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spec_vnops.c revision 1.42
      1 /*	$NetBSD: spec_vnops.c,v 1.42 1998/08/18 06:30:09 thorpej Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1989, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. All advertising materials mentioning features or use of this software
     16  *    must display the following acknowledgement:
     17  *	This product includes software developed by the University of
     18  *	California, Berkeley and its contributors.
     19  * 4. Neither the name of the University nor the names of its contributors
     20  *    may be used to endorse or promote products derived from this software
     21  *    without specific prior written permission.
     22  *
     23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     33  * SUCH DAMAGE.
     34  *
     35  *	@(#)spec_vnops.c	8.15 (Berkeley) 7/14/95
     36  */
     37 
     38 #include <sys/param.h>
     39 #include <sys/proc.h>
     40 #include <sys/systm.h>
     41 #include <sys/kernel.h>
     42 #include <sys/conf.h>
     43 #include <sys/buf.h>
     44 #include <sys/mount.h>
     45 #include <sys/namei.h>
     46 #include <sys/vnode.h>
     47 #include <sys/stat.h>
     48 #include <sys/errno.h>
     49 #include <sys/ioctl.h>
     50 #include <sys/file.h>
     51 #include <sys/disklabel.h>
     52 #include <sys/lockf.h>
     53 
     54 #include <miscfs/genfs/genfs.h>
     55 #include <miscfs/specfs/specdev.h>
     56 
     57 /* symbolic sleep message strings for devices */
     58 const char	devopn[] = "devopn";
     59 const char	devio[] = "devio";
     60 const char	devwait[] = "devwait";
     61 const char	devin[] = "devin";
     62 const char	devout[] = "devout";
     63 const char	devioc[] = "devioc";
     64 const char	devcls[] = "devcls";
     65 
     66 int (**spec_vnodeop_p) __P((void *));
     67 struct vnodeopv_entry_desc spec_vnodeop_entries[] = {
     68 	{ &vop_default_desc, vn_default_error },
     69 	{ &vop_lookup_desc, spec_lookup },		/* lookup */
     70 	{ &vop_create_desc, spec_create },		/* create */
     71 	{ &vop_mknod_desc, spec_mknod },		/* mknod */
     72 	{ &vop_open_desc, spec_open },			/* open */
     73 	{ &vop_close_desc, spec_close },		/* close */
     74 	{ &vop_access_desc, spec_access },		/* access */
     75 	{ &vop_getattr_desc, spec_getattr },		/* getattr */
     76 	{ &vop_setattr_desc, spec_setattr },		/* setattr */
     77 	{ &vop_read_desc, spec_read },			/* read */
     78 	{ &vop_write_desc, spec_write },		/* write */
     79 	{ &vop_lease_desc, spec_lease_check },		/* lease */
     80 	{ &vop_ioctl_desc, spec_ioctl },		/* ioctl */
     81 	{ &vop_poll_desc, spec_poll },			/* poll */
     82 	{ &vop_revoke_desc, spec_revoke },		/* revoke */
     83 	{ &vop_mmap_desc, spec_mmap },			/* mmap */
     84 	{ &vop_fsync_desc, spec_fsync },		/* fsync */
     85 	{ &vop_seek_desc, spec_seek },			/* seek */
     86 	{ &vop_remove_desc, spec_remove },		/* remove */
     87 	{ &vop_link_desc, spec_link },			/* link */
     88 	{ &vop_rename_desc, spec_rename },		/* rename */
     89 	{ &vop_mkdir_desc, spec_mkdir },		/* mkdir */
     90 	{ &vop_rmdir_desc, spec_rmdir },		/* rmdir */
     91 	{ &vop_symlink_desc, spec_symlink },		/* symlink */
     92 	{ &vop_readdir_desc, spec_readdir },		/* readdir */
     93 	{ &vop_readlink_desc, spec_readlink },		/* readlink */
     94 	{ &vop_abortop_desc, spec_abortop },		/* abortop */
     95 	{ &vop_inactive_desc, spec_inactive },		/* inactive */
     96 	{ &vop_reclaim_desc, spec_reclaim },		/* reclaim */
     97 	{ &vop_lock_desc, spec_lock },			/* lock */
     98 	{ &vop_unlock_desc, spec_unlock },		/* unlock */
     99 	{ &vop_bmap_desc, spec_bmap },			/* bmap */
    100 	{ &vop_strategy_desc, spec_strategy },		/* strategy */
    101 	{ &vop_print_desc, spec_print },		/* print */
    102 	{ &vop_islocked_desc, spec_islocked },		/* islocked */
    103 	{ &vop_pathconf_desc, spec_pathconf },		/* pathconf */
    104 	{ &vop_advlock_desc, spec_advlock },		/* advlock */
    105 	{ &vop_blkatoff_desc, spec_blkatoff },		/* blkatoff */
    106 	{ &vop_valloc_desc, spec_valloc },		/* valloc */
    107 	{ &vop_vfree_desc, spec_vfree },		/* vfree */
    108 	{ &vop_truncate_desc, spec_truncate },		/* truncate */
    109 	{ &vop_update_desc, spec_update },		/* update */
    110 	{ &vop_bwrite_desc, spec_bwrite },		/* bwrite */
    111 	{ (struct vnodeop_desc*)NULL, (int(*) __P((void *)))NULL }
    112 };
    113 struct vnodeopv_desc spec_vnodeop_opv_desc =
    114 	{ &spec_vnodeop_p, spec_vnodeop_entries };
    115 
    116 /*
    117  * Trivial lookup routine that always fails.
    118  */
    119 int
    120 spec_lookup(v)
    121 	void *v;
    122 {
    123 	struct vop_lookup_args /* {
    124 		struct vnode *a_dvp;
    125 		struct vnode **a_vpp;
    126 		struct componentname *a_cnp;
    127 	} */ *ap = v;
    128 
    129 	*ap->a_vpp = NULL;
    130 	return (ENOTDIR);
    131 }
    132 
    133 /*
    134  * Open a special file.
    135  */
    136 /* ARGSUSED */
    137 int
    138 spec_open(v)
    139 	void *v;
    140 {
    141 	struct vop_open_args /* {
    142 		struct vnode *a_vp;
    143 		int  a_mode;
    144 		struct ucred *a_cred;
    145 		struct proc *a_p;
    146 	} */ *ap = v;
    147 	struct proc *p = ap->a_p;
    148 	struct vnode *bvp, *vp = ap->a_vp;
    149 	dev_t bdev, dev = (dev_t)vp->v_rdev;
    150 	register int maj = major(dev);
    151 	int error;
    152 
    153 	/*
    154 	 * Don't allow open if fs is mounted -nodev.
    155 	 */
    156 	if (vp->v_mount && (vp->v_mount->mnt_flag & MNT_NODEV))
    157 		return (ENXIO);
    158 
    159 	switch (vp->v_type) {
    160 
    161 	case VCHR:
    162 		if ((u_int)maj >= nchrdev)
    163 			return (ENXIO);
    164 		if (ap->a_cred != FSCRED && (ap->a_mode & FWRITE)) {
    165 			/*
    166 			 * When running in very secure mode, do not allow
    167 			 * opens for writing of any disk character devices.
    168 			 */
    169 			if (securelevel >= 2 && cdevsw[maj].d_type == D_DISK)
    170 				return (EPERM);
    171 			/*
    172 			 * When running in secure mode, do not allow opens
    173 			 * for writing of /dev/mem, /dev/kmem, or character
    174 			 * devices whose corresponding block devices are
    175 			 * currently mounted.
    176 			 */
    177 			if (securelevel >= 1) {
    178 				if ((bdev = chrtoblk(dev)) != (dev_t)NODEV &&
    179 				    vfinddev(bdev, VBLK, &bvp) &&
    180 				    bvp->v_usecount > 0 &&
    181 				    (error = vfs_mountedon(bvp)))
    182 					return (error);
    183 				if (iskmemdev(dev))
    184 					return (EPERM);
    185 			}
    186 		}
    187 		if (cdevsw[maj].d_type == D_TTY)
    188 			vp->v_flag |= VISTTY;
    189 		VOP_UNLOCK(vp, 0);
    190 		error = (*cdevsw[maj].d_open)(dev, ap->a_mode, S_IFCHR, p);
    191 		vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
    192 		return (error);
    193 
    194 	case VBLK:
    195 		if ((u_int)maj >= nblkdev)
    196 			return (ENXIO);
    197 		/*
    198 		 * When running in very secure mode, do not allow
    199 		 * opens for writing of any disk block devices.
    200 		 */
    201 		if (securelevel >= 2 && ap->a_cred != FSCRED &&
    202 		    (ap->a_mode & FWRITE) && bdevsw[maj].d_type == D_DISK)
    203 			return (EPERM);
    204 		/*
    205 		 * Do not allow opens of block devices that are
    206 		 * currently mounted.
    207 		 */
    208 		if ((error = vfs_mountedon(vp)) != 0)
    209 			return (error);
    210 		return ((*bdevsw[maj].d_open)(dev, ap->a_mode, S_IFBLK, p));
    211 	case VNON:
    212 	case VLNK:
    213 	case VDIR:
    214 	case VREG:
    215 	case VBAD:
    216 	case VFIFO:
    217 	case VSOCK:
    218 		break;
    219 	}
    220 	return (0);
    221 }
    222 
    223 /*
    224  * Vnode op for read
    225  */
    226 /* ARGSUSED */
    227 int
    228 spec_read(v)
    229 	void *v;
    230 {
    231 	struct vop_read_args /* {
    232 		struct vnode *a_vp;
    233 		struct uio *a_uio;
    234 		int  a_ioflag;
    235 		struct ucred *a_cred;
    236 	} */ *ap = v;
    237 	register struct vnode *vp = ap->a_vp;
    238 	register struct uio *uio = ap->a_uio;
    239  	struct proc *p = uio->uio_procp;
    240 	struct buf *bp;
    241 	daddr_t bn, nextbn;
    242 	long bsize, bscale, ssize;
    243 	struct partinfo dpart;
    244 	int n, on, majordev;
    245 	int (*ioctl) __P((dev_t, u_long, caddr_t, int, struct proc *));
    246 	int error = 0;
    247 
    248 #ifdef DIAGNOSTIC
    249 	if (uio->uio_rw != UIO_READ)
    250 		panic("spec_read mode");
    251 	if (uio->uio_segflg == UIO_USERSPACE && uio->uio_procp != curproc)
    252 		panic("spec_read proc");
    253 #endif
    254 	if (uio->uio_resid == 0)
    255 		return (0);
    256 
    257 	switch (vp->v_type) {
    258 
    259 	case VCHR:
    260 		VOP_UNLOCK(vp, 0);
    261 		error = (*cdevsw[major(vp->v_rdev)].d_read)
    262 			(vp->v_rdev, uio, ap->a_ioflag);
    263 		vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
    264 		return (error);
    265 
    266 	case VBLK:
    267 		if (uio->uio_offset < 0)
    268 			return (EINVAL);
    269 		bsize = BLKDEV_IOSIZE;
    270 		ssize = DEV_BSIZE;
    271 		if ((majordev = major(vp->v_rdev)) < nblkdev &&
    272 		    (ioctl = bdevsw[majordev].d_ioctl) != NULL &&
    273 		    (*ioctl)(vp->v_rdev, DIOCGPART, (caddr_t)&dpart, FREAD, p) == 0) {
    274 			if (dpart.part->p_fstype == FS_BSDFFS &&
    275 			    dpart.part->p_frag != 0 && dpart.part->p_fsize != 0)
    276 				bsize = dpart.part->p_frag *
    277 				    dpart.part->p_fsize;
    278 			if (dpart.disklab->d_secsize != 0)
    279 				ssize = dpart.disklab->d_secsize;
    280 		}
    281 		bscale = bsize / ssize;
    282 		do {
    283 			bn = (uio->uio_offset / ssize) &~ (bscale - 1);
    284 			on = uio->uio_offset % bsize;
    285 			n = min((unsigned)(bsize - on), uio->uio_resid);
    286 			if (vp->v_lastr + bscale == bn) {
    287 				nextbn = bn + bscale;
    288 				error = breadn(vp, bn, (int)bsize, &nextbn,
    289 					(int *)&bsize, 1, NOCRED, &bp);
    290 			} else
    291 				error = bread(vp, bn, (int)bsize, NOCRED, &bp);
    292 			vp->v_lastr = bn;
    293 			n = min(n, bsize - bp->b_resid);
    294 			if (error) {
    295 				brelse(bp);
    296 				return (error);
    297 			}
    298 			error = uiomove((char *)bp->b_data + on, n, uio);
    299 			brelse(bp);
    300 		} while (error == 0 && uio->uio_resid > 0 && n != 0);
    301 		return (error);
    302 
    303 	default:
    304 		panic("spec_read type");
    305 	}
    306 	/* NOTREACHED */
    307 }
    308 
    309 /*
    310  * Vnode op for write
    311  */
    312 /* ARGSUSED */
    313 int
    314 spec_write(v)
    315 	void *v;
    316 {
    317 	struct vop_write_args /* {
    318 		struct vnode *a_vp;
    319 		struct uio *a_uio;
    320 		int  a_ioflag;
    321 		struct ucred *a_cred;
    322 	} */ *ap = v;
    323 	register struct vnode *vp = ap->a_vp;
    324 	register struct uio *uio = ap->a_uio;
    325 	struct proc *p = uio->uio_procp;
    326 	struct buf *bp;
    327 	daddr_t bn;
    328 	long bsize, bscale, ssize;
    329 	struct partinfo dpart;
    330 	int n, on, majordev;
    331 	int (*ioctl) __P((dev_t, u_long, caddr_t, int, struct proc *));
    332 	int error = 0;
    333 
    334 #ifdef DIAGNOSTIC
    335 	if (uio->uio_rw != UIO_WRITE)
    336 		panic("spec_write mode");
    337 	if (uio->uio_segflg == UIO_USERSPACE && uio->uio_procp != curproc)
    338 		panic("spec_write proc");
    339 #endif
    340 
    341 	switch (vp->v_type) {
    342 
    343 	case VCHR:
    344 		VOP_UNLOCK(vp, 0);
    345 		error = (*cdevsw[major(vp->v_rdev)].d_write)
    346 			(vp->v_rdev, uio, ap->a_ioflag);
    347 		vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
    348 		return (error);
    349 
    350 	case VBLK:
    351 		if (uio->uio_resid == 0)
    352 			return (0);
    353 		if (uio->uio_offset < 0)
    354 			return (EINVAL);
    355 		bsize = BLKDEV_IOSIZE;
    356 		ssize = DEV_BSIZE;
    357 		if ((majordev = major(vp->v_rdev)) < nblkdev &&
    358 		    (ioctl = bdevsw[majordev].d_ioctl) != NULL &&
    359 		    (*ioctl)(vp->v_rdev, DIOCGPART, (caddr_t)&dpart, FREAD, p) == 0) {
    360 			if (dpart.part->p_fstype == FS_BSDFFS &&
    361 			    dpart.part->p_frag != 0 && dpart.part->p_fsize != 0)
    362 				bsize = dpart.part->p_frag *
    363 				    dpart.part->p_fsize;
    364 			if (dpart.disklab->d_secsize != 0)
    365 				ssize = dpart.disklab->d_secsize;
    366 		}
    367 		bscale = bsize / ssize;
    368 		do {
    369 			bn = (uio->uio_offset / ssize) &~ (bscale - 1);
    370 			on = uio->uio_offset % bsize;
    371 			n = min((unsigned)(bsize - on), uio->uio_resid);
    372 			if (n == bsize)
    373 				bp = getblk(vp, bn, bsize, 0, 0);
    374 			else
    375 				error = bread(vp, bn, bsize, NOCRED, &bp);
    376 			n = min(n, bsize - bp->b_resid);
    377 			if (error) {
    378 				brelse(bp);
    379 				return (error);
    380 			}
    381 			error = uiomove((char *)bp->b_data + on, n, uio);
    382 			if (n + on == bsize)
    383 				bawrite(bp);
    384 			else
    385 				bdwrite(bp);
    386 		} while (error == 0 && uio->uio_resid > 0 && n != 0);
    387 		return (error);
    388 
    389 	default:
    390 		panic("spec_write type");
    391 	}
    392 	/* NOTREACHED */
    393 }
    394 
    395 /*
    396  * Device ioctl operation.
    397  */
    398 /* ARGSUSED */
    399 int
    400 spec_ioctl(v)
    401 	void *v;
    402 {
    403 	struct vop_ioctl_args /* {
    404 		struct vnode *a_vp;
    405 		u_long a_command;
    406 		caddr_t  a_data;
    407 		int  a_fflag;
    408 		struct ucred *a_cred;
    409 		struct proc *a_p;
    410 	} */ *ap = v;
    411 	dev_t dev = ap->a_vp->v_rdev;
    412 	int maj = major(dev);
    413 
    414 	switch (ap->a_vp->v_type) {
    415 
    416 	case VCHR:
    417 		return ((*cdevsw[maj].d_ioctl)(dev, ap->a_command, ap->a_data,
    418 		    ap->a_fflag, ap->a_p));
    419 
    420 	case VBLK:
    421 		if (ap->a_command == 0 && (long)ap->a_data == B_TAPE) {
    422 			if (bdevsw[maj].d_type == D_TAPE)
    423 				return (0);
    424 			else
    425 				return (1);
    426 		}
    427 		return ((*bdevsw[maj].d_ioctl)(dev, ap->a_command, ap->a_data,
    428 		   ap->a_fflag, ap->a_p));
    429 
    430 	default:
    431 		panic("spec_ioctl");
    432 		/* NOTREACHED */
    433 	}
    434 }
    435 
    436 /* ARGSUSED */
    437 int
    438 spec_poll(v)
    439 	void *v;
    440 {
    441 	struct vop_poll_args /* {
    442 		struct vnode *a_vp;
    443 		int a_events;
    444 		struct proc *a_p;
    445 	} */ *ap = v;
    446 	register dev_t dev;
    447 
    448 	switch (ap->a_vp->v_type) {
    449 
    450 	case VCHR:
    451 		dev = ap->a_vp->v_rdev;
    452 		return (*cdevsw[major(dev)].d_poll)(dev, ap->a_events, ap->a_p);
    453 
    454 	default:
    455 		return (genfs_poll(v));
    456 	}
    457 }
    458 /*
    459  * Synch buffers associated with a block device
    460  */
    461 /* ARGSUSED */
    462 int
    463 spec_fsync(v)
    464 	void *v;
    465 {
    466 	struct vop_fsync_args /* {
    467 		struct vnode *a_vp;
    468 		struct ucred *a_cred;
    469 		int  a_flags;
    470 		struct proc *a_p;
    471 	} */ *ap = v;
    472 	register struct vnode *vp = ap->a_vp;
    473 
    474 	if (vp->v_type == VBLK)
    475 		vflushbuf(vp, (ap->a_flags & FSYNC_WAIT) != 0);
    476 	return (0);
    477 }
    478 
    479 /*
    480  * Just call the device strategy routine
    481  */
    482 int
    483 spec_strategy(v)
    484 	void *v;
    485 {
    486 	struct vop_strategy_args /* {
    487 		struct buf *a_bp;
    488 	} */ *ap = v;
    489 
    490 	(*bdevsw[major(ap->a_bp->b_dev)].d_strategy)(ap->a_bp);
    491 	return (0);
    492 }
    493 
    494 int
    495 spec_inactive(v)
    496 	void *v;
    497 {
    498 	struct vop_inactive_args /* {
    499 		struct vnode *a_vp;
    500 		struct proc *a_p;
    501 	} */ *ap = v;
    502 
    503 	VOP_UNLOCK(ap->a_vp, 0);
    504 	return (0);
    505 }
    506 
    507 /*
    508  * This is a noop, simply returning what one has been given.
    509  */
    510 int
    511 spec_bmap(v)
    512 	void *v;
    513 {
    514 	struct vop_bmap_args /* {
    515 		struct vnode *a_vp;
    516 		daddr_t  a_bn;
    517 		struct vnode **a_vpp;
    518 		daddr_t *a_bnp;
    519 		int *a_runp;
    520 	} */ *ap = v;
    521 
    522 	if (ap->a_vpp != NULL)
    523 		*ap->a_vpp = ap->a_vp;
    524 	if (ap->a_bnp != NULL)
    525 		*ap->a_bnp = ap->a_bn;
    526 	if (ap->a_runp != NULL)
    527 		*ap->a_runp = 0;
    528 	return (0);
    529 }
    530 
    531 /*
    532  * Device close routine
    533  */
    534 /* ARGSUSED */
    535 int
    536 spec_close(v)
    537 	void *v;
    538 {
    539 	struct vop_close_args /* {
    540 		struct vnode *a_vp;
    541 		int  a_fflag;
    542 		struct ucred *a_cred;
    543 		struct proc *a_p;
    544 	} */ *ap = v;
    545 	register struct vnode *vp = ap->a_vp;
    546 	dev_t dev = vp->v_rdev;
    547 	int (*devclose) __P((dev_t, int, int, struct proc *));
    548 	int mode, error;
    549 
    550 	switch (vp->v_type) {
    551 
    552 	case VCHR:
    553 		/*
    554 		 * Hack: a tty device that is a controlling terminal
    555 		 * has a reference from the session structure.
    556 		 * We cannot easily tell that a character device is
    557 		 * a controlling terminal, unless it is the closing
    558 		 * process' controlling terminal.  In that case,
    559 		 * if the reference count is 2 (this last descriptor
    560 		 * plus the session), release the reference from the session.
    561 		 */
    562 		if (vcount(vp) == 2 && ap->a_p &&
    563 		    vp == ap->a_p->p_session->s_ttyvp) {
    564 			vrele(vp);
    565 			ap->a_p->p_session->s_ttyvp = NULL;
    566 		}
    567 		/*
    568 		 * If the vnode is locked, then we are in the midst
    569 		 * of forcably closing the device, otherwise we only
    570 		 * close on last reference.
    571 		 */
    572 		if (vcount(vp) > 1 && (vp->v_flag & VXLOCK) == 0)
    573 			return (0);
    574 		devclose = cdevsw[major(dev)].d_close;
    575 		mode = S_IFCHR;
    576 		break;
    577 
    578 	case VBLK:
    579 		/*
    580 		 * On last close of a block device (that isn't mounted)
    581 		 * we must invalidate any in core blocks, so that
    582 		 * we can, for instance, change floppy disks.
    583 		 */
    584 		error = vinvalbuf(vp, V_SAVE, ap->a_cred, ap->a_p, 0, 0);
    585 		if (error)
    586 			return (error);
    587 		/*
    588 		 * We do not want to really close the device if it
    589 		 * is still in use unless we are trying to close it
    590 		 * forcibly. Since every use (buffer, vnode, swap, cmap)
    591 		 * holds a reference to the vnode, and because we mark
    592 		 * any other vnodes that alias this device, when the
    593 		 * sum of the reference counts on all the aliased
    594 		 * vnodes descends to one, we are on last close.
    595 		 */
    596 		if (vcount(vp) > 1 && (vp->v_flag & VXLOCK) == 0)
    597 			return (0);
    598 		devclose = bdevsw[major(dev)].d_close;
    599 		mode = S_IFBLK;
    600 		break;
    601 
    602 	default:
    603 		panic("spec_close: not special");
    604 	}
    605 
    606 	return ((*devclose)(dev, ap->a_fflag, mode, ap->a_p));
    607 }
    608 
    609 /*
    610  * Print out the contents of a special device vnode.
    611  */
    612 int
    613 spec_print(v)
    614 	void *v;
    615 {
    616 	struct vop_print_args /* {
    617 		struct vnode *a_vp;
    618 	} */ *ap = v;
    619 
    620 	printf("tag VT_NON, dev %d, %d\n", major(ap->a_vp->v_rdev),
    621 	    minor(ap->a_vp->v_rdev));
    622 	return 0;
    623 }
    624 
    625 /*
    626  * Return POSIX pathconf information applicable to special devices.
    627  */
    628 int
    629 spec_pathconf(v)
    630 	void *v;
    631 {
    632 	struct vop_pathconf_args /* {
    633 		struct vnode *a_vp;
    634 		int a_name;
    635 		register_t *a_retval;
    636 	} */ *ap = v;
    637 
    638 	switch (ap->a_name) {
    639 	case _PC_LINK_MAX:
    640 		*ap->a_retval = LINK_MAX;
    641 		return (0);
    642 	case _PC_MAX_CANON:
    643 		*ap->a_retval = MAX_CANON;
    644 		return (0);
    645 	case _PC_MAX_INPUT:
    646 		*ap->a_retval = MAX_INPUT;
    647 		return (0);
    648 	case _PC_PIPE_BUF:
    649 		*ap->a_retval = PIPE_BUF;
    650 		return (0);
    651 	case _PC_CHOWN_RESTRICTED:
    652 		*ap->a_retval = 1;
    653 		return (0);
    654 	case _PC_VDISABLE:
    655 		*ap->a_retval = _POSIX_VDISABLE;
    656 		return (0);
    657 	case _PC_SYNC_IO:
    658 		*ap->a_retval = 1;
    659 		return (0);
    660 	default:
    661 		return (EINVAL);
    662 	}
    663 	/* NOTREACHED */
    664 }
    665 
    666 /*
    667  * Advisory record locking support.
    668  */
    669 int
    670 spec_advlock(v)
    671 	void *v;
    672 {
    673 	struct vop_advlock_args /* {
    674 		struct vnode *a_vp;
    675 		caddr_t a_id;
    676 		int a_op;
    677 		struct flock *a_fl;
    678 		int a_flags;
    679 	} */ *ap = v;
    680 	register struct vnode *vp = ap->a_vp;
    681 
    682 	return (lf_advlock(&vp->v_speclockf, (off_t)0, ap->a_id, ap->a_op,
    683 	                   ap->a_fl, ap->a_flags));
    684 }
    685