/*
 * Copyright (c) 1989, 1991, 1993, 1995
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Rick Macklem at The University of Guelph.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      @(#)nfs_socket.c        8.5 (Berkeley) 3/30/95
 * $FreeBSD: src/sys/nfs/nfs_socket.c,v 1.60.2.6 2003/03/26 01:44:46 alfred Exp $
 */

/*
 * Socket operations for use by nfs
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/malloc.h>
#include <sys/mount.h>
#include <sys/kernel.h>
#include <sys/mbuf.h>
#include <sys/vnode.h>
#include <sys/fcntl.h>
#include <sys/protosw.h>
#include <sys/resourcevar.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/socketops.h>
#include <sys/syslog.h>
#include <sys/thread.h>
#include <sys/tprintf.h>
#include <sys/sysctl.h>
#include <sys/signalvar.h>

#include <sys/signal2.h>
#include <sys/mutex2.h>
#include <sys/socketvar2.h>

#include <netinet/in.h>
#include <netinet/tcp.h>
#include <sys/thread2.h>

#include "rpcv2.h"
#include "nfsproto.h"
#include "nfs.h"
#include "xdr_subs.h"
#include "nfsm_subs.h"
#include "nfsmount.h"
#include "nfsnode.h"
#include "nfsrtt.h"

#define TRUE    1
#define FALSE   0

/*
 * RTT calculations are scaled by 256 (8 bits).  A proper fractional
 * RTT will still be calculated even with a slow NFS timer.
 */
#define NFS_SRTT(r)     (r)->r_nmp->nm_srtt[proct[(r)->r_procnum]]
#define NFS_SDRTT(r)    (r)->r_nmp->nm_sdrtt[proct[(r)->r_procnum]]
#define NFS_RTT_SCALE_BITS      8       /* bits */
#define NFS_RTT_SCALE           256     /* value */

/*
 * Defines which timer to use for the procnum.
 * 0 - default
 * 1 - getattr
 * 2 - lookup
 * 3 - read
 * 4 - write
 */
static int proct[NFS_NPROCS] = {
        0, 1, 0, 2, 1, 3, 3, 4, 0, 0,   /* 00-09        */
        0, 0, 0, 0, 0, 0, 3, 3, 0, 0,   /* 10-19        */
        0, 5, 0, 0, 0, 0,               /* 20-29        */
};

static int multt[NFS_NPROCS] = {
        1, 1, 1, 1, 1, 1, 1, 1, 1, 1,   /* 00-09        */
        1, 1, 1, 1, 1, 1, 1, 1, 1, 1,   /* 10-19        */
        1, 2, 1, 1, 1, 1,               /* 20-29        */
};

static int nfs_backoff[8] = { 2, 3, 5, 8, 13, 21, 34, 55 };
static int nfs_realign_test;
static int nfs_realign_count;
static int nfs_showrtt;
static int nfs_showrexmit;
int nfs_maxasyncbio = NFS_MAXASYNCBIO;

SYSCTL_DECL(_vfs_nfs);

SYSCTL_INT(_vfs_nfs, OID_AUTO, realign_test, CTLFLAG_RW, &nfs_realign_test, 0,
    "Number of times mbufs have been tested for bad alignment");
SYSCTL_INT(_vfs_nfs, OID_AUTO, realign_count, CTLFLAG_RW, &nfs_realign_count, 0,
    "Number of realignments for badly aligned mbuf data");
SYSCTL_INT(_vfs_nfs, OID_AUTO, showrtt, CTLFLAG_RW, &nfs_showrtt, 0,
    "Show round trip time output");
SYSCTL_INT(_vfs_nfs, OID_AUTO, showrexmit, CTLFLAG_RW, &nfs_showrexmit, 0,
    "Show retransmits info");
SYSCTL_INT(_vfs_nfs, OID_AUTO, maxasyncbio, CTLFLAG_RW, &nfs_maxasyncbio, 0,
    "Max number of asynchronous bio's");

static int nfs_request_setup(nfsm_info_t info);
static int nfs_request_auth(struct nfsreq *rep);
static int nfs_request_try(struct nfsreq *rep);
static int nfs_request_waitreply(struct nfsreq *rep);
static int nfs_request_processreply(nfsm_info_t info, int);

int nfsrtton = 0;
struct nfsrtt nfsrtt;
struct callout  nfs_timer_handle;

static int      nfs_msg (struct thread *,char *,char *);
static int      nfs_rcvlock (struct nfsmount *nmp, struct nfsreq *myreq);
static void     nfs_rcvunlock (struct nfsmount *nmp);
static void     nfs_realign (struct mbuf **pm, int hsiz);
static int      nfs_receive (struct nfsmount *nmp, struct nfsreq *rep,
                                struct sockaddr **aname, struct mbuf **mp);
static void     nfs_softterm (struct nfsreq *rep, int islocked);
static void     nfs_hardterm (struct nfsreq *rep, int islocked);
static int      nfs_reconnect (struct nfsmount *nmp, struct nfsreq *rep);
#ifndef NFS_NOSERVER
static int      nfsrv_getstream (struct nfssvc_sock *, int, int *);
static void     nfs_timer_req(struct nfsreq *req);
static void     nfs_checkpkt(struct mbuf *m, int len);

int (*nfsrv3_procs[NFS_NPROCS]) (struct nfsrv_descript *nd,
                                    struct nfssvc_sock *slp,
                                    struct thread *td,
                                    struct mbuf **mreqp) = {
        nfsrv_null,
        nfsrv_getattr,
        nfsrv_setattr,
        nfsrv_lookup,
        nfsrv3_access,
        nfsrv_readlink,
        nfsrv_read,
        nfsrv_write,
        nfsrv_create,
        nfsrv_mkdir,
        nfsrv_symlink,
        nfsrv_mknod,
        nfsrv_remove,
        nfsrv_rmdir,
        nfsrv_rename,
        nfsrv_link,
        nfsrv_readdir,
        nfsrv_readdirplus,
        nfsrv_statfs,
        nfsrv_fsinfo,
        nfsrv_pathconf,
        nfsrv_commit,
        nfsrv_noop,
        nfsrv_noop,
        nfsrv_noop,
        nfsrv_noop
};
#endif /* NFS_NOSERVER */

/*
 * Initialize sockets and congestion for a new NFS connection.
 * We do not free the sockaddr if error.
 */
int
nfs_connect(struct nfsmount *nmp, struct nfsreq *rep)
{
        struct socket *so;
        int error;
        struct sockaddr *saddr;
        struct sockaddr_in *sin;
        struct thread *td = &thread0; /* only used for socreate and sobind */

        nmp->nm_so = so = NULL;
        if (nmp->nm_flag & NFSMNT_FORCE)
                return (EINVAL);
        saddr = nmp->nm_nam;
        error = socreate(saddr->sa_family, &so, nmp->nm_sotype,
                nmp->nm_soproto, td);
        if (error)
                goto bad;
        nmp->nm_soflags = so->so_proto->pr_flags;

        /*
         * Some servers require that the client port be a reserved port number.
         */
        if (saddr->sa_family == AF_INET && (nmp->nm_flag & NFSMNT_RESVPORT)) {
                struct sockopt sopt;
                int ip;
                struct sockaddr_in ssin;

                bzero(&sopt, sizeof sopt);
                ip = IP_PORTRANGE_LOW;
                sopt.sopt_level = IPPROTO_IP;
                sopt.sopt_name = IP_PORTRANGE;
                sopt.sopt_val = (void *)&ip;
                sopt.sopt_valsize = sizeof(ip);
                sopt.sopt_td = NULL;
                error = sosetopt(so, &sopt);
                if (error)
                        goto bad;
                bzero(&ssin, sizeof ssin);
                sin = &ssin;
                sin->sin_len = sizeof (struct sockaddr_in);
                sin->sin_family = AF_INET;
                sin->sin_addr.s_addr = INADDR_ANY;
                sin->sin_port = htons(0);
                error = sobind(so, (struct sockaddr *)sin, td);
                if (error)
                        goto bad;
                bzero(&sopt, sizeof sopt);
                ip = IP_PORTRANGE_DEFAULT;
                sopt.sopt_level = IPPROTO_IP;
                sopt.sopt_name = IP_PORTRANGE;
                sopt.sopt_val = (void *)&ip;
                sopt.sopt_valsize = sizeof(ip);
                sopt.sopt_td = NULL;
                error = sosetopt(so, &sopt);
                if (error)
                        goto bad;
        }

        /*
         * Protocols that do not require connections may be optionally left
         * unconnected for servers that reply from a port other than NFS_PORT.
         */
        if (nmp->nm_flag & NFSMNT_NOCONN) {
                if (nmp->nm_soflags & PR_CONNREQUIRED) {
                        error = ENOTCONN;
                        goto bad;
                }
        } else {
                error = soconnect(so, nmp->nm_nam, td, TRUE);
                if (error)
                        goto bad;

                /*
                 * Wait for the connection to complete. Cribbed from the
                 * connect system call but with the wait timing out so
                 * that interruptible mounts don't hang here for a long time.
                 */
                crit_enter();
                while ((so->so_state & SS_ISCONNECTING) && so->so_error == 0) {
                        (void) tsleep((caddr_t)&so->so_timeo, 0,
                                "nfscon", 2 * hz);
                        if ((so->so_state & SS_ISCONNECTING) &&
                            so->so_error == 0 && rep &&
                            (error = nfs_sigintr(nmp, rep, rep->r_td)) != 0){
                                soclrstate(so, SS_ISCONNECTING);
                                crit_exit();
                                goto bad;
                        }
                }
                if (so->so_error) {
                        error = so->so_error;
                        so->so_error = 0;
                        crit_exit();
                        goto bad;
                }
                crit_exit();
        }
        so->so_rcv.ssb_timeo = (5 * hz);
        so->so_snd.ssb_timeo = (5 * hz);

        /*
         * Get buffer reservation size from sysctl, but impose reasonable
         * limits.
         */
        if (nmp->nm_sotype == SOCK_STREAM) {
                if (so->so_proto->pr_flags & PR_CONNREQUIRED) {
                        struct sockopt sopt;
                        int val;

                        bzero(&sopt, sizeof sopt);
                        sopt.sopt_level = SOL_SOCKET;
                        sopt.sopt_name = SO_KEEPALIVE;
                        sopt.sopt_val = &val;
                        sopt.sopt_valsize = sizeof val;
                        val = 1;
                        sosetopt(so, &sopt);
                }
                if (so->so_proto->pr_protocol == IPPROTO_TCP) {
                        struct sockopt sopt;
                        int val;

                        bzero(&sopt, sizeof sopt);
                        sopt.sopt_level = IPPROTO_TCP;
                        sopt.sopt_name = TCP_NODELAY;
                        sopt.sopt_val = &val;
                        sopt.sopt_valsize = sizeof val;
                        val = 1;
                        sosetopt(so, &sopt);

                        bzero(&sopt, sizeof sopt);
                        sopt.sopt_level = IPPROTO_TCP;
                        sopt.sopt_name = TCP_FASTKEEP;
                        sopt.sopt_val = &val;
                        sopt.sopt_valsize = sizeof val;
                        val = 1;
                        sosetopt(so, &sopt);
                }
        }
        error = soreserve(so, nfs_soreserve, nfs_soreserve, NULL);
        if (error)
                goto bad;
        atomic_set_int(&so->so_rcv.ssb_flags, SSB_NOINTR);
        atomic_set_int(&so->so_snd.ssb_flags, SSB_NOINTR);

        /*
         * Clear AUTOSIZE, otherwise the socket buffer could be reduced
         * to the point where rpc's cannot be queued using the mbuf
         * interface.
         */
        atomic_clear_int(&so->so_rcv.ssb_flags, SSB_AUTOSIZE);
        atomic_clear_int(&so->so_snd.ssb_flags, SSB_AUTOSIZE);

        /* Initialize other non-zero congestion variables */
        nmp->nm_srtt[0] = nmp->nm_srtt[1] = nmp->nm_srtt[2] =
                nmp->nm_srtt[3] = (NFS_TIMEO << NFS_RTT_SCALE_BITS);
        nmp->nm_sdrtt[0] = nmp->nm_sdrtt[1] = nmp->nm_sdrtt[2] =
                nmp->nm_sdrtt[3] = 0;
        nmp->nm_maxasync_scaled = NFS_MINASYNC_SCALED;
        nmp->nm_timeouts = 0;

        /*
         * Assign nm_so last.  The moment nm_so is assigned the nfs_timer()
         * can mess with the socket.
         */
        nmp->nm_so = so;
        return (0);

bad:
        if (so) {
                soshutdown(so, SHUT_RDWR);
                soclose(so, FNONBLOCK);
        }
        return (error);
}

/*
 * Reconnect routine:
 * Called when a connection is broken on a reliable protocol.
 * - clean up the old socket
 * - nfs_connect() again
 * - set R_NEEDSXMIT for all outstanding requests on mount point
 * If this fails the mount point is DEAD!
 * nb: Must be called with the nfs_sndlock() set on the mount point.
 */
static int
nfs_reconnect(struct nfsmount *nmp, struct nfsreq *rep)
{
        struct nfsreq *req;
        int error;

        nfs_disconnect(nmp);
        if (nmp->nm_rxstate >= NFSSVC_STOPPING)
                return (EINTR);
        while ((error = nfs_connect(nmp, rep)) != 0) {
                if (error == EINTR || error == ERESTART)
                        return (EINTR);
                if (error == EINVAL)
                        return (error);
                if (nmp->nm_rxstate >= NFSSVC_STOPPING)
                        return (EINTR);
                (void) tsleep((caddr_t)&lbolt, 0, "nfscon", 0);
        }

        /*
         * Loop through outstanding request list and fix up all requests
         * on old socket.
         */
        crit_enter();
        TAILQ_FOREACH(req, &nmp->nm_reqq, r_chain) {
                KKASSERT(req->r_nmp == nmp);
                req->r_flags |= R_NEEDSXMIT;
        }
        crit_exit();
        return (0);
}

/*
 * NFS disconnect. Clean up and unlink.
 */
void
nfs_disconnect(struct nfsmount *nmp)
{
        struct socket *so;

        if (nmp->nm_so) {
                so = nmp->nm_so;
                nmp->nm_so = NULL;
                soshutdown(so, SHUT_RDWR);
                soclose(so, FNONBLOCK);
        }
}

void
nfs_safedisconnect(struct nfsmount *nmp)
{
        int error;

        error = nfs_rcvlock(nmp, NULL);
        nfs_disconnect(nmp);
        if (error == 0)
                nfs_rcvunlock(nmp);
}

/*
 * This is the nfs send routine. For connection based socket types, it
 * must be called with an nfs_sndlock() on the socket.
 * "rep == NULL" indicates that it has been called from a server.
 * For the client side:
 * - return EINTR if the RPC is terminated, 0 otherwise
 * - set R_NEEDSXMIT if the send fails for any reason
 * - do any cleanup required by recoverable socket errors (?)
 * For the server side:
 * - return EINTR or ERESTART if interrupted by a signal
 * - return EPIPE if a connection is lost for connection based sockets (TCP...)
 * - do any cleanup required by recoverable socket errors (?)
 */
int
nfs_send(struct socket *so, struct sockaddr *nam, struct mbuf *top,
         struct nfsreq *rep)
{
        struct sockaddr *sendnam;
        int error, soflags, flags;

        if (rep) {
                if (rep->r_flags & R_SOFTTERM) {
                        m_freem(top);
                        return (EINTR);
                }
                if ((so = rep->r_nmp->nm_so) == NULL) {
                        rep->r_flags |= R_NEEDSXMIT;
                        m_freem(top);
                        return (0);
                }
                rep->r_flags &= ~R_NEEDSXMIT;
                soflags = rep->r_nmp->nm_soflags;
        } else {
                soflags = so->so_proto->pr_flags;
        }
        if ((soflags & PR_CONNREQUIRED) || (so->so_state & SS_ISCONNECTED))
                sendnam = NULL;
        else
                sendnam = nam;
        if (so->so_type == SOCK_SEQPACKET)
                flags = MSG_EOR;
        else
                flags = 0;

        /*
         * calls pru_sosend -> sosend -> so_pru_send -> netrpc
         */
        error = so_pru_sosend(so, sendnam, NULL, top, NULL, flags,
                              curthread /*XXX*/);

        /*
         * ENOBUFS for dgram sockets is transient and non fatal.
         * No need to log, and no need to break a soft mount.
         */
        if (error == ENOBUFS && so->so_type == SOCK_DGRAM) {
                error = 0;
                /*
                 * do backoff retransmit on client
                 */
                if (rep) {
                        if ((rep->r_nmp->nm_state & NFSSTA_SENDSPACE) == 0) {
                                rep->r_nmp->nm_state |= NFSSTA_SENDSPACE;
                                kprintf("Warning: NFS: Insufficient sendspace "
                                        "(%lu),\n"
                                        "\t You must increase vfs.nfs.soreserve"
                                        "or decrease vfs.nfs.maxasyncbio\n",
                                        so->so_snd.ssb_hiwat);
                        }
                        rep->r_flags |= R_NEEDSXMIT;
                }
        }

        if (error) {
                if (rep) {
                        log(LOG_INFO, "nfs send error %d for server %s\n",error,
                            rep->r_nmp->nm_mountp->mnt_stat.f_mntfromname);
                        /*
                         * Deal with errors for the client side.
                         */
                        if (rep->r_flags & R_SOFTTERM)
                                error = EINTR;
                        else
                                rep->r_flags |= R_NEEDSXMIT;
                } else {
                        log(LOG_INFO, "nfsd send error %d\n", error);
                }

                /*
                 * Handle any recoverable (soft) socket errors here. (?)
                 */
                if (error != EINTR && error != ERESTART &&
                        error != EWOULDBLOCK && error != EPIPE)
                        error = 0;
        }
        return (error);
}

/*
 * Receive a Sun RPC Request/Reply. For SOCK_DGRAM, the work is all
 * done by soreceive(), but for SOCK_STREAM we must deal with the Record
 * Mark and consolidate the data into a new mbuf list.
 * nb: Sometimes TCP passes the data up to soreceive() in long lists of
 *     small mbufs.
 * For SOCK_STREAM we must be very careful to read an entire record once
 * we have read any of it, even if the system call has been interrupted.
 */
static int
nfs_receive(struct nfsmount *nmp, struct nfsreq *rep,
            struct sockaddr **aname, struct mbuf **mp)
{
        struct socket *so;
        struct sockbuf sio;
        struct uio auio;
        struct iovec aio;
        struct mbuf *m;
        struct mbuf *control;
        u_int32_t len;
        struct sockaddr **getnam;
        int error, sotype, rcvflg;
        struct thread *td = curthread;  /* XXX */

        /*
         * Set up arguments for soreceive()
         */
        *mp = NULL;
        *aname = NULL;
        sotype = nmp->nm_sotype;

        /*
         * For reliable protocols, lock against other senders/receivers
         * in case a reconnect is necessary.
         * For SOCK_STREAM, first get the Record Mark to find out how much
         * more there is to get.
         * We must lock the socket against other receivers
         * until we have an entire rpc request/reply.
         */
        if (sotype != SOCK_DGRAM) {
                error = nfs_sndlock(nmp, rep);
                if (error)
                        return (error);
tryagain:
                /*
                 * Check for fatal errors and resending request.
                 */
                /*
                 * Ugh: If a reconnect attempt just happened, nm_so
                 * would have changed. NULL indicates a failed
                 * attempt that has essentially shut down this
                 * mount point.
                 */
                if (rep && (rep->r_mrep || (rep->r_flags & R_SOFTTERM))) {
                        nfs_sndunlock(nmp);
                        return (EINTR);
                }
                so = nmp->nm_so;
                if (so == NULL) {
                        error = nfs_reconnect(nmp, rep);
                        if (error) {
                                nfs_sndunlock(nmp);
                                return (error);
                        }
                        goto tryagain;
                }
                while (rep && (rep->r_flags & R_NEEDSXMIT)) {
                        m = m_copym(rep->r_mreq, 0, M_COPYALL, M_WAITOK);
                        nfsstats.rpcretries++;
                        error = nfs_send(so, rep->r_nmp->nm_nam, m, rep);
                        if (error) {
                                if (error == EINTR || error == ERESTART ||
                                    (error = nfs_reconnect(nmp, rep)) != 0) {
                                        nfs_sndunlock(nmp);
                                        return (error);
                                }
                                goto tryagain;
                        }
                }
                nfs_sndunlock(nmp);
                if (sotype == SOCK_STREAM) {
                        /*
                         * Get the length marker from the stream
                         */
                        aio.iov_base = (caddr_t)&len;
                        aio.iov_len = sizeof(u_int32_t);
                        auio.uio_iov = &aio;
                        auio.uio_iovcnt = 1;
                        auio.uio_segflg = UIO_SYSSPACE;
                        auio.uio_rw = UIO_READ;
                        auio.uio_offset = 0;
                        auio.uio_resid = sizeof(u_int32_t);
                        auio.uio_td = td;
                        do {
                           rcvflg = MSG_WAITALL;
                           error = so_pru_soreceive(so, NULL, &auio, NULL,
                                                    NULL, &rcvflg);
                           if (error == EWOULDBLOCK && rep) {
                                if (rep->r_flags & R_SOFTTERM)
                                        return (EINTR);
                           }
                        } while (error == EWOULDBLOCK);

                        if (error == 0 && auio.uio_resid > 0) {
                            /*
                             * Only log short packets if not EOF
                             */
                            if (auio.uio_resid != sizeof(u_int32_t)) {
                                log(LOG_INFO,
                                    "short receive (%d/%d) from nfs server %s\n",
                                    (int)(sizeof(u_int32_t) - auio.uio_resid),
                                    (int)sizeof(u_int32_t),
                                    nmp->nm_mountp->mnt_stat.f_mntfromname);
                            }
                            error = EPIPE;
                        }
                        if (error)
                                goto errout;
                        len = ntohl(len) & ~0x80000000;
                        /*
                         * This is SERIOUS! We are out of sync with the sender
                         * and forcing a disconnect/reconnect is all I can do.
                         */
                        if (len > NFS_MAXPACKET) {
                            log(LOG_ERR, "%s (%d) from nfs server %s\n",
                                "impossible packet length",
                                len,
                                nmp->nm_mountp->mnt_stat.f_mntfromname);
                            error = EFBIG;
                            goto errout;
                        }

                        /*
                         * Get the rest of the packet as an mbuf chain
                         */
                        sbinit(&sio, len);
                        do {
                            rcvflg = MSG_WAITALL;
                            error = so_pru_soreceive(so, NULL, NULL, &sio,
                                                     NULL, &rcvflg);
                        } while (error == EWOULDBLOCK || error == EINTR ||
                                 error == ERESTART);
                        if (error == 0 && sio.sb_cc != len) {
                            if (sio.sb_cc != 0) {
                                log(LOG_INFO,
                                    "short receive (%zu/%d) from nfs server %s\n",
                                    (size_t)len - auio.uio_resid, len,
                                    nmp->nm_mountp->mnt_stat.f_mntfromname);
                            }
                            error = EPIPE;
                        }
                        *mp = sio.sb_mb;
                } else {
                        /*
                         * Non-stream, so get the whole packet by not
                         * specifying MSG_WAITALL and by specifying a large
                         * length.
                         *
                         * We have no use for control msg., but must grab them
                         * and then throw them away so we know what is going
                         * on.
                         */
                        sbinit(&sio, 100000000);
                        do {
                            rcvflg = 0;
                            error =  so_pru_soreceive(so, NULL, NULL, &sio,
                                                      &control, &rcvflg);
                            if (control)
                                m_freem(control);
                            if (error == EWOULDBLOCK && rep) {
                                if (rep->r_flags & R_SOFTTERM) {
                                        m_freem(sio.sb_mb);
                                        return (EINTR);
                                }
                            }
                        } while (error == EWOULDBLOCK ||
                                 (error == 0 && sio.sb_mb == NULL && control));
                        if ((rcvflg & MSG_EOR) == 0)
                                kprintf("Egad!!\n");
                        if (error == 0 && sio.sb_mb == NULL)
                                error = EPIPE;
                        len = sio.sb_cc;
                        *mp = sio.sb_mb;
                }
errout:
                if (error && error != EINTR && error != ERESTART) {
                        m_freem(*mp);
                        *mp = NULL;
                        if (error != EPIPE) {
                                log(LOG_INFO,
                                    "receive error %d from nfs server %s\n",
                                    error,
                                 nmp->nm_mountp->mnt_stat.f_mntfromname);
                        }
                        error = nfs_sndlock(nmp, rep);
                        if (!error) {
                                error = nfs_reconnect(nmp, rep);
                                if (!error)
                                        goto tryagain;
                                else
                                        nfs_sndunlock(nmp);
                        }
                }
        } else {
                if ((so = nmp->nm_so) == NULL)
                        return (EACCES);
                if (so->so_state & SS_ISCONNECTED)
                        getnam = NULL;
                else
                        getnam = aname;
                sbinit(&sio, 100000000);
                do {
                        rcvflg = 0;
                        error =  so_pru_soreceive(so, getnam, NULL, &sio,
                                                  NULL, &rcvflg);
                        if (error == EWOULDBLOCK && rep &&
                            (rep->r_flags & R_SOFTTERM)) {
                                m_freem(sio.sb_mb);
                                return (EINTR);
                        }
                } while (error == EWOULDBLOCK);

                len = sio.sb_cc;
                *mp = sio.sb_mb;

                /*
                 * A shutdown may result in no error and no mbuf.
                 * Convert to EPIPE.
                 */
                if (*mp == NULL && error == 0)
                        error = EPIPE;
        }
        if (error) {
                m_freem(*mp);
                *mp = NULL;
        }

        /*
         * Search for any mbufs that are not a multiple of 4 bytes long
         * or with m_data not longword aligned.
         * These could cause pointer alignment problems, so copy them to
         * well aligned mbufs.
         */
        nfs_realign(mp, 5 * NFSX_UNSIGNED);
        return (error);
}

/*
 * Implement receipt of reply on a socket.
 *
 * We must search through the list of received datagrams matching them
 * with outstanding requests using the xid, until ours is found.
 *
 * If myrep is NULL we process packets on the socket until
 * interrupted or until nm_reqrxq is non-empty.
 */
/* ARGSUSED */
int
nfs_reply(struct nfsmount *nmp, struct nfsreq *myrep)
{
        struct nfsreq *rep;
        struct sockaddr *nam;
        u_int32_t rxid;
        u_int32_t *tl;
        int error;
        struct nfsm_info info;

        /*
         * Loop around until we get our own reply
         */
        for (;;) {
                /*
                 * Lock against other receivers so that I don't get stuck in
                 * sbwait() after someone else has received my reply for me.
                 * Also necessary for connection based protocols to avoid
                 * race conditions during a reconnect.
                 *
                 * If nfs_rcvlock() returns EALREADY, that means that
                 * the reply has already been recieved by another
                 * process and we can return immediately.  In this
                 * case, the lock is not taken to avoid races with
                 * other processes.
                 */
                info.mrep = NULL;

                error = nfs_rcvlock(nmp, myrep);
                if (error == EALREADY)
                        return (0);
                if (error)
                        return (error);

                /*
                 * If myrep is NULL we are the receiver helper thread.
                 * Stop waiting for incoming replies if there are
                 * messages sitting on reqrxq that we need to process,
                 * or if a shutdown request is pending.
                 */
                if (myrep == NULL && (TAILQ_FIRST(&nmp->nm_reqrxq) ||
                    nmp->nm_rxstate > NFSSVC_PENDING)) {
                        nfs_rcvunlock(nmp);
                        return(EWOULDBLOCK);
                }

                /*
                 * Get the next Rpc reply off the socket
                 *
                 * We cannot release the receive lock until we've
                 * filled in rep->r_mrep, otherwise a waiting
                 * thread may deadlock in soreceive with no incoming
                 * packets expected.
                 */
                error = nfs_receive(nmp, myrep, &nam, &info.mrep);
                if (error) {
                        /*
                         * Ignore routing errors on connectionless protocols??
                         */
                        nfs_rcvunlock(nmp);
                        if (NFSIGNORE_SOERROR(nmp->nm_soflags, error)) {
                                if (nmp->nm_so == NULL)
                                        return (error);
                                nmp->nm_so->so_error = 0;
                                continue;
                        }
                        return (error);
                }
                if (nam)
                        kfree(nam, M_SONAME);

                /*
                 * Get the xid and check that it is an rpc reply
                 */
                info.md = info.mrep;
                info.dpos = mtod(info.md, caddr_t);
                NULLOUT(tl = nfsm_dissect(&info, 2*NFSX_UNSIGNED));
                rxid = *tl++;
                if (*tl != rpc_reply) {
                        nfsstats.rpcinvalid++;
                        m_freem(info.mrep);
                        info.mrep = NULL;
nfsmout:
                        nfs_rcvunlock(nmp);
                        continue;
                }

                /*
                 * Loop through the request list to match up the reply
                 * Iff no match, just drop the datagram.  On match, set
                 * r_mrep atomically to prevent the timer from messing
                 * around with the request after we have exited the critical
                 * section.
                 */
                crit_enter();
                TAILQ_FOREACH(rep, &nmp->nm_reqq, r_chain) {
                        if (rep->r_mrep == NULL && rxid == rep->r_xid)
                                break;
                }

                /*
                 * Fill in the rest of the reply if we found a match.
                 *
                 * Deal with duplicate responses if there was no match.
                 */
                if (rep) {
                        rep->r_md = info.md;
                        rep->r_dpos = info.dpos;
                        if (nfsrtton) {
                                struct rttl *rt;

                                rt = &nfsrtt.rttl[nfsrtt.pos];
                                rt->proc = rep->r_procnum;
                                rt->rto = 0;
                                rt->sent = 0;
                                rt->cwnd = nmp->nm_maxasync_scaled;
                                rt->srtt = nmp->nm_srtt[proct[rep->r_procnum] - 1];
                                rt->sdrtt = nmp->nm_sdrtt[proct[rep->r_procnum] - 1];
                                rt->fsid = nmp->nm_mountp->mnt_stat.f_fsid;
                                getmicrotime(&rt->tstamp);
                                if (rep->r_flags & R_TIMING)
                                        rt->rtt = rep->r_rtt;
                                else
                                        rt->rtt = 1000000;
                                nfsrtt.pos = (nfsrtt.pos + 1) % NFSRTTLOGSIZ;
                        }

                        /*
                         * New congestion control is based only on async
                         * requests.
                         */
                        if (nmp->nm_maxasync_scaled < NFS_MAXASYNC_SCALED)
                                ++nmp->nm_maxasync_scaled;
                        if (rep->r_flags & R_SENT) {
                                rep->r_flags &= ~R_SENT;
                        }
                        /*
                         * Update rtt using a gain of 0.125 on the mean
                         * and a gain of 0.25 on the deviation.
                         *
                         * NOTE SRTT/SDRTT are only good if R_TIMING is set.
                         */
                        if ((rep->r_flags & R_TIMING) && rep->r_rexmit == 0) {
                                /*
                                 * Since the timer resolution of
                                 * NFS_HZ is so course, it can often
                                 * result in r_rtt == 0. Since
                                 * r_rtt == N means that the actual
                                 * rtt is between N+dt and N+2-dt ticks,
                                 * add 1.
                                 */
                                int n;
                                int d;

#define NFSRSB  NFS_RTT_SCALE_BITS
                                n = ((NFS_SRTT(rep) * 7) +
                                     (rep->r_rtt << NFSRSB)) >> 3;
                                d = n - NFS_SRTT(rep);
                                NFS_SRTT(rep) = n;

                                /*
                                 * Don't let the jitter calculation decay
                                 * too quickly, but we want a fast rampup.
                                 */
                                if (d < 0)
                                        d = -d;
                                d <<= NFSRSB;
                                if (d < NFS_SDRTT(rep))
                                        n = ((NFS_SDRTT(rep) * 15) + d) >> 4;
                                else
                                        n = ((NFS_SDRTT(rep) * 3) + d) >> 2;
                                NFS_SDRTT(rep) = n;
#undef NFSRSB
                        }
                        nmp->nm_timeouts = 0;
                        rep->r_mrep = info.mrep;
                        nfs_hardterm(rep, 0);
                } else {
                        /*
                         * Extract vers, prog, nfsver, procnum.  A duplicate
                         * response means we didn't wait long enough so
                         * we increase the SRTT to avoid future spurious
                         * timeouts.
                         */
                        u_int procnum = nmp->nm_lastreprocnum;
                        int n;

                        if (procnum < NFS_NPROCS && proct[procnum]) {
                                if (nfs_showrexmit)
                                        kprintf("D");
                                n = nmp->nm_srtt[proct[procnum]];
                                n += NFS_ASYSCALE * NFS_HZ;
                                if (n < NFS_ASYSCALE * NFS_HZ * 10)
                                        n = NFS_ASYSCALE * NFS_HZ * 10;
                                nmp->nm_srtt[proct[procnum]] = n;
                        }
                }
                nfs_rcvunlock(nmp);
                crit_exit();

                /*
                 * If not matched to a request, drop it.
                 * If it's mine, get out.
                 */
                if (rep == NULL) {
                        nfsstats.rpcunexpected++;
                        m_freem(info.mrep);
                        info.mrep = NULL;
                } else if (rep == myrep) {
                        if (rep->r_mrep == NULL)
                                panic("nfsreply nil");
                        return (0);
                }
        }
}

/*
 * Run the request state machine until the target state is reached
 * or a fatal error occurs.  The target state is not run.  Specifying
 * a target of NFSM_STATE_DONE runs the state machine until the rpc
 * is complete.
 *
 * EINPROGRESS is returned for all states other then the DONE state,
 * indicating that the rpc is still in progress.
 */
int
nfs_request(struct nfsm_info *info, nfsm_state_t bstate, nfsm_state_t estate)
{
        struct nfsreq *req;

        while (info->state >= bstate && info->state < estate) {
                switch(info->state) {
                case NFSM_STATE_SETUP:
                        /*
                         * Setup the nfsreq.  Any error which occurs during
                         * this state is fatal.
                         */
                        info->error = nfs_request_setup(info);
                        if (info->error) {
                                info->state = NFSM_STATE_DONE;
                                return (info->error);
                        } else {
                                req = info->req;
                                req->r_mrp = &info->mrep;
                                req->r_mdp = &info->md;
                                req->r_dposp = &info->dpos;
                                info->state = NFSM_STATE_AUTH;
                        }
                        break;
                case NFSM_STATE_AUTH:
                        /*
                         * Authenticate the nfsreq.  Any error which occurs
                         * during this state is fatal.
                         */
                        info->error = nfs_request_auth(info->req);
                        if (info->error) {
                                info->state = NFSM_STATE_DONE;
                                return (info->error);
                        } else {
                                info->state = NFSM_STATE_TRY;
                        }
                        break;
                case NFSM_STATE_TRY:
                        /*
                         * Transmit or retransmit attempt.  An error in this
                         * state is ignored and we always move on to the
                         * next state.
                         *
                         * This can trivially race the receiver if the
                         * request is asynchronous.  nfs_request_try()
                         * will thus set the state for us and we
                         * must also return immediately if we are
                         * running an async state machine, because
                         * info can become invalid due to races after
                         * try() returns.
                         */
                        if (info->req->r_flags & R_ASYNC) {
                                nfs_request_try(info->req);
                                if (estate == NFSM_STATE_WAITREPLY)
                                        return (EINPROGRESS);
                        } else {
                                nfs_request_try(info->req);
                                info->state = NFSM_STATE_WAITREPLY;
                        }
                        break;
                case NFSM_STATE_WAITREPLY:
                        /*
                         * Wait for a reply or timeout and move on to the
                         * next state.  The error returned by this state
                         * is passed to the processing code in the next
                         * state.
                         */
                        info->error = nfs_request_waitreply(info->req);
                        info->state = NFSM_STATE_PROCESSREPLY;
                        break;
                case NFSM_STATE_PROCESSREPLY:
                        /*
                         * Process the reply or timeout.  Errors which occur
                         * in this state may cause the state machine to
                         * go back to an earlier state, and are fatal
                         * otherwise.
                         */
                        info->error = nfs_request_processreply(info,
                                                               info->error);
                        switch(info->error) {
                        case ENEEDAUTH:
                                info->state = NFSM_STATE_AUTH;
                                break;
                        case EAGAIN:
                                info->state = NFSM_STATE_TRY;
                                break;
                        default:
                                /*
                                 * Operation complete, with or without an
                                 * error.  We are done.
                                 */
                                info->req = NULL;
                                info->state = NFSM_STATE_DONE;
                                return (info->error);
                        }
                        break;
                case NFSM_STATE_DONE:
                        /*
                         * Shouldn't be reached
                         */
                        return (info->error);
                        /* NOT REACHED */
                }
        }

        /*
         * If we are done return the error code (if any).
         * Otherwise return EINPROGRESS.
         */
        if (info->state == NFSM_STATE_DONE)
                return (info->error);
        return (EINPROGRESS);
}

/*
 * nfs_request - goes something like this
 *      - fill in request struct
 *      - links it into list
 *      - calls nfs_send() for first transmit
 *      - calls nfs_receive() to get reply
 *      - break down rpc header and return with nfs reply pointed to
 *        by mrep or error
 * nb: always frees up mreq mbuf list
 */
static int
nfs_request_setup(nfsm_info_t info)
{
        struct nfsreq *req;
        struct nfsmount *nmp;
        struct mbuf *m;
        int i;

        /*
         * Reject requests while attempting a forced unmount.
         */
        if (info->vp->v_mount->mnt_kern_flag & MNTK_UNMOUNTF) {
                m_freem(info->mreq);
                info->mreq = NULL;
                return (EIO);
        }
        nmp = VFSTONFS(info->vp->v_mount);
        req = kmalloc(sizeof(struct nfsreq), M_NFSREQ, M_WAITOK);
        req->r_nmp = nmp;
        req->r_vp = info->vp;
        req->r_td = info->td;
        req->r_procnum = info->procnum;
        req->r_mreq = NULL;
        req->r_cred = info->cred;

        i = 0;
        m = info->mreq;
        while (m) {
                i += m->m_len;
                m = m->m_next;
        }
        req->r_mrest = info->mreq;
        req->r_mrest_len = i;

        /*
         * The presence of a non-NULL r_info in req indicates
         * async completion via our helper threads.  See the receiver
         * code.
         */
        if (info->bio) {
                req->r_info = info;
                req->r_flags = R_ASYNC;
        } else {
                req->r_info = NULL;
                req->r_flags = 0;
        }
        info->req = req;
        return(0);
}

static int
nfs_request_auth(struct nfsreq *rep)
{
        struct nfsmount *nmp = rep->r_nmp;
        struct mbuf *m;
        char nickv[RPCX_NICKVERF];
        int error = 0, auth_len, auth_type;
        int verf_len;
        u_int32_t xid;
        char *auth_str, *verf_str;
        struct ucred *cred;

        cred = rep->r_cred;
        rep->r_failed_auth = 0;

        /*
         * Get the RPC header with authorization.
         */
        verf_str = auth_str = NULL;
        verf_len = 0;
        if (nmp->nm_flag & NFSMNT_KERB) {
                verf_str = nickv;
                verf_len = sizeof (nickv);
                auth_type = RPCAUTH_KERB4;
                bzero((caddr_t)rep->r_key, sizeof(rep->r_key));
                if (rep->r_failed_auth ||
                    nfs_getnickauth(nmp, cred, &auth_str, &auth_len,
                                    verf_str, verf_len)) {
                        error = nfs_getauth(nmp, rep, cred, &auth_str,
                                &auth_len, verf_str, &verf_len, rep->r_key);
                        if (error) {
                                m_freem(rep->r_mrest);
                                rep->r_mrest = NULL;
                                kfree((caddr_t)rep, M_NFSREQ);
                                return (error);
                        }
                }
        } else {
                auth_type = RPCAUTH_UNIX;
                if (cred->cr_ngroups < 1)
                        panic("nfsreq nogrps");
                auth_len = ((((cred->cr_ngroups - 1) > nmp->nm_numgrps) ?
                        nmp->nm_numgrps : (cred->cr_ngroups - 1)) << 2) +
                        5 * NFSX_UNSIGNED;
        }
        if (rep->r_mrest)
                nfs_checkpkt(rep->r_mrest, rep->r_mrest_len);
        m = nfsm_rpchead(cred, nmp->nm_flag, rep->r_procnum, auth_type,
                        auth_len, auth_str, verf_len, verf_str,
                        rep->r_mrest, rep->r_mrest_len, &rep->r_mheadend, &xid);
        rep->r_mrest = NULL;
        if (auth_str)
                kfree(auth_str, M_TEMP);

        /*
         * For stream protocols, insert a Sun RPC Record Mark.
         */
        if (nmp->nm_sotype == SOCK_STREAM) {
                M_PREPEND(m, NFSX_UNSIGNED, M_WAITOK);
                *mtod(m, u_int32_t *) = htonl(0x80000000 |
                         (m->m_pkthdr.len - NFSX_UNSIGNED));
        }

        nfs_checkpkt(m, m->m_pkthdr.len);

        rep->r_mreq = m;
        rep->r_xid = xid;
        return (0);
}

static int
nfs_request_try(struct nfsreq *rep)
{
        struct nfsmount *nmp = rep->r_nmp;
        struct mbuf *m2;
        int error;

        /*
         * Request is not on any queue, only the owner has access to it
         * so it should not be locked by anyone atm.
         *
         * Interlock to prevent races.  While locked the only remote
         * action possible is for r_mrep to be set (once we enqueue it).
         */
        if (rep->r_flags == 0xdeadc0de) {
                print_backtrace(-1);
                panic("flags nbad");
        }
        KKASSERT((rep->r_flags & (R_LOCKED | R_ONREQQ)) == 0);
        if (nmp->nm_flag & NFSMNT_SOFT)
                rep->r_retry = nmp->nm_retry;
        else
                rep->r_retry = NFS_MAXREXMIT + 1;       /* past clip limit */
        rep->r_rtt = rep->r_rexmit = 0;
        if (proct[rep->r_procnum] > 0)
                rep->r_flags |= R_TIMING | R_LOCKED;
        else
                rep->r_flags |= R_LOCKED;
        rep->r_mrep = NULL;

        nfsstats.rpcrequests++;

        if (nmp->nm_flag & NFSMNT_FORCE) {
                rep->r_flags |= R_SOFTTERM;
                rep->r_flags &= ~R_LOCKED;
                if (rep->r_info)
                        rep->r_info->error = EINTR;
                return (0);
        }
        rep->r_flags |= R_NEEDSXMIT;    /* in case send lock races us */

        /*
         * Do the client side RPC.
         *
         * Chain request into list of outstanding requests. Be sure
         * to put it LAST so timer finds oldest requests first.  Note
         * that our control of R_LOCKED prevents the request from
         * getting ripped out from under us or transmitted by the
         * timer code.
         *
         * For requests with info structures we must atomically set the
         * info's state because the structure could become invalid upon
         * return due to races (i.e., if async)
         */
        crit_enter();
        mtx_link_init(&rep->r_link);
        KKASSERT((rep->r_flags & R_ONREQQ) == 0);
        TAILQ_INSERT_TAIL(&nmp->nm_reqq, rep, r_chain);
        rep->r_flags |= R_ONREQQ;
        ++nmp->nm_reqqlen;
        if (rep->r_flags & R_ASYNC)
                rep->r_info->state = NFSM_STATE_WAITREPLY;
        crit_exit();

        error = 0;

        /*
         * Send if we can.  Congestion control is not handled here any more
         * becausing trying to defer the initial send based on the nfs_timer
         * requires having a very fast nfs_timer, which is silly.
         */
        if (nmp->nm_so) {
                if (nmp->nm_soflags & PR_CONNREQUIRED)
                        error = nfs_sndlock(nmp, rep);
                if (error == 0 && (rep->r_flags & R_NEEDSXMIT)) {
                        m2 = m_copym(rep->r_mreq, 0, M_COPYALL, M_WAITOK);
                        error = nfs_send(nmp->nm_so, nmp->nm_nam, m2, rep);
                        rep->r_flags &= ~R_NEEDSXMIT;
                        if ((rep->r_flags & R_SENT) == 0) {
                                rep->r_flags |= R_SENT;
                        }
                        if (nmp->nm_soflags & PR_CONNREQUIRED)
                                nfs_sndunlock(nmp);
                }
        } else {
                rep->r_rtt = -1;
        }
        if (error == EPIPE)
                error = 0;

        /*
         * Release the lock.  The only remote action that may have occurred
         * would have been the setting of rep->r_mrep.  If this occured
         * and the request was async we have to move it to the reader
         * thread's queue for action.
         *
         * For async requests also make sure the reader is woken up so
         * it gets on the socket to read responses.
         */
        crit_enter();
        if (rep->r_flags & R_ASYNC) {
                if (rep->r_mrep)
                        nfs_hardterm(rep, 1);
                rep->r_flags &= ~R_LOCKED;
                nfssvc_iod_reader_wakeup(nmp);
        } else {
                rep->r_flags &= ~R_LOCKED;
        }
        if (rep->r_flags & R_WANTED) {
                rep->r_flags &= ~R_WANTED;
                wakeup(rep);
        }
        crit_exit();
        return (error);
}

/*
 * This code is only called for synchronous requests.  Completed synchronous
 * requests are left on reqq and we remove them before moving on to the
 * processing state.
 */
static int
nfs_request_waitreply(struct nfsreq *rep)
{
        struct nfsmount *nmp = rep->r_nmp;
        int error;

        KKASSERT((rep->r_flags & R_ASYNC) == 0);

        /*
         * Wait until the request is finished.
         */
        error = nfs_reply(nmp, rep);

        /*
         * RPC done, unlink the request, but don't rip it out from under
         * the callout timer.
         *
         * Once unlinked no other receiver or the timer will have
         * visibility, so we do not have to set R_LOCKED.
         */
        crit_enter();
        while (rep->r_flags & R_LOCKED) {
                rep->r_flags |= R_WANTED;
                tsleep(rep, 0, "nfstrac", 0);
        }
        KKASSERT(rep->r_flags & R_ONREQQ);
        TAILQ_REMOVE(&nmp->nm_reqq, rep, r_chain);
        rep->r_flags &= ~R_ONREQQ;
        --nmp->nm_reqqlen;
        if (TAILQ_FIRST(&nmp->nm_bioq) &&
            nmp->nm_reqqlen <= nfs_maxasyncbio * 2 / 3) {
                nfssvc_iod_writer_wakeup(nmp);
        }
        crit_exit();

        /*
         * Decrement the outstanding request count.
         */
        if (rep->r_flags & R_SENT) {
                rep->r_flags &= ~R_SENT;
        }
        return (error);
}

/*
 * Process reply with error returned from nfs_requet_waitreply().
 *
 * Returns EAGAIN if it wants us to loop up to nfs_request_try() again.
 * Returns ENEEDAUTH if it wants us to loop up to nfs_request_auth() again.
 */
static int
nfs_request_processreply(nfsm_info_t info, int error)
{
        struct nfsreq *req = info->req;
        struct nfsmount *nmp = req->r_nmp;
        u_int32_t *tl;
        int verf_type;
        int i;

        /*
         * If there was a successful reply and a tprintf msg.
         * tprintf a response.
         */
        if (error == 0 && (req->r_flags & R_TPRINTFMSG)) {
                nfs_msg(req->r_td,
                        nmp->nm_mountp->mnt_stat.f_mntfromname,
                        "is alive again");
        }

        /*
         * Assign response and handle any pre-process error.  Response
         * fields can be NULL if an error is already pending.
         */
        info->mrep = req->r_mrep;
        info->md = req->r_md;
        info->dpos = req->r_dpos;

        if (error) {
                m_freem(req->r_mreq);
                req->r_mreq = NULL;
                kfree(req, M_NFSREQ);
                info->req = NULL;
                return (error);
        }

        /*
         * break down the rpc header and check if ok
         */
        NULLOUT(tl = nfsm_dissect(info, 3 * NFSX_UNSIGNED));
        if (*tl++ == rpc_msgdenied) {
                if (*tl == rpc_mismatch) {
                        error = EOPNOTSUPP;
                } else if ((nmp->nm_flag & NFSMNT_KERB) &&
                           *tl++ == rpc_autherr) {
                        if (req->r_failed_auth == 0) {
                                req->r_failed_auth++;
                                req->r_mheadend->m_next = NULL;
                                m_freem(info->mrep);
                                info->mrep = NULL;
                                m_freem(req->r_mreq);
                                req->r_mreq = NULL;
                                return (ENEEDAUTH);
                        } else {
                                error = EAUTH;
                        }
                } else {
                        error = EACCES;
                }
                m_freem(info->mrep);
                info->mrep = NULL;
                m_freem(req->r_mreq);
                req->r_mreq = NULL;
                kfree(req, M_NFSREQ);
                info->req = NULL;
                return (error);
        }

        /*
         * Grab any Kerberos verifier, otherwise just throw it away.
         */
        verf_type = fxdr_unsigned(int, *tl++);
        i = fxdr_unsigned(int32_t, *tl);
        if ((nmp->nm_flag & NFSMNT_KERB) && verf_type == RPCAUTH_KERB4) {
                error = nfs_savenickauth(nmp, req->r_cred, i, req->r_key,
                                         &info->md, &info->dpos, info->mrep);
                if (error)
                        goto nfsmout;
        } else if (i > 0) {
                ERROROUT(nfsm_adv(info, nfsm_rndup(i)));
        }
        NULLOUT(tl = nfsm_dissect(info, NFSX_UNSIGNED));
        /* 0 == ok */
        if (*tl == 0) {
                NULLOUT(tl = nfsm_dissect(info, NFSX_UNSIGNED));
                if (*tl != 0) {
                        error = fxdr_unsigned(int, *tl);

                        /*
                         * Does anyone even implement this?  Just impose
                         * a 1-second delay.
                         */
                        if ((nmp->nm_flag & NFSMNT_NFSV3) &&
                                error == NFSERR_TRYLATER) {
                                m_freem(info->mrep);
                                info->mrep = NULL;
                                error = 0;

                                tsleep((caddr_t)&lbolt, 0, "nqnfstry", 0);
                                return (EAGAIN);        /* goto tryagain */
                        }

#if 0
                        /*
                         * XXX We can't do this here any more because the
                         *     caller may be holding a shared lock on the
                         *     namecache entry.
                         *
                         * If the File Handle was stale, invalidate the
                         * lookup cache, just in case.
                         *
                         * To avoid namecache<->vnode deadlocks we must
                         * release the vnode lock if we hold it.
                         */
                        if (error == ESTALE) {
                                struct vnode *vp = req->r_vp;
                                int ltype;

                                ltype = lockstatus(&vp->v_lock, curthread);
                                if (ltype == LK_EXCLUSIVE || ltype == LK_SHARED)
                                        lockmgr(&vp->v_lock, LK_RELEASE);
                                cache_inval_vp(vp, CINV_CHILDREN);
                                if (ltype == LK_EXCLUSIVE || ltype == LK_SHARED)
                                        lockmgr(&vp->v_lock, ltype);
                        }
#endif
                        if (nmp->nm_flag & NFSMNT_NFSV3) {
                                KKASSERT(*req->r_mrp == info->mrep);
                                KKASSERT(*req->r_mdp == info->md);
                                KKASSERT(*req->r_dposp == info->dpos);
                                error |= NFSERR_RETERR;
                        } else {
                                m_freem(info->mrep);
                                info->mrep = NULL;
                        }
                        m_freem(req->r_mreq);
                        req->r_mreq = NULL;
                        kfree(req, M_NFSREQ);
                        info->req = NULL;
                        return (error);
                }

                KKASSERT(*req->r_mrp == info->mrep);
                KKASSERT(*req->r_mdp == info->md);
                KKASSERT(*req->r_dposp == info->dpos);
                m_freem(req->r_mreq);
                req->r_mreq = NULL;
                kfree(req, M_NFSREQ);
                return (0);
        }
        m_freem(info->mrep);
        info->mrep = NULL;
        error = EPROTONOSUPPORT;
nfsmout:
        m_freem(req->r_mreq);
        req->r_mreq = NULL;
        kfree(req, M_NFSREQ);
        info->req = NULL;
        return (error);
}

#ifndef NFS_NOSERVER
/*
 * Generate the rpc reply header
 * siz arg. is used to decide if adding a cluster is worthwhile
 */
int
nfs_rephead(int siz, struct nfsrv_descript *nd, struct nfssvc_sock *slp,
            int err, struct mbuf **mrq, struct mbuf **mbp, caddr_t *bposp)
{
        u_int32_t *tl;
        struct nfsm_info info;

        siz += RPC_REPLYSIZ;
        info.mb = m_getl(max_hdr + siz, M_WAITOK, MT_DATA, M_PKTHDR, NULL);
        info.mreq = info.mb;
        info.mreq->m_pkthdr.len = 0;
        /*
         * If this is not a cluster, try and leave leading space
         * for the lower level headers.
         */
        if ((max_hdr + siz) < MINCLSIZE)
                info.mreq->m_data += max_hdr;
        tl = mtod(info.mreq, u_int32_t *);
        info.mreq->m_len = 6 * NFSX_UNSIGNED;
        info.bpos = ((caddr_t)tl) + info.mreq->m_len;
        *tl++ = txdr_unsigned(nd->nd_retxid);
        *tl++ = rpc_reply;
        if (err == ERPCMISMATCH || (err & NFSERR_AUTHERR)) {
                *tl++ = rpc_msgdenied;
                if (err & NFSERR_AUTHERR) {
                        *tl++ = rpc_autherr;
                        *tl = txdr_unsigned(err & ~NFSERR_AUTHERR);
                        info.mreq->m_len -= NFSX_UNSIGNED;
                        info.bpos -= NFSX_UNSIGNED;
                } else {
                        *tl++ = rpc_mismatch;
                        *tl++ = txdr_unsigned(RPC_VER2);
                        *tl = txdr_unsigned(RPC_VER2);
                }
        } else {
                *tl++ = rpc_msgaccepted;

                /*
                 * For Kerberos authentication, we must send the nickname
                 * verifier back, otherwise just RPCAUTH_NULL.
                 */
                if (nd->nd_flag & ND_KERBFULL) {
                    struct nfsuid *nuidp;
                    struct timeval ktvout;

                    for (nuidp = NUIDHASH(slp, nd->nd_cr.cr_uid)->lh_first;
                        nuidp != NULL; nuidp = nuidp->nu_hash.le_next) {
                        if (nuidp->nu_cr.cr_uid == nd->nd_cr.cr_uid &&
                            (!nd->nd_nam2 || netaddr_match(AF_INET,
                             &nuidp->nu_haddr, nd->nd_nam2)))
                            break;
                    }
                    if (nuidp) {
                        /*
                         * Encrypt the timestamp in ecb mode using the
                         * session key.
                         */
#ifdef NFSKERB
                        XXX
#else
                        ktvout.tv_sec = 0;
                        ktvout.tv_usec = 0;
#endif

                        *tl++ = rpc_auth_kerb;
                        *tl++ = txdr_unsigned(3 * NFSX_UNSIGNED);
                        *tl = ktvout.tv_sec;
                        tl = nfsm_build(&info, 3 * NFSX_UNSIGNED);
                        *tl++ = ktvout.tv_usec;
                        *tl++ = txdr_unsigned(nuidp->nu_cr.cr_uid);
                    } else {
                        *tl++ = 0;
                        *tl++ = 0;
                    }
                } else {
                        *tl++ = 0;
                        *tl++ = 0;
                }
                switch (err) {
                case EPROGUNAVAIL:
                        *tl = txdr_unsigned(RPC_PROGUNAVAIL);
                        break;
                case EPROGMISMATCH:
                        *tl = txdr_unsigned(RPC_PROGMISMATCH);
                        tl = nfsm_build(&info, 2 * NFSX_UNSIGNED);
                        *tl++ = txdr_unsigned(2);
                        *tl = txdr_unsigned(3);
                        break;
                case EPROCUNAVAIL:
                        *tl = txdr_unsigned(RPC_PROCUNAVAIL);
                        break;
                case EBADRPC:
                        *tl = txdr_unsigned(RPC_GARBAGE);
                        break;
                default:
                        *tl = 0;
                        if (err != NFSERR_RETVOID) {
                                tl = nfsm_build(&info, NFSX_UNSIGNED);
                                if (err)
                                    *tl = txdr_unsigned(nfsrv_errmap(nd, err));
                                else
                                    *tl = 0;
                        }
                        break;
                }
        }

        if (mrq != NULL)
            *mrq = info.mreq;
        *mbp = info.mb;
        *bposp = info.bpos;
        if (err != 0 && err != NFSERR_RETVOID)
                nfsstats.srvrpc_errs++;
        return (0);
}


#endif /* NFS_NOSERVER */

/*
 * Nfs timer routine.
 *
 * Scan the nfsreq list and retranmit any requests that have timed out
 * To avoid retransmission attempts on STREAM sockets (in the future) make
 * sure to set the r_retry field to 0 (implies nm_retry == 0).
 *
 * Requests with attached responses, terminated requests, and
 * locked requests are ignored.  Locked requests will be picked up
 * in a later timer call.
 */
void
nfs_timer_callout(void *arg /* never used */)
{
        struct nfsmount *nmp;
        struct nfsreq *req;
#ifndef NFS_NOSERVER
        struct nfssvc_sock *slp;
        u_quad_t cur_usec;
#endif /* NFS_NOSERVER */

        lwkt_gettoken(&nfs_token);
        TAILQ_FOREACH(nmp, &nfs_mountq, nm_entry) {
                lwkt_gettoken(&nmp->nm_token);
                TAILQ_FOREACH(req, &nmp->nm_reqq, r_chain) {
                        KKASSERT(nmp == req->r_nmp);
                        if (req->r_mrep)
                                continue;
                        if (req->r_flags & (R_SOFTTERM | R_LOCKED))
                                continue;

                        /*
                         * Handle timeout/retry.  Be sure to process r_mrep
                         * for async requests that completed while we had
                         * the request locked or they will hang in the reqq
                         * forever.
                         */
                        req->r_flags |= R_LOCKED;
                        if (nfs_sigintr(nmp, req, req->r_td)) {
                                nfs_softterm(req, 1);
                                req->r_flags &= ~R_LOCKED;
                        } else {
                                nfs_timer_req(req);
                                if (req->r_flags & R_ASYNC) {
                                        if (req->r_mrep)
                                                nfs_hardterm(req, 1);
                                        req->r_flags &= ~R_LOCKED;
                                        nfssvc_iod_reader_wakeup(nmp);
                                } else {
                                        req->r_flags &= ~R_LOCKED;
                                }
                        }
                        if (req->r_flags & R_WANTED) {
                                req->r_flags &= ~R_WANTED;
                                wakeup(req);
                        }
                }
                lwkt_reltoken(&nmp->nm_token);
        }
#ifndef NFS_NOSERVER

        /*
         * Scan the write gathering queues for writes that need to be
         * completed now.
         */
        cur_usec = nfs_curusec();

        TAILQ_FOREACH(slp, &nfssvc_sockhead, ns_chain) {
                /* XXX race against removal */
                if (lwkt_trytoken(&slp->ns_token)) {
                        if (slp->ns_tq.lh_first &&
                            (slp->ns_tq.lh_first->nd_time <= cur_usec)) {
                                nfsrv_wakenfsd(slp, 1);
                        }
                        lwkt_reltoken(&slp->ns_token);
                }
        }
#endif /* NFS_NOSERVER */

        callout_reset(&nfs_timer_handle, nfs_ticks, nfs_timer_callout, NULL);
        lwkt_reltoken(&nfs_token);
}

static
void
nfs_timer_req(struct nfsreq *req)
{
        struct thread *td = &thread0; /* XXX for creds, will break if sleep */
        struct nfsmount *nmp = req->r_nmp;
        struct mbuf *m;
        struct socket *so;
        int timeo;
        int error;

        /*
         * rtt ticks and timeout calculation.  Return if the timeout
         * has not been reached yet, unless the packet is flagged
         * for an immediate send.
         *
         * The mean rtt doesn't help when we get random I/Os, we have
         * to multiply by fairly large numbers.
         */
        if (req->r_rtt >= 0) {
                /*
                 * Calculate the timeout to test against.
                 */
                req->r_rtt++;
                if (nmp->nm_flag & NFSMNT_DUMBTIMR) {
                        timeo = nmp->nm_timeo << NFS_RTT_SCALE_BITS;
                } else if (req->r_flags & R_TIMING) {
                        timeo = NFS_SRTT(req) + NFS_SDRTT(req);
                } else {
                        timeo = nmp->nm_timeo << NFS_RTT_SCALE_BITS;
                }
                timeo *= multt[req->r_procnum];
                /* timeo is still scaled by SCALE_BITS */

#define NFSFS   (NFS_RTT_SCALE * NFS_HZ)
                if (req->r_flags & R_TIMING) {
                        static long last_time;
                        if (nfs_showrtt && last_time != time_uptime) {
                                kprintf("rpccmd %d NFS SRTT %d SDRTT %d "
                                        "timeo %d.%03d\n",
                                        proct[req->r_procnum],
                                        NFS_SRTT(req), NFS_SDRTT(req),
                                        timeo / NFSFS,
                                        timeo % NFSFS * 1000 /  NFSFS);
                                last_time = time_uptime;
                        }
                }
#undef NFSFS

                /*
                 * deal with nfs_timer jitter.
                 */
                timeo = (timeo >> NFS_RTT_SCALE_BITS) + 1;
                if (timeo < 2)
                        timeo = 2;

                if (nmp->nm_timeouts > 0)
                        timeo *= nfs_backoff[nmp->nm_timeouts - 1];
                if (timeo > NFS_MAXTIMEO)
                        timeo = NFS_MAXTIMEO;
                if (req->r_rtt <= timeo) {
                        if ((req->r_flags & R_NEEDSXMIT) == 0)
                                return;
                } else if (nmp->nm_timeouts < 8) {
                        nmp->nm_timeouts++;
                }
        }

        /*
         * Check for server not responding
         */
        if ((req->r_flags & R_TPRINTFMSG) == 0 &&
             req->r_rexmit > nmp->nm_deadthresh) {
                nfs_msg(req->r_td, nmp->nm_mountp->mnt_stat.f_mntfromname,
                        "not responding");
                req->r_flags |= R_TPRINTFMSG;
        }
        if (req->r_rexmit >= req->r_retry) {    /* too many */
                nfsstats.rpctimeouts++;
                nfs_softterm(req, 1);
                return;
        }

        /*
         * Generally disable retransmission on reliable sockets,
         * unless the request is flagged for immediate send.
         */
        if (nmp->nm_sotype != SOCK_DGRAM) {
                if (++req->r_rexmit > NFS_MAXREXMIT)
                        req->r_rexmit = NFS_MAXREXMIT;
                if ((req->r_flags & R_NEEDSXMIT) == 0)
                        return;
        }

        /*
         * Stop here if we do not have a socket!
         */
        if ((so = nmp->nm_so) == NULL)
                return;

        /*
         * If there is enough space and the window allows.. resend it.
         *
         * r_rtt is left intact in case we get an answer after the
         * retry that was a reply to the original packet.
         *
         * NOTE: so_pru_send()
         */
        if (ssb_space(&so->so_snd) >= req->r_mreq->m_pkthdr.len &&
            (req->r_flags & (R_SENT | R_NEEDSXMIT)) &&
           (m = m_copym(req->r_mreq, 0, M_COPYALL, M_NOWAIT))){
                if ((nmp->nm_flag & NFSMNT_NOCONN) == 0)
                    error = so_pru_send(so, 0, m, NULL, NULL, td);
                else
                    error = so_pru_send(so, 0, m, nmp->nm_nam, NULL, td);
                if (error) {
                        if (NFSIGNORE_SOERROR(nmp->nm_soflags, error))
                                so->so_error = 0;
                        req->r_flags |= R_NEEDSXMIT;
                } else if (req->r_mrep == NULL) {
                        /*
                         * Iff first send, start timing
                         * else turn timing off, backoff timer
                         * and divide congestion window by 2.
                         *
                         * It is possible for the so_pru_send() to
                         * block and for us to race a reply so we
                         * only do this if the reply field has not
                         * been filled in.  R_LOCKED will prevent
                         * the request from being ripped out from under
                         * us entirely.
                         *
                         * Record the last resent procnum to aid us
                         * in duplicate detection on receive.
                         */
                        if ((req->r_flags & R_NEEDSXMIT) == 0) {
                                if (nfs_showrexmit)
                                        kprintf("X");
                                if (++req->r_rexmit > NFS_MAXREXMIT)
                                        req->r_rexmit = NFS_MAXREXMIT;
                                nmp->nm_maxasync_scaled >>= 1;
                                if (nmp->nm_maxasync_scaled < NFS_MINASYNC_SCALED)
                                        nmp->nm_maxasync_scaled = NFS_MINASYNC_SCALED;
                                nfsstats.rpcretries++;
                                nmp->nm_lastreprocnum = req->r_procnum;
                        } else {
                                req->r_flags |= R_SENT;
                                req->r_flags &= ~R_NEEDSXMIT;
                        }
                }
        }
}

/*
 * Mark all of an nfs mount's outstanding requests with R_SOFTTERM and
 * wait for all requests to complete. This is used by forced unmounts
 * to terminate any outstanding RPCs.
 *
 * Locked requests cannot be canceled but will be marked for
 * soft-termination.
 */
int
nfs_nmcancelreqs(struct nfsmount *nmp)
{
        struct nfsreq *req;
        int i;

        crit_enter();
        TAILQ_FOREACH(req, &nmp->nm_reqq, r_chain) {
                if (req->r_mrep != NULL || (req->r_flags & R_SOFTTERM))
                        continue;
                nfs_softterm(req, 0);
        }
        /* XXX  the other two queues as well */
        crit_exit();

        for (i = 0; i < 30; i++) {
                crit_enter();
                TAILQ_FOREACH(req, &nmp->nm_reqq, r_chain) {
                        if (nmp == req->r_nmp)
                                break;
                }
                crit_exit();
                if (req == NULL)
                        return (0);
                tsleep(&lbolt, 0, "nfscancel", 0);
        }
        return (EBUSY);
}

/*
 * Soft-terminate a request, effectively marking it as failed.
 *
 * Must be called from within a critical section.
 */
static void
nfs_softterm(struct nfsreq *rep, int islocked)
{
        rep->r_flags |= R_SOFTTERM;
        if (rep->r_info)
                rep->r_info->error = EINTR;
        nfs_hardterm(rep, islocked);
}

/*
 * Hard-terminate a request, typically after getting a response.
 *
 * The state machine can still decide to re-issue it later if necessary.
 *
 * Must be called from within a critical section.
 */
static void
nfs_hardterm(struct nfsreq *rep, int islocked)
{
        struct nfsmount *nmp = rep->r_nmp;

        /*
         * The nm_send count is decremented now to avoid deadlocks
         * when the process in soreceive() hasn't yet managed to send
         * its own request.
         */
        if (rep->r_flags & R_SENT) {
                rep->r_flags &= ~R_SENT;
        }

        /*
         * If we locked the request or nobody else has locked the request,
         * and the request is async, we can move it to the reader thread's
         * queue now and fix up the state.
         *
         * If we locked the request or nobody else has locked the request,
         * we can wake up anyone blocked waiting for a response on the
         * request.
         */
        if (islocked || (rep->r_flags & R_LOCKED) == 0) {
                if ((rep->r_flags & (R_ONREQQ | R_ASYNC)) ==
                    (R_ONREQQ | R_ASYNC)) {
                        rep->r_flags &= ~R_ONREQQ;
                        TAILQ_REMOVE(&nmp->nm_reqq, rep, r_chain);
                        --nmp->nm_reqqlen;
                        TAILQ_INSERT_TAIL(&nmp->nm_reqrxq, rep, r_chain);
                        KKASSERT(rep->r_info->state == NFSM_STATE_TRY ||
                                 rep->r_info->state == NFSM_STATE_WAITREPLY);

                        /*
                         * When setting the state to PROCESSREPLY we must
                         * roll-up any error not related to the contents of
                         * the reply (i.e. if there is no contents).
                         */
                        rep->r_info->state = NFSM_STATE_PROCESSREPLY;
                        nfssvc_iod_reader_wakeup(nmp);
                        if (TAILQ_FIRST(&nmp->nm_bioq) &&
                            nmp->nm_reqqlen <= nfs_maxasyncbio * 2 / 3) {
                                nfssvc_iod_writer_wakeup(nmp);
                        }
                }
                mtx_abort_link(&nmp->nm_rxlock, &rep->r_link);
        }
}

/*
 * Test for a termination condition pending on the process.
 * This is used for NFSMNT_INT mounts.
 */
int
nfs_sigintr(struct nfsmount *nmp, struct nfsreq *rep, struct thread *td)
{
        sigset_t tmpset;
        struct proc *p;
        struct lwp *lp;

        if (rep && (rep->r_flags & R_SOFTTERM))
                return (EINTR);
        /* Terminate all requests while attempting a forced unmount. */
        if (nmp->nm_mountp->mnt_kern_flag & MNTK_UNMOUNTF)
                return (EINTR);
        if (!(nmp->nm_flag & NFSMNT_INT))
                return (0);
        /* td might be NULL YYY */
        if (td == NULL || (p = td->td_proc) == NULL)
                return (0);

        lp = td->td_lwp;
        tmpset = lwp_sigpend(lp);
        SIGSETNAND(tmpset, lp->lwp_sigmask);
        SIGSETNAND(tmpset, p->p_sigignore);
        if (SIGNOTEMPTY(tmpset) && NFSINT_SIGMASK(tmpset))
                return (EINTR);

        return (0);
}

/*
 * Lock a socket against others.
 * Necessary for STREAM sockets to ensure you get an entire rpc request/reply
 * and also to avoid race conditions between the processes with nfs requests
 * in progress when a reconnect is necessary.
 */
int
nfs_sndlock(struct nfsmount *nmp, struct nfsreq *rep)
{
        mtx_t *mtx = &nmp->nm_txlock;
        struct thread *td;
        int slptimeo;
        int slpflag;
        int error;

        slpflag = 0;
        slptimeo = 0;
        td = rep ? rep->r_td : NULL;
        if (nmp->nm_flag & NFSMNT_INT)
                slpflag = PCATCH;

        while ((error = mtx_lock_ex_try(mtx)) != 0) {
                if (nfs_sigintr(nmp, rep, td)) {
                        error = EINTR;
                        break;
                }
                error = mtx_lock_ex(mtx, slpflag, slptimeo);
                if (error == 0)
                        break;
                if (slpflag == PCATCH) {
                        slpflag = 0;
                        slptimeo = 2 * hz;
                }
        }
        /* Always fail if our request has been cancelled. */
        if (rep && (rep->r_flags & R_SOFTTERM)) {
                if (error == 0)
                        mtx_unlock(mtx);
                error = EINTR;
        }
        return (error);
}

/*
 * Unlock the stream socket for others.
 */
void
nfs_sndunlock(struct nfsmount *nmp)
{
        mtx_unlock(&nmp->nm_txlock);
}

/*
 * Lock the receiver side of the socket.
 *
 * rep may be NULL.
 */
static int
nfs_rcvlock(struct nfsmount *nmp, struct nfsreq *rep)
{
        mtx_t *mtx = &nmp->nm_rxlock;
        int slpflag;
        int slptimeo;
        int error;

        /*
         * Unconditionally check for completion in case another nfsiod
         * get the packet while the caller was blocked, before the caller
         * called us.  Packet reception is handled by mainline code which
         * is protected by the BGL at the moment.
         *
         * We do not strictly need the second check just before the
         * tsleep(), but it's good defensive programming.
         */
        if (rep && rep->r_mrep != NULL)
                return (EALREADY);

        if (nmp->nm_flag & NFSMNT_INT)
                slpflag = PCATCH;
        else
                slpflag = 0;
        slptimeo = 0;

        while ((error = mtx_lock_ex_try(mtx)) != 0) {
                if (nfs_sigintr(nmp, rep, (rep ? rep->r_td : NULL))) {
                        error = EINTR;
                        break;
                }
                if (rep && rep->r_mrep != NULL) {
                        error = EALREADY;
                        break;
                }

                /*
                 * NOTE: can return ENOLCK, but in that case rep->r_mrep
                 *       will already be set.
                 */
                if (rep) {
                        error = mtx_lock_ex_link(mtx, &rep->r_link,
                                                 slpflag, slptimeo);
                } else {
                        error = mtx_lock_ex(mtx, slpflag, slptimeo);
                }
                if (error == 0)
                        break;

                /*
                 * If our reply was recieved while we were sleeping,
                 * then just return without taking the lock to avoid a
                 * situation where a single iod could 'capture' the
                 * recieve lock.
                 */
                if (rep && rep->r_mrep != NULL) {
                        error = EALREADY;
                        break;
                }
                if (slpflag == PCATCH) {
                        slpflag = 0;
                        slptimeo = 2 * hz;
                }
        }
        if (error == 0) {
                if (rep && rep->r_mrep != NULL) {
                        error = EALREADY;
                        mtx_unlock(mtx);
                }
        }
        return (error);
}

/*
 * Unlock the stream socket for others.
 */
static void
nfs_rcvunlock(struct nfsmount *nmp)
{
        mtx_unlock(&nmp->nm_rxlock);
}

/*
 * nfs_realign:
 *
 * Check for badly aligned mbuf data and realign by copying the unaligned
 * portion of the data into a new mbuf chain and freeing the portions
 * of the old chain that were replaced.
 *
 * We cannot simply realign the data within the existing mbuf chain
 * because the underlying buffers may contain other rpc commands and
 * we cannot afford to overwrite them.
 *
 * We would prefer to avoid this situation entirely.  The situation does
 * not occur with NFS/UDP and is supposed to only occassionally occur
 * with TCP.  Use vfs.nfs.realign_count and realign_test to check this.
 *
 * NOTE!  M_NOWAIT cannot be used here.  The mbufs must be acquired
 *        because the rpc request OR reply cannot be thrown away.  TCP NFS
 *        mounts do not retry their RPCs unless the TCP connection itself
 *        is dropped so throwing away a RPC will basically cause the NFS
 *        operation to lockup indefinitely.
 */
static void
nfs_realign(struct mbuf **pm, int hsiz)
{
        struct mbuf *m;
        struct mbuf *n = NULL;

        /*
         * Check for misalignemnt
         */
        ++nfs_realign_test;
        while ((m = *pm) != NULL) {
                if ((m->m_len & 0x3) || (mtod(m, intptr_t) & 0x3))
                        break;
                pm = &m->m_next;
        }

        /*
         * If misalignment found make a completely new copy.
         */
        if (m) {
                ++nfs_realign_count;
                n = m_dup_data(m, M_WAITOK);
                m_freem(*pm);
                *pm = n;
        }
}

#ifndef NFS_NOSERVER

/*
 * Parse an RPC request
 * - verify it
 * - fill in the cred struct.
 */
int
nfs_getreq(struct nfsrv_descript *nd, struct nfsd *nfsd, int has_header)
{
        int len, i;
        u_int32_t *tl;
        struct uio uio;
        struct iovec iov;
        caddr_t cp;
        u_int32_t nfsvers, auth_type;
        uid_t nickuid;
        int error = 0, ticklen;
        struct nfsuid *nuidp;
        struct timeval tvin, tvout;
        struct nfsm_info info;
#if 0                           /* until encrypted keys are implemented */
        NFSKERBKEYSCHED_T keys; /* stores key schedule */
#endif

        info.mrep = nd->nd_mrep;
        info.md = nd->nd_md;
        info.dpos = nd->nd_dpos;

        if (has_header) {
                NULLOUT(tl = nfsm_dissect(&info, 10 * NFSX_UNSIGNED));
                nd->nd_retxid = fxdr_unsigned(u_int32_t, *tl++);
                if (*tl++ != rpc_call) {
                        m_freem(info.mrep);
                        return (EBADRPC);
                }
        } else {
                NULLOUT(tl = nfsm_dissect(&info, 8 * NFSX_UNSIGNED));
        }
        nd->nd_repstat = 0;
        nd->nd_flag = 0;
        if (*tl++ != rpc_vers) {
                nd->nd_repstat = ERPCMISMATCH;
                nd->nd_procnum = NFSPROC_NOOP;
                return (0);
        }
        if (*tl != nfs_prog) {
                nd->nd_repstat = EPROGUNAVAIL;
                nd->nd_procnum = NFSPROC_NOOP;
                return (0);
        }
        tl++;
        nfsvers = fxdr_unsigned(u_int32_t, *tl++);
        if (nfsvers < NFS_VER2 || nfsvers > NFS_VER3) {
                nd->nd_repstat = EPROGMISMATCH;
                nd->nd_procnum = NFSPROC_NOOP;
                return (0);
        }
        if (nfsvers == NFS_VER3)
                nd->nd_flag = ND_NFSV3;
        nd->nd_procnum = fxdr_unsigned(u_int32_t, *tl++);
        if (nd->nd_procnum == NFSPROC_NULL)
                return (0);
        if (nd->nd_procnum >= NFS_NPROCS ||
                (nd->nd_procnum >= NQNFSPROC_GETLEASE) ||
                (!nd->nd_flag && nd->nd_procnum > NFSV2PROC_STATFS)) {
                nd->nd_repstat = EPROCUNAVAIL;
                nd->nd_procnum = NFSPROC_NOOP;
                return (0);
        }
        if ((nd->nd_flag & ND_NFSV3) == 0)
                nd->nd_procnum = nfsv3_procid[nd->nd_procnum];
        auth_type = *tl++;
        len = fxdr_unsigned(int, *tl++);
        if (len < 0 || len > RPCAUTH_MAXSIZ) {
                m_freem(info.mrep);
                return (EBADRPC);
        }

        nd->nd_flag &= ~ND_KERBAUTH;
        /*
         * Handle auth_unix or auth_kerb.
         */
        if (auth_type == rpc_auth_unix) {
                len = fxdr_unsigned(int, *++tl);
                if (len < 0 || len > NFS_MAXNAMLEN) {
                        m_freem(info.mrep);
                        return (EBADRPC);
                }
                ERROROUT(nfsm_adv(&info, nfsm_rndup(len)));
                NULLOUT(tl = nfsm_dissect(&info, 3 * NFSX_UNSIGNED));
                bzero((caddr_t)&nd->nd_cr, sizeof (struct ucred));
                nd->nd_cr.cr_ref = 1;
                nd->nd_cr.cr_uid = fxdr_unsigned(uid_t, *tl++);
                nd->nd_cr.cr_ruid = nd->nd_cr.cr_svuid = nd->nd_cr.cr_uid;
                nd->nd_cr.cr_gid = fxdr_unsigned(gid_t, *tl++);
                nd->nd_cr.cr_rgid = nd->nd_cr.cr_svgid = nd->nd_cr.cr_gid;
                len = fxdr_unsigned(int, *tl);
                if (len < 0 || len > RPCAUTH_UNIXGIDS) {
                        m_freem(info.mrep);
                        return (EBADRPC);
                }
                NULLOUT(tl = nfsm_dissect(&info, (len + 2) * NFSX_UNSIGNED));
                for (i = 1; i <= len; i++)
                    if (i < NGROUPS)
                        nd->nd_cr.cr_groups[i] = fxdr_unsigned(gid_t, *tl++);
                    else
                        tl++;
                nd->nd_cr.cr_ngroups = (len >= NGROUPS) ? NGROUPS : (len + 1);
                if (nd->nd_cr.cr_ngroups > 1)
                    nfsrvw_sort(nd->nd_cr.cr_groups, nd->nd_cr.cr_ngroups);
                len = fxdr_unsigned(int, *++tl);
                if (len < 0 || len > RPCAUTH_MAXSIZ) {
                        m_freem(info.mrep);
                        return (EBADRPC);
                }
                if (len > 0) {
                        ERROROUT(nfsm_adv(&info, nfsm_rndup(len)));
                }
        } else if (auth_type == rpc_auth_kerb) {
                switch (fxdr_unsigned(int, *tl++)) {
                case RPCAKN_FULLNAME:
                        ticklen = fxdr_unsigned(int, *tl);
                        *((u_int32_t *)nfsd->nfsd_authstr) = *tl;
                        uio.uio_resid = nfsm_rndup(ticklen) + NFSX_UNSIGNED;
                        nfsd->nfsd_authlen = uio.uio_resid + NFSX_UNSIGNED;
                        if (uio.uio_resid > (len - 2 * NFSX_UNSIGNED)) {
                                m_freem(info.mrep);
                                return (EBADRPC);
                        }
                        uio.uio_offset = 0;
                        uio.uio_iov = &iov;
                        uio.uio_iovcnt = 1;
                        uio.uio_segflg = UIO_SYSSPACE;
                        iov.iov_base = (caddr_t)&nfsd->nfsd_authstr[4];
                        iov.iov_len = RPCAUTH_MAXSIZ - 4;
                        ERROROUT(nfsm_mtouio(&info, &uio, uio.uio_resid));
                        NULLOUT(tl = nfsm_dissect(&info, 2 * NFSX_UNSIGNED));
                        if (*tl++ != rpc_auth_kerb ||
                                fxdr_unsigned(int, *tl) != 4 * NFSX_UNSIGNED) {
                                kprintf("Bad kerb verifier\n");
                                nd->nd_repstat = (NFSERR_AUTHERR|AUTH_BADVERF);
                                nd->nd_procnum = NFSPROC_NOOP;
                                return (0);
                        }
                        NULLOUT(cp = nfsm_dissect(&info, 4 * NFSX_UNSIGNED));
                        tl = (u_int32_t *)cp;
                        if (fxdr_unsigned(int, *tl) != RPCAKN_FULLNAME) {
                                kprintf("Not fullname kerb verifier\n");
                                nd->nd_repstat = (NFSERR_AUTHERR|AUTH_BADVERF);
                                nd->nd_procnum = NFSPROC_NOOP;
                                return (0);
                        }
                        cp += NFSX_UNSIGNED;
                        bcopy(cp, nfsd->nfsd_verfstr, 3 * NFSX_UNSIGNED);
                        nfsd->nfsd_verflen = 3 * NFSX_UNSIGNED;
                        nd->nd_flag |= ND_KERBFULL;
                        nfsd->nfsd_flag |= NFSD_NEEDAUTH;
                        break;
                case RPCAKN_NICKNAME:
                        if (len != 2 * NFSX_UNSIGNED) {
                                kprintf("Kerb nickname short\n");
                                nd->nd_repstat = (NFSERR_AUTHERR|AUTH_BADCRED);
                                nd->nd_procnum = NFSPROC_NOOP;
                                return (0);
                        }
                        nickuid = fxdr_unsigned(uid_t, *tl);
                        NULLOUT(tl = nfsm_dissect(&info, 2 * NFSX_UNSIGNED));
                        if (*tl++ != rpc_auth_kerb ||
                                fxdr_unsigned(int, *tl) != 3 * NFSX_UNSIGNED) {
                                kprintf("Kerb nick verifier bad\n");
                                nd->nd_repstat = (NFSERR_AUTHERR|AUTH_BADVERF);
                                nd->nd_procnum = NFSPROC_NOOP;
                                return (0);
                        }
                        NULLOUT(tl = nfsm_dissect(&info, 3 * NFSX_UNSIGNED));
                        tvin.tv_sec = *tl++;
                        tvin.tv_usec = *tl;

                        for (nuidp = NUIDHASH(nfsd->nfsd_slp,nickuid)->lh_first;
                            nuidp != NULL; nuidp = nuidp->nu_hash.le_next) {
                                if (nuidp->nu_cr.cr_uid == nickuid &&
                                    (!nd->nd_nam2 ||
                                     netaddr_match(AF_INET,
                                      &nuidp->nu_haddr, nd->nd_nam2)))
                                        break;
                        }
                        if (!nuidp) {
                                nd->nd_repstat =
                                        (NFSERR_AUTHERR|AUTH_REJECTCRED);
                                nd->nd_procnum = NFSPROC_NOOP;
                                return (0);
                        }

                        /*
                         * Now, decrypt the timestamp using the session key
                         * and validate it.
                         */
#ifdef NFSKERB
                        XXX
#else
                        tvout.tv_sec = 0;
                        tvout.tv_usec = 0;
#endif

                        tvout.tv_sec = fxdr_unsigned(long, tvout.tv_sec);
                        tvout.tv_usec = fxdr_unsigned(long, tvout.tv_usec);
                        if (nuidp->nu_expire != time_uptime ||
                            nuidp->nu_timestamp.tv_sec > tvout.tv_sec ||
                            (nuidp->nu_timestamp.tv_sec == tvout.tv_sec &&
                             nuidp->nu_timestamp.tv_usec > tvout.tv_usec)) {
                                nuidp->nu_expire = 0;
                                nd->nd_repstat =
                                    (NFSERR_AUTHERR|AUTH_REJECTVERF);
                                nd->nd_procnum = NFSPROC_NOOP;
                                return (0);
                        }
                        nfsrv_setcred(&nuidp->nu_cr, &nd->nd_cr);
                        nd->nd_flag |= ND_KERBNICK;
                        break;
                }
        } else {
                nd->nd_repstat = (NFSERR_AUTHERR | AUTH_REJECTCRED);
                nd->nd_procnum = NFSPROC_NOOP;
                return (0);
        }

        nd->nd_md = info.md;
        nd->nd_dpos = info.dpos;
        return (0);
nfsmout:
        return (error);
}

#endif

/*
 * Send a message to the originating process's terminal.  The thread and/or
 * process may be NULL.  YYY the thread should not be NULL but there may
 * still be some uio_td's that are still being passed as NULL through to
 * nfsm_request().
 */
static int
nfs_msg(struct thread *td, char *server, char *msg)
{
        tpr_t tpr;

        if (td && td->td_proc)
                tpr = tprintf_open(td->td_proc);
        else
                tpr = NULL;
        tprintf(tpr, "nfs server %s: %s\n", server, msg);
        tprintf_close(tpr);
        return (0);
}

#ifndef NFS_NOSERVER

/*
 * Socket upcall routine for nfsd sockets.  This runs in the protocol
 * thread and passes waitflag == M_NOWAIT.
 */
void
nfsrv_rcv_upcall(struct socket *so, void *arg, int waitflag)
{
        struct nfssvc_sock *slp = (struct nfssvc_sock *)arg;

        if (slp->ns_needq_upcall == 0) {
                slp->ns_needq_upcall = 1;       /* ok to race */
                lwkt_gettoken(&nfs_token);
                nfsrv_wakenfsd(slp, 1);
                lwkt_reltoken(&nfs_token);
        }
#if 0
        lwkt_gettoken(&slp->ns_token);
        slp->ns_flag |= SLP_NEEDQ;
        nfsrv_rcv(so, arg, waitflag);
        lwkt_reltoken(&slp->ns_token);
#endif
}

/*
 * Process new data on a receive socket.  Essentially do as much as we can
 * non-blocking, else punt and it will be called with M_WAITOK from an nfsd.
 *
 * slp->ns_token is held on call
 */
void
nfsrv_rcv(struct socket *so, void *arg, int waitflag)
{
        struct nfssvc_sock *slp = (struct nfssvc_sock *)arg;
        struct mbuf *m;
        struct sockaddr *nam;
        struct sockbuf sio;
        int flags, error;
        int nparallel_wakeup = 0;

        ASSERT_LWKT_TOKEN_HELD(&slp->ns_token);

        if ((slp->ns_flag & SLP_VALID) == 0)
                return;

        /*
         * Do not allow an infinite number of completed RPC records to build
         * up before we stop reading data from the socket.  Otherwise we could
         * end up holding onto an unreasonable number of mbufs for requests
         * waiting for service.
         *
         * This should give pretty good feedback to the TCP layer and
         * prevents a memory crunch for other protocols.
         *
         * Note that the same service socket can be dispatched to several
         * nfs servers simultaniously.  The tcp protocol callback calls us
         * with M_NOWAIT.  nfsd calls us with M_WAITOK (typically).
         */
        if (NFSRV_RECLIMIT(slp))
                return;

        /*
         * Handle protocol specifics to parse an RPC request.  We always
         * pull from the socket using non-blocking I/O.
         */
        if (so->so_type == SOCK_STREAM) {
                /*
                 * The data has to be read in an orderly fashion from a TCP
                 * stream, unlike a UDP socket.  It is possible for soreceive
                 * and/or nfsrv_getstream() to block, so make sure only one
                 * entity is messing around with the TCP stream at any given
                 * moment.  The receive sockbuf's lock in soreceive is not
                 * sufficient.
                 */
                if (slp->ns_flag & SLP_GETSTREAM)
                        return;
                slp->ns_flag |= SLP_GETSTREAM;

                /*
                 * Do soreceive().  Pull out as much data as possible without
                 * blocking.
                 */
                sbinit(&sio, 1000000000);
                flags = MSG_DONTWAIT;
                error = so_pru_soreceive(so, NULL, NULL, &sio, NULL, &flags);
                if (error || sio.sb_mb == NULL) {
                        if (error != EWOULDBLOCK)
                                slp->ns_flag |= SLP_DISCONN;
                        slp->ns_flag &= ~(SLP_GETSTREAM | SLP_NEEDQ);
                        goto done;
                }
                m = sio.sb_mb;
                if (slp->ns_rawend) {
                        slp->ns_rawend->m_next = m;
                        slp->ns_cc += sio.sb_cc;
                } else {
                        slp->ns_raw = m;
                        slp->ns_cc = sio.sb_cc;
                }
                while (m->m_next)
                        m = m->m_next;
                slp->ns_rawend = m;

                /*
                 * Now try and parse as many record(s) as we can out of the
                 * raw stream data.  This will set SLP_DOREC.
                 */
                error = nfsrv_getstream(slp, waitflag, &nparallel_wakeup);
                if (error && error != EWOULDBLOCK)
                        slp->ns_flag |= SLP_DISCONN;
                slp->ns_flag &= ~SLP_GETSTREAM;
        } else {
                /*
                 * For UDP soreceive typically pulls just one packet, loop
                 * to get the whole batch.
                 */
                do {
                        sbinit(&sio, 1000000000);
                        flags = MSG_DONTWAIT;
                        error = so_pru_soreceive(so, &nam, NULL, &sio,
                                                 NULL, &flags);
                        if (sio.sb_mb) {
                                struct nfsrv_rec *rec;
                                int mf = (waitflag & M_NOWAIT) ?
                                            M_NOWAIT : M_WAITOK;
                                rec = kmalloc(sizeof(struct nfsrv_rec),
                                             M_NFSRVDESC, mf);
                                if (!rec) {
                                        if (nam)
                                                kfree(nam, M_SONAME);
                                        m_freem(sio.sb_mb);
                                        continue;
                                }
                                nfs_realign(&sio.sb_mb, 10 * NFSX_UNSIGNED);
                                rec->nr_address = nam;
                                rec->nr_packet = sio.sb_mb;
                                STAILQ_INSERT_TAIL(&slp->ns_rec, rec, nr_link);
                                ++slp->ns_numrec;
                                slp->ns_flag |= SLP_DOREC;
                                ++nparallel_wakeup;
                        } else {
                                slp->ns_flag &= ~SLP_NEEDQ;
                        }
                        if (error) {
                                if ((so->so_proto->pr_flags & PR_CONNREQUIRED)
                                    && error != EWOULDBLOCK) {
                                        slp->ns_flag |= SLP_DISCONN;
                                        break;
                                }
                        }
                        if (NFSRV_RECLIMIT(slp))
                                break;
                } while (sio.sb_mb);
        }

        /*
         * If we were upcalled from the tcp protocol layer and we have
         * fully parsed records ready to go, or there is new data pending,
         * or something went wrong, try to wake up a nfsd thread to deal
         * with it.
         */
done:
        /* XXX this code is currently not executed (nfsrv_rcv_upcall) */
        if (waitflag == M_NOWAIT && (slp->ns_flag & SLP_ACTION_MASK)) {
                lwkt_gettoken(&nfs_token);
                nfsrv_wakenfsd(slp, nparallel_wakeup);
                lwkt_reltoken(&nfs_token);
        }
}

/*
 * Try and extract an RPC request from the mbuf data list received on a
 * stream socket. The "waitflag" argument indicates whether or not it
 * can sleep.
 */
static int
nfsrv_getstream(struct nfssvc_sock *slp, int waitflag, int *countp)
{
        struct mbuf *m, **mpp;
        char *cp1, *cp2;
        int len;
        struct mbuf *om, *m2, *recm;
        u_int32_t recmark;

        for (;;) {
            if (slp->ns_reclen == 0) {
                if (slp->ns_cc < NFSX_UNSIGNED)
                        return (0);
                m = slp->ns_raw;
                if (m->m_len >= NFSX_UNSIGNED) {
                        bcopy(mtod(m, caddr_t), (caddr_t)&recmark, NFSX_UNSIGNED);
                        m->m_data += NFSX_UNSIGNED;
                        m->m_len -= NFSX_UNSIGNED;
                } else {
                        cp1 = (caddr_t)&recmark;
                        cp2 = mtod(m, caddr_t);
                        while (cp1 < ((caddr_t)&recmark) + NFSX_UNSIGNED) {
                                while (m->m_len == 0) {
                                        m = m->m_next;
                                        cp2 = mtod(m, caddr_t);
                                }
                                *cp1++ = *cp2++;
                                m->m_data++;
                                m->m_len--;
                        }
                }
                slp->ns_cc -= NFSX_UNSIGNED;
                recmark = ntohl(recmark);
                slp->ns_reclen = recmark & ~0x80000000;
                if (recmark & 0x80000000)
                        slp->ns_flag |= SLP_LASTFRAG;
                else
                        slp->ns_flag &= ~SLP_LASTFRAG;
                if (slp->ns_reclen > NFS_MAXPACKET || slp->ns_reclen <= 0) {
                        log(LOG_ERR, "%s (%d) from nfs client\n",
                            "impossible packet length",
                            slp->ns_reclen);
                        return (EPERM);
                }
            }

            /*
             * Now get the record part.
             *
             * Note that slp->ns_reclen may be 0.  Linux sometimes
             * generates 0-length RPCs
             */
            recm = NULL;
            if (slp->ns_cc == slp->ns_reclen) {
                recm = slp->ns_raw;
                slp->ns_raw = slp->ns_rawend = NULL;
                slp->ns_cc = slp->ns_reclen = 0;
            } else if (slp->ns_cc > slp->ns_reclen) {
                len = 0;
                m = slp->ns_raw;
                om = NULL;

                while (len < slp->ns_reclen) {
                        if ((len + m->m_len) > slp->ns_reclen) {
                                m2 = m_copym(m, 0, slp->ns_reclen - len,
                                        waitflag);
                                if (m2) {
                                        if (om) {
                                                om->m_next = m2;
                                                recm = slp->ns_raw;
                                        } else
                                                recm = m2;
                                        m->m_data += slp->ns_reclen - len;
                                        m->m_len -= slp->ns_reclen - len;
                                        len = slp->ns_reclen;
                                } else {
                                        return (EWOULDBLOCK);
                                }
                        } else if ((len + m->m_len) == slp->ns_reclen) {
                                om = m;
                                len += m->m_len;
                                m = m->m_next;
                                recm = slp->ns_raw;
                                om->m_next = NULL;
                        } else {
                                om = m;
                                len += m->m_len;
                                m = m->m_next;
                        }
                }
                slp->ns_raw = m;
                slp->ns_cc -= len;
                slp->ns_reclen = 0;
            } else {
                return (0);
            }

            /*
             * Accumulate the fragments into a record.
             */
            mpp = &slp->ns_frag;
            while (*mpp)
                mpp = &((*mpp)->m_next);
            *mpp = recm;
            if (slp->ns_flag & SLP_LASTFRAG) {
                struct nfsrv_rec *rec;
                int mf = (waitflag & M_NOWAIT) ? M_NOWAIT : M_WAITOK;
                rec = kmalloc(sizeof(struct nfsrv_rec), M_NFSRVDESC, mf);
                if (!rec) {
                    m_freem(slp->ns_frag);
                } else {
                    nfs_realign(&slp->ns_frag, 10 * NFSX_UNSIGNED);
                    rec->nr_address = NULL;
                    rec->nr_packet = slp->ns_frag;
                    STAILQ_INSERT_TAIL(&slp->ns_rec, rec, nr_link);
                    ++slp->ns_numrec;
                    slp->ns_flag |= SLP_DOREC;
                    ++*countp;
                }
                slp->ns_frag = NULL;
            }
        }
}

#ifdef INVARIANTS

/*
 * Sanity check our mbuf chain.
 */
static void
nfs_checkpkt(struct mbuf *m, int len)
{
        int xlen = 0;
        while (m) {
                xlen += m->m_len;
                m = m->m_next;
        }
        if (xlen != len) {
                panic("nfs_checkpkt: len mismatch %d/%d mbuf %p",
                        xlen, len, m);
        }
}

#else

static void
nfs_checkpkt(struct mbuf *m __unused, int len __unused)
{
}

#endif

/*
 * Parse an RPC header.
 *
 * If the socket is invalid or no records are pending we return ENOBUFS.
 * The caller must deal with NEEDQ races.
 */
int
nfsrv_dorec(struct nfssvc_sock *slp, struct nfsd *nfsd,
            struct nfsrv_descript **ndp)
{
        struct nfsrv_rec *rec;
        struct mbuf *m;
        struct sockaddr *nam;
        struct nfsrv_descript *nd;
        int error;

        *ndp = NULL;
        if ((slp->ns_flag & SLP_VALID) == 0 || !STAILQ_FIRST(&slp->ns_rec))
                return (ENOBUFS);
        rec = STAILQ_FIRST(&slp->ns_rec);
        STAILQ_REMOVE_HEAD(&slp->ns_rec, nr_link);
        KKASSERT(slp->ns_numrec > 0);
        if (--slp->ns_numrec == 0)
                slp->ns_flag &= ~SLP_DOREC;
        nam = rec->nr_address;
        m = rec->nr_packet;
        kfree(rec, M_NFSRVDESC);
        nd = kmalloc(sizeof(struct nfsrv_descript), M_NFSRVDESC, M_WAITOK);
        nd->nd_md = nd->nd_mrep = m;
        nd->nd_nam2 = nam;
        nd->nd_dpos = mtod(m, caddr_t);
        error = nfs_getreq(nd, nfsd, TRUE);
        if (error) {
                if (nam) {
                        kfree(nam, M_SONAME);
                }
                kfree((caddr_t)nd, M_NFSRVDESC);
                return (error);
        }
        *ndp = nd;
        nfsd->nfsd_nd = nd;
        return (0);
}

/*
 * Try to assign service sockets to nfsd threads based on the number
 * of new rpc requests that have been queued on the service socket.
 *
 * If no nfsd's are available or additonal requests are pending, set the
 * NFSD_CHECKSLP flag so that one of the running nfsds will go look for
 * the work in the nfssvc_sock list when it is finished processing its
 * current work.  This flag is only cleared when an nfsd can not find
 * any new work to perform.
 */
void
nfsrv_wakenfsd(struct nfssvc_sock *slp, int nparallel)
{
        struct nfsd *nd;

        if ((slp->ns_flag & SLP_VALID) == 0)
                return;
        if (nparallel <= 1)
                nparallel = 1;
        TAILQ_FOREACH(nd, &nfsd_head, nfsd_chain) {
                if (nd->nfsd_flag & NFSD_WAITING) {
                        nd->nfsd_flag &= ~NFSD_WAITING;
                        if (nd->nfsd_slp)
                                panic("nfsd wakeup");
                        nfsrv_slpref(slp);
                        nd->nfsd_slp = slp;
                        wakeup((caddr_t)nd);
                        if (--nparallel == 0)
                                break;
                }
        }

        /*
         * If we couldn't assign slp then the NFSDs are all busy and
         * we set a flag indicating that there is pending work.
         */
        if (nparallel)
                nfsd_head_flag |= NFSD_CHECKSLP;
}
#endif /* NFS_NOSERVER */