summaryrefslogtreecommitdiff
path: root/net/sunrpc/xprtsock.c
blob: 2e1529217e656a380b9d934917561959b58c5ad0 (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
/*
 * linux/net/sunrpc/xprtsock.c
 *
 * Client-side transport implementation for sockets.
 *
 * TCP callback races fixes (C) 1998 Red Hat Software <alan@redhat.com>
 * TCP send fixes (C) 1998 Red Hat Software <alan@redhat.com>
 * TCP NFS related read + write fixes
 *  (C) 1999 Dave Airlie, University of Limerick, Ireland <airlied@linux.ie>
 *
 * Rewrite of larges part of the code in order to stabilize TCP stuff.
 * Fix behaviour when socket buffer is full.
 *  (C) 1999 Trond Myklebust <trond.myklebust@fys.uio.no>
 *
 * IP socket transport implementation, (C) 2005 Chuck Lever <cel@netapp.com>
 */

#include <linux/types.h>
#include <linux/slab.h>
#include <linux/capability.h>
#include <linux/sched.h>
#include <linux/pagemap.h>
#include <linux/errno.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/net.h>
#include <linux/mm.h>
#include <linux/udp.h>
#include <linux/tcp.h>
#include <linux/sunrpc/clnt.h>
#include <linux/file.h>

#include <net/sock.h>
#include <net/checksum.h>
#include <net/udp.h>
#include <net/tcp.h>

/*
 * How many times to try sending a request on a socket before waiting
 * for the socket buffer to clear.
 */
#define XS_SENDMSG_RETRY	(10U)

/*
 * Time out for an RPC UDP socket connect.  UDP socket connects are
 * synchronous, but we set a timeout anyway in case of resource
 * exhaustion on the local host.
 */
#define XS_UDP_CONN_TO		(5U * HZ)

/*
 * Wait duration for an RPC TCP connection to be established.  Solaris
 * NFS over TCP uses 60 seconds, for example, which is in line with how
 * long a server takes to reboot.
 */
#define XS_TCP_CONN_TO		(60U * HZ)

/*
 * Wait duration for a reply from the RPC portmapper.
 */
#define XS_BIND_TO		(60U * HZ)

/*
 * Delay if a UDP socket connect error occurs.  This is most likely some
 * kind of resource problem on the local host.
 */
#define XS_UDP_REEST_TO		(2U * HZ)

/*
 * The reestablish timeout allows clients to delay for a bit before attempting
 * to reconnect to a server that just dropped our connection.
 *
 * We implement an exponential backoff when trying to reestablish a TCP
 * transport connection with the server.  Some servers like to drop a TCP
 * connection when they are overworked, so we start with a short timeout and
 * increase over time if the server is down or not responding.
 */
#define XS_TCP_INIT_REEST_TO	(3U * HZ)
#define XS_TCP_MAX_REEST_TO	(5U * 60 * HZ)

/*
 * TCP idle timeout; client drops the transport socket if it is idle
 * for this long.  Note that we also timeout UDP sockets to prevent
 * holding port numbers when there is no RPC traffic.
 */
#define XS_IDLE_DISC_TO		(5U * 60 * HZ)

#ifdef RPC_DEBUG
# undef  RPC_DEBUG_DATA
# define RPCDBG_FACILITY	RPCDBG_TRANS
#endif

#ifdef RPC_DEBUG_DATA
static void xs_pktdump(char *msg, u32 *packet, unsigned int count)
{
	u8 *buf = (u8 *) packet;
	int j;

	dprintk("RPC:      %s\n", msg);
	for (j = 0; j < count && j < 128; j += 4) {
		if (!(j & 31)) {
			if (j)
				dprintk("\n");
			dprintk("0x%04x ", j);
		}
		dprintk("%02x%02x%02x%02x ",
			buf[j], buf[j+1], buf[j+2], buf[j+3]);
	}
	dprintk("\n");
}
#else
static inline void xs_pktdump(char *msg, u32 *packet, unsigned int count)
{
	/* NOP */
}
#endif

#define XS_SENDMSG_FLAGS	(MSG_DONTWAIT | MSG_NOSIGNAL)

static inline int xs_send_head(struct socket *sock, struct sockaddr *addr, int addrlen, struct xdr_buf *xdr, unsigned int base, unsigned int len)
{
	struct kvec iov = {
		.iov_base	= xdr->head[0].iov_base + base,
		.iov_len	= len - base,
	};
	struct msghdr msg = {
		.msg_name	= addr,
		.msg_namelen	= addrlen,
		.msg_flags	= XS_SENDMSG_FLAGS,
	};

	if (xdr->len > len)
		msg.msg_flags |= MSG_MORE;

	if (likely(iov.iov_len))
		return kernel_sendmsg(sock, &msg, &iov, 1, iov.iov_len);
	return kernel_sendmsg(sock, &msg, NULL, 0, 0);
}

static int xs_send_tail(struct socket *sock, struct xdr_buf *xdr, unsigned int base, unsigned int len)
{
	struct kvec iov = {
		.iov_base	= xdr->tail[0].iov_base + base,
		.iov_len	= len - base,
	};
	struct msghdr msg = {
		.msg_flags	= XS_SENDMSG_FLAGS,
	};

	return kernel_sendmsg(sock, &msg, &iov, 1, iov.iov_len);
}

/**
 * xs_sendpages - write pages directly to a socket
 * @sock: socket to send on
 * @addr: UDP only -- address of destination
 * @addrlen: UDP only -- length of destination address
 * @xdr: buffer containing this request
 * @base: starting position in the buffer
 *
 */
static inline int xs_sendpages(struct socket *sock, struct sockaddr *addr, int addrlen, struct xdr_buf *xdr, unsigned int base)
{
	struct page **ppage = xdr->pages;
	unsigned int len, pglen = xdr->page_len;
	int err, ret = 0;
	ssize_t (*sendpage)(struct socket *, struct page *, int, size_t, int);

	if (unlikely(!sock))
		return -ENOTCONN;

	clear_bit(SOCK_ASYNC_NOSPACE, &sock->flags);

	len = xdr->head[0].iov_len;
	if (base < len || (addr != NULL && base == 0)) {
		err = xs_send_head(sock, addr, addrlen, xdr, base, len);
		if (ret == 0)
			ret = err;
		else if (err > 0)
			ret += err;
		if (err != (len - base))
			goto out;
		base = 0;
	} else
		base -= len;

	if (unlikely(pglen == 0))
		goto copy_tail;
	if (unlikely(base >= pglen)) {
		base -= pglen;
		goto copy_tail;
	}
	if (base || xdr->page_base) {
		pglen -= base;
		base += xdr->page_base;
		ppage += base >> PAGE_CACHE_SHIFT;
		base &= ~PAGE_CACHE_MASK;
	}

	sendpage = sock->ops->sendpage ? : sock_no_sendpage;
	do {
		int flags = XS_SENDMSG_FLAGS;

		len = PAGE_CACHE_SIZE;
		if (base)
			len -= base;
		if (pglen < len)
			len = pglen;

		if (pglen != len || xdr->tail[0].iov_len != 0)
			flags |= MSG_MORE;

		/* Hmm... We might be dealing with highmem pages */
		if (PageHighMem(*ppage))
			sendpage = sock_no_sendpage;
		err = sendpage(sock, *ppage, base, len, flags);
		if (ret == 0)
			ret = err;
		else if (err > 0)
			ret += err;
		if (err != len)
			goto out;
		base = 0;
		ppage++;
	} while ((pglen -= len) != 0);
copy_tail:
	len = xdr->tail[0].iov_len;
	if (base < len) {
		err = xs_send_tail(sock, xdr, base, len);
		if (ret == 0)
			ret = err;
		else if (err > 0)
			ret += err;
	}
out:
	return ret;
}

/**
 * xs_nospace - place task on wait queue if transmit was incomplete
 * @task: task to put to sleep
 *
 */
static void xs_nospace(struct rpc_task *task)
{
	struct rpc_rqst *req = task->tk_rqstp;
	struct rpc_xprt *xprt = req->rq_xprt;

	dprintk("RPC: %4d xmit incomplete (%u left of %u)\n",
			task->tk_pid, req->rq_slen - req->rq_bytes_sent,
			req->rq_slen);

	if (test_bit(SOCK_ASYNC_NOSPACE, &xprt->sock->flags)) {
		/* Protect against races with write_space */
		spin_lock_bh(&xprt->transport_lock);

		/* Don't race with disconnect */
		if (!xprt_connected(xprt))
			task->tk_status = -ENOTCONN;
		else if (test_bit(SOCK_NOSPACE, &xprt->sock->flags))
			xprt_wait_for_buffer_space(task);

		spin_unlock_bh(&xprt->transport_lock);
	} else
		/* Keep holding the socket if it is blocked */
		rpc_delay(task, HZ>>4);
}

/**
 * xs_udp_send_request - write an RPC request to a UDP socket
 * @task: address of RPC task that manages the state of an RPC request
 *
 * Return values:
 *        0:	The request has been sent
 *   EAGAIN:	The socket was blocked, please call again later to
 *		complete the request
 * ENOTCONN:	Caller needs to invoke connect logic then call again
 *    other:	Some other error occured, the request was not sent
 */
static int xs_udp_send_request(struct rpc_task *task)
{
	struct rpc_rqst *req = task->tk_rqstp;
	struct rpc_xprt *xprt = req->rq_xprt;
	struct xdr_buf *xdr = &req->rq_snd_buf;
	int status;

	xs_pktdump("packet data:",
				req->rq_svec->iov_base,
				req->rq_svec->iov_len);

	req->rq_xtime = jiffies;
	status = xs_sendpages(xprt->sock, (struct sockaddr *) &xprt->addr,
				sizeof(xprt->addr), xdr, req->rq_bytes_sent);

	dprintk("RPC:      xs_udp_send_request(%u) = %d\n",
			xdr->len - req->rq_bytes_sent, status);

	if (likely(status >= (int) req->rq_slen))
		return 0;

	/* Still some bytes left; set up for a retry later. */
	if (status > 0)
		status = -EAGAIN;

	switch (status) {
	case -ENETUNREACH:
	case -EPIPE:
	case -ECONNREFUSED:
		/* When the server has died, an ICMP port unreachable message
		 * prompts ECONNREFUSED. */
		break;
	case -EAGAIN:
		xs_nospace(task);
		break;
	default:
		dprintk("RPC:      sendmsg returned unrecognized error %d\n",
			-status);
		break;
	}

	return status;
}

static inline void xs_encode_tcp_record_marker(struct xdr_buf *buf)
{
	u32 reclen = buf->len - sizeof(rpc_fraghdr);
	rpc_fraghdr *base = buf->head[0].iov_base;
	*base = htonl(RPC_LAST_STREAM_FRAGMENT | reclen);
}

/**
 * xs_tcp_send_request - write an RPC request to a TCP socket
 * @task: address of RPC task that manages the state of an RPC request
 *
 * Return values:
 *        0:	The request has been sent
 *   EAGAIN:	The socket was blocked, please call again later to
 *		complete the request
 * ENOTCONN:	Caller needs to invoke connect logic then call again
 *    other:	Some other error occured, the request was not sent
 *
 * XXX: In the case of soft timeouts, should we eventually give up
 *	if sendmsg is not able to make progress?
 */
static int xs_tcp_send_request(struct rpc_task *task)
{
	struct rpc_rqst *req = task->tk_rqstp;
	struct rpc_xprt *xprt = req->rq_xprt;
	struct xdr_buf *xdr = &req->rq_snd_buf;
	int status, retry = 0;

	xs_encode_tcp_record_marker(&req->rq_snd_buf);

	xs_pktdump("packet data:",
				req->rq_svec->iov_base,
				req->rq_svec->iov_len);

	/* Continue transmitting the packet/record. We must be careful
	 * to cope with writespace callbacks arriving _after_ we have
	 * called sendmsg(). */
	while (1) {
		req->rq_xtime = jiffies;
		status = xs_sendpages(xprt->sock, NULL, 0, xdr,
						req->rq_bytes_sent);

		dprintk("RPC:      xs_tcp_send_request(%u) = %d\n",
				xdr->len - req->rq_bytes_sent, status);

		if (unlikely(status < 0))
			break;

		/* If we've sent the entire packet, immediately
		 * reset the count of bytes sent. */
		req->rq_bytes_sent += status;
		if (likely(req->rq_bytes_sent >= req->rq_slen)) {
			req->rq_bytes_sent = 0;
			return 0;
		}

		status = -EAGAIN;
		if (retry++ > XS_SENDMSG_RETRY)
			break;
	}

	switch (status) {
	case -EAGAIN:
		xs_nospace(task);
		break;
	case -ECONNREFUSED:
	case -ECONNRESET:
	case -ENOTCONN:
	case -EPIPE:
		status = -ENOTCONN;
		break;
	default:
		dprintk("RPC:      sendmsg returned unrecognized error %d\n",
			-status);
		xprt_disconnect(xprt);
		break;
	}

	return status;
}

/**
 * xs_close - close a socket
 * @xprt: transport
 *
 * This is used when all requests are complete; ie, no DRC state remains
 * on the server we want to save.
 */
static void xs_close(struct rpc_xprt *xprt)
{
	struct socket *sock = xprt->sock;
	struct sock *sk = xprt->inet;

	if (!sk)
		return;

	dprintk("RPC:      xs_close xprt %p\n", xprt);

	write_lock_bh(&sk->sk_callback_lock);
	xprt->inet = NULL;
	xprt->sock = NULL;

	sk->sk_user_data = NULL;
	sk->sk_data_ready = xprt->old_data_ready;
	sk->sk_state_change = xprt->old_state_change;
	sk->sk_write_space = xprt->old_write_space;
	write_unlock_bh(&sk->sk_callback_lock);

	sk->sk_no_check = 0;

	sock_release(sock);
}

/**
 * xs_destroy - prepare to shutdown a transport
 * @xprt: doomed transport
 *
 */
static void xs_destroy(struct rpc_xprt *xprt)
{
	dprintk("RPC:      xs_destroy xprt %p\n", xprt);

	cancel_delayed_work(&xprt->connect_worker);
	flush_scheduled_work();

	xprt_disconnect(xprt);
	xs_close(xprt);
	kfree(xprt->slot);
}

static inline struct rpc_xprt *xprt_from_sock(struct sock *sk)
{
	return (struct rpc_xprt *) sk->sk_user_data;
}

/**
 * xs_udp_data_ready - "data ready" callback for UDP sockets
 * @sk: socket with data to read
 * @len: how much data to read
 *
 */
static void xs_udp_data_ready(struct sock *sk, int len)
{
	struct rpc_task *task;
	struct rpc_xprt *xprt;
	struct rpc_rqst *rovr;
	struct sk_buff *skb;
	int err, repsize, copied;
	u32 _xid, *xp;

	read_lock(&sk->sk_callback_lock);
	dprintk("RPC:      xs_udp_data_ready...\n");
	if (!(xprt = xprt_from_sock(sk)))
		goto out;

	if ((skb = skb_recv_datagram(sk, 0, 1, &err)) == NULL)
		goto out;

	if (xprt->shutdown)
		goto dropit;

	repsize = skb->len - sizeof(struct udphdr);
	if (repsize < 4) {
		dprintk("RPC:      impossible RPC reply size %d!\n", repsize);
		goto dropit;
	}

	/* Copy the XID from the skb... */
	xp = skb_header_pointer(skb, sizeof(struct udphdr),
				sizeof(_xid), &_xid);
	if (xp == NULL)
		goto dropit;

	/* Look up and lock the request corresponding to the given XID */
	spin_lock(&xprt->transport_lock);
	rovr = xprt_lookup_rqst(xprt, *xp);
	if (!rovr)
		goto out_unlock;
	task = rovr->rq_task;

	if ((copied = rovr->rq_private_buf.buflen) > repsize)
		copied = repsize;

	/* Suck it into the iovec, verify checksum if not done by hw. */
	if (csum_partial_copy_to_xdr(&rovr->rq_private_buf, skb))
		goto out_unlock;

	/* Something worked... */
	dst_confirm(skb->dst);

	xprt_adjust_cwnd(task, copied);
	xprt_update_rtt(task);
	xprt_complete_rqst(task, copied);

 out_unlock:
	spin_unlock(&xprt->transport_lock);
 dropit:
	skb_free_datagram(sk, skb);
 out:
	read_unlock(&sk->sk_callback_lock);
}

static inline size_t xs_tcp_copy_data(skb_reader_t *desc, void *p, size_t len)
{
	if (len > desc->count)
		len = desc->count;
	if (skb_copy_bits(desc->skb, desc->offset, p, len)) {
		dprintk("RPC:      failed to copy %zu bytes from skb. %zu bytes remain\n",
				len, desc->count);
		return 0;
	}
	desc->offset += len;
	desc->count -= len;
	dprintk("RPC:      copied %zu bytes from skb. %zu bytes remain\n",
			len, desc->count);
	return len;
}

static inline void xs_tcp_read_fraghdr(struct rpc_xprt *xprt, skb_reader_t *desc)
{
	size_t len, used;
	char *p;

	p = ((char *) &xprt->tcp_recm) + xprt->tcp_offset;
	len = sizeof(xprt->tcp_recm) - xprt->tcp_offset;
	used = xs_tcp_copy_data(desc, p, len);
	xprt->tcp_offset += used;
	if (used != len)
		return;

	xprt->tcp_reclen = ntohl(xprt->tcp_recm);
	if (xprt->tcp_reclen & RPC_LAST_STREAM_FRAGMENT)
		xprt->tcp_flags |= XPRT_LAST_FRAG;
	else
		xprt->tcp_flags &= ~XPRT_LAST_FRAG;
	xprt->tcp_reclen &= RPC_FRAGMENT_SIZE_MASK;

	xprt->tcp_flags &= ~XPRT_COPY_RECM;
	xprt->tcp_offset = 0;

	/* Sanity check of the record length */
	if (unlikely(xprt->tcp_reclen < 4)) {
		dprintk("RPC:      invalid TCP record fragment length\n");
		xprt_disconnect(xprt);
		return;
	}
	dprintk("RPC:      reading TCP record fragment of length %d\n",
			xprt->tcp_reclen);
}

static void xs_tcp_check_recm(struct rpc_xprt *xprt)
{
	dprintk("RPC:      xprt = %p, tcp_copied = %lu, tcp_offset = %u, tcp_reclen = %u, tcp_flags = %lx\n",
			xprt, xprt->tcp_copied, xprt->tcp_offset, xprt->tcp_reclen, xprt->tcp_flags);
	if (xprt->tcp_offset == xprt->tcp_reclen) {
		xprt->tcp_flags |= XPRT_COPY_RECM;
		xprt->tcp_offset = 0;
		if (xprt->tcp_flags & XPRT_LAST_FRAG) {
			xprt->tcp_flags &= ~XPRT_COPY_DATA;
			xprt->tcp_flags |= XPRT_COPY_XID;
			xprt->tcp_copied = 0;
		}
	}
}

static inline void xs_tcp_read_xid(struct rpc_xprt *xprt, skb_reader_t *desc)
{
	size_t len, used;
	char *p;

	len = sizeof(xprt->tcp_xid) - xprt->tcp_offset;
	dprintk("RPC:      reading XID (%Zu bytes)\n", len);
	p = ((char *) &xprt->tcp_xid) + xprt->tcp_offset;
	used = xs_tcp_copy_data(desc, p, len);
	xprt->tcp_offset += used;
	if (used != len)
		return;
	xprt->tcp_flags &= ~XPRT_COPY_XID;
	xprt->tcp_flags |= XPRT_COPY_DATA;
	xprt->tcp_copied = 4;
	dprintk("RPC:      reading reply for XID %08x\n",
						ntohl(xprt->tcp_xid));
	xs_tcp_check_recm(xprt);
}

static inline void xs_tcp_read_request(struct rpc_xprt *xprt, skb_reader_t *desc)
{
	struct rpc_rqst *req;
	struct xdr_buf *rcvbuf;
	size_t len;
	ssize_t r;

	/* Find and lock the request corresponding to this xid */
	spin_lock(&xprt->transport_lock);
	req = xprt_lookup_rqst(xprt, xprt->tcp_xid);
	if (!req) {
		xprt->tcp_flags &= ~XPRT_COPY_DATA;
		dprintk("RPC:      XID %08x request not found!\n",
				ntohl(xprt->tcp_xid));
		spin_unlock(&xprt->transport_lock);
		return;
	}

	rcvbuf = &req->rq_private_buf;
	len = desc->count;
	if (len > xprt->tcp_reclen - xprt->tcp_offset) {
		skb_reader_t my_desc;

		len = xprt->tcp_reclen - xprt->tcp_offset;
		memcpy(&my_desc, desc, sizeof(my_desc));
		my_desc.count = len;
		r = xdr_partial_copy_from_skb(rcvbuf, xprt->tcp_copied,
					  &my_desc, xs_tcp_copy_data);
		desc->count -= r;
		desc->offset += r;
	} else
		r = xdr_partial_copy_from_skb(rcvbuf, xprt->tcp_copied,
					  desc, xs_tcp_copy_data);

	if (r > 0) {
		xprt->tcp_copied += r;
		xprt->tcp_offset += r;
	}
	if (r != len) {
		/* Error when copying to the receive buffer,
		 * usually because we weren't able to allocate
		 * additional buffer pages. All we can do now
		 * is turn off XPRT_COPY_DATA, so the request
		 * will not receive any additional updates,
		 * and time out.
		 * Any remaining data from this record will
		 * be discarded.
		 */
		xprt->tcp_flags &= ~XPRT_COPY_DATA;
		dprintk("RPC:      XID %08x truncated request\n",
				ntohl(xprt->tcp_xid));
		dprintk("RPC:      xprt = %p, tcp_copied = %lu, tcp_offset = %u, tcp_reclen = %u\n",
				xprt, xprt->tcp_copied, xprt->tcp_offset, xprt->tcp_reclen);
		goto out;
	}

	dprintk("RPC:      XID %08x read %Zd bytes\n",
			ntohl(xprt->tcp_xid), r);
	dprintk("RPC:      xprt = %p, tcp_copied = %lu, tcp_offset = %u, tcp_reclen = %u\n",
			xprt, xprt->tcp_copied, xprt->tcp_offset, xprt->tcp_reclen);

	if (xprt->tcp_copied == req->rq_private_buf.buflen)
		xprt->tcp_flags &= ~XPRT_COPY_DATA;
	else if (xprt->tcp_offset == xprt->tcp_reclen) {
		if (xprt->tcp_flags & XPRT_LAST_FRAG)
			xprt->tcp_flags &= ~XPRT_COPY_DATA;
	}

out:
	if (!(xprt->tcp_flags & XPRT_COPY_DATA))
		xprt_complete_rqst(req->rq_task, xprt->tcp_copied);
	spin_unlock(&xprt->transport_lock);
	xs_tcp_check_recm(xprt);
}

static inline void xs_tcp_read_discard(struct rpc_xprt *xprt, skb_reader_t *desc)
{
	size_t len;

	len = xprt->tcp_reclen - xprt->tcp_offset;
	if (len > desc->count)
		len = desc->count;
	desc->count -= len;
	desc->offset += len;
	xprt->tcp_offset += len;
	dprintk("RPC:      discarded %Zu bytes\n", len);
	xs_tcp_check_recm(xprt);
}

static int xs_tcp_data_recv(read_descriptor_t *rd_desc, struct sk_buff *skb, unsigned int offset, size_t len)
{
	struct rpc_xprt *xprt = rd_desc->arg.data;
	skb_reader_t desc = {
		.skb	= skb,
		.offset	= offset,
		.count	= len,
		.csum	= 0
	};

	dprintk("RPC:      xs_tcp_data_recv started\n");
	do {
		/* Read in a new fragment marker if necessary */
		/* Can we ever really expect to get completely empty fragments? */
		if (xprt->tcp_flags & XPRT_COPY_RECM) {
			xs_tcp_read_fraghdr(xprt, &desc);
			continue;
		}
		/* Read in the xid if necessary */
		if (xprt->tcp_flags & XPRT_COPY_XID) {
			xs_tcp_read_xid(xprt, &desc);
			continue;
		}
		/* Read in the request data */
		if (xprt->tcp_flags & XPRT_COPY_DATA) {
			xs_tcp_read_request(xprt, &desc);
			continue;
		}
		/* Skip over any trailing bytes on short reads */
		xs_tcp_read_discard(xprt, &desc);
	} while (desc.count);
	dprintk("RPC:      xs_tcp_data_recv done\n");
	return len - desc.count;
}

/**
 * xs_tcp_data_ready - "data ready" callback for TCP sockets
 * @sk: socket with data to read
 * @bytes: how much data to read
 *
 */
static void xs_tcp_data_ready(struct sock *sk, int bytes)
{
	struct rpc_xprt *xprt;
	read_descriptor_t rd_desc;

	read_lock(&sk->sk_callback_lock);
	dprintk("RPC:      xs_tcp_data_ready...\n");
	if (!(xprt = xprt_from_sock(sk)))
		goto out;
	if (xprt->shutdown)
		goto out;

	/* We use rd_desc to pass struct xprt to xs_tcp_data_recv */
	rd_desc.arg.data = xprt;
	rd_desc.count = 65536;
	tcp_read_sock(sk, &rd_desc, xs_tcp_data_recv);
out:
	read_unlock(&sk->sk_callback_lock);
}

/**
 * xs_tcp_state_change - callback to handle TCP socket state changes
 * @sk: socket whose state has changed
 *
 */
static void xs_tcp_state_change(struct sock *sk)
{
	struct rpc_xprt *xprt;

	read_lock(&sk->sk_callback_lock);
	if (!(xprt = xprt_from_sock(sk)))
		goto out;
	dprintk("RPC:      xs_tcp_state_change client %p...\n", xprt);
	dprintk("RPC:      state %x conn %d dead %d zapped %d\n",
				sk->sk_state, xprt_connected(xprt),
				sock_flag(sk, SOCK_DEAD),
				sock_flag(sk, SOCK_ZAPPED));

	switch (sk->sk_state) {
	case TCP_ESTABLISHED:
		spin_lock_bh(&xprt->transport_lock);
		if (!xprt_test_and_set_connected(xprt)) {
			/* Reset TCP record info */
			xprt->tcp_offset = 0;
			xprt->tcp_reclen = 0;
			xprt->tcp_copied = 0;
			xprt->tcp_flags = XPRT_COPY_RECM | XPRT_COPY_XID;
			xprt->reestablish_timeout = XS_TCP_INIT_REEST_TO;
			xprt_wake_pending_tasks(xprt, 0);
		}
		spin_unlock_bh(&xprt->transport_lock);
		break;
	case TCP_SYN_SENT:
	case TCP_SYN_RECV:
		break;
	default:
		xprt_disconnect(xprt);
		break;
	}
 out:
	read_unlock(&sk->sk_callback_lock);
}

/**
 * xs_udp_write_space - callback invoked when socket buffer space
 *                             becomes available
 * @sk: socket whose state has changed
 *
 * Called when more output buffer space is available for this socket.
 * We try not to wake our writers until they can make "significant"
 * progress, otherwise we'll waste resources thrashing kernel_sendmsg
 * with a bunch of small requests.
 */
static void xs_udp_write_space(struct sock *sk)
{
	read_lock(&sk->sk_callback_lock);

	/* from net/core/sock.c:sock_def_write_space */
	if (sock_writeable(sk)) {
		struct socket *sock;
		struct rpc_xprt *xprt;

		if (unlikely(!(sock = sk->sk_socket)))
			goto out;
		if (unlikely(!(xprt = xprt_from_sock(sk))))
			goto out;
		if (unlikely(!test_and_clear_bit(SOCK_NOSPACE, &sock->flags)))
			goto out;

		xprt_write_space(xprt);
	}

 out:
	read_unlock(&sk->sk_callback_lock);
}

/**
 * xs_tcp_write_space - callback invoked when socket buffer space
 *                             becomes available
 * @sk: socket whose state has changed
 *
 * Called when more output buffer space is available for this socket.
 * We try not to wake our writers until they can make "significant"
 * progress, otherwise we'll waste resources thrashing kernel_sendmsg
 * with a bunch of small requests.
 */
static void xs_tcp_write_space(struct sock *sk)
{
	read_lock(&sk->sk_callback_lock);

	/* from net/core/stream.c:sk_stream_write_space */
	if (sk_stream_wspace(sk) >= sk_stream_min_wspace(sk)) {
		struct socket *sock;
		struct rpc_xprt *xprt;

		if (unlikely(!(sock = sk->sk_socket)))
			goto out;
		if (unlikely(!(xprt = xprt_from_sock(sk))))
			goto out;
		if (unlikely(!test_and_clear_bit(SOCK_NOSPACE, &sock->flags)))
			goto out;

		xprt_write_space(xprt);
	}

 out:
	read_unlock(&sk->sk_callback_lock);
}

static void xs_udp_do_set_buffer_size(struct rpc_xprt *xprt)
{
	struct sock *sk = xprt->inet;

	if (xprt->rcvsize) {
		sk->sk_userlocks |= SOCK_RCVBUF_LOCK;
		sk->sk_rcvbuf = xprt->rcvsize * xprt->max_reqs *  2;
	}
	if (xprt->sndsize) {
		sk->sk_userlocks |= SOCK_SNDBUF_LOCK;
		sk->sk_sndbuf = xprt->sndsize * xprt->max_reqs * 2;
		sk->sk_write_space(sk);
	}
}

/**
 * xs_udp_set_buffer_size - set send and receive limits
 * @xprt: generic transport
 * @sndsize: requested size of send buffer, in bytes
 * @rcvsize: requested size of receive buffer, in bytes
 *
 * Set socket send and receive buffer size limits.
 */
static void xs_udp_set_buffer_size(struct rpc_xprt *xprt, size_t sndsize, size_t rcvsize)
{
	xprt->sndsize = 0;
	if (sndsize)
		xprt->sndsize = sndsize + 1024;
	xprt->rcvsize = 0;
	if (rcvsize)
		xprt->rcvsize = rcvsize + 1024;

	xs_udp_do_set_buffer_size(xprt);
}

/**
 * xs_udp_timer - called when a retransmit timeout occurs on a UDP transport
 * @task: task that timed out
 *
 * Adjust the congestion window after a retransmit timeout has occurred.
 */
static void xs_udp_timer(struct rpc_task *task)
{
	xprt_adjust_cwnd(task, -ETIMEDOUT);
}

static int xs_bindresvport(struct rpc_xprt *xprt, struct socket *sock)
{
	struct sockaddr_in myaddr = {
		.sin_family = AF_INET,
	};
	int err;
	unsigned short port = xprt->port;

	do {
		myaddr.sin_port = htons(port);
		err = sock->ops->bind(sock, (struct sockaddr *) &myaddr,
						sizeof(myaddr));
		if (err == 0) {
			xprt->port = port;
			dprintk("RPC:      xs_bindresvport bound to port %u\n",
					port);
			return 0;
		}
		if (port <= xprt_min_resvport)
			port = xprt_max_resvport;
		else
			port--;
	} while (err == -EADDRINUSE && port != xprt->port);

	dprintk("RPC:      can't bind to reserved port (%d).\n", -err);
	return err;
}

/**
 * xs_udp_connect_worker - set up a UDP socket
 * @args: RPC transport to connect
 *
 * Invoked by a work queue tasklet.
 */
static void xs_udp_connect_worker(void *args)
{
	struct rpc_xprt *xprt = (struct rpc_xprt *) args;
	struct socket *sock = xprt->sock;
	int err, status = -EIO;

	if (xprt->shutdown || xprt->addr.sin_port == 0)
		goto out;

	dprintk("RPC:      xs_udp_connect_worker for xprt %p\n", xprt);

	/* Start by resetting any existing state */
	xs_close(xprt);

	if ((err = sock_create_kern(PF_INET, SOCK_DGRAM, IPPROTO_UDP, &sock)) < 0) {
		dprintk("RPC:      can't create UDP transport socket (%d).\n", -err);
		goto out;
	}

	if (xprt->resvport && xs_bindresvport(xprt, sock) < 0) {
		sock_release(sock);
		goto out;
	}

	if (!xprt->inet) {
		struct sock *sk = sock->sk;

		write_lock_bh(&sk->sk_callback_lock);

		sk->sk_user_data = xprt;
		xprt->old_data_ready = sk->sk_data_ready;
		xprt->old_state_change = sk->sk_state_change;
		xprt->old_write_space = sk->sk_write_space;
		sk->sk_data_ready = xs_udp_data_ready;
		sk->sk_write_space = xs_udp_write_space;
		sk->sk_no_check = UDP_CSUM_NORCV;

		xprt_set_connected(xprt);

		/* Reset to new socket */
		xprt->sock = sock;
		xprt->inet = sk;

		write_unlock_bh(&sk->sk_callback_lock);
	}
	xs_udp_do_set_buffer_size(xprt);
	status = 0;
out:
	xprt_wake_pending_tasks(xprt, status);
	xprt_clear_connecting(xprt);
}

/*
 * We need to preserve the port number so the reply cache on the server can
 * find our cached RPC replies when we get around to reconnecting.
 */
static void xs_tcp_reuse_connection(struct rpc_xprt *xprt)
{
	int result;
	struct socket *sock = xprt->sock;
	struct sockaddr any;

	dprintk("RPC:      disconnecting xprt %p to reuse port\n", xprt);

	/*
	 * Disconnect the transport socket by doing a connect operation
	 * with AF_UNSPEC.  This should return immediately...
	 */
	memset(&any, 0, sizeof(any));
	any.sa_family = AF_UNSPEC;
	result = sock->ops->connect(sock, &any, sizeof(any), 0);
	if (result)
		dprintk("RPC:      AF_UNSPEC connect return code %d\n",
				result);
}

/**
 * xs_tcp_connect_worker - connect a TCP socket to a remote endpoint
 * @args: RPC transport to connect
 *
 * Invoked by a work queue tasklet.
 */
static void xs_tcp_connect_worker(void *args)
{
	struct rpc_xprt *xprt = (struct rpc_xprt *)args;
	struct socket *sock = xprt->sock;
	int err, status = -EIO;

	if (xprt->shutdown || xprt->addr.sin_port == 0)
		goto out;

	dprintk("RPC:      xs_tcp_connect_worker for xprt %p\n", xprt);

	if (!xprt->sock) {
		/* start from scratch */
		if ((err = sock_create_kern(PF_INET, SOCK_STREAM, IPPROTO_TCP, &sock)) < 0) {
			dprintk("RPC:      can't create TCP transport socket (%d).\n", -err);
			goto out;
		}

		if (xprt->resvport && xs_bindresvport(xprt, sock) < 0) {
			sock_release(sock);
			goto out;
		}
	} else
		/* "close" the socket, preserving the local port */
		xs_tcp_reuse_connection(xprt);

	if (!xprt->inet) {
		struct sock *sk = sock->sk;

		write_lock_bh(&sk->sk_callback_lock);

		sk->sk_user_data = xprt;
		xprt->old_data_ready = sk->sk_data_ready;
		xprt->old_state_change = sk->sk_state_change;
		xprt->old_write_space = sk->sk_write_space;
		sk->sk_data_ready = xs_tcp_data_ready;
		sk->sk_state_change = xs_tcp_state_change;
		sk->sk_write_space = xs_tcp_write_space;

		/* socket options */
		sk->sk_userlocks |= SOCK_BINDPORT_LOCK;
		sock_reset_flag(sk, SOCK_LINGER);
		tcp_sk(sk)->linger2 = 0;
		tcp_sk(sk)->nonagle |= TCP_NAGLE_OFF;

		xprt_clear_connected(xprt);

		/* Reset to new socket */
		xprt->sock = sock;
		xprt->inet = sk;

		write_unlock_bh(&sk->sk_callback_lock);
	}

	/* Tell the socket layer to start connecting... */
	status = sock->ops->connect(sock, (struct sockaddr *) &xprt->addr,
			sizeof(xprt->addr), O_NONBLOCK);
	dprintk("RPC: %p  connect status %d connected %d sock state %d\n",
			xprt, -status, xprt_connected(xprt), sock->sk->sk_state);
	if (status < 0) {
		switch (status) {
			case -EINPROGRESS:
			case -EALREADY:
				goto out_clear;
			case -ECONNREFUSED:
			case -ECONNRESET:
				/* retry with existing socket, after a delay */
				break;
			default:
				/* get rid of existing socket, and retry */
				xs_close(xprt);
				break;
		}
	}
out:
	xprt_wake_pending_tasks(xprt, status);
out_clear:
	xprt_clear_connecting(xprt);
}

/**
 * xs_connect - connect a socket to a remote endpoint
 * @task: address of RPC task that manages state of connect request
 *
 * TCP: If the remote end dropped the connection, delay reconnecting.
 *
 * UDP socket connects are synchronous, but we use a work queue anyway
 * to guarantee that even unprivileged user processes can set up a
 * socket on a privileged port.
 *
 * If a UDP socket connect fails, the delay behavior here prevents
 * retry floods (hard mounts).
 */
static void xs_connect(struct rpc_task *task)
{
	struct rpc_xprt *xprt = task->tk_xprt;

	if (xprt_test_and_set_connecting(xprt))
		return;

	if (xprt->sock != NULL) {
		dprintk("RPC:      xs_connect delayed xprt %p for %lu seconds\n",
				xprt, xprt->reestablish_timeout / HZ);
		schedule_delayed_work(&xprt->connect_worker,
					xprt->reestablish_timeout);
		xprt->reestablish_timeout <<= 1;
		if (xprt->reestablish_timeout > XS_TCP_MAX_REEST_TO)
			xprt->reestablish_timeout = XS_TCP_MAX_REEST_TO;
	} else {
		dprintk("RPC:      xs_connect scheduled xprt %p\n", xprt);
		schedule_work(&xprt->connect_worker);

		/* flush_scheduled_work can sleep... */
		if (!RPC_IS_ASYNC(task))
			flush_scheduled_work();
	}
}

static struct rpc_xprt_ops xs_udp_ops = {
	.set_buffer_size	= xs_udp_set_buffer_size,
	.reserve_xprt		= xprt_reserve_xprt_cong,
	.release_xprt		= xprt_release_xprt_cong,
	.connect		= xs_connect,
	.send_request		= xs_udp_send_request,
	.set_retrans_timeout	= xprt_set_retrans_timeout_rtt,
	.timer			= xs_udp_timer,
	.release_request	= xprt_release_rqst_cong,
	.close			= xs_close,
	.destroy		= xs_destroy,
};

static struct rpc_xprt_ops xs_tcp_ops = {
	.reserve_xprt		= xprt_reserve_xprt,
	.release_xprt		= xprt_release_xprt,
	.connect		= xs_connect,
	.send_request		= xs_tcp_send_request,
	.set_retrans_timeout	= xprt_set_retrans_timeout_def,
	.close			= xs_close,
	.destroy		= xs_destroy,
};

/**
 * xs_setup_udp - Set up transport to use a UDP socket
 * @xprt: transport to set up
 * @to:   timeout parameters
 *
 */
int xs_setup_udp(struct rpc_xprt *xprt, struct rpc_timeout *to)
{
	size_t slot_table_size;

	dprintk("RPC:      setting up udp-ipv4 transport...\n");

	xprt->max_reqs = xprt_udp_slot_table_entries;
	slot_table_size = xprt->max_reqs * sizeof(xprt->slot[0]);
	xprt->slot = kmalloc(slot_table_size, GFP_KERNEL);
	if (xprt->slot == NULL)
		return -ENOMEM;
	memset(xprt->slot, 0, slot_table_size);

	xprt->prot = IPPROTO_UDP;
	xprt->port = xprt_max_resvport;
	xprt->tsh_size = 0;
	xprt->resvport = capable(CAP_NET_BIND_SERVICE) ? 1 : 0;
	/* XXX: header size can vary due to auth type, IPv6, etc. */
	xprt->max_payload = (1U << 16) - (MAX_HEADER << 3);

	INIT_WORK(&xprt->connect_worker, xs_udp_connect_worker, xprt);
	xprt->bind_timeout = XS_BIND_TO;
	xprt->connect_timeout = XS_UDP_CONN_TO;
	xprt->reestablish_timeout = XS_UDP_REEST_TO;
	xprt->idle_timeout = XS_IDLE_DISC_TO;

	xprt->ops = &xs_udp_ops;

	if (to)
		xprt->timeout = *to;
	else
		xprt_set_timeout(&xprt->timeout, 5, 5 * HZ);

	return 0;
}

/**
 * xs_setup_tcp - Set up transport to use a TCP socket
 * @xprt: transport to set up
 * @to: timeout parameters
 *
 */
int xs_setup_tcp(struct rpc_xprt *xprt, struct rpc_timeout *to)
{
	size_t slot_table_size;

	dprintk("RPC:      setting up tcp-ipv4 transport...\n");

	xprt->max_reqs = xprt_tcp_slot_table_entries;
	slot_table_size = xprt->max_reqs * sizeof(xprt->slot[0]);
	xprt->slot = kmalloc(slot_table_size, GFP_KERNEL);
	if (xprt->slot == NULL)
		return -ENOMEM;
	memset(xprt->slot, 0, slot_table_size);

	xprt->prot = IPPROTO_TCP;
	xprt->port = xprt_max_resvport;
	xprt->tsh_size = sizeof(rpc_fraghdr) / sizeof(u32);
	xprt->resvport = capable(CAP_NET_BIND_SERVICE) ? 1 : 0;
	xprt->max_payload = RPC_MAX_FRAGMENT_SIZE;

	INIT_WORK(&xprt->connect_worker, xs_tcp_connect_worker, xprt);
	xprt->bind_timeout = XS_BIND_TO;
	xprt->connect_timeout = XS_TCP_CONN_TO;
	xprt->reestablish_timeout = XS_TCP_INIT_REEST_TO;
	xprt->idle_timeout = XS_IDLE_DISC_TO;

	xprt->ops = &xs_tcp_ops;

	if (to)
		xprt->timeout = *to;
	else
		xprt_set_timeout(&xprt->timeout, 2, 60 * HZ);

	return 0;
}