xref: /openbsd-src/sys/nfs/nfs_socket.c (revision 1a1df6393e0c865b3bd533cc019a70ad3fa9f991)
1 /*	$OpenBSD: nfs_socket.c,v 1.119 2017/06/27 12:02:43 mpi Exp $	*/
2 /*	$NetBSD: nfs_socket.c,v 1.27 1996/04/15 20:20:00 thorpej Exp $	*/
3 
4 /*
5  * Copyright (c) 1989, 1991, 1993, 1995
6  *	The Regents of the University of California.  All rights reserved.
7  *
8  * This code is derived from software contributed to Berkeley by
9  * Rick Macklem at The University of Guelph.
10  *
11  * Redistribution and use in source and binary forms, with or without
12  * modification, are permitted provided that the following conditions
13  * are met:
14  * 1. Redistributions of source code must retain the above copyright
15  *    notice, this list of conditions and the following disclaimer.
16  * 2. Redistributions in binary form must reproduce the above copyright
17  *    notice, this list of conditions and the following disclaimer in the
18  *    documentation and/or other materials provided with the distribution.
19  * 3. Neither the name of the University nor the names of its contributors
20  *    may be used to endorse or promote products derived from this software
21  *    without specific prior written permission.
22  *
23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33  * SUCH DAMAGE.
34  *
35  *	@(#)nfs_socket.c	8.5 (Berkeley) 3/30/95
36  */
37 
38 /*
39  * Socket operations for use by nfs
40  */
41 
42 #include <sys/param.h>
43 #include <sys/systm.h>
44 #include <sys/proc.h>
45 #include <sys/mount.h>
46 #include <sys/kernel.h>
47 #include <sys/mbuf.h>
48 #include <sys/vnode.h>
49 #include <sys/domain.h>
50 #include <sys/protosw.h>
51 #include <sys/signalvar.h>
52 #include <sys/socket.h>
53 #include <sys/socketvar.h>
54 #include <sys/syslog.h>
55 #include <sys/tprintf.h>
56 #include <sys/namei.h>
57 #include <sys/pool.h>
58 #include <sys/queue.h>
59 
60 #include <netinet/in.h>
61 #include <netinet/tcp.h>
62 
63 #include <nfs/rpcv2.h>
64 #include <nfs/nfsproto.h>
65 #include <nfs/nfs.h>
66 #include <nfs/xdr_subs.h>
67 #include <nfs/nfsm_subs.h>
68 #include <nfs/nfsmount.h>
69 #include <nfs/nfs_var.h>
70 
71 /* External data, mostly RPC constants in XDR form. */
72 extern u_int32_t rpc_reply, rpc_msgdenied, rpc_mismatch, rpc_vers,
73 	rpc_auth_unix, rpc_msgaccepted, rpc_call, rpc_autherr;
74 extern u_int32_t nfs_prog;
75 extern struct nfsstats nfsstats;
76 extern int nfsv3_procid[NFS_NPROCS];
77 extern int nfs_ticks;
78 
79 extern struct pool nfsrv_descript_pl;
80 
81 /*
82  * There is a congestion window for outstanding rpcs maintained per mount
83  * point. The cwnd size is adjusted in roughly the way that:
84  * Van Jacobson, Congestion avoidance and Control, In "Proceedings of
85  * SIGCOMM '88". ACM, August 1988.
86  * describes for TCP. The cwnd size is chopped in half on a retransmit timeout
87  * and incremented by 1/cwnd when each rpc reply is received and a full cwnd
88  * of rpcs is in progress.
89  * (The sent count and cwnd are scaled for integer arith.)
90  * Variants of "slow start" were tried and were found to be too much of a
91  * performance hit (ave. rtt 3 times larger),
92  * I suspect due to the large rtt that nfs rpcs have.
93  */
94 #define	NFS_CWNDSCALE	256
95 #define	NFS_MAXCWND	(NFS_CWNDSCALE * 32)
96 int nfs_backoff[8] = { 2, 4, 8, 16, 32, 64, 128, 256 };
97 
98 /* RTT estimator */
99 enum nfs_rto_timers nfs_ptimers[NFS_NPROCS] = {
100 	NFS_DEFAULT_TIMER,	/* NULL */
101 	NFS_GETATTR_TIMER,	/* GETATTR */
102 	NFS_DEFAULT_TIMER,	/* SETATTR */
103 	NFS_LOOKUP_TIMER,	/* LOOKUP */
104 	NFS_GETATTR_TIMER,	/* ACCESS */
105 	NFS_READ_TIMER,		/* READLINK */
106 	NFS_READ_TIMER,		/* READ */
107 	NFS_WRITE_TIMER,	/* WRITE */
108 	NFS_DEFAULT_TIMER,	/* CREATE */
109 	NFS_DEFAULT_TIMER,	/* MKDIR */
110 	NFS_DEFAULT_TIMER,	/* SYMLINK */
111 	NFS_DEFAULT_TIMER,	/* MKNOD */
112 	NFS_DEFAULT_TIMER,	/* REMOVE */
113 	NFS_DEFAULT_TIMER,	/* RMDIR */
114 	NFS_DEFAULT_TIMER,	/* RENAME */
115 	NFS_DEFAULT_TIMER,	/* LINK */
116 	NFS_READ_TIMER,		/* READDIR */
117 	NFS_READ_TIMER,		/* READDIRPLUS */
118 	NFS_DEFAULT_TIMER,	/* FSSTAT */
119 	NFS_DEFAULT_TIMER,	/* FSINFO */
120 	NFS_DEFAULT_TIMER,	/* PATHCONF */
121 	NFS_DEFAULT_TIMER,	/* COMMIT */
122 	NFS_DEFAULT_TIMER,	/* NOOP */
123 };
124 
125 void nfs_init_rtt(struct nfsmount *);
126 void nfs_update_rtt(struct nfsreq *);
127 int  nfs_estimate_rto(struct nfsmount *, u_int32_t procnum);
128 
129 void nfs_realign(struct mbuf **, int);
130 void nfs_realign_fixup(struct mbuf *, struct mbuf *, unsigned int *);
131 
132 int nfs_rcvlock(struct nfsreq *);
133 int nfs_receive(struct nfsreq *, struct mbuf **, struct mbuf **);
134 int nfs_reconnect(struct nfsreq *);
135 int nfs_reply(struct nfsreq *);
136 void nfs_msg(struct nfsreq *, char *);
137 void nfs_rcvunlock(int *);
138 
139 int nfsrv_getstream(struct nfssvc_sock *, int);
140 
141 unsigned int nfs_realign_test = 0;
142 unsigned int nfs_realign_count = 0;
143 
144 /* Initialize the RTT estimator state for a new mount point. */
145 void
146 nfs_init_rtt(struct nfsmount *nmp)
147 {
148 	int i;
149 
150 	for (i = 0; i < NFS_MAX_TIMER; i++)
151 		nmp->nm_srtt[i] = NFS_INITRTT;
152 	for (i = 0; i < NFS_MAX_TIMER; i++)
153 		nmp->nm_sdrtt[i] = 0;
154 }
155 
156 /*
157  * Update a mount point's RTT estimator state using data from the
158  * passed-in request.
159  *
160  * Use a gain of 0.125 on the mean and a gain of 0.25 on the deviation.
161  *
162  * NB: Since the timer resolution of NFS_HZ is so course, it can often
163  * result in r_rtt == 0. Since r_rtt == N means that the actual RTT is
164  * between N + dt and N + 2 - dt ticks, add 1 before calculating the
165  * update values.
166  */
167 void
168 nfs_update_rtt(struct nfsreq *rep)
169 {
170 	int t1 = rep->r_rtt + 1;
171 	int index = nfs_ptimers[rep->r_procnum] - 1;
172 	int *srtt = &rep->r_nmp->nm_srtt[index];
173 	int *sdrtt = &rep->r_nmp->nm_sdrtt[index];
174 
175 	t1 -= *srtt >> 3;
176 	*srtt += t1;
177 	if (t1 < 0)
178 		t1 = -t1;
179 	t1 -= *sdrtt >> 2;
180 	*sdrtt += t1;
181 }
182 
183 /*
184  * Estimate RTO for an NFS RPC sent via an unreliable datagram.
185  *
186  * Use the mean and mean deviation of RTT for the appropriate type
187  * of RPC for the frequent RPCs and a default for the others.
188  * The justification for doing "other" this way is that these RPCs
189  * happen so infrequently that timer est. would probably be stale.
190  * Also, since many of these RPCs are non-idempotent, a conservative
191  * timeout is desired.
192  *
193  * getattr, lookup - A+2D
194  * read, write     - A+4D
195  * other           - nm_timeo
196  */
197 int
198 nfs_estimate_rto(struct nfsmount *nmp, u_int32_t procnum)
199 {
200 	enum nfs_rto_timers timer = nfs_ptimers[procnum];
201 	int index = timer - 1;
202 	int rto;
203 
204 	switch (timer) {
205 	case NFS_GETATTR_TIMER:
206 	case NFS_LOOKUP_TIMER:
207 		rto = ((nmp->nm_srtt[index] + 3) >> 2) +
208 				((nmp->nm_sdrtt[index] + 1) >> 1);
209 		break;
210 	case NFS_READ_TIMER:
211 	case NFS_WRITE_TIMER:
212 		rto = ((nmp->nm_srtt[index] + 7) >> 3) +
213 				(nmp->nm_sdrtt[index] + 1);
214 		break;
215 	default:
216 		rto = nmp->nm_timeo;
217 		return (rto);
218 	}
219 
220 	if (rto < NFS_MINRTO)
221 		rto = NFS_MINRTO;
222 	else if (rto > NFS_MAXRTO)
223 		rto = NFS_MAXRTO;
224 
225 	return (rto);
226 }
227 
228 
229 
230 /*
231  * Initialize sockets and congestion for a new NFS connection.
232  * We do not free the sockaddr if error.
233  */
234 int
235 nfs_connect(struct nfsmount *nmp, struct nfsreq *rep)
236 {
237 	struct socket *so;
238 	int s, error, rcvreserve, sndreserve;
239 	struct sockaddr *saddr;
240 	struct sockaddr_in *sin;
241 	struct mbuf *m;
242 
243 	nmp->nm_so = NULL;
244 	saddr = mtod(nmp->nm_nam, struct sockaddr *);
245 	error = socreate(saddr->sa_family, &nmp->nm_so, nmp->nm_sotype,
246 		nmp->nm_soproto);
247 	if (error)
248 		goto bad;
249 	so = nmp->nm_so;
250 	nmp->nm_soflags = so->so_proto->pr_flags;
251 
252 	/*
253 	 * Some servers require that the client port be a reserved port number.
254 	 * We always allocate a reserved port, as this prevents filehandle
255 	 * disclosure through UDP port capture.
256 	 */
257 	if (saddr->sa_family == AF_INET) {
258 		struct mbuf *mopt;
259 		int *ip;
260 
261 		MGET(mopt, M_WAIT, MT_SOOPTS);
262 		mopt->m_len = sizeof(int);
263 		ip = mtod(mopt, int *);
264 		*ip = IP_PORTRANGE_LOW;
265 		error = sosetopt(so, IPPROTO_IP, IP_PORTRANGE, mopt);
266 		if (error)
267 			goto bad;
268 
269 		MGET(m, M_WAIT, MT_SONAME);
270 		sin = mtod(m, struct sockaddr_in *);
271 		memset(sin, 0, sizeof(*sin));
272 		sin->sin_len = m->m_len = sizeof(struct sockaddr_in);
273 		sin->sin_family = AF_INET;
274 		sin->sin_addr.s_addr = INADDR_ANY;
275 		sin->sin_port = htons(0);
276 		error = sobind(so, m, &proc0);
277 		m_freem(m);
278 		if (error)
279 			goto bad;
280 
281 		MGET(mopt, M_WAIT, MT_SOOPTS);
282 		mopt->m_len = sizeof(int);
283 		ip = mtod(mopt, int *);
284 		*ip = IP_PORTRANGE_DEFAULT;
285 		error = sosetopt(so, IPPROTO_IP, IP_PORTRANGE, mopt);
286 		if (error)
287 			goto bad;
288 	}
289 
290 	/*
291 	 * Protocols that do not require connections may be optionally left
292 	 * unconnected for servers that reply from a port other than NFS_PORT.
293 	 */
294 	if (nmp->nm_flag & NFSMNT_NOCONN) {
295 		if (nmp->nm_soflags & PR_CONNREQUIRED) {
296 			error = ENOTCONN;
297 			goto bad;
298 		}
299 	} else {
300 		error = soconnect(so, nmp->nm_nam);
301 		if (error)
302 			goto bad;
303 
304 		/*
305 		 * Wait for the connection to complete. Cribbed from the
306 		 * connect system call but with the wait timing out so
307 		 * that interruptible mounts don't hang here for a long time.
308 		 */
309 		s = solock(so);
310 		while ((so->so_state & SS_ISCONNECTING) && so->so_error == 0) {
311 			sosleep(so, &so->so_timeo, PSOCK, "nfscon", 2 * hz);
312 			if ((so->so_state & SS_ISCONNECTING) &&
313 			    so->so_error == 0 && rep &&
314 			    (error = nfs_sigintr(nmp, rep, rep->r_procp)) != 0){
315 				so->so_state &= ~SS_ISCONNECTING;
316 				sounlock(s);
317 				goto bad;
318 			}
319 		}
320 		if (so->so_error) {
321 			error = so->so_error;
322 			so->so_error = 0;
323 			sounlock(s);
324 			goto bad;
325 		}
326 		sounlock(s);
327 	}
328 	/*
329 	 * Always set receive timeout to detect server crash and reconnect.
330 	 * Otherwise, we can get stuck in soreceive forever.
331 	 */
332 	so->so_rcv.sb_timeo = (5 * hz);
333 	if (nmp->nm_flag & (NFSMNT_SOFT | NFSMNT_INT))
334 		so->so_snd.sb_timeo = (5 * hz);
335 	else
336 		so->so_snd.sb_timeo = 0;
337 	if (nmp->nm_sotype == SOCK_DGRAM) {
338 		sndreserve = nmp->nm_wsize + NFS_MAXPKTHDR;
339 		rcvreserve = (max(nmp->nm_rsize, nmp->nm_readdirsize) +
340 		    NFS_MAXPKTHDR) * 2;
341 	} else if (nmp->nm_sotype == SOCK_SEQPACKET) {
342 		sndreserve = (nmp->nm_wsize + NFS_MAXPKTHDR) * 2;
343 		rcvreserve = (max(nmp->nm_rsize, nmp->nm_readdirsize) +
344 		    NFS_MAXPKTHDR) * 2;
345 	} else {
346 		if (nmp->nm_sotype != SOCK_STREAM)
347 			panic("nfscon sotype");
348 		if (so->so_proto->pr_flags & PR_CONNREQUIRED) {
349 			MGET(m, M_WAIT, MT_SOOPTS);
350 			*mtod(m, int32_t *) = 1;
351 			m->m_len = sizeof(int32_t);
352 			sosetopt(so, SOL_SOCKET, SO_KEEPALIVE, m);
353 		}
354 		if (so->so_proto->pr_protocol == IPPROTO_TCP) {
355 			MGET(m, M_WAIT, MT_SOOPTS);
356 			*mtod(m, int32_t *) = 1;
357 			m->m_len = sizeof(int32_t);
358 			sosetopt(so, IPPROTO_TCP, TCP_NODELAY, m);
359 		}
360 		sndreserve = (nmp->nm_wsize + NFS_MAXPKTHDR +
361 		    sizeof (u_int32_t)) * 2;
362 		rcvreserve = (nmp->nm_rsize + NFS_MAXPKTHDR +
363 		    sizeof (u_int32_t)) * 2;
364 	}
365 	s = solock(so);
366 	error = soreserve(so, sndreserve, rcvreserve);
367 	sounlock(s);
368 	if (error)
369 		goto bad;
370 	so->so_rcv.sb_flags |= SB_NOINTR;
371 	so->so_snd.sb_flags |= SB_NOINTR;
372 
373 	/* Initialize other non-zero congestion variables */
374 	nfs_init_rtt(nmp);
375 	nmp->nm_cwnd = NFS_MAXCWND / 2;	    /* Initial send window */
376 	nmp->nm_sent = 0;
377 	nmp->nm_timeouts = 0;
378 	return (0);
379 
380 bad:
381 	nfs_disconnect(nmp);
382 	return (error);
383 }
384 
385 /*
386  * Reconnect routine:
387  * Called when a connection is broken on a reliable protocol.
388  * - clean up the old socket
389  * - nfs_connect() again
390  * - set R_MUSTRESEND for all outstanding requests on mount point
391  * If this fails the mount point is DEAD!
392  * nb: Must be called with the nfs_sndlock() set on the mount point.
393  */
394 int
395 nfs_reconnect(struct nfsreq *rep)
396 {
397 	struct nfsreq *rp;
398 	struct nfsmount *nmp = rep->r_nmp;
399 	int error;
400 
401 	nfs_disconnect(nmp);
402 	while ((error = nfs_connect(nmp, rep)) != 0) {
403 		if (error == EINTR || error == ERESTART)
404 			return (EINTR);
405 		(void) tsleep((caddr_t)&lbolt, PSOCK, "nfsrecon", 0);
406 	}
407 
408 	/*
409 	 * Loop through outstanding request list and fix up all requests
410 	 * on old socket.
411 	 */
412 	TAILQ_FOREACH(rp, &nmp->nm_reqsq, r_chain) {
413 		rp->r_flags |= R_MUSTRESEND;
414 		rp->r_rexmit = 0;
415 	}
416 	return (0);
417 }
418 
419 /*
420  * NFS disconnect. Clean up and unlink.
421  */
422 void
423 nfs_disconnect(struct nfsmount *nmp)
424 {
425 	struct socket *so;
426 
427 	if (nmp->nm_so) {
428 		so = nmp->nm_so;
429 		nmp->nm_so = NULL;
430 		soshutdown(so, SHUT_RDWR);
431 		soclose(so);
432 	}
433 }
434 
435 /*
436  * This is the nfs send routine. For connection based socket types, it
437  * must be called with an nfs_sndlock() on the socket.
438  * "rep == NULL" indicates that it has been called from a server.
439  * For the client side:
440  * - return EINTR if the RPC is terminated, 0 otherwise
441  * - set R_MUSTRESEND if the send fails for any reason
442  * - do any cleanup required by recoverable socket errors (???)
443  * For the server side:
444  * - return EINTR or ERESTART if interrupted by a signal
445  * - return EPIPE if a connection is lost for connection based sockets (TCP...)
446  * - do any cleanup required by recoverable socket errors (???)
447  */
448 int
449 nfs_send(struct socket *so, struct mbuf *nam, struct mbuf *top,
450     struct nfsreq *rep)
451 {
452 	struct mbuf *sendnam;
453 	int error, soflags, flags;
454 
455 	if (rep) {
456 		if (rep->r_flags & R_SOFTTERM) {
457 			m_freem(top);
458 			return (EINTR);
459 		}
460 		if ((so = rep->r_nmp->nm_so) == NULL) {
461 			rep->r_flags |= R_MUSTRESEND;
462 			m_freem(top);
463 			return (0);
464 		}
465 		rep->r_flags &= ~R_MUSTRESEND;
466 		soflags = rep->r_nmp->nm_soflags;
467 	} else
468 		soflags = so->so_proto->pr_flags;
469 	if ((soflags & PR_CONNREQUIRED) || (so->so_state & SS_ISCONNECTED))
470 		sendnam = NULL;
471 	else
472 		sendnam = nam;
473 	if (so->so_type == SOCK_SEQPACKET)
474 		flags = MSG_EOR;
475 	else
476 		flags = 0;
477 
478 	error = sosend(so, sendnam, NULL, top, NULL, flags);
479 	if (error) {
480 		if (rep) {
481 			/*
482 			 * Deal with errors for the client side.
483 			 */
484 			if (rep->r_flags & R_SOFTTERM)
485 				error = EINTR;
486 			else
487 				rep->r_flags |= R_MUSTRESEND;
488 		}
489 
490 		/*
491 		 * Handle any recoverable (soft) socket errors here. (???)
492 		 */
493 		if (error != EINTR && error != ERESTART &&
494 			error != EWOULDBLOCK && error != EPIPE)
495 			error = 0;
496 	}
497 	return (error);
498 }
499 
500 #ifdef NFSCLIENT
501 /*
502  * Receive a Sun RPC Request/Reply. For SOCK_DGRAM, the work is all
503  * done by soreceive(), but for SOCK_STREAM we must deal with the Record
504  * Mark and consolidate the data into a new mbuf list.
505  * nb: Sometimes TCP passes the data up to soreceive() in long lists of
506  *     small mbufs.
507  * For SOCK_STREAM we must be very careful to read an entire record once
508  * we have read any of it, even if the system call has been interrupted.
509  */
510 int
511 nfs_receive(struct nfsreq *rep, struct mbuf **aname, struct mbuf **mp)
512 {
513 	struct socket *so;
514 	struct uio auio;
515 	struct iovec aio;
516 	struct mbuf *m;
517 	struct mbuf *control;
518 	u_int32_t len;
519 	struct mbuf **getnam;
520 	int error, sotype, rcvflg;
521 	struct proc *p = curproc;	/* XXX */
522 
523 	/*
524 	 * Set up arguments for soreceive()
525 	 */
526 	*mp = NULL;
527 	*aname = NULL;
528 	sotype = rep->r_nmp->nm_sotype;
529 
530 	/*
531 	 * For reliable protocols, lock against other senders/receivers
532 	 * in case a reconnect is necessary.
533 	 * For SOCK_STREAM, first get the Record Mark to find out how much
534 	 * more there is to get.
535 	 * We must lock the socket against other receivers
536 	 * until we have an entire rpc request/reply.
537 	 */
538 	if (sotype != SOCK_DGRAM) {
539 		error = nfs_sndlock(&rep->r_nmp->nm_flag, rep);
540 		if (error)
541 			return (error);
542 tryagain:
543 		/*
544 		 * Check for fatal errors and resending request.
545 		 */
546 		/*
547 		 * Ugh: If a reconnect attempt just happened, nm_so
548 		 * would have changed. NULL indicates a failed
549 		 * attempt that has essentially shut down this
550 		 * mount point.
551 		 */
552 		if (rep->r_mrep || (rep->r_flags & R_SOFTTERM)) {
553 			nfs_sndunlock(&rep->r_nmp->nm_flag);
554 			return (EINTR);
555 		}
556 		so = rep->r_nmp->nm_so;
557 		if (!so) {
558 			error = nfs_reconnect(rep);
559 			if (error) {
560 				nfs_sndunlock(&rep->r_nmp->nm_flag);
561 				return (error);
562 			}
563 			goto tryagain;
564 		}
565 		while (rep->r_flags & R_MUSTRESEND) {
566 			m = m_copym(rep->r_mreq, 0, M_COPYALL, M_WAIT);
567 			nfsstats.rpcretries++;
568 			rep->r_rtt = 0;
569 			rep->r_flags &= ~R_TIMING;
570 			error = nfs_send(so, rep->r_nmp->nm_nam, m, rep);
571 			if (error) {
572 				if (error == EINTR || error == ERESTART ||
573 				    (error = nfs_reconnect(rep)) != 0) {
574 					nfs_sndunlock(&rep->r_nmp->nm_flag);
575 					return (error);
576 				}
577 				goto tryagain;
578 			}
579 		}
580 		nfs_sndunlock(&rep->r_nmp->nm_flag);
581 		if (sotype == SOCK_STREAM) {
582 			aio.iov_base = (caddr_t) &len;
583 			aio.iov_len = sizeof(u_int32_t);
584 			auio.uio_iov = &aio;
585 			auio.uio_iovcnt = 1;
586 			auio.uio_segflg = UIO_SYSSPACE;
587 			auio.uio_rw = UIO_READ;
588 			auio.uio_offset = 0;
589 			auio.uio_resid = sizeof(u_int32_t);
590 			auio.uio_procp = p;
591 			do {
592 			   rcvflg = MSG_WAITALL;
593 			   error = soreceive(so, NULL, &auio, NULL, NULL,
594 			       &rcvflg, 0);
595 			   if (error == EWOULDBLOCK && rep) {
596 				if (rep->r_flags & R_SOFTTERM)
597 					return (EINTR);
598 				/*
599 				 * looks like the server died after it
600 				 * received the request, make sure
601 				 * that we will retransmit and we
602 				 * don't get stuck here forever.
603 				 */
604 				if (rep->r_rexmit >= rep->r_nmp->nm_retry) {
605 					nfsstats.rpctimeouts++;
606 					error = EPIPE;
607 				}
608 			   }
609 			} while (error == EWOULDBLOCK);
610 			if (!error && auio.uio_resid > 0) {
611 			    log(LOG_INFO,
612 				 "short receive (%zu/%zu) from nfs server %s\n",
613 				 sizeof(u_int32_t) - auio.uio_resid,
614 				 sizeof(u_int32_t),
615 				 rep->r_nmp->nm_mountp->mnt_stat.f_mntfromname);
616 			    error = EPIPE;
617 			}
618 			if (error)
619 				goto errout;
620 
621 			len = ntohl(len) & ~0x80000000;
622 			/*
623 			 * This is SERIOUS! We are out of sync with the sender
624 			 * and forcing a disconnect/reconnect is all I can do.
625 			 */
626 			if (len > NFS_MAXPACKET) {
627 			    log(LOG_ERR, "%s (%u) from nfs server %s\n",
628 				"impossible packet length",
629 				len,
630 				rep->r_nmp->nm_mountp->mnt_stat.f_mntfromname);
631 			    error = EFBIG;
632 			    goto errout;
633 			}
634 			auio.uio_resid = len;
635 			do {
636 			    rcvflg = MSG_WAITALL;
637 			    error =  soreceive(so, NULL, &auio, mp, NULL,
638 			        &rcvflg, 0);
639 			} while (error == EWOULDBLOCK || error == EINTR ||
640 				 error == ERESTART);
641 			if (!error && auio.uio_resid > 0) {
642 			    log(LOG_INFO,
643 				"short receive (%zu/%u) from nfs server %s\n",
644 				len - auio.uio_resid, len,
645 				rep->r_nmp->nm_mountp->mnt_stat.f_mntfromname);
646 			    error = EPIPE;
647 			}
648 		} else {
649 			/*
650 			 * NB: Since uio_resid is big, MSG_WAITALL is ignored
651 			 * and soreceive() will return when it has either a
652 			 * control msg or a data msg.
653 			 * We have no use for control msg., but must grab them
654 			 * and then throw them away so we know what is going
655 			 * on.
656 			 */
657 			auio.uio_resid = len = 100000000; /* Anything Big */
658 			auio.uio_procp = p;
659 			do {
660 			    rcvflg = 0;
661 			    error =  soreceive(so, NULL, &auio, mp, &control,
662 			        &rcvflg, 0);
663 			    m_freem(control);
664 			    if (error == EWOULDBLOCK && rep) {
665 				if (rep->r_flags & R_SOFTTERM)
666 					return (EINTR);
667 			    }
668 			} while (error == EWOULDBLOCK ||
669 				 (!error && *mp == NULL && control));
670 			if ((rcvflg & MSG_EOR) == 0)
671 				printf("Egad!!\n");
672 			if (!error && *mp == NULL)
673 				error = EPIPE;
674 			len -= auio.uio_resid;
675 		}
676 errout:
677 		if (error && error != EINTR && error != ERESTART) {
678 			m_freemp(mp);
679 			if (error != EPIPE)
680 				log(LOG_INFO,
681 				    "receive error %d from nfs server %s\n",
682 				    error,
683 				 rep->r_nmp->nm_mountp->mnt_stat.f_mntfromname);
684 			error = nfs_sndlock(&rep->r_nmp->nm_flag, rep);
685 			if (!error) {
686 				error = nfs_reconnect(rep);
687 				if (!error)
688 					goto tryagain;
689 				nfs_sndunlock(&rep->r_nmp->nm_flag);
690 			}
691 		}
692 	} else {
693 		if ((so = rep->r_nmp->nm_so) == NULL)
694 			return (EACCES);
695 		if (so->so_state & SS_ISCONNECTED)
696 			getnam = NULL;
697 		else
698 			getnam = aname;
699 		auio.uio_resid = len = 1000000;
700 		auio.uio_procp = p;
701 		do {
702 			rcvflg = 0;
703 			error =  soreceive(so, getnam, &auio, mp, NULL,
704 			    &rcvflg, 0);
705 			if (error == EWOULDBLOCK &&
706 			    (rep->r_flags & R_SOFTTERM))
707 				return (EINTR);
708 		} while (error == EWOULDBLOCK);
709 		len -= auio.uio_resid;
710 	}
711 	if (error)
712 		m_freemp(mp);
713 	/*
714 	 * Search for any mbufs that are not a multiple of 4 bytes long
715 	 * or with m_data not longword aligned.
716 	 * These could cause pointer alignment problems, so copy them to
717 	 * well aligned mbufs.
718 	 */
719 	nfs_realign(mp, 5 * NFSX_UNSIGNED);
720 	return (error);
721 }
722 
723 /*
724  * Implement receipt of reply on a socket.
725  * We must search through the list of received datagrams matching them
726  * with outstanding requests using the xid, until ours is found.
727  */
728 int
729 nfs_reply(struct nfsreq *myrep)
730 {
731 	struct nfsreq *rep;
732 	struct nfsmount *nmp = myrep->r_nmp;
733 	struct nfsm_info	info;
734 	struct mbuf *nam;
735 	u_int32_t rxid, *tl, t1;
736 	caddr_t cp2;
737 	int error;
738 
739 	/*
740 	 * Loop around until we get our own reply
741 	 */
742 	for (;;) {
743 		/*
744 		 * Lock against other receivers so that I don't get stuck in
745 		 * sbwait() after someone else has received my reply for me.
746 		 * Also necessary for connection based protocols to avoid
747 		 * race conditions during a reconnect.
748 		 */
749 		error = nfs_rcvlock(myrep);
750 		if (error)
751 			return (error == EALREADY ? 0 : error);
752 
753 		/*
754 		 * Get the next Rpc reply off the socket
755 		 */
756 		error = nfs_receive(myrep, &nam, &info.nmi_mrep);
757 		nfs_rcvunlock(&nmp->nm_flag);
758 		if (error) {
759 
760 			/*
761 			 * Ignore routing errors on connectionless protocols??
762 			 */
763 			if (NFSIGNORE_SOERROR(nmp->nm_soflags, error)) {
764 				if (nmp->nm_so)
765 					nmp->nm_so->so_error = 0;
766 				continue;
767 			}
768 			return (error);
769 		}
770 		m_freem(nam);
771 
772 		/*
773 		 * Get the xid and check that it is an rpc reply
774 		 */
775 		info.nmi_md = info.nmi_mrep;
776 		info.nmi_dpos = mtod(info.nmi_md, caddr_t);
777 		nfsm_dissect(tl, u_int32_t *, 2*NFSX_UNSIGNED);
778 		rxid = *tl++;
779 		if (*tl != rpc_reply) {
780 			nfsstats.rpcinvalid++;
781 			m_freem(info.nmi_mrep);
782 nfsmout:
783 			continue;
784 		}
785 
786 		/*
787 		 * Loop through the request list to match up the reply
788 		 * Iff no match, just drop the datagram
789 		 */
790 		TAILQ_FOREACH(rep, &nmp->nm_reqsq, r_chain) {
791 			if (rep->r_mrep == NULL && rxid == rep->r_xid) {
792 				/* Found it.. */
793 				rep->r_mrep = info.nmi_mrep;
794 				rep->r_md = info.nmi_md;
795 				rep->r_dpos = info.nmi_dpos;
796 
797 				/*
798 				 * Update congestion window.
799 				 * Do the additive increase of
800 				 * one rpc/rtt.
801 				 */
802 				if (nmp->nm_cwnd <= nmp->nm_sent) {
803 					nmp->nm_cwnd +=
804 					   (NFS_CWNDSCALE * NFS_CWNDSCALE +
805 					   (nmp->nm_cwnd >> 1)) / nmp->nm_cwnd;
806 					if (nmp->nm_cwnd > NFS_MAXCWND)
807 						nmp->nm_cwnd = NFS_MAXCWND;
808 				}
809 				rep->r_flags &= ~R_SENT;
810 				nmp->nm_sent -= NFS_CWNDSCALE;
811 
812 				if (rep->r_flags & R_TIMING)
813 					nfs_update_rtt(rep);
814 
815 				nmp->nm_timeouts = 0;
816 				break;
817 			}
818 		}
819 		/*
820 		 * If not matched to a request, drop it.
821 		 * If it's mine, get out.
822 		 */
823 		if (rep == 0) {
824 			nfsstats.rpcunexpected++;
825 			m_freem(info.nmi_mrep);
826 		} else if (rep == myrep) {
827 			if (rep->r_mrep == NULL)
828 				panic("nfsreply nil");
829 			return (0);
830 		}
831 	}
832 }
833 
834 /*
835  * nfs_request - goes something like this
836  *	- fill in request struct
837  *	- links it into list
838  *	- calls nfs_send() for first transmit
839  *	- calls nfs_receive() to get reply
840  *	- break down rpc header and return with nfs reply pointed to
841  *	  by mrep or error
842  * nb: always frees up mreq mbuf list
843  */
844 int
845 nfs_request(struct vnode *vp, int procnum, struct nfsm_info *infop)
846 {
847 	struct mbuf *m;
848 	u_int32_t *tl;
849 	struct nfsmount *nmp;
850 	struct timeval tv;
851 	caddr_t cp2;
852 	int t1, i, error = 0;
853 	int trylater_delay;
854 	struct nfsreq *rep;
855 	int  mrest_len;
856 	struct nfsm_info	info;
857 
858 	rep = pool_get(&nfsreqpl, PR_WAITOK);
859 	rep->r_nmp = VFSTONFS(vp->v_mount);
860 	rep->r_vp = vp;
861 	rep->r_procp = infop->nmi_procp;
862 	rep->r_procnum = procnum;
863 
864 	mrest_len = 0;
865 	m = infop->nmi_mreq;
866 	while (m) {
867 		mrest_len += m->m_len;
868 		m = m->m_next;
869 	}
870 
871 	/* empty mbuf for AUTH_UNIX header */
872 	rep->r_mreq = m_gethdr(M_WAIT, MT_DATA);
873 	rep->r_mreq->m_next = infop->nmi_mreq;
874 	rep->r_mreq->m_pkthdr.len = mrest_len;
875 
876 	trylater_delay = NFS_MINTIMEO;
877 
878 	nmp = rep->r_nmp;
879 
880 	/* Get the RPC header with authorization. */
881 	nfsm_rpchead(rep, infop->nmi_cred, RPCAUTH_UNIX);
882 	m = rep->r_mreq;
883 
884 	/*
885 	 * For stream protocols, insert a Sun RPC Record Mark.
886 	 */
887 	if (nmp->nm_sotype == SOCK_STREAM) {
888 		M_PREPEND(m, NFSX_UNSIGNED, M_WAIT);
889 		*mtod(m, u_int32_t *) = htonl(0x80000000 |
890 			 (m->m_pkthdr.len - NFSX_UNSIGNED));
891 	}
892 
893 tryagain:
894 	rep->r_rtt = rep->r_rexmit = 0;
895 	if (nfs_ptimers[rep->r_procnum] != NFS_DEFAULT_TIMER)
896 		rep->r_flags = R_TIMING;
897 	else
898 		rep->r_flags = 0;
899 	rep->r_mrep = NULL;
900 
901 	/*
902 	 * Do the client side RPC.
903 	 */
904 	nfsstats.rpcrequests++;
905 	/*
906 	 * Chain request into list of outstanding requests. Be sure
907 	 * to put it LAST so timer finds oldest requests first.
908 	 */
909 	if (TAILQ_EMPTY(&nmp->nm_reqsq))
910 		timeout_add(&nmp->nm_rtimeout, nfs_ticks);
911 	TAILQ_INSERT_TAIL(&nmp->nm_reqsq, rep, r_chain);
912 
913 	/*
914 	 * If backing off another request or avoiding congestion, don't
915 	 * send this one now but let timer do it. If not timing a request,
916 	 * do it now.
917 	 */
918 	if (nmp->nm_so && (nmp->nm_sotype != SOCK_DGRAM ||
919 		(nmp->nm_flag & NFSMNT_DUMBTIMR) ||
920 		nmp->nm_sent < nmp->nm_cwnd)) {
921 		if (nmp->nm_soflags & PR_CONNREQUIRED)
922 			error = nfs_sndlock(&nmp->nm_flag, rep);
923 		if (!error) {
924 			error = nfs_send(nmp->nm_so, nmp->nm_nam,
925 					m_copym(m, 0, M_COPYALL, M_WAIT),
926 					rep);
927 			if (nmp->nm_soflags & PR_CONNREQUIRED)
928 				nfs_sndunlock(&nmp->nm_flag);
929 		}
930 		if (!error && (rep->r_flags & R_MUSTRESEND) == 0) {
931 			nmp->nm_sent += NFS_CWNDSCALE;
932 			rep->r_flags |= R_SENT;
933 		}
934 	} else {
935 		rep->r_rtt = -1;
936 	}
937 
938 	/*
939 	 * Wait for the reply from our send or the timer's.
940 	 */
941 	if (!error || error == EPIPE)
942 		error = nfs_reply(rep);
943 
944 	/*
945 	 * RPC done, unlink the request.
946 	 */
947 	TAILQ_REMOVE(&nmp->nm_reqsq, rep, r_chain);
948 	if (TAILQ_EMPTY(&nmp->nm_reqsq))
949 		timeout_del(&nmp->nm_rtimeout);
950 
951 	/*
952 	 * Decrement the outstanding request count.
953 	 */
954 	if (rep->r_flags & R_SENT) {
955 		rep->r_flags &= ~R_SENT;	/* paranoia */
956 		nmp->nm_sent -= NFS_CWNDSCALE;
957 	}
958 
959 	/*
960 	 * If there was a successful reply and a tprintf msg.
961 	 * tprintf a response.
962 	 */
963 	if (!error && (rep->r_flags & R_TPRINTFMSG))
964 		nfs_msg(rep, "is alive again");
965 	info.nmi_mrep = rep->r_mrep;
966 	info.nmi_md = rep->r_md;
967 	info.nmi_dpos = rep->r_dpos;
968 	if (error) {
969 		infop->nmi_mrep = NULL;
970 		goto nfsmout1;
971 	}
972 
973 	/*
974 	 * break down the rpc header and check if ok
975 	 */
976 	nfsm_dissect(tl, u_int32_t *, 3 * NFSX_UNSIGNED);
977 	if (*tl++ == rpc_msgdenied) {
978 		if (*tl == rpc_mismatch)
979 			error = EOPNOTSUPP;
980 		else
981 			error = EACCES;	/* Should be EAUTH. */
982 		infop->nmi_mrep = NULL;
983 		goto nfsmout1;
984 	}
985 
986 	/*
987 	 * Since we only support RPCAUTH_UNIX atm we step over the
988 	 * reply verifer type, and in the (error) case that there really
989 	 * is any data in it, we advance over it.
990 	 */
991 	tl++;			/* Step over verifer type */
992 	i = fxdr_unsigned(int32_t, *tl);
993 	if (i > 0)
994 		nfsm_adv(nfsm_rndup(i));	/* Should not happen */
995 
996 	nfsm_dissect(tl, u_int32_t *, NFSX_UNSIGNED);
997 	/* 0 == ok */
998 	if (*tl == 0) {
999 		nfsm_dissect(tl, u_int32_t *, NFSX_UNSIGNED);
1000 		if (*tl != 0) {
1001 			error = fxdr_unsigned(int, *tl);
1002 			if ((nmp->nm_flag & NFSMNT_NFSV3) &&
1003 			    error == NFSERR_TRYLATER) {
1004 				m_freem(info.nmi_mrep);
1005 				error = 0;
1006 				tv.tv_sec = trylater_delay;
1007 				tv.tv_usec = 0;
1008 				tsleep(&tv, PSOCK, "nfsretry", tvtohz(&tv));
1009 				trylater_delay *= NFS_TIMEOUTMUL;
1010 				if (trylater_delay > NFS_MAXTIMEO)
1011 					trylater_delay = NFS_MAXTIMEO;
1012 
1013 				goto tryagain;
1014 			}
1015 
1016 			/*
1017 			 * If the File Handle was stale, invalidate the
1018 			 * lookup cache, just in case.
1019 			 */
1020 			if (error == ESTALE)
1021 				cache_purge(rep->r_vp);
1022 		}
1023 		goto nfsmout;
1024 	}
1025 
1026 	error = EPROTONOSUPPORT;
1027 
1028 nfsmout:
1029 	infop->nmi_mrep = info.nmi_mrep;
1030 	infop->nmi_md = info.nmi_md;
1031 	infop->nmi_dpos = info.nmi_dpos;
1032 nfsmout1:
1033 	m_freem(rep->r_mreq);
1034 	pool_put(&nfsreqpl, rep);
1035 	return (error);
1036 }
1037 #endif /* NFSCLIENT */
1038 
1039 /*
1040  * Generate the rpc reply header
1041  * siz arg. is used to decide if adding a cluster is worthwhile
1042  */
1043 int
1044 nfs_rephead(int siz, struct nfsrv_descript *nd, struct nfssvc_sock *slp,
1045     int err, struct mbuf **mrq, struct mbuf **mbp)
1046 {
1047 	u_int32_t *tl;
1048 	struct mbuf *mreq;
1049 	struct mbuf *mb;
1050 
1051 	MGETHDR(mreq, M_WAIT, MT_DATA);
1052 	mb = mreq;
1053 	/*
1054 	 * If this is a big reply, use a cluster else
1055 	 * try and leave leading space for the lower level headers.
1056 	 */
1057 	siz += RPC_REPLYSIZ;
1058 	if (siz >= MHLEN - max_hdr) {
1059 		MCLGET(mreq, M_WAIT);
1060 	} else
1061 		mreq->m_data += max_hdr;
1062 	tl = mtod(mreq, u_int32_t *);
1063 	mreq->m_len = 6 * NFSX_UNSIGNED;
1064 	*tl++ = txdr_unsigned(nd->nd_retxid);
1065 	*tl++ = rpc_reply;
1066 	if (err == ERPCMISMATCH || (err & NFSERR_AUTHERR)) {
1067 		*tl++ = rpc_msgdenied;
1068 		if (err & NFSERR_AUTHERR) {
1069 			*tl++ = rpc_autherr;
1070 			*tl = txdr_unsigned(err & ~NFSERR_AUTHERR);
1071 			mreq->m_len -= NFSX_UNSIGNED;
1072 		} else {
1073 			*tl++ = rpc_mismatch;
1074 			*tl++ = txdr_unsigned(RPC_VER2);
1075 			*tl = txdr_unsigned(RPC_VER2);
1076 		}
1077 	} else {
1078 		*tl++ = rpc_msgaccepted;
1079 
1080 		/* AUTH_UNIX requires RPCAUTH_NULL. */
1081 		*tl++ = 0;
1082 		*tl++ = 0;
1083 
1084 		switch (err) {
1085 		case EPROGUNAVAIL:
1086 			*tl = txdr_unsigned(RPC_PROGUNAVAIL);
1087 			break;
1088 		case EPROGMISMATCH:
1089 			*tl = txdr_unsigned(RPC_PROGMISMATCH);
1090 			tl = nfsm_build(&mb, 2 * NFSX_UNSIGNED);
1091 			*tl++ = txdr_unsigned(NFS_VER2);
1092 			*tl = txdr_unsigned(NFS_VER3);
1093 			break;
1094 		case EPROCUNAVAIL:
1095 			*tl = txdr_unsigned(RPC_PROCUNAVAIL);
1096 			break;
1097 		case EBADRPC:
1098 			*tl = txdr_unsigned(RPC_GARBAGE);
1099 			break;
1100 		default:
1101 			*tl = 0;
1102 			if (err != NFSERR_RETVOID) {
1103 				tl = nfsm_build(&mb, NFSX_UNSIGNED);
1104 				if (err)
1105 				    *tl = txdr_unsigned(nfsrv_errmap(nd, err));
1106 				else
1107 				    *tl = 0;
1108 			}
1109 			break;
1110 		};
1111 	}
1112 
1113 	*mrq = mreq;
1114 	if (mbp != NULL)
1115 		*mbp = mb;
1116 	if (err != 0 && err != NFSERR_RETVOID)
1117 		nfsstats.srvrpc_errs++;
1118 	return (0);
1119 }
1120 
1121 /*
1122  * nfs timer routine
1123  * Scan the nfsreq list and retranmit any requests that have timed out.
1124  */
1125 void
1126 nfs_timer(void *arg)
1127 {
1128 	struct nfsmount *nmp = arg;
1129 	struct nfsreq *rep;
1130 	struct mbuf *m;
1131 	struct socket *so;
1132 	int timeo, s, error;
1133 
1134 	NET_LOCK(s);
1135 	TAILQ_FOREACH(rep, &nmp->nm_reqsq, r_chain) {
1136 		if (rep->r_mrep || (rep->r_flags & R_SOFTTERM))
1137 			continue;
1138 		if (nfs_sigintr(nmp, rep, rep->r_procp)) {
1139 			rep->r_flags |= R_SOFTTERM;
1140 			continue;
1141 		}
1142 		if (rep->r_rtt >= 0) {
1143 			rep->r_rtt++;
1144 			if (nmp->nm_flag & NFSMNT_DUMBTIMR)
1145 				timeo = nmp->nm_timeo;
1146 			else
1147 				timeo = nfs_estimate_rto(nmp, rep->r_procnum);
1148 			if (nmp->nm_timeouts > 0)
1149 				timeo *= nfs_backoff[nmp->nm_timeouts - 1];
1150 			if (rep->r_rtt <= timeo)
1151 				continue;
1152 			if (nmp->nm_timeouts < nitems(nfs_backoff))
1153 				nmp->nm_timeouts++;
1154 		}
1155 
1156 		/* Check for server not responding. */
1157 		if ((rep->r_flags & R_TPRINTFMSG) == 0 && rep->r_rexmit > 4) {
1158 			nfs_msg(rep, "not responding");
1159 			rep->r_flags |= R_TPRINTFMSG;
1160 		}
1161 		if (rep->r_rexmit >= nmp->nm_retry) {	/* too many */
1162 			nfsstats.rpctimeouts++;
1163 			rep->r_flags |= R_SOFTTERM;
1164 			continue;
1165 		}
1166 		if (nmp->nm_sotype != SOCK_DGRAM) {
1167 			if (++rep->r_rexmit > NFS_MAXREXMIT)
1168 				rep->r_rexmit = NFS_MAXREXMIT;
1169 			continue;
1170 		}
1171 
1172 		if ((so = nmp->nm_so) == NULL)
1173 			continue;
1174 
1175 		/*
1176 		 * If there is enough space and the window allows..
1177 		 *	Resend it
1178 		 * Set r_rtt to -1 in case we fail to send it now.
1179 		 */
1180 		rep->r_rtt = -1;
1181 		if (sbspace(so, &so->so_snd) >= rep->r_mreq->m_pkthdr.len &&
1182 		   ((nmp->nm_flag & NFSMNT_DUMBTIMR) ||
1183 		    (rep->r_flags & R_SENT) ||
1184 		    nmp->nm_sent < nmp->nm_cwnd) &&
1185 		   (m = m_copym(rep->r_mreq, 0, M_COPYALL, M_DONTWAIT))){
1186 			if ((nmp->nm_flag & NFSMNT_NOCONN) == 0)
1187 			    error = (*so->so_proto->pr_usrreq)(so, PRU_SEND, m,
1188 			    NULL, NULL, curproc);
1189 			else
1190 			    error = (*so->so_proto->pr_usrreq)(so, PRU_SEND, m,
1191 			    nmp->nm_nam, NULL, curproc);
1192 			if (error) {
1193 				if (NFSIGNORE_SOERROR(nmp->nm_soflags, error))
1194 					so->so_error = 0;
1195 			} else {
1196 				/*
1197 				 * Iff first send, start timing
1198 				 * else turn timing off, backoff timer
1199 				 * and divide congestion window by 2.
1200 				 */
1201 				if (rep->r_flags & R_SENT) {
1202 					rep->r_flags &= ~R_TIMING;
1203 					if (++rep->r_rexmit > NFS_MAXREXMIT)
1204 						rep->r_rexmit = NFS_MAXREXMIT;
1205 					nmp->nm_cwnd >>= 1;
1206 					if (nmp->nm_cwnd < NFS_CWNDSCALE)
1207 						nmp->nm_cwnd = NFS_CWNDSCALE;
1208 					nfsstats.rpcretries++;
1209 				} else {
1210 					rep->r_flags |= R_SENT;
1211 					nmp->nm_sent += NFS_CWNDSCALE;
1212 				}
1213 				rep->r_rtt = 0;
1214 			}
1215 		}
1216 	}
1217 	NET_UNLOCK(s);
1218 	timeout_add(&nmp->nm_rtimeout, nfs_ticks);
1219 }
1220 
1221 /*
1222  * Test for a termination condition pending on the process.
1223  * This is used for NFSMNT_INT mounts.
1224  */
1225 int
1226 nfs_sigintr(struct nfsmount *nmp, struct nfsreq *rep, struct proc *p)
1227 {
1228 
1229 	if (rep && (rep->r_flags & R_SOFTTERM))
1230 		return (EINTR);
1231 	if (!(nmp->nm_flag & NFSMNT_INT))
1232 		return (0);
1233 	if (p && p->p_siglist &&
1234 	    (((p->p_siglist & ~p->p_sigmask) &
1235 	    ~p->p_p->ps_sigacts->ps_sigignore) & NFSINT_SIGMASK))
1236 		return (EINTR);
1237 	return (0);
1238 }
1239 
1240 /*
1241  * Lock a socket against others.
1242  * Necessary for STREAM sockets to ensure you get an entire rpc request/reply
1243  * and also to avoid race conditions between the processes with nfs requests
1244  * in progress when a reconnect is necessary.
1245  */
1246 int
1247 nfs_sndlock(int *flagp, struct nfsreq *rep)
1248 {
1249 	struct proc *p;
1250 	int slpflag = 0, slptimeo = 0;
1251 
1252 	if (rep) {
1253 		p = rep->r_procp;
1254 		if (rep->r_nmp->nm_flag & NFSMNT_INT)
1255 			slpflag = PCATCH;
1256 	} else
1257 		p = NULL;
1258 	while (*flagp & NFSMNT_SNDLOCK) {
1259 		if (rep && nfs_sigintr(rep->r_nmp, rep, p))
1260 			return (EINTR);
1261 		*flagp |= NFSMNT_WANTSND;
1262 		(void) tsleep((caddr_t)flagp, slpflag | (PZERO - 1), "nfsndlck",
1263 			slptimeo);
1264 		if (slpflag == PCATCH) {
1265 			slpflag = 0;
1266 			slptimeo = 2 * hz;
1267 		}
1268 	}
1269 	*flagp |= NFSMNT_SNDLOCK;
1270 	return (0);
1271 }
1272 
1273 /*
1274  * Unlock the stream socket for others.
1275  */
1276 void
1277 nfs_sndunlock(int *flagp)
1278 {
1279 
1280 	if ((*flagp & NFSMNT_SNDLOCK) == 0)
1281 		panic("nfs sndunlock");
1282 	*flagp &= ~NFSMNT_SNDLOCK;
1283 	if (*flagp & NFSMNT_WANTSND) {
1284 		*flagp &= ~NFSMNT_WANTSND;
1285 		wakeup((caddr_t)flagp);
1286 	}
1287 }
1288 
1289 int
1290 nfs_rcvlock(struct nfsreq *rep)
1291 {
1292 	int *flagp = &rep->r_nmp->nm_flag;
1293 	int slpflag, slptimeo = 0;
1294 
1295 	if (*flagp & NFSMNT_INT)
1296 		slpflag = PCATCH;
1297 	else
1298 		slpflag = 0;
1299 
1300 	while (*flagp & NFSMNT_RCVLOCK) {
1301 		if (nfs_sigintr(rep->r_nmp, rep, rep->r_procp))
1302 			return (EINTR);
1303 		*flagp |= NFSMNT_WANTRCV;
1304 		(void) tsleep((caddr_t)flagp, slpflag | (PZERO - 1), "nfsrcvlk",
1305 			slptimeo);
1306 		if (rep->r_mrep != NULL) {
1307 			/*
1308 			 * Don't take the lock if our reply has been received
1309 			 * while we where sleeping.
1310 			 */
1311 			 return (EALREADY);
1312 		}
1313 		if (slpflag == PCATCH) {
1314 			slpflag = 0;
1315 			slptimeo = 2 * hz;
1316 		}
1317 	}
1318 	*flagp |= NFSMNT_RCVLOCK;
1319 	return (0);
1320 }
1321 
1322 /*
1323  * Unlock the stream socket for others.
1324  */
1325 void
1326 nfs_rcvunlock(int *flagp)
1327 {
1328 
1329 	if ((*flagp & NFSMNT_RCVLOCK) == 0)
1330 		panic("nfs rcvunlock");
1331 	*flagp &= ~NFSMNT_RCVLOCK;
1332 	if (*flagp & NFSMNT_WANTRCV) {
1333 		*flagp &= ~NFSMNT_WANTRCV;
1334 		wakeup((caddr_t)flagp);
1335 	}
1336 }
1337 
1338 /*
1339  * Auxiliary routine to align the length of mbuf copies made with m_copyback().
1340  */
1341 void
1342 nfs_realign_fixup(struct mbuf *m, struct mbuf *n, unsigned int *off)
1343 {
1344 	size_t padding;
1345 
1346 	/*
1347 	 * The maximum number of bytes that m_copyback() places in a mbuf is
1348 	 * always an aligned quantity, so realign happens at the chain's tail.
1349 	 */
1350 	while (n->m_next != NULL)
1351 		n = n->m_next;
1352 
1353 	/*
1354 	 * Pad from the next elements in the source chain. Loop until the
1355 	 * destination chain is aligned, or the end of the source is reached.
1356 	 */
1357 	do {
1358 		m = m->m_next;
1359 		if (m == NULL)
1360 			return;
1361 
1362 		padding = min(ALIGN(n->m_len) - n->m_len, m->m_len);
1363 		if (padding > M_TRAILINGSPACE(n))
1364 			panic("nfs_realign_fixup: no memory to pad to");
1365 
1366 		bcopy(mtod(m, void *), mtod(n, char *) + n->m_len, padding);
1367 
1368 		n->m_len += padding;
1369 		m_adj(m, padding);
1370 		*off += padding;
1371 
1372 	} while (!ALIGNED_POINTER(n->m_len, void *));
1373 }
1374 
1375 /*
1376  * The NFS RPC parsing code uses the data address and the length of mbuf
1377  * structures to calculate on-memory addresses. This function makes sure these
1378  * parameters are correctly aligned.
1379  */
1380 void
1381 nfs_realign(struct mbuf **pm, int hsiz)
1382 {
1383 	struct mbuf *m;
1384 	struct mbuf *n = NULL;
1385 	unsigned int off = 0;
1386 
1387 	++nfs_realign_test;
1388 	while ((m = *pm) != NULL) {
1389 		if (!ALIGNED_POINTER(m->m_data, void *) ||
1390 		    !ALIGNED_POINTER(m->m_len,  void *)) {
1391 			MGET(n, M_WAIT, MT_DATA);
1392 #define ALIGN_POINTER(n) ((u_int)(((n) + sizeof(void *)) & ~sizeof(void *)))
1393 			if (ALIGN_POINTER(m->m_len) >= MINCLSIZE) {
1394 				MCLGET(n, M_WAIT);
1395 			}
1396 			n->m_len = 0;
1397 			break;
1398 		}
1399 		pm = &m->m_next;
1400 	}
1401 	/*
1402 	 * If n is non-NULL, loop on m copying data, then replace the
1403 	 * portion of the chain that had to be realigned.
1404 	 */
1405 	if (n != NULL) {
1406 		++nfs_realign_count;
1407 		while (m) {
1408 			m_copyback(n, off, m->m_len, mtod(m, caddr_t), M_WAIT);
1409 
1410 			/*
1411 			 * If an unaligned amount of memory was copied, fix up
1412 			 * the last mbuf created by m_copyback().
1413 			 */
1414 			if (!ALIGNED_POINTER(m->m_len, void *))
1415 				nfs_realign_fixup(m, n, &off);
1416 
1417 			off += m->m_len;
1418 			m = m->m_next;
1419 		}
1420 		m_freemp(pm);
1421 		*pm = n;
1422 	}
1423 }
1424 
1425 
1426 /*
1427  * Parse an RPC request
1428  * - verify it
1429  * - fill in the cred struct.
1430  */
1431 int
1432 nfs_getreq(struct nfsrv_descript *nd, struct nfsd *nfsd, int has_header)
1433 {
1434 	int len, i;
1435 	u_int32_t *tl;
1436 	int32_t t1;
1437 	caddr_t cp2;
1438 	u_int32_t nfsvers, auth_type;
1439 	int error = 0;
1440 	struct nfsm_info	info;
1441 
1442 	info.nmi_mrep = nd->nd_mrep;
1443 	info.nmi_md = nd->nd_md;
1444 	info.nmi_dpos = nd->nd_dpos;
1445 	if (has_header) {
1446 		nfsm_dissect(tl, u_int32_t *, 10 * NFSX_UNSIGNED);
1447 		nd->nd_retxid = fxdr_unsigned(u_int32_t, *tl++);
1448 		if (*tl++ != rpc_call) {
1449 			m_freem(info.nmi_mrep);
1450 			return (EBADRPC);
1451 		}
1452 	} else
1453 		nfsm_dissect(tl, u_int32_t *, 8 * NFSX_UNSIGNED);
1454 	nd->nd_repstat = 0;
1455 	nd->nd_flag = 0;
1456 	if (*tl++ != rpc_vers) {
1457 		nd->nd_repstat = ERPCMISMATCH;
1458 		nd->nd_procnum = NFSPROC_NOOP;
1459 		return (0);
1460 	}
1461 	if (*tl != nfs_prog) {
1462 		nd->nd_repstat = EPROGUNAVAIL;
1463 		nd->nd_procnum = NFSPROC_NOOP;
1464 		return (0);
1465 	}
1466 	tl++;
1467 	nfsvers = fxdr_unsigned(u_int32_t, *tl++);
1468 	if (nfsvers != NFS_VER2 && nfsvers != NFS_VER3) {
1469 		nd->nd_repstat = EPROGMISMATCH;
1470 		nd->nd_procnum = NFSPROC_NOOP;
1471 		return (0);
1472 	}
1473 	if (nfsvers == NFS_VER3)
1474 		nd->nd_flag = ND_NFSV3;
1475 	nd->nd_procnum = fxdr_unsigned(u_int32_t, *tl++);
1476 	if (nd->nd_procnum == NFSPROC_NULL)
1477 		return (0);
1478 	if (nd->nd_procnum >= NFS_NPROCS ||
1479 		(nd->nd_procnum > NFSPROC_COMMIT) ||
1480 		(!nd->nd_flag && nd->nd_procnum > NFSV2PROC_STATFS)) {
1481 		nd->nd_repstat = EPROCUNAVAIL;
1482 		nd->nd_procnum = NFSPROC_NOOP;
1483 		return (0);
1484 	}
1485 	if ((nd->nd_flag & ND_NFSV3) == 0)
1486 		nd->nd_procnum = nfsv3_procid[nd->nd_procnum];
1487 	auth_type = *tl++;
1488 	len = fxdr_unsigned(int, *tl++);
1489 	if (len < 0 || len > RPCAUTH_MAXSIZ) {
1490 		m_freem(info.nmi_mrep);
1491 		return (EBADRPC);
1492 	}
1493 
1494 	/* Handle auth_unix */
1495 	if (auth_type == rpc_auth_unix) {
1496 		len = fxdr_unsigned(int, *++tl);
1497 		if (len < 0 || len > NFS_MAXNAMLEN) {
1498 			m_freem(info.nmi_mrep);
1499 			return (EBADRPC);
1500 		}
1501 		nfsm_adv(nfsm_rndup(len));
1502 		nfsm_dissect(tl, u_int32_t *, 3 * NFSX_UNSIGNED);
1503 		memset(&nd->nd_cr, 0, sizeof (struct ucred));
1504 		nd->nd_cr.cr_ref = 1;
1505 		nd->nd_cr.cr_uid = fxdr_unsigned(uid_t, *tl++);
1506 		nd->nd_cr.cr_gid = fxdr_unsigned(gid_t, *tl++);
1507 		len = fxdr_unsigned(int, *tl);
1508 		if (len < 0 || len > RPCAUTH_UNIXGIDS) {
1509 			m_freem(info.nmi_mrep);
1510 			return (EBADRPC);
1511 		}
1512 		nfsm_dissect(tl, u_int32_t *, (len + 2) * NFSX_UNSIGNED);
1513 		for (i = 0; i < len; i++)
1514 		    if (i < NGROUPS_MAX)
1515 			nd->nd_cr.cr_groups[i] = fxdr_unsigned(gid_t, *tl++);
1516 		    else
1517 			tl++;
1518 		nd->nd_cr.cr_ngroups = (len > NGROUPS_MAX) ? NGROUPS_MAX : len;
1519 		len = fxdr_unsigned(int, *++tl);
1520 		if (len < 0 || len > RPCAUTH_MAXSIZ) {
1521 			m_freem(info.nmi_mrep);
1522 			return (EBADRPC);
1523 		}
1524 		if (len > 0)
1525 			nfsm_adv(nfsm_rndup(len));
1526 	} else {
1527 		nd->nd_repstat = (NFSERR_AUTHERR | AUTH_REJECTCRED);
1528 		nd->nd_procnum = NFSPROC_NOOP;
1529 		return (0);
1530 	}
1531 
1532 	nd->nd_md = info.nmi_md;
1533 	nd->nd_dpos = info.nmi_dpos;
1534 	return (0);
1535 nfsmout:
1536 	return (error);
1537 }
1538 
1539 void
1540 nfs_msg(struct nfsreq *rep, char *msg)
1541 {
1542 	tpr_t tpr;
1543 
1544 	if (rep->r_procp)
1545 		tpr = tprintf_open(rep->r_procp);
1546 	else
1547 		tpr = NULL;
1548 
1549 	tprintf(tpr, "nfs server %s: %s\n",
1550 	    rep->r_nmp->nm_mountp->mnt_stat.f_mntfromname, msg);
1551 	tprintf_close(tpr);
1552 }
1553 
1554 #ifdef NFSSERVER
1555 /*
1556  * Socket upcall routine for the nfsd sockets.
1557  * The caddr_t arg is a pointer to the "struct nfssvc_sock".
1558  * Essentially do as much as possible non-blocking, else punt and it will
1559  * be called with M_WAIT from an nfsd.
1560  */
1561 void
1562 nfsrv_rcv(struct socket *so, caddr_t arg, int waitflag)
1563 {
1564 	struct nfssvc_sock *slp = (struct nfssvc_sock *)arg;
1565 	struct mbuf *m;
1566 	struct mbuf *mp, *nam;
1567 	struct uio auio;
1568 	int flags, error;
1569 
1570 	if ((slp->ns_flag & SLP_VALID) == 0)
1571 		return;
1572 
1573 	/* Defer soreceive() to an nfsd. */
1574 	if (waitflag == M_DONTWAIT) {
1575 		slp->ns_flag |= SLP_NEEDQ;
1576 		goto dorecs;
1577 	}
1578 
1579 	auio.uio_procp = NULL;
1580 	if (so->so_type == SOCK_STREAM) {
1581 		/*
1582 		 * Do soreceive().
1583 		 */
1584 		auio.uio_resid = 1000000000;
1585 		flags = MSG_DONTWAIT;
1586 		error = soreceive(so, &nam, &auio, &mp, NULL,
1587 		    &flags, 0);
1588 		if (error || mp == NULL) {
1589 			if (error == EWOULDBLOCK)
1590 				slp->ns_flag |= SLP_NEEDQ;
1591 			else
1592 				slp->ns_flag |= SLP_DISCONN;
1593 			goto dorecs;
1594 		}
1595 		m = mp;
1596 		if (slp->ns_rawend) {
1597 			slp->ns_rawend->m_next = m;
1598 			slp->ns_cc += 1000000000 - auio.uio_resid;
1599 		} else {
1600 			slp->ns_raw = m;
1601 			slp->ns_cc = 1000000000 - auio.uio_resid;
1602 		}
1603 		while (m->m_next)
1604 			m = m->m_next;
1605 		slp->ns_rawend = m;
1606 
1607 		/*
1608 		 * Now try and parse record(s) out of the raw stream data.
1609 		 */
1610 		error = nfsrv_getstream(slp, waitflag);
1611 		if (error) {
1612 			if (error == EPERM)
1613 				slp->ns_flag |= SLP_DISCONN;
1614 			else
1615 				slp->ns_flag |= SLP_NEEDQ;
1616 		}
1617 	} else {
1618 		do {
1619 			auio.uio_resid = 1000000000;
1620 			flags = MSG_DONTWAIT;
1621 			error = soreceive(so, &nam, &auio, &mp,
1622 			    NULL, &flags, 0);
1623 			if (mp) {
1624 				if (nam) {
1625 					m = nam;
1626 					m->m_next = mp;
1627 				} else
1628 					m = mp;
1629 				if (slp->ns_recend)
1630 					slp->ns_recend->m_nextpkt = m;
1631 				else
1632 					slp->ns_rec = m;
1633 				slp->ns_recend = m;
1634 				m->m_nextpkt = NULL;
1635 			}
1636 			if (error) {
1637 				if ((so->so_proto->pr_flags & PR_CONNREQUIRED)
1638 					&& error != EWOULDBLOCK) {
1639 					slp->ns_flag |= SLP_DISCONN;
1640 					goto dorecs;
1641 				}
1642 			}
1643 		} while (mp);
1644 	}
1645 
1646 	/*
1647 	 * Now try and process the request records, non-blocking.
1648 	 */
1649 dorecs:
1650 	if (waitflag == M_DONTWAIT &&
1651 		(slp->ns_rec || (slp->ns_flag & (SLP_NEEDQ | SLP_DISCONN))))
1652 		nfsrv_wakenfsd(slp);
1653 }
1654 
1655 /*
1656  * Try and extract an RPC request from the mbuf data list received on a
1657  * stream socket. The "waitflag" argument indicates whether or not it
1658  * can sleep.
1659  */
1660 int
1661 nfsrv_getstream(struct nfssvc_sock *slp, int waitflag)
1662 {
1663 	struct mbuf *m, **mpp;
1664 	char *cp1, *cp2;
1665 	int len;
1666 	struct mbuf *om, *m2, *recm;
1667 	u_int32_t recmark;
1668 
1669 	if (slp->ns_flag & SLP_GETSTREAM)
1670 		return (0);
1671 	slp->ns_flag |= SLP_GETSTREAM;
1672 	for (;;) {
1673 	    if (slp->ns_reclen == 0) {
1674 		if (slp->ns_cc < NFSX_UNSIGNED) {
1675 			slp->ns_flag &= ~SLP_GETSTREAM;
1676 			return (0);
1677 		}
1678 		m = slp->ns_raw;
1679 		if (m->m_len >= NFSX_UNSIGNED) {
1680 			bcopy(mtod(m, caddr_t), (caddr_t)&recmark, NFSX_UNSIGNED);
1681 			m->m_data += NFSX_UNSIGNED;
1682 			m->m_len -= NFSX_UNSIGNED;
1683 		} else {
1684 			cp1 = (caddr_t)&recmark;
1685 			cp2 = mtod(m, caddr_t);
1686 			while (cp1 < ((caddr_t)&recmark) + NFSX_UNSIGNED) {
1687 				while (m->m_len == 0) {
1688 					m = m->m_next;
1689 					cp2 = mtod(m, caddr_t);
1690 				}
1691 				*cp1++ = *cp2++;
1692 				m->m_data++;
1693 				m->m_len--;
1694 			}
1695 		}
1696 		slp->ns_cc -= NFSX_UNSIGNED;
1697 		recmark = ntohl(recmark);
1698 		slp->ns_reclen = recmark & ~0x80000000;
1699 		if (recmark & 0x80000000)
1700 			slp->ns_flag |= SLP_LASTFRAG;
1701 		else
1702 			slp->ns_flag &= ~SLP_LASTFRAG;
1703 		if (slp->ns_reclen > NFS_MAXPACKET) {
1704 			slp->ns_flag &= ~SLP_GETSTREAM;
1705 			return (EPERM);
1706 		}
1707 	    }
1708 
1709 	    /*
1710 	     * Now get the record part.
1711 	     */
1712 	    recm = NULL;
1713 	    if (slp->ns_cc == slp->ns_reclen) {
1714 		recm = slp->ns_raw;
1715 		slp->ns_raw = slp->ns_rawend = NULL;
1716 		slp->ns_cc = slp->ns_reclen = 0;
1717 	    } else if (slp->ns_cc > slp->ns_reclen) {
1718 		len = 0;
1719 		m = slp->ns_raw;
1720 		om = NULL;
1721 		while (len < slp->ns_reclen) {
1722 			if ((len + m->m_len) > slp->ns_reclen) {
1723 				m2 = m_copym(m, 0, slp->ns_reclen - len,
1724 					waitflag);
1725 				if (m2) {
1726 					if (om) {
1727 						om->m_next = m2;
1728 						recm = slp->ns_raw;
1729 					} else
1730 						recm = m2;
1731 					m->m_data += slp->ns_reclen - len;
1732 					m->m_len -= slp->ns_reclen - len;
1733 					len = slp->ns_reclen;
1734 				} else {
1735 					slp->ns_flag &= ~SLP_GETSTREAM;
1736 					return (EWOULDBLOCK);
1737 				}
1738 			} else if ((len + m->m_len) == slp->ns_reclen) {
1739 				om = m;
1740 				len += m->m_len;
1741 				m = m->m_next;
1742 				recm = slp->ns_raw;
1743 				om->m_next = NULL;
1744 			} else {
1745 				om = m;
1746 				len += m->m_len;
1747 				m = m->m_next;
1748 			}
1749 		}
1750 		slp->ns_raw = m;
1751 		slp->ns_cc -= len;
1752 		slp->ns_reclen = 0;
1753 	    } else {
1754 		slp->ns_flag &= ~SLP_GETSTREAM;
1755 		return (0);
1756 	    }
1757 
1758 	    /*
1759 	     * Accumulate the fragments into a record.
1760 	     */
1761 	    mpp = &slp->ns_frag;
1762 	    while (*mpp)
1763 		mpp = &((*mpp)->m_next);
1764 	    *mpp = recm;
1765 	    if (slp->ns_flag & SLP_LASTFRAG) {
1766 		if (slp->ns_recend)
1767 		    slp->ns_recend->m_nextpkt = slp->ns_frag;
1768 		else
1769 		    slp->ns_rec = slp->ns_frag;
1770 		slp->ns_recend = slp->ns_frag;
1771 		slp->ns_frag = NULL;
1772 	    }
1773 	}
1774 }
1775 
1776 /*
1777  * Parse an RPC header.
1778  */
1779 int
1780 nfsrv_dorec(struct nfssvc_sock *slp, struct nfsd *nfsd,
1781     struct nfsrv_descript **ndp)
1782 {
1783 	struct mbuf *m, *nam;
1784 	struct nfsrv_descript *nd;
1785 	int error;
1786 
1787 	*ndp = NULL;
1788 	if ((slp->ns_flag & SLP_VALID) == 0 ||
1789 	    (m = slp->ns_rec) == NULL)
1790 		return (ENOBUFS);
1791 	slp->ns_rec = m->m_nextpkt;
1792 	if (slp->ns_rec)
1793 		m->m_nextpkt = NULL;
1794 	else
1795 		slp->ns_recend = NULL;
1796 	if (m->m_type == MT_SONAME) {
1797 		nam = m;
1798 		m = m->m_next;
1799 		nam->m_next = NULL;
1800 	} else
1801 		nam = NULL;
1802 	nd = pool_get(&nfsrv_descript_pl, PR_WAITOK);
1803 	nfs_realign(&m, 10 * NFSX_UNSIGNED);
1804 	nd->nd_md = nd->nd_mrep = m;
1805 	nd->nd_nam2 = nam;
1806 	nd->nd_dpos = mtod(m, caddr_t);
1807 	error = nfs_getreq(nd, nfsd, 1);
1808 	if (error) {
1809 		m_freem(nam);
1810 		pool_put(&nfsrv_descript_pl, nd);
1811 		return (error);
1812 	}
1813 	*ndp = nd;
1814 	nfsd->nfsd_nd = nd;
1815 	return (0);
1816 }
1817 
1818 
1819 /*
1820  * Search for a sleeping nfsd and wake it up.
1821  * SIDE EFFECT: If none found, set NFSD_CHECKSLP flag, so that one of the
1822  * running nfsds will go look for the work in the nfssvc_sock list.
1823  */
1824 void
1825 nfsrv_wakenfsd(struct nfssvc_sock *slp)
1826 {
1827 	struct nfsd	*nfsd;
1828 
1829 	if ((slp->ns_flag & SLP_VALID) == 0)
1830 		return;
1831 
1832 	TAILQ_FOREACH(nfsd, &nfsd_head, nfsd_chain) {
1833 		if (nfsd->nfsd_flag & NFSD_WAITING) {
1834 			nfsd->nfsd_flag &= ~NFSD_WAITING;
1835 			if (nfsd->nfsd_slp)
1836 				panic("nfsd wakeup");
1837 			slp->ns_sref++;
1838 			nfsd->nfsd_slp = slp;
1839 			wakeup_one(nfsd);
1840 			return;
1841 		}
1842 	}
1843 
1844 	slp->ns_flag |= SLP_DOREC;
1845 	nfsd_head_flag |= NFSD_CHECKSLP;
1846 }
1847 #endif /* NFSSERVER */
1848