usr/src/sys/dev/vn.c

/*
 * Copyright (c) 1988 University of Utah.
 * Copyright (c) 1990 The Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * the Systems Programming Group of the University of Utah Computer
 * Science Department.
 *
 * %sccs.include.redist.c%
 *
 * from: Utah $Hdr: vn.c 1.1 91/04/30$
 *
 *	@(#)vn.c	7.8 (Berkeley) %G%
 */

/*
 * Vnode disk driver.
 *
 * Block/character interface to a vnode.  Allows one to treat a file
 * as a disk (e.g. build a filesystem in it, mount it, etc.).
 *
 * NOTE 1: This uses the VOP_BMAP/VOP_STRATEGY interface to the vnode
 * instead of a simple VOP_RDWR.  We do this to avoid distorting the
 * local buffer cache.
 *
 * NOTE 2: There is a security issue involved with this driver.
 * Once mounted all access to the contents of the "mapped" file via
 * the special file is controlled by the permissions on the special
 * file, the protection of the mapped file is ignored (effectively,
 * by using root credentials in all transactions).
 */
#include "vn.h"
#if NVN > 0

#include "sys/param.h"
#include "sys/systm.h"
#include "sys/namei.h"
#include "sys/proc.h"
#include "sys/errno.h"
#include "sys/dkstat.h"
#include "sys/buf.h"
#include "sys/malloc.h"
#include "sys/ioctl.h"
#include "sys/mount.h"
#include "sys/vnode.h"
#include "sys/specdev.h"
#include "sys/file.h"
#include "sys/uio.h"

#include "vnioctl.h"

#ifdef DEBUG
int vndebug = 0x00;
#define VDB_FOLLOW	0x01
#define VDB_INIT	0x02
#define VDB_IO		0x04
#endif

struct	buf vnbuf[NVN];
struct	buf vntab[NVN];

#define b_cylin	b_resid

#define	vnunit(x)	((minor(x) >> 3) & 0x7)	/* for consistency */

#define	getvnbuf()	\
	((struct buf *)malloc(sizeof(struct buf), M_DEVBUF, M_WAITOK))
#define putvnbuf(bp)	\
	free((caddr_t)(bp), M_DEVBUF)

struct vn_softc {
	int		 sc_flags;	/* flags */
	size_t		 sc_size;	/* size of vn */
	struct vnode	*sc_vp;		/* vnode */
	struct ucred	*sc_cred;	/* credentials */
	int		 sc_maxactive;	/* max # of active requests */
} vn_softc[NVN];

/* sc_flags */
#define	VNF_ALIVE	0x01
#define VNF_INITED	0x02

int
vnopen(dev, flags, mode, p)
	dev_t dev;
	int flags, mode;
	struct proc *p;
{
	int unit = vnunit(dev);

#ifdef DEBUG
	if (vndebug & VDB_FOLLOW)
		printf("vnopen(%x, %x, %x, %x)\n", dev, flags, mode, p);
#endif
	if (unit >= NVN)
		return(ENXIO);
	return(0);
}

/*
 * Break the request into bsize pieces and submit using VOP_BMAP/VOP_STRATEGY.
 * Note that this driver can only be used for swapping over NFS on the hp
 * since nfs_strategy on the vax cannot handle u-areas and page tables.
 */
vnstrategy(bp)
	register struct buf *bp;
{
	int unit = vnunit(bp->b_dev);
	register struct vn_softc *vn = &vn_softc[unit];
	register struct buf *nbp;
	register int bn, bsize, resid;
	register caddr_t addr;
	int sz, flags;
	extern int vniodone();

#ifdef DEBUG
	if (vndebug & VDB_FOLLOW)
		printf("vnstrategy(%x): unit %d\n", bp, unit);
#endif
	if ((vn->sc_flags & VNF_INITED) == 0) {
		bp->b_error = ENXIO;
		bp->b_flags |= B_ERROR;
		biodone(bp);
		return;
	}
	bn = bp->b_blkno;
	sz = howmany(bp->b_bcount, DEV_BSIZE);
	bp->b_resid = bp->b_bcount;
	if (bn < 0 || bn + sz > vn->sc_size) {
		if (bn != vn->sc_size) {
			bp->b_error = EINVAL;
			bp->b_flags |= B_ERROR;
		}
		biodone(bp);
		return;
	}
	bn = dbtob(bn);
	bsize = vn->sc_vp->v_mount->mnt_stat.f_iosize;
	addr = bp->b_un.b_addr;
	flags = bp->b_flags | B_CALL;
	for (resid = bp->b_resid; resid; resid -= sz) {
		struct vnode *vp;
		daddr_t nbn;
		int off, s;

		nbp = getvnbuf();
		off = bn % bsize;
		sz = MIN(bsize - off, resid);
		(void) VOP_BMAP(vn->sc_vp, bn / bsize, &vp, &nbn);
#ifdef DEBUG
		if (vndebug & VDB_IO)
			printf("vnstrategy: vp %x/%x bn %x/%x\n",
			       vn->sc_vp, vp, bn, nbn);
#endif
		nbp->b_flags = flags;
		nbp->b_bcount = sz;
		nbp->b_bufsize = bp->b_bufsize;
		nbp->b_error = 0;
		if (vp->v_type == VBLK || vp->v_type == VCHR)
			nbp->b_dev = vp->v_rdev;
		else
			nbp->b_dev = NODEV;
		nbp->b_un.b_addr = addr;
		nbp->b_blkno = nbn + btodb(off);
		nbp->b_proc = bp->b_proc;
		nbp->b_iodone = vniodone;
		nbp->b_vp = vp;
		nbp->b_pfcent = (int) bp;	/* XXX */
		/*
		 * Just sort by block number
		 */
		nbp->b_cylin = nbp->b_blkno;
		s = splbio();
		disksort(&vntab[unit], nbp);
		if (vntab[unit].b_active < vn->sc_maxactive) {
			vntab[unit].b_active++;
			vnstart(unit);
		}
		splx(s);
		bn += sz;
		addr += sz;
	}
}

/*
 * Feed requests sequentially.
 * We do it this way to keep from flooding NFS servers if we are connected
 * to an NFS file.  This places the burden on the client rather than the
 * server.
 */
vnstart(unit)
{
	register struct vn_softc *vn = &vn_softc[unit];
	register struct buf *bp;

	/*
	 * Dequeue now since lower level strategy routine might
	 * queue using same links
	 */
	bp = vntab[unit].b_actf;
	vntab[unit].b_actf = bp->b_actf;
#ifdef DEBUG
	if (vndebug & VDB_IO)
		printf("vnstart(%d): bp %x vp %x blkno %x addr %x cnt %x\n",
		       unit, bp, bp->b_vp, bp->b_blkno, bp->b_un.b_addr,
		       bp->b_bcount);
#endif
	VOP_STRATEGY(bp);
}

vniodone(bp)
	register struct buf *bp;
{
	register struct buf *pbp = (struct buf *)bp->b_pfcent;	/* XXX */
	register int unit = vnunit(pbp->b_dev);
	int s;

	s = splbio();
#ifdef DEBUG
	if (vndebug & VDB_IO)
		printf("vniodone(%d): bp %x vp %x blkno %x addr %x cnt %x\n",
		       unit, bp, bp->b_vp, bp->b_blkno, bp->b_un.b_addr,
		       bp->b_bcount);
#endif
	if (bp->b_error) {
#ifdef DEBUG
		if (vndebug & VDB_IO)
			printf("vniodone: bp %x error %d\n", bp, bp->b_error);
#endif
		pbp->b_flags |= B_ERROR;
		pbp->b_error = biowait(bp);
	}
	pbp->b_resid -= bp->b_bcount;
	putvnbuf(bp);
	if (pbp->b_resid == 0) {
#ifdef DEBUG
		if (vndebug & VDB_IO)
			printf("vniodone: pbp %x iodone\n", pbp);
#endif
		biodone(pbp);
	}
	if (vntab[unit].b_actf)
		vnstart(unit);
	else
		vntab[unit].b_active--;
	splx(s);
}

vnread(dev, uio, flags, p)
	dev_t dev;
	struct uio *uio;
	int flags;
	struct proc *p;
{
	register int unit = vnunit(dev);

#ifdef DEBUG
	if (vndebug & VDB_FOLLOW)
		printf("vnread(%x, %x, %x, %x)\n", dev, uio, flags, p);
#endif
	return(physio(vnstrategy, &vnbuf[unit], dev, B_READ, minphys, uio));
}

vnwrite(dev, uio, flags, p)
	dev_t dev;
	struct uio *uio;
	int flags;
	struct proc *p;
{
	register int unit = vnunit(dev);

#ifdef DEBUG
	if (vndebug & VDB_FOLLOW)
		printf("vnwrite(%x, %x, %x, %x)\n", dev, uio, flags, p);
#endif
	return(physio(vnstrategy, &vnbuf[unit], dev, B_WRITE, minphys, uio));
}

/* ARGSUSED */
vnioctl(dev, cmd, data, flag, p)
	dev_t dev;
	u_long cmd;
	caddr_t data;
	int flag;
	struct proc *p;
{
	int unit = vnunit(dev);
	register struct vn_softc *vn;
	struct vn_ioctl *vio;
	struct vattr vattr;
	struct nameidata nd;
	int error;

#ifdef DEBUG
	if (vndebug & VDB_FOLLOW)
		printf("vnioctl(%x, %x, %x, %x, %x): unit %d\n",
		       dev, cmd, data, flag, p, unit);
#endif
	error = suser(p->p_ucred, &p->p_acflag);
	if (error)
		return (error);
	if (unit >= NVN)
		return (ENXIO);

	vn = &vn_softc[unit];
	vio = (struct vn_ioctl *)data;
	switch (cmd) {

	case VNIOCSET:
		if (vn->sc_flags & VNF_INITED)
			return(EBUSY);
		/*
		 * Always open for read and write.
		 * This is probably bogus, but it lets vn_open()
		 * weed out directories, sockets, etc. so we don't
		 * have to worry about them.
		 */
		NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, vio->vn_file, p);
		if (error = vn_open(&nd, FREAD|FWRITE, 0))
			return(error);
		if (error = VOP_GETATTR(nd.ni_vp, &vattr, p->p_ucred, p)) {
			VOP_UNLOCK(nd.ni_vp);
			(void) vn_close(nd.ni_vp, FREAD|FWRITE, p->p_ucred, p);
			return(error);
		}
		VOP_UNLOCK(nd.ni_vp);
		vn->sc_vp = nd.ni_vp;
		vn->sc_size = btodb(vattr.va_size);	/* note truncation */
		if (error = vnsetcred(vn, p->p_ucred)) {
			(void) vn_close(vn->sc_vp, FREAD|FWRITE, p->p_ucred, p);
			return(error);
		}
		vnthrottle(vn, vn->sc_vp);
		vio->vn_size = dbtob(vn->sc_size);
		vn->sc_flags |= VNF_INITED;
#ifdef DEBUG
		if (vndebug & VDB_INIT)
			printf("vnioctl: SET vp %x size %x\n",
			       vn->sc_vp, vn->sc_size);
#endif
		break;

	case VNIOCCLR:
		if ((vn->sc_flags & VNF_INITED) == 0)
			return(ENXIO);
		vnclear(vn);
#ifdef DEBUG
		if (vndebug & VDB_INIT)
			printf("vnioctl: CLRed\n");
#endif
		break;

	default:
		return(ENXIO);
	}
	return(0);
}

/*
 * Duplicate the current processes' credentials.  Since we are called only
 * as the result of a SET ioctl and only root can do that, any future access
 * to this "disk" is essentially as root.  Note that credentials may change
 * if some other uid can write directly to the mapped file (NFS).
 */
vnsetcred(vn, cred)
	register struct vn_softc *vn;
	struct ucred cred;
{
	struct uio auio;
	struct iovec aiov;
	char tmpbuf[DEV_BSIZE];

	vn->sc_cred = crdup(cred);
	/* XXX: Horrible kludge to establish credentials for NFS */
	aiov.iov_base = tmpbuf;
	aiov.iov_len = MIN(DEV_BSIZE, dbtob(vn->sc_size));
	auio.uio_iov = &aiov;
	auio.uio_iovcnt = 1;
	auio.uio_offset = 0;
	auio.uio_rw = UIO_READ;
	auio.uio_segflg = UIO_SYSSPACE;
	auio.uio_resid = aiov.iov_len;
	return(VOP_READ(vn->sc_vp, &auio, 0, vn->sc_cred));
}

/*
 * Set maxactive based on FS type
 */
vnthrottle(vn, vp)
	register struct vn_softc *vn;
	struct vnode *vp;
{
	extern struct vnodeops ufs_vnodeops, nfsv2_vnodeops;

	if (vp->v_op == &nfsv2_vnodeops)
		vn->sc_maxactive = 2;
	else
		vn->sc_maxactive = 8;

	if (vn->sc_maxactive < 1)
		vn->sc_maxactive = 1;
}

vnshutdown()
{
	register struct vn_softc *vn;

	for (vn = &vn_softc[0]; vn < &vn_softc[NVN]; vn++)
		if (vn->sc_flags & VNF_INITED)
			vnclear(vn);
}

vnclear(vn)
	register struct vn_softc *vn;
{
	register struct vnode *vp = vn->sc_vp;
	struct proc *p = curproc;		/* XXX */

#ifdef DEBUG
	if (vndebug & VDB_FOLLOW)
		printf("vnclear(%x): vp %x\n", vp);
#endif
	vn->sc_flags &= ~VNF_INITED;
	if (vp == (struct vnode *)0)
		panic("vnioctl: null vp");
#if 0
	/* XXX - this doesn't work right now */
	(void) VOP_FSYNC(vp, 0, vn->sc_cred, MNT_WAIT, p);
#endif
	(void) vn_close(vp, FREAD|FWRITE, vn->sc_cred, p);
	crfree(vn->sc_cred);
	vn->sc_vp = (struct vnode *)0;
	vn->sc_cred = (struct ucred *)0;
	vn->sc_size = 0;
}

vnsize(dev)
	dev_t dev;
{
	int unit = vnunit(dev);
	register struct vn_softc *vn = &vn_softc[unit];

	if (unit >= NVN || (vn->sc_flags & VNF_INITED) == 0)
		return(-1);
	return(vn->sc_size);
}

vndump(dev)
{
	return(ENXIO);
}
#endif
Commit	Line	Data
	1	/*
	2	* Copyright (c) 1988 University of Utah.
	3	* Copyright (c) 1990 The Regents of the University of California.
	4	* All rights reserved.
	5	*
	6	* This code is derived from software contributed to Berkeley by
	7	* the Systems Programming Group of the University of Utah Computer
	8	* Science Department.
	9	*
	10	* %sccs.include.redist.c%
	11	*
	12	* from: Utah $Hdr: vn.c 1.1 91/04/30$
	13	*
	14	* @(#)vn.c 7.8 (Berkeley) %G%
	15	*/
	16
	17	/*
	18	* Vnode disk driver.
	19	*
	20	* Block/character interface to a vnode. Allows one to treat a file
	21	* as a disk (e.g. build a filesystem in it, mount it, etc.).
	22	*
	23	* NOTE 1: This uses the VOP_BMAP/VOP_STRATEGY interface to the vnode
	24	* instead of a simple VOP_RDWR. We do this to avoid distorting the
	25	* local buffer cache.
	26	*
	27	* NOTE 2: There is a security issue involved with this driver.
	28	* Once mounted all access to the contents of the "mapped" file via
	29	* the special file is controlled by the permissions on the special
	30	* file, the protection of the mapped file is ignored (effectively,
	31	* by using root credentials in all transactions).
	32	*/
	33	#include "vn.h"
	34	#if NVN > 0
	35
	36	#include "sys/param.h"
	37	#include "sys/systm.h"
	38	#include "sys/namei.h"
	39	#include "sys/proc.h"
	40	#include "sys/errno.h"
	41	#include "sys/dkstat.h"
	42	#include "sys/buf.h"
	43	#include "sys/malloc.h"
	44	#include "sys/ioctl.h"
	45	#include "sys/mount.h"
	46	#include "sys/vnode.h"
	47	#include "sys/specdev.h"
	48	#include "sys/file.h"
	49	#include "sys/uio.h"
	50
	51	#include "vnioctl.h"
	52
	53	#ifdef DEBUG
	54	int vndebug = 0x00;
	55	#define VDB_FOLLOW 0x01
	56	#define VDB_INIT 0x02
	57	#define VDB_IO 0x04
	58	#endif
	59
	60	struct buf vnbuf[NVN];
	61	struct buf vntab[NVN];
	62
	63	#define b_cylin b_resid
	64
	65	#define vnunit(x) ((minor(x) >> 3) & 0x7) /* for consistency */
	66
	67	#define getvnbuf() \
	68	((struct buf *)malloc(sizeof(struct buf), M_DEVBUF, M_WAITOK))
	69	#define putvnbuf(bp) \
	70	free((caddr_t)(bp), M_DEVBUF)
	71
	72	struct vn_softc {
	73	int sc_flags; /* flags */
	74	size_t sc_size; /* size of vn */
	75	struct vnode sc_vp; / vnode */
	76	struct ucred sc_cred; / credentials */
	77	int sc_maxactive; /* max # of active requests */
	78	} vn_softc[NVN];
	79
	80	/* sc_flags */
	81	#define VNF_ALIVE 0x01
	82	#define VNF_INITED 0x02
	83
	84	int
	85	vnopen(dev, flags, mode, p)
	86	dev_t dev;
	87	int flags, mode;
	88	struct proc *p;
	89	{
	90	int unit = vnunit(dev);
	91
	92	#ifdef DEBUG
	93	if (vndebug & VDB_FOLLOW)
	94	printf("vnopen(%x, %x, %x, %x)\n", dev, flags, mode, p);
	95	#endif
	96	if (unit >= NVN)
	97	return(ENXIO);
	98	return(0);
	99	}
	100
	101	/*
	102	* Break the request into bsize pieces and submit using VOP_BMAP/VOP_STRATEGY.
	103	* Note that this driver can only be used for swapping over NFS on the hp
	104	* since nfs_strategy on the vax cannot handle u-areas and page tables.
	105	*/
	106	vnstrategy(bp)
	107	register struct buf *bp;
	108	{
	109	int unit = vnunit(bp->b_dev);
	110	register struct vn_softc *vn = &vn_softc[unit];
	111	register struct buf *nbp;
	112	register int bn, bsize, resid;
	113	register caddr_t addr;
	114	int sz, flags;
	115	extern int vniodone();
	116
	117	#ifdef DEBUG
	118	if (vndebug & VDB_FOLLOW)
	119	printf("vnstrategy(%x): unit %d\n", bp, unit);
	120	#endif
	121	if ((vn->sc_flags & VNF_INITED) == 0) {
	122	bp->b_error = ENXIO;
	123	bp->b_flags \|= B_ERROR;
	124	biodone(bp);
	125	return;
	126	}
	127	bn = bp->b_blkno;
	128	sz = howmany(bp->b_bcount, DEV_BSIZE);
	129	bp->b_resid = bp->b_bcount;
	130	if (bn < 0 \|\| bn + sz > vn->sc_size) {
	131	if (bn != vn->sc_size) {
	132	bp->b_error = EINVAL;
	133	bp->b_flags \|= B_ERROR;
	134	}
	135	biodone(bp);
	136	return;
	137	}
	138	bn = dbtob(bn);
	139	bsize = vn->sc_vp->v_mount->mnt_stat.f_iosize;
	140	addr = bp->b_un.b_addr;
	141	flags = bp->b_flags \| B_CALL;
	142	for (resid = bp->b_resid; resid; resid -= sz) {
	143	struct vnode *vp;
	144	daddr_t nbn;
	145	int off, s;
	146
	147	nbp = getvnbuf();
	148	off = bn % bsize;
	149	sz = MIN(bsize - off, resid);
	150	(void) VOP_BMAP(vn->sc_vp, bn / bsize, &vp, &nbn);
	151	#ifdef DEBUG
	152	if (vndebug & VDB_IO)
	153	printf("vnstrategy: vp %x/%x bn %x/%x\n",
	154	vn->sc_vp, vp, bn, nbn);
	155	#endif
	156	nbp->b_flags = flags;
	157	nbp->b_bcount = sz;
	158	nbp->b_bufsize = bp->b_bufsize;
	159	nbp->b_error = 0;
	160	if (vp->v_type == VBLK \|\| vp->v_type == VCHR)
	161	nbp->b_dev = vp->v_rdev;
	162	else
	163	nbp->b_dev = NODEV;
	164	nbp->b_un.b_addr = addr;
	165	nbp->b_blkno = nbn + btodb(off);
	166	nbp->b_proc = bp->b_proc;
	167	nbp->b_iodone = vniodone;
	168	nbp->b_vp = vp;
	169	nbp->b_pfcent = (int) bp; /* XXX */
	170	/*
	171	* Just sort by block number
	172	*/
	173	nbp->b_cylin = nbp->b_blkno;
	174	s = splbio();
	175	disksort(&vntab[unit], nbp);
	176	if (vntab[unit].b_active < vn->sc_maxactive) {
	177	vntab[unit].b_active++;
	178	vnstart(unit);
	179	}
	180	splx(s);
	181	bn += sz;
	182	addr += sz;
	183	}
	184	}
	185
	186	/*
	187	* Feed requests sequentially.
	188	* We do it this way to keep from flooding NFS servers if we are connected
	189	* to an NFS file. This places the burden on the client rather than the
	190	* server.
	191	*/
	192	vnstart(unit)
	193	{
	194	register struct vn_softc *vn = &vn_softc[unit];
	195	register struct buf *bp;
	196
	197	/*
	198	* Dequeue now since lower level strategy routine might
	199	* queue using same links
	200	*/
	201	bp = vntab[unit].b_actf;
	202	vntab[unit].b_actf = bp->b_actf;
	203	#ifdef DEBUG
	204	if (vndebug & VDB_IO)
	205	printf("vnstart(%d): bp %x vp %x blkno %x addr %x cnt %x\n",
	206	unit, bp, bp->b_vp, bp->b_blkno, bp->b_un.b_addr,
	207	bp->b_bcount);
	208	#endif
	209	VOP_STRATEGY(bp);
	210	}
	211
	212	vniodone(bp)
	213	register struct buf *bp;
	214	{
	215	register struct buf pbp = (struct buf )bp->b_pfcent; /* XXX */
	216	register int unit = vnunit(pbp->b_dev);
	217	int s;
	218
	219	s = splbio();
	220	#ifdef DEBUG
	221	if (vndebug & VDB_IO)
	222	printf("vniodone(%d): bp %x vp %x blkno %x addr %x cnt %x\n",
	223	unit, bp, bp->b_vp, bp->b_blkno, bp->b_un.b_addr,
	224	bp->b_bcount);
	225	#endif
	226	if (bp->b_error) {
	227	#ifdef DEBUG
	228	if (vndebug & VDB_IO)
	229	printf("vniodone: bp %x error %d\n", bp, bp->b_error);
	230	#endif
	231	pbp->b_flags \|= B_ERROR;
	232	pbp->b_error = biowait(bp);
	233	}
	234	pbp->b_resid -= bp->b_bcount;
	235	putvnbuf(bp);
	236	if (pbp->b_resid == 0) {
	237	#ifdef DEBUG
	238	if (vndebug & VDB_IO)
	239	printf("vniodone: pbp %x iodone\n", pbp);
	240	#endif
	241	biodone(pbp);
	242	}
	243	if (vntab[unit].b_actf)
	244	vnstart(unit);
	245	else
	246	vntab[unit].b_active--;
	247	splx(s);
	248	}
	249
	250	vnread(dev, uio, flags, p)
	251	dev_t dev;
	252	struct uio *uio;
	253	int flags;
	254	struct proc *p;
	255	{
	256	register int unit = vnunit(dev);
	257
	258	#ifdef DEBUG
	259	if (vndebug & VDB_FOLLOW)
	260	printf("vnread(%x, %x, %x, %x)\n", dev, uio, flags, p);
	261	#endif
	262	return(physio(vnstrategy, &vnbuf[unit], dev, B_READ, minphys, uio));
	263	}
	264
	265	vnwrite(dev, uio, flags, p)
	266	dev_t dev;
	267	struct uio *uio;
	268	int flags;
	269	struct proc *p;
	270	{
	271	register int unit = vnunit(dev);
	272
	273	#ifdef DEBUG
	274	if (vndebug & VDB_FOLLOW)
	275	printf("vnwrite(%x, %x, %x, %x)\n", dev, uio, flags, p);
	276	#endif
	277	return(physio(vnstrategy, &vnbuf[unit], dev, B_WRITE, minphys, uio));
	278	}
	279
	280	/* ARGSUSED */
	281	vnioctl(dev, cmd, data, flag, p)
	282	dev_t dev;
	283	u_long cmd;
	284	caddr_t data;
	285	int flag;
	286	struct proc *p;
	287	{
	288	int unit = vnunit(dev);
	289	register struct vn_softc *vn;
	290	struct vn_ioctl *vio;
	291	struct vattr vattr;
	292	struct nameidata nd;
	293	int error;
	294
	295	#ifdef DEBUG
	296	if (vndebug & VDB_FOLLOW)
	297	printf("vnioctl(%x, %x, %x, %x, %x): unit %d\n",
	298	dev, cmd, data, flag, p, unit);
	299	#endif
	300	error = suser(p->p_ucred, &p->p_acflag);
	301	if (error)
	302	return (error);
	303	if (unit >= NVN)
	304	return (ENXIO);
	305
	306	vn = &vn_softc[unit];
	307	vio = (struct vn_ioctl *)data;
	308	switch (cmd) {
	309
	310	case VNIOCSET:
	311	if (vn->sc_flags & VNF_INITED)
	312	return(EBUSY);
	313	/*
	314	* Always open for read and write.
	315	* This is probably bogus, but it lets vn_open()
	316	* weed out directories, sockets, etc. so we don't
	317	* have to worry about them.
	318	*/
	319	NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, vio->vn_file, p);
	320	if (error = vn_open(&nd, FREAD\|FWRITE, 0))
	321	return(error);
	322	if (error = VOP_GETATTR(nd.ni_vp, &vattr, p->p_ucred, p)) {
	323	VOP_UNLOCK(nd.ni_vp);
	324	(void) vn_close(nd.ni_vp, FREAD\|FWRITE, p->p_ucred, p);
	325	return(error);
	326	}
	327	VOP_UNLOCK(nd.ni_vp);
	328	vn->sc_vp = nd.ni_vp;
	329	vn->sc_size = btodb(vattr.va_size); /* note truncation */
	330	if (error = vnsetcred(vn, p->p_ucred)) {
	331	(void) vn_close(vn->sc_vp, FREAD\|FWRITE, p->p_ucred, p);
	332	return(error);
	333	}
	334	vnthrottle(vn, vn->sc_vp);
	335	vio->vn_size = dbtob(vn->sc_size);
	336	vn->sc_flags \|= VNF_INITED;
	337	#ifdef DEBUG
	338	if (vndebug & VDB_INIT)
	339	printf("vnioctl: SET vp %x size %x\n",
	340	vn->sc_vp, vn->sc_size);
	341	#endif
	342	break;
	343
	344	case VNIOCCLR:
	345	if ((vn->sc_flags & VNF_INITED) == 0)
	346	return(ENXIO);
	347	vnclear(vn);
	348	#ifdef DEBUG
	349	if (vndebug & VDB_INIT)
	350	printf("vnioctl: CLRed\n");
	351	#endif
	352	break;
	353
	354	default:
	355	return(ENXIO);
	356	}
	357	return(0);
	358	}
	359
	360	/*
	361	* Duplicate the current processes' credentials. Since we are called only
	362	* as the result of a SET ioctl and only root can do that, any future access
	363	* to this "disk" is essentially as root. Note that credentials may change
	364	* if some other uid can write directly to the mapped file (NFS).
	365	*/
	366	vnsetcred(vn, cred)
	367	register struct vn_softc *vn;
	368	struct ucred cred;
	369	{
	370	struct uio auio;
	371	struct iovec aiov;
	372	char tmpbuf[DEV_BSIZE];
	373
	374	vn->sc_cred = crdup(cred);
	375	/* XXX: Horrible kludge to establish credentials for NFS */
	376	aiov.iov_base = tmpbuf;
	377	aiov.iov_len = MIN(DEV_BSIZE, dbtob(vn->sc_size));
	378	auio.uio_iov = &aiov;
	379	auio.uio_iovcnt = 1;
	380	auio.uio_offset = 0;
	381	auio.uio_rw = UIO_READ;
	382	auio.uio_segflg = UIO_SYSSPACE;
	383	auio.uio_resid = aiov.iov_len;
	384	return(VOP_READ(vn->sc_vp, &auio, 0, vn->sc_cred));
	385	}
	386
	387	/*
	388	* Set maxactive based on FS type
	389	*/
	390	vnthrottle(vn, vp)
	391	register struct vn_softc *vn;
	392	struct vnode *vp;
	393	{
	394	extern struct vnodeops ufs_vnodeops, nfsv2_vnodeops;
	395
	396	if (vp->v_op == &nfsv2_vnodeops)
	397	vn->sc_maxactive = 2;
	398	else
	399	vn->sc_maxactive = 8;
	400
	401	if (vn->sc_maxactive < 1)
	402	vn->sc_maxactive = 1;
	403	}
	404
	405	vnshutdown()
	406	{
	407	register struct vn_softc *vn;
	408
	409	for (vn = &vn_softc[0]; vn < &vn_softc[NVN]; vn++)
	410	if (vn->sc_flags & VNF_INITED)
	411	vnclear(vn);
	412	}
	413
	414	vnclear(vn)
	415	register struct vn_softc *vn;
	416	{
	417	register struct vnode *vp = vn->sc_vp;
	418	struct proc p = curproc; / XXX */
	419
	420	#ifdef DEBUG
	421	if (vndebug & VDB_FOLLOW)
	422	printf("vnclear(%x): vp %x\n", vp);
	423	#endif
	424	vn->sc_flags &= ~VNF_INITED;
	425	if (vp == (struct vnode *)0)
	426	panic("vnioctl: null vp");
	427	#if 0
	428	/* XXX - this doesn't work right now */
	429	(void) VOP_FSYNC(vp, 0, vn->sc_cred, MNT_WAIT, p);
	430	#endif
	431	(void) vn_close(vp, FREAD\|FWRITE, vn->sc_cred, p);
	432	crfree(vn->sc_cred);
	433	vn->sc_vp = (struct vnode *)0;
	434	vn->sc_cred = (struct ucred *)0;
	435	vn->sc_size = 0;
	436	}
	437
	438	vnsize(dev)
	439	dev_t dev;
	440	{
	441	int unit = vnunit(dev);
	442	register struct vn_softc *vn = &vn_softc[unit];
	443
	444	if (unit >= NVN \|\| (vn->sc_flags & VNF_INITED) == 0)
	445	return(-1);
	446	return(vn->sc_size);
	447	}
	448
	449	vndump(dev)
	450	{
	451	return(ENXIO);
	452	}
	453	#endif