sys/nfs/nfs_vfsops.c

/*
 * 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.
 *
 * %sccs.include.redist.c%
 *
 *	@(#)nfs_vfsops.c	8.12 (Berkeley) 05/20/95
 */

#include <sys/param.h>
#include <sys/conf.h>
#include <sys/ioctl.h>
#include <sys/signal.h>
#include <sys/proc.h>
#include <sys/namei.h>
#include <sys/vnode.h>
#include <sys/kernel.h>
#include <sys/mount.h>
#include <sys/buf.h>
#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/systm.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/nqnfs.h>

struct nfsstats nfsstats;
static int nfs_sysctl(int *, u_int, void *, size_t *, void *, size_t,
		      struct proc *);
extern int nfs_ticks;

/*
 * nfs vfs operations.
 */
struct vfsops nfs_vfsops = {
	nfs_mount,
	nfs_start,
	nfs_unmount,
	nfs_root,
	nfs_quotactl,
	nfs_statfs,
	nfs_sync,
	nfs_vget,
	nfs_fhtovp,
	nfs_vptofh,
	nfs_init,
	nfs_sysctl
};

/*
 * This structure must be filled in by a primary bootstrap or bootstrap
 * server for a diskless/dataless machine. It is initialized below just
 * to ensure that it is allocated to initialized data (.data not .bss).
 */
struct nfs_diskless nfs_diskless = { 0 };
int nfs_diskless_valid = 0;

void nfs_disconnect __P((struct nfsmount *));
void nfsargs_ntoh __P((struct nfs_args *));
int nfs_fsinfo __P((struct nfsmount *, struct vnode *, struct ucred *,
	struct proc *));
static int nfs_mountdiskless __P((char *, char *, int, struct sockaddr_in *,
	struct nfs_args *, struct proc *, struct vnode **, struct mount **));

/*
 * nfs statfs call
 */
int
nfs_statfs(mp, sbp, p)
	struct mount *mp;
	register struct statfs *sbp;
	struct proc *p;
{
	register struct vnode *vp;
	register struct nfs_statfs *sfp;
	register caddr_t cp;
	register u_long *tl;
	register long t1, t2;
	caddr_t bpos, dpos, cp2;
	struct nfsmount *nmp = VFSTONFS(mp);
	int error = 0, v3 = (nmp->nm_flag & NFSMNT_NFSV3), retattr;
	struct mbuf *mreq, *mrep, *md, *mb, *mb2;
	struct ucred *cred;
	struct nfsnode *np;
	u_quad_t tquad;

#ifndef nolint
	sfp = (struct nfs_statfs *)0;
#endif
	error = nfs_nget(mp, (nfsfh_t *)nmp->nm_fh, nmp->nm_fhsize, &np);
	if (error)
		return (error);
	vp = NFSTOV(np);
	cred = crget();
	cred->cr_ngroups = 1;
	if (v3 && (nmp->nm_flag & NFSMNT_GOTFSINFO) == 0)
		(void)nfs_fsinfo(nmp, vp, cred, p);
	nfsstats.rpccnt[NFSPROC_FSSTAT]++;
	nfsm_reqhead(vp, NFSPROC_FSSTAT, NFSX_FH(v3));
	nfsm_fhtom(vp, v3);
	nfsm_request(vp, NFSPROC_FSSTAT, p, cred);
	if (v3)
		nfsm_postop_attr(vp, retattr);
	if (!error)
		nfsm_dissect(sfp, struct nfs_statfs *, NFSX_STATFS(v3));
	sbp->f_iosize = min(nmp->nm_rsize, nmp->nm_wsize);
	if (v3) {
		sbp->f_bsize = NFS_FABLKSIZE;
		fxdr_hyper(&sfp->sf_tbytes, &tquad);
		sbp->f_blocks = (long)(tquad / ((u_quad_t)NFS_FABLKSIZE));
		fxdr_hyper(&sfp->sf_fbytes, &tquad);
		sbp->f_bfree = (long)(tquad / ((u_quad_t)NFS_FABLKSIZE));
		fxdr_hyper(&sfp->sf_abytes, &tquad);
		sbp->f_bavail = (long)(tquad / ((u_quad_t)NFS_FABLKSIZE));
		sbp->f_files = (fxdr_unsigned(long, sfp->sf_tfiles.nfsuquad[1])
			& 0x7fffffff);
		sbp->f_ffree = (fxdr_unsigned(long, sfp->sf_ffiles.nfsuquad[1])
			& 0x7fffffff);
	} else {
		sbp->f_bsize = fxdr_unsigned(long, sfp->sf_bsize);
		sbp->f_blocks = fxdr_unsigned(long, sfp->sf_blocks);
		sbp->f_bfree = fxdr_unsigned(long, sfp->sf_bfree);
		sbp->f_bavail = fxdr_unsigned(long, sfp->sf_bavail);
		sbp->f_files = 0;
		sbp->f_ffree = 0;
	}
	if (sbp != &mp->mnt_stat) {
		bcopy(mp->mnt_stat.f_mntonname, sbp->f_mntonname, MNAMELEN);
		bcopy(mp->mnt_stat.f_mntfromname, sbp->f_mntfromname, MNAMELEN);
	}
	nfsm_reqdone;
	vrele(vp);
	crfree(cred);
	return (error);
}

/*
 * nfs version 3 fsinfo rpc call
 */
int
nfs_fsinfo(nmp, vp, cred, p)
	register struct nfsmount *nmp;
	register struct vnode *vp;
	struct ucred *cred;
	struct proc *p;
{
	register struct nfsv3_fsinfo *fsp;
	register caddr_t cp;
	register long t1, t2;
	register u_long *tl, pref, max;
	caddr_t bpos, dpos, cp2;
	int error = 0, retattr;
	struct mbuf *mreq, *mrep, *md, *mb, *mb2;

	nfsstats.rpccnt[NFSPROC_FSINFO]++;
	nfsm_reqhead(vp, NFSPROC_FSINFO, NFSX_FH(1));
	nfsm_fhtom(vp, 1);
	nfsm_request(vp, NFSPROC_FSINFO, p, cred);
	nfsm_postop_attr(vp, retattr);
	if (!error) {
		nfsm_dissect(fsp, struct nfsv3_fsinfo *, NFSX_V3FSINFO);
		pref = fxdr_unsigned(u_long, fsp->fs_wtpref);
		if (pref < nmp->nm_wsize)
			nmp->nm_wsize = (pref + NFS_FABLKSIZE - 1) &
				~(NFS_FABLKSIZE - 1);
		max = fxdr_unsigned(u_long, fsp->fs_wtmax);
		if (max < nmp->nm_wsize) {
			nmp->nm_wsize = max & ~(NFS_FABLKSIZE - 1);
			if (nmp->nm_wsize == 0)
				nmp->nm_wsize = max;
		}
		pref = fxdr_unsigned(u_long, fsp->fs_rtpref);
		if (pref < nmp->nm_rsize)
			nmp->nm_rsize = (pref + NFS_FABLKSIZE - 1) &
				~(NFS_FABLKSIZE - 1);
		max = fxdr_unsigned(u_long, fsp->fs_rtmax);
		if (max < nmp->nm_rsize) {
			nmp->nm_rsize = max & ~(NFS_FABLKSIZE - 1);
			if (nmp->nm_rsize == 0)
				nmp->nm_rsize = max;
		}
		pref = fxdr_unsigned(u_long, fsp->fs_dtpref);
		if (pref < nmp->nm_readdirsize)
			nmp->nm_readdirsize = (pref + NFS_DIRBLKSIZ - 1) &
				~(NFS_DIRBLKSIZ - 1);
		if (max < nmp->nm_readdirsize) {
			nmp->nm_readdirsize = max & ~(NFS_DIRBLKSIZ - 1);
			if (nmp->nm_readdirsize == 0)
				nmp->nm_readdirsize = max;
		}
		nmp->nm_flag |= NFSMNT_GOTFSINFO;
	}
	nfsm_reqdone;
	return (error);
}

/*
 * Mount a remote root fs via. nfs. This depends on the info in the
 * nfs_diskless structure that has been filled in properly by some primary
 * bootstrap.
 * It goes something like this:
 * - do enough of "ifconfig" by calling ifioctl() so that the system
 *   can talk to the server
 * - If nfs_diskless.mygateway is filled in, use that address as
 *   a default gateway.
 * - hand craft the swap nfs vnode hanging off a fake mount point
 *	if swdevt[0].sw_dev == NODEV
 * - build the rootfs mount point and call mountnfs() to do the rest.
 */
int
nfs_mountroot()
{
	struct mount *mp, *swap_mp;
	struct nfs_diskless *nd = &nfs_diskless;
	struct socket *so;
	struct vnode *vp;
	struct proc *p = curproc;		/* XXX */
	int error, i;
	u_long l;
	char buf[128];

	/*
	 * XXX time must be non-zero when we init the interface or else
	 * the arp code will wedge...
	 */
	if (time.tv_sec == 0)
		time.tv_sec = 1;

	/*
	 * XXX splnet, so networks will receive...
	 */
	splnet();

#ifdef notyet
	/* Set up swap credentials. */
	proc0.p_ucred->cr_uid = ntohl(nd->swap_ucred.cr_uid);
	proc0.p_ucred->cr_gid = ntohl(nd->swap_ucred.cr_gid);
	if ((proc0.p_ucred->cr_ngroups = ntohs(nd->swap_ucred.cr_ngroups)) >
		NGROUPS)
		proc0.p_ucred->cr_ngroups = NGROUPS;
	for (i = 0; i < proc0.p_ucred->cr_ngroups; i++)
	    proc0.p_ucred->cr_groups[i] = ntohl(nd->swap_ucred.cr_groups[i]);
#endif

	/*
	 * Do enough of ifconfig(8) so that the critical net interface can
	 * talk to the server.
	 */
	error = socreate(nd->myif.ifra_addr.sa_family, &so, SOCK_DGRAM, 0);
	if (error) {
		printf("nfs_mountroot: socreate(%04x): %d",
			nd->myif.ifra_addr.sa_family, error);
		return (error);
	}

	/*
	 * We might not have been told the right interface, so we pass
	 * over the first ten interfaces of the same kind, until we get
	 * one of them configured.
	 */

	for (i = strlen(nd->myif.ifra_name) - 1;
		nd->myif.ifra_name[i] >= '0' &&
		nd->myif.ifra_name[i] <= '9';
		nd->myif.ifra_name[i] ++) {
		error = ifioctl(so, SIOCAIFADDR, (caddr_t)&nd->myif, p);
		if(!error)
			break;
	}
	if (error) {
		printf("nfs_mountroot: SIOCAIFADDR: %d", error);
		return (error);
	}
	soclose(so);

	/*
	 * If the gateway field is filled in, set it as the default route.
	 */
	if (nd->mygateway.sin_len != 0) {
		struct sockaddr_in mask, sin;

		bzero((caddr_t)&mask, sizeof(mask));
		sin = mask;
		sin.sin_family = AF_INET;
		sin.sin_len = sizeof(sin);
		error = rtrequest(RTM_ADD, (struct sockaddr *)&sin,
		    (struct sockaddr *)&nd->mygateway,
		    (struct sockaddr *)&mask,
		    RTF_UP | RTF_GATEWAY, (struct rtentry **)0);
		if (error) {
			printf("nfs_mountroot: RTM_ADD: %d", error);
			return (error);
		}
	}

	swap_mp = NULL;
	if (nd->swap_nblks) {
		/*
		 * Create a fake mount point just for the swap vnode so that the
		 * swap file can be on a different server from the rootfs.
		 */
		nd->swap_args.fh = nd->swap_fh;
		/*
		 * If using nfsv3_diskless, replace NFSX_V2FH with
		 * nd->swap_fhsize.
		 */
		nd->swap_args.fhsize = NFSX_V2FH;
		l = ntohl(nd->swap_saddr.sin_addr.s_addr);
		sprintf(buf,"%ld.%ld.%ld.%ld:%s",
			(l >> 24) & 0xff, (l >> 16) & 0xff,
			(l >>  8) & 0xff, (l >>  0) & 0xff,nd->swap_hostnam);
		printf("NFS SWAP: %s\n",buf);
		if (error = nfs_mountdiskless(buf, "/swap", 0,
		    &nd->swap_saddr, &nd->swap_args, p, &vp, &swap_mp))
			return (error);
		vfs_unbusy(swap_mp, p);

		for (i=0;swdevt[i].sw_dev != NODEV;i++) ;

		/*
		 * Since the swap file is not the root dir of a file system,
		 * hack it to a regular file.
		 */
		vp->v_type = VREG;
		vp->v_flag = 0;
		swapdev_vp = vp;
		VREF(vp);
		swdevt[i].sw_vp = vp;
		swdevt[i].sw_nblks = nd->swap_nblks*2;

		if (!swdevt[i].sw_nblks) {
			swdevt[i].sw_nblks = 2048;
			printf("defaulting to %d kbyte.\n",
				swdevt[i].sw_nblks/2);
		} else
			printf("using %d kbyte.\n",swdevt[i].sw_nblks/2);
	}

	/*
	 * Create the rootfs mount point.
	 */
	nd->root_args.fh = nd->root_fh;
	/*
	 * If using nfsv3_diskless, replace NFSX_V2FH with nd->root_fhsize.
	 */
	nd->root_args.fhsize = NFSX_V2FH;
	l = ntohl(nd->swap_saddr.sin_addr.s_addr);
	sprintf(buf,"%ld.%ld.%ld.%ld:%s",
		(l >> 24) & 0xff, (l >> 16) & 0xff,
		(l >>  8) & 0xff, (l >>  0) & 0xff,nd->root_hostnam);
	printf("NFS ROOT: %s\n",buf);
	if (error = nfs_mountdiskless(buf, "/", MNT_RDONLY,
	    &nd->root_saddr, &nd->root_args, p, &vp, &mp)) {
		if (swap_mp) {
			mp->mnt_vfc->vfc_refcount--;
			free(swap_mp, M_MOUNT);
		}
		return (error);
	}

	simple_lock(&mountlist_slock);
	CIRCLEQ_INSERT_TAIL(&mountlist, mp, mnt_list);
	simple_unlock(&mountlist_slock);
	rootvp = vp;
	vfs_unbusy(mp, p);

	/*
	 * This is not really an nfs issue, but it is much easier to
	 * set hostname here and then let the "/etc/rc.xxx" files
	 * mount the right /var based upon its preset value.
	 */
	bcopy(nd->my_hostnam, hostname, MAXHOSTNAMELEN);
	hostname[MAXHOSTNAMELEN - 1] = '\0';
	for (i = 0; i < MAXHOSTNAMELEN; i++)
		if (hostname[i] == '\0')
			break;
	hostnamelen = i;
	inittodr(ntohl(nd->root_time));
	return (0);
}

/*
 * Internal version of mount system call for diskless setup.
 */
static int
nfs_mountdiskless(path, which, mountflag, sin, args, p, vpp, mpp)
	char *path;
	char *which;
	int mountflag;
	struct sockaddr_in *sin;
	struct nfs_args *args;
	struct proc *p;
	struct vnode **vpp;
	struct mount **mpp;
{
	struct mount *mp;
	struct mbuf *m;
	int error;

	if (error = vfs_rootmountalloc("nfs", path, &mp)) {
		printf("nfs_mountroot: NFS not configured");
		return (error);
	}
	mp->mnt_flag = mountflag;
	MGET(m, MT_SONAME, M_WAITOK);
	bcopy((caddr_t)sin, mtod(m, caddr_t), sin->sin_len);
	m->m_len = sin->sin_len;
	if (error = mountnfs(args, mp, m, which, path, vpp)) {
		printf("nfs_mountroot: mount %s on %s: %d", path, which, error);
		mp->mnt_vfc->vfc_refcount--;
		vfs_unbusy(mp, p);
		free(mp, M_MOUNT);
		return (error);
	}
	(void) copystr(which, mp->mnt_stat.f_mntonname, MNAMELEN - 1, 0);
	*mpp = mp;
	return (0);
}

/*
 * VFS Operations.
 *
 * mount system call
 * It seems a bit dumb to copyinstr() the host and path here and then
 * bcopy() 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(mp, path, data, ndp, p)
	struct mount *mp;
	char *path;
	caddr_t data;
	struct nameidata *ndp;
	struct proc *p;
{
	int error;
	struct nfs_args args;
	struct mbuf *nam;
	struct vnode *vp;
	char pth[MNAMELEN], hst[MNAMELEN];
	u_int len;
	u_char nfh[NFSX_V3FHMAX];

	error = copyin(data, (caddr_t)&args, sizeof (struct nfs_args));
	if (error)
		return (error);
	if (args.version != NFS_ARGSVERSION)
		return (EPROGMISMATCH);
	error = copyin((caddr_t)args.fh, (caddr_t)nfh, args.fhsize);
	if (error)
		return (error);
	error = copyinstr(path, pth, MNAMELEN-1, &len);
	if (error)
		return (error);
	bzero(&pth[len], MNAMELEN - len);
	error = copyinstr(args.hostname, hst, MNAMELEN-1, &len);
	if (error)
		return (error);
	bzero(&hst[len], MNAMELEN - len);
	/* sockargs() call must be after above copyin() calls */
	error = sockargs(&nam, (caddr_t)args.addr, args.addrlen, MT_SONAME);
	if (error)
		return (error);
	args.fh = nfh;
	error = mountnfs(&args, mp, nam, pth, hst, &vp);
	return (error);
}

/*
 * Common code for mount and mountroot
 */
int
mountnfs(argp, mp, nam, pth, hst, vpp)
	register struct nfs_args *argp;
	register struct mount *mp;
	struct mbuf *nam;
	char *pth, *hst;
	struct vnode **vpp;
{
	register struct nfsmount *nmp;
	struct nfsnode *np;
	int error, maxio;

	if (mp->mnt_flag & MNT_UPDATE) {
		nmp = VFSTONFS(mp);
		/* update paths, file handles, etc, here	XXX */
		m_freem(nam);
		return (0);
	} else {
		MALLOC(nmp, struct nfsmount *, sizeof (struct nfsmount),
		    M_NFSMNT, M_WAITOK);
		bzero((caddr_t)nmp, sizeof (struct nfsmount));
		TAILQ_INIT(&nmp->nm_uidlruhead);
		mp->mnt_data = (qaddr_t)nmp;
	}
	vfs_getnewfsid(mp);
	nmp->nm_mountp = mp;
	nmp->nm_flag = argp->flags;
	if (nmp->nm_flag & NFSMNT_NQNFS)
		/*
		 * We have to set mnt_maxsymlink to a non-zero value so
		 * that COMPAT_43 routines will know that we are setting
		 * the d_type field in directories (and can zero it for
		 * unsuspecting binaries).
		 */
		mp->mnt_maxsymlinklen = 1;
	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_leaseterm = NQ_DEFLEASE;
	nmp->nm_deadthresh = NQ_DEADTHRESH;
	CIRCLEQ_INIT(&nmp->nm_timerhead);
	nmp->nm_inprog = NULLVP;
	nmp->nm_fhsize = argp->fhsize;
	bcopy((caddr_t)argp->fh, (caddr_t)nmp->nm_fh, argp->fhsize);
	bcopy(hst, mp->mnt_stat.f_mntfromname, MNAMELEN);
	bcopy(pth, mp->mnt_stat.f_mntonname, MNAMELEN);
	nmp->nm_nam = nam;

	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;
	}

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

	if ((argp->flags & NFSMNT_WSIZE) && argp->wsize > 0) {
		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;
	}
	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) {
		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;
	}
	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 blocksize */
		nmp->nm_readdirsize &= ~(NFS_DIRBLKSIZ - 1);
		if (nmp->nm_readdirsize < NFS_DIRBLKSIZ)
			nmp->nm_readdirsize = NFS_DIRBLKSIZ;
	}
	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_LEASETERM) && argp->leaseterm >= 2 &&
		argp->leaseterm <= NQ_MAXLEASE)
		nmp->nm_leaseterm = argp->leaseterm;
	if ((argp->flags & NFSMNT_DEADTHRESH) && argp->deadthresh >= 1 &&
		argp->deadthresh <= NQ_NEVERDEAD)
		nmp->nm_deadthresh = argp->deadthresh;
	/* Set up the sockets and per-host congestion */
	nmp->nm_sotype = argp->sotype;
	nmp->nm_soproto = argp->proto;

	/*
	 * 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)))
		goto bad;

	/*
	 * This is silly, but it has to be set so that vinifod() works.
	 * We do not want to do an nfs_statfs() 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;
	/*
	 * 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 == ROOTINO (2).
	 */
	error = nfs_nget(mp, (nfsfh_t *)nmp->nm_fh, nmp->nm_fhsize, &np);
	if (error)
		goto bad;
	*vpp = NFSTOV(np);

	return (0);
bad:
	nfs_disconnect(nmp);
	free((caddr_t)nmp, M_NFSMNT);
	m_freem(nam);
	return (error);
}

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

	if (mntflags & MNT_FORCE)
		flags |= FORCECLOSE;
	nmp = VFSTONFS(mp);
	/*
	 * 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().  The VFS unmount()
	 * has done vput on this vnode, otherwise we would get deadlock!
	 */
	error = nfs_nget(mp, (nfsfh_t *)nmp->nm_fh, nmp->nm_fhsize, &np);
	if (error)
		return(error);
	vp = NFSTOV(np);
	if (vp->v_usecount > 2) {
		vput(vp);
		return (EBUSY);
	}

	/*
	 * Must handshake with nqnfs_clientd() if it is active.
	 */
	nmp->nm_flag |= NFSMNT_DISMINPROG;
	while (nmp->nm_inprog != NULLVP)
		(void) tsleep((caddr_t)&lbolt, PSOCK, "nfsdism", 0);
	error = vflush(mp, vp, flags);
	if (error) {
		vput(vp);
		nmp->nm_flag &= ~NFSMNT_DISMINPROG;
		return (error);
	}

	/*
	 * We are now committed to the unmount.
	 * For NQNFS, let the server daemon free the nfsmount structure.
	 */
	if (nmp->nm_flag & (NFSMNT_NQNFS | NFSMNT_KERB))
		nmp->nm_flag |= NFSMNT_DISMNT;

	/*
	 * There are two reference counts to get rid of here.
	 */
	vrele(vp);
	vrele(vp);
	vgone(vp);
	nfs_disconnect(nmp);
	m_freem(nmp->nm_nam);

	if ((nmp->nm_flag & (NFSMNT_NQNFS | NFSMNT_KERB)) == 0)
		free((caddr_t)nmp, M_NFSMNT);
	return (0);
}

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

	nmp = VFSTONFS(mp);
	error = nfs_nget(mp, (nfsfh_t *)nmp->nm_fh, nmp->nm_fhsize, &np);
	if (error)
		return (error);
	vp = NFSTOV(np);
	vp->v_type = VDIR;
	vp->v_flag = VROOT;
	*vpp = vp;
	return (0);
}

extern int syncprt;

/*
 * Flush out the buffer cache
 */
/* ARGSUSED */
int
nfs_sync(mp, waitfor, cred, p)
	struct mount *mp;
	int waitfor;
	struct ucred *cred;
	struct proc *p;
{
	register struct vnode *vp;
	int error, allerror = 0;

	/*
	 * Force stale buffer cache information to be flushed.
	 */
loop:
	for (vp = mp->mnt_vnodelist.lh_first;
	     vp != NULL;
	     vp = vp->v_mntvnodes.le_next) {
		/*
		 * If the vnode that we are about to sync is no longer
		 * associated with this mount point, start over.
		 */
		if (vp->v_mount != mp)
			goto loop;
		if (VOP_ISLOCKED(vp) || vp->v_dirtyblkhd.lh_first == NULL)
			continue;
		if (vget(vp, LK_EXCLUSIVE, p))
			goto loop;
		error = VOP_FSYNC(vp, cred, waitfor, p);
		if (error)
			allerror = error;
		vput(vp);
	}
	return (allerror);
}

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

	return (EOPNOTSUPP);
}

/*
 * At this point, this should never happen
 */
/* ARGSUSED */
int
nfs_fhtovp(mp, fhp, nam, vpp, exflagsp, credanonp)
	register struct mount *mp;
	struct fid *fhp;
	struct mbuf *nam;
	struct vnode **vpp;
	int *exflagsp;
	struct ucred **credanonp;
{

	return (EINVAL);
}

/*
 * Vnode pointer to File handle, should never happen either
 */
/* ARGSUSED */
int
nfs_vptofh(vp, fhp)
	struct vnode *vp;
	struct fid *fhp;
{

	return (EINVAL);
}

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

	return (0);
}

/*
 * Do operations associated with quotas, not supported
 */
/* ARGSUSED */
int
nfs_quotactl(mp, cmd, uid, arg, p)
	struct mount *mp;
	int cmd;
	uid_t uid;
	caddr_t arg;
	struct proc *p;
{

	return (EOPNOTSUPP);
}

/*
 * Do that sysctl thang...
 */
static int
nfs_sysctl(int *name, u_int namelen, void *oldp, size_t *oldlenp, void *newp,
	   size_t newlen, struct proc *p)
{
	int rv;

	/*
	 * All names at this level are terminal.
	 */
	if(namelen > 1)
		return ENOTDIR;	/* overloaded */

	switch(name[0]) {
	case NFS_NFSSTATS:
		if(!oldp) {
			*oldlenp = sizeof nfsstats;
			return 0;
		}

		if(*oldlenp < sizeof nfsstats) {
			*oldlenp = sizeof nfsstats;
			return ENOMEM;
		}

		rv = copyout(&nfsstats, oldp, sizeof nfsstats);
		if(rv) return rv;

		if(newp && newlen != sizeof nfsstats)
			return EINVAL;

		if(newp) {
			return copyin(newp, &nfsstats, sizeof nfsstats);
		}
		return 0;

	default:
		return EOPNOTSUPP;
	}
}