vfs_mount.c

Go to the documentation of this file.

/*-
 * Copyright (c) 1999-2004 Poul-Henning Kamp
 * Copyright (c) 1999 Michael Smith
 * Copyright (c) 1989, 1993
 *      The Regents of the University of California.  All rights reserved.
 * (c) UNIX System Laboratories, Inc.
 * All or some portions of this file are derived from material licensed
 * to the University of California by American Telephone and Telegraph
 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
 * the permission of UNIX System Laboratories, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__FBSDID("$BSDSUniX$");

#include <sys/param.h>
#include <sys/conf.h>
#include <sys/fcntl.h>
#include <sys/jail.h>
#include <sys/kernel.h>
#include <sys/libkern.h>
#include <sys/malloc.h>
#include <sys/mount.h>
#include <sys/mutex.h>
#include <sys/namei.h>
#include <sys/priv.h>
#include <sys/proc.h>
#include <sys/filedesc.h>
#include <sys/reboot.h>
#include <sys/sbuf.h>
#include <sys/syscallsubr.h>
#include <sys/sysproto.h>
#include <sys/sx.h>
#include <sys/sysctl.h>
#include <sys/sysent.h>
#include <sys/systm.h>
#include <sys/vnode.h>
#include <vm/uma.h>

#include <geom/geom.h>

#include <machine/stdarg.h>

#include <security/audit/audit.h>
#include <security/mac/mac_framework.h>

#define VFS_MOUNTARG_SIZE_MAX   (1024 * 64)

static int      vfs_domount(struct thread *td, const char *fstype, char *fspath,
                    uint64_t fsflags, struct vfsoptlist **optlist);
static void     free_mntarg(struct mntarg *ma);

static int      usermount = 0;
SYSCTL_INT(_vfs, OID_AUTO, usermount, CTLFLAG_RW, &usermount, 0,
    "Unprivileged users may mount and unmount file systems");

MALLOC_DEFINE(M_MOUNT, "mount", "vfs mount structure");
static uma_zone_t mount_zone;

/* List of mounted filesystems. */
struct mntlist mountlist = TAILQ_HEAD_INITIALIZER(mountlist);

/* For any iteration/modification of mountlist */
struct mtx mountlist_mtx;
MTX_SYSINIT(mountlist, &mountlist_mtx, "mountlist", MTX_DEF);

/*
 * Global opts, taken by all filesystems
 */
static const char *global_opts[] = {
        "errmsg",
        "fstype",
        "fspath",
        "ro",
        "rw",
        "nosuid",
        "noexec",
        NULL
};

static int
mount_init(void *mem, int size, int flags)
{
        struct mount *mp;

        mp = (struct mount *)mem;
        mtx_init(&mp->mnt_mtx, "struct mount mtx", NULL, MTX_DEF);
        lockinit(&mp->mnt_explock, PVFS, "explock", 0, 0);
        return (0);
}

static void
mount_fini(void *mem, int size)
{
        struct mount *mp;

        mp = (struct mount *)mem;
        lockdestroy(&mp->mnt_explock);
        mtx_destroy(&mp->mnt_mtx);
}

static void
vfs_mount_init(void *dummy __unused)
{

        mount_zone = uma_zcreate("Mountpoints", sizeof(struct mount), NULL,
            NULL, mount_init, mount_fini, UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
}
SYSINIT(vfs_mount, SI_SUB_VFS, SI_ORDER_ANY, vfs_mount_init, NULL);

/*
 * ---------------------------------------------------------------------
 * Functions for building and sanitizing the mount options
 */

/* Remove one mount option. */
static void
vfs_freeopt(struct vfsoptlist *opts, struct vfsopt *opt)
{

        TAILQ_REMOVE(opts, opt, link);
        free(opt->name, M_MOUNT);
        if (opt->value != NULL)
                free(opt->value, M_MOUNT);
        free(opt, M_MOUNT);
}

/* Release all resources related to the mount options. */
void
vfs_freeopts(struct vfsoptlist *opts)
{
        struct vfsopt *opt;

        while (!TAILQ_EMPTY(opts)) {
                opt = TAILQ_FIRST(opts);
                vfs_freeopt(opts, opt);
        }
        free(opts, M_MOUNT);
}

void
vfs_deleteopt(struct vfsoptlist *opts, const char *name)
{
        struct vfsopt *opt, *temp;

        if (opts == NULL)
                return;
        TAILQ_FOREACH_SAFE(opt, opts, link, temp)  {
                if (strcmp(opt->name, name) == 0)
                        vfs_freeopt(opts, opt);
        }
}

static int
vfs_isopt_ro(const char *opt)
{

        if (strcmp(opt, "ro") == 0 || strcmp(opt, "rdonly") == 0 ||
            strcmp(opt, "norw") == 0)
                return (1);
        return (0);
}

static int
vfs_isopt_rw(const char *opt)
{

        if (strcmp(opt, "rw") == 0 || strcmp(opt, "noro") == 0)
                return (1);
        return (0);
}

/*
 * Check if options are equal (with or without the "no" prefix).
 */
static int
vfs_equalopts(const char *opt1, const char *opt2)
{
        char *p;

        /* "opt" vs. "opt" or "noopt" vs. "noopt" */
        if (strcmp(opt1, opt2) == 0)
                return (1);
        /* "noopt" vs. "opt" */
        if (strncmp(opt1, "no", 2) == 0 && strcmp(opt1 + 2, opt2) == 0)
                return (1);
        /* "opt" vs. "noopt" */
        if (strncmp(opt2, "no", 2) == 0 && strcmp(opt1, opt2 + 2) == 0)
                return (1);
        while ((p = strchr(opt1, '.')) != NULL &&
            !strncmp(opt1, opt2, ++p - opt1)) {
                opt2 += p - opt1;
                opt1 = p;
                /* "foo.noopt" vs. "foo.opt" */
                if (strncmp(opt1, "no", 2) == 0 && strcmp(opt1 + 2, opt2) == 0)
                        return (1);
                /* "foo.opt" vs. "foo.noopt" */
                if (strncmp(opt2, "no", 2) == 0 && strcmp(opt1, opt2 + 2) == 0)
                        return (1);
        }
        /* "ro" / "rdonly" / "norw" / "rw" / "noro" */
        if ((vfs_isopt_ro(opt1) || vfs_isopt_rw(opt1)) &&
            (vfs_isopt_ro(opt2) || vfs_isopt_rw(opt2)))
                return (1);
        return (0);
}

/*
 * If a mount option is specified several times,
 * (with or without the "no" prefix) only keep
 * the last occurence of it.
 */
static void
vfs_sanitizeopts(struct vfsoptlist *opts)
{
        struct vfsopt *opt, *opt2, *tmp;

        TAILQ_FOREACH_REVERSE(opt, opts, vfsoptlist, link) {
                opt2 = TAILQ_PREV(opt, vfsoptlist, link);
                while (opt2 != NULL) {
                        if (vfs_equalopts(opt->name, opt2->name)) {
                                tmp = TAILQ_PREV(opt2, vfsoptlist, link);
                                vfs_freeopt(opts, opt2);
                                opt2 = tmp;
                        } else {
                                opt2 = TAILQ_PREV(opt2, vfsoptlist, link);
                        }
                }
        }
}

/*
 * Build a linked list of mount options from a struct uio.
 */
int
vfs_buildopts(struct uio *auio, struct vfsoptlist **options)
{
        struct vfsoptlist *opts;
        struct vfsopt *opt;
        size_t memused, namelen, optlen;
        unsigned int i, iovcnt;
        int error;

        opts = malloc(sizeof(struct vfsoptlist), M_MOUNT, M_WAITOK);
        TAILQ_INIT(opts);
        memused = 0;
        iovcnt = auio->uio_iovcnt;
        for (i = 0; i < iovcnt; i += 2) {
                namelen = auio->uio_iov[i].iov_len;
                optlen = auio->uio_iov[i + 1].iov_len;
                memused += sizeof(struct vfsopt) + optlen + namelen;
                /*
                 * Avoid consuming too much memory, and attempts to overflow
                 * memused.
                 */
                if (memused > VFS_MOUNTARG_SIZE_MAX ||
                    optlen > VFS_MOUNTARG_SIZE_MAX ||
                    namelen > VFS_MOUNTARG_SIZE_MAX) {
                        error = EINVAL;
                        goto bad;
                }

                opt = malloc(sizeof(struct vfsopt), M_MOUNT, M_WAITOK);
                opt->name = malloc(namelen, M_MOUNT, M_WAITOK);
                opt->value = NULL;
                opt->len = 0;
                opt->pos = i / 2;
                opt->seen = 0;

                /*
                 * Do this early, so jumps to "bad" will free the current
                 * option.
                 */
                TAILQ_INSERT_TAIL(opts, opt, link);

                if (auio->uio_segflg == UIO_SYSSPACE) {
                        bcopy(auio->uio_iov[i].iov_base, opt->name, namelen);
                } else {
                        error = copyin(auio->uio_iov[i].iov_base, opt->name,
                            namelen);
                        if (error)
                                goto bad;
                }
                /* Ensure names are null-terminated strings. */
                if (namelen == 0 || opt->name[namelen - 1] != '\0') {
                        error = EINVAL;
                        goto bad;
                }
                if (optlen != 0) {
                        opt->len = optlen;
                        opt->value = malloc(optlen, M_MOUNT, M_WAITOK);
                        if (auio->uio_segflg == UIO_SYSSPACE) {
                                bcopy(auio->uio_iov[i + 1].iov_base, opt->value,
                                    optlen);
                        } else {
                                error = copyin(auio->uio_iov[i + 1].iov_base,
                                    opt->value, optlen);
                                if (error)
                                        goto bad;
                        }
                }
        }
        vfs_sanitizeopts(opts);
        *options = opts;
        return (0);
bad:
        vfs_freeopts(opts);
        return (error);
}

/*
 * Merge the old mount options with the new ones passed
 * in the MNT_UPDATE case.
 *
 * XXX: This function will keep a "nofoo" option in the new
 * options.  E.g, if the option's canonical name is "foo",
 * "nofoo" ends up in the mount point's active options.
 */
static void
vfs_mergeopts(struct vfsoptlist *toopts, struct vfsoptlist *oldopts)
{
        struct vfsopt *opt, *new;

        TAILQ_FOREACH(opt, oldopts, link) {
                new = malloc(sizeof(struct vfsopt), M_MOUNT, M_WAITOK);
                new->name = strdup(opt->name, M_MOUNT);
                if (opt->len != 0) {
                        new->value = malloc(opt->len, M_MOUNT, M_WAITOK);
                        bcopy(opt->value, new->value, opt->len);
                } else
                        new->value = NULL;
                new->len = opt->len;
                new->seen = opt->seen;
                TAILQ_INSERT_HEAD(toopts, new, link);
        }
        vfs_sanitizeopts(toopts);
}

/*
 * Mount a filesystem.
 */
int
sys_nmount(td, uap)
        struct thread *td;
        struct nmount_args /* {
                struct iovec *iovp;
                unsigned int iovcnt;
                int flags;
        } */ *uap;
{
        struct uio *auio;
        int error;
        u_int iovcnt;
        uint64_t flags;

        /*
         * Mount flags are now 64-bits. On 32-bit archtectures only
         * 32-bits are passed in, but from here on everything handles
         * 64-bit flags correctly.
         */
        flags = uap->flags;

        AUDIT_ARG_FFLAGS(flags);
        CTR4(KTR_VFS, "%s: iovp %p with iovcnt %d and flags %d", __func__,
            uap->iovp, uap->iovcnt, flags);

        /*
         * Filter out MNT_ROOTFS.  We do not want clients of nmount() in
         * userspace to set this flag, but we must filter it out if we want
         * MNT_UPDATE on the root file system to work.
         * MNT_ROOTFS should only be set by the kernel when mounting its
         * root file system.
         */
        flags &= ~MNT_ROOTFS;

        iovcnt = uap->iovcnt;
        /*
         * Check that we have an even number of iovec's
         * and that we have at least two options.
         */
        if ((iovcnt & 1) || (iovcnt < 4)) {
                CTR2(KTR_VFS, "%s: failed for invalid iovcnt %d", __func__,
                    uap->iovcnt);
                return (EINVAL);
        }

        error = copyinuio(uap->iovp, iovcnt, &auio);
        if (error) {
                CTR2(KTR_VFS, "%s: failed for invalid uio op with %d errno",
                    __func__, error);
                return (error);
        }
        error = vfs_donmount(td, flags, auio);

        free(auio, M_IOV);
        return (error);
}

/*
 * ---------------------------------------------------------------------
 * Various utility functions
 */

void
vfs_ref(struct mount *mp)
{

        CTR2(KTR_VFS, "%s: mp %p", __func__, mp);
        MNT_ILOCK(mp);
        MNT_REF(mp);
        MNT_IUNLOCK(mp);
}

void
vfs_rel(struct mount *mp)
{

        CTR2(KTR_VFS, "%s: mp %p", __func__, mp);
        MNT_ILOCK(mp);
        MNT_REL(mp);
        MNT_IUNLOCK(mp);
}

/*
 * Allocate and initialize the mount point struct.
 */
struct mount *
vfs_mount_alloc(struct vnode *vp, struct vfsconf *vfsp, const char *fspath,
    struct ucred *cred)
{
        struct mount *mp;

        mp = uma_zalloc(mount_zone, M_WAITOK);
        bzero(&mp->mnt_startzero,
            __rangeof(struct mount, mnt_startzero, mnt_endzero));
        TAILQ_INIT(&mp->mnt_nvnodelist);
        mp->mnt_nvnodelistsize = 0;
        TAILQ_INIT(&mp->mnt_activevnodelist);
        mp->mnt_activevnodelistsize = 0;
        mp->mnt_ref = 0;
        (void) vfs_busy(mp, MBF_NOWAIT);
        mp->mnt_op = vfsp->vfc_vfsops;
        mp->mnt_vfc = vfsp;
        vfsp->vfc_refcount++;   /* XXX Unlocked */
        mp->mnt_stat.f_type = vfsp->vfc_typenum;
        mp->mnt_gen++;
        strlcpy(mp->mnt_stat.f_fstypename, vfsp->vfc_name, MFSNAMELEN);
        mp->mnt_vnodecovered = vp;
        mp->mnt_cred = crdup(cred);
        mp->mnt_stat.f_owner = cred->cr_uid;
        strlcpy(mp->mnt_stat.f_mntonname, fspath, MNAMELEN);
        mp->mnt_iosize_max = DFLTPHYS;
#ifdef MAC
        mac_mount_init(mp);
        mac_mount_create(cred, mp);
#endif
        arc4rand(&mp->mnt_hashseed, sizeof mp->mnt_hashseed, 0);
        TAILQ_INIT(&mp->mnt_uppers);
        return (mp);
}

/*
 * Destroy the mount struct previously allocated by vfs_mount_alloc().
 */
void
vfs_mount_destroy(struct mount *mp)
{

        MNT_ILOCK(mp);
        mp->mnt_kern_flag |= MNTK_REFEXPIRE;
        if (mp->mnt_kern_flag & MNTK_MWAIT) {
                mp->mnt_kern_flag &= ~MNTK_MWAIT;
                wakeup(mp);
        }
        while (mp->mnt_ref)
                msleep(mp, MNT_MTX(mp), PVFS, "mntref", 0);
        KASSERT(mp->mnt_ref == 0,
            ("%s: invalid refcount in the drain path @ %s:%d", __func__,
            __FILE__, __LINE__));
        if (mp->mnt_writeopcount != 0)
                panic("vfs_mount_destroy: nonzero writeopcount");
        if (mp->mnt_secondary_writes != 0)
                panic("vfs_mount_destroy: nonzero secondary_writes");
        mp->mnt_vfc->vfc_refcount--;
        if (!TAILQ_EMPTY(&mp->mnt_nvnodelist)) {
                struct vnode *vp;

                TAILQ_FOREACH(vp, &mp->mnt_nvnodelist, v_nmntvnodes)
                        vprint("", vp);
                panic("unmount: dangling vnode");
        }
        KASSERT(TAILQ_EMPTY(&mp->mnt_uppers), ("mnt_uppers"));
        if (mp->mnt_nvnodelistsize != 0)
                panic("vfs_mount_destroy: nonzero nvnodelistsize");
        if (mp->mnt_activevnodelistsize != 0)
                panic("vfs_mount_destroy: nonzero activevnodelistsize");
        if (mp->mnt_lockref != 0)
                panic("vfs_mount_destroy: nonzero lock refcount");
        MNT_IUNLOCK(mp);
#ifdef MAC
        mac_mount_destroy(mp);
#endif
        if (mp->mnt_opt != NULL)
                vfs_freeopts(mp->mnt_opt);
        crfree(mp->mnt_cred);
        uma_zfree(mount_zone, mp);
}

int
vfs_donmount(struct thread *td, uint64_t fsflags, struct uio *fsoptions)
{
        struct vfsoptlist *optlist;
        struct vfsopt *opt, *tmp_opt;
        char *fstype, *fspath, *errmsg;
        int error, fstypelen, fspathlen, errmsg_len, errmsg_pos;

        errmsg = fspath = NULL;
        errmsg_len = fspathlen = 0;
        errmsg_pos = -1;

        error = vfs_buildopts(fsoptions, &optlist);
        if (error)
                return (error);

        if (vfs_getopt(optlist, "errmsg", (void **)&errmsg, &errmsg_len) == 0)
                errmsg_pos = vfs_getopt_pos(optlist, "errmsg");

        /*
         * We need these two options before the others,
         * and they are mandatory for any filesystem.
         * Ensure they are NUL terminated as well.
         */
        fstypelen = 0;
        error = vfs_getopt(optlist, "fstype", (void **)&fstype, &fstypelen);
        if (error || fstype[fstypelen - 1] != '\0') {
                error = EINVAL;
                if (errmsg != NULL)
                        strncpy(errmsg, "Invalid fstype", errmsg_len);
                goto bail;
        }
        fspathlen = 0;
        error = vfs_getopt(optlist, "fspath", (void **)&fspath, &fspathlen);
        if (error || fspath[fspathlen - 1] != '\0') {
                error = EINVAL;
                if (errmsg != NULL)
                        strncpy(errmsg, "Invalid fspath", errmsg_len);
                goto bail;
        }

        /*
         * We need to see if we have the "update" option
         * before we call vfs_domount(), since vfs_domount() has special
         * logic based on MNT_UPDATE.  This is very important
         * when we want to update the root filesystem.
         */
        TAILQ_FOREACH_SAFE(opt, optlist, link, tmp_opt) {
                if (strcmp(opt->name, "update") == 0) {
                        fsflags |= MNT_UPDATE;
                        vfs_freeopt(optlist, opt);
                }
                else if (strcmp(opt->name, "async") == 0)
                        fsflags |= MNT_ASYNC;
                else if (strcmp(opt->name, "force") == 0) {
                        fsflags |= MNT_FORCE;
                        vfs_freeopt(optlist, opt);
                }
                else if (strcmp(opt->name, "reload") == 0) {
                        fsflags |= MNT_RELOAD;
                        vfs_freeopt(optlist, opt);
                }
                else if (strcmp(opt->name, "multilabel") == 0)
                        fsflags |= MNT_MULTILABEL;
                else if (strcmp(opt->name, "noasync") == 0)
                        fsflags &= ~MNT_ASYNC;
                else if (strcmp(opt->name, "noatime") == 0)
                        fsflags |= MNT_NOATIME;
                else if (strcmp(opt->name, "atime") == 0) {
                        free(opt->name, M_MOUNT);
                        opt->name = strdup("nonoatime", M_MOUNT);
                }
                else if (strcmp(opt->name, "noclusterr") == 0)
                        fsflags |= MNT_NOCLUSTERR;
                else if (strcmp(opt->name, "clusterr") == 0) {
                        free(opt->name, M_MOUNT);
                        opt->name = strdup("nonoclusterr", M_MOUNT);
                }
                else if (strcmp(opt->name, "noclusterw") == 0)
                        fsflags |= MNT_NOCLUSTERW;
                else if (strcmp(opt->name, "clusterw") == 0) {
                        free(opt->name, M_MOUNT);
                        opt->name = strdup("nonoclusterw", M_MOUNT);
                }
                else if (strcmp(opt->name, "noexec") == 0)
                        fsflags |= MNT_NOEXEC;
                else if (strcmp(opt->name, "exec") == 0) {
                        free(opt->name, M_MOUNT);
                        opt->name = strdup("nonoexec", M_MOUNT);
                }
                else if (strcmp(opt->name, "nosuid") == 0)
                        fsflags |= MNT_NOSUID;
                else if (strcmp(opt->name, "suid") == 0) {
                        free(opt->name, M_MOUNT);
                        opt->name = strdup("nonosuid", M_MOUNT);
                }
                else if (strcmp(opt->name, "nosymfollow") == 0)
                        fsflags |= MNT_NOSYMFOLLOW;
                else if (strcmp(opt->name, "symfollow") == 0) {
                        free(opt->name, M_MOUNT);
                        opt->name = strdup("nonosymfollow", M_MOUNT);
                }
                else if (strcmp(opt->name, "noro") == 0)
                        fsflags &= ~MNT_RDONLY;
                else if (strcmp(opt->name, "rw") == 0)
                        fsflags &= ~MNT_RDONLY;
                else if (strcmp(opt->name, "ro") == 0)
                        fsflags |= MNT_RDONLY;
                else if (strcmp(opt->name, "rdonly") == 0) {
                        free(opt->name, M_MOUNT);
                        opt->name = strdup("ro", M_MOUNT);
                        fsflags |= MNT_RDONLY;
                }
                else if (strcmp(opt->name, "suiddir") == 0)
                        fsflags |= MNT_SUIDDIR;
                else if (strcmp(opt->name, "sync") == 0)
                        fsflags |= MNT_SYNCHRONOUS;
                else if (strcmp(opt->name, "union") == 0)
                        fsflags |= MNT_UNION;
        }

        /*
         * Be ultra-paranoid about making sure the type and fspath
         * variables will fit in our mp buffers, including the
         * terminating NUL.
         */
        if (fstypelen >= MFSNAMELEN - 1 || fspathlen >= MNAMELEN - 1) {
                error = ENAMETOOLONG;
                goto bail;
        }

        error = vfs_domount(td, fstype, fspath, fsflags, &optlist);
bail:
        /* copyout the errmsg */
        if (errmsg_pos != -1 && ((2 * errmsg_pos + 1) < fsoptions->uio_iovcnt)
            && errmsg_len > 0 && errmsg != NULL) {
                if (fsoptions->uio_segflg == UIO_SYSSPACE) {
                        bcopy(errmsg,
                            fsoptions->uio_iov[2 * errmsg_pos + 1].iov_base,
                            fsoptions->uio_iov[2 * errmsg_pos + 1].iov_len);
                } else {
                        copyout(errmsg,
                            fsoptions->uio_iov[2 * errmsg_pos + 1].iov_base,
                            fsoptions->uio_iov[2 * errmsg_pos + 1].iov_len);
                }
        }

        if (optlist != NULL)
                vfs_freeopts(optlist);
        return (error);
}

/*
 * Old mount API.
 */
#ifndef _SYS_SYSPROTO_H_
struct mount_args {
        char    *type;
        char    *path;
        int     flags;
        caddr_t data;
};
#endif
/* ARGSUSED */
int
sys_mount(td, uap)
        struct thread *td;
        struct mount_args /* {
                char *type;
                char *path;
                int flags;
                caddr_t data;
        } */ *uap;
{
        char *fstype;
        struct vfsconf *vfsp = NULL;
        struct mntarg *ma = NULL;
        uint64_t flags;
        int error;

        /*
         * Mount flags are now 64-bits. On 32-bit architectures only
         * 32-bits are passed in, but from here on everything handles
         * 64-bit flags correctly.
         */
        flags = uap->flags;

        AUDIT_ARG_FFLAGS(flags);

        /*
         * Filter out MNT_ROOTFS.  We do not want clients of mount() in
         * userspace to set this flag, but we must filter it out if we want
         * MNT_UPDATE on the root file system to work.
         * MNT_ROOTFS should only be set by the kernel when mounting its
         * root file system.
         */
        flags &= ~MNT_ROOTFS;

        fstype = malloc(MFSNAMELEN, M_TEMP, M_WAITOK);
        error = copyinstr(uap->type, fstype, MFSNAMELEN, NULL);
        if (error) {
                free(fstype, M_TEMP);
                return (error);
        }

        AUDIT_ARG_TEXT(fstype);
        mtx_lock(&Giant);
        vfsp = vfs_byname_kld(fstype, td, &error);
        free(fstype, M_TEMP);
        if (vfsp == NULL) {
                mtx_unlock(&Giant);
                return (ENOENT);
        }
        if (vfsp->vfc_vfsops->vfs_cmount == NULL) {
                mtx_unlock(&Giant);
                return (EOPNOTSUPP);
        }

        ma = mount_argsu(ma, "fstype", uap->type, MFSNAMELEN);
        ma = mount_argsu(ma, "fspath", uap->path, MNAMELEN);
        ma = mount_argb(ma, flags & MNT_RDONLY, "noro");
        ma = mount_argb(ma, !(flags & MNT_NOSUID), "nosuid");
        ma = mount_argb(ma, !(flags & MNT_NOEXEC), "noexec");

        error = vfsp->vfc_vfsops->vfs_cmount(ma, uap->data, flags);
        mtx_unlock(&Giant);
        return (error);
}

/*
 * vfs_domount_first(): first file system mount (not update)
 */
static int
vfs_domount_first(
        struct thread *td,              /* Calling thread. */
        struct vfsconf *vfsp,           /* File system type. */
        char *fspath,                   /* Mount path. */
        struct vnode *vp,               /* Vnode to be covered. */
        uint64_t fsflags,               /* Flags common to all filesystems. */
        struct vfsoptlist **optlist     /* Options local to the filesystem. */
        )
{
        struct vattr va;
        struct mount *mp;
        struct vnode *newdp;
        int error;

        mtx_assert(&Giant, MA_OWNED);
        ASSERT_VOP_ELOCKED(vp, __func__);
        KASSERT((fsflags & MNT_UPDATE) == 0, ("MNT_UPDATE shouldn't be here"));

        /*
         * If the user is not root, ensure that they own the directory
         * onto which we are attempting to mount.
         */
        error = VOP_GETATTR(vp, &va, td->td_ucred);
        if (error == 0 && va.va_uid != td->td_ucred->cr_uid)
                error = priv_check_cred(td->td_ucred, PRIV_VFS_ADMIN, 0);
        if (error == 0)
                error = vinvalbuf(vp, V_SAVE, 0, 0);
        if (error == 0 && vp->v_type != VDIR)
                error = ENOTDIR;
        if (error == 0) {
                VI_LOCK(vp);
                if ((vp->v_iflag & VI_MOUNT) == 0 && vp->v_mountedhere == NULL)
                        vp->v_iflag |= VI_MOUNT;
                else
                        error = EBUSY;
                VI_UNLOCK(vp);
        }
        if (error != 0) {
                vput(vp);
                return (error);
        }
        VOP_UNLOCK(vp, 0);

        /* Allocate and initialize the filesystem. */
        mp = vfs_mount_alloc(vp, vfsp, fspath, td->td_ucred);
        /* XXXMAC: pass to vfs_mount_alloc? */
        mp->mnt_optnew = *optlist;
        /* Set the mount level flags. */
        mp->mnt_flag = (fsflags & (MNT_UPDATEMASK | MNT_ROOTFS | MNT_RDONLY));

        /*
         * Mount the filesystem.
         * XXX The final recipients of VFS_MOUNT just overwrite the ndp they
         * get.  No freeing of cn_pnbuf.
         */
        error = VFS_MOUNT(mp);
        if (error != 0) {
                vfs_unbusy(mp);
                vfs_mount_destroy(mp);
                VI_LOCK(vp);
                vp->v_iflag &= ~VI_MOUNT;
                VI_UNLOCK(vp);
                vrele(vp);
                return (error);
        }

        if (mp->mnt_opt != NULL)
                vfs_freeopts(mp->mnt_opt);
        mp->mnt_opt = mp->mnt_optnew;
        *optlist = NULL;
        (void)VFS_STATFS(mp, &mp->mnt_stat);

        /*
         * Prevent external consumers of mount options from reading mnt_optnew.
         */
        mp->mnt_optnew = NULL;

        MNT_ILOCK(mp);
        if ((mp->mnt_flag & MNT_ASYNC) != 0 &&
            (mp->mnt_kern_flag & MNTK_NOASYNC) == 0)
                mp->mnt_kern_flag |= MNTK_ASYNC;
        else
                mp->mnt_kern_flag &= ~MNTK_ASYNC;
        MNT_IUNLOCK(mp);

        vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
        cache_purge(vp);
        VI_LOCK(vp);
        vp->v_iflag &= ~VI_MOUNT;
        VI_UNLOCK(vp);
        vp->v_mountedhere = mp;
        /* Place the new filesystem at the end of the mount list. */
        mtx_lock(&mountlist_mtx);
        TAILQ_INSERT_TAIL(&mountlist, mp, mnt_list);
        mtx_unlock(&mountlist_mtx);
        vfs_event_signal(NULL, VQ_MOUNT, 0);
        if (VFS_ROOT(mp, LK_EXCLUSIVE, &newdp))
                panic("mount: lost mount");
        VOP_UNLOCK(newdp, 0);
        VOP_UNLOCK(vp, 0);
        mountcheckdirs(vp, newdp);
        vrele(newdp);
        if ((mp->mnt_flag & MNT_RDONLY) == 0)
                vfs_allocate_syncvnode(mp);
        vfs_unbusy(mp);
        return (0);
}

/*
 * vfs_domount_update(): update of mounted file system
 */
static int
vfs_domount_update(
        struct thread *td,              /* Calling thread. */
        struct vnode *vp,               /* Mount point vnode. */
        uint64_t fsflags,               /* Flags common to all filesystems. */
        struct vfsoptlist **optlist     /* Options local to the filesystem. */
        )
{
        struct oexport_args oexport;
        struct export_args export;
        struct mount *mp;
        int error, export_error;
        uint64_t flag;

        mtx_assert(&Giant, MA_OWNED);
        ASSERT_VOP_ELOCKED(vp, __func__);
        KASSERT((fsflags & MNT_UPDATE) != 0, ("MNT_UPDATE should be here"));

        if ((vp->v_vflag & VV_ROOT) == 0) {
                vput(vp);
                return (EINVAL);
        }
        mp = vp->v_mount;
        /*
         * We only allow the filesystem to be reloaded if it
         * is currently mounted read-only.
         */
        flag = mp->mnt_flag;
        if ((fsflags & MNT_RELOAD) != 0 && (flag & MNT_RDONLY) == 0) {
                vput(vp);
                return (EOPNOTSUPP);    /* Needs translation */
        }
        /*
         * Only privileged root, or (if MNT_USER is set) the user that
         * did the original mount is permitted to update it.
         */
        error = vfs_suser(mp, td);
        if (error != 0) {
                vput(vp);
                return (error);
        }
        if (vfs_busy(mp, MBF_NOWAIT)) {
                vput(vp);
                return (EBUSY);
        }
        VI_LOCK(vp);
        if ((vp->v_iflag & VI_MOUNT) != 0 || vp->v_mountedhere != NULL) {
                VI_UNLOCK(vp);
                vfs_unbusy(mp);
                vput(vp);
                return (EBUSY);
        }
        vp->v_iflag |= VI_MOUNT;
        VI_UNLOCK(vp);
        VOP_UNLOCK(vp, 0);

        MNT_ILOCK(mp);
        mp->mnt_flag &= ~MNT_UPDATEMASK;
        mp->mnt_flag |= fsflags & (MNT_RELOAD | MNT_FORCE | MNT_UPDATE |
            MNT_SNAPSHOT | MNT_ROOTFS | MNT_UPDATEMASK | MNT_RDONLY);
        if ((mp->mnt_flag & MNT_ASYNC) == 0)
                mp->mnt_kern_flag &= ~MNTK_ASYNC;
        MNT_IUNLOCK(mp);
        mp->mnt_optnew = *optlist;
        vfs_mergeopts(mp->mnt_optnew, mp->mnt_opt);

        /*
         * Mount the filesystem.
         * XXX The final recipients of VFS_MOUNT just overwrite the ndp they
         * get.  No freeing of cn_pnbuf.
         */
        error = VFS_MOUNT(mp);

        export_error = 0;
        if (error == 0) {
                /* Process the export option. */
                if (vfs_copyopt(mp->mnt_optnew, "export", &export,
                    sizeof(export)) == 0) {
                        export_error = vfs_export(mp, &export);
                } else if (vfs_copyopt(mp->mnt_optnew, "export", &oexport,
                    sizeof(oexport)) == 0) {
                        export.ex_flags = oexport.ex_flags;
                        export.ex_root = oexport.ex_root;
                        export.ex_anon = oexport.ex_anon;
                        export.ex_addr = oexport.ex_addr;
                        export.ex_addrlen = oexport.ex_addrlen;
                        export.ex_mask = oexport.ex_mask;
                        export.ex_masklen = oexport.ex_masklen;
                        export.ex_indexfile = oexport.ex_indexfile;
                        export.ex_numsecflavors = 0;
                        export_error = vfs_export(mp, &export);
                }
        }

        MNT_ILOCK(mp);
        if (error == 0) {
                mp->mnt_flag &= ~(MNT_UPDATE | MNT_RELOAD | MNT_FORCE |
                    MNT_SNAPSHOT);
        } else {
                /*
                 * If we fail, restore old mount flags. MNT_QUOTA is special,
                 * because it is not part of MNT_UPDATEMASK, but it could have
                 * changed in the meantime if quotactl(2) was called.
                 * All in all we want current value of MNT_QUOTA, not the old
                 * one.
                 */
                mp->mnt_flag = (mp->mnt_flag & MNT_QUOTA) | (flag & ~MNT_QUOTA);
        }
        if ((mp->mnt_flag & MNT_ASYNC) != 0 &&
            (mp->mnt_kern_flag & MNTK_NOASYNC) == 0)
                mp->mnt_kern_flag |= MNTK_ASYNC;
        else
                mp->mnt_kern_flag &= ~MNTK_ASYNC;
        MNT_IUNLOCK(mp);

        if (error != 0)
                goto end;

        if (mp->mnt_opt != NULL)
                vfs_freeopts(mp->mnt_opt);
        mp->mnt_opt = mp->mnt_optnew;
        *optlist = NULL;
        (void)VFS_STATFS(mp, &mp->mnt_stat);
        /*
         * Prevent external consumers of mount options from reading
         * mnt_optnew.
         */
        mp->mnt_optnew = NULL;

        if ((mp->mnt_flag & MNT_RDONLY) == 0)
                vfs_allocate_syncvnode(mp);
        else
                vfs_deallocate_syncvnode(mp);
end:
        vfs_unbusy(mp);
        VI_LOCK(vp);
        vp->v_iflag &= ~VI_MOUNT;
        VI_UNLOCK(vp);
        vrele(vp);
        return (error != 0 ? error : export_error);
}

/*
 * vfs_domount(): actually attempt a filesystem mount.
 */
static int
vfs_domount(
        struct thread *td,              /* Calling thread. */
        const char *fstype,             /* Filesystem type. */
        char *fspath,                   /* Mount path. */
        uint64_t fsflags,               /* Flags common to all filesystems. */
        struct vfsoptlist **optlist     /* Options local to the filesystem. */
        )
{
        struct vfsconf *vfsp;
        struct nameidata nd;
        struct vnode *vp;
        char *pathbuf;
        int error;

        /*
         * Be ultra-paranoid about making sure the type and fspath
         * variables will fit in our mp buffers, including the
         * terminating NUL.
         */
        if (strlen(fstype) >= MFSNAMELEN || strlen(fspath) >= MNAMELEN)
                return (ENAMETOOLONG);

        if (jailed(td->td_ucred) || usermount == 0) {
                if ((error = priv_check(td, PRIV_VFS_MOUNT)) != 0)
                        return (error);
        }

        /*
         * Do not allow NFS export or MNT_SUIDDIR by unprivileged users.
         */
        if (fsflags & MNT_EXPORTED) {
                error = priv_check(td, PRIV_VFS_MOUNT_EXPORTED);
                if (error)
                        return (error);
        }
        if (fsflags & MNT_SUIDDIR) {
                error = priv_check(td, PRIV_VFS_MOUNT_SUIDDIR);
                if (error)
                        return (error);
        }
        /*
         * Silently enforce MNT_NOSUID and MNT_USER for unprivileged users.
         */
        if ((fsflags & (MNT_NOSUID | MNT_USER)) != (MNT_NOSUID | MNT_USER)) {
                if (priv_check(td, PRIV_VFS_MOUNT_NONUSER) != 0)
                        fsflags |= MNT_NOSUID | MNT_USER;
        }

        /* Load KLDs before we lock the covered vnode to avoid reversals. */
        vfsp = NULL;
        if ((fsflags & MNT_UPDATE) == 0) {
                /* Don't try to load KLDs if we're mounting the root. */
                if (fsflags & MNT_ROOTFS)
                        vfsp = vfs_byname(fstype);
                else
                        vfsp = vfs_byname_kld(fstype, td, &error);
                if (vfsp == NULL)
                        return (ENODEV);
                if (jailed(td->td_ucred) && !(vfsp->vfc_flags & VFCF_JAIL))
                        return (EPERM);
        }

        /*
         * Get vnode to be covered or mount point's vnode in case of MNT_UPDATE.
         */
        NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF | MPSAFE | AUDITVNODE1,
            UIO_SYSSPACE, fspath, td);
        error = namei(&nd);
        if (error != 0)
                return (error);
        if (!NDHASGIANT(&nd))
                mtx_lock(&Giant);
        NDFREE(&nd, NDF_ONLY_PNBUF);
        vp = nd.ni_vp;
        if ((fsflags & MNT_UPDATE) == 0) {
                pathbuf = malloc(MNAMELEN, M_TEMP, M_WAITOK);
                strcpy(pathbuf, fspath);
                error = vn_path_to_global_path(td, vp, pathbuf, MNAMELEN);
                /* debug.disablefullpath == 1 results in ENODEV */
                if (error == 0 || error == ENODEV) {
                        error = vfs_domount_first(td, vfsp, pathbuf, vp,
                            fsflags, optlist);
                }
                free(pathbuf, M_TEMP);
        } else
                error = vfs_domount_update(td, vp, fsflags, optlist);
        mtx_unlock(&Giant);

        ASSERT_VI_UNLOCKED(vp, __func__);
        ASSERT_VOP_UNLOCKED(vp, __func__);

        return (error);
}

/*
 * Unmount a filesystem.
 *
 * Note: unmount takes a path to the vnode mounted on as argument, not
 * special file (as before).
 */
#ifndef _SYS_SYSPROTO_H_
struct unmount_args {
        char    *path;
        int     flags;
};
#endif
/* ARGSUSED */
int
sys_unmount(td, uap)
        struct thread *td;
        register struct unmount_args /* {
                char *path;
                int flags;
        } */ *uap;
{
        struct nameidata nd;
        struct mount *mp;
        char *pathbuf;
        int error, id0, id1, vfslocked;

        AUDIT_ARG_VALUE(uap->flags);
        if (jailed(td->td_ucred) || usermount == 0) {
                error = priv_check(td, PRIV_VFS_UNMOUNT);
                if (error)
                        return (error);
        }

        pathbuf = malloc(MNAMELEN, M_TEMP, M_WAITOK);
        error = copyinstr(uap->path, pathbuf, MNAMELEN, NULL);
        if (error) {
                free(pathbuf, M_TEMP);
                return (error);
        }
        mtx_lock(&Giant);
        if (uap->flags & MNT_BYFSID) {
                AUDIT_ARG_TEXT(pathbuf);
                /* Decode the filesystem ID. */
                if (sscanf(pathbuf, "FSID:%d:%d", &id0, &id1) != 2) {
                        mtx_unlock(&Giant);
                        free(pathbuf, M_TEMP);
                        return (EINVAL);
                }

                mtx_lock(&mountlist_mtx);
                TAILQ_FOREACH_REVERSE(mp, &mountlist, mntlist, mnt_list) {
                        if (mp->mnt_stat.f_fsid.val[0] == id0 &&
                            mp->mnt_stat.f_fsid.val[1] == id1)
                                break;
                }
                mtx_unlock(&mountlist_mtx);
        } else {
                /*
                 * Try to find global path for path argument.
                 */
                NDINIT(&nd, LOOKUP,
                    FOLLOW | LOCKLEAF | MPSAFE | AUDITVNODE1,
                    UIO_SYSSPACE, pathbuf, td);
                if (namei(&nd) == 0) {
                        vfslocked = NDHASGIANT(&nd);
                        NDFREE(&nd, NDF_ONLY_PNBUF);
                        error = vn_path_to_global_path(td, nd.ni_vp, pathbuf,
                            MNAMELEN);
                        if (error == 0 || error == ENODEV)
                                vput(nd.ni_vp);
                        VFS_UNLOCK_GIANT(vfslocked);
                }
                mtx_lock(&mountlist_mtx);
                TAILQ_FOREACH_REVERSE(mp, &mountlist, mntlist, mnt_list) {
                        if (strcmp(mp->mnt_stat.f_mntonname, pathbuf) == 0)
                                break;
                }
                mtx_unlock(&mountlist_mtx);
        }
        free(pathbuf, M_TEMP);
        if (mp == NULL) {
                /*
                 * Previously we returned ENOENT for a nonexistent path and
                 * EINVAL for a non-mountpoint.  We cannot tell these apart
                 * now, so in the !MNT_BYFSID case return the more likely
                 * EINVAL for compatibility.
                 */
                mtx_unlock(&Giant);
                return ((uap->flags & MNT_BYFSID) ? ENOENT : EINVAL);
        }

        /*
         * Don't allow unmounting the root filesystem.
         */
        if (mp->mnt_flag & MNT_ROOTFS) {
                mtx_unlock(&Giant);
                return (EINVAL);
        }
        error = dounmount(mp, uap->flags, td);
        mtx_unlock(&Giant);
        return (error);
}

/*
 * Do the actual filesystem unmount.
 */
int
dounmount(mp, flags, td)
        struct mount *mp;
        int flags;
        struct thread *td;
{
        struct vnode *coveredvp, *fsrootvp;
        int error;
        uint64_t async_flag;
        int mnt_gen_r;

        mtx_assert(&Giant, MA_OWNED);

        if ((coveredvp = mp->mnt_vnodecovered) != NULL) {
                mnt_gen_r = mp->mnt_gen;
                VI_LOCK(coveredvp);
                vholdl(coveredvp);
                vn_lock(coveredvp, LK_EXCLUSIVE | LK_INTERLOCK | LK_RETRY);
                vdrop(coveredvp);
                /*
                 * Check for mp being unmounted while waiting for the
                 * covered vnode lock.
                 */
                if (coveredvp->v_mountedhere != mp ||
                    coveredvp->v_mountedhere->mnt_gen != mnt_gen_r) {
                        VOP_UNLOCK(coveredvp, 0);
                        return (EBUSY);
                }
        }
        /*
         * Only privileged root, or (if MNT_USER is set) the user that did the
         * original mount is permitted to unmount this filesystem.
         */
        error = vfs_suser(mp, td);
        if (error) {
                if (coveredvp)
                        VOP_UNLOCK(coveredvp, 0);
                return (error);
        }

        vn_start_write(NULL, &mp, V_WAIT);
        MNT_ILOCK(mp);
        if ((mp->mnt_kern_flag & MNTK_UNMOUNT) != 0 ||
            !TAILQ_EMPTY(&mp->mnt_uppers)) {
                MNT_IUNLOCK(mp);
                if (coveredvp)
                        VOP_UNLOCK(coveredvp, 0);
                vn_finished_write(mp);
                return (EBUSY);
        }
        mp->mnt_kern_flag |= MNTK_UNMOUNT | MNTK_NOINSMNTQ;
        /* Allow filesystems to detect that a forced unmount is in progress. */
        if (flags & MNT_FORCE)
                mp->mnt_kern_flag |= MNTK_UNMOUNTF;
        error = 0;
        if (mp->mnt_lockref) {
                mp->mnt_kern_flag |= MNTK_DRAINING;
                error = msleep(&mp->mnt_lockref, MNT_MTX(mp), PVFS,
                    "mount drain", 0);
        }
        MNT_IUNLOCK(mp);
        KASSERT(mp->mnt_lockref == 0,
            ("%s: invalid lock refcount in the drain path @ %s:%d",
            __func__, __FILE__, __LINE__));
        KASSERT(error == 0,
            ("%s: invalid return value for msleep in the drain path @ %s:%d",
            __func__, __FILE__, __LINE__));

        if (mp->mnt_flag & MNT_EXPUBLIC)
                vfs_setpublicfs(NULL, NULL, NULL);

        vfs_msync(mp, MNT_WAIT);
        MNT_ILOCK(mp);
        async_flag = mp->mnt_flag & MNT_ASYNC;
        mp->mnt_flag &= ~MNT_ASYNC;
        mp->mnt_kern_flag &= ~MNTK_ASYNC;
        MNT_IUNLOCK(mp);
        cache_purgevfs(mp);     /* remove cache entries for this file sys */
        vfs_deallocate_syncvnode(mp);
        /*
         * For forced unmounts, move process cdir/rdir refs on the fs root
         * vnode to the covered vnode.  For non-forced unmounts we want
         * such references to cause an EBUSY error.
         */
        if ((flags & MNT_FORCE) &&
            VFS_ROOT(mp, LK_EXCLUSIVE, &fsrootvp) == 0) {
                if (mp->mnt_vnodecovered != NULL)
                        mountcheckdirs(fsrootvp, mp->mnt_vnodecovered);
                if (fsrootvp == rootvnode) {
                        vrele(rootvnode);
                        rootvnode = NULL;
                }
                vput(fsrootvp);
        }
        if (((mp->mnt_flag & MNT_RDONLY) ||
             (error = VFS_SYNC(mp, MNT_WAIT)) == 0) || (flags & MNT_FORCE) != 0)
                error = VFS_UNMOUNT(mp, flags);
        vn_finished_write(mp);
        /*
         * If we failed to flush the dirty blocks for this mount point,
         * undo all the cdir/rdir and rootvnode changes we made above.
         * Unless we failed to do so because the device is reporting that
         * it doesn't exist anymore.
         */
        if (error && error != ENXIO) {
                if ((flags & MNT_FORCE) &&
                    VFS_ROOT(mp, LK_EXCLUSIVE, &fsrootvp) == 0) {
                        if (mp->mnt_vnodecovered != NULL)
                                mountcheckdirs(mp->mnt_vnodecovered, fsrootvp);
                        if (rootvnode == NULL) {
                                rootvnode = fsrootvp;
                                vref(rootvnode);
                        }
                        vput(fsrootvp);
                }
                MNT_ILOCK(mp);
                mp->mnt_kern_flag &= ~MNTK_NOINSMNTQ;
                if ((mp->mnt_flag & MNT_RDONLY) == 0) {
                        MNT_IUNLOCK(mp);
                        vfs_allocate_syncvnode(mp);
                        MNT_ILOCK(mp);
                }
                mp->mnt_kern_flag &= ~(MNTK_UNMOUNT | MNTK_UNMOUNTF);
                mp->mnt_flag |= async_flag;
                if ((mp->mnt_flag & MNT_ASYNC) != 0 &&
                    (mp->mnt_kern_flag & MNTK_NOASYNC) == 0)
                        mp->mnt_kern_flag |= MNTK_ASYNC;
                if (mp->mnt_kern_flag & MNTK_MWAIT) {
                        mp->mnt_kern_flag &= ~MNTK_MWAIT;
                        wakeup(mp);
                }
                MNT_IUNLOCK(mp);
                if (coveredvp)
                        VOP_UNLOCK(coveredvp, 0);
                return (error);
        }
        mtx_lock(&mountlist_mtx);
        TAILQ_REMOVE(&mountlist, mp, mnt_list);
        mtx_unlock(&mountlist_mtx);
        if (coveredvp != NULL) {
                coveredvp->v_mountedhere = NULL;
                vput(coveredvp);
        }
        vfs_event_signal(NULL, VQ_UNMOUNT, 0);
        vfs_mount_destroy(mp);
        return (0);
}

/*
 * Report errors during filesystem mounting.
 */
void
vfs_mount_error(struct mount *mp, const char *fmt, ...)
{
        struct vfsoptlist *moptlist = mp->mnt_optnew;
        va_list ap;
        int error, len;
        char *errmsg;

        error = vfs_getopt(moptlist, "errmsg", (void **)&errmsg, &len);
        if (error || errmsg == NULL || len <= 0)
                return;

        va_start(ap, fmt);
        vsnprintf(errmsg, (size_t)len, fmt, ap);
        va_end(ap);
}

void
vfs_opterror(struct vfsoptlist *opts, const char *fmt, ...)
{
        va_list ap;
        int error, len;
        char *errmsg;

        error = vfs_getopt(opts, "errmsg", (void **)&errmsg, &len);
        if (error || errmsg == NULL || len <= 0)
                return;

        va_start(ap, fmt);
        vsnprintf(errmsg, (size_t)len, fmt, ap);
        va_end(ap);
}

/*
 * ---------------------------------------------------------------------
 * Functions for querying mount options/arguments from filesystems.
 */

/*
 * Check that no unknown options are given
 */
int
vfs_filteropt(struct vfsoptlist *opts, const char **legal)
{
        struct vfsopt *opt;
        char errmsg[255];
        const char **t, *p, *q;
        int ret = 0;

        TAILQ_FOREACH(opt, opts, link) {
                p = opt->name;
                q = NULL;
                if (p[0] == 'n' && p[1] == 'o')
                        q = p + 2;
                for(t = global_opts; *t != NULL; t++) {
                        if (strcmp(*t, p) == 0)
                                break;
                        if (q != NULL) {
                                if (strcmp(*t, q) == 0)
                                        break;
                        }
                }
                if (*t != NULL)
                        continue;
                for(t = legal; *t != NULL; t++) {
                        if (strcmp(*t, p) == 0)
                                break;
                        if (q != NULL) {
                                if (strcmp(*t, q) == 0)
                                        break;
                        }
                }
                if (*t != NULL)
                        continue;
                snprintf(errmsg, sizeof(errmsg),
                    "mount option <%s> is unknown", p);
                ret = EINVAL;
        }
        if (ret != 0) {
                TAILQ_FOREACH(opt, opts, link) {
                        if (strcmp(opt->name, "errmsg") == 0) {
                                strncpy((char *)opt->value, errmsg, opt->len);
                                break;
                        }
                }
                if (opt == NULL)
                        printf("%s\n", errmsg);
        }
        return (ret);
}

/*
 * Get a mount option by its name.
 *
 * Return 0 if the option was found, ENOENT otherwise.
 * If len is non-NULL it will be filled with the length
 * of the option. If buf is non-NULL, it will be filled
 * with the address of the option.
 */
int
vfs_getopt(opts, name, buf, len)
        struct vfsoptlist *opts;
        const char *name;
        void **buf;
        int *len;
{
        struct vfsopt *opt;

        KASSERT(opts != NULL, ("vfs_getopt: caller passed 'opts' as NULL"));

        TAILQ_FOREACH(opt, opts, link) {
                if (strcmp(name, opt->name) == 0) {
                        opt->seen = 1;
                        if (len != NULL)
                                *len = opt->len;
                        if (buf != NULL)
                                *buf = opt->value;
                        return (0);
                }
        }
        return (ENOENT);
}

int
vfs_getopt_pos(struct vfsoptlist *opts, const char *name)
{
        struct vfsopt *opt;

        if (opts == NULL)
                return (-1);

        TAILQ_FOREACH(opt, opts, link) {
                if (strcmp(name, opt->name) == 0) {
                        opt->seen = 1;
                        return (opt->pos);
                }
        }
        return (-1);
}

char *
vfs_getopts(struct vfsoptlist *opts, const char *name, int *error)
{
        struct vfsopt *opt;

        *error = 0;
        TAILQ_FOREACH(opt, opts, link) {
                if (strcmp(name, opt->name) != 0)
                        continue;
                opt->seen = 1;
                if (opt->len == 0 ||
                    ((char *)opt->value)[opt->len - 1] != '\0') {
                        *error = EINVAL;
                        return (NULL);
                }
                return (opt->value);
        }
        *error = ENOENT;
        return (NULL);
}

int
vfs_flagopt(struct vfsoptlist *opts, const char *name, uint64_t *w,
        uint64_t val)
{
        struct vfsopt *opt;

        TAILQ_FOREACH(opt, opts, link) {
                if (strcmp(name, opt->name) == 0) {
                        opt->seen = 1;
                        if (w != NULL)
                                *w |= val;
                        return (1);
                }
        }
        if (w != NULL)
                *w &= ~val;
        return (0);
}

int
vfs_scanopt(struct vfsoptlist *opts, const char *name, const char *fmt, ...)
{
        va_list ap;
        struct vfsopt *opt;
        int ret;

        KASSERT(opts != NULL, ("vfs_getopt: caller passed 'opts' as NULL"));

        TAILQ_FOREACH(opt, opts, link) {
                if (strcmp(name, opt->name) != 0)
                        continue;
                opt->seen = 1;
                if (opt->len == 0 || opt->value == NULL)
                        return (0);
                if (((char *)opt->value)[opt->len - 1] != '\0')
                        return (0);
                va_start(ap, fmt);
                ret = vsscanf(opt->value, fmt, ap);
                va_end(ap);
                return (ret);
        }
        return (0);
}

int
vfs_setopt(struct vfsoptlist *opts, const char *name, void *value, int len)
{
        struct vfsopt *opt;

        TAILQ_FOREACH(opt, opts, link) {
                if (strcmp(name, opt->name) != 0)
                        continue;
                opt->seen = 1;
                if (opt->value == NULL)
                        opt->len = len;
                else {
                        if (opt->len != len)
                                return (EINVAL);
                        bcopy(value, opt->value, len);
                }
                return (0);
        }
        return (ENOENT);
}

int
vfs_setopt_part(struct vfsoptlist *opts, const char *name, void *value, int len)
{
        struct vfsopt *opt;

        TAILQ_FOREACH(opt, opts, link) {
                if (strcmp(name, opt->name) != 0)
                        continue;
                opt->seen = 1;
                if (opt->value == NULL)
                        opt->len = len;
                else {
                        if (opt->len < len)
                                return (EINVAL);
                        opt->len = len;
                        bcopy(value, opt->value, len);
                }
                return (0);
        }
        return (ENOENT);
}

int
vfs_setopts(struct vfsoptlist *opts, const char *name, const char *value)
{
        struct vfsopt *opt;

        TAILQ_FOREACH(opt, opts, link) {
                if (strcmp(name, opt->name) != 0)
                        continue;
                opt->seen = 1;
                if (opt->value == NULL)
                        opt->len = strlen(value) + 1;
                else if (strlcpy(opt->value, value, opt->len) >= opt->len)
                        return (EINVAL);
                return (0);
        }
        return (ENOENT);
}

/*
 * Find and copy a mount option.
 *
 * The size of the buffer has to be specified
 * in len, if it is not the same length as the
 * mount option, EINVAL is returned.
 * Returns ENOENT if the option is not found.
 */
int
vfs_copyopt(opts, name, dest, len)
        struct vfsoptlist *opts;
        const char *name;
        void *dest;
        int len;
{
        struct vfsopt *opt;

        KASSERT(opts != NULL, ("vfs_copyopt: caller passed 'opts' as NULL"));

        TAILQ_FOREACH(opt, opts, link) {
                if (strcmp(name, opt->name) == 0) {
                        opt->seen = 1;
                        if (len != opt->len)
                                return (EINVAL);
                        bcopy(opt->value, dest, opt->len);
                        return (0);
                }
        }
        return (ENOENT);
}

/*
 * These are helper functions for filesystems to traverse all
 * their vnodes.  See MNT_VNODE_FOREACH() in sys/mount.h.
 *
 * This interface has been deprecated in favor of MNT_VNODE_FOREACH_ALL.
 */

MALLOC_DECLARE(M_VNODE_MARKER);

struct vnode *
__mnt_vnode_next(struct vnode **mvp, struct mount *mp)
{
        struct vnode *vp;

        mtx_assert(MNT_MTX(mp), MA_OWNED);

        KASSERT((*mvp)->v_mount == mp, ("marker vnode mount list mismatch"));
        if (should_yield()) {
                MNT_IUNLOCK(mp);
                kern_yield(PRI_UNCHANGED);
                MNT_ILOCK(mp);
        }
        vp = TAILQ_NEXT(*mvp, v_nmntvnodes);
        while (vp != NULL && vp->v_type == VMARKER)
                vp = TAILQ_NEXT(vp, v_nmntvnodes);

        /* Check if we are done */
        if (vp == NULL) {
                __mnt_vnode_markerfree(mvp, mp);
                return (NULL);
        }
        TAILQ_REMOVE(&mp->mnt_nvnodelist, *mvp, v_nmntvnodes);
        TAILQ_INSERT_AFTER(&mp->mnt_nvnodelist, vp, *mvp, v_nmntvnodes);
        return (vp);
}

struct vnode *
__mnt_vnode_first(struct vnode **mvp, struct mount *mp)
{
        struct vnode *vp;

        mtx_assert(MNT_MTX(mp), MA_OWNED);

        vp = TAILQ_FIRST(&mp->mnt_nvnodelist);
        while (vp != NULL && vp->v_type == VMARKER)
                vp = TAILQ_NEXT(vp, v_nmntvnodes);

        /* Check if we are done */
        if (vp == NULL) {
                *mvp = NULL;
                return (NULL);
        }
        MNT_REF(mp);
        MNT_IUNLOCK(mp);
        *mvp = (struct vnode *) malloc(sizeof(struct vnode),
                                       M_VNODE_MARKER,
                                       M_WAITOK | M_ZERO);
        MNT_ILOCK(mp);
        (*mvp)->v_type = VMARKER;

        vp = TAILQ_FIRST(&mp->mnt_nvnodelist);
        while (vp != NULL && vp->v_type == VMARKER)
                vp = TAILQ_NEXT(vp, v_nmntvnodes);

        /* Check if we are done */
        if (vp == NULL) {
                MNT_IUNLOCK(mp);
                free(*mvp, M_VNODE_MARKER);
                MNT_ILOCK(mp);
                *mvp = NULL;
                MNT_REL(mp);
                return (NULL);
        }
        (*mvp)->v_mount = mp;
        TAILQ_INSERT_AFTER(&mp->mnt_nvnodelist, vp, *mvp, v_nmntvnodes);
        return (vp);
}


void
__mnt_vnode_markerfree(struct vnode **mvp, struct mount *mp)
{

        if (*mvp == NULL)
                return;

        mtx_assert(MNT_MTX(mp), MA_OWNED);

        KASSERT((*mvp)->v_mount == mp, ("marker vnode mount list mismatch"));
        TAILQ_REMOVE(&mp->mnt_nvnodelist, *mvp, v_nmntvnodes);
        MNT_IUNLOCK(mp);
        free(*mvp, M_VNODE_MARKER);
        MNT_ILOCK(mp);
        *mvp = NULL;
        MNT_REL(mp);
}

int
__vfs_statfs(struct mount *mp, struct statfs *sbp)
{
        int error;

        error = mp->mnt_op->vfs_statfs(mp, &mp->mnt_stat);
        if (sbp != &mp->mnt_stat)
                *sbp = mp->mnt_stat;
        return (error);
}

void
vfs_mountedfrom(struct mount *mp, const char *from)
{

        bzero(mp->mnt_stat.f_mntfromname, sizeof mp->mnt_stat.f_mntfromname);
        strlcpy(mp->mnt_stat.f_mntfromname, from,
            sizeof mp->mnt_stat.f_mntfromname);
}

/*
 * ---------------------------------------------------------------------
 * This is the api for building mount args and mounting filesystems from
 * inside the kernel.
 *
 * The API works by accumulation of individual args.  First error is
 * latched.
 *
 * XXX: should be documented in new manpage kernel_mount(9)
 */

/* A memory allocation which must be freed when we are done */
struct mntaarg {
        SLIST_ENTRY(mntaarg)    next;
};

/* The header for the mount arguments */
struct mntarg {
        struct iovec *v;
        int len;
        int error;
        SLIST_HEAD(, mntaarg)   list;
};

/*
 * Add a boolean argument.
 *
 * flag is the boolean value.
 * name must start with "no".
 */
struct mntarg *
mount_argb(struct mntarg *ma, int flag, const char *name)
{

        KASSERT(name[0] == 'n' && name[1] == 'o',
            ("mount_argb(...,%s): name must start with 'no'", name));

        return (mount_arg(ma, name + (flag ? 2 : 0), NULL, 0));
}

/*
 * Add an argument printf style
 */
struct mntarg *
mount_argf(struct mntarg *ma, const char *name, const char *fmt, ...)
{
        va_list ap;
        struct mntaarg *maa;
        struct sbuf *sb;
        int len;

        if (ma == NULL) {
                ma = malloc(sizeof *ma, M_MOUNT, M_WAITOK | M_ZERO);
                SLIST_INIT(&ma->list);
        }
        if (ma->error)
                return (ma);

        ma->v = realloc(ma->v, sizeof *ma->v * (ma->len + 2),
            M_MOUNT, M_WAITOK);
        ma->v[ma->len].iov_base = (void *)(uintptr_t)name;
        ma->v[ma->len].iov_len = strlen(name) + 1;
        ma->len++;

        sb = sbuf_new_auto();
        va_start(ap, fmt);
        sbuf_vprintf(sb, fmt, ap);
        va_end(ap);
        sbuf_finish(sb);
        len = sbuf_len(sb) + 1;
        maa = malloc(sizeof *maa + len, M_MOUNT, M_WAITOK | M_ZERO);
        SLIST_INSERT_HEAD(&ma->list, maa, next);
        bcopy(sbuf_data(sb), maa + 1, len);
        sbuf_delete(sb);

        ma->v[ma->len].iov_base = maa + 1;
        ma->v[ma->len].iov_len = len;
        ma->len++;

        return (ma);
}

/*
 * Add an argument which is a userland string.
 */
struct mntarg *
mount_argsu(struct mntarg *ma, const char *name, const void *val, int len)
{
        struct mntaarg *maa;
        char *tbuf;

        if (val == NULL)
                return (ma);
        if (ma == NULL) {
                ma = malloc(sizeof *ma, M_MOUNT, M_WAITOK | M_ZERO);
                SLIST_INIT(&ma->list);
        }
        if (ma->error)
                return (ma);
        maa = malloc(sizeof *maa + len, M_MOUNT, M_WAITOK | M_ZERO);
        SLIST_INSERT_HEAD(&ma->list, maa, next);
        tbuf = (void *)(maa + 1);
        ma->error = copyinstr(val, tbuf, len, NULL);
        return (mount_arg(ma, name, tbuf, -1));
}

/*
 * Plain argument.
 *
 * If length is -1, treat value as a C string.
 */
struct mntarg *
mount_arg(struct mntarg *ma, const char *name, const void *val, int len)
{

        if (ma == NULL) {
                ma = malloc(sizeof *ma, M_MOUNT, M_WAITOK | M_ZERO);
                SLIST_INIT(&ma->list);
        }
        if (ma->error)
                return (ma);

        ma->v = realloc(ma->v, sizeof *ma->v * (ma->len + 2),
            M_MOUNT, M_WAITOK);
        ma->v[ma->len].iov_base = (void *)(uintptr_t)name;
        ma->v[ma->len].iov_len = strlen(name) + 1;
        ma->len++;

        ma->v[ma->len].iov_base = (void *)(uintptr_t)val;
        if (len < 0)
                ma->v[ma->len].iov_len = strlen(val) + 1;
        else
                ma->v[ma->len].iov_len = len;
        ma->len++;
        return (ma);
}

/*
 * Free a mntarg structure
 */
static void
free_mntarg(struct mntarg *ma)
{
        struct mntaarg *maa;

        while (!SLIST_EMPTY(&ma->list)) {
                maa = SLIST_FIRST(&ma->list);
                SLIST_REMOVE_HEAD(&ma->list, next);
                free(maa, M_MOUNT);
        }
        free(ma->v, M_MOUNT);
        free(ma, M_MOUNT);
}

/*
 * Mount a filesystem
 */
int
kernel_mount(struct mntarg *ma, uint64_t flags)
{
        struct uio auio;
        int error;

        KASSERT(ma != NULL, ("kernel_mount NULL ma"));
        KASSERT(ma->v != NULL, ("kernel_mount NULL ma->v"));
        KASSERT(!(ma->len & 1), ("kernel_mount odd ma->len (%d)", ma->len));

        auio.uio_iov = ma->v;
        auio.uio_iovcnt = ma->len;
        auio.uio_segflg = UIO_SYSSPACE;

        error = ma->error;
        if (!error)
                error = vfs_donmount(curthread, flags, &auio);
        free_mntarg(ma);
        return (error);
}

/*
 * A printflike function to mount a filesystem.
 */
int
kernel_vmount(int flags, ...)
{
        struct mntarg *ma = NULL;
        va_list ap;
        const char *cp;
        const void *vp;
        int error;

        va_start(ap, flags);
        for (;;) {
                cp = va_arg(ap, const char *);
                if (cp == NULL)
                        break;
                vp = va_arg(ap, const void *);
                ma = mount_arg(ma, cp, vp, (vp != NULL ? -1 : 0));
        }
        va_end(ap);

        error = kernel_mount(ma, flags);
        return (error);
}

void
vfs_oexport_conv(const struct oexport_args *oexp, struct export_args *exp)
{

        bcopy(oexp, exp, sizeof(*oexp));
        exp->ex_numsecflavors = 0;
}