd->size) {
		err = pohmelfs_crypto_process_input_page(&st->eng, page, cmd->size, cmd->iv);
		if (err < 0)
			goto err_out_page_unlock;
	} else {
		SetPageUptodate(page);
		unlock_page(page);
		page_cache_release(page);
	}

	pohmelfs_put_inode(POHMELFS_I(inode));
	wake_up(&st->psb->wait);

	return 0;

err_out_page_unlock:
	SetPageError(page);
	unlock_page(page);
err_out_page_put:
	page_cache_release(page);
err_out_put:
	pohmelfs_put_inode(POHMELFS_I(inode));
err_out_exit:
	wake_up(&st->psb->wait);
	return err;
}

static int pohmelfs_check_name(struct pohmelfs_inode *parent, struct qstr *str,
		struct netfs_inode_info *info)
{
	struct inode *inode;
	struct pohmelfs_name *n;
	int err = 0;
	u64 ino = 0;

	mutex_lock(&parent->offset_lock);
	n = pohmelfs_search_hash(parent, str->hash);
	if (n)
		ino = n->ino;
	mutex_unlock(&parent->offset_lock);

	if (!ino)
		goto out;

	inode = ilookup(parent->vfs_inode.i_sb, ino);
	if (!inode)
		goto out;

	dprintk("%s: parent: %llu, inode: %llu.\n", __func__, parent->ino, ino);

	pohmelfs_fill_inode(inode, info);
	pohmelfs_put_inode(POHMELFS_I(inode));
	err = -EEXIST;
out:
	return err;
}

/*
 * Readdir response from server. If special field is set, we wakeup
 * listener (readdir() call), which will copy data to userspace.
 */
static int pohmelfs_readdir_response(struct netfs_state *st)
{
	struct inode *inode;
	struct netfs_cmd *cmd = &st->cmd;
	struct netfs_inode_info *info;
	struct pohmelfs_inode *parent = NULL, *npi;
	int err = 0, last = cmd->ext;
	struct qstr str;

	if (cmd->size > st->size)
		return -EINVAL;

	inode = ilookup(st->psb->sb, cmd->id);
	if (!inode) {
		printk("%s: failed to find inode: id: %llu.\n", __func__, cmd->id);
		return -ENOENT;
	}
	parent = POHMELFS_I(inode);

	if (!cmd->size && cmd->start) {
		err = -cmd->start;
		goto out;
	}

	if (cmd->size) {
		char *name;

		err = pohmelfs_data_recv_and_check(st, st->data, cmd->size);
		if (err)
			goto err_out_put;

		info = (struct netfs_inode_info *)(st->data);

		name = (char *)(info + 1);
		str.len = cmd->size - sizeof(struct netfs_inode_info) - 1 - cmd->cpad;
		name[str.len] = 0;
		str.name = name;
		str.hash = jhash(str.name, str.len, 0);

		netfs_convert_inode_info(info);

		if (parent) {
			err = pohmelfs_check_name(parent, &str, info);
			if (err) {
				if (err == -EEXIST)
					err = 0;
				goto out;
			}
		}

		info->ino = cmd->start;
		if (!info->ino)
			info->ino = pohmelfs_new_ino(st->psb);

		dprintk("%s: parent: %llu, ino: %llu, name: '%s', hash: %x, len: %u, mode: %o.\n",
				__func__, parent->ino, info->ino, str.name, str.hash, str.len,
				info->mode);

		npi = pohmelfs_new_inode(st->psb, parent, &str, info, 0);
		if (IS_ERR(npi)) {
			err = PTR_ERR(npi);

			if (err != -EEXIST)
				goto err_out_put;
		} else {
			set_bit(NETFS_INODE_REMOTE_SYNCED, &npi->state);
			clear_bit(NETFS_INODE_OWNED, &npi->state);
		}
	}
out:
	if (last) {
		set_bit(NETFS_INODE_REMOTE_DIR_SYNCED, &parent->state);
		set_bit(NETFS_INODE_REMOTE_SYNCED, &parent->state);
		wake_up(&st->psb->wait);
	}
	pohmelfs_put_inode(parent);

	return err;

err_out_put:
	clear_bit(NETFS_INODE_REMOTE_DIR_SYNCED, &parent->state);
	printk("%s: parent: %llu, ino: %llu, cmd_id: %llu.\n", __func__, parent->ino, cmd->start, cmd->id);
	pohmelfs_put_inode(parent);
	wake_up(&st->psb->wait);
	return err;
}

/*
 * Lookup command response.
 * It searches for inode to be looked at (if it exists) and substitutes
 * its inode information (size, permission, mode and so on), if inode does
 * not exist, new one will be created and inserted into caches.
 */
static int pohmelfs_lookup_response(struct netfs_state *st)
{
	struct inode *inode = NULL;
	struct netfs_cmd *cmd = &st->cmd;
	struct netfs_inode_info *info;
	struct pohmelfs_inode *parent = NULL, *npi;
	int err = -EINVAL;
	char *name;

	inode = ilookup(st->psb->sb, cmd->id);
	if (!inode) {
		printk("%s: lookup response: id: %llu, start: %llu, size: %u.\n",
				__func__, cmd->id, cmd->start, cmd->size);
		err = -ENOENT;
		goto err_out_exit;
	}
	parent = POHMELFS_I(inode);

	if (!cmd->size) {
		err = -cmd->start;
		goto err_out_put;
	}

	if (cmd->size < sizeof(struct netfs_inode_info)) {
		printk("%s: broken lookup response: id: %llu, start: %llu, size: %u.\n",
				__func__, cmd->id, cmd->start, cmd->size);
		err = -EINVAL;
		goto err_out_put;
	}

	err = pohmelfs_data_recv_and_check(st, st->data, cmd->size);
	if (err)
		goto err_out_put;

	info = (struct netfs_inode_info *)(st->data);
	name = (char *)(info + 1);

	netfs_convert_inode_info(info);

	info->ino = cmd->start;
	if (!info->ino)
		info->ino = pohmelfs_new_ino(st->psb);

	dprintk("%s: parent: %llu, ino: %llu, name: '%s', start: %llu.\n",
			__func__, parent->ino, info->ino, name, cmd->start);

	if (cmd->start)
		npi = pohmelfs_new_inode(st->psb, parent, NULL, info, 0);
	else {
		struct qstr str;

		str.name = name;
		str.len = cmd->size - sizeof(struct netfs_inode_info) - 1 - cmd->cpad;
		str.hash = jhash(name, str.len, 0);

		npi = pohmelfs_new_inode(st->psb, parent, &str, info, 0);
	}
	if (IS_ERR(npi)) {
		err = PTR_ERR(npi);

		if (err != -EEXIST)
			goto err_out_put;
	} else {
		set_bit(NETFS_INODE_REMOTE_SYNCED, &npi->state);
		clear_bit(NETFS_INODE_OWNED, &npi->state);
	}

	clear_bit(NETFS_COMMAND_PENDING, &parent->state);
	pohmelfs_put_inode(parent);

	wake_up(&st->psb->wait);

	return 0;

err_out_put:
	pohmelfs_put_inode(parent);
err_out_exit:
	clear_bit(NETFS_COMMAND_PENDING, &parent->state);
	wake_up(&st->psb->wait);
	printk("%s: inode: %p, id: %llu, start: %llu, size: %u, err: %d.\n",
			__func__, inode, cmd->id, cmd->start, cmd->size, err);
	return err;
}

/*
 * Create response, just marks local inode as 'created', so that writeback
 * for any of its children (or own) would not try to sync it again.
 */
static int pohmelfs_create_response(struct netfs_state *st)
{
	struct inode *inode;
	struct netfs_cmd *cmd = &st->cmd;
	struct pohmelfs_inode *pi;

	inode = ilookup(st->psb->sb, cmd->id);
	if (!inode) {
		printk("%s: failed to find inode: id: %llu, start: %llu.\n",
				__func__, cmd->id, cmd->start);
		goto err_out_exit;
	}

	pi = POHMELFS_I(inode);

	/*
	 * To lock or not to lock?
	 * We actually do not care if it races...
	 */
	if (cmd->start)
		make_bad_inode(inode);
	set_bit(NETFS_INODE_REMOTE_SYNCED, &pi->state);

	pohmelfs_put_inode(pi);

	wake_up(&st->psb->wait);
	return 0;

err_out_exit:
	wake_up(&st->psb->wait);
	return -ENOENT;
}

/*
 * Object remove response. Just says that remove request has been received.
 * Used in cache coherency protocol.
 */
static int pohmelfs_remove_response(struct netfs_state *st)
{
	struct netfs_cmd *cmd = &st->cmd;
	int err;

	err = pohmelfs_data_recv_and_check(st, st->data, cmd->size);
	if (err)
		return err;

	dprintk("%s: parent: %llu, path: '%s'.\n", __func__, cmd->id, (char *)st->data);

	return 0;
}

/*
 * Transaction reply processing.
 *
 * Find transaction based on its generation number, bump its reference counter,
 * so that none could free it under us, drop from the trees and lists and
 * drop reference counter. When it hits zero (when all destinations replied
 * and all timeout handled by async scanning code), completion will be called
 * and transaction will be freed.
 */
static int pohmelfs_transaction_response(struct netfs_state *st)
{
	struct netfs_trans_dst *dst;
	struct netfs_trans *t = NULL;
	struct netfs_cmd *cmd = &st->cmd;
	short err = (signed)cmd->ext;

	mutex_lock(&st->trans_lock);
	dst = netfs_trans_search(st, cmd->start);
	if (dst) {
		netfs_trans_remove_nolock(dst, st);
		t = dst->trans;

		pohmelfs_ftrans_update(cmd->start);
	}
	mutex_unlock(&st->trans_lock);

	if (!t) {
		int check = pohmelfs_ftrans_check(cmd->start);
		printk("%s: failed to find transaction: start: %llu: id: %llu, size: %u, ext: %u, double: %d.\n",
				__func__, cmd->start, cmd->id, cmd->size, cmd->ext, check);
		err = -EINVAL;
		goto out;
	}

	t->result = err;
	netfs_trans_drop_dst_nostate(dst);

out:
	wake_up(&st->psb->wait);
	return err;
}

/*
 * Inode metadata cache coherency message.
 */
static int pohmelfs_page_cache_response(struct netfs_state *st)
{
	struct netfs_cmd *cmd = &st->cmd;
	struct inode *inode;

	dprintk("%s: st: %p, id: %llu, start: %llu, size: %u.\n", __func__, st, cmd->id, cmd->start, cmd->size);

	inode = ilookup(st->psb->sb, cmd->id);
	if (!inode) {
		printk("%s: failed to find inode: id: %llu.\n", __func__, cmd->id);
		return -ENOENT;
	}

	set_bit(NETFS_INODE_NEED_FLUSH, &POHMELFS_I(inode)->state);
	pohmelfs_put_inode(POHMELFS_I(inode));

	return 0;
}

/*
 * Root capabilities response: export statistics
 * like used and available size, number of files and dirs,
 * permissions.
 */
static int pohmelfs_root_cap_response(struct netfs_state *st)
{
	struct netfs_cmd *cmd = &st->cmd;
	struct netfs_root_capabilities *cap;
	struct pohmelfs_sb *psb = st->psb;

	if (cmd->size != sizeof(struct netfs_root_capabilities)) {
		psb->flags = EPROTO;
		wake_up(&psb->wait);
		return -EPROTO;
	}

	cap = st->data;

	netfs_convert_root_capabilities(cap);

	if (psb->total_size < cap->used + cap->avail)
		psb->total_size = cap->used + cap->avail;
	if (cap->avail)
		psb->avail_size = cap->avail;
	psb->state_flags = cap->flags;

	if (psb->state_flags & POHMELFS_FLAGS_RO) {
		psb->sb->s_flags |= MS_RDONLY;
		printk(KERN_INFO "Mounting POHMELFS (%d) read-only.\n", psb->idx);
	}

	if (psb->state_flags & POHMELFS_FLAGS_XATTR)
		printk(KERN_INFO "Mounting POHMELFS (%d) "
			"with extended attributes support.\n", psb->idx);

	if (atomic_read(&psb->total_inodes) <= 1)
		atomic_long_set(&psb->total_inodes, cap->nr_files);

	dprintk("%s: total: %llu, avail: %llu, flags: %llx, inodes: %llu.\n",
		__func__, psb->total_size, psb->avail_size, psb->state_flags, cap->nr_files);

	psb->flags = 0;
	wake_up(&psb->wait);
	return 0;
}

/*
 * Crypto capabilities of the server, where it says that
 * it supports or does not requested hash/cipher algorithms.
 */
static int pohmelfs_crypto_cap_response(struct netfs_state *st)
{
	struct netfs_cmd *cmd = &st->cmd;
	struct netfs_crypto_capabilities *cap;
	struct pohmelfs_sb *psb = st->psb;
	int err = 0;

	if (cmd->size != sizeof(struct netfs_crypto_capabilities)) {
		psb->flags = EPROTO;
		wake_up(&psb->wait);
		return -EPROTO;
	}

	cap = st->data;

	dprintk("%s: cipher '%s': %s, hash: '%s': %s.\n",
			__func__,
			psb->cipher_string, (cap->cipher_strlen)?"SUPPORTED":"NOT SUPPORTED",
			psb->hash_string, (cap->hash_strlen)?"SUPPORTED":"NOT SUPPORTED");

	if (!cap->hash_strlen) {
		if (psb->hash_strlen && psb->crypto_fail_unsupported)
			err = -ENOTSUPP;
		psb->hash_strlen = 0;
		kfree(psb->hash_string);
		psb->hash_string = NULL;
	}

	if (!cap->cipher_strlen) {
		if (psb->cipher_strlen && psb->crypto_fail_unsupported)
			err = -ENOTSUPP;
		psb->cipher_strlen = 0;
		kfree(psb->cipher_string);
		psb->cipher_string = NULL;
	}

	return err;
}

/*
 * Capabilities handshake response.
 */
static int pohmelfs_capabilities_response(struct netfs_state *st)
{
	struct netfs_cmd *cmd = &st->cmd;
	int err = 0;

	err = pohmelfs_data_recv(st, st->data, cmd->size);
	if (err)
		return err;

	switch (cmd->id) {
		case POHMELFS_CRYPTO_CAPABILITIES:
			return pohmelfs_crypto_cap_response(st);
		case POHMELFS_ROOT_CAPABILITIES:
			return pohmelfs_root_cap_response(st);
		default:
			break;
	}
	return -EINVAL;
}

/*
 * Receiving extended attribute.
 * Does not work properly if received size is more than requested one,
 * it should not happen with current request/reply model though.
 */
static int pohmelfs_getxattr_response(struct netfs_state *st)
{
	struct pohmelfs_sb *psb = st->psb;
	struct netfs_cmd *cmd = &st->cmd;
	struct pohmelfs_mcache *m;
	short error = (signed short)cmd->ext, err;
	unsigned int sz, total_size;

	m = pohmelfs_mcache_search(psb, cmd->id);

	dprintk("%s: id: %llu, gen: %llu, err: %d.\n",
		__func__, cmd->id, (m)?m->gen:0, error);

	if (!m) {
		printk("%s: failed to find getxattr cache entry: id: %llu.\n", __func__, cmd->id);
		return -ENOENT;
	}

	if (cmd->size) {
		sz = min_t(unsigned int, cmd->size, m->size);
		err = pohmelfs_data_recv_and_check(st, m->data, sz);
		if (err) {
			error = err;
			goto out;
		}

		m->size = sz;
		total_size = cmd->size - sz;

		while (total_size) {
			sz = min(total_size, st->size);

			err = pohmelfs_data_recv_and_check(st, st->data, sz);
			if (err) {
				error = err;
				break;
			}

			total_size -= sz;
		}
	}

out:
	m->err = error;
	complete(&m->complete);
	pohmelfs_mcache_put(psb, m);

	return error;
}

int pohmelfs_data_lock_response(struct netfs_state *st)
{
	struct pohmelfs_sb *psb = st->psb;
	struct netfs_cmd *cmd = &st->cmd;
	struct pohmelfs_mcache *m;
	short err = (signed short)cmd->ext;
	u64 id = cmd->id;

	m = pohmelfs_mcache_search(psb, id);

	dprintk("%s: id: %llu, gen: %llu, err: %d.\n",
		__func__, cmd->id, (m)?m->gen:0, err);

	if (!m) {
		pohmelfs_data_recv(st, st->data, cmd->size);
		printk("%s: failed to find data lock response: id: %llu.\n", __func__, cmd->id);
		return -ENOENT;
	}

	if (cmd->size)
		err = pohmelfs_data_recv_and_check(st, &m->info, cmd->size);

	m->err = err;
	complete(&m->complete);
	pohmelfs_mcache_put(psb, m);

	return err;
}

static void __inline__ netfs_state_reset(struct netfs_state *st)
{
	netfs_state_lock_send(st);
	netfs_state_exit(st);
	netfs_state_init(st);
	netfs_state_unlock_send(st);
}

/*
 * Main receiving function, called from dedicated kernel thread.
 */
static int pohmelfs_recv(void *data)
{
	int err = -EINTR;
	struct netfs_state *st = data;
	struct netfs_cmd *cmd = &st->cmd;

	while (!kthread_should_stop()) {
		/*
		 * If socket will be reset after this statement, then
		 * pohmelfs_data_recv() will just fail and loop will
		 * start again, so it can be done without any locks.
		 *
		 * st->read_socket is needed to prevents state machine
		 * breaking between this data reading and subsequent one
		 * in protocol specific functions during connection reset.
		 * In case of reset we have to read next command and do
		 * not expect data for old command to magically appear in
		 * new connection.
		 */
		st->read_socket = st->socket;
		err = pohmelfs_data_recv(st, cmd, sizeof(struct netfs_cmd));
		if (err) {
			msleep(1000);
			continue;
		}

		netfs_convert_cmd(cmd);

		dprintk("%s: cmd: %u, id: %llu, start: %llu, size: %u, "
				"ext: %u, csize: %u, cpad: %u.\n",
				__func__, cmd->cmd, cmd->id, cmd->start,
				cmd->size, cmd->ext, cmd->csize, cmd->cpad);

		if (cmd->csize) {
			struct pohmelfs_crypto_engine *e = &st->eng;

			if (unlikely(cmd->csize > e->size/2)) {
				netfs_state_reset(st);
				continue;
			}

			if (e->hash && unlikely(cmd->csize != st->psb->crypto_attached_size)) {
				dprintk("%s: cmd: cmd: %u, id: %llu, start: %llu, size: %u, "
						"csize: %u != digest size %u.\n",
						__func__, cmd->cmd, cmd->id, cmd->start, cmd->size,
						cmd->csize, st->psb->crypto_attached_size);
				netfs_state_reset(st);
				continue;
			}

			err = pohmelfs_data_recv(st, e->data, cmd->csize);
			if (err) {
				netfs_state_reset(st);
				continue;
			}

#ifdef CONFIG_POHMELFS_DEBUG
			{
				unsigned int i;
				unsigned char *hash = e->data;

				dprintk("%s: received hash: ", __func__);
				for (i=0; i<cmd->csize; ++i) {
					printk("%02x ", hash[i]);
				}
				printk("\n");
			}
#endif
			cmd->size -= cmd->csize;
		}

		/*
		 * This should catch protocol breakage and random garbage instead of commands.
		 */
		if (unlikely((cmd->size > st->size) && (cmd->cmd != NETFS_XATTR_GET))) {
			netfs_state_reset(st);
			continue;
		}

		switch (cmd->cmd) {
			case NETFS_READ_PAGE:
				err = pohmelfs_read_page_response(st);
				break;
			case NETFS_READDIR:
				err = pohmelfs_readdir_response(st);
				break;
			case NETFS_LOOKUP:
				err = pohmelfs_lookup_response(st);
				break;
			case NETFS_CREATE:
				err = pohmelfs_create_response(st);
				break;
			case NETFS_REMOVE:
				err = pohmelfs_remove_response(st);
				break;
			case NETFS_TRANS:
				err = pohmelfs_transaction_response(st);
				break;
			case NETFS_PAGE_CACHE:
				err = pohmelfs_page_cache_response(st);
				break;
			case NETFS_CAPABILITIES:
				err = pohmelfs_capabilities_response(st);
				break;
			case NETFS_LOCK:
				err = pohmelfs_data_lock_response(st);
				break;
			case NETFS_XATTR_GET:
				err = pohmelfs_getxattr_response(st);
				break;
			default:
				printk("%s: wrong cmd: %u, id: %llu, start: %llu, size: %u, ext: %u.\n",
					__func__, cmd->cmd, cmd->id, cmd->start, cmd->size, cmd->ext);
				netfs_state_reset(st);
				break;
		}
	}

	while (!kthread_should_stop())
		schedule_timeout_uninterruptible(msecs_to_jiffies(10));

	return err;
}

int netfs_state_init(struct netfs_state *st)
{
	int err;
	struct pohmelfs_ctl *ctl = &st->ctl;

	err = sock_create(ctl->addr.sa_family, ctl->type, ctl->proto, &st->socket);
	if (err) {
		printk("%s: failed to create a socket: family: %d, type: %d, proto: %d, err: %d.\n",
				__func__, ctl->addr.sa_family, ctl->type, ctl->proto, err);
		goto err_out_exit;
	}

	st->socket->sk->sk_allocation = GFP_NOIO;
	st->socket->sk->sk_sndtimeo = st->socket->sk->sk_rcvtimeo = msecs_to_jiffies(60000);

	err = kernel_connect(st->socket, (struct sockaddr *)&ctl->addr, ctl->addrlen, 0);
	if (err) {
		printk("%s: failed to connect to server: idx: %u, err: %d.\n",
				__func__, st->psb->idx, err);
		goto err_out_release;
	}
	st->socket->sk->sk_sndtimeo = st->socket->sk->sk_rcvtimeo = msecs_to_jiffies(60000);

	err = netfs_poll_init(st);
	if (err)
		goto err_out_release;

	if (st->socket->ops->family == AF_INET) {
		struct sockaddr_in *sin = (struct sockaddr_in *)&ctl->addr;
		printk(KERN_INFO "%s: (re)connected to peer %u.%u.%u.%u:%d.\n", __func__,
			NIPQUAD(sin->sin_addr.s_addr), ntohs(sin->sin_port));
	} else if (st->socket->ops->family == AF_INET6) {
		struct sockaddr_in6 *sin = (struct sockaddr_in6 *)&ctl->addr;
		printk(KERN_INFO "%s: (re)connected to peer "
			"%pi6:%d",
			__func__, &sin->sin6_addr, ntohs(sin->sin6_port));
	}

	return 0;

err_out_release:
	sock_release(st->socket);
err_out_exit:
	st->socket = NULL;
	return err;
}

void netfs_state_exit(struct netfs_state *st)
{
	if (st->socket) {
		netfs_poll_exit(st);
		st->socket->ops->shutdown(st->socket, 2);

		if (st->socket->ops->family == AF_INET) {
			struct sockaddr_in *sin = (struct sockaddr_in *)&st->ctl.addr;
			printk("%s: disconnected from peer %u.%u.%u.%u:%d.\n", __func__,
				NIPQUAD(sin->sin_addr.s_addr), ntohs(sin->sin_port));
		} else if (st->socket->ops->family == AF_INET6) {
			struct sockaddr_in6 *sin = (struct sockaddr_in6 *)&st->ctl.addr;
			printk("%s: disconnected from peer "
				"%pi6:%d",
				__func__, &sin->sin6_addr, ntohs(sin->sin6_port));
		}

		sock_release(st->socket);
		st->socket = NULL;
		st->read_socket = NULL;
		st->need_reset = 0;
	}
}

int pohmelfs_state_init_one(struct pohmelfs_sb *psb, struct pohmelfs_config *conf)
{
	struct netfs_state *st = &conf->state;
	int err = -ENOMEM;

	mutex_init(&st->__state_lock);
	mutex_init(&st->__state_send_lock);
	init_waitqueue_head(&st->thread_wait);

	st->psb = psb;
	st->trans_root = RB_ROOT;
	mutex_init(&st->trans_lock);

	st->size = psb->trans_data_size;
	st->data = kmalloc(st->size, GFP_KERNEL);
	if (!st->data)
		goto err_out_exit;

	if (psb->perform_crypto) {
		err = pohmelfs_crypto_engine_init(&st->eng, psb);
		if (err)
			goto err_out_free_data;
	}

	err = netfs_state_init(st);
	if (err)
		goto err_out_free_engine;

	st->thread = kthread_run(pohmelfs_recv, st, "pohmelfs/%u", psb->idx);
	if (IS_ERR(st->thread)) {
		err = PTR_ERR(st->thread);
		goto err_out_netfs_exit;
	}

	if (!psb->active_state)
		psb->active_state = conf;

	dprintk("%s: conf: %p, st: %p, socket: %p.\n",
			__func__, conf, st, st->socket);
	return 0;

err_out_netfs_exit:
	netfs_state_exit(st);
err_out_free_engine:
	pohmelfs_crypto_engine_exit(&st->eng);
err_out_free_data:
	kfree(st->data);
err_out_exit:
	return err;

}

void pohmelfs_state_flush_transactions(struct netfs_state *st)
{
	struct rb_node *rb_node;
	struct netfs_trans_dst *dst;

	mutex_lock(&st->trans_lock);
	for (rb_node = rb_first(&st->trans_root); rb_node; ) {
		dst = rb_entry(rb_node, struct netfs_trans_dst, state_entry);
		rb_node = rb_next(rb_node);

		dst->trans->result = -EINVAL;
		netfs_trans_remove_nolock(dst, st);
		netfs_trans_drop_dst_nostate(dst);
	}
	mutex_unlock(&st->trans_lock);
}

static void pohmelfs_state_exit_one(struct pohmelfs_config *c)
{
	struct netfs_state *st = &c->state;

	dprintk("%s: exiting, st: %p.\n", __func__, st);
	if (st->thread) {
		kthread_stop(st->thread);
		st->thread = NULL;
	}

	netfs_state_lock_send(st);
	netfs_state_exit(st);
	netfs_state_unlock_send(st);

	pohmelfs_state_flush_transactions(st);

	pohmelfs_crypto_engine_exit(&st->eng);
	kfree(st->data);

	kfree(c);
}

/*
 * Initialize network stack. It searches for given ID in global
 * configuration table, this contains information of the remote server
 * (address (any supported by socket interface) and port, protocol and so on).
 */
int pohmelfs_state_init(struct pohmelfs_sb *psb)
{
	int err = -ENOMEM;

	err = pohmelfs_copy_config(psb);
	if (err) {
		pohmelfs_state_exit(psb);
		return err;
	}

	return 0;
}

void pohmelfs_state_exit(struct pohmelfs_sb *psb)
{
	struct pohmelfs_config *c, *tmp;

	list_for_each_entry_safe(c, tmp, &psb->state_list, config_entry) {
		list_del(&c->config_entry);
		pohmelfs_state_exit_one(c);
	}
}

void pohmelfs_switch_active(struct pohmelfs_sb *psb)
{
	struct pohmelfs_config *c = psb->active_state;

	if (!list_empty(&psb->state_list)) {
		if (c->config_entry.next != &psb->state_list) {
			psb->active_state = list_entry(c->config_entry.next,
				struct pohmelfs_config, config_entry);
		} else {
			psb->active_state = list_entry(psb->state_list.next,
				struct pohmelfs_config, config_entry);
		}

		dprintk("%s: empty: %d, active %p -> %p.\n",
			__func__, list_empty(&psb->state_list), c,
			psb->active_state);
	} else
		psb->active_state = NULL;
}

void pohmelfs_check_states(struct pohmelfs_sb *psb)
{
	struct pohmelfs_config *c, *tmp;
	LIST_HEAD(delete_list);

	mutex_lock(&psb->state_lock);
	list_for_each_entry_safe(c, tmp, &psb->state_list, config_entry) {
		if (pohmelfs_config_check(c, psb->idx)) {

			if (psb->active_state == c)
				pohmelfs_switch_active(psb);
			list_move(&c->config_entry, &delete_list);
		}
	}
	pohmelfs_copy_config(psb);
	mutex_unlock(&psb->state_lock);

	list_for_each_entry_safe(c, tmp, &delete_list, config_entry) {
		list_del(&c->config_entry);
		pohmelfs_state_exit_one(c);
	}
}