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filecore_vfsops.c revision 1.81.2.1
      1 /*	$NetBSD: filecore_vfsops.c,v 1.81.2.1 2017/04/27 05:36:37 pgoyette Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 1994 The Regents of the University of California.
      5  * 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. Neither the name of the University nor the names of its contributors
     16  *    may be used to endorse or promote products derived from this software
     17  *    without specific prior written permission.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     29  * SUCH DAMAGE.
     30  *
     31  *	filecore_vfsops.c	1.1	1998/6/26
     32  */
     33 
     34 /*-
     35  * Copyright (c) 1998 Andrew McMurry
     36  *
     37  * Redistribution and use in source and binary forms, with or without
     38  * modification, are permitted provided that the following conditions
     39  * are met:
     40  * 1. Redistributions of source code must retain the above copyright
     41  *    notice, this list of conditions and the following disclaimer.
     42  * 2. Redistributions in binary form must reproduce the above copyright
     43  *    notice, this list of conditions and the following disclaimer in the
     44  *    documentation and/or other materials provided with the distribution.
     45  * 3. All advertising materials mentioning features or use of this software
     46  *    must display the following acknowledgement:
     47  *	This product includes software developed by the University of
     48  *	California, Berkeley and its contributors.
     49  * 4. Neither the name of the University nor the names of its contributors
     50  *    may be used to endorse or promote products derived from this software
     51  *    without specific prior written permission.
     52  *
     53  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     54  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     55  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     56  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     57  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     58  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     59  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     60  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     61  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     62  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     63  * SUCH DAMAGE.
     64  *
     65  *	filecore_vfsops.c	1.1	1998/6/26
     66  */
     67 
     68 #include <sys/cdefs.h>
     69 __KERNEL_RCSID(0, "$NetBSD: filecore_vfsops.c,v 1.81.2.1 2017/04/27 05:36:37 pgoyette Exp $");
     70 
     71 #if defined(_KERNEL_OPT)
     72 #include "opt_compat_netbsd.h"
     73 #endif
     74 
     75 #include <sys/param.h>
     76 #include <sys/systm.h>
     77 #include <sys/namei.h>
     78 #include <sys/proc.h>
     79 #include <sys/vnode.h>
     80 #include <miscfs/genfs/genfs.h>
     81 #include <miscfs/specfs/specdev.h>
     82 #include <sys/mount.h>
     83 #include <sys/buf.h>
     84 #include <sys/file.h>
     85 #include <sys/device.h>
     86 #include <sys/errno.h>
     87 #include <sys/pool.h>
     88 #include <sys/conf.h>
     89 #include <sys/sysctl.h>
     90 #include <sys/kauth.h>
     91 #include <sys/module.h>
     92 
     93 #include <fs/filecorefs/filecore.h>
     94 #include <fs/filecorefs/filecore_extern.h>
     95 #include <fs/filecorefs/filecore_node.h>
     96 #include <fs/filecorefs/filecore_mount.h>
     97 
     98 MODULE(MODULE_CLASS_VFS, filecore, NULL);
     99 
    100 static struct sysctllog *filecore_sysctl_log;
    101 
    102 extern const struct vnodeopv_desc filecore_vnodeop_opv_desc;
    103 
    104 const struct vnodeopv_desc * const filecore_vnodeopv_descs[] = {
    105 	&filecore_vnodeop_opv_desc,
    106 	NULL,
    107 };
    108 
    109 struct vfsops filecore_vfsops = {
    110 	.vfs_name = MOUNT_FILECORE,
    111 	.vfs_min_mount_data = sizeof (struct filecore_args),
    112 	.vfs_mount = filecore_mount,
    113 	.vfs_start = filecore_start,
    114 	.vfs_unmount = filecore_unmount,
    115 	.vfs_root = filecore_root,
    116 	.vfs_quotactl = (void *)eopnotsupp,
    117 	.vfs_statvfs = filecore_statvfs,
    118 	.vfs_sync = filecore_sync,
    119 	.vfs_vget = filecore_vget,
    120 	.vfs_loadvnode = filecore_loadvnode,
    121 	.vfs_fhtovp = filecore_fhtovp,
    122 	.vfs_vptofh = filecore_vptofh,
    123 	.vfs_init = filecore_init,
    124 	.vfs_reinit = filecore_reinit,
    125 	.vfs_done = filecore_done,
    126 	.vfs_snapshot = (void *)eopnotsupp,
    127 	.vfs_extattrctl = vfs_stdextattrctl,
    128 	.vfs_suspendctl = genfs_suspendctl,
    129 	.vfs_renamelock_enter = genfs_renamelock_enter,
    130 	.vfs_renamelock_exit = genfs_renamelock_exit,
    131 	.vfs_fsync = (void *)eopnotsupp,
    132 	.vfs_opv_descs = filecore_vnodeopv_descs
    133 };
    134 
    135 static int
    136 filecore_modcmd(modcmd_t cmd, void *arg)
    137 {
    138 	int error;
    139 
    140 	switch (cmd) {
    141 	case MODULE_CMD_INIT:
    142 		error = vfs_attach(&filecore_vfsops);
    143 		if (error != 0)
    144 			break;
    145 		sysctl_createv(&filecore_sysctl_log, 0, NULL, NULL,
    146 			       CTLFLAG_PERMANENT,
    147 			       CTLTYPE_NODE, "filecore",
    148 			       SYSCTL_DESCR("Acorn FILECORE file system"),
    149 			       NULL, 0, NULL, 0,
    150 			       CTL_VFS, 19, CTL_EOL);
    151 		/*
    152 		 * XXX the "19" above could be dynamic, thereby eliminating
    153 		 * one more instance of the "number to vfs" mapping problem,
    154 		 * but "19" is the order as taken from sys/mount.h
    155 		 */
    156 		break;
    157 	case MODULE_CMD_FINI:
    158 		error = vfs_detach(&filecore_vfsops);
    159 		if (error != 0)
    160 			break;
    161 		sysctl_teardown(&filecore_sysctl_log);
    162 		break;
    163 	default:
    164 		error = ENOTTY;
    165 		break;
    166 	}
    167 
    168 	return (error);
    169 }
    170 
    171 /*
    172  * Called by vfs_mountroot when iso is going to be mounted as root.
    173  *
    174  * Name is updated by mount(8) after booting.
    175  */
    176 
    177 static int filecore_mountfs(struct vnode *devvp, struct mount *mp,
    178 		struct lwp *l, struct filecore_args *argp);
    179 
    180 #if 0
    181 int
    182 filecore_mountroot(void)
    183 {
    184 	struct mount *mp;
    185 	extern struct vnode *rootvp;
    186 	struct proc *p = curproc;	/* XXX */
    187 	int error;
    188 	struct filecore_args args;
    189 
    190 	if (device_class(root_device) != DV_DISK)
    191 		return (ENODEV);
    192 
    193 	/*
    194 	 * Get vnodes for swapdev and rootdev.
    195 	 */
    196 	if (bdevvp(rootdev, &rootvp))
    197 		panic("filecore_mountroot: can't setup rootvp");
    198 
    199 	if ((error = vfs_rootmountalloc(MOUNT_FILECORE, "root_device", &mp)) != 0)
    200 		return (error);
    201 
    202 	args.flags = FILECOREMNT_ROOT;
    203 	if ((error = filecore_mountfs(rootvp, mp, p, &args)) != 0) {
    204 		vfs_unbusy(mp);
    205 		vfs_rele(mp);
    206 		return (error);
    207 	}
    208 	mountlist_append(mp);
    209 	(void)filecore_statvfs(mp, &mp->mnt_stat, p);
    210 	vfs_unbusy(mp);
    211 	return (0);
    212 }
    213 #endif
    214 
    215 /*
    216  * VFS Operations.
    217  *
    218  * mount system call
    219  */
    220 int
    221 filecore_mount(struct mount *mp, const char *path, void *data, size_t *data_len)
    222 {
    223 	struct lwp *l = curlwp;
    224 	struct vnode *devvp;
    225 	struct filecore_args *args = data;
    226 	int error;
    227 	struct filecore_mnt *fcmp = NULL;
    228 	const struct bdevsw *bdev;
    229 
    230 	if (args == NULL)
    231 		return EINVAL;
    232 	if (*data_len < sizeof *args)
    233 		return EINVAL;
    234 
    235 	if (mp->mnt_flag & MNT_GETARGS) {
    236 		fcmp = VFSTOFILECORE(mp);
    237 		if (fcmp == NULL)
    238 			return EIO;
    239 		args->flags = fcmp->fc_mntflags;
    240 		args->uid = fcmp->fc_uid;
    241 		args->gid = fcmp->fc_gid;
    242 		args->fspec = NULL;
    243 		*data_len = sizeof *args;
    244 		return 0;
    245 	}
    246 
    247 	if ((mp->mnt_flag & MNT_RDONLY) == 0)
    248 		return (EROFS);
    249 
    250 	if ((mp->mnt_flag & MNT_UPDATE) && args->fspec == NULL)
    251 		return EINVAL;
    252 
    253 	/*
    254 	 * Not an update, or updating the name: look up the name
    255 	 * and verify that it refers to a sensible block device.
    256 	 */
    257 	error = namei_simple_user(args->fspec,
    258 				NSM_FOLLOW_NOEMULROOT, &devvp);
    259 	if (error != 0)
    260 		return (error);
    261 
    262 	if (devvp->v_type != VBLK) {
    263 		vrele(devvp);
    264 		return ENOTBLK;
    265 	}
    266 	if ((bdev = bdevsw_lookup_acquire(devvp->v_rdev)) == NULL) {
    267 		vrele(devvp);
    268 		return ENXIO;
    269 	}
    270 	/*
    271 	 * If mount by non-root, then verify that user has necessary
    272 	 * permissions on the device.
    273 	 */
    274 	vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY);
    275 	error = kauth_authorize_system(l->l_cred, KAUTH_SYSTEM_MOUNT,
    276 	    KAUTH_REQ_SYSTEM_MOUNT_DEVICE, mp, devvp, KAUTH_ARG(VREAD));
    277 	VOP_UNLOCK(devvp);
    278 	if (error) {
    279 		bdevsw_release(bdev);
    280 		vrele(devvp);
    281 		return (error);
    282 	}
    283 	if ((mp->mnt_flag & MNT_UPDATE) == 0)
    284 		error = filecore_mountfs(devvp, mp, l, args);
    285 	else {
    286 		fcmp = VFSTOFILECORE(mp);
    287 		if (devvp != fcmp->fc_devvp)
    288 			error = EINVAL;	/* needs translation */
    289 		else
    290 			vrele(devvp);
    291 	}
    292 	if (error) {
    293 		bdevsw_release(bdev);
    294 		vrele(devvp);
    295 		return error;
    296 	}
    297 	fcmp = VFSTOFILECORE(mp);
    298 	error = set_statvfs_info(path, UIO_USERSPACE, args->fspec,
    299 	    UIO_USERSPACE, mp->mnt_op->vfs_name, mp, l);
    300 	bdevsw_release(bdev);
    301 	return error;
    302 }
    303 
    304 /*
    305  * Common code for mount and mountroot
    306  */
    307 static int
    308 filecore_mountfs(struct vnode *devvp, struct mount *mp, struct lwp *l, struct filecore_args *argp)
    309 {
    310 	struct filecore_mnt *fcmp = (struct filecore_mnt *)0;
    311 	struct buf *bp = NULL;
    312 	dev_t dev = devvp->v_rdev;
    313 	int error = EINVAL;
    314 	int ronly = (mp->mnt_flag & MNT_RDONLY) != 0;
    315 	struct filecore_disc_record *fcdr;
    316 	unsigned map;
    317 	unsigned log2secsize;
    318 
    319 	if (!ronly)
    320 		return EROFS;
    321 
    322 	if ((error = vinvalbuf(devvp, V_SAVE, l->l_cred, l, 0, 0)) != 0)
    323 		return (error);
    324 
    325 	vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY);
    326 	error = VOP_OPEN(devvp, ronly ? FREAD : FREAD|FWRITE, FSCRED);
    327 	VOP_UNLOCK(devvp);
    328 	if (error)
    329 		return error;
    330 
    331 	/* Read the filecore boot block to check FS validity and to find the map */
    332 	error = bread(devvp, FILECORE_BOOTBLOCK_BLKN,
    333 			   FILECORE_BOOTBLOCK_SIZE, 0, &bp);
    334 #ifdef FILECORE_DEBUG_BR
    335 		printf("bread(%p, %x, %d, CRED, %p)=%d\n", devvp,
    336 		       FILECORE_BOOTBLOCK_BLKN, FILECORE_BOOTBLOCK_SIZE,
    337 		       bp, error);
    338 #endif
    339 	if (error != 0)
    340 		goto out;
    341 
    342 	KASSERT(bp != NULL);
    343 	if (filecore_bbchecksum(bp->b_data) != 0) {
    344 		error = EINVAL;
    345 		goto out;
    346 	}
    347 	fcdr = (struct filecore_disc_record *)((char *)(bp->b_data) +
    348 	    FILECORE_BB_DISCREC);
    349 	map = ((((8 << fcdr->log2secsize) - fcdr->zone_spare)
    350 	    * (fcdr->nzones / 2) - 8 * FILECORE_DISCREC_SIZE)
    351 	    << fcdr->log2bpmb) >> fcdr->log2secsize;
    352 	log2secsize = fcdr->log2secsize;
    353 #ifdef FILECORE_DEBUG_BR
    354 	printf("brelse(%p) vf1\n", bp);
    355 #endif
    356 	brelse(bp, BC_AGE);
    357 	bp = NULL;
    358 
    359 	/* Read the bootblock in the map */
    360 	error = bread(devvp, map, 1 << log2secsize, 0, &bp);
    361 #ifdef FILECORE_DEBUG_BR
    362 		printf("bread(%p, %x, %d, CRED, %p)=%d\n", devvp,
    363 		       map, 1 << log2secsize, bp, error);
    364 #endif
    365 	if (error != 0)
    366 		goto out;
    367        	fcdr = (struct filecore_disc_record *)((char *)(bp->b_data) + 4);
    368 	fcmp = kmem_zalloc(sizeof(*fcmp), KM_SLEEP);
    369 	if (fcdr->log2bpmb > fcdr->log2secsize)
    370 		fcmp->log2bsize = fcdr->log2bpmb;
    371 	else	fcmp->log2bsize = fcdr->log2secsize;
    372 	fcmp->blksize = 1 << fcmp->log2bsize;
    373 	memcpy(&fcmp->drec, fcdr, sizeof(*fcdr));
    374 	fcmp->map = map;
    375 	fcmp->idspz = ((8 << fcdr->log2secsize) - fcdr->zone_spare)
    376 	    / (fcdr->idlen + 1);
    377 	fcmp->mask = (1 << fcdr->idlen) - 1;
    378 	if (fcdr->big_flag & 1) {
    379 		fcmp->nblks = ((((u_int64_t)fcdr->disc_size_2) << 32)
    380 		    + fcdr->disc_size) / fcmp->blksize;
    381 	} else {
    382 		fcmp->nblks=fcdr->disc_size / fcmp->blksize;
    383 	}
    384 
    385 #ifdef FILECORE_DEBUG_BR
    386 	printf("brelse(%p) vf2\n", bp);
    387 #endif
    388 	brelse(bp, BC_AGE);
    389 	bp = NULL;
    390 
    391 	mp->mnt_data = fcmp;
    392 	mp->mnt_stat.f_fsidx.__fsid_val[0] = (long)dev;
    393 	mp->mnt_stat.f_fsidx.__fsid_val[1] = makefstype(MOUNT_FILECORE);
    394 	mp->mnt_stat.f_fsid = mp->mnt_stat.f_fsidx.__fsid_val[0];
    395 	mp->mnt_stat.f_namemax = 10;
    396 	mp->mnt_flag |= MNT_LOCAL;
    397 	mp->mnt_dev_bshift = fcdr->log2secsize;
    398 	mp->mnt_fs_bshift = fcmp->log2bsize;
    399 
    400 	fcmp->fc_mountp = mp;
    401 	fcmp->fc_dev = dev;
    402 	fcmp->fc_devvp = devvp;
    403 	fcmp->fc_mntflags = argp->flags;
    404 	if (argp->flags & FILECOREMNT_USEUID) {
    405 		fcmp->fc_uid = kauth_cred_getuid(l->l_cred);
    406 		fcmp->fc_gid = kauth_cred_getgid(l->l_cred);
    407 	} else {
    408 		fcmp->fc_uid = argp->uid;
    409 		fcmp->fc_gid = argp->gid;
    410 	}
    411 
    412 	return 0;
    413 out:
    414 	if (bp) {
    415 #ifdef FILECORE_DEBUG_BR
    416 		printf("brelse(%p) vf3\n", bp);
    417 #endif
    418 		brelse(bp, 0);
    419 	}
    420 	vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY);
    421 	(void)VOP_CLOSE(devvp, ronly ? FREAD : FREAD|FWRITE, NOCRED);
    422 	VOP_UNLOCK(devvp);
    423 	return error;
    424 }
    425 
    426 /*
    427  * Make a filesystem operational.
    428  * Nothing to do at the moment.
    429  */
    430 /* ARGSUSED */
    431 int
    432 filecore_start(struct mount *mp, int flags)
    433 {
    434 	return 0;
    435 }
    436 
    437 /*
    438  * unmount system call
    439  */
    440 int
    441 filecore_unmount(struct mount *mp, int mntflags)
    442 {
    443 	struct filecore_mnt *fcmp;
    444 	int error, flags = 0;
    445 
    446 	if (mntflags & MNT_FORCE)
    447 		flags |= FORCECLOSE;
    448 	if ((error = vflush(mp, NULLVP, flags)) != 0)
    449 		return (error);
    450 
    451 	fcmp = VFSTOFILECORE(mp);
    452 
    453 	if (fcmp->fc_devvp->v_type != VBAD)
    454 		spec_node_setmountedfs(fcmp->fc_devvp, NULL);
    455 	vn_lock(fcmp->fc_devvp, LK_EXCLUSIVE | LK_RETRY);
    456 	error = VOP_CLOSE(fcmp->fc_devvp, FREAD, NOCRED);
    457 	vput(fcmp->fc_devvp);
    458 	kmem_free(fcmp, sizeof(*fcmp));
    459 	mp->mnt_data = NULL;
    460 	mp->mnt_flag &= ~MNT_LOCAL;
    461 	return (error);
    462 }
    463 
    464 /*
    465  * Return root of a filesystem
    466  */
    467 int
    468 filecore_root(struct mount *mp, struct vnode **vpp)
    469 {
    470 	struct vnode *nvp;
    471         int error;
    472 
    473         if ((error = VFS_VGET(mp, FILECORE_ROOTINO, &nvp)) != 0)
    474                 return (error);
    475         *vpp = nvp;
    476         return (0);
    477 }
    478 
    479 /*
    480  * Get file system statistics.
    481  */
    482 int
    483 filecore_statvfs(struct mount *mp, struct statvfs *sbp)
    484 {
    485 	struct filecore_mnt *fcmp = VFSTOFILECORE(mp);
    486 
    487 	sbp->f_bsize = fcmp->blksize;
    488 	sbp->f_frsize = sbp->f_bsize; /* XXX */
    489 	sbp->f_iosize = sbp->f_bsize;	/* XXX */
    490 	sbp->f_blocks = fcmp->nblks;
    491 	sbp->f_bfree = 0; /* total free blocks */
    492 	sbp->f_bavail = 0; /* blocks free for non superuser */
    493 	sbp->f_bresvd = 0; /* reserved blocks */
    494 	sbp->f_files =  0; /* total files */
    495 	sbp->f_ffree = 0; /* free file nodes for non superuser */
    496 	sbp->f_favail = 0; /* free file nodes */
    497 	sbp->f_fresvd = 0; /* reserved file nodes */
    498 	copy_statvfs_info(sbp, mp);
    499 	return 0;
    500 }
    501 
    502 /* ARGSUSED */
    503 int
    504 filecore_sync(struct mount *mp, int waitfor, kauth_cred_t cred)
    505 {
    506 	return (0);
    507 }
    508 
    509 /*
    510  * File handle to vnode
    511  *
    512  * Have to be really careful about stale file handles:
    513  * - check that the inode number is in range
    514  * - call iget() to get the locked inode
    515  * - check for an unallocated inode (i_mode == 0)
    516  * - check that the generation number matches
    517  */
    518 
    519 struct ifid {
    520 	ushort		ifid_len;
    521 	ushort		ifid_pad;
    522 	u_int32_t	ifid_ino;
    523 };
    524 
    525 /* ARGSUSED */
    526 int
    527 filecore_fhtovp(struct mount *mp, struct fid *fhp, struct vnode **vpp)
    528 {
    529 	struct ifid ifh;
    530 	struct vnode *nvp;
    531 	struct filecore_node *ip;
    532 	int error;
    533 
    534 	if (fhp->fid_len != sizeof(struct ifid))
    535 		return EINVAL;
    536 
    537 	memcpy(&ifh, fhp, sizeof(ifh));
    538 	if ((error = VFS_VGET(mp, ifh.ifid_ino, &nvp)) != 0) {
    539 		*vpp = NULLVP;
    540 		return (error);
    541 	}
    542         ip = VTOI(nvp);
    543         if (filecore_staleinode(ip)) {
    544                 vput(nvp);
    545                 *vpp = NULLVP;
    546                 return (ESTALE);
    547         }
    548 	*vpp = nvp;
    549 	return (0);
    550 }
    551 
    552 /* This looks complicated. Look at other vgets as well as the iso9660 one.
    553  *
    554  * The filecore inode number is made up of 1 byte directory entry index and
    555  * 3 bytes of the internal disc address of the directory. On a read-only
    556  * filesystem this is unique. For a read-write version we may not be able to
    557  * do vget, see msdosfs.
    558  */
    559 
    560 int
    561 filecore_vget(struct mount *mp, ino_t ino, struct vnode **vpp)
    562 {
    563 	int error;
    564 
    565 	error = vcache_get(mp, &ino, sizeof(ino), vpp);
    566 	if (error)
    567 		return error;
    568 	error = vn_lock(*vpp, LK_EXCLUSIVE);
    569 	if (error) {
    570 		vrele(*vpp);
    571 		*vpp = NULL;
    572 		return error;
    573 	}
    574 	return 0;
    575 }
    576 
    577 /*
    578  * Vnode pointer to File handle
    579  */
    580 /* ARGSUSED */
    581 int
    582 filecore_vptofh(struct vnode *vp, struct fid *fhp, size_t *fh_size)
    583 {
    584 	struct filecore_node *ip = VTOI(vp);
    585 	struct ifid ifh;
    586 
    587 	if (*fh_size < sizeof(struct ifid)) {
    588 		*fh_size = sizeof(struct ifid);
    589 		return E2BIG;
    590 	}
    591 	memset(&ifh, 0, sizeof(ifh));
    592 	ifh.ifid_len = sizeof(struct ifid);
    593 	ifh.ifid_ino = ip->i_number;
    594 	memcpy(fhp, &ifh, sizeof(ifh));
    595        	return 0;
    596 }
    597