/*      $NetBSD: nfs_vfsops.c,v 1.246 2024/05/13 00:11:22 msaitoh Exp $ */

/*
 * Copyright (c) 1989, 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_vfsops.c        8.12 (Berkeley) 5/20/95
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: nfs_vfsops.c,v 1.246 2024/05/13 00:11:22 msaitoh Exp $");

#if defined(_KERNEL_OPT)
#include "opt_nfs.h"
#endif

#include <sys/param.h>
#include <sys/ioctl.h>
#include <sys/signal.h>
#include <sys/proc.h>
#include <sys/namei.h>
#include <sys/device.h>
#include <sys/vnode.h>
#include <sys/kernel.h>
#include <sys/mount.h>
#include <sys/buf.h>
#include <sys/mbuf.h>
#include <sys/dirent.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
#include <sys/timetc.h>
#include <sys/kauth.h>
#include <sys/module.h>

#include <net/if.h>
#include <net/route.h>
#include <netinet/in.h>

#include <nfs/rpcv2.h>
#include <nfs/nfsproto.h>
#include <nfs/nfsnode.h>
#include <nfs/nfs.h>
#include <nfs/nfsmount.h>
#include <nfs/xdr_subs.h>
#include <nfs/nfsm_subs.h>
#include <nfs/nfsdiskless.h>
#include <nfs/nfs_var.h>

MODULE(MODULE_CLASS_VFS, nfs, NULL);

extern struct nfsstats nfsstats;
extern int nfs_ticks;

/*
 * keep a count of the nfs mounts to generate fictitious drive names
 * for the per drive stats.
 */
unsigned int nfs_mount_count = 0;

int nfs_commitsize;

/*
 * nfs vfs operations.
 */

extern const struct vnodeopv_desc nfsv2_vnodeop_opv_desc;
extern const struct vnodeopv_desc spec_nfsv2nodeop_opv_desc;
extern const struct vnodeopv_desc fifo_nfsv2nodeop_opv_desc;

const struct vnodeopv_desc * const nfs_vnodeopv_descs[] = {
        &nfsv2_vnodeop_opv_desc,
        &spec_nfsv2nodeop_opv_desc,
        &fifo_nfsv2nodeop_opv_desc,
        NULL,
};

struct vfsops nfs_vfsops = {
        .vfs_name = MOUNT_NFS,
        .vfs_min_mount_data = sizeof (struct nfs_args),
        .vfs_mount = nfs_mount,
        .vfs_start = nfs_start,
        .vfs_unmount = nfs_unmount,
        .vfs_root = nfs_root,
        .vfs_quotactl = (void *)eopnotsupp,
        .vfs_statvfs = nfs_statvfs,
        .vfs_sync = nfs_sync,
        .vfs_loadvnode = nfs_loadvnode,
        .vfs_vget = nfs_vget,
        .vfs_fhtovp = nfs_fhtovp,
        .vfs_vptofh = nfs_vptofh,
        .vfs_init = nfs_vfs_init,
        .vfs_done = nfs_vfs_done,
        .vfs_mountroot = nfs_mountroot,
        .vfs_snapshot = (void *)eopnotsupp,
        .vfs_extattrctl = vfs_stdextattrctl,
        .vfs_suspendctl = genfs_suspendctl,
        .vfs_renamelock_enter = genfs_renamelock_enter,
        .vfs_renamelock_exit = genfs_renamelock_exit,
        .vfs_fsync = (void *)eopnotsupp,
        .vfs_opv_descs = nfs_vnodeopv_descs
};

extern u_int32_t nfs_procids[NFS_NPROCS];
extern u_int32_t nfs_prog, nfs_vers;

static int nfs_mount_diskless(struct nfs_dlmount *, const char *,
    struct mount **, struct vnode **, struct lwp *);

static int
nfs_modcmd(modcmd_t cmd, void *arg)
{
        int error;

        switch (cmd) {
        case MODULE_CMD_INIT:
                error = vfs_attach(&nfs_vfsops);
                return error;
        case MODULE_CMD_FINI:
                error = vfs_detach(&nfs_vfsops);
                return error;
        default:
                return ENOTTY;
        }
}

/*
 * nfs statvfs call
 */
int
nfs_statvfs(struct mount *mp, struct statvfs *sbp)
{
        struct lwp *l = curlwp;
        struct vnode *vp;
        struct nfs_statfs *sfp;
        char *cp;
        u_int32_t *tl;
        int32_t t1, t2;
        char *bpos, *dpos, *cp2;
        struct nfsmount *nmp = VFSTONFS(mp);
        int error = 0, retattr;
#ifdef NFS_V2_ONLY
        const int v3 = 0;
#else
        int v3 = (nmp->nm_flag & NFSMNT_NFSV3);
#endif
        struct mbuf *mreq, *mrep = NULL, *md, *mb;
        kauth_cred_t cred;
        u_quad_t tquad;
        struct nfsnode *np;

#ifndef nolint
        sfp = (struct nfs_statfs *)0;
#endif
        vp = nmp->nm_vnode;
        np = VTONFS(vp);
        cred = kauth_cred_alloc();
#ifndef NFS_V2_ONLY
        if (v3 && (nmp->nm_iflag & NFSMNT_GOTFSINFO) == 0)
                (void)nfs_fsinfo(nmp, vp, cred, l);
#endif
        nfsstats.rpccnt[NFSPROC_FSSTAT]++;
        nfsm_reqhead(np, NFSPROC_FSSTAT, NFSX_FH(v3));
        nfsm_fhtom(np, v3);
        nfsm_request(np, NFSPROC_FSSTAT, l, cred);
        if (v3)
                nfsm_postop_attr(vp, retattr, 0);
        if (error) {
                if (mrep != NULL) {
                        if (mrep->m_next != NULL)
                                printf("nfs_vfsops: nfs_statvfs would lose buffers\n");
                        m_freem(mrep);
                }
                goto nfsmout;
        }
        nfsm_dissect(sfp, struct nfs_statfs *, NFSX_STATFS(v3));
        sbp->f_flag = nmp->nm_flag;
        sbp->f_iosize = uimin(nmp->nm_rsize, nmp->nm_wsize);
        if (v3) {
                sbp->f_frsize = sbp->f_bsize = NFS_FABLKSIZE;
                tquad = fxdr_hyper(&sfp->sf_tbytes);
                sbp->f_blocks = ((quad_t)tquad / (quad_t)NFS_FABLKSIZE);
                tquad = fxdr_hyper(&sfp->sf_fbytes);
                sbp->f_bfree = ((quad_t)tquad / (quad_t)NFS_FABLKSIZE);
                tquad = fxdr_hyper(&sfp->sf_abytes);
                tquad = ((quad_t)tquad / (quad_t)NFS_FABLKSIZE);
                sbp->f_bresvd = sbp->f_bfree - tquad;
                sbp->f_bavail = tquad;
                /* Handle older NFS servers returning negative values */
                if ((quad_t)sbp->f_bavail < 0)
                        sbp->f_bavail = 0;
                tquad = fxdr_hyper(&sfp->sf_tfiles);
                sbp->f_files = tquad;
                tquad = fxdr_hyper(&sfp->sf_ffiles);
                sbp->f_ffree = tquad;
                sbp->f_favail = tquad;
                sbp->f_fresvd = 0;
        } else {
                sbp->f_bsize = NFS_FABLKSIZE;
                sbp->f_frsize = fxdr_unsigned(int32_t, sfp->sf_bsize);
                sbp->f_blocks = fxdr_unsigned(int32_t, sfp->sf_blocks);
                sbp->f_bfree = fxdr_unsigned(int32_t, sfp->sf_bfree);
                sbp->f_bavail = fxdr_unsigned(int32_t, sfp->sf_bavail);
                sbp->f_fresvd = 0;
                sbp->f_files = 0;
                sbp->f_ffree = 0;
                sbp->f_favail = 0;
                sbp->f_fresvd = 0;
        }
        copy_statvfs_info(sbp, mp);
        nfsm_reqdone;
        kauth_cred_free(cred);
        return (error);
}

#ifndef NFS_V2_ONLY
/*
 * nfs version 3 fsinfo rpc call
 */
int
nfs_fsinfo(struct nfsmount *nmp, struct vnode *vp, kauth_cred_t cred, struct lwp *l)
{
        struct nfsv3_fsinfo *fsp;
        char *cp;
        int32_t t1, t2;
        u_int32_t *tl, pref, xmax;
        char *bpos, *dpos, *cp2;
        int error = 0, retattr;
        struct mbuf *mreq, *mrep, *md, *mb;
        u_int64_t maxfsize;
        struct nfsnode *np = VTONFS(vp);

        nfsstats.rpccnt[NFSPROC_FSINFO]++;
        nfsm_reqhead(np, NFSPROC_FSINFO, NFSX_FH(1));
        nfsm_fhtom(np, 1);
        nfsm_request(np, NFSPROC_FSINFO, l, cred);
        nfsm_postop_attr(vp, retattr, 0);
        if (!error) {
                nfsm_dissect(fsp, struct nfsv3_fsinfo *, NFSX_V3FSINFO);
                pref = fxdr_unsigned(u_int32_t, fsp->fs_wtpref);
                if ((nmp->nm_flag & NFSMNT_WSIZE) == 0 &&
                    pref < nmp->nm_wsize && pref >= NFS_FABLKSIZE)
                        nmp->nm_wsize = (pref + NFS_FABLKSIZE - 1) &
                                ~(NFS_FABLKSIZE - 1);
                xmax = fxdr_unsigned(u_int32_t, fsp->fs_wtmax);
                if (xmax < nmp->nm_wsize && xmax > 0) {
                        nmp->nm_wsize = xmax & ~(NFS_FABLKSIZE - 1);
                        if (nmp->nm_wsize == 0)
                                nmp->nm_wsize = xmax;
                }
                pref = fxdr_unsigned(u_int32_t, fsp->fs_rtpref);
                if ((nmp->nm_flag & NFSMNT_RSIZE) == 0 &&
                    pref < nmp->nm_rsize && pref >= NFS_FABLKSIZE)
                        nmp->nm_rsize = (pref + NFS_FABLKSIZE - 1) &
                                ~(NFS_FABLKSIZE - 1);
                xmax = fxdr_unsigned(u_int32_t, fsp->fs_rtmax);
                if (xmax < nmp->nm_rsize && xmax > 0) {
                        nmp->nm_rsize = xmax & ~(NFS_FABLKSIZE - 1);
                        if (nmp->nm_rsize == 0)
                                nmp->nm_rsize = xmax;
                }
                pref = fxdr_unsigned(u_int32_t, fsp->fs_dtpref);
                if (pref < nmp->nm_readdirsize && pref >= NFS_DIRFRAGSIZ)
                        nmp->nm_readdirsize = (pref + NFS_DIRFRAGSIZ - 1) &
                                ~(NFS_DIRFRAGSIZ - 1);
                if (xmax < nmp->nm_readdirsize && xmax > 0) {
                        nmp->nm_readdirsize = xmax & ~(NFS_DIRFRAGSIZ - 1);
                        if (nmp->nm_readdirsize == 0)
                                nmp->nm_readdirsize = xmax;
                }
                nmp->nm_maxfilesize = 0xffffffffffffffffull;
                maxfsize = fxdr_hyper(&fsp->fs_maxfilesize);
                if (maxfsize > 0 && maxfsize < nmp->nm_maxfilesize)
                        nmp->nm_maxfilesize = maxfsize;
                nmp->nm_mountp->mnt_fs_bshift =
                    ffs(MIN(nmp->nm_rsize, nmp->nm_wsize)) - 1;
                nmp->nm_iflag |= NFSMNT_GOTFSINFO;
        }
        nfsm_reqdone;
        return (error);
}
#endif

/*
 * Mount a remote root fs via. NFS.  It goes like this:
 * - Call nfs_boot_init() to fill in the nfs_diskless struct
 * - build the rootfs mount point and call mountnfs() to do the rest.
 */
int
nfs_mountroot(void)
{
        struct timespec ts;
        struct nfs_diskless *nd;
        struct vattr attr;
        struct mount *mp;
        struct vnode *vp;
        struct lwp *l;
        time_t n;
        int error;

        l = curlwp; /* XXX */

        if (device_class(root_device) != DV_IFNET)
                return (ENODEV);

        /*
         * XXX time must be non-zero when we init the interface or else
         * the arp code will wedge.  [Fixed now in if_ether.c]
         * However, the NFS attribute cache gives false "hits" when the
         * current time < nfs_attrtimeo(nmp, np) so keep this in for now.
         */
        if (time_second < NFS_MAXATTRTIMO) {
                ts.tv_sec = NFS_MAXATTRTIMO;
                ts.tv_nsec = 0;
                tc_setclock(&ts);
        }

        /*
         * Call nfs_boot_init() to fill in the nfs_diskless struct.
         * Side effect:  Finds and configures a network interface.
         */
        nd = kmem_zalloc(sizeof(*nd), KM_SLEEP);
        error = nfs_boot_init(nd, l);
        if (error) {
                kmem_free(nd, sizeof(*nd));
                return (error);
        }

        /*
         * Create the root mount point.
         */
        error = nfs_mount_diskless(&nd->nd_root, "/", &mp, &vp, l);
        if (error)
                goto out;
        printf("root on %s\n", nd->nd_root.ndm_host);

        /*
         * Link it into the mount list.
         */
        mountlist_append(mp);
        rootvp = vp;
        mp->mnt_vnodecovered = NULLVP;
        vfs_unbusy(mp);

        /* Get root attributes (for the time). */
        vn_lock(vp, LK_SHARED | LK_RETRY);
        error = VOP_GETATTR(vp, &attr, l->l_cred);
        VOP_UNLOCK(vp);
        if (error)
                panic("nfs_mountroot: getattr for root");
        n = attr.va_atime.tv_sec;
#ifdef  DEBUG
        printf("root time: 0x%jx\n", (intmax_t)n);
#endif
        setrootfstime(n);

out:
        if (error)
                nfs_boot_cleanup(nd, l);
        kmem_free(nd, sizeof(*nd));
        return (error);
}

/*
 * Internal version of mount system call for diskless setup.
 * Separate function because we used to call it twice.
 * (once for root and once for swap)
 */
static int
nfs_mount_diskless(struct nfs_dlmount *ndmntp, const char *mntname, struct mount **mpp, struct vnode **vpp, struct lwp *l)
        /* mntname:      mount point name */
{
        struct mount *mp;
        struct mbuf *m;
        int error;

        vfs_rootmountalloc(MOUNT_NFS, mntname, &mp);

        mp->mnt_op = &nfs_vfsops;

        /*
         * Historical practice expects NFS root file systems to
         * be initially mounted r/w.
         */
        mp->mnt_flag &= ~MNT_RDONLY;

        /* Get mbuf for server sockaddr. */
        m = m_get(M_WAIT, MT_SONAME);
        if (m == NULL)
                panic("nfs_mountroot: mget soname for %s", mntname);
        MCLAIM(m, &nfs_mowner);
        memcpy(mtod(m, void *), (void *)ndmntp->ndm_args.addr,
              (m->m_len = ndmntp->ndm_args.addr->sa_len));

        error = mountnfs(&ndmntp->ndm_args, mp, m, mntname,
                         ndmntp->ndm_args.hostname, vpp, l);
        if (error) {
                vfs_unbusy(mp);
                vfs_rele(mp);
                printf("nfs_mountroot: mount %s failed: %d\n",
                       mntname, error);
        } else
                *mpp = mp;

        return (error);
}

void
nfs_decode_args(struct nfsmount *nmp, struct nfs_args *argp, struct lwp *l)
{
        int s;
        int adjsock;
        int maxio;

        s = splsoftnet();

        /*
         * Silently clear NFSMNT_NOCONN if it's a TCP mount, it makes
         * no sense in that context.
         */
        if (argp->sotype == SOCK_STREAM)
                argp->flags &= ~NFSMNT_NOCONN;

        /*
         * Cookie translation is not needed for v2, silently ignore it.
         */
        if ((argp->flags & (NFSMNT_XLATECOOKIE|NFSMNT_NFSV3)) ==
            NFSMNT_XLATECOOKIE)
                argp->flags &= ~NFSMNT_XLATECOOKIE;

        /* Re-bind if rsrvd port requested and wasn't on one */
        adjsock = !(nmp->nm_flag & NFSMNT_RESVPORT)
                  && (argp->flags & NFSMNT_RESVPORT);
        /* Also re-bind if we're switching to/from a connected UDP socket */
        adjsock |= ((nmp->nm_flag & NFSMNT_NOCONN) !=
                    (argp->flags & NFSMNT_NOCONN));

        /* Update flags. */
        nmp->nm_flag = argp->flags;
        splx(s);

        if ((argp->flags & NFSMNT_TIMEO) && argp->timeo > 0) {
                nmp->nm_timeo = (argp->timeo * NFS_HZ + 5) / 10;
                if (nmp->nm_timeo < NFS_MINTIMEO)
                        nmp->nm_timeo = NFS_MINTIMEO;
                else if (nmp->nm_timeo > NFS_MAXTIMEO)
                        nmp->nm_timeo = NFS_MAXTIMEO;
        }

        if ((argp->flags & NFSMNT_RETRANS) && argp->retrans > 1) {
                nmp->nm_retry = argp->retrans;
                if (nmp->nm_retry > NFS_MAXREXMIT)
                        nmp->nm_retry = NFS_MAXREXMIT;
        }

#ifndef NFS_V2_ONLY
        if (argp->flags & NFSMNT_NFSV3) {
                if (argp->sotype == SOCK_DGRAM)
                        maxio = NFS_MAXDGRAMDATA;
                else
                        maxio = NFS_MAXDATA;
        } else
#endif
                maxio = NFS_V2MAXDATA;

        if ((argp->flags & NFSMNT_WSIZE) && argp->wsize > 0) {
                int osize = nmp->nm_wsize;
                nmp->nm_wsize = argp->wsize;
                /* Round down to multiple of blocksize */
                nmp->nm_wsize &= ~(NFS_FABLKSIZE - 1);
                if (nmp->nm_wsize <= 0)
                        nmp->nm_wsize = NFS_FABLKSIZE;
                adjsock |= (nmp->nm_wsize != osize);
        }
        if (nmp->nm_wsize > maxio)
                nmp->nm_wsize = maxio;
        if (nmp->nm_wsize > MAXBSIZE)
                nmp->nm_wsize = MAXBSIZE;

        if ((argp->flags & NFSMNT_RSIZE) && argp->rsize > 0) {
                int osize = nmp->nm_rsize;
                nmp->nm_rsize = argp->rsize;
                /* Round down to multiple of blocksize */
                nmp->nm_rsize &= ~(NFS_FABLKSIZE - 1);
                if (nmp->nm_rsize <= 0)
                        nmp->nm_rsize = NFS_FABLKSIZE;
                adjsock |= (nmp->nm_rsize != osize);
        }
        if (nmp->nm_rsize > maxio)
                nmp->nm_rsize = maxio;
        if (nmp->nm_rsize > MAXBSIZE)
                nmp->nm_rsize = MAXBSIZE;

        if ((argp->flags & NFSMNT_READDIRSIZE) && argp->readdirsize > 0) {
                nmp->nm_readdirsize = argp->readdirsize;
                /* Round down to multiple of minimum blocksize */
                nmp->nm_readdirsize &= ~(NFS_DIRFRAGSIZ - 1);
                if (nmp->nm_readdirsize < NFS_DIRFRAGSIZ)
                        nmp->nm_readdirsize = NFS_DIRFRAGSIZ;
                /* Bigger than buffer size makes no sense */
                if (nmp->nm_readdirsize > NFS_DIRBLKSIZ)
                        nmp->nm_readdirsize = NFS_DIRBLKSIZ;
        } else if (argp->flags & NFSMNT_RSIZE)
                nmp->nm_readdirsize = nmp->nm_rsize;

        if (nmp->nm_readdirsize > maxio)
                nmp->nm_readdirsize = maxio;

        if ((argp->flags & NFSMNT_MAXGRPS) && argp->maxgrouplist >= 0 &&
                argp->maxgrouplist <= NFS_MAXGRPS)
                nmp->nm_numgrps = argp->maxgrouplist;
        if ((argp->flags & NFSMNT_READAHEAD) && argp->readahead >= 0 &&
                argp->readahead <= NFS_MAXRAHEAD)
                nmp->nm_readahead = argp->readahead;
        if ((argp->flags & NFSMNT_DEADTHRESH) && argp->deadthresh >= 1 &&
                argp->deadthresh <= NFS_NEVERDEAD)
                nmp->nm_deadthresh = argp->deadthresh;

        adjsock |= ((nmp->nm_sotype != argp->sotype) ||
                    (nmp->nm_soproto != argp->proto));
        nmp->nm_sotype = argp->sotype;
        nmp->nm_soproto = argp->proto;

        if (nmp->nm_so && adjsock) {
                nfs_safedisconnect(nmp);
                if (nmp->nm_sotype == SOCK_DGRAM)
                        while (nfs_connect(nmp, (struct nfsreq *)0, l)) {
                                printf("nfs_args: retrying connect\n");
                                kpause("nfscn3", false, hz, NULL);
                        }
        }
}

/*
 * VFS Operations.
 *
 * mount system call
 * It seems a bit dumb to copyinstr() the host and path here and then
 * memcpy() them in mountnfs(), but I wanted to detect errors before
 * doing the sockargs() call because sockargs() allocates an mbuf and
 * an error after that means that I have to release the mbuf.
 */
/* ARGSUSED */
int
nfs_mount(struct mount *mp, const char *path, void *data, size_t *data_len)
{
        struct lwp *l = curlwp;
        int error;
        struct nfs_args *args = data;
        struct mbuf *nam;
        struct nfsmount *nmp = VFSTONFS(mp);
        struct sockaddr *sa;
        struct vnode *vp;
        char *pth, *hst;
        size_t len;
        u_char *nfh;

        if (args == NULL)
                return EINVAL;
        if (*data_len < sizeof *args)
                return EINVAL;

        if (mp->mnt_flag & MNT_GETARGS) {

                if (nmp == NULL)
                        return (EIO);
                if (args->addr != NULL) {
                        sa = mtod(nmp->nm_nam, struct sockaddr *);
                        error = copyout(sa, args->addr, sa->sa_len);
                        if (error)
                                return (error);
                        args->addrlen = sa->sa_len;
                } else
                        args->addrlen = 0;

                args->version = NFS_ARGSVERSION;
                args->sotype = nmp->nm_sotype;
                args->proto = nmp->nm_soproto;
                args->fh = NULL;
                args->fhsize = 0;
                args->flags = nmp->nm_flag;
                args->wsize = nmp->nm_wsize;
                args->rsize = nmp->nm_rsize;
                args->readdirsize = nmp->nm_readdirsize;
                args->timeo = nmp->nm_timeo;
                args->retrans = nmp->nm_retry;
                args->maxgrouplist = nmp->nm_numgrps;
                args->readahead = nmp->nm_readahead;
                args->leaseterm = 0; /* dummy */
                args->deadthresh = nmp->nm_deadthresh;
                args->hostname = NULL;
                *data_len = sizeof *args;
                return 0;
        }

        if (args->version != NFS_ARGSVERSION)
                return (EPROGMISMATCH);
        if (args->flags & (NFSMNT_NQNFS|NFSMNT_KERB))
                return (EPROGUNAVAIL);
#ifdef NFS_V2_ONLY
        if (args->flags & NFSMNT_NFSV3)
                return (EPROGMISMATCH);
#endif
        if (mp->mnt_flag & MNT_UPDATE) {
                if (nmp == NULL)
                        return (EIO);
                /*
                 * When doing an update, we can't change from or to
                 * v3, or change cookie translation
                 */
                args->flags = (args->flags & ~(NFSMNT_NFSV3|NFSMNT_XLATECOOKIE)) |
                    (nmp->nm_flag & (NFSMNT_NFSV3|NFSMNT_XLATECOOKIE));
                nfs_decode_args(nmp, args, l);
                return (0);
        }
        if (args->fhsize < 0 || args->fhsize > NFSX_V3FHMAX)
                return (EINVAL);
        nfh = malloc(NFSX_V3FHMAX, M_TEMP, M_WAITOK);
        error = copyin(args->fh, nfh, args->fhsize);
        if (error)
                goto free_nfh;
        pth = malloc(MNAMELEN, M_TEMP, M_WAITOK);
        error = copyinstr(path, pth, MNAMELEN - 1, &len);
        if (error)
                goto free_pth;
        memset(&pth[len], 0, MNAMELEN - len);
        hst = malloc(MNAMELEN, M_TEMP, M_WAITOK);
        error = copyinstr(args->hostname, hst, MNAMELEN - 1, &len);
        if (error)
                goto free_hst;
        memset(&hst[len], 0, MNAMELEN - len);
        /* sockargs() call must be after above copyin() calls */
        error = sockargs(&nam, args->addr, args->addrlen, UIO_USERSPACE,
            MT_SONAME);
        if (error)
                goto free_hst;
        MCLAIM(nam, &nfs_mowner);
        args->fh = nfh;
        error = mountnfs(args, mp, nam, pth, hst, &vp, l);

free_hst:
        free(hst, M_TEMP);
free_pth:
        free(pth, M_TEMP);
free_nfh:
        free(nfh, M_TEMP);

        return (error);
}

/*
 * Common code for mount and mountroot
 */
int
mountnfs(struct nfs_args *argp, struct mount *mp, struct mbuf *nam, const char *pth, const char *hst, struct vnode **vpp, struct lwp *l)
{
        struct nfsmount *nmp;
        struct nfsnode *np;
        struct vnode *vp;
        int error;
        struct vattr *attrs;
        kauth_cred_t cr;
        char iosname[IOSTATNAMELEN];

        /*
         * If the number of nfs iothreads to use has never
         * been set, create a reasonable number of them.
         */

        if (nfs_niothreads < 0) {
                nfs_set_niothreads(NFS_DEFAULT_NIOTHREADS);
        }

        if (mp->mnt_flag & MNT_UPDATE) {
                nmp = VFSTONFS(mp);
                /* update paths, file handles, etc, here        XXX */
                m_freem(nam);
                return 0;
        }
        nmp = kmem_zalloc(sizeof(*nmp), KM_SLEEP);
        TAILQ_INIT(&nmp->nm_uidlruhead);
        TAILQ_INIT(&nmp->nm_bufq);
        rw_init(&nmp->nm_writeverflock);
        mutex_init(&nmp->nm_lock, MUTEX_DEFAULT, IPL_NONE);
        cv_init(&nmp->nm_rcvcv, "nfsrcv");
        cv_init(&nmp->nm_sndcv, "nfssnd");
        cv_init(&nmp->nm_aiocv, "nfsaio");
        cv_init(&nmp->nm_disconcv, "nfsdis");

        mp->mnt_data = nmp;
        mp->mnt_stat.f_namemax = NFS_MAXNAMLEN;
        vfs_getnewfsid(mp);
        nmp->nm_mountp = mp;

#ifndef NFS_V2_ONLY
        if ((argp->flags & NFSMNT_NFSV3) == 0)
#endif
        {
                if (argp->fhsize != NFSX_V2FH) {
                        return EINVAL;
                }
        }

        /*
         * V2 can only handle 32 bit filesizes. For v3, nfs_fsinfo
         * will overwrite this.
         */
        nmp->nm_maxfilesize = 0xffffffffLL;

        nmp->nm_timeo = NFS_TIMEO;
        nmp->nm_retry = NFS_RETRANS;
        nmp->nm_wsize = NFS_WSIZE;
        nmp->nm_rsize = NFS_RSIZE;
        nmp->nm_readdirsize = NFS_READDIRSIZE;
        nmp->nm_numgrps = NFS_MAXGRPS;
        nmp->nm_readahead = NFS_DEFRAHEAD;
        nmp->nm_deadthresh = NFS_DEFDEADTHRESH;
        error = set_statvfs_info(pth, UIO_SYSSPACE, hst, UIO_SYSSPACE,
            mp->mnt_op->vfs_name, mp, l);
        if (error)
                goto bad;
        nmp->nm_nam = nam;

        /* Set up the sockets and per-host congestion */
        nmp->nm_sotype = argp->sotype;
        nmp->nm_soproto = argp->proto;

        nfs_decode_args(nmp, argp, l);

        mp->mnt_fs_bshift = ffs(MIN(nmp->nm_rsize, nmp->nm_wsize)) - 1;
        mp->mnt_dev_bshift = DEV_BSHIFT;

        /*
         * For Connection based sockets (TCP,...) defer the connect until
         * the first request, in case the server is not responding.
         */
        if (nmp->nm_sotype == SOCK_DGRAM &&
                (error = nfs_connect(nmp, (struct nfsreq *)0, l)))
                goto bad;

        /*
         * This is silly, but it has to be set so that vinifod() works.
         * We do not want to do an nfs_statvfs() here since we can get
         * stuck on a dead server and we are holding a lock on the mount
         * point.
         */
        mp->mnt_stat.f_iosize = NFS_MAXDGRAMDATA;
        error = nfs_nget(mp, (nfsfh_t *)argp->fh, argp->fhsize, &np);
        if (error)
                goto bad;
        vp = NFSTOV(np);
        attrs = malloc(sizeof(struct vattr), M_TEMP, M_WAITOK);
        VOP_GETATTR(vp, attrs, l->l_cred);
        if ((nmp->nm_flag & NFSMNT_NFSV3) && (vp->v_type == VDIR)) {
                cr = kauth_cred_alloc();
                kauth_cred_setuid(cr, attrs->va_uid);
                kauth_cred_seteuid(cr, attrs->va_uid);
                kauth_cred_setsvuid(cr, attrs->va_uid);
                kauth_cred_setgid(cr, attrs->va_gid);
                kauth_cred_setegid(cr, attrs->va_gid);
                kauth_cred_setsvgid(cr, attrs->va_gid);
                nfs_cookieheuristic(vp, &nmp->nm_iflag, l, cr);
                kauth_cred_free(cr);
        }
        free(attrs, M_TEMP);

        /*
         * A reference count is needed on the nfsnode representing the
         * remote root.  If this object is not persistent, then backward
         * traversals of the mount point (i.e. "..") will not work if
         * the nfsnode gets flushed out of the cache. Ufs does not have
         * this problem, because one can identify root inodes by their
         * number == UFS_ROOTINO (2). So, just unlock, but no rele.
         */

        nmp->nm_vnode = vp;
        if (vp->v_type == VNON)
                vp->v_type = VDIR;
        vp->v_vflag |= VV_ROOT;
        VOP_UNLOCK(vp);
        *vpp = vp;

        snprintf(iosname, sizeof(iosname), "nfs%u", nfs_mount_count++);
        nmp->nm_stats = iostat_alloc(IOSTAT_NFS, nmp, iosname);

        return (0);
bad:
        nfs_disconnect(nmp);
        rw_destroy(&nmp->nm_writeverflock);
        mutex_destroy(&nmp->nm_lock);
        cv_destroy(&nmp->nm_rcvcv);
        cv_destroy(&nmp->nm_sndcv);
        cv_destroy(&nmp->nm_aiocv);
        cv_destroy(&nmp->nm_disconcv);
        kmem_free(nmp, sizeof(*nmp));
        m_freem(nam);
        return (error);
}

/*
 * unmount system call
 */
int
nfs_unmount(struct mount *mp, int mntflags)
{
        struct nfsmount *nmp = VFSTONFS(mp);
        struct vnode *vp;
        int error, flags = 0;

        if (mntflags & MNT_FORCE) {
                mutex_enter(&nmp->nm_lock);
                flags |= FORCECLOSE;
                nmp->nm_iflag |= NFSMNT_DISMNTFORCE;
                mutex_exit(&nmp->nm_lock);

        }

        /*
         * Goes something like this..
         * - Check for activity on the root vnode (other than ourselves).
         * - Call vflush() to clear out vnodes for this file system,
         *   except for the root vnode.
         * - Decrement reference on the vnode representing remote root.
         * - Close the socket
         * - Free up the data structures
         */
        /*
         * We need to decrement the ref. count on the nfsnode representing
         * the remote root.  See comment in mountnfs().
         */
        vp = nmp->nm_vnode;
        error = vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
        if (error != 0)
                goto err;

        if ((mntflags & MNT_FORCE) == 0 && vrefcnt(vp) > 1) {
                VOP_UNLOCK(vp);
                error = EBUSY;
                goto err;
        }

        error = vflush(mp, vp, flags);
        if (error) {
                VOP_UNLOCK(vp);
                goto err;
        }

        /*
         * We are now committed to the unmount; mark the mount structure
         * as doomed so that any sleepers kicked awake by nfs_disconnect
         * will go away cleanly.
         */
        nmp->nm_iflag |= NFSMNT_DISMNT;

        /*
         * No new async I/O will be added, but await for pending
         * ones to drain.
         */
        while (nfs_iodbusy(nmp))
                kpause("nfsumnt", false, hz, NULL);

        /*
         * Clean up the stats... note that we carefully avoid decrementing
         * nfs_mount_count here for good reason - we may not be unmounting
         * the last thing mounted.
         */
        iostat_free(nmp->nm_stats);

        /*
         * There is one reference count to get rid of here
         * (see comment in mountnfs()).
         */
        VOP_UNLOCK(vp);
        vgone(vp);
        nfs_disconnect(nmp);
        m_freem(nmp->nm_nam);

        rw_destroy(&nmp->nm_writeverflock);
        mutex_destroy(&nmp->nm_lock);
        cv_destroy(&nmp->nm_rcvcv);
        cv_destroy(&nmp->nm_sndcv);
        cv_destroy(&nmp->nm_aiocv);
        cv_destroy(&nmp->nm_disconcv);
        kmem_free(nmp, sizeof(*nmp));
        return (0);

err:
        if (mntflags & MNT_FORCE) {
                mutex_enter(&nmp->nm_lock);
                nmp->nm_iflag &= ~NFSMNT_DISMNTFORCE;   
                mutex_exit(&nmp->nm_lock);
        }

        return error;
}

/*
 * Return root of a filesystem
 */
int
nfs_root(struct mount *mp, int lktype, struct vnode **vpp)
{
        struct vnode *vp;
        struct nfsmount *nmp;
        int error;

        nmp = VFSTONFS(mp);
        vp = nmp->nm_vnode;
        vref(vp);
        error = vn_lock(vp, lktype | LK_RETRY);
        if (error != 0) {
                vrele(vp);
                return error;
        }
        *vpp = vp;
        return (0);
}

extern int syncprt;

static bool
nfs_sync_selector(void *cl, struct vnode *vp)
{

        KASSERT(mutex_owned(vp->v_interlock));

        return !LIST_EMPTY(&vp->v_dirtyblkhd) ||
            (vp->v_iflag & VI_ONWORKLST) != 0;
}

/*
 * Flush out the buffer cache
 */
/* ARGSUSED */
int
nfs_sync(struct mount *mp, int waitfor, kauth_cred_t cred)
{
        struct vnode *vp;
        struct vnode_iterator *marker;
        int error, allerror = 0;

        /*
         * Force stale buffer cache information to be flushed.
         */
        vfs_vnode_iterator_init(mp, &marker);
        while ((vp = vfs_vnode_iterator_next(marker, nfs_sync_selector,
            NULL)))
        {
                error = vn_lock(vp, LK_EXCLUSIVE);
                if (error) {
                        vrele(vp);
                        continue;
                }
                error = VOP_FSYNC(vp, cred,
                    waitfor == MNT_WAIT ? FSYNC_WAIT : 0, 0, 0);
                if (error)
                        allerror = error;
                vput(vp);
        }
        vfs_vnode_iterator_destroy(marker);
        return allerror;
}

/*
 * NFS flat namespace lookup.
 * Currently unsupported.
 */
/* ARGSUSED */
int
nfs_vget(struct mount *mp, ino_t ino, int lktype, struct vnode **vpp)
{

        return (EOPNOTSUPP);
}

/*
 * Do that sysctl thang...
 */
static int
sysctl_vfs_nfs_iothreads(SYSCTLFN_ARGS)
{
        struct sysctlnode node;
        int val;
        int error;

        val = nfs_niothreads;
        node = *rnode;
        node.sysctl_data = &val;
        error = sysctl_lookup(SYSCTLFN_CALL(&node));
        if (error || newp == NULL)
                return error;

        return nfs_set_niothreads(val);
}

SYSCTL_SETUP(nfs_sysctl_init, "nfs sysctl")
{

        sysctl_createv(clog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT,
                       CTLTYPE_NODE, "nfs",
                       SYSCTL_DESCR("NFS vfs options"),
                       NULL, 0, NULL, 0,
                       CTL_VFS, 2, CTL_EOL);
        /*
         * XXX the "2" above could be dynamic, thereby eliminating one
         * more instance of the "number to vfs" mapping problem, but
         * "2" is the order as taken from sys/mount.h
         */

        sysctl_createv(clog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
                       CTLTYPE_STRUCT, "nfsstats",
                       SYSCTL_DESCR("NFS operation statistics"),
                       NULL, 0, &nfsstats, sizeof(nfsstats),
                       CTL_VFS, 2, NFS_NFSSTATS, CTL_EOL);
        sysctl_createv(clog, 0, NULL, NULL,
                       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
                       CTLTYPE_INT, "iothreads",
                       SYSCTL_DESCR("Number of NFS client processes desired"),
                       sysctl_vfs_nfs_iothreads, 0, NULL, 0,
                       CTL_VFS, 2, NFS_IOTHREADS, CTL_EOL);
}

/* ARGSUSED */
int
nfs_fhtovp(struct mount *mp, struct fid *fid, int lktype, struct vnode **vpp)
{
        size_t fidsize;
        size_t fhsize;
        struct nfsnode *np;
        int error;
        struct vattr va;

        fidsize = fid->fid_len;
        if (fidsize < sizeof(*fid)) {
                return EINVAL;
        }
        fhsize = fidsize - sizeof(*fid);
        if ((fhsize % NFSX_UNSIGNED) != 0) {
                return EINVAL;
        }
        if ((VFSTONFS(mp)->nm_flag & NFSMNT_NFSV3) != 0) {
                if (fhsize > NFSX_V3FHMAX || fhsize == 0) {
                        return EINVAL;
                }
        } else {
                if (fhsize != NFSX_V2FH) {
                        return EINVAL;
                }
        }
        /* XXX lktype ignored */
        error = nfs_nget(mp, (void *)fid->fid_data, fhsize, &np);
        if (error) {
                return error;
        }
        *vpp = NFSTOV(np);
        error = VOP_GETATTR(*vpp, &va, kauth_cred_get());
        if (error != 0) {
                vput(*vpp);
                *vpp = NULLVP;
        }
        return error;
}

/* ARGSUSED */
int
nfs_vptofh(struct vnode *vp, struct fid *buf, size_t *bufsize)
{
        struct nfsnode *np;
        struct fid *fid;
        size_t fidsize;
        int error = 0;

        np = VTONFS(vp);
        fidsize = sizeof(*fid) + np->n_fhsize;
        if (*bufsize < fidsize) {
                error = E2BIG;
        }
        *bufsize = fidsize;
        if (error == 0) {
                struct fid fid_store;

                fid = &fid_store;
                memset(fid, 0, sizeof(*fid));
                fid->fid_len = fidsize;
                memcpy(buf, fid, sizeof(*fid));
                memcpy(buf->fid_data, np->n_fhp, np->n_fhsize);
        }
        return error;
}

/*
 * Vfs start routine, a no-op.
 */
/* ARGSUSED */
int
nfs_start(struct mount *mp, int flags)
{

        return (0);
}

/*
 * Called once at VFS init to initialize client-specific data structures.
 */
void
nfs_vfs_init(void)
{
        unsigned scale;

        /* Initialize NFS server / client shared data. */
        nfs_init();
        nfs_node_init();

        /* Initialize the kqueue structures */
        nfs_kqinit();
        /* Initialize the iod structures */
        nfs_iodinit();

        scale = PAGE_SHIFT - 4;
        nfs_commitsize = uimin(uvmexp.npages, INT_MAX >> scale) << scale;
}

void
nfs_vfs_done(void)
{

        nfs_node_done();
        nfs_kqfini();
        nfs_iodfini();
        nfs_fini();
}