fs/lofs/lofs_vfsops.c

	lofs_vfsops.c revision b431137cd272e49097db14ab8b85efbbe92a1d76
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson/*
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson * CDDL HEADER START
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson *
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson * The contents of this file are subject to the terms of the
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson * Common Development and Distribution License, Version 1.0 only
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson * (the "License").  You may not use this file except in compliance
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson * with the License.
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson *
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson * or http://www.opensolaris.org/os/licensing.
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson * See the License for the specific language governing permissions
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson * and limitations under the License.
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson *
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson * When distributing Covered Code, include this CDDL HEADER in each
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson * If applicable, add the following below this CDDL HEADER, with the
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson * fields enclosed by brackets "[]" replaced with your own identifying
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson * information: Portions Copyright [yyyy] [name of copyright owner]
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson *
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson * CDDL HEADER END
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson */
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson/*
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson * Use is subject to license terms.
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson */
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson#pragma ident   "%Z%%M% %I% %E% SMI"
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson#include <sys/param.h>
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson#include <sys/errno.h>
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson#include <sys/vfs.h>
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson#include <sys/vnode.h>
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson#include <sys/uio.h>
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson#include <sys/pathname.h>
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson#include <sys/kmem.h>
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson#include <sys/cred.h>
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson#include <sys/statvfs.h>
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson#include <sys/fs/lofs_info.h>
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson#include <sys/fs/lofs_node.h>
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson#include <sys/mount.h>
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson#include <sys/mntent.h>
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson#include <sys/mkdev.h>
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson#include <sys/sysmacros.h>
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson#include <sys/systm.h>
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson#include <sys/cmn_err.h>
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson#include <sys/policy.h>
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson#include "fs/fs_subr.h"
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson/*
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson * This is the loadable module wrapper.
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson */
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson#include <sys/modctl.h>
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson
b00044a2eb43864b8718585d21949611a2ee59efJames Carlsonstatic mntopts_t lofs_mntopts;
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson
b00044a2eb43864b8718585d21949611a2ee59efJames Carlsonstatic int lofsinit(int, char *);
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson
b00044a2eb43864b8718585d21949611a2ee59efJames Carlsonstatic vfsdef_t vfw = {
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson    VFSDEF_VERSION,
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson    "lofs",
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson    lofsinit,
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson    VSW_HASPROTO,
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson    &lofs_mntopts
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson};
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson/*
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson * Stuff needed to support "zonedevfs" mode.
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson */
b00044a2eb43864b8718585d21949611a2ee59efJames Carlsonstatic major_t lofs_major;
b00044a2eb43864b8718585d21949611a2ee59efJames Carlsonstatic minor_t lofs_minor;
b00044a2eb43864b8718585d21949611a2ee59efJames Carlsonstatic kmutex_t lofs_minor_lock;
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson/*
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson * LOFS mount options table
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson */
b00044a2eb43864b8718585d21949611a2ee59efJames Carlsonstatic char *xattr_cancel[] = { MNTOPT_NOXATTR, NULL };
b00044a2eb43864b8718585d21949611a2ee59efJames Carlsonstatic char *noxattr_cancel[] = { MNTOPT_XATTR, NULL };
b00044a2eb43864b8718585d21949611a2ee59efJames Carlsonstatic char *zonedevfs_cancel[] = { MNTOPT_LOFS_NOZONEDEVFS, NULL };
b00044a2eb43864b8718585d21949611a2ee59efJames Carlsonstatic char *nozonedevfs_cancel[] = { MNTOPT_LOFS_ZONEDEVFS, NULL };
b00044a2eb43864b8718585d21949611a2ee59efJames Carlsonstatic char *sub_cancel[] = { MNTOPT_LOFS_NOSUB, NULL };
b00044a2eb43864b8718585d21949611a2ee59efJames Carlsonstatic char *nosub_cancel[] = { MNTOPT_LOFS_SUB, NULL };
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson
b00044a2eb43864b8718585d21949611a2ee59efJames Carlsonstatic mntopt_t mntopts[] = {
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson/*
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson *  option name     cancel option   default arg flags
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson *      private data
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson */
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson    { MNTOPT_XATTR,     xattr_cancel,   NULL,       0,
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson        (void *)0 },
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson    { MNTOPT_NOXATTR,   noxattr_cancel, NULL,       0,
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson        (void *)0 },
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson    { MNTOPT_LOFS_ZONEDEVFS,    zonedevfs_cancel,   NULL,   0,
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson        (void *)0 },
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson    { MNTOPT_LOFS_NOZONEDEVFS,  nozonedevfs_cancel, NULL,   0,
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson        (void *)0 },
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson    { MNTOPT_LOFS_SUB,  sub_cancel, NULL,       0,
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson        (void *)0 },
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson    { MNTOPT_LOFS_NOSUB,    nosub_cancel,   NULL,       0,
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson        (void *)0 },
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson};
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson
b00044a2eb43864b8718585d21949611a2ee59efJames Carlsonstatic mntopts_t lofs_mntopts = {
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson    sizeof (mntopts) / sizeof (mntopt_t),
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson    mntopts
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson};
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson/*
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson * Module linkage information for the kernel.
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson */
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson
b00044a2eb43864b8718585d21949611a2ee59efJames Carlsonstatic struct modlfs modlfs = {
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson    &mod_fsops, "filesystem for lofs", &vfw
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson};
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson
b00044a2eb43864b8718585d21949611a2ee59efJames Carlsonstatic struct modlinkage modlinkage = {
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson    MODREV_1, (void *)&modlfs, NULL
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson};
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson/*
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson * This is the module initialization routine.
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson */
b00044a2eb43864b8718585d21949611a2ee59efJames Carlsonint
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson_init()
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson{
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson    int status;
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson    lofs_subrinit();
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson    status = mod_install(&modlinkage);
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson    if (status != 0) {
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson        /*
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson         * Cleanup previously initialized work.
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson         */
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson        lofs_subrfini();
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson    }
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson    return (status);
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson}
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson/*
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson * Don't allow the lofs module to be unloaded for now.
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson * There is a memory leak if it gets unloaded.
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson */
b00044a2eb43864b8718585d21949611a2ee59efJames Carlsonint
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson_fini()
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson{
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson    return (EBUSY);
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson}
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson
b00044a2eb43864b8718585d21949611a2ee59efJames Carlsonint
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson_info(struct modinfo *modinfop)
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson{
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson    return (mod_info(&modlinkage, modinfop));
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson}
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson
b00044a2eb43864b8718585d21949611a2ee59efJames Carlsonstatic int lofsfstype;
b00044a2eb43864b8718585d21949611a2ee59efJames Carlsonvfsops_t *lo_vfsops;
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson/*
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson * lo mount vfsop
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson * Set up mount info record and attach it to vfs struct.
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson */
ab32bdf2f746488f918233b2d8cabd5835efe9f3James Carlson/*ARGSUSED*/
ab32bdf2f746488f918233b2d8cabd5835efe9f3James Carlsonstatic int
ab32bdf2f746488f918233b2d8cabd5835efe9f3James Carlsonlo_mount(struct vfs *vfsp,
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson    struct vnode *vp,
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson    struct mounta *uap,
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson    struct cred *cr)
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson{
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson    int error;
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson    struct vnode *srootvp = NULL;   /* the server's root */
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson    struct vnode *realrootvp;
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson    struct loinfo *li;
b00044a2eb43864b8718585d21949611a2ee59efJames Carlson    int is_zonedevfs = 0;
    int nodev;

    nodev = vfs_optionisset(vfsp, MNTOPT_NODEVICES, NULL);

    if ((error = secpolicy_fs_mount(cr, vp, vfsp)) != 0)
        return (EPERM);

    /*
     * Loopback devices which get "nodevices" added can be done without
     * "nodevices" set because we cannot import devices into a zone
     * with loopback.  Note that we have all zone privileges when
     * this happens; if not, we'd have gotten "nosuid".
     */
    if (!nodev && vfs_optionisset(vfsp, MNTOPT_NODEVICES, NULL))
        vfs_setmntopt(vfsp, MNTOPT_DEVICES, NULL, VFS_NODISPLAY);

    /*
     * We must ensure that only the global zone applies the 'zonedevfs'
     * option; we don't want non-global zones to be able to establish
     * lofs mounts using the special dev_t we use to ensure that the
     * contents of a zone's /dev cannot be victim to link(2) or rename(2).
     * See below, where we set all of this up.
     *
     * Since this is more like a privilege check, we use crgetzoneid(cr)
     * instead of getzoneid().
     */
    is_zonedevfs = vfs_optionisset(vfsp, MNTOPT_LOFS_ZONEDEVFS, NULL);
    if (crgetzoneid(cr) != GLOBAL_ZONEID && is_zonedevfs)
        return (EPERM);

    mutex_enter(&vp->v_lock);
    if (!(uap->flags & MS_OVERLAY) &&
        (vp->v_count != 1 || (vp->v_flag & VROOT))) {
        mutex_exit(&vp->v_lock);
        return (EBUSY);
    }
    mutex_exit(&vp->v_lock);

    /*
     * Find real root, and make vfs point to real vfs
     */
    if (error = lookupname(uap->spec, (uap->flags & MS_SYSSPACE) ?
        UIO_SYSSPACE : UIO_USERSPACE, FOLLOW, NULLVPP,
        &realrootvp))
        return (error);

    /*
     * realrootvp may be an AUTOFS node, in which case we
     * perform a VOP_ACCESS() to trigger the mount of the
     * intended filesystem, so we loopback mount the intended
     * filesystem instead of the AUTOFS filesystem.
     */
    (void) VOP_ACCESS(realrootvp, 0, 0, cr);

    /*
     * We're interested in the top most filesystem.
     * This is specially important when uap->spec is a trigger
     * AUTOFS node, since we're really interested in mounting the
     * filesystem AUTOFS mounted as result of the VOP_ACCESS()
     * call not the AUTOFS node itself.
     */
    if (vn_mountedvfs(realrootvp) != NULL) {
        if (error = traverse(&realrootvp)) {
            VN_RELE(realrootvp);
            return (error);
        }
    }

    /*
     * Allocate a vfs info struct and attach it
     */
    li = kmem_zalloc(sizeof (struct loinfo), KM_SLEEP);
    li->li_realvfs = realrootvp->v_vfsp;
    li->li_mountvfs = vfsp;

    /*
     * Set mount flags to be inherited by loopback vfs's
     */
    if (vfs_optionisset(vfsp, MNTOPT_RO, NULL)) {
        li->li_mflag |= VFS_RDONLY;
    }
    if (vfs_optionisset(vfsp, MNTOPT_NOSUID, NULL)) {
        li->li_mflag |= (VFS_NOSETUID|VFS_NODEVICES);
    }
    if (vfs_optionisset(vfsp, MNTOPT_NODEVICES, NULL)) {
        li->li_mflag |= VFS_NODEVICES;
    }
    if (vfs_optionisset(vfsp, MNTOPT_NOSETUID, NULL)) {
        li->li_mflag |= VFS_NOSETUID;
    }
    /*
     * Permissive flags are added to the "deny" bitmap.
     */
    if (vfs_optionisset(vfsp, MNTOPT_NOXATTR, NULL)) {
        li->li_dflag |= VFS_XATTR;
    }
    if (vfs_optionisset(vfsp, MNTOPT_NONBMAND, NULL)) {
        li->li_dflag |= VFS_NBMAND;
    }

    /*
     * Propagate inheritable mount flags from the real vfs.
     */
    if ((li->li_realvfs->vfs_flag & VFS_RDONLY) &&
        !vfs_optionisset(vfsp, MNTOPT_RO, NULL))
        vfs_setmntopt(vfsp, MNTOPT_RO, NULL,
            VFS_NODISPLAY);
    if ((li->li_realvfs->vfs_flag & VFS_NOSETUID) &&
        !vfs_optionisset(vfsp, MNTOPT_NOSETUID, NULL))
        vfs_setmntopt(vfsp, MNTOPT_NOSETUID, NULL,
            VFS_NODISPLAY);
    if ((li->li_realvfs->vfs_flag & VFS_NODEVICES) &&
        !vfs_optionisset(vfsp, MNTOPT_NODEVICES, NULL))
        vfs_setmntopt(vfsp, MNTOPT_NODEVICES, NULL,
            VFS_NODISPLAY);
    /*
     * Permissive flags such as VFS_XATTR, as opposed to restrictive flags
     * such as VFS_RDONLY, are handled differently.  An explicit
     * MNTOPT_NOXATTR should override the underlying filesystem's VFS_XATTR.
     */
    if ((li->li_realvfs->vfs_flag & VFS_XATTR) &&
        !vfs_optionisset(vfsp, MNTOPT_NOXATTR, NULL) &&
        !vfs_optionisset(vfsp, MNTOPT_XATTR, NULL))
        vfs_setmntopt(vfsp, MNTOPT_XATTR, NULL,
            VFS_NODISPLAY);
    if ((li->li_realvfs->vfs_flag & VFS_NBMAND) &&
        !vfs_optionisset(vfsp, MNTOPT_NBMAND, NULL) &&
        !vfs_optionisset(vfsp, MNTOPT_NONBMAND, NULL))
        vfs_setmntopt(vfsp, MNTOPT_NBMAND, NULL,
            VFS_NODISPLAY);

    li->li_refct = 0;
    vfsp->vfs_data = (caddr_t)li;
    vfsp->vfs_bcount = 0;
    vfsp->vfs_fstype = lofsfstype;
    vfsp->vfs_bsize = li->li_realvfs->vfs_bsize;

    /*
     * Test to see if we need to be in "zone /dev" mode.  In zonedevfs
     * mode, we pull a nasty trick; we make sure that the lofs dev_t does
     * *not* reflect the underlying device, so that no renames or links
     * can occur to or from the /dev hierarchy.
     */
    if (is_zonedevfs) {
        dev_t dev;

        mutex_enter(&lofs_minor_lock);
        do {
            lofs_minor = (lofs_minor + 1) & MAXMIN32;
            dev = makedevice(lofs_major, lofs_minor);
        } while (vfs_devismounted(dev));
        mutex_exit(&lofs_minor_lock);

        vfsp->vfs_dev = dev;
        vfs_make_fsid(&vfsp->vfs_fsid, dev, lofsfstype);

        li->li_flag |= LO_ZONEDEVFS;
    } else {
        vfsp->vfs_dev = li->li_realvfs->vfs_dev;
        vfsp->vfs_fsid.val[0] = li->li_realvfs->vfs_fsid.val[0];
        vfsp->vfs_fsid.val[1] = li->li_realvfs->vfs_fsid.val[1];
    }

    if (vfs_optionisset(vfsp, MNTOPT_LOFS_NOSUB, NULL)) {
        li->li_flag |= LO_NOSUB;
    }

    /*
     * Setup the hashtable. If the root of this mount isn't a directory,
     * there's no point in allocating a large hashtable. A table with one
     * bucket is sufficient.
     */
    if (realrootvp->v_type != VDIR)
        lsetup(li, 1);
    else
        lsetup(li, 0);

    /*
     * Make the root vnode
     */
    srootvp = makelonode(realrootvp, li, 0);
    srootvp->v_flag |= VROOT;
    li->li_rootvp = srootvp;

#ifdef LODEBUG
    lo_dprint(4, "lo_mount: vfs %p realvfs %p root %p realroot %p li %p\n",
        vfsp, li->li_realvfs, srootvp, realrootvp, li);
#endif
    return (0);
}

/*
 * Undo loopback mount
 */
static int
lo_unmount(struct vfs *vfsp, int flag, struct cred *cr)
{
    struct loinfo *li;

    if (secpolicy_fs_unmount(cr, vfsp) != 0)
        return (EPERM);

    /*
     * Forced unmount is not supported by this file system
     * and thus, ENOTSUP, is being returned.
     */
    if (flag & MS_FORCE)
        return (ENOTSUP);

    li = vtoli(vfsp);
#ifdef LODEBUG
    lo_dprint(4, "lo_unmount(%p) li %p\n", vfsp, li);
#endif
    if (li->li_refct != 1 || li->li_rootvp->v_count != 1) {
#ifdef LODEBUG
        lo_dprint(4, "refct %d v_ct %d\n", li->li_refct,
            li->li_rootvp->v_count);
#endif
        return (EBUSY);
    }
    VN_RELE(li->li_rootvp);
    return (0);
}

/*
 * Find root of lofs mount.
 */
static int
lo_root(struct vfs *vfsp, struct vnode **vpp)
{
    *vpp = vtoli(vfsp)->li_rootvp;
#ifdef LODEBUG
    lo_dprint(4, "lo_root(0x%p) = %p\n", vfsp, *vpp);
#endif
    /*
     * If the root of the filesystem is a special file, return the specvp
     * version of the vnode. We don't save the specvp vnode in our
     * hashtable since that's exclusively for lnodes.
     */
    if (IS_DEVVP(*vpp)) {
        struct vnode *svp;

        svp = specvp(*vpp, (*vpp)->v_rdev, (*vpp)->v_type, kcred);
        if (svp == NULL)
            return (ENOSYS);
        *vpp = svp;
    } else {
        VN_HOLD(*vpp);
    }

    return (0);
}

/*
 * Get file system statistics.
 */
static int
lo_statvfs(register struct vfs *vfsp, struct statvfs64 *sbp)
{
    vnode_t *realrootvp;

#ifdef LODEBUG
    lo_dprint(4, "lostatvfs %p\n", vfsp);
#endif
    /*
     * Using realrootvp->v_vfsp (instead of the realvfsp that was
     * cached) is necessary to make lofs work woth forced UFS unmounts.
     * In the case of a forced unmount, UFS stores a set of dummy vfsops
     * in all the (i)vnodes in the filesystem. The dummy ops simply
     * returns back EIO.
     */
    (void) lo_realvfs(vfsp, &realrootvp);
    if (realrootvp != NULL)
        return (VFS_STATVFS(realrootvp->v_vfsp, sbp));
    else
        return (EIO);
}

/*
 * LOFS doesn't have any data or metadata to flush, pending I/O on the
 * underlying filesystem will be flushed when such filesystem is synched.
 */
/* ARGSUSED */
static int
lo_sync(struct vfs *vfsp,
    short flag,
    struct cred *cr)
{
#ifdef LODEBUG
    lo_dprint(4, "lo_sync: %p\n", vfsp);
#endif
    return (0);
}

/*
 * Obtain the vnode from the underlying filesystem.
 */
static int
lo_vget(struct vfs *vfsp, struct vnode **vpp, struct fid *fidp)
{
    vnode_t *realrootvp;

#ifdef LODEBUG
    lo_dprint(4, "lo_vget: %p\n", vfsp);
#endif
    (void) lo_realvfs(vfsp, &realrootvp);
    if (realrootvp != NULL)
        return (VFS_VGET(realrootvp->v_vfsp, vpp, fidp));
    else
        return (EIO);
}

/*
 * Free mount-specific data.
 */
static void
lo_freevfs(struct vfs *vfsp)
{
    struct loinfo *li = vtoli(vfsp);

    ldestroy(li);
    kmem_free(li, sizeof (struct loinfo));
}

static int
lofsinit(int fstyp, char *name)
{
    static const fs_operation_def_t lo_vfsops_template[] = {
        VFSNAME_MOUNT, lo_mount,
        VFSNAME_UNMOUNT, lo_unmount,
        VFSNAME_ROOT, lo_root,
        VFSNAME_STATVFS, lo_statvfs,
        VFSNAME_SYNC, (fs_generic_func_p) lo_sync,
        VFSNAME_VGET, lo_vget,
        VFSNAME_FREEVFS, (fs_generic_func_p) lo_freevfs,
        NULL, NULL
    };
    int error;

    error = vfs_setfsops(fstyp, lo_vfsops_template, &lo_vfsops);
    if (error != 0) {
        cmn_err(CE_WARN, "lofsinit: bad vfs ops template");
        return (error);
    }

    error = vn_make_ops(name, lo_vnodeops_template, &lo_vnodeops);
    if (error != 0) {
        (void) vfs_freevfsops_by_type(fstyp);
        cmn_err(CE_WARN, "lofsinit: bad vnode ops template");
        return (error);
    }

    lofsfstype = fstyp;

    if ((lofs_major = getudev()) == (major_t)-1) {
        (void) vfs_freevfsops_by_type(fstyp);
        cmn_err(CE_WARN, "lofsinit: Can't get unique device number.");
        return (ENXIO);
    }

    lofs_minor = 0;
    mutex_init(&lofs_minor_lock, NULL, MUTEX_DEFAULT, NULL);

    return (0);
}