Ignore machine-check MSRs

[freebsd-src/fkvm-freebsd.git] / sys / kern / vfs_mount.c

/*-
 * 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("$FreeBSD$");

#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/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>

#include "opt_rootdevname.h"
#include "opt_mac.h"

#define ROOTNAME                "root_device"
#define VFS_MOUNTARG_SIZE_MAX   (1024 * 64)

static int      vfs_domount(struct thread *td, const char *fstype,
                    char *fspath, int fsflags, void *fsdata);
static int      vfs_mountroot_ask(void);
static int      vfs_mountroot_try(const char *mountfrom);
static int      vfs_donmount(struct thread *td, int fsflags,
                    struct uio *fsoptions);
static void     free_mntarg(struct mntarg *ma);
static int      vfs_getopt_pos(struct vfsoptlist *opts, const char *name);

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");
MALLOC_DEFINE(M_VNODE_MARKER, "vnodemarker", "vnode marker");
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);

TAILQ_HEAD(vfsoptlist, vfsopt);
struct vfsopt {
        TAILQ_ENTRY(vfsopt) link;
        char    *name;
        void    *value;
        int     len;
};

/*
 * The vnode of the system's root (/ in the filesystem, without chroot
 * active.)
 */
struct vnode    *rootvnode;

/*
 * The root filesystem is detailed in the kernel environment variable
 * vfs.root.mountfrom, which is expected to be in the general format
 *
 * <vfsname>:[<path>]
 * vfsname   := the name of a VFS known to the kernel and capable
 *              of being mounted as root
 * path      := disk device name or other data used by the filesystem
 *              to locate its physical store
 */

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

/*
 * The root specifiers we will try if RB_CDROM is specified.
 */
static char *cdrom_rootdevnames[] = {
        "cd9660:cd0",
        "cd9660:acd0",
        NULL
};

/* legacy find-root code */
char            *rootdevnames[2] = {NULL, NULL};
#ifndef ROOTDEVNAME
#  define ROOTDEVNAME NULL
#endif
static const char       *ctrootdevname = ROOTDEVNAME;

/*
 * ---------------------------------------------------------------------
 * 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);
#ifdef INVARIANTS
        else if (opt->len != 0)
                panic("%s: mount option with NULL value but length != 0",
                    __func__);
#endif
        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);
        }
}

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

        /* "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);
        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.
 */
static int
vfs_buildopts(struct uio *auio, struct vfsoptlist **options)
{
        struct vfsoptlist *opts;
        struct vfsopt *opt;
        size_t memused;
        unsigned int i, iovcnt;
        int error, namelen, optlen;

        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) {
                opt = malloc(sizeof(struct vfsopt), M_MOUNT, M_WAITOK);
                namelen = auio->uio_iov[i].iov_len;
                optlen = auio->uio_iov[i + 1].iov_len;
                opt->name = malloc(namelen, M_MOUNT, M_WAITOK);
                opt->value = NULL;
                opt->len = 0;

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

                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 (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 if there is no matching "foo" option
 *     to be cancelled in the old options.  This is a bug
 *     if the option's canonical name is "foo".  E.g., "noro"
 *     shouldn't end up in the mount point's active options,
 *     but it can.
 */
static void
vfs_mergeopts(struct vfsoptlist *toopts, struct vfsoptlist *opts)
{
        struct vfsopt *opt, *opt2, *new;

        TAILQ_FOREACH(opt, opts, link) {
                /*
                 * Check that this option hasn't been redefined
                 * nor cancelled with a "no" mount option.
                 */
                opt2 = TAILQ_FIRST(toopts);
                while (opt2 != NULL) {
                        if (strcmp(opt2->name, opt->name) == 0)
                                goto next;
                        if (strncmp(opt2->name, "no", 2) == 0 &&
                            strcmp(opt2->name + 2, opt->name) == 0) {
                                vfs_freeopt(toopts, opt2);
                                goto next;
                        }
                        opt2 = TAILQ_NEXT(opt2, link);
                }
                /* We want this option, duplicate it. */
                new = malloc(sizeof(struct vfsopt), M_MOUNT, M_WAITOK);
                new->name = malloc(strlen(opt->name) + 1, M_MOUNT, M_WAITOK);
                strcpy(new->name, opt->name);
                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;
                TAILQ_INSERT_TAIL(toopts, new, link);
next:
                continue;
        }
}

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

        AUDIT_ARG(fflags, uap->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 in the kernel in vfs_mountroot_try().
         */
        uap->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))
                return (EINVAL);

        error = copyinuio(uap->iovp, iovcnt, &auio);
        if (error)
                return (error);
        iov = auio->uio_iov;
        for (i = 0; i < iovcnt; i++) {
                if (iov->iov_len > MMAXOPTIONLEN) {
                        free(auio, M_IOV);
                        return (EINVAL);
                }
                iov++;
        }
        error = vfs_donmount(td, uap->flags, auio);

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

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

void
vfs_ref(struct mount *mp)
{

        MNT_ILOCK(mp);
        MNT_REF(mp);
        MNT_IUNLOCK(mp);
}

void
vfs_rel(struct mount *mp)
{

        MNT_ILOCK(mp);
        MNT_REL(mp);
        MNT_IUNLOCK(mp);
}

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_lock, PVFS, "vfslock", 0, 0);
        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);
        lockdestroy(&mp->mnt_lock);
        mtx_destroy(&mp->mnt_mtx);
}

/*
 * 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;
        mp->mnt_ref = 0;
        (void) vfs_busy(mp, LK_NOWAIT, 0);
        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);
        return (mp);
}

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

        MNT_ILOCK(mp);
        for (i = 0; mp->mnt_ref && i < 3; i++)
                msleep(mp, MNT_MTX(mp), PVFS, "mntref", hz);
        /*
         * This will always cause a 3 second delay in rebooting due to
         * refs on the root mountpoint that never go away.  Most of these
         * are held by init which never exits.
         */
        if (i == 3 && (!rebooting || bootverbose))
                printf("Mount point %s had %d dangling refs\n",
                    mp->mnt_stat.f_mntonname, mp->mnt_ref);
        if (mp->mnt_holdcnt != 0) {
                printf("Waiting for mount point to be unheld\n");
                while (mp->mnt_holdcnt != 0) {
                        mp->mnt_holdcntwaiters++;
                        msleep(&mp->mnt_holdcnt, MNT_MTX(mp),
                               PZERO, "mntdestroy", 0);
                        mp->mnt_holdcntwaiters--;
                }
                printf("mount point unheld\n");
        }
        if (mp->mnt_writeopcount > 0) {
                printf("Waiting for mount point write ops\n");
                while (mp->mnt_writeopcount > 0) {
                        mp->mnt_kern_flag |= MNTK_SUSPEND;
                        msleep(&mp->mnt_writeopcount,
                               MNT_MTX(mp),
                               PZERO, "mntdestroy2", 0);
                }
                printf("mount point write ops completed\n");
        }
        if (mp->mnt_secondary_writes > 0) {
                printf("Waiting for mount point secondary write ops\n");
                while (mp->mnt_secondary_writes > 0) {
                        mp->mnt_kern_flag |= MNTK_SUSPEND;
                        msleep(&mp->mnt_secondary_writes,
                               MNT_MTX(mp),
                               PZERO, "mntdestroy3", 0);
                }
                printf("mount point secondary write ops completed\n");
        }
        MNT_IUNLOCK(mp);
        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");
        }
        MNT_ILOCK(mp);
        if (mp->mnt_kern_flag & MNTK_MWAIT)
                wakeup(mp);
        if (mp->mnt_writeopcount != 0)
                panic("vfs_mount_destroy: nonzero writeopcount");
        if (mp->mnt_secondary_writes != 0)
                panic("vfs_mount_destroy: nonzero secondary_writes");
        if (mp->mnt_nvnodelistsize != 0)
                panic("vfs_mount_destroy: nonzero nvnodelistsize");
        mp->mnt_writeopcount = -1000;
        mp->mnt_nvnodelistsize = -1000;
        mp->mnt_secondary_writes = -1000;
        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);
}

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

        errmsg = NULL;
        errmsg_len = 0;
        errmsg_pos = -1;
        has_rw = 0;
        has_noro = 0;

        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;
                        has_noro = 1;
                }
                else if (strcmp(opt->name, "rw") == 0) {
                        fsflags &= ~MNT_RDONLY;
                        has_rw = 1;
                }
                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;
        }

        /*
         * If "rw" was specified as a mount option, and we
         * are trying to update a mount-point from "ro" to "rw",
         * we need a mount option "noro", since in vfs_mergeopts(),
         * "noro" will cancel "ro", but "rw" will not do anything.
         */
        if (has_rw && !has_noro) {
                noro_opt = malloc(sizeof(struct vfsopt), M_MOUNT, M_WAITOK);
                noro_opt->name = strdup("noro", M_MOUNT);
                noro_opt->value = NULL;
                noro_opt->len = 0;
                TAILQ_INSERT_TAIL(optlist, noro_opt, link);
        }

        /*
         * 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;
        }

        mtx_lock(&Giant);
        error = vfs_domount(td, fstype, fspath, fsflags, optlist);
        mtx_unlock(&Giant);
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 (error != 0)
                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
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;
        int error;

        AUDIT_ARG(fflags, uap->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 in the kernel in vfs_mountroot_try().
         */
        uap->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, MNAMELEN);
        ma = mount_argsu(ma, "fspath", uap->path, MNAMELEN);
        ma = mount_argb(ma, uap->flags & MNT_RDONLY, "noro");
        ma = mount_argb(ma, !(uap->flags & MNT_NOSUID), "nosuid");
        ma = mount_argb(ma, !(uap->flags & MNT_NOEXEC), "noexec");

        error = vfsp->vfc_vfsops->vfs_cmount(ma, uap->data, uap->flags, td);
        mtx_unlock(&Giant);
        return (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. */
        int fsflags,            /* Flags common to all filesystems. */
        void *fsdata            /* Options local to the filesystem. */
        )
{
        struct vnode *vp;
        struct mount *mp;
        struct vfsconf *vfsp;
        struct export_args export;
        int error, flag = 0;
        struct vattr va;
        struct nameidata nd;

        mtx_assert(&Giant, MA_OWNED);
        /*
         * 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
         */
        NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF | AUDITVNODE1, UIO_SYSSPACE,
            fspath, td);
        if ((error = namei(&nd)) != 0)
                return (error);
        NDFREE(&nd, NDF_ONLY_PNBUF);
        vp = nd.ni_vp;
        if (fsflags & MNT_UPDATE) {
                if ((vp->v_vflag & VV_ROOT) == 0) {
                        vput(vp);
                        return (EINVAL);
                }
                mp = vp->v_mount;
                MNT_ILOCK(mp);
                flag = mp->mnt_flag;
                /*
                 * We only allow the filesystem to be reloaded if it
                 * is currently mounted read-only.
                 */
                if ((fsflags & MNT_RELOAD) &&
                    ((mp->mnt_flag & MNT_RDONLY) == 0)) {
                        MNT_IUNLOCK(mp);
                        vput(vp);
                        return (EOPNOTSUPP);    /* Needs translation */
                }
                MNT_IUNLOCK(mp);
                /*
                 * 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) {
                        vput(vp);
                        return (error);
                }
                if (vfs_busy(mp, LK_NOWAIT, 0)) {
                        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);
                MNT_ILOCK(mp);
                mp->mnt_flag |= fsflags &
                    (MNT_RELOAD | MNT_FORCE | MNT_UPDATE | MNT_SNAPSHOT | MNT_ROOTFS);
                MNT_IUNLOCK(mp);
                VOP_UNLOCK(vp, 0);
                mp->mnt_optnew = fsdata;
                vfs_mergeopts(mp->mnt_optnew, mp->mnt_opt);
        } else {
                /*
                 * 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) {
                        vput(vp);
                        return (error);
                }
                if (va.va_uid != td->td_ucred->cr_uid) {
                        error = priv_check_cred(td->td_ucred, PRIV_VFS_ADMIN,
                            0);
                        if (error) {
                                vput(vp);
                                return (error);
                        }
                }
                error = vinvalbuf(vp, V_SAVE, td, 0, 0);
                if (error != 0) {
                        vput(vp);
                        return (error);
                }
                if (vp->v_type != VDIR) {
                        vput(vp);
                        return (ENOTDIR);
                }
                VI_LOCK(vp);
                if ((vp->v_iflag & VI_MOUNT) != 0 ||
                    vp->v_mountedhere != NULL) {
                        VI_UNLOCK(vp);
                        vput(vp);
                        return (EBUSY);
                }
                vp->v_iflag |= VI_MOUNT;
                VI_UNLOCK(vp);

                /*
                 * Allocate and initialize the filesystem.
                 */
                mp = vfs_mount_alloc(vp, vfsp, fspath, td->td_ucred);
                VOP_UNLOCK(vp, 0);

                /* XXXMAC: pass to vfs_mount_alloc? */
                mp->mnt_optnew = fsdata;
        }

        /*
         * Set the mount level flags.
         */
        MNT_ILOCK(mp);
        mp->mnt_flag = (mp->mnt_flag & ~MNT_UPDATEMASK) |
                (fsflags & (MNT_UPDATEMASK | MNT_FORCE | MNT_ROOTFS |
                            MNT_RDONLY));
        if ((mp->mnt_flag & MNT_ASYNC) == 0)
                mp->mnt_kern_flag &= ~MNTK_ASYNC;
        MNT_IUNLOCK(mp);
        /*
         * 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, td);

        /*
         * Process the export option only if we are
         * updating mount options.
         */
        if (!error && (fsflags & MNT_UPDATE)) {
                if (vfs_copyopt(mp->mnt_optnew, "export", &export,
                    sizeof(export)) == 0)
                        error = vfs_export(mp, &export);
        }

        if (!error) {
                if (mp->mnt_opt != NULL)
                        vfs_freeopts(mp->mnt_opt);
                mp->mnt_opt = mp->mnt_optnew;
                (void)VFS_STATFS(mp, &mp->mnt_stat, td);
        }
        /*
         * Prevent external consumers of mount options from reading
         * mnt_optnew.
        */
        mp->mnt_optnew = NULL;
        if (mp->mnt_flag & MNT_UPDATE) {
                MNT_ILOCK(mp);
                if (error)
                        mp->mnt_flag = (mp->mnt_flag & MNT_QUOTA) |
                                (flag & ~MNT_QUOTA);
                else
                        mp->mnt_flag &= ~(MNT_UPDATE | MNT_RELOAD |
                                          MNT_FORCE | MNT_SNAPSHOT);
                if ((mp->mnt_flag & MNT_ASYNC) != 0 && mp->mnt_noasync == 0)
                        mp->mnt_kern_flag |= MNTK_ASYNC;
                else
                        mp->mnt_kern_flag &= ~MNTK_ASYNC;
                MNT_IUNLOCK(mp);
                if ((mp->mnt_flag & MNT_RDONLY) == 0) {
                        if (mp->mnt_syncer == NULL)
                                error = vfs_allocate_syncvnode(mp);
                } else {
                        if (mp->mnt_syncer != NULL)
                                vrele(mp->mnt_syncer);
                        mp->mnt_syncer = NULL;
                }
                vfs_unbusy(mp);
                VI_LOCK(vp);
                vp->v_iflag &= ~VI_MOUNT;
                VI_UNLOCK(vp);
                vrele(vp);
                return (error);
        }
        MNT_ILOCK(mp);
        if ((mp->mnt_flag & MNT_ASYNC) != 0 && mp->mnt_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);
        /*
         * Put the new filesystem on the mount list after root.
         */
        cache_purge(vp);
        if (!error) {
                struct vnode *newdp;

                VI_LOCK(vp);
                vp->v_iflag &= ~VI_MOUNT;
                VI_UNLOCK(vp);
                vp->v_mountedhere = mp;
                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, td))
                        panic("mount: lost mount");
                mountcheckdirs(vp, newdp);
                vput(newdp);
                VOP_UNLOCK(vp, 0);
                if ((mp->mnt_flag & MNT_RDONLY) == 0)
                        error = vfs_allocate_syncvnode(mp);
                vfs_unbusy(mp);
                if (error)
                        vrele(vp);
        } else {
                VI_LOCK(vp);
                vp->v_iflag &= ~VI_MOUNT;
                VI_UNLOCK(vp);
                vfs_unbusy(mp);
                vfs_mount_destroy(mp);
                vput(vp);
        }
        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
unmount(td, uap)
        struct thread *td;
        register struct unmount_args /* {
                char *path;
                int flags;
        } */ *uap;
{
        struct mount *mp;
        char *pathbuf;
        int error, id0, id1;

        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);
        }
        AUDIT_ARG(upath, td, pathbuf, ARG_UPATH1);
        mtx_lock(&Giant);
        if (uap->flags & MNT_BYFSID) {
                /* 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 {
                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;
        int 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);
        }

        MNT_ILOCK(mp);
        if (mp->mnt_kern_flag & MNTK_UNMOUNT) {
                MNT_IUNLOCK(mp);
                if (coveredvp)
                        VOP_UNLOCK(coveredvp, 0);
                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 = lockmgr(&mp->mnt_lock, LK_DRAIN | LK_INTERLOCK |
            ((flags & MNT_FORCE) ? 0 : LK_NOWAIT), MNT_MTX(mp));
        if (error) {
                MNT_ILOCK(mp);
                mp->mnt_kern_flag &= ~(MNTK_UNMOUNT | MNTK_NOINSMNTQ |
                    MNTK_UNMOUNTF);
                if (mp->mnt_kern_flag & MNTK_MWAIT)
                        wakeup(mp);
                MNT_IUNLOCK(mp);
                if (coveredvp)
                        VOP_UNLOCK(coveredvp, 0);
                return (error);
        }
        vn_start_write(NULL, &mp, V_WAIT);

        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 */
        if (mp->mnt_syncer != NULL)
                vrele(mp->mnt_syncer);
        /*
         * 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, td) == 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, td)) == 0) ||
            (flags & MNT_FORCE)) {
                error = VFS_UNMOUNT(mp, flags, td);
        }
        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, td) == 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 && mp->mnt_syncer == NULL) {
                        MNT_IUNLOCK(mp);
                        (void) 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_noasync == 0)
                        mp->mnt_kern_flag |= MNTK_ASYNC;
                lockmgr(&mp->mnt_lock, LK_RELEASE, NULL);
                if (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);
        lockmgr(&mp->mnt_lock, LK_RELEASE, NULL);
        vfs_mount_destroy(mp);
        return (0);
}

/*
 * ---------------------------------------------------------------------
 * Mounting of root filesystem
 *
 */

struct root_hold_token {
        const char                      *who;
        LIST_ENTRY(root_hold_token)     list;
};

static LIST_HEAD(, root_hold_token)     root_holds =
    LIST_HEAD_INITIALIZER(&root_holds);

static int root_mount_complete;

/*
 * Hold root mount.
 */
struct root_hold_token *
root_mount_hold(const char *identifier)
{
        struct root_hold_token *h;

        h = malloc(sizeof *h, M_DEVBUF, M_ZERO | M_WAITOK);
        h->who = identifier;
        mtx_lock(&mountlist_mtx);
        LIST_INSERT_HEAD(&root_holds, h, list);
        mtx_unlock(&mountlist_mtx);
        return (h);
}

/*
 * Release root mount.
 */
void
root_mount_rel(struct root_hold_token *h)
{

        mtx_lock(&mountlist_mtx);
        LIST_REMOVE(h, list);
        wakeup(&root_holds);
        mtx_unlock(&mountlist_mtx);
        free(h, M_DEVBUF);
}

/*
 * Wait for all subsystems to release root mount.
 */
static void
root_mount_prepare(void)
{
        struct root_hold_token *h;

        for (;;) {
                DROP_GIANT();
                g_waitidle();
                PICKUP_GIANT();
                mtx_lock(&mountlist_mtx);
                if (LIST_EMPTY(&root_holds)) {
                        mtx_unlock(&mountlist_mtx);
                        break;
                }
                printf("Root mount waiting for:");
                LIST_FOREACH(h, &root_holds, list)
                        printf(" %s", h->who);
                printf("\n");
                msleep(&root_holds, &mountlist_mtx, PZERO | PDROP, "roothold",
                    hz);
        }
}

/*
 * Root was mounted, share the good news.
 */
static void
root_mount_done(void)
{

        /*
         * Use a mutex to prevent the wakeup being missed and waiting for
         * an extra 1 second sleep.
         */
        mtx_lock(&mountlist_mtx);
        root_mount_complete = 1;
        wakeup(&root_mount_complete);
        mtx_unlock(&mountlist_mtx);
}

/*
 * Return true if root is already mounted.
 */
int
root_mounted(void)
{

        /* No mutex is acquired here because int stores are atomic. */
        return (root_mount_complete);
}

/*
 * Wait until root is mounted.
 */
void
root_mount_wait(void)
{

        /*
         * Panic on an obvious deadlock - the function can't be called from
         * a thread which is doing the whole SYSINIT stuff.
         */
        KASSERT(curthread->td_proc->p_pid != 0,
            ("root_mount_wait: cannot be called from the swapper thread"));
        mtx_lock(&mountlist_mtx);
        while (!root_mount_complete) {
                msleep(&root_mount_complete, &mountlist_mtx, PZERO, "rootwait",
                    hz);
        }
        mtx_unlock(&mountlist_mtx);
}

static void
set_rootvnode(struct thread *td)
{
        struct proc *p;

        if (VFS_ROOT(TAILQ_FIRST(&mountlist), LK_EXCLUSIVE, &rootvnode, td))
                panic("Cannot find root vnode");

        p = td->td_proc;
        FILEDESC_XLOCK(p->p_fd);

        if (p->p_fd->fd_cdir != NULL)
                vrele(p->p_fd->fd_cdir);
        p->p_fd->fd_cdir = rootvnode;
        VREF(rootvnode);

        if (p->p_fd->fd_rdir != NULL)
                vrele(p->p_fd->fd_rdir);
        p->p_fd->fd_rdir = rootvnode;
        VREF(rootvnode);

        FILEDESC_XUNLOCK(p->p_fd);

        VOP_UNLOCK(rootvnode, 0);

        EVENTHANDLER_INVOKE(mountroot);
}

/*
 * Mount /devfs as our root filesystem, but do not put it on the mountlist
 * yet.  Create a /dev -> / symlink so that absolute pathnames will lookup.
 */

static void
devfs_first(void)
{
        struct thread *td = curthread;
        struct vfsoptlist *opts;
        struct vfsconf *vfsp;
        struct mount *mp = NULL;
        int error;

        vfsp = vfs_byname("devfs");
        KASSERT(vfsp != NULL, ("Could not find devfs by name"));
        if (vfsp == NULL)
                return;

        mp = vfs_mount_alloc(NULLVP, vfsp, "/dev", td->td_ucred);

        error = VFS_MOUNT(mp, td);
        KASSERT(error == 0, ("VFS_MOUNT(devfs) failed %d", error));
        if (error)
                return;

        opts = malloc(sizeof(struct vfsoptlist), M_MOUNT, M_WAITOK);
        TAILQ_INIT(opts);
        mp->mnt_opt = opts;

        mtx_lock(&mountlist_mtx);
        TAILQ_INSERT_HEAD(&mountlist, mp, mnt_list);
        mtx_unlock(&mountlist_mtx);

        set_rootvnode(td);

        error = kern_symlink(td, "/", "dev", UIO_SYSSPACE);
        if (error)
                printf("kern_symlink /dev -> / returns %d\n", error);
}

/*
 * Surgically move our devfs to be mounted on /dev.
 */

static void
devfs_fixup(struct thread *td)
{
        struct nameidata nd;
        int error;
        struct vnode *vp, *dvp;
        struct mount *mp;

        /* Remove our devfs mount from the mountlist and purge the cache */
        mtx_lock(&mountlist_mtx);
        mp = TAILQ_FIRST(&mountlist);
        TAILQ_REMOVE(&mountlist, mp, mnt_list);
        mtx_unlock(&mountlist_mtx);
        cache_purgevfs(mp);

        VFS_ROOT(mp, LK_EXCLUSIVE, &dvp, td);
        VI_LOCK(dvp);
        dvp->v_iflag &= ~VI_MOUNT;
        VI_UNLOCK(dvp);
        dvp->v_mountedhere = NULL;

        /* Set up the real rootvnode, and purge the cache */
        TAILQ_FIRST(&mountlist)->mnt_vnodecovered = NULL;
        set_rootvnode(td);
        cache_purgevfs(rootvnode->v_mount);

        NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF, UIO_SYSSPACE, "/dev", td);
        error = namei(&nd);
        if (error) {
                printf("Lookup of /dev for devfs, error: %d\n", error);
                return;
        }
        NDFREE(&nd, NDF_ONLY_PNBUF);
        vp = nd.ni_vp;
        if (vp->v_type != VDIR) {
                vput(vp);
        }
        error = vinvalbuf(vp, V_SAVE, td, 0, 0);
        if (error) {
                vput(vp);
        }
        cache_purge(vp);
        mp->mnt_vnodecovered = vp;
        vp->v_mountedhere = mp;
        mtx_lock(&mountlist_mtx);
        TAILQ_INSERT_TAIL(&mountlist, mp, mnt_list);
        mtx_unlock(&mountlist_mtx);
        VOP_UNLOCK(vp, 0);
        vput(dvp);
        vfs_unbusy(mp);

        /* Unlink the no longer needed /dev/dev -> / symlink */
        kern_unlink(td, "/dev/dev", UIO_SYSSPACE);
}

/*
 * 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);
}

/*
 * Find and mount the root filesystem
 */
void
vfs_mountroot(void)
{
        char *cp;
        int error, i, asked = 0;

        root_mount_prepare();

        mount_zone = uma_zcreate("Mountpoints", sizeof(struct mount),
            NULL, NULL, mount_init, mount_fini,
            UMA_ALIGN_PTR, UMA_ZONE_NOFREE);
        devfs_first();

        /*
         * We are booted with instructions to prompt for the root filesystem.
         */
        if (boothowto & RB_ASKNAME) {
                if (!vfs_mountroot_ask())
                        goto mounted;
                asked = 1;
        }

        /*
         * The root filesystem information is compiled in, and we are
         * booted with instructions to use it.
         */
        if (ctrootdevname != NULL && (boothowto & RB_DFLTROOT)) {
                if (!vfs_mountroot_try(ctrootdevname))
                        goto mounted;
                ctrootdevname = NULL;
        }

        /*
         * We've been given the generic "use CDROM as root" flag.  This is
         * necessary because one media may be used in many different
         * devices, so we need to search for them.
         */
        if (boothowto & RB_CDROM) {
                for (i = 0; cdrom_rootdevnames[i] != NULL; i++) {
                        if (!vfs_mountroot_try(cdrom_rootdevnames[i]))
                                goto mounted;
                }
        }

        /*
         * Try to use the value read by the loader from /etc/fstab, or
         * supplied via some other means.  This is the preferred
         * mechanism.
         */
        cp = getenv("vfs.root.mountfrom");
        if (cp != NULL) {
                error = vfs_mountroot_try(cp);
                freeenv(cp);
                if (!error)
                        goto mounted;
        }

        /*
         * Try values that may have been computed by code during boot
         */
        if (!vfs_mountroot_try(rootdevnames[0]))
                goto mounted;
        if (!vfs_mountroot_try(rootdevnames[1]))
                goto mounted;

        /*
         * If we (still) have a compiled-in default, try it.
         */
        if (ctrootdevname != NULL)
                if (!vfs_mountroot_try(ctrootdevname))
                        goto mounted;
        /*
         * Everything so far has failed, prompt on the console if we haven't
         * already tried that.
         */
        if (!asked)
                if (!vfs_mountroot_ask())
                        goto mounted;

        panic("Root mount failed, startup aborted.");

mounted:
        root_mount_done();
}

/*
 * Mount (mountfrom) as the root filesystem.
 */
static int
vfs_mountroot_try(const char *mountfrom)
{
        struct mount    *mp;
        char            *vfsname, *path;
        time_t          timebase;
        int             error;
        char            patt[32];

        vfsname = NULL;
        path    = NULL;
        mp      = NULL;
        error   = EINVAL;

        if (mountfrom == NULL)
                return (error);         /* don't complain */
        printf("Trying to mount root from %s\n", mountfrom);

        /* parse vfs name and path */
        vfsname = malloc(MFSNAMELEN, M_MOUNT, M_WAITOK);
        path = malloc(MNAMELEN, M_MOUNT, M_WAITOK);
        vfsname[0] = path[0] = 0;
        sprintf(patt, "%%%d[a-z0-9]:%%%ds", MFSNAMELEN, MNAMELEN);
        if (sscanf(mountfrom, patt, vfsname, path) < 1)
                goto out;

        if (path[0] == '\0')
                strcpy(path, ROOTNAME);

        error = kernel_vmount(
            MNT_RDONLY | MNT_ROOTFS,
            "fstype", vfsname,
            "fspath", "/",
            "from", path,
            NULL);
        if (error == 0) {
                /*
                 * We mount devfs prior to mounting the / FS, so the first
                 * entry will typically be devfs.
                 */
                mp = TAILQ_FIRST(&mountlist);
                KASSERT(mp != NULL, ("%s: mountlist is empty", __func__));

                /*
                 * Iterate over all currently mounted file systems and use
                 * the time stamp found to check and/or initialize the RTC.
                 * Typically devfs has no time stamp and the only other FS
                 * is the actual / FS.
                 * Call inittodr() only once and pass it the largest of the
                 * timestamps we encounter.
                 */
                timebase = 0;
                do {
                        if (mp->mnt_time > timebase)
                                timebase = mp->mnt_time;
                        mp = TAILQ_NEXT(mp, mnt_list);
                } while (mp != NULL);
                inittodr(timebase);

                devfs_fixup(curthread);
        }
out:
        free(path, M_MOUNT);
        free(vfsname, M_MOUNT);
        return (error);
}

/*
 * ---------------------------------------------------------------------
 * Interactive root filesystem selection code.
 */

static int
vfs_mountroot_ask(void)
{
        char name[128];

        for(;;) {
                printf("\nManual root filesystem specification:\n");
                printf("  <fstype>:<device>  Mount <device> using filesystem <fstype>\n");
#if defined(__amd64__) || defined(__i386__) || defined(__ia64__)
                printf("                       eg. ufs:da0s1a\n");
#else
                printf("                       eg. ufs:/dev/da0a\n");
#endif
                printf("  ?                  List valid disk boot devices\n");
                printf("  <empty line>       Abort manual input\n");
                printf("\nmountroot> ");
                gets(name, sizeof(name), 1);
                if (name[0] == '\0')
                        return (1);
                if (name[0] == '?') {
                        printf("\nList of GEOM managed disk devices:\n  ");
                        g_dev_print();
                        continue;
                }
                if (!vfs_mountroot_try(name))
                        return (0);
        }
}

/*
 * ---------------------------------------------------------------------
 * 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);
                printf("%s\n", errmsg);
                ret = EINVAL;
        }
        if (ret != 0) {
                TAILQ_FOREACH(opt, opts, link) {
                        if (strcmp(opt->name, "errmsg") == 0) {
                                strncpy((char *)opt->value, errmsg, opt->len);
                        }
                }
        }
        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) {
                        if (len != NULL)
                                *len = opt->len;
                        if (buf != NULL)
                                *buf = opt->value;
                        return (0);
                }
        }
        return (ENOENT);
}

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

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

        i = 0;
        TAILQ_FOREACH(opt, opts, link) {
                if (strcmp(name, opt->name) == 0)
                        return (i);
                ++i;
        }
        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;
                if (((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, u_int *w, u_int val)
{
        struct vfsopt *opt;

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

/*
 * 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) {
                        if (len != opt->len)
                                return (EINVAL);
                        bcopy(opt->value, dest, opt->len);
                        return (0);
                }
        }
        return (ENOENT);
}

/*
 * This is a helper function for filesystems to traverse their
 * vnodes.  See MNT_VNODE_FOREACH() in sys/mount.h
 */

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 ((*mvp)->v_yield++ == 500) {
                MNT_IUNLOCK(mp);
                (*mvp)->v_yield = 0;
                uio_yield();
                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);
        }
        mp->mnt_holdcnt++;
        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;
                mp->mnt_holdcnt--;
                if (mp->mnt_holdcnt == 0 && mp->mnt_holdcntwaiters != 0)
                        wakeup(&mp->mnt_holdcnt);
                return (NULL);
        }
        mp->mnt_markercnt++;
        (*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;

        mp->mnt_markercnt--;
        mp->mnt_holdcnt--;
        if (mp->mnt_holdcnt == 0 && mp->mnt_holdcntwaiters != 0)
                wakeup(&mp->mnt_holdcnt);
}


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

        error = mp->mnt_op->vfs_statfs(mp, &mp->mnt_stat, td);
        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, int 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);
}