summaryrefslogtreecommitdiff
path: root/fs/nfs/client.c
blob: c46e94fed9eb3f131eb48646ce7ada34f7cf531e (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
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
/* client.c: NFS client sharing and management code
 *
 * Copyright (C) 2006 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/module.h>
#include <linux/init.h>

#include <linux/time.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/string.h>
#include <linux/stat.h>
#include <linux/errno.h>
#include <linux/unistd.h>
#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/stats.h>
#include <linux/sunrpc/metrics.h>
#include <linux/nfs_fs.h>
#include <linux/nfs_mount.h>
#include <linux/nfs4_mount.h>
#include <linux/lockd/bind.h>
#include <linux/smp_lock.h>
#include <linux/seq_file.h>
#include <linux/mount.h>
#include <linux/nfs_idmap.h>
#include <linux/vfs.h>
#include <linux/inet.h>
#include <linux/nfs_xdr.h>

#include <asm/system.h>

#include "nfs4_fs.h"
#include "callback.h"
#include "delegation.h"
#include "iostat.h"
#include "internal.h"

#define NFSDBG_FACILITY		NFSDBG_CLIENT

static DEFINE_SPINLOCK(nfs_client_lock);
static LIST_HEAD(nfs_client_list);
static LIST_HEAD(nfs_volume_list);
static DECLARE_WAIT_QUEUE_HEAD(nfs_client_active_wq);

/*
 * RPC cruft for NFS
 */
static struct rpc_version *nfs_version[5] = {
	[2]			= &nfs_version2,
#ifdef CONFIG_NFS_V3
	[3]			= &nfs_version3,
#endif
#ifdef CONFIG_NFS_V4
	[4]			= &nfs_version4,
#endif
};

struct rpc_program nfs_program = {
	.name			= "nfs",
	.number			= NFS_PROGRAM,
	.nrvers			= ARRAY_SIZE(nfs_version),
	.version		= nfs_version,
	.stats			= &nfs_rpcstat,
	.pipe_dir_name		= "/nfs",
};

struct rpc_stat nfs_rpcstat = {
	.program		= &nfs_program
};


#ifdef CONFIG_NFS_V3_ACL
static struct rpc_stat		nfsacl_rpcstat = { &nfsacl_program };
static struct rpc_version *	nfsacl_version[] = {
	[3]			= &nfsacl_version3,
};

struct rpc_program		nfsacl_program = {
	.name			= "nfsacl",
	.number			= NFS_ACL_PROGRAM,
	.nrvers			= ARRAY_SIZE(nfsacl_version),
	.version		= nfsacl_version,
	.stats			= &nfsacl_rpcstat,
};
#endif  /* CONFIG_NFS_V3_ACL */

/*
 * Allocate a shared client record
 *
 * Since these are allocated/deallocated very rarely, we don't
 * bother putting them in a slab cache...
 */
static struct nfs_client *nfs_alloc_client(const char *hostname,
					   const struct sockaddr_in *addr,
					   int nfsversion)
{
	struct nfs_client *clp;
	int error;

	if ((clp = kzalloc(sizeof(*clp), GFP_KERNEL)) == NULL)
		goto error_0;

	error = rpciod_up();
	if (error < 0) {
		dprintk("%s: couldn't start rpciod! Error = %d\n",
				__FUNCTION__, error);
		goto error_1;
	}
	__set_bit(NFS_CS_RPCIOD, &clp->cl_res_state);

	if (nfsversion == 4) {
		if (nfs_callback_up() < 0)
			goto error_2;
		__set_bit(NFS_CS_CALLBACK, &clp->cl_res_state);
	}

	atomic_set(&clp->cl_count, 1);
	clp->cl_cons_state = NFS_CS_INITING;

	clp->cl_nfsversion = nfsversion;
	memcpy(&clp->cl_addr, addr, sizeof(clp->cl_addr));

	if (hostname) {
		clp->cl_hostname = kstrdup(hostname, GFP_KERNEL);
		if (!clp->cl_hostname)
			goto error_3;
	}

	INIT_LIST_HEAD(&clp->cl_superblocks);
	clp->cl_rpcclient = ERR_PTR(-EINVAL);

#ifdef CONFIG_NFS_V4
	init_rwsem(&clp->cl_sem);
	INIT_LIST_HEAD(&clp->cl_delegations);
	INIT_LIST_HEAD(&clp->cl_state_owners);
	INIT_LIST_HEAD(&clp->cl_unused);
	spin_lock_init(&clp->cl_lock);
	INIT_DELAYED_WORK(&clp->cl_renewd, nfs4_renew_state);
	rpc_init_wait_queue(&clp->cl_rpcwaitq, "NFS client");
	clp->cl_boot_time = CURRENT_TIME;
	clp->cl_state = 1 << NFS4CLNT_LEASE_EXPIRED;
#endif

	return clp;

error_3:
	if (__test_and_clear_bit(NFS_CS_CALLBACK, &clp->cl_res_state))
		nfs_callback_down();
error_2:
	rpciod_down();
	__clear_bit(NFS_CS_RPCIOD, &clp->cl_res_state);
error_1:
	kfree(clp);
error_0:
	return NULL;
}

static void nfs4_shutdown_client(struct nfs_client *clp)
{
#ifdef CONFIG_NFS_V4
	if (__test_and_clear_bit(NFS_CS_RENEWD, &clp->cl_res_state))
		nfs4_kill_renewd(clp);
	while (!list_empty(&clp->cl_unused)) {
		struct nfs4_state_owner *sp;

		sp = list_entry(clp->cl_unused.next,
				struct nfs4_state_owner,
				so_list);
		list_del(&sp->so_list);
		kfree(sp);
	}
	BUG_ON(!list_empty(&clp->cl_state_owners));
	if (__test_and_clear_bit(NFS_CS_IDMAP, &clp->cl_res_state))
		nfs_idmap_delete(clp);
#endif
}

/*
 * Destroy a shared client record
 */
static void nfs_free_client(struct nfs_client *clp)
{
	dprintk("--> nfs_free_client(%d)\n", clp->cl_nfsversion);

	nfs4_shutdown_client(clp);

	/* -EIO all pending I/O */
	if (!IS_ERR(clp->cl_rpcclient))
		rpc_shutdown_client(clp->cl_rpcclient);

	if (__test_and_clear_bit(NFS_CS_CALLBACK, &clp->cl_res_state))
		nfs_callback_down();

	if (__test_and_clear_bit(NFS_CS_RPCIOD, &clp->cl_res_state))
		rpciod_down();

	kfree(clp->cl_hostname);
	kfree(clp);

	dprintk("<-- nfs_free_client()\n");
}

/*
 * Release a reference to a shared client record
 */
void nfs_put_client(struct nfs_client *clp)
{
	if (!clp)
		return;

	dprintk("--> nfs_put_client({%d})\n", atomic_read(&clp->cl_count));

	if (atomic_dec_and_lock(&clp->cl_count, &nfs_client_lock)) {
		list_del(&clp->cl_share_link);
		spin_unlock(&nfs_client_lock);

		BUG_ON(!list_empty(&clp->cl_superblocks));

		nfs_free_client(clp);
	}
}

/*
 * Find a client by address
 * - caller must hold nfs_client_lock
 */
static struct nfs_client *__nfs_find_client(const struct sockaddr_in *addr, int nfsversion, int match_port)
{
	struct nfs_client *clp;

	list_for_each_entry(clp, &nfs_client_list, cl_share_link) {
		/* Don't match clients that failed to initialise properly */
		if (clp->cl_cons_state < 0)
			continue;

		/* Different NFS versions cannot share the same nfs_client */
		if (clp->cl_nfsversion != nfsversion)
			continue;

		if (memcmp(&clp->cl_addr.sin_addr, &addr->sin_addr,
			   sizeof(clp->cl_addr.sin_addr)) != 0)
			continue;

		if (!match_port || clp->cl_addr.sin_port == addr->sin_port)
			goto found;
	}

	return NULL;

found:
	atomic_inc(&clp->cl_count);
	return clp;
}

/*
 * Find a client by IP address and protocol version
 * - returns NULL if no such client
 */
struct nfs_client *nfs_find_client(const struct sockaddr_in *addr, int nfsversion)
{
	struct nfs_client *clp;

	spin_lock(&nfs_client_lock);
	clp = __nfs_find_client(addr, nfsversion, 0);
	spin_unlock(&nfs_client_lock);
	if (clp != NULL && clp->cl_cons_state != NFS_CS_READY) {
		nfs_put_client(clp);
		clp = NULL;
	}
	return clp;
}

/*
 * Look up a client by IP address and protocol version
 * - creates a new record if one doesn't yet exist
 */
static struct nfs_client *nfs_get_client(const char *hostname,
					 const struct sockaddr_in *addr,
					 int nfsversion)
{
	struct nfs_client *clp, *new = NULL;
	int error;

	dprintk("--> nfs_get_client(%s,"NIPQUAD_FMT":%d,%d)\n",
		hostname ?: "", NIPQUAD(addr->sin_addr),
		addr->sin_port, nfsversion);

	/* see if the client already exists */
	do {
		spin_lock(&nfs_client_lock);

		clp = __nfs_find_client(addr, nfsversion, 1);
		if (clp)
			goto found_client;
		if (new)
			goto install_client;

		spin_unlock(&nfs_client_lock);

		new = nfs_alloc_client(hostname, addr, nfsversion);
	} while (new);

	return ERR_PTR(-ENOMEM);

	/* install a new client and return with it unready */
install_client:
	clp = new;
	list_add(&clp->cl_share_link, &nfs_client_list);
	spin_unlock(&nfs_client_lock);
	dprintk("--> nfs_get_client() = %p [new]\n", clp);
	return clp;

	/* found an existing client
	 * - make sure it's ready before returning
	 */
found_client:
	spin_unlock(&nfs_client_lock);

	if (new)
		nfs_free_client(new);

	error = wait_event_interruptible(nfs_client_active_wq,
				clp->cl_cons_state != NFS_CS_INITING);
	if (error < 0) {
		nfs_put_client(clp);
		return ERR_PTR(-ERESTARTSYS);
	}

	if (clp->cl_cons_state < NFS_CS_READY) {
		error = clp->cl_cons_state;
		nfs_put_client(clp);
		return ERR_PTR(error);
	}

	BUG_ON(clp->cl_cons_state != NFS_CS_READY);

	dprintk("--> nfs_get_client() = %p [share]\n", clp);
	return clp;
}

/*
 * Mark a server as ready or failed
 */
static void nfs_mark_client_ready(struct nfs_client *clp, int state)
{
	clp->cl_cons_state = state;
	wake_up_all(&nfs_client_active_wq);
}

/*
 * Initialise the timeout values for a connection
 */
static void nfs_init_timeout_values(struct rpc_timeout *to, int proto,
				    unsigned int timeo, unsigned int retrans)
{
	to->to_initval = timeo * HZ / 10;
	to->to_retries = retrans;
	if (!to->to_retries)
		to->to_retries = 2;

	switch (proto) {
	case IPPROTO_TCP:
		if (!to->to_initval)
			to->to_initval = 60 * HZ;
		if (to->to_initval > NFS_MAX_TCP_TIMEOUT)
			to->to_initval = NFS_MAX_TCP_TIMEOUT;
		to->to_increment = to->to_initval;
		to->to_maxval = to->to_initval + (to->to_increment * to->to_retries);
		to->to_exponential = 0;
		break;
	case IPPROTO_UDP:
	default:
		if (!to->to_initval)
			to->to_initval = 11 * HZ / 10;
		if (to->to_initval > NFS_MAX_UDP_TIMEOUT)
			to->to_initval = NFS_MAX_UDP_TIMEOUT;
		to->to_maxval = NFS_MAX_UDP_TIMEOUT;
		to->to_exponential = 1;
		break;
	}
}

/*
 * Create an RPC client handle
 */
static int nfs_create_rpc_client(struct nfs_client *clp, int proto,
						unsigned int timeo,
						unsigned int retrans,
						rpc_authflavor_t flavor,
						int flags)
{
	struct rpc_timeout	timeparms;
	struct rpc_clnt		*clnt = NULL;
	struct rpc_create_args args = {
		.protocol	= proto,
		.address	= (struct sockaddr *)&clp->cl_addr,
		.addrsize	= sizeof(clp->cl_addr),
		.timeout	= &timeparms,
		.servername	= clp->cl_hostname,
		.program	= &nfs_program,
		.version	= clp->rpc_ops->version,
		.authflavor	= flavor,
		.flags		= flags,
	};

	if (!IS_ERR(clp->cl_rpcclient))
		return 0;

	nfs_init_timeout_values(&timeparms, proto, timeo, retrans);
	clp->retrans_timeo = timeparms.to_initval;
	clp->retrans_count = timeparms.to_retries;

	clnt = rpc_create(&args);
	if (IS_ERR(clnt)) {
		dprintk("%s: cannot create RPC client. Error = %ld\n",
				__FUNCTION__, PTR_ERR(clnt));
		return PTR_ERR(clnt);
	}

	clp->cl_rpcclient = clnt;
	return 0;
}

/*
 * Version 2 or 3 client destruction
 */
static void nfs_destroy_server(struct nfs_server *server)
{
	if (!IS_ERR(server->client_acl))
		rpc_shutdown_client(server->client_acl);

	if (!(server->flags & NFS_MOUNT_NONLM))
		lockd_down();	/* release rpc.lockd */
}

/*
 * Version 2 or 3 lockd setup
 */
static int nfs_start_lockd(struct nfs_server *server)
{
	int error = 0;

	if (server->nfs_client->cl_nfsversion > 3)
		goto out;
	if (server->flags & NFS_MOUNT_NONLM)
		goto out;
	error = lockd_up((server->flags & NFS_MOUNT_TCP) ?
			IPPROTO_TCP : IPPROTO_UDP);
	if (error < 0)
		server->flags |= NFS_MOUNT_NONLM;
	else
		server->destroy = nfs_destroy_server;
out:
	return error;
}

/*
 * Initialise an NFSv3 ACL client connection
 */
#ifdef CONFIG_NFS_V3_ACL
static void nfs_init_server_aclclient(struct nfs_server *server)
{
	if (server->nfs_client->cl_nfsversion != 3)
		goto out_noacl;
	if (server->flags & NFS_MOUNT_NOACL)
		goto out_noacl;

	server->client_acl = rpc_bind_new_program(server->client, &nfsacl_program, 3);
	if (IS_ERR(server->client_acl))
		goto out_noacl;

	/* No errors! Assume that Sun nfsacls are supported */
	server->caps |= NFS_CAP_ACLS;
	return;

out_noacl:
	server->caps &= ~NFS_CAP_ACLS;
}
#else
static inline void nfs_init_server_aclclient(struct nfs_server *server)
{
	server->flags &= ~NFS_MOUNT_NOACL;
	server->caps &= ~NFS_CAP_ACLS;
}
#endif

/*
 * Create a general RPC client
 */
static int nfs_init_server_rpcclient(struct nfs_server *server, rpc_authflavor_t pseudoflavour)
{
	struct nfs_client *clp = server->nfs_client;

	server->client = rpc_clone_client(clp->cl_rpcclient);
	if (IS_ERR(server->client)) {
		dprintk("%s: couldn't create rpc_client!\n", __FUNCTION__);
		return PTR_ERR(server->client);
	}

	if (pseudoflavour != clp->cl_rpcclient->cl_auth->au_flavor) {
		struct rpc_auth *auth;

		auth = rpcauth_create(pseudoflavour, server->client);
		if (IS_ERR(auth)) {
			dprintk("%s: couldn't create credcache!\n", __FUNCTION__);
			return PTR_ERR(auth);
		}
	}
	server->client->cl_softrtry = 0;
	if (server->flags & NFS_MOUNT_SOFT)
		server->client->cl_softrtry = 1;

	server->client->cl_intr = 0;
	if (server->flags & NFS4_MOUNT_INTR)
		server->client->cl_intr = 1;

	return 0;
}

/*
 * Initialise an NFS2 or NFS3 client
 */
static int nfs_init_client(struct nfs_client *clp, const struct nfs_mount_data *data)
{
	int proto = (data->flags & NFS_MOUNT_TCP) ? IPPROTO_TCP : IPPROTO_UDP;
	int error;

	if (clp->cl_cons_state == NFS_CS_READY) {
		/* the client is already initialised */
		dprintk("<-- nfs_init_client() = 0 [already %p]\n", clp);
		return 0;
	}

	/* Check NFS protocol revision and initialize RPC op vector */
	clp->rpc_ops = &nfs_v2_clientops;
#ifdef CONFIG_NFS_V3
	if (clp->cl_nfsversion == 3)
		clp->rpc_ops = &nfs_v3_clientops;
#endif
	/*
	 * Create a client RPC handle for doing FSSTAT with UNIX auth only
	 * - RFC 2623, sec 2.3.2
	 */
	error = nfs_create_rpc_client(clp, proto, data->timeo, data->retrans,
					RPC_AUTH_UNIX, 0);
	if (error < 0)
		goto error;
	nfs_mark_client_ready(clp, NFS_CS_READY);
	return 0;

error:
	nfs_mark_client_ready(clp, error);
	dprintk("<-- nfs_init_client() = xerror %d\n", error);
	return error;
}

/*
 * Create a version 2 or 3 client
 */
static int nfs_init_server(struct nfs_server *server, const struct nfs_mount_data *data)
{
	struct nfs_client *clp;
	int error, nfsvers = 2;

	dprintk("--> nfs_init_server()\n");

#ifdef CONFIG_NFS_V3
	if (data->flags & NFS_MOUNT_VER3)
		nfsvers = 3;
#endif

	/* Allocate or find a client reference we can use */
	clp = nfs_get_client(data->hostname, &data->addr, nfsvers);
	if (IS_ERR(clp)) {
		dprintk("<-- nfs_init_server() = error %ld\n", PTR_ERR(clp));
		return PTR_ERR(clp);
	}

	error = nfs_init_client(clp, data);
	if (error < 0)
		goto error;

	server->nfs_client = clp;

	/* Initialise the client representation from the mount data */
	server->flags = data->flags & NFS_MOUNT_FLAGMASK;

	if (data->rsize)
		server->rsize = nfs_block_size(data->rsize, NULL);
	if (data->wsize)
		server->wsize = nfs_block_size(data->wsize, NULL);

	server->acregmin = data->acregmin * HZ;
	server->acregmax = data->acregmax * HZ;
	server->acdirmin = data->acdirmin * HZ;
	server->acdirmax = data->acdirmax * HZ;

	/* Start lockd here, before we might error out */
	error = nfs_start_lockd(server);
	if (error < 0)
		goto error;

	error = nfs_init_server_rpcclient(server, data->pseudoflavor);
	if (error < 0)
		goto error;

	server->namelen  = data->namlen;
	/* Create a client RPC handle for the NFSv3 ACL management interface */
	nfs_init_server_aclclient(server);
	if (clp->cl_nfsversion == 3) {
		if (server->namelen == 0 || server->namelen > NFS3_MAXNAMLEN)
			server->namelen = NFS3_MAXNAMLEN;
		server->caps |= NFS_CAP_READDIRPLUS;
	} else {
		if (server->namelen == 0 || server->namelen > NFS2_MAXNAMLEN)
			server->namelen = NFS2_MAXNAMLEN;
	}

	dprintk("<-- nfs_init_server() = 0 [new %p]\n", clp);
	return 0;

error:
	server->nfs_client = NULL;
	nfs_put_client(clp);
	dprintk("<-- nfs_init_server() = xerror %d\n", error);
	return error;
}

/*
 * Load up the server record from information gained in an fsinfo record
 */
static void nfs_server_set_fsinfo(struct nfs_server *server, struct nfs_fsinfo *fsinfo)
{
	unsigned long max_rpc_payload;

	/* Work out a lot of parameters */
	if (server->rsize == 0)
		server->rsize = nfs_block_size(fsinfo->rtpref, NULL);
	if (server->wsize == 0)
		server->wsize = nfs_block_size(fsinfo->wtpref, NULL);

	if (fsinfo->rtmax >= 512 && server->rsize > fsinfo->rtmax)
		server->rsize = nfs_block_size(fsinfo->rtmax, NULL);
	if (fsinfo->wtmax >= 512 && server->wsize > fsinfo->wtmax)
		server->wsize = nfs_block_size(fsinfo->wtmax, NULL);

	max_rpc_payload = nfs_block_size(rpc_max_payload(server->client), NULL);
	if (server->rsize > max_rpc_payload)
		server->rsize = max_rpc_payload;
	if (server->rsize > NFS_MAX_FILE_IO_SIZE)
		server->rsize = NFS_MAX_FILE_IO_SIZE;
	server->rpages = (server->rsize + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
	server->backing_dev_info.ra_pages = server->rpages * NFS_MAX_READAHEAD;

	if (server->wsize > max_rpc_payload)
		server->wsize = max_rpc_payload;
	if (server->wsize > NFS_MAX_FILE_IO_SIZE)
		server->wsize = NFS_MAX_FILE_IO_SIZE;
	server->wpages = (server->wsize + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
	server->wtmult = nfs_block_bits(fsinfo->wtmult, NULL);

	server->dtsize = nfs_block_size(fsinfo->dtpref, NULL);
	if (server->dtsize > PAGE_CACHE_SIZE)
		server->dtsize = PAGE_CACHE_SIZE;
	if (server->dtsize > server->rsize)
		server->dtsize = server->rsize;

	if (server->flags & NFS_MOUNT_NOAC) {
		server->acregmin = server->acregmax = 0;
		server->acdirmin = server->acdirmax = 0;
	}

	server->maxfilesize = fsinfo->maxfilesize;

	/* We're airborne Set socket buffersize */
	rpc_setbufsize(server->client, server->wsize + 100, server->rsize + 100);
}

/*
 * Probe filesystem information, including the FSID on v2/v3
 */
static int nfs_probe_fsinfo(struct nfs_server *server, struct nfs_fh *mntfh, struct nfs_fattr *fattr)
{
	struct nfs_fsinfo fsinfo;
	struct nfs_client *clp = server->nfs_client;
	int error;

	dprintk("--> nfs_probe_fsinfo()\n");

	if (clp->rpc_ops->set_capabilities != NULL) {
		error = clp->rpc_ops->set_capabilities(server, mntfh);
		if (error < 0)
			goto out_error;
	}

	fsinfo.fattr = fattr;
	nfs_fattr_init(fattr);
	error = clp->rpc_ops->fsinfo(server, mntfh, &fsinfo);
	if (error < 0)
		goto out_error;

	nfs_server_set_fsinfo(server, &fsinfo);

	/* Get some general file system info */
	if (server->namelen == 0) {
		struct nfs_pathconf pathinfo;

		pathinfo.fattr = fattr;
		nfs_fattr_init(fattr);

		if (clp->rpc_ops->pathconf(server, mntfh, &pathinfo) >= 0)
			server->namelen = pathinfo.max_namelen;
	}

	dprintk("<-- nfs_probe_fsinfo() = 0\n");
	return 0;

out_error:
	dprintk("nfs_probe_fsinfo: error = %d\n", -error);
	return error;
}

/*
 * Copy useful information when duplicating a server record
 */
static void nfs_server_copy_userdata(struct nfs_server *target, struct nfs_server *source)
{
	target->flags = source->flags;
	target->acregmin = source->acregmin;
	target->acregmax = source->acregmax;
	target->acdirmin = source->acdirmin;
	target->acdirmax = source->acdirmax;
	target->caps = source->caps;
}

/*
 * Allocate and initialise a server record
 */
static struct nfs_server *nfs_alloc_server(void)
{
	struct nfs_server *server;

	server = kzalloc(sizeof(struct nfs_server), GFP_KERNEL);
	if (!server)
		return NULL;

	server->client = server->client_acl = ERR_PTR(-EINVAL);

	/* Zero out the NFS state stuff */
	INIT_LIST_HEAD(&server->client_link);
	INIT_LIST_HEAD(&server->master_link);

	server->io_stats = nfs_alloc_iostats();
	if (!server->io_stats) {
		kfree(server);
		return NULL;
	}

	return server;
}

/*
 * Free up a server record
 */
void nfs_free_server(struct nfs_server *server)
{
	dprintk("--> nfs_free_server()\n");

	spin_lock(&nfs_client_lock);
	list_del(&server->client_link);
	list_del(&server->master_link);
	spin_unlock(&nfs_client_lock);

	if (server->destroy != NULL)
		server->destroy(server);
	if (!IS_ERR(server->client))
		rpc_shutdown_client(server->client);

	nfs_put_client(server->nfs_client);

	nfs_free_iostats(server->io_stats);
	kfree(server);
	nfs_release_automount_timer();
	dprintk("<-- nfs_free_server()\n");
}

/*
 * Create a version 2 or 3 volume record
 * - keyed on server and FSID
 */
struct nfs_server *nfs_create_server(const struct nfs_mount_data *data,
				     struct nfs_fh *mntfh)
{
	struct nfs_server *server;
	struct nfs_fattr fattr;
	int error;

	server = nfs_alloc_server();
	if (!server)
		return ERR_PTR(-ENOMEM);

	/* Get a client representation */
	error = nfs_init_server(server, data);
	if (error < 0)
		goto error;

	BUG_ON(!server->nfs_client);
	BUG_ON(!server->nfs_client->rpc_ops);
	BUG_ON(!server->nfs_client->rpc_ops->file_inode_ops);

	/* Probe the root fh to retrieve its FSID */
	error = nfs_probe_fsinfo(server, mntfh, &fattr);
	if (error < 0)
		goto error;
	if (!(fattr.valid & NFS_ATTR_FATTR)) {
		error = server->nfs_client->rpc_ops->getattr(server, mntfh, &fattr);
		if (error < 0) {
			dprintk("nfs_create_server: getattr error = %d\n", -error);
			goto error;
		}
	}
	memcpy(&server->fsid, &fattr.fsid, sizeof(server->fsid));

	dprintk("Server FSID: %llx:%llx\n",
		(unsigned long long) server->fsid.major,
		(unsigned long long) server->fsid.minor);

	BUG_ON(!server->nfs_client);
	BUG_ON(!server->nfs_client->rpc_ops);
	BUG_ON(!server->nfs_client->rpc_ops->file_inode_ops);

	spin_lock(&nfs_client_lock);
	list_add_tail(&server->client_link, &server->nfs_client->cl_superblocks);
	list_add_tail(&server->master_link, &nfs_volume_list);
	spin_unlock(&nfs_client_lock);

	server->mount_time = jiffies;
	return server;

error:
	nfs_free_server(server);
	return ERR_PTR(error);
}

#ifdef CONFIG_NFS_V4
/*
 * Initialise an NFS4 client record
 */
static int nfs4_init_client(struct nfs_client *clp,
		int proto, int timeo, int retrans,
		const char *ip_addr,
		rpc_authflavor_t authflavour)
{
	int error;

	if (clp->cl_cons_state == NFS_CS_READY) {
		/* the client is initialised already */
		dprintk("<-- nfs4_init_client() = 0 [already %p]\n", clp);
		return 0;
	}

	/* Check NFS protocol revision and initialize RPC op vector */
	clp->rpc_ops = &nfs_v4_clientops;

	error = nfs_create_rpc_client(clp, proto, timeo, retrans, authflavour,
					RPC_CLNT_CREATE_DISCRTRY);
	if (error < 0)
		goto error;
	memcpy(clp->cl_ipaddr, ip_addr, sizeof(clp->cl_ipaddr));

	error = nfs_idmap_new(clp);
	if (error < 0) {
		dprintk("%s: failed to create idmapper. Error = %d\n",
			__FUNCTION__, error);
		goto error;
	}
	__set_bit(NFS_CS_IDMAP, &clp->cl_res_state);

	nfs_mark_client_ready(clp, NFS_CS_READY);
	return 0;

error:
	nfs_mark_client_ready(clp, error);
	dprintk("<-- nfs4_init_client() = xerror %d\n", error);
	return error;
}

/*
 * Set up an NFS4 client
 */
static int nfs4_set_client(struct nfs_server *server,
		const char *hostname, const struct sockaddr_in *addr,
		const char *ip_addr,
		rpc_authflavor_t authflavour,
		int proto, int timeo, int retrans)
{
	struct nfs_client *clp;
	int error;

	dprintk("--> nfs4_set_client()\n");

	/* Allocate or find a client reference we can use */
	clp = nfs_get_client(hostname, addr, 4);
	if (IS_ERR(clp)) {
		error = PTR_ERR(clp);
		goto error;
	}
	error = nfs4_init_client(clp, proto, timeo, retrans, ip_addr, authflavour);
	if (error < 0)
		goto error_put;

	server->nfs_client = clp;
	dprintk("<-- nfs4_set_client() = 0 [new %p]\n", clp);
	return 0;

error_put:
	nfs_put_client(clp);
error:
	dprintk("<-- nfs4_set_client() = xerror %d\n", error);
	return error;
}

/*
 * Create a version 4 volume record
 */
static int nfs4_init_server(struct nfs_server *server,
		const struct nfs4_mount_data *data, rpc_authflavor_t authflavour)
{
	int error;

	dprintk("--> nfs4_init_server()\n");

	/* Initialise the client representation from the mount data */
	server->flags = data->flags & NFS_MOUNT_FLAGMASK;
	server->caps |= NFS_CAP_ATOMIC_OPEN;

	if (data->rsize)
		server->rsize = nfs_block_size(data->rsize, NULL);
	if (data->wsize)
		server->wsize = nfs_block_size(data->wsize, NULL);

	server->acregmin = data->acregmin * HZ;
	server->acregmax = data->acregmax * HZ;
	server->acdirmin = data->acdirmin * HZ;
	server->acdirmax = data->acdirmax * HZ;

	error = nfs_init_server_rpcclient(server, authflavour);

	/* Done */
	dprintk("<-- nfs4_init_server() = %d\n", error);
	return error;
}

/*
 * Create a version 4 volume record
 * - keyed on server and FSID
 */
struct nfs_server *nfs4_create_server(const struct nfs4_mount_data *data,
				      const char *hostname,
				      const struct sockaddr_in *addr,
				      const char *mntpath,
				      const char *ip_addr,
				      rpc_authflavor_t authflavour,
				      struct nfs_fh *mntfh)
{
	struct nfs_fattr fattr;
	struct nfs_server *server;
	int error;

	dprintk("--> nfs4_create_server()\n");

	server = nfs_alloc_server();
	if (!server)
		return ERR_PTR(-ENOMEM);

	/* Get a client record */
	error = nfs4_set_client(server, hostname, addr, ip_addr, authflavour,
			data->proto, data->timeo, data->retrans);
	if (error < 0)
		goto error;

	/* set up the general RPC client */
	error = nfs4_init_server(server, data, authflavour);
	if (error < 0)
		goto error;

	BUG_ON(!server->nfs_client);
	BUG_ON(!server->nfs_client->rpc_ops);
	BUG_ON(!server->nfs_client->rpc_ops->file_inode_ops);

	/* Probe the root fh to retrieve its FSID */
	error = nfs4_path_walk(server, mntfh, mntpath);
	if (error < 0)
		goto error;

	dprintk("Server FSID: %llx:%llx\n",
		(unsigned long long) server->fsid.major,
		(unsigned long long) server->fsid.minor);
	dprintk("Mount FH: %d\n", mntfh->size);

	error = nfs_probe_fsinfo(server, mntfh, &fattr);
	if (error < 0)
		goto error;

	BUG_ON(!server->nfs_client);
	BUG_ON(!server->nfs_client->rpc_ops);
	BUG_ON(!server->nfs_client->rpc_ops->file_inode_ops);

	spin_lock(&nfs_client_lock);
	list_add_tail(&server->client_link, &server->nfs_client->cl_superblocks);
	list_add_tail(&server->master_link, &nfs_volume_list);
	spin_unlock(&nfs_client_lock);

	server->mount_time = jiffies;
	dprintk("<-- nfs4_create_server() = %p\n", server);
	return server;

error:
	nfs_free_server(server);
	dprintk("<-- nfs4_create_server() = error %d\n", error);
	return ERR_PTR(error);
}

/*
 * Create an NFS4 referral server record
 */
struct nfs_server *nfs4_create_referral_server(struct nfs_clone_mount *data,
					       struct nfs_fh *mntfh)
{
	struct nfs_client *parent_client;
	struct nfs_server *server, *parent_server;
	struct nfs_fattr fattr;
	int error;

	dprintk("--> nfs4_create_referral_server()\n");

	server = nfs_alloc_server();
	if (!server)
		return ERR_PTR(-ENOMEM);

	parent_server = NFS_SB(data->sb);
	parent_client = parent_server->nfs_client;

	/* Get a client representation.
	 * Note: NFSv4 always uses TCP, */
	error = nfs4_set_client(server, data->hostname, data->addr,
			parent_client->cl_ipaddr,
			data->authflavor,
			parent_server->client->cl_xprt->prot,
			parent_client->retrans_timeo,
			parent_client->retrans_count);
	if (error < 0)
		goto error;

	/* Initialise the client representation from the parent server */
	nfs_server_copy_userdata(server, parent_server);
	server->caps |= NFS_CAP_ATOMIC_OPEN;

	error = nfs_init_server_rpcclient(server, data->authflavor);
	if (error < 0)
		goto error;

	BUG_ON(!server->nfs_client);
	BUG_ON(!server->nfs_client->rpc_ops);
	BUG_ON(!server->nfs_client->rpc_ops->file_inode_ops);

	/* Probe the root fh to retrieve its FSID and filehandle */
	error = nfs4_path_walk(server, mntfh, data->mnt_path);
	if (error < 0)
		goto error;

	/* probe the filesystem info for this server filesystem */
	error = nfs_probe_fsinfo(server, mntfh, &fattr);
	if (error < 0)
		goto error;

	dprintk("Referral FSID: %llx:%llx\n",
		(unsigned long long) server->fsid.major,
		(unsigned long long) server->fsid.minor);

	spin_lock(&nfs_client_lock);
	list_add_tail(&server->client_link, &server->nfs_client->cl_superblocks);
	list_add_tail(&server->master_link, &nfs_volume_list);
	spin_unlock(&nfs_client_lock);

	server->mount_time = jiffies;

	dprintk("<-- nfs_create_referral_server() = %p\n", server);
	return server;

error:
	nfs_free_server(server);
	dprintk("<-- nfs4_create_referral_server() = error %d\n", error);
	return ERR_PTR(error);
}

#endif /* CONFIG_NFS_V4 */

/*
 * Clone an NFS2, NFS3 or NFS4 server record
 */
struct nfs_server *nfs_clone_server(struct nfs_server *source,
				    struct nfs_fh *fh,
				    struct nfs_fattr *fattr)
{
	struct nfs_server *server;
	struct nfs_fattr fattr_fsinfo;
	int error;

	dprintk("--> nfs_clone_server(,%llx:%llx,)\n",
		(unsigned long long) fattr->fsid.major,
		(unsigned long long) fattr->fsid.minor);

	server = nfs_alloc_server();
	if (!server)
		return ERR_PTR(-ENOMEM);

	/* Copy data from the source */
	server->nfs_client = source->nfs_client;
	atomic_inc(&server->nfs_client->cl_count);
	nfs_server_copy_userdata(server, source);

	server->fsid = fattr->fsid;

	error = nfs_init_server_rpcclient(server, source->client->cl_auth->au_flavor);
	if (error < 0)
		goto out_free_server;
	if (!IS_ERR(source->client_acl))
		nfs_init_server_aclclient(server);

	/* probe the filesystem info for this server filesystem */
	error = nfs_probe_fsinfo(server, fh, &fattr_fsinfo);
	if (error < 0)
		goto out_free_server;

	dprintk("Cloned FSID: %llx:%llx\n",
		(unsigned long long) server->fsid.major,
		(unsigned long long) server->fsid.minor);

	error = nfs_start_lockd(server);
	if (error < 0)
		goto out_free_server;

	spin_lock(&nfs_client_lock);
	list_add_tail(&server->client_link, &server->nfs_client->cl_superblocks);
	list_add_tail(&server->master_link, &nfs_volume_list);
	spin_unlock(&nfs_client_lock);

	server->mount_time = jiffies;

	dprintk("<-- nfs_clone_server() = %p\n", server);
	return server;

out_free_server:
	nfs_free_server(server);
	dprintk("<-- nfs_clone_server() = error %d\n", error);
	return ERR_PTR(error);
}

#ifdef CONFIG_PROC_FS
static struct proc_dir_entry *proc_fs_nfs;

static int nfs_server_list_open(struct inode *inode, struct file *file);
static void *nfs_server_list_start(struct seq_file *p, loff_t *pos);
static void *nfs_server_list_next(struct seq_file *p, void *v, loff_t *pos);
static void nfs_server_list_stop(struct seq_file *p, void *v);
static int nfs_server_list_show(struct seq_file *m, void *v);

static struct seq_operations nfs_server_list_ops = {
	.start	= nfs_server_list_start,
	.next	= nfs_server_list_next,
	.stop	= nfs_server_list_stop,
	.show	= nfs_server_list_show,
};

static struct file_operations nfs_server_list_fops = {
	.open		= nfs_server_list_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
	.release	= seq_release,
};

static int nfs_volume_list_open(struct inode *inode, struct file *file);
static void *nfs_volume_list_start(struct seq_file *p, loff_t *pos);
static void *nfs_volume_list_next(struct seq_file *p, void *v, loff_t *pos);
static void nfs_volume_list_stop(struct seq_file *p, void *v);
static int nfs_volume_list_show(struct seq_file *m, void *v);

static struct seq_operations nfs_volume_list_ops = {
	.start	= nfs_volume_list_start,
	.next	= nfs_volume_list_next,
	.stop	= nfs_volume_list_stop,
	.show	= nfs_volume_list_show,
};

static struct file_operations nfs_volume_list_fops = {
	.open		= nfs_volume_list_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
	.release	= seq_release,
};

/*
 * open "/proc/fs/nfsfs/servers" which provides a summary of servers with which
 * we're dealing
 */
static int nfs_server_list_open(struct inode *inode, struct file *file)
{
	struct seq_file *m;
	int ret;

	ret = seq_open(file, &nfs_server_list_ops);
	if (ret < 0)
		return ret;

	m = file->private_data;
	m->private = PDE(inode)->data;

	return 0;
}

/*
 * set up the iterator to start reading from the server list and return the first item
 */
static void *nfs_server_list_start(struct seq_file *m, loff_t *_pos)
{
	struct list_head *_p;
	loff_t pos = *_pos;

	/* lock the list against modification */
	spin_lock(&nfs_client_lock);

	/* allow for the header line */
	if (!pos)
		return SEQ_START_TOKEN;
	pos--;

	/* find the n'th element in the list */
	list_for_each(_p, &nfs_client_list)
		if (!pos--)
			break;

	return _p != &nfs_client_list ? _p : NULL;
}

/*
 * move to next server
 */
static void *nfs_server_list_next(struct seq_file *p, void *v, loff_t *pos)
{
	struct list_head *_p;

	(*pos)++;

	_p = v;
	_p = (v == SEQ_START_TOKEN) ? nfs_client_list.next : _p->next;

	return _p != &nfs_client_list ? _p : NULL;
}

/*
 * clean up after reading from the transports list
 */
static void nfs_server_list_stop(struct seq_file *p, void *v)
{
	spin_unlock(&nfs_client_lock);
}

/*
 * display a header line followed by a load of call lines
 */
static int nfs_server_list_show(struct seq_file *m, void *v)
{
	struct nfs_client *clp;

	/* display header on line 1 */
	if (v == SEQ_START_TOKEN) {
		seq_puts(m, "NV SERVER   PORT USE HOSTNAME\n");
		return 0;
	}

	/* display one transport per line on subsequent lines */
	clp = list_entry(v, struct nfs_client, cl_share_link);

	seq_printf(m, "v%d %02x%02x%02x%02x %4hx %3d %s\n",
		   clp->cl_nfsversion,
		   NIPQUAD(clp->cl_addr.sin_addr),
		   ntohs(clp->cl_addr.sin_port),
		   atomic_read(&clp->cl_count),
		   clp->cl_hostname);

	return 0;
}

/*
 * open "/proc/fs/nfsfs/volumes" which provides a summary of extant volumes
 */
static int nfs_volume_list_open(struct inode *inode, struct file *file)
{
	struct seq_file *m;
	int ret;

	ret = seq_open(file, &nfs_volume_list_ops);
	if (ret < 0)
		return ret;

	m = file->private_data;
	m->private = PDE(inode)->data;

	return 0;
}

/*
 * set up the iterator to start reading from the volume list and return the first item
 */
static void *nfs_volume_list_start(struct seq_file *m, loff_t *_pos)
{
	struct list_head *_p;
	loff_t pos = *_pos;

	/* lock the list against modification */
	spin_lock(&nfs_client_lock);

	/* allow for the header line */
	if (!pos)
		return SEQ_START_TOKEN;
	pos--;

	/* find the n'th element in the list */
	list_for_each(_p, &nfs_volume_list)
		if (!pos--)
			break;

	return _p != &nfs_volume_list ? _p : NULL;
}

/*
 * move to next volume
 */
static void *nfs_volume_list_next(struct seq_file *p, void *v, loff_t *pos)
{
	struct list_head *_p;

	(*pos)++;

	_p = v;
	_p = (v == SEQ_START_TOKEN) ? nfs_volume_list.next : _p->next;

	return _p != &nfs_volume_list ? _p : NULL;
}

/*
 * clean up after reading from the transports list
 */
static void nfs_volume_list_stop(struct seq_file *p, void *v)
{
	spin_unlock(&nfs_client_lock);
}

/*
 * display a header line followed by a load of call lines
 */
static int nfs_volume_list_show(struct seq_file *m, void *v)
{
	struct nfs_server *server;
	struct nfs_client *clp;
	char dev[8], fsid[17];

	/* display header on line 1 */
	if (v == SEQ_START_TOKEN) {
		seq_puts(m, "NV SERVER   PORT DEV     FSID\n");
		return 0;
	}
	/* display one transport per line on subsequent lines */
	server = list_entry(v, struct nfs_server, master_link);
	clp = server->nfs_client;

	snprintf(dev, 8, "%u:%u",
		 MAJOR(server->s_dev), MINOR(server->s_dev));

	snprintf(fsid, 17, "%llx:%llx",
		 (unsigned long long) server->fsid.major,
		 (unsigned long long) server->fsid.minor);

	seq_printf(m, "v%d %02x%02x%02x%02x %4hx %-7s %-17s\n",
		   clp->cl_nfsversion,
		   NIPQUAD(clp->cl_addr.sin_addr),
		   ntohs(clp->cl_addr.sin_port),
		   dev,
		   fsid);

	return 0;
}

/*
 * initialise the /proc/fs/nfsfs/ directory
 */
int __init nfs_fs_proc_init(void)
{
	struct proc_dir_entry *p;

	proc_fs_nfs = proc_mkdir("nfsfs", proc_root_fs);
	if (!proc_fs_nfs)
		goto error_0;

	proc_fs_nfs->owner = THIS_MODULE;

	/* a file of servers with which we're dealing */
	p = create_proc_entry("servers", S_IFREG|S_IRUGO, proc_fs_nfs);
	if (!p)
		goto error_1;

	p->proc_fops = &nfs_server_list_fops;
	p->owner = THIS_MODULE;

	/* a file of volumes that we have mounted */
	p = create_proc_entry("volumes", S_IFREG|S_IRUGO, proc_fs_nfs);
	if (!p)
		goto error_2;

	p->proc_fops = &nfs_volume_list_fops;
	p->owner = THIS_MODULE;
	return 0;

error_2:
	remove_proc_entry("servers", proc_fs_nfs);
error_1:
	remove_proc_entry("nfsfs", proc_root_fs);
error_0:
	return -ENOMEM;
}

/*
 * clean up the /proc/fs/nfsfs/ directory
 */
void nfs_fs_proc_exit(void)
{
	remove_proc_entry("volumes", proc_fs_nfs);
	remove_proc_entry("servers", proc_fs_nfs);
	remove_proc_entry("nfsfs", proc_root_fs);
}

#endif /* CONFIG_PROC_FS */