summaryrefslogtreecommitdiffstats
path: root/fs/nfsd/nfssvc.c
blob: 81d47049588f22ca936ad45f916c8eba7a326142 (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
// SPDX-License-Identifier: GPL-2.0
/*
 * Central processing for nfsd.
 *
 * Authors:	Olaf Kirch (okir@monad.swb.de)
 *
 * Copyright (C) 1995, 1996, 1997 Olaf Kirch <okir@monad.swb.de>
 */

#include <linux/sched/signal.h>
#include <linux/freezer.h>
#include <linux/module.h>
#include <linux/fs_struct.h>
#include <linux/swap.h>
#include <linux/siphash.h>

#include <linux/sunrpc/stats.h>
#include <linux/sunrpc/svcsock.h>
#include <linux/sunrpc/svc_xprt.h>
#include <linux/lockd/bind.h>
#include <linux/nfsacl.h>
#include <linux/seq_file.h>
#include <linux/inetdevice.h>
#include <net/addrconf.h>
#include <net/ipv6.h>
#include <net/net_namespace.h>
#include "nfsd.h"
#include "cache.h"
#include "vfs.h"
#include "netns.h"
#include "filecache.h"

#include "trace.h"

#define NFSDDBG_FACILITY	NFSDDBG_SVC

extern struct svc_program	nfsd_program;
static int			nfsd(void *vrqstp);
#if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
static int			nfsd_acl_rpcbind_set(struct net *,
						     const struct svc_program *,
						     u32, int,
						     unsigned short,
						     unsigned short);
static __be32			nfsd_acl_init_request(struct svc_rqst *,
						const struct svc_program *,
						struct svc_process_info *);
#endif
static int			nfsd_rpcbind_set(struct net *,
						 const struct svc_program *,
						 u32, int,
						 unsigned short,
						 unsigned short);
static __be32			nfsd_init_request(struct svc_rqst *,
						const struct svc_program *,
						struct svc_process_info *);

/*
 * nfsd_mutex protects nn->nfsd_serv -- both the pointer itself and some members
 * of the svc_serv struct such as ->sv_temp_socks and ->sv_permsocks.
 *
 * If (out side the lock) nn->nfsd_serv is non-NULL, then it must point to a
 * properly initialised 'struct svc_serv' with ->sv_nrthreads > 0 (unless
 * nn->keep_active is set).  That number of nfsd threads must
 * exist and each must be listed in ->sp_all_threads in some entry of
 * ->sv_pools[].
 *
 * Each active thread holds a counted reference on nn->nfsd_serv, as does
 * the nn->keep_active flag and various transient calls to svc_get().
 *
 * Finally, the nfsd_mutex also protects some of the global variables that are
 * accessed when nfsd starts and that are settable via the write_* routines in
 * nfsctl.c. In particular:
 *
 *	user_recovery_dirname
 *	user_lease_time
 *	nfsd_versions
 */
DEFINE_MUTEX(nfsd_mutex);

/*
 * nfsd_drc_lock protects nfsd_drc_max_pages and nfsd_drc_pages_used.
 * nfsd_drc_max_pages limits the total amount of memory available for
 * version 4.1 DRC caches.
 * nfsd_drc_pages_used tracks the current version 4.1 DRC memory usage.
 */
DEFINE_SPINLOCK(nfsd_drc_lock);
unsigned long	nfsd_drc_max_mem;
unsigned long	nfsd_drc_mem_used;

#if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
static struct svc_stat	nfsd_acl_svcstats;
static const struct svc_version *nfsd_acl_version[] = {
	[2] = &nfsd_acl_version2,
	[3] = &nfsd_acl_version3,
};

#define NFSD_ACL_MINVERS            2
#define NFSD_ACL_NRVERS		ARRAY_SIZE(nfsd_acl_version)

static struct svc_program	nfsd_acl_program = {
	.pg_prog		= NFS_ACL_PROGRAM,
	.pg_nvers		= NFSD_ACL_NRVERS,
	.pg_vers		= nfsd_acl_version,
	.pg_name		= "nfsacl",
	.pg_class		= "nfsd",
	.pg_stats		= &nfsd_acl_svcstats,
	.pg_authenticate	= &svc_set_client,
	.pg_init_request	= nfsd_acl_init_request,
	.pg_rpcbind_set		= nfsd_acl_rpcbind_set,
};

static struct svc_stat	nfsd_acl_svcstats = {
	.program	= &nfsd_acl_program,
};
#endif /* defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL) */

static const struct svc_version *nfsd_version[] = {
	[2] = &nfsd_version2,
#if defined(CONFIG_NFSD_V3)
	[3] = &nfsd_version3,
#endif
#if defined(CONFIG_NFSD_V4)
	[4] = &nfsd_version4,
#endif
};

#define NFSD_MINVERS    	2
#define NFSD_NRVERS		ARRAY_SIZE(nfsd_version)

struct svc_program		nfsd_program = {
#if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
	.pg_next		= &nfsd_acl_program,
#endif
	.pg_prog		= NFS_PROGRAM,		/* program number */
	.pg_nvers		= NFSD_NRVERS,		/* nr of entries in nfsd_version */
	.pg_vers		= nfsd_version,		/* version table */
	.pg_name		= "nfsd",		/* program name */
	.pg_class		= "nfsd",		/* authentication class */
	.pg_stats		= &nfsd_svcstats,	/* version table */
	.pg_authenticate	= &svc_set_client,	/* export authentication */
	.pg_init_request	= nfsd_init_request,
	.pg_rpcbind_set		= nfsd_rpcbind_set,
};

static bool
nfsd_support_version(int vers)
{
	if (vers >= NFSD_MINVERS && vers < NFSD_NRVERS)
		return nfsd_version[vers] != NULL;
	return false;
}

static bool *
nfsd_alloc_versions(void)
{
	bool *vers = kmalloc_array(NFSD_NRVERS, sizeof(bool), GFP_KERNEL);
	unsigned i;

	if (vers) {
		/* All compiled versions are enabled by default */
		for (i = 0; i < NFSD_NRVERS; i++)
			vers[i] = nfsd_support_version(i);
	}
	return vers;
}

static bool *
nfsd_alloc_minorversions(void)
{
	bool *vers = kmalloc_array(NFSD_SUPPORTED_MINOR_VERSION + 1,
			sizeof(bool), GFP_KERNEL);
	unsigned i;

	if (vers) {
		/* All minor versions are enabled by default */
		for (i = 0; i <= NFSD_SUPPORTED_MINOR_VERSION; i++)
			vers[i] = nfsd_support_version(4);
	}
	return vers;
}

void
nfsd_netns_free_versions(struct nfsd_net *nn)
{
	kfree(nn->nfsd_versions);
	kfree(nn->nfsd4_minorversions);
	nn->nfsd_versions = NULL;
	nn->nfsd4_minorversions = NULL;
}

static void
nfsd_netns_init_versions(struct nfsd_net *nn)
{
	if (!nn->nfsd_versions) {
		nn->nfsd_versions = nfsd_alloc_versions();
		nn->nfsd4_minorversions = nfsd_alloc_minorversions();
		if (!nn->nfsd_versions || !nn->nfsd4_minorversions)
			nfsd_netns_free_versions(nn);
	}
}

int nfsd_vers(struct nfsd_net *nn, int vers, enum vers_op change)
{
	if (vers < NFSD_MINVERS || vers >= NFSD_NRVERS)
		return 0;
	switch(change) {
	case NFSD_SET:
		if (nn->nfsd_versions)
			nn->nfsd_versions[vers] = nfsd_support_version(vers);
		break;
	case NFSD_CLEAR:
		nfsd_netns_init_versions(nn);
		if (nn->nfsd_versions)
			nn->nfsd_versions[vers] = false;
		break;
	case NFSD_TEST:
		if (nn->nfsd_versions)
			return nn->nfsd_versions[vers];
		fallthrough;
	case NFSD_AVAIL:
		return nfsd_support_version(vers);
	}
	return 0;
}

static void
nfsd_adjust_nfsd_versions4(struct nfsd_net *nn)
{
	unsigned i;

	for (i = 0; i <= NFSD_SUPPORTED_MINOR_VERSION; i++) {
		if (nn->nfsd4_minorversions[i])
			return;
	}
	nfsd_vers(nn, 4, NFSD_CLEAR);
}

int nfsd_minorversion(struct nfsd_net *nn, u32 minorversion, enum vers_op change)
{
	if (minorversion > NFSD_SUPPORTED_MINOR_VERSION &&
	    change != NFSD_AVAIL)
		return -1;

	switch(change) {
	case NFSD_SET:
		if (nn->nfsd4_minorversions) {
			nfsd_vers(nn, 4, NFSD_SET);
			nn->nfsd4_minorversions[minorversion] =
				nfsd_vers(nn, 4, NFSD_TEST);
		}
		break;
	case NFSD_CLEAR:
		nfsd_netns_init_versions(nn);
		if (nn->nfsd4_minorversions) {
			nn->nfsd4_minorversions[minorversion] = false;
			nfsd_adjust_nfsd_versions4(nn);
		}
		break;
	case NFSD_TEST:
		if (nn->nfsd4_minorversions)
			return nn->nfsd4_minorversions[minorversion];
		return nfsd_vers(nn, 4, NFSD_TEST);
	case NFSD_AVAIL:
		return minorversion <= NFSD_SUPPORTED_MINOR_VERSION &&
			nfsd_vers(nn, 4, NFSD_AVAIL);
	}
	return 0;
}

/*
 * Maximum number of nfsd processes
 */
#define	NFSD_MAXSERVS		8192

int nfsd_nrthreads(struct net *net)
{
	int rv = 0;
	struct nfsd_net *nn = net_generic(net, nfsd_net_id);

	mutex_lock(&nfsd_mutex);
	if (nn->nfsd_serv)
		rv = nn->nfsd_serv->sv_nrthreads;
	mutex_unlock(&nfsd_mutex);
	return rv;
}

static int nfsd_init_socks(struct net *net, const struct cred *cred)
{
	int error;
	struct nfsd_net *nn = net_generic(net, nfsd_net_id);

	if (!list_empty(&nn->nfsd_serv->sv_permsocks))
		return 0;

	error = svc_create_xprt(nn->nfsd_serv, "udp", net, PF_INET, NFS_PORT,
					SVC_SOCK_DEFAULTS, cred);
	if (error < 0)
		return error;

	error = svc_create_xprt(nn->nfsd_serv, "tcp", net, PF_INET, NFS_PORT,
					SVC_SOCK_DEFAULTS, cred);
	if (error < 0)
		return error;

	return 0;
}

static int nfsd_users = 0;

static int nfsd_startup_generic(void)
{
	int ret;

	if (nfsd_users++)
		return 0;

	ret = nfsd_file_cache_init();
	if (ret)
		goto dec_users;

	ret = nfs4_state_start();
	if (ret)
		goto out_file_cache;
	return 0;

out_file_cache:
	nfsd_file_cache_shutdown();
dec_users:
	nfsd_users--;
	return ret;
}

static void nfsd_shutdown_generic(void)
{
	if (--nfsd_users)
		return;

	nfs4_state_shutdown();
	nfsd_file_cache_shutdown();
}

static bool nfsd_needs_lockd(struct nfsd_net *nn)
{
	return nfsd_vers(nn, 2, NFSD_TEST) || nfsd_vers(nn, 3, NFSD_TEST);
}

/**
 * nfsd_copy_boot_verifier - Atomically copy a write verifier
 * @verf: buffer in which to receive the verifier cookie
 * @nn: NFS net namespace
 *
 * This function provides a wait-free mechanism for copying the
 * namespace's boot verifier without tearing it.
 */
void nfsd_copy_boot_verifier(__be32 verf[2], struct nfsd_net *nn)
{
	int seq = 0;

	do {
		read_seqbegin_or_lock(&nn->writeverf_lock, &seq);
		memcpy(verf, nn->writeverf, sizeof(*verf));
	} while (need_seqretry(&nn->writeverf_lock, seq));
	done_seqretry(&nn->writeverf_lock, seq);
}

static void nfsd_reset_boot_verifier_locked(struct nfsd_net *nn)
{
	struct timespec64 now;
	u64 verf;

	/*
	 * Because the time value is hashed, y2038 time_t overflow
	 * is irrelevant in this usage.
	 */
	ktime_get_raw_ts64(&now);
	verf = siphash_2u64(now.tv_sec, now.tv_nsec, &nn->siphash_key);
	memcpy(nn->writeverf, &verf, sizeof(nn->writeverf));
}

/**
 * nfsd_reset_boot_verifier - Generate a new boot verifier
 * @nn: NFS net namespace
 *
 * This function updates the ->writeverf field of @nn. This field
 * contains an opaque cookie that, according to Section 18.32.3 of
 * RFC 8881, "the client can use to determine whether a server has
 * changed instance state (e.g., server restart) between a call to
 * WRITE and a subsequent call to either WRITE or COMMIT.  This
 * cookie MUST be unchanged during a single instance of the NFSv4.1
 * server and MUST be unique between instances of the NFSv4.1
 * server."
 */
void nfsd_reset_boot_verifier(struct nfsd_net *nn)
{
	write_seqlock(&nn->writeverf_lock);
	nfsd_reset_boot_verifier_locked(nn);
	write_sequnlock(&nn->writeverf_lock);
}

static int nfsd_startup_net(struct net *net, const struct cred *cred)
{
	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
	int ret;

	if (nn->nfsd_net_up)
		return 0;

	ret = nfsd_startup_generic();
	if (ret)
		return ret;
	ret = nfsd_init_socks(net, cred);
	if (ret)
		goto out_socks;

	if (nfsd_needs_lockd(nn) && !nn->lockd_up) {
		ret = lockd_up(net, cred);
		if (ret)
			goto out_socks;
		nn->lockd_up = true;
	}

	ret = nfsd_file_cache_start_net(net);
	if (ret)
		goto out_lockd;
	ret = nfs4_state_start_net(net);
	if (ret)
		goto out_filecache;

#ifdef CONFIG_NFSD_V4_2_INTER_SSC
	nfsd4_ssc_init_umount_work(nn);
#endif
	nn->nfsd_net_up = true;
	return 0;

out_filecache:
	nfsd_file_cache_shutdown_net(net);
out_lockd:
	if (nn->lockd_up) {
		lockd_down(net);
		nn->lockd_up = false;
	}
out_socks:
	nfsd_shutdown_generic();
	return ret;
}

static void nfsd_shutdown_net(struct net *net)
{
	struct nfsd_net *nn = net_generic(net, nfsd_net_id);

	nfsd_file_cache_shutdown_net(net);
	nfs4_state_shutdown_net(net);
	if (nn->lockd_up) {
		lockd_down(net);
		nn->lockd_up = false;
	}
	nn->nfsd_net_up = false;
	nfsd_shutdown_generic();
}

static DEFINE_SPINLOCK(nfsd_notifier_lock);
static int nfsd_inetaddr_event(struct notifier_block *this, unsigned long event,
	void *ptr)
{
	struct in_ifaddr *ifa = (struct in_ifaddr *)ptr;
	struct net_device *dev = ifa->ifa_dev->dev;
	struct net *net = dev_net(dev);
	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
	struct sockaddr_in sin;

	if (event != NETDEV_DOWN || !nn->nfsd_serv)
		goto out;

	spin_lock(&nfsd_notifier_lock);
	if (nn->nfsd_serv) {
		dprintk("nfsd_inetaddr_event: removed %pI4\n", &ifa->ifa_local);
		sin.sin_family = AF_INET;
		sin.sin_addr.s_addr = ifa->ifa_local;
		svc_age_temp_xprts_now(nn->nfsd_serv, (struct sockaddr *)&sin);
	}
	spin_unlock(&nfsd_notifier_lock);

out:
	return NOTIFY_DONE;
}

static struct notifier_block nfsd_inetaddr_notifier = {
	.notifier_call = nfsd_inetaddr_event,
};

#if IS_ENABLED(CONFIG_IPV6)
static int nfsd_inet6addr_event(struct notifier_block *this,
	unsigned long event, void *ptr)
{
	struct inet6_ifaddr *ifa = (struct inet6_ifaddr *)ptr;
	struct net_device *dev = ifa->idev->dev;
	struct net *net = dev_net(dev);
	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
	struct sockaddr_in6 sin6;

	if (event != NETDEV_DOWN || !nn->nfsd_serv)
		goto out;

	spin_lock(&nfsd_notifier_lock);
	if (nn->nfsd_serv) {
		dprintk("nfsd_inet6addr_event: removed %pI6\n", &ifa->addr);
		sin6.sin6_family = AF_INET6;
		sin6.sin6_addr = ifa->addr;
		if (ipv6_addr_type(&sin6.sin6_addr) & IPV6_ADDR_LINKLOCAL)
			sin6.sin6_scope_id = ifa->idev->dev->ifindex;
		svc_age_temp_xprts_now(nn->nfsd_serv, (struct sockaddr *)&sin6);
	}
	spin_unlock(&nfsd_notifier_lock);

out:
	return NOTIFY_DONE;
}

static struct notifier_block nfsd_inet6addr_notifier = {
	.notifier_call = nfsd_inet6addr_event,
};
#endif

/* Only used under nfsd_mutex, so this atomic may be overkill: */
static atomic_t nfsd_notifier_refcount = ATOMIC_INIT(0);

static void nfsd_last_thread(struct svc_serv *serv, struct net *net)
{
	struct nfsd_net *nn = net_generic(net, nfsd_net_id);

	/* check if the notifier still has clients */
	if (atomic_dec_return(&nfsd_notifier_refcount) == 0) {
		unregister_inetaddr_notifier(&nfsd_inetaddr_notifier);
#if IS_ENABLED(CONFIG_IPV6)
		unregister_inet6addr_notifier(&nfsd_inet6addr_notifier);
#endif
	}

	/*
	 * write_ports can create the server without actually starting
	 * any threads--if we get shut down before any threads are
	 * started, then nfsd_last_thread will be run before any of this
	 * other initialization has been done except the rpcb information.
	 */
	svc_rpcb_cleanup(serv, net);
	if (!nn->nfsd_net_up)
		return;

	nfsd_shutdown_net(net);
	pr_info("nfsd: last server has exited, flushing export cache\n");
	nfsd_export_flush(net);
}

void nfsd_reset_versions(struct nfsd_net *nn)
{
	int i;

	for (i = 0; i < NFSD_NRVERS; i++)
		if (nfsd_vers(nn, i, NFSD_TEST))
			return;

	for (i = 0; i < NFSD_NRVERS; i++)
		if (i != 4)
			nfsd_vers(nn, i, NFSD_SET);
		else {
			int minor = 0;
			while (nfsd_minorversion(nn, minor, NFSD_SET) >= 0)
				minor++;
		}
}

/*
 * Each session guarantees a negotiated per slot memory cache for replies
 * which in turn consumes memory beyond the v2/v3/v4.0 server. A dedicated
 * NFSv4.1 server might want to use more memory for a DRC than a machine
 * with mutiple services.
 *
 * Impose a hard limit on the number of pages for the DRC which varies
 * according to the machines free pages. This is of course only a default.
 *
 * For now this is a #defined shift which could be under admin control
 * in the future.
 */
static void set_max_drc(void)
{
	#define NFSD_DRC_SIZE_SHIFT	7
	nfsd_drc_max_mem = (nr_free_buffer_pages()
					>> NFSD_DRC_SIZE_SHIFT) * PAGE_SIZE;
	nfsd_drc_mem_used = 0;
	dprintk("%s nfsd_drc_max_mem %lu \n", __func__, nfsd_drc_max_mem);
}

static int nfsd_get_default_max_blksize(void)
{
	struct sysinfo i;
	unsigned long long target;
	unsigned long ret;

	si_meminfo(&i);
	target = (i.totalram - i.totalhigh) << PAGE_SHIFT;
	/*
	 * Aim for 1/4096 of memory per thread This gives 1MB on 4Gig
	 * machines, but only uses 32K on 128M machines.  Bottom out at
	 * 8K on 32M and smaller.  Of course, this is only a default.
	 */
	target >>= 12;

	ret = NFSSVC_MAXBLKSIZE;
	while (ret > target && ret >= 8*1024*2)
		ret /= 2;
	return ret;
}

static const struct svc_serv_ops nfsd_thread_sv_ops = {
	.svo_shutdown		= nfsd_last_thread,
	.svo_function		= nfsd,
	.svo_enqueue_xprt	= svc_xprt_do_enqueue,
	.svo_module		= THIS_MODULE,
};

void nfsd_shutdown_threads(struct net *net)
{
	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
	struct svc_serv *serv;

	mutex_lock(&nfsd_mutex);
	serv = nn->nfsd_serv;
	if (serv == NULL) {
		mutex_unlock(&nfsd_mutex);
		return;
	}

	svc_get(serv);
	/* Kill outstanding nfsd threads */
	svc_set_num_threads(serv, NULL, 0);
	nfsd_put(net);
	mutex_unlock(&nfsd_mutex);
}

bool i_am_nfsd(void)
{
	return kthread_func(current) == nfsd;
}

int nfsd_create_serv(struct net *net)
{
	int error;
	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
	struct svc_serv *serv;

	WARN_ON(!mutex_is_locked(&nfsd_mutex));
	if (nn->nfsd_serv) {
		svc_get(nn->nfsd_serv);
		return 0;
	}
	if (nfsd_max_blksize == 0)
		nfsd_max_blksize = nfsd_get_default_max_blksize();
	nfsd_reset_versions(nn);
	serv = svc_create_pooled(&nfsd_program, nfsd_max_blksize,
				 &nfsd_thread_sv_ops);
	if (serv == NULL)
		return -ENOMEM;

	serv->sv_maxconn = nn->max_connections;
	error = svc_bind(serv, net);
	if (error < 0) {
		/* NOT nfsd_put() as notifiers (see below) haven't
		 * been set up yet.
		 */
		svc_put(serv);
		return error;
	}
	spin_lock(&nfsd_notifier_lock);
	nn->nfsd_serv = serv;
	spin_unlock(&nfsd_notifier_lock);

	set_max_drc();
	/* check if the notifier is already set */
	if (atomic_inc_return(&nfsd_notifier_refcount) == 1) {
		register_inetaddr_notifier(&nfsd_inetaddr_notifier);
#if IS_ENABLED(CONFIG_IPV6)
		register_inet6addr_notifier(&nfsd_inet6addr_notifier);
#endif
	}
	nfsd_reset_boot_verifier(nn);
	return 0;
}

int nfsd_nrpools(struct net *net)
{
	struct nfsd_net *nn = net_generic(net, nfsd_net_id);

	if (nn->nfsd_serv == NULL)
		return 0;
	else
		return nn->nfsd_serv->sv_nrpools;
}

int nfsd_get_nrthreads(int n, int *nthreads, struct net *net)
{
	int i = 0;
	struct nfsd_net *nn = net_generic(net, nfsd_net_id);

	if (nn->nfsd_serv != NULL) {
		for (i = 0; i < nn->nfsd_serv->sv_nrpools && i < n; i++)
			nthreads[i] = nn->nfsd_serv->sv_pools[i].sp_nrthreads;
	}

	return 0;
}

/* This is the callback for kref_put() below.
 * There is no code here as the first thing to be done is
 * call svc_shutdown_net(), but we cannot get the 'net' from
 * the kref.  So do all the work when kref_put returns true.
 */
static void nfsd_noop(struct kref *ref)
{
}

void nfsd_put(struct net *net)
{
	struct nfsd_net *nn = net_generic(net, nfsd_net_id);

	if (kref_put(&nn->nfsd_serv->sv_refcnt, nfsd_noop)) {
		svc_shutdown_net(nn->nfsd_serv, net);
		svc_destroy(&nn->nfsd_serv->sv_refcnt);
		spin_lock(&nfsd_notifier_lock);
		nn->nfsd_serv = NULL;
		spin_unlock(&nfsd_notifier_lock);
	}
}

int nfsd_set_nrthreads(int n, int *nthreads, struct net *net)
{
	int i = 0;
	int tot = 0;
	int err = 0;
	struct nfsd_net *nn = net_generic(net, nfsd_net_id);

	WARN_ON(!mutex_is_locked(&nfsd_mutex));

	if (nn->nfsd_serv == NULL || n <= 0)
		return 0;

	if (n > nn->nfsd_serv->sv_nrpools)
		n = nn->nfsd_serv->sv_nrpools;

	/* enforce a global maximum number of threads */
	tot = 0;
	for (i = 0; i < n; i++) {
		nthreads[i] = min(nthreads[i], NFSD_MAXSERVS);
		tot += nthreads[i];
	}
	if (tot > NFSD_MAXSERVS) {
		/* total too large: scale down requested numbers */
		for (i = 0; i < n && tot > 0; i++) {
			int new = nthreads[i] * NFSD_MAXSERVS / tot;
			tot -= (nthreads[i] - new);
			nthreads[i] = new;
		}
		for (i = 0; i < n && tot > 0; i++) {
			nthreads[i]--;
			tot--;
		}
	}

	/*
	 * There must always be a thread in pool 0; the admin
	 * can't shut down NFS completely using pool_threads.
	 */
	if (nthreads[0] == 0)
		nthreads[0] = 1;

	/* apply the new numbers */
	svc_get(nn->nfsd_serv);
	for (i = 0; i < n; i++) {
		err = svc_set_num_threads(nn->nfsd_serv,
					  &nn->nfsd_serv->sv_pools[i],
					  nthreads[i]);
		if (err)
			break;
	}
	nfsd_put(net);
	return err;
}

/*
 * Adjust the number of threads and return the new number of threads.
 * This is also the function that starts the server if necessary, if
 * this is the first time nrservs is nonzero.
 */
int
nfsd_svc(int nrservs, struct net *net, const struct cred *cred)
{
	int	error;
	bool	nfsd_up_before;
	struct nfsd_net *nn = net_generic(net, nfsd_net_id);

	mutex_lock(&nfsd_mutex);
	dprintk("nfsd: creating service\n");

	nrservs = max(nrservs, 0);
	nrservs = min(nrservs, NFSD_MAXSERVS);
	error = 0;

	if (nrservs == 0 && nn->nfsd_serv == NULL)
		goto out;

	strlcpy(nn->nfsd_name, utsname()->nodename,
		sizeof(nn->nfsd_name));

	error = nfsd_create_serv(net);
	if (error)
		goto out;

	nfsd_up_before = nn->nfsd_net_up;

	error = nfsd_startup_net(net, cred);
	if (error)
		goto out_put;
	error = svc_set_num_threads(nn->nfsd_serv, NULL, nrservs);
	if (error)
		goto out_shutdown;
	error = nn->nfsd_serv->sv_nrthreads;
out_shutdown:
	if (error < 0 && !nfsd_up_before)
		nfsd_shutdown_net(net);
out_put:
	/* Threads now hold service active */
	if (xchg(&nn->keep_active, 0))
		nfsd_put(net);
	nfsd_put(net);
out:
	mutex_unlock(&nfsd_mutex);
	return error;
}

#if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
static bool
nfsd_support_acl_version(int vers)
{
	if (vers >= NFSD_ACL_MINVERS && vers < NFSD_ACL_NRVERS)
		return nfsd_acl_version[vers] != NULL;
	return false;
}

static int
nfsd_acl_rpcbind_set(struct net *net, const struct svc_program *progp,
		     u32 version, int family, unsigned short proto,
		     unsigned short port)
{
	if (!nfsd_support_acl_version(version) ||
	    !nfsd_vers(net_generic(net, nfsd_net_id), version, NFSD_TEST))
		return 0;
	return svc_generic_rpcbind_set(net, progp, version, family,
			proto, port);
}

static __be32
nfsd_acl_init_request(struct svc_rqst *rqstp,
		      const struct svc_program *progp,
		      struct svc_process_info *ret)
{
	struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);
	int i;

	if (likely(nfsd_support_acl_version(rqstp->rq_vers) &&
	    nfsd_vers(nn, rqstp->rq_vers, NFSD_TEST)))
		return svc_generic_init_request(rqstp, progp, ret);

	ret->mismatch.lovers = NFSD_ACL_NRVERS;
	for (i = NFSD_ACL_MINVERS; i < NFSD_ACL_NRVERS; i++) {
		if (nfsd_support_acl_version(rqstp->rq_vers) &&
		    nfsd_vers(nn, i, NFSD_TEST)) {
			ret->mismatch.lovers = i;
			break;
		}
	}
	if (ret->mismatch.lovers == NFSD_ACL_NRVERS)
		return rpc_prog_unavail;
	ret->mismatch.hivers = NFSD_ACL_MINVERS;
	for (i = NFSD_ACL_NRVERS - 1; i >= NFSD_ACL_MINVERS; i--) {
		if (nfsd_support_acl_version(rqstp->rq_vers) &&
		    nfsd_vers(nn, i, NFSD_TEST)) {
			ret->mismatch.hivers = i;
			break;
		}
	}
	return rpc_prog_mismatch;
}
#endif

static int
nfsd_rpcbind_set(struct net *net, const struct svc_program *progp,
		 u32 version, int family, unsigned short proto,
		 unsigned short port)
{
	if (!nfsd_vers(net_generic(net, nfsd_net_id), version, NFSD_TEST))
		return 0;
	return svc_generic_rpcbind_set(net, progp, version, family,
			proto, port);
}

static __be32
nfsd_init_request(struct svc_rqst *rqstp,
		  const struct svc_program *progp,
		  struct svc_process_info *ret)
{
	struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);
	int i;

	if (likely(nfsd_vers(nn, rqstp->rq_vers, NFSD_TEST)))
		return svc_generic_init_request(rqstp, progp, ret);

	ret->mismatch.lovers = NFSD_NRVERS;
	for (i = NFSD_MINVERS; i < NFSD_NRVERS; i++) {
		if (nfsd_vers(nn, i, NFSD_TEST)) {
			ret->mismatch.lovers = i;
			break;
		}
	}
	if (ret->mismatch.lovers == NFSD_NRVERS)
		return rpc_prog_unavail;
	ret->mismatch.hivers = NFSD_MINVERS;
	for (i = NFSD_NRVERS - 1; i >= NFSD_MINVERS; i--) {
		if (nfsd_vers(nn, i, NFSD_TEST)) {
			ret->mismatch.hivers = i;
			break;
		}
	}
	return rpc_prog_mismatch;
}

/*
 * This is the NFS server kernel thread
 */
static int
nfsd(void *vrqstp)
{
	struct svc_rqst *rqstp = (struct svc_rqst *) vrqstp;
	struct svc_xprt *perm_sock = list_entry(rqstp->rq_server->sv_permsocks.next, typeof(struct svc_xprt), xpt_list);
	struct net *net = perm_sock->xpt_net;
	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
	int err;

	/* At this point, the thread shares current->fs
	 * with the init process. We need to create files with the
	 * umask as defined by the client instead of init's umask. */
	if (unshare_fs_struct() < 0) {
		printk("Unable to start nfsd thread: out of memory\n");
		goto out;
	}

	current->fs->umask = 0;

	/*
	 * thread is spawned with all signals set to SIG_IGN, re-enable
	 * the ones that will bring down the thread
	 */
	allow_signal(SIGKILL);
	allow_signal(SIGHUP);
	allow_signal(SIGINT);
	allow_signal(SIGQUIT);

	atomic_inc(&nfsdstats.th_cnt);

	set_freezable();

	/*
	 * The main request loop
	 */
	for (;;) {
		/* Update sv_maxconn if it has changed */
		rqstp->rq_server->sv_maxconn = nn->max_connections;

		/*
		 * Find a socket with data available and call its
		 * recvfrom routine.
		 */
		while ((err = svc_recv(rqstp, 60*60*HZ)) == -EAGAIN)
			;
		if (err == -EINTR)
			break;
		validate_process_creds();
		svc_process(rqstp);
		validate_process_creds();
	}

	/* Clear signals before calling svc_exit_thread() */
	flush_signals(current);

	atomic_dec(&nfsdstats.th_cnt);

out:
	/* Take an extra ref so that the svc_put in svc_exit_thread()
	 * doesn't call svc_destroy()
	 */
	svc_get(nn->nfsd_serv);

	/* Release the thread */
	svc_exit_thread(rqstp);

	/* We need to drop a ref, but may not drop the last reference
	 * without holding nfsd_mutex, and we cannot wait for nfsd_mutex as that
	 * could deadlock with nfsd_shutdown_threads() waiting for us.
	 * So three options are:
	 * - drop a non-final reference,
	 * - get the mutex without waiting
	 * - sleep briefly andd try the above again
	 */
	while (!svc_put_not_last(nn->nfsd_serv)) {
		if (mutex_trylock(&nfsd_mutex)) {
			nfsd_put(net);
			mutex_unlock(&nfsd_mutex);
			break;
		}
		msleep(20);
	}

	/* Release module */
	module_put_and_exit(0);
	return 0;
}

/**
 * nfsd_dispatch - Process an NFS or NFSACL Request
 * @rqstp: incoming request
 * @statp: pointer to location of accept_stat field in RPC Reply buffer
 *
 * This RPC dispatcher integrates the NFS server's duplicate reply cache.
 *
 * Return values:
 *  %0: Processing complete; do not send a Reply
 *  %1: Processing complete; send Reply in rqstp->rq_res
 */
int nfsd_dispatch(struct svc_rqst *rqstp, __be32 *statp)
{
	const struct svc_procedure *proc = rqstp->rq_procinfo;

	/*
	 * Give the xdr decoder a chance to change this if it wants
	 * (necessary in the NFSv4.0 compound case)
	 */
	rqstp->rq_cachetype = proc->pc_cachetype;

	svcxdr_init_decode(rqstp);
	if (!proc->pc_decode(rqstp, &rqstp->rq_arg_stream))
		goto out_decode_err;

	switch (nfsd_cache_lookup(rqstp)) {
	case RC_DOIT:
		break;
	case RC_REPLY:
		goto out_cached_reply;
	case RC_DROPIT:
		goto out_dropit;
	}

	/*
	 * Need to grab the location to store the status, as
	 * NFSv4 does some encoding while processing
	 */
	svcxdr_init_encode(rqstp);

	*statp = proc->pc_func(rqstp);
	if (*statp == rpc_drop_reply || test_bit(RQ_DROPME, &rqstp->rq_flags))
		goto out_update_drop;

	if (!proc->pc_encode(rqstp, &rqstp->rq_res_stream))
		goto out_encode_err;

	nfsd_cache_update(rqstp, rqstp->rq_cachetype, statp + 1);
out_cached_reply:
	return 1;

out_decode_err:
	trace_nfsd_garbage_args_err(rqstp);
	*statp = rpc_garbage_args;
	return 1;

out_update_drop:
	nfsd_cache_update(rqstp, RC_NOCACHE, NULL);
out_dropit:
	return 0;

out_encode_err:
	trace_nfsd_cant_encode_err(rqstp);
	nfsd_cache_update(rqstp, RC_NOCACHE, NULL);
	*statp = rpc_system_err;
	return 1;
}

/**
 * nfssvc_decode_voidarg - Decode void arguments
 * @rqstp: Server RPC transaction context
 * @xdr: XDR stream positioned at arguments to decode
 *
 * Return values:
 *   %false: Arguments were not valid
 *   %true: Decoding was successful
 */
bool nfssvc_decode_voidarg(struct svc_rqst *rqstp, struct xdr_stream *xdr)
{
	return true;
}

/**
 * nfssvc_encode_voidres - Encode void results
 * @rqstp: Server RPC transaction context
 * @xdr: XDR stream into which to encode results
 *
 * Return values:
 *   %false: Local error while encoding
 *   %true: Encoding was successful
 */
bool nfssvc_encode_voidres(struct svc_rqst *rqstp, struct xdr_stream *xdr)
{
	return true;
}

int nfsd_pool_stats_open(struct inode *inode, struct file *file)
{
	int ret;
	struct nfsd_net *nn = net_generic(inode->i_sb->s_fs_info, nfsd_net_id);

	mutex_lock(&nfsd_mutex);
	if (nn->nfsd_serv == NULL) {
		mutex_unlock(&nfsd_mutex);
		return -ENODEV;
	}
	svc_get(nn->nfsd_serv);
	ret = svc_pool_stats_open(nn->nfsd_serv, file);
	mutex_unlock(&nfsd_mutex);
	return ret;
}

int nfsd_pool_stats_release(struct inode *inode, struct file *file)
{
	int ret = seq_release(inode, file);
	struct net *net = inode->i_sb->s_fs_info;

	mutex_lock(&nfsd_mutex);
	nfsd_put(net);
	mutex_unlock(&nfsd_mutex);
	return ret;
}